Ink, inkjet recording method, ink set, ink medium set, and printing medium

Abstract

To provide various dispersion liquids for recording which are excellent in storage stability and re-dispersion properties, and a printed matter using the dispersion liquids.SOLUTION: A dispersion liquid contains a crosslinking agent and an acid group-containing resin, wherein when a molar equivalent number of a crosslinking functional group of the crosslinking agent is represented by A, and a molar equivalent number of an acidic functional group of the acid group-containing resin is represented by B, a crosslinking value calculated from A / B exceeds 1.60 and is 3.00 or less.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an ink, an inkjet recording method, an ink set, an ink media set, and a print medium. [Background technology]

[0002] Among various color recording methods, the recording method using an inkjet printer (inkjet recording method), which is one of the most representative methods, generates small droplets of ink and deposits them on a printing medium such as paper to perform recording. In recent years, demand has increased for commercial and industrial applications, and there is a demand for inks that can be printed on a variety of printing media.

[0003] In commercial fields such as catalogs and pamphlets, printing media with lower ink absorption than plain paper (hereinafter also referred to as "low-ink-absorbency media"), such as coated paper and art paper, are often used. In industrial fields such as outdoor signage and soft food packaging, printing media with low ink absorption (hereinafter also referred to as "low-ink-absorbency media"), such as polyvinyl chloride film, PET (polyethylene terephthalate) film, and polyolefin film, are often used.

[0004] For poorly ink-absorbent media and non-ink-absorbent media, solvent inks using organic solvents as the main solvent and curable inks containing polymerizable monomers have been developed. However, these inks have many safety issues for the natural environment and the human body. Therefore, in recent years, water-based inks using water as the main solvent have been developed actively. In particular, from the viewpoint of weather resistance and water resistance of recorded materials, inks using pigments as colorants have become mainstream. Pigment inks are required to be stable over a long period of time. It is known that pigments that are generally present in ink in a dispersed state as particles rather than molecules undergo settling over time due to aggregation of pigment particles. As a result, a concentration gradient occurs in the ink, which can cause problems such as failure to obtain initial printing characteristics or, in the worst case, clogging of nozzles with aggregated particles, making it impossible to eject the ink. For this reason, there is a demand for the development of an ink composition that, when used as an ink composition, is good in various fastness properties, gives high density images when printed, and has good storage stability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2012-533651 [Patent Document 2] JP 2017-186545 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a dispersion liquid having excellent storage stability and redispersibility, an inkjet recording method using the dispersion liquid, a dispersion liquid set including the dispersion liquid, a dispersion liquid media set including the dispersion liquid or the dispersion liquid set and a printing medium, and a printing medium to which the dispersion liquid or each dispersion liquid of the dispersion liquid set is adhered. [Means for solving the problem]

[0007] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a dispersion containing a crosslinker and an acid group-containing resin, in which the crosslinking value calculated by A / B is more than 1.60 and is not more than 3.00, where A is the molar equivalent number of crosslinking functional groups of the crosslinker and B is the molar equivalent number of acidic functional groups of the acid group-containing resin, and thus completed the present invention.

[0008] That is, the present invention relates to the following 1) to 9). 1) A dispersion comprising a crosslinker and an acid group-containing resin, wherein a crosslinking value calculated by A / B exceeds 1.60 and is not more than 3.00, where A is the molar equivalent number of crosslinking functional groups of the crosslinker and B is the molar equivalent number of acidic functional groups of the acid group-containing resin. 2) 2) The dispersion according to claim 1, wherein the crosslinking value calculated by A / B is 1.65 or more and 2.70 or less. 3) The dispersion according to 1) or 2), further comprising a colorant. 4) The dispersion according to 1) or 2), further comprising a wax. 5) An inkjet recording method comprising ejecting droplets of the dispersion according to 1) or 2) from an inkjet head to record on a print medium. 6) 5) The inkjet recording method according to 5), wherein the printing medium is a printing medium that is poorly ink-absorbent or non-ink-absorbent. 7) A dispersion set comprising the dispersion according to 1) or 2) and another dispersion different from the dispersion. 8) A dispersion media set comprising at least one selected from the group consisting of the dispersion according to 1) or 2) and the dispersion set according to claim 7, and a printing medium. 9) A printing medium having adhered thereto at least one selected from the group consisting of the dispersion according to 1) or 2) and the dispersions contained in the dispersion set according to claim 7. Effect of the Invention

[0009] The present invention provides a dispersion having excellent storage stability and redispersibility. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, specific embodiments to which the present invention is applied will be described in detail. As used herein, "CI" means "Color Index."

[0011] <Dispersion> The dispersion according to the present embodiment contains a crosslinking agent and an acid group-containing resin, and when the molar equivalent number of the crosslinking functional group of the crosslinking agent is A and the molar equivalent number of the acid functional group of the acid group-containing resin is B, the crosslinking value calculated by A / B is more than 1.60 and is 3.00 or less. The components contained in the dispersion according to the present embodiment will be described in detail below. Note that, each of the components described below may be used alone or in combination of two or more kinds.

[0012] <Crosslinking agent> The dispersion contains a crosslinking agent. The crosslinking agent bonds with a plurality of acidic functional groups of the acid group-containing resin described later to form a crosslinked structure, resulting in a "crosslinked polymer" having a crosslinked structure. The crosslinking agent is not particularly limited as long as it has a plurality of crosslinking functional groups capable of bonding to the acidic functional groups described later.

