Colored dispersion for inkjet, ink for inkjet recording, and inkjet recording method

Abstract

Provided are a colored dispersion for inkjet and a method for producing the same. The colored dispersion for inkjet contains a colorant, a dispersant, a tellurium compound, and water. The dispersant is an A-B block polymer, the monomers constituting the A block are (meth)acrylic acid and butyl (meth)acrylate, and the content of (meth)acrylic acid in the A block is 26 to 42% by mass. The monomers constituting the B block include cyclohexyl (meth)acrylate. The acid value of the dispersant is 100 to 159 mgKOH / g, and the mass average molecular weight of the dispersant is 10,000 to 50,000. In addition, provided are an inkjet recording ink containing the dispersion, an inkjet recording method using the ink, a recording medium having the ink attached thereto, and an inkjet printer having a container containing the ink loaded therein.

Description

Technical Field

[0001] The present invention relates to a colored dispersion for inkjet, an ink for inkjet recording containing the dispersion, and an inkjet recording method using the ink. Background Art

[0002] Among various color recording methods, a recording method using an inkjet printer (inkjet recording method) is one of the representative methods. It is a method of recording by generating ink droplets and attaching them to various recording media (paper, plastic film, cloth, etc.). This recording method has the characteristics of easy miniaturization and high speed, so it has rapidly spread in recent years and is expected to increase significantly in the future.

[0003] In the inkjet recording method, in addition to the recording medium with high ink absorption capacity such as inkjet paper, glossy paper, general plain paper, etc. with an ink receiving layer, sometimes the recording medium with low ink absorption capacity such as coated paper, plastic film, and ink non-absorbent recording medium that does not absorb ink at all is also used. When such ink absorption capacity or ink non-absorbent recording medium is printed with water-based inkjet ink, it will take a lot of time to dry because the ink is difficult to penetrate into the recording medium. Therefore, when the recording medium printed on the surface is reversed immediately in the inkjet printer and printed on the back side, and the high-speed automatic two-sided printing is performed, sometimes the problem of the reversal roller being contaminated due to the undried ink is generated.

[0004] In order to solve the above-mentioned problems, inks with high drying properties have been proposed. However, such inks with high drying properties are prone to clogging near the nozzles of the inkjet head. If the nozzles are clogged due to solids such as colorants and resin particles in the ink, the ink cannot be ejected stably, resulting in a significant reduction in the quality of the printed image.

[0005] Such a problem can be solved by improving the redispersibility of the ink after drying. This is because, even if the ink dries near the nozzle, if the dried ink is redispersed and clogging is not likely to occur using the ink newly supplied from the nozzle to the nozzle, the above problem can be solved and the ejection stability can be improved. In order to improve the redispersibility of aqueous inkjet ink, it is effective to increase the hydrophilicity of the dispersant that disperses the colorant in the ink. However, when the hydrophilicity of the dispersant is increased, the water resistance of the recorded image is reduced, and the image may be easily peeled off when water adheres to the printed material and is wiped. In this way, redispersibility and water resistance are opposite properties, and an ink that achieves both properties in a well-balanced manner is strongly required.

[0006] Patent Document 1 discloses an ink composition capable of forming an image having excellent adhesion, fixability, and water resistance on a recording medium that has poor ink absorption or non-ink absorption.

[0007] Patent Document 2 discloses an ink which exhibits good drying properties even when printed on a non-porous substrate and has high gloss, abrasion resistance, and ethanol resistance in the printed portion.

[0008] Prior art literature

[0009] Patent Literature

[0010] Patent Document 1: Japanese Patent Application Publication No. 2017-66215

[0011] Patent Document 2: Japanese Patent Application Publication No. 2014-240451 Summary of the invention

[0012] Problems to be solved by the invention

[0013] An object of the present invention is to provide a colored dispersion for inkjet which is excellent in redispersibility after drying and in water resistance of a recorded image, an inkjet recording ink containing the dispersion, and an inkjet recording method using the ink.

[0014] Means for solving problems

[0015] Specific means for solving the above-mentioned problems include the following embodiments.

[0016] 1) A coloring dispersion for inkjet, comprising a coloring agent, a dispersant, a tellurium compound and water,

[0017] The dispersant is an AB block polymer, wherein the monomers constituting the A block of the AB block polymer are (meth)acrylic acid and butyl (meth)acrylate, and the content of (meth)acrylic acid in the total mass of the monomers constituting the A block is 26 to 42% by mass, and the monomers constituting the B block of the AB block polymer include cyclohexyl (meth)acrylate,

[0018] The acid value of the above dispersant is 100 to 159 mgKOH / g,

[0019] The mass average molecular weight of the above dispersant is 10,000 to 50,000.

[0020] 2) The inkjet colored dispersion according to 1), wherein the total content of the tellurium compound in terms of metal tellurium is 160 ppm or less on a mass basis.

[0021] 3) The colored dispersion liquid for inkjet according to 1) or 2), wherein the acid value of the dispersant is 112 to 135 mgKOH / g.

[0022] 4) The colored dispersion liquid for inkjet according to any one of 1) to 3), wherein the mass average molecular weight of the dispersant is 10,000 to 30,000.

[0023] 5) The colored dispersion liquid for inkjet according to any one of 1) to 4), wherein the colorant is a colorant selected from the group consisting of pigments and disperse dyes.

[0024] 6) The colored dispersion for inkjet according to any one of 1) to 5), wherein the monomer constituting the B block of the AB block polymer comprises (meth)acrylic acid.

[0025] 7) An inkjet recording ink comprising the colored dispersion for inkjet according to any one of 1) to 6).

[0026] 8) An inkjet recording method comprising ejecting droplets of the inkjet recording ink described in 7) from an inkjet printer to perform recording on a recording medium.

[0027] 9) The inkjet recording method according to 8), wherein the recording medium is a poorly ink-absorbing or non-ink-absorbing recording medium.

[0028] 10) The inkjet recording method according to 9), wherein the recording medium is a recording medium subjected to at least one surface modification treatment selected from the group consisting of a corona discharge treatment, a plasma treatment, and a flame treatment.

[0029] 11) A recording medium colored with the ink for inkjet recording described in 7).

[0030] 12) An inkjet printer loaded with a container containing the ink for inkjet recording described in 7).

[0031] 13) The method for producing a colored dispersion liquid for inkjet according to any one of 1) to 6), comprising the step of coating the dispersant on the surface of the colorant.

[0032] 14) The production method according to 13), wherein the dispersant is coated on the surface of the colorant by a phase inversion emulsification method.

[0033] Effects of the Invention

[0034] According to the present invention, there can be provided a colored dispersion for inkjet which is excellent in redispersibility after drying and in water resistance of a recorded image, an inkjet recording ink containing the dispersion, and an inkjet recording method using the ink. DETAILED DESCRIPTION

[0035] Hereinafter, specific embodiments to which the present invention is applied will be described in detail.

[0036] In the present specification, each component contained in the inkjet coloring dispersion and the inkjet recording ink may be used alone or in combination of two or more.

[0037] In addition, the term "(meth)acrylic acid" in this specification is used to include both "acrylic acid" and "methacrylic acid". The same applies to "(meth)acrylate" and the like.

[0038] In the present specification, when a unit is described in only one of the upper and lower limits of a range such as "X to Y mass %", it means that the unit of the upper and lower limits of the range is the same, that is, "X mass % to Y mass %" or the like.

[0039] <Coloring Dispersion for Inkjet>

[0040] The inkjet colored dispersion (hereinafter, also referred to as "dispersion") according to the present embodiment contains a colorant, a dispersant, a tellurium compound and water, wherein the dispersant is an AB block polymer, the monomers constituting the A block of the AB block polymer are (meth)acrylic acid and butyl (meth)acrylate, and the content of (meth)acrylic acid in the total mass of the monomers constituting the A block is 26 to 42% by mass, the monomers constituting the B block of the AB block polymer include cyclohexyl (meth)acrylate, the acid value of the dispersant is 100 to 159 mgKOH / g, and the mass average molecular weight of the dispersant is 10000 to 50000. The components contained in the dispersion according to the present embodiment are described in detail below.

