JP2017019998A - Water-in-oil type emulsion ink for inkjet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-in-oil type emulsion ink for inkjet excellent in storage stability and discharge stability and high in image concentration.SOLUTION: There is provided a water-in-oil type emulsion ink for inkjet having a water phase containing water and a liquid organic compound having an acidic group and an oil phase containing a water insoluble organic solvent and a basic emulsifier, where one of the water phase and the oil phase contains a coloring material. There is provided a water-in-oil type emulsion ink for inkjet having the water phase containing water and a liquid organic compound having a basic group and an oil phase containing a water insoluble organic solvent and an acidic emulsifier, where one of the water phase and the oil phase contains a coloring material.SELECTED DRAWING: None

Description

  The present invention relates to a water-in-oil emulsion ink for inkjet.

Water-in-oil (W / O) emulsions are used in pharmaceuticals, cosmetics, inks and the like. Among these, a low-viscosity water-in-oil emulsion with a low water content is suitable for inkjet inks because it can be ejected from an inkjet head.
Water-in-oil emulsion ink for ink-jet printing causes less curl on printing paper when printed on plain paper, and has higher image density and reduced show-through than oil-based ink. Therefore, it is possible to enable high-speed printing for plain paper. However, a water-in-oil emulsion having a low water content and a low viscosity has a problem that the water phase is easily separated over time.

  In Patent Document 1 and Patent Document 2, since a bleeding occurs when a colorant is added to an oil phase, a water-in-oil emulsion ink suitable for inkjet printing in which an aqueous phase containing a water-soluble dye is dispersed in the oil phase. Is disclosed. In Patent Documents 1 and 2, the polyglycerin fatty acid ester is used as an emulsifier, and the aqueous phase is dispersed in the oil phase.

  Patent Document 3 discloses the use of a polyglycerin fatty acid ester as an emulsifier in a water-in-oil emulsion ink for inkjet. Patent Document 3 discloses an example in which a pigment is contained in an oil phase and an example in which a water-soluble dye is contained in an aqueous phase. Patent Document 3 describes that, in an example in which a water-soluble dye is contained in an aqueous phase, a dissolution aid such as an amine surfactant is further contained in the aqueous phase.

In Patent Document 4, a water-in-oil emulsion for inkjet excellent in dischargeability and storage stability by dispersing an aqueous phase containing polyglycerin in an oil phase containing pigment using an emulsifier such as polyglycerin fatty acid ester. Providing ink is disclosed.
Patent Document 5 discloses an ink-jet emulsion ink containing a nonionic surfactant such as polyglycerin hydroxy fatty acid ester as an emulsifier. In Examples 5 and 6 of Patent Document 5, the aqueous phase contains a dye and a pigment, respectively.

JP 2013-72057 A JP 2013-177383 A JP 2012-122047 A JP 2013-18819 A JP 2006-56931 A

In patent documents 1-5, the emulsion is adjusted using a nonionic fatty acid ester as an emulsifier. However, in an emulsion ink for inkjet, since a dye and a pigment are contained in an aqueous phase and / or an oil phase, storage stability may not be sufficiently obtained only by using a nonionic fatty acid ester as an emulsifier.
In Patent Document 3, a water phase contains a water-soluble dye and a solubilizing agent such as an amine surfactant. However, by using an amine surfactant in the aqueous phase, the charge balance between the oil phase and the aqueous phase of the emulsion ink may be lost, and storage stability may not be sufficiently maintained.
In Patent Document 5, a pigment is contained in the aqueous phase of the emulsion ink. When a pigment dispersant is contained in the water phase together with the pigment, the charge balance between the oil phase and the water phase of the emulsion ink may be lost.

In the case of using an emulsion ink, in particular, when a pigment is used, the storage stability may be reduced due to the loss of the charge balance of the emulsion. Therefore, it is difficult to obtain storage stability suitable for inkjet inks simply by using an emulsifier as in a conventional emulsion.
Further, by including a color material in the water phase, it is possible to prevent the show-through and increase the image density. However, in the case where a color material is included in the aqueous phase, there is a problem that the storage stability is lowered because the amount of water in the aqueous phase increases in order to disperse or dissolve the color material.
One object of the present invention is to provide a water-in-oil emulsion ink for inkjet which has excellent storage stability and ejection stability and has a high image density.

The gist of the present invention is as follows.
(1) It has an aqueous phase containing water and a liquid organic compound having an acidic group, and an oil phase containing a water-insoluble organic solvent and a basic emulsifier, and at least one of the aqueous phase and the oil phase is colored. A water-in-oil emulsion ink for inkjet, comprising a material.
(2) The water-in-oil emulsion ink for inkjet according to (1), wherein the liquid organic compound having an acidic group has an acid value of 10 mgKOH / g or more.
(3) The water-in-oil emulsion ink for inkjet according to (1) or (2), wherein the liquid organic compound having an acidic group has a phosphate group.
(4) The water-in-oil emulsion ink for ink jet according to any one of (1) to (3), wherein the basic emulsifier has one or more basic groups among an amino group, an imino group, and a pyrrolidone group. .
(5) The basic emulsifier is at least one of polyester polyamine, polyester polyimine, polyalkylolaminoamide and its salt, polyether polyamine, and vinylpyrrolidone copolymer, (1) to (4 The water-in-oil emulsion ink for inkjet according to any one of the above.

(6) It has an aqueous phase containing water and a liquid organic compound having a basic group, and an oil phase containing a water-insoluble organic solvent and an acidic emulsifier, and at least one of the aqueous phase and the oil phase is colored. A water-in-oil emulsion ink for inkjet, comprising a material.
(7) The water-in-oil emulsion ink for inkjet according to (6), wherein the acidic emulsifier has one or more acidic groups among a carboxy group, a phosphate group, and a phosphate ester group.
(8) The water-in-oil emulsion ink for inkjet according to (6) or (7), wherein the acidic emulsifier is at least one of polyester having an acidic group and polyether having an acidic group.
(9) The water-in-oil emulsion ink for inkjet according to any one of (1) to (8), wherein the aqueous phase contains one or more of an acetylene diol compound and a polyether-modified siloxane.
(10) The water-in-oil emulsion ink for inkjet according to any one of (1) to (9), wherein the aqueous phase contains a color material, and the color material is a self-dispersing pigment.

  According to the present invention, it is possible to provide a water-in-oil emulsion ink for inkjet which has excellent storage stability and ejection stability and high image density.

(First embodiment)
A water-in-oil emulsion inkjet ink according to an embodiment of the present invention has an aqueous phase containing water and a liquid organic compound having an acidic group, and an oil phase containing a water-insoluble organic solvent and a basic emulsifier, At least one of the water phase and the oil phase contains a color material.
According to this, it is possible to provide a water-in-oil emulsion ink for inkjet which has excellent storage stability and ejection stability and high image density.
In the following description, a liquid organic compound having an acidic group may be simply referred to as an “acidic compound”.

According to the present embodiment, the emulsion droplets composed of the aqueous phase can be stably dispersed in the oil phase by including the acidic compound in the water phase and the basic emulsifier in the oil phase.
For emulsion inks that contain a color material in the aqueous phase, use a color material with a hydrophilic functional group introduced to improve the dispersibility or solubility of the color material in water, or use a pigment dispersant together with the pigment. To do. In such an emulsion ink, the charge balance is lost, and the storage stability tends to decrease. In the present embodiment, the storage stability can be enhanced by including an acidic compound in the water phase and a basic emulsifier in the oil phase, regardless of the type of the colorant or pigment dispersant.
In addition, in an emulsion ink in which a coloring material is contained in an aqueous phase, the amount of water tends to increase because the coloring material is dispersed or dissolved in water. Thus, even if the amount of water increases, according to the present embodiment, the storage stability can be maintained well.
The storage stability can also be improved in the emulsion ink in which the color material is contained in the oil phase. In particular, even in an emulsion ink in which a pigment is contained in an oil phase together with a pigment dispersant, it is possible to prevent the charge balance from being lost and maintain good storage stability.

In addition, by including an acidic compound in the water phase and a basic emulsifier in the oil phase, an emulsion ink having a low viscosity and excellent ejection stability can be obtained.
Further, even if the amount of water is low and the viscosity is low, the content of the color material in the ink can be increased, and the image density of the printed matter can be increased. In particular, emulsion inks limit the water content of the water phase, but when the water phase contains a color material, the content of the color material is increased while maintaining good storage stability, so that the ink with a high image density can be used. Can be provided.

