Liquid ink composition

Abstract

To provide a liquid ink composition that can be applied to a wide range of films, has high film adhesion and high laminate strength, and is suitable for various types of printing.SOLUTION: A liquid ink composition contains a polyurethane resin (A) having a polyol structure with neopentyl glycol and 2-methyl-1,3-propanediol as reaction materials. For the mass ratio of neopentyl glycol and 2-methyl-1,3-propanediol in the polyol structure, the neopentyl glycol has a higher content.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a liquid ink composition for gravure ink and flexographic ink for flexible packaging lamination, and in particular to a liquid ink composition for flexible packaging lamination that can exhibit excellent printability and adhesive performance on laminate substrates and that can be applied to various films coated with inorganic or organic barrier coating materials. [Background technology]

[0002] Liquid inks for lamination used mainly in the production of flexible packaging materials contain urethane resin or urethane urea resin as a main component. These urethane resins or urethane urea resins are produced using various reactive raw materials in order to impart their respective properties. For example, Patent Document 1 discloses a printing ink binder containing polyethylene glycol (hereinafter, referred to as PEG)-containing polyurethane resin and vinyl chloride-vinyl acetate copolymer resin as components, in which the PEG-containing polyurethane resin is obtained by reacting at least (A) a polyester polyol having a number average molecular weight of 1000 to 6000, (B) PEG, (C) a diisocyanate compound, and (D) a chain extender, and in which the content of (B) PEG is in the range of 1 to 40 parts by mass per 100 parts by mass of the PEG-containing polyurethane resin. Also, a printing ink binder is exemplified in which, in a polyurethane resin obtained by reacting (A) a polyester polyol having a number average molecular weight of 2,000 to 10,000, (B) an organic diisocyanate, and (C) a chain extender, (A) is a polyester polyol obtained by reacting (a) a glycol with (b) a dibasic acid, and at least 25 mass % of the glycol (a) is a glycol having an ether bond in the molecule (e.g., Patent Document 2). Furthermore, in an ink composition for flexible packaging laminates, the main components of which are a binder resin, a colorant, and an organic solvent other than aromatic organic solvents, the binder resin contains a polypropylene glycol (hereinafter referred to as PPG)-containing polyurethane resin and a vinyl chloride vinyl acetate copolymer resin having hydroxyl groups as essential components, the vinyl chloride vinyl acetate copolymer resin having hydroxyl groups has a hydroxyl value of 50 to 200 mg equivalent KOH / g, and the vinyl chloride content ratio per 100 parts by weight of the copolymer resin is 80 to 95 parts by weight (for example, Patent Document 3).

[0003] 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. For example, in non-aromatic solvent or ketone-based solvent-based liquid inks, from the standpoint of printability, there is a tendency to use acetates 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.

[0004] Various films such as polyethylene terephthalate, polypropylene, and nylon are used in the manufacture of flexible packaging materials, and printing inks are required to adhere to these various printing substrates. In recent years, there has been a trend toward an increase in high-performance films with various barrier properties as films used in film packages. These high-performance films have inorganic or organic barrier coating agents applied to their surfaces, and when these high-performance films are used as base rolls for gravure printing or flexographic printing, the adhesion between the base roll of film and the ink can often be impaired. These high-performance films are available in a wide variety of types depending on the industry and purpose, such as oxygen barriers that block air to prevent the contents from deteriorating for food and electronic components, and water vapor barriers that block water vapor. Many of these films are also technically undisclosed, and the current situation is that it is difficult to maintain adhesion compared to general film printing. Furthermore, aesthetic appeal is also required for printed matters on these flexible packaging materials, but problems that impair printability include poor transfer caused by the "plate clogging phenomenon" where ink clogs the cells of the gravure printing plate, the "plate fogging phenomenon" where ink is transferred to the film substrate as "fogging" in areas other than the image area where it cannot be scraped off with a doctor, tone jumps caused by a sudden thinning of the dots, and streaky unevenness in the printed area. In recent years, there has been an even greater demand for high design appeal for printed matters, and so further improvements are being sought in inks that have sufficient adhesion properties for the increasing variety of films while also having excellent printability. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. WO2015 / 068412 [Patent Document 2] JP 2010-270216 A [Patent Document 3] JP 2005-298618 A Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a liquid ink composition that can be applied to a wide variety of films, has excellent adhesion to the films and lamination strength, and is also excellent in various printability. [Means for solving the problem]

[0007] Means for Solving the Problems The present inventors have conducted intensive research to solve the above-mentioned problems, and as a result have found that the problems can be effectively solved by adopting a polyurethane resin (A) having a polyol structure in which neopentyl glycol and 2-methyl-1,3-propanediol are used as reaction raw materials, in which the mass ratio of neopentyl glycol to 2-methyl-1,3-propanediol in the polyol structure is higher than that of neopentyl glycol.

[0008] That is, the present invention relates to a liquid ink composition containing a polyurethane resin (A) having a polyol structure in which neopentyl glycol and 2-methyl-1,3-propanediol are reaction raw materials, in which the mass ratio of neopentyl glycol to 2-methyl-1,3-propanediol in the polyol structure is higher than that of neopentyl glycol.

[0009] The present invention further relates to a liquid ink composition containing a colorant and an organic solvent.

