Binder resin for liquid ink, liquid ink containing said binder resin, and printed matter

Abstract

The present invention is able to provide: a binder resin for liquid inks, the binder resin being used for a liquid ink which is improved in terms of highlight transferability and plate fogging for the purpose of enhancing the aesthetic decoratability, while being improved in terms of adhesiveness, deinking properties and chemical resistance for the purpose of imparting functionalities; a liquid ink which contains this binder resin; and a printed material. A binder resin for liquid inks according to the present invention contains at least one resin that is selected from the group consisting of a polyurethane resin and an acrylic resin. The Trouton ratio of this binder resin for liquid inks is 3.0 to 10.0 as measured at 30°C with a solid content of 30%.

Description

[Technical field]

[0001] The present invention relates to a binder resin for liquid ink, a liquid ink containing the binder resin, and a printed matter. This application claims priority based on Japanese Patent Application No. 2022-126666, filed on August 8, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] The present invention relates to a binder resin for liquid printing ink that can be used as gravure ink or flexographic ink for flexible packaging. Gravure ink and flexographic ink are widely used for the purpose of imparting beauty and functionality to printed materials. For this reason, when performing gravure or flexographic printing, highlight transferability and plate fogging properties are required to enhance beauty, and adhesion, deinking property, and chemical resistance are required to impart functionality. Inks such as those described in Patent Document 1 and Patent Document 2 have been developed so far, but they have not yet met all of the required performance. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-014487 A [Patent Document 2] Patent No. 6066677 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention provides a binder resin for liquid ink, which is used in liquid ink having improved adhesion, deinking properties, and chemical resistance for the purpose of imparting highlight transfer properties and plate fogging properties for enhancing cosmetic appearance, and functionality, and a liquid ink and printed matter containing the binder resin. [Means for solving the problem]

[0005] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that adding a binder resin having a specific Trouton ratio within a specific solid content range to a liquid ink is effective in solving the problems.

[0006] The present disclosure includes the following embodiments. [1] A binder resin for liquid ink, Contains at least one resin selected from the group consisting of polyurethane resins and acrylic resins; The binder resin for liquid ink is characterized in that the Trouton ratio of the binder resin for liquid ink, when measured at a solid content of 30% and at 30° C., is 3.0 to 10.0. [2] The binder resin for liquid ink according to [1], wherein the binder resin for liquid ink has an extensional viscosity of 3.0 Pa s or more and 8.0 Pa s or less when measured at 30°C with a solid content of 30%. [3] The liquid ink binder resin according to [1] or [2], wherein the liquid ink binder resin has a shear viscosity of 0.45 Pa s or more and 0.95 Pa s or less when measured at 30°C with a solid content of 30%. [4] The binder resin for liquid ink according to any one of [1] to [3], wherein the polyurethane resin is contained in an amount of 8 to 60 mass % based on the total solid content of the liquid ink. [5] The binder resin for liquid ink according to any one of [1] to [4], wherein the acrylic resin is contained in an amount of 8 to 60 mass % based on the total solid content of the liquid ink. [6] A liquid ink comprising the liquid ink binder resin according to any one of [1] to [5]. [7] A printed matter having a printed layer formed by printing the liquid ink described in [6] on a substrate. Effect of the Invention

[0007] According to the present invention, it is possible to provide a binder resin for liquid ink, which is used in liquid ink having improved adhesion, deinking properties, and chemical resistance for the purpose of imparting highlight transfer properties and plate fogging properties for enhancing cosmetic appearance, and functionality, a liquid ink containing the binder resin, and a printed matter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (Liquid ink binder resin) A liquid ink binder resin according to one embodiment of the present invention (sometimes referred to as the liquid ink binder resin of the present embodiment or the binder resin of the present embodiment) contains at least one resin selected from the group consisting of polyurethane resins and acrylic resins. The liquid ink binder resin according to the present embodiment has a Trouton ratio of 3.0 or more and 10.0 or less when measured at a solids content of 30% and at 30°C.

[0009] The liquid ink binder resin has a ratio of extensional viscosity to shear viscosity, which will be described later. The evaluation method will be described in detail in the Examples. The Trouton ratio of the liquid ink binder resin, measured at a solid content of 30% and at 30° C., is preferably 4.0 to 9.0, and more preferably 5.0 to 8.0. When the liquid ink binder resin has a Trouton ratio of 3.0 to 10.0, measured at a solid content of 30% and at 30° C., the liquid ink using the liquid ink binder resin is preferable in terms of plate fogging properties and highlight transfer properties.

[0010] The liquid ink binder resin preferably has an extensional viscosity of 3.0 Pa·s or more and 8.0 Pa·s or less, more preferably 4.0 or more and 7.0 or less, when measured at 30° C. and with a solid content of 30%.

[0011] The liquid ink binder resin preferably has a shear viscosity of 0.45 Pa·s or more and 0.95 Pa·s or less, more preferably 0.5 or more and 0.9 or less, when measured at 30° C. and with a solid content of 30%.