[0041] [Colorant]

[0042] The colorant contained in the dispersion liquid involved in this embodiment is not particularly limited as long as it is a water-insoluble colorant, and known pigments, disperse dyes, etc. can be used. In this specification, the so-called water-insoluble colorant refers to a colorant whose solubility in water at 25°C is usually 5g / L or less, preferably 3g / L or less, more preferably 1g / L or less, and further preferably 0.5g / L or less. The lower limit of solubility includes 0g / L. It should be noted that, unless otherwise specified, "colorant" refers to "water-insoluble colorant".

[0043] As the pigment, inorganic pigments, organic pigments, extender pigments, etc. can be mentioned, and any pigment can be used. In addition, these pigments can also be combined. For example, an extender pigment can also be added to an organic pigment to prepare a dispersion liquid.

[0044] Examples of the inorganic pigment include carbon black, titanium oxide, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides.

[0045] When a black dispersion is prepared, thermal black, acetylene black, oil-furnace black, gas-furnace black, lamp black, gas black, channel black, and other carbon blacks are preferred as inorganic pigments. Commercially available carbon blacks include, for example, Raven series manufactured by Columbia Carbon Company; Monarch series, Regal series, and Mogul series manufactured by Cabot Corporation; HiBlack series, ColorBlack series, Printex series, SpecialBlack series, and Nerox series manufactured by Orion Engineered Carbons; MA series, MCF series, No. 25, No. 33, No. 40, No. 47, No. 52, No. 900, and No. 2300 manufactured by Mitsubishi Chemical Corporation; and the like.

[0046] Examples of inorganic pigments other than carbon black include CI Pigment White 6 and 27; aluminum hydroxide; and the like.

[0047] As organic pigments, for example, various pigments such as azo, diazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perylone, thioindigo, anthraquinone, and quinophthalone can be cited. The organic pigment can also be used in combination with the above-mentioned inorganic pigment. For example, in order to improve the fluidity of the solid, the organic pigment can also be used in combination with a body pigment.

[0048] Specific examples of organic pigments include yellow pigments such as CI Pigment Yellow 1, 2, 3, 12, 13, 14, 16, 17, 24, 55, 73, 74, 75, 83, 93, 94, 95, 97, 98, 108, 114, 128, 129, 138, 139, 150, 151, 154, 180, 185, 193, 199, 202, and 213; CI Pigment Red 5, 7, 12, 48, 48:1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 168, 177, 178, 179, 9, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 269, 272 and other red pigments; CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, 80 and other blue pigments; CI Pigment Violet 19, 23, 29, 37, 38, 50 and other purple pigments; CI Pigment Orange 13, 16, 43, 68, 69, 71, 73 and other orange pigments; CI Pigment Green 7, 36, 54 and other green pigments; CI Pigment Black 1 and other black pigments; and so on.

[0049] Examples of the extender pigment include silica, calcium carbonate, talc, clay, barium sulfate, white carbon, etc. The extender pigment is often used in combination with other colorants.

[0050] Examples of the disperse dye include known disperse dyes, and among these, dyes selected from CI disperses (CI Dispers) are preferred. Specific examples thereof include yellow dyes such as CI Disperse 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, and 237; CI Disperse Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, 283 and other red dyes; CI Disperse Orange 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, 97 and other orange dyes; CI Disperse Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, 79:1 and other purple dyes; CI Disperse 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 other blue dyes; and so on.

[0051] The average particle size of the colorant is usually 50 to 300 nm, preferably 60 to 250 nm. The "average particle size" herein refers to the average particle size of particles measured using a laser scattering method.

[0052] The colorant is preferably coated with a dispersant on its surface. The term "coated" as used herein includes both a state where a portion of the colorant surface is coated with a dispersant and a state where the entire surface of the colorant is coated with a dispersant.

[0053] The content of the colorant relative to the total mass of the dispersion liquid involved in this embodiment is usually 0.1 to 30 mass%, preferably 0.5 to 20 mass%, and more preferably 1 to 15 mass%. In addition, the content of the colorant relative to the total mass of the ink involved in this embodiment described later is usually 1 to 30 mass%, preferably 1 to 10 mass%, and more preferably 2 to 7 mass%.

[0054] [Dispersant]

[0055] The dispersant contained in the dispersion liquid involved in this embodiment is an AB block polymer. The so-called AB block polymer refers to a polymer formed by chemically bonding an A polymer (hereinafter referred to as "A block") and a B polymer (hereinafter referred to as "B block"), and A and B respectively refer to polymers formed by one or more addition polymerizable monomers.

[0056] Hereinafter, the role of the AB block polymer (hereinafter also referred to as a "block copolymer") in the dispersion of the colorant will be described in detail.

[0057] As a method for stabilizing the dispersion of the colorant in water, a polymer dispersant such as a resin is usually used, and entropy repulsion, ion repulsion, or steric repulsion is used to hinder the aggregation of the colorants to stabilize the dispersion state. Here, the so-called polymer dispersant refers to a polymer having a hydrophilic part and a hydrophobic part, the hydrophobic part plays a role of adsorption on the surface of the colorant and the hydrophilic part plays a role of dispersion in water. As the above-mentioned polymer dispersant, a random polymer (hereinafter also referred to as a "random copolymer") in which the hydrophilic part and the hydrophobic part are irregularly arranged, and the above-mentioned block copolymer are mainly used.

[0058] Since the hydrophilic and hydrophobic parts of the random copolymer are arranged irregularly, they are sparsely adsorbed on the colorant surface, resulting in failure to fully cover the colorant surface. In addition, the affinity for liquid media such as water and water-soluble organic solvents is sometimes insufficient. If the dispersant is eroded by the solvent in the ink in this state, the dispersant is easily peeled off, which may cause aggregation of the colorant.

[0059] On the other hand, block copolymer is a structure formed by bonding a polymer that a hydrophilic part is continuously arranged with a hydrophobic part, and compared with random copolymer, it can be adsorbed on the colorant surface with a higher coating area, and the hydrophilic block has good affinity to the liquid medium, so even if it is eroded by a solvent, it is not easy to cause the disengagement of the dispersant, and a stable dispersion state can be maintained. In addition, block copolymer is hydrophilic compared with random copolymer, and even if the ink is dried near the nozzle, it is also easy to be redispersed by the ink newly supplied, and the effect of the blockage of the nozzle can be expected to be difficult to produce. On the other hand, because the dispersion stability of block copolymer is also high, even if the moisture in the ink evaporates first when drying on the recording medium and the relative solvent concentration in the ink becomes high, it is also possible to carry out film coating without causing the aggregation of the colorant. As a result, a film with high smoothness and surface coated with resin is formed, and the effect of high water resistance can be expected.

[0060] As a method for obtaining the above-mentioned block copolymer, the TERP (Organotellurium-Mediated Living Radical Polymerization) method using an organic tellurium compound is known. The TERP method will be described in detail below.

[0061] The so-called TERP method is a polymerization method for polymerizing a radical polymerizable compound (vinyl monomer) using an organic tellurium compound as a chain transfer agent, and is described in, for example, International Publication No. 2004 / 14848, International Publication No. 2004 / 14962, International Publication No. 2004 / 072126, and International Publication No. 2004 / 096870. Specific polymerization methods of the TERP method include the following (a) to (d).

[0062] (a) A vinyl monomer is polymerized using an organic tellurium compound represented by the following formula (1).

[0063] (b) A vinyl monomer is polymerized using a mixture of an organic tellurium compound represented by the following formula (1) and an azo polymerization initiator.

