Method for producing polyurethane urea resin solution and method for producing printing ink composition for laminate for flexible packaging

Abstract

To provide a method for producing a polyurethane urea resin solution which does not cause turbidity of the polyurethane urea resin solution used for an ink composition, generation of insoluble matter, and fluidity failure such as gelation even when a single solvent-based ink composition is produced, and to provide a method for producing a printing ink composition for laminate for flexible packaging, in which the ink composition using the polyurethane urea resin solution is excellent in printability such as storage stability, two pack stability of ink, and resolubility.SOLUTION: A first step of synthesizing an isocyanate group-terminated urethane prepolymer by reacting a polyol component with a polyisocyanate component, a second step of adding an ester-based solvent and water to the obtained isocyanate group-terminated urethane prepolymer and reacting a monoamine component, and then a third step of reacting a polyamine component, in which in the second step, the temperature at the time of adding the ester-based solvent is a temperature equal to or lower than the boiling point of the ester-based solvent, and the water is added after allowing the isocyanate group-terminated urethane prepolymer to stand to cool or cooling the isocyanate group-terminated urethane prepolymer, A method for producing a polyurethane urea resin solution, comprising: adding water to an isocyanate group-terminated prepolymer in an amount of 0.2 to 24% by mass; and reacting a monoamine component with the isocyanate group-terminated prepolymer in such a manner that an amine equivalent number of the monoamine component with respect to an isocyanate equivalent number of the isocyanate group-terminated prepolymer is 0.005 to 0.550.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a polyurethane urea resin solution and a method for producing a printing ink composition for a flexible packaging laminate. More specifically, the present invention relates to a method for producing a polyurethane urea resin solution and a method for producing a printing ink composition for a flexible packaging laminate, which can produce an ink composition having excellent physical properties such as appearance and viscosity even when producing a single-solvent ink composition. [Background technology]

[0002] In recent years, the gravure printing industry, which uses large amounts of organic solvents, has become increasingly interested in solvent recovery due to the need to comply with hydrocarbon emission regulations and legal regulations such as the Fire Service Act and the Industrial Safety and Health Act. Accordingly, a laminate printing ink composition for flexible packaging, as described in Patent Document 1, has been developed as a solvent-recovery type ink composition. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 4082 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the polyurethane urea resin solution used in the ink composition described in Patent Document 1 may become cloudy or produce insoluble matter, particularly when it is a single solvent system.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and has an object to provide a method for producing a polyurethane urea resin solution that does not cause poor flowability such as turbidity or generation of insoluble matter in the polyurethane urea resin solution used in the ink composition, or gelation, even when producing a single-solvent ink composition, and a method for producing a printing ink composition for laminates for flexible packaging that uses a polyurethane urea resin solution and has excellent storage stability, two-component ink stability, resolubility, and other printing suitability. [Means for solving the problem]

[0006] The present invention, which solves the above problems, mainly comprises the following configuration.

[0007] (1) A method for producing a polyurethane urea resin solution, comprising: a first step of reacting a polyol component with a polyisocyanate component to synthesize an isocyanate-terminated urethane prepolymer; a second step of adding an ester solvent and water to the obtained isocyanate-terminated urethane prepolymer and reacting a monoamine component; and a third step of subsequently reacting a polyamine component, wherein in the second step, the ester solvent is added at a temperature equal to or lower than the boiling point of the ester solvent; the isocyanate-terminated urethane prepolymer is allowed to cool or the water is added after cooling; the water is added in an amount of 0.2 to 24 mass% relative to the isocyanate-terminated prepolymer; and the monoamine component is reacted so that the amine equivalent of the monoamine component relative to the isocyanate equivalent of the isocyanate-terminated prepolymer is 0.005 to 0.550.

[0008] According to this configuration, even when a single-solvent ink composition is produced, the resulting polyurethane urea resin solution does not suffer from poor fluidity such as turbidity or gelation. Furthermore, in the second step, water is less likely to act as a chain extender for the isocyanate group-terminated urethane prepolymer, and a polyurethane urea resin solution with excellent fluidity can be obtained.

[0009] (2) The method for producing a polyurethane urea resin solution according to (1), wherein the temperature of the isocyanate group-terminated urethane prepolymer when water is added in the second step is 0 to 50°C.

[0010] According to this configuration, the polyurethane urea resin solution obtained is less likely to suffer from poor fluidity such as turbidity and gelation, even when a single-solvent ink composition is produced. Furthermore, in the second step, water acts less likely to act as a chain extender for the isocyanate group-terminated urethane prepolymer, making it possible to obtain a polyurethane urea resin solution with better fluidity.

[0011] (3) The method for producing a polyurethane urea resin solution according to (1) or (2), wherein the polyamine component is a diamine component and a polyalkylene polyamine component.

[0012] According to this configuration, the polyurethane urea resin solution obtained exhibits good pigment dispersibility in a single-solvent ink composition.

[0013] (4) A method for producing a printing ink composition for a flexible packaging laminate, comprising a step of dispersing and mixing a pigment with the polyurethane urea resin solution according to any one of (1) to (3), wherein the water content in the printing ink composition for a flexible packaging laminate is 0.1 to 11% by mass.

[0014] According to this configuration, the ink composition obtained has excellent printability such as storage stability, two-component ink stability, and resolubility, even when it is a single solvent system. [Effects of the Invention]

[0015] According to the present invention, it is possible to provide a method for producing a polyurethane urea resin and a method for producing a printing ink composition for flexible packaging laminate, which can produce an ink composition that is excellent in physical properties such as appearance and viscosity, even when producing a single-solvent-based ink composition. DETAILED DESCRIPTION OF THE INVENTION

[0016] <Method of manufacturing polyurethane urea resin solution> A method for producing a polyurethane urea resin solution according to one embodiment of the present invention comprises a first step of reacting a polyol component with a polyisocyanate component to synthesize an isocyanate-terminated urethane prepolymer; a second step of adding an ester solvent and water to the resulting isocyanate-terminated urethane prepolymer and reacting the monoamine component; and a third step of subsequently reacting the polyamine component. In the second step, the ester solvent is added at a temperature below the boiling point of the ester solvent. In the second step, water is added after allowing the isocyanate-terminated urethane prepolymer to cool or after cooling. In the second step, water is added in an amount of 0.2 to 24% by mass relative to the isocyanate-terminated prepolymer. In the second step, the monoamine component is reacted such that the amine equivalent ratio of the monoamine component to the isocyanate equivalent of the isocyanate-terminated prepolymer is 0.005 to 0.550. Each step is described below.

