Liquid ink composition, and printed matter and laminate made by using the same

Abstract

To provide a liquid ink composition that exhibits superior viscosity stability and superior laminate strength in both gravure printing and flexographic printing, regardless of whether it is a one-liquid type not comprising a curing agent or a two-liquid type comprising a curing agent.SOLUTION: The present invention provides a liquid ink composition comprising a binder resin (A), an organic solvent (B), and a carboxylic acid (C) having a boiling point of 150°C or less (excluding hydroxycarboxylic acids), and also printed matter and laminate made using the liquid ink composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a liquid ink composition that can be used as a laminate gravure ink or flexographic ink for flexible packaging, and to a printed matter and a laminated product using the same. [Background technology]

[0002] Lamination liquid inks, which are mainly used in the manufacture of flexible packaging materials, contain urethane resins or urethane urea resins as their main components. Furthermore, in recent years, the use of aromatic solvents such as toluene and ketone-based solvents such as methyl ethyl ketone is being restricted from the standpoint of both work hygiene during printing and the harmfulness of packaging materials. From the standpoint of printability, this toluene-free liquid ink tends to use acetate esters such as ethyl acetate and propyl acetate, alcohol-based solvents such as isopropyl alcohol and normal propyl alcohol, or mixed solvents thereof, instead of aromatic and ketone-based solvents.

[0003] However, even inks that do not use aromatic or ketone solvents cannot avoid emitting volatile organic chemicals (VOCs) into the atmosphere. Therefore, it is useful to use water in combination with organic solvents to reduce the amount of VOCs emitted. The use of water is also useful for improving the transferability of the ink.

[0004] On the other hand, isocyanate hardeners are sometimes added to improve the physical properties of liquid inks (two-component type), but this tends to result in poor viscosity stability, especially when water gets in.

[0005] As an example, a printing ink binder with excellent stability over time has been disclosed in which styrene maleic anhydride is contained as a stabilizer in a polyurethane resin solution (see, for example, Patent Document 1). However, when styrene maleic anhydride is added, the viscosity stability is good in a two-component type in which a hardener is added, but in a one-component type in which a hardener is not added, the viscosity stability cannot be said to be sufficient. In either the one-component type or the two-component type, it is desirable for the viscosity stability to be sufficiently good.

[0006] Furthermore, Patent Document 2 discloses a gravure ink containing a glycol ether organic solvent and water, but this ink does not have sufficient viscosity stability, particularly when two liquids are used.

[0007] Furthermore, the ink performance required for gravure ink or flexographic ink is good printability, and for laminating ink, adhesion to substrates and lamination strength are required. Therefore, liquid inks that are excellent in these ink performances and have good viscosity stability in either one-component or two-component types are desired. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2014-005318 A [Patent Document 2] Patent No. 6090521 Summary of the Invention [Problem to be solved by the invention]

[0009] The present invention aims to provide a liquid ink composition that has excellent viscosity stability and excellent laminate strength in either a one-component type that does not use a curing agent or a two-component type that does use a curing agent in gravure printing or flexographic printing, and also to provide a printed matter obtained by printing the liquid ink composition, and a laminate having a printed layer obtained by printing the liquid ink composition. [Means for solving the problem]

[0010] As a result of extensive research into solving the above problems, the inventors have found that by adding a carboxylic acid (excluding hydroxycarboxylic acid) having a boiling point of 150°C or less to a liquid ink composition, it is possible to improve the viscosity stability of both one-component and two-component types, and to obtain a liquid ink composition with excellent laminate strength.

[0011] That is, the present invention relates to a binder resin (A), an organic solvent (B), and a carboxylic acid (C) having a boiling point of 150° C. or less (excluding hydroxycarboxylic acids). The present invention relates to a liquid ink composition comprising:

[0012] Furthermore, the present invention relates to a printed matter obtained by printing the above liquid ink composition.

[0013] Furthermore, the present invention relates to a laminate having a printed layer formed by printing the above liquid ink composition. Effect of the Invention

[0014] The present invention provides a liquid ink composition that has excellent viscosity stability and excellent laminate strength in either a one-component type that does not use a curing agent or a two-component type that does use a curing agent in gravure printing or flexographic printing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] The present invention relates to a liquid ink composition containing a binder resin (A), an organic solvent (B), and a carboxylic acid (C) (excluding hydroxycarboxylic acids) having a boiling point of 150° C. or less. The following will explain in detail.

[0016] (Definition of words) In the present invention, the liquid ink composition refers to a liquid printing ink, such as gravure ink or flexographic ink, that is applied to a printing method using a printing plate, and is preferably gravure ink or flexographic ink. The liquid ink of the present invention does not contain an active energy curable component, i.e., it is an active energy ray non-reactive liquid ink.

[0017] In the following description, all "ink" refers to "printing ink." Furthermore, all "parts" refer to "parts by mass," "total amount of ink" refers to the total amount of ink including all volatile components such as organic solvents, and "total amount of ink solids" refers to the total amount of only non-volatile components, excluding volatile components.

[0018] The liquid ink composition of the present invention contains at least a pigment, a binder resin, an organic solvent, an acidic amino acid and its salt, and a polymer thereof.

[0019] <Binder resin> The binder resin is not particularly limited as long as it is a binder resin for liquid inks that are applied to printing methods using printing plates, such as gravure inks or flexographic inks. Examples of the resin include polyurethane resins, polyurethane polyurea resins, vinyl chloride-vinyl acetate copolymer resins, maleic acid resins, cellulose resins, polyester resins, acrylic resins, polyamide resins, chlorinated polypropylene resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, alkyd resins, polyvinyl chloride resins, rosin resins, rosin-modified maleic acid resins, ketone resins, cyclized rubbers, chlorinated rubbers, polyvinyl butyral resins, and petroleum resins. Among them, it is preferable to use polyurethane resins, polyurethane polyurea resins, acrylic resins, and vinyl chloride-vinyl acetate copolymer resins. These resins can be used alone or in combination of two or more.

[0020] The binder resin is preferably a polyurethane resin and / or a polyurethane polyurea resin, because it has excellent adhesion to the film substrate, blocking resistance, lamination suitability, highlight transferability, and the like. The content of the polyurethane resin and / or the polyurethane polyurea resin in the liquid ink composition is, for example, in the case of gravure printing, preferably 5% by mass or more in terms of solid content relative to 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 moderate ink viscosity and work efficiency during ink production and printing, and in the case of flexographic printing, preferably 5% by mass or more and 30% by mass or less in terms of solid content relative to the total mass of the flexographic ink. In addition, the lower limit of the ratio of the polyurethane resin and / or the polyurethane polyurea resin to the total amount of resin in the ink is preferably 5% by mass, more preferably 10% by mass, more preferably 15% by mass, more preferably 20% by mass, more preferably 25% by mass, and even more preferably 50% by mass or more. In addition, the upper limit of the solids weight ratio in the ink is preferably 100% by mass, more preferably 95% by mass, more preferably 90% by mass, more preferably 80% by mass, and more preferably 75% by mass.

[0021] (Polyurethane resin and / or polyurethane polyurea resin) The polyurethane resin and / or polyurethane polyurea resin is not particularly limited as long as it is a polyurethane resin obtained by reacting a polyol with a polyisocyanate. As the polyol, it is preferable to use a polyester polyol, and it is preferable to use both a polyester polyol and a polyether polyol.

[0022] The polyester polyol is preferably a polyester polyol obtained by dehydration condensation or polymerization of a low molecular weight polyol and a polycarboxylic acid or an anhydride thereof. The polyester polyol can further increase the laminate strength by increasing the cohesive energy by introducing an ester group.

[0023] As the low molecular weight polyol, various known compounds having two or more hydroxyl groups generally used in the production of polyester polyols can be used, and one or more of them may be used in combination.Specifically, for example, 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, 2-butyl-2-ethyl-1,3- Glycols having a branched structure such as propanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, neopentyl glycol, 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; glycerin, trimethylolpropane, trimethylolethane, pentaerythritol, and sorbitol can be used.

[0024] As the polyvalent carboxylic acid or anhydride thereof, various known polyvalent carboxylic acids generally used in the production of polyester polyols can be used, and one or more of them may be used in combination. Specifically, for example, polycarboxylic acids having 6 or less carbon atoms and two or more carboxyl groups, such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, fumaric acid, maleic acid, and anhydrides of these acids, aromatic dicarboxylic acids, such as phthalic acid, isophthalic acid, terephthalic acid, and anhydrides of these acids, aliphatic dicarboxylic acids, such as pimelic acid, suberic acid, azelaic acid, sebacic acid, and dimer acid, tricarboxylic acids, such as trimellitic acid and anhydrides thereof, benzenetetracarboxylic acid, benzenepentacarboxylic acid, benzenehexacarboxylic acid, and anhydrides of these acids, etc. can be used.

[0025] The polyester polyol may be any of various known polyester polyols that are generally used in the production of polyurethane resins, such as polyester polyols obtained by ring-opening polymerization of cyclic ester compounds, for example lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone), and one or more of these may be used in combination.

[0026] The number average molecular weight of the polyester polyol is preferably in the range of 500 to 8,000, more preferably in the range of 1000 to 7,000, and even more preferably in the range of 3,000 to 6,000. If the number average molecular weight of the polyester polyol is less than 500, the polyurethane resin and / or polyurethane urea resin film tends to be hard and the adhesion to the polyester film tends to be reduced. If the number average molecular weight is more than 8,000, the polyurethane resin film tends to be brittle and the blocking resistance of the ink film tends to be reduced.

[0027] As the polyether polyol, various known polyether polyols generally used in the production of polyurethane resins and / or polyurethane polyurea resins can be used, and one or more of them may be used in combination. For example, polyether polyols of polymers or copolymers of methylene oxide, ethylene oxide, propylene oxide, tetrahydrofuran, etc. can be mentioned. Specifically, known general-purpose ones such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol may be used. By containing polyether polyol, adhesion, especially on high-performance barrier films, is greatly improved, resulting in excellent blocking resistance and laminate strength.

