Pretreatment liquid for use in inkjet printing - Patent Application 20070122997

Abstract

The present invention relates to an aqueous pretreatment liquid for use in inkjet printing, the aqueous pretreatment liquid comprising water; magnesium sulfate; and a crystallization retarder selected from the group consisting of sorbitol, xylitol, adonitol, β-alanine, proline, and γ-aminobutyric acid. The pretreatment liquid is non-yellowing, odorless, and does not crystallize upon drying. Prints made by using the pretreatment liquid according to the present invention in combination with aqueous inks show a significant reduction in edge curl after extended periods of time.

Description

[Technical Field]

[0001] The present invention relates to an aqueous pretreatment liquid for use in ink jet printing, and in particular to an aqueous pretreatment liquid suitable for application onto a recording substrate by an ink jet imaging device. [Background technology]

[0002] In the field of inkjet printing, pretreatment liquids are used to improve print quality. Pretreatment liquids contain components that react with components in the ink; for example, colloidal stability of dispersed pigment particles (present in the ink) is provided by metal salts (present in the pretreatment liquid). Therefore, upon contact between the ink composition and the pretreatment liquid, the dispersed pigment particles are destabilized, aggregated, and fixed to the surface of the recording substrate. Therefore, color bleeding and merging (between colors) on machine-coated (MC) paper can be prevented, resulting in improved print quality. On plain paper, OD increases and sheer decreases.

[0003] Pretreatment liquids are known in the prior art and usually contain either strongly acidic compounds or (poly)valent metal salts, which have the function of fixing agents and / or crushing agents.

[0004] Pretreatment liquids containing polyvalent metal salts, also called reaction solutions or reaction liquids, primer liquids, treatment liquids or ink-receiving solutions, are known from the prior art, in particular from US 6,419,352; US 6,786,588; US 8,523,342; US 8,591,018; US 2011 / 0303113; US 2012 / 0098883; US 2012 / 0314000; and WO 2014 / 051547.

[0005] Published U.S. Patent Application Publication No. 2012 / 0019588 discloses a fixing fluid for inkjet printing that contains metal carboxylates as fixing agents, particularly calcium acetate, calcium propionate, calcium butyrate, calcium bromide, calcium carbonate, calcium chloride, calcium citrate, calcium cyanamide, calcium phosphate, calcium lactate, calcium nitrate, calcium oxalate, and calcium sulfate.

[0006] Published US Patent Application Publication No. 2014 / 0055520 discloses an ink-receptive solution that includes at least one metal salt, particularly calcium chloride.

[0007] JP2014097632 discloses a treatment liquid for treating a recording medium, the treatment liquid containing at least a water-soluble organic solvent, an amphiphilic substance, an organic acid or an organic acid salt, and / or a cationic polymer, a hydrophobic crosslinking agent, and water. Bisethoxydiglycol succinate and sodium dilauroyl glutamate lysine can be cited as amphiphilic substances.

[0008] EP2489707A1 discloses an ink composition containing cyan or magenta pigment particles and (substantially) water-insoluble resin particles and / or water-insoluble wax particles. It also discloses an ink set containing such an ink and a treatment liquid containing an aggregating component that forms aggregates upon contact with the ink composition.

[0009] EP 0 761 783 A2 discloses an inkjet ink and an inkjet recording method, in which a reaction solution contains a reactant that is capable of disrupting the dispersed and / or dissolved state of a pigment in an ink composition when brought into contact with the ink composition.

[0010] WO2011 / 099977A1 ​​discloses a fixer composition for inkjet printing, which contains a metal carboxylate as a fixing agent.

[0011] EP 0 959 112 A1 discloses a reaction solution containing at least a polyvalent metal salt, ammonia, and benzotriazole or a benzotriazole derivative.

[0012] US2012 / 229558A1 discloses a processing solution for inkjet recording, comprising water and a basic amino acid or a salt thereof contained in the processing solution in an amount of 1% by weight or more. Disclosed examples of the basic amino acid are lysine, arginine, histidine, and ornithine.

[0013] US2012 / 0098883 discloses an aqueous primer (pretreatment liquid) containing magnesium sulfate, which provides a non-yellowing pretreatment liquid, which is preferable from the viewpoint of inkjet printing.

[0014] Magnesium sulfate is a non-toxic salt that has the benefits of being non-yellowing (like magnesium / calcium nitrate) and low odor (like magnesium / calcium acetate or magnesium / calcium propionate).

[0015] A disadvantage of pretreatment solutions containing magnesium sulfate as a crushing agent is that magnesium sulfate tends to crystallize in the primer solution, especially at high concentrations. A high concentration of crushing salt is desirable to allow for the application of a thin film of pretreatment solution using a minimum amount of liquid (e.g., water) to provide the correct amount of crushing agent to the surface of the printing substrate. Crystallization of the crushing agent in the pretreatment solution can impair the jetting ability of the pretreatment solution due to the presence of crystals that can form obstructions in the jetting path of the image-forming device. [Prior art documents] [Patent documents]

