JP2016020455A - Inkjet ink composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink composition excellent in antiseptic performance and having low temperature stability.SOLUTION: There is provided an inkjet ink composition containing at least an antiseptic agent having a logP value of water/octanol distribution coefficient of 2.0 or more, a nonionic surfactant having HLB by a Griffin method of less than 6, a water soluble organic solvent having logP value of the water/octanol distribution coefficient of 0 to 2.0, water and the content of the water is 55 mass% or more and the water soluble organic solvent contains alkyl polyol or glycol alkyl ether.SELECTED DRAWING: None

Description

  The present invention relates to an inkjet ink composition.

  The ink jet recording method is capable of recording high-definition images with a relatively simple device, and has been rapidly developed in various fields. Among them, various studies have been made on the antiseptic properties of the ink composition. For example, in Patent Document 1, the concentration of 1,2-benzisothiazolin-3-one having antiseptic and antibacterial action is as high as possible, the handling safety is high, and it is stable for long-term low-temperature storage, In addition, for the purpose of providing an aqueous solution that is difficult to crystallize during subdivision and preparation, 1,2-benzoisothiazolin-3-one system in a mixed solvent containing water and a hydroxyl group-containing organic solvent and / or a ketone solvent An antiseptic / antibacterial agent composition containing a compound, further comprising an organic amine compound and a metal hydroxide is disclosed.

JP 2011-46624 A

  However, the antiseptic performance of the ink composition is required before recording and is an unnecessary function after recording. In addition, preservatives may cause allergic contact dermatitis if they bleed out to the recording surface and contact the skin for a long time, or may evaporate from the surface and worsen the indoor environment. Since the wastewater treatment may be difficult when the composition is discarded, it is desired that the amount used is small while having sufficient antiseptic performance. On the other hand, if the usage-amount of antiseptic component is reduced, antiseptic performance will be impaired.

  Further, as described in the cited document 1, generally, the preservative component has low solubility in water, and the ink composition may be transported in the form of a cartridge, for example, at −20 ° C. There is a risk of insolubilization and precipitation during low-temperature storage, resulting in a decrease in low-temperature stability. Thus, the improvement in antiseptic performance and low-temperature stability is in a trade-off relationship.

  SUMMARY An advantage of some aspects of the invention is to provide an ink composition that is excellent in antiseptic performance and has low-temperature stability.

  The present inventors diligently studied to solve the above problems. As a result, the present invention was completed by finding that an ink composition having a predetermined composition can solve the above problems.

That is, the present invention is as follows.
[1]
A preservative having a log P value of water / octanol partition coefficient of 2.0 or more;
A nonionic surfactant having a Griffin method HLB of less than 6,
A water-soluble organic solvent having a log P value of water / octanol partition coefficient of 0 to 2.0;
Including at least water
The water content is 55% by mass or more,
The water-soluble organic solvent comprises an alkyl polyol or glycol alkyl ether;
Inkjet ink composition.
[2]
The inkjet ink composition according to [1], wherein the preservative has a standard boiling point of 300 ° C. or higher.
[3]
The content of the preservative is 10 ppm or more and 500 ppm or less,
The inkjet ink composition according to [1] or [2], wherein the total content of the water-soluble organic solvent and the nonionic surfactant is 0.50% by mass or more and 15% by mass or less.
[4]
The alkyl group of the alkyl polyol has 5 to 8 carbon atoms,
The inkjet ink composition according to any one of [1] to [3], wherein the alkyl group of the glycol alkyl ether has 2 to 6 carbon atoms.
[5]
The inkjet ink composition according to any one of [1] to [4], wherein a total content of components other than the moisture and the solid content is 10% by mass or more and 40% by mass or less.
[6]
The inkjet ink composition according to any one of [1] to [5], wherein the preservative contains at least one selected from the group consisting of isothiazoline compounds and haloalkynyl compounds.
[7]
Any one of [1] to [6] above, wherein the nonionic surfactant contains at least one selected from the group consisting of a nonionic acetylene glycol surfactant and a silicone surfactant. The ink-jet ink composition described in 1.
[8]
The preservative is selected from the group consisting of 2-butyl-1,2-benzisothiazolin-3-one, 3-iodo-2-propynylbutylcarbamate, and 2-n-octyl-4-isothiazolin-3-one. The inkjet ink composition according to any one of [1] to [7] above, comprising at least one or more of the above.
[9]
The inkjet ink composition according to any one of [1] to [8], which is attached to a non-absorbent film or a low-absorbent coated paper.