[0028] The polyether polyol preferably has a number average molecular weight of 100 to 4000. If the number average molecular weight of the polyether polyol is less than 100, the film of the polyurethane resin (A) tends to be hard, and the adhesion to the polyester film is reduced. If the number average molecular weight is more than 4000, the film of the polyurethane resin tends to be brittle, and the blocking resistance of the ink film is reduced.

[0029] The polyether polyol is preferably contained in the range of 1 to 50% by mass relative to the polyurethane resin and / or polyurethane polyurea resin. If the polyether polyol is less than 1 part by mass relative to 100 parts by mass of the polyurethane resin and / or polyurethane polyurea resin, the solubility of the polyurethane resin and / or polyurethane polyurea resin in ketone, ester, and alcohol-based solvents decreases, and the adhesion to the high-performance barrier film tends to decrease. In addition, the resolubility of the ink film in the solvent decreases, and the tone reproducibility of the printed matter tends to decrease. If the amount exceeds 50 parts by mass, the ink film becomes excessively soft and tends to have poor blocking resistance. The number average molecular weight of the polyester polyol or polyether polyol is a value measured by gel permeation chromatography (GPC) under the following conditions. Measurement equipment: High-speed GPC equipment (Tosoh Corporation "HLC-8220GPC") Column: The following columns manufactured by Tosoh Corporation were used, connected in series.

[0030] "TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 "TSKgel G2000" (7.8mmI.D. x 30cm) x 1 Detector: RI (differential refractometer) Column temperature: 40℃ Eluent: tetrahydrofuran (THF) Flow rate: 1.0mL / min Injection volume: 100 μL (sample concentration 0.4% by mass in tetrahydrofuran solution) Standard sample: A calibration curve was prepared using the following standard polystyrene. (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 In addition, as a polyol to be used in combination with the polyurethane resin and / or polyurethane polyurea resin as required, various known polyols generally used in the production of polyurethane resins can be used, and one or more of them may be used in combination. For example, saturated polyols such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, and pentaerythritol are usable. polycarbonate polyols (2) obtained by reacting the above-mentioned low molecular weight polyols with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, phosgene, etc.; polybutadiene glycols (3); glycols (4) obtained by adding ethylene oxide or propylene oxide to bisphenol A; and acrylic polyols (4) obtained by copolymerizing, in one molecule, one or more hydroxyethyl groups, hydroxypropyl acrylate, hydroxybutyl acrylate, etc., or the corresponding methacrylic acid derivatives, etc., with, for example, acrylic acid, methacrylic acid, or an ester thereof.

[0031] Diisocyanate compounds used in polyurethane resins and / or polyurethane polyurea resins include various known aromatic diisocyanates, aliphatic diisocyanates, alicyclic diisocyanates, etc. that are generally used in the production of polyurethane resins. For example, 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, cyclohexane-2,4-di ... ,4-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, dimeryl diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis(isocyanatemethyl)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, etc. These diisocyanate compounds can be used alone or in combination of two or more kinds.

[0032] Examples of chain extenders used in polyurethane resins and / or polyurethane polyurea resins 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.

[0033] In addition, a monovalent active hydrogen compound can be used as a terminal blocking agent for the purpose of stopping the reaction. Examples of such compounds include dialkylamines such as di-n-butylamine, and alcohols such as ethanol and isopropyl alcohol. Furthermore, when it is particularly desired to introduce a carboxyl group into the polyurethane resin, amino acids such as glycine and L-alanine can be used as a reaction stopping agent. These terminal blocking agents can be used alone or in combination of two or more.

[0034] The polyurethane resin and / or polyurethane polyurea resin is produced, for example, by reacting polypropylene glycol and a polyol used in combination with a diisocyanate compound in a ratio in which the isocyanate group is in excess to obtain a prepolymer having an isocyanate group at the end, and reacting the obtained prepolymer with a chain extender and / or a terminal blocking agent in a suitable solvent, i.e., an ester solvent such as ethyl acetate, propyl acetate, or butyl acetate, which is usually used as a solvent for non-toluene gravure ink; a ketone solvent such as acetone, methyl ethyl ketone, or methyl isobutyl ketone; an alcohol solvent such as methanol, ethanol, isopropyl alcohol, or n-butanol; a hydrocarbon solvent such as methylcyclohexane or ethylcyclohexane; or a mixture of these solvents, in a two-stage method, or by reacting polypropylene glycol and a polyol used in combination with a diisocyanate compound, a chain extender, and / or a terminal blocking agent at once in a suitable solvent among the above. Among these methods, the two-stage method is preferable for obtaining a uniform polyurethane resin and / or polyurethane polyurea resin. In addition, when producing polyurethane resin and / or polyurethane polyurea resin by a two-stage method, it is preferable to react so that the total (equivalent ratio) of amino groups of the chain extender and (or) end blocking agent is 1 / 0.9 to 1.3. When the equivalent ratio of the isocyanate group to the amino group is smaller than 1 / 1.3, the chain extender and (or) end blocking agent remain unreacted, and the polyurethane resin and / or polyurethane polyurea resin may yellow or emit an odor after printing. Furthermore, in recent years, from the viewpoint of the working environment, it is more preferable not to use aromatic solvents such as toluene and xylene or ketone solvents.

[0035] The weight average molecular weight of the polyurethane resin and / or polyurethane polyurea resin thus obtained is preferably within the range of 15,000 to 100,000, and more preferably within the range of 15,000 to 80,000. If the weight average molecular weight of the polyurethane resin and / or polyurethane polyurea resin is less than 15,000, the blocking resistance of the resulting ink composition and the strength and oil resistance of the printed film tend to be reduced, while if it exceeds 100,000, the viscosity of the resulting ink composition tends to be high, making it difficult to obtain a desired print density.

[0036] Furthermore, the amine value of the polyurethane resin and / or polyurethane urea resin used in the liquid ink composition of the present invention 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.

[0037] In order to obtain heat resistance in the ink film, it is effective to use a resin having a urea bond such as a polyurethane polyurea resin. In addition, the polyurethane resin and / or polyurethane urea resin is preferably a biomass urethane resin and / or a biomass polyurethane urea resin that uses a material derived from biomass.

[0038] The binder resin (A) is preferably a combination of the above-mentioned polyurethane resin and / or polyurethane urea resin with other resins. The resin to be used in combination with the polyurethane resin and / or polyurethane urea resin may be, for example, one or more resins selected from vinyl chloride-vinyl acetate copolymer resin, maleic acid resin, cellulose resin, polyester resin, acrylic resin, and polyamide resin. In the binder resin (A), the content of the resin other than the polyurethane resin and / or polyurethane urea resin is preferably in the range of 1 to 50 mass% relative to the total mass (solid content) of the binder resin (A), and more preferably 2 to 40 mass%.

[0039] (Vinyl chloride-vinyl acetate copolymer resin) The binder resin (A) may contain a vinyl chloride-vinyl acetate copolymer resin, which provides excellent dispersibility.

[0040] The vinyl chloride-vinyl acetate copolymer resin used in the liquid ink composition of the present invention is obtained, for example, by copolymerizing vinyl chloride and vinyl acetate, and may have hydroxyl groups in the resin. Such vinyl chloride-vinyl acetate copolymer resins having hydroxyl groups can be obtained by introducing hydroxyl groups by partially hydrolyzing the copolymerized vinyl chloride and vinyl acetate resins, or by adding a component having a hydroxyl group other than vinyl chloride and vinyl acetate, such as 2-hydroxyethyl methacrylate, during polymerization and copolymerizing the resulting mixture to introduce hydroxyl groups. Commercially available vinyl chloride-vinyl acetate copolymer resins having hydroxyl groups can also be used.

[0041] In the case of vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group, the properties of the resin coating and the resin dissolution behavior are determined by the content ratio of hydroxyl group-containing structures such as vinyl chloride skeleton, vinyl acetate skeleton, and vinyl alcohol skeleton. That is, vinyl chloride imparts toughness and hardness to the resin coating, vinyl acetate imparts adhesiveness and flexibility, and hydroxyl groups such as vinyl alcohol impart good solubility in polar solvents. It is preferable that the total resin components contain 0.1 to 5.0 mass% in terms of solid content.

[0042] (Cellulose-based resin) The binder resin (A) may contain a cellulose-based resin. Examples of the cellulose-based resin include cellulose acetate propionate, cellulose acetate butyrate, and other cellulose ester resins, nitrocellulose (also called nitrocellulose), hydroxyalkyl cellulose, and carboxyalkyl cellulose. The cellulose ester resin preferably has an alkyl group, and examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, and a hexyl group, and the alkyl group may further have a substituent.

[0043] Of the above, the cellulose-based resin is preferably cellulose acetate propionate, cellulose acetate butyrate, or nitrocellulose. The molecular weight is preferably 5,000 to 200,000 in weight average molecular weight, more preferably 10,000 to 50,000. The glass transition temperature is preferably 120°C to 180°C. The combined use of the polyurethane resin and / or polyurethane polyurea resin of the present invention is expected to improve the blocking resistance, scratch resistance, and other physical properties of the ink film.

[0044] Nitrocellulose (nitrocellulose) is preferably obtained by reacting natural cellulose with nitric acid to replace three hydroxyl groups in the six-membered ring of the anhydrous glucopyranose group in the natural cellulose with nitric acid groups to produce a nitric acid ester.

[0045] (Acrylic resin) The acrylic resin is not particularly limited as long as it is a copolymer of a polymerizable monomer mainly composed of (meth)acrylic acid ester. Examples of the polymerizable monomer include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, iso-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, iso-octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, iso-nonyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and phenoxyethyl (meth)acrylate. The polymerization method is not particularly limited, and those obtained by known bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc. can be used.

[0046] The weight average molecular weight of the acrylic resin is preferably in the range of 5,000 to 200,000, and more preferably in the range of 10,000 to 100,000. The amount of the acrylic resin added is preferably 0.15 to 40% by mass, and more preferably 1.0 to 35% by mass, based on the total amount of the ink.

