JP2010270225A - Method for producing oil-based ink composition for ink jet printer and ink composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method for an ink composition not generating ink delivery failure of an inkjet printer caused by a Ca compound without removing/purifying the Ca compound in a manufacturing material of the ink composition and excellent in delivery stability, and an ink composition. <P>SOLUTION: In the manufacturing method of the oily ink composition for the inkjet printer, at least a pigment (a) in which the Ca compound is not removed, a Ca compound soluble organic solvent (b) and a fixing resin (c) are dispersed in an organic solvent (d) containing a compound (v) represented by formula (1) below, provided that the formula is X1-(O-C<SB>2</SB>H<SB>4</SB>)<SB>n</SB>-OX2 (1) wherein X1 and X2 represent a 1-4C alkyl group and may be the same or different, and n represents an integer of 2-4. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an oil-based ink composition for an ink jet printer (hereinafter, simply referred to as “ink composition producing method”), and more specifically, ejection stability of an ink jet printer derived from a Ca compound that does not cause ink ejection failure. Relates to a method for producing an excellent ink composition.

  In an inkjet printer for commercial and business use, a large amount of ink is used for a long time. Foreign matter contained in the ink may gradually clog a filter provided in the middle of the ink supply path, resulting in a state where ink cannot be supplied, which may lead to ejection failure.

  The above-mentioned insoluble precipitate is also affected by a precipitate composed of impurities derived from Ca compounds such as alkaline earth metals present in the raw material, particularly a poorly soluble salt of Ca, when producing an inkjet printer ink.

  Many impurities derived from the above Ca compound are present in the unpurified pigment which is a colorant of the ink jet printer ink. In addition, the above impurities include Ca salt of fatty acid such as Ca salt of stearic acid as a stabilizer of polymer resin that is a material constituting an ink container used in an ink jet printer, and fatty acid and free Ca compound. Ca salt of fatty acid produced by chemical reaction is eluted in the ink. Further, it is deposited in the ink flow path of the printer. The calcium stearate accumulates on a metal filter in front of the printer head nozzle, resulting in poor ink ejection.

  In order to improve the ejection failure due to the impurities, the production of a certain kind of ink for ink jet recording (Patent Document 1) is disclosed. In the manufacture of the ink disclosed in Patent Document 1, a metal compound such as a Ca compound in a colorant is removed and purified in advance using an ion exchange resin such as a Na-type chelate resin column, and after purification, the colorant is used. Ink compositions are manufactured.

  However, since the purification for removing these substances is time-consuming and expensive, the resulting ink is also expensive. Even if purified raw materials are used, it takes time to manage them. In addition, it is necessary to select and manage not only the raw materials but also the manufacturing process in which contamination of the above-mentioned impurities can be considered, the ink container used in the ink jet printer, the printer member such as the resin constituting the ink flow path, and the like.

  From the above, there is a demand for a method for producing an ink composition having excellent ejection stability without particularly refining the raw materials to be used.

Japanese Patent Publication No.2-2906

  Accordingly, an object of the present invention is to produce an ink composition having excellent ejection stability without causing ink ejection failure of an inkjet printer derived from a Ca compound without removing and purifying the Ca compound in the ink composition production raw material. Is to provide.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention have disclosed a method for producing an ink composition using an unpurified Ca compound by using an unremoved pigment and using the following specific components. It has been found that an ink composition having long-term ejection stability that does not cause dot omission or foreign matter in a printed matter can be obtained without causing filter clogging of an ink jet printer derived from the compound.

The above object is achieved by the present invention described below. That is, in the present invention, at least the pigment (a) from which the Ca compound has not been removed, the Ca compound-soluble organic solvent (b), and the fixing resin (c) are represented by the compound (v) And a method for producing an oil-based ink composition for an ink jet printer, wherein the oil-based ink composition is dispersed in an organic solvent (d).
_{X1- (O-C 2 H 4} ) n -OX2 (1)
(X1 and X2 in the above formula are alkyl groups having 1 to 4 carbon atoms, which may be the same or different, and n represents an integer of 2 to 4).

