Core-shell type emulsion for water-based flexible packaging printing and method for producing the same

Abstract

To provide a core shell-type emulsion for aqueous soft package printing excellent in adhesion to paper and film.SOLUTION: The core shell-type emulsion for aqueous soft package printing includes: (A) at least one compound selected from the group consisting of a dimer acid, a trimer acid, a polyamide compound having an acid value obtained by reacting a dimer acid and / or a trimer acid with a polyvalent amine, and a polyester compound having an acid value obtained by reacting a dimer acid and / or a trimer acid with a polyhydric alcohol; (B) a water-soluble resin which is a polymer of an ethylenic unsaturated monomer containing a carboxyl group-containing ethylenic unsaturated monomer; and (C) an emulsion polymerization product of an ethylenic unsaturated monomer (c), where the acid value of the compound (A) is 80 mgKOH / g or higher, the compound (A) is contained in an emulsion solid content by 0.5-40 mass%, the compound (A) and the water-soluble resin (B) constitute a shell part, and the emulsion polymerization product (C) constitutes a core part.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a core-shell type aqueous emulsion for flexible packaging printing, which has excellent adhesion to paper and films and uses specific polycarboxylic acids and / or their derivatives.

Background Art

[0002] Materials for packaging foods and daily necessities include paper, plastic films, etc. Solvent-based inks are mainly used for printing these materials. In recent years, there has been an increasing demand for water-based inks that do not use organic solvents as inks for addressing environmental issues.

[0003] However, compared with solvent-based inks, water-based inks have inferior wettability to films. As a result, the ink is repelled and a good printed product cannot be obtained, and there is a problem that the adhesion of the ink to the film is not sufficient.

[0004] In order to solve these above-mentioned problems, Patent Document 1 has examined a water-based ink containing an acrylic resin obtained by copolymerizing with a monomer having both an amide group and a vinyl group.

[0005] In addition, Patent Document 2 has examined an aqueous emulsion containing an acrylic-urethane resin and an organic polyhydrazide compound.

[0006] However, in Patent Document 1, the water resistance, solvent resistance, and adhesion to the substrate are still insufficient. In Patent Document 2, although the adhesion and water resistance are improved, there are new problems such as poor ink drying on the substrate caused by hydrazide.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] An object of the present invention is to provide an aqueous core-shell type emulsion for flexible packaging, which has excellent adhesion to paper and films.

Means for Solving the Problems

[0009] The present inventors have found that a core-shell type emulsion containing a specific polyvalent carboxylic acid and / or its derivative and a specific water-soluble resin and a specific polyvalent carboxylic acid and / or its derivative on the shell side has excellent adhesion to paper and films, and completed the present invention.

[0010] That is, the present invention is <1>An aqueous core-shell type emulsion for flexible packaging printing, comprising at least one compound selected from the group consisting of (A) a dimer acid (a-1), a trimer acid (a-2), a polyamide compound (a-3) having an acid value obtained by reacting a dimer acid (a-1) and / or a trimer acid (a-2) with a polyvalent amine, and a polyester compound (a-4) having an acid value obtained by reacting a dimer acid (a-1) and / or a trimer acid (a-2) with a polyvalent alcohol, (B) a water-soluble resin which is a polymer of an ethylenically unsaturated monomer containing a carboxy group-containing ethylenically unsaturated monomer, and (C) an emulsion polymer of an ethylenically unsaturated monomer (c), wherein the acid value of the compound (A) is 80 mgKOH / g or more, the compound (A) is contained in the emulsion solid content in an amount of 0.5 to 40% by mass, and the compound (A) and the water-soluble resin (B) form a shell part and the emulsion polymer (C) forms a core part. <2>The aqueous core-shell type emulsion for flexible packaging printing according to <1> above, wherein the water-soluble resin (B) is a polymer of a monomer mixture containing an aromatic-containing ethylenically unsaturated monomer and / or an alicyclic structure-containing ethylenically unsaturated monomer. <3>The aqueous core-shell type emulsion for aqueous flexible packaging printing according to <1>, characterized in that the solubility of the ethylenically unsaturated monomer (c) in water at 20 °C is less than 3 g / 100 g of water. <4>A binder resin for printing ink for aqueous flexible packaging, characterized by containing the aqueous core-shell type emulsion for aqueous flexible packaging printing according to any one of <1> to <3>. <5>A coating varnish for aqueous flexible packaging printing, characterized by containing the aqueous core-shell type emulsion for aqueous flexible packaging printing according to any one of <1> to <3>. <6>A method for producing an aqueous core-shell type emulsion for aqueous flexible packaging printing, which is obtained by emulsion polymerization of an ethylenically unsaturated monomer (c) in water in the presence of a water-soluble resin which is a polymer of an ethylenically unsaturated monomer containing a carboxy group-containing ethylenically unsaturated monomer and at least one compound selected from the group consisting of (A) a polyamide compound (a-3) having an acid value obtained by reacting a dimer acid (a-1), a trimer acid (a-2), a dimer acid (a-1) and / or a trimer acid (a-2) with a polyvalent amine, and a polyester compound (a-4) having an acid value obtained by reacting a dimer acid (a-1) and / or a trimer acid (a-2) with a polyvalent alcohol, wherein the acid value of the compound (A) is 80 mgKOH / g or more, and the compound (A) is contained in the emulsion solid content in an amount of 0.5 to 40% by mass. <7>The method for producing an aqueous core-shell type emulsion for aqueous flexible packaging printing according to <6>, characterized in that the water-soluble resin (B) is a polymer of a monomer mixture containing an aromatic group-containing ethylenically unsaturated monomer and / or an alicyclic structure-containing ethylenically unsaturated monomer. <8>The method for producing an aqueous core-shell type emulsion for aqueous flexible packaging printing according to <6>, characterized in that the solubility of the ethylenically unsaturated monomer (c) in water at 20 °C is less than 3 g / 100 g of water. is.