  Hereinafter, the embodiment of the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to this, and various modifications are possible without departing from the scope of the present invention. It is.

[Inkjet ink composition]
The inkjet ink composition of the present embodiment (hereinafter also referred to as “ink composition”) includes a preservative having a log P value of water / octanol distribution coefficient of 2.0 or more, and a nonion having an HLB of less than 6 in the Griffin method. A surfactant, a water-soluble organic solvent having a water / octanol partition coefficient log P value of 0 to 2.0, and water, and the water content is 55% by mass or more, The water-soluble organic solvent contains an alkyl polyol or glycol alkyl ether.

〔Preservative〕
The log P value of the water / octanol partition coefficient of the preservative is 2.0 or more, preferably 2.2 or more, more preferably 2.4 or more. When the log P value is 2.0 or more, the preservative contained in the recorded matter is less likely to bleed out on the recording surface, and the preservative is easily agglomerated and separated during wastewater treatment, so that the aquatic environment is reduced. Difficult to contaminate. The log P value of the water / octanol partition coefficient of the preservative is preferably 6.0 or less, more preferably 5.5 or less, and further preferably 5.0 or less. When the log P value is 6.0 or less, the low-temperature stability tends to be further improved. “LogP” refers to a value defined by OECD Test Guideline 107. In addition, logP can be measured by the method described in the examples. A higher log P value indicates higher hydrophobicity, and a lower log P value indicates higher hydrophilicity.

  Although it does not specifically limit as an antiseptic | preservative, For example, an isothiazoline compound, a halo alkynyl compound, a bronopol, chlorocresol etc. are mentioned. Among these, the antiseptic performance tends to be further improved by including at least one selected from the group consisting of isothiazoline compounds and haloalkynyl compounds as preservatives.

  The isothiazoline compound is not particularly limited. For example, 2-butyl-1,2-benzisothiazoline-3-one (boiling point 333 ° C., log P value 3.5), 2-n-octyl-4-isothiazoline-3- ON (boiling point 305 ° C., log P value 2.5), dichlorooctyl isothiazolinone (boiling point 323 ° C., log P value 4.3).

  The haloalkynyl compound is not particularly limited. For example, 3-iodo-2-propynylbutylcarbamate (boiling point 322 ° C., log P value 4.4), N, N′-hexamethylenebis (carbamic acid 3-iodo-2) -Propynyl) (boiling point 572 ° C., log P value 5.1), N-octylcarbamic acid 4-iodo-2-butynyl (boiling point 400 ° C., log P value 5.6).

  Among these, the group consisting of 2-butyl-1,2-benzisothiazolin-3-one, 3-iodo-2-propynylbutylcarbamate, and 2-n-octyl-4-isothiazolin-3-one as preservatives By including at least one or more selected more, the antiseptic performance tends to be further improved.

  The content of the preservative is preferably 1.0 ppm or more, more preferably 5.0 ppm or more, and further preferably 10 ppm or more with respect to the total amount of the ink composition. When the content of the preservative is 1.0 ppm or more, sufficient antiseptic performance can be imparted in combination with a nonionic surfactant and a water-soluble organic solvent. Further, the content of the preservative is preferably 700 ppm or less, more preferably 600 ppm or less, and further preferably 500 ppm or less with respect to the total amount of the ink composition. When the content of the preservative is 500 ppm or less, the low temperature stability tends to be further improved. Further, if the content of the preservative is reduced, the amount of the preservative contained in the recorded material is reduced and the amount of bleeding out on the recording surface can be reduced. Furthermore, since the amount of preservatives that must be separated during wastewater treatment is reduced, the aquatic environment tends not to be polluted.

