Emulsion composition for aqueous coat agent, aqueous coat agent and method for producing emulsion composition for aqueous coat agent

Abstract

To provide a method for producing an emulsion composition for an aqueous coat agent which forms a coating film excellent in water resistance / oil resistance / heat sealability on a paper base material for food packaging, and can reduce odor of coating paper.SOLUTION: A method for producing an emulsion composition for an aqueous coat agent includes a step of emulsion-polymerizing a monomer satisfying the following (1) and (2) in water (C), in the presence of sodium dioctyl sulfosuccinate (A), and obtaining an acrylic resin and / or a styrene acrylic resin (B). (1) With respect to 100 pts.mass of the total monomer, an amount of 2-ethyl hexyl acrylate (b-1) is 30 to 50 pts.mass. (2) With respect to 100 pts.mass of the total monomer, an amount of a monomer (b-2) having a carboxyl group is 0 to 5 pts.mass.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an emulsion composition that forms a coating film on a food packaging paper substrate that has excellent water resistance, oil resistance, and heat sealability, and that can reduce the odor of the coated paper; an aqueous coating agent containing the emulsion composition; and a method for producing the emulsion composition. [Background technology]

[0002] In recent years, as a measure to combat the problem of plastic waste, there has been growing demand for materials that can replace the polyethylene laminates used in food-contact paper such as paper cups and burger wraps. As an alternative to polyethylene lamination, the use of coating agents with functions such as water resistance, oil resistance, and heat sealing properties is being considered. However, since most of these coating agents are expensive, there is a growing demand for inexpensive acrylic materials.

[0003] However, acrylic materials have a problem with odors caused by residual acrylic monomers and decomposition products of the monomers after coating, making them difficult to use in food contact paper. The cause of residual monomers is thought to be the need to use monomers with low polymerization reactivity, such as 2-ethylhexyl acrylate, or thiol-based chain transfer agents in order to achieve the film resistance required of coating agents, such as water resistance and oil resistance. Such low-reactivity monomers remain in aqueous coating agents as residual monomers and become odorous components after coating. Furthermore, residual monomers in aqueous coating agents hydrolyze during the reaction or during storage after the reaction, producing high-boiling alcohols, which, like the residual monomers, become odorous components after coating. As a countermeasure, attempts have been made to accelerate emulsion polymerization by using a combination of various surfactants, but these have still not been sufficient from the standpoint of odor.

[0004] Patent Document 1 discloses a food packaging sheet that has excellent food resistance in addition to blocking and heat sealing properties, but because it uses a thiol-based chain transfer agent, there are concerns about odor issues. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-016065 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] The present invention aims to provide an emulsion composition for an aqueous coating agent that forms a coating film on a food packaging paper substrate that has excellent water resistance, oil resistance, and heat sealability, and that can reduce the odor of the coated paper; an aqueous coating agent that contains the emulsion composition; and a method for producing the emulsion composition. [Means for solving the problem]

[0007] The present inventors have discovered that emulsion compositions obtained using sodium dioctylsulfosuccinate, among many other polymerization emulsifiers, have a low content of unreacted 2-ethylhexyl acrylate monomer and its hydrolyzate, 2-ethylhexyl alcohol, even when a certain amount of 2-ethylhexyl acrylate is used to ensure water resistance, oil resistance, and heat sealability. Furthermore, the present inventors have discovered that this method enables the performance of the coating agent to be achieved with a very small amount (less than 0.3 parts by mass per 100 parts by mass of total monomers) of thiol-based chain transfer agent, or even without any thiol-based chain transfer agent. Overall, the present inventors have found that, as a result of reducing the amount of odor-causing components in the emulsion composition, paper coated with an aqueous coating agent containing the emulsion composition has an improved odor compared to conventional coated paper.