[0064] (c) A vinyl monomer is polymerized using a mixture of an organic tellurium compound represented by the following formula (1) and an organic ditellurium compound represented by the following formula (2).

[0065] (d) A vinyl monomer is polymerized using a mixture of an organic tellurium compound represented by the following formula (1), an azo polymerization initiator, and an organic ditellurium compound represented by the following formula (2).

[0066] [Chemical formula 1]

[0067]

[0068] R 1 -Te-Te-R 1 (2)

[0069] [In formula (1), R 1 R represents an alkyl group, an aryl group, or an aromatic heterocyclic group having 1 to 8 carbon atoms. 2 and R 3 Each independently represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. 4 represents an alkyl group, an aryl group, a substituted aryl group, an aromatic heterocyclic group, an alkoxy group, an acyl group, an amide group, an oxycarbonyl group, a cyano group, an allyl group, or a propargyl group having 1 to 8 carbon atoms. 1 represents an alkyl group, an aryl group, or an aromatic heterocyclic group having 1 to 8 carbon atoms.]

[0070] Specific examples of the organic tellurium compound represented by the above formula (1) include ethyl-2-methyl-2-n-butyl tellurium propionate, ethyl-2-n-butyl tellurium propionate, (2-hydroxyethyl)-2-methyl-methyl tellurium propionate, and the like, as well as compounds described in International Publication No. 2004 / 14848, International Publication No. 2004 / 14962, International Publication No. 2004 / 072126, and International Publication No. 2004 / 096870. Specific examples of the organic ditellurium compound represented by the above formula (2) include dimethyl ditellurium, dibutyl ditellurium, and the like. The azo polymerization initiator is not particularly limited as long as it is an azo polymerization initiator used in conventional free radical polymerization, and examples thereof include 2,2'-azobis(isobutyronitrile) (AIBN), 2,2'-azobis(2,4-dimethylvaleronitrile) (ADVN), 1,1'-azobis(1-cyclohexanecarbonitrile) (ACHN), and 2,2'-azobis(4-methoxy-2,4-dimethylvaleronitrile) (V-70).

[0071] In the polymerization step, the following substances are mixed in a container replaced with an inert gas: a vinyl monomer; an organic tellurium compound represented by the above formula (1); and, depending on the type of the vinyl monomer, an azo polymerization initiator and / or an organic ditellurium compound represented by the above formula (2) for the purpose of promoting the reaction, controlling the molecular weight, molecular weight distribution, etc. Examples of the inert gas include nitrogen, argon, and helium, preferably argon and nitrogen. The amount of the vinyl monomer used in the above (a) to (d) can be appropriately adjusted according to the physical properties of the target copolymer.

[0072] The polymerization reaction can be carried out under solvent-free conditions, but it is also possible to use aprotic solvents or protic solvents commonly used in free radical polymerization, and stir the above mixture to carry out. As aprotic solvents, for example, anisole, benzene, toluene, propylene glycol monomethyl ether acetate, ethyl acetate, tetrahydrofuran (THF), etc. can be mentioned. As protic solvents, for example, water, methanol, 1-methoxy-2-propanol, etc. can be mentioned. Solvents can be used alone or in combination of two or more. The amount of solvent used is not particularly limited, for example, preferably 0.01 to 50 mL relative to 1 g of vinyl monomer. The reaction temperature and reaction time can be appropriately adjusted according to the molecular weight and molecular weight distribution of the obtained copolymer, but are usually stirred at 0 to 150°C for 1 minute to 100 hours. After the polymerization reaction is completed, the target copolymer can be isolated by removing the solvent and residual vinyl monomer from the obtained reaction mixture by the usual separation and purification method.

[0073] The monomers constituting the A block of the AB block polymer are (meth) acrylic acid and (meth) butyl acrylate, preferably a combination of methacrylic acid and butyl methacrylate. In addition, the monomers constituting the B block of the AB block polymer include (meth) cyclohexyl acrylate, preferably cyclohexyl methacrylate. The A block having a hydrophilic portion dissolves in a liquid medium, and the B block having a hydrophobic portion is adsorbed on the surface of the colorant, thereby forming a stable dispersed state. The A block has a carboxyl group, and by neutralizing it with a neutralizer, it can be dissolved in a liquid medium. On the other hand, the B block is almost insoluble in a liquid medium, and is adsorbed on the surface of the colorant with strong hydrophobicity in the liquid medium to maintain a coated state. The (meth) cyclohexyl acrylate constituting the B block has a 6-membered monocyclic saturated hydrocarbon group, is highly hydrophobic, and has a soft molecular structure. Therefore, compared with planar cyclic aromatic hydrocarbons and polycyclic saturated hydrocarbons that are limited in the conformations that can be formed, various chemical surface modifications of the colorant can be made and the structure can be flexibly changed to allow adsorption through stronger interactions. As a result, strong dispersion stability can be obtained even if it is eroded by the solvent in the ink.

[0074] The content of (meth)acrylic acid in the total mass of the monomers constituting the A block is usually 26 to 42 mass %, preferably 31 to 40 mass %, more preferably 31 to 37 mass %, and further preferably 33 to 35 mass %. By setting the lower limit of the content to the above-mentioned respective set rates, sufficient hydrophilicity as a dispersant can be obtained, and there is a tendency that dispersion stability and redispersibility become good. In addition, by setting the upper limit of the content to the above-mentioned respective set rates, moderate hydrophilicity as a dispersant is maintained, and it is not easy for the dispersant to separate from the colorant, and there is a tendency that dispersion stability becomes good.

[0075] The content of cyclohexyl (meth)acrylate in the total mass of the monomers constituting the B block is generally 80 to 100 mass %, preferably 90 to 99.8 mass %, and more preferably 95 to 99 mass %. The monomers constituting the B block may also contain additional monomers. The content of the additional monomers is generally 0 to 20 mass %, preferably 0.2 to 10 mass %, and more preferably 1 to 5 mass % relative to the total mass of the monomers constituting the B block. The additional monomer is preferably (meth)acrylic acid. The content of (meth)acrylic acid in the total mass of the monomers constituting the B block is generally 0.1 to 10 mass %, preferably 0.5 to 5 mass %. By containing a small amount of hydrophilic (meth)acrylic acid in the hydrophobic B block, the flexibility of the structure of the dispersant in the liquid medium is increased, the adsorption of the colorant becomes easy, and there is a tendency to improve the dispersion stability.

[0076] The proportion of the A block in the AB block polymer is usually 10 to 90% by mass, preferably 20 to 80% by mass, and more preferably 30 to 70% by mass.

[0077] The acid value of the dispersant is 100 to 159 mgKOH / g, preferably 112 to 135 mgKOH / g. By setting the lower limit of the acid value to the above-mentioned set values, there is a tendency that sufficient solubility in the liquid medium can be obtained and redispersibility becomes good. In addition, by setting the upper limit of the acid value to the above-mentioned set values, there is a tendency that the water resistance and color development of the recorded image can be improved. It should be noted that the acid value of the dispersant is measured by the method described in the examples described later.

[0078] The mass average molecular weight of the dispersant is 10000 to 50000, preferably 10000 to 30000. By setting the mass average molecular weight to the above-mentioned ranges, the stability of the dispersion tends to be improved. The mass average molecular weight of the dispersant is measured by the method described in the examples described below.

[0079] The dispersant may be neutralized with a neutralizing agent to neutralize the acid group. Examples of the neutralizing agent include alkali metal hydroxides, alkaline earth metal hydroxides, ammonia, aliphatic amine compounds, and alcohol amine compounds.

[0080] Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, etc. Examples of alkaline earth metal hydroxides include beryllium hydroxide, magnesium hydroxide, calcium hydroxide, strontium hydroxide, etc. Among them, alkali metal hydroxides are preferred, and lithium hydroxide and sodium hydroxide are more preferred.