  The standard boiling point of the preservative is preferably 280 ° C. or higher, more preferably 290 ° C. or higher, and further preferably 300 ° C. or higher. When the standard boiling point of the preservative is 280 ° C. or higher, the preservative contained in the recorded matter is less likely to evaporate from the recording surface.

  A preservative may be used individually by 1 type, and may be used in mixture of 2 or more types.

[Nonionic surfactant]
The HLB of the nonionic surfactant Griffin method is less than 6.0, preferably 5.5 or less, more preferably 5.0 or less. When the HLB is less than 6.0, the compatibility with the above preservative is high, and the low temperature stability of the preservative can be increased. In particular, an ink composition that is desired to have a relatively low viscosity from the viewpoint of ejection stability has a relatively high water content and tends to decrease the stability of the hydrophobic component, but has the nonionic surfactant. Therefore, even in such a case, the dissolution stability is improved. The HLB of the nonionic surfactant Griffin method is preferably 2.0 or more, more preferably 2.5 or more, and further preferably 3.0 or more. When the HLB is 2.0 or more, the dissolution stability of the nonionic surfactant itself can be maintained. In addition, the HLB value in this specification is defined by the Griffin method.

  The nonionic surfactant is not particularly limited, and examples thereof include a nonionic acetylene glycol surfactant and a silicone surfactant. Among these, by containing at least one or more selected from the group consisting of nonionic acetylene glycol surfactants and silicone surfactants as nonionic surfactants, antiseptics can be obtained by compatibility with preservatives. The low temperature stability of the agent can be increased. In particular, an ink composition that is desired to have a relatively low viscosity from the viewpoint of ejection stability has a relatively high water content and tends to decrease the stability of the hydrophobic component, but has the nonionic surfactant. Therefore, even in such a case, the dissolution stability tends to be improved.

  The nonionic acetylene glycol surfactant is not particularly limited. For example, Surfinol 61 (HLB6), Surfinol 104S (HLB4), Surfinol 104PG50 (HLB4), Surfinol 420 (HLB4), Surfinol 82 (HLB4) and Surfynol DF110D (HLB3).

  Although it does not specifically limit as a silicone type surfactant, For example, Shin-Etsu Chemical Co., Ltd. KF-6015 (HLB4.5), KF-6016 (HLB4.5), KF-6017 (HLB4.5), KF -6028 (HLB4).

  The content of the nonionic surfactant is preferably 0.010% by mass or more, more preferably 0.050% by mass or more, and further preferably 0.10% by mass with respect to the total amount of the ink composition. That's it. When the content of the nonionic surfactant is 0.010% by mass or more, low-temperature stability due to compatibility with the preservative can be increased. Further, the content of the nonionic surfactant is preferably 1.5% by mass or less, more preferably 1.0% by mass or less, and further preferably 0.75% with respect to the total amount of the ink composition. It is below mass%. When the content of the nonionic surfactant is 1.5% by mass or less, the dissolution stability of the nonionic surfactant itself can be maintained.

  A nonionic surfactant may be used individually by 1 type, and may be used in mixture of 2 or more types.

[Surface tension modifier]
The ink composition may contain a surface tension adjusting agent as required. The surface tension adjusting agent adjusts the wettability with respect to the recording medium. For example, in the case of a base material in which ink is likely to permeate, such as a cotton cloth, addition is unnecessary. On the other hand, in the case of a substrate that does not have an ink absorption layer and is difficult to wet with water-based ink, such as a plastic film, a surface tension adjusting agent is added to reduce the surface tension of the ink to about 20 mN / m.

  Although it does not specifically limit as a surface tension modifier, For example, lower alcohols, such as ethanol, a propanol, butanol; Butylene glycol, 1, 3- pentanediol, 2-ethyl- 1, 3- propanediol, 1, 6-, Diols such as hexanediol, glycol monoethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and propylene glycol monomethyl ether; an HLB value from the nonionic surfactant described above High acetylene glycol surfactants; and silicone surfactants.