[0008] That is, the present invention provides: <1> The composition contains at least dioctyl sodium sulfosuccinate (A), an acrylic resin and / or a styrene-acrylic resin (B), and water (C), An emulsion composition for an aqueous coating agent, wherein the mass ratio of the monomers constituting the resin (B) satisfies the following (1) and (2): (1) The amount of 2-ethylhexyl acrylate (b-1) contained in 100 parts by mass of the monomer constituting the resin (B) is 30 to 50 parts by mass. (2) The amount of the monomer (b-2) having a carboxyl group contained in 100 parts by mass of the monomer constituting the resin (B) is 0 to 5 parts by mass. <2> The content of 2-ethylhexyl acrylate (b-1) and 2-ethylhexyl alcohol derived from (b-1) in the emulsion composition for aqueous coating agents is Each of the above is less than 300 ppm. <1> The emulsion composition for an aqueous coating agent according to claim 1, <3> The emulsion composition was applied to paper at a solid content of 10 g / m 2 The coated paper has an odor intensity of 350 or less as measured by an odor measuring device. <1> The emulsion composition for an aqueous coating agent according to the present invention, <4> The emulsion composition for aqueous coating agents is characterized in that the content of dioctyl sodium sulfosuccinate (A) is 0.03% to 1.5% by mass. <1> The emulsion composition for an aqueous coating agent according to the present invention, <5> The monomer (b-2) having a carboxyl group is at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. <1> The emulsion composition for an aqueous coating agent according to the present invention, <6> The aforementioned <1> ~ <5> an aqueous coating agent for food packaging paper, comprising the emulsion composition for an aqueous coating agent according to claim 1; <7> The aforementioned <6> A food packaging paper having a coating layer containing the aqueous coating agent for food packaging paper according to claim 1. <8> In the presence of sodium dioctyl sulfosuccinate (A), A method for producing an emulsion composition for an aqueous coating agent, comprising the steps of emulsion-polymerizing a monomer mixture satisfying the following (1) and (2) in water (C) to obtain an acrylic resin and / or a styrene-acrylic resin (B): , (1) The amount of 2-ethylhexyl acrylate (b-1) contained in 100 parts by mass of the monomer mixture is 30 to 50 parts by mass. (2) The amount of the monomer (b-2) having a carboxyl group contained in 100 parts by mass of the monomer mixture is 0 to 5 parts by mass. <9> The emulsion composition for aqueous coating agents is characterized in that the contents of 2-ethylhexyl acrylate (b-1) and 2-ethylhexyl alcohol derived from (b-1) are each less than 300 ppm. <7> A method for producing the emulsion composition according to claim 1, <10> The emulsion composition was applied to paper at a solid content of 10 g / m 2 The odor intensity of the coated paper measured by an odor measuring device is 350 or less. <7> a method for producing the emulsion composition for an aqueous coating agent according to the present invention; <11> dioctyl sodium sulfosuccinate (A) is used in an amount of 0.1 to 2.0% by mass based on the monomer mixture, <7> a method for producing the emulsion composition for an aqueous coating agent according to the present invention; <12> The monomer (b-2) having a carboxyl group is at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. <7> a method for producing the emulsion composition for an aqueous coating agent according to the present invention; is. [Effects of the Invention]

[0009] According to the present invention, it is possible to provide an emulsion composition for aqueous coating agents that has excellent water resistance, oil resistance, and heat sealability and that has reduced odor when applied to paper, and an aqueous coating agent containing the same. BEST MODE FOR CARRYING OUT THE INVENTION

[0010] The emulsion composition for an aqueous coating agent, the aqueous coating agent containing the emulsion composition, and the method for producing the emulsion composition for an aqueous coating agent of the present invention will be specifically described below.

[0011] <Emulsion composition for aqueous coating agents> The emulsion composition for an aqueous coating agent of the present invention contains at least dioctyl sodium sulfosuccinate (A), an acrylic resin and / or a styrene-acrylic resin (B), and water (C), The mass ratio of the monomers constituting the resin (B) satisfies the following (1) and (2). (1) The amount of 2-ethylhexyl acrylate (b-1) contained in 100 parts by mass of the monomer constituting the resin (B) is 30 to 50 parts by mass. (2) The amount of the monomer (b-2) having a carboxyl group contained in 100 parts by mass of the monomer constituting the resin (B) is 0 to 5 parts by mass.

[0012] The emulsion composition for aqueous coating agents of the present invention preferably contains 0.03 to 1.5 mass % of dioctyl sodium sulfosuccinate (A), 25 to 50 mass % of resin (B), and 48.5 to 74.97 mass % of water (C).

[0013] Various commercially available products can be used as dioctyl sodium sulfosuccinate (A). Commercially available dioctyl sulfosuccinate (A) products include "Sunmorin (registered trademark) OT-70 (manufactured by Sanyo Chemical Industries, Ltd.)," "Pelex (registered trademark) OT-P (manufactured by Kao Corporation)," and "Neocol (registered trademark) SW-C (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)."

[0014] In the present invention, the acrylic resin is a polymer obtained by copolymerizing at least (meth)acrylic acid esters, and the styrene-acrylic resin is a polymer obtained by copolymerizing at least (meth)acrylic acid esters and styrenes.

[0015] Examples of the (meth)acrylic acid esters include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate (b-1), and benzyl (meth)acrylate; (meth)acrylic acid esters having a hydroxyl group such as 2-hydroxyethyl (meth)acrylate; and glycidyl (meth)acrylate, and these may be used alone or in combination.

[0016] The styrenes may be any monomer having a styrene skeleton, such as styrene and α-methylstyrene, and may contain one or more of these in combination.

[0017] The emulsion composition for aqueous coating agents of the present invention contains at least 30 to 50 parts by weight of 2-ethylhexyl acrylate (b-1) per 100 parts by weight of the monomers constituting resin (B), and optionally 0 to 5 parts by weight of a monomer (b-2) having a carboxyl group. If the amount of 2-ethylhexyl acrylate (b-1) is less than 30 parts by weight, the desired water resistance and oil resistance cannot be achieved when the emulsion composition is applied to paper. If the amount of 2-ethylhexyl acrylate (b-1) is more than 50 parts by weight, residual monomers that cause odors are likely to be generated. Furthermore, if the amount of carboxyl group-containing monomer (b-2) is more than 5 parts by weight, residual monomers that cause odors are likely to be generated, and the desired properties practical for a coating agent cannot be achieved.

