Printing ink composition for laminate for soft packaging, laminate processing method, and method for manufacturing laminate processed product

Abstract

To provide a printing ink composition for laminate for soft packaging which is excellent in various physical properties such as storage stability, extrusion laminate suitability, and blocking resistance.SOLUTION: A printing ink composition for laminate for soft packaging contains a pigment, a binder resin containing a polyurethane resin, and an organic solvent. The polyurethane resin contains acyclic diamine as a diamine component and polypropylene glycol as a polyol component, a content of the acyclic diamine is 30% or more in a molar ratio in the diamine component, and a number average molecular weight of the polypropylene glycol is 300 to 3,300.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a printing ink composition for flexible packaging laminate, a lamination method, and a method for producing a laminated product. More specifically, the present invention relates to a printing ink composition for flexible packaging laminate, which has excellent storage stability and various physical properties such as extrusion lamination suitability and blocking resistance, a lamination method, and a method for producing a laminated product. [Background technology]

[0002] Packaging materials using various plastic films are used for foods, confectionery, household goods, pet food, etc., so that functions such as design, economy, content protection, and transportability can be obtained. In addition, gravure printing and flexographic printing are applied to many packaging materials with the intention of imparting design and message appealing to consumers. In order to obtain these packaging materials, front printing is performed on the surface of the base film of the packaging material, or reverse printing is performed in which an adhesive or anchor coating agent is applied as necessary to the printed surface of the base film of the packaging material and the film is laminated. In reverse printing, color inks and white ink are printed sequentially on various films such as polyester, nylon, and aluminum foil. After that, a polyethylene film, a polypropylene film, or the like is laminated on the printed layer of the white ink for the purpose of heat sealing by dry lamination processing using an adhesive or extrusion lamination processing using an anchor coating agent (see, for example, Patent Documents 1-2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-298618 A [Patent Document 2] Japanese Patent Application Publication No. 57-98577 Summary of the Invention [Problem to be solved by the invention]

[0004] However, in general, printing inks for packaging materials contain polyurethane resin as a binder resin. Polypropylene glycol or polyester polyol is used as a polyol component, which is a main raw material of polyurethane resin. Polyurethane resins using polypropylene glycol have a significantly inferior laminate strength of the obtained printed matter compared to polyurethane resins using polyester polyol. In particular, polyurethane resins using polypropylene glycol are less suitable for extrusion lamination.

[0005] The present invention has been made in view of the above-mentioned conventional problems, and has an object to provide a printing ink composition for laminating flexible packaging, which has excellent storage stability and excellent physical properties such as suitability for extrusion lamination and blocking resistance, a lamination method, and a method for producing a laminated product. [Means for solving the problem]

[0006] As a result of intensive research to solve the above problems, the present inventors have found that the above problems can be solved by adopting a non-cyclic diamine as the diamine component in the polyurethane resin and adopting a polypropylene glycol having a predetermined number average molecular weight as the polyol component, and have completed the present invention. That is, the printing ink composition for flexible packaging laminate, the lamination method, and the manufacturing method of the laminated product of the present invention, which solve the above problems, mainly include the following configurations.

[0007] (1) A printing ink composition for a flexible packaging laminate comprising: a pigment; a binder resin containing a polyurethane resin; and an organic solvent; the polyurethane resin contains an acyclic diamine as a diamine component and a polyol component containing polypropylene glycol, the acyclic diamine content in the diamine component being 30% or more by molar ratio; and the polypropylene glycol having a number average molecular weight of 300 to 3,300.

[0008] According to such a constitution, the printing ink composition for flexible packaging laminate has excellent physical properties such as extrusion lamination suitability and blocking resistance, etc. In addition, the printing ink composition for flexible packaging laminate has excellent storage stability.

[0009] (2) The printing ink composition for flexible packaging laminate according to (1), wherein the number of atoms connecting the two nitrogen atoms in the non-cyclic diamine is 2 to 6.

[0010] According to this constitution, the printing ink composition for flexible packaging laminate has excellent suitability for extrusion lamination.

[0011] (3) The printing ink composition for flexible packaging laminates according to (1) or (2), wherein the content of the polypropylene glycol in the polyol component is 95 mass% or more.

[0012] According to this constitution, the printing ink composition for flexible packaging laminate has excellent doctor cutability and is therefore highly suitable for high-speed printing.