[0016] [Patent Document 1] U.S. Patent No. 6,419,352 [Patent Document 2] U.S. Patent No. 6,786,588 [Patent Document 3] U.S. Patent No. 8,523,342 [Patent Document 4] U.S. Patent No. 8,591,018 [Patent Document 5] US Patent Application Publication No. 2011 / 0303113 [Patent Document 6] US Patent Application Publication No. 2012 / 0098883 [Patent Document 7] US Patent Application Publication No. 2012 / 0314000 [Patent Document 8] International Publication No. 2014 / 051547 [Patent Document 9] US Patent Application Publication No. 2012 / 0019588 [Patent Document 10] US Patent Application Publication No. 2014 / 0055520 [Patent Document 11] Japanese Patent Application Publication No. 2014-097632 [Patent Document 12] European Patent Application Publication No. 2489707 [Patent Document 13] European Patent Application Publication No. 0761783 [Patent Document 14] International Publication No. 2011 / 099977 [Patent Document 15] European Patent Application Publication No. 0959112 [Patent Document 16] US Patent Application Publication No. 2012 / 229558 Summary of the Invention [Problem to be solved by the invention]

[0017] Therefore, an object of the present invention is to provide a pre-treatment liquid that is non-yellowing and odorless, has good jetting properties, and provides curl resistance. [Means for solving the problem]

[0018] (Summary of the Invention) The target product can be obtained at least in part by the pretreatment liquid according to claim 1.

[0019] Such a pretreatment liquid contains, in addition to water and magnesium sulfate, a crystallization retarder, which is a non-migratory solvent that becomes crystalline after the printed matter dries, and this can reduce curl caused by migratory liquid solvents, such as glycerol, ethylene glycol, and 2-pyrrolidone, which are often required in ink compositions.

[0020] Suitable non-migrating solvents are sorbitol, xylitol, adonitol, β-alanine, proline, and γ-aminobutyric acid.

[0021] In one embodiment, magnesium sulfate is present at a concentration of greater than 10 wt % based on anhydrous magnesium sulfate of the total pretreatment composition.

[0022] In one embodiment, the crystallization retarder is present in an amount greater than 10 wt %, preferably greater than 12 wt %, and more preferably greater than 15 wt % of the total pretreatment composition.

[0023] For a more complete understanding of the present invention and its advantages, exemplary embodiments of the invention will be described in more detail in the following description with reference to the accompanying drawings, in which like reference characters indicate like elements, and in which: [Brief explanation of the drawings]

[0024] [Figure 1] Results of evaporation experiments: A) magnesium sulfate solution, B) pretreatment solution containing magnesium sulfate and β-alanine (Comparative Example A and Examples 1 and 2). [Figure 2] Results of evaporation experiments of several pretreatment solutions according to the present invention, including co-solvents: A) sorbitol (Example 3); B) β-alanine (Example 4); C) γ-aminobutyric acid (Example 5); and D) proline (Example 6). [Figure 3] Results from printing examples showing curl one month after printing for A) no pretreatment; B) pretreatment 2; C) pretreatment 1. DETAILED DESCRIPTION OF THE INVENTION

[0025] Pretreatment liquid The pretreatment solution of the present invention contains a metal sulfate, which is a non-yellowing, odorless crushing agent. The pretreatment solution may also contain additives such as cosolvents, pH adjusters, and surfactants. The pretreatment solution of the present invention is suitable for use on plain paper and machine-coated (MC) paper, as is well known in the art.

[0026] metal salts The metal sulfates that can be suitably used in the pretreatment solution of the present invention contain monovalent metal ions, such as Li + , Na + , K. + , Hg + , Cu + , and Ag + However, it is preferable to be able to apply a thin layer of the pretreatment solution to the printing substrate (especially paper-like substrates) to prevent deformation of the printing substrate. Therefore, salts that provide a relatively high ionic strength to provide an effective pretreatment solution in a thin layer are preferred.

[0027] In the context of the present invention, ionic strength is determined by the formula 1:

[0028]

number

[0029] For example, the ionic strength of a 0.5 mol / l Na2SO4 solution is 0.5*(2*0.5*(1) 2 +1*0.5*(-2) 2 )=1.5M is.

[0030] Another criterion that must be observed is that the solubility of the selected salt is high enough to be able to prepare an effective reaction solution. For these reasons, polyvalent metal ions, such as Ca, 2+ , Mg 2+ , Sr 2+ , Zn 2+ , Cu 2+ , Ni 2+ , Fe 3+ , Cr 3+ , and Al 3+ Among these, Mg is preferred for HSE reasons. 2+ and Ca 2+ CaSO4 is insoluble in water, and therefore, for the reasons mentioned above, Mg 2+ is most preferred.

[0031] Typically, the pretreatment solution of the present invention contains 10 wt% to 60 wt%, preferably 15 wt% to 50 wt%, and more preferably 20 wt% to 40 wt% of a polyvalent metal sulfate based on the total composition. However, the amount of salt is limited by the maximum solubility of the salt. The saturation of the salt in the pretreatment solution (actual concentration / maximum solubility * 100%) is generally 10% to 100%, preferably 15% to 95%, and more preferably 20% to 80%.

[0032] Co-solvent A cosolvent may be added to the pretreatment liquid to meet jettability requirements. The cosolvent has multiple functions, such as improving the rheological behavior of the pretreatment liquid and / or preventing the pretreatment liquid from drying within the image-forming device or on the nozzle surface of the image-forming device, which can lead to the precipitation of metal salts within the image-forming device or on the nozzle plate. A cosolvent may also be used to improve the penetration of the main solvent (water) into the printing substrate; such a cosolvent is also called a penetrant. The type of cosolvent used is not limited to any particular type, as long as the effects of the present invention are maintained. Cosolvents similar to those used in (aqueous) ink compositions can also be suitably used in the pretreatment liquid according to the present invention. Examples of suitable cosolvents include water-soluble organic solvents such as polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, ammonium compounds, sulfur-containing compounds, propylene carbonate, and ethylene carbonate. In the present invention, a solid cosolvent is used that is a non-migratory component when printed onto a substrate, and thus can compete with the migratory cosolvent present in the ink composition printed on top of the applied pretreatment layer, thus preventing or at least reducing (long-term) curl of the print.