Moreover, in preferable embodiment of this invention, Ca metal content of the metal conversion of the said pigment (a) is 400 ppm-2000 ppm, The said pigment (a) is a green pigment, a cyan (blue) pigment, a magenta pigment, Or a yellow pigment, wherein the Ca compound-soluble organic solvent (b) is selected from the compound (x) represented by the following general formula (2) and the compound (y) represented by the following general formula (3) At least one.
_{X3- (OCH 2 CH 2) n} OH (2)
(X3 in the above formula represents an alkyl group having 2 to 7 carbon atoms, and n represents an integer of 1 to 7)
_{CH 3 -CH (OH) COOX4 (} 3)
(X4 in the above formula represents an alkyl group having 1 to 5 carbon atoms.)

  The Ca compound-soluble organic solvent (b) is at least one selected from tetraethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol isobutyl ether, ethylene glycol monobutyl ether, ethyl lactate, and butyl lactate. The amount of the Ca compound-soluble organic solvent (b) is 1-40% by mass in the total amount of the ink composition, and the compound (v) is diethylene glycol diethyl ether. Is preferred.

  Moreover, this invention provides the oil-based ink composition for inkjet printers characterized by metal content Ca metal content obtained by the manufacturing method of the said ink composition being 10-100 ppm.

  The method for producing an ink composition of the present invention is an ink composition having excellent ejection stability that does not cause ink ejection failure of an ink jet printer derived from the Ca compound even if the Ca compound is contained in the ink composition production raw material. It is effective to get. In particular, since it is not necessary to use a pigment obtained by removing and purifying the Ca compound derived from the pigment, it is possible to reduce the manufacturing cost because the time and cost associated with the purification can be reduced. Furthermore, the ink composition obtained by the present production method can eliminate the influence of Ca compounds that are considered to flow in from a polymer resin material that comes into contact with the ink composition such as an ink container and an ink flow path in an ink jet printer. There is an effect that special selection management of members is not required.

  Next, the present invention will be described in more detail with reference to preferred embodiments. The present invention provides an organic solvent containing a specific compound (v), at least a pigment (a) from which an unpurified Ca compound has not been removed, a Ca compound-soluble organic solvent (b), and a fixing resin (c). (D) A method for producing an ink composition dispersed in. That is, the specific Ca compound-soluble organic solvent (b) is blended with the pigment (a) from which the Ca compound has not been removed, and dispersed together with the fixing resin (c) in the specific organic solvent (d).

  The pigment (a) used in the present invention is a pigment in which the Ca compound mixed in the pigment is not removed or reduced by a conventional purification treatment such as an ion exchange resin method, but the Ca compound is not removed. As the pigment (a), any organic pigment, inorganic pigment, and carbon black that can be used for inkjet printing can be used.

  Examples of the pigment (a) include phthalocyanine series such as phthalocyanine blue and phthalocyanine green, pyranthrone series such as pyranthrone orange and pyranthrone red, permanent azo pigments such as permanent red 2B, pigment scarlet and lithol red, and benzidine. Insoluble azo pigments such as yellow, hansa yellow and toluidine red, quinophthalones such as quinophthalone yellow, thioindigo, benzimidazolone, anthraquinone, azo lake, dioxazine, diketopyrrolopyrrole, isoindolinone, quinacridone, Examples thereof include organic pigments such as isoindoline-based and quinoxalinedione-based; inorganic pigments such as titanium oxide, ultramarine blue, bitumen, dial, zinc white, and barium sulfate.

  The above-mentioned pigment is not particularly specified, but preferably a pigment whose metal equivalent Ca metal content is 400 ppm to 2000 ppm and is not purified can be used in the production method of the present invention. When said Ca metal content exceeds the said upper limit, it is not enough to eliminate the filter clogging of the inkjet printer derived from Ca compound of the ink composition obtained. On the other hand, those having a Ca metal content of less than the above lower limit can also be used in the present invention.

  Specific examples of the pigment include C.I. Pigment Blue 15: 3, C.I. Pigment Blue 15: 4, C.I. Pigment Blue 15: 6, C.I. Pigment green 7, C.I. Pigment Green 36, C.I. Pigment Green 58, C.I. Pigment Red 122, C.I. Pigment Yellow 74, C.I. Pigment Yellow 128, C.I. Pigment Yellow 138, C.I. Pigment yellow 139, C.I. Pigment Yellow 213, C.I. Pigment Yellow 150, C.I. Pigment Yellow 180, C.I. Pigment Violet 19, C.I. Pigment Orange 43, C.I. Pigment Orange 61, C.I. Pigment Orange 64, C.I. Pigment Orange 71, C.I. Examples include I Pigment Orange 73, carbon black and other non-purified products having no Ca compound removed.