[0013] The crosslinked structure of the polymer may be, for example, a crosslinked structure in which two or more acidic functional groups contained in one type of acid group-containing resin are crosslinked via one crosslinking agent, or a crosslinked structure in which two or more acidic functional groups contained in two or more types of acid group-containing resins are crosslinked via one crosslinking agent.

[0014] When the dispersion contains a colorant, which will be described later, the polymer is adsorbed to a part or the whole of the surface of the colorant. It is believed that the polymer has the crosslinked structure, which makes it difficult for the polymer adsorbed to the colorant surface to be detached, thereby improving stability.

[0015] The crosslinking agent has a crosslinking functional group capable of forming the crosslinked structure. Examples of the crosslinking functional group include an epoxy group, a hydroxyl group, an amino group, and an oxazoline group. Examples of the crosslinking agent include a compound having at least one crosslinking functional group selected from the group consisting of an epoxy group, a hydroxyl group, an amino group, and an oxazoline group in the molecule, and a compound having at least two or more crosslinking functional groups selected from the group consisting of an epoxy group, a hydroxyl group, an amino group, and an oxazoline group in total.

[0016] The crosslinking agent has a plurality of crosslinking functional groups, and the structure of the site other than the crosslinking functional group is not particularly limited as long as it does not interfere with the crosslinking reaction with the acid group-containing resin described later. Examples of the structure of the site other than the crosslinking functional group include linear, branched and cyclic alkylene groups, arylene groups, heterocycles, -CO-, -O-, -NH- and -S-, and groups selected from the group consisting of combinations thereof, and a divalent group selected from the group consisting of linear or branched alkylene groups having 2 to 4 carbon atoms, phenyl groups, -CO-, -O- and combinations thereof is preferred, and a group formed by combining an ethylene group or a propylene group with -O- is more preferred. Preferred examples of the crosslinking agent include a compound having two or more epoxy groups in the molecule, a compound having two or more hydroxyl groups in the molecule, a compound having two or more amino groups in the molecule, and a compound having two or more oxazoline groups in the molecule.

[0017] Examples of compounds having two or more epoxy groups in the molecule include polyglycidyl ethers in which the hydroxyl groups of polyhydric alcohols are replaced with glycidyl groups. Specific examples of polyglycidyl ethers include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin triglycidyl ether, glycerol polyglycidyl ether, polyglycerol polyglycidyl ether, trimethylolpropane polyglycidyl ether, sorbitol polyglycidyl ether, pentaerythritol polyglycidyl ether, resorcinol diglycidyl ether, neopentyl glycol diglycidyl ether, and hydrogenated bisphenol A diglycidyl ether.

[0018] Examples of compounds having two or more hydroxyl groups in the molecule include polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerin, polyglycerin, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentyl alcohol, diethanolamine, tridiethanolamine, polypropylene glycol, polyvinyl alcohol, pentaerythritol, sorbitol, sorbitan, glucose, mannite, mannitan, sucrose, and glucose.

[0019] Examples of compounds having two or more amino groups in the molecule include polyamines such as ethylenediamine and polyethyleneimine.

[0020] Examples of compounds having two or more oxazoline groups in the molecule include compounds in which two or more and four or less, preferably two or more and three or less oxazoline groups are bonded to an aliphatic group or an aromatic group. More specific examples include bisoxazoline compounds such as 2,2'-bis(2-oxazoline), 1,3-phenylenebisoxazoline, and 1,3-benzobisoxazoline, and compounds having a terminal oxazoline group obtained by reacting the bisoxazoline compound with a polybasic carboxylic acid. Of the commercially available crosslinking agents, preferred ones include, for example, Denacol EX-321L (130 g / eq), EX-512 (183 g / eq), EX-810 (113 g / eq), etc. (all manufactured by Nagase ChemteX Corporation). The crosslinking agent has a crosslinking functional group, and the molar equivalent number (g / eq) of the crosslinking functional group of the crosslinking agent can be calculated from the following relational formula (Formula (1)). For commercially available products, the molar equivalent number listed in the product catalog or the molar equivalent number calculated based on the value listed in the product catalog can be used. Crosslinking value = catalog value of crosslinking agent equivalent number or molar equivalent number of crosslinking functional group / molar equivalent number of acidic functional group of acid group-containing resin Formula (1) The molar equivalent number of the crosslinking functional group can be calculated from the molar equivalent number of the crosslinking functional group (=equivalent number of the crosslinking functional group) / the number of moles of the crosslinking functional group.

[0021] <Acid group-containing resin> The dispersion contains an acid group-containing resin. The acid group-containing resin is not particularly limited as long as it can form a "crosslinked polymer" with the crosslinking agent, and examples thereof include copolymers composed of at least two monomers (preferably at least one of which is a hydrophilic monomer) selected from the group consisting of monomers of styrene and its derivatives; vinyl naphthalene and its derivatives; aliphatic alcohol esters of α,β-ethylenically unsaturated carboxylic acids; acrylic acid and its derivatives; maleic acid and its derivatives; itaconic acid and its derivatives; faric acid and its derivatives; vinyl acetate, vinyl alcohol, vinyl pyrrolidone, acrylamide, and derivatives thereof. Examples of such copolymers include styrene-(meth)acrylic acid copolymers, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymers, (meth)acrylic acid ester-(meth)acrylic acid copolymers, polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymers, styrene-maleic acid copolymers, etc.