[0013] (4) A lamination method comprising printing on a plastic film with the printing ink composition for flexible packaging laminate described in any one of (1) to (3), and then laminating a film-like or molten polymer by a dry lamination method or an extrusion lamination method.

[0014] According to this configuration, the laminated product obtained can be easily produced by lamination, and has excellent physical properties such as blocking resistance.

[0015] (5) a printing layer forming step of printing a printing ink composition for flexible packaging laminate according to any one of (1) to (3) on a plastic film to form a printing layer; A method for producing a laminated product, comprising a lamination step of laminating a film-like or molten polymer on the printed layer by dry lamination or extrusion lamination.

[0016] According to this configuration, the laminated product obtained can be easily produced by lamination, and has excellent physical properties such as blocking resistance. Effect of the Invention

[0017] According to the present invention, it is possible to provide a printing ink composition for laminating flexible packaging, which has excellent storage stability and excellent physical properties such as suitability for extrusion lamination and blocking resistance, a lamination method, and a method for producing a laminated product. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] <Printing ink composition for flexible packaging laminate> A printing ink composition for flexible packaging laminates (hereinafter also referred to as ink composition) according to one embodiment of the present invention contains a pigment, a binder resin containing a polyurethane resin, and an organic solvent. The polyurethane resin contains a non-cyclic diamine as a diamine component and polypropylene glycol as a polyol component. The content of the non-cyclic diamine in the diamine component is 30% or more by molar ratio. The number average molecular weight of the polypropylene glycol is 300 to 3300. Each of these will be described below.

[0019] (Pigments) Examples of pigments include inorganic, organic and extender pigments that can be generally used in ink compositions containing organic solvents. Examples of inorganic pigments include titanium oxide, red iron oxide, antimony red, cadmium red, cadmium yellow, cobalt blue, Prussian blue, ultramarine blue, carbon black, graphite, etc. Examples of organic pigments include soluble azo pigments, insoluble azo pigments, azo lake pigments, condensed azo pigments, copper phthalocyanine pigments, condensed polycyclic pigments, etc. Examples of extender pigments include calcium carbonate, kaolin clay, barium sulfate, aluminum hydroxide, talc, etc.

[0020] The pigment content is not particularly limited. For example, the pigment content in the ink composition is preferably 0.5% by mass or more, and more preferably 5% by mass or more. The pigment content is preferably 50% by mass or less, and more preferably 40% by mass or less. When the pigment content is within the above range, the resulting printed matter has sufficient color development and excellent printability.

[0021] (binder resin) The binder resin includes a polyurethane resin. The polyurethane resin includes a non-cyclic diamine as a diamine component and a polyol component including polypropylene glycol. Specifically, the polyurethane resin of the present embodiment is a polyurethane resin obtained by reacting a urethane prepolymer having an isocyanate group at a terminal, which is obtained by reacting a high molecular diol including polypropylene glycol with a polyisocyanate, with a polyamine component including a non-cyclic diamine.

[0022] The method for producing the polyurethane resin is not particularly limited. As an example, the polyurethane resin can be obtained by the following methods (1) to (4).

[0023] (1) A method in which a polyamine component is added as a chain extender to a urethane prepolymer having isocyanate groups at its terminals, which is obtained by reacting a high molecular diol containing polypropylene glycol with a polyisocyanate, and chain extension is carried out to obtain a urethane prepolymer having isocyanate groups at its terminals. Thereafter, a monoamino alcohol component is reacted as a reaction terminator, and then a reaction terminator which is a polyamine component is reacted.

[0024] (2) A method in which a polyamine component is added as a chain extender to a urethane prepolymer having isocyanate groups at its terminals, which is obtained by reacting a high molecular diol containing polypropylene glycol with a polyisocyanate, and chain extension is performed to obtain a urethane prepolymer having isocyanate groups at its terminals. After that, a monoamino alcohol component and a polyamine component are simultaneously added as reaction terminators to cause the reaction.

[0025] (3) A method in which a urethane prepolymer having an isocyanate group at its terminal, obtained by reacting a polymeric diol containing polypropylene glycol with a polyisocyanate, is reacted with a polyamine component that acts as a chain extender and a reaction terminator, and a monoalcohol component that acts as a reaction terminator, thereby simultaneously carrying out chain extension and reaction termination to obtain a polyurethane resin.

