JP2010270220A - Manufacturing method for oily ink composition for inkjet printer and oily 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: The manufacturing method for the oily ink composition for the inkjet printer comprises dispersing at least a pigment (a) in which the Ca compound is not removed, a Ca compound soluble pigment dispersing agent (b) and/or a Ca compound soluble organic solvent (c) and a fixing resin (d) in an organic solvent (e) containing a compound (s) represented by formula (1). A pigment dispersing agent (f) other than (b) is used when the dispersing agent (b) is not used. <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 general, when printing is performed for a long time by operating an ink jet printer, or when printing is not performed for a long time, an insoluble precipitate is often deposited at the tip of the ink discharge nozzle of the printer. This significantly changes the direction in which the ink is ejected from the ink jet printer onto the substrate, the droplets of ink droplets, or the ejection speed of the ink, which adversely affects the image reproducibility of photographic prints and prevents stable printing.

  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 present inventors have used an unpurified Ca compound as a non-removed pigment and a method for producing an ink composition comprising the following specific components: However, the present inventors have found that an ink composition having long-term ejection stability in which dot missing or foreign matter does not appear in a printed matter can be obtained without causing filter clogging of an inkjet printer derived from a Ca compound.

（上記式中のＸ１はアルキル基を、Ｘ２は水素原子またはアルキル基を、ｎは１〜４の整数を表す。） The above object is achieved by the present invention described below. That is, the present invention comprises a pigment (a) from which at least the Ca compound has not been removed, a Ca compound-soluble pigment dispersant (b) and / or a Ca compound-soluble organic solvent (c), and a fixing resin (d). When dispersing in the organic solvent (e) containing the compound (s) represented by the following general formula (1), when the dispersant (b) is not used, a pigment dispersant (f) other than b is added. Provided is a method for producing an oil-based ink composition for an ink jet printer.

(X1 in the above formula represents an alkyl group, X2 represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 4.)

（上記式中のＸ３は炭素数が２〜７のアルキル基を、ｎは１〜７の整数を表す。）

（上記式中のＸ４は炭素数が１〜５のアルキル基を表す。）
前記Ｃａ化合物溶解性有機溶媒（ｃ）が、テトラエチレングリコールモノブチルエーテル、トリエチレングリコールモノブチルエーテル、ジエチレングリコールモノブチルエーテル、ジエチレングリコールイソブチルエーテル、エチレングリコールモノブチルエーテル、乳酸エチル、および乳酸ブチルから選ばれる少なくとも１種であり、前記Ｃａ化合物溶解性顔料分散剤（ｂ）およびＣａ化合物溶解性有機溶媒（ｃ）の各々の配合量が、インク組成物総量中において（ｂ）が０〜１０質量％および／または（ｃ）が０〜４０質量％を占める量（いずれもが同時に０にならない）であり、前記化合物（ｓ）が、エチレングリコールモノブチルエーテルアセテート、ジエチレングリコールモノブチルエーテルアセテート、およびプロピレングリコールモノメチルエーテルアセテートから選ばれる少なくとも１種であり、および前記顔料分散剤（ｆ）が、ウレタン系高分子分散剤、アクリル系高分子分散剤、およびリン酸エステル系高分子分散剤から選ばれる少なくとも１種であることが好ましい。 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, and the Ca compound-soluble pigment dispersant (b) is at least one selected from the group consisting of a polycaprolactone-based polymer dispersant, a fatty acid ester-based polymer dispersant, and a polyether-based polymer dispersant. And at least one selected from the compound (x) represented by the following general formula (2) and the compound (y) represented by the following general formula (3): Seeds,

(X3 in the above formula represents an alkyl group having 2 to 7 carbon atoms, and n represents an integer of 1 to 7)

(X4 in the above formula represents an alkyl group having 1 to 5 carbon atoms.)
The Ca compound-soluble organic solvent (c) 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. And the blending amount of each of the Ca compound-soluble pigment dispersant (b) and the Ca compound-soluble organic solvent (c) is such that (b) is 0 to 10% by mass and / or (c) in the total amount of the ink composition. ) Occupies 0 to 40% by mass (both of which do not simultaneously become 0), and the compound (s) contains ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, and propylene glycol. And the pigment dispersant (f) is selected from urethane polymer dispersants, acrylic polymer dispersants, and phosphate ester polymer dispersants. It is preferable that there is at least one.