Advantages of the Invention

[0011] The core-shell type emulsion for aqueous flexible packaging printing provided by the present invention has excellent adhesion to any substrate such as paper and film, and thus can be suitably used as a raw material for a binder for printing ink or a coating varnish.

Embodiments for Carrying Out the Invention

[0012] The core-shell type emulsion for aqueous flexible packaging printing of the present invention contains at least water, (A) at least one compound selected from the group consisting of dimer acid (a-1), trimer acid (a-2), a polyamide compound (a-3) having an acid value obtained by reacting dimer acid (a-1) and / or trimer acid (a-2) with a polyvalent amine, and a polyester compound (a-4) having an acid value obtained by reacting dimer acid (a-1) and / or trimer acid (a-2) with a polyhydric alcohol (hereinafter referred to as compound (A)), (B) a water-soluble resin which is a polymer of an ethylenically unsaturated monomer containing a carboxy group-containing ethylenically unsaturated monomer (hereinafter referred to as water-soluble resin (B)), and (C) an emulsion polymer of an ethylenically unsaturated monomer (c) (hereinafter referred to as emulsion polymer (C)).

[0013] Compound (A) is at least one compound selected from the group consisting of dimer acid (a-1), trimer acid (a-2), a polyamide compound (a-3) having an acid value obtained by reacting dimer acid (a-1) and / or trimer acid (a-2) with a polyvalent amine, and a polyester compound (a-4) having an acid value obtained by reacting dimer acid (a-1) and / or trimer acid (a-2) with a polyhydric alcohol. Compound (A) has an excellent adhesion effect to the substrate, and since dimer acid (a-1) and trimer acid (a-2) themselves are plant-derived as described later, it can be said that they are environmentally friendly materials.

[0014] Dimer acid (a-1) is a dibasic acid obtained by polymerizing purified vegetable fatty acids obtained from drying oils, semi-drying oils, etc. As typical raw materials, unsaturated fatty acids with 18 carbon atoms such as oleic acid, linoleic acid, and linolenic acid are used, so the main component becomes a dicarboxylic acid with 36 carbon atoms. In addition to the main component, dimer acid contains trimer acid and monomer acid. The content of monomer acid is 0 to 15% by mass based on 100% by mass of the total of monomer acid, dimer acid, and trimer acid; the content of dimer acid is 70 to 100% by mass based on 100% by mass of the total of monomer acid, dimer acid, and trimer acid; the content of trimer acid is preferably 0 to 15% by mass based on 100% by mass of the total of monomer acid, dimer acid, and trimer acid.

[0015] For dimer acid (a-1), commercially available dimer acid can be used. Specific examples of commercially available dimer acid include the "PRIPOL (registered trademark)" series manufactured by Croda Japan Co., Ltd., the "Halimer" series manufactured by Harima Kasei Co., Ltd., the "EMPOL (registered trademark)" series manufactured by BASF Japan Co., Ltd., the "Tsunodime (registered trademark)" series manufactured by Tsukuno Food Industry Co., Ltd., and the like.

[0016] Also, trimer acid (a-2) is a purified product of the trimer acid component contained in dimer acid. The content of monomer acid in trimer acid is 0 to 10% by mass based on 100% by mass of the total of monomer acid, dimer acid, and trimer acid; the content of dimer acid is 20 to 40% by mass based on 100% by mass of the total of monomer acid, dimer acid, and trimer acid; the content of trimer acid is preferably 50 to 80% by mass based on 100% by mass of the total of monomer acid, dimer acid, and trimer acid.

[0017] For trimer acid (a-2), commercially available trimer acid can be used. Examples of commercially available trimer acid include "Tsunodime (registered trademark) 346" manufactured by Tsukuno Food Industry Co., Ltd.

[0018] Further, as the compound (A), a polyamide compound (a-3) having an acid value obtained by reacting the above-described dimer acid (a-1) and / or trimer acid (a-2) with a polyamine can also be used.