[0026] (4) A method in which a urethane prepolymer having an isocyanate group at its terminal, obtained by reacting a polymer diol containing polypropylene glycol with a polyisocyanate, is reacted with a monoalcohol component as a reaction terminator, and then a polyamine component is added to simultaneously carry out chain extension and reaction termination, thereby obtaining a polyurethane resin.

[0027] The polyol component of the present embodiment may contain other polyol components as appropriate in addition to the above polypropylene glycol.

[0028] The other polyol component is not particularly limited. For example, the other polyol component may be a polyalkylene glycol such as polyethylene glycol, a polyether diol compound such as an alkylene oxide adduct of bisphenol A with ethylene oxide or propylene oxide, a polyester diol obtained by condensation reaction of one or more dibasic acids such as adipic acid, sebacic acid, or phthalic anhydride with one or more glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, or 3-methyl-1,5-pentanediol, or a polyester diol compound such as polycaprolactone diol.

[0029] In these methods, a polymer diol compound other than polypropylene glycol may be used in combination as appropriate. Such polymer diols include various polymer diol compounds such as polyalkylene glycols such as polyethylene glycol, polyether diol compounds such as alkylene oxide adducts of bisphenol A with ethylene oxide, propylene oxide, etc., polyester diols obtained by condensation reaction of dibasic acids such as adipic acid, sebacic acid, phthalic anhydride, etc. with glycols such as ethylene glycol, propylene glycol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, etc., and polyester diol compounds such as polycaprolactone diols.

[0030] These high molecular weight diol compounds may be used in combination with alkanediols such as 1,4-pentanediol, 2,5-hexanediol, and 3-methyl-1,5-pentanediol, and low molecular weight diol compounds such as ethylene glycol, propylene glycol, 1,4-butanediol, and 1,3-butanediol.

[0031] The number average molecular weight of the polypropylene glycol may be 300 or more, and preferably 800 or more. The number average molecular weight of the polypropylene glycol may be 3300 or less, and preferably 2200 or less. When the number average molecular weight of the polypropylene glycol is within the above range, the ink composition is less likely to gel and has excellent storage stability. In addition, the adhesive strength of the resulting coating film is excellent. The ink composition of this embodiment may contain multiple polypropylene glycols having different number average molecular weights. In this case, it is preferable that the average value of the number average molecular weight of each of the multiple polypropylene glycols is within the above number average molecular weight range.

[0032] The content of polypropylene glycol is not particularly limited. For example, the content of polypropylene glycol in the polyol component is preferably 95% by mass or more, and may be 100% by mass. When the content of polypropylene glycol is within the above range, the ink composition has excellent doctor cut-off properties and is highly suitable for high-speed printing.

[0033] The polyisocyanate used in the present embodiment is not particularly limited. For example, the polyisocyanate is obtained by mixing an aromatic diisocyanate compound such as tolylene diisocyanate, an alicyclic diisocyanate compound such as 1,4-cyclohexane diisocyanate or isophorone diisocyanate, an aliphatic diisocyanate compound such as hexamethylene diisocyanate, and an aromatic aliphatic diisocyanate compound such as α,α,α',α'-tetramethylxylylene diisocyanate.

[0034] The blending ratio of polyisocyanate and polypropylene glycol is not particularly limited. For example, the blending ratio is preferably 0.8:1 to 3.0:1, more preferably 0.9:1 to 2.0:1 in terms of the equivalent ratio of isocyanate group:hydroxyl group (isocyanate index). When the isocyanate index is within the above range, the ink composition has excellent blocking resistance and the like of the resulting printed matter.

[0035] The chain extender used in this embodiment may contain a non-cyclic diamine. The non-cyclic diamine is not particularly limited. For example, the non-cyclic diamine may be an aliphatic diamine such as ethylenediamine, propylenediamine, tetramethylenediamine, or hexamethylenediamine, a polyamine such as diethylenetriamine or triethylenetetratriamine, or a diamine having a hydroxyl group such as N-(2-hydroxyethyl)ethylenediamine, N-(2-hydroxyethyl)propylenediamine, or N,N'-di(2-hydroxyethyl)ethylenediamine.

[0036] In addition to the above non-cyclic diamines, the chain extender may also contain a cyclic diamine, such as, for example, alicyclic diamines such as isophorone diamine and 4,4'-dicyclohexylmethane diamine, aromatic diamines such as toluylene diamine, and aromatic aliphatic diamines such as xylene diamine.