  The pigment (a) used in the present invention preferably includes a green pigment, a cyan (blue) pigment, a magenta pigment, and a yellow pigment within the above-mentioned Ca metal content range. Examples of the pigment include unrefined C.I. having a Ca metal content of 1300 ppm in terms of metal. Pigment Green 36, unrefined C.I. with a Ca metal content of 550 ppm in terms of metal. Pigment Blue 15: 4, unrefined C.I. with a Ca metal content of 600 ppm in terms of metal. Pigment Red 122, unrefined C.I. with a Ca metal content of 450 ppm in terms of metal. I pigment yellow 180 etc. are mentioned. The metal-converted Ca metal content in the present invention is a value measured by the following Ca metal content measurement method.

(Ca metal content measurement method)
Measurement was performed by ICP-OES method (inductively coupled plasma optical emission spectrometry) using [Vista-Pro] manufactured by VARIAN.

  The Ca compound-soluble organic solvent (b) used in the present invention is an organic solvent that is excellent in solubility and dispersibility in the Ca compound in the pigment (a) from which the Ca compound has not been removed. As said Ca compound, it is Ca compound which precipitates easily in the ink flow path of inkjet printers, such as organic and inorganic Ca salt, for example.

As the above-mentioned Ca compound-soluble organic solvent (b), any one can be used as long as it has excellent solubility in Ca compounds, but preferably a compound represented by the following general formula (2) And at least one selected from (x) and a compound (y) represented by the following general formula (3).
_{X3- (OCH 2 CH 2) n} OH (2)
(X3 in the above formula represents an alkyl group having 2 to 7 carbon atoms, and n represents an integer of 1 to 7)
_{CH 3 -CH (OH) COOX4 (} 3)
(X4 in the above formula represents an alkyl group having 1 to 5 carbon atoms.)

  Examples of the compound (x) include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol mono t-butyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol isobutyl ether, triethylene glycol monoethyl ether, triethylene glycol Examples include glycol ethers such as ethylene glycol monobutyl ether and tetraethylene glycol monobutyl ether.

  Examples of the compound (y) include lactic acid esters such as methyl lactate, ethyl lactate, propyl lactate, and butyl lactate.

  The Ca compound-soluble organic solvent (b) is particularly preferably that in the general formula (2), X3 is an alkyl group having 4 carbon atoms, n is an integer of 1 to 4, and the general formula ( In 3), X4 is an alkyl group having 2 to 4 carbon atoms. The Ca compound-soluble organic solvent (b) is at least one selected from tetraethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol isobutyl ether, ethylene glycol monobutyl ether, ethyl lactate, and butyl lactate. These can be used alone or in admixture of two or more.

  The blending amount of the Ca compound-soluble organic solvent (b) is preferably an amount occupying 1 to 40% by mass in the total amount of the ink composition. If the amount of the Ca compound-soluble organic solvent (b) exceeds the upper limit, sufficient physical properties as an ink cannot be obtained. On the other hand, when the blending amount of the soluble organic solvent (b) is less than the lower limit, the effect of improving the ink ejection failure of the ink jet printer derived from the Ca compound in the obtained ink composition cannot be obtained.

  The fixing resin (c) used in the present invention is a water-insoluble resin that fixes the pigment (a) to a printing substrate, and is a known natural or synthetic resin that is dispersed and compatible in the resulting ink composition. Any resin that does not interfere with the object of the present invention can be used. Examples of the fixing resin include acrylic resins; vinyl chloride vinyl acetate copolymer resins, vinyl acetate resins such as polyvinyl acetate resins and butyral resins; polyester resins; polyamide resins; fibrin resins; epoxy resins; Examples include rosin derivatives such as rosin-modified phenolic resins; petroleum resins and the like. Said water-insoluble resin can be used individually or in mixture of 2 or more types as appropriate. Preferably, an acrylic resin alone or a mixture of an acrylic resin and a vinyl chloride vinyl acetate copolymer resin is used.