[0017] (1st step) The first step is a step of reacting a polyol component with a polyisocyanate component to synthesize an isocyanate group-terminated urethane prepolymer.

[0018] Polyol component The polyol component is not particularly limited. Examples of the polyol component include polyether polyol components such as polyalkylene glycols (e.g., polyethylene glycol, polypropylene glycol, polytetramethylene glycol), high molecular weight polyether diol compounds (e.g., alkylene oxide adducts of bisphenol A with ethylene oxide, propylene oxide, etc.), polymeric polyester diols obtained by condensation reaction of one or more dibasic acids (e.g., adipic acid, sebacic acid, phthalic anhydride) with one or more glycols (e.g., ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol), and polyester polyol components such as polyester diol compounds (e.g., polycaprolactone diols). The polyol component may also be a biomass polyether polyol component or a biomass polyester polyol component using a vegetable oil-derived component.

[0019] The polyol component preferably contains 30% by mass or more of a polyester polyol component, because this facilitates the production of a polyurethane urea resin using an ester-based solvent, and the resulting ink composition has excellent printability, such as anti-fogging properties, and lamination suitability.

[0020] Polyisocyanate component The polyisocyanate component is not particularly limited. For example, the polyisocyanate component is obtained by mixing an aromatic diisocyanate compound such as tolylene diisocyanate, an alicyclic diisocyanate compound such as 1,4-cyclohexane diisocyanate, isophorone diisocyanate (IPDI), or 4,4'-dicyclohexylmethane diisocyanate (hydrogenated MDI), an aliphatic diisocyanate compound such as hexamethylene diisocyanate, and an aromatic aliphatic diisocyanate compound such as α,α,α',α'-tetramethylxylylene diisocyanate. Biomass-derived polyisocyanate components can also be used.

[0021] The method for reacting the polyol component with the polyisocyanate component is not particularly limited.

[0022] The reaction temperature is not particularly limited, and is, for example, about 50 to 120°C.

[0023] A catalyst may be added during the reaction as appropriate. The catalyst is not particularly limited. Examples of the catalyst include dibutyltin dilaurate, dibutyltin diacetate, lead naphthanate, lead octanoate, bismuth catalyst, zinc carboxylate, and amine catalyst.

[0024] The isocyanate index of the resulting isocyanate group-terminated urethane prepolymer is preferably 1.2 or more. The isocyanate index is preferably 3.0 or less, more preferably 2.0 or less. When the isocyanate index is within the above range, the resulting polyurethane urea resin has good hardness, and when a printing ink composition for flexible packaging laminate using the same is used for printing, the blocking resistance is less likely to decrease, and the adhesiveness and lamination suitability are excellent. In this embodiment, the isocyanate index (II) can be defined by the following formula: II = NCO groups of polyisocyanate (equivalent moles) / OH groups of polyol (equivalent moles)

[0025] (2nd process) The second step is a step of adding an ester solvent and water to the obtained isocyanate-terminated urethane prepolymer and reacting with the monoamine component. In the second step, the temperature when adding the ester solvent is a temperature below the boiling point of the ester solvent. Water is added after allowing the isocyanate-terminated urethane prepolymer to cool or cooling, and water is added in an amount of 0.2 to 24 mass% relative to the isocyanate-terminated prepolymer, and the monoamine component is reacted so that the amine equivalent number of the monoamine component relative to the isocyanate equivalent number of the isocyanate-terminated prepolymer is 0.005 to 0.550.

[0026] The temperature when the ester solvent is added may be any temperature not higher than the boiling point of the ester solvent, preferably not higher than 50° C., and more preferably not higher than 40° C. This makes it easier to obtain a polyurethane urea resin solution with excellent fluidity.

[0027] Water may be added after the isocyanate group-terminated urethane prepolymer has been allowed to cool or cooled. The temperature of the isocyanate group-terminated urethane prepolymer after being allowed to cool or cooled is preferably 0 to 50°C, more preferably 20 to 40°C. This allows the production of a polyurethane urea resin solution that is less prone to poor fluidity such as turbidity and gelation, even when producing a single-solvent ink composition. Furthermore, in this second step, water is less likely to act as a chain extender for the isocyanate group-terminated urethane prepolymer, making it easier to obtain a polyurethane urea resin solution with better fluidity.

[0028] Ester solvents The ester-based solvent is not particularly limited. Examples include ethyl acetate, n-propyl acetate, isopropyl acetate, isobutyl acetate, propylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. Among these, the ester-based solvent is preferably ethyl acetate, n-propyl acetate, or isopropyl acetate in terms of excellent drying properties and residual solvent, and more preferably ethyl acetate in terms of excellent drying properties, residual solvent, and cost.

[0029] The content of the ester-based solvent is not particularly limited. For example, the content of the ester-based solvent in the ink composition is preferably 15% by mass or more in order to ensure excellent printability of the resulting ink composition. Furthermore, the content of the ester-based solvent in the ink composition is preferably 90% by mass or less. When the content of the ester-based solvent is within the above range, the resulting ink composition has excellent printability and is likely to produce sufficient color development in the resulting printed matter.

[0030] ·water Water is added to provide reaction stability to the polyurethane urea resin and fluidity to the polyurethane urea resin solution and ink composition.

[0031] Water may be added in an amount of 0.2% by mass or more, preferably 1% by mass or more, relative to the isocyanate-terminated prepolymer. Water may be added in an amount of 24% by mass or less, preferably 10% by mass or less, relative to the isocyanate-terminated prepolymer. If the amount of water added is less than 0.2% by mass, the resulting polyurethane urea resin solution may suffer from poor fluidity, such as gelation. On the other hand, if the amount of water added exceeds 24% by mass, the resulting polyurethane urea resin solution may suffer from cloudiness.

[0032] Monoamine components The monoamine component is not particularly limited, and examples of the monoamine component include octylamine, monoethanolamine, monomethanolamine, and monoheptanolamine.