[0033] Examples of water-soluble organic solvents include (but are not limited to) glycerin (also called glycerol), propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols preferably having a molecular weight between 200 grams / mol and 1000 grams / mol (e.g., PEG200, PEG400, PEG600, PEG800, PEG1000), glycerin ethoxylate, pentaerythritol ethoxylate, polyethylene glycol (di)methyl ether preferably having a molecular weight between 200 grams / mol and 1000 grams / mol, trimethylolpropane, diglycerol (diglycerin), trimethylglycine (betaine), N-methylmorpholine N-oxide, decaglycerin, 1,4-butanediol, 1,3-butanediol, 1,2,6-Hexanetriol, 2-pyrrolidinone, dimethylimidazolidinone, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether Examples of suitable olefin glycols include ethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, tripropylene glycol dibutyl ether, 3-methyl 2,4-pentanediol, diethylene glycol monoethyl ether acetate, 1,2-hexanediol, 1,2-pentanediol, and 1,2-butanediol.

[0034] Suitable solid cosolvents that provide curl resistance include, but are not limited to, xylitol, betaine (trimethylglycine), isosorbide, dimethylurea (DMU), sorbitol, and adonitol. Examples of other curl-resistant (solid) cosolvents are certain amino acids, such as (but not limited to) β-alanine, proline, and γ-aminobutyric acid.

[0035] In one embodiment, a mixture of water-soluble organic solvents may be included in the pretreatment liquid of the present invention, with each organic solvent preferably being present in an amount of 1 to 40% by weight, more preferably 3 to 30% by weight, and even more preferably 5 to 20% by weight, based on the total weight of the ink composition.

[0036] pH adjuster To meet the pH requirements specified for the printhead used, a pH-adjusting agent can be added to the pretreatment liquid to optimize the pH of the pretreatment liquid. Generally, the pH specification for the printhead is in the alkaline region (i.e., pH > 7). Therefore, alkaline pH-adjusting agents are preferred. Examples of suitable pH-adjusting agents include (but are not limited to) KOH, ammonia, (secondary and tertiary) amines, and aminoalcohols, particularly N-alkyl-dialkanolamines. Specific examples of suitable aminoalcohols include triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, Nn-butyl-monoethanolamine, and Nn-butyl-diethanolamine.

[0037] Typically, the pH adjuster is present in the pretreatment solution in a small amount, particularly less than 1 wt % of the total pretreatment solution composition, but the pH adjuster can be suitably applied in any amount until the desired pH is reached and the effects of the present invention are maintained.

[0038] surfactants A surfactant can be added to the pretreatment liquid to improve the spreading behavior of the pretreatment liquid on the printing substrate. Examples of suitable surfactants are not limited to any particular type, as long as the effects of the present invention are maintained.

[0039] Examples of surfactants include nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, particularly betaine surfactants, silicone surfactants, and fluorosurfactants, and in particular at least one selected from acetylene surfactants, silicone surfactants, and fluorosurfactants.

[0040] Examples of cationic surfactants include aliphatic amine salts, aliphatic quaternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts.

[0041] Examples of anionic surfactants include alkyl sulfates, sodium dodecyl sulfate (SDS), polyoxyethylene alkyl ether acetates, dodecylbenzenesulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates, fatty acid soaps, N-acyl-N-methylglycinates, N-acyl-N-methyl-β-alanines, N-acylglutamates, acylated peptides, alkyl sulfonates, alkylbenzenesulfonates, alkylnaphthalenesulfonates, dialkyl sulfosuccinates (e.g., sulfosuccinates), and the like. Dioctyl succinate sodium salt (DSS; also known as docusate sodium, aerosol OT, and AOT), alkyl sulfoacetates, α-olefin sulfonates, N-acyl-methyltaurine, sulfonated oils, higher alcohol sulfates, secondary higher alcohol sulfates, alkyl ether sulfates, secondary higher alcohol ethoxy sulfates, polyoxyethylene alkylphenyl ether sulfates, monoglycerides, fatty acid alkylolamide sulfates, alkyl ether phosphates, and alkyl phosphates.

[0042] Examples of amphoteric surfactants include carboxybetaine types, sulfobetaine types, aminocarboxylates, and imidazolium betaines.

[0043] Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxypropylene polyoxyethylene alkyl ethers, polyoxyethylene secondary alcohol ethers, polyoxyethylene alkylphenyl ethers, polyoxyethylene sterol ethers, polyoxyethylene lanolin derivatives, polyoxyethylene polyoxypropylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene glycerin fatty acid esters, polyoxyethylene castor oil, hydrogenated castor oil, polyoxyethylene sorbitol fatty acid esters, polyethylene glycol fatty acid esters, fatty acid monoglycerides, polyglycerin fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty esters, propylene glycol fatty acid esters, cane sugar fatty acid esters, fatty acid alkanolamides, polyoxyethylene alkylamides, polyoxyethylene fatty acid amides, polyoxyethylene alkylamines, alkylamine oxides, alkoxylated alcohols, acetylene glycol, ethoxylated acetylene glycol, and acetylene alcohols.