  Examples of the acrylic resin include a polymer made of (meth) acrylate ([(meth) acrylate] means both acrylate and methacrylate) and a copolymer thereof. Examples of the (meth) acrylate include alkyl (meth) acrylates such as methyl, ethyl, propyl, or butyl (meth) acrylate; hydroxymethyl, hydroxyethyl, hydroxypropyl, hydroxybutyl, hydroxypentyl (meth) acrylate, and the like. And hydroxyalkyl (meth) acrylates. Specific examples of the polymer and copolymer include, for example, methyl methacrylate polymer, methyl methacrylate / butyl methacrylate copolymer, methyl methacrylate / butyl acrylate / hydroxyethyl methacrylate / methacrylic acid copolymer, styrene / Copolymers of (meth) acrylate copolymers and other comonomers such as acrylic acid, methacrylic acid, styrene, acrylamide, vinyltoluene, glycidyl methacrylate, and hydroxyethyl acrylate. And mixtures thereof. As said acrylic resin, it can obtain with the brand name of [Paraloid B-60] from Rohm & Haas, and can use it by this invention.

  Examples of the vinyl chloride / vinyl acetate copolymer resins include vinyl chloride / vinyl acetate copolymers, vinyl chloride / vinyl acetate / maleic acid copolymers, vinyl chloride / vinyl acetate / vinyl alcohol copolymers, and chlorides. And vinyl / vinyl acetate / hydroxyalkyl acrylate copolymers and the like, and mixtures thereof. The above vinyl chloride / vinyl acetate copolymer resin can be obtained from Dow Chemical Company under the trade name [VYHH] and used in the present invention.

  When the acrylic resin (A) and the vinyl chloride / vinyl acetate copolymer resin (B) are used in combination, the blending ratio is preferably B / A = 10/100 to 70/100 (mass ratio).

The organic solvent (d) used in the present invention contains the compound (v) represented by the following general formula (1), and preferably the compound (v) alone or in the total amount of the solvent. 10 mass% to 100 mass%.
_{X1- (O-C 2 H 4} ) n -OX2 (1)
(X1 and X2 in the above formula are alkyl groups having 1 to 4 carbon atoms, which may be the same or different, and n represents an integer of 2 to 4).

  Examples of the compound (v) include diethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, diethylene glycol ethyl methyl ether, and triethylene glycol ethyl methyl. Ether, tetraethylene glycol ethyl methyl ether, diethylene glycol di-n-propyl ether, diethylene glycol di-iso-propyl ether, etc., preferably diethylene glycol diethyl ether.

  The organic solvent (d) includes the compound (v) as an essential component, and other known organic solvents for ink jet printing oil-based inks other than the Ca compound-soluble organic solvent (b). It can be used in combination within the range.

  Examples of other organic solvents used in combination with the compound (v) constituting the organic solvent (d) include γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprolactone, γ-laurolactone, and the like. Γ-lactones, δ-lactones such as δ-valerolactone, and lactones such as ε-lactones such as ε-caprolactone; ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin, polyglycerin and the like Lower alcohols such as methanol, ethanol, normal propanol and isopropanol; esters such as ethyl acetate, propyl acetate, butyl acetate and methyl 2-methoxypropionate; ketones such as methyl isobutyl ketone and cyclohexanone; Polyhydric alcohol derivatives such as lenglycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, ethylene glycol monobutyl ether acetate; In addition, the organic solvent for well-known inkjet printing oil-based inks etc. are mentioned. The above organic solvents can be used alone or in a suitable mixture of two or more.

  In the production method of the present invention, a pigment dispersant can be blended. As the dispersant, a known polymer dispersant for ink jet printing oil-based ink can be used. Examples of the pigment dispersant include urethane polycaprolactone polymer dispersant, organic acid polymer dispersant, acrylic polymer dispersant, urethane polymer dispersant, phosphate ester polymer dispersant, Fatty acid ester polymer dispersant, polycaprolactone polymer dispersant, polyether polymer dispersant, etc., preferably urethane polymer dispersant, acrylic polymer dispersant, phosphate ester polymer dispersant , At least one selected from polycaprolactone-based polymer dispersants, fatty acid ester-based polymer dispersants, and polyether-based polymer dispersants.

  In addition, in the production method of the present invention, additives such as an antistatic agent, a viscosity modifier, a leveling agent, a slip agent, an antifoaming agent, an antioxidant, and an ultraviolet absorber are obstructed as necessary. It can be used by adding in a range not present.

