WO2014156758A1

WO2014156758A1 - Colorant dispersion liquid, ink composition, ink set, ink jet recording method, and colored body

Info

Publication number: WO2014156758A1
Application number: PCT/JP2014/057096
Authority: WO
Inventors: 明央桑原; 波崔; 彬川口
Original assignee: 日本化薬株式会社
Priority date: 2013-03-28
Filing date: 2014-03-17
Publication date: 2014-10-02
Also published as: JPWO2014156758A1; JP6293119B2

Abstract

Provided are: a colorant dispersion liquid that has good filterability when removing impurities, that has good storage stability, and that exhibits excellent coloring properties, redispersibility, and storage stability when included in an ink composition; and an ink composition containing the colorant dispersion liquid. The colorant dispersion liquid comprises water, a colorant and a dispersant. The dispersant is a copolymer of a monomer (A) that is styrene, a monomer (B) that is acrylic acid, and a monomer (C) that is a C4-C9 alkyl ester of acrylic acid. The ink composition contains the colorant dispersion liquid.

Description

Colored dispersion, ink composition, ink set, ink jet recording method and colored body

The present invention relates to a colored dispersion, an ink composition, an ink set, an ink jet recording method, and a colored body.

As colorants used in inkjet inks, two types of colorants are generally known: water-soluble dyes and substantially water-free colorants such as pigments, disperse dyes, and oil-soluble dyes. It has been. Among these, a recorded image using a water-soluble dye as a colorant is excellent in image quality such as sharpness, and a colorant unnecessary for water and a recorded image using a pigment among them are light, ozone It is said to be excellent in various fastness properties against water and the like. Due to these various advantages of excellent fastness, the use of ink-jet inks (pigment inks for ink-jet) containing a colorant unnecessary for water is spreading.

In particular, in industrial applications, use as a digital printing output machine is expected due to improvements in inkjet technology, and water-based inks are required from the environmental and safety viewpoints.

However, when a colorant that is insoluble in water is used in an ink-jet ink, it is necessary to make the colorant fine and then disperse it in the ink to stabilize the state. For this reason, in order to keep the dispersion state stable for a long period of time, selection of the dispersant is extremely important.
The dispersant has a high affinity with the colorant surface, and has a high affinity with a hydrophobic portion adsorbed on the colorant surface and an aqueous medium such as water or a water-soluble organic solvent contained in the ink. Nonionic and anionic surfactants and various polymer compounds have been proposed as dispersants.

On the other hand, with the improvement of inkjet printer technology, high-resolution printing and high-speed printing have become possible. Ink-jet inks containing unnecessary colorants in water are required to have finer colorants than ever before. ing. Ink containing such a finer colorant is more difficult than ever to maintain its storage stability due to problems such as changes in particle size and viscosity due to storage. Various studies have been conducted for improving storage stability.

Furthermore, the ink containing an unnecessary colorant in water has a drawback that the dispersion state of the pigment is broken and the colorant is aggregated when the water content is lost due to some factors and becomes dry. Since the colorant once agglomerated in this way cannot be returned to the dispersed state again even if an aqueous medium such as water is added (redispersibility is poor), improvement thereof is strongly demanded.

For example, Patent Documents 1 to 10 propose the use of various polymer compounds as dispersants. However, since the storage stability of a colored dispersion containing an unnecessary colorant in water and the ink composition is not yet sufficient, there is a strong demand for improvement.

Japanese Patent Laid-Open No. 08-253716 JP 2009-144060 A Japanese Patent Laid-Open No. 08-183920 JP 2004-217916 A Japanese Patent Laid-Open No. 11-228891 Japanese Patent Laid-Open No. 06-306317 Japanese Patent Laid-Open No. 08-183920 JP 2009-132781 A JP 2011-63769 A JP 2011-202020 A

The present invention provides a colored dispersion having good filterability when removing impurities, good storage stability, and excellent color development, redispersibility, and storage stability when incorporated in an ink composition, It is an object to provide an ink composition containing a colored dispersion, an ink set including the ink composition, an ink jet recording method using the ink composition, and a colored body colored with the ink composition.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the above-described problems can be solved by a colored dispersion containing a specific monomer copolymer as a dispersant and an ink composition containing the same. The inventors have found that this can be solved and completed the present invention.
That is, the present invention relates to the following [1] to [24].

[1]
A colored dispersion containing water, a colorant, and a dispersant, wherein the dispersant is a copolymer of the following monomers (A), (B), and (C).
Monomer (A): Styrene.
Monomer (B): acrylic acid.
Monomer (C): C4-C9 alkyl ester of acrylic acid.
[2]
The colored dispersion according to the above [1], wherein the dispersant has a mass average molecular weight of 8,000 to 100,000 and an acid value of 50 to 400 mg / KOH.
[3]
The colored dispersion according to [1] or [2], wherein the dispersant has a mass average molecular weight of 8,000 to 50,000 and an acid value of 100 to 300 mg / KOH.
[4]
The colored dispersion according to any one of [1] to [3], wherein the monomer (C) is 2-ethylhexyl acrylate.
[5]
The colored dispersion according to any one of [1] to [4], wherein the colorant is a colorant substantially insoluble in water.
[6]
The colored dispersion according to any one of [1] to [5], wherein the colorant is at least one colorant selected from the group consisting of an organic pigment, an inorganic pigment, and carbon black.
[7]
An ink composition comprising the colored dispersion according to any one of [1] to [6] above and a water-soluble organic solvent.
[8]
Furthermore, the ink composition as described in [7] above, which contains a surfactant.
[9]
The ink composition according to [7] or [8], wherein the water-soluble organic solvent is at least one selected from the group consisting of glycol ethers and alkanediols.
[10]
The glycol ether is selected from the group consisting of ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and propylene glycol monopropyl ether. The ink composition according to [9], wherein the ink composition is at least one kind.
[11]
The alkanediol is 1,2-pentanediol, 1,2-hexanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, and 2,4-diethyl-1, The ink composition according to [9] or [10] above, which is at least one selected from the group consisting of 5-pentanediol.
[12]
The ink composition according to [8], wherein the surfactant is at least one selected from the group consisting of an anionic surfactant and a nonionic surfactant.
[13]
The ink according to [12], wherein the anionic surfactant is at least one selected from the group consisting of polyoxyethylene dinonyl phenyl ether sulfate, polyoxyethylene lauryl ether sulfate, and dioctyl sulfosuccinate. Composition.
[14]
The ink composition according to [12] or [13], wherein the nonionic surface activity is at least one selected from the group consisting of polyoxyethylene acetylene glycol ether and polyoxyethylene distyrenated phenyl ether.
[15]
The ink composition according to any one of [7] to [14], which is used for inkjet recording.
[16]
An ink jet recording method in which recording is performed by ejecting droplets of the ink composition according to any one of [7] to [14] according to a recording signal and attaching the droplets to a recording material.
[17]
The inkjet recording method according to [16], wherein the recording material is an information transmission sheet.
[18]
The inkjet recording method according to [17], wherein the information transmission sheet is a sheet having an ink receiving layer containing a porous white inorganic substance.
[19]
The inkjet recording method according to [17], wherein the information transmission sheet is cast-coated paper.
[20]
The inkjet recording method according to [17], wherein the information transmission sheet is coated paper or art paper.
[21]
The inkjet recording method according to [19] or [20], wherein the information transmission sheet is a sheet that has been subjected to at least one surface modification treatment selected from corona discharge treatment, plasma treatment, and frame treatment. .
[22]
A colored body colored with the ink composition according to any one of [7] to [15].
[23]
An inkjet printer loaded with a container containing the ink composition according to any one of [7] to [14].
[24]
An ink set including four types of inks of black ink, cyan ink, magenta ink, and yellow ink, and at least one of the four types of ink is any one of [7] to [15]. An ink set which is the ink composition according to claim 1.

According to the present invention, a colored dispersion having good filterability when removing impurities, good storage stability, and excellent color development, redispersibility, and storage stability when incorporated in an ink composition, An ink composition containing a colored dispersion, an ink set including the ink composition, an ink jet recording method using the ink composition, and a colored body colored with the ink composition can be provided.