"Water phase"
The aqueous phase contains a liquid organic compound having an acidic group together with water.
The liquid organic compound (acidic compound) having an acidic group is an organic compound that is liquid at 23 ° C. and has an acidic group.
By adding an acidic compound to the aqueous phase, emulsion droplets composed of the aqueous phase can be stably dispersed in the oil phase, and the emulsification stability of the water-in-oil emulsion can be enhanced.

  The melting point of the acidic compound is preferably 23 ° C. or lower, more preferably 15 ° C. or lower in order to maintain a liquid state at room temperature. The acidic compound preferably has 2 or more carbon atoms.

The acidic compound has a water phase solubility in water of preferably 5 g / 100 g or more at 23 ° C., more preferably 10 g / 100 g or more.
The solubility of the acidic compound in the water-insoluble organic solvent is preferably 3 g / 100 g or less, more preferably 0.5 g / 100 g or less at 23 ° C.
More preferably, the acidic compound is substantially completely soluble in water, which is the solvent of the aqueous phase, and does not substantially dissolve in the water-insoluble organic solvent in the mixing ratio of the water-in-oil emulsion.
The acidic compound is dissolved in water in the water phase and not in the water-insoluble organic solvent in the oil phase, so that the acidic compound is confined in the emulsion droplets composed of the aqueous phase, thereby further improving the dispersion stability of the emulsion droplets. Can do.
The pH of the acidic compound is preferably 2 to 7 and more preferably 2.5 to 6.5 in a 10% by mass aqueous solution.

  Examples of the acidic group of the acidic compound include a phosphoric acid group, a carboxy group, a sulfonic acid group, a phosphoric ester group, a sulfuric ester group, a nitric ester group, a phosphorous acid group, a phosphonic acid group, and a sulfinic acid group. . These may be contained in one molecule or in combination of two or more. It is preferable to have two or more acidic groups in one molecule of the acidic compound.

The acidic compound may be an oligomer, a polymer, or a low molecular weight compound.
As the oligomer or polymer, for example, poly (meth) acrylic resins, polyester resins, polyvinyl resins, polyether resins and the like can be used alone or in combination. Moreover, you may use the copolymer of the monomer or oligomer which comprises these resin.

As an acidic group, it originates from the monomer which comprises an oligomer or a polymer, and the acidic group may couple | bond and introduce | transduce into the principal chain or side chain of each structural unit. For example, a copolymer of (meth) acrylic acid ester and (meth) acrylic acid can be used. In this case, carboxy groups are introduced depending on the proportion of acrylic acid. Moreover, the copolymer etc. of (meth) acrylic acid ester and acid phosphoxy and (meth) acrylate can be mentioned. In this case, a phosphate group is introduced.
Moreover, as an acidic group, the oligomer or polymer may be introduce | transduced into phosphoric acid ester. In this case, a phosphate group is introduced according to the position and ratio of the hydroxyl group. In the case of having hydroxyl groups at both ends of the oligomer or polymer, phosphate groups are introduced at both ends of the oligomer or polymer to have a total of two phosphate groups.
When the acidic compound is an oligomer or a polymer, the weight average molecular weight is preferably 500 to 10,000, more preferably 1000 to 5,000.

  Specific examples of the oligomer or polymer as the acidic compound include, for example, polyoxyalkyl phosphate esters such as polyoxyethylene alkyl phosphate esters, polyoxyethylene polyoxypropylene phosphate esters, and polyether polyester phosphate esters. Examples thereof include phosphoric acid ester compounds; alkylpolyphosphonic acids; carboxy group-containing (meth) acrylic polymers. These may be used alone or in combination of two or more.

  As the acidic compound, low molecular weight compounds such as phosphate ester, sulfate ester, 1-hydroxyethane-1,1-diphosphonic acid may be used.

The acidic compound preferably has an acid value. The acid value of the acidic compound is preferably 3 to 200 mgKOH / g, more preferably 10 to 150 mgKOH / g.
Here, the acid value is the number of milligrams of potassium hydroxide required to neutralize all acidic components in 1 g of the nonvolatile content. The same applies hereinafter.

  Among these, a liquid organic compound having at least one of a phosphoric acid group, a phosphonic acid group, a phosphoric ester group and a carboxy group having an acid value of 10 mgKOH / g or more is preferable, and a phosphoric acid group is particularly preferable. Moreover, what has a phosphate group in the both ends of an acidic compound is still more preferable.

  Among the commercially available products, those that can be used as acidic compounds include, for example, “DISPERBYK102, 106, 110, 111, 180, 190, 194N, 2015” (all trade names) manufactured by Big Chemie Japan. “TEGO Dispers 655” manufactured by Sakai Kogyo Co., Ltd. “Efka 6230” manufactured by EFKA Co., Ltd. “PH-210” manufactured by Kyrest Co., Ltd. “ARUFON UC3510” manufactured by Toagosei Co., Ltd. “CM294P” manufactured by Unichemical Co., Ltd. “TEGO” manufactured by Evonik R) Dispers 651 (phosphate ester of specially modified polyether polymer) ”and the like.

As content of an acidic compound, it is preferable that it is 0.1-20 mass% with respect to the water phase whole quantity, More preferably, it is 1-15 mass%.
The content of the acidic compound is preferably 0.01 to 10% by mass, more preferably 0.1 to 6% by mass with respect to the total amount of the ink.
The mass ratio between the acidic compound and the color material is preferably 1.5 ≧ (mass of acidic compound) / (mass of color material) ≧ 0.5. Within this range, a water-in-oil emulsion excellent in emulsion stability can be provided.
The acidic compound is preferably selected so that the color material does not aggregate when used in combination with a color material, particularly a self-dispersing pigment.

The aqueous phase can further include a surface tension reducing agent.
By adding a surface tension reducing agent to the aqueous phase, the difference in interfacial tension between each component of the aqueous phase and water can be reduced, and finer emulsion droplets can be obtained. Furthermore, the storage stability at high temperatures can be further improved by adding a surface tension additive to the aqueous phase.
The surface tension reducing agent is preferably a component that reduces the surface tension of the acidic compound in the aqueous phase. When a coloring material is blended in the aqueous phase, the surface tension reducing agent is preferably a component that reduces the surface tension of the coloring material together with the acidic compound in the aqueous phase.
The surface tension reducing agent is preferably one that makes the surface tension of the mixture of acidic compound and colorant in the aqueous phase 30 to 50 mN / m, more preferably 35 to 45 mN / m, and still more preferably 37.5 to 42.5 mN. / M.
Although it does not restrict | limit especially as a surface tension reducing agent, It is preferable to select so that a color material may not aggregate when it uses together with the mixture of the acidic compound of a water phase, and a color material.

As the surface tension reducing agent, for example, acetylene diol compounds, polyether-modified siloxanes, silicone compounds, fluorine compounds and the like can be used alone or in combination of two or more.
Of these, acetylenic diol compounds and polyether-modified siloxanes can be preferably used as the surface tension reducing agent.
As the acetylene diol compound, acetylene diol to which 50 to 90% by mass of ethylene oxide (EO) is added can be used. In this case, it is preferable that 5 to 50 mol of EO is added in one molecule.

Examples of acetylenic diol compounds include Surfynol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, and DF37. CT111, CT121, CT131, CT136, TG, GA, DF110D (all trade names, manufactured by Air Products and Chemicals Inc.);
Olfin B, Y, P, A, STG, SPC, E1004, E1010, PD-001, PD-002W, PD-003, PD-004, EXP. 4001, EXP. 4036, EXP. 4051, EXP. 4123, EXP. 4300, AF-103, AF-104, AK-02, SK-14, AE-3 (all are trade names, manufactured by Nissin Chemical Industry Co., Ltd.);
Acetylenol E00, E00P, E40, E100 (all are trade names, manufactured by Kawaken Fine Chemical Co., Ltd.) and the like.
Examples of the polyether-modified siloxane include BYK345, 346, 347, 348, 349, 3455, 302, 307, 322, 323, 331, 333, 342, 377, 378 (all trade names, manufactured by Big Chemie Japan). Etc.

The aqueous phase solvent is preferably water such as distilled water or ion exchange water.
It is preferable that water is 70-100 mass% of the solvent of an aqueous phase, More preferably, it is 80-100 mass%.

The aqueous phase can further include a water-soluble organic solvent.
As the water-soluble organic solvent, an organic compound that is liquid at room temperature and is soluble in water can be used, and a water-soluble organic solvent that is uniformly mixed with the same volume of water at 1 atm 20 ° C. is preferably used. .
For example, lower alcohols such as methanol, ethanol, 1-propanol, isopropanol, 1-butanol, 2-butanol, isobutanol, 2-methyl-2-propanol; ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene Glycols such as glycol, propylene glycol, dipropylene glycol, tripropylene glycol and polypropylene glycol; glycerols such as glycerin, diglycerin, triglycerin and polyglycerin; acetins such as monoacetin, diacetin and triacetin; ethylene glycol monomethyl ether; Ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobuty Ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether Glycol ethers such as ether, tetraethylene glycol monoethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether; triethanolamine, 1-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, β -Use thiodiglycol, sulfolane, etc. Can be.