[0022] Among these, styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, (meth)acrylic acid ester-(meth)acrylic acid copolymer, polyethylene glycol (meth)acrylate-(meth)acrylic acid copolymer are preferred; styrene-(meth)acrylic acid copolymer, styrene-(meth)acrylic acid-(meth)acrylic acid ester copolymer, (meth)acrylic acid ester-(meth)acrylic acid copolymer are more preferred; (meth)acrylic acid ester-(meth)acrylic acid copolymer is even more preferred; and methacrylic acid ester-methacrylic acid copolymer is particularly preferred.

[0023] The acid group-containing resin can be synthesized or obtained as a commercially available product. Specific examples of commercially available products include JONCRYL 62 (weight average molecular weight 13,000, acid value 213), 67 (weight average molecular weight 12,500, acid value 213), 68 (weight average molecular weight 13,000, acid value 200), 586 (weight average molecular weight 4,600, acid value 108), 611 (weight average molecular weight 8,100, acid value 53), 678 (weight average molecular weight 8,600, acid value 215), 679 (weight average molecular weight 9,000, and 819 (weight average molecular weight 14500, acid value 75), etc., manufactured by Seiko PMC Corporation. NS-2092 (weight average molecular weight 9000, acid value 200), RS-1191 (weight average molecular weight 6500, acid value 280), VS-1047 (weight average molecular weight 10000, acid value 240), BS-1291 (weight average molecular weight 10000, acid value 210), ZS-1417 (weight average molecular weight 14000, acid value 156), US-1071 (weight average molecular weight 10000, acid value 75) styrene-acrylic copolymers such as YS-1274 (weight average molecular weight 19000, acid value 200), ZS-1074 (weight average molecular weight 14000, acid value 210), X-1 (weight average molecular weight 18000, acid value 110), VS-1259 (weight average molecular weight 25000, acid value 164), and FS-2358 (weight average molecular weight 25000, acid value 203); and more preferably, Joncryl 678, 680, 682, 690, etc. The acid group-containing resin has a weight average molecular weight preferably in the range of 1000 to 50000, more preferably in the range of 2000 to 20000, even more preferably in the range of 5000 to 15000, particularly preferably in the range of 6000 to 10000, and extremely preferably in the range of more than 8000 and less than 9000. The acid value is preferably in the range of 20 to 400, more preferably in the range of 50 to 300, even more preferably in the range of 80 to 250, particularly preferably in the range of 200 to 240, and extremely preferably in the range of 210 to 230. The acid group-containing resin is preferably a block copolymer, more preferably an AB block copolymer.

[0024] The acid group-containing resin has an acidic functional group, and the molar equivalent number of the acidic functional group of the acid group-containing resin can be calculated by the following formula (2). Molar equivalent number of acidic functional groups = acid value of acidic functional groups / molar amount of acidic functional groups Equation (2)

[0025] The "acid value" in this specification (unit: mgKOH / g) is calculated by calculating the theoretical number of moles of acid groups contained in 1 g of resin from the monomer composition, and assuming that this number of moles of acid groups is equal to the number of moles of potassium hydroxide (molecular weight: 56.1) required for neutralization.

[0026] The crosslinking agent and the acid group-containing resin contained in the dispersion have a crosslinking value calculated by A / B, where A is the molar equivalent number of the crosslinking functional group of the crosslinking agent and B is the molar equivalent number of the acidic functional group of the acid group-containing resin, which is greater than 1.60 and less than 3.00, preferably greater than 1.65 and less than 2.70, more preferably greater than 1.70 and less than 2.50, and even more preferably greater than 1.70 and less than 2.20.

[0027] The dispersion may further contain a colorant. The colorant is not particularly limited, but examples thereof include pigments and disperse dyes.

[0028] Examples of the pigment include inorganic pigments, organic pigments, extender pigments, hollow particles, and the like. Examples of inorganic pigments include carbon black, metal oxides, metal hydroxides, metal sulfides, metal ferrocyanides, and metal chlorides.

[0029] When the dispersion according to the present embodiment is a black dispersion and the colorant is an inorganic pigment, the inorganic pigment contained in the black dispersion is preferably carbon black such as thermal black, acetylene black, oil furnace black, gas furnace black, lamp black, gas black, channel black, etc. Specific examples of carbon black include the Raven series manufactured by Columbia Carbon Co., the Monarch series, Regal series, and Mogul series manufactured by Cabot Corporation, the HiBlack series, ColorBlack series, Printex series, SpecialBlack series, and Nerox series manufactured by Orion Engineered Carbons Co., Ltd., the 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.

[0030] When the dispersion according to the present embodiment is a white dispersion and the colorant is an inorganic pigment, examples of the inorganic pigment contained in the white dispersion include oxides, nitrides, or oxynitrides of metals such as zinc, silicon, aluminum, titanium, strontium, and zirconium; inorganic compounds such as glass and silica; etc. Among these, titanium dioxide and zinc oxide are preferred.

[0031] Examples of organic pigments include various pigments such as azo, disazo, phthalocyanine, quinacridone, isoindolinone, dioxazine, perylene, perinone, thioindigo, anthraquinone, and quinophthalone.