[Method for producing ink composition]
The method for producing the ink composition of the present invention includes the pigment (a) from which the Ca compound has not been removed, the Ca compound-soluble organic solvent (b), the fixing resin (c), and other pigment dispersants and additives. Is suitably blended in the organic solvent (d) containing the compound (v) and uniformly kneaded and dispersed by a known method. As the production method, for example, the above-mentioned Ca compound-unremoved pigment (a), a Ca compound-soluble organic solvent (b), and a pigment dispersant are added to the organic solvent (d). After stirring uniformly at 1,000 rpm for 1 hour with a dissolver, the particles are pre-dispersed in a bead mill filled with zirconia beads (2 mm) until the particles of the pigment (a) are 5 μm or less with a ground gauge. Further, the dispersion is performed with a nanomill filled with 0.3 mm zirconia beads until the average particle size of the pigment (a) is 250 nm or less to obtain a pigment dispersion. While the pigment dispersion is stirred at 1,500 rpm, the fixing resin (c) is added, and the mixture is uniformly kneaded and dispersed while adding an appropriate amount of the organic solvent (d). The ink composition of the present invention was produced by adjusting to 18 mPa · s, preferably 3 to 8 mPa · s. The above-mentioned viscosity is a value measured using an “AMVn” viscometer manufactured by Anton Paar. The particle diameter of the pigment is a value measured using “Microtrac UPA150” manufactured by Nikkiso Co., Ltd.

  The ink composition obtained by the above method for producing an ink composition has a metal equivalent Ca metal content of 10 ppm to 100 ppm. When the Ca metal content in the ink composition exceeds the above upper limit, it is not sufficient to eliminate the filter clogging of the ink jet printer derived from the Ca compound. On the other hand, even if Ca metal content is less than the said minimum, it can be used. The ink composition of the present invention can be effectively used as a piezo ink jet printer ink composition without causing filter clogging of a printer derived from a Ca compound.

  Next, the present invention will be described more specifically with reference to examples and comparative examples. In the text, “part” or “%” is based on mass unless otherwise specified. The present invention is not limited to the following.

(Examples 1-7)
Table 1 using the pigment (a) from which the Ca compound had not been removed, the Ca compound-soluble organic solvent (b), the fixing resin (c), the organic solvent (d), and the pigment dispersant (e). And each component is mix | blended as shown in Table 2, and a viscosity is 3.6-5.0 mPa * s (25 by the Anton Paar "AMVn" viscometer by said [Ink composition manufacturing method]. The ink compositions R1 to R7 of the present invention were produced by uniformly kneading and dispersing so that the temperature of the ink composition was 1 ° C. The method for producing the ink composition is as follows. First, a pigment dispersion is prepared, and then the remaining part of the fixing resin (c) and the organic solvent (d) is blended while the pigment dispersion is uniformly stirred at 1,500 rpm. It is manufactured.

(Comparative Examples 1-5)
In the examples, each component was blended as shown in Table 2 except that the Ca compound-soluble organic solvent (b) was not used, and the ink compositions S1 to S5 of the comparative examples were prepared in the same manner as in the production methods of the examples. Manufactured.

Each component used for manufacture of said Example and a comparative example is as follows.
-Pigment without removing Ca compound (a)
a1: Green pigment (C.I Pigment Green 36, Ca metal content in terms of metal 1300 ppm)
a2: Cyan pigment (C.I Pigment Blue 15: 4, Ca metal content 550 ppm in terms of metal)
a3: Magenta pigment (C.I Pigment Red 122, Ca metal content 600 ppm in terms of metal)
a4: Yellow pigment (CI Pigment Yellow 180, Ca metal content 450 ppm in terms of metal)

-Ca compound soluble organic solvent (b)
b1: Tetraethylene glycol monobutyl ether b2: Triethylene glycol monobutyl ether b3: Butyl lactate

・ Fixing resin (c)
Acrylic resin (Rohm & Haas [Paraloid B-60])

Organic solvent (d)
(Compound (v))
v1: Diethylene glycol diethyl ether v2: Tetraethylene glycol dimethyl ether (other organic solvents k)
k1: γ-butyrolactone k2: propylene glycol monomethyl ether acetate k3: ethylene glycol monobutyl ether acetate k4: cyclohexanone k5: butyl acetate

・ Pigment dispersant (e)
e1: Urethane polymer dispersant ([Disperby 163] manufactured by Big Chemie)
e2: Acrylic polymer dispersant ([Disperby 2050] manufactured by Big Chemie)
e3: Phosphate ester polymer dispersant ([Disparon DA-325] manufactured by Enomoto Kasei Co., Ltd.)
e4: Polycaprolactone polymer dispersant (Lubrisol [SOLSPERSE32000])
e5: Fatty acid ester polymer dispersant ([Floren D90] manufactured by Kyoeisha Chemical Co., Ltd.)
e6: polycaprolactone-based polymer dispersant ([Ajisper PB821] manufactured by Ajinomoto Fine Techno Co., Ltd.)