The boiling point of the water-soluble organic solvent is preferably 100 ° C. or higher, and more preferably 150 ° C. or higher. On the other hand, the lower limit of the boiling point of the water-soluble solvent is not particularly limited as long as the water-soluble solvent is liquid in the range of −20 to 90 ° C. The water-soluble organic solvent is preferably selected so as not to be substantially compatible with the water-insoluble organic solvent used in the oil phase.
These water-soluble organic solvents may be used alone or in combination of two or more as long as they form a single phase with water. The content of the water-soluble organic solvent in the ink is preferably 5 to 50% by mass and more preferably 10 to 35% by mass as the total content when two or more types are used.
By using a water-soluble organic solvent, the surface tension of the aqueous phase can be reduced during emulsification, and the difference in interfacial tension between the oil phase and the aqueous phase can be reduced. This makes it possible to form a fine emulsion without shearing with a strong mechanical force during emulsification, and to suppress an increase in temperature during emulsification.

Since the water-soluble organic solvent is useful for reducing the difference in interfacial tension between the oil phase and the aqueous phase during emulsion adjustment, it may be removed after emulsion adjustment.
The removal of the water-soluble organic solvent is performed by reducing pressure and / or heating using an evaporator, a hot plate or the like. At this time, the degree of pressure reduction and / or heating is adjusted so that the water-soluble organic solvent is removed, but a part of the water and the water-insoluble organic solvent remain.
In this case, the water-soluble organic solvent preferably has a boiling point of 100 ° C. or lower, more preferably 90 ° C. or lower.

  In the aqueous phase, metal salts, electrolytes, humectants, water-soluble polymers, oil-in-water (O / W) resin emulsions, antifungal agents, antiseptics, pH adjusters, as long as the effects of the present invention are not impaired. Other optional components such as an antifreezing agent may be added.

"Oil phase"
The oil phase contains a basic emulsifier together with a water-insoluble organic solvent.
As the water-insoluble organic solvent, any of a non-polar organic solvent and a polar organic solvent can be used. These may be used alone or in combination. In the present invention, the water-insoluble organic solvent is an organic solvent that is not uniformly mixed with the same volume of water at 1 atm. The water-insoluble organic solvent is preferably an organic solvent that is substantially incompatible with water.

Preferable examples of the nonpolar organic solvent include petroleum hydrocarbon solvents such as aliphatic hydrocarbon solvents, alicyclic hydrocarbon solvents, and aromatic hydrocarbon solvents.
Examples of the aliphatic hydrocarbon solvent and the alicyclic hydrocarbon solvent include water-insoluble organic solvents such as paraffinic, isoparaffinic, and naphthenic solvents, and commercially available products include 0 Solvent L and 0 Solvent M. No. 0 solvent H, Cactus normal paraffin N-10, Cactus normal paraffin N-11, Cactus normal paraffin N-12, Cactus normal paraffin N-13, Cactus normal paraffin N-14, Cactus normal paraffin N-15H, Cactus normal paraffin N-15 Paraffin YHNP, Cactus normal paraffin SHNP, Isosol 300, Isosol 400, Teclean N-16, Teclean N-20, Teclean N-22, AF Solvent No. 4, AF Solvent No. 5, AF Solvent No. 6, AF Solvent No., Naphthezol 160, Naphthezol 200, Naphthezol 220 (all manufactured by JX Nippon Mining & Energy Corporation); Isopar G, Isopar H, Isopar L, Isopar M, Exol D40, Exol D60, Exol D80, Exol D95, Exol D110, Preferable examples include Exol D130 (all manufactured by TonenGeneral Sekiyu KK).
As the aromatic hydrocarbon solvent, grade alkene L, grade alkene 200P (all manufactured by JX Nippon Oil & Energy Corporation), Solvesso 100, Solvesso 150, Solvesso 200, Solvesso 200ND (all manufactured by TonenGeneral Sekiyu KK), etc. Can be preferably mentioned.
The distillation initial boiling point of the petroleum hydrocarbon solvent is preferably 100 ° C. or higher, more preferably 150 ° C. or higher, and even more preferably 200 ° C. or higher. The distillation initial boiling point can be measured in accordance with JIS K0066 “Method for Distillation Test of Chemical Products”.

Preferred examples of the polar organic solvent include fatty acid ester solvents, higher alcohol solvents, higher fatty acid solvents and the like.
For example, isononyl isononanoate, isodecyl isononanoate, methyl laurate, isopropyl laurate, hexyl laurate, isopropyl myristate, isopropyl palmitate, hexyl palmitate, isooctyl palmitate, isostearyl palmitate, methyl oleate, ethyl oleate , Isopropyl oleate, butyl oleate, hexyl oleate, methyl linoleate, ethyl linoleate, isobutyl linoleate, butyl stearate, hexyl stearate, isooctyl stearate, isopropyl isostearate, 2-octyldecyl pivalate, soybean oil Methyl, soybean oil isobutyl, tall oil methyl, tall oil isobutyl, etc., the number of carbon atoms in one molecule is 13 or more, preferably 16-30 fatty acid esters Agent;
A higher alcohol solvent having 6 or more, preferably 12 to 20 carbon atoms in one molecule, such as isomyristyl alcohol, isopalmityl alcohol, isostearyl alcohol, oleyl alcohol, isoeicosyl alcohol, decyltetradecanol;
Higher fatty acid solvents such as lauric acid, isomyristic acid, palmitic acid, isopalmitic acid, α-linolenic acid, linoleic acid, oleic acid, isostearic acid and the like having 12 or more, preferably 14 to 20 carbon atoms in one molecule Is mentioned.
The boiling point of polar organic solvents such as fatty acid ester solvents, higher alcohol solvents and higher fatty acid solvents is preferably 150 ° C. or higher, more preferably 200 ° C. or higher, and further preferably 250 ° C. or higher. preferable. The water-insoluble organic solvent having a boiling point of 250 ° C. or higher includes a water-insoluble organic solvent having no boiling point.

  These water-insoluble organic solvents may be used alone or in combination of two or more as long as a single phase is formed. Moreover, you may include another organic solvent in the range which can form a single phase with the water-insoluble organic solvent to be used.

  Among these, as the water-insoluble organic solvent for the oil phase, nonpolar organic solvents are preferable, and hydrocarbon solvents such as naphthenic, paraffinic, and isoparaffinic solvents are more preferable.

  The water-insoluble organic solvent preferably has a Hansen solubility parameter (HSP value) of 14 to 18 MPa / cm 3. The water-insoluble organic solvent preferably has a dispersion term δd of 12 to 20, a polar term δp of 0 to 4, and a hydrogen bond term δh of 0 to 4.

The 50% distillation point of the water-insoluble organic solvent is preferably 400 ° C. or lower, more preferably 300 ° C. or lower. On the other hand, the lower limit of the 50% distillation point of the water-insoluble organic solvent is preferably 100 ° C. or higher in order to prevent volatilization of the water-insoluble organic solvent and maintain the stability of the emulsion ink. More preferably. When two or more water-insoluble organic solvents are contained in the oil phase, the 50% distillation point of a mixture of two or more water-insoluble organic solvents constituting the oil phase is preferably within this range.
The 50% distillation point means a temperature at which 50% by mass of a solvent is volatilized, which is measured according to JIS K0066 “Testing method for distillation of chemical products”.

A basic emulsifier is an emulsifier having a basic group.
The basic emulsifier is preferably such that when the basic emulsifier is dissolved in the water-insoluble organic solvent, the redox potential (ORP value) decreases as the concentration of the basic emulsifier increases.
For example, when dissolving the basic emulsifier in a solvent capable of dissolving the basic emulsifier, the basic emulsifier is dissolved by 5.0% by mass compared to the ORP value when the basic emulsifier is dissolved by 0.5% by mass. It is preferable that the ORP value when it is made to show a low value.
Further, the ORP value when the basic emulsifier is dissolved in 5.0% by mass in dodecane is preferably 0 mV or less.

  On the other hand, when the basic emulsifier contains an acidic group together with the basic group, the basic emulsifier is preferably used as the basic emulsifier even if the acidic group is contained, as long as the ORP value tends to be low. it can.

  Examples of the basic group of the basic emulsifier include an amino group, an amide group, a pyridyl group, an imino group, and a pyrrolidone group, and among them, an amino group, an imino group, and a pyrrolidone group are preferable. Moreover, as a basic group of a basic emulsifier, the nitrogen-containing functional group which has a urethane bond etc. can be mentioned. Further, a nitrogen-containing structural unit such as a urethane bond may be introduced into the basic emulsifier.