[0032] 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, 155, 180, 185, 193, 199, 202, and 213; Red pigments such as 5, 7, 12, 48, 48:1, 57, 88, 112, 122, 123, 146, 149, 150, 166, 168, 177, 178, 179, 184, 185, 202, 206, 207, 254, 255, 257, 260, 264, 269, 272; blue pigments such as CI Pigment Blue 1, 2, 3, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 22, 25, 60, 66, 80; violet pigments such as CI Pigment Violet 19, 23, 29, 37, 38, 50; orange pigments such as CI Pigment Orange 13, 16, 43, 68, 69, 71, 73; CI Pigment Green 7, 36, 54, and other green pigments; and CI Pigment Black 1, and other black pigments. Among these, CI Pigment Blue 15:4 is preferred.

[0033] 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.

[0034] As the hollow particles, known hollow particles described in, for example, U.S. Pat. No. 4,880,465, Japanese Patent No. 3,562,754, Japanese Patent No. 6,026,234, Japanese Patent No. 5,459,460, JP-A-2003-268694, Japanese Patent No. 4,902,216, etc. can be used, and they are particularly preferably used as white pigments.

[0035] As disperse dyes, for example, dyes selected from CI Dispers are preferred. Specific examples thereof include yellow dyes such as CI 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, and 237; red dyes such as CI Dispers Red 60, 73, 88, 91, 92, 111, 127, 131, 143, 145, 146, 152, 153, 154, 167, 179, 191, 192, 206, 221, 258, and 283; and CI Dispers Orange. Orange dyes such as 9, 25, 29, 30, 31, 32, 37, 38, 42, 44, 45, 53, 54, 55, 56, 61, 71, 73, 76, 80, 96, 97, etc.; violet dyes such as CI Dispers Violet 25, 27, 28, 54, 57, 60, 73, 77, 79, 79:1, etc.; blue dyes such as CI 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, etc.;

[0036] The average particle size of the colorant is preferably 30 to 300 nm, and more preferably 50 to 250 nm. In this specification, the average particle size refers to the average particle size of particles measured by a laser light scattering method.

[0037] The content of the colorant is preferably 1 to 30 mass %, more preferably 1 to 10 mass %, and even more preferably 2 to 8 mass %, relative to the total mass of the dispersion according to this embodiment.

[0038] The colorant may further contain other dyes in addition to the pigment and the disperse dye. Examples of the other dyes include solvent dyes, direct dyes, acid dyes, and reactive dyes.

[0039] When the dispersion contains a plurality of kinds of the colorants, the blending ratio of the colorants can be set arbitrarily according to the purpose. When the dispersion contains the other dyes in addition to the colorants, the blending ratio of the total amount of the colorants to the total amount of the other dyes can also be set arbitrarily.

[0040] The ratio of crosslinker to pigment in the dispersion (total mass of crosslinker / total mass of pigment) is preferably 0.03 to 1, more preferably 0.1 to 1, even more preferably 0.2 to 0.75, and particularly preferably 0.25 to 0.5.

[0041] The ratio of the acid group-containing resin to the crosslinking agent in the dispersion (total mass of the acid group-containing resin / total mass of the crosslinking agent) is preferably 0.5 to 5, more preferably 0.5 to 1.5, even more preferably 0.65 to 1.5, and particularly preferably 0.7 to 1.2.

[0042] The dispersion may further contain water. The water is preferably water with a low content of impurities such as metal ions, i.e., ion-exchanged water, distilled water, etc. The content of water is 60 to 90% by mass, preferably 70 to 90% by mass, based on the total mass of the dispersion according to this embodiment.

[0043] The dispersion may contain, as necessary, a dispersion preparation agent such as an organic solvent, a surfactant, an antifungal agent, a preservative, a pH adjuster, a chelating agent, a rust inhibitor, an antifoaming agent, a water-soluble ultraviolet absorber, an antioxidant, a resin emulsion, etc. The content of each dispersion preparation agent can be arbitrarily set depending on the use of the dispersion, etc.

[0044] Examples of organic solvents include C1-C6 alkanols such as methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, and tertiary butanol; carboxylic acid amides such as N,N-dimethylformamide and N,N-dimethylacetamide; lactams such as 2-pyrrolidone, N-methyl-2-pyrrolidone, and N-methylpyrrolidin-2-one; cyclic ureas such as 1,3-dimethylimidazolidin-2-one and 1,3-dimethylhexahydropyrimidin-2-one; acetone, 2- Ketones, ketoalcohols, or carbonates such as methyl-2-hydroxypentan-4-one and ethylene carbonate; cyclic ethers such as tetrahydrofuran and dioxane; ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, polyethylene glycol (preferably those having a molecular weight of 400, 800, 1540, or more), polypropylene glycol, thiodiglycol, mono-, oligo-, or polyalkylene glycols or thioglycols having a C2-C6 alkylene unit, such as glycol, dithiodiglycol, etc.; C3-C9 polyols (triols), such as glycerin, diglycerin, hexane-1,2,6-triol, and trimethylolpropane; glycol ethers, such as ethylene glycol monoallyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, dipropylene glycol monopropyl ether, and dipropylene glycol monomethyl ether (preferably, C7-C10 triethylene glycol ether, or C4-C13 mono-, di-, or tripropylene glycol ether); C6-C9 alkanediols, such as 1,2-hexanediol, 1,6-hexanediol, and 2-methyl-2,4-pentanediol; γ-butyrolactone; and dimethyl sulfoxide.