[0033] The amine equivalent number of the monoamine component when reacting the monoamine component may be 0.005 or more, preferably 0.03 or more, relative to the number of moles of isocyanate equivalent of the isocyanate group-terminated prepolymer. Furthermore, the amine equivalent number of the monoamine component may be 0.550 or less, preferably 0.3 or less, relative to the number of isocyanate equivalent of the isocyanate group-terminated prepolymer. If the amine equivalent number of the monoamine component is less than 0.005, the resulting polyurethane urea resin solution may have poor fluidity, such as gelation, while if it exceeds 0.550, the resulting polyurethane urea resin solution may have a problem of becoming cloudy.

[0034] There are no particular limitations on the method for adding an ester solvent and water to an isocyanate group-terminated urethane prepolymer and reacting it with a monoamine component.

[0035] The reaction temperature is not particularly limited, and is, for example, about 0 to 50°C.

[0036] (3rd step) The third step is a step of reacting the polyamine component.

[0037] Polyamine ingredients The polyamine component functions as a chain extender and a reaction terminator. The polyamine component is used to improve the cohesive strength and storage stability (pigment dispersibility) of the polyurethane urea resin. The polyamine component is not particularly limited. Examples of the polyamine component include aliphatic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, and hexamethylenediamine; alicyclic diamines such as isophoronediamine and 4,4'-dicyclohexylmethanediamine; aromatic diamines such as toluylenediamine; aromatic aliphatic diamines such as xylenediamine; diamines having hydroxyl groups such as N-(2-hydroxyethyl)ethylenediamine, N-(2-hydroxyethyl)propylenediamine, and N,N'-di(2-hydroxyethyl)ethylenediamine; and polyalkylene polyamines such as diethylenetriamine and triethylenetetramine. Among these, diamine components and polyalkylene polyamine components are preferred. This provides the polyurethane urea resin with improved storage stability (pigment dispersibility).

[0038] In the method for producing a polyurethane urea resin according to the present embodiment, optional components may be added as needed during synthesis of the polyurethane urea resin. The optional components are not particularly limited. Examples of the optional components include chain extenders such as diol compounds (e.g., ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, diethylene glycol, and triethylene glycol) and triol compounds (e.g., glycerin), and reaction terminators such as monoalcohols (e.g., methanol and ethanol) and alkylamines (e.g., n-propylamine, n-butylamine, and di-n-butylamine).

[0039] The method for reacting the polyamine component is not particularly limited.

[0040] The reaction temperature is not particularly limited, and is, for example, about 0 to 50°C.

[0041] Through the above steps, a polyurethane urea resin can be produced.

[0042] The amine value of the polyurethane urea resin is preferably 0.1 to 10.0 mgKOH / g, and more preferably 0.2 to 8.0 mgKOH / g. When the amine value is within the above range, the resulting ink composition exhibits excellent adhesion to films, lamination suitability, and blocking resistance. In this embodiment, the amine value refers to the amine value per 1 g of solid content, measured using a 0.1 N hydrochloric acid aqueous solution by potentiometric titration (for example, COMTITE (AUTO TITRATOR COM-900, BURET B-900, TITSTATION K-900), manufactured by Hiranuma Sangyo Co., Ltd.), and then converted into the potassium hydroxide equivalent. In this embodiment, there are no particular limitations on the method for adjusting the amine value to fall within the above range.

[0043] The obtained polyurethane urea resin solution is a polyurethane urea resin solution that is free from poor fluidity such as turbidity, generation of insoluble matter, and gelation, and even when the polyurethane urea resin solution is used to produce a single-solvent ink composition described below, it is possible to produce a printing ink composition for flexible packaging laminate that has excellent physical properties such as storage stability, two-component ink stability, and printability.

[0044] <Method for producing printing ink composition for flexible packaging laminate> A method for producing a printing ink composition for flexible packaging laminates (hereinafter also referred to as ink composition) according to one embodiment of the present invention includes a step of dispersing and mixing a pigment and the polyurethane urea resin solution described above. Water is contained in the ink composition in an amount of 0.1 to 10% by mass. Each of these components will be described below.

[0045] (pigment) The pigment is not particularly limited. For example, the pigment may be various inorganic or organic pigments. Specific examples of inorganic pigments include colored pigments (including achromatic colored pigments such as white and black) such as titanium oxide, red iron oxide, antimony red, cadmium yellow, cobalt blue, ultramarine, Prussian blue, carbon black, and graphite, and extender pigments such as calcium carbonate, kaolin, clay, barium sulfate, aluminum hydroxide, and talc. Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, and condensed polycyclic pigments. Pigments may be used in combination.

[0046] Furthermore, titanium oxide used as a white pigment is preferably silica alumina and / or titanium oxide that has been surface-treated with an organic agent for reasons of stability over time.

[0047] The content of the pigment is not particularly limited. For example, the pigment may be contained in the ink composition in an amount of 0.5 to 50% by mass. When the content of the pigment is within the above range, the ink composition is likely to exhibit sufficient color development and has excellent printability.

[0048] (Polyurethane urea resin solution) The polyurethane urea resin solution may be the polyurethane urea resin solution described above in relation to the method for producing the polyurethane urea resin solution.

[0049] (ester solvent) The method for producing the ink composition of this embodiment preferably uses only ester-based solvents and contains substantially no organic solvents other than ester-based solvents. The ester-based solvent is not particularly limited. Examples of ester-based solvents include ethyl acetate, n-propyl acetate, isopropyl acetate, isobutyl acetate, propylene glycol monoethyl ether acetate, and propylene glycol monomethyl ether acetate. Among these, ethyl acetate, n-propyl acetate, and isopropyl acetate are preferred as ester-based solvents because of their excellent drying properties and residual solvent content. Ethyl acetate is even more preferred because of its excellent drying properties, residual solvent content, and cost. This facilitates solvent recovery from the ink composition, and since the ink composition contains only ester-based solvents, it is easily reusable. In this embodiment, "substantially free of organic solvents other than ester-based solvents" refers to a content of essentially 0%, but also includes cases where a small amount of organic solvent is contained in the additive.

[0050] (water) The ink composition preferably contains 0.1 to 11% by mass of water in order to impart fluidity to the ink composition.