[0037] In the polyurethane resin of the present embodiment, the non-cyclic diamine contained as the diamine component is preferably one in which the number of atoms connecting the two nitrogen atoms in the non-cyclic diamine is 2 or more. Also, the number of atoms connecting the two nitrogen atoms in the non-cyclic diamine is preferably 6 or less, more preferably 4 or less. When the number of atoms connecting the two nitrogen atoms is within the above range, the ink composition has excellent suitability for extrusion lamination. Such non-cyclic diamines include ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, N-(2-hydroxyethyl)ethylenediamine, N-(2-hydroxyethyl)propylenediamine, etc., and particularly preferred are ethylenediamine, propylenediamine, tetramethylenediamine, N-(2-hydroxyethyl)ethylenediamine, etc.

[0038] In the polyurethane resin of this embodiment, the content of the non-cyclic diamine in the diamine component may be 30% or more in molar ratio, preferably 50% or more, and more preferably 70% or more. The content of the non-cyclic diamine in the diamine component may be 100%, and is preferably 90% or less. By having the content of the non-cyclic diamine within the above range, the ink composition can achieve both suitability for extrusion lamination and resistance to elution.

[0039] The reaction terminator used in this embodiment is not particularly limited. For example, the reaction terminator is a polyamine compound, a monoamine compound, a monoalcohol compound, or the like. The reaction terminator used in the above method (3) is not particularly limited. For example, the reaction terminator is a polyamine compound. The compound used in the above method (4) that simultaneously performs chain extension and reaction termination is not particularly limited. These may be only the chain extenders described above, or a combination of a chain extender and a reaction terminator may be used.

[0040] In the polyurethane resin of the present embodiment, it is preferable that the reaction is stopped with the above polyamine compound so that the amine value is 1.00 to 13.00 mgKOH / g, in order to obtain excellent storage stability and pigment dispersibility. The polyamine compound is not particularly limited. For example, the polyamine compound is aliphatic diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, and hexamethylenediamine, polyamines such as diethylenetriamine and triethylenetetratriamine, and diamines having a hydroxyl group such as N-(2-hydroxyethyl)ethylenediamine and N-(2-hydroxyethyl)propylenediamine.

[0041] The reaction terminator that can be used in combination with such a polyamine compound is not particularly limited. For example, the reaction terminator is a monoamine compound, a monoalcohol compound, etc., which are known reaction terminators. Specifically, the reaction terminator is a monoalkylamine such as n-propylamine or n-butylamine, a dialkylamine such as di-n-butylamine, an alkanolamine such as monoethanolamine or diethanolamine, or a monoalcohol such as ethanol. From the viewpoint of adhesion and solubility, it is preferable to use an alkanolamine in combination with the above polyamine compound.

[0042] In addition to the above non-cyclic diamine, the reaction terminator may contain a cyclic diamine as appropriate. Examples of the cyclic diamine include alicyclic diamines such as isophorone diamine and 4,4'-dicyclohexylmethane diamine, aromatic diamines such as toluylene diamine, and aromatic aliphatic diamines such as xylene diamine.

[0043] In this embodiment, the molecular weight, chemical structure, and equivalent ratio of the components other than those described above may be appropriately adjusted based on the desired hardness of the polyurethane resin, etc.

[0044] The weight average molecular weight of the polyurethane resin in this embodiment is preferably at least 8000, and more preferably at least 14000. The number average molecular weight of the polyurethane resin is preferably at most 70000, and more preferably at most 60000. By having the content of the polyurethane resin within the above range, the ink composition can achieve both appropriate flexibility and high lamination suitability.

[0045] The content of the polyurethane resin is not particularly limited. For example, the content of the polyurethane resin in the ink composition is preferably 4% by mass or more, more preferably 6% by mass or more. The content of the polyurethane resin is preferably 30% by mass or less, more preferably 25% by mass or less. When the content of the polyurethane resin is within the above range, the ink composition has excellent pigment dispersibility, a suitable viscosity, and excellent ejection stability. The ink composition can also exhibit good print density, printability, and lamination suitability.