[0012] <Polyurethane resin> The content of the polyurethane resin in the binder resin for liquid ink of this embodiment can be, for example, 8 to 60% by mass based on the total solid content of the liquid ink. For example, in the case of gravure ink used in gravure printing, the content is preferably 5% by mass or more in terms of solid content based on the total mass of the ink from the viewpoint of sufficient adhesion of the gravure ink to the printed material, and 25% by mass or less from the viewpoint of appropriate ink viscosity and work efficiency during ink production and printing. In addition, in the case of flexographic ink used in flexographic printing, the content is preferably 5% by mass or more and 30% by mass or less in terms of solid content based on the total mass of the flexographic ink.

[0013] The number average molecular weight of the polyurethane resin used in the liquid ink binder resin of this embodiment is preferably within the range of 10,000 to 100,000. If the number average molecular weight of the polyurethane resin is less than 10,000, the blocking resistance, lamination strength, chemical resistance, etc. of the resulting ink tend to be low. If the number average molecular weight of the polyurethane resin is more than 100,000, the viscosity of the resulting ink tends to be high, making it difficult to obtain a desired print density.

[0014] The polyurethane resin used in the liquid ink binder resin of this embodiment preferably uses polyester polyol and / or polyether polyol as its reaction raw material.

[0015] The number average molecular weight of the polyester polyol is preferably 1000 to 7000. If the number average molecular weight of the polyester polyol is less than 1000, the polyurethane resin film tends to be hard and the adhesion to the polyester film tends to decrease. If the number average molecular weight is more than 7000, the polyurethane resin film tends to be brittle and the blocking resistance of the film tends to decrease. On the other hand, the polyether polyol is preferably 1 to 50 parts by mass per 100 parts by mass of the polyurethane resin. If the polyether polyol is less than 1 part by mass, the solubility of the polyurethane resin in ketone, ester, and alcohol-based solvents decreases, and the adhesion, especially on high-performance barrier films, tends to decrease. In addition, the resolubility of the film in the solvent decreases, and the tone reproducibility of the printed matter tends to decrease. If the polyether polyol exceeds 50 parts by mass, the film becomes excessively soft and tends to have poor blocking resistance.

[0016] The number average molecular weight of the polyester polyol is a value measured by gel permeation chromatography (GPC) under the following conditions. Measurement device: high-speed GPC device ("HLC-8220GPC" manufactured by Tosoh Corporation) Column: The following columns manufactured by Tosoh Corporation were used, connected in series. "TSKgelG5000" (7.8mmI.D. x 30cm) x 1 "TSKgelG4000" (7.8mmI.D. x 30cm) x 1 "TSKgelG3000" (7.8mmI.D. x 30cm) x 1 "TSKgelG2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: Tetrahydrofuran (THF) Flow rate: 1.0 mL / min Injection volume: 100 μL (a tetrahydrofuran solution with a sample concentration of 0.4% by mass) Standard sample: A calibration curve was prepared using the following standard polystyrene.

[0017] (Standard polystyrene) "TSKgel Standard Polystyrene A-500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-1000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-2500" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene A-5000" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-1" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-4" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-10" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-20" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-40" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-80" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-128" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-288" manufactured by Tosoh Corporation "TSKgel Standard Polystyrene F-550" manufactured by Tosoh Corporation

[0018] As the polyester polyol, for example, one obtained by a known esterification reaction between a compound having two or more hydroxyl groups and a polybasic acid can be used.

[0019] The compound having two or more hydroxyl groups is used as a chain extender, and examples of such compounds include glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol; 2-methyl-1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, Compounds having a number average molecular weight in the range of 50 to 400, such as glycols having a branched structure, such as 2-isopropyl-1,4-butanediol, 2,4-dimethyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2-ethyl-1,6-hexanediol, 3,5-heptanediol, and 2-methyl-1,8-octanediol; aliphatic polyols, such as trimethylolpropane, trimethylolethane, pentaerythritol, saccharose, methylene glycol, glycerin, and sorbitol; and aromatic polyols, such as bisphenol A, 4,4'-dihydroxydiphenyl, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl sulfone, hydrogenated bisphenol A, and hydroquinone, can be used. These chain extenders may be used alone or in combination of two or more.

[0020] Examples of the polybasic acid that can be used include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, phthalic acid, and anhydrides of these acids. These polybasic acids may be used alone or in combination of two or more kinds.

[0021] The polyether polyol preferably has a number average molecular weight of 100 to 4000. As described in detail below, examples of the polyether polyol include polyether polyols of polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc. Specifically, known and general-purpose polyether polyols such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used, and among these, polyethylene glycol is preferred. By containing the polyester polyol and / or polyether polyol within the above range, the adhesion, particularly on the substrate film, is significantly improved, resulting in excellent blocking resistance and laminate strength.

[0022] Similarly, if the number average molecular weight of the polyether polyol is less than 100, the polyurethane resin film tends to become hard and the adhesion to the polyester film tends to decrease. If the number average molecular weight is more than 4000, the polyurethane resin film tends to become brittle and the blocking resistance of the film tends to decrease. The number average molecular weight of the polyether polyol was measured by gel permeation chromatography (GPC) under the same conditions as the polyester polyol.