[0047] (polyester resin) The polyester resin is not particularly limited as long as it is a polyester resin obtained by reacting an alcohol with a carboxylic acid using a known esterification polymerization reaction.

[0048] Examples of alcohols include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-butyl-1,3propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 1,2-pentanediol, 3-methyl-1,5-pentanediol, hexanediol, octanediol, 1,4-butynediol, 1,4-butylenediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol, 1,4-cyclohexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, spiroglycol, and isosorbide. These may be used alone or in combination of two or more. Among these, polyfunctional alcohols are preferred.

[0049] Examples of carboxylic acids include formic acid, acetic acid, propionic acid, butanoic acid, pentanoic acid, hexanoic acid, heptanoic acid, hexanoic acid, heptanoic acid, octanoic acid, nonanoic acid, decanoic acid, oleic acid, linoleic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, and 1,4-cyclohexanedicarboxylic acid. These may be used alone or in combination of two or more. Among these, polyfunctional carboxylic acids are preferred.

[0050] The weight average molecular weight of the polyester resin is preferably 500 to 6000, and more preferably 1400 to 5500. The amount of polyester resin added is preferably 0.15 to 40% by mass, and more preferably 1.0 to 35% by mass, based on the total amount of the ink.

[0051] (Polyamide resin) The polyamide resin is, for example, a thermoplastic polyamide soluble in an organic solvent that can be obtained by polycondensation of a polybasic acid and a polyamine. In particular, a polyamide resin containing a reaction product of an acid component containing a polymerized fatty acid and / or a dimer acid with an aliphatic and / or aromatic polyamine is preferable, and further, a polyamide resin containing a portion of primary and secondary monoamines is preferable.

[0052] Examples of polybasic acids used as raw materials for polyamide resins include, but are not limited to, adipic acid, sebacic acid, azelaic acid, phthalic anhydride, isophthalic acid, suberic acid, glutaric acid, fumaric acid, pimelic acid, oxalic acid, malonic acid, succinic acid, maleic acid, terephthalic acid, 1,4-cyclohexyldicarboxylic acid, trimellitic acid, dimer acid, hydrogenated dimer acid, and polymerized fatty acid. Among these, polyamide resins containing a structure derived from dimer acid or polymerized fatty acid as the main component (50% by mass or more in the polyamide resin) are preferred. Here, polymerized fatty acid is obtained by cyclization reaction of unsaturated fatty acid, and includes monobasic fatty acid, dimerized polymerized fatty acid (dimer acid), trimerized polymerized fatty acid, and the like. Fatty acids constituting dimer acid or polymerized fatty acid include those derived from natural oils such as soybean oil, palm oil, and rice bran oil, and those obtained from oleic acid and linoleic acid are preferred. The polybasic acid may be used in combination with a monocarboxylic acid, such as acetic acid, propionic acid, lauric acid, palmitic acid, benzoic acid, or cyclohexane carboxylic acid.

[0053] Examples of the polyamine include polyamines, primary or secondary monoamines, etc. Examples of the polyamines used in the polyamide resin include aliphatic diamines such as ethylenediamine, propylenediamine, hexamethylenediamine, and methylaminopropylamine, and aliphatic polyamines such as diethylenetriamine and triethylenetetramine, and examples of the alicyclic polyamines include cyclohexylenediamine and isophoronediamine. Examples of the aromatic aliphatic polyamines include xylylenediamine, and examples of the aromatic polyamines include phenylenediamine and diaminodiphenylmethane. Examples of the primary and secondary monoamines include n-butylamine, octylamine, diethylamine, monoethanolamine, monopropanolamine, diethanolamine, and dipropanolamine.

[0054] The amount of polyamide resin added is preferably 0.15 to 40% by mass, and more preferably 1.0 to 35% by mass, based on the total amount of the ink.

[0055] (Organic solvent (B)) As the organic solvent (B) used in the liquid ink composition, various organic solvents can be used, for example, aromatic organic solvents such as toluene and xylene, ketone-based solvents such as acetone, methyl ethyl ketone, and methyl isobutyl ketone, ester-based solvents such as ethyl acetate, n-propyl acetate, butyl acetate, and propylene glycol monomethyl ether acetate, and alcohol-based solvents such as n-propanol, isopropanol, n-butanol, and propylene glycol monomethyl ether, which can be used alone or in a mixture of two or more. Among them, from the viewpoint of compatibility when carboxylic acid (C) is added, it is preferable to contain ester-based solvents such as ethyl acetate, n-propyl acetate, and butyl acetate, and it is more preferable to use these ester-based solvents and alcohol-based solvents in combination. In recent years, from the viewpoint of working environment, it is more preferable not to use aromatic solvents such as toluene and xylene or ketone-based solvents.

[0056] The liquid ink composition may contain water as a volatile component together with the organic solvent. The content of water is preferably less than 10% by mass of the total ink composition. The addition of water makes it possible to control the drying property of the ink, and in particular in gravure printing, the gradation part characterized by a small amount of ink transfer can be beautifully reproduced. Furthermore, it is preferable that the content of water is in the range of 1 to 5% by mass of the total ink composition, because this improves the printability.

[0057] The addition of water also makes it possible to reduce the amount of organic solvent used. Water may be added to the organic solvent in advance to make it a water-containing organic solvent, or a specific amount of water may be added separately. Alternatively, a carboxylic acid aqueous solution may be prepared by mixing the solvent (B) with a carboxylic acid (C) having a boiling point of 150° C. or less, and the carboxylic acid aqueous solution may be added to an organic solvent or a liquid ink composition to make a water-containing liquid ink composition.

[0058] (Carboxylic acid (C) with a boiling point of 150°C or less) The liquid ink composition of the present invention requires a carboxylic acid (C) having a boiling point of 150° C. or less (however, hydroxycarboxylic acids are excluded in the case of carboxylic acid (C)). Due to the composition of the binder resin (A), organic solvent (B), and carboxylic acid (C) having a boiling point of 150° C. or less (however, hydroxycarboxylic acids are excluded in the case of carboxylic acid (C)), a liquid ink with excellent viscosity stability can be obtained in both a one-component type that does not use a curing agent and a two-component type that does use a curing agent.

[0059] The carboxylic acid (C) having a boiling point of 150° C. or less may be any compound having a carboxylic acid structure in the molecule, and examples thereof include carboxylic acids having a carbon number of 1 to 3. More specific examples thereof include formic acid, acetic acid, and ethyl carboxylic acid.

[0060] By including a carboxylic acid (C) having a boiling point of 150°C or less, a liquid ink composition having excellent stability over time in one liquid and excellent stability in two liquids can be obtained. In addition, compared to the case of using a hydroxycarboxylic acid, the laminate strength can be improved. This is because the carboxylic acid (C) has a boiling point of 150°C or less, and therefore is easily volatilized in the drying process after application of the ink composition, and does not remain in the coating film. On the other hand, even if the boiling point is 150°C or less, hydroxycarboxylic acids such as malic acid and gluconic acid do not volatilize, and the solid content remains in the coating film, so it is thought that they are unlikely to contribute to improving the laminate strength.

[0061] The amount of the hydroxycarboxylic acid (C) added is not particularly limited. The upper limit is preferably 0.05% by mass or less, more preferably 0.03% by mass or less, and more preferably 0.01% by mass or less, based on the total amount of the liquid ink composition. On the other hand, the lower limit is preferably 0.0001% by mass or more, and even more preferably 0.0015% by mass or more. Specifically, the range in which the effects of the present invention can be sufficiently obtained is preferably 0.0001% by mass or more and 0.05% by mass or less, more preferably 0.001% by mass or more and 0.01% by mass or less, and even more preferably 0.0015% by mass or more and 0.015% by mass or less.

[0062] (Colorant (D)) Examples of the colorant (D) include organic and inorganic pigments and dyes that are commonly used in inks, paints, and recording materials.

[0063] Examples of the organic pigment include condensed polycyclic organic pigments having a cyclic structure with a benzene ring or a heterocycle, azo pigments, etc. Specific examples of preferred organic pigments are given below.