Examples of the basic emulsifier include modified polyurethane, basic group-containing poly (meth) acrylate, basic group-containing polyester, polyesteramine, quaternary ammonium salt, alkylamine salt such as stearylamine acetate, fatty acid amine salt, polyester, and the like. Examples include basic emulsifiers selected from polyamines, polyester polyimines, polyalkylolaminoamides and salts thereof, polyether polyamines, and vinylpyrrolidone copolymers. Of these, polymer emulsifiers are preferable, and polyester polyamines, polyester polyimines, polyalkylol aminoamides and salts thereof, polyether polyamines, and vinylpyrrolidone copolymers are particularly preferable. You may use these individually or in combination of multiple types.
Moreover, as a basic emulsifier, the block copolymer etc. which have the 1st block containing the unit which has a C12 or more alkyl group, and the 2nd block containing the unit which has a basic group can be used.

Examples of commercially available basic emulsifiers include:
“Solsperse 11200, 13940 (polyester polyimine), 17000, 18000, 19000 (polyester polyamine), 24000, 32000, 38500, 39000, 71000 (polyether polyamine), 22000, manufactured by Nippon Lubrizol Co., Ltd. 28000 "(both are trade names),
“DISPERBYK109 (polyalkylolaminoamide and its salt), 116, 2096, 2163” (all trade names) manufactured by Big Chemie Japan, Inc .;
“Acetamine 24, 86 (above, alkylamine salt type)” manufactured by Kao Corporation (both are trade names);
“Disparon KS-860, KS-873N4 (above, amine salt of polymer polyester)” manufactured by Enomoto Kasei Co., Ltd. (both are trade names);
“Hypermer KD-3 (basic polymer amide)” manufactured by Croda Japan Co., Ltd .;
“Ajisper PB-821” manufactured by Ajinomoto Fine Techno Co., Ltd .;
Examples include “ANTARON V-216 ((vinyl pyrrolidone / hexadecene) copolymer), V-220 ((vinyl pyrrolidone / eicosene) copolymer)” manufactured by ISP.

The basic emulsifier preferably has an amine value. The amine value of the basic emulsifier is preferably 3 to 200 mgKOH / g, more preferably 10 to 150 mgKOH / g, and still more preferably 30 to 100 mgKOH / g. As a result, fine and stable emulsion droplets can be produced.
Here, the amine value is the number of milligrams of potassium hydroxide equivalent to hydrochloric acid necessary for neutralizing all basic components contained in 1 g of the nonvolatile content. The same applies hereinafter.

From the viewpoint of emulsion stability, the basic emulsifier in the oil phase is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass, based on the entire continuous phase.
The basic emulsifier is preferably 0.05 to 10% by mass, more preferably 0.5 to 5% by mass, based on the total amount of the ink.

  You may add other arbitrary components, such as antioxidant, a surface tension regulator, and an antifoamer, to the oil phase in the range which does not impair the effect of this invention.

"Coloring material"
The color material may be included in at least one of the aqueous phase and the oil phase, and may be included in both. As the color material, both dyes and pigments can be used.

  When the water phase contains a color material, organic pigments such as azo pigments, phthalocyanine pigments, polycyclic pigments and dyed lake pigments, and inorganic pigments can be used as the pigment. Examples of the azo pigment include a soluble azo lake pigment, an insoluble azo pigment, and a condensed azo pigment. Examples of phthalocyanine pigments include metal phthalocyanine pigments and metal-free phthalocyanine pigments. Polycyclic pigments include quinacridone pigments, perylene pigments, perinone pigments, isoindoline pigments, isoindolinone pigments, dioxysazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, metal complex pigments. And diketopyrrolopyrrole (DPP). Representative examples of inorganic pigments include carbon black and titanium oxide. These pigments may be used alone or in combination of two or more.

  Examples of the dye include basic dyes, acid dyes, direct dyes, soluble vat dyes, acid mordant dyes, mordant dyes, reactive dyes, vat dyes, sulfur dyes, and the like, water-soluble dyes, and water-soluble by reduction or the like The water-soluble dye which became can be used preferably. Further, disperse dyes such as azo, anthraquinone, azomethine, and nitro are also preferably used.

On the other hand, when a coloring material is contained in the oil phase, a known pigment similar to the pigment that can be contained in the aqueous phase can be used as the pigment.
As the dye, for example, oil-soluble dyes such as azo, anthraquinone and azine can be used.

When a pigment is used as the coloring material, a pigment dispersant can be further added to the aqueous phase or the oil phase in order to improve the dispersion of the pigment in the aqueous phase or the oil phase. It is preferable to use a nonionic pigment dispersant so as not to affect the stability of the emulsion.
Specific examples of nonionic pigment dispersants include “EFKA4520 (modified polyurethane), 4510, 4530, 4540, 4550, 4570, 4590 (modified polyacrylate)” manufactured by BASF (all trade names); Daiichi Kogyo Seiyaku "Discall N-509 (polyalkylene polyamine alkylene oxide adduct)" manufactured by the company; "DISPERBYK-193" manufactured by Big Chemie Japan Co., Ltd., and the like.

  The content of the pigment dispersant is sufficient as long as the pigment can be sufficiently dispersed in the oil phase, and may be appropriately set.

When a coloring material is blended in the aqueous phase, a self-dispersing pigment can be preferably used as the coloring material in the aqueous phase.
Self-dispersing pigments are pigments that are self-dispersible in water, have many water-solubilizing groups such as carboxyl groups, carbonyl groups, hydroxyl groups, and sulfone groups on the pigment surface, and there is no polymer dispersant. Is a pigment that is stably dispersed. The self-dispersing pigment can be obtained by subjecting a normal pigment to surface treatment such as acid / base treatment, coupling agent treatment, polymer graft treatment, plasma treatment, oxidation / reduction treatment, and the like.
The self-dispersing pigment is not particularly limited, and for example, a self-dispersing pigment surface-treated by a method described in JP-A-8-3498, JP-T 2000-513396, or the like can be used.

Examples of a method for directly introducing a water-soluble functional group onto the surface of the pigment include a method in which carbon black is oxidized with hypochlorous acid soda. According to this method, a -COO (M) group or a lactone group can be introduced into the carbon black surface.
The pigment that can be used for the self-dispersing pigment is not particularly limited, and any of inorganic pigments and organic pigments can be used. Examples of pigments suitable for the surface treatment include carbon black such as MA8 and MA100 (manufactured by Mitsubishi Chemical Corporation) and color black FW200 (manufactured by Degussa).

The average particle diameter (diameter) of the self-dispersing pigment is preferably 60 nm or more, more preferably 70 nm or more, and further preferably 75 nm or more. Moreover, it is preferably 145 nm or less, more preferably 140 nm or less, and further preferably 130 nm or less.
Here, the average particle diameter is obtained by a dynamic light scattering method in a liquid.
As a specific method for measuring the average particle size, a dynamic light scattering particle size distribution measuring device “LB-500” (manufactured by Horiba, Ltd.), FPAR-1000 (manufactured by Otsuka Electronics Co., Ltd., cumulant method analysis), It can be measured using Nanotrac UPA 150EX (manufactured by Nikkiso Co., Ltd., 50% integrated value) or the like. The same applies hereinafter.

As a commercial item of a black self-dispersion pigment, for example, CAB-O-JET200, 300, 400 (manufactured by Cabot Japan Co., Ltd.); BONJET BLACK CW-1S, CW-2, CW-3, CW-4, CW- 5, CW-6 (manufactured by Orient Chemical Co., Ltd.); LIOJET WD BLACK 002C (manufactured by Toyo Ink Co.); Aqua-BLACK001, 162 (manufactured by Tokai Carbon Corporation); SDP BLACK 100, 1000, 2000 (Sensient For example).
Color self-dispersing pigments may also be used. Examples of the color self-dispersing pigment include SMART CYAN, MAGENTA, YELLOW, ULTRA CYAN, MAGENTA, YELLOW manufactured by Sensitive Colors Co., Ltd .; CAB-O-JET250C, 270C, 450C, 260M, 265M, 465M, 270Y manufactured by Cabot Japan Co., Ltd. 470Y, 740Y, and the like.
Two or more types of self-dispersing pigments can be used in the same ink as necessary.