[0046] The amine value of the polyurethane resin is not particularly limited. For example, the amine value of the polyurethane resin is preferably 1.00 mgKOH / g or more, more preferably 1.50 mgKOH / g or more. The amine value of the polyurethane resin is preferably 13.00 mgKOH / g or less, more preferably 11.00 mgKOH / g or less. When the amine value is within the above range, the ink composition has excellent adhesion to the film and excellent lamination suitability. In addition, the ink composition has excellent blocking resistance of the coating film obtained. In this embodiment, the amine value means the amine value per 1 g of solid content, and refers to a value converted into the equivalent amount of potassium hydroxide after measuring by potentiometric titration method (for example, COMTITE (AUTO TITRATOR COM-900, BURET B-900, TITSTATION K-900), manufactured by Hiranuma Sangyo Co., Ltd.) using a 0.1 N hydrochloric acid aqueous solution.

[0047] The hydroxyl value of the polyurethane resin is not particularly limited. For example, the hydroxyl value of the polyurethane resin is preferably 0.50 mgKOH / g or more, more preferably 1.00 mgKOH / g or more. The hydroxyl value of the polyurethane resin is preferably 12.00 mgKOH / g or less, more preferably 11.00 mgKOH / g or less. When the hydroxyl value is within the above range, the ink composition has an excellent balance of resolubility, adhesion, and blocking resistance. In this embodiment, the hydroxyl value can be determined by applying the method specified in JIS K 1557-1:2007. That is, the hydroxyl group is acetylated by dissolving the polyurethane resin as a sample in a pyridine solution containing an acetylating reagent (e.g., acetic anhydride), and then the excess acetylating reagent is hydrolyzed with water, and the amount of acetic acid generated is determined by titrating with potassium hydroxide. At this time, the carboxyl groups contained in the polyurethane resin are also titrated with potassium hydroxide, so the hydroxyl value (mgKOH / g) is calculated by subtracting the acid value of the polyurethane resin from the titration result.

[0048] Returning to the explanation of the binder resin as a whole, the binder resin of this embodiment may be a polyurethane resin, and may also be a vinyl chloride / vinyl acetate copolymer, soluble nitrocellulose, cellulose acetate propionate resin, or other binder resins used in combination.

[0049] In cases where the pigment is not sufficiently dispersed by only including a polyurethane resin, or when the adhesiveness or lamination suitability of a metal deposition film or the like is to be improved, it is preferable that the ink composition is used in combination with a vinyl chloride / vinyl acetate copolymer. The vinyl chloride / vinyl acetate copolymer may be a copolymer of vinyl chloride monomer and vinyl acetate monomer that has been used in gravure printing ink compositions. Among them, the copolymer of vinyl chloride monomer and vinyl acetate monomer is preferably a vinyl chloride / vinyl acetate copolymer having a hydroxyl group, preferably having 50 to 200 hydroxyl groups, in an environmentally friendly organic solvent system of the ink. Such a vinyl chloride / vinyl acetate copolymer having a hydroxyl group can be obtained by partially saponifying the acetate ester moiety.

[0050] In the case of vinyl chloride / vinyl acetate copolymers having hydroxyl groups obtained by saponifying a portion of the acetate ester moieties, the film properties and dissolution behavior of the resin are determined by the ratio of the constituent units based on the reactive sites of vinyl chloride in the molecule (formula 1 below), the constituent units based on the reactive sites of vinyl acetate (formula 2 below), and the constituent units based on the saponification of the reactive sites of vinyl acetate (formula 3 below). In other words, the constituent units based on the reactive sites of vinyl chloride impart toughness and hardness to the resin film, the constituent units based on the reactive sites of vinyl acetate impart adhesion and flexibility, and the constituent units based on the saponification of the reactive sites of vinyl acetate impart good solubility to environmentally friendly organic solvent systems for inks.

[0051] Formula 1 -CH2-CHCl- Formula 2 -CH2-CH(OCOCH3)- Formula 3 -CH2-CH(OH)-

[0052] Specific examples of such vinyl chloride / vinyl acetate copolymers having hydroxyl groups include Solvine A, AL, TA5R, TA2, TA3, TAO, TAOL, C, CH, CN, and CNL, manufactured by Nissin Chemical Industry Co., Ltd.

[0053] The total content of the polyurethane resin and the vinyl chloride / vinyl acetate copolymer in the ink composition is preferably 5 to 20 mass %.

[0054] The ink composition of the present embodiment may contain soluble nitrocellulose and cellulose acetate propionate resin in order to improve blocking resistance.