[0019] Examples of the polyamine used in the polyamide compound (a-3) include ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, polyethylene polyamines having higher molecular weights than these, meta-xylylenediamine, isophoronediamine, 3,3'-dimethyl-4,4'-diaminodicyclohexylmethane, 4,4'-diaminodicyclohexylmethane, 2,4'-diaminodicyclohexylmethane, 1,2-diaminopropane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, bis-(3-aminopropyl)amine, N,N'-bis-(3-aminopropyl)-1,2-diaminoethane, 1,2-diaminocyclohexane, 1,3-diaminocyclohexane, 1,4-diaminocyclohexane, N-(2-aminoethyl)piperazine, N-(2-aminobutyl)piperazine, N,N-bis(2-aminoethyl)piperazine, and N,N-bis(3-aminopropyl)piperazine. In addition, compositions obtained by partially N-methylating diethylenetriamine and the like can be mentioned. These can be used alone or in combination. Among these, ethylenediamine and diethylenetriamine are preferred because of their high versatility and easy availability.

[0020] Furthermore, as the compound (A), a polyester compound (a-4) having an acid value obtained by reacting the above-described dimer acid (a-1) and / or trimer acid (a-2) with a polyalcohol can also be used.

[0021] Examples of the polyhydric alcohol used in the polyester compound (a-4) include glycols such as ethylene glycol, propylene glycol, diethylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propanediol, 1,5-pentamethyl glycol, neopentyl glycol, 3-methyl-1,5-pentanediol, 1,6-hexamethylene glycol, bishydroxyethoxybenzene or p-xylene glycol. Class and group Examples of the polyhydroxy compounds include glycerin, trimethylolpropane, hexanetriol, triethanolamine, pentaerythritol, etc. These may be used alone or in combination. Among these, propylene glycol and diethylene glycol are preferred because of their high versatility and easy availability.

[0022] The compound (A) may have an acid value such that it can be dissolved or dispersed in water as a salt completely or partially neutralized with an alkaline substance. However, in order to be stably dispersed in the shell part, the acid value is preferably 80 mgKOH / g or more. Examples of the alkaline substance include ammonia and organic amines such as methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, propylamine, butylamine, monoethanolamine, diethanolamine, propanolamine, dimethylethanolamine, methyldiethanolamine, morpholine; and alkali metals such as sodium hydroxide and potassium hydroxide. These can be used alone or in combination of two or more. Among these, ammonia and sodium hydroxide are preferred from the viewpoints of emulsion handling and adhesion to the substrate. It is desirable to add the alkaline substance in an amount of 50 to 150 equivalent% based on the acid value.

[0023] The water-soluble resin (B) is a salt obtained by completely or partially neutralizing the acid groups of a resin derived from a carboxy group-containing ethylenically unsaturated monomer with an alkaline substance and solubilized in water. By using the water-soluble resin (B) in the shell portion of the core-shell type emulsion for aqueous flexible packaging printing, it becomes excellent in adhesion to the substrate compared to when using a low-molecular surfactant. In particular, from the viewpoint of adhesion, it is preferably a polymer of a monomer mixture containing a carboxy group-containing ethylenically unsaturated monomer, an aromatic-containing ethylenically unsaturated monomer, and / or an alicyclic structure-containing ethylenically unsaturated monomer as the ethylenically unsaturated monomer.

[0024] Examples of the carboxy group-containing ethylenically unsaturated monomer include acrylic acid and methacrylic acid.

[0025] Examples of the aromatic-containing ethylenically unsaturated monomer include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, m-methylstyrene, vinylnaphthalene, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxytetraethylene glycol (meth)acrylate, phenoxyhexaethylene glycol (meth)acrylate, phenyl (meth)acrylate, and the like.

[0026] Examples of the alicyclic structure-containing ethylenically unsaturated monomer include cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclodecyl (meth)acrylate, and cyclododecyl (meth)acrylate.

[0027] Examples of other ethylenically unsaturated monomers include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and benzyl (meth)acrylate; and (meth)acrylic acid esters having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate. In addition to the above-mentioned ethylenically unsaturated monomers, as long as the effects of the present invention are not inhibited, ethylenically unsaturated monomers having acid groups other than carboxyl groups, such as ethylenically unsaturated monomers containing phosphate ester groups, and bifunctional or higher-functional ethylenically unsaturated monomers such as ethylene glycol di(meth)acrylate and diethylene glycol di(meth)acrylate may be included in the monomer composition to be copolymerized.

[0028] The water-soluble resin (B) can be obtained by a known polymerization method. For example, the resin is polymerized by dropping a mixture of the ethylenically unsaturated monomers together with a suitable polymerization initiator at a reaction temperature suitable for polymerization in the range of 60 to 200 °C using a reaction solvent suitable for the reaction, and then the reaction solvent is distilled off as necessary, and an alkaline substance is added to make an aqueous solution as an alkali salt. Examples of such methods include this method.

[0029] As the polymerization initiator, various known polymerization initiators such as various azo-based polymerization initiators and organic peroxides can be used according to the reaction solvent and reaction temperature. The water-soluble resin (B) only needs to have an acid value such that it can be solubilized in water as an alkali salt, but from the viewpoint of the stability of the core-shell type emulsion for aqueous flexible packaging printing of the present invention, it is preferably 50 to 350 mgKOH / g.