Hereinafter, the present invention will be described in detail.
In this specification, “CI” is an abbreviation for color index. Further, in this specification, “%” and “parts” are described on a mass basis unless otherwise specified, including examples.

The colorant contained in the colored dispersion is not particularly limited, and any known and commonly used pigments, disperse dyes and the like can be used. Moreover, you may use these together as needed. A colorant substantially unnecessary for water is preferable, and at least one colorant selected from the group consisting of organic pigments, inorganic pigments, and carbon black is more preferable.
In the present specification, the colorant substantially unnecessary for water is a colorant having a solubility per liter of water of usually 0.5 g or less, preferably 0.1 g or less, more preferably about 0.03 g or less. Means that. Examples of such colorants include organic pigments, inorganic pigments, carbon black, extender pigments, and disperse dyes.
These colorants may be used alone or in combination of two or more.
Examples of the purpose of blending the colorant include hue adjustment of a recorded image; improvement of storage stability when a colored dispersion or ink composition is used; and the like. The hue adjustment referred to here means that the recorded image is shaded; the color gamut of the recorded image is expanded; Preferably, it is desirable to use two or less kinds of colorants in combination, and it is particularly preferable to use a single colorant.
The content of the colorant is usually 1 to 30%, preferably 1 to 10%, more preferably 2 to 7% with respect to the total mass of the ink composition as the content in the ink composition.

Examples of organic pigments include insoluble azo pigments such as toluidine red, toluidine maroon, hansa yellow, benzidine yellow, and pyrazolone red; soluble azo pigments such as lithol red, helio bordeaux, pigment scarlet, and permanent red 2B; alizarin, indanthrone, thio Derivatives from vat dyes such as indigo maroon; phthalocyanine pigments such as phthalocyanine blue and phthalocyanine green; quinacridone pigments such as quinacridone red and quinacridone magenta; perylene pigments such as perylene red and perylene scarlet; isoindolinone yellow, iso Isoindolinone pigments such as indolinone orange; imidazolones such as benzimidazolone yellow, benzimidazolone orange, and benzimidazolone red Materials: Pilanthrone pigments such as pyranthrone red and pyranthrone orange; thioindigo pigments; condensed azo pigments; flavanthrone yellow, acylamide yellow, quinophthalone yellow, nickel azo yellow, copper azomethine yellow, perinone orange, anthrone orange, Other pigments such as dianthraquinonyl red and dioxazine violet can be mentioned.

Specific examples of organic pigments include C.I. I. Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 120, 128, 129, 138, 139, 150, 151, 154, 155, 180, 185, 193, 199, 202, 213 and the like yellow pigments; I. Pigment Red 5, 7, 12, 48, 48: 1, 48: 2, 48: 3, 48: 4, 57, 58, 58: 1, 58: 2, 88, 112, 122, 123, 146, 149, Red pigments such as 150, 166, 168, 177, 178, 179, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 269, 272; I. Pigment Blue 1, 2, 3, 15, 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 22, 25, 60, 66, 80, and the like; C.I. I. Pigment Violet 19, 23, 29, 37, 38, 50, etc. Violet color pigments; C.I. I. Pigment Orange 13, 16, 36, 38, 43, 64, 68, 69, 71, 73, etc. Orange to brown pigments; C.I. I. Pigment Green 7, 36, 54, 58, etc. green pigments; C.I. I. Pigment Black 1 or the like; a black pigment;

Examples of inorganic pigments include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides. In particular, carbon black is preferable as the black colorant. Examples of the carbon black include thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, and channel black. Among these, furnace black, lamp black, acetylene black, and channel black are preferable.

Specific examples of the carbon black, for example, Raven760ULTRA, Raven780ULTRA, Raven790ULTRA, Raven1060ULTRA, Raven1080ULTRA, Raven1170, Raven1190ULTRA II, Raven1200, Raven1250, Raven1255, Raven1500, Raven2000, Raven2500ULTRA, Raven3500, Raven5000ULTRA II, Raven5250, Raven5750, Raven7000 (or, (Manufactured by Columbia Carbon Co.); Monarch700, Monarch800, Monarch880, Monarch900, Monarch1000, Monarch1100, Mon rch1300, Monarch1400, Regal1330R, Regal1400R, Regal1660R, Moguul L (hereinafter, manufactured by Cabot Corporation); NEROX-305, Color Black FW1, Color Black FW2, ColorBlack FW200Vck, 160 180IQ, Printex 35, Printex U, Printex V, Printex 140U, Printex 140V, Special Black 4, Special Black 4A, Special Black 5, Special 6 or higher Made near De Carbon Inc.); MA7, MA8, MA100, MA600, MCF-88, No. 25, no. 33, no. 40, no. 47, no. 52, no. 900, no. 2300 (manufactured by Mitsubishi Chemical Corporation);

Examples of extender pigments include silica, calcium carbonate, talc, clay, barium sulfate, and white carbon. These extender pigments are not used alone and are usually used in combination with an inorganic pigment or an organic pigment. Examples of the purpose of use in combination include effects such as improvement of fluidity.

Examples of the disperse dye include azobenzene-based and anthraquinone-based disperse dyes.

Specific examples of disperse dyes include C.I. I. Dispers Yellow 9, 23, 33, 42, 49, 54, 58, 60, 64, 66, 71, 76, 79, 83, 86, 90, 93, 99, 114, 116, 119, 122, 126, 149, 160, 163, 165, 180, 183, 186, 198, 200, 211, 224, 226, 227, 231, 237; I. Dispers Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, 283; I. Dispers Orange 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, 97; C.I. I. Dispers Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, 79: 1; I. Dispers Blue 27, 56, 60, 79: 1, 87, 143, 165, 165: 1, 165: 2, 181, 185, 197, 202, 225, 257, 266, 267, 281, 341, 353, 354, 358, 364, 365, 368 and the like.

The dispersant contained in the colored dispersion is a copolymer of a monomer (A) that is styrene, a monomer (B) that is acrylic acid, and a monomer (C) that is a C4-C9 alkyl ester of acrylic acid, that is, A copolymer.
A copolymer obtained by using methacrylic acid or methacrylate ester as a monomer is not suitable as a dispersant because it cannot maintain a stable dispersion state even if it is contained in a colored dispersion.

Examples of the acrylic acid C4-C9 alkyl ester of the monomer (C) include those in which the alkyl portion is linear, branched or cyclic, and those having a linear or branched chain are preferred. The range of the carbon number of the alkyl moiety is usually C4-C9, preferably C4-C8.
Specific examples include, for example, linear alkyl moieties such as butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, and nonyl acrylate; 1-methylpropyl acrylate, isobutyl acrylate, t-butyl acrylate, 1- , 2-, or 3-methylbutyl acrylate, 1,1-, 1,2-, or 2,2-dimethylpropyl acrylate, 1-ethylpropyl acrylate, 1-, 2-, 3-, or 4-methylpentyl Acrylate, 1,1-, 1,2-, 2,2-, 1,3-, or 3,3-dimethylbutyl acrylate, 1- or 2-ethylbutyl acrylate, 1-isopropylpropyl acrylate, 1-2 -, 3-, 4-, or 5-methylhexyl acrylate 1,1-, 1,2-, 1,3-, 1,4-, 2,2-, 2,3-, 2,4-, 3,3-, 3,4-, or 4,4 -Alkyl moieties such as dimethylpentyl acrylate, 1-, 2-, or 3-ethylpentyl acrylate, 2-ethylhexyl acrylate, etc. are branched; alkyl moieties such as cyclobutyl acrylate, cyclopentyl acrylate, cyclohexyl acrylate are cyclic; Etc.
Among these, a monomer (C) selected from the group consisting of butyl acrylate and 2-ethylhexyl acrylate is preferable from the viewpoints of industrially stable supply and improved dispersion stability and printing density. The latter is more preferred.

The content ratio of the monomer (A), monomer (B), and monomer (C) in the dispersant is usually 20 to 60% for the monomer (A), 10 to 50% for the monomer (B), and 20 for the monomer (C). The monomer (A) is preferably 30 to 50%, the monomer (B) is 10 to 40%, and the monomer (C) is 30 to 50%.