[0018] Monomers other than (b-1) and (b-2) preferably include (meth)acrylic acid esters other than (b-1) and styrenes, and from the viewpoints of reactivity and odor, preferably include methyl methacrylate, butyl acrylate, and styrene. Methyl methacrylate, butyl acrylate, and styrene have particularly good polymerizability and contribute to reducing the residual monomer of (b-1) and its hydrolysates after emulsion polymerization, so they are preferably included in an amount of 45 to 70 parts by mass per 100 parts by mass of the monomers constituting resin (B).

[0019] When a monomer (b-2) having a carboxyl group is contained, examples thereof include unsaturated monocarboxylic acids such as (meth)acrylic acid and crotonic acid, and unsaturated dicarboxylic acids such as fumaric acid, maleic acid, itaconic acid and citraconic acid, but it is preferably at least one selected from acrylic acid, methacrylic acid, itaconic acid and fumaric acid, and more preferably contains acrylic acid.

[0020] In the emulsion composition for an aqueous coating agent of the present invention, from the viewpoint of reducing odor when applied to paper, the content of 2-ethylhexyl acrylate (b-1) and 2-ethylhexyl alcohol derived from (b-1) is preferably less than 300 ppm each relative to the total mass of the emulsion composition.

[0021] The emulsion composition for aqueous coating agents of the present invention is applied to paper at a solid content of 10 g / m 2 When coated paper is used as food packaging, it is preferable that the odor intensity measured by an odor measuring device is 350 or less, as this results in a dramatic improvement in odor that is difficult to detect even in a sensory evaluation using human olfactory senses.

[0022] The emulsion composition for an aqueous coating agent of the present invention is preferably obtained by a method including an emulsion polymerization step, which will be described later.

[0023] <Method for producing emulsion composition> The method for producing an emulsion composition for an aqueous coating agent of the present invention is characterized by comprising a step of emulsion polymerizing, in the presence of dioctyl sodium sulfosuccinate (A), a monomer that satisfies the following (1) and (2) in water (C) to obtain an acrylic resin and / or a styrene-acrylic resin (B): (1) The amount of 2-ethylhexyl acrylate (b-1) contained in 100 parts by mass of the monomer mixture is 30 to 50 parts by mass. (2) The amount of the monomer (b-2) having a carboxyl group contained in 100 parts by mass of the monomer mixture is 0 to 5 parts by mass.

[0024] An essential feature of the present invention is the discovery that dioctyl sodium sulfosuccinate is the most suitable emulsifier for reducing unreacted and decomposed products of specific monomers constituting resin (B) in emulsion polymerization of resin (B) with properties suitable for aqueous coating agents. By emulsion polymerizing a monomer mixture containing 2-ethylhexyl acrylate (b-1) in the presence of dioctyl sodium sulfosuccinate (A), polymerization of the monomer mixture containing 2-ethylhexyl acrylate (b-1) proceeds sufficiently, and odor can be reduced by reducing residual monomers. The amount of dioctyl sodium sulfosuccinate (A) used when obtaining resin (B) by emulsion polymerization in water is determined from the viewpoint of safety. From the viewpoint of exhibiting good coating film properties and reducing odor by reducing residual monomers, it is preferably contained in the range of 0.1 to 2.0 mass% of the monomer mixture, and more preferably contained in the range of 0.3 to 1.5 mass% because it can contribute to further odor reduction.

[0025] In addition, in the production of the emulsion composition for aqueous coating agents of the present invention, resin (B) may be obtained by emulsion polymerization in water using an emulsifier other than dioctyl sulfosuccinic acid (A). As emulsifiers other than (A), commercially available nonionic emulsifiers or anionic emulsifiers, regardless of whether they are reactive, can be used. Examples of nonionic emulsifiers include polyethylene oxide, polyoxyethylene lauryl ether, and polypropylene oxide compounds. Examples of anionic emulsifiers include sodium dodecylbenzenesulfonate, sodium polyoxyethylene styrenated phenol sulfate, and formalin condensates of sodium naphthalenesulfonate. These may be used in amounts up to 2% by mass of resin (B) contained in the emulsion composition, provided that the effects of the present invention are not impaired. Examples include Adeka Reasoap® SR-10, SR-20, ER-10, and ER-20 (manufactured by Adeka Corporation) and Neogen® S-20F (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.).

[0026] In the production of the emulsion composition for aqueous coating agents of the present invention, known chain transfer agents such as alkyl mercaptans can be used as needed. From the standpoint of odor, when using thiol-based chain transfer agents such as alkyl mercaptans, it is preferable to use as little chain transfer agent as possible, preferably less than 0.3 parts by mass of chain transfer agent per 100 parts by mass of the monomer mixture. When using addition-cleavage chain transfer agents such as α-methylstyrene dimer, less care is required than with thiol-based chain transfer agents from the standpoint of odor. However, using large amounts of addition-cleavage chain transfer agents can have adverse effects such as deterioration of polymerization properties, and there is concern about worsening odor due to residual monomers and decomposition products. Therefore, even when using addition-cleavage chain transfer agents, it is preferable to use as little chain transfer agent as possible, preferably 0 to 0.5 parts by mass of chain transfer agent per 100 parts by mass of the monomer mixture.