[0045] The surfactant may be anionic, nonionic, silicone, or fluorine-based surfactants. Among these, surfactants selected from silicone and fluorine-based surfactants are preferred, and silicone-based surfactants are more preferred from the viewpoint of safety to living organisms and the environment.

[0046] Examples of anionic surfactants include alkyl sulfocarboxylates, α-olefin sulfonates, polyoxyethylene alkyl ether acetates, polyoxyethylene alkyl ether sulfates, N-acylamino acids or salts thereof, N-acylmethyltaurines, alkyl sulfates, polyoxyalkyl ether sulfates, alkyl sulfates, polyoxyethylene alkyl ether phosphates, rosin acid soaps, castor oil sulfates, lauryl alcohol sulfates, alkylphenol phosphates, alkyl phosphates, alkylarylsulfonates, diethylsulfosuccinates, diethylhexylsulfosuccinates, and dioctylsulfosuccinates.

[0047] Examples of nonionic surfactants include ether surfactants such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, polyoxyethylene alkyl ether, and polyoxyethylene distyrenated phenyl ether (for example, Emulgen A-60, A-90, and A-500 manufactured by Kao Corporation); polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, and sorbitan monostearate. ester-based surfactants such as 2,4,7,9-tetramethyl-5-decyne-4,7-diol, 3,6-dimethyl-4-octyne-3,6-diol, 3,5-dimethyl-1-hexyne-3-ol (for example, Surfynol 104, 104PG50, 82, 420, 440, 465, 485; Olfine STG; and the like, all of which are manufactured by Evonik Japan Ltd.); and polyglycol ether-based surfactants.

[0048] Examples of silicone surfactants include polyether-modified siloxanes and polyether-modified polydimethylsiloxanes. Examples of such products include Dynol 960 and 980 manufactured by Air Products Co., Ltd.; Silface SAG001, SAG002, SAG003, SAG005, SAG503A, SAG008, SAG009, and SAG010 manufactured by Nissin Chemical Industry Co., Ltd.; BYK-345, 347, 348, 349, 3450 (also known as BYKLPX 23289), 3451 (also known as BYKLPX 23347), 3455, LP-X23288, and LP G20726 manufactured by BYK Japan Co., Ltd.; and TEGO Twin 4000, TEGOWet KL 245, 250, 260, 265, 270, and 280 manufactured by EvonicTego Chemie Co., Ltd.

[0049] Examples of fluorine-based surfactants include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups on the side chains, etc. Examples of commercially available products include Capstone FS-30 and FS-31 manufactured by Chemours.

[0050] Examples of antifungal agents include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof.

[0051] Examples of the preservative include organic sulfur compounds, organic nitrogen sulfur compounds, organic halogen compounds, haloarylsulfone compounds, iodopropargyl compounds, haloalkylthio 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, anilide compounds, adamantane compounds, dithiocarbamate compounds, brominated indanone compounds, benzyl bromoacetate compounds, inorganic salt compounds, etc. Specific examples of organic halogen compounds include sodium pentachlorophenol, etc. Specific examples of pyridine oxide compounds include sodium 2-pyridinethiol-1-oxide, etc. Specific examples of isothiazoline compounds include 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 5-chloro-2-methyl-4-isothiazolin-3-one, 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 chloride, etc. Specific examples of other antiseptics and fungicides include anhydrous sodium acetate, sodium sorbate, sodium benzoate, and Arch Chemical's trade names Proxel GXL(S), Proxel LV, and Proxel XL-2(S).

[0052] Examples of pH adjusters include alkanolamines such as diethanolamine, triethanolamine, and N-methyldiethanolamine; alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; ammonium hydroxide (aqueous ammonia); 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; and inorganic bases such as disodium phosphate.

[0053] Examples of the chelating agent include disodium ethylenediaminetetraacetate, sodium nitrilotriacetate, sodium hydroxyethylethylenediaminetriacetate, sodium diethylenetriaminepentaacetate, and sodium uracildiacetate.

[0054] Examples of the rust inhibitor include acid sulfite, sodium thiosulfate, ammonium thioglycolate, diisopropylammonium nitrite, pentaerythritol tetranitrate, and dicyclohexylammonium nitrite.

[0055] Examples of the defoaming agent include silicone-based, silica mineral oil-based, olefin-based, acetylene-based compounds, etc. Examples of commercially available defoaming agents include Surfynol DF37, DF58, DF110D, DF220, MD-20, and Olfin SK-14 manufactured by Shin-Etsu Chemical Co., Ltd.

[0056] Examples of the water-soluble ultraviolet absorber include sulfonated benzophenone compounds, benzotriazole compounds, salicylic acid compounds, cinnamic acid compounds, and triazine compounds.

[0057] As the antioxidant, for example, various organic and metal complex-based discoloration inhibitors can be used. Examples of organic discoloration inhibitors include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc.

[0058] The dispersion according to the present embodiment may contain a wax in order to improve the fixation of the dispersion to the print medium. When the dispersion according to the present embodiment contains a wax, the image fastness such as water resistance, abrasion resistance, and alcohol resistance of the image printed on the print medium tends to be improved. The wax may be a wax emulsion.

[0059] As the wax emulsion, an emulsion in which a natural wax or a synthetic wax is dispersed in an aqueous medium can be used.