The above dispersant has a mass average molecular weight of usually 8,000 to 100,000, preferably 8,000 to 50,000, more preferably 8,000 to 30,000, and even more preferably 10,000 to 30,000. Particularly preferably, it is in the range of 10,000 to 28,000.
When the weight average molecular weight of the dispersant is 8,000 or more, the storage stability of the colored dispersion or the ink composition is improved. Moreover, the increase in the viscosity of a colored dispersion liquid can be suppressed as a mass mean molecular weight is 100,000 or less. For this reason, when an ink composition containing such a colored dispersion is prepared, the free dispersant is prevented from adhering to the vicinity of the printer nozzle, and the ink ejection from the printer is improved. .

The acid value of the above dispersant is usually 50 to 400 mgKOH / g, preferably 100 to 300 mgKOH / g, more preferably 120 to 250 mgKOH / g. When the acid value of the dispersant is 50 mgKOH / g or more, the storage stability of the colored dispersion and the ink composition and the ink dischargeability from the printer are good. Further, when the acid value of the dispersant is 400 mgKOH / g or less, the storage stability of the colored dispersion or the ink composition is improved. The mass average molecular weight and the acid value can be measured by a known method.
As an example, the acid value can be calculated from the structural unit of the polymer, but it can also be obtained by titration with a dispersant dissolved in an appropriate solvent (for example, methyl ethyl ketone).

The dispersant can be produced by a known polymerization method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. Among these, the solution polymerization method is preferable.
As the solvent used in the solution polymerization method, a polar organic solvent having a high affinity with the dispersant produced by polymerization is preferable, and a solubility in water at 20 ° C. is preferably 50% or less, more preferably 5% or more. Further preferred.
Examples of the polar organic solvent include aliphatic alcohols such as ethanol, 1-propanol, isopropanol, 1-butanol and butoxyethanol; aromatics such as toluene and xylene; ketones such as methyl ethyl ketone and methyl isobutyl ketone; And esters such as ethyl acetate; glycol ethers such as propylene glycol monomethyl ether, diethylene glycol monobutyl ether, and triethylene glycol monomethyl ether; Of these, aliphatic alcohols, esters, and glycol ethers are preferred.
The colorant contained in the ink composition may be microencapsulated. Examples of the organic solvent used when microencapsulating the colorant include methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, butoxyethanol, or a mixed solvent of one or more of these and water. Of these, methyl ethyl ketone and methyl isobutyl ketone are preferred.

There is no restriction | limiting in particular in the polymerization initiator used in said polymerization method, Arbitrary compounds can be used suitably. Among them, a radical polymerization initiator is preferable. Examples of the polymerization initiator include known polymerization initiators such as azo compounds and organic peroxides.
Examples of the azo compound include 2,2′-azobis (isobutyronitrile) (AIBN), 2,2′-azobis (2-methylbutyronitrile) (AMBN), 2,2′-azobis (2 , 4-Dimethylvaleronitrile) (ADVN), 1,1′-azobis (1-cyclohexanecarbonitrile) (ACHN), dimethyl-2,2′-azobisisobutyrate (MAIB), 4,4′-azobis (4-cyanovaleric acid) (ACVA), 1,1′-azobis (1-acetoxy-1-phenylethane), 2,2′-azobis (2-methylbutyramide), 2,2′-azobis (4 -Methoxy-2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylamidinopropane) dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propyl Pan], 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis (2,4,4-trimethylpentane), 2-cyano-2-propyl Azoformamide, 2,2′-azobis (N-butyl-2-methylpropionamide), 2,2′-azobis (N-cyclohexyl-2-methylpropionamide) and the like can be mentioned.
Examples of the organic peroxide include benzoyl peroxide, dibenzoyl oxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxy Ethyl) peroxydicarbonate, t-butylperoxyoctoate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionylperoxide And diacetyl peroxide. These polymerization initiators can be used alone or in combination of two or more.

The amount of the polymerization initiator used is preferably 0.001 to 5 moles, more preferably 0.01 per mole of monomer (when there are a plurality of types of monomers, per mole of molecular weight determined from the monomer blended monomer ratio). ~ 2 moles.
When carrying out the polymerization reaction, known polymerization chain transfer agents such as mercaptans such as octyl mercaptan and 2-mercaptoethanol, thiuram disulfides and the like can be further added to the reaction system.

The reaction conditions for the polymerization reaction vary depending on the type of polymerization initiator, monomer, and solvent to be used, and it is difficult to say in general. Usually, the polymerization temperature is 30 to 150 ° C., preferably 50 to 100 ° C. The polymerization time is about 1 to 20 hours. Moreover, it is preferable to perform reaction in inert gas atmosphere, such as nitrogen gas and argon gas.
After completion of the polymerization reaction, the produced dispersant can be isolated from the reaction solution by a known method such as reprecipitation or solvent distillation. Further, the obtained polymer can be purified by repeating reprecipitation, membrane separation, chromatographic method, extraction method, etc. to remove unreacted monomers and the like.

Without isolating the dispersant generated by the polymerization reaction, the aqueous organic medium or the aqueous dispersion of the dispersant can be obtained by replacing the polar organic solvent, which is the reaction solvent, with an aqueous medium.
Examples of such a method include the following two methods.
Method 1:
A polymerization reaction is performed in a solvent azeotropic with water, and after the reaction is completed, a dispersant formed by adding water and a neutralizing agent is transferred to an aqueous layer, and the solvent is azeotroped with water to remove it. A method for obtaining an aqueous solution of a dispersant or an aqueous dispersion.
Method 2:
The composition of the ink composition is determined, for example, when a water-soluble organic solvent is contained, after performing a polymerization reaction using the water-soluble organic solvent as a reaction solvent, water and a neutralizing agent are added, and an aqueous solution of a dispersant is added. Alternatively, a method for obtaining an aqueous dispersion.
In the above method 2, the obtained aqueous solution or dispersion of the dispersant contains a water-soluble organic solvent. Thus, even if it contains a water-soluble organic solvent, as long as it contains water in this specification, it is called "an aqueous solution of a dispersant or an aqueous dispersion."
Examples of the neutralizing agent include the same “pH adjusting agent” in “ink preparation agent” described later.
One type of neutralizing agent may be used, or two or more types may be used in combination.

The amount of the neutralizing agent used can be calculated from the degree of neutralization. The degree of neutralization is usually 10 to 200%, preferably 20 to 150%, and more preferably 50 to 100%.
The degree of neutralization can be determined by the following formula.
Degree of neutralization (%) = {[weight of neutralizer (g) / equivalent of neutralizer] / (acid value of polymer × molecular weight of neutralizer) / (molecular weight of KOH × equivalent of neutralizer × 1000 ) × polymer weight (g)} × 100
For example, polymer acid value: 200 (mg number of KOH required to completely neutralize 1 g of polymer), polymer amount: 10 g, neutralizing agent triethanolamine (Mw 149.2, equivalent 1), triethanolamine amount: At 5 g, the neutralization degree can be calculated as 93.8% from the following calculation formula.
Degree of neutralization (%) = {5 g / (200 × 149.2 / 56 × 1000) × 10} × 100 = 93.8%

The ratio of the above dispersant to the colorant is usually 10 to 150%, preferably 10 to 60%, and more preferably 15 to 45% with respect to the colorant. By setting the use ratio of the dispersant in the above range, it is possible to prevent the storage stability of the colored dispersion from being lowered, the deterioration of the recorded image using the ink composition containing the colored dispersion, and the like.
Although it is difficult to determine the content of each component in the colored dispersion in general, from the viewpoint of improving the printing density when an ink composition is used,
The colorant is usually 5 to 60%, preferably 10 to 40%, more preferably 10 to 30%,
The dispersant is usually 2 to 40%, preferably 3 to 20%, more preferably 4 to 10%,
If necessary, the water-soluble organic solvent is usually 3 to 40%, preferably 5 to 20%,
The balance is water. In addition, all of these content are conversion values as solid content.