[0081] Ammonia is not particularly limited and may be a gas or a liquid dissolved in water or an organic solvent. Among them, aqueous ammonia is preferred.

[0082] Examples of the aliphatic amine compound include monomethylamine, dimethylamine, trimethylamine, monoethylamine, diethylamine, and triethylamine.

[0083] Examples of the alcoholamine compound include monoethanolamine, diethanolamine, triethanolamine, monopropanolamine, dipropanolamine, tripropanolamine, methylethanolamine, dimethylethanolamine, and N-methyldiethanolamine.

[0084] The neutralization degree is 100% when the total amount of the acid groups in the dispersant is neutralized with a theoretically equivalent amount of a neutralizing agent. The upper limit of the neutralization degree may exceed 100%. The neutralization degree of the dispersant is usually 30 to 200%, preferably 50 to 150%.

[0085] The total mass of the dispersant relative to the total mass of the colorant is generally expressed as a numerical value called a distribution ratio. The distribution ratio can be calculated by the following formula.

[0086] Dispersant ratio = total mass of dispersant / total mass of colorant

[0087] The dispersion liquid of this embodiment and the ink of this embodiment described later generally have a limit ratio of 0.1 to 1.0, preferably 0.1 to 0.6, and more preferably 0.1 to 0.5. By setting the limit ratio to the above-mentioned ranges, dispersion stability becomes good, and there is a tendency to suppress degradation of recorded images.

[0088] [Tellurium compounds from chain transfer agents]

[0089] The growing end of the block copolymer obtained by TERP is -TeR 1 (Where R 1 The tellurium atom is removed from the growth end by separation and purification after the polymerization reaction. After the removal of the tellurium atom, the tellurium compound derived from the chain transfer agent may remain in the block copolymer.

[0090] In this embodiment, the content of the tellurium compound from the chain transfer agent can be controlled by separating and purifying the block copolymer after the polymerization reaction. Therefore, the content of the tellurium compound from the chain transfer agent in the total mass of the dispersion is not particularly limited. The total content of the tellurium compound in terms of metal tellurium is 0.01 ppm or more, preferably 0.1 ppm or more, more preferably 1 ppm or more, and preferably 160 ppm or less, based on the mass.

[0091] [water]

[0092] The dispersion liquid involved in this embodiment is an aqueous dispersion liquid containing water. There is no limitation on the water that can be used, but water with few impurities such as inorganic ions is preferred. Examples of such water include ion-exchanged water and distilled water.

[0093] The content of water is usually 50 to 90% by mass, preferably 60 to 90% by mass, and more preferably 70 to 90% by mass, relative to the total mass of the dispersion liquid involved in the present embodiment. In addition, the content of water is usually 20 to 90% by mass, preferably 35 to 90% by mass, and more preferably 50 to 90% by mass, relative to the total mass of the ink involved in the present embodiment described later.

[0094] [Method for producing dispersion liquid]

[0095] The manufacturing method of the dispersion liquid involved in the present embodiment includes a process for dispersing a colorant. As a method for dispersing a colorant, a known method can be used. As an example thereof, methods such as a sand mill (bead mill), a roller mill, a ball mill, a paint agitator, an ultrasonic disperser, and a microfluidizer can be cited. In addition, preferably, after preparing the dispersion liquid, components with large particle sizes are removed by filtration, centrifugation, etc.

[0096] In order to suppress foaming when preparing the dispersion, a very small amount of defoamer can be added. Among them, there are also defoamers that hinder dispersion and micronization. It is preferable to use a defoamer that does not affect dispersion and stability after dispersion. As defoamers, for example, silicone-based defoamers and acetylene glycol-based defoamers can be mentioned. As silicone-based defoamers, for example, Surfinol DF-58 manufactured by Nissin Chemical Co., Ltd. and BYK1770 manufactured by BYK Chemie can be mentioned. As acetylene glycol-based defoamers, for example, Orfin SK-14 manufactured by Nissin Chemical Co., Ltd. can be mentioned.

[0097] Preferably, the method for producing a dispersion liquid according to the present embodiment further comprises a step of coating the surface of the colorant with a dispersant. Thus, a dispersion liquid containing a colorant whose surface is coated with a dispersant can be obtained. The step of coating the surface of the colorant with a dispersant can be performed after the step of dispersing the colorant, or can be performed simultaneously with the step of dispersing the colorant.

[0098] Methods for coating the surface of the colorant with a dispersant can be roughly divided into physical and mechanical methods and chemical methods. As specific methods, for example, any known method such as a surface precipitation method and an interfacial polymerization method (surface polymerization method) can be cited. Here, the so-called surface precipitation method refers to a method of adjusting the pH of a liquid medium containing a colorant; utilizing methods such as differences in the solubility of the colorant in the liquid medium to precipitate a dispersant on the surface of the colorant to coat the colorant. This method includes an acid precipitation method, a phase inversion emulsification method, and the like. The interfacial polymerization method is a method in which a compound having a polymerizable functional group such as a monomer, oligomer, or pigment derivative is adsorbed or bound to the surface of the colorant, and then polymerized with other monomers that form the dispersant to form a dispersant that covers the surface of the colorant. Among them, the surface precipitation method is preferred, and the phase inversion emulsification method is more preferred.

[0099] The phase inversion emulsification method is a method in which a colorant and a dispersant are mixed and dispersed in an organic solvent, and then water is added to uniformly adsorb the dispersant on the surface of the pigment. The following six methods are known as specific production processes.

[0100] 1. A process of mixing a solution of a hydrophilic organic solvent in which a colorant is dispersed and a dispersant is dispersed or dissolved in water with a liquid containing water as a main component, and then removing the solvent. It should be noted that components other than water in the "liquid containing water as a main component" include, for example, surfactants, preservatives, etc.

[0101] 2. A step of removing the solvent by mixing a solution of a hydrophilic organic solvent in which a colorant is dispersed and dispersed or dissolved in water by neutralization with a mixed liquid containing water and a neutralizing agent.

[0102] 3. A step of removing the solvent by mixing a solution of a mixed solvent of a hydrophilic organic solvent and a hydrophobic organic solvent in which a dispersant having a colorant dispersed therein or dissolved in water with a liquid having water as a main component.

[0103] 4. A step of removing the solvent by mixing a solution of a mixed solvent of a hydrophilic organic solvent and a hydrophobic organic solvent in which a dispersant in which a colorant is dispersed and dispersed or dissolved in water by neutralization with a mixed liquid containing water and a neutralizing agent.

[0104] 5. A process of mixing the colorant with a solution of a mixed solvent mainly composed of a hydrophilic organic solvent and water, which is a dispersant dispersed or dissolved in water, so that the pigment is dispersed in the solution, and then removing the solvent.

[0105] 6. A process of mixing a solution of a hydrophobic organic solvent in which a dispersant is dissolved with a liquid mainly composed of water and containing a neutralizer to prepare an emulsion (emulsion or microemulsion), adding a colorant thereto, mixing and dispersing, and then adding water to remove the solvent.

[0106] Examples of the organic solvent include alcohol solvents, ketone solvents, ether solvents, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents, halogenated aliphatic hydrocarbon solvents, etc. Examples of the alcohol solvent include methanol, ethanol, propanol, isopropanol, butanol, etc. Examples of the ketone solvent include acetone, 2-butanone, etc.

[0107] As the surfactant, for example, the above-mentioned defoaming agent can be used, and an amount that does not inhibit dispersion can be added even in the phase inversion emulsification method.