[0030] Examples of the alkaline substance include the same alkaline substances used for the compound (A) described above. The addition amount of the alkaline substance is desirably added so as to be 50 to 150 equivalent% with respect to the acid value of the water-soluble resin (B).

[0031] As the ethylenically unsaturated monomer (c) constituting the emulsion polymer (C), in addition to the ethylenically unsaturated monomer constituting the water-soluble resin (B), vinyl compounds such as vinyl acetate and alkyl vinyl ether; epoxy group-containing monomers such as glycidyl (meth)acrylate and 3,4-epoxycyclohexyl (meth)acrylate can be mentioned. Among these, considering the balance of hydrophilicity and hydrophobicity of the emulsion that affects the uniformity of the coating film, the ethylenically unsaturated monomer (c) constituting the emulsion polymer (C) is preferably an ethylenically unsaturated monomer having a solubility in water at 20 °C of less than 3 g / 100 g. More preferably, styrene (solubility in water: 0.1 g / 100 g water or less), methyl methacrylate (solubility in water: 1.0 g / 100 g water), ethyl acrylate (solubility in water: 1.5 g / 100 g water), ethyl methacrylate (solubility in water: 0.4 g / 100 g water), butyl acrylate (solubility in water: 0.1 g / 100 g water), butyl methacrylate (solubility in water: 0.1 g / 100 g water or less), 2-ethylhexyl (meth)acrylate (solubility in water: 0.1 g / 100 g water or less), benzyl (meth)acrylate (solubility in water: 0.1 g / 100 g water or less), glycidyl methacrylate (solubility in water: 2.3 g / 100 g water). The emulsion polymer (C) can be obtained by subjecting one or a combination of two or more of these to emulsion polymerization described later.

[0032] The core-shell type emulsion for aqueous flexible packaging printing of the present invention is an emulsion in which particles having a core-shell type structure composed of a hydrophilic shell part and a hydrophobic core part are stably dispersed in water. Specifically, the compound (A) and the water-soluble resin (B) constitute the shell part, and the emulsion polymer (C) constitutes the core part. When the compound (A) is introduced into the core part, the adhesion deteriorates. Also, in the type where the compound (A) is outside the core-shell emulsion, that is, the compound (A) is mixed with the core-shell emulsion composed of the water-soluble resin (B) and the emulsion polymer (C), separation occurs over time (as a result, there is a risk of adversely affecting the ink properties and coating suitability).

[0033] The polymerization method of the core-shell type emulsion for aqueous flexible packaging printing of the present invention is not particularly limited. For example, it can be obtained by dropping an ethylenically unsaturated monomer (c) constituting the emulsion polymer (C) into an aqueous solution containing the compound (A) and the water-soluble resin (B) and carrying out emulsion polymerization. As another method, it can be obtained by preliminarily mixing an aqueous solution containing the compound (A) and the water-soluble resin (B) with the ethylenically unsaturated monomer (c) constituting the emulsion polymer (C) to form monomer micelles and then carrying out emulsion polymerization.

[0034] Examples of the polymerization initiator used in the emulsion polymerization include known water-soluble and oil-soluble polymerization initiators, and one or more of these can be used in combination.

[0035] The core-shell type emulsion for aqueous flexible packaging printing of the present invention can be appropriately set the ratios of the components (A) to (C) arbitrarily according to various physical properties required for inks and coating varnishes within the range where there are no problems with emulsion stability, handling during production, and storage stability of the product. Usually, based on the total amount of the components (A) to (C), the component (A) is 0.5 to 40% by mass, the component (B) is 5 to 60% by mass, and the component (C) is 39.5 to 80% by mass. From the viewpoint of adhesion, preferably, the component (A) is 10 to 40% by mass, the component (B) is 10 to 50% by mass, and the component (C) is 40 to 80% by mass, and more preferably, the component (A) is 20 to 40% by mass, the component (B) is 10 to 40% by mass, and the component (C) is 40 to 70% by mass.

[0036] In the core-shell type emulsion for aqueous flexible packaging printing of the present invention, various additives such as surfactants, defoamers, preservatives, leveling agents, rust inhibitors, lubricants (waxes), freeze stabilizers, fillers, etc., and other resin varnishes, emulsions, organic solvents, etc. can be added within the range that does not affect the effects of the present invention.

[0037] When the core-shell type emulsion for aqueous flexible packaging printing of the present invention is used in ink, it is added and used as a binder resin in a dispersion in which a pigment is dispersed with a pigment dispersant. When it is used as a coating varnish, it can be obtained by adding the above-mentioned various additives and the like to the core-shell type emulsion for aqueous flexible packaging printing according to the required physical properties.

Examples

[0038] Hereinafter, examples of the present invention will be described. Note that the present invention is not limited to these examples.