[0044] As the fluorosurfactant, a surfactant having 2 to 16 fluorine-substituted carbon atoms is preferred, and a surfactant having 4 to 16 fluorine-substituted carbon atoms is more preferred. If the number of fluorine-substituted carbon atoms is less than 2, the effects specific to fluorosurfactants may not be obtained. If it exceeds 16, storage stability may be reduced.

[0045] Examples of fluorosurfactants include nonionic fluorosurfactants, anionic fluorosurfactants, and amphoteric fluorosurfactants.

[0046] Examples of nonionic fluorosurfactants include perfluoroalkyl phosphate ester compounds, perfluoroalkyl ethylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups as side chains. Among these, polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups as side chains are preferred because they have low foaming properties.

[0047] As the fluorosurfactant, commercially available products may be used.

[0048] Examples of commercially available products include SURFLON S-HI, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all of which are manufactured by Asahi Glass Co., Ltd.), FLUORAD FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, and FC-431 (all of which are manufactured by Sumitomo 3M Limited), MEGAFAC F-470, F-1405, and F-474 (all of which are manufactured by Dainippon Ink and Chemicals, Inc.), ZONYL Examples include TBS, FSP, FSA, FSN-100, FSN, FSG-100, FSO, FS-300, and UR (all of which are manufactured by DuPont de Nemours), FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW (all of which are manufactured by Neos Corporation), and POLYFOX PF-136A, PF-156A, PF-151N, PF-154, and PF-159 (all of which are manufactured by OMNOVA Solutions Inc.). Among these, ZONYL FS-300 (manufactured by EI du Pont de Nemours and Company), FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (manufactured by NEOS Corporation), and POLYFOX PF-151N (manufactured by OMNOVA Solutions Inc.) are preferred because they are excellent in print quality, particularly in color development ability and dye leveling ability.

[0049] The silicone surfactant is not particularly limited and can be suitably selected depending on the intended use.

[0050] Examples of silicone surfactants include side-chain-modified polydimethylsiloxane, both-end-modified polydimethylsiloxane, one-end-modified polydimethylsiloxane, and side-chain / both-end-modified polydimethylsiloxane. Polyether-modified silicone surfactants having polyoxyethylene groups or polyoxyethylenepolyoxypropylene groups as modifying groups are particularly preferred because they exhibit excellent physical properties as aqueous surfactants.

[0051] Silicone surfactants may be suitably synthesized or commercially available products may be used, such as those readily available from BYK Chemie GmbH, Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Silicone Co., Ltd., Nippon Emulsion Co., Ltd., and Kyoeisha Chemical Co., Ltd.

[0052] The polyether-modified silicone surfactant is not particularly limited and can be suitably selected depending on the intended use. Examples thereof include compounds in which a polyalkylene oxide structure represented by Formula 1 is contained in the Si moiety side chain of dimethylpolysiloxane.

[0053] [ka] In the formula, X=-R(C2H4O) a (C3H6O) b R'.

[0054] In Formula 1, x, y, a, and b are each an integer; R represents an alkyl group, and R' represents an alkylene group.

[0055] As the polyether-modified silicone surfactant / polyalkylene oxide-modified silicone, commercially available products may be used.

[0056] Commercially available examples include KF-618, KF-642, and KF-643 (manufactured by Shin-Etsu Chemical Co., Ltd.); EMALEX-SS-5602 and SS-1906EX (manufactured by Nippon Emulsion Co., Ltd.); FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, and FZ-2164 (manufactured by Dow Corning Toray Silicone Co., Ltd.); and BYK-33, BYK331, BYK341, BYK348, BYK349, BYK3455, BYK-387 (manufactured by BYK Chemie GmbH); Tegowet 240, Tegowet 245, Tegowet 250, Tegowet 260 (manufactured by Evonik); Silwet L-77 (manufactured by Sabic), and DBE714 surfactants.

[0057] Any of the surfactants mentioned in this section may be used alone or in combination.

[0058] Ethoxylated acetylenic glycols have the general structure shown in Formula 2.

[0059] [ka]

[0060] wherein R1 and R4 are the same or different alkyl groups having 3 to 10, preferably 3 to 6, carbon atoms, preferably R1 and R4 are the same, R2 and R3 are the same or different and are selected from methyl and ethyl, preferably R2 and R3 are both methyl, and x and y are both integers, having a sum ranging between 1 and 60.

[0061] In one embodiment, an ethoxylated acetylenic glycol according to Formula 2 is used as a surfactant in an ink composition according to the present invention, either alone or in combination with other surfactants, wherein x and y are independent of each other and each range from 0 to 25, preferably from 0 to 20, more preferably from 0 to 15, with the proviso that at least one of x and y is greater than 0.

[0062] Specific examples of ethoxylated acetylenic glycols include ethoxylated 3-methyl-1-nonyn-3-ol, ethoxylated 7,10-dimethyl-8-hexadecyne-7,10-diol, ethoxylated 4,7-dimethyl-5-decyne-4,7-diol, ethoxylated 2,4,7,9-tetramethyl-5-decyne-4,7-diol, and ethoxylated 2,5,8,11-tetramethyl-6-dodecyne-5,8-diol, which may be used in combination with one another.

[0063] The surfactants may be used individually and in combination.

[0064] ink Any ink composition containing dispersed particles that aggregate upon contact with the salt contained in the pretreatment liquid may be used. The dispersed particles may be colorant particles, particularly pigment particles, and / or latex particles. Examples of suitable inks are aqueous pigment inks and latex inks, in which particles (e.g., pigment particles and / or latex particles) present in the ink are susceptible to reaction with the metal salt present in the primer composition according to the present invention. Such ink compositions are disclosed, for example, in published International Patent Application Publication No. WO 2013 / 131924, particularly in the Examples and cited prior art, which are incorporated herein by reference.