[0010] The present invention further relates to a liquid ink composition in which the polyol is a polyester polyol.

[0011] The present invention further relates to a liquid ink composition, in which the content of neopentyl glycol and 2-methyl-1,3-propanediol in the polyol that is the raw material for the polyester polyol is 80 mass % or more.

[0012] The present invention further relates to a liquid ink composition containing a vinyl chloride-vinyl acetate copolymer resin and / or soluble nitrocellulose.

[0013] Furthermore, the present invention relates to a liquid ink composition that does not contain an aromatic organic solvent and / or a ketone solvent as an organic solvent.

[0014] Furthermore, the present invention relates to a printed matter obtained by printing the liquid ink composition.

[0015] Furthermore, the present invention relates to a laminate comprising the printed matter. Effect of the Invention

[0016] According to the present invention, a liquid ink composition can be obtained which can be applied to a wide variety of films, and which is particularly excellent in adhesion to films, lamination strength, and printability. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] (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. 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 essentially contains a polyurethane resin (A) having a polyol structure in which neopentyl glycol (hereinafter referred to as "NPG") and 2-methyl-1,3-propanediol (hereinafter referred to as "MPO") are used as reactive raw materials, and in which the mass ratio of NPG to MPO in the polyol structure is higher than that of NPG.

[0019] (Polyurethane resin A) In the polyurethane resin (A), the printability can be improved by adjusting the mass ratio of NPG to MPO in the polyol structure so that NPG is more abundant. Specifically, the mass ratio of NPG:MPO is in the range of 51:49 to 99:1.

[0020] The polyol structure of the polyurethane resin (A) is produced using NPG and MPO as reaction raw materials, and may be produced using a polyester-type diol compound which is a condensation product of glycols containing NPG and MPO with a dibasic acid such as adipic acid, phthalic anhydride, isophthalic acid, or the like, or may be produced using NPG and MPO as they are.

[0021] The polyol of the polyurethane resin (A) is preferably one produced using a polyester type diol compound, that is, the polyol is preferably a polyester polyol. The polyester diol compound is obtained by reacting a glycol with a dibasic acid as described above, and the number average molecular weight thereof is preferably 1,000 to 6,000. As glycols serving as reaction raw materials for polyester diol compounds, glycols other than NPG and MPO, such as ethylene glycol, propylene glycol, 1,4-butanediol, etc., may be used in combination with NPG and MPO. From the viewpoint of improving printability, the higher the content ratio of NPG and MPO in the total mass of glycols serving as raw materials for polyester diol compounds, the better. That is, the higher the content ratio of NPG and MPO in the polyol serving as raw materials for polyester polyol of polyurethane resin (A), the better, specifically, it is preferably 80% by mass or more, more preferably 85% by mass or more, more preferably 90% by mass or more, more preferably 95% by mass or more, even more preferably 98% by mass or more, and most preferably 100% by mass.

[0022] The polyurethane resin (A) can be produced by a conventional method using the above-mentioned polyester polyol, a diisocyanate compound, a chain extender, a reaction terminator, and other materials.

[0023] As the polyol to be used in combination with the polyurethane resin (A) used in the liquid ink composition of the present invention as necessary, various known polyols generally used in the production of polyurethane resins can be used, and one or more types may be used in combination.For example, polyether polyols of polymers or copolymers of methylene oxide, ethylene oxide, tetrahydrofuran, etc. (1); 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 - Butylene diol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol, 1,2,4-butanetriol, sorbitol, pentaerythritol, and other saturated or unsaturated low molecular weight polyols (2); these low molecular weight polyols (2) and adipic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, spe polyester polyols (3) obtained by dehydration condensation or polymerization of polyvalent carboxylic acids such as phosphoric acid, azelaic acid, sebacic acid, trimellitic acid, and pyromellitic acid, or their anhydrides; polyester polyols (4) obtained by ring-opening polymerization of cyclic ester compounds, such as lactones such as polycaprolactone, polyvalerolactone, and poly(β-methyl-γ-valerolactone); polycarbonate polyols (5) obtained by reacting the low molecular weight polyols (2) with, for example, dimethyl carbonate, diphenyl carbonate, ethylene carbonate, and phosgene; polybutadiene glycols (6); glycols (7) obtained by adding ethylene oxide or propylene oxide to bisphenol A; and acrylic polyols (8) obtained by copolymerizing, for example, acrylic acid, methacrylic acid, or an ester thereof, one or more hydroxyethyl groups, hydroxypropyl acrylate, hydroxybutyl acrylate, or the like, or the corresponding methacrylic acid derivatives, in one molecule.

[0024] Of the polyester polyols (3), a high molecular weight diol obtained from a diol (glycol) and a dibasic acid can have up to 5 mol % of the diol substituted with the low molecular weight polyols (2) having three or more hydroxyl groups.

[0025] When NPG and / or MPO are contained as the combined polyol, the content of NPG and / or MPO contained in the combined polyol is also included in the mass of NPG and MPO in the polyol structure of the polyurethane resin (A).

[0026] The polyurethane resin (A) can be produced by a conventional method using NPG and MPO as they are, together with a diisocyanate compound, a chain extender, a reaction terminator, etc. In this case, it is preferable to synthesize the polyurethane resin (A) by using the above-mentioned combined polyol in addition.