[0051] The water content in the ink composition may be 0.1% by mass or more, and preferably 1% by mass or more. The water content in the ink composition may be 11% by mass or less, and preferably 10% by mass or less. If the water content is less than 0.1% by mass, the ink composition tends to have high viscosity. On the other hand, if the water content exceeds 11% by mass, the ink composition tends to have poor storage stability.

[0052] (optional ingredient) The method for producing the ink composition of this embodiment may contain optional components, such as cellulose ester resins other than polyurethane urea resins, rosin and its derivatives, binder resins such as vinyl chloride / vinyl acetate copolymers and vinyl chloride / acrylic polymers, adhesion improvers such as chlorinated polypropylene and dammar resins, anti-blocking agents such as silica particles, polyethylene wax, fatty acid amides, soluble nitrocellulose and polyamide resins, pigment dispersants, crosslinking agents, lubricants, surfactants, etc.

[0053] <Binder resins other than polyurethane urea resins> Cellulose ester resin The ink composition of this embodiment may contain a cellulose ester resin for the purposes of anti-blocking and viscosity adjustment. Examples of the cellulose ester resin include cellulose acetate propionate resin and cellulose acetate butyrate resin.

[0054] The cellulose acetate propionate resin may be any resin conventionally used in gravure printing ink compositions. Cellulose acetate propionate resin is obtained by triesterifying cellulose with acetic acid and propionic acid, followed by hydrolysis. Generally, commercially available cellulose acetate propionate resins have an acetylation content of 0.6 to 2.5% by mass, a propionylation content of 42 to 46% by mass, and a hydroxyl group content of 1.8 to 5% by mass. Depending on the type of pigment, the cellulose acetate propionate resin is preferably used in a range of 0.1 to 3.0% by mass in a gravure printing ink composition for film.

[0055] The cellulose acetate butyrate resin can be any resin conventionally used in gravure printing ink compositions. Cellulose acetate butyrate resin is obtained by triesterifying cellulose with acetic acid and butyric acid, followed by hydrolysis. Generally, commercially available cellulose acetate butyrate resins are acetylated at 2 to 30% by mass, butyrated at 17 to 53% by mass, and contain 1 to 5% by mass of hydroxyl groups. Depending on the type of pigment, the cellulose acetate butyrate resin is preferably used in the ink composition in an amount of 0.1 to 3.0% by mass.

[0056] Rosin and its derivatives The ink composition of this embodiment may contain rosin and its derivatives for improving adhesion and stability over time.

[0057] Rosin includes gum rosin, tall oil rosin, wood rosin, etc. Generally, rosin is an amber-colored, amorphous resin obtained from pine trees, and since it is obtained from nature, it is a mixture. Rosin may be isolated into its constituent components, namely, abietic acid, neoabietic acid, palustric acid, pimaric acid, isopimaric acid, sandaracopimaric acid, and dehydroabietic acid, and these are also defined as rosin in this embodiment.

[0058] The rosin derivatives are compounds obtained by modifying the above-mentioned rosin, and specific examples thereof are listed below. (1) Hydrogenated rosin: A rosin whose weather resistance has been improved by adding hydrogen to the conjugated double bonds (hydrogenation). (2) Disproportionated rosin: Disproportionation is a modification in which two molecules of rosin react with each other, resulting in two molecules of abietic acid with conjugated double bonds, one of which becomes aromatic and the other a molecule with a single double bond. Disproportionated rosin is generally less weather-resistant than hydrogenated rosin, but its weather resistance is better than that of untreated rosin. (3) Rosin-modified phenolic resin: Rosin-modified phenolic resin is often used as the main binder in offset printing inks. Rosin-modified phenolic resin can be obtained by known manufacturing methods. (4) Rosin ester: An ester resin derived from rosin, which has long been used as a tackifier for adhesives and pressure sensitive adhesives. (5) Rosin-modified maleic acid resin: This is produced by adding maleic anhydride to rosin, and may also include hydroxyl group-containing compounds such as glycerin that are esterified with the anhydride groups and grafted, if necessary. (6) Polymerized rosin: A derivative containing dimerized resin acid derived from natural resin rosin. In addition, known rosins and rosin derivatives can also be used, and these can be used alone or in combination.

[0059] Furthermore, the acid value of the rosin and its rosin derivatives is preferably 120 mgKOH / g or more. When the acid value is 120 mgKOH / g or more, the ink composition has improved laminate strength. The acid value is more preferably 160 mgKOH / g or more. When rosin and its derivatives are blended, the total amount used is preferably 0.1 to 3.0 mass % in terms of solid mass of the ink composition.

[0060] Vinyl chloride / vinyl acetate copolymer The vinyl chloride / vinyl acetate copolymers can be produced by known methods using vinyl chloride monomer and vinyl acetate monomer, which are conventionally used in gravure printing ink compositions, as essential components, and, if necessary, fatty acid vinyl monomers such as vinyl propionate, vinyl monochloroacetate, vinyl versatate, vinyl laurate, vinyl stearate, and vinyl benzoate, and monomers having functional groups such as hydroxyl groups, as copolymerization components.

[0061] Among them, in the organic solvent system of this embodiment, a vinyl chloride / vinyl acetate copolymer having 50 to 200 hydroxyl groups is suitable. Such a vinyl chloride / vinyl acetate copolymer having hydroxyl groups can be obtained by saponifying a portion of the ester moiety and introducing a (meth)acrylic monomer having a hydroxyl group.

[0062] In the case of a vinyl chloride / vinyl acetate copolymer having hydroxyl groups obtained by saponifying a portion of the ester moieties, the coating properties and dissolution behavior of the resin are determined by the ratio of the structural units based on the reactive sites of vinyl chloride (formula 1 below), the structural units based on the reactive sites of vinyl acetate (formula 2 below), and the structural units based on saponification of the reactive sites of vinyl acetate (formula 3 below) in the molecule. That is, the structural units based on the reactive sites of vinyl chloride impart toughness and hardness to the resin coating, the structural units based on the reactive sites of vinyl acetate impart adhesion and flexibility, and the structural units based on saponification of the reactive sites of vinyl acetate impart good solubility in the organic solvent system of this embodiment. Formula 1 -CH2-CHCl- Formula 2 -CH2-CH(OCOCH3)- Formula 3 -CH2-CH(OH)-

[0063] Such vinyl chloride / vinyl acetate copolymers may be commercially available, and examples thereof include Solbin A, AL, TA5R, TA2, TA3, TAO, TAOL, C, CH, CN, and CNL manufactured by Nissin Chemical Industry Co., Ltd.