[0055] The content of soluble nitrocellulose in the ink composition is preferably 0.1 to 2.0% by mass, and the content of cellulose acetate propionate resin in the ink composition is preferably 0.1 to 3.0% by mass.

[0056] The soluble nitrocellulose may 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 a six-membered ring of an anhydrous glucopyranose group in the natural cellulose with nitric acid groups to form a nitric acid ester. The soluble nitrocellulose that may be used in the present embodiment preferably has a nitrogen content of 10 to 13% and an average degree of polymerization of 35 to 90. Specific examples of the soluble nitrocellulose include SS1 / 2, SS1 / 4, SS1 / 8, TR1 / 16, NC RS-2, (KCNC, manufactured by KOREA CNC LTD), and the like.

[0057] Cellulose acetate propionate resin is obtained by triesterifying cellulose with acetic acid and propionic acid, followed by hydrolysis. Generally, resins with 0.6 to 2.5% by weight of acetylation, 42 to 46% by weight of propionation, and 1.8 to 5% of hydroxyl groups are commercially available. A specific example of the cellulose acetate propionate resin is cellulose acetate propionate manufactured by Kanto Chemical Co., Ltd.

[0058] Furthermore, the ink composition of the present embodiment may further contain, as other binder resins, cellulose acetate butyrate resin, acrylic resin, polyamide resin, rosin, rosin derivatives, adhesive resins, and the like, as supplementary binder resins, within a range that does not reduce performance and taking into consideration costs.

[0059] (Organic solvent) The organic solvent is blended to dissolve the pigment and the binder resin. The organic solvent is not particularly limited. For example, the organic solvent may be toluene, a ketone-based organic solvent (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), an ester-based organic solvent (methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, isobutyl acetate, etc.), an alcohol-based organic solvent (methanol, ethanol, n-propanol, isopropanol, butanol, etc.), or a hydrocarbon-based solvent (toluene, methylcyclohexane, etc.). Among these, in consideration of environmental issues and the printability and drying properties of the ink, the organic solvent is preferably a mixed solvent of an ester-based organic solvent and an alcohol-based organic solvent. In this case, the ratio of the ester-based organic solvent to the alcohol-based organic solvent is preferably in the range of ester-based organic solvent / alcohol-based organic solvent=10 / 90 to 90 / 10. The organic solvent may be used in combination with an aqueous solvent such as water as appropriate.

[0060] The content of the organic solvent in the ink composition is preferably 15% by mass or more in order to obtain an ink composition with excellent printability. The content of the organic solvent is preferably 90% by mass or less. By having the content of the organic solvent within the above range, the ink composition has excellent printability and is easy to sufficiently color.

[0061] (optional ingredient) The ink composition of the present embodiment may be blended with various additives as appropriate, such as adhesion improvers such as chlorinated polypropylene and dammar resins, anti-blocking agents such as silica particles, wax and fatty acid amides, antistatic agents, pigment dispersants, crosslinking agents such as chelating agents, lubricants, leveling agents, defoamers, inhibitors, surfactants and hard resins.

[0062] The method for producing the ink composition of the present embodiment is not particularly limited. As an example, the ink composition can be prepared by mixing and stirring the pigment, the binder resin, the organic solvent, and various optional components, and then grinding the mixture using various grinding machines, such as a bead mill, a ball mill, a sand mill, an attritor, a roll mill, or a pearl mill.

[0063] When the ink composition is used in gravure printing, it is preferable to dilute it with an organic solvent so that the viscosity is appropriate for the printing conditions at the atmospheric temperature during printing, specifically, until the Zahn cup No. 3 outflow time is 12 to 23 seconds / 25°C, or about 14 to 16 seconds / 25°C in high-speed printing.

[0064] The obtained ink composition is printed on an adherend such as various plastic films for flexible packaging to form a printed layer (printed layer forming step). Examples of plastic films include oriented and non-oriented polyolefins such as polyethylene and polypropylene, polyester, nylon, cellophane, vinylon, etc., in particular, in that they can be printed integrally with the packaging material.

[0065] The obtained printed matter is made into a bag, laminated by various lamination methods, and can be used as a laminated product such as a packaging container for food, etc. Examples of lamination methods that can be used for the above-mentioned packaging bag include an extrusion lamination method in which an anchor coating agent is applied to the surface of the printed matter and then a molten polymer is laminated thereon, and a dry lamination method in which an adhesive is applied to the surface of the printed matter and then a polymer is laminated on a film (lamination process).