  In addition, the present invention provides an oil-based ink composition for an ink jet printer, wherein the metal-calculated Ca metal content obtained by the method for producing an ink composition is 10 ppm to 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 includes a pigment (a) from which at least unpurified Ca compound has not been removed, a specific Ca compound-soluble pigment dispersant (b) and / or a Ca compound-soluble organic solvent (c), a fixing resin ( d) is dispersed in an organic solvent (e) containing the specific compound (s), and when the dispersant (b) is not used, a pigment dispersant (f) other than b is used. Is a method for producing an ink composition. That is, the above-described Ca compound is not removed from the pigment (a), and one or both of the specific Ca compound-soluble pigment dispersant (b) and the Ca compound-soluble organic solvent (c) are blended, Disperse together with the fixing resin (d) in a specific organic solvent (e). When the above dispersant (b) is not used, a pigment dispersant (f) other than the Ca compound-soluble organic solvent (c) and the dispersant (b) can be used in combination. Moreover, a pigment dispersant (f) can also be mix | blended with Ca compound soluble pigment dispersant (b).

  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 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.

  Further, the Ca compound-soluble pigment dispersant (b) used in the present invention is a pigment dispersant excellent in solubility and dispersibility in the pigment (a) from which the Ca compound has not been removed. The pigment dispersant (b) is preferably at least one selected from the group consisting of polycaprolactone polymer dispersants, fatty acid ester polymer dispersants, and polyether polymer dispersants. The above polymer dispersants can be used alone or in admixture of two or more.

  Examples of the polycaprolactone-based polymer dispersant include [Ajisper PB821], [Azisper PB822], [Azisper PB823], [Azisper PB824], [Azisper PB824], and Lubrizol, manufactured by Ajinomoto Fine Techno Co., Ltd. Examples include [SOLSPERSE28000], [SOLSPERSE24000], [SOLSPERSE32000], [SOLSPERSE33000], [SOLSPERSE39000], and the like.

  Examples of the fatty acid ester polymer dispersant include [Disperbyk108], [Disperbyk191], [DisperbykP104], [Anti-Terra-U] manufactured by BYK Chemie; [Asper PN411] manufactured by Ajinomoto Fine Techno Co., Ltd. [Ajisper PA111], [Azisper PB817]; [EFKA1501], [EFKA1502], [EFKA1503] manufactured by Efka Chemicals; [SOLPERSE18000], [SOLPERSE19000], [SOLPERSE21000] manufactured by Lubrizol; ) [Floren D90], [Floren TG-740W] and the like.

  Examples of the polyether polymer dispersant include, for example, [Disperbyk181], [Disperbyk183], [Disperbyk187], [Disperbyk190], [Disperbyk2070] manufactured by Big Chemie, and [Floren TG-650 manufactured by Kyoeisha Chemical Co., Ltd.]. ] Etc. are mentioned.

  The pigment dispersant (f) is a pigment dispersant other than the pigment dispersant (b). For example, a urethane polycaprolactone polymer dispersant, an organic acid polymer dispersant, an acrylic polymer Molecular dispersants, urethane-based polymer dispersants, phosphate ester-based polymer dispersants, other known polymer dispersants for inkjet print inks, and mixtures thereof, preferably urethane-based polymer dispersants, acrylic And at least one selected from a polymer dispersant and a phosphate ester polymer dispersant. The pigment dispersant (f) is obtained under trade names such as [Disperby 163] and [Disperby 2050] manufactured by Big Chemie, and [Disparon DA-325] manufactured by Enomoto Kasei Co., Ltd. and used in the present invention. Can do. When the pigment dispersant (f) is used alone without being combined with any of the Ca compound-soluble pigment dispersant (b) and the Ca compound-soluble organic solvent (c), the Ca compound is not used. This is not preferable because ejection defects are likely to occur in the ink jet printer nozzle derived from the removed pigment (a).

  Further, the Ca compound-soluble organic solvent (c) used in the present invention is excellent in solubility 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.

（上記式中のＸ３は炭素数が２〜７のアルキル基を、ｎは１〜７の整数を表す。）

（上記式中のＸ４は炭素数が１〜５のアルキル基を表す。） As the above-mentioned Ca compound-soluble organic solvent (c), any solvent can be used as long as it has excellent solubility in Ca compounds. Preferably, the compound is 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 in the above formula represents an alkyl group having 2 to 7 carbon atoms, and n represents an integer of 1 to 7)

(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 t-butyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol isobutyl ether, triethylene glycol monoethyl ether, and triethylene. Examples include glycol ethers such as 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 (c) is particularly preferably, 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 (c) 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 may be used alone or in admixture of two or more.