[0064] The azo pigment may be any organic pigment having an azo group (N=N) in the molecule, and may be any of a soluble azo lake pigment, an insoluble azo pigment, and a condensed azo pigment. Examples of azo pigments include CI Pigment Red 10, CI Pigment Red 11, CI Pigment Red 112, CI Pigment Red 114, CI Pigment Red 119, CI Pigment Red 12, CI Pigment Red 136, CI Pigment Red 14, CI Pigment Red 144, CI Pigment Red 146, CI Pigment Red 147, CI Pigment Red 15, CI Pigment Red 150, and CI Pigment Red 160. 6, CI Pigment Red 164, CI Pigment Red 166, CI Pigment Red 17, CI Pigment Red 170, CI Pigment Red 171, CI Pigment Red 175, CI Pigment Red 176, CI Pigment Red 18, CI Pigment Red 183, CI Pigment Red 184, CI Pigment Red 185, CI Pigment Red 187, CI Pigment Red 188, CI Pigment Red 193, CI Pigment Red 194, CI Pigment Red 195, CI Pigment Red 196, CI Pigment Red 197, CI Pigment Red 198, CI Pigment Red 199, CI Pigment Red 200, CI Pigment Red 201, CI Pigment Red 202, CI Pigment Red 203, CI Pigment Red 204, CI Pigment Red 205, CI Pigment Red 206, CI Pigment Red 207, CI Pigment Red 208, CI Pigment Red 209, CI Pigment Red 210, CI Pigment Red 211, CI Pigment Red 212, CI Pigment Red 213, CI Pigment Red 214, CI Pigment Red 215, CI Pigment Red 216, CI Pigment Red 217, CI Pigment Red 218, CI Pigment Red 219 Tread 2, CI Pigment Red 200, CI Pigment Red 208, CI Pigment Red 21, CI Pigment Red 210, CI Pigment Red 211, CI Pigment Red 213, CI Pigment Red 214, CI Pigment Red 22, CI Pigment Red 220, CI Pigment Red 221, CI Pigment Red 23, CI Pigment Red 237, CI Pigment Red 238, CI Pigment Red 239, CI Pigment Red 240, CI Pigment Red 241, CI Pigment Red 242, CI Pigment Red 243, CI Pigment Red 244, CI Pigment Red 245, CI Pigment Red 246, CI Pigment Red 247, CI Pigment Red 248, CI Pigment Red 249 Pigment Red 242, CI Pigment Red 243, CI Pigment Red 245, CI Pigment Red 247, CI Pigment Red 253, CI Pigment Red 256, CI Pigment Red 258, CI Pigment Red 266, CI Pigment Red 268, CI Pigment Red 269, CI Pigment Red 3, CI Pigment Red 31, CI Pigment Red 32, CI Pigment Red 38, CI Pigment Red 4, CIPigment Red 41, CI Pigment Red 48, CI Pigment Red 48:1, CI Pigment Red 48:2, CI Pigment Red 48:3, CI Pigment Red 48:4, CI Pigment Red 49, CI Pigment Red 49:1, CI Pigment Red 49:2, CI Pigment Red 5, CI Pigment Red 50:1, CI Pigment Red 52:1, CI Pigment Red 52:2, CI Pigment Red 53:1, CI Pigment Red 54, CI Pigment Red 55:1, CI Pigment Red 56:2, CI Pigment Red 57:1, CI Pigment Red 58:2, CI Pigment Red 59:3, CI Pigment Red 60:1, CI Pigment Red 61:1, CI Pigment Red 62:1, CI Pigment Red 63:2, CI Pigment Red 64:1, CI Pigment Red 65:1, CI Pigment Red 66:1, CI Pigment Red 67:1, CI Pigment Red 68:2, CI Pigment Red 69:1, CI Pigment Red 70:1, CI Pigment Red 71:1, CI Pigment Red 72:1, CI Pigment Red 73:1, CI Pigment Red 74:1, CI Pigment Red 75:1, CI Pigment Red 76:1, CI Pigment Red 77:1, CI Pigment Red 78:1, CI Pigment Red 79:2, CI Pigment Red 80:1, CI Pigment Red 81:1, CI Pigment Red 82:1, CI Pigment Red 8 Tread 57:1, CI Pigment Red 58, CI Pigment Red 58:4, CI Pigment Red 6, CI Pigment Red 60, CI Pigment Red 60:1, CI Pigment Red 63, CI Pigment Red 63:1, CI Pigment Red 63:2, CI Pigment Red 64:1, CI Pigment Red 68, CI Pigment Red 7, CI Pigment Red 8, CI Pigment Red 9, CI Pigment Red 95, CI Pigment Yellow 1, CI Pigment Yellow Rho 10, CI Pigment Yellow 100, CI Pigment Yellow 104, CI Pigment Yellow 105, CI Pigment Yellow 106, CI Pigment Yellow 111, CI Pigment Yellow 113, CI Pigment Yellow 114, CI Pigment Yellow 116, CI Pigment Yellow 12, CI Pigment Yellow 120, CI Pigment Yellow 124, CI Pigment Yellow 126, CI Pigment Yellow 127, CI Pigment Yellow 128, CI Pigment Yellow 129, CI Pigment Yellow 200, CI Pigment Yellow 201, CI Pigment Yellow 202, CI Pigment Yellow 203, CI Pigment Yellow 204, CI Pigment Yellow 205, CI Pigment Yellow 206, CI Pigment Yellow 207, CI Pigment Yellow 208, CI Pigment Yellow 209, CI Pigment Yellow 210, CI Pigment Yellow 211, CI Pigment Yellow 212, CI Pigment Yellow 213, CI Pigment Yellow 214, CI Pigment Yellow 215, CI Pigment Yellow 216, CI Pigment Yellow 217, CI Pigment Yellow 218, CI Pigment Yellow 219, CI Pigment Yellow 220, CI Pigment Yellow 221, CI Pigment Yellow 222, CI Pigment Yellow 223, CI Pigment Yellow 224, CI Pigment Yellow 225, CI Pigment Yellow 226, CI Pigment Yellow 227, CI Pigment Yellow 228, CI Pigment Yellow 229, CI Pigment Yellow 230, Pigment Yellow 13, CI Pigment Yellow 130, CI Pigment Yellow 133, CI Pigment Yellow 14, CI Pigment Yellow 15, CI Pigment Yellow 151, CI Pigment Yellow 152, CI Pigment Yellow 154, CI Pigment Yellow 155, CI Pigment Yellow 16, CI Pigment Yellow 165, CI Pigment Yellow 166, CI Pigment Yellow 167, CI Pigment Yellow 168, CI Pigment Yellow 169, CIPigment Yellow 17, CI Pigment Yellow 170, CI Pigment Yellow 172, CI Pigment Yellow 174, CI Pigment Yellow 175, CI Pigment Yellow 176, CI Pigment Yellow 180, CI Pigment Yellow 181, CI Pigment Yellow 183, CI Pigment Yellow 191, CI Pigment Yellow 191:1, CI Pigment Yellow 194, CI Pigment Yellow 2, CI Pigment Yellow 205, CI Pigment Yellow 2 06, CI Pigment Yellow 209, CI Pigment Yellow 212, CI Pigment Yellow 214, CI Pigment Yellow 219, CI Pigment Yellow 3, CI Pigment Yellow 4, CI Pigment Yellow 49, CI Pigment Yellow 5, CI Pigment Yellow 55, CI Pigment Yellow 6, CI Pigment Yellow 60, CI Pigment Yellow 61, CI Pigment Yellow 62, CI Pigment Yellow 63, CI Pigment Yellow 65, CI Pigment Yellow Pigment Yellow 7, CI Pigment Yellow 73, CI Pigment Yellow 74, CI Pigment Yellow 75, CI Pigment Yellow 77, CI Pigment Yellow 81, CI Pigment Yellow 83, CI Pigment Yellow 87, CI Pigment Yellow 9, CI Pigment Yellow 93, CI Pigment Yellow 94, CI Pigment Yellow 95, CI Pigment Yellow 97, CI Pigment Yellow 98, CI Pigment Orange 1, CI Pigment Orange 13, CI Pigment Pigment Orange 15, CI Pigment Orange 16, CI Pigment Orange 17, CI Pigment Orange 17:1, CI Pigment Orange 19, CI Pigment Orange 2, CI Pigment Orange 22, CI Pigment Orange 24, CI Pigment Orange 3, CI Pigment Orange 34, CI Pigment Orange 36, CI Pigment Orange 38, CI Pigment Orange 4, CI Pigment Orange 46, CI Pigment Orange 5, CI Pigment Orange 60, CIPigment Orange 62, CI Pigment Orange 64, CI Pigment Orange 72, CI Pigment Orange 74, CI Pigment Brown 25, CI Pigment Brown 32, CI Pigment Brown 5, CI Pigment Blue 25, CI Pigment Blue 26, CI Pigment Violet 13, CI Pigment Violet 17, CI Pigment Violet 32, and CI Pigment Violet 50. These may be used alone or in combination.

[0065] As the azo pigment, CI Pigment Red 57:1 (PR57:1), CI Pigment Red 146 (PR146), CI Pigment Yellow 13 (PY13), CI Pigment Yellow 55 (PY55), CI Pigment Yellow 83 (PY83), CI Pigment Yellow 180 (PY180), and CI Pigment Range 13 (PO13) are particularly preferred.

[0066] The primary particle size of the azo pigment is, for example, 0.01-1.0 μm, preferably 0.1-0.6 μm. The specific surface area of ​​the azo pigment is, for example, 10-150 m2 / g, preferably 20-100 m2 / g. When the primary particle size and specific surface area are within the above ranges, the pigment can have excellent coloring power and dispersibility.

[0067] In addition, the color pigment may be a condensed polycyclic organic pigment. The condensed polycyclic organic pigment refers to an organic pigment having a cyclic structure with a benzene ring or a heterocycle among organic pigments. Examples of the condensed polycyclic organic pigment used in the present invention include CI Pigment Blue 15, CI Pigment Blue 15:1, CI Pigment Blue 15:2, CI Pigment Blue 15:3, CI Pigment Blue 15:4, CI Pigment Blue 15:5, CI Pigment Blue 15:6, CI Pigment Blue 16, CI Pigment Blue 17, CI Pigment Blue 75, CI Pigment Blue 79, CI Pigment Green 7, and CI Pigment Green 36. , Phthalocyanine pigments such as CI Pigment Green 58, CI Pigment Green 59, CI Pigment Green 62, CI Pigment Green 63, CI Pigment Violet 19, CI Pigment Violet 42, CI Pigment Violet 55, CI Pigment Red 122, CI Pigment Red 202, CI Pigment Red 206, CI Pigment Red 207, CI Pigment Red 209, CI Pigment Orange 48, CI Quinacridone pigments such as CI Pigment Orange 49; Dioxazine pigments such as CI Pigment Violet 23, CI Pigment Violet 34, CI Pigment Violet 35, CI Pigment Violet 37, CI Pigment Blue 80; Perylene pigments such as CI Pigment Red 123, CI Pigment Red 149, CI Pigment Red 178, CI Pigment Red 179, CI Pigment Red 190, CI Pigment Red 224, CI Pigment Violet 29, CI Pigment Black 31, CI Pigment Black 32; Perinone pigments such as CI Pigment Orange 43, CI Pigment Red 194; Isoindolinone pigments such as CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 173, CI Pigment Yellow 179, CI Pigment Orange 61, CI Pigment Brown 38;Isoindoline pigments such as CI Pigment Yellow 185, CI Pigment Orange 66, CI Pigment Orange 69, CI Pigment Red 260; Thioindigo pigments such as CI Pigment Red 88, CI Pigment Red 181, CI Pigment Red 279, CI Pigment Violet 36, CI Pigment Violet 38; CI Pigment Red 83, CI Pigment Red 89, CI Pigment Red 168, CI Pigment Red 177, CI Pigment Red 182, CI Pigment Red 216, CI Pigment Red 226, CI Pigment Red 251, CI Pigment Red 263, CI Pigment Blue 60, CI Pigment Yellow 24, CI Pigment Yellow 99, CI Pigment Yellow 108, CI Pigment Yellow 123, CI Pigment Yellow 199, CI Pigment Violet 31, CI Pigment Orange 4 0, CI Pigment Orange 51, CI Pigment Violet 5:1, CI Pigment Black 20 and other anthraquinone pigments, CI Pigment Yellow 138, CI Pigment Yellow 231 and other quinophthalone pigments, CI Pigment Orange 71, CI Pigment Orange 73, CI Pigment Orange 81, CI Pigment Red 254, CI Pigment Red 255, CI Pigment Red 264, CI Pigment Red 270, CI Pigment Red 272 and other diketopyrrolopyrrole pigments, CI Pigment Yellow 117, CI Pigment Yellow 129, CI Pigment Yellow 150, CI Pigment Yellow 153, CI Pigment Orange 65, CI Pigment Orange 68, CI Pigment Red 257, CI Pigment Red 271, CI Pigment Green 8, CI Pigment Green 10 and other metal complex pigments.