[0066] As described above, according to the present embodiment, the ink composition has excellent storage stability. In addition, the printing ink composition for flexible packaging laminate has excellent physical properties such as suitability for extrusion lamination and blocking resistance. In addition, the obtained laminated product can be easily produced by lamination. In addition, the laminated product has excellent physical properties such as blocking resistance. EXAMPLES

[0067] The present invention will be described in more detail below with reference to the following examples. The present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass". The figures for the amounts of each material in the tables are "parts by mass".

[0068] The raw materials used are shown below. PB15:4 (Pigment Blue 15:4) Titanium oxide (rutile type titanium oxide, silica alumina treatment, average particle size 0.3 μm) Mixed solvent A (propyl acetate / isopropyl alcohol = 75 / 25) Mixed solvent B (ethyl acetate / propyl acetate / isopropyl alcohol = 50 / 25 / 25)

[0069] <Production Example 1: Synthesis of polyurethane resin> In a four-neck flask equipped with a stirrer, a cooling tube, and a nitrogen gas inlet tube, 100.0 parts by mass of polypropylene glycol having an average molecular weight of 2,000 and 16.7 parts by mass of isophorone diisocyanate were charged, and the mixture was reacted at 100 to 105 ° C for 6 hours while introducing nitrogen gas. The mixture was allowed to cool to near room temperature, and 276.4 parts by mass of mixed solvent A was added, followed by adding 1.5 parts by mass of ethylenediamine and 0.3 parts by mass of monoethanolamine to react, to obtain a polyurethane resin varnish of Production Example 1 (solid content 30% by mass, amine value 2.13, hydroxyl value 2.37). The amine value and hydroxyl value were calculated by the following method. Hydroxyl value The hydroxyl value was determined by applying the method specified in JIS K 1557-1:2007. That is, the hydroxyl groups were acetylated by dissolving the polyurethane resin sample in a pyridine solution containing an acetylating agent (acetic anhydride), and then the excess acetylating agent was hydrolyzed with water, and the amount of acetic acid generated was determined by titrating with potassium hydroxide. At this time, the carboxyl groups contained in the polyurethane resin were also titrated with potassium hydroxide, so the hydroxyl value (mgKOH / g) was calculated by subtracting the acid value of the polyurethane resin from the titration result. Amine number The amine value means the amine value per 1 g of solid content, and was measured by potentiometric titration (COMTITE AUTO TITRATOR COM-900, BURET B-900, TITSTATION K-900, manufactured by Hiranuma Sangyo Co., Ltd.) using a 0.1 N aqueous hydrochloric acid solution, and then converted into the equivalent amount of potassium hydroxide.

[0070] <Production Examples 2 to 11, Comparative Production Examples 1 to 3> The polyurethane resins of Production Examples 2 to 11 and Comparative Production Examples 1 to 3 were prepared in the same manner as Production Example 1, except that the formulation was changed to that shown in Table 1 (unit: parts by mass). In Table 1, the molecular weight (number average molecular weight) of the polyester polyol was calculated based on the structures and hydroxyl values ​​of the polycarboxylic acid and polyol constituting the polyester. The molecular weight (number average molecular weight) of the polyol such as polypropylene glycol was calculated based on the structures and hydroxyl values ​​of the monomers constituting the polyol.

[0071] [Table 1]

[0072] Example 1: Preparation of ink composition The pigment and the polyurethane resin varnish obtained in Production Example 1 were kneaded using a paint conditioner manufactured by Red Devil Co., Ltd., and mixed solvent B was added to obtain an ink composition.

[0073] <Examples 2 to 12 and Comparative Examples 1 to 3> Ink compositions of Examples 2 to 12 and Comparative Examples 1 to 3 were prepared in the same manner as in Example 1, except that the formulation was changed to that shown in Table 2 (unit: parts by mass).