[0039] <Synthesis of Compound (A)> (Synthesis Example 1) 495 g of dimer acid (A1) was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser, and a nitrogen inlet tube. After nitrogen substitution, 13.1 g of ethylenediamine was added dropwise over 10 minutes while stirring. Then, the internal temperature was raised to 170 °C, and 7.8 g of water was removed. This was designated as dimer acid polyamide (A3). The acid value of the obtained dimer acid polyamide (A3) was 150 mgKOH / g.

[0040] (Synthesis Example 2) 489 g of dimer acid (A1) was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser, and a nitrogen inlet tube. After nitrogen substitution, 26.2 g of ethylenediamine was added dropwise over 10 minutes while stirring. Then, the internal temperature was raised to 170 °C, and 15.7 g of water was removed. This was designated as dimer acid polyamide (A4). The acid value of the obtained dimer acid polyamide (A4) was 80 mgKOH / g.

[0041] (Synthesis Example 3) 495 g of dimer acid (A1) was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser tube, and a nitrogen inlet tube. After nitrogen substitution, 22.5 g of diethylenetriamine was added dropwise over 15 minutes while stirring. Thereafter, the internal temperature was raised to 170°C, and 7.9 g of water was removed. This was designated as dimer acid polyamide (A5). The acid value of the obtained dimer acid polyamide (A5) was 145 mgKOH / g.

[0042] (Synthesis Example 4) 470 g of dimer acid (A1) was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser tube, and a nitrogen inlet tube. After nitrogen substitution, 44.5 g of diethylene glycol was charged while stirring, and then the internal temperature was raised to 170°C, and 15.2 g of water was removed. This was designated as dimer acid polyester (A6). The acid value of the obtained dimer acid polyester (A6) was 150 mgKOH / g.

[0043] (Synthesis Example 5) 495 g of dimer acid (A1) was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser tube, and a nitrogen inlet tube. After nitrogen substitution, 16.6 g of propylene glycol was charged while stirring, and then the internal temperature was raised to 170°C, and 7.9 g of water was removed. This was designated as dimer acid polyester (A7). The acid value of the obtained dimer acid polyester (A7) was 146 mgKOH / g.

[0044] (Comparative Synthesis Example 1) 486 g of dimer acid (A1) was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser tube, and a nitrogen inlet tube. After nitrogen substitution, 34.7 g of ethylenediamine was added dropwise over 10 minutes while stirring. Thereafter, the internal temperature was raised to 170°C, and 20.1 g of water was removed. This was designated as dimer acid polyamide (RA1). The acid value of the obtained dimer acid polyamide (RA1) was 40 mgKOH / g.

[0045] (Comparative Synthesis Example 2) 400 g of adipic acid (AA) was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux cooling pipe, and a nitrogen introduction pipe. After nitrogen substitution, 41.0 g of ethylenediamine was added dropwise over 10 minutes while stirring. Then, the internal temperature was raised to 170 °C, and 36.0 g of water was removed. This was designated as polyamide (RA2). The acid value of the obtained polyamide (RA2) was 546 mgKOH / g.

[0046] <Synthesis of water-soluble resin (B)> (Synthesis Example 6) 1000 g of propylene glycol monomethyl ether as a solvent was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux cooling pipe, and a nitrogen introduction pipe. While stirring under nitrogen substitution, the temperature was raised to 145 °C. Next, a mixed solution of 200 g of styrene, 450 g of α-methylstyrene, 30 g of ethyl diglycol acrylate, 320 g of acrylic acid, and 10 g of ditertiary butyl peroxide as a polymerization initiator was added dropwise over 180 minutes, and then held at 145 °C for 120 minutes. The solvent was distilled off under reduced pressure to obtain an aromatic-containing acrylic resin B1 with an acid value of 249 mgKOH / g.

[0047] (Synthesis Example 7) 1000 g of propylene glycol monomethyl ether as a solvent was charged into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux cooling pipe, and a nitrogen introduction pipe. While stirring under nitrogen substitution, the temperature was raised to 145 °C. Next, a mixed solution of 650 g of methyl methacrylate, 230 g of butyl acrylate, 120 g of methacrylic acid, and 10 g of ditertiary butyl peroxide as a polymerization initiator was added dropwise over 180 minutes, and then held at 145 °C for 120 minutes. The solvent was distilled off under reduced pressure to obtain an acrylic resin B2 with an acid value of 78 mgKOH / g.

[0048] (Synthesis Example 8) 1000 g of propylene glycol monomethyl ether was charged as a solvent into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser tube, and a nitrogen inlet tube. While stirring under nitrogen substitution, the temperature was raised to 145°C. Next, a mixed solution of 100 g of styrene, 400 g of α-methylstyrene, 50 g of 2-ethylhexyl acrylate, 50 g of butyl acrylate, 400 g of acrylic acid, and 10 g of ditertiary butyl peroxide as a polymerization initiator was added dropwise over 180 minutes, and then held at 145°C for 120 minutes. The solvent was distilled off under reduced pressure to obtain an aromatic-containing acrylic resin B3 having an acid value of 311 mg KOH / g.