  Although it does not specifically limit as an acetylene glycol type surfactant, For example, Olfin E1004, E1010, E1020, PD-001, PD-002W, PD-004, PD-005, EXP. 4200, EXP. 4123, EXP. 4300 (all are trade names manufactured by Nissin Chemical Industry Co., Ltd.), Surfinol 440, 465, 485, CT111, CT121, TG, GA, Dinol 604, 607 (all of these are Air Products Japan, Inc.) trade name), acetylenol E40, E60, E100 (all are trade names made by Kawaken Fine Chemical Co., Ltd.). One acetylene glycol surfactant may be used alone, or two or more acetylene glycol surfactants may be used in combination.

  Examples of silicone surfactants include polysiloxane compounds and polyether-modified organosiloxanes. Although it does not specifically limit as a commercial item of a silicone type surfactant, Specifically, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-347, BYK -348, BYK-349 (above trade name, manufactured by Big Chemie Japan Co., Ltd.), KF-351A, KF-352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640 KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF-6012 (above trade name, manufactured by Shin-Etsu Chemical Co., Ltd.), Silface SAG002, 005, 503A, 008 (above Trade name, manufactured by Nissin Chemical Industry Co., Ltd.).

  The content of the surface tension adjusting agent is preferably 0.10% by mass to 2.5% by mass, and more preferably 0.25% by mass to 1.5% by mass with respect to the total amount of the ink composition. More preferably, it is 0.50 mass% or more and 1.25 mass% or less. When the content of the surface tension adjusting agent is within the above range, the wettability of the ink with respect to the recording medium can be appropriately adjusted.

(Water-soluble organic solvent)
The log P value of the water / octanol partition coefficient of the water-soluble organic solvent is 0 or more and 2.0 or less, preferably 0 or more and 2.0 or less, more preferably 0 or more and 1.5 or less. When the log P value is within the above range, the compatibility between the nonionic surfactant and the water-soluble organic solution component in the ink composition and the solubility of the nonionic surfactant are further improved, and the low temperature stability is improved. More improved. Furthermore, since the water-soluble organic solvent itself has a high bacteriostatic property, the antibacterial and antiseptic properties are further improved, and the amount of the preservative used can be reduced.

  The water-soluble organic solvent includes alkyl polyol or glycol alkyl ether.

  The number of carbon atoms in the alkyl group of the alkyl polyol is preferably 5 or more and 8 or less. When the carbon number of the alkyl group of the alkyl polyol is 5 or more, the compatibility with the preservative increases, and the low temperature stability of the preservative tends to be further improved. Further, when the alkyl group of the alkyl polyol has 8 or less carbon atoms, the solubility in ink tends to be further improved.

  Examples of the alkyl polyol include, but are not limited to, for example, 1,2-pentanediol (log P value 0.01, alkyl group carbon number 5), 2-methyl-2-ethyl-1,3-propanediol (log P value). 0.2, carbon number of alkyl group 6), 1,3-hexanediol (log P value 0.3, alkyl group carbon number 6), 2,3-hexanediol (log P value 0.4, carbon of alkyl group) 6), 1,2-hexanediol (log P value 0.5, alkyl group carbon number 6), 1,3-heptanediol (log P value 0.5, alkyl group carbon number 7), 1,7- Heptanediol (log P value 0.8, alkyl group carbon number 7), 1,2-heptanediol (log P value 1, alkyl group carbon number 7), 1,8-octanediol (log P value 1, alkyl group) 8 carbon atoms Le group), 1,2-octanediol (logP value 1.5, 8 carbon atoms in the alkyl group).

  The number of carbon atoms of the alkyl group of the glycol alkyl ether is preferably 2 or more and 6 or less. When the number of carbon atoms of the alkyl group of the glycol alkyl ether is 2 or more, compatibility with the preservative increases and the low-temperature stability of the preservative tends to be further improved. Moreover, when the carbon number of the alkyl group of the glycol alkyl ether is 6 or less, the solubility in ink tends to be further improved.

