Method for manufacturing resin aqueous dispersion composition

Abstract

To provide a method for manufacturing a resin aqueous dispersion composition causing a small amount of resin residue.SOLUTION: A method for manufacturing an aqueous dispersion composition, which includes a copolymer including a structural unit derived from acrylic acid, and a neutralizer, includes mixing the copolymer, the neutralizer, and water in a stirring container with stirring means by the stirring means. A value of X / Y is 0.8 or more, where a diameter of the stirring means is X(m), and a diameter of the stirring container is Y(m).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing an aqueous dispersion composition containing a polymer. Specifically, the present disclosure relates to a method for producing an aqueous dispersion composition containing a polymer including structural units derived from acrylic acid and a neutralizing agent. [Background technology]

[0002] Certain resins are capable of forming films with good thermal adhesion, and are therefore used in a wide range of applications, such as coating agents, heat sealing agents, dilatation tack agents, in-mold labels, percoat agents, fiber treatment agents, and various binders.

[0003] Resins used in these various applications may be used in a solid state or in a dissolved or dispersed state in a solvent or water. The former is difficult to form a thin film, and therefore it is difficult to meet the recent global demand for a reduction in the amount of plastic used. Therefore, when forming a film, the latter state has become more common. Among the latter state resins, there is a growing demand for aqueous resins, particularly those dispersed in water, that do not require the use of organic solvents, particularly from the viewpoints of resource conservation, safety, and environmental issues. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 50-135141 [Patent Document 2] Patent No. 6426751 [Patent Document 3] Patent No. 4364983 Summary of the Invention [Problem to be solved by the invention]

[0005] In view of the above circumstances, there is an increasing demand for aqueous resin dispersion compositions with excellent performance. In particular, depending on the type and application of the substrate, there is a demand for aqueous resin dispersion compositions with a low amount of resin residue. Therefore, the present inventors have conducted research to obtain an aqueous resin dispersion composition with a small amount of resin residue. [Means for solving the problem]

[0006] The present disclosure includes, for example, the subject matter described in the following sections: Section 1. A method for producing an aqueous dispersion composition containing a copolymer containing a structural unit derived from acrylic acid and a neutralizing agent, comprising: mixing the copolymer, the neutralizing agent, and water in a stirring vessel equipped with a stirring means by the stirring means; When the diameter of the stirring means is X (m) and the diameter of the stirring vessel is Y (m), the value of X / Y is 0.8 or more. Method for producing an aqueous dispersion composition. Section 2. A method for producing an aqueous dispersion composition containing a copolymer containing a structural unit derived from acrylic acid and a neutralizing agent, comprising: mixing the copolymer, the neutralizing agent, and water in a twin-screw extruder; Method for producing an aqueous dispersion composition. Section 3. A method for producing an aqueous dispersion composition containing a copolymer containing a structural unit derived from acrylic acid and a neutralizing agent, comprising: mixing the copolymer, the neutralizing agent, and water in a twin-screw extruder; Item 1. A method for producing the aqueous dispersion composition according to item 1. [Effects of the Invention]

[0007] It is possible to produce an aqueous resin dispersion composition with a small amount of resin residue. DETAILED DESCRIPTION OF THE INVENTION

[0008] Each embodiment included in the present disclosure will be described in more detail below. The present disclosure includes a method for producing an aqueous dispersion composition containing a copolymer containing structural units derived from acrylic acid and a neutralizing agent, the method comprising mixing the copolymer and the neutralizing agent in a stirring vessel equipped with a stirring means by the stirring means, wherein the value of X / Y, where X (m) is the diameter of the stirring means and Y (m) is the diameter of the stirring vessel, is 0.8 or more. This production method is sometimes referred to as the production method of the present disclosure.