[0027] The emulsion polymerization method used in the present invention can be any conventional emulsion polymerization method. For example, a reaction vessel equipped with a stirrer and a nitrogen gas inlet tube is charged with dioctyl sulfosuccinic acid (A), water (C), and, if necessary, an emulsifier other than (A) and a chain transfer agent. A polymerization initiator is used, such as a peroxide (e.g., ammonium persulfate, potassium persulfate, or hydrogen peroxide), or a redox initiator consisting of a combination of such a peroxide with a reducing agent (e.g., ferrous sulfate, sodium bisulfite, ascorbic acid, or sodium ascorbate). The monomer emulsion described below is added dropwise over 60 to 180 minutes at a reaction temperature of 60 to 90°C, and the reaction is allowed to proceed for 60 to 480 minutes after the completion of the addition, completing the reaction. The monomer emulsion is prepared by previously mixing and stirring dioctyl sulfosuccinic acid (A), water (C), monomers, and, if necessary, an emulsifier other than (A) and a chain transfer agent. In order to achieve the desired performance for food contact paper applications, the polymerization may be carried out in one, two, or three stages as necessary. After the reaction is complete, the required amount of 25% aqueous ammonia is added with stirring to neutralize the mixture, yielding an emulsion composition.

[0028] <Water-based coating agent> The emulsion composition obtained by the present invention is useful as a component of an aqueous coating agent for food contact paper, and can be made into an aqueous coating agent by adding general-purpose organic solvents such as isopropyl alcohol (IPA) and butyl cellosolve, as well as fillers, waxes, release agents, film-forming aids, leveling agents, antifoaming agents, and preservatives as necessary.

[0029] When using an aqueous coating agent containing the emulsion composition of the present invention, the substrate to be coated is paper or paperboard, and specific examples include cup base paper, food packaging paper, kraft paper, liner paper, and fine paper.

[0030] The coating conditions for the aqueous coating agent include methods using a printing machine such as flexographic printing or gravure printing, and methods using a coating machine such as a roll coater, size press coater, blade coater, curtain coater, air knife coater, or rod coater. The coating amount is determined according to the required level of heat sealability, and is set to 1 to 15 g / m of the aqueous coating agent in solid content on one side of the substrate. 2 Depending on the application, both sides of the substrate may be coated. There are no particular restrictions on the drying method after coating, and examples include non-contact infrared drying, hot air drying, and contact cylinder drying.

[0031] The uses of the aqueous coating agent are not particularly limited, but it is suitable for any application requiring heat sealability, water resistance, or oil resistance, and is particularly suitable as a replacement for polyethylene laminate in applications where various performance properties have traditionally been ensured by polyethylene laminate. [Example]

[0032] The present invention will be described in detail below with reference to examples and comparative examples. Note that % means % by mass unless otherwise specified.

[0033] <Synthesis of emulsion composition> Example 1 A separable flask equipped with a thermometer, condenser, and stirrer was charged with ion-exchanged water (587.3 g) and dioctyl sodium sulfosuccinate (A) (0.3 g). The temperature was raised to 80 °C under nitrogen purging. Next, a dilution of ammonium persulfate (0.6 g) dissolved in ion-exchanged water (6.0 g) was added. After 5 minutes, a monomer emulsion of ion-exchanged water (100 g), dioctyl sodium sulfosuccinate (A) (0.3 g), methyl methacrylate (159.6 g), 2-ethylhexyl acrylate (135.5 g), and acrylic acid (6.0 g) was added dropwise over 120 minutes. Sixty minutes after the completion of the dropwise addition, 25% aqueous ammonia solution (0.3 g) was added. Sixty minutes after the addition of the aqueous ammonia, a dilution of ammonium persulfate (0.3 g) dissolved in ion-exchanged water (3.0 g) was added to consume any remaining monomer. After a further 60 minutes, the mixture was cooled to obtain emulsion composition (1).

[0034] Example 2 An emulsion composition (2) was obtained in the same manner as in Example 1, except that ammonium persulfate (1.5 g) to be added before the dropwise addition of the monomer emulsion was dissolved in ion-exchanged water (15 g) to form a diluted solution, methyl methacrylate (118.8 g), butyl acrylate (26.7 g), 2-ethylhexyl acrylate (148.5 g), acrylic acid (3.0 g), and dioctyl sodium sulfosuccinate (A) (3.3 g) were used as the monomer emulsion, and 25% aqueous ammonia solution (0.2 g) was used.

[0035] Example 3 An emulsion composition (3) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.9 g, a dilution of ammonium persulfate (0.3 g) dissolved in ion-exchanged water (3 g) was added before the dropwise addition of the monomer emulsion, methyl methacrylate (144.4 g), butyl acrylate (30.1 g), 2-ethylhexyl acrylate (120.3 g), acrylic acid (3.0 g), styrene (3.0 g), and dioctyl sodium sulfosuccinate (A) (3.6 g) were used as the monomer emulsion, and 25% aqueous ammonia solution (0.2 g) was used.

[0036] Example 4 An emulsion composition (4) was obtained in the same manner as in Example 1, except that butyl acrylate was not used and methyl methacrylate (156.5 g), 2-ethylhexyl acrylate (135.4 g), acrylic acid (6.0 g), styrene (3.0 g), dioctyl sodium sulfosuccinate (A) (0.6 g), and α-methylstyrene dimer (1.5 g) were used as the monomer emulsion.