[0064] From the viewpoint of solubility in organic solvents used in the ink composition of this embodiment and printability, the vinyl chloride / vinyl acetate copolymer may have various functional groups in the molecule, and preferably has 50 to 200 hydroxyl groups. Commercially available vinyl chloride / vinyl acetate copolymers such as Solbin A, AL, TA5R, TA2, TA3, TAO, and TAOL are preferably used.

[0065] Vinyl chloride / acrylic copolymer Vinyl chloride / acrylic copolymers are copolymers of vinyl chloride and acrylic monomers as their main components. The form of the copolymer is not particularly limited, and for example, the acrylic monomers may be incorporated into the main chain of polyvinyl chloride in a block or random manner, or may be graft-copolymerized onto the side chains of polyvinyl chloride.

[0066] The acrylic monomer may be a (meth)acrylic acid ester, an acrylic monomer having a hydroxyl group, etc. Examples of the (meth)acrylic acid ester include a (meth)acrylic acid alkyl ester, and the alkyl group may be linear, branched, or cyclic, and is preferably a linear alkyl group.

[0067] Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tetradecyl (meth)acrylate, hexadecyl (meth)acrylate, and octadecyl (meth)acrylate.

[0068] Examples of acrylic monomers having a hydroxyl group include (meth)acrylic acid hydroxyalkyl esters such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, and 8-hydroxyoctyl (meth)acrylate; glycol mono(meth)acrylates such as polyethylene glycol mono(meth)acrylate, polypropylene glycol mono(meth)acrylate, and 1,4-cyclohexanedimethanol mono(meth)acrylate; caprolactone-modified (meth)acrylate; and hydroxyethyl acrylamide.

[0069] The acrylic monomer may also have a functional group other than a hydroxyl group, such as a carboxyl group, an amide bond group, an amino group, or an alkylene oxide group.

[0070] The vinyl chloride / acrylic copolymer resin preferably has a mass average molecular weight of 10,000 to 70,000. The weight-average molecular weight can be measured by gel permeation chromatography (GPC). For example, chromatography can be performed using a Water 2690 (manufactured by Waters) as a GPC device and a PLgel 5μ MIXED-D (manufactured by Polymer Laboratories) as a column, and the weight-average molecular weight can be determined as a polystyrene equivalent.

[0071] In addition, in view of the solubility in organic solvents and adhesion to substrates in this embodiment, the vinyl chloride / acrylic copolymer preferably has 50 to 200 hydroxyl groups.

[0072] The amount of vinyl chloride / vinyl acetate copolymer or vinyl chloride / acrylic polymer used may be in the range of polyurethane urea resin / (vinyl chloride / vinyl acetate copolymer and / or vinyl chloride / acrylic copolymer)=95 / 5 to 45 / 55 (mass ratio).

[0073] Adhesion improver Chlorinated polypropylenes with a chlorination degree of 20 to 50% are preferably used. When the chlorination degree is within the above range, the chlorinated polypropylene has excellent compatibility with organic solvents and excellent adhesion to films. In the present embodiment, the chlorination degree is defined as the mass % of chlorine atoms in the chlorinated polypropylene resin. Furthermore, the chlorinated polypropylene is preferably a modified or unmodified chlorinated polypropylene having a mass average molecular weight of 5,000 to 200,000. When the mass average molecular weight is within the above range, the chlorinated polypropylene has excellent adhesion and excellent solubility in organic solvents. When chlorinated polypropylene is used, it is preferably used in an amount of 3.0 mass % or less in terms of the solids mass % of the ink composition.

[0074] Dammar resin, also written as damar or dammar, is a type of natural resin derived from plants. Specifically, it is a type of natural resin obtained from Dipterocarpaceae or Burseraceae plants that grow in Southeast Asia, including Malaysia and Indonesia. When used, dammar resin is dissolved in an appropriate organic solvent to form a varnish. Because dammar resin does not contain chlorine, it can eliminate or reduce chlorine compared to using chlorinated polyolefin resin in printing ink compositions. Furthermore, when using dammar resin, it is preferable to use it at a solids content of 3.0 mass% or less of the ink composition.

[0075] Anti-blocking agent Examples of silica particles include natural and synthetic silica particles, crystalline and amorphous silica particles, and hydrophobic and hydrophilic silica particles. The silica particles preferably have an average particle diameter of 1.0 to 5.0 μm (the average particle diameter of silica particles refers to the particle diameter at 50% cumulative value (D50) in the particle size distribution, and can be determined by the Coulter counter method). The silica particles may be hydrophilic silica particles having hydrophilic functional groups on their surfaces, or hydrophobic silica particles in which the hydrophilic functional groups have been hydrophobized with alkylsilane or the like. Among these, hydrophilic silica particles are preferred. Ink compositions containing hydrophilic silica particles promote ink wetting and spreading during overprinting and also improve the overprinting effect (hereinafter sometimes referred to as "trapping property"). When silica particles are used, they are used in an amount of 3.0 mass % or less, preferably 1.0 mass % or less, in the ink composition.

[0076] The polyethylene wax used has an average particle size in the range of 1.0 to 3.0 μm (the average particle size refers to the particle size measured with Microtrac UPA #1, manufactured by Honeywell). When the particle size of the polyethylene wax is within the above range, the ink composition has excellent smoothness, anti-blocking properties, and trapping properties. When polyethylene wax is used, its content in the ink composition is preferably 1.5% by mass or less.

[0077] The soluble nitrocellulose can be any soluble nitrocellulose that has been used in gravure printing ink compositions. The soluble nitrocellulose is obtained by reacting natural cellulose with nitric acid to replace three hydroxyl groups in the six-membered ring of the anhydroglucopyranose group in the natural cellulose with nitric acid groups, resulting in a nitric acid ester. The soluble nitrocellulose used in this embodiment preferably has a nitrogen content of 10 to 13% and an average degree of polymerization of 35 to 90. Specific examples of soluble nitrocellulose include SS1 / 2, SS1 / 4, SS1 / 8, TR1 / 16, and NCRS-2 (manufactured by KOREA CNC LTD). When soluble nitrocellulose is used, it is preferable to use it in an amount of 2.0 mass% or less in the ink composition, depending on the type of pigment.