[0027] The diisocyanate compound used in the polyurethane resin (A) in the ink composition for flexible packaging laminate of the present invention includes 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.

[0028] Examples of chain extenders used in the polyurethane resin (A) in the liquid ink composition of the present invention 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, di-2-hydroxypropylethylenediamine, etc. These chain extenders may be used alone or in combination of two or more. 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.

[0029] The polyurethane resin (A) in the liquid ink composition of the present invention can be produced, for example, by a two-stage method in which a polyester-type polyol compound using NPG and MPO as reaction raw materials, a co-used polyol, and a diisocyanate compound are reacted in a ratio such that the isocyanate groups are in excess to obtain a prepolymer having terminal isocyanate groups, and the prepolymer is reacted 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 that is commonly used as a solvent for 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 toluene, xylene, methylcyclohexane, or ethylcyclohexane; or a mixture of these solvents; or a one-stage method in which a polyester-type polyol compound using NPG and MPO as reaction raw materials, a co-used polyol, a diisocyanate compound, a chain extender, and / or a terminal blocking agent are reacted at once in a suitable solvent from among the above. Among these methods, the two-stage method is preferred to obtain a uniform polyurethane resin. When producing a polyurethane resin by the two-stage method, it is preferred to react the chain extender and / or the end-capping agent so that the total (equivalent ratio) of the amino groups is 1 / 0.9 to 1.3. When the equivalent ratio of the isocyanate group to the amino group is less than 1 / 1.3, the chain extender and / or the end-capping agent remain unreacted, and the polyurethane resin may turn yellow or emit an odor after printing. Furthermore, in recent years, from the viewpoint of the working environment, it is more preferred not to use aromatic solvents such as toluene and xylene or ketone solvents.

[0030] The weight average molecular weight of the polyurethane resin (A) 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 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, whereas if it exceeds 100,000, the viscosity of the resulting ink composition tends to be high and the gloss of the printed film tends to be reduced. The content of the polyurethane resin (A) used in the liquid ink composition of the present invention in the ink is preferably 4% by mass or more relative to the total mass of the ink from the viewpoint of sufficient adhesion of the ink to the printed material, and 40% by mass or less from the viewpoint of appropriate ink viscosity and work efficiency during ink production and printing, and more preferably in the range of 6 to 30% by mass. In addition, the lower limit of the solids mass ratio in the ink is preferably 10% by mass, more preferably 15% by mass, more preferably 20% by mass, and even more preferably 25% by mass. In addition, the upper limit of the solids mass ratio in the ink is preferably 95% by mass, more preferably 90% by mass, more preferably 80% by mass, and even more preferably 75% by mass.

[0031] (Other binder resins) The liquid ink composition of the present invention may contain, in addition to the polyurethane resin (A), other binder resins that can be used in combination in the technical field of liquid inks. Examples of resins that can be used in combination with the liquid ink composition as necessary include vinyl chloride-vinyl acetate copolymer resins, chlorinated polyolefin resins, ethylene-vinyl acetate copolymer resins, vinyl acetate resins, polyamide resins, acrylic resins, polyester resins, alkyd resins, polyvinyl chloride resins, rosin-based resins, rosin-modified maleic acid resins, ketone resins, cyclized rubbers, chlorinated rubbers, butyral, petroleum resins, cellulose-based resins, and urethane resins other than the polyurethane resin (A). The co-used resin may be used alone or in combination of two or more kinds. The content of the co-used resin is preferably 0.1 to 25% by mass, more preferably 2 to 15% by mass, based on the total mass of the ink. Among these, it is preferable to contain a vinyl chloride-vinyl acetate copolymer resin, a chlorinated polyolefin resin, a rosin-modified maleic acid resin, or a cellulose-based resin.

[0032] (Vinyl chloride vinyl acetate copolymer resin) In the liquid ink composition of the present invention, the addition of the vinyl chloride / vinyl acetate copolymer resin improves blocking resistance and retort resistance. In particular, when the vinyl chloride / vinyl acetate copolymer resin (B) contains a hydroxyl group, hot water resistance such as retort resistance is remarkably improved.

[0033] The vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group preferably has a hydroxyl value of 50 to 200 mgKOH / g and a content of vinyl chloride in the copolymer resin of 80 to 95 mass %.

[0034] The vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group used in the liquid ink composition of the present invention can be obtained by two methods. One is obtained by copolymerizing vinyl chloride monomer, vinyl acetate monomer, and vinyl alcohol in an appropriate ratio. The other is obtained by copolymerizing vinyl chloride and vinyl acetate, and then partially saponifying the vinyl acetate. The vinyl chloride-vinyl acetate copolymer resin having a hydroxyl group has a resin coating property and a resin dissolution behavior that are determined by the monomer ratio of vinyl chloride, vinyl acetate, and vinyl alcohol. That is, vinyl chloride imparts toughness and hardness to the resin coating, vinyl acetate imparts adhesion and flexibility, and vinyl alcohol imparts good solubility in polar solvents.