  Each ink composition obtained above was printed on a 200 μm polyvinyl chloride sheet (Lintec Corp., Bucal 900) using an inkjet printer (Seiko Epson Corp., MJ-8000C). Ink ejection stability and filter clogging were evaluated by the following measurement methods. Further, the metal metal equivalent Ca metal content in the ink was measured by the above (Ca metal content measurement method). The evaluation results are shown in Table 3.

[Discharge stability]
High-duty image patterns were printed for 20 consecutive days, and the occurrence of missing dots that could not be recovered by cleaning was evaluated. Visually observe the recovery of missing dots after cleaning from the printed sample.
Rating:
○: The missing dot is recovered by cleaning.
X: It does not recover even after cleaning.

[Filter clogging]
After performing the printing stability (ejection stability) evaluation, the filter part is disassembled, and the filter is observed for foreign matter clogging with a 1000 × metal microscope.
Rating:
○: No foreign matter is clogged in the metal filter.
X: The foreign matter clogging to a metal filter is recognized.

  From the above evaluation results, the method for producing an ink composition of the present invention causes an ink ejection failure of an ink jet printer in a raw material for producing the ink composition by using a specific Ca compound-soluble organic solvent. It has been proved that an ink composition excellent in ejection stability can be obtained without causing ink ejection failure even if it is produced by containing a Ca compound. Furthermore, the ink ejection defect considered to be derived from the Ca compound eluted from the polymer resin material constituting the ink container, the ink flow path and the like of the ink jet printer that comes into contact with the ink composition is also eliminated. On the other hand, in the comparative example, the discharge stability was poor even when the Ca compound of the same level as the example was contained.

  According to the present invention, the method for producing an ink composition of the present invention is an ink composition having excellent ejection stability without causing ink ejection failure even when a Ca compound is contained in the raw material for producing the ink composition. In particular, since it is not necessary to remove and purify the Ca compound derived from the pigment, the production cost can be reduced. Further, the Ca compound from the polymer resin material of the ink contact member in the ink jet printer can be reduced. Since the influence can be eliminated, it can be effectively used as an ink composition for a piezoelectric inkjet printer or the like.

Claims (8)

An organic solvent containing a compound (v) represented by the following general formula (1), wherein at least the pigment (a) from which the Ca compound has not been removed, the Ca compound-soluble organic solvent (b), and the fixing resin (c) (D) The manufacturing method of the oil-based ink composition for inkjet printers characterized by disperse | distributing in.
_{X1- (O-C 2 H 4} ) n -OX2 (1)
(X1 and X2 in the above formula are alkyl groups having 1 to 4 carbon atoms, which may be the same or different, and n represents an integer of 2 to 4).   2. The method for producing an ink composition according to claim 1, wherein the metal (Ca) content of the pigment (a) in terms of metal is 400 ppm to 2000 ppm.   The method for producing an ink composition according to claim 1 or 2, wherein the pigment (a) is a green pigment, a cyan (blue) pigment, a magenta pigment, or a yellow pigment. The Ca compound-soluble organic solvent (b) is at least one selected from a compound (x) represented by the following general formula (2) and a compound (y) represented by the following general formula (3). Item 2. A method for producing an ink composition according to Item 1.
_{X3- (OCH 2 CH 2) n} OH (2)
(X3 in the above formula represents an alkyl group having 2 to 7 carbon atoms, and n represents an integer of 1 to 7)
_{CH 3 -CH (OH) COOX4 (} 3)
(X4 in the above formula represents an alkyl group having 1 to 5 carbon atoms.)   The Ca compound-soluble organic solvent (b) is at least one selected from tetraethylene glycol monobutyl ether, triethylene glycol monobutyl ether, diethylene glycol monobutyl ether, diethylene glycol isobutyl ether, ethylene glycol monobutyl ether, ethyl lactate, and butyl lactate. A method for producing an ink composition according to claim 4.   2. The method for producing an ink composition according to claim 1, wherein the compounding amount of the Ca compound-soluble organic solvent (b) occupies 1 to 40% by mass in the total amount of the ink composition.   The method for producing an ink composition according to claim 1, wherein the compound (v) is diethylene glycol diethyl ether.   An oil-based ink composition for an ink jet printer, wherein the Ca metal content in terms of metal obtained by the method for producing an ink composition according to any one of claims 1 to 7 is 10 to 100 ppm.