[0023] The diisocyanate compound used in the polyurethane resin in the liquid ink binder resin of this embodiment may be any of various known compounds that are generally used in the production of polyurethane resins, such as aromatic diisocyanates, aliphatic diisocyanates, and alicyclic diisocyanates. Specific examples of these include 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4'-dibenzyl isocyanate, dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, cyclohexane-1,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimethyle diisocyanate, dimethyl ... Examples of the diisocyanate include aryl diisocyanate, isophorone diisocyanate (3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate; 5-isocyanato-1-(isocyanomethyl)-1,3,3-trimethylcyclohexane;), dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, methylcyclohexane diisocyanate, norbornane diisocyanate, m-tetramethylxylylene diisocyanate, 4,4-diphenylmethane diisocyanate, tolylene diisocyanate, bis-chloromethyl-diphenylmethane-diisocyanate, 2,6-diisocyanate-benzyl chloride, and dimer diisocyanate in which the carboxyl group of dimer acid is converted to an isocyanate group. These diisocyanate compounds can be used alone or in combination of two or more.

[0024] Examples of chain extenders used in the polyurethane resin in the liquid ink binder resin of this embodiment include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4'-diamine, etc., as well as amines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropyldiamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine. These chain extenders can be used alone or in combination of two or more.

[0025] Furthermore, the amine value of the polyurethane resin used in the liquid ink binder resin of this embodiment is preferably 10.0 mgKOH / g or less. If the amine value exceeds 10.0 mgKOH / g, blocking resistance tends to deteriorate, and the stability of the second liquid after the addition of the curing agent decreases. From the viewpoint of maintaining good blocking resistance and second liquid stability while maintaining plate fogging resistance, adhesion, and extrusion lamination strength, the range of 1.0 to 5.0 mgKOH / g is more preferable, and the range of 1.0 to 3.5 mgKOH / g is even more preferable.

[0026] <Acrylic resin> The acrylic resin can be obtained by copolymerizing various (meth)acrylate monomers and, if necessary, other polymerizable unsaturated group-containing compounds.

[0027] The monomer constituting the acrylic resin is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-pentafluoropropyl (meth)acrylate, perfluorocyclohexyl (meth)acrylate, and glyceryl (meth)acrylate. (Meth)acrylic monomers such as ricinyl (meth)acrylate, allyl glycidyl ether, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, 2-dimethylaminoethyl (meth)acrylate, (meth)acrylamide, N-monoalkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, N-methylol (meth)acrylamide, N-isopropoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, N-isobutoxymethyl (meth)acrylamide, 2-aziridinylethyl (meth)acrylate, dicyclopentenyl (meth)acrylate, acrolein, diacetone (meth)acrylamide, and acetoacetoxyethyl (meth)acrylate can be used. The term "(meth)acrylate" refers to either or both of acrylate and methacrylate, and "(meth)acrylic" refers to either or both of acrylic and methacrylic.

[0028] As the polymerizable unsaturated group-containing compound, in addition to the (meth)acrylic monomers, vinyl acetate, vinyl propionate, vinyl versatate, methyl vinyl ether, ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, (meth)acrylonitrile, styrene, α-methylstyrene, divinylstyrene, isoprene, chloroprene, butadiene, ethylene, tetrafluoroethylene, vinylidene fluoride, N-vinylpyrrolidone, etc. may be used. Each of these may be used alone, or two or more of them may be used in combination.

[0029] The acrylic resins (A1) and (A2) having an acid value can be obtained by copolymerizing a (meth)acrylic monomer having a carboxyl group for the purpose of introducing one or more hydrophilic groups selected from the group consisting of a carboxyl group and a carboxylate group. The carboxylate group is a group in which a carboxyl group is neutralized with a basic compound. Examples of the (meth)acrylic monomer having a carboxyl group include (meth)acrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, β-(meth)acryloyloxyethyl hydrogen succinate, and β-(meth)acryloyloxyethyl hydrogen phthalate. The acrylic resins (A1) and (A2) can be produced, for example, by polymerizing various monomers in the presence of a polymerization initiator at a temperature range of 60°C to 150°C. Examples of the polymerization method include bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Examples of the polymerization mode include random copolymerization, block copolymerization, and graft copolymerization.

[0030] [Solvent (1)] Examples of the solvent (1) used in the liquid ink binder resin of this embodiment include water, water-based solvents containing water, and organic solvents. Examples of the water-based solvent include an aqueous alcohol solution such as an ethyl alcohol solution or an isopropyl alcohol solution, and an aqueous ammonia solution. The solvent used in the liquid ink binder resin of this embodiment is preferably an organic solvent. The solvent (1) used in the liquid ink binder resin of this embodiment may be the same as or different from the solvent (2) used in the liquid ink described below.

[0031] <Organic solvent> The organic solvent is not particularly limited, and examples thereof include various organic solvents such as aromatic hydrocarbons, such as toluene, xylene, Solvesso #100, and Solvesso #150; aliphatic hydrocarbons, such as hexane, methylcyclohexane, heptane, octane, and decane; and esters, such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, butyl acetate, amyl acetate, ethyl formate, and butyl propionate. Examples of water-miscible organic solvents include various organic solvents such as alcohols such as methanol, ethyl alcohol, propanol, butanol, and isopropyl alcohol, ketones such as acetone, methyl ethyl ketone, and cyclohexanone, and glycol ethers such as ethylene glycol (mono, di) methyl ether, ethylene glycol (mono, di) ethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, monobutyl ether, diethylene glycol (mono, di) methyl ether, diethylene glycol (mono, di) ethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol monobutyl ether, triethylene glycol (mono, di) methyl ether, propylene glycol (mono, di) methyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and dipropylene glycol (mono, di) methyl ether. These can be used alone or in combination of two or more.