[0108] Examples of the preservative include organic sulfur compounds, organic nitrogen sulfur compounds, organic halogen compounds, halogenated aromatic sulfone compounds, iodopropargyl compounds, halogenated alkylthio compounds, nitrile compounds, pyridine compounds, 8-oxyquinoline compounds, benzothiazole compounds, isothiazolin compounds, dithiol compounds, pyridine oxide compounds, nitropropane compounds, organic tin compounds, phenol compounds, quaternary ammonium salt compounds, triazine compounds, thiazine compounds, aniline compounds, adamantane compounds, dithiocarbamate compounds, indanone bromide compounds, benzyl bromoacetate compounds, and inorganic salt compounds. Specific examples of commercially available preservatives include Proxel GXL (S) and Proxel XL-2 (S) manufactured by Arch Chemical Co., Ltd. and Roshima 640 manufactured by Dow Chemical Co., Ltd.

[0109] By using the above method, a colorant having a dispersant on the surface and an average particle size of 250 nm or less can be easily obtained. The average particle size of the colorant can be controlled by selecting the type of colorant; the type of dispersant, the acid value, the mass average molecular weight, etc. The average particle size of the colorant is usually 50 to 180 nm, preferably 60 to 150 nm.

[0110] <Inkjet Recording Ink>

[0111] The inkjet recording ink (hereinafter, also referred to as "ink") according to the present embodiment contains the dispersion liquid according to the present embodiment, and may further contain other ink modifiers as required. Examples of such ink modifiers include solvents, surfactants, preservatives, mildew inhibitors, pH adjusters, chelating agents, rust inhibitors, water-soluble ultraviolet absorbers, antioxidants, resin emulsions, wax agents, and slip agents.

[0112] As the solvent, an organic solvent is preferred. Examples of the organic solvent include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, tert-butanol, 1,2-hexanediol, 1,4-butanediol, 1,6-hexanediol, trimethylolpropane, hexane-1,2,6-triol and other C1-C6 alkanols having 1 to 3 hydroxyl groups; amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone and N-methylpyrrolidin-2-one; 1,3-dimethylimidazolidin-2-one, 1,3-dimethylhexahydropyridine- 2-ketone and other cyclic ureas; ketones or ketone alcohols such as acetone, 2-methyl-2-hydroxypentane-4-one, and ethylene carbonate; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol, diethylene glycol, propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,4-butanediol, 1,2-hexanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol or polypropylene glycol having a molecular weight of 400 or more, mono-, oligo-, or polyalkylene glycol or thioethylene glycol having a C2-C6 alkylene unit such as thiodiethylene glycol and dithiodiethylene glycol; glycerol Oil, diglycerol, hexane-1,2,6-triol, trimethylolpropane and other polyols (triols); ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether (butyl carbitol), triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monoallyl ether, ethylene glycol monoisopropyl ether, diethylene glycol monomethyl ether, propylene glycol n-butyl ether, propylene glycol monopropyl ether, triethylene glycol monobutyl ether, tripropylene glycol methyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, diethylene glycol Glycol ethers (preferably, alkyl ethers or alkenyl ethers of alkylene glycols having 1 to 5 (more preferably 1 to 4, further preferably 1 to 3) C2-C4 alkanediols as repeating units) such as alcohol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol dimethyl propylene ether, dipropylene glycol methyl ether, dipropylene glycol n-butyl ether, dipropylene glycol n-propyl ether, 3-methoxy-3-methyl-1-butanol, etc.; γ-butyrolactone, dimethyl sulfoxide, etc.

[0113] Among these solvents, solvents selected from glycol ethers and solvents selected from alkanols are preferred.

[0114] The content of the solvent is usually 3 to 50% by mass, preferably 5 to 40% by mass, based on the total mass of the ink.

[0115] As the above-mentioned solvent, not only a water-soluble organic solvent but also a water-insoluble organic solvent can be used. As the water-insoluble organic solvent, for example, a C8-C16 (preferably C8-12) alkyl having a hydroxyl group and an acyloxy group can be cited. As a specific example thereof, for example, Texanol can be cited. When using a water-insoluble organic solvent, in order to prevent separation from the ink, for example, it is preferable to adjust the content ratio with the water-soluble organic solvent.

[0116] The printing speed of industrial inkjet printers is usually variable. Therefore, it is preferable to appropriately adjust the surface tension of the ink according to the printing speed. The surface tension of the ink can be adjusted by a surfactant.

[0117] Examples of the surfactant include anionic, cationic, nonionic, amphoteric, silicone-based, and fluorine-based surfactants.

[0118] Examples of the anionic surfactant include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, N-acylamino acids or salts thereof, N-acylmethyl taurates, alkyl sulfate polyoxyalkyl ether sulfates, alkyl sulfate polyoxyethylene alkyl ether phosphates, rosin soaps, castor oil sulfate ester salts, lauryl sulfate ester salts, alkylphenol type phosphates, alkyl type phosphates, alkylaryl sulfonates, diethyl sulfosuccinates, diethylhexyl sulfosuccinates, dioctyl sulfosuccinates, and the like.

[0119] Examples of the cationic surfactant include 2-vinylpyridine derivatives and poly-4-vinylpyridine derivatives.

[0120] Examples of the amphoteric surfactant include lauryl dimethylaminoacetic acid betaine, 2-alkyl-N-carboxymethyl-N-hydroxyethylimidazolinium betaine, coconut oil fatty acid amide propyl dimethylaminoacetic acid betaine, polyoctylpolyaminoethylglycine, and imidazoline derivatives.

[0121] Examples of the nonionic surfactant include polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene tridecyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and polyoxyethylene alkyl ether; polyoxyethylene acylates such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate; polyoxyethylene aryl ethers such as polyoxyalkylene styrenated phenyl ether; acetylene glycol (alcohol) systems such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, and 3,5-dimethyl-1-hexyn-3-ol; polyglycol ether systems, and the like. Various types of nonionic surfactants can be easily purchased in the form of Surfinol series such as Surfinol 465 manufactured by Nissin Chemical Co., Ltd., Orfin series; Emargen series manufactured by Kao Corporation; New Call series manufactured by Nippon Emulsifier Co., Ltd.; and Neugen series manufactured by Daiichi Kogyo Seiyaku Co., Ltd.

[0122] As the silicone surfactant, for example, polyether-modified siloxane, polyether-modified polydimethylsiloxane, etc. can be cited. As one example, Dynol 960 and Dynol 980 manufactured by Air Products; Silface SAG001, Silface SAG002, Silface SAG003, Silface SAG005, Silface SAG503A, Silface SAG008, Silface SAG009, Silface SAG010 manufactured by Nissin Chemical Co., Ltd.; BYK-345, BYK-347, BYK-348, BYK-349, BYK-3450, BYK-3451, BYK-3455, BYK-LPX23288, BYK-LPX23347, BYK-LP G20726 manufactured by BYK Chemie; and the like.

[0123] As fluorine-based surfactants, for example, perfluoroalkylsulfonic acid compounds, perfluoroalkylcarboxylic acid compounds, perfluoroalkylphosphate compounds, perfluoroalkylethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in a side chain can be cited. As one example, Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, and Capstone manufactured by DuPont can be cited. FS-30, FS-31; PF-151N, PF-154N manufactured by OMNOVA; F-114, F-410, F-444, EXP.TF-2066, EXP.TF-2148, EXP.TF-2149, F-430, F-477, F-552, F-553, F-554, F-555, F-556, F-557, F-558, F-559, F-561, F-562, R-40, R-41, RS-72-K, RS-75, RS-76-E, RS-76-NS, RS-77, EXP.TF-1540, EXP.TF-1760 manufactured by DIC Corporation; BYK BYK-3440, BYK-3441 manufactured by Chemie, etc.

[0124] Among them, preferred are surfactants selected from nonionic and silicone-based surfactants.

[0125] As the preservative, the above-mentioned preservatives can be used in the same manner.

[0126] Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyrithione-1-oxide, ethyl p-hydroxybenzoate, 1,2-benzisothiazolin-3-one and salts thereof.