[0060] Examples of natural wax emulsions include emulsions of various waxes, such as petroleum-based waxes such as paraffin wax and microcrystalline wax; lignite-based waxes such as montan wax; vegetable waxes such as carnauba wax and candelilla wax; and animal and vegetable waxes such as beeswax and lanolin.

[0061] Examples of synthetic wax emulsions include emulsions of polyalkylene wax (preferably poly C2-C4 alkylene wax), oxidized polyalkylene wax (preferably poly C2-C4 alkylene wax), paraffin wax, etc. Among these, emulsions of wax selected from polyethylene wax, polypropylene wax, oxidized polyethylene wax, oxidized polypropylene wax, and paraffin wax are preferred.

[0062] In order to prevent clogging of the inkjet head, the average particle size of the wax is preferably 50 nm to 5 μm, and more preferably 100 nm to 1 μm.

[0063] Examples of commercially available wax emulsions include CERAFLOUR 925, 929, 950, 991, AQUACER 498, 515, 526, 531, 537, 539, 552, 1547, AQUAMAT 208, 263, 272; MINERPOL 221 (all manufactured by BYK Japan Co., Ltd.); KUE-100, 11 (all manufactured by Sanyo Chemical Industry Co., Ltd.); HYTEC P-5300, E-6500, 9015, 6400 (all manufactured by Toho Chemical Industry Co., Ltd.); and the like.

[0064] When the dispersion according to the present embodiment contains wax, the wax solid content is preferably 1 to 20% by mass, more preferably 3 to 15% by mass. By making the wax solid content 1% by mass or more, the dispersion tends to exhibit good fixability to the print medium. In addition, by making the wax solid content 20% by mass or less, the dispersion tends to have good ejection properties and storage stability.

[0065] The method for preparing the dispersion according to the present embodiment is not particularly limited, and any known preparation method can be used. One example of the method is to prepare a liquid containing a crosslinker and an acid group-containing resin, and then add water and, if necessary, the dispersion preparation agent to this liquid and mix them. In the preparation of the dispersion, a heating step is not essential.

[0066] Examples of methods for preparing the liquid include phase inversion emulsification, acid precipitation, interfacial polymerization, in-situ polymerization, liquid hardening coating, coacervation (phase separation), liquid drying, melt dispersion cooling, air suspension coating, spray drying, etc. Among these, phase inversion emulsification, acid precipitation, and interfacial polymerization are preferred, and phase inversion emulsification is more preferred.

[0067] When preparing a dispersion by the phase inversion emulsification method, for example, a dispersant is dissolved in an organic solvent such as 2-butanone, and an aqueous solution of a neutralizing agent is added to prepare an emulsion. A colorant is added to the obtained emulsion and a dispersion treatment is performed. The organic solvent and a part of the water are distilled off under reduced pressure from the liquid obtained in this manner to obtain the desired dispersion.

[0068] The dispersion treatment can be carried out using a sand mill (bead mill), a roll mill, a ball mill, a paint shaker, an ultrasonic disperser, a microfluidizer, or the like. For example, when using a sand mill, beads having a particle diameter of about 0.01 to 1 mm can be used, and the packing rate of the beads can be appropriately set to carry out the dispersion treatment. The particle diameter of the particles contained in the dispersion can be made uniform by subjecting the dispersion obtained as described above to an operation such as filtration or centrifugation. When foaming occurs during the preparation of the dispersion, a very small amount of a known silicone-based, acetylene glycol-based, or other defoaming agent can be added.

[0069] The dispersion according to the present embodiment preferably has a low content of inorganic impurities such as chlorides of metal cations (e.g., sodium chloride) and metal sulfates (e.g., sodium sulfate). Such inorganic impurities are often contained in commercially available colorants. The content of inorganic impurities is approximately 1% by mass or less relative to the total mass of the colorant, and the lower limit is ideally below the detection limit of an analytical instrument, i.e., 0% by mass. Methods for obtaining a colorant with low inorganic impurities include, for example, a method using a reverse osmosis membrane; a method in which a solid colorant is suspended and stirred in a mixed solvent of C1-C4 alcohol such as methanol and water, and the colored body is separated by filtration and dried; a method in which inorganic impurities are exchanged and adsorbed by an ion exchange resin; and the like.

[0070] The dispersion according to the present embodiment is preferably subjected to microfiltration. For the microfiltration, a membrane filter, glass filter paper, etc. can be used. The pore size of the filter used for the microfiltration is usually 0.5 to 20 μm, preferably 0.5 to 10 μm.

[0071] The dispersion according to the present embodiment is also excellent in storage stability, redispersibility, color development, and saturation. In addition, the printed image recorded using the dispersion according to the present embodiment is also excellent in various fastness properties such as light resistance, heat resistance, and oxidation gas resistance (e.g., ozone gas resistance). In addition, the dispersion according to the present embodiment has little coating unevenness during image formation, and is also excellent in image forming properties.

[0072] Examples of the dispersion set according to the present embodiment include a set of the above-mentioned dispersions according to the present embodiment, or a set including the above-mentioned dispersion according to the present embodiment and another dispersion different from the above-mentioned dispersion, etc. The other dispersion is not particularly limited as long as it has a different structure from the dispersion according to the present embodiment, but it is preferable that the other dispersion has a different hue from the dispersion according to the present embodiment.