[0032] The solid content of the liquid ink binder resin of this embodiment is preferably 5% by mass or more and 50% by mass or less, and more preferably 10% by mass or more and 40% by mass or less. The liquid ink binder resin used for measuring the Trouton ratio of the liquid ink binder resin of this embodiment when measured at 30° C. with a solid content of 30% has a solid content of 30%.

[0033] (Liquid ink) A liquid ink according to one embodiment of the present invention (sometimes referred to as the liquid ink according to this embodiment) contains the binder resin for liquid ink according to this embodiment described above. <Other ingredients> The liquid ink of the present embodiment may further contain a colorant or an auxiliary agent.

[0034] Colorants used in the liquid ink of this embodiment include inorganic pigments, organic pigments, and dyes that are used in general inks, paints, and recording agents, etc. Examples of organic pigments include soluble azo-based, insoluble azo-based, azo-based, phthalocyanine-based, halogenated phthalocyanine-based, anthraquinone-based, anthanthrone-based, dianthraquinonyl-based, anthrapyrimidine-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine azo-based, flavanthrone-based, diketopyrrolopyrrole-based, isoindoline-based, indanthrone-based, and carbon black-based pigments. Other examples include carmine 6B, lake red C, permanent red 2B, disazo yellow, pyrazolone orange, carmine FB, chromophthalic yellow, chromophthalic red, phthalocyanine blue, phthalocyanine green, dioxazine violet, quinacridone magenta, quinacridone red, indanthrone blue, pyrimidine yellow, thioindigo bordeaux, thioindigo magenta, perylene red, perinone orange, isoindolinone yellow, aniline black, diketopyrrolopyrrole red, daylight fluorescent pigments, etc. In addition, both non-acid-treated pigments and acid-treated pigments can be used.

[0035] From the viewpoint of ensuring the concentration and coloring power of the liquid ink of this embodiment, the total content of the pigments is preferably 1% by mass or more and preferably 60% by mass or less of the total amount of the liquid ink of this embodiment.

[0036] As the auxiliary, waxes such as paraffin wax, polyethylene wax, carnauba wax, etc. for imparting friction resistance, slipperiness, etc., fatty acid amide compounds such as oleic acid amide, stearic acid amide, erucic acid amide, etc., silicone-based and non-silicone-based defoamers for suppressing foaming during printing, dispersants, etc. may be appropriately used. As the dispersant, nonionic dispersants are preferred.

[0037] The acid value of the dispersant is preferably 30 mgKOH / g or less, more preferably 25 mgKOH / g or less, and even more preferably 20 mgKOH / g or less, and may be, for example, 1 mgKOH / g or more, or even 3 mgKOH / g or more.

[0038] The acid value of the dispersant is preferably smaller than that of the acid additive. The difference between the acid value of the acid additive and the acid value of the dispersant is, for example, preferably 1 mgKOH / g or more, more preferably 3 mgKOH / g or more, and preferably 30 mgKOH / g or less, more preferably 20 mgKOH / g or less.

[0039] The content of the dispersant is preferably 1 part by mass or more, more preferably 2 parts by mass or more, more preferably 5 parts by mass or more, more preferably 10 parts by mass or more, more preferably 15 parts by mass or more, and more preferably 20 parts by mass or more, relative to 100 parts by mass of the colorant. The content of the dispersant is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, more preferably 75 parts by mass or less, more preferably 70 parts by mass or less, more preferably 65 parts by mass or less, and more preferably 60 parts by mass or less, relative to 100 parts by mass of the colorant.

[0040] In addition to the above, water, wetting agents, adhesive aids, leveling agents, antistatic agents, viscosity modifiers, metal chelates, trapping agents, antiblocking agents, isocyanate-based curing agents, and silane coupling agents can also be used as necessary. The viscosity of the liquid ink is preferably 6 seconds or more, more preferably 10 seconds or more, and even more preferably 13 seconds or more, as measured at 25°C using a Zahn Cup #3 manufactured by Rigo Co., Ltd. Also, it is preferably 25 seconds or less, more preferably 20 seconds or less, and even more preferably 18 seconds or less.

[0041] [Solvent (2)] Examples of the solvent (2) used in the liquid ink of this embodiment include water, aqueous solvents containing water, and organic solvents. Examples of the aqueous solvent include an aqueous alcohol solution such as an ethyl alcohol solution or an isopropyl alcohol solution, and an aqueous ammonia solution. The solvent (2) used in the liquid ink of this embodiment is preferably an organic solvent. The solvent (2) used in the liquid ink of this embodiment may be the same as or different from the solvent (1) used in the binder resin for the liquid ink of this embodiment described above. The solvent (2) used in the liquid ink of this embodiment may include the solvent (1) contained in the binder resin for the liquid ink used and the added solvent (3). The solvent (3) may be the same as or different from the solvent (1) used in the binder resin for the liquid ink of this embodiment described above.