[0068] The condensed polycyclic organic pigment used in the present invention may be a commercially available product, or may be manufactured by a known, commonly used method. Of course, after manufacturing, it may be used after being appropriately treated with known methods, for example, pigment derivative treatment, surfactant treatment, rosin treatment, or resin treatment. Furthermore, the pigment particle size, particle shape, and particle surface charge may be adjusted and controlled for printing inks, paints, colored molded products, stationery, textile printing, toner, color filters, inkjet inks, and cosmetics. When a condensed polycyclic organic pigment with a high specific surface area by the BET method is used in an ink, the viscosity of the ink increases, and when the specific surface area is low, the coloring power of the ink decreases. Therefore, the specific surface area by the BET method of the condensed polycyclic organic pigment is 20 to 130 m. 2 / g is preferable, and 50 to 100m 2 / g range is more preferred.

[0069] Examples of inorganic pigments include white inorganic pigments such as titanium oxide, zinc oxide, zinc sulfide, barium sulfate, calcium carbonate, chromium oxide, silica, litbones, antimony white, and gypsum. Among inorganic pigments, titanium oxide is particularly preferred. Titanium oxide is white and is preferred in terms of coloring power, hiding power, chemical resistance, and weather resistance, and from the viewpoint of printing performance, the titanium oxide is preferably treated with silica and / or alumina.

[0070] Examples of inorganic pigments other than white include carbon black, aluminum particles, mica, bronze powder, chrome vermilion, yellow lead, cadmium yellow, cadmium red, ultramarine, Prussian blue, and zircon. Aluminum is in powder or paste form, but it is preferable to use it in paste form from the standpoint of handleability and safety. Whether leafing or non-leafing aluminum is used is selected appropriately from the standpoint of brightness and concentration.

[0071] The carbon black may be any commercially available carbon black. There is no particular limitation on the carbon black that can be used, and various commercially available carbon blacks such as oil furnace black, gas furnace black, channel black, and acetylene black produced by the contact method, furnace method, thermal method, etc. may be used. The particle size of the carbon black is, for example, 5 to 200 nm, and preferably 20 to 50 nm. The nitrogen adsorption specific surface area of ​​the carbon black is, for example, 20 to 500 m 2 / g, preferably 30 to 150m 2 The DBP oil absorption of carbon black is, for example, 20 to 150 cm 3 / 100g, preferably 30-120cm 3 The carbon black has a volatile content of, for example, 0.1 to 10.0%. The carbon black has a pH value of, for example, 1 to 10, preferably 2 or higher.

[0072] The commercially available carbon blacks include MA7, 8, 11, 77, 100, 100R, 100S, 220, 230, 600, #650, #750, #40, #44B, #44, #45B, #47, #45, #33, #45L, #47, #50, #52, #2700, #2650, #2600, #200, #2350, #2300, #2200, #1000, #990, #980, #970, #960, #950, #900, #850, #32, #30, #25, #20, #10, #5, CF9, #95, #260 (all manufactured by Mitsubishi Chemical Corporation), and Special Black6, 5, 4A, 4, 101, 550, 350, 250, 100", "Printex U, 150T, V, 140V, 140U", "PrinteX P, L6, L, G, ES23, ES22, A, 95, 90, 85, 80, 75, 60, 55, 45, 40, 35, 300, 30, 3, 25, 200", "Color Black S170, S160, FW2V, FW200, FW2, FW18, FW1" (all manufactured by Orion Engineered Carbons), "Black Pearls1000M, 800, 880, 4630", "Monarch 1300, 700, 880, 4630", "Regal 330R, 660R, 660, 400R, 415R, 415", "MOGUL E, L" (all manufactured by Cabot Corporation), "Raven 7000, 3500, 5250, 5750, 5000ULTRAII, 1255, 1250, 1190, 1000, 1020, 1035, 1100ULTRA, 1170, 1200" (all manufactured by Columbian Chemicals), "SUNBLACK SB200, 210, 220, 230, 240, 250, 260, 270, 280, 300, 305, 320, 400, 410, 600, 700, 705, 710, 715, 720, 725, 805, 900, 910, 935, 960" (all manufactured by Asahi Carbon Co., Ltd.), Toka Black #8500, #8500F, #7550SB, #7550F" (all manufactured by Tokai Carbon Co., Ltd.), and the like.

[0073] The liquid ink composition has excellent ink dispersibility and flowability, whether it is a one-component type that does not use a curing agent such as an isocyanate curing agent, or a two-component type that does use a curing agent.

[0074] As the curing agent, known ones can be used, but it is preferable to use a polyisocyanate-based curing agent (crosslinking agent) using an aromatic isocyanate such as diphenylmethane diisocyanate, toluene diisocyanate, xylene diisocyanate, or naphthalene diisocyanate, or an alicyclic isocyanate such as isophorone diisocyanate or norbornene diisocyanate.

[0075] The liquid ink composition may further contain, as necessary, an extender pigment, a pigment dispersant, a leveling agent, an antifoaming agent, a wax, a plasticizer, an infrared absorbing agent, an ultraviolet absorbing agent, an aromatic agent, a flame retardant, and the like.

[0076] The liquid ink composition can be produced by dissolving and / or dispersing a resin, a pigment, etc., in an organic solvent. Specifically, a pigment dispersion is produced by dispersing a pigment in an organic solvent using a polyurethane resin or the like, and other compounds are added to the resulting pigment dispersion as necessary to produce an ink. The carboxylic acid having 1 to 20 carbon atoms may be added during the production of the pigment, during the production of the pigment dispersion, or during the production of the ink using the pigment dispersion.

[0077] The particle size distribution of the pigment in the pigment dispersion can be adjusted by appropriately adjusting the size of the grinding media of the dispersing machine, the packing rate of the grinding media, the dispersion treatment time, the discharge speed of the pigment dispersion, the viscosity of the pigment dispersion, etc. As the dispersing machine, for example, a commonly used roller mill, ball mill, pebble mill, attritor, sand mill, etc. can be used.

[0078] When air bubbles or unexpectedly large particles are contained in the ink, they degrade the quality of the printed matter, so it is preferable to remove them by filtration, etc. As the filter, a conventionally known filter can be used.

[0079] The viscosity of the ink produced by the above method is preferably in the range of 10 mPa s or more from the viewpoint of preventing sedimentation of the pigment and adequately dispersing it, and 1000 mPa s or less from the viewpoint of workability during ink production and printing. The above viscosity is measured at 25°C using a Tokimec B-type viscometer.

[0080] The viscosity of the ink can be adjusted by appropriately selecting the types and amounts of raw materials used, such as polyurethane resin, colorant, organic solvent, etc. The viscosity of the ink can also be adjusted by adjusting the particle size and particle size distribution of the colorant in the ink.

[0081] The hues of the liquid ink composition of the present invention include yellow, red, indigo, and black as basic process colors, and three colors outside the process gamut: red (orange), grass (green), and purple, depending on the type of pigment used. In addition, transparent yellow, peony, vermilion, brown, gold, silver, pearl, and a nearly transparent medium (containing an extender pigment as necessary) for adjusting color density are prepared as base colors. Inks for boiling retort printing are appropriately selected in consideration of the migration property and heat resistance of the pigment. The base inks of each hue are diluted with a diluting solvent to a viscosity and concentration suitable for gravure printing or flexographic printing, and are supplied to each printing unit alone or mixed together.

[0082] (Printed material) The printed matter of the present invention is a printed matter obtained by printing the above-mentioned liquid ink composition on a substrate such as a film. The printed matter of the present invention may be a multilayer printed matter having a plurality of printed layers. In the case of a multilayer printed matter, at least one layer may be formed by the liquid ink composition of the present invention. The printed layer can be formed by printing on various substrates using the liquid ink composition, and is useful as an ink for gravure printing using a gravure printing plate such as an electronic engraving intaglio or an etching type intaglio plate, or for flexographic printing using a flexographic printing plate such as a resin plate, while excluding ink for an inkjet method in which ink is ejected from an inkjet nozzle without using a plate.

[0083] That is, in the case of inkjet ink, ink droplets ejected from a nozzle directly adhere to a substrate to form a printed item, whereas in the case of the liquid printing ink of the present invention, the printing ink is first adhered to and transferred to a printing plate or printing pattern, and then the ink alone is again adhered to the substrate and dried as necessary to form a printed item.