Examples of the water-soluble organic solvent contained in the ink composition include C1-C6 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, and tert-butanol; N, N-dimethylformamide, Carboxylic acid amides such as N, N-dimethylacetamide; Lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-methylpyrrolidin-2-one; 1,3-dimethylimidazolidin-2-one, 1, Cyclic ureas such as 3-dimethylhexahydropyrimido-2-one; ketones or ketoalcohols such as acetone, 2-methyl-2-hydroxypentan-4-one, ethylene carbonate; cyclic ethers such as tetrahydrofuran and dioxane; Ethylene glycol, diethylene glycol 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,4-butylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol (preferably molecular weight 400 , 800, 1540 or higher), mono-, oligo-, or polyalkylene glycols or thioglycols having C2-C6 alkylene units such as polypropylene glycol, thiodiglycol, dithiodiglycol, etc .; glycerin, diglycerin, hexane- C3-C9 polyol (triol) such as 1,2,6-triol and trimethylolpropane; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, Tylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol Glycol ethers such as ethylene glycol monobutyl ether, propylene glycol monopropyl ether, prolene glycol monobutyl ether, dipropylene glycol monomethyl ether (preferably mono, di, or triethylene glycol C1-C6 ether, and mono or dipropylene glycol C1- Selected from the group consisting of C4 ether 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 2-methyl-2,4-pentanediol, 2-ethyl- C5-C9 alkanediols such as 1,3-hexanediol and 2,4-diethyl-1,5-pentanediol; γ-butyrolactone, dimethyl sulfoxide and the like. These organic solvents may be used independently and may use 2 or more types together.

Among the above, as the water-soluble organic solvent, it is preferable to use at least one water-soluble organic solvent selected from the group consisting of glycol ether and alkanediol.
Among the above, the glycol ether is preferably ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, ethylene More preferred are glycol monoallyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and propylene glycol monopropyl ether.
Similarly, as the alkanediol, any of the above compounds is preferable.
The content of the water-soluble organic solvent is usually 0.5 to 50%, preferably 1.0 to 30%, more preferably 3 to 15% with respect to the total mass of the ink composition.

The ink composition preferably further contains a surfactant.
Examples of surfactants include known surfactants such as anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, silicone surfactants, and fluorosurfactants. Can be mentioned. Among these, at least one surfactant selected from the group consisting of anionic and nonionic surfactants is preferable.

Anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, polyoxyethylene dinonyl phenyl ether sulfates, polyoxyethylene lauryl. Ether sulfate, N-acyl amino acid or salt thereof, N-acylmethyl taurate, alkyl sulfate polyoxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester, Lauryl alcohol sulfate, alkylphenol phosphate, alkyl phosphate, alkylaryl sulfonate, diethyl sulfosulfonate, diethylhexyl sulfosilicate, dioctyl sulfosilicate, etc. It is below. Specific examples of commercially available products include, for example, Hightenol ^™ LA-10, LA-12, LA-16, NE-05, NE-15, NF-13, NF-17, Neohaitenol ^™ ECL- 30S, ECL-45 (above, manufactured by Daiichi Kogyo Seiyaku), Adeka Coal ^TM EC-8600 (manufactured by Adeka), Perex ^TM OT-P (manufactured by Kao) and the like.
Among these, polyoxyethylene dinonyl phenyl ether sulfate, polyoxyethylene lauryl ether sulfate, and dioctyl sulfosuccinate are preferable.
In the present specification, the superscript “TM” means a trademark.

Nonionic surfactants include polyoxyethylene nonyl phenyl ether, polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, polyoxyethylene acetylene Ether type such as glycol ether, polyoxyethylene distyrenated phenyl ether (for example, Sobutanol ^TM EP-5035, 7085, 9050 manufactured by Nippon Shokubai; Pluronic ^TM L-31, L-34, L-44 manufactured by Adeka; Kao Made in Emulgen ^{TM a-90,} etc.), polyoxyethylene oleate ester, polyoxyethylene distearate ester, sorbitan laurate, sorbitan monostearate Esters such as sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, polyoxyethylene stearate; 2,4,7,9-tetramethyl-5-decyne-4,7-diol, Acetylene glycol (alcohol) series such as 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyn-3-ol; both Surfynol ^TM 104 manufactured by Nisshin Chemical Co., Ltd. , 104PG50, 105PG50, 82, 420, 440, 465, 485; Olfine ^™ STG; polyglycol ether type (eg, TergItol ^™ 15-S-7 manufactured by SIGMA-ALDRICH) and the like.
Among these, surfinol, polyoxyethylene acetylene glycol ether, and polyoxyethylene distyrenated phenyl ether are preferable.

Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.

Amphoteric surfactants include lauryldimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amidopropyldimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, imidazoline derivatives, etc. Is mentioned.

Examples of the silicone surfactant include polyether-modified siloxane and polyether-modified polydimethylsiloxane. Specific examples of commercially available products include, for example, BYK-347 (polyether-modified siloxane); BYK-345, BYK-348, BYK-349 (polyether-modified polydimethylsiloxane) manufactured by BYK Chemie, Inc .; Etc.

Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group as a side chain. And polyoxyalkylene ether polymer compounds. As specific examples of commercially available products, for example, Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, Capstone FS-30, FS-31 (above, manufactured by DuPont) PF-151N, PF-154N (manufactured by Omninova); and the like.

When the ink composition contains a surfactant, the total content of the surfactant is usually 0.1 to 3%, preferably 0.3 to 1.5% with respect to the total mass of the ink composition. is there. When the content is 0.1% or more, an effect as a surfactant can be obtained, and when the content is 3% or less, the storage stability of the ink is improved.

The ink composition may further contain an ink preparation agent other than those described above, if necessary. Examples of such ink preparation agents include antiseptic / antifungal agents, pH adjusters, chelating reagents, rust preventives, water-soluble ultraviolet absorbers, antioxidants, water-soluble polymers, water-dispersible polymers, and antifoaming agents. Etc.
The total content of these ink preparation agents in the ink composition is approximately 0.05 to 30%.

Specific examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one and salts thereof. .

Specific examples of the preservative include, for example, organic sulfur, organic nitrogen sulfur, organic halogen, haloaryl sulfone, iodopropargyl, haloalkylthio, nitrile, pyridine, 8-oxyquinoline, benzo Thiazole, isothiazoline, dithiol, pyridine oxide, nitropropane, organotin, phenol, quaternary ammonium salt, triazine, thiazine, anilide, adamantane, dithiocarbamate, brominated indanone , Benzyl bromacetate compounds, inorganic salt compounds and the like. Specific examples of the organic halogen compound include, for example, sodium pentachlorophenol. Specific examples of the pyridine oxide compound include sodium 2-pyridinethiol-1-oxide. Specific examples of the isothiazoline-based compound include, for example, 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, and 5-chloro-2-methyl-4-isothiazoline-3- ON, 5-chloro-2-methyl-4-isothiazolin-3-one magnesium chloride, 5-chloro-2-methyl-4-isothiazolin-3-one calcium chloride, 2-methyl-4-isothiazolin-3-one calcium Examples include chloride. Specific examples of other antiseptic / antifungal agents include anhydrous sodium acetate, sodium sorbate, sodium benzoate, trade name, Proxel ^RTM GXL (S), Proxel ^RTM XL-2 (S), and the like.

As the pH adjuster, any substance can be used as long as it can control the pH of the ink in the range of, for example, 5 to 11 without adversely affecting the prepared ink. Specific examples thereof include, for example, mono-, di-, or triethanolamine; N-methyldiethanolamine; mono-, di-, or tripropanolamine; alkanolamines such as methylethanolamine, dimethylethanolamine; mono-, di-, or trimethylamine; Alkyl amines such as mono-, di-, or triethylamine; hydroxides of alkali metals such as lithium hydroxide, sodium hydroxide, potassium hydroxide; ammonium hydroxide (ammonia water); lithium carbonate, sodium carbonate, sodium bicarbonate, carbonic acid Examples include alkali metal carbonates such as potassium; alkali metal salts of organic acids such as sodium silicate and potassium acetate; inorganic bases such as disodium phosphate.

Specific examples of the chelating reagent include, for example, disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uracil diacetate and the like.