[0042] <Organic solvent> The organic solvent is not particularly limited, but is the same as that explained in the solvent (1) used in the binder resin for liquid ink of this embodiment. Examples of the solvent (2) used in the liquid ink of this embodiment include ester-based organic solvents. From the viewpoint of preventing the liquid ink of this embodiment from drying out due to its high volatility, the ester-based organic solvent preferably contains an ester-based organic solvent having 5 or more carbon atoms. The ester-based organic solvent having 5 or more carbon atoms is not limited, but isopropyl acetate, normal propyl acetate, and butyl acetate are more preferable, and normal propyl acetate is particularly preferable.

[0043] The content of the ester-based organic solvent in the liquid ink of this embodiment is preferably 1% or more, preferably 3% or more, preferably 5% or more, preferably 7% or more, preferably 10% or more, preferably 12% or more, preferably 15% or more, preferably 18% or more, preferably 20% or more, and preferably 35% or less, preferably 32% or less, preferably 30% or less, preferably 28% or less, preferably 25% or less, preferably 23% or less.

[0044] The content of the ester-based organic solvent in the liquid ink of this embodiment is preferably 1 to 35%, preferably 3 to 35%, preferably 5 to 32%, preferably 7 to 32%, preferably 10 to 30%, preferably 12 to 30%, preferably 15 to 28%, preferably 18 to 28%, preferably 20 to 25%, and preferably 20 to 23%.

[0045] When the liquid ink of the present embodiment is used as a gravure ink, it may contain an alcohol that does not contain an aromatic hydrocarbon organic solvent and has a specific evaporation rate of 100 or less when the evaporation rate of butyl acetate is taken as 100. By containing an alcohol with a specific evaporation rate of 100 or less, it is possible to maintain highlight transferability with a dot area of ​​10% or less and to maintain highlight improvement. The following two mechanisms are cited. (1) After the liquid ink of this embodiment is transferred to the substrate, half of the liquid ink of this embodiment remains in the cells of the gravure plate. (2) The remaining liquid ink of this embodiment evaporates its solvents until it comes into contact with the liquid ink of this embodiment in the ink pan again, and becomes semi-dry. Furthermore, since the solvent with the fastest evaporation rate evaporates first, the solvent with the slowest evaporation rate remains in the ink pan. (3) At this time, if any solvent with high resin solubility remains, the semi-dried composition will re-dissolve when it comes into contact with the liquid ink of this embodiment again, preventing the liquid ink of this embodiment from solidifying in the cells. The evaporation rate of general-purpose alcohols is so fast that the specific evaporation rate exceeds 100 when the evaporation rate of butyl acetate is taken as 100, making it difficult for the above mechanism to function. Secondly, alcohols with a specific evaporation rate of 100 or less when the evaporation rate of butyl acetate is taken as 100 have a low ratio of hydroxyl groups (alcohol groups) per alcohol molecule, which tends to increase the solubility of polyurethane resins. From the viewpoints of both work hygiene during printing and the harmfulness of packaging materials, it is more preferable to use ethyl acetate, propyl acetate, isopropyl alcohol, normal propanol, etc., and not to use aromatic solvents such as toluene or ketone-based solvents such as methyl ethyl ketone. Among them, from the viewpoint of solubility in polyurethane resin and soluble nitrocellulose, a mixture of isopropyl alcohol / ethyl acetate / normal propyl acetate / methylcyclohexane is more preferable. In addition, glycol ethers can be added in an amount of less than 10% by mass of the total composition to adjust the dryness.

[0046] The liquid ink of the present embodiment can be used, for example, in gravure printing or flexographic printing.

[0047] When the liquid ink of the present embodiment is used for gravure printing or flexographic printing, it can be produced using an Eiger mill, sand mill, gamma mill, attritor, or the like that is generally used in the production of gravure or flexographic inks.

[0048] [Preparation method] When preparing the liquid ink of this embodiment, from the viewpoint of uniformity, a preliminary composition (kneaded base ink) may be prepared by previously mixing at least a portion of the binder resin, the colorant, at least a portion of the acidic additive, and at least a portion of the organic solvent.

[0049] (Printing on substrate) The liquid ink of the present embodiment has excellent adhesion to various substrates and can be used for printing on paper, synthetic paper, cloth, thermoplastic resin film, plastic products, steel plates, etc. The liquid ink of the present embodiment is useful as an ink for gravure printing using a gravure printing plate by electronic engraving intaglio, etc., or for flexographic printing using a flexographic printing plate by a resin plate, etc. On the other hand, the liquid ink of the present embodiment can also be used for an inkjet method in which ink is discharged from an inkjet nozzle without using a plate, but this is not very preferable. That is, in the case of inkjet ink, ink droplets discharged from a nozzle directly adhere to a substrate to form a printed matter. In contrast to inkjet ink, the liquid ink of the present embodiment is once adhered to and transferred to a printing plate or a printing pattern, and then only the ink is again adhered to a substrate, and dried as necessary to form a printed matter.

[0050] The thickness of a liquid ink film formed by gravure printing or flexographic printing using the liquid ink of this embodiment is, for example, preferably 10 μm or less, and more preferably 5 μm or less.