[0078] The fatty acid amide is not particularly limited as long as it has an amide group and a residue obtained by removing an acid group from a fatty acid. The fatty acid amide may be a monoamide, a substituted amide, a bisamide, a methylolamide, an esteramide, or the like, and is preferably at least one selected from the group consisting of a monoamide, a substituted amide, and a bisamide, since this improves blocking resistance. The amount of fatty acid amide used in the ink composition is preferably 1% by mass or less.

[0079] Monoamide: Monoamide is represented by the following general formula (1): General formula (1) R1-CONH2 (In the formula, R1 represents the residue obtained by removing COOH from a fatty acid.)

[0080] Specific examples of monoamides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, oleic acid amide, and erucic acid amide.

[0081] Substituted amide: The substituted amide is represented by the following general formula (2): General formula (2) R2-CONH-R3 (In the formula, R2 and R3 represent the residue obtained by removing COOH from a fatty acid, and may be the same or different.)

[0082] The substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide.

[0083] Bisamide: Bisamide is represented by the following general formula (3) or (4). General formula (3) R4-CONH-R5-HNCO-R6 General formula (4) R7-NHCO-R8-CONH-R9 (In the formula, R4, R6, R7, and R9 represent residues obtained by removing COOH from fatty acids and may be the same or different, and R5 and R8 represent alkylene or arylene groups having 1 to 10 carbon atoms.)

[0084] Examples of bisamides include methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-distearyl adipamide, N,N'-distearyl sebacic acid amide, N,N'-dioleyl adipamide, and N,N'-dioleyl sebacic acid amide.

[0085] Methylolamide: Methylolamide is represented by the following general formula (5): General formula (5) R10-CONHCH2OH (In the formula, R10 represents a residue obtained by removing COOH from a fatty acid.)

[0086] Examples of the methylol amide include methylol palmitic acid amide, methylol stearic acid amide, methylol behenic acid amide, methylol hydroxystearic acid amide, methylol oleic acid amide, and methylol erucic acid amide.

[0087] Ester amide: Ester amide is represented by the following general formula (6): General formula (6) R11-CONH-R12-OCO-R13 (In the formula, R11 and R13 represent a residue obtained by removing COOH from a fatty acid and may be the same or different, and R12 represents an alkylene group or arylene group having 1 to 10 carbon atoms.)

[0088] Examples of the ester amide include stearylamide ethyl stearate and oleylamide ethyl stearate.

[0089] The melting point of the fatty acid amide is preferably 50°C to 150°C.

[0090] Furthermore, the fatty acid constituting the fatty acid amide is preferably a saturated fatty acid having 12 to 22 carbon atoms and / or an unsaturated fatty acid having 16 to 25 carbon atoms, more preferably a saturated fatty acid having 16 to 18 carbon atoms and / or an unsaturated fatty acid having 18 to 22 carbon atoms. More preferred saturated fatty acids are lauric acid, palmitic acid, stearic acid, behenic acid, and hydroxystearic acid, and more preferred unsaturated fatty acids are oleic acid and erucic acid.

[0091] Antistatic agent The antistatic agent is not particularly limited. Examples of the antistatic agent include coconut alkyl bis(hydroxyethyl)methyl nitrate and coconut alkyl bis(hydroxyethyl)methyl chloride, quaternary ammonium salt compounds (sulfates), quaternary ammonium salts (hydrochlorides) such as monoalkyl trimethyl ammonium chloride, monoalkyl benzyl dimethyl ammonium chloride, and dialkyl dimethyl ammonium chloride, thiocyanates, alkyl imidazolines, and alkyl imidazoliums. The content of the antistatic agent in the ink composition is preferably 3.0% by mass or less.

[0092] Returning to the description of the ink composition as a whole, the method for producing the ink composition of this embodiment is not particularly limited. As an example, the ink composition can be prepared by milling the pigment, polyurethane urea resin, and, if necessary, the ester-based solvent using various milling machines such as a bead mill, ball mill, sand mill, attritor, roll mill, or pearl mill, and then adding water and various optional components if necessary, and stirring and mixing the mixture.

[0093] The viscosity of the resulting ink composition is preferably adjusted to 10 to 1,000 mPa·s. When used in gravure printing, the ink composition is preferably diluted with an ester solvent so that the viscosity is appropriate for the printing conditions at the ambient temperature during printing, specifically, until the Zahn Cup No. 3 flow rate is 12 to 23 seconds at 25°C, or approximately 14 to 16 seconds at 25°C for high-speed printing.

[0094] The ink composition of this embodiment is easy to handle because the viscosity can be easily adjusted within the above range, even when it is a single solvent system.

[0095] Furthermore, according to the method for producing the ink composition of this embodiment, even in the case of a single solvent system, various physical properties such as storage stability, two-component ink stability, and printability are excellent.

[0096] <Method for obtaining a laminated product using a printing ink composition for flexible packaging laminate> Next, a method for obtaining a laminated product using the ink composition of this embodiment will be described.

[0097] In the present embodiment, the laminated product is produced, for example, by first printing a non-white ink composition on a resin film at least once by gravure printing, and then optionally printing a white ink composition on the surface side of the colored ink layer formed by these printings (the layer below the surface after final lamination) by gravure printing, followed by drying with a dryer.

[0098] A resin film or the like can be laminated by various lamination methods on the white ink composition layer side of the resulting printed matter to obtain a laminated product for use in a packaging bag or the like.

[0099] The laminated product can be obtained by extrusion lamination, in which an anchor coating agent is applied to the surface of a printed material and then a molten polymer is laminated thereon, or by dry lamination, in which an adhesive is applied to the surface of a printed material and then a film-like polymer is attached. The extrusion lamination method involves applying an anchor coating agent such as a titanium-based, urethane-based, imine-based, or polybutadiene-based agent to the surface of the printed material as needed, and then laminating the molten polymer using a known extrusion laminator. Furthermore, the molten resin can be used as an intermediate layer to sandwich the printed material with other materials.