[0073] Furthermore, the print medium according to this embodiment has adhered thereto at least one selected from the group consisting of the dispersion liquid according to this embodiment or the dispersion liquid contained in the dispersion liquid set.

[0074] Moreover, the dispersion media set according to this embodiment includes the dispersion or dispersion set according to this embodiment described above, and a print medium.

[0075] The printing medium is not particularly limited, but is preferably a poorly ink-absorbent or non-ink-absorbent printing medium, and more preferably a non-ink-absorbent printing medium. Examples of poorly ink-absorbent printing media include plain paper without an ink-receiving layer, media used in gravure printing or offset printing, art paper, coated paper, matte paper, cast paper, etc. Examples of non-ink-absorbent printing media include PET (polyethylene terephthalate) film, PP (polypropylene) film, polyvinyl chloride sheet, glass, rubber, etc.

[0076] The inkjet recording method according to this embodiment involves ejecting droplets of the dispersion according to this embodiment from an inkjet head to record on a print medium. There are no particular limitations on the ink nozzles of the inkjet printer that eject the dispersion, and they can be appropriately selected depending on the purpose.

[0077] The inkjet recording method according to this embodiment also includes a method of improving image quality by ejecting a large number of small volumes of dispersion liquids each having a low content of colorant; a method of improving image quality by using a plurality of dispersion liquids each having substantially the same hue but different content of colorant; and a method of improving the fixation of the colorant to the printing medium by using a colorless and transparent dispersion liquid in combination with a dispersion liquid containing a colorant.

[0078] As the inkjet recording method, a known method can be adopted. Examples of such methods include a charge control method, a drop-on-demand method (also called a pressure pulse method), an acoustic inkjet method, and a thermal inkjet method. The inkjet recording method may be either a multi-pass method or a single-pass method (one-pass printing method). In industrial inkjet printers, single-pass printing using a line head type inkjet printer is also preferably performed for the purpose of increasing the printing speed. In addition, in recent years, circulation heads having a mechanism (i.e., a circulation mechanism) that prevents the dispersion liquid from drying in the vicinity of the nozzle by circulating the dispersion liquid up to the vicinity of the nozzle have been actively developed. The dispersion liquid according to this embodiment is also preferably used in such a circulation head.

[0079] When recording on a print medium, for example, a container (ink tank) containing the dispersion liquid is loaded at a predetermined position of an inkjet printer, and recording is performed on the print medium by the above-mentioned printing method. Note that full-color printing can also be achieved by loading containers containing dispersion liquids of each color at predetermined positions of the inkjet printer, and recording on the print medium by the above-mentioned printing method.

[0080] In addition, when using a printing medium that does not have a dispersion liquid receiving layer, it is also preferable to carry out a surface modification treatment. Examples of the surface modification treatment include corona discharge treatment, plasma treatment, and frame treatment. It is generally known that the effect of the surface modification treatment decreases over time. For this reason, it is preferable to carry out the surface modification treatment step and the inkjet recording step consecutively, and it is more preferable to carry out the surface modification treatment step immediately before the inkjet recording step.

[0081] For all of the above items, combinations of preferred items are more preferred, and combinations of more preferred items are even more preferred. The same applies to combinations of preferred items and more preferred items, combinations of more preferred items and even more preferred items, etc. EXAMPLES

[0082] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following examples. In the text, "parts" and "%" are by mass unless otherwise specified. In the examples, when quantitative determination of the pigment solid content in the dispersion was required, it was determined by the dry weight method using MS-70 manufactured by A&D Co., Ltd. The pigment solid content is a converted value calculated from the total amount of solids, i.e., the pigment solid content alone. All of the inks in the examples are contained in the above dispersion.

[0083] [Preparation Example 1: Preparation of Joncryl 678 NaOH Neutralization] 20 parts of Joncryl 678 (BASF) were added to 6 parts of 25% aqueous sodium hydroxide solution, 54 parts of ion-exchanged water, and 20 parts of propylene glycol, and the mixture was heated to 90-120° C. and stirred for 5 hours to obtain a neutralized Joncryl 678 NaOH.

[0084] [Examples 1 to 4] Preparation of Dispersions 1 to 4 Zirconia beads with a diameter of 0.3 mm were added to a mixture of each component shown in Table 1 below, and dispersion treatment was carried out for about 15 hours in a sand mill under water cooling. The pigment content of the obtained liquid was adjusted to 12.0% with ion-exchanged water, and then filtered with glass fiber filter paper GC-50 (manufactured by ADVANTEC) to obtain each colored dispersion liquid.

[0085] [Comparative Examples 1 and 2] Preparation of Dispersions 5 and 6 Zirconia beads with a diameter of 0.3 mm were added to a mixture of each component shown in Table 1 below, and dispersion treatment was carried out for about 15 hours in a sand mill under water cooling. The pigment content of the obtained liquid was adjusted to 12.0% with ion-exchanged water, and then filtered with glass fiber filter paper GC-50 (manufactured by ADVANTEC) to obtain each colored dispersion liquid.

[0086] [Examples 5 to 8] Preparation of Inks 1 to 4 Dispersions 1 to 4 obtained in Examples 1 to 4 above were mixed with the components shown in Table 2 below, stirred for 30 minutes, and then filtered through glass fiber filter paper GC-50 (manufactured by ADVANTEC) to prepare inks 1 to 4, respectively.