  The blending amount of each of the Ca compound-soluble pigment dispersant (b) and the Ca compound-soluble organic solvent (c) is preferably such that (b) is 0 to 10% by mass and / or (c) in the total amount of the ink composition. ) Occupies 0 to 40% by mass (both do not simultaneously become 0). That is, the Ca compound-soluble pigment dispersant (b) and the Ca compound-soluble organic solvent (c) may be used singly or in combination within the range of the blending amounts in the production method of the present invention. Can be used.

  The fixing resin (d) used in the present invention is a water-insoluble resin for fixing 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).

（上記式中のＸ１はアルキル基を、Ｘ２は水素原子またはアルキル基を、ｎは１〜４の整数を表す。） The organic solvent (e) used in the present invention contains the compound (s) represented by the following general formula (1), and preferably the compound (s) alone or in the total amount of the solvent. 10 mass% to 100 mass%.

(X1 in the above formula represents an alkyl group, X2 represents a hydrogen atom or an alkyl group, and n represents an integer of 1 to 4.)

  Examples of the compound (s) include glycol ether acetates derived from glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and propylene glycol. Said compound (s) can be used individually or in mixture of 2 or more types as appropriate. Specific examples of the compound (s) include, for example, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monopropyl ether acetate, diethylene glycol monobutyl ether acetate, triethylene glycol Ethylene glycol ethyl ether acetate, triethylene glycol monobutyl ether acetate and the like, preferably at least one selected from ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate.

  The organic solvent (e) can be used in combination with other known organic solvents for inkjet printing oil-based inks, using the compound (s) as an essential component.

  Examples of the other organic solvents include γ-lactones such as γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-caprolactone, and γ-laurolactone, and δ-lactones such as δ-valerolactone. Lactones such as ε-lactones such as ε-caprolactone; polyhydric alcohols such as ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, glycerin and polyglycerin; 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; ethylene glycol monomethyl ether, propylene glycol Polyol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether and other polyhydric alcohol derivatives; for other known inkjet printing oil-based inks The organic solvent of these is mentioned. The above organic solvents can be used alone or in a suitable mixture of two or more.

  In the present invention, if necessary, 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 added within a range that does not impede the purpose of the present invention. It can be used by adding.

[Method for producing ink composition]
The method for producing the ink composition of the present invention comprises the above-mentioned pigment (a) from which the Ca compound has not been removed, one of the Ca compound-soluble pigment dispersant (b) and the Ca compound-soluble organic solvent (c), or Both and the fixing resin (d) are appropriately blended in the organic solvent (e) containing the compound (s), and are kneaded and dispersed uniformly by a known method. In addition, when not using said Ca compound solubility pigment dispersant (b), it can manufacture using said pigment dispersants other than this dispersant (b). As the production method, for example, in the organic solvent (e), the above-described Ca compound-unremoved pigment (a), Ca compound-soluble pigment dispersant (b), and Ca compound-soluble organic solvent ( c) or the pigment dispersant (f) is added without using the Ca compound-soluble pigment dispersant (b), and the mixture is stirred uniformly at 1,000 rpm for 1 hour with a dissolver. Preliminarily disperse with a bead mill filled with zirconia beads (2 mm) until the particles of a) become 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 (d) is added, and the mixture is uniformly kneaded and dispersed while adding an appropriate amount of the organic solvent (e). The ink composition of the present invention was produced by adjusting to 18 mPa · s, preferably 6 to 15 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 1-14)
Pigment (a) from which Ca compound has not been removed, Ca compound-soluble pigment dispersant (b), Ca compound-soluble organic solvent (c), fixing resin (d), organic solvent (e), and pigment Using the dispersant (f), the respective components as shown in Table 1 and Table 2 were blended, and the viscosity was measured using the “AMVn” viscometer manufactured by Anton Paar Co., Ltd. according to the above [Ink composition production method]. Were uniformly kneaded and dispersed so as to be 7.5 to 11.0 mPa · s (25 ° C.) to produce ink compositions V1 to V14 of the present invention. 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 (d) and the organic solvent (e) is blended while the pigment dispersion is uniformly stirred at 1,500 rpm. It is manufactured.

(Comparative Examples 1-5)
In the same manner as in the method for producing the ink composition of the example, each component was blended as shown in Table 3 to produce ink compositions W1 to W5 of comparative examples.