[0065] coloring agent The colorant particles may be a pigment or a mixture of pigments, a dye or a mixture of dyes, or a mixture including a pigment and a dye, so long as the colorant is water-dispersible.

[0066] Examples of pigments that can be used in the present invention include, but are not limited to, commonly known pigments, and either water-dispersible pigments or oil-dispersible pigments can be used. For example, organic pigments such as insoluble pigments or lake pigments, as well as inorganic pigments such as carbon black, can be preferably used.

[0067] Examples of insoluble pigments are not particularly limited, but preferred are azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, or diketopyrrolopyrrole dyes.

[0068] Examples include inorganic and organic pigments for black and color inks. These pigments may be used alone or in combination. Inorganic pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, as well as carbon black produced by known methods such as catalytic, furnace, and thermal processes.

[0069] Examples of organic pigments that can be used include azo pigments (including azo lakes, insoluble azo pigments, condensation pigments, and chelate azo pigments), polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments), dye chelates (e.g., basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, and aniline black. Among these, pigments with high affinity for water are particularly preferred.

[0070] Specific pigments that can be preferably used are listed below.

[0071] Examples of magenta or red pigments include CI Pigment Red 1, CI Pigment Red 2, CI Pigment Red 3, CI Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CI Pigment Red 15, CI Pigment Red 16, CI Pigment Red 17, CI Pigment Red 22, CI Pigment Red 23, CI Pigment Red 31, CI Pigment Red 38, CI Pigment Red 48:1, CI Pigment Red 48:2 (Permanent Red 2 B(Ca)), CI Pigment Red 48:3, CI Pigment Red 48:4, CI Pigment Red 49:1, CI Pigment Red 52:2; CI Pigment Red 53:1, CI Pigment Red 57:1 (Brilliant Carmine 6B), CI Pigment Red 60:1, CI Pigment Red 63:1, CI Pigment Red 64:1, CI Pigment Red 81, CI Pigment Red 83, CI Pigment Red 88, CI Pigment Red 101 (Red Iron Oxide), CI Pigment Red 104, CI Pigment Red 106, CI Pigment Red 108 (Cadmium Red), CI Pigment Red 112, CI Pigment Red 114, CI Pigment Red 122 (Quinacridone Magenta), CI Pigment Red 123, CI Pigment Red 139, CI Pigment Red 44, CI Pigment Red 146, CI Pigment Red 149, CI Pigment Red 166, CI Pigment Red 168, CI Pigment Red 170, CI Pigment Red 1 72, CI Pigment Red 177, CI Pigment Red 178, CI Pigment Red 179, CI Pigment Red 185, CI Pigment Red 190, CI Pigment Red 193, CI Pigment Red 209, CI Pigment Red 219, and CI Pigment Red 222, CI Pigment Violet 1 (Rhodamine Lake), CI Pigment Violet 3, CI Pigment Violet 5:1, CI Pigment Violet 16, CI Pigment Violet 19, C.CI Pigment Violet 23, and CI Pigment Violet 38.

[0072] Examples of orange or yellow pigments include CI Pigment Yellow 1, CI Pigment Yellow 3, CI Pigment Yellow 12, CI Pigment Yellow 13, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 15:3, CI Pigment Yellow 17, CI Pigment Yellow 24, CI Pigment Yellow 34, CI Pigment Yellow 35, CI Pigment Yellow 37, CI Pigment Yellow 42 (yellow iron oxide), CI Pigment Yellow 53, CI Pigment Yellow 55, CI Pigment Yellow 74, CI Pigment Yellow 81, CI Pigment Yellow 83, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 95, CI Pigment Yellow 97, and CI Pigment Yellow 9. 8, CI Pigment Yellow 100, CI Pigment Yellow 101, CI Pigment Yellow 104, CI Pigment Yellow 408, CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 117, CI Pigment Yellow 120, CI Pigment Yellow 128, CI Pigment Yellow 138, CI Pigment Yellow 150, CI Pigment Yellow 151, CI Pigment Yellow 153, and CI Pigment Yellow 183; CI Pigment Orange 5, CI Pigment Orange 13, CI Pigment Orange 16, CI Pigment Orange 17, CI Pigment Orange 31, CI Pigment Orange 34, CI Pigment Orange 36, CI Pigment Orange 43, and CI Pigment Orange 51.

[0073] Examples of green or cyan pigments include CI Pigment Blue 1, CI Pigment Blue 2, CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3 (Phthalocyanine Blue), CI Pigment Blue 16, CI Pigment Blue 17:1, CI Pigment Blue 56, CI Pigment Blue 60, CI Pigment Blue 63, CI Pigment Green 1, CI Pigment Green 4, CI Pigment Green 7, CI Pigment Green 8, CI Pigment Green 10, CI Pigment Green 17, CI Pigment Green 18, and CI Pigment Green 36.

[0074] In addition to the above pigments, when red, green, blue, or intermediate colors are required, the following pigments are preferably employed individually or in combination: Examples of pigments that can be employed include CI Pigment Red 209, 224, 177, and 194, CI Pigment Orange 43, CI Vat Violet 3, CI Pigment Violet 19, 23, and 37, CI Pigment Green 36 and 7, and CI Pigment Blue 15:6.