[0037] Example 5 An emulsion composition (5) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.6 g, a dilution of ammonium persulfate (0.3 g) dissolved in ion-exchanged water (3 g) was added before the dropwise addition of the monomer emulsion, methyl methacrylate (132.5 g), 2-ethylhexyl acrylate (150.6 g), acrylic acid (15.1 g), styrene (3.0 g), dioctyl sodium sulfosuccinate (A) (2.4 g), and α-methylstyrene dimer (0.6 g) were used as the monomer emulsion, and 25% aqueous ammonia solution (0.8 g) was used.

[0038] Example 6 An emulsion composition (6) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 1.2 g, and methyl methacrylate (120.0 g), butyl acrylate (81.0 g), 2-ethylhexyl acrylate (90.0 g), acrylic acid (6.0 g), styrene (3.0 g), dioctyl sodium sulfosuccinate (A) (4.8 g), and α-methylstyrene dimer (0.3 g) were used as the monomer emulsion.

[0039] Example 7 An emulsion composition (7) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 1.5 g, a dilution of ammonium persulfate (1.5 g) dissolved in ion-exchanged water (15 g) was added before the dropwise addition of the monomer emulsion, methyl methacrylate (107.4 g), butyl acrylate (44.8 g), 2-ethylhexyl acrylate (104.5 g), acrylic acid (11.9 g), styrene (29.8 g), dioctyl sodium sulfosuccinate (A) (3.0 g), and α-methylstyrene dimer (1.2 g) were used as the monomer emulsion, and 25% aqueous ammonia solution (0.6 g) was used.

[0040] Example 8 An emulsion composition (8) was obtained in the same manner as in Example 1, except that the amount of ion-exchanged water (652 g) charged into the separable flask was changed, a diluted solution of ammonium persulfate (0.7 g) dissolved in ion-exchanged water (7 g) was added before the dropwise addition of the monomer emulsion, methyl methacrylate (167.3 g), 2-ethylhexyl acrylate (150.6 g), acrylic acid (10.0 g), styrene (6.7 g), and t-dodecyl mercaptan (1.0 g) were used as the monomer emulsion, and 25% aqueous ammonia solution (0.5 g) was used.

[0041] Example 9 An emulsion composition (9) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.6 g, a dilution of ammonium persulfate (0.9 g) dissolved in ion-exchanged water (9 g) was added before the dropwise addition of the monomer emulsion, acrylic acid was not used, and methyl methacrylate (150.1 g), 2-ethylhexyl acrylate (141.1 g), styrene (9.0 g), dioctyl sodium sulfosuccinate (A) (1.8 g), and n-dodecyl mercaptan (0.9 g) were used as the monomer emulsion, and 25% aqueous ammonia solution was not used.

[0042] Example 10 An emulsion composition (10) was obtained in the same manner as in Example 1, except that a dilution of ammonium persulfate (1.2 g) dissolved in ion-exchanged water (12 g) was added before the dropwise addition of the monomer emulsion, and methyl methacrylate (158.3 g), 2-ethylhexyl acrylate (134.4 g), sodium dioctyl sulfosuccinate (A) (0.9 g), and t-dodecyl mercaptan (1.5 g) were used as the monomer emulsion.

[0043] Example 11 An emulsion composition (11) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.9 g, a diluted solution of ammonium persulfate (1.2 g) dissolved in ion-exchanged water (12 g) was added before the dropwise addition of the monomer emulsion, and methyl methacrylate (157.9 g), 2-ethylhexyl acrylate (134.0 g), dioctyl sodium sulfosuccinate (A) (1.8 g), and n-dodecyl mercaptan (1.5 g) were used for the monomer emulsion.

[0044] Example 12 An emulsion composition (12) was obtained in the same manner as in Example 1, except that methyl methacrylate (156.2 g), 2-ethylhexyl acrylate (135.2 g), styrene (3.0 g), dioctyl sodium sulfosuccinate (A) (1.2 g), and α-methylstyrene dimer (2.1 g) were used as the monomer emulsion.

[0045] Example 13 An emulsion composition (13) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 1.5 g, and methyl methacrylate (155.1 g), 2-ethylhexyl acrylate (134.3 g), dioctyl sodium sulfosuccinate (A) (6.0 g), styrene (3.0 g), and α-methylstyrene dimer (0.6 g) were used as the monomer emulsion.

[0046] Example 14 An emulsion composition (14) was obtained in the same manner as in Example 1, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.6 g, NEOGEN (registered trademark) S-20F (0.6 g as an active ingredient) was used in combination, methyl methacrylate (122.5 g), butyl acrylate (15.3 g), 2-ethylhexyl acrylate (91.9 g), acrylic acid (9.2 g), styrene (67.4 g), dioctyl sodium sulfosuccinate (A) (1.5 g), and α-methylstyrene dimer (0.3 g) were used as the monomer emulsion, and the amount of 25% aqueous ammonia solution was 0.5 g.

[0047] (Comparative Example 1) An emulsion composition (15) was obtained in the same manner as in Example 12, except that the dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to ADEKA REASOAP (registered trademark) SR-10 (0.6 g as an active ingredient), the dioctyl sodium sulfosuccinate (A) used in the monomer emulsion was changed to ADEKA REASOAP (registered trademark) SR-10 (0.9 g as an active ingredient), and methyl methacrylate (156.6 g), 2-ethylhexyl acrylate (135.5 g), and α-methylstyrene dimer (0.6 g) were used.