Pigment (a) from which the above Ca compound has not been removed, Ca compound-soluble pigment dispersant (b), Ca compound-soluble organic solvent (c), fixing resin (d), organic solvent (e), and pigment dispersant (F) 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 pigment dispersant (b)
b1: Fatty acid ester polymer dispersing agent ([Disperbyk108] manufactured by Big Chemie)
b2: Fatty acid ester polymer dispersant ([Floren D90] manufactured by Kyoeisha Chemical Co., Ltd.)
b3: Polyether-based polymer dispersant ([Disperbyk187] manufactured by Big Chemie)
b4: Polyether-based polymer dispersant ([Disperbyk 2070] manufactured by Big Chemie)
b5: polycaprolactone polymer dispersant (Lubrisol [SOLSPERSE32000])
b6: Polycaprolactone-based polymer dispersant ([Ajisper PB821] manufactured by Ajinomoto Fine Techno Co., Ltd.)

-Ca compound soluble organic solvent (c)
c1: Tetraethylene glycol monobutyl ether c2: Triethylene glycol monobutyl ether c3: Butyl lactate

・ Fixing resin (d)
d1: Acrylic resin (Rohm & Haas [Paraloid B-60])
d2: Vinyl chloride vinyl acetate copolymer ([VYHH] manufactured by Dow Chemical Company)

Organic solvent (e)
(Compound (s))
s1: Ethylene glycol monobutyl ether acetate s2: Diethylene glycol monobutyl ether acetate s3: Propylene glycol monomethyl ether acetate (other organic solvent m)
m1: triethylene glycol monomethyl ether m2: tetraethylene glycol dimethyl ether m3: γ-butyrolactone m4: diethylene glycol diethyl ether m5: cyclohexanone m6: butyl acetate

・ Pigment dispersant (f)
f1: Urethane polymer dispersant ([Disperby 163] manufactured by Big Chemie)
f2: Acrylic polymer dispersant ([Disperby 2050] manufactured by Big Chemie)
f3: Phosphate ester polymer dispersant ([Disparon DA-325] manufactured by Enomoto Kasei 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 Tables 4 and 5.

[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.

  Based on the above evaluation results, the ink composition production method of the present invention can be used even if the raw material for producing the ink composition contains a Ca compound that causes ink ejection failure of an inkjet printer. It was proved that an ink composition excellent in ejection stability can be obtained without causing ink. 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 (10)

The pigment (a) from which at least the Ca compound has not been removed, the Ca compound-soluble pigment dispersant (b) and / or the Ca compound-soluble organic solvent (c), and the fixing resin (d) are represented by the following general formula (1). In the case where the dispersant (b) is not used, a pigment dispersant (f) other than b is used, which is dispersed in an organic solvent (e) containing the compound (s) represented by A method for producing an oil-based ink composition for an inkjet printer.

(X1 in the above formula represents an alkyl group, X2 represents a hydrogen atom or an alkyl group, and n represents an integer of 1 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.   2. The Ca compound-soluble pigment dispersant (b) is at least one selected from the group consisting of a polycaprolactone polymer dispersant, a fatty acid ester polymer dispersant, and a polyether polymer dispersant. The manufacturing method of the ink composition as described in above. The Ca compound-soluble organic solvent (c) 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 in the above formula represents an alkyl group having 2 to 7 carbon atoms, and n represents an integer of 1 to 7)

(X4 in the above formula represents an alkyl group having 1 to 5 carbon atoms.)   The Ca compound-soluble organic solvent (c) 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 5.   The blending amount of each of the Ca compound-soluble pigment dispersant (b) and the Ca compound-soluble organic solvent (c) is such that (b) is 0 to 10% by mass and / or (c) in the total amount of the ink composition. The method for producing an ink composition according to claim 1, wherein the amount is from 0 to 40% by mass (both are not simultaneously 0).   The method for producing an ink composition according to claim 1, wherein the compound (s) is at least one selected from ethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether acetate, and propylene glycol monomethyl ether acetate.   2. The ink composition according to claim 1, wherein the pigment dispersant (f) is at least one selected from a urethane polymer dispersant, an acrylic polymer dispersant, and a phosphate ester polymer dispersant. Production method.   An oil-based ink composition for an inkjet printer, wherein the metal metal-based Ca metal content obtained by the method for producing an ink composition according to any one of claims 1 to 9 is 10 ppm to 100 ppm.