[0084] Examples of the film substrate include films and laminates made of thermoplastic resins such as polyethylene terephthalate (hereinafter sometimes referred to as PET), polyethylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polybutylene terephthalate, and polybutylene naphthalate, polyamides such as nylon 6, nylon 66, and nylon 46, polyhydroxycarboxylic acids such as polylactic acid, aliphatic polyester resins such as poly(ethylene succinate) and poly(butylene succinate), polyolefins such as polypropylene (CPP: non-oriented polypropylene film, OPP: biaxially oriented polypropylene film), polyethylene (LLDPE: low-density polyethylene film, HDPE: high-density polyethylene film), polyimide, polyarylate, polystyrene, polyacrylonitrile, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and mixtures thereof. Among these, films made of polyester, polyamide, polyethylene, and polypropylene can be preferably used.

[0085] It is also preferable to use a film formed from a material containing a biomass-derived component as the film substrate. Biomass films are sold by various companies, and for example, sheets such as those listed in the list of biomass certified products listed in the Japan Organics Resources Association can be used.

[0086] Specifically, a well-known film is made from biomass-derived ethylene glycol. Biomass-derived ethylene glycol is made from ethanol (biomass ethanol) produced from biomass. For example, biomass-derived ethylene glycol can be obtained by a method of producing ethylene glycol from biomass ethanol via ethylene oxide using a conventionally known method. Commercially available biomass ethylene glycol may also be used, and for example, biomass ethylene glycol commercially available from India Glycoal Limited can be suitably used.

[0087] Alternatively, products using biomass raw materials classified by the degree of biomass plastic as stipulated by ISO16620 or ASTM D6866 are also on the market. Radioactive carbon-14C exists in the atmosphere at a ratio of 1 in 1012 particles, and this ratio does not change even with atmospheric carbon dioxide, so this ratio does not change even in plants that fix this carbon dioxide through photosynthesis. For this reason, the carbon in plant-derived resins contains radioactive carbon-14C. In contrast, the carbon in fossil fuel-derived resins contains almost no radioactive carbon-14C. Therefore, by measuring the concentration of radioactive carbon-14C in the resin with an accelerator mass spectrometer, the proportion of plant-derived resin in the resin, i.e., the degree of biomass plastic, can be determined. Examples of plant-derived low-density polyethylene, which is a biomass plastic having a biomass plastic content of 80% or more, preferably 90% or more as specified by ISO16620 or ASTM D6866, include Braskem products under the trade names "SBC818", "SPB608", "SBF0323HC", "STN7006", "SEB853", and "SPB681", and films using these as raw materials can be preferably used.

[0088] For example, as an alternative to conventional polyethylene terephthalate films using petroleum-based raw materials, films containing biomass polyesters and biomass polyethylene terephthalate, which have biomass-derived ethylene glycol as the diol unit and fossil fuel-derived dicarboxylic acids as the dicarboxylic acid units, are known. The dicarboxylic acid unit of the biomass polyester uses a dicarboxylic acid derived from a fossil fuel. As the dicarboxylic acid, an aromatic dicarboxylic acid, an aliphatic dicarboxylic acid, and a derivative thereof can be used without limitation.

[0089] In addition to the above diol component and dicarboxylic acid component, the copolymer polyester may be a copolymer polyester containing a copolymer component as a third component, such as a bifunctional oxycarboxylic acid or at least one polyfunctional compound selected from the group consisting of a trifunctional or higher functional polyhydric alcohol, a trifunctional or higher functional polycarboxylic acid and / or its anhydride, and a trifunctional or higher functional oxycarboxylic acid, in order to form a crosslinked structure.

[0090] In addition, for example, as an alternative to conventional polyolefin films using petroleum-based raw materials, biomass polyolefin films such as biomass polyethylene films and biomass polyethylene-polypropylene films, which contain polyethylene resins made from biomass-derived ethylene glycol, are also known.

[0091] The polyethylene resin is not particularly limited except that ethylene glycol derived from biomass is used as part of the raw material. Examples of the polyethylene resin include ethylene homopolymers and copolymers of ethylene and α-olefins with ethylene as the main component (ethylene-α-olefin copolymers containing 90% by mass or more of ethylene units). These may be used alone or in combination of two or more.

[0092] The α-olefin constituting the copolymer of ethylene and α-olefin is not particularly limited, and examples thereof include α-olefins having 4 to 8 carbon atoms, such as 1-butene, 4-methyl-1-pentene, 1-hexene, and 1-octene. Known polyethylene resins, such as low-density polyethylene resin, medium-density polyethylene resin, and linear low-density polyethylene resin, can be used.

[0093] Among these, from the viewpoint of making it more difficult for damage such as holes or tears to occur even when films are rubbed against each other, linear low-density polyethylene resin (LLDPE) (a copolymer of ethylene and 1-hexene, or a copolymer of ethylene and 1-octene) is preferred, and linear low-density polyethylene resin having a density of 0.910 to 0.925 g / cm3 is more preferred.

[0094] In addition, films and sheets containing starch, a biomass raw material, or polylactic acid are also known. These can be selected and used appropriately depending on the application.

[0095] The biomass film may be a laminate of a plurality of biomass films, or may be a laminate of a conventional petroleum-based film and a biomass film.

[0096] These petroleum-based films and biomass films may be laminated with a vapor-deposited layer of a metal such as aluminum or a metal oxide such as silica or alumina, may use a metal foil, may be used in combination with a barrier film containing a gas barrier layer such as polyvinyl alcohol, an ethylene-vinyl alcohol copolymer, or vinylidene chloride, or may be coated with polyvinyl alcohol, etc. By using such a film, a laminate with higher barrier properties against water vapor, oxygen, alcohol, inert gases, volatile organic compounds (fragrances), etc. can be obtained.

[0097] These films may be unstretched or stretched, and the manufacturing method is not limited. As a stretching method, a resin is melt-extruded into a sheet by an extrusion film forming method or the like, and then simultaneous biaxial stretching or sequential biaxial stretching is generally performed. In the case of sequential biaxial stretching, a longitudinal stretching process is generally performed first, and then a transverse stretching process is generally performed. Specifically, a method of combining longitudinal stretching utilizing the speed difference between rolls and transverse stretching using a tenter is often used.

[0098] The thickness of the base film is not particularly limited, but is usually in the range of 1 to 500 μm. The film surface may be subjected to various surface treatments such as flame treatment and corona discharge treatment as necessary so that an adhesive layer without defects such as film breakage or repellency is formed.

[0099] The printing method can be a known printing method such as gravure printing or flexographic printing, but gravure printing is particularly preferred.

[0100] In the above printing method, i.e., after the printing ink is once adhered and transferred to a printing plate or a printing pattern, only the ink is adhered again to a substrate and, if necessary, dried or cured in an oven to fix it, thereby obtaining a printed matter. The film thickness of the printing ink formed by the gravure printing method or flexographic printing method using the liquid printing ink of the present invention is, for example, 10 μm or less, preferably 5 μm or less.

[0101] The printed matter of the present invention can be preferably used on a film substrate with the above-mentioned liquid ink composition as a front printing ink, a back printing ink, or a laminating ink. When used as a front printing ink, a separate overprint varnish layer can be provided. On the other hand, when used as a back printing ink, a separate anchor coat varnish layer can be provided.

[0102] In the printed matter, the order in which the color printed layer and the white printed layer are provided is not particularly limited, and they may be laminated in the order of film substrate / color printed layer / white printed layer, or in the order of film substrate / white printed layer / color printed layer. For example, the color printed layer can form a pattern using a colorant, and the second white printed layer and the third printed layer formed by a liquid printing ink containing a white pigment can be used as the background of the pattern.

[0103] It may further have other printed layers, which may have, for example, a white pigment, or, in the case of an overprint varnish, may not contain a colorant (white pigment or colored pigment).

[0104] (Laminate) The laminate of the present invention is obtained by laminating a plurality of substrates, and has a printed layer of the liquid printing ink of the present invention on at least one of the substrates. The substrates can be laminated by lamination with an adhesive or by extrusion lamination.

[0105] More specifically, the laminate has the following structure: (1) Base film 1 / printing layer / adhesive layer 1 / sealant film (2) Base film 1 / printed layer / adhesive layer 1 / metal-deposited unstretched film (3) Base film 1 / printed layer / adhesive layer 1 / metal-deposited stretched film (4) Transparent vapor-deposited stretched film / printed layer / adhesive layer 1 / sealant film (5) Base film 1 / printing layer / adhesive layer 1 / base film 2 / adhesive layer 2 / sealant film (6) Base film 1 / printed layer / adhesive layer 1 / metal-deposited stretched film / adhesive layer 2 / sealant film (7) Base film 1 / printed layer / adhesive layer 1 / transparent vapor-deposited stretched film / adhesive layer 2 / sealant film (8) Base film 1 / printed layer / adhesive layer 1 / metal layer / adhesive layer 2 / sealant film (9) Base film 1 / printing layer / adhesive layer 1 / base film 2 / adhesive layer 2 / metal layer / adhesive layer 3 / sealant film (10) Base film 1 / printed layer / adhesive layer 1 / metal layer / adhesive layer 2 / base film 2 / adhesive layer 3 / sealant film Examples include, but are not limited to, the above. The above "base film 1 / and printed layer" corresponds to the above printed matter having a white printed layer and a color printed layer on a film base. In the above configurations (1) to (10), a printed layer is provided on the surface of the base film 1 on the adhesive layer 1 side, but a printed layer may be provided on the surface (front surface) of the base film 1 opposite to the adhesive layer 1, or a printed layer may be provided on the base film 2.

[0106] Examples of the base film 1 used in the structure (1) include an OPP film, a PET film, and a nylon film (hereinafter also referred to as an Ny film). The base film 1 may be coated with a coating for the purpose of improving the gas barrier properties and the ink receptivity when a printing layer is provided, which will be described later. Examples of commercially available base films 1 with coatings include K-OPP films and K-PET films. Examples of sealant films include CPP films and LLDPE films.

[0107] The base film 1 used in the structures (2) and (3) can be an OPP film, a PET film, etc. As the metal-vapor-deposited unstretched film, a VM-CPP film obtained by depositing a metal such as aluminum on a CPP film can be used, and as the metal-vapor-deposited stretched film, a VM-OPP film obtained by depositing a metal such as aluminum on an OPP film can be used.