[0035] When the liquid ink is used as a laminate ink for flexible packaging, it is necessary to satisfy all of the performances, including adhesion, blocking resistance, lamination strength, boiling and retorting suitability, and printability, so there is an appropriate monomer ratio for the vinyl chloride and vinyl acetate copolymer resin having a hydroxyl group. That is, 80 to 95 parts by mass of vinyl chloride is preferable for 100 parts by mass of vinyl chloride and vinyl acetate copolymer resin having a hydroxyl group. If it is less than 80 parts by mass, the toughness of the resin film tends to be inferior and blocking resistance tends to decrease. If it exceeds 95 parts by mass, the resin film tends to be too hard and adhesion tends to decrease. In addition, the hydroxyl value obtained from vinyl alcohol is preferably 50 to 200 mgKOH / g. If it is less than 50 mgKOH / g, the solubility in polar solvents is poor and printability is likely to be poor. If it exceeds 200 mgKOH / g, water resistance tends to decrease and boiling and retorting suitability tends to be poor. The vinyl chloride-vinyl acetate copolymer resin is contained in an amount of 0.1 to 10 mass %, and preferably 0.2 to 5 mass %, based on 100 mass % of the ink.

[0036] (Chlorinated polyolefin resin) The chlorinated polyolefin resin usable in the present invention is not particularly limited as long as it is a polyolefin resin in which at least a part of hydrogen atoms is replaced by chlorine atoms. The weight average molecular weight of the chlorinated polyolefin is preferably 5,000 to 100,000, more preferably 5,000 to 70,000, and even more preferably 7,000 to 50,000. In addition, the chlorine content of the chlorinated polyolefin resin is preferably 25 to 45% by mass in order to improve adhesion to the substrate. In addition, from the viewpoint of solubility in organic solvents, the chlorine content is more preferably 26 to 43% by mass. Here, the chlorine content refers to the mass % of chlorine atoms contained in 100% by mass of the chlorinated polyolefin resin. In addition, from the viewpoint of balance with blocking resistance, the chlorinated polyolefin resin is contained in 100% by mass of the ink in 0.1 to 10% by mass, preferably 0.2 to 5% by mass.

[0037] Chlorinated polyolefin resins have flexible alkyl groups as branched structures, so they are flexible even at low temperatures and contribute to improving substrate adhesion. The structure of the polyolefin resin in the chlorinated polyolefin resin is not particularly limited. For example, resins containing homopolymers or copolymers of α-olefin-based unsaturated hydrocarbons such as polypropylene, poly-1-butene, and poly-4-methyl-1-pentene are preferred. Among these, those containing a polypropylene structure (i.e., a chlorinated polypropylene structure) are particularly preferred.

[0038] (Cellulose-based resin) Examples of the cellulose resin include cellulose acetate propionate, cellulose acetate butyrate, other cellulose ester resins, nitrocellulose (also called nitrocellulose), hydroxyalkylcellulose, and carboxyalkylcellulose. The cellulose ester resin preferably has an alkyl group, and examples of the alkyl group include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, and hexyl groups, and the alkyl group may further have a substituent. Among the above, the cellulose resin is preferably cellulose acetate propionate, cellulose acetate butyrate, and nitrocellulose. The molecular weight is preferably 5,000 to 200,000 in weight average molecular weight, and more preferably 10,000 to 50,000. In addition, the glass transition temperature is preferably 120°C to 180°C. When the polyurethane resin (A) of the present invention is used in combination, it is expected that the blocking resistance, scratch resistance, and other ink film properties are improved. 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.

[0039] The use of nitrocellulose (nitrocellulose) provides high dispersibility in pigments, and therefore is particularly suitable for use as a coating agent for surface printing, as it can improve the strength of the printing ink coating film. The nitrocellulose (nitrocellulose) preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 30 to 500, and more preferably has a nitrogen content of 10 to 13% by mass and an average degree of polymerization of 45 to 290. The amount of the cellulose resin added is preferably 0.1 to 25% by mass, and more preferably 0.3 to 10% by mass, based on the total amount of the ink.

[0040] (Coloring agent) The colorant used in the liquid ink composition of the present invention may be either a colored pigment or a white pigment. If these pigments are not added, the composition can be used as an overcoat varnish.

[0041] Colorants used in the liquid ink composition of the present invention include organic pigments and dyes that are used in general inks, paints, recording materials, etc. Examples of organic pigments include azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethineazo-based, dicepyrrolopyrrole-based, isoindoline-based pigments, etc.

[0042] The color index names are: CIPigment Yellow 1, 3, 12, 13, 14, 17, 42, 74, 83; CI Pigment Orange 16; CIPigment Red 5, 22, 38, 48:1, 48:2, 48:4, 49:1, 53:1, 57:1, 63:1, 81, 101; CIPigment Violet 19, 23; CIPigment Blue 23, 15:1, 15:3, 15:4, 17:1, 18, 27, 29 CIPigment Green 7, 36, 58, 59; CI Pigment Black 7; CI Pigment White 4, 6, 18, etc.

[0043] It is preferable to use CI Pigment Blue 15:3 (copper phthalocyanine) for indigo ink, CI Pigment Yellow 83 for yellow ink from the viewpoints of cost and light resistance, and CI Pigment Red 57:1 for crimson ink. It is preferable to use carbon black for black ink, aluminum for gold and silver ink, and mica for pearl ink from the viewpoints of cost and coloring power. Aluminum is in powder or paste form, but it is preferable to use it in paste form from the viewpoints of handling and safety, and whether to use leafing or non-leafing is appropriately selected from the viewpoints of brightness and density.