The content of the color material is changed according to the desired image density and color, but is preferably 1 to 15% by mass, more preferably 3 to 10% by mass, based on the solid content, based on the total amount of ink. is there. When the color material is 1% by weight or more, a sufficient image density can be obtained. When the color material is 15% by mass or less, a low-viscosity ink suitable for inkjet printing can be obtained. In addition, when the content of the coloring material is within this range, the storage stability of the ink can be favorably maintained.
When the color material is contained in the aqueous phase, the color material is preferably contained at 0.1 to 10% by mass with respect to the total amount of the aqueous phase.
When the color material is included in the oil phase, the color material is preferably included at 0.1 to 10% by mass with respect to the total amount of the oil phase.

"Emulsion ink adjustment method"
A water-in-oil (W / O) emulsion can be produced by mixing and emulsifying the oil phase and the water phase. The aqueous phase and the oil phase are preferably prepared separately in advance. Subsequently, it can emulsify, adding a water phase in an oil phase. Or you may emulsify, after adding the component which comprises an oil phase to a water phase collectively or separately. For emulsification of the aqueous phase and the oil phase, an emulsifier such as a disper mixer or a homomixer can be used.

  The aqueous phase is dispersed or mixed by stirring or dividing all components into a stirring mixer such as a disperser or a disperser such as a bead mill, respectively, and if necessary, passed through a filter such as a membrane filter. Can be prepared. The oil phase can be adjusted in the same manner as the water phase.

  The water-in-oil emulsion of the present invention is preferably blended so that the oil phase is 40 to 95% by mass and the water phase is 60 to 5% by mass. When the ratio of the aqueous phase exceeds 60% by mass, the aqueous phase may be separated in the water-in-oil emulsion. If the ratio of the aqueous phase is less than 5% by mass, when used as an ink, the image density may be lowered, or printout may occur. In general, since the emulsion viscosity tends to increase as the ratio of the aqueous phase increases, the blending ratio of both phases in the ink is more preferably 50 to 95% by mass of the oil phase and 50 to 5% by mass of the aqueous phase. 60-95 mass% of phases and 40-10 mass% of water phases are still more preferable, 70-95 mass% of oil phases and 30-15 mass% of water phases are especially preferable.

The average particle size of the emulsion droplets is preferably about 500 nm or less, more preferably 300 nm or less, and even more preferably 200 nm or less.
The average particle size of the emulsion droplets can be measured according to a dynamic light scattering method.
The average particle size of the emulsion can be controlled by adjusting the amount of the basic emulsifier blended in the oil phase, the water content of the aqueous phase, and the like.

  The amount of water in the ink is preferably 3 to 50% by mass, more preferably 5%, based on the total amount of the ink because the viscosity of the ink can be reduced while maintaining a high print density and reduction in the back-through. It is -40 mass%, More preferably, it is 10-35 mass%.

In the case of using a self-dispersing pigment in the water phase as a colorant, the self-dispersing pigment is usually marketed at 5 to 20% by mass based on the solid content, and when the pigment content in the ink is increased, the water content is The ink viscosity may increase and the ink viscosity may increase. Therefore, in order to reduce the water content while increasing the pigment content in the ink, it is preferable to remove a part of the water during the emulsion adjustment. The removal of water may be performed before emulsification, during emulsification, or after emulsification. The removal of moisture is preferably performed in the presence of an acidic compound in order to prevent precipitation of the self-dispersing pigment. Further, since the self-dispersing pigment is presumed to be in a stable state in the emulsion in the presence of a basic emulsifier and an acidic compound, it is more preferable to remove water after emulsification.
The removal of water can be performed using the same method as the removal of the water-soluble organic solvent described above.

(Second Embodiment)
A water-in-oil emulsion inkjet ink according to another embodiment of the present invention has an aqueous phase containing water and a liquid organic compound having a basic group, and an oil phase containing a water-insoluble organic solvent and an acidic emulsifier. At least one of the water phase and the oil phase contains a color material.
According to this, it is possible to provide a water-in-oil emulsion ink that is excellent in image quality as well as storage stability and ejection stability.
In the following description, the description overlapping with the first embodiment described above is omitted. Further, a liquid organic compound having a basic group may be simply referred to as “basic compound”.

According to this embodiment, the emulsion phase droplet which consists of an aqueous phase can be stably disperse | distributed to an oil phase by including a basic compound in an aqueous phase and including an acidic emulsifier in an oil phase.
For emulsion inks that contain a color material in the aqueous phase, use a color material with a hydrophilic functional group introduced to improve the dispersibility or solubility of the color material in water, or use a pigment dispersant together with the pigment. To do. In such an emulsion ink, the charge balance is lost, and the storage stability tends to decrease. In the present embodiment, the storage stability can be enhanced by including a basic compound in the water phase and an acidic emulsifier in the oil phase, regardless of the type of the colorant or pigment dispersant.
In addition, in an emulsion ink in which a coloring material is contained in an aqueous phase, the amount of water tends to increase because the coloring material is dispersed or dissolved in water. Thus, even if the amount of water increases, according to the present embodiment, the storage stability can be maintained well.
The storage stability can also be improved in the emulsion ink in which the color material is contained in the oil phase. In particular, even in an emulsion ink in which a pigment is contained in an oil phase together with a pigment dispersant, it is possible to prevent the charge balance from being lost and maintain good storage stability.

Further, by including a basic compound in the water phase and an acidic emulsifier in the oil phase, an emulsion ink having a low viscosity and excellent ejection stability can be obtained.
Further, even if the amount of water is low and the viscosity is low, the content of the color material in the ink can be increased, and the image density of the printed matter can be increased. In particular, emulsion inks limit the water content of the water phase, but when the water phase contains a color material, the content of the color material is increased while maintaining good storage stability, so that the ink with a high image density can be used. Can be provided.

"Water phase"
The aqueous phase contains a liquid organic compound having a basic group together with water.
The liquid organic compound having a basic group (hereinafter sometimes simply referred to as “basic compound”) is an organic compound that is liquid at 23 ° C. and has a basic group.
By adding a basic compound to the aqueous phase, emulsion droplets composed of the aqueous phase can be stably dispersed in the oil phase, and the emulsification stability of the water-in-oil emulsion can be enhanced.

  The melting point of the basic compound is preferably 23 ° C. or lower, more preferably 15 ° C. or lower in order to maintain a liquid state at room temperature. Moreover, it is preferable that carbon number of a basic compound is 2 or more.

The basic compound preferably has a water phase solubility in water of 5 g / 100 g or more at 23 ° C., more preferably 10 g / 100 g or more.
The basic compound preferably has a solubility of 3 g / 100 g or less, more preferably 0.5 g / 100 g or less, with respect to the water-insoluble organic solvent in the oil phase.
More preferably, the basic compound is substantially completely soluble in water, which is the solvent of the aqueous phase, and does not substantially dissolve in the water-insoluble organic solvent in the mixing ratio of the water-in-oil emulsion.
The basic compound is dissolved in water in the water phase and not in the water-insoluble organic solvent in the oil phase, so that the basic compound is confined in the emulsion droplets composed of the aqueous phase, thereby improving the dispersion stability of the emulsion droplets. Can be increased.
The pH of the basic compound is preferably 7 to 9 and more preferably 7.5 to 8.5 in a 10% by mass aqueous solution.

Examples of the basic group of the basic compound include an amino group and a pyridyl group. The amino group may be any of a primary amino group, a secondary amino group, a tertiary amino group, and a combination thereof. Among these, it is preferable that the basic compound contains a secondary amino group (imino group). Moreover, as a basic group of a basic compound, the nitrogen-containing functional group which has a urethane bond, an amide bond, etc. can be mentioned. In addition, a nitrogen-containing structural unit such as a urethane bond or an amide bond may be introduced into the basic compound.
The basic compound is preferably a liquid organic compound having two or more basic groups in one molecule.

The basic compound may be an oligomer, a polymer, or a low molecular weight compound.
As the oligomer or polymer, for example, polyurethane resin, poly (meth) acrylic resin, polyester resin, polyvinyl resin, polyether resin, polyethyleneimine and the like can be used alone or in combination. Moreover, you may use the copolymer of the monomer or oligomer which comprises these resin.

The basic group may be derived from a monomer constituting the oligomer or polymer and introduced by binding an acidic group to the main chain or side chain of each structural unit.
The basic group may be introduced as an oligomer or polymer alkylammonium salt or amine salt.
When the basic compound is an oligomer or a polymer, the weight average molecular weight is preferably 500 to 10,000, more preferably 1,000 to 5,000.

  Examples of the basic compound include modified polyurethane, basic group-containing poly (meth) acrylate, basic group-containing polyester, polyesteramine, polyethyleneimine, quaternary ammonium salt, alkylamine salt such as stearylamine acetate, fatty acid amine, and the like. A salt etc. can be mentioned. You may use these individually or in combination of multiple types.