[0108] Examples of the transparent evaporated stretched film used in the structure (4) include films obtained by evaporating silica or alumina onto OPP film, PET film, nylon film, etc. For the purpose of protecting the inorganic evaporated layer of silica or alumina, a film having a coating applied onto the evaporated layer may be used. Examples of the sealant film include the same as those in the structure (1).

[0109] The base film 1 used in the structure (5) may be a PET film, etc. The base film 2 may be a nylon film, etc. The sealant film may be the same as that in the structure (1).

[0110] The base film 1 of the structure (6) may be the same as that of the structures (2) and (3). The metal-vapor-deposited stretched film may be a VM-OPP film or a VM-PET film in which a metal such as aluminum is vapor-deposited on an OPP film or a PET film. The sealant film may be the same as that of the structure (1).

[0111] The base film 1 in the structure (7) may be a PET film, etc. The transparent deposition stretched film may be the same as that in the structure (4). The sealant film may be the same as that in the structure (1).

[0112] The base film 1 in the structure (8) may be a PET film, etc. The metal layer may be an aluminum foil, etc. The sealant film may be the same as that in the structure (1).

[0113] In the structures (9) and (10), the base film 1 may be a PET film or the like. The base film 2 may be a nylon film or the like. The metal layer may be an aluminum foil or the like. The sealant film may be the same as that in the structure (1). (adhesive layer) The adhesive layer may be formed by a known adhesive for film lamination. When laminating by extrusion lamination, a known anchor coating agent for extrusion lamination may be used as an adhesive auxiliary. When a material having gas barrier properties is used as the adhesive or anchor coating agent, a laminate having particularly excellent barrier properties can be obtained.

[0114] Particularly preferred as an adhesive with excellent gas barrier properties is 3 g / m 2 The oxygen barrier property of the cured coating of the adhesive applied at (solid content) is 300cc / m 2 / day / atm or less, or water vapor barrier of 120g / m 2 / day. Commercially available products include the "PASLIM" series, such as PASLIM VM001 and PASLIM J350X, manufactured by DIC Corporation, and "Maxive" manufactured by Mitsubishi Gas Chemical Company.

[0115] The adhesive layer may be made of any known material without particular limitation, but preferably contains a cured product of a polyol and an isocyanate compound. When the polyol and / or isocyanate compound contains a biomass-derived component, a laminate with a high biomass content can be obtained, thereby reducing the environmental load.

[0116] In addition, the adhesive may contain an adhesion promoter, an acid anhydride, a compound having an oxygen scavenging function, a tackifier, a gas barrier adhesive stabilizer (antioxidant, heat stabilizer, ultraviolet absorber, etc.), a plasticizer, an antistatic agent, a lubricant, an antiblocking agent, a colorant, a crystal nucleating agent, etc. These various additives may be added in advance to either one or both of the polyol composition (A) and the polyisocyanate composition (B), or may be added when the polyol composition (A) and the polyisocyanate composition (B) are mixed.

[0117] The gas barrier adhesive used may be either a solvent-based or solventless type. When the gas barrier adhesive used is a solvent-based adhesive, the adhesive of the present invention is applied onto the surface of the printed layer printed on the first substrate using a roll such as a gravure roll, and the organic solvent is evaporated by heating in an oven or the like, and then the other substrate is laminated to obtain the laminate of the present invention. After lamination, it is preferable to perform an aging treatment. The aging temperature is preferably room temperature to 80°C, and the aging time is preferably 12 to 240 hours.

[0118] When the gas barrier adhesive used is a solventless type, the adhesive of the present invention, which has been preheated to about 40°C to 100°C, is applied to the printed layer surface of the first substrate using a roll such as a gravure roll, and the other substrate is immediately laminated to obtain the laminate of the present invention. After lamination, it is preferable to carry out an aging treatment. The aging temperature is preferably room temperature to 70°C, and the aging time is preferably 6 to 240 hours.

[0119] When the gas barrier adhesive is used as an adhesion promoter, the adhesion promoter of the present invention is applied to the printed layer surface printed on the first substrate using a roll such as a gravure roll, and the organic solvent is evaporated by heating in an oven or the like, and then the polymer material melted by an extruder is laminated to obtain the laminate of the present invention. As the polymer material to be melted, polyolefin resins such as low-density polyethylene resin, linear low-density polyethylene resin, and ethylene-vinyl acetate copolymer resin are preferred. The aging temperature is preferably room temperature to 70°C, and the aging time is preferably 6 to 240 hours.

[0120] The amount of gas barrier adhesive to be applied is adjusted as appropriate. For example, in the case of a solvent-based adhesive, the solid content is 1 g / m 2 More than 10g / m 2 Less than 2 g / m 2 More than 5g / m 2 Adjust the amount of adhesive applied so that it is as follows: For a solvent-free adhesive, the amount of adhesive applied is, for example, 1 g / m 2 More than 5g / m 2 Less than 1 g / m 2 More than 3g / m 2 The following is the result.

[0121] When using an adhesive as an adhesive auxiliary, the amount of application is adjusted appropriately. For example, 2 More than 2g / m 2 The solid content is as follows:

[0122] (Laminate other layers) The laminate of the present invention may be used alone or may further include other films or substrates. As the other substrates, in addition to the above-mentioned stretched film, unstretched film, and transparent vapor deposition film, porous substrates such as paper, wood, and leather can also be used. The adhesive used when bonding the other substrates may or may not be a gas barrier adhesive as described above.

[0123] <Packaging material> The printed matter and laminate of the present invention can be used as a multi-layer packaging material for the purpose of protecting food, medicines, etc. When used as a multi-layer packaging material, the layer structure can be changed depending on the contents, the environment of use, and the form of use.

[0124] The packaging material of the present invention can be obtained, for example, by using the laminate of the present invention, overlapping the surfaces of the sealant films of the laminate so that they face each other, and then heat-sealing the peripheral edge. Examples of the bag-making method include folding or overlapping the laminate of the present invention so that the surfaces of the inner layers (the surfaces of the sealant films) face each other, and heat-sealing the peripheral edge, for example, by a side seal type, a two-sided seal type, a three-sided seal type, a four-sided seal type, an envelope seal type, a grooving seal type, a pleated seal type, a flat bottom seal type, a square bottom seal type, a gusset type, or other heat seal type. The packaging material of the present invention can take various forms depending on the contents, the environment of use, and the form of use. Self-supporting packaging materials (standing pouches) and the like are also possible. Heat sealing can be performed by known methods such as bar seal, rotary roll seal, belt seal, impulse seal, high frequency seal, and ultrasonic seal.

[0125] The packaging material of the present invention is filled with contents through its opening, and the opening is heat-sealed to produce a product using the packaging material of the present invention. The use of the packaging material is not particularly limited, but it can be suitably used for food packaging, medicines, sanitary products, cosmetics, electronic materials, building materials, industrial materials, etc. Contents to be filled include confectioneries such as rice crackers, bean snacks, nuts, biscuits and cookies, wafer snacks, marshmallows, pies, semi-dried cakes, candies, and snacks, staple foods such as bread, snack noodles, instant noodles, dried noodles, pasta, aseptically packaged cooked rice, porridge, porridge, packaged rice cakes, and cereal foods, pickles, boiled beans, natto, miso, frozen tofu, tofu, nametake mushrooms, konjac, wild vegetable processed products, jams, peanut cream, salads, frozen vegetables, and potato processed products, livestock processed products such as hams, bacon, sausages, chicken processed products, and corned beef, and fish ham and sausages. Examples of the foodstuffs include processed fish products such as fish paste, fish paste products, kamaboko, nori, tsukudani, bonito flakes, shiokara, smoked salmon, and spicy cod roe, fruit pulp such as peaches, mandarin oranges, pineapples, apples, pears, and cherries, vegetables such as corn, asparagus, mushrooms, onions, carrots, radishes, and potatoes, prepared foods such as frozen and chilled prepared foods such as hamburger steaks, meatballs, seafood fries, gyoza, and croquettes, dairy products such as butter, margarine, cheese, cream, instant creamy powder, and infant formula, liquid seasonings, retort curry, and pet food. They can also be used as packaging materials for cigarettes, disposable hand warmers, medicines, supplements, infusion packs, and vacuum insulation materials. EXAMPLES

[0126] The present invention will be described more specifically with reference to examples. In the following, all "parts" and "%" are based on mass. In the present invention, the weight average molecular weight (converted into polystyrene) was measured by gel permeation chromatography (GPC) using an HLC8220 system manufactured by Tosoh Corporation under the following conditions. Separation columns: four TSKgel GMHHR-N columns manufactured by Tosoh Corporation. Column temperature: 40°C. Mobile phase: tetrahydrofuran manufactured by Wako Pure Chemical Industries, Ltd. Flow rate: 1.0 ml / min. Sample concentration: 1.0 wt%. Sample injection amount: 100 microliters. Detector: differential refractometer.

[0127] The amine value indicates the amount of potassium hydroxide (KOH) in mg that is equivalent to the amount of hydrochloric acid required to neutralize the amino groups contained in 1 g of polyurethane resin. The measurement method is to add and dissolve 30 mL of neutral ethanol to a precisely weighed sample (P grams), and then titrate the resulting solution with a 0.2 mol / L ethanolic hydrochloric acid solution (titer f). The point at which the color of the solution changes from green to yellow is considered the end point, and the titer (HmL) at this point is used to calculate the amine value according to the following formula 2. The sample refers to the polyurethane resin solution obtained in each synthesis example, and is calculated based on a solid content of 30% by mass. Amine value = (H x f x 0.2 x 56.108) / P / 0.3 [mgKOH / g] The viscosity was measured at 25° C. using a Tokimec B-type viscometer.