Specific examples of the rust preventive include, for example, acidic sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, dicyclohexylammonium nitrite and the like.

Specific examples of water-soluble ultraviolet absorbers include sulfonated benzophenone compounds, benzotriazole compounds, salicylic acid compounds, cinnamic acid compounds, and triazine compounds.

The water-soluble polymer compound is not particularly limited as long as it is a polymer that dissolves in water, but an anionic polymer and a nonionic polymer are preferable from the viewpoint of dispersion stability. Specific examples of the anionic polymer include cellulose derivatives such as carboxymethyl cellulose, acrylic acid derivatives such as polyacrylic acid, and polystyrene derivatives such as polystyrene sulfonate. Specific examples of the nonionic polymer include polyethylene glycol, polyvinyl alcohol, polyvinyl pyrrolidone, gelatin and the like.

The water-dispersible resin has a function of fixing the colorant in the ink composition to the recording material by forming a film at room temperature. The resin used for the water-dispersible resin is not particularly limited. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, vinyl chloride resin, acrylic styrene resin, acrylic silicone resin, styrene Examples thereof include butadiene resins.
The water-dispersible resin is used, for example, in the state of a resin emulsion dispersed in water as a continuous phase.
Some resin emulsions are commercially available. Specific examples thereof include, for example, Superflex ^™ 126, 130, 150, 170, 210, 420, 470, 820, 830, 890 (urethane resin emulsion, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.); Hydran ^™ HW-350, HW-178, HW-163, HW-171, AP-20, AP-30, WLS-201, WLS-210 (urethane resin emulsion, manufactured by DIC); 0569, 0850Z, 2108 (styrene-butadiene resin emulsion) AE980, AE981A, AE982, AE986B, AE104 (acrylic resin emulsion, manufactured by Etec); and the like.
When a water-dispersible resin is used, the content of the water-dispersible resin in the total mass of the ink composition is usually 0.5 to 20%, preferably 1 to 15%, more preferably 2 in terms of solid content. ~ 10%. By setting it to 0.5% or more, it becomes easy to obtain sufficient fixability to the recording material, and by setting it to 20% or less, there is no possibility of hindering normal ejection of ink droplets in ink jet recording. .

As specific examples of the antioxidant, for example, various organic and metal complex anti-fading agents can be used. Examples of the organic anti-fading agent include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, and heterocyclic rings. .

Specific examples of the antifoaming agent include silicone, silica mineral oil, olefin, and acetylene. Examples of commercially available antifoaming agents include Surfinol ^TM DF37, DF58, DF-110D, DF220, MD-20, and Olfine ^TM SK-14, all manufactured by Shin-Etsu Chemical Co., Ltd. These antifoaming agents may be used alone or in combination of two or more.
When an antifoaming agent is used, its addition amount is preferably 0.01 to 5%, more preferably 0.03 to 3%, and even more preferably 0.05 to 1% with respect to the total mass of the liquid to be added. . The effect as an antifoamer becomes favorable by setting it as 0.01% or more, and dispersion stability becomes favorable by setting it as 5% or less.

The ink composition contains at least the colored dispersion and a water-soluble organic solvent, and may further contain the ink preparation agent such as a surfactant as necessary. The remainder other than these is water.

When the ink composition is used for ink jet recording, it is preferable that the content of inorganic impurities such as metal cation chloride (for example, sodium chloride) and sulfate (for example, sodium sulfate) in the ink composition is small. Inorganic impurities are often mixed in the bulk of the colorant, and it is also preferable to purify the bulk as necessary. As a standard of the content of inorganic impurities, it is about 1% or less with respect to the total mass of the colorant, and the lower limit may be less than the detection limit of the analytical instrument, that is, 0%. As a method for removing inorganic impurities from the colorant, for example, a dried product of a dye or a wet cake is treated with a suitable water-soluble organic solvent (for example, C1-C4 alcohol such as methanol) and, if necessary, a water-soluble organic solvent. Desalting may be carried out by a method such as stirring in a mixed solvent with water, filtering and separating the precipitate, and drying; a method of exchanging and adsorbing inorganic impurities with an ion exchange resin;

The pH of the ink composition is usually preferably pH 7 to 11 and pH 8 to 10 for the purpose of improving storage stability and compatibility with ink jet printer members. The surface tension of the ink composition is usually 10 to 50 mN / m and preferably 20 to 40 mN / m. Further, the viscosity of the ink composition is usually 2 to 30 mPa · s, and preferably 3 to 20 mPa · s.
The pH and surface tension of the ink composition can be appropriately adjusted with a pH adjuster, a surfactant, a water-soluble organic solvent, or the like.

Although there is no restriction | limiting in particular in the manufacturing method of the said ink composition, It can manufacture efficiently by performing the following process 1 thru | or 3 grade | etc.,.
Step 1:
A step of obtaining a colored dispersion by dispersing the above-mentioned colorant, dispersant, water, and, if necessary, a mixture containing a water-soluble organic solvent and an ink regulator.
Step 2:
A step of adding the above-mentioned water-soluble organic solvent and, if necessary, an ink adjusting agent and water to the colored dispersion obtained in step 1 and mixing them to obtain an ink composition.
Step 3:
A step of finely filtering the ink composition obtained in step 2 to remove impurities such as coarse particles in the ink composition;
In addition, although said process 3 is not necessarily essential, when using the said ink composition for inkjet recording, it is preferable to perform process 3.

Examples of the dispersion treatment in Step 1 include a kneader such as a roll mill, a bead mill, a kneader, and an extruder; a high-pressure homogenizer [manufactured by Izumi Food Machinery Co., Ltd.], a minilab 8.3H type [manufactured by Rannie], and the like. Homovalve type high-pressure homogenizer; microfluidizer [manufactured by Microfluidics], nanomizer [manufactured by Nanomizer Co., Ltd.], optimizer [manufactured by Sugino Machine Co., Ltd.], Genus PY [manufactured by Shiramizu Chemical Co., Ltd.], DeBEE2000 [Japan BN And the like, a method of obtaining a colored dispersion by mixing well using a chamber-type high-pressure homogenizer such as “made by Co., Ltd.”; a high shear stirrer such as a homomixer or a dissolver;

The average particle size of the colorant in the colored dispersion is usually 200 nm or less, preferably 50 to 200 nm, more preferably 70 to 170 nm, further from the viewpoint of storage stability and dischargeability of the colored dispersion and the ink composition. The thickness is preferably 80 to 130 nm.
Further, in some cases, in addition to the average particle diameter, it is also preferable to measure the colorants D90 and D10.
The D90 of the colorant (the cumulative 90% value calculated from the small particle side in the scattering intensity frequency distribution) is usually 300 nm or less, preferably 250 nm, from the viewpoint of increasing the storage stability of the dispersion by reducing coarse particles. Hereinafter, it is more preferably 200 nm or less. The lower limit is preferably 100 nm or more from the viewpoint of ease of production.
D10 (a cumulative 10% value calculated from the small particle side in the scattering intensity frequency distribution) of the colorant is usually 10 nm or more, preferably from the viewpoint of print density and ease of production when an ink composition is used. Is 20 nm or more, more preferably 30 nm or more and 50 nm or less.

The step 2 is not particularly limited as long as each component is sufficiently mixed, but a high-speed stirrer such as a dissolver or a homomixer is preferable from the viewpoint of preparation time. In addition, the order of adding each component is not particularly limited, but for the purpose of reducing the aggregation action such as solvent shock, the water-soluble organic solvent and, if necessary, the ink preparation agent are dissolved in water, and then colored. It is also preferable to add a dispersion.

Step 3 is a step of filtering and separating coarse particles, dust, dust and the like in the ink composition for the purpose of preventing nozzle clogging of the ink jet printer. The opening diameter of the filter used for filtration is not particularly limited, but is usually about 0.5 to 10 μm, preferably about 1 to 3 μm.
The material of the filter is not particularly limited, but polypropylene, glass fiber and the like are preferable from the viewpoint of price and filtration efficiency.
The above-mentioned filter may be used alone for filtration, and it is also preferable to perform filtration using two or more types of filters.