  The glycol alkyl ether is not particularly limited. For example, ethylene glycol monopropyl ether (log P value 0.05, alkyl group carbon number 3), tetraethylene glycol monobutyl ether (log P value 0.1, alkyl group carbon number). 4), propylene glycol monoethyl ether (log P value 0.3, alkyl group carbon number 2), triethylene glycol monobutyl ether (log P value 0.3, alkyl group carbon number 4), diethylene glycol monobutyl ether (log P value 0) .6, alkyl group carbon number 4), propylene glycol monobutyl ether (log P value 1.1, alkyl group carbon number 4), dipropylene glycol monobutyl ether (log P value 1.5, alkyl group carbon number 4), Diethylene glycol Monohexyl ether (logP value 1.5, to 6 carbon atoms alkyl group).

  The content of the water-soluble organic solvent is preferably 0.10% by mass or more, more preferably 0.25% by mass or more, and further preferably 0.50% by mass or more with respect to the total amount of the ink composition. It is. When the content of the water-soluble organic solvent is 0.10% by mass or more, the compatibility between the nonionic surfactant and the solution component in the ink composition, the solubility of the nonionic surfactant, and the preservative The solubility of the preservative tends to be further improved, and the low temperature stability of the preservative tends to be further improved. Furthermore, since the water-soluble organic solvent itself has a high bacteriostatic property, the antibacterial and antiseptic properties of the ink are further improved, and the amount of the preservative used tends to be reduced. Further, the content of the water-soluble organic solvent is preferably 17.5% by mass or less, more preferably 15% by mass or less, and further preferably 12.5% by mass or less with respect to the total amount of the ink composition. It is. When the content of the water-soluble organic solvent is 17.5% by mass or less, the viscosity of the ink can be adjusted to be lower.

  A water-soluble organic solvent may be used individually by 1 type, and may be used in mixture of 2 or more types.

  The total content of the water-soluble organic solvent and the nonionic surfactant is preferably 0.10% by mass or more, more preferably 0.25% by mass or more, and further preferably 0.50% by mass or more. . When the total content of the water-soluble organic solvent and the nonionic surfactant is 0.10% by mass or more, the solubility of the preservative tends to be further improved, and the low-temperature stability of the preservative tends to be further improved. Further, the total content of the water-soluble organic solvent and the nonionic surfactant is preferably 20% by mass or less, more preferably 17.5% by mass or less, and still more preferably with respect to the total amount of the ink composition. Is 15% by mass or less. When the total content of the solvent and the nonionic surfactant is 20% by mass or less, the viscosity of the ink can be adjusted to be lower.

〔water〕
Examples of water include water from which ionic impurities have been removed as much as possible, such as pure water such as ion exchange water, ultrafiltration water, reverse osmosis water, and distilled water, and ultrapure water. In addition, when water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is used, generation of mold and bacteria can be prevented when the ink is stored for a long period of time. This tends to improve the storage stability.

  The water content is 55% by mass or more, preferably 60% by mass or more, and more preferably 65% by mass or more based on the total amount of the ink composition. When the water content is 55% by mass or more, the ink composition has a relatively low viscosity, and as the water content increases, the stability of the hydrophobic component tends to decrease. By having the activator, the low temperature stability is improved even in such a case. Further, the content of water is preferably 90% by mass or less, more preferably 85% by mass or less, and further preferably 80% by mass or less with respect to the total amount of the ink composition. When the water content is 90% by mass or less, the low-temperature stability tends to be further improved.

  The total content of components other than (moisture and solid content) is preferably 5.0% by mass or more, more preferably 10% by mass or more, and further preferably 15% by mass with respect to the total amount of the ink composition. % Or more. When the total content of components other than moisture and solid content is 5.0% by mass or more, the low-temperature stability of the preservative tends to be further improved. The total content of components other than moisture and solid content is preferably 45% by mass or less, more preferably 40% by mass or less, and still more preferably 35% by mass or less with respect to the total amount of the ink composition. It is. When the total content of components other than moisture and solid content is 45% by mass or less, the viscosity of the ink can be adjusted to be lower. The total content of components other than water and solid content can be calculated by subtracting the water content and the solid content from the total amount of the ink composition. Here, moisture refers to the amount of water, and solid content refers to solid components such as color materials and resins.