[0075] Further, examples of black pigments include CI Pigment Black 1, CI Pigment Black 6, CI Pigment Black 7, and CI Pigment Black 11. Specific examples of pigments for black inks that can be used in the present invention include carbon black (e.g., furnace black, lamp black, acetylene black, and channel black); (CI Pigment Black 7) or metallic pigments (e.g., copper, iron (CI Pigment Black 11), and titanium oxide); and organic pigments (e.g., aniline black (CI Pigment Black 1)).

[0076] The amount of water-insoluble pigment contained in the inkjet ink is preferably 0.5% to 15% by weight, more preferably 0.8% to 10% by weight, and even more preferably 1% to 6% by weight, in terms of solid content. If the amount of water-insoluble pigment is less than 0.5% by weight, the color development ability and image density of the ink may decrease. If it exceeds 15% by weight, the viscosity of the ink increases, which can adversely affect ink ejection stability.

[0077] latex particles The inkjet inks in the ink set according to the present invention may contain a water-dispersible resin (latex resin) in consideration of pigment fixation to a recording medium. A water-dispersible resin having excellent film-forming properties (image-forming properties), high water repellency, high water resistance, and high weather resistance is useful for recording images with high water resistance and high image density (high color development ability).

[0078] Examples of water-dispersible resins include synthetic resins and natural polymer compounds.

[0079] Examples of synthetic resins include polyester resins, polyurethane resins, polyepoxy resins, polyamide resins, polyether resins, poly(meth)acrylic resins, acrylic-silicone resins, fluorine-based resins, polyolefin resins, polystyrene-based resins, polybutadiene-based resins, polyvinyl acetate-based resins, polyvinyl alcohol-based resins, polyvinyl ester-based resins, polyvinyl chloride-based resins, polyacrylic acid-based resins, unsaturated carboxylic acid-based resins, and copolymers such as styrene-acrylate copolymer resins and styrene-butadiene copolymer resins.

[0080] Examples of natural polymer compounds include cellulose, rosin, and natural rubber.

[0081] In one embodiment, the water-dispersible resin used in the present invention may be made of a resin having water-soluble functional groups such as carboxylic acid groups or sulfonic acid groups.

[0082] In one embodiment, the ink composition according to the present invention contains a resin having a carboxylic acid group with a low dissociation rate, which allows for rapid aggregation of the water-dispersible resin. Carboxylic acid groups tend to be affected by pH changes, so their dispersion state changes easily and their aggregation properties are high. Examples of resins suitable for use in ink compositions according to embodiments of the present invention include acrylic resins, vinyl acetate resins, styrene-butadiene resins, vinyl chloride resins, acrylic-styrene resins, butadiene resins, and styrene resins. The resin component of the water-dispersible resin is preferably a polymer having both hydrophilic and hydrophobic moieties within the molecule. By having the hydrophobic moiety, the hydrophobic moiety can be oriented toward the inside of the water-dispersible resin, and the hydrophilic moiety can be oriented toward the outside of the water-dispersible resin. As a result, the dispersion state changes more significantly in response to pH changes in the liquid, resulting in more efficient aggregation of the ink.

[0083] Examples of commercially available water-dispersible resin emulsions include Joncryl 537 and 7640 (styrene-acrylic resin emulsions, manufactured by Johnson Polymer Co., Ltd.), Microgel E-1002 and E-5002 (styrene-acrylic resin emulsions, manufactured by Nippon Paint Co., Ltd.), Voncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), Voncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink and Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Jurymer ET-410 (acrylic resin emulsion, manufactured by Nihon Junyaku Co., Ltd.), Aron HD-5 and A-104 (acrylic resin emulsion, manufactured by Toa Gosei Co., Ltd.), Saibinol SK-200 (acrylic resin emulsion, manufactured by Saiden Chemical Co., Ltd.), and Zaikthene L (acrylic resin emulsion, manufactured by Sumitomo Seika Chemicals Co., Ltd.), acrylic copolymer emulsions from DSM Neoresins, such as the NeoCryl product line, in particular the acrylic styrene copolymer emulsions NeoCryl A-662, NeoCryl A-633, NeoCryl A-1131, NeoCryl A-2091, NeoCryl A-550, NeoCryl BT-101, NeoCryl SR-270, NeoCryl XK-52, NeoCryl XK-39, NeoCryl XK-205, NeoCryl A-1044, NeoCryl A-1049, NeoCryl A-1110, NeoCryl A-1120, NeoCryl A-1127, NeoCryl A-2092, NeoCryl A-2099, NeoCryl A-308, NeoCryl A-409, NeoCryl A-509, NeoCryl A-609, NeoCryl A-610, NeoCryl A-621, NeoCryl A-633, NeoCryl A-1131, NeoCryl A-2091, NeoCryl A-550, NeoCryl BT-101, NeoCryl SR-270, NeoCryl XK-52, NeoCryl XK-39, NeoCryl XK-205, NeoCryl A-1044, NeoCryl A-1049, NeoCryl A-1110, NeoCryl A-1120, NeoCryl A-1127, NeoCryl A-2092, NeoCryl A-2099, NeoCryl A-308, NeoCryl A-409, NeoCryl A-409, NeoCryl A-409, NeoCr Examples of water-dispersible resin emulsions include NeoCryl A-45, NeoCryl A-615, NeoCryl BT-24, NeoCryl BT-26, NeoCryl BT-36, NeoCryl XK-15, NeoCryl X-151, NeoCryl XK-232, NeoCryl XK-234, NeoCryl XK-237, NeoCryl XK-238, NeoCryl XK-86, NeoCryl XK-90, and NeoCryl XK-95. However, the water-dispersible resin emulsion is not limited to these examples.