[0087] [Comparative Examples 3 and 4] Preparation of Inks 5 and 6 Dispersions 3 and 4 obtained in Comparative Examples 3 and 4 above were mixed with the components shown in Table 2 below, stirred for 30 minutes, and then filtered through glass fiber filter paper GC-50 (manufactured by ADVANTEC) to prepare inks 5 and 6, respectively.

[0088] The abbreviations in Tables 1 and 2 below represent the following: NEROX605: Carbon black (Orion Engineered Carbons) Denacol EX-321L: Trimethylolpropane polyglycidyl ether (manufactured by Nagase Chemtex) Denacol EX-810: Ethylene glycol diglycidyl ether (Nagase Chemtex) Denacol EX-512: Polyglycerol polyglycidyl ether (manufactured by Nagase Chemtex) Proxel GXL: Antiseptic and antifungal agent (manufactured by Lonza) Surfynol 104: Acetylene glycol surfactant (manufactured by Air Products Japan) diluted with propylene glycol to a 50% concentration. AQ515: BYK AQUACER515

[0089] [Table 1]

[0090] [Table 2]

[0091] (A) Measurement of average particle size For each of the ink samples obtained in the Examples and Comparative Examples, immediately after preparation and after storage in a sealed container at 60°C for 7 days, the ink was diluted with ion-exchanged water so that the concentration of the dye component was 0.02%, and each test liquid of the Examples and Comparative Examples was prepared. The D50 and D90 of each test liquid obtained were measured. A NANOTRAC WAVE II-EX150 (manufactured by Microtrack Bell) was used to measure D50 and D90.

[0092] (B) Preparation of bar coater coating Each ink of the Examples and Comparative Examples was applied to the entire surface of OK Topcoat+ (Oji Paper Co., Ltd.) using a bar coater No. 3 on an automatic coater (PI-1210, Tester Sangyo Co., Ltd.). After that, it was dried for 2 minutes in a thermostatic chamber at 120°C to obtain a test print.

[0093] [Storage stability] The rate of change in the average particle diameters D50 and D90 measured in (A) above between immediately after preparation and after storage for 7 days was calculated using the following formula, and each was evaluated on a 5-level scale of AA to D. The smaller the discrepancy between the measured values ​​immediately after preparation and after 7 days of storage, the better the stability, indicating excellent storage stability. The lowest evaluation index was used as the overall evaluation of storage stability. Change rate of physical property value = (measured value after 7 days storage - measured value immediately after preparation) / (measured value immediately after preparation) x 100% AA: Change rate is less than ±5% A: The rate of change is more than ±5% and less than ±10% B: The rate of change is more than ±10% and less than ±15% C: Change rate is more than ±15% and less than ±20% D: Change rate is ±20% or more

[0094] [Abrasion resistance test] The bar coater coating obtained in (A) above was rubbed 10 times against each other with a Gakushin tester manufactured by Yasuda Seiki Seisakusho Co., Ltd., with a load of 500 g. The bar coater coating of OK Topcoat+ attached to the Gakushin tester and the rubbed surface (scraped surface) were measured for color hues (L*, a*, b*) at five points using a spectrophotometer (eXact, manufactured by X-Rite) under light source D50 and status T conditions to determine the color difference. The smaller the color difference, the less color transfer to the rubbed surface and the better the abrasion resistance of the bar coater coating. The abrasion resistance was evaluated according to the following criteria. AA: ΔE is less than 2.5 A: ΔE is 2.5 or more and less than 3.0 B: ΔE is 3.0 or more and less than 4.0 C: ΔE is 4.0 or more and less than 5.0 D: ΔE is 5.0 or more Color difference (ΔE) = (ΔL* + Δa* + Δb*) 1 / 2

[0095] [Table 3]

[0096] From the results in Table 3, the inks of the examples have better storage stability and abrasion resistance than the inks of the comparative examples, and therefore the inks of the present invention are extremely useful as inkjet recording inks. [Industrial Applicability]

[0097] The dispersion of the present invention is excellent in storage stability and redispersibility, and is therefore extremely useful as an ink for various recording purposes, particularly as an ink for ink-jet recording.

Claims

1. A dispersion comprising a crosslinker and an acid group-containing resin, wherein a crosslinking value calculated by A / B is greater than 1.60 and is not greater than 3.00, where A is the molar equivalent number of crosslinking functional groups of the crosslinker, and B is the molar equivalent number of acidic functional groups of the acid group-containing resin.

2. The dispersion according to claim 1 , wherein the crosslinking value calculated by A / B is 1.65 or more and 2.70 or less.

3. The dispersion of claim 1 or 2 further comprising a colorant.

4. 3. The dispersion of claim 1 or 2, further comprising a wax.

5. An inkjet recording method, comprising ejecting droplets of the dispersion according to claim 1 or 2 from an inkjet head to record on a print medium.

6. The inkjet recording method according to claim 5 , wherein the print medium is a print medium that is poorly ink-absorbent or non-ink-absorbent.

7. A dispersion set comprising the dispersion according to claim 1 or 2 and another dispersion different from the dispersion.

8. A dispersion media set comprising at least one selected from the group consisting of the dispersion according to claim 1 or 2 and the dispersion set according to claim 7, and a printing medium.

9. A printing medium having adhered thereto at least one selected from the group consisting of the dispersion according to claim 1 or 2 and the dispersions contained in the dispersion set according to claim 7.

Images