[0128] (Preparation of polyurethane resin solution P) A 1-liter four-neck flask equipped with a stirrer, a thermometer, a Dimroth-type reflux condenser, and a nitrogen gas inlet tube was charged with 264.20 parts of polyester polyol having a number average molecular weight of 5100 obtained from adipic acid and 3-methyl-1,5-pentanediol, and heated to 50°C while stirring with nitrogen gas. Then, 28.01 parts of isophorone diisocyanate was added, and the reaction was carried out at 90°C until the NCO%, which is the residual rate of isocyanate groups, reached 1.99%. After cooling, 157.34 parts of n-propyl acetate was added to obtain a urethane prepolymer solution (B2) having an isocyanate group at the end. Next, 10.96 parts of 1-amino-3-aminomethyl-3,5,5-trimethylcyclohexane, 1.37 parts of monoethanolamine, 411.00 parts of n-propyl acetate, 142.00 parts of n-propyl alcohol, and 449.55 parts of the urethane prepolymer solution (B2) were added to a 1-liter four-neck flask equipped with a stirrer, a thermometer, a Dimroth-type reflux condenser, and a nitrogen gas inlet tube, and the mixture was allowed to react at 45° C. for 4 hours to obtain a polyurethane resin solution (P) with a solid content of 30%, a weight average molecular weight of 48,000, and an amine value of 1.5 (mgKOH / g).

[0129] (Preparation of vinyl chloride / vinyl acetate copolymer resin solution V) A hydroxyl group-containing vinyl chloride-vinyl acetate copolymer resin (resin monomer composition by mass: vinyl chloride / vinyl acetate / vinyl alcohol=92 / 3 / 5, hydroxyl value (mgKOH)=64) used in combination with a polyurethane resin was prepared into a 15% solution in n-propyl acetate, and this was called the vinyl chloride-vinyl acetate resin solution (V).

[0130] (Acrylic resin) (Preparation of acrylic resin solution Ac) A solid acrylic resin (Dianal BR 50 manufactured by Mitsubishi Chemical Corporation) was dissolved with stirring in ethyl acetate to give a 40% solution, which was designated as an acrylic resin solution Ac.

[0131] (Adjustment of white kneaded base ink (W1)) A mixture of 25 parts of polyurethane resin solution P (solid content 30%), 10 parts of vinyl chloride-vinyl acetate resin solution V (solid content 15%), 35 parts of titanium oxide pigment R-780 (manufactured by Ishihara Sangyo Kaisha, Ltd.), 10 parts of isopropyl alcohol, and 20 parts of ethyl acetate was kneaded to prepare a white kneaded base ink (W1).

[0132] (Adjustment of white kneaded base ink (W2)) A mixture of 30 parts of polyurethane resin solution P (solid content 30%), 35 parts of titanium oxide pigment R-780 (manufactured by Ishihara Sangyo Kaisha, Ltd.), 10 parts of isopropyl alcohol, and 25 parts of ethyl acetate was milled to prepare a white milled base ink (W2).

[0133] (Adjustment of white kneaded base ink (W3)) A mixture of 45 parts of vinyl chloride-vinyl acetate resin solution V (solid content 15%), 35 parts of titanium oxide pigment R-780 (manufactured by Ishihara Sangyo Kaisha, Ltd.), 5 parts of isopropyl alcohol, and 15 parts of ethyl acetate was milled to prepare a white milled base ink (W3).

[0134] (Adjustment of white kneaded base ink (W4)) A mixture of 25 parts of acrylic resin solution Ac (solid content 40%), 10 parts of vinyl chloride-vinyl acetate resin solution V (solid content 15%), 35 parts of titanium oxide pigment R-780 (manufactured by Ishihara Sangyo Kaisha, Ltd.), 10 parts of isopropyl alcohol, and 20 parts of ethyl acetate was kneaded to prepare a white kneaded base ink (W4).

[0135] (Examples 1 to 5) The white kneaded base ink (W) was mixed with water, ethyl acetate, and various carboxylic acids or aqueous carboxylic acid solutions in the proportions shown in Table 1 to prepare liquid white inks.

[0136] (Comparative Examples 1 to 5) White liquid inks were prepared by mixing the white kneaded base ink (W) with water, ethyl acetate, and an acid solution in the ratios shown in Table 2. The acid solution was a mixed solution (solid content 5%) of various hydroxycarboxylic acids in isopropyl alcohol:ethyl acetate = 1:1.

[0137] In addition, in Comparative Example 5, no carboxylic acid or water was added. The liquid white inks of Examples 1 to 7 and Comparative Examples 1 to 5 obtained above were evaluated as follows. A evaluation was carried out.

[0138] (viscosity measurement) The viscosity of the liquid white ink was measured at a liquid temperature of 25°C using a Zahn Cup No. 4 manufactured by Rigo Co., Ltd. immediately after the ink was produced.

[0139] (viscosity stability) Each liquid white ink was placed in a glass bottle and stored at 50°C for 28 days. After that, the viscosity was measured at 25°C and the change in viscosity was evaluated compared to before and after storage in one liquid. The evaluation criteria were as follows:

[0140] (evaluation) ○: No viscosity change Viscosity change is less than 2 seconds △: Viscosity change is slight. Viscosity difference is 2 seconds or more but less than 5 seconds. ×: Viscosity change is very large. Viscosity difference is 5 seconds or more. (2-liquid stability) The liquid white ink was placed in a glass bottle, and 4% by mass of CVL No. 10 hardener (isocyanate hardener: manufactured by DIC) was added to 100% by mass of the ink. After storing at 25°C for one day, the viscosity was measured and the change in viscosity from before storage was evaluated. The evaluation criteria were as follows. (evaluation) ○: No viscosity change Viscosity change is less than 2 seconds △: Viscosity change is slight. Viscosity difference is 2 seconds or more but less than 5 seconds. ×: Viscosity change is large. Viscosity difference is 5 seconds or more. (Laminate strength) The liquid white inks of Examples 1 to 10 and Comparative Examples 1 to 8 obtained above were adjusted with ethyl acetate to 16 seconds (25°C) using a Zahn cup #3 (manufactured by Rigo Co., Ltd.), printed on a nylon film (ON-RT (15 μm) manufactured by Unitika Ltd., hereinafter referred to as NY) that had been corona-treated on one side using a gravure proofing machine equipped with a gravure plate with a plate depth of 35 μm, and dried at 40 to 50°C to obtain a print.

[0141] The printed surface of the obtained NY print was coated with a urethane-based dry lamination adhesive DIC Dry LX-703VL / KR-90 (DIC) using a dry laminator (DIC Engineering), and a non-oriented low-density polyethylene film (hereinafter, LLDPE: TUX-HC 60μm, Mitsui Chemicals Tohcello Co., Ltd.) was laminated onto the adhesive-coated surface. The laminate was then aged at 40°C for 5 days to obtain a laminate.

[0142] The obtained laminate was cut into a width of 15 mm and subjected to a 90° peel test at a pulling speed of 300 mm / min. (Blocking resistance test) The liquid white inks of Examples 1 to 10 and Comparative Examples 1 to 8 obtained above were adjusted with ethyl acetate to 16 seconds (25°C) using a Zahn cup #3 (manufactured by Rigo Co., Ltd.), printed on a nylon film (ON-RT (15 μm) manufactured by Unitika Ltd., hereinafter referred to as NY) that had been corona-treated on one side using a gravure proofing machine equipped with a gravure plate with a plate depth of 35 μm, and dried at 40 to 50°C to obtain a print.

[0143] Immediately after obtaining the print, the film was placed over the printed surface and the non-printed surface so that they were in contact with each other, and the film was then subjected to a pressure of 5 kgf / cm 2 After removing the samples, the state of ink transfer to the non-printed surface was visually evaluated using the following 5-point scale.

[0144] (Evaluation Criteria) ◎: Less than 5% of the ink was transferred to the non-printed surface. ○: Slight metastasis of less than 5% to 20% is observed. △: Metastasis is observed in 20% or more but less than 50%. ×: Metastasis of 50% or more is observed.

[0145] (Odor test) Immediately after producing a print similar to that obtained in the blocking resistance test, the print was placed in a glass bottle and sealed, and the bottle was heated in a thermostatic chamber at 40°C. After that, 15 subjects were asked to open the bottle, smell it, and evaluate the strangeness of the odor. The evaluation criteria are as follows. (evaluation) ○: Two or fewer people felt uncomfortable with the odor △: 3 to 5 people feel uncomfortable with the odor ×: Six or more people feel uncomfortable with the odor

[0146] [Table 1]

[0147] [Table 2]

[0148] [Table 3]

[0149] [Table 4]

[0150] From the above results, it was found that the liquid ink composition of the present invention, whether it is a one-component type that does not use a curing agent, or a two-component type that does use a curing agent, can produce inks that have excellent viscosity stability and laminate strength.

Claims

1. Binder resin (A), organic solvent (B), and carboxylic acid (C) with a boiling point of 150°C or less (excluding hydroxycarboxylic acid) A liquid ink composition comprising:

2. 2. The liquid ink composition according to claim 1, wherein the binder resin (A) contains at least one resin selected from the group consisting of polyurethane resins, vinyl chloride-vinyl acetate copolymer resins, maleic acid resins, cellulose resins, polyester resins, acrylic resins, and polyamide resins.

3. The liquid ink composition according to claim 1 or 2, which contains 0.05% by mass or less of acetic acid.

4. 3. The liquid ink composition according to claim 1, wherein the organic solvent (B) is at least one selected from the group consisting of ester-based solvents, alcohol-based solvents, and ketone-based solvents.

5. The liquid ink composition according to claim 1 or 2, further comprising a colorant (D).

6. The liquid ink composition according to claim 1 or 2, wherein the liquid ink composition contains less than 10% by mass of water.

7. The liquid ink composition according to claim 1 or 2, wherein the organic solvent (B) does not contain an aromatic organic solvent and / or a ketone-based solvent.

8. A printed matter obtained by printing the liquid ink composition according to claim 1 or 2.

9. A laminate having a printed layer formed by printing the liquid ink composition according to claim 1 or 2.

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