  The basic compound preferably has an amine value. The amine value of the basic compound is preferably 2 to 200 mgKOH / g, more preferably 4 to 100 mgKOH / g.

  As a basic compound, even if it is a liquid organic compound which has a basic group and does not have an acidic group, the liquid organic compound which has an acidic group with a basic group may be sufficient. As a liquid organic compound which has an acidic group with a basic group, the compound which has both basic groups among the above-mentioned acidic compounds can be used.

Among the commercially available products, those that can be used as basic compounds include, for example,
“DISPERBYK106, 180, 185, 191, 198” manufactured by Big Chemie Japan Co., Ltd .; “Solsperse 20000” (all trade names) manufactured by Nippon Lubrizol Co., Ltd., etc. can be used.

As content of a basic compound, it is preferable that it is 0.1-20 mass% with respect to the water phase whole quantity, More preferably, it is 1-15 mass%.
The content of the basic compound is preferably 0.01 to 10% by mass, more preferably 0.1 to 6% by mass with respect to the total amount of the ink.
The mass ratio of the basic compound and the color material is preferably 1.5 ≧ (mass of the basic compound) / (mass of the color material) ≧ 0.5. Within this range, an oil-in-oil emulsion excellent in emulsion stability can be provided.
As the basic compound, it is preferable to select a basic compound that does not aggregate when used in combination with a coloring material, particularly a self-dispersing pigment.

  The aqueous phase solvent is preferably water, and may further contain a surface tension reducing agent and / or a water-soluble organic solvent. Details are as described in the first embodiment.

"Oil phase"
The oil phase contains an acidic emulsifier together with a water-insoluble organic solvent.
The details of the water-insoluble organic solvent are as described in the first embodiment.

An acidic emulsifier is an emulsifier having an acidic group.
When the acidic emulsifier is dissolved in the water-insoluble organic solvent, the acidic emulsifier preferably has a higher oxidation-reduction potential (ORP) value as the concentration of the acidic emulsifier increases.
For example, when the acidic emulsifier is dissolved in a solvent capable of dissolving the acidic emulsifier, when the acidic emulsifier is dissolved by 5.0% by mass, compared to the ORP value when the acidic emulsifier is dissolved by 0.5% by mass. It is preferable that the ORP value is a high value.
The ORP value when the acidic emulsifier is dissolved in dodecane by 5.0% by mass is preferably 500 mV or more, and more preferably 1000 mV or more.

  Examples of the acidic group of the acidic emulsifier include a phosphoric acid group, a carboxy group, a sulfonic acid group, a phosphoric acid ester group, a sulfuric acid ester group, a nitric acid ester group, a phosphorous acid group, a phosphonic acid group, and a sulfinic acid group. . Of these, a phosphoric acid group, a carboxy group, and a phosphoric acid ester group are preferable. These may be contained in one molecule or in combination of two or more.

The acidic emulsifier may be an oligomer, a polymer, or a low molecular weight compound.
As the oligomer or polymer, for example, poly (meth) acrylic resin, polyester resin, polyvinyl resin, polyether resin, or the like can be used. Moreover, you may use the copolymer of the monomer or oligomer which comprises these resin.

As an acidic group, it originates from the monomer which comprises an oligomer or a polymer, and the acidic group may couple | bond and introduce | transduce into the principal chain or side chain of each structural unit.
Moreover, as an acidic group, the oligomer or polymer may be introduce | transduced into phosphoric acid ester.
When the acidic emulsifier is an oligomer or a polymer, the weight average molecular weight is preferably 500 to 10,000, more preferably 1,000 to 5,000.

As the acidic emulsifier, polyester having an acidic group and polyether having an acidic group can be preferably used.
As polyester which has an acidic group, phosphoric acid ester of polyester, nitrate ester, carbonate ester, carboxylic acid ester etc. can be mentioned, for example. Of these, polycaprolactone, polyvalerolactone phosphates, nitrates, carbonates, and carboxylates can be preferably used. In addition, as the polyester having an acidic group, a higher fatty acid multimer having a hydroxyl group such as 12-hydroxystearic acid can be used.
Examples of the polyether having an acidic group include phosphoric acid esters, nitric acid esters, carbonic acid esters, carboxylic acid esters of polyethers such as polyethylene glycol and polypropylene glycol. Of these, polyether phosphate esters can be preferably used.

Moreover, as an acidic emulsifier, low molecular weight compounds, such as higher fatty acids, such as 12-hydroxy stearic acid, can be used.
The above acidic emulsifiers can be used alone or in combination.

  The acidic emulsifier preferably has an acid value. The acid value of the acidic emulsifier is preferably 10 to 200 mgKOH / g, more preferably 20 to 150 mgKOH / g, and still more preferably 30 to 100 mgKOH / g.

Among the commercially available products, those that can be used as acidic emulsifiers include, for example,
"Solsperse 3000 (polyester polyacid)" (12-hydroxystearic acid hexamer, acid value 32 mgKOH / g), "Solsperse 21000 (polyester polyacid)" (12-hydroxystearic acid) Body, acid value 72 mgKOH / g), “Solsperse 36000 (polyester polyacid)” (polycaprolactone phosphate, acid value 45 mgKOH / g), “Solsperse 41000” (polyether phosphate, acid value 50 mgKOH / g) );
“Hypermer KD-4 (acidic condensed fatty acid)”, “Hypermer KD-8” manufactured by Croda Japan Co., Ltd .;
“DISPERBYK2096” (acid value 40 mgKOH / g) manufactured by Big Chemie Japan Co., Ltd. can be exemplified.

The acidic emulsifier in the oil phase is preferably 0.1 to 15% by mass, more preferably 1 to 10% by mass, based on the total amount of the oil phase, from the viewpoint of emulsion stability.
The acid emulsifier is preferably 0.05 to 10% by mass, more preferably 0.5 to 5% by mass, based on the total amount of the ink.

The color material is contained in at least one of the aqueous phase and the oil phase. Details of the color material are as described in the first embodiment.
The water-in-oil (W / O) emulsion can be prepared by mixing and emulsifying an oil phase and a water phase in the same manner as in the first embodiment.
In the oil phase and the water phase, any additive may be included as in the first embodiment.

(Inkjet ink)
As the ink-jet ink according to the present embodiment, the above-described water-in-oil emulsion can be used as it is, and if necessary, it is usually used in the field as long as the object of the present invention is not impaired. Various additives can be included. For example, a nozzle clogging preventive agent, an antioxidant, a conductivity adjusting agent, a viscosity adjusting agent, a surface tension adjusting agent, an oxygen absorbent and the like can be added as appropriate. These types are not particularly limited, and those used in the field can be used.

The viscosity of the ink-jet ink varies depending on the nozzle diameter of the discharge head of the ink-jet recording system, the discharge environment, and the like, but in general, it is preferably 5 to 100 mPa · s at 23 ° C., preferably 5 to 50 mPa · s. More preferably, it is more preferably 10 to 20 mPa · s.
The viscosity of the ink can be adjusted by adjusting the type and amount of components of the oil phase and the amount of the aqueous phase.

  The printing method using the inkjet ink is not particularly limited, and any method such as a piezo method, an electrostatic method, or a thermal method may be used. When an ink jet recording apparatus is used, it is preferable that the ink according to the present embodiment is ejected from the ink jet head based on a digital signal, and the ejected ink droplets are attached to the recording medium.

  In the present embodiment, the recording medium is not particularly limited, and printing paper such as plain paper, coated paper, special paper, cloth, inorganic sheet, film, OHP sheet, etc., and these are used as a base material and an adhesive layer on the back surface An adhesive sheet or the like provided with can be used. Among these, printing paper such as plain paper and coated paper can be preferably used from the viewpoint of ink permeability.

  Here, the plain paper is paper in which an ink receiving layer, a film layer, and the like are not formed on normal paper. Examples of plain paper include high quality paper, medium quality paper, PPC paper, reprinted paper, recycled paper, and the like. Plain paper is a paper in which ink easily penetrates because paper fibers having a thickness of several μm to several tens of μm form voids of several tens to several hundreds of μm.

  Further, as the coated paper, inkjet coated paper or so-called coated printing paper can be preferably used. Here, the coated printing paper is a printing paper conventionally used in letterpress printing, offset printing, gravure printing, etc., and has an inorganic pigment such as clay or calcium carbonate on the surface of high-quality paper or medium-quality paper. A printing paper provided with a coating layer by a paint containing a binder such as starch. Coated printing paper can be applied to fine coated paper, high-quality lightweight coated paper, medium-weight lightweight coated paper, high-quality coated paper, medium-quality coated paper, art paper, cast coated paper, etc., depending on the coating amount and coating method. being classified. Coated printing paper has fewer voids on the paper surface than plain paper and inkjet coated paper, so that ink penetration is slow and ink components tend to stay on the paper surface. Therefore, the ink according to the present embodiment is suitable for improving the fixing property to the coated printing paper.

  Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. Unless otherwise specified, “%” indicates “mass%”.

<Ink adjustment>
The components of the oil phase shown in Tables 1 to 4 were mixed at each blending amount to prepare an oil phase. Next, the components of the aqueous phase shown in each table were mixed in each compounding amount to prepare an aqueous phase. The compounding quantity of each component in a table | surface is shown by the mass%.
In each table, the unit of acid value and amine value of the liquid organic compound is “mgKOH / g”.
When each component contains a volatile component, the amount of nonvolatile components is shown in parentheses together with the total amount of each component. In addition, the total amount of water in the ink including water among the volatile components contained in the aqueous phase is also shown in each table. In Example 20, water was added separately to the aqueous phase.

The aqueous phase was added dropwise to the prepared oil phase while stirring at 5000 rpm using a high-speed homogenizer “Hiscotron” (trade name, manufactured by Microtec Nithion). Thereafter, the mixture was stirred at 12000 rpm for 3 minutes to obtain a water-in-oil (W / O) emulsion ink.
In Comparative Examples 1 to 4, 6, and 7, since separation started immediately after emulsification, no subsequent evaluation was performed.

Details of each component are as follows.
"Water phase"
(Self-dispersing pigment)
BONJET BLACK CW-5: “BONJET BLACK CW-5” manufactured by Orient Chemical Co., Ltd., non-volatile content 13%, surface functional group -COONa.
SMART Magenta: “SMART Magenta” manufactured by Sensient Colors Co., Ltd., 14% nonvolatile content, surface functional group -COONa.
Cab-O-Jet 270Y: “Cab-O-Jet 270Y” manufactured by Cabot Japan Co., Ltd., 10% nonvolatile content, surface functional group —SO ₂ Na.
(Pigment) Carbon black: “# 970” manufactured by Mitsubishi Chemical Corporation.
(Pigment Dispersant) “DISPERBYK-193” manufactured by Big Chemie Japan Co., Ltd., copolymer having affinity for pigment, nonionic, non-volatile content 40%.

(Liquid organic compound)
Compound having an acid value of 132 and an amine value of 74: “DISPERBYK-106” manufactured by Big Chemie Japan Co., Ltd., polymer salt having an acidic group, 91% nonvolatile content, acid value of 132 mgKOH / g, amine value of 74 mgKOH / g.
Compound having acid value 94 and amine value 94: “DISPERBYK-180” manufactured by Big Chemie Japan Co., Ltd., alkylol ammonium salt of copolymer containing acid group, non-volatile content 81%, acid value 94 mgKOH / g, amine value 94 mgKOH / g.
Compound having an acid value of 30 and an amine value of 20: “DISPERBYK-191” manufactured by Big Chemie Japan Co., Ltd., a copolymer having an affinity for pigment, non-volatile content of 98%, an acid value of 30 mgKOH / g, and an amine value of 20 mgKOH / g.
Compound having an acid value of 10 and an amine value of 0: “DISPERBYK-2015” manufactured by Big Chemie Japan Co., Ltd., acrylic copolymer of control polymerization, non-volatile content of 40%, acid value of 10 mgKOH / g.
Compound having an acid value of 75 and an amine value of 0: “DISPERBYK-194N” manufactured by Big Chemie Japan Co., Ltd., a copolymer having an affinity for the pigment, a non-volatile content of 57%, and an acid value of 75 mgKOH / g.
Compound having an acid value of 129 and an amine value of 0: “DISPERBYK-111” manufactured by Big Chemie Japan Co., Ltd., a copolymer containing an acid group (a phosphate compound having a phosphate group at both ends of the copolymer), nonvolatile content 95%, acid value 129 mg KOH / g.
Compound having an acid value of 10 and an amine value of 0: “DISPERBYK-190” manufactured by Big Chemie Japan Co., Ltd., a block copolymer having affinity for the pigment, non-volatile content of 40%, and an acid value of 10 mgKOH / g.
Compound having an acid value of 0 and an amine value of 4: “DISPERBYK-198” manufactured by Big Chemie Japan Co., Ltd., a copolymer having a basic pigment affinity group, a non-volatile content of 40%, an amine value of 4 mgKOH / g.
(Comparative compound) Compounds having an acid value of 0 and an amine value of 0: TEGO (R) Dispers 652: “TEGO (R) Dispers 652” manufactured by Evonik, active ingredient 100%, acid value 0 mgKOH / g, amine value 0 mgKOH / g.

(Solid resin) Polyvinyl alcohol: “Kuraray Poval PVA224” manufactured by Kuraray Co., Ltd.
(Surface tension reducing agent)
Surfynol 465: Acetylene diol compound, “Surfinol 465” manufactured by Air Products Japan Co., Ltd. EO (ethylene oxide) 65% addition (mass%), EO is added 10 mol.
Surfynol 485: Acetylene diol compound, “Surfinol 485” manufactured by Air Products Japan Co., Ltd. EO is 85% addition (mass%), and 30 mol of EO is added.
Orphin EXP. 4123: Acetylene diol compound, “Orphine EXP. 4123” manufactured by Nissin Chemical Industry Co., Ltd.
BYK-348: Polyether-modified siloxane, “BYK-348” manufactured by Big Chemie Japan Co., Ltd.
Silicone compound “Silface SAG503A”: polyether-modified silicone, “Silface SAG503A” manufactured by Nissin Chemical Industry Co., Ltd.
Fluorine compound “Surflon S-243”: Perfluoroalkyl EO adduct, “Surflon S-243” manufactured by AGC Seimi Chemical Co., Ltd.
(Water-soluble organic solvent) Glycerin: “Glycerin” manufactured by Wako Pure Chemical Industries, Ltd.

"Oil phase"
(Basic emulsifier)
Solsperse 11200: “Solsperse 11200” manufactured by Nippon Lubrizol Co., Ltd., nonvolatile content 50%.
Solsperse 17000: “Solsperse 17000” manufactured by Nippon Lubrizol Co., Ltd., nonvolatile content 100%.
Solsperse 18000: “Solsperse 18000” manufactured by Nippon Lubrizol Co., Ltd., nonvolatile content 100%.
Solsperse 19000: “Solsperse 19000” manufactured by Nippon Lubrizol Co., Ltd., nonvolatile content 100%.
Hypermer KD-3: “Hypermer KD-3” manufactured by Croda Japan Co., Ltd., nonvolatile content 100%.
Solsperse 71000: “Solsperse 71000” manufactured by Nippon Lubrizol Co., Ltd., nonvolatile content 100%.
DISPERBYK-109: “DISPERBYK-109” manufactured by Big Chemie Japan, Inc., 100% nonvolatile content.
ANTARON V-216: “ANTARON V-216” manufactured by ISP, 100% non-volatile content.

(Acid emulsifier)
Hypermer KD-4: “Hypermer KD-4” manufactured by Croda Japan Co., Ltd., nonvolatile content 100%.
Hypermer KD-8: “Hypermer KD-8” manufactured by Croda Japan Co., Ltd., nonvolatile content 100%.
Solsperse 3000: “Solsperse 3000” manufactured by Nippon Lubrizol Co., Ltd., 100% nonvolatile content.
Solsperse 21000: “Solsperse 21000” manufactured by Nippon Lubrizol Co., Ltd., nonvolatile content 100%.
Solsperse 41000: “Solsperse 41000” manufactured by Nippon Lubrizol Co., Ltd., nonvolatile content 100%.
(Comparative emulsifier)
Decaglyceryl diisostearate: “Decalyn2-ISV” manufactured by Nikko Chemicals Co., Ltd., decaglyceryl diisostearate.
Monoisostearyl glyceryl ether: “Penetol GE-IS” manufactured by Kao Corporation, monoisostearyl glyceryl ether.

(Water-insoluble organic solvent)
AF Solvent No. 4: “AF Solvent No. 4” manufactured by JX Nippon Oil & Energy Corporation, naphthenic hydrocarbon.
Isopar M: “Isopar M” manufactured by TonenGeneral Sekiyu KK, isoparaffinic hydrocarbon.
Methyl oleate: “Exepal M-OL” manufactured by Kao Corporation, fatty acid ester.

  The liquid organic compound used is a liquid organic compound having an acid value as a compound having an acid value, a liquid organic compound having a basic group as a compound having an amine value, and a compound having both an acid value and an amine value as It is a liquid organic compound having an acidic group and a basic group. A compound having an acid value and an amine value of 0 is a liquid organic compound having no acidic group or basic group.