[Color material]
The ink composition may further include a color material such as a pigment or a dye.

  Examples of inorganic pigments include, but are not limited to, carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, iron oxide, titanium oxide, zinc oxide, and silica. It is done.

  Examples of organic pigments include, but are not limited to, quinacridone pigments, quinacridone quinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, ansanthrone pigments, indanthrone pigments, flavanthrone pigments, Examples include perylene pigments, diketopyrrolopyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments. It is done.

  The pigment may be used by dispersing the pigment using a water-soluble resin, a water-dispersible resin or a surfactant, or the surface of the pigment is oxidized with ozone, hypochlorous acid, fuming sulfuric acid, or the like. It may be sulfonated and used as a self-dispersing pigment.

  A pigment may be used individually by 1 type, or may use 2 or more types together.

  Although it does not specifically limit as dye, For example, an acidic dye, a direct dye, a reactive dye, and a basic dye are mentioned. More specifically, C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52, 80, 82, 249, 254, 289, C.I. I. Acid Blue 9, 45, 249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1,12,24,33,50,55,58,86,132,142,144,173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Directed Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Directed Blue 2, 3, 8, 10, 12, 31, 35, 63, 116, 130, 149, 199, 230, 231, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive black 3, 4, 35 etc. are mentioned.

  A dye may be used individually by 1 type and may use 2 or more types together. Furthermore, you may mix and use dye and a pigment.

  The content of the coloring material can be appropriately adjusted according to the use, but is preferably 0.10 to 20.0% by mass, more preferably 0.20 to 15.0% by mass, and further preferably. Is 1.0-10.0 mass%.

[Humectant]
The ink composition may further include a humectant (humectant). Any humectant can be used without particular limitation as long as it is generally used in an inkjet ink composition. The boiling point of the humectant is preferably 180 ° C. or higher, more preferably 200 ° C. or higher. When the boiling point is within the above range, good water retention and wettability can be imparted to the ink composition.

  Although it does not specifically limit as a moisturizer, For example, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentamethylene glycol, trimethylene glycol, 2-butene-1,4-diol, 2-ethyl- 1,3-hexanediol, 2-methyl-2,4-pentanediol, tripropylene glycol, polyethylene glycol having a number average molecular weight of 2000 or less, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, glycerin, mesoerythritol, Polyols such as trimethylolpropane and pentaerythritol, lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone and ε-caprolactam, urea, thiourea and ethyl Urea, urea derivatives such as 1,3-dimethylimidazolidinone, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol (sorbitol), maltose, cellobiose, lactose, sucrose, trehalose, maltotri Examples thereof include monosaccharides such as aose, disaccharides, oligosaccharides and polysaccharides, derivatives of these saccharides, glycine, and trimethylglycine betaines.

  A moisturizer may be used individually by 1 type, and may be used in mixture of 2 or more types.

  Although content of a moisturizing agent can be suitably adjusted according to a use, Preferably it is 2.5-30 mass%, More preferably, it is 5.0-25 mass%, More preferably, it is 10-20. % By mass.

[PH adjuster]
The ink composition may further include a pH adjuster. Although it does not specifically limit as a pH adjuster, For example, inorganic acids (for example, sulfuric acid, hydrochloric acid, nitric acid, etc.), inorganic bases (for example, lithium hydroxide, sodium hydroxide, potassium hydroxide, ammonia, etc.), organic bases ( Triethanolamine, diethanolamine, monoethanolamine, tripropanolamine), organic acids (for example, adipic acid, citric acid, succinic acid, etc.) and the like.

  A pH adjuster may be used individually by 1 type, and may be used in mixture of 2 or more types.

  The content of the pH adjusting agent can be appropriately adjusted according to the use, but is preferably adjusted to an ink pH of 6.5 to 10.5, more preferably an ink pH of 7.0 to 9.5. Can be added.