[0084] As the fluororesin, fluororesin fine particles having a fluoroolefin unit are preferred. Among these, fluorine-containing resin fine particles containing a fluoroolefin unit and a vinyl ether unit are particularly preferred. The fluoroolefin unit is not particularly limited and can be suitably selected according to the intended use. Examples thereof include -CFCF-, -CFCF(CF)-, and -CFCFCl-.

[0085] The vinyl ether unit is not particularly limited and can be suitably selected depending on the intended use. Examples thereof include -C(R a )HC(OR b )-(wherein, R a is a hydrogen atom or a methyl group; R b Ha-CH2R c , -C2H4R c , -C3H6R c , -C4H8R c , and -CH 10 R c wherein R c is selected from the group consisting of a hydrogen atom (-H), a hydroxy group (-OH), or a carboxylic acid group (-COOH).

[0086] As the fluorine-containing vinyl ether resin microparticles containing fluoroolefin units and vinyl ether units, an alternating copolymer in which fluoroolefin units and vinyl ether units are alternately copolymerized is preferred.As such fluorine-containing resin microparticles, a compound that is suitably synthesized may be used, or a commercially available product may be used.Examples of commercially available products include FLUONATE FEM-500 and FEM-600, DICGUARD F-52S, F-90, F-90M, F-90N, and AQUAFURFURAN TE-5A manufactured by Dainippon Ink and Chemicals, Inc.; LUMIFLON FE4300, FE4500, FE4400, ASAHI GUARD AG-7105, AG-950, AG-7600, AG-7000, and AG-1100 manufactured by Asahi Glass Co., Ltd.

[0087] The water-dispersible resin may be used in the form of a homopolymer, copolymer, or composite resin, and any water-dispersible resin having a single phase structure or a core-shell structure, and those prepared by power-feed emulsion polymerization may be used.

[0088] Water-dispersible resins can be those that contain hydrophilic groups and thus have a certain degree of self-dispersibility, or those that do not have dispersibility themselves but are rendered dispersible by the use of surfactants and / or other resins containing hydrophilic groups. Among these resins, emulsions of resins obtained by emulsion or suspension polymerization of ionomers of polyester or polyurethane resins are most suitable. In the case of emulsion polymerization of unsaturated monomers, resin dispersions are obtained by initiating the polymerization reaction of the dispersed monomer phase in an emulsion of monomer in water. Polymerization initiators, surfactants, chain transfer agents, chelating agents, and pH adjusters may also be added to the emulsion of monomer in water. Therefore, water-dispersible resins are easily obtained, and the resin components can be varied to easily achieve desired properties.

[0089] The content of the water-dispersible resin added to the ink of the present invention is preferably 1 to 40% by weight, more preferably 1.5 to 30% by weight, and even more preferably 2 to 25% by weight, based on the total weight of the ink.

[0090] Even more preferably, the amount of the water-dispersible resin contained in the inkjet ink is 2.5 to 15% by weight, more preferably 3 to 7% by weight, in terms of solid content, relative to the total ink composition.

[0091] The ink may contain additives such as co-solvents and surfactants, which are not limited to any particular type and may be similar to the co-solvents and surfactants used in the pretreatment liquid according to the present invention as described above.

[0092] The ink set according to the present invention comprises the pretreatment liquid according to the present invention and the ink composition as described above. [Example]

[0093] material Multiwet Sil was obtained from Croda; Latex dispersion Neocryl XK205 was obtained from DSM Neoresins; Pigment dispersion COJ 450 C was obtained from Cabot. All other materials were obtained from Sigma Aldrich. All materials were used as received.

[0094] Comparative Example A (CE-A): Evaporation experiment of magnesium sulfate solution. A 27.1 wt% solution of magnesium sulfate heptahydrate (MgSO4.7H2O) was prepared by adding 27.1 grams of magnesium sulfate heptahydrate to 72.9 grams of demineralized water (or other equivalent amount). The mixture was stirred until the MgSO4.7H2O was completely dissolved. Five grams of the mixture was added to a disposable aluminum tray and allowed to stand at room temperature for three days. The residue was weighed. In this particular example, the volume of solution was 5.00 grams. The weight of the residue was 1.94 grams. The residue was therefore 38.8 wt% of the original sample. A photograph of the sample (Figure 1A) clearly shows the crystallization of magnesium sulfate.

[0095] Example 1 Preparation of a pretreatment solution according to the present invention (pretreatment solution 1). A pretreatment solution was prepared by adding 27.11 grams of magnesium sulfate heptahydrate (MgSO4.7H2O), 20 grams of β-alanine, 5 grams of 1 M acetic acid, 0.85 grams of Nn-butyldiethanolamine, 0.40 grams of Empigen BB, and 0.20 grams of Multiwet SU to 46.44 grams of water to obtain 100 grams of Pretreatment Solution 1.

[0096] Example 2 Evaporation experiment of pretreatment liquid 1. Five grams of the pretreatment solution was added to a disposable aluminum tray and allowed to sit at room temperature for three days. The residue was weighed. In this particular example, the amount of solution was 4.99 grams. The weight of the residue was 1.93 grams. The residue was therefore 38.7 wt% of the original sample. A photograph of the sample (Figure 1B) clearly shows no signs of magnesium sulfate crystallization.