[0048] (Comparative Example 2) An emulsion composition (16) was obtained in the same manner as in Example 12, except that the dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to NEOGEN (registered trademark) S-20F (0.6 g as an active ingredient), the dioctyl sodium sulfosuccinate (A) used in the monomer emulsion was changed to S-20F (0.9 g as an active ingredient), and methyl methacrylate (155.6 g), 2-ethylhexyl acrylate (134.7 g), and α-methylstyrene dimer (0.6 g) were used.

[0049] (Comparative Example 3) An emulsion composition (17) was obtained in the same manner as in Example 12, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.6 g, the amount of dioctyl sodium sulfosuccinate (A) used in the monomer emulsion was changed to (2.4 g), styrene was not used, and methyl methacrylate (129.0 g), butyl acrylate (90.0 g), 2-ethylhexyl acrylate (75.0 g), and α-methylstyrene dimer (0.6 g) were used in the monomer emulsion.

[0050] Comparative Example 4 An emulsion composition (18) was obtained in the same manner as in Example 12, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.6 g, the amount of dioctyl sodium sulfosuccinate (A) used in the monomer emulsion was changed to 2.4 g, styrene was not used, and methyl methacrylate (99.0 g), butyl acrylate (30.0 g), 2-ethylhexyl acrylate (165.0 g), and α-methylstyrene dimer (0.6 g) were used in the monomer emulsion.

[0051] (Comparative Example 5) The procedure was the same as in Example 13, except that dioctyl sodium sulfosuccinate (A) was not used. The liquid containing a large amount of impurities was filtered to obtain emulsion composition (19).

[0052] (Comparative Example 6) An emulsion composition (20) was obtained in the same manner as in Example 12, except that the amount of dioctyl sodium sulfosuccinate (A) charged into the separable flask was changed to 0.6 g, the amount of dioctyl sodium sulfosuccinate (A) used in the monomer emulsion was changed to 2.4 g, methyl methacrylate (156.0 g), 2-ethylhexyl acrylate (123.0 g), acrylic acid (18.0 g), and α-methylstyrene dimer (0.6 g) were used in the monomer emulsion, and the amount of 25% aqueous ammonia solution was changed to 0.9 g.

[0053] Example 15 A separable flask equipped with a thermometer, condenser, and stirrer was charged with ion-exchanged water (582.8 g) and dioctyl sodium sulfosuccinate (A) (0.6 g). The mixture was heated to 80 °C under nitrogen purging. Next, a dilution of ammonium persulfate (0.6 g) dissolved in ion-exchanged water (6.0 g) was added. Five minutes later, a monomer emulsion of ion-exchanged water (20 g), dioctyl sodium sulfosuccinate (A) (0.48 g), methyl methacrylate (22.2 g), butyl acrylate (10.8 g), 2-ethylhexyl acrylate (24.0 g), acrylic acid (3.0 g), and α-methylstyrene dimer (0.2 g) was added dropwise over 30 minutes. Thirty minutes after the completion of the dropwise addition, the second stage consisted of a monomer emulsion of ion-exchanged water (80 g), dioctyl sodium sulfosuccinate (A) (1.92 g), methyl methacrylate (88.7 g), butyl acrylate (43.2 g), 2-ethylhexyl acrylate (95.9 g), acrylic acid (12.0 g), and α-methylstyrene dimer (0.7 g) added dropwise over 90 minutes. Sixty minutes after the completion of the dropwise addition, 25% aqueous ammonia solution (0.8 g) was added. Sixty minutes after the addition of the aqueous ammonia, a dilution of ammonium persulfate (0.3 g) dissolved in ion-exchanged water (3.0 g) was added to consume any remaining monomer. After another 60 minutes, the mixture was cooled to obtain emulsion composition (21).

[0054] Example 16 An emulsion composition (22) was obtained in the same manner as in Example 15, except that in the first stage, α-methylstyrene dimer was not used, and a monomer emulsion of dioctyl sodium sulfosuccinate (A) (0.72 g), methyl methacrylate (44.1 g), butyl acrylate (4.5 g), 2-ethylhexyl acrylate (27.0 g), acrylic acid (0.9 g), styrene (13.5 g), and t-dodecyl mercaptan (0.9 g) was used; and in the second stage, α-methylstyrene dimer was not used, and a monomer emulsion of dioctyl sodium sulfosuccinate (A) (1.68 g), methyl methacrylate (105.0 g), butyl acrylate (10.5 g), 2-ethylhexyl acrylate (63.0 g), acrylic acid (2.1 g), and styrene (29.4 g) was used, and 25% aqueous ammonia solution (0.2 g) was used.

[0055] Example 17 An emulsion composition (23) was obtained in the same manner as in Example 15, except that butyl acrylate and α-methylstyrene dimer were not used in the first stage, and a monomer emulsion of dioctyl sodium sulfosuccinate (A) (0.36 g), methyl methacrylate (19.3 g), 2-ethylhexyl acrylate (22.0 g), acrylic acid (1.3 g), and styrene (2.2 g) was used; and that butyl acrylate was not used in the second stage, and a monomer emulsion of dioctyl sodium sulfosuccinate (A) (2.04 g), methyl methacrylate (107.1 g), 2-ethylhexyl acrylate (127.4 g), acrylic acid (7.6 g), styrene (12.7 g), and α-methylstyrene dimer (0.8 g) was used, and 25% aqueous ammonia solution (0.5 g) was used.