[0127] As the pH adjuster, any substance can be used as long as it does not adversely affect the prepared ink and can control the pH thereof to 5 to 11. Specific examples thereof include alkanolamines such as diethanolamine, triethanolamine, and N-methyldiethanolamine; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide (ammonia water); alkali metal carbonates such as lithium carbonate, sodium carbonate, sodium bicarbonate, and potassium carbonate; alkali metal salts of organic acids such as sodium silicate and potassium acetate; inorganic bases such as disodium phosphate; and the like.

[0128] Examples of the chelating agent include disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, sodium uracildiacetate, and the like.

[0129] Examples of the rust inhibitor include acidic sulfites, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

[0130] Examples of the water-soluble ultraviolet absorber include sulfonated benzophenone compounds, benzotriazole compounds, salicylic acid compounds, cinnamic acid compounds, and triazine compounds.

[0131] As the antioxidant, various organic and metal complex anti-fading agents can be used. Examples of organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromanes, alkoxyanilines, and heterocyclics.

[0132] In order to remove foreign matter, the ink of this embodiment is preferably subjected to microfiltration. When conducting microfiltration, a membrane filter, glass filter paper, etc. can be used. The pore size of the filter or the like when conducting microfiltration is usually 0.5 to 20 μm, preferably 0.5 to 10 μm.

[0133] From the viewpoint of improving storage stability, the pH of the ink involved in this embodiment is usually 5 to 11, preferably 6 to 10. The surface tension of the ink involved in this embodiment at 25°C is usually 10 to 50 mN / m, preferably 20 to 40 mN / m. The viscosity of the ink involved in this embodiment at 25°C is usually 30 mPa·s or less, preferably 20 mPa·s or less. The lower limit of the viscosity is not particularly limited, but is usually about 2 mPa·s.

[0134] <Inkjet recording method, recording medium, and inkjet printer>

[0135] The inkjet recording method according to the present embodiment is a method of performing recording on a recording medium by ejecting droplets of the ink according to the present embodiment described above from an inkjet printer.

[0136] There is no particular limitation on the ink nozzles and nozzles of the inkjet printer, and they can be appropriately selected according to the purpose. In recent years, circulating nozzles with a mechanism for preventing the ink near the nozzle from drying by circulating the ink near the nozzle have been widely developed. The inkjet recording method involved in this embodiment is also appropriately applicable to such nozzles.

[0137] As the inkjet recording method, a known method can be adopted. Specific examples of the inkjet recording method include, for example, a charge control method that uses electrostatic attraction to eject ink; a drop-on-demand inkjet method (also called a pressure pulse method) that uses vibration pressure of a piezoelectric element; an acoustic wave inkjet method that converts an electrical signal into a sound beam and irradiates the ink to eject the ink using its radiation pressure; a thermal inkjet method that heats the ink to form bubbles and uses the pressure generated; and the like.

[0138] The inkjet recording method also includes: a method of spraying a large amount of ink with a low colorant content, called light ink, in a small volume; a method of improving image quality by using a plurality of inks with different colorant contents in substantially the same hue; a method of improving the fixation of the colorant to the recording medium by combining colorless and transparent ink with ink containing a colorant; and the like.

[0139] There are no particular restrictions on the recording medium, but a recording medium that is poorly ink-absorbent or ink-non-absorbent is preferred. As a recording medium that is poorly ink-absorbent, for example, there can be mentioned ordinary paper without an ink-receiving layer; recording media used for gravure printing, offset printing, etc.; art paper, coated paper, matte paper, cast paper; and the like. In addition, as a recording medium that is non-ink-absorbent, there can be mentioned PET (polyethylene terephthalate) sheets, PP (polypropylene) sheets, vinyl chloride sheets, glass, rubber, and the like. It should be noted that the so-called recording medium that is poorly ink-absorbent or ink-non-absorbent refers to a recording medium having a surface with low water permeability, absorption, and / or adsorption, and also includes a material that does not open to the outside even if there are multiple cavities inside. More quantitatively speaking, it refers to the time from the beginning of contact to 30 msec in the Bristow method. 1 / 2 The water absorption is 10mL / m 2 The following recording media.

[0140] When the above-mentioned recording medium is used, a better image can be obtained by performing a surface modification treatment.

[0141] As the surface modification treatment, it is preferred to use a treatment selected from the group consisting of a corona discharge treatment, a plasma treatment, and a flame treatment. As far as the recording medium subjected to the surface modification treatment is concerned, it is generally known that its effect decreases over time. Therefore, it is preferred that the surface modification treatment of the recording medium and the inkjet recording of the recording medium are carried out continuously. In particular, it is preferred that the surface modification treatment of the recording medium is carried out immediately before the inkjet recording is carried out. As far as the surface modification treatment of the recording medium is concerned, it is also possible to change the strength of the effect of the surface treatment by adjusting the number of treatments, the treatment time, and the conditions of the treatment.

[0142] When recording on a recording medium using the inkjet recording method according to this embodiment, for example, a container containing the ink according to this embodiment can be loaded at a predetermined position of an inkjet printer, and recording can be performed on the recording medium using the above-described recording method.

[0143] The inkjet recording method involved in the present embodiment can also use the inks of the four colors of yellow, magenta, cyan and black and the inks of various colors such as green, blue (or purple), red (or orange) as needed. The inks of various colors can be injected into respective containers, and the containers are loaded into the prescribed positions of the inkjet printer for inkjet recording. For the purpose of increasing the printing speed, the industrial inkjet printer also preferably uses the structure of the line-type inkjet printer for single-pass printing. The ink involved in the present embodiment can also obtain excellent ejection properties under such printing conditions.

[0144] For all matters described above, a combination of preferred aspects is more preferred, and a combination of more preferred aspects is further preferred. The same applies to a combination of a preferred aspect and a more preferred aspect, and a combination of a more preferred aspect and a further preferred aspect.

[0145] Example

[0146] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the examples.

[0147] In the examples, "parts", "%" and "ppm" are all based on mass unless otherwise specified. Unless otherwise specified, the synthesis reactions, crystallization and other operations in the examples are all carried out under stirring. In addition, when it is necessary to measure the pigment solid content of the dispersion, MS-70 (manufactured by A&D Co., Ltd.) is used and the dry weight method is used to obtain it. It should be noted that the so-called pigment solid content in the examples refers to the conversion value of only the pigment solid content in the measured value obtained by the dry weight method.

[0148] In this example, the mass average molecular weight (Mw), molecular weight distribution (PDI), acid value, and polymerization rate of the block copolymer were evaluated by the following methods.

[0149] [Mass average molecular weight (Mw) and molecular weight distribution (PDI)]

[0150] Determined by gel permeation chromatography (GPC) using a high performance liquid chromatograph (manufactured by Tosoh Corporation, model: HLC-8320). Before measurement, the carboxyl groups of the measurement sample (polymerization product) were methylated using a trimethylsilyldiazomethane - hexane solution (concentration: 0.6 mol / L). Two TSKgel SuperMultipore HZ-H (Φ4.6 mm × 150 mm) (manufactured by Tosoh Corporation) were used as the chromatographic columns, tetrahydrofuran was used as the mobile phase, and a differential refractive index detector was used. The measurement conditions were set as follows: the column temperature was 40 °C, the sample concentration was 10 mg / mL, the sample injection volume was 10 μL, and the flow rate was 0.35 mL / min. Polystyrene (manufactured by Tosoh Corporation, TSK Standerd) was used as the standard substance to prepare a standard curve (calibration curve), and the weight average molecular weight (Mw) and number average molecular weight (Mn) were measured. The molecular weight distribution (PDI = Mw / Mn) was calculated based on these measured values.

[0151] [Acid value]

[0152] The acid value represents the mass of potassium hydroxide required to neutralize the acidic components per 1 g of the solid component. The measurement sample was dissolved in tetrahydrofuran, a few drops of phenolphthalein ethanol solution as an indicator were added, and neutralization titration was carried out with a 0.1 mol / L potassium hydroxide / 2-propanol solution. The acid value (A) was calculated using the following formula.