[0100] The molten polymer used in the extrusion lamination method may be a conventionally used resin such as low-density polyethylene, ethylene-vinyl acetate copolymer, polypropylene, etc. Among these, the molten polymer preferably contains low-density polyethylene because it is easily oxidized during melting to generate carbonyl groups.

[0101] The dry lamination method involves coating the surface of a layer of white ink composition with a urethane-based, isocyanate-based, or other adhesive, and then laminating a film-like polymer using a known dry laminating machine. Resins that can be used for the film used in the dry lamination method include polyethylene and unstretched polypropylene. For packaging materials used in retort applications, aluminum foil can be sandwiched between the substrate and the laminated resin film. Such laminated products can also be used for boiling and retort applications after being made into bags and filled with the contents.

[0102] The resin film used here is not particularly limited, and examples thereof include polyester films such as polyethylene terephthalate (PET), polylactic acid, and polycaprolactone, various plastic films for printing such as nylon and vinylon, and films obtained by laminating a barrier layer formed by metal deposition or coating a barrier resin on any of these plastic films for printing. [Example]

[0103] The present invention will be described in more detail below with reference to examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass."

[0104] <Example of a method for producing a polyurethane urea resin solution> Example 1 A four-neck flask equipped with a stirrer, a condenser, and a nitrogen gas inlet tube was charged with 100 parts by weight of a polyester polyol of ethylene glycol / neopentyl glycol = 7 / 3 (molar ratio) and adipic acid with an average molecular weight of 2000, 100 parts by weight of polypropylene glycol with an average molecular weight of 2000, and 35.0 parts by weight of isophorone diisocyanate, and the mixture was reacted at 80 to 90 ° C for 3 hours while introducing nitrogen gas. The resulting isocyanate-terminated urethane prepolymer was allowed to cool to 25 ° C to prevent the chain extension reaction with water from proceeding, and then 15.1 parts by weight of water and 737.9 parts by weight of ethyl acetate were added. Then, 0.06 parts by weight of monoethanolamine was added and the reaction was continued for 30 minutes. 10.0 parts by weight of isophorone diamine was added and the reaction was continued for 30 minutes at 20 to 30 ° C to extend the chain and terminate the reaction, yielding polyurethane urea resin solution 1 (solids content 25% by weight, weight average molecular weight 50,000).

[0105] (Examples 2 to 7, Comparative Examples 1 to 4) A polyurethane urea resin solution was prepared in the same manner as in Example 1, except that the formulation and conditions were changed to those shown in Table 1. In Table 1, "II" represents the isocyanate index, and "AI" represents the amine index (the amine index in the table is the number of equivalents of the amine component / the number of isocyanate equivalents of the isocyanate group-terminated prepolymer).

[0106] The polyurethane urea resin solutions obtained in Examples 1 to 7 and Comparative Examples 1 to 4 were evaluated for "turbidity" and "fluidity" by the following evaluation methods. The results are shown in Table 1.

[0107] [Table 1]

[0108] <Turbidity> The resulting polyurethane urea resin solution was collected in a glass bottle and evaluated for turbidity according to the following evaluation criteria. (Evaluation criteria) A: It was clear and not cloudy. B: Slight turbidity occurred. C: Turbid and opaque.

[0109] <Liquidity> The fluidity of the resulting polyurethane urea resin solution was evaluated according to the following evaluation criteria. (Evaluation criteria) A: No poor fluidity such as gelation occurred. B: Slight thickening occurred, but no gelation occurred. C: Poor fluidity such as gelation occurred.

[0110] As shown in Table 1, the polyurethane urea resin solutions prepared by the manufacturing methods described in Examples 1 to 7 of the present invention were not cloudy and did not suffer from poor fluidity such as gelation, even though they were single-solvent polyurethane urea resin solutions.

[0111] <Example of method for producing printing ink composition for flexible packaging laminate> The raw materials used are shown below. (pigment) White pigment: Titanium oxide (particle size 0.23 μm, oil absorption 24 g / 100 g, silica alumina treatment, pH 6.5 to 8.5) (Cellulose acetate propionate (CAP) solution) 20 parts by mass of cellulose acetate propionate (manufactured by Kanto Scientific Co., Ltd., number average molecular weight 25,000, propionyl 43 to 47%) was dissolved in 80 parts by mass of ethyl acetate to obtain a cellulose acetate propionate (CAP) solution with a solid content of 20%. (rosin and its derivatives) Polymerized rosin: Acid value 160mgKOH / g (ester solvent) Ethyl acetate (hardening agent) Lamiol R hardener (manufactured by Sakata Inx Corporation)

[0112] Example 8 The polyurethane urea resin solution prepared in Example 1 above, pigment, and ethyl acetate were kneaded using a paint conditioner manufactured by Red Devil Co., Ltd., and water, cellulose acetate propionate (CAP), polymerized rosin, and ethyl acetate were added and stirred to disperse and mix, thereby obtaining ink compositions for laminate printing on flexible packaging of the Examples and Comparative Examples shown in Table 2.

[0113] (Examples 9 to 16, Comparative Example 5) An ink composition for laminate printing for flexible packaging was prepared in the same manner as in Example 8, except that the formulation was changed to that shown in Table 2.

[0114] The ink compositions for laminate printing on flexible packaging obtained in Examples 8 to 16 and Comparative Example 5 were evaluated for "storage stability," "two-component ink stability," "printability (fading)," and "printed matter evaluation" using the following evaluation methods. The results are shown in Table 2.