[0051] In addition, since the liquid ink of the present embodiment contains an acidic additive, it is preferable to thoroughly clean the equipment used immediately after use. As the cleaning agent, a cleaning agent generally used for cleaning liquid inks can be used.

[0052] (Printed material) By printing the liquid ink of this embodiment on or above the surface of the substrate A, a printed matter having a coating (printed layer) can be obtained. EXAMPLES

[0053] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The present invention will be described in more detail below with reference to examples.

[0054] "Synthesis of binder resin for liquid ink" Example 1 "Synthesis of acrylic resin 1" A reactor equipped with a thermometer, a reflux condenser, and a nitrogen inlet tube was charged with 70 parts by mass of styrene, and the temperature was raised to 90°C in a nitrogen atmosphere. A mixture consisting of 30 parts by mass of cyclohexyl methacrylate, 20 parts by mass of methyl methacrylate, 20.0 parts by mass of 2-hydroxyethyl methacrylate, and 1.0 parts by mass of 2,2'-azobis(2-methylbutyronitrile) (hereinafter abbreviated as "ABN-E") was added dropwise over 4 hours. After the completion of the dropwise addition, the mixture was kept at 90°C for 2 hours, and then 30 parts by mass of ethyl acetate and 30 parts by mass of isopropyl alcohol were added dropwise over 1 hour. Next, the mixture was kept at 90°C for 12 hours, and then ethyl acetate and isopropyl alcohol were added to obtain an acrylic resin solution. The resin solid content concentration of the obtained acrylic resin solution was 30.0% by mass, and the Mw of the resin solid content was 27,000. The obtained acrylic resin solution was designated as acrylic resin 1 (solid content 30.0% by mass) of this example, and the extensional viscosity, shear viscosity, and Trouton ratio were evaluated by the following methods. The results are shown in Table 1.

[0055] Example 2 "Synthesis of urethane resin 1" In a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 100.0 parts of polyester polyol (hydroxyl value: 80.0 mgKOH / g) consisting of 3-methyl-1,5-pentanediol, 1,12-dodecanedioic acid and adipic acid and 24.0 parts of isophorone diisocyanate were charged and reacted for 10 hours at 90°C under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.50% by mass, and then 61.1 parts of ethyl acetate were added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 7.0 parts of isophorone diamine, 0.30 parts of di-n-butylamine, 108.0 parts of ethyl acetate and 112.8 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a urethane resin solution. The obtained urethane resin solution had a resin solids concentration of 30.0% by mass and the Mw of the resin solids was 30,000. The obtained urethane resin solution was designated as Urethane Resin 1 (solid content 30.0% by mass) of this example, and the extensional viscosity, shear viscosity, and Trouton ratio were evaluated by the following methods. The results are shown in Table 1.

[0056] Example 3 "Synthesis of urethane resin 2" A four-neck flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas inlet tube was charged with 100.0 parts of a polyester polyol consisting of polyethylene glycol (hydroxyl value: 56.1 mg KOH / g), sebacic acid, and adipic acid (hydroxyl value: 50.0 mg KOH / g), 4.0 parts of isophorone diisocyanate, 5.0 parts of hexamethylene diisocyanate, and 3.0 parts of tolylene diisocyanate, and reacted under a nitrogen stream at 90°C for 10 hours to produce a urethane prepolymer with an isocyanate group content of 1.50 mass%, and then 61.1 parts of ethyl acetate was added to this to obtain a homogeneous solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 2.9 parts of 1,3-bisaminomethylcyclohexane, 0.10 parts of di-n-butylamine, 0.30 parts of 2-amino-2-methyl-1-propanol, 108.0 parts of ethyl acetate, and 112.8 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a urethane resin solution. The obtained urethane resin solution had a resin solid concentration of 30.0% by mass, and the Mw of the resin solid was 54,000. The obtained urethane resin solution was used as urethane resin 2 (solid content 30.0% by mass) of this example, and the extensional viscosity, shear viscosity, and Trouton ratio were evaluated by the following method. The results are shown in Table 1.

[0057] Example 4 "Synthesis of urethane resin 3" In a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 100.0 parts of polyester polyol consisting of 1,9-nonanediol and adipic acid (hydroxyl value: 70.0 mgKOH / g) and 18.5 parts of isophorone diisocyanate were charged, and reacted for 10 hours at 90°C under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 1.50% by mass, and then 61.1 parts of ethyl acetate were added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 2.1 parts of isophorone diamine, 1.0 parts of 2-(2-aminoethylamino)ethanol, 0.30 parts of di-n-butylamine, 108.0 parts of ethyl acetate and 112.8 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a urethane resin solution. The obtained urethane resin solution had a resin solid content concentration of 30.0% by mass and the Mw of the resin solid content was 73,000. The obtained urethane resin solution was used as the urethane resin 3 of this example (solid content 30.0% by mass), and the extensional viscosity, shear viscosity, and Trouton ratio were evaluated by the following methods. The results are shown in Table 1.