[0044] Examples of white pigments that can be used in the liquid ink composition of the present invention include titanium oxide, zinc sulfide, white lead, zinc oxide, lithopone, antimony white, basic lead sulfate, basic lead silicate, barium sulfate, calcium carbonate, gypsum, and silica. The average particle size of the pigment is preferably in the range of 10 to 200 nm, and more preferably about 50 to 150 nm. The amount of the color pigment added is preferably within a range of 1 to 20% by mass of the total amount of the ink in order to obtain sufficient image density and light resistance of the printed image.

[0045] (Organic solvent) As the organic solvent (E) used in the liquid ink composition of the present invention, 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. 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-based solvents.

[0046] In the present invention, if necessary, the composition may further contain a combined resin, 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, etc. For example, if an appropriate amount of silica is added as the extender pigment, the abrasion resistance tends to be further improved.

[0047] Specifically, the liquid ink composition of the present invention is prepared by mixing the polyurethane resin (A) and a resin, such as a vinyl chloride-vinyl acetate copolymer resin or a chlorinated polyolefin, which is used in combination as required, in advance with various organic solvents such as ethyl acetate, methyl ethyl ketone, toluene, and IPA. In the case of a varnish composition, the varnish composition can be obtained by adding various additives while stirring the solution with a dispersion stirrer and further stirring. In the case of an ink composition, the ink composition can be obtained by adding a colorant and dispersing it sufficiently.

[0048] When a colorant is used in the liquid ink composition of the present invention, the hues are determined according to the type of colorant used, and there are five process basic colors, yellow, red, indigo, black, and white, and three process gamut colors, red (orange), grass (green), and purple. 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. Ink for boil retort printing is appropriately selected in consideration of the migration property and heat resistance of the pigment. The base ink of each hue is diluted with a diluting solvent to a viscosity and concentration suitable for gravure printing or flexographic printing, and is supplied to each printing unit alone or mixed.

[0049] 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. 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.

[0050] 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. 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 pigment in the ink.

[0051] Of the plastic films that can be used, polyester resin films are particularly preferred, while the liquid ink composition of the present invention is particularly useful for polypropylene films, which tend to have poor adhesion, and can also be used widely on various high-performance films, such as other polypropylene, nylon, and polyethylene resin films, whose surfaces are coated with inorganic or organic barrier coating materials. EXAMPLES

[0052] The present invention will be described more specifically with reference to examples. In the following, "parts" and "%" are all based on mass. The measurements in the present invention were carried out as follows.

[0053] <Acid value measurement method> Approximately 20 g of sample was precisely weighed and placed in an Erlenmeyer flask, and 30 ml of a toluene / methanol (volume ratio: toluene / methanol = 7 / 3) mixture was added to dissolve it. Phenolphthalein test solution was added as an indicator, and the solution was titrated with 0.1 mol / l alcoholic potassium hydroxide solution until it turned a pale pink color. The acid value (mgKOH / g) was calculated using the following formula (1). (Formula 1) Acid value (mgKOH / g)=(5.611×V×F) / S Where S is the amount of sample taken (g) V: Titration volume (ml) of 0.1 mol / l alcoholic potassium hydroxide solution F: Potency of 0.1 mol / l alcoholic potassium hydroxide solution

[0054] <Method for measuring hydroxyl value> Approximately 5 g of sample was precisely weighed and placed in an Erlenmeyer flask, and 25 ml of acetylating agent (a mixture of acetic anhydride and pyridine at a volume ratio of 1:19) was added and stirred at 100°C for 1 hour. Then 10 ml of ion-exchanged water was added and cooled to room temperature. After cooling, 100 ml of acetone, 10 ml of n-butanol, and phenolphthalein test solution were added as indicators, and the solution was titrated with 0.5 mol / l alcoholic potassium hydroxide solution until it turned a pale pink color. The hydroxyl value was calculated using the following formula (2). (Equation 2) Hydroxyl value (mgKOH / g) = [{(BT) x F x 28.05} / S] + D Where S is the amount of sample taken (g) T: Titration volume (ml) of 0.5 mol / l alcoholic potassium hydroxide solution B: Titration volume (ml) of 0.1 mol / l alcoholic potassium hydroxide solution in a blank experiment F: Potency of 0.5 mol / l alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

[0055] <Method for measuring amine value> Approximately 40 g of sample was precisely weighed and placed in an Erlenmeyer flask, and 200 ml of a toluene / methanol (volume ratio: toluene / methanol = 7 / 3) mixture was added to dissolve it. Bromophenol blue test solution was added as an indicator, and the solution was titrated with 0.1 mol / l hydrochloric acid solution until the solution changed from blue to yellow. The amine value was calculated using formula (3). (Equation 3) Amine value = (V x F x 0.1 x 56.11) / S Where S is the amount of sample taken (g) V: Titration volume (ml) of 0.1 mol / l hydrochloric acid solution F: Potency of 0.1 mol / l hydrochloric acid solution

[0056] <Method of measuring number average molecular weight and weight average molecular weight> The number average molecular weight (polystyrene equivalent) and the weight average molecular weight (polystyrene equivalent) were measured using a Tosoh Corporation HLC8220 system under the following conditions. Separation column: TSKgelGMH manufactured by Tosoh Corporation HR -N 4 pieces used Column temperature: 40℃ Mobile phase: Tetrahydrofuran (Wako Pure Chemical Industries, Ltd.) Flow rate: 1.0ml / min Sample concentration: 1.0% by weight Sample injection volume: 100 microliters Detector: Differential refractometer.