[0115] [Table 2]

[0116] <Storage stability> The obtained printing ink composition for flexible packaging laminate was placed in a glass bottle and stored at an ambient temperature of 60°C for 14 days to evaluate the storage stability of the ink based on whether or not the pigment settled. The results are shown in Table 1. (Evaluation criteria) A: No sedimentation was observed, and the storage stability of the ink composition was good. B: Some settling was observed. C: A lot of sedimentation was observed, and the storage stability of the ink composition was poor. <Two-component ink stability> Each of the gravure printing ink compositions for lamination was placed in a glass bottle, and 3 parts by mass of a curing agent was added to 100 parts by mass of each ink. The ink was then stored at 40°C for 3 days, and the change in viscosity measured with a Zahn Cup No. 3 was used to evaluate the two-component stability of the ink in accordance with the following evaluation criteria. (Evaluation criteria) A: Viscosity change is less than 2 seconds B: Viscosity change is between 2 seconds and 5 seconds C: Viscosity change is 5 seconds or more

[0117] <Production of laminate> 100 parts by mass of each printing ink composition for flexible packaging laminate was diluted with ethyl acetate, and the viscosity was adjusted to 15 seconds using a Zahn Cup No. 3 (Rigo Co., Ltd.). The printing ink composition for flexible packaging laminate was printed on the treated surface of each film using a gravure printing machine under the following conditions, followed by drying to obtain printed matter for lamination. The obtained laminate printed matter was also evaluated for "printability (blurring)" and "printed matter evaluation (blocking resistance, adhesion, retort resistance)." The results are shown in Table 2. (Printing method / printing conditions) Printing room environment: Temperature 25°C, humidity 50% Coating machine: Gravure proofing machine Coating speed: 150 m / min Printing plate: Direct 175 line solid plate Drying temperature: 55℃ (air volume 80%)

[0118] <About the film> PET: Polyethylene terephthalate film with corona discharge treatment on one side, manufactured by Toyobo Co., Ltd., E-5101, thickness 12 μm OPP: Corona-discharged biaxially oriented polypropylene film, Toyobo Co., Ltd., P-2161, thickness 25 μm NY: Nylon film, Toyobo Co., Ltd., N-1102, thickness 15 μm Fine Barrier: PET film with alumina vapor deposition on one side (Fine Barrier AT-R, manufactured by Reiko Co., Ltd.) Techbarrier: PET film with silica vapor deposition on one side (Techbarrier TXR, manufactured by Mitsubishi Plastics, Inc.) A-OP: Stretched polypropylene film coated on one side with polyvinyl alcohol (A-OPBH, manufactured by Mitsui Chemicals Tocello Co., Ltd.) Emblem: Stretched nylon film coated on one side with polyvinylidene chloride (Emblem-DC DCR, manufactured by Unitika Ltd.) Besela: PET film coated on one side with acrylic polymer (Besela ET140R, manufactured by Toppan Printing Co., Ltd.) GL: PET film with alumina vapor deposition on one side (GL-ARH, manufactured by Toppan Printing Co., Ltd.)

[0119] (Printability (blurred)) The printability was evaluated based on the percentage of the area of ​​smudges in the printed portion at the end of printing, which were caused by ink clogging the plate. A: There was no cassoulet at all. B: Slight smearing was observed, but within the practical range. C: There was a lot of smearing. <Evaluation of printed matter (blocking resistance)> One day after printing with each test ink, the printed surface of the print and the untreated surface of each film were combined and weighed at 400 g / cm 2 After leaving the film at 40°C for 12 hours under a load of 1.0 g, the film was peeled off and the blocking resistance was evaluated according to the following criteria. (Evaluation criteria) A: There was absolutely no resistance when peeling off the film, and the ink did not peel off from the printed surface. B: There was resistance when peeling the film, but the ink did not peel off from the printed surface. C: There was resistance when peeling off the film, and the ink peeled off from the printed surface. <Printed matter evaluation (adhesion)> Immediately after printing, cellophane tape was applied to the printed surface of the resulting print, which was then rubbed twice with the pad of the thumb. The cellophane tape was then peeled off, and the adhesion was evaluated based on the percentage of the area of ​​the ink film that peeled off from the adherend. (Evaluation criteria) A: The film did not peel off at all. B: The area where the film peeled off was less than 20%. C: The area where the film peeled off was 20% or more. <Evaluation of printed matter (retort resistance)> One day after printing, each print was applied with 3.0 g / m2 of solids. 2 After applying a urethane adhesive (Takelac A-626 / Takenate A-50, manufactured by Mitsui Chemicals Polyurethane Urea, Inc.) in an amount of 0.01g, an unstretched polypropylene film (RXC-3, 60 μm thick, manufactured by Mitsui Chemicals Tohcello, Inc.) was laminated using a dry laminating machine and left to stand at 40°C for 3 days to obtain a dry laminate. This dry laminate was made into a bag, filled with a mixture of 90% by mass of water and 10% by mass of salad oil, and heat-sealed. The bag was then immersed in pressurized hot water at 120°C for 30 minutes to evaluate retort resistance based on whether or not the laminate film floated. (Evaluation criteria) A: No lamination was observed at all. B: Fine, short laminations were observed on pinholes or in some areas. C: Long stripes of lamination were observed over the entire surface.

[0120] As shown in Table 2, the printing ink compositions for flexible packaging laminates prepared by the manufacturing methods described in Examples 8 to 16 of the present invention were single-solvent ink compositions, but they had excellent storage stability, two-component ink stability, and printability (fade), and also had excellent physical properties in evaluations of printed matter such as adhesion.

Claims

1. a first step of reacting a polyol component with a polyisocyanate component to synthesize an isocyanate group-terminated urethane prepolymer; a second step of adding an ester solvent and water to the obtained isocyanate group-terminated urethane prepolymer and reacting the monoamine component; and then a third step of reacting a polyamine component, In the second step, the temperature at which the ester-based solvent is added is a temperature equal to or lower than the boiling point of the ester-based solvent, The water is added after the isocyanate group-terminated urethane prepolymer is allowed to cool or is cooled, adding the water in an amount of 0.2 to 24% by mass based on the isocyanate group-terminated prepolymer; a method for producing a polyurethane urea resin solution, comprising reacting the monoamine component so that the number of amine equivalents of the monoamine component relative to the number of isocyanate equivalents of the isocyanate group-terminated prepolymer is 0.005 to 0.

550.

2. 2. The method for producing a polyurethane urea resin solution according to claim 1, wherein the temperature of the isocyanate group-terminated urethane prepolymer when water is added in the second step is 0 to 50°C.

3. The method for producing a polyurethane urea resin solution according to claim 1 or 2, wherein the polyamine component is a diamine component and a polyalkylene polyamine component.

4. The method includes a step of dispersing and mixing a pigment and the polyurethane urea resin solution according to claim 1 or 2, The method for producing a printing ink composition for a flexible packaging laminate, wherein the water is contained in an amount of 0.1 to 11 mass % in the printing ink composition for a flexible packaging laminate.

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