〔resin〕
The ink composition may further include a resin. The resin is added mainly when the colorant is a pigment, and is used for improving the adhesion of the pigment to the recording medium.
The resin is selected from water-soluble resins or water-dispersed resin emulsions, for example, acrylic polymers, polyacrylic acid esters and copolymers thereof, polymethacrylic acid esters and copolymers thereof, styrene acrylate copolymers, Styrene methacrylate copolymer, polyacrylamide, polyacrylic acid or polymethacrylic acid and polyolefin copolymer, vinyl acetate / vinyl alcohol polymer, vinyl acetate / olefin copolymer, polyvinyl chloride and its copolymer A polymer, polyvinyl pyrrolidone, a copolymer thereof, and the like can be used.

[Other ingredients]
The ink composition used in the present embodiment has a storage aid and viscosity to maintain good storage stability and ejection stability from the head, to improve clogging, or to prevent deterioration of the ink composition. Various additives such as a modifier, an antioxidant, and a chelating agent for capturing metal ions that affect the dispersion can be appropriately added.

[Method for preparing inkjet ink composition]
The ink-jet ink composition can be adjusted by mixing the above components. It does not specifically limit as a mixing method, A conventionally well-known method can be used.

[Use]
The ink composition of the present embodiment can be used for various recording media, such as cotton fabric with high ink absorbability, ink jet exclusive paper, medium absorbency fine paper, copy paper, and low absorption. It can be used for coated or non-absorbent coated paper or plastic film. In particular, the antiseptic component is preferably used for a low-absorbency recording medium or a non-absorbent recording medium that tends to bleed out to the surface of the recording medium.

  Although it does not specifically limit as a low absorptive recording medium, For example, the coated paper by which the coating layer for accepting oil-based ink was provided in the surface is mentioned. The coated paper is not particularly limited, and examples thereof include printing paper such as art paper, coated paper, and matte paper.

  The non-absorbable recording medium is not particularly limited. For example, a plastic film that does not have an ink absorbing layer, a substrate such as paper coated with plastic, or a plastic film bonded thereto Etc. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene.

  Here, the “low-absorbing recording medium” or “non-absorbing recording medium” refers to a recording medium having a water absorption of 10 mL / m 2 or less from the start of contact to 30 msec in the Bristow method. This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method".

  Further, the non-absorbent recording medium or the low-absorbing recording medium can be classified by the wettability of the recording surface with respect to water. For example, a 0.5 μL water droplet is dropped on the recording surface of the recording medium, and the contact angle reduction rate (comparison of the contact angle at 0.5 milliseconds after the landing and the contact angle at 5 seconds) is measured. The medium can be characterized. More specifically, as a property of the recording medium, the non-absorbing property of the “non-absorbing recording medium” indicates that the above-described reduction rate is less than 1%, and the low absorption of the “low-absorbing recording medium”. The property indicates that the decrease rate is 1% or more and less than 5%. Moreover, absorptivity means that said reduction rate is 5% or more. In addition, a contact angle can be measured using portable contact angle meter PCA-1 (made by Kyowa Interface Science Co., Ltd.) etc.

  Among these, the ink composition of the present embodiment is preferably attached to a non-absorbent film or a low-absorbent coated paper. Since the non-absorbing film or the low-absorbing coated paper tends to bleed out the antiseptic component to the surface of the recording medium, the present invention is particularly advantageous as a means for reducing the preservative amount.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples. The present invention is not limited in any way by the following examples.

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〔水溶性有機溶剤〕
下記表２に示す。

〔保湿剤〕
グリセリン
トリメチロールプロパン
プロピレングリコール
〔表面張力調整剤〕
オルフィンＥ１０１０（アセチレングリコール系界面活性剤、エアプロダクツ社製）
ＢＹＫ−３４８（シリコーン系界面活性剤、ビックケミー・ジャパン社製）
〔ｐＨ調整剤〕
トリエタノールアミン
〔色材〕
カーボンブラック
ダイレクトブルー１９９
〔樹脂〕
エチレン−酢酸ビニル樹脂（三井・デュポンポリケミカル株式会社社製） [Material for ink composition]
The main materials for the ink compositions used in the following examples and comparative examples are as follows.
〔Preservative〕
Shown in Table 1 below.