The ink composition can be used in various fields. For example, it can be used for writing, printing, information recording, textile printing, and the like, and is particularly preferably used for inkjet recording.

The ink jet recording method is a method of performing recording by ejecting droplets of the ink composition in accordance with a recording signal and attaching them to a recording material. The ink nozzles used for recording are not particularly limited and can be appropriately selected according to the purpose.
As a method used in the above recording method, for example, a charge control method that ejects ink using electrostatic attraction force; a drop-on-demand method (pressure pulse method) that uses vibration pressure of a piezoelectric element; Acoustic ink jet system that irradiates ink by changing to beam and ejects ink using its radiation pressure; thermal ink jet that heats ink to form bubbles and uses generated pressure, that is, bubble jet (registered trademark) system Any known method such as; can be employed.
In addition, a method called a photo ink, which ejects a large amount of ink with a small pigment content in a small volume; a method which improves the image quality by using a plurality of inks having substantially the same hue and different pigment concentrations; colorless A method using a transparent ink is also included.

The recording material is not particularly limited, and examples thereof include information transmission sheets such as paper and films, fibers and cloths (cellulose, nylon, wool, etc.), leather, and color filter base materials. Among these, an information transmission sheet is preferable.
Examples of the information transmission sheet include those in which an ink receiving layer is provided on a substrate such as paper, synthetic paper, or film. The ink receiving layer is, for example, a method of impregnating or coating the base material with a cationic polymer; inorganic fine particles such as porous silica, alumina sol, and special ceramics together with a hydrophilic polymer such as polyvinyl alcohol and polyvinylpyrrolidone, and the surface of the base material. It is provided by the method of coating to; Those provided with such an ink receiving layer are usually called ink jet exclusive paper, ink jet exclusive film, glossy paper, gloss film and the like.
Since these sheets have high surface gloss and excellent water resistance, they are suitable for recording photographic images. Commercially available products of such sheets include, for example, Canon Inc. Product Name: Professional Photo Paper, Super Photo Paper, Glossy Gold and Matt Photo Paper; Seiko Epson Corporation Product Name: Photographic Paper Crispia (High Gloss) ), Photographic paper (gloss), photo matte paper; manufactured by Nippon Hewlett-Packard Co., Ltd., trade name: Advanced Photo Paper (gloss); manufactured by Fuji Film Co., Ltd., trade name: Painting Photo Finishing Pro;

As the information transmission sheet having no ink receiving layer, various papers such as coated paper and art paper used for gravure printing, offset printing, etc. (for example, Oji Paper's Foam Gloss TM, OK Top Coat TM Aurora Coat TM manufactured by Nippon Paper Industries Co., Ltd., Pearl Coat TM manufactured by Mitsubishi Paper Industries Co., Ltd.); cast coated paper used for label printing applications, and the like.
Examples of the information transmission sheet having no ink receiving layer include plain paper such as Npi70 manufactured by Nippon Paper Industries Co., Ltd. and PD-W70 manufactured by Mitsubishi Paper Industries Co., Ltd. Generally, plain paper is liable to cause ink bleeding (feathering) along the fiber direction of pulp exposed on the surface. Therefore, in many cases, a sizing agent of about 0.1% is added to the pulp weight in order to suppress bleeding of the water-based ink. Although the addition of this sizing agent has the effect of suppressing ink bleeding and improving the image quality, it lowers the permeation rate of the ink, and thus has the disadvantage of slowing the drying of the adhered ink. When the drying of the ink is delayed, for example, when performing double-sided printing, the image is soiled or disturbed due to poor drying of ink. However, by using the ink composition, a good recorded image can be obtained even with such plain paper.

When an information transmission sheet that does not have an ink receiving layer is used, a surface modification treatment is also preferably performed.
As the surface modification treatment, a known surface modification treatment selected from corona discharge treatment, plasma treatment, and flame treatment is preferable. Here, it is generally known that the effect of the surface modification treatment decreases with time. For this reason, the surface modification treatment step and the inkjet recording step are preferably performed continuously, and the surface modification treatment step is preferably performed immediately before the inkjet recording step.

The corona discharge treatment is a treatment method in which corona discharge is generated by applying a high voltage of several thousand volts between a grounded metal roll and a wire-like electrode placed at intervals of several millimeters.
By disposing and processing the information transmission sheet between the electrode and the roll during corona discharge, the surface is hydrophilized.

In the plasma treatment, the information transmission sheet is placed in a container containing argon, neon, helium, nitrogen, nitrogen dioxide, oxygen, air, etc., exposed to plasma generated by glow discharge, and the surface contains oxygen, nitrogen, etc. Hydrophilic treatment is performed by introducing a group. When an inert gas such as argon or neon is present at a low pressure, it is considered that radicals are generated on the surface of the information transmission sheet by the plasma. Then, it is considered that radicals are combined with oxygen by being exposed to air, and carboxylic acid groups, carbonyl groups, amino groups, and the like are introduced to the surface of the sheet.

The flame treatment is also referred to as flame treatment, which is a treatment for improving hydrophilicity by spraying a gas oxidation flame or the like sprayed from a burner or the like on the surface of the information transmission sheet and oxidizing the surface.

The above surface modification treatment can be performed by appropriately adjusting the number of treatments; treatment time; applied voltage; etc. so as to obtain a desired effect.

The colored body means a substance colored with the ink composition, and the material is not particularly limited as long as it is a substance colored with the ink. Preferably, the recording material is colored by the inkjet recording method.

When recording on a recording material by the inkjet recording method, for example, a container containing the ink composition may be loaded at a predetermined position of an inkjet printer and recording may be performed by the recording method described above.

The said ink composition can be made into the ink composition of each color by selecting the coloring agent to contain. For example, full color recording can be performed as an ink set including at least four types of inks of black, cyan, magenta, and yellow. The ink set is an ink set in which at least one of the four types of ink is the ink composition.
Moreover, in order to express a richer color etc., the said ink set may further use together the ink composition of each color, such as green, blue (or violet), and red (or orange), as needed. .
The ink composition of each color is injected into each container, and each container is loaded into a predetermined position of the ink jet printer to perform ink jet recording.

The colored dispersion of the present invention has good storage stability, and the ink composition of the present invention containing it has good storage stability, small changes in ink viscosity and particle diameter during storage, and ejection with an inkjet printer. The performance does not change over a long period of time, and furthermore, the filterability and redispersibility are good, so that when used for ink jet recording, no ejection failure or nozzle clogging occurs even if used for a long period of time. In addition, not only inkjet paper but also printed matter on plain paper, the print density is high, water fastness, light fastness, high fastness such as rubbing resistance, etc., high quality and excellent image stability Is obtained. Furthermore, even when the type of paper is changed, a printed matter with small hue change and high color stability can be obtained.

EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited at all by the following example.
Unless otherwise specified, when filtration / separation was performed, suction filtration was performed using glass filter paper GC-50 and glass filter paper GA-100 as filter paper, either alone or in combination as appropriate.
When measuring the content of the colorant in the total mass of the colored dispersion, it was determined by a dry weight method using a moisture meter MS-70 manufactured by A & D Corporation.
For measuring the viscosity, a RE105L viscometer (manufactured by Toki Sangyo Co., Ltd.) was used.
Further, when the desired amount of product was not obtained by one synthesis or the like, the same operation was repeated until the desired amount was obtained.

(A) Synthesis of dispersant and preparation of dispersant solvent solution [Synthesis Example 1]
Into a 1 L flask equipped with a reflux condenser, a dropping funnel and a stirrer, nitrogen was allowed to flow at 0.02 L / min to form a nitrogen atmosphere, and 126.0 parts of isopropanol and 84.0 parts of ethyl acetate were added and stirred. Heated to 88 ° C. To this liquid, a monomer solution consisting of 115.5 parts of styrene, 115.2 parts of butyl acrylate, 69.3 parts of acrylic acid, 36.0 parts of isopropanol, and 24.0 parts of ethyl acetate was dropped over 3 hours. . On the other hand, a solution consisting of 13.5 parts of perbutyl O (manufactured by NOF), 18.0 parts of isopropanol, and 12.0 parts of ethyl acetate was dropped into the same solution over 3 hours in parallel with the dropping of the monomer solution. . After completion of the dropwise addition of each solution, the reaction was carried out at the same temperature for 1 hour. A solution consisting of 3.0 parts of perbutyl O (manufactured by NOF) and 15.0 parts of propylene glycol monomethyl ether was added to the obtained liquid, and the mixture was further reacted at the same temperature for 3 hours. By adding 81.0 parts of isopropanol and 54.0 parts of ethyl acetate to the obtained liquid and cooling to room temperature, a solvent of a dispersant having a solid content of 39.5% and an acid value of 177 mgKOH / g (in terms of solid content) A solution was obtained. The obtained solvent solution is designated as “dispersant solution 1”.