[0049] (Synthesis Example 9) 1000 g of propylene glycol monomethyl ether was charged as a solvent into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser tube, and a nitrogen inlet tube. While stirring under nitrogen substitution, the temperature was raised to 145°C. Next, a mixed solution of 330 g of styrene, 400 g of α-methylstyrene, 270 g of acrylic acid, and 10 g of ditertiary butyl peroxide as a polymerization initiator was added dropwise over 180 minutes, and then held at 145°C for 120 minutes. The solvent was distilled off under reduced pressure to obtain an aromatic-containing acrylic resin B4 having an acid value of 210 mg KOH / g.

[0050] (Synthesis Example 10) 1000 g of propylene glycol monomethyl ether was charged as a solvent into a reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux condenser tube, and a nitrogen inlet tube. While stirring under nitrogen substitution, the temperature was raised to 145°C. Next, a mixed solution of 590 g of methyl methacrylate, 250 g of cyclohexyl acrylate, 160 g of methacrylic acid, and 10 g of ditertiary butyl peroxide as a polymerization initiator was added dropwise over 180 minutes, and then held at 145°C for 120 minutes. The solvent was distilled off under reduced pressure to obtain an alicyclic structure-containing acrylic resin B5 having an acid value of 104 mg KOH / g.

[0051] (Synthesis of Core-Shell Emulsion) (Example 1) A reaction vessel equipped with a stirring motor, a stirring blade, a temperature sensor, a reflux cooling pipe, and a nitrogen introduction pipe was charged with 40 g of dimer acid (A1) as compound (A), 40 g of an aromatic-containing acrylic resin B1 as water-soluble resin (B), and 200 g of water, and stirred. Ammonia (15.7 g of 28% aqueous ammonia) in an amount of 100 mol% with respect to the acid value of each of compound (A) and water-soluble resin (B) was added thereto, and the temperature was raised to 80 °C and dissolved. Thereafter, after thoroughly purging the inside of the reaction vessel with nitrogen, 110 g of a mixture of ethylenically unsaturated monomers (c) (a mixed solution of 56 g of styrene and 64 g of 2-ethylhexyl acrylate), which is a raw material of the emulsion polymer (C), was added dropwise into the reaction vessel over 3 hours together with an aqueous solution prepared by dissolving 1.2 g of ammonium persulfate in 36 g of water, and emulsion polymerization was carried out at 80 °C. After completion of the reaction, the mixture was cooled to 30 °C or lower, and then water was added to adjust the solid content to 35% or more and the viscosity to be in the range of 150 to 3000 mPa·s / 25 °C, thereby obtaining a core-shell type emulsion (E1) for aqueous flexible packaging printing. In the present invention, the viscosity is the viscosity of the emulsion stock solution at 25 °C measured with a B-type viscometer, and the solid content is obtained by weighing 2 g of each emulsion into an aluminum cup, drying it at 140 °C for 1 hour, then cooling it to 25 °C in a desiccator containing a desiccant, measuring the mass of the residue, and calculating the mass ratio (%) of the non-volatile components in the emulsion.

[0052] (Examples 2 to 13) (E2 to E13), core-shell type emulsions for aqueous flexible packaging printing, were obtained in the same manner as in Example 1, except that the types and charged amounts of components (A) to (B) were changed as shown in Table 1.

[0053] (Example 14) A core-shell type emulsion (E14) for aqueous flexible packaging printing was obtained in the same manner as in Example 3, except that the composition of the mixture of ethylenically unsaturated monomers (c) was changed to 56 g of styrene and 64 g of butyl acrylate.

[0054] (Example 15) An aqueous core-shell type emulsion (E15) for flexible packaging printing was obtained in the same manner as in Example 3, except that the composition of the ethylenically unsaturated monomer (c) mixture was changed to 56 g of methyl methacrylate and 64 g of 2-ethylhexyl acrylate.

[0055] (Example 16) An aqueous core-shell type emulsion (E16) for flexible packaging printing was obtained in the same manner as in Example 3, except that the composition of the ethylenically unsaturated monomer (c) mixture was changed to 54 g of styrene, 64 g of 2-ethylhexyl acrylate, and 2 g of glycidyl methacrylate.

[0056] (Example 17) An aqueous core-shell type emulsion (E17) for flexible packaging printing was obtained in the same manner as in Example 3, except that the composition of the ethylenically unsaturated monomer (c) mixture was changed to 56 g of styrene and 64 g of methyl methacrylate.

[0057] (Comparative Examples 1, 2, 4 to 6, 8) An attempt was made to obtain an aqueous core-shell type emulsion for flexible packaging printing in the same manner as in Example 1, except that the types and amounts charged of components (A) to (C) were changed as shown in Table 1. However, the emulsion gelled during emulsion polymerization and could not be used for the following evaluation. In Comparative Example 1, the composition of the ethylenically unsaturated monomer (c) mixture was 47 g of styrene and 53 g of 2-ethylhexyl acrylate.