[Nonionic surfactant]
It is shown in Table 2 below.
(Water-soluble organic solvent)
It is shown in Table 2 below.

[Humectant]
Glycerin Trimethylolpropane Propylene glycol (Surface tension modifier)
Orphine E1010 (acetylene glycol surfactant, manufactured by Air Products)
BYK-348 (silicone surfactant, manufactured by Big Chemie Japan)
[PH adjuster]
Triethanolamine (coloring material)
Carbon black direct blue 199
〔resin〕
Ethylene-vinyl acetate resin (Mitsui / DuPont Polychemical Co., Ltd.)

[Measurement method of log P value]
The logP values were transcribed from MSDS and literature values.

[Preparation of ink composition]
Each material was mixed with the composition shown in Table 3 below and stirred sufficiently to obtain each ink composition. In Table 3 below, the unit of numerical values is mass%, and the total is 100.0 mass%.

[Evaluation]
[Antimicrobial test]
The number of viable bacteria after inoculating 10 ^{5 of} each bacterial species in the ink compositions of Examples and Comparative Examples and allowing them to act at 25 ° C. for 24 hours was determined based on the following criteria (determination criteria)
Initial: 100,000 CFU / g
A: Less than 100 CFU / g B: 100 CFU / g or more and less than 1,000 CFU / g C: 1,000 CFU / g or more and less than 10,000 CFU / g D: 10,000 CFU / g or more

[Low temperature stability test]
The ink composition was placed in a sample bottle and allowed to stand at −20 ° C. for 1 week, and the ink composition after standing was filtered to collect low-temperature precipitates. Low temperature stability was evaluated by the number of low temperature precipitates. Evaluation criteria are shown below.
(Judgment criteria)
A: Low-temperature precipitates are less than 50/1 mL B: Low-temperature precipitates are 50/1 mL or more and less than 200/1 mL C: Low-temperature precipitates are 200/1 mL or more

Claims (9)

A preservative having a log P value of water / octanol partition coefficient of 2.0 or more;
A nonionic surfactant having a Griffin method HLB of less than 6,
A water-soluble organic solvent having a log P value of water / octanol partition coefficient of 0 to 2.0;
Including at least water
The water content is 55% by mass or more,
The water-soluble organic solvent comprises an alkyl polyol or glycol alkyl ether;
Inkjet ink composition.   The inkjet ink composition according to claim 1, wherein the preservative has a normal boiling point of 300 ° C. or higher. The content of the preservative is 10 ppm or more and 500 ppm or less,
The inkjet ink composition of Claim 1 or 2 whose total content of the said water-soluble organic solvent and the said nonionic surfactant is 0.50 mass% or more and 15 mass% or less. The alkyl group of the alkyl polyol has 5 to 8 carbon atoms,
The inkjet ink composition according to any one of claims 1 to 3, wherein the alkyl group of the glycol alkyl ether has 2 to 6 carbon atoms.   The inkjet ink composition of any one of Claims 1-4 whose total content of components other than the said water | moisture content and solid content is 10 mass% or more and 40 mass% or less.   The inkjet ink composition according to claim 1, wherein the preservative contains at least one selected from the group consisting of isothiazoline compounds and haloalkynyl compounds.   The said nonionic surfactant contains at least 1 sort (s) or more selected from the group which consists of a nonionic acetylene glycol type surfactant and a silicone type surfactant in any one of Claims 1-6. Inkjet ink composition.   The preservative is selected from the group consisting of 2-butyl-1,2-benzisothiazolin-3-one, 3-iodo-2-propynylbutylcarbamate, and 2-n-octyl-4-isothiazolin-3-one. The ink-jet ink composition according to any one of claims 1 to 7, comprising at least one or more thereof.   The ink-jet ink composition according to any one of claims 1 to 8, which is attached to a non-absorbent film or a low-absorbent coated paper.