[Synthesis Example 2]
Into a 1 L flask equipped with a reflux condenser, a dropping funnel and a stirrer, nitrogen was allowed to flow at 0.02 L / min to form a nitrogen atmosphere, and 126.0 parts of isopropanol and 84.0 parts of ethyl acetate were added and stirred. Heated to 88 ° C. To this solution, a monomer solution consisting of 115.5 parts of styrene, 115.2 parts of 2-ethylhexyl acrylate, 69.3 parts of acrylic acid, 36.0 parts of isopropanol, and 24.0 parts of ethyl acetate was added over 3 hours. It was dripped. On the other hand, a solution consisting of 13.5 parts of perbutyl O (manufactured by NOF), 18.0 parts of isopropanol, and 12.0 parts of ethyl acetate was dropped into the same solution over 3 hours in parallel with the dropping of the monomer solution. . After completion of the dropwise addition of each solution, the reaction was carried out at the same temperature for 1 hour. A solution consisting of 3.0 parts of perbutyl O (manufactured by NOF) and 15.0 parts of propylene glycol monomethyl ether was added to the obtained liquid, and the mixture was further reacted at the same temperature for 3 hours. By adding 81.0 parts of isopropanol and 54.0 parts of ethyl acetate to the obtained liquid and cooling to room temperature, a dispersant having a solid content of 39.5% and an acid value of 176 mgKOH / g (in terms of solid content) was obtained. A solvent solution was obtained. The obtained solvent solution is designated as “dispersant solution 2”.

[Synthesis Examples 3 to 9]
Dispersant solutions 3 to 9 were obtained in the same manner as in Synthesis Examples 1 and 2 except that the monomers listed in Table 1 were used.
In Tables 1 to 4, the numerical values indicating the amount of each component are all “parts”, and “−” indicates that the component is not included.
The abbreviations used in Table 1 have the following meanings.
ST: Styrene BA: Butyl acrylate EHA: 2-ethylhexyl acrylate EHMA: 2-ethylhexyl methacrylate AA: Acrylic acid MA: Methacrylic acid PBO: Perbutyl O (t-butylperoxy-2-ethylhexanoate)
The “solid content” used as appropriate in Tables 1 to 6 means the solid content converted value of the dispersant contained in each dispersant solution, and the unit is “%”. Similarly, the unit of “acid value” is “mgKOH / g”, the unit of “average particle diameter” is “nm”, and the unit of “viscosity” is “mPa · s”.

(B) Preparation of aqueous dispersant solution [Preparation Example 1]
Dispersant solution 1 (150.8 parts), triethanolamine (72.1 parts), and purified water (159.8 parts) obtained in Synthesis Example 1 were placed in a 500 mL beaker and stirred to obtain a solution. Got. The obtained solution was transferred to a 1 L eggplant-shaped flask, and isopropanol, ethyl acetate, and a part of water were distilled off with an evaporator (−90 bar, 55 ° C.) to obtain an aqueous dispersant solution. The solid content of the resulting aqueous dispersant solution was calculated from the dry weight at 120 ° C. using the above moisture meter, and by adding ion-exchanged water, an aqueous solution of the dispersant having a dispersant content of 20% was obtained. Prepared. The resulting aqueous solution of the dispersant is referred to as “dispersant aqueous solution 1”.

[Preparation Examples 2 to 11]
Dispersant aqueous solutions 2 to 11 were obtained in the same manner as in Preparation Example 1, except that the respective components listed in Table 2 were used.
In the aqueous dispersant solutions 1 to 11 prepared as described above, the neutralization degree of the dispersant contained in each aqueous solution is 1.0, and the content of the dispersant is 20%.

(C) Preparation of colored dispersion [Example 1]
C. I. Pigment Red 122 (Alpa Fast Pink E AS-2709-S manufactured by MEGHMANI PIGMENTS, 25 parts), Dispersant Aqueous Solution 1 (37.5 parts) obtained in Preparation Example 1 above, diethylene glycol (10.0 parts), Orphine SK-14 (0.02 part) was mixed, and dispersed with a sand grinder at 2000 rpm for 15 hours. The obtained liquid was diluted with 159.8 parts of purified water, and the dispersion beads were separated by filtration to prepare a magenta colored dispersion. The resulting colored dispersion is designated as “Colored dispersion 1”.
The content of the colorant in the total mass of the dispersion 1 was 15%. The average particle diameter of the colorant in the colored dispersion 1 was 94 nm, and the viscosity was 3.1 mPa · s.

[Examples 2 to 7]
Colored dispersions 2 to 7 were obtained in the same manner as in Example 1 except that the respective components listed in Table 3 below were used.

[Comparative Examples 1 to 7]
Colored dispersions 8 to 14 were obtained in the same manner as in Example 1 except that each component described in Table 3 below was used.
In the colored dispersions of Examples and Comparative Examples obtained as described above, the content of the colorant contained in each colored dispersion is 15%, and the ratio of the dispersant to the colorant is 30%.
In Table 3 below, “PY151” means “CI Pigment Yellow 151”.

(D) Preparation of ink composition [Example 8]
Colored dispersion 1 (33.3 parts) obtained in Example 1 above, glycerin (22.0 parts), triethylene glycol (8.0 parts), 2-pyrrolidone (9.0 parts), diethylene glycol monobutyl ether ( 1.0 part), Surfynol ^TM 465 (0.7 part), Haitenol LA-16 (0.3 part), Surfynol ^TM DF-110D (0.01 part), and Triethanolamine (0.2 part) The ink composition of Example 8 was obtained by filtering out impurities with a 3 μm membrane filter. All ink compositions were adjusted so that the total content of the colorant was 5%.

[Examples 9 to 14]
Ink compositions of Examples 9 to 14 were obtained in the same manner as in Example 8, except that the respective components listed in Table 4 were used.

[Comparative Examples 8 to 11]
Ink compositions of Comparative Examples 8 to 11 were obtained in the same manner as in Example 8, except that the components shown in Table 4 below were used. In addition, the colored dispersions of Comparative Examples 1 and 2 gelled after storage in “(G) Storage Stability Test” described below, and the colored dispersion of Comparative Example 3 had an increase in viscosity after storage. Since the storage stability as a colored dispersion was extremely poor, they were not used for preparing the ink composition.
The ink compositions of Examples and Comparative Examples prepared as described above were adjusted so that the colorant content was 5%.
In addition, “DGMBE” described in Table 4 below means “diethylene glycol monobutyl ether”.

[Measurement of Physical Properties of Colored Dispersion and Ink Composition]
The average particle diameter and the viscosity were measured as the physical properties of the colored dispersions and ink compositions of the above Examples and Comparative Examples.
(E) Measurement of average particle diameter Immediately after the preparation of each colored dispersion obtained in Examples and Comparative Examples, and after storing in a sealed container at 70 ° C. for 5 days or 60 ° C. for 7 days, two samples each In Example 1, the color dispersion was diluted with ion-exchanged water so that the concentration of the dye component was 0.02%, and each test solution of Examples and Comparative Examples was prepared. About each obtained test liquid, the average particle diameter was measured. For measurement of the average particle size, a dynamic light scattering particle size distribution measuring device LB-500 (manufactured by Horiba, Ltd.) was used.