[0009] Polymers containing structural units derived from acrylic acid are acrylic acid polymers (polyacrylic acids) or copolymers containing structural units derived from acrylic acid and structural units derived from monomers other than acrylic acid (other monomer components). Examples of other monomer components include α,β-unsaturated carboxylic acids such as methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, as well as ethylene, propylene, butene, isobutene, butadiene, isoprene, and styrene. These other monomer components can be used alone or in combination of two or more. Among other monomer components, ethylene is more preferred. That is, copolymers containing structural units derived from acrylic acid and structural units derived from ethylene are particularly preferred. Copolymers containing structural units derived from acrylic acid and structural units derived from ethylene may also contain structural units derived from one or more other monomer components. For convenience, acrylic acid polymers (polyacrylic acids) are referred to as acrylic acid copolymers containing 0% by mass of structural units derived from other monomer components, and polymers containing structural units derived from acrylic acid used in the production methods of the present disclosure may be referred to as the acrylic acid copolymers of the present disclosure. In other words, the "acrylic acid copolymer of the present disclosure" includes acrylic acid polymers (polyacrylic acids). The acrylic acid copolymer of the present disclosure preferably contains 1 to 100 mass% of structural units derived from acrylic acid, and the upper and lower limits of this range are 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, The content may be 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, or 99% by mass. The range may be, for example, 2 to 80% by mass or 3 to 50% by mass. It is more preferably 4 to 30% by mass, and even more preferably 5 to 25% by mass. The content (mass %) of constitutional units derived from acrylic acid in the acrylic acid copolymer of the present disclosure can also be said to be the amount of acrylic acid relative to the total amount of monomers that contributed to the constitution of the copolymer.

[0010] Among the acrylic acid copolymers of the present disclosure, copolymers containing structural units derived from acrylic acid and structural units derived from ethylene (in other words, copolymers with ethylene and acrylic acid as monomers) are particularly preferred. As described above, the copolymer may contain structural units other than structural units derived from ethylene and structural units derived from acrylic acid. Examples of such structural units include structural units derived from α,β-unsaturated carboxylic acids such as methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid, as well as structural units derived from propylene, butene, isobutene, butadiene, isoprene, and styrene. When these are used, they may be used alone or in combination of two or more. Although not particularly limited, of all the structural units of a copolymer containing structural units derived from acrylic acid and structural units derived from ethylene, the total of the structural units derived from acrylic acid and structural units derived from ethylene is preferably 80 mol % or more, and more preferably 85, 90, 95, 96, 97, 98, or 99 mol % or more of the structural units derived from acrylic acid and structural units derived from ethylene. The total of the structural units derived from acrylic acid and structural units derived from ethylene may be 100 mol % or more (i.e., ethylene / acrylic acid copolymer: EAA).

[0011] Although not particularly limited, the acrylic acid copolymer of the present disclosure preferably has a melt index of about 10 to 500 g / 10 min. A melt index of 10 g / 10 min or more makes it easier to emulsify, and a melt index of 500 g / 10 min or less makes it less sticky and easier to handle. The upper or lower limit of the range may be, for example, 20, 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 160, 170, 180, 190, 200, 210, 220, 230, 240, 250, 260, 270, 280, 290, 300, 310, 320, 330, 340, 350, 360, 370, 380, 390, 400, 410, 420, 430, 440, 450, 460, 470, 480, or 490 g / 10 min. The range may be, for example, 20 to 450 g / 10 min or 40 to 400 g / 10 min. In this disclosure, the melt index is a value obtained by heating and pressurizing a resin placed in a cylindrical extrusion plastometer at a constant temperature (190°C) and measuring the amount of resin extruded from the opening at the bottom of the container in 10 minutes.

[0012] In order to adjust the content of structural units derived from acrylic acid in the acrylic acid copolymer of the present disclosure, two or more (preferably 2, 3, 4, or 5, more preferably 2 or 3, and even more preferably 2) polymers that fall under the acrylic acid copolymer of the present disclosure and have different contents of structural units derived from acrylic acid may be mixed and used. The mixing method is not particularly limited, but a method in which two or more types of acrylic acid copolymers of the present disclosure are mixed uniformly is preferred. Examples of mixing methods include a method in which two or more types of acrylic acid copolymers of the present disclosure are dissolved in a solvent and then the solvent is removed, and a method in which the copolymers are kneaded together (mixed while kneading). Among the kneading methods, melt kneading (preferably, kneading while melting the copolymers at a temperature equal to or higher than the melting points of all the copolymers to be mixed) is preferred. Specific kneading means include a single-screw or multiple-screw extruder, a kneader, and the like. As the multiple-screw extruder, a twin-screw extruder or a four-screw extruder is preferred, and a twin-screw extruder is more preferred. In particular, when melt kneading is performed, for example, a single-screw or multiple-screw extruder (particularly a twin-screw extruder) is preferred. Furthermore, the temperature when melt kneading is preferably a temperature equal to or higher than the melting point of the acrylic acid copolymer of the present disclosure having the highest melting point among the two or more acrylic acid copolymers of the present disclosure used. Specific temperatures vary depending on the melting points of the two or more acrylic acid copolymers of the present disclosure used, but may be, for example, about 100 to 250°C. The upper or lower limit of this range (100 to 250°C) may be, for example, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, 220, 225, 230, 235, 240, or 245°C. For example, the range is preferably about 110 to 220°C or about 120 to 180°C. The time for mixing (preferably melt-kneading) is not particularly limited as long as the effects of the present invention are not impaired, and can be set appropriately. Although it depends on the mixing means used, it is exemplified as about 1 to 60 minutes.