[0153] A = 56.11 × Vs × 0.1 × f / w

[0154] A: Acid value (mgKOH / g)

[0155] Vs: Usage amount of 0.1 mol / L potassium hydroxide / 2-propanol solution required for titration (mL)

[0156] f: Valence of 0.1 mol / L potassium hydroxide / propanol solution (Japanese: 力価)

[0157] w: Mass of the measurement sample (g) (converted to solid component)

[0158] [Polymerization rate]

[0159] Measured using a nuclear magnetic resonance (NMR) measurement device (manufactured by Bruker Corporation, model: AVANCE500 (frequency 500 MHz)) 1 1H-NMR (solvent: deuterated chloroform, internal standard: tetramethylsilane). For the obtained NMR spectrum, the integration ratio of the peaks from the vinyl group of the monomer and the ester side chain of the polymer was determined, and the polymerization rate of the monomer was calculated.

[0160] <Synthesis of dispersant (block copolymer)>

[0161] [Synthesis Example 1: Synthesis of Dispersant a]

[0162] In a nitrogen-substituted glove box, the B block monomer, ethyl-2-methyl-2-n-butyl telluryl-propionate (BTEE), dibutyl ditellurium (DBDT), 2,2'-azobis(isobutyronitrile) (AIBN), and methyl ethyl ketone (MEK) in the proportion shown in Table 1, which had been previously substituted with nitrogen, were loaded and reacted. The A block monomer in the proportion shown in Table 1, which had been previously substituted with nitrogen, was added to the reaction solution and reacted. After the reaction was completed, the reaction solution was diluted with THF and injected into heptane under stirring. The precipitated polymer was filtered and dried to obtain the target dispersant a. The obtained dispersant a was ashed and measured by inductively coupled plasma mass spectrometry (ICP / MS), and the total content of the tellurium compound was calculated in terms of metal tellurium. Mw was 18613, PDI was 1.22, acid value was 105 mgKOH / g, and the total content of tellurium compounds calculated as metal tellurium (hereinafter also referred to as "metal tellurium content") was 7519 ppm.

[0163] [Synthesis Examples 2 to 19: Synthesis of Dispersants b to s]

[0164] The same operation as in Synthesis Example 1 was performed except that the B block monomer and the A block monomer were used in the ratios shown in Tables 1 to 3, respectively, to obtain the corresponding dispersants b to s. The Mw, PDI, acid value, and metal tellurium content of the obtained dispersants b to s were the values ​​shown in Tables 1 to 3.

[0165] <Synthesis of dispersant (random copolymer)>

[0166] [Synthesis Example 20: Synthesis of Dispersant t]

[0167] In a nitrogen-substituted glove box, monomers, BTEE, DBDT, AIBN, and MEK in the proportions shown in Table 4, which had been previously substituted with nitrogen, were added and reacted. After the reaction was completed, the reaction solution was diluted with THF and injected into heptane under stirring. The precipitated polymer was filtered and dried to obtain the target dispersant t. The obtained dispersant t was ashed and measured by inductively coupled plasma mass spectrometry (ICP / MS), and the total content of tellurium compounds was calculated in terms of metal tellurium. Mw was 19603, PDI was 1.33, acid value was 121 mgKOH / g, and metal tellurium content was 297 ppm.

[0168] [Table 1]

[0169]

[0170] [Table 2]

[0171]

[0172] [Table 3]

[0173]

[0174] [Table 4]

[0175] The meanings of the abbreviations in Tables 1 to 4 are as follows.

[0176] BMA: Butyl Methacrylate

[0177] MAA: Methacrylic acid

[0178] CHMA: Cyclohexyl methacrylate

[0179] BzMA: benzyl methacrylate

[0180] IBXMA: Isobornyl methacrylate

[0181] DCPMA: Dicyclopentyl Methacrylate

[0182] <Preparation of dispersion>

[0183] [Preparation Example 1: Preparation of Dispersion Liquid a]

[0184] Dispersant a (5.4 parts) obtained in Synthesis Example 1 was dissolved in 2-butanone (12.5 parts) to prepare a uniform solution. A liquid obtained by dissolving 28% ammonia solution (0.6 parts) in ion exchange water (62.7 parts) was added thereto, and Surfinol DF-58 (manufactured by Nissin Chemical Industry Co., Ltd.) (0.3 parts) and Roshima 640 (manufactured by Dow Chemical Co., Ltd.) (0.5 parts) were added, and then stirred for 1 hour to prepare an emulsified solution in which the dispersant was dissolved. At this time, no crystals were precipitated. CI Pigment Red 122 (manufactured by Clariant, Ink Jet Magenta E02) (18.0 parts) was added thereto in such a manner that the fraction ratio became 0.3, and dispersed using a sand mill (manufactured by IMEX Co., Ltd., 6TSG-1 / 8 type). Dispersion was performed at 1500 rpm for 10 hours. Thereafter, ion exchange water (100 parts) was added dropwise, and the dispersion beads were removed by filtration. Then, 2-butanone and a portion of water were removed by reduced pressure distillation using an evaporator to obtain a dispersion a having a pigment solid content of 12%. Since the separation ratio was 0.3 as described above, the dispersant concentration in the dispersion a was calculated to be 3.6%, and since the metal tellurium content in the dispersant a was 7519 ppm as described above, the metal tellurium content in the total mass of the dispersion a was calculated to be 271 ppm.

[0185] [Preparation Examples 2 to 20: Preparation of Dispersions b to t]

[0186] In the same manner as in Preparation Example 1, the components described in the following Tables 5 to 7 were mixed to prepare dispersions b to t.

[0187] [Table 5]

[0188]

[0189] [Table 6]

[0190]

[0191] [Table 7]

[0192]

[0193] <Ink Preparation>

[0194] [Examples 1 to 12 and Comparative Examples 1 to 8]

[0195] The dispersions a to t obtained in the above-mentioned dispersion examples 1 to 20 and the components listed in Tables 8 to 10 were mixed and filtered through a syringe filter (MiniSart manufactured by Sartorius) with a pore size of 5 μm to obtain inks of Examples 1 to 12 and Comparative Examples 1 to 8. The remainder was adjusted with ion exchange water so that the pigment solid content of each ink was 5%.

[0196] [Table 8] [Table 9]

[0197] [Table 10]

[0198]

[0199] The meanings of the abbreviations in Tables 8 to 10 are as follows.

[0200] BYK3450: Silicone surfactant (manufactured by BYK Chemie)

[0201] <Preparation of transparent ink>

[0202] Dipropylene glycol n-propyl ether (30.0 parts), ethylene glycol monoisopropyl ether (30.0 parts), 3-methoxy-3-methyl-1-butanol (15.0 parts), BYK 3450 (manufactured by BYK Chemie) (2.1 parts), and ion exchange water (207.9 parts) were mixed and filtered through a membrane filter with a pore size of 0.45 μm (manufactured by Toyo Roshi Co., Ltd., Advantech Dismic-25CS) to obtain a colorless and transparent ink.

[0203] The transparent ink is a liquid composition obtained by removing the solid pigment components from the inks of the above-mentioned embodiments and comparative examples. Even if the ink dries near the nozzle of the inkjet head, the dried ink can be redispersed by the ink supplied in the nozzle itself, thereby making it less likely to be clogged and ensuring the stability of ejection. Therefore, when the transparent ink is added to the material formed after the ink dries, the easier it is to redisperse, which means that the nozzle is less likely to be clogged after drying, which can be said to be excellent.