[0097] [Examples 3 to 6] Evaporation experiments of mixtures containing magnesium sulfate and sorbitol, β-alanine, γ-aminobutyric acid, and proline as cosolvents, respectively. To obtain aqueous solutions containing 25 wt% MgSO4.7H2O and 20 wt% cosolvents, namely sorbitol (Example 3), β-alanine (Example 4), γ-aminobutyric acid (Example 5), and proline (Example 6), 2.5 gr of MgSO4.7H2O, 2 grams of cosolvent, and 5.5 gr of demineralized water were mixed. 1 ml of each was dispensed into disposable aluminum trays and dried at 30% relative humidity for one week. The photograph in Figure 2 clearly shows no signs of crystallization.

[0098] The solutions tested showed no signs of crystallization, indicating that the co-solvents used can be used to effectively prevent crystallization and prepare jettable pretreatment solutions. A composition containing 27 wt% MgSO4 and 12.5 wt% β-alanine was found to exhibit no crystallization whatsoever.

[0099] Example 6 Preparation of a pretreatment solution according to the present invention (pretreatment solution 2). A pretreatment solution was prepared according to Example 1, using 17.50 grams of xylitol instead of 20 grams of β-alanine. The difference was made up by adding 2.5 grams of additional demineralized water. 100 grams of pretreatment solution was obtained.

[0100] Example 7 Preparation of Ink Compositions for Use in Printing Experiments 8-10 Inks were prepared by adding the ingredients as shown in Table 1 (preferably in the order set out in Table 1 with stirring between) to obtain the compositions as shown in Table 1.

[0101] [Table 1]

[0102] [Examples 8 to 10] Printing experiments All printing experiments were carried out on a printing apparatus containing a 600 DPI Kyocera KJ4B printhead. Both the pretreatment and the ink were ejected in this manner. The printing substrate used was Soporset premium offset from Igepa.

[0103] Three printing experiments were carried out, each in duplicate. First, the 8.5 gr / m2 paper prepared in Example 7 was used. 2 A single (single-sided) print was made by applying the ink composition of 2 gr / m as prepared in Example 6 to the print substrate shown above (Example 8, Figure 3A). 2 Pre-treatment solution 2 of 8.5 gr / m prepared in Example 7 was then applied. 2 A single print was made by applying the ink composition of Example 9 (FIG. 3B). Thirdly, the previous experiment was repeated using Pretreatment Solution 1 as prepared in Example 1 (Example 10, FIG. 3C). The print was dried and fixed with the aid of IR irradiation (drying and fixing in one step). The printed sheet was exposed to IR irradiation for 5 seconds. The drying and fixing temperature was approximately 90°C.

[0104] Two sheets were cut from each experiment to obtain two full-bleed prints per experiment (no unprinted paper surrounding the printed area), and the curl of the paper was tracked as a function of time.

[0105] The photograph in Figure 3 shows the curl one month after printing, and it can be clearly seen that the use of the pre-treatment liquid according to the invention significantly reduces the (inward) curl.

[0106] Example 11: Determination of color shift (lightfastness) and yellowing of white paper The color shift (also known as lightfastness), expressed as ΔE2000, of samples of the printing substrate Soporset premium offset (with and without application of a pretreatment liquid) obtained from Igepa is determined using an Xrite lab measuring device according to ASTM D3424-11, method 3. The samples are irradiated with a xenon light source at a wavelength of 420 nm at a temperature of 63°C. The measurements are carried out immediately after sample preparation and repeated after 3 days. All measurements are carried out in triplicate. ΔE2000 (color shift) is determined and is a direct indicator of yellowing. The measurement results are shown in Table 2. The salt concentration used in these tests was 1.1 mol / kg for all salts used. Table 2 shows that the pretreatment solution containing 28.2 wt% magnesium nitrate (Mg(NO3)2.6H2O) exhibits a significant color shift relative to blank paper, while the pretreatment solution containing 27.1 wt% magnesium sulfate (MgSO4.7H2O) exhibits a significantly lower color shift and therefore has improved "yellowing" performance, i.e., a less pronounced yellowing effect.

[0107] [Table 2]

[0108] Thus, due to the selection of a crushing agent, magnesium sulfate, which can be present in high concentrations through the use of a crystallization retarder selected from the group consisting of sorbitol, xylitol, adonitol, β-alanine, proline, and γ-aminobutyric acid, the pretreatment solution according to the present invention is non-yellowing and odorless. The pretreatment composition as a whole further provides a significant reduction in (inward) curl.

Claims

1. 1. An aqueous pretreatment liquid for use in inkjet printing, comprising: a. water; b. magnesium sulfate; and c. a crystallization retarder selected from the group consisting of β-alanine, proline, and γ-aminobutyric acid An aqueous pretreatment solution comprising:

2. The magnesium sulfate content of the pretreatment liquid composition is anhydrous MgSO 4 ４ 10. The aqueous pretreatment solution of claim 1, wherein the aqueous pretreatment solution is present in a concentration greater than 10 wt. % based on the total weight of the aqueous pretreatment solution.

3. 3. The aqueous pretreatment solution of claim 1, wherein the crystallization retarder is present in an amount greater than 10 wt % based on the total pretreatment solution composition.

4. Use of an agent selected from the group consisting of sorbitol, xylitol, adonitol, beta-alanine, proline, and gamma-aminobutyric acid as a crystallization retarder in an aqueous pretreatment liquid for use in inkjet printing, wherein the aqueous pretreatment liquid further contains water and magnesium sulfate.

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