[0058] (Comparative Example 3) In Example 1, an emulsion of Comparative Example 3 was obtained in the same manner as in Example 1, except that compound (A) was not used and 80 g of an aromatic-containing acrylic resin B1 was used as the water-soluble resin (B).

[0059] (Comparative Example 7) An aqueous core-shell type emulsion for flexible packaging printing was obtained in the same manner as in Example 1, except that the types and amounts charged of components (A) to (C) were changed as shown in Table 1. However, the emulsion separated when allowed to stand after cooling and could not be used for the following evaluation.

[0060] (Comparative Examples 9 - 12) Emulsions of Comparative Examples 9 - 12 were obtained in the same manner as in Example 1, except that the types and amounts of components (A) - (C) were changed as shown in Table 1. Table 1 shows the types and amounts of components (A) - (C) used in each Example and Comparative Example, and Table 2 shows the physical properties of the emulsions and the emulsion solids obtained in each Example and Comparative Example, respectively.

[0061] (Method for Measuring Acid Value) For the acid value of Compound (A) and water-soluble resin (B), 0.1 g of the sample was collected, dissolved in 50 mL of THF, and after adding several drops of phenolphthalein test solution as an indicator, 0.5 mol / L potassium hydroxide ethanol solution was added dropwise with stirring until the THF solution turned light red for 30 seconds or more. Let the amount of 0.5 mol / L potassium hydroxide ethanol solution used for the dropwise addition be Y mL, The acid value was calculated as Acid value = Y × 0.5 × 56.1.

[0062] [Table 1]

[0063] (Abbreviations in the Table) Component (A) A1: Dimer acid (Tsunoda Dimer 216R, manufactured by Tsukuno Food Industry Co., Ltd.), acid value 192 mgKOH / g A2: Trimer acid (Tsunoda Dimer 346, manufactured by Tsukuno Food Industry Co., Ltd.), acid value 180 mgKOH / g AA: Adipic acid (manufactured by Asahi Kasei Chemicals Corporation), acid value 768 mgKOH / g SA: Sebacic acid (manufactured by Toyokuni Essential Oils Co., Ltd.), acid value 555 mgKOH / g OA: Oleic acid (manufactured by Shin Nippon Rika Co., Ltd.), acid value 199 mgKOH / g LA: Linoleic acid (manufactured by Fujifilm Wako Pure Chemical Corporation), acid value 200 mgKOH / g ISA: Isostearic acid (manufactured by Nissan Chemical Industries, Ltd.), acid value 198 mgKOH / g RCA: Ricinoleic acid (manufactured by Ito Oil Co., Ltd.), acid value 188 mg KOH / g (Component (B)) B6: Newcol 2320-SN (polyoxyethylene alkyl ether sulfate, manufactured by Nippon Emulsifier Co., Ltd.) (Component (C)) St: Styrene (solubility in water: 0.1 g / 100 g water or less) 2EHA: 2-Ethylhexyl acrylate (solubility in water: 0.1 g / 100 g water or less) MMA: Methyl methacrylate (solubility in water: 1.0 g / 100 g water) BA: Butyl acrylate (solubility in water: 0.1 g / 100 g water) GMA: Glycidyl methacrylate (solubility in water: 2.3 g / 100 g water) MA: Methyl acrylate (solubility in water: 6.0 g / 100 g water)

[0064]

Table 2

[0065] <Preparation of Aqueous Pigment Dispersion> As the pigment, 60 parts of titanium oxide CR-90 (manufactured by Ishihara Sangyo Co., Ltd.), 8 parts of M-30 (styrene maleic acid resin varnish, acid value 155 mg KOH / g, manufactured by Starlight PMC Co., Ltd.) as the pigment dispersion resin, 32 parts of ion-exchanged water, and 150 parts of glass beads were charged into a 250 ml poly bottle and shaken for 60 minutes with a paint shaker, and then an aqueous pigment dispersion was obtained by removing the glass beads.

[0066] <Preparation of Aqueous Ink> 50 parts of the obtained aqueous pigment dispersion and 50 parts of a core-shell type emulsion for aqueous flexible packaging printing were mixed to obtain an aqueous ink for flexible packaging. The adhesion of the ink film was evaluated by the following method.

[0067] <Adhesion Evaluation> Using commercially available coated paper, PET film which is a polyester film, OPP film which is a biaxially oriented polypropylene film, and OPS (registered trademark) film which is a biaxially oriented polystyrene film as the base materials, the prepared water-based printing ink for flexible packaging was coated with a bar coater #6. After drying at room temperature for one day, a 18-mm-wide cellophane tape (registered trademark, Nichiban Co., Ltd.) was adhered to the coated film portion, and then the tape was peeled off, and the state of the peeled portion was visually evaluated. When the coated object was not peeled at all, it was rated (5); when the area of the peeled portion was less than 10% of the whole, it was rated (4); when the area of the peeled portion was 10% or more and less than 20% of the whole, it was rated (3); when the peeled area was 20% or more and less than 50% of the whole, it was rated (2); when the peeled area was 50% or more of the whole, it was rated (1). The larger the number, the better the adhesion, and at (3) or above, it is at a practical level.