[0058] Example 5 "Synthesis of urethane resin 4" In a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 100.0 parts of polyester polyol consisting of 2,4-diethyl 1,5-pentanediol and sebacic acid (hydroxyl value: 50.0 mgKOH / g), 13.4 parts of isophorone diisocyanate and 10.0 parts of tolylene diisocyanate were charged and reacted for 10 hours at 90°C under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 5.00% by mass, and then 61.1 parts of ethyl acetate were added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 10.4 parts of isophorone diamine, 1.0 parts of ethylene diamine, 0.30 parts of 2-amino-2-methyl-1-propanol, 108.0 parts of ethyl acetate and 112.8 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a urethane resin solution. The obtained urethane resin solution had a resin solid concentration of 30.0% by mass, and the Mw of the resin solid was 37,000. The obtained urethane resin solution was used as urethane resin 4 (solid content 30.0% by mass) in this example, and the extensional viscosity, shear viscosity, and Trouton ratio were evaluated by the following methods. The results are shown in Table 1.

[0059] Example 6 "Synthesis of urethane resin 5" In a four-neck flask equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen gas inlet tube, 100.0 parts of polyester polyol consisting of neopentyl glycol, propylene glycol, adipic acid and sebacic acid (hydroxyl value: 50.0 mgKOH / g), 11.3 parts of isophorone diisocyanate and 5.0 parts of hexamethylene diisocyanate were charged and reacted for 10 hours at 90 ° C under a nitrogen stream to produce a urethane prepolymer with an isocyanate group content of 2.60 mass%, and then 61.1 parts of ethyl acetate were added to the mixture to obtain a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 6.7 parts of isophorone diamine, 0.50 parts of di-n-butylamine, 108.0 parts of ethyl acetate and 112.8 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C for 5 hours to obtain a urethane resin solution. The obtained urethane resin solution had a resin solid concentration of 30.0% by mass, and the Mw of the resin solid was 29,500. The obtained urethane resin solution was used as Urethane Resin 5 (solid content 30.0% by mass) of this example, and the extensional viscosity, shear viscosity, and Trouton ratio were evaluated by the following methods. The results are shown in Table 1.

[0060] Comparative Example 1 Acrylic resin 2: X-321L (Seiko PMC, water-based acrylic resin, solid content 32.8%) was diluted with water to a solid content of 30.0 mass%, and the extensional viscosity, shear viscosity, and Trouton ratio were evaluated by the following methods. The results are shown in Table 1.

[0061] "Ink formulation" Example 7 A blue liquid printing ink was prepared by kneading a mixture (total 100 parts) of 40 parts by mass of N-propyl acetate (normal propyl acetate), 10 parts by mass of ethyl acetate, 11 parts by mass of indigo pigment, 3 parts by mass of vinyl chloride-vinyl acetate resin (vinyl chloride-vinyl acetate copolymer resin), 6 parts by mass of isopropyl alcohol, 1 part by mass of dispersant, and 129 parts by mass of the acrylic resin prepared in Example 1. A 42% IPA / EtAc mixed solvent (isopropyl alcohol / ethyl acetate=50 / 50 (parts by mass / parts by mass)) was added to 100 parts by mass of the obtained mixture so that the temperature was about 15 seconds (25°C) in a Zahn cup #3 (manufactured by Rigo Co., Ltd.), and the liquid ink was prepared.

[0062] (Examples 8 to 24, Comparative Example 2)

[0063] The above binder resins and solvent liquids were used in the mixing ratios shown in Table 2 below to prepare liquid inks of Examples 7 to 24 and Comparative Example 2.

[0064] The prepared liquid inks of Examples 7 to 24 and Comparative Example 2 were printed on any one of the substrates A using a gravure proofing machine equipped with a gravure plate with a plate depth of 35 μm and dried at 45° C. to obtain a print of Configuration 1 below. The obtained printed matter of the Examples and Comparative Examples was evaluated for the following items using the methods described below. The results are shown in Table 2. In each of the following evaluations, no difference in the evaluation results due to differences in the type of base material A was observed.

[0065] <Printed material composition> Composition: Substrate A - Coating layer 1

[0066] <Base material A> Corona-treated biaxially stretched polypropylene film (Pylen P216 manufactured by Toyobo Co., Ltd.) 1) Thickness 20μm (OPP) Corona-treated polyethylene terephthalate film (Toyobo Co., Ltd. Ester E5102, thickness 12 μm) (PET)

[0067] [Evaluation method] <Evaluation of binder resins for liquid inks> <Extensional viscosity, shear viscosity, Trouton ratio> The liquid ink binder resins of Examples 1 to 6 and Comparative Example 1 were each measured using the following method until the elongation rate reached 4000 s -1 Extensional viscosity at a shear rate of 4000s -1 The shear viscosity at the extensional viscosity and the shear viscosity at the shear viscosity were measured. The ratio of these values ​​(extensional viscosity / shear viscosity) was then calculated as the Trouton ratio. The extensional viscosity was measured in accordance with the capillary rheometer evaluation method described in JIS-7199 (ISO11443, ASTM D3835).

[0068] Specifically, a twin capillary type apparatus (RHEOGRAPH20 manufactured by Gottfert) was used in combination with a capillary die having a length of 10 mm and a diameter of 0.5 mm and a capillary die having a length of 0.25 mm and a diameter of 0.5 mm.