[0204] <Evaluation>

[0205] [Redispersibility Evaluation]

[0206] The inks of Examples 1 to 12 and Comparative Examples 1 to 8 were 20 μL was dropped onto a glass dish, and the ink was dried in a constant temperature and humidity machine at 45°C for 10 minutes to obtain a dried product of the ink. After that, 10 mL of the above-mentioned transparent ink was dropped into the dried ink, the glass dish was slowly shaken, and it was left to stand for 1 hour. After that, the glass dish was slowly shaken again, and visual observation was made to see if redispersion was performed, and the evaluation was performed according to the following criteria. The results are shown in Tables 11 and 12. Since the redispersed solution does not produce residue and the colored solution diffuses like penetration, it can be judged visually. It can be said that the more residue there is, the worse the redispersibility. The following evaluation of 3 or above is ideal in practice.

[0207] -Evaluation Criteria-

[0208] 5: There is no residue, and the dried ink is completely redispersed.

[0209] 4: A very small amount of residue was observed, but the dried matter of the ink was almost redispersed.

[0210] 3: There is a small amount of residue, but the dried ink is redispersed to a certain extent.

[0211] 2: A large amount of residue was observed, and the dried matter of the ink was hardly redispersed.

[0212] 1: The dried ink does not change and there is almost no redispersion.

[0213] [Water resistance evaluation]

[0214] 20 μL of the ink of Examples 1 to 12 and Comparative Examples 1 to 8 was dripped onto a PET film (E5102 manufactured by Toyobo Co., Ltd.), and applied using a rod coater No. 3 (manufactured by Yasuda Seiki Co., Ltd.) in an automatic coater (PI-1210 manufactured by Teste Sangyo Co., Ltd.). Afterwards, the coated PET film was left to dry in a constant temperature and humidity machine at 70°C for 3 minutes. Then, a cotton swab moistened with ion exchange water was used to rub the ink coating film back and forth with a width of 1 cm, and the number of reciprocations until the ink coating film at the wiping location was completely peeled off was measured. The measurement was performed at a total of 5 locations in the same coating film, and the water resistance was evaluated by the average value of the number of reciprocations. The results are shown in Tables 11 and 12. The greater the number of reciprocations until the ink coating film is peeled off, the better the water resistance is, and in practical terms, 6 or more reciprocations are expected. In Tables 11 and 12, the values ​​in the "Water Resistance" column are the number of reciprocating cycles.

[0215] [Table 11]

[0216]

[0217] [Table 12]

[0218] As can be seen from Table 11, Example 1 is an example that achieves both good redispersibility and water resistance. In addition, it can be seen that Examples 2 to 4 are examples in which the metal tellurium content in the dispersion is lower than that in Example 1, and the water resistance is further improved while maintaining the same redispersibility. This is considered to be because the metal tellurium content from the dispersant is low, the adsorption force of the dispersant on the colorant is increased, and the dispersion stability is improved. Therefore, even after drying after ink coating, the colorant does not aggregate, and a smooth coating film can be formed in a better dispersed state.

[0219] As compared with Example 4, Examples 5 to 8 are examples in which the physical properties of the block copolymer structure such as Mw, acid value, and MAA content ratio in the A block are higher, but similarly to Example 4, both good redispersibility and water resistance are achieved.

[0220] Examples 9 to 12 are particularly preferred embodiments, and are examples in which both excellent redispersibility and water resistance are achieved.

[0221] On the other hand, Comparative Example 8 is an example of a random copolymer having a monomer ratio and physical properties substantially equivalent to those of the block copolymer of Example 9, but the redispersibility and water resistance are very poor results compared to the examples. It is believed that this is because the hydrophilic part and the hydrophobic part are arranged in a disordered manner, so the hydrophilicity to the liquid medium is low, and the dispersion stability is also poor, so the dispersant is easily separated and the colorant aggregates during drying. According to this example, it is shown that the structure of the block copolymer has an excellent effect on redispersibility and water resistance.

[0222] Comparative Example 1 is an example in which Mw, acid value, and MAA content ratio in the A block are all lower than those in the Examples. As a result, the redispersibility is extremely poor and the water resistance is also poor.

[0223] Comparative Example 2 is also an example in which the acid value and the MAA content ratio in the A block are low, and as a result, both the redispersibility and the water resistance are poor.

[0224] Comparative Example 3 is an example with a low acid value, and the water resistance is poor. From the above Comparative Examples 1 to 3, it can be seen that by using a dispersant that has a balance between Mw, acid value, and MAA content ratio in the A block, and polymer structure and physical properties, good redispersibility and water resistance of the ink can be achieved at the same time.

[0225] Comparative Examples 4 and 5 are examples in which the B block is composed of benzyl methacrylate, which is a cyclic aromatic hydrocarbon having a planar structure. As a result, the redispersibility was inferior to that of the Examples.

[0226] Comparative Example 6 is an example in which the B block is composed of isobornyl methacrylate, which is a polycyclic saturated hydrocarbon with limited structural conformations. Compared with the examples, the redispersibility and water resistance are both very poor. Similarly, Comparative Example 7 is an example in which the B block is composed of dicyclopentanyl methacrylate. The redispersibility is also poor.

[0227] From the above Comparative Examples 4 to 7, it can be seen that even if the structure and physical properties of the block copolymer meet the requirements, it becomes difficult to achieve both redispersibility and water resistance if the type of monomer constituting the hydrophobic part is changed. Therefore, the B block monomer of this example, cyclohexyl methacrylate, is a preferred embodiment.

[0228] The results in Tables 11 and 12 above show that the inks of the Examples are excellent inks having both high redispersibility and high water resistance, compared with the inks of the Comparative Examples.

Claims

1. A coloring dispersion for inkjet, comprising a coloring agent, a dispersant, a tellurium compound and water, The dispersant is an AB block polymer, wherein the monomers constituting the A block of the AB block polymer are (meth)acrylic acid and butyl (meth)acrylate, and the content of (meth)acrylic acid in the total mass of the monomers constituting the A block is 26 to 42% by mass, and the monomers constituting the B block of the AB block polymer include cyclohexyl (meth)acrylate, The acid value of the dispersant is 100 to 159 mgKOH / g, The mass average molecular weight of the dispersant is 10,000 to 50,000.

2. The colored dispersion for inkjet according to claim 1, wherein The total content of the tellurium compound calculated as metallic tellurium is 160 ppm or less on a mass basis.

3. The colored dispersion for inkjet according to claim 1 or 2, wherein The acid value of the dispersant is 112 to 135 mgKOH / g.

4. The colored dispersion liquid for inkjet according to claim 1 or 2, wherein The mass average molecular weight of the dispersant is 10,000 to 30,000.

5. The colored dispersion for inkjet according to claim 1 or 2, wherein The colorant is a colorant selected from the group consisting of pigments and disperse dyes.

6. The colored dispersion for inkjet according to claim 1 or 2, wherein The monomer constituting the B block of the AB block polymer includes (meth)acrylic acid.

7. An inkjet recording ink comprising the colored dispersion liquid for inkjet according to any one of claims 1 to 6.

8. An inkjet recording method, wherein: The recording is performed by ejecting droplets of the inkjet recording ink according to claim 7 from an inkjet printer and causing them to adhere to a recording medium.

9. The inkjet recording method according to claim 8, wherein The recording medium is a poorly ink-absorbing or ink-non-absorbing recording medium.

10. The inkjet recording method according to claim 9, wherein The recording medium is a recording medium subjected to at least one surface modification treatment selected from the group consisting of a corona discharge treatment, a plasma treatment, and a flame treatment.

11. A recording medium having the inkjet recording ink according to claim 7 adhered thereto.

12. An inkjet printer loaded with a container containing the inkjet recording ink according to claim 7.

13. A method for producing a colored dispersion for inkjet, wherein: The inkjet colored dispersion liquid is the inkjet colored dispersion liquid according to any one of claims 1 to 6, The method for producing the inkjet colored dispersion liquid includes the step of coating the dispersant on the surface of the colorant.

14. The method for producing a colored dispersion liquid for inkjet according to claim 13, wherein: The dispersant is coated on the surface of the colorant by a phase inversion emulsification method.

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