[0056] Example 18 An emulsion composition (24) was obtained in the same manner as in Example 15, except that in the first stage, a monomer emulsion of dioctyl sodium sulfosuccinate (A) (0.6 g), methyl methacrylate (30.8 g), butyl acrylate (7.5 g), 2-ethylhexyl acrylate (33.8 g), acrylic acid (1.5 g), and styrene (1.5 g) was used, and in the second stage, α-methylstyrene dimer was not used, and a monomer emulsion of dioctyl sodium sulfosuccinate (A) (1.8 g), methyl methacrylate (94.5 g), butyl acrylate (20.3 g), 2-ethylhexyl acrylate (101.3 g), acrylic acid (4.5 g), and styrene (4.5 g) was used, and 25% aqueous ammonia solution (0.3 g) was used.

[0057] Example 19 A separable flask equipped with a thermometer, condenser, and stirrer was charged with ion-exchanged water (585.2 g) and dioctyl sodium sulfosuccinate (A) (0.6 g). The mixture was heated to 80 °C under nitrogen purging. Next, a dilution of ammonium persulfate (0.6 g) dissolved in ion-exchanged water (6.0 g) was added. Five minutes later, a monomer emulsion of ion-exchanged water (20 g), dioctyl sodium sulfosuccinate (A) (0.48 g), methyl methacrylate (30.6 g), butyl acrylate (6.0 g), 2-ethylhexyl acrylate (20.4 g), acrylic acid (2.4 g), styrene (0.6 g), and α-methylstyrene dimer (0.2 g) was added dropwise over 30 minutes. Thirty minutes after the completion of the dropwise addition, a monomer emulsion of 20 g of ion-exchanged water, 0.48 g of dioctyl sulfosuccinate (A), 30.6 g of methyl methacrylate, 5.4 g of butyl acrylate, 21.0 g of 2-ethylhexyl acrylate, 2.4 g of acrylic acid, and 0.6 g of styrene was added dropwise over 30 minutes. Thirty minutes after the completion of the dropwise addition, a monomer emulsion of 60 g of ion-exchanged water, 1.44 g of dioctyl sulfosuccinate (A), 91.8 g of methyl methacrylate, 14.4 g of butyl acrylate, 64.8 g of acrylic acid, 7.2 g of styrene, and 1.8 g of styrene was added dropwise over 60 minutes. Sixty minutes after the completion of the dropwise addition, 25% aqueous ammonia solution (0.6 g) was added. Sixty minutes after the addition of the aqueous ammonia, a diluted solution of ammonium persulfate (0.3 g) dissolved in ion-exchanged water (3.0 g) was added to consume the remaining monomer. After another 60 minutes, the mixture was cooled to obtain emulsion composition (25).

[0058] <Evaluation of 2-ethylhexyl acrylate and 2-ethylhexyl alcohol content by gas chromatography> The contents of 2-ethylhexyl acrylate and 2-ethylhexyl alcohol in the emulsion compositions prepared in the Examples and Comparative Examples were evaluated by gas chromatography (internal standard / calibration curve method). Samples of the coating agent and emulsion composition were dissolved in acetone containing an internal standard (DMF) without dilution, and then analyzed. The measurement results are shown relative to the total amount of emulsion composition.

[0059] Measuring device: GC-2010 (Shimadzu Corporation) Column: UAFFAP, length 30 m, inner diameter 0.25 mm Carrier gas: Nitrogen Carrier gas flow rate: 3.0 ml / min Detector: FID Inlet temperature: 200℃ Detector temperature: 250℃ Heating pattern (column): Hold at 50°C for 2 minutes, increase to 170°C at 5°C / min, then increase to 220°C at 32°C / min and hold for 15 minutes Split ratio: 25 Sample: 1 μl

[0060] <Coated paper for evaluation> The obtained emulsion composition was used as an aqueous coating agent and coated on one side of glossy kraft paper (basis weight 50 g / m 2 The coating was applied to a surface of approximately 1000 mm² using a bar coater and dried at 100°C for 30 seconds. The coating amount was 10 g / m² in solid form. 2 The coated surface was evaluated as follows.

[0061] <Odor intensity evaluation> Coated paper (0.01m 2 ) was placed in a PET bag and sealed, and after 24 hours the odor intensity was measured using a portable odor sensor, POLFA (manufactured by KALMOA). The odor intensity was calculated by subtracting the measurement value (blank) without the bag or sample from the measurement result of the sample, and an odor intensity of 400 or less was considered to be at a practical level.

[0062] <Water resistance> It was measured by the Cobb method of JIS-P-8140. In the present invention, Cobb1800 is 7 g / m 2 The following is a practical level.