[0013] A composition obtained by blending two or more acrylic acid copolymers of the present disclosure can also be preferably used as a copolymer containing structural units derived from acrylic acid (acrylic acid copolymer of the present disclosure) in the production method of the present disclosure. In this case, the two or more copolymers to be blended are not particularly limited, but it is preferable that at least one of the structural units contained therein is a copolymer in common, and it is more preferable that all of the structural units contained therein are a copolymer in common. In other words, if one of the copolymers to be blended is, for example, a copolymer containing structural units derived from acrylic acid and structural units derived from ethylene, it is preferable that the remaining one or more copolymers to be blended are also copolymers containing structural units derived from acrylic acid and structural units derived from ethylene. Furthermore, if one of the copolymers to be blended is, for example, an ethylene / acrylic acid copolymer, it is more preferable that the remaining one or more copolymers to be blended are also ethylene / acrylic acid copolymers.

[0014] In the production method of the present disclosure, the copolymer of the present disclosure, a neutralizing agent, and water are mixed using a specific mixer. This mixing results in emulsification, resulting in an aqueous dispersion composition. This aqueous dispersion composition may be referred to as the aqueous dispersion composition of the present disclosure. The agitator used in the manufacturing method of the present disclosure has a stirring vessel equipped with a stirring means, and further, when the diameter of the stirring means is X (m) and the diameter of the stirring vessel is Y (m), the value of X / Y is 0.8 or greater. The upper limit of this value is not particularly limited, but it may be less than 1, and more specifically, 0.999 is an example. The upper or lower limit of this range (0.8 to 0.999) may be, for example, 0.81, 0.82, 0.83, 0.84, 0.85, 0.86, 0.87, 0.88, 0.89, 0.9, 0.91, 0.92, 0.93, 0.94, 0.95, 0.96, 0.97, 0.98, 0.99, or 0.995. For example, the range may be 0.81 to 0.99. The stirring means is not particularly limited, and is preferably a known stirring means, more specifically, for example, a stirring blade. The diameter of the stirring means is the maximum diameter generated when the stirring means rotates. If the diameter value is not constant, the longest value is used. For example, in a stirrer equipped with a long stirring blade and a short stirring blade as the stirring means, the diameter of the stirring means is the maximum diameter of the circle generated when the long stirring blade rotates. The diameter of the agitator vessel is the diameter of the narrowest part through which the agitator can pass. For example, in the case of a single-screw or multiple-screw (e.g., twin-screw or four-screw) extruder, it is the cylinder diameter. For example, if a mixer with an agitator blade having a radius of 4 cm is placed at the center of a square agitator vessel with sides of 10 cm, the diameter of the narrowest part through which the agitator blade can pass is the length of one side (10 cm), not the length of the diagonal of the square. In this case, X / Y = 0.08 / 0.1 = 0.8.

[0015] Such a stirrer is not particularly limited as long as it satisfies the above conditions, and examples thereof include a single-screw or multiple-screw (e.g., twin-screw or four-screw) extruder, an autoclave, a kneader, etc. Among these, a twin-screw extruder is particularly preferred. As the neutralizing agent, for example, ammonia, organic amines, and alkali metal salts can be preferably used. As the organic amine, for example, diisopropanolamine, 2-amino-2-methyl-1-propanol, triethanolamine, etc. are preferred. Furthermore, as the alkali metal salt, for example, sodium hydroxide, potassium hydroxide, etc. are preferred. Among the neutralizing agents, ammonia is particularly preferred. The neutralizing agents can be used alone or in combination of two or more. The amount of neutralizing agent used can be set, for example, so that the degree of neutralization of the acrylic acid copolymer of the present disclosure (mol % of the acrylic acid moieties in the polymer that are neutralized