[0074] [Table 2]

[0075] 100 parts by mass of each of the ink compositions of Examples 1 to 12 and Comparative Examples 1 to 3 was diluted with mixed solvent B, and the viscosity was adjusted to 15 seconds using a Zahn Cup No. 3 manufactured by Rigo Co., Ltd. Using a gravure printing machine, each of the diluted ink compositions was printed on the treated surface of each type of film under the following conditions, followed by drying to obtain printed matter. (Printing method / printing conditions) Printing room environment: Temperature 25°C, humidity 50% Coating machine: Gravure printing machine Coating speed: 150m / min Printing plate: Direct 175 lines 28μm solid plate Drying temperature: 55℃ (Various films) PET: Polyethylene terephthalate film with corona discharge treatment on one side, Toyobo Co., Ltd., E-5101, thickness 12 μm OPP: Corona discharge treated biaxially oriented polypropylene film, Toyobo Co., Ltd., P-2161, thickness 25 μm

[0076] The performance of the ink compositions of Examples 1 to 12 and Comparative Examples 1 to 3 and the prints obtained using them were evaluated by the following methods. The evaluation results are shown in Table 2.

[0077] <Ink storage stability> The ink composition obtained above was placed in a glass bottle and stored at an ambient temperature of 60° C. for 14 days, after which the storage stability of the ink was evaluated based on the presence or absence of pigment sedimentation. (Evaluation Criteria) ◯: No sedimentation was observed, and the storage stability of the ink composition base material was good. ×: Sedimentation was observed, and the storage stability of the ink composition base material was poor. <Blocking resistance> The printed surface of each film print one day after printing with each ink composition was combined with the untreated surface of each film, and the ink composition was weighed at 400 g / cm 2 After leaving the film at 40° C. for 12 hours under a load of 1000 μg / cm2, the blocking resistance was evaluated based on the state of each film when it was peeled off. (Evaluation Criteria) ○: There is absolutely no resistance when the film is peeled off, and the ink does not peel off from the printed surface. △: There is some resistance when peeling off the film, but the ink does not peel off from the printed surface. ×: There is resistance when peeling off the film, and the ink peels off from the printed surface. <Extrusion laminate strength> Each printed matter of Examples 1 to 12 and Comparative Examples 1 to 3 was treated with an imine-based anchor coating agent (Epomin P-1000) or an isocyanate-based anchor coating agent (Takelac A-3210 / Takelac A-3072), and then laminated with molten polyethylene using an extrusion laminator to obtain a laminated product. These laminated products were cut into 15 mm widths after aging at 40°C for 1 day, and the T-type peel strength (g / 15 mm) was measured as the extrusion laminate strength using a peel tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd.). The results are shown in Table 2. OPP film / imine anchor coating agent (Evaluation Criteria) ○: 1N / 15mm or more. △: 0.5N / 15mm or more, less than 1N / 15mm. ×: Less than 0.5N / 15mm. ·PET film / imine anchor coating agent ○: 5N / 15mm or more. △: 3N / 15mm or more, less than 5N / 15mm. ×: Less than 3N / 15mm. ·PET film / isocyanate anchor coating agent ○: 5N / 15mm or more. △: 3N / 15mm or more, less than 5N / 15mm. ×: Less than 3N / 15mm.

[0078] As shown in Table 2, the ink compositions of Examples 1 to 12 of the present invention had excellent storage stability. In addition, the ink compositions of Examples 1 to 12 of the present invention had excellent extrusion lamination properties, and the obtained laminated products had excellent blocking resistance.

Claims

1. The ink contains a pigment, a binder resin including a polyurethane resin, and an organic solvent, The polyurethane resin contains a non-cyclic diamine as a diamine component and a polypropylene glycol as a polyol component, The content of the non-cyclic diamine in the diamine component is 30% or more by molar ratio, The polypropylene glycol has a number average molecular weight of 300 to 3,300.

2. 2. The printing ink composition for flexible packaging laminate according to claim 1, wherein the number of atoms connecting the two nitrogen atoms in the non-cyclic diamine is 2 to 6.

3. 3. The printing ink composition for flexible packaging laminates according to claim 1, wherein the content of the polypropylene glycol in the polyol component is 95 mass% or more.

4. 3. A lamination method comprising printing on a plastic film with the printing ink composition for flexible packaging laminates according to claim 1 or 2, and then laminating a film-like or molten polymer on the printed surface by dry lamination or extrusion lamination.

5. A printing layer forming step of printing a printing ink composition for flexible packaging laminate according to claim 1 or 2 on a plastic film to form a printing layer; A method for producing a laminated product, comprising a lamination step of laminating a film-like or molten polymer on the printed layer by dry lamination or extrusion lamination.

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