[0069] Then, the temperature is 30°C and the shear rate is 100 to 300,000 s -1 The true shear viscosity was obtained by removing the pressure loss using the Burghley correction from the apparent shear viscosity (pressure) measured at . The extensional viscosity corresponding to the extensional rate was calculated using the Cogswell equation from the obtained true shear viscosity and pressure loss. Extension speed 4000s -1 Extensional viscosity at shear rate of 4000 s -1 The shear viscosity and Trouton ratio values ​​for are shown in Table 1.

[0070] <How to evaluate printed materials> <Adhesiveness> After each of the printed matter of the Examples and Comparative Examples was left to stand for one day, cellophane tape was applied to the printed surface, which was then quickly peeled off, and the appearance of the printed film was visually evaluated.

[0071] "Evaluation Criteria" ◯: The printing film did not peel off at all. △: 60% or more but less than 80% of the printed film remained on the film. ×: Less than 40% of the printed film remained on the film.

[0072] <Alcohol resistance> The printed surface of each of the printed matter in the Examples and Comparative Examples was rubbed 100 times under a load of 200 g with a cloth soaked in ethyl alcohol using a Gakushin type abrasion resistance tester, and the alcohol suitability was evaluated from the change in the printed surface.

[0073] "Evaluation Criteria" ○: No change in the printed surface or the padding. △: Streaky scratches are observed on the printed surface. ×: Surface scratches are observed on the printed surface.

[0074] <Highlight transferability> The viscosity of the liquid ink obtained in the Examples and Comparative Examples was adjusted to 16 seconds (25°C) with ethyl acetate using a Zahn cup #3 (Rigo Co., Ltd.). Then, using an MD type gravure printing machine (Fuji Machine Co., Ltd.) equipped with a laser gravure plate having a plate depth of 25 μm, printing was performed on the treated surface of a biaxially oriented polypropylene film (Futamura Chemical Co., Ltd., FOR, thickness 20 μm) that had been corona discharge-treated on one side. The blurring test involved visually evaluating the blurring in the highlight printed areas (dot area less than 10%) and the degree of dirt in the non-printed areas when printing at a speed of 200 m / min with a gravure plate circumference of 600 mmφ.

[0075] "Evaluation Criteria" ◯: No smearing at all, no stains on non-printed areas. Δ: A little fading is observed, and a little staining is observed in the non-printed parts. ×: A lot of smudges are observed, and a lot of stains are observed even in the non-printed parts.

[0076] <Plate fogging> Among the prints printed under the conditions of the highlight transfer test, the degree of staining (plate fogging) of the non-printed parts was evaluated.

[0077] "Evaluation Criteria" A: No print stains are visible. △: Slight print staining is visible, but within the practical range. ×: Severe print staining is observed.

[0078] <Deinking property> [Alkaline solution] Sodium hydroxide solution "SH solution": Sodium hydroxide (reagent grade 1) manufactured by Wako Pure Chemical Industries, Ltd. was dissolved in ion-exchanged water to prepare a 1.5% by mass aqueous solution. [Peel test conditions] The peeling test was performed under the following conditions with a treatment time of 30 minutes for evaluation. If peeling occurs within 5 minutes of treatment, it indicates fairly high performance (deinking ability). The examples and comparative examples were cut into test pieces of 10 mm x 10 mm in size, and the test pieces were subjected to a peel test under the following conditions. Conditions: Sodium hydroxide solution stirred at 80℃ The peelability of the coating under the above conditions was evaluated.

[0079] "Evaluation Criteria" ◯: 90% or more of the ink film detached from the substrate in less than 5 minutes. △: 90% or more of the ink coating film detached from the substrate within 15 minutes or more and less than 30 minutes. ×: Less than 50% of the ink film was detached from the substrate after 30 minutes of testing.

[0080] [Table 1]

[0081] [Table 2]

[0082] (Consideration) As can be seen from the results in Tables 1 and 2, printed matter using liquid ink containing the liquid ink binder resin of the present invention not only exhibits excellent cosmetic properties, but also has the functionality of being easily deinked and chemically resistant.

Claims

1. A binder resin for liquid ink, comprising: At least one resin selected from the group consisting of polyurethane resin and acrylic resin, The liquid ink binder resin has a Trouton ratio of 4.0 to 9.0 when measured at 30° C. and a solid content of 30%; The liquid ink binder resin has an extensional viscosity of 3.0 Pa·s or more and 8.0 Pa·s or less when measured at 30° C. and a solid content of 30%; The liquid ink binder resin has a shear viscosity of 0.45 Pa·s or more and 0.95 Pa·s or less when measured at 30° C. and a solid content of 30%; The extensional viscosity is an extensional viscosity at an extensional speed of 4000 s −1 , The shear viscosity is a shear viscosity at a shear rate of 4000 s −1 A binder resin for liquid ink, wherein the Trouton ratio is a ratio of the extensional viscosity to the shear viscosity (extensional viscosity / shear viscosity).

2. 2. The liquid ink binder resin according to claim 1, wherein the polyurethane resin is contained in an amount of 8 to 60% by mass based on the total solid content of the liquid ink.

3. 3. The liquid ink binder resin according to claim 1, wherein the acrylic resin is contained in an amount of 8 to 60% by mass based on the total solid content of the liquid ink.

4. A liquid ink comprising the binder resin for liquid ink according to claim 1 or 2.

5. A printed matter having a printed layer formed by printing the liquid ink according to claim 4 on a substrate.

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