(F) Measurement of Viscosity For each colored dispersion obtained in Examples and Comparative Examples, immediately after preparation of the colored dispersion and after storage in a sealed container at 70 ° C. for 5 days or 60 ° C. for 7 days, 25 ° C. The viscosities were measured respectively.
An E-type viscometer RE105L (manufactured by Toki Sangyo Co., Ltd.) was used for measuring the viscosity.

(G) Storage Stability Test Regarding the average particle diameter and viscosity measured in the above (E) and (F), the change rate of each measured value immediately after preparation and after storage at 70 ° C. for 5 days or 60 ° C. for 7 days is shown below. It was calculated by the equation and evaluated according to the following four criteria A to D.
The smaller the difference between the measured values immediately after preparation and after storage for 5 days, the better the storage stability, and the better the storage stability. The storage stability was determined as a comprehensive judgment based on the criteria with the worst evaluation results.
As described above, the colored dispersants of Comparative Examples 1 and 2 gelled after storage, and the colored dispersion of Comparative Example 3 had a very large increase in viscosity after storage, both of which had very poor storage stability. For 1 and 2, the average particle size and viscosity were not measured, and for Comparative Example 3, the average particle size was not measured.
Average particle diameter or viscosity change rate = (measured value after storage−measured value immediately after preparation) / (measured value immediately after preparation) × 100%
A: Change rate is less than ± 5% B: Change rate is ± 5% or more, less than ± 10% C: Change rate is ± 10% or more, less than ± 15% D: Change rate is ± 15% or more, ± 20% Less than

(H) Redispersibility test Each of the ink compositions of the above Examples and Comparative Examples was placed on a glass petri dish by 25 μL, and dried for 1 hour with a 60 ° C. constant temperature and humidity machine. To the obtained dried ink composition, 10 mL of ion-exchanged water was dropped at room temperature, and whether or not it was redispersed was visually observed and evaluated according to the following four criteria. The re-dispersed ink is more excellent because it is easier to eliminate clogging after drying. The results are shown in Table 6 below.
A: All was redispersed without residue.
B: A little residue remains, but most are redispersed.
C: A lot of residue remains but is slightly redispersed.
D: Not redispersed at all.

(I) Filterability test 100 g of the colored dispersions of the above examples and comparative examples were filtered through glass filter paper GC-50 and glass filter paper GA-100, and the state of filtration was visually observed. The evaluation was made according to a three-stage standard.
A: Both GC-50 and GA-100 can be filtered without clogging.
B: Although clogging occurs with GC-50, it can be filtered without clogging with GA-100.
C: Both GC-50 and GA-100 are clogged and cannot be filtered.

(J) Evaluation of color development The ink compositions of the above Examples and Comparative Examples were solid-printed on the following two types of recording materials using a commercially available ink jet printer (PX-101 manufactured by Epson Corporation). The obtained colored product was used as a test piece, and the color developability (print density) was evaluated by a colorimeter (SpectroEye manufactured by X-Rite) according to the following three evaluation criteria. The results are shown in Table 6 below.
A: Print density is 1.2 or more B: Print density is 0.9 or more and less than 1.2 C: Print density is less than 0.9 [Recording material]
Plain paper 1: Npi70 from Nippon Paper Industries
Plain paper 2: PD-W70 manufactured by Mitsubishi Paper Industries

Table 5 below shows the evaluation results of the colored dispersion.

From the above results, it was revealed that the colored dispersions of the respective examples were excellent in storage stability and filterability.

On the other hand, each of the colored dispersions of Comparative Examples, except for Comparative Examples 5 to 7, had a drastic change in physical property values such as an increase in viscosity after storage, and the storage stability was poor.

Table 6 below shows the evaluation results of the ink composition.

From the above results, it was revealed that the ink compositions of Examples 8 to 14 were significantly superior in storage stability and redispersibility as compared with the ink compositions of Comparative Examples 8 to 11. High storage stability indicates that the physical property value of the ink composition does not change over a long period of time, and ensures stable ejection performance and stable image quality. In addition, good redispersibility indicates that even when the ink is dried on the head nozzle surface, the nozzles are not clogged, and ejection abnormalities such as ejection bending and non-ejection do not occur. It is clear that it has very high reliability.

Also, in terms of color developability, the ink compositions of Examples 8 to 14 were superior to Comparative Examples 8 to 11, indicating that the quality of the printed matter was excellent.

As described above, when the ink compositions of Examples 9 to 16 are used as ink-jet inks, it is clear that the ink composition is not only high in print quality but can provide the print quality over a long period of time. It became.

The colored dispersion of the present invention is very excellent in storage stability and filterability, and the ink composition using the colored dispersion is excellent in storage stability, redispersibility and color developability, and the reliability of inkjet ink. The nature is extremely high. Further, since it is possible to provide a high-quality printed material for a long period of time, it is extremely useful as an ink for inkjet recording.

Claims

A colored dispersion containing water, a colorant, and a dispersant, wherein the dispersant is a copolymer of the following monomers (A), (B), and (C).
Monomer (A): Styrene.
Monomer (B): acrylic acid.
Monomer (C): C4-C9 alkyl ester of acrylic acid.
The colored dispersion according to claim 1, wherein the dispersant has a mass average molecular weight of 8,000 to 100,000 and an acid value of 50 to 400 mg / KOH.
The colored dispersion according to claim 1 or 2, wherein the dispersant has a mass average molecular weight of 8,000 to 50,000 and an acid value of 100 to 300 mg / KOH.
The colored dispersion according to any one of claims 1 to 3, wherein the monomer (C) is 2-ethylhexyl acrylate.
The colored dispersion according to any one of claims 1 to 4, wherein the colorant is a colorant substantially insoluble in water.
6. The colored dispersion according to claim 1, wherein the colorant is at least one colorant selected from the group consisting of organic pigments, inorganic pigments, and carbon black.
An ink composition comprising the colored dispersion according to any one of claims 1 to 6 and a water-soluble organic solvent.
The ink composition according to claim 7, further comprising a surfactant.
The ink composition according to claim 7 or 8, wherein the water-soluble organic solvent is at least one selected from the group consisting of glycol ethers and alkanediols.
The glycol ether is selected from the group consisting of ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, and propylene glycol monopropyl ether. The ink composition according to claim 9, wherein the ink composition is at least one kind.
The alkanediol is 1,2-pentanediol, 1,2-hexanediol, 2-methyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, and 2,4-diethyl-1, The ink composition according to claim 9 or 10, which is at least one selected from the group consisting of 5-pentanediol.
The ink composition according to claim 8, wherein the surfactant is at least one selected from the group consisting of an anionic surfactant and a nonionic surfactant.
The ink composition according to claim 12, wherein the anionic surfactant is at least one selected from the group consisting of polyoxyethylene dinonyl phenyl ether sulfate, polyoxyethylene lauryl ether sulfate, and dioctyl sulfosuccinate. object.
The ink composition according to claim 12 or 13, wherein the nonionic surface activity is at least one selected from the group consisting of polyoxyethylene acetylene glycol ether and polyoxyethylene distyrenated phenyl ether.
The ink composition according to any one of claims 7 to 14, which is used for inkjet recording.
15. An ink jet recording method for performing recording by ejecting the droplets of the ink composition according to any one of claims 7 to 14 in accordance with a recording signal and attaching the droplets to a recording material.
The inkjet recording method according to claim 16, wherein the recording material is an information transmission sheet.
The ink jet recording method according to claim 17, wherein the information transmission sheet is a sheet having an ink receiving layer containing a porous white inorganic substance.
The inkjet recording method according to claim 17, wherein the information transmission sheet is cast-coated paper.
The inkjet recording method according to claim 17, wherein the information transmission sheet is coated paper or art paper.
21. The ink jet recording method according to claim 19 or 20, wherein the information transmission sheet is a sheet subjected to at least one kind of surface modification treatment selected from corona discharge treatment, plasma treatment, and frame treatment.
A colored body colored with the ink composition according to any one of claims 7 to 15.
An inkjet printer loaded with a container containing the ink composition according to any one of claims 7 to 14.
16. An ink set comprising four types of inks of black ink, cyan ink, magenta ink, and yellow ink, and at least one of the four types of ink is any one of claims 7 to 15. An ink set which is the ink composition described in 1.