[0057] <Method of measuring viscosity> The viscosity was measured at 25° C. using a Tokimec B-type viscometer.

[0058] (Synthesis of polyester polyol) [Synthesis Example 1-1] A round-bottom flask equipped with a stirring rod, a temperature sensor, a rectifying tube and a nitrogen gas inlet tube was charged with 314.4 parts of neopentyl glycol (hereinafter also abbreviated as NPG), 169.2 parts of 2-methyl-1,3-propanediol (hereinafter also abbreviated as MPO), 684.9 parts of adipic acid, and 0.07 parts of tetraisopropyl titanate, and a dehydration condensation reaction was carried out at 220 ° C. under a nitrogen stream. The reaction was stopped when the acid value reached 0.5 mg KOH / g, and polyester polyol P1 was obtained. The obtained polyester polyol P1 had a hydroxyl value of 24 mg KOH / g and an acid value of 0.5 mg KOH / g.

[0059] [Synthesis Example 1-2] In a round-bottom flask equipped with a stirring rod, a temperature sensor, a rectifying tube and a nitrogen gas inlet tube, 244.0 parts of NPG, 234.3 parts of MPO, 691.9 parts of adipic acid and 0.07 parts of tetraisopropyl titanate were charged and subjected to a dehydration condensation reaction at 220°C under a nitrogen stream. The reaction was stopped when the acid value reached 0.5mgKOH / g, and polyester polyol P2 was obtained. The obtained polyester polyol P2 had a hydroxyl value of 24mgKOH / g and an acid value of 0.5mgKOH / g.

[0060] [Synthesis Examples 1-3] A round-bottom flask equipped with a stirring rod, a temperature sensor, a rectifying tube and a nitrogen gas inlet tube was charged with 218.8 parts of NPG, 194.3 parts of MPO, 72.8 parts of 3-methyl-1,5-pentanediol (hereinafter also abbreviated as MPD), 681.8 parts of adipic acid, and 0.07 parts of tetraisopropyl titanate, and a dehydration condensation reaction was carried out at 220 ° C. under a nitrogen stream. The reaction was stopped when the acid value became 0.5 mg KOH / g, and polyester polyol P3 was obtained. The obtained polyester polyol P3 had a hydroxyl value of 24 mg KOH / g and an acid value of 0.5 mg KOH / g.

[0061] [Comparative Synthesis Example 1-1] A round-bottom flask equipped with a stirring rod, a temperature sensor, a rectifying tube and a nitrogen gas inlet tube was charged with 214.3 parts of NPG, 261.8 parts of MPO, 694.8 parts of adipic acid and 0.07 parts of tetraisopropyl titanate, and a dehydration condensation reaction was carried out at 220°C under a nitrogen stream. The reaction was stopped when the acid value reached 0.5mgKOH / g, and polyester polyol P4 was obtained. The obtained polyester polyol P4 had a hydroxyl value of 24mgKOH / g and an acid value of 0.5mgKOH / g.

[0062] [Comparative Synthesis Example 1-2] A round-bottom flask equipped with a stirring rod, a temperature sensor, a rectifying tube and a nitrogen gas inlet tube was charged with 193.7 parts of NPG, 217.8 parts of MPO, 72.5 parts of MPD, 684.3 parts of adipic acid and 0.07 parts of tetraisopropyl titanate, and a dehydration condensation reaction was carried out at 220°C under a nitrogen stream. The reaction was stopped when the acid value reached 0.5mgKOH / g, and polyester polyol P5 was obtained. The obtained polyester polyol P5 had a hydroxyl value of 24mgKOH / g and an acid value of 0.5mgKOH / g.

[0063] [Synthesis Example 2-1] 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 (P1) and 11.0 parts of isophorone diisocyanate were charged, and reacted at 90°C for 10 hours under a nitrogen stream to produce a urethane prepolymer, and then 90.8 parts of ethyl acetate was 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 4.84 parts of isophorone diamine, 0.35 parts of di-n-butylamine, 85.4 parts of ethyl acetate and 94.9 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a polyurethane resin solution A1. The obtained polyurethane resin solution A1 had a resin solid concentration of 30.0% by mass, a resin solid amine value of 1.5 mgKOH / g, and a weight average molecular weight of the resin solid of 77,000.

[0064] [Synthesis Example 2-2] 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 (P2) and 11.0 parts of isophorone diisocyanate were charged, and reacted at 90 ° C for 10 hours under a nitrogen gas flow to produce a urethane prepolymer, and then 90.8 parts of ethyl acetate was added to the mixture to produce a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 4.84 parts of isophorone diamine, 0.35 parts of di-n-butylamine, 85.4 parts of ethyl acetate and 94.9 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45 ° C for 5 hours to obtain a polyurethane resin solution A2. The obtained polyurethane resin solution A2 had a resin solid concentration of 30.0 mass%, a resin solid amine value of 1.5 mg KOH / g, and a weight average molecular weight of the resin solid of 77,000.