[0063] <Oil resistance> The evaluation was based on the following two items (1) and (2). (1) Kit value: Evaluation was carried out in accordance with JAPAN TAPPI No. 41. In the present invention, a Kit value of 8 to 12 is a practical level. (2) Salad oil resistance: 0.1 g of salad oil was dropped onto the coating film, and the time until it penetrated was measured to evaluate. In the present invention, a practical level is 24 hours or more.

[0064] <Heat sealability> The coated surfaces were placed together and heat sealed under the following conditions, and the peel strength was measured. Heat sealing conditions Equipment: TP-701-B HEAT SEAL TESTER (manufactured by TESTER SANGYO CO., LTD.) Temperature: 120℃ Load: 2kgf / cm 2 Time: 0.5 seconds

[0065] Peel strength measurement conditions 24 hours after heat sealing, the peel strength was measured under the following conditions. Device: RTG-1210 (manufactured by ORIENTEC CORPORATION) Temperature: room temperature Peeling speed: 300 mm / min Peeling method: T-shaped peeling In the present invention, when the peel strength is 3.0 N / 15 mm or more, the substrate collapses during the peel test, and therefore it is judged that the heat sealability is sufficient.

[0066] [Table 1]

[0067] [Table 2]

[0068] [Table 3]

[0069] Explanation of terms in the table MMA: methyl methacrylate BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate Decomposition product: 2-ethylhexyl alcohol 24h<:More than 24 hours <18h: Less than 18 hours

[0070] In Table 3, the mass ratio of the monomer mixture in the emulsion polymerization step of resin (B) is the total value (the value in the "Total" column in the table) obtained by multiplying the monomer mixture added at each stage by the ratio shown in the table. For example, in Example 17, the amount of 2-ethylhexyl acrylate (b-1) contained in 100 parts by mass of the monomer mixture is (49 × 0.15) + (50 × 0.85) = 49.85 parts by mass.

[0071] From the examples and comparative examples, it can be seen that the examples that satisfy all of the conditions of the present invention have reduced odor from the coated paper, and the water resistance, oil resistance, and heat sealability are all at or above practical levels and are superior to the comparative examples that do not satisfy even one of the conditions of the present invention.

Claims

1. The composition contains at least dioctyl sodium sulfosuccinate (A), an acrylic resin and / or a styrene-acrylic resin (B), and water (C), An emulsion composition for an aqueous coating agent, wherein the mass ratio of the monomers constituting the resin (B) satisfies the following (1) and (2): (1) The amount of 2-ethylhexyl acrylate (b-1) contained in 100 parts by mass of the monomer constituting the resin (B) is 30 to 50 parts by mass. (2) The amount of the carboxyl group-containing monomer (b-2) contained in 100 parts by mass of the monomer constituting the resin (B) is 0 to 5 parts by mass.

2. The content of 2-ethylhexyl acrylate (b-1) and 2-ethylhexyl alcohol derived from (b-1) in the emulsion composition for aqueous coating agents is 2. The emulsion composition for an aqueous coating agent according to claim 1, wherein each of the components is less than 300 ppm.

3. The emulsion composition was applied to paper at a solid content of 10 g / m ２ 2. The emulsion composition for aqueous coating agents according to claim 1, wherein the odor intensity of the coated paper measured with an odor measuring device is 350 or less.

4. 2. The emulsion composition for aqueous coating agents according to claim 1, wherein the content of dioctyl sodium sulfosuccinate (A) contained in the emulsion composition for aqueous coating agents is 0.03% to 1.5% by mass.

5. The emulsion composition for aqueous coating agents according to claim 1, wherein the carboxyl group-containing monomer (b-2) is at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and fumaric acid.

6. An aqueous coating agent for food packaging paper, comprising the emulsion composition for aqueous coating agents according to any one of claims 1 to 5.

7. A food packaging paper having a coating layer containing the aqueous coating agent according to claim 6.

8. In the presence of dioctyl sodium sulfosuccinate (A), A method for producing an emulsion composition for an aqueous coating agent, comprising the steps of emulsion-polymerizing a monomer mixture satisfying the following (1) and (2) in water (C) to obtain an acrylic resin and / or a styrene-acrylic resin (B): (1) The amount of 2-ethylhexyl acrylate (b-1) contained in 100 parts by mass of the monomer mixture is 30 to 50 parts by mass. (2) The amount of the carboxyl group-containing monomer (b-2) contained in 100 parts by mass of the monomer mixture is 0 to 5 parts by mass.

9. The method for producing an emulsion composition according to claim 7, wherein the content of 2-ethylhexyl acrylate (b-1) and 2-ethylhexyl alcohol derived from (b-1) in the emulsion composition for an aqueous coating agent is each less than 300 ppm.

10. The emulsion composition was applied to paper at a solid content of 10 g / m ２ 8. The method for producing an emulsion composition for aqueous coating agents according to claim 7, wherein the odor intensity of the coated paper measured with an odor measuring device is 350 or less.

11. 8. The method for producing an emulsion composition for an aqueous coating agent according to claim 7, wherein the dioctyl sodium sulfosuccinate (A) is used in an amount of 0.1 to 2.0% by mass based on the monomer mixture.

12. The method for producing an emulsion composition for an aqueous coating agent according to claim 7, wherein the monomer (b-2) having a carboxyl group is at least one selected from the group consisting of acrylic acid, methacrylic acid, itaconic acid, and fumaric acid.

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