<Evaluation>
The following evaluations were performed using the inks described above. The results are shown in each table.
(Ink viscosity)
The obtained emulsion ink was sampled and the ink viscosity was measured. The ink viscosity was measured at room temperature (23 ° C.) using a rheometer ARG2 (manufactured by TA Instruments Inc.) with a cone angle of 2 °, a diameter of 40 mm.

(Storage stability)
The storage stability was evaluated by comparing the ink viscosity immediately after preparation of the emulsion ink with the ink viscosity after being left under a certain condition.
The obtained emulsion ink was put in a 10 ml screw-vial bottle and left under conditions of 23 ° C. for 1 month, 50 ° C. for 1 month, and 70 ° C. for 1 week. Thereafter, the ink was sampled, visually evaluated, and the ink viscosity was measured.
The ink viscosity was measured at room temperature (23 ° C.) using a rheometer ARG2 (manufactured by TA Instruments Inc.) with a cone angle of 2 °, a diameter of 40 mm.
From the measurement result of the ink viscosity, the ink viscosity change rate was obtained by the following formula.
Ink viscosity change rate (%) = 100− {ink viscosity after standing (mPa · s) / ink viscosity immediately after preparation (mPa · s)} × 100

From the visual evaluation of the ink after standing and the ink viscosity change rate, the storage stability was evaluated according to the following criteria.
A: In any leaving environment, ink separation and pigment aggregation sediment are not observed, and the ink viscosity change rate is within ± 5%.
B: Separation of ink and aggregated sediment of pigment are not observed in any standing environment. When left at 23 ° C. for 1 month, the ink viscosity change rate is within ± 5%, but after leaving at 50 ° C. for 1 month or 70 ° C. for 1 week, the ink viscosity change rate is ± 5% or more and less than 10%.
C: Ink separation and pigment aggregation sediment are not observed when left at 23 ° C for one month, but ink separation, pigment aggregation sedimentation is observed after standing at 50 ° C for one month or 70 ° C for one week, or ink viscosity The rate of change is ± 10% or more.
D: Ink separation, pigment aggregation and sedimentation are observed after standing at 23 ° C. for 1 month, or ink viscosity change rate is ± 10% or more.

(Discharge stability)
Using a line-type inkjet printer-"Orufis EX9050" (trade name, manufactured by Riso Kagaku Co., Ltd.), 10 sheets of solid images are continuously printed on plain paper "ideal paper thin mouth" (trade name, manufactured by Riso Kagaku Co., Ltd.). Printing was performed, the state of non-ejection of the ink was observed, and the following criteria were evaluated.
A: There was almost no non-ejection, and almost the same image could be printed on the first and tenth sheets.
B: There are many non-ejections, and the same image cannot be printed on the first and tenth sheets.
C: Unable to eject or too many non-ejections to print a solid image.

(Image density)
A solid image was printed on plain paper “ideal paper thin mouth” (trade name, manufactured by Riso Kagaku Co., Ltd.) using a line-type ink jet printer “Orifice EX9050” (trade name: manufactured by Riso Kagaku Co., Ltd.). The OD value of the surface of the solid image portion was measured using a spectrocolorimeter (X-Rite exact advance, manufactured by X-Rite), and evaluated according to the following criteria.
For the color images of Examples 3, 6, 11 and 12, the following criteria are used in the same manner as the black image using the image density value of the color area (cyan / magenta / yellow) automatically selected by the filter. It was evaluated with.
A: The OD value is 1.15 or more.
B: The OD value is 1.05 or more and less than 1.15.
C: OD value is less than 1.05.

As shown in the respective tables, the inks of the respective examples had good evaluations, and the viscosity of the emulsion ink was within an appropriate range.
In Examples 1 to 9, a basic emulsifier was included in the oil phase, and a liquid organic compound having an acidic group was included in the aqueous phase, and the results of excellent image quality as well as storage stability and ejection stability were obtained.
Through Examples 1 to 9, it was found that good results were obtained with various basic emulsifiers in the oil phase, liquid organic compounds having various acidic groups in the aqueous phase, and various water-insoluble organic solvents in the oil phase.

In Examples 10 to 14, the oil phase contained an acidic emulsifier, and the water phase contained a liquid organic compound having a basic group, and the results were excellent in image quality as well as storage stability and ejection stability.
Through Examples 10 to 14, it was found that good results were obtained with various acidic emulsifiers in the oil phase, liquid organic compounds having various basic groups in the aqueous phase, and various water-insoluble organic solvents in the oil phase.
When Examples 1-9 are compared with Examples 10-14, the storage stability at high temperature is further improved in the ink containing the basic emulsifier in the oil phase and the liquid organic compound having an acidic group in the aqueous phase. It was done.

In Examples 15 to 20, a basic emulsifier was included in the oil phase, and a liquid organic compound having an acidic group was included in the aqueous phase, and the results were excellent in image quality as well as storage stability and ejection stability.
In Examples 15 and 16, the aqueous phase contained an acetylenic diol surface tension reducing agent and a polyether-modified siloxane surface tension reducing agent, respectively, and the storage stability and ejection stability were further improved.
In Example 20, a pigment and a pigment dispersant are used in an aqueous phase, a basic emulsifier is contained in an oil phase, and a liquid organic compound having an acidic group is contained in an aqueous phase, and the image quality is excellent with storage stability and ejection stability. The result was obtained.
In Example 20, the aqueous phase contained an acetylenic diol-based surface tension reducing agent, and the storage stability and discharge stability were further improved.

In Comparative Example 1, although the oil phase contained an acidic emulsifier, the water phase did not contain a liquid organic compound, and the emulsion stability decreased.
In Comparative Examples 2 to 4, the oil phase contained an acidic emulsifier, and the aqueous phase contained a liquid organic compound having an acidic group but no basic group, resulting in a decrease in emulsion stability.
In Comparative Example 5, a low molecular weight emulsifier was included in the oil phase, and a liquid organic compound having an acidic group was included in the aqueous phase, and sufficient evaluation results were not obtained.
In Comparative Example 6, the oil phase contained a basic emulsifier, and the water phase contained a liquid organic compound having no acidic group and having a basic group, and sufficient evaluation results were not obtained.
In Comparative Example 7, although the oil phase contained a basic emulsifier, the liquid organic compound in the aqueous phase did not have an acidic group and a basic group, and the emulsion stability decreased.
In Comparative Example 8, although the oil phase contained a basic emulsifier, the water phase contained no solid organic resin and the emulsion stability decreased.
In Comparative Example 9, the amount of pigment was less than that in Comparative Example 5, and sufficient evaluation results could not be obtained.
In Comparative Example 10, the aqueous phase did not contain a liquid organic compound as compared with Comparative Example 5, and the emulsion stability decreased.

Claims (10)

Having an aqueous phase containing water and a liquid organic compound having an acidic group, and an oil phase containing a water-insoluble organic solvent and a basic emulsifier,
At least one of the water phase and the oil phase contains a color material,
Water-in-oil emulsion ink for inkjet.   The water-in-oil emulsion ink for inkjet according to claim 1, wherein the liquid organic compound having an acidic group has an acid value of 10 mgKOH / g or more.   The water-in-oil emulsion ink for inkjet according to claim 1, wherein the liquid organic compound having an acidic group has a phosphate group.   The water-in-oil emulsion ink for inkjet according to any one of claims 1 to 3, wherein the basic emulsifier has one or more basic groups among amino group, imino group and pyrrolidone group.   The said basic emulsifier is at least 1 sort (s) among polyester polyamine, polyester polyimine, polyalkylol amino amide and its salt, polyether polyamine, and vinylpyrrolidone-type copolymer, Any one of Claim 1 to 4 The water-in-oil emulsion ink for inkjet according to item. Having an aqueous phase containing water and a liquid organic compound having a basic group, and an oil phase containing a water-insoluble organic solvent and an acidic emulsifier,
At least one of the water phase and the oil phase contains a color material,
Water-in-oil emulsion ink for inkjet.   The water-in-oil emulsion ink for inkjet according to claim 6, wherein the acidic emulsifier has one or more acidic groups among a carboxy group, a phosphate group, and a phosphate ester group.   The water-in-oil emulsion ink for inkjet according to claim 6 or 7, wherein the acidic emulsifier is at least one of polyester having acidic groups and polyether having acidic groups.   The water-in-oil emulsion ink for inkjet according to any one of claims 1 to 8, wherein the aqueous phase contains one or more of an acetylenic diol compound and a polyether-modified siloxane.   The water-in-oil emulsion ink for inkjet according to any one of claims 1 to 9, wherein the aqueous phase contains a color material, and the color material is a self-dispersing pigment.