[0065] [Synthesis Example 2-3] 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 (P3) and 11.0 parts of isophorone diisocyanate were charged, and reacted at 90°C for 10 hours under a nitrogen stream to produce a urethane prepolymer, and then 90.8 parts of ethyl acetate was added to the mixture to produce a uniform solution of the urethane prepolymer. Next, the urethane prepolymer solution was added to a mixture consisting of 4.84 parts of isophorone diamine, 0.35 parts of di-n-butylamine, 85.4 parts of ethyl acetate and 94.9 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a polyurethane resin solution A3. The obtained polyurethane resin solution A3 had a resin solid concentration of 30.0% by mass, a resin solid amine value of 1.5 mgKOH / g, and a weight average molecular weight of the resin solid of 77,000.

[0066] [Comparative Synthesis Example 2-1] 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 polyester polyol (P4) and 11.0 parts of isophorone diisocyanate, and reacted for 10 hours at 90°C under a nitrogen stream to produce a urethane prepolymer, and then 90.8 parts of ethyl acetate was 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 4.84 parts of isophorone diamine, 0.35 parts of di-n-butylamine, 85.4 parts of ethyl acetate and 94.9 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a polyurethane resin solution H1. The obtained polyurethane resin solution H1 had a resin solid concentration of 30.0 mass%, a resin solid amine value of 1.5 mgKOH / g, and a weight average molecular weight of the resin solid of 77,000.

[0067] [Comparative Synthesis Example 2-2] 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 polyester polyol (P5) and 11.0 parts of isophorone diisocyanate, and reacted for 10 hours at 90°C under a nitrogen stream to produce a urethane prepolymer, and then 90.8 parts of ethyl acetate was 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 4.84 parts of isophorone diamine, 0.35 parts of di-n-butylamine, 85.4 parts of ethyl acetate and 94.9 parts of isopropyl alcohol, and the mixture was stirred and reacted at 45°C for 5 hours to obtain a polyurethane resin solution H2. The obtained polyurethane resin solution H2 had a resin solid concentration of 30.0% by mass, a resin solid amine value of 1.5 mgKOH / g, and a weight average molecular weight of the resin solid of 77,000.

[0068] [Preparation Example 1: 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 polyurethane resin was prepared into a 15% solution in ethyl acetate, and this was designated as vinyl chloride-vinyl acetate resin solution V.

[0069] [Preparation Example 2: Preparation of chlorinated polyolefin solution PP] Nippon Paper Industries Co., Ltd.'s "Superchlorine 814HS" was dissolved in ethyl acetate to prepare a 30% solids solution, which was used as a chlorinated polyolefin solution (PP).

[0070] [Preparation Example 3: Preparation of Maleic Acid Resin Solution M] Maleic acid resin solution M was prepared by mixing 20% ​​IPA, 50% ethyl acetate, and 30% SMA 3000P manufactured by Tomoe Engineering Co., Ltd. to form a 30% solids solution and thoroughly stirring the mixture.

[0071] (Preparation of Cellulose Acetate Propionate CAP482-0.5 Resin Solution Ca) 80 parts of a mixture of isopropyl alcohol / ethyl acetate / normal propyl acetate / methylcyclohexane (weight ratio of 25 / 25 / 13 / 10) was added to 20 parts of cellulose acetate propionate CAP482-0.5 (manufactured by Eastman Chemical Co.) and thoroughly mixed to prepare a cellulose ester resin solution Ca.

[0072] [Example 1] A mixture consisting of 25 parts of polyurethane resin solution A1 (solid concentration 30.0 mass%), 1.5 parts of vinyl chloride vinyl acetate copolymer resin solution V (solid content 15%), 2 parts of chlorinated polyolefin resin solution PP (solid content 30%), 0.5 parts of maleic acid resin solution M (solid content 30%), 36 parts of titanium oxide pigment R-780 (manufactured by Teika Co., Ltd.), 14 parts of ethyl acetate, 8 parts of isopropyl alcohol, and 13 parts of N-propyl acetate, totaling 100 parts, was kneaded using a Dyno Mill (manufactured by Willy & Bachofenon Co., Ltd.) to prepare a liquid printing white ink of the present invention.

[0073] [Examples 2 to 7, Comparative Examples 1 and 2] Using the compositions shown in Tables 1 to 2, liquid printing inks were prepared in the same manner as in Example 1 for Examples 2 to 7 and Comparative Examples 1 to 6.

[0074] [Method of manufacturing film prints] The viscosity of the obtained printing ink was adjusted to 16 seconds (25°C) using ethyl acetate in a Zahn cup #3 (manufactured by Rigo Co., Ltd.), and printed on various films (OPP, PET, NY, transparent deposition film) and corona-treated polyester film (hereinafter referred to as PET film: manufactured by Toyobo Co., Ltd., product name Ester E5102, thickness 12 μm) shown in Tables 1 to X 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 prints. The obtained prints were evaluated for adhesion to various films, lamination strength in a PET film / aluminum / unstretched polypropylene film (hereinafter referred to as R-CPP: Toray Synthetic Films Co., Ltd. ZK-75 50μm) configuration, and printability after retort treatment. The results are shown in Tables 1 and 2. The evaluations were performed using the following test methods.