[0068] Table 3 shows the evaluation results of the adhesion tests for each sample.

[0069]

Table 3

[0070] The adhesion of the core-shell type emulsions (E1 to E17) for water-based flexible packaging printing obtained in Examples 1 to 17 that satisfy the conditions of the present invention to the base materials was all at a practical level or above. On the other hand, in Comparative Examples 1 to 12 that did not satisfy the conditions of the present invention, emulsions could not be obtained or the adhesion to the base materials was insufficient.

[0071] From the comparison between Evaluation Example 4 and Evaluation Example 5, it can be seen that when a water-soluble resin containing an aromatic ethylenically unsaturated monomer is used as the (B) component, the adhesion to the base is excellent. Also, from the comparison between Evaluation Example 13 and Evaluation Examples 3, 11, and 12, it can be seen that when a water-soluble resin containing an alicyclic structure-containing ethylenically unsaturated monomer is used as the (B) component, the adhesion evaluation to the base material is excellent.

[0072] Furthermore, from the comparison between Evaluation Examples 3, 14 to 16 and Evaluation Example 17, it can be seen that when an ethylenically unsaturated monomer having a solubility in water at 20 °C of less than 3 g / 100 g water is used as the component (C), the adhesion to the substrate is excellent.

[0073] The core-shell type emulsion for aqueous flexible packaging printing provided by the present invention has excellent adhesion to any substrate of paper or film, and thus is useful as a raw material for a printing ink binder or a coating varnish. In addition, since the dimer acid and trimer acid in the component (A) are derived from plants, they are materials with low environmental impact.

Claims

1. (A) At least one compound selected from the group consisting of a polyamide compound (a-3) having an acid value obtained by reacting dimer acid (a-1), trimer acid (a-2), dimer acid (a-1) and / or trimer acid (a-2) with a polyvalent amine, and a polyester compound (a-4) having an acid value obtained by reacting dimer acid (a-1) and / or trimer acid (a-2) with a polyvalent alcohol, (B) A water-soluble resin which is a polymer of an ethylenically unsaturated monomer containing a carboxy group-containing ethylenically unsaturated monomer, (C) An emulsion polymer of an ethylenically unsaturated monomer (c) and is an aqueous core-shell type emulsion for water-based flexible packaging printing, wherein the acid value of the compound (A) is 80 mgKOH / g or more, the compound (A) is contained in the emulsion solid content in an amount of 0.5 to 40% by mass, the compound (A) and the water-soluble resin (B) form a shell part, and the emulsion polymer (C) forms a core part, and which is an aqueous core-shell type emulsion for water-based flexible packaging printing.

2. The aqueous core-shell type emulsion for water-based flexible packaging printing according to claim 1, wherein the water-soluble resin (B) is a polymer of a monomer mixture containing an aromatic-containing ethylenically unsaturated monomer and / or an alicyclic structure-containing ethylenically unsaturated monomer.

3. The aqueous core-shell type emulsion for water-based flexible packaging printing according to claim 1, wherein the solubility of the ethylenically unsaturated monomer (c) in water at 20°C is less than 3 g / 100 g of water.

4. A binder resin for water-based flexible packaging printing ink, comprising the aqueous core-shell type emulsion for water-based flexible packaging printing according to any one of claims 1 to 3.

5. A coating varnish for water-based flexible packaging printing, comprising the aqueous core-shell type emulsion for water-based flexible packaging printing according to any one of claims 1 to 3.

6. (A) At least one compound selected from the group consisting of a polyamide compound (a-3) having an acid value obtained by reacting dimer acid (a-1), trimer acid (a-2), dimer acid (a-1) and / or trimer acid (a-2) with a polyvalent amine, and a polyester compound (a-4) having an acid value obtained by reacting dimer acid (a-1) and / or trimer acid (a-2) with a polyvalent alcohol, (B) A water-soluble resin which is a polymer of an ethylenically unsaturated monomer containing a carboxy group-containing ethylenically unsaturated monomer A method for producing a core-shell type emulsion for aqueous flexible packaging printing by emulsion polymerizing an ethylenically unsaturated monomer (c) in water in the presence of The acid value of the compound (A) is 80 mgKOH / g or more, and the method for producing a core-shell type emulsion for aqueous flexible packaging printing is characterized in that the compound (A) is contained in the emulsion solid content in an amount of 0.5 to 40% by mass. **Claim 7** The method for producing a core-shell type emulsion for aqueous flexible packaging printing according to claim 6, wherein the water-soluble resin (B) is a polymer of a monomer mixture containing an aromatic-containing ethylenically unsaturated monomer and / or an alicyclic structure-containing ethylenically unsaturated monomer. **Claim 8** The method for producing a core-shell type emulsion for aqueous flexible packaging printing according to claim 6, wherein the solubility of the ethylenically unsaturated monomer (c) in water at 20°C is less than 3 g / 100 g of water.

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