[0075] 1) Adhesion (various films) The above printed matter was left for one day, and then cellophane tape (12 mm wide, made by Nichiban) was applied to the printed surface, which was then quickly peeled off and the appearance of the printed film was visually evaluated. The evaluation criteria were as follows: 5: The printing film did not peel off at all. 4: 90% or more of the printed film remained on the film. 3: 80% or more but less than 90% of the printed film remained on the film. 2: 60% or more but less than 80% of the printed film remained on the film. 1: Less than 60% of the printed film remained on the film.

[0076] 2) Measurement of laminate strength The above PET film print is coated with a urethane-based dry lamination adhesive, Dick Dry LX-500 / KW-75 (DIC), at a coating weight of 3.5 g / m 2After drying, an aluminum foil (hereinafter, AL: Toyo Aluminum Industrial Co., Ltd., Aluminum Foil C, 15 μm) was laminated using a dry laminator (DIC Engineering Co., Ltd.) to obtain a two-layer laminate 1. Next, an adhesive was similarly applied onto the AL of the laminate 1, and a non-oriented polypropylene film (hereinafter, R-CPP: Toray Synthetic Films Co., Ltd., ZK-75, 50 μm) was laminated thereon, and aging was performed at 40° C. for 5 days to obtain a three-layer composite laminate 2. Thereafter, the laminate strength was measured. The larger the value, the stronger the laminate strength. 5: The laminate strength is 400 (g / 15 mm) or more and is sufficiently strong. 4: The laminate strength is between 300 and 400 (g / 15 mm), which is slightly insufficient. 3: The laminate strength is between 200 and 300 (g / 15 mm) and is insufficient. 2: The laminate strength is between 100 and 200 (g / 15 mm) and is insufficient. 1: The laminate strength is less than 100 and is insufficient.

[0077] 3) Printability test: Transferability The degree of ink transfer (degree of blurring) to the printed portion of the PET film print was evaluated. The evaluation was performed with a gravure plate circumference of 600 mmφ and a printing speed of 300 m / min. 5: No blurring 4: Very slight blurring 3: Some blurring occurs, practical range 2: Blurring is clearly visible 1: There is a lot of smearing

[0078] 4) Printability test: Plate fogging The degree of staining (plate fogging) of the non-printed parts of the PET film prints was evaluated. 5: No print stains 4: Print stains are very slightly visible 3: Print stains: Slightly visible, within practical range 2: Print stains are noticeable 1: Severe print stains

[0079] 5) Printability test: streaky stains The occurrence of streaky ink stains (unevenness) on the printed portion of the PET film print was evaluated. 5: No streaks 4: Very slight streak stains 3: Streaky stains, slightly visible, practical range 2: Streaky stains are noticeable 1: Severe streaking

[0080] 5) Printability test: Tone jump In the printed portion of the PET film print, the occurrence of tone jumps caused by thinning of dots and sudden changes in color was evaluated. 5: No Tone Jump 4: Tone jump: Very slightly noticeable 3: Tone jump: Slightly noticeable, within practical range 2: Tone jump is evident 1: Tone jump: severe

[0081] Tables 1 and 2 show the formulations of each liquid printing ink and the evaluation results.

[0082] [Table 1]

[0083] [Table 2]

[0084] The abbreviations in the table are as follows: OPP: Toyobo P2161 (20μm) PET: Toyobo Co., Ltd. E5100 (12 μm) NY: ON-RT (15μm) manufactured by Unitika Ltd. Transparent deposition film: IB-PET-PUB (12μm) manufactured by Dai Nippon Printing Co., Ltd.

[0085] FASTGEN Blue LA5380: Phthalocyanine blue pigment, manufactured by DIC Corporation Silica: Silica 350D, average particle size 3.9 μm Moreover, blank spaces indicate that no compound has been added.

[0086] In the examples, the adhesiveness to the film and the lamination strength were high, and the printability was also excellent. [Industrial Applicability]

[0087] The liquid ink composition of the present invention can be used for a wide range of industrial products, such as food packaging materials, sanitary products, cosmetics, and electronic components.

Claims

1. The polyurethane resin (A) has a polyester polyol structure in which neopentyl glycol and 2-methyl-1,3-propanediol are reacted as raw materials, and does not contain a polyether polyol as a reactant, A liquid ink composition comprising a polyurethane resin (A) in which the mass ratio of neopentyl glycol to 2-methyl-1,3-propanediol in the polyester polyol structure is higher than that of neopentyl glycol.

2. The liquid ink composition according to claim 1, further comprising a colorant and an organic solvent.

3. 3. The liquid ink composition according to claim 1, wherein the content ratio of neopentyl glycol and 2-methyl-1,3-propanediol in the raw materials of the polyester polyol is in the range of 80 mass % or more.

4. 4. The liquid ink composition according to claim 1, further comprising at least one resin selected from the group consisting of vinyl chloride-vinyl acetate copolymer resins, chlorinated polyolefins, maleic acid resins and / or cellulose-based resins.

5. 5. The liquid ink composition according to claim 1, wherein the organic solvent does not include an aromatic organic solvent and / or a ketone solvent.

6. A printed matter obtained by printing the liquid ink composition according to any one of claims 1 to 5.

7. A laminate having a printed layer formed by printing the liquid ink composition according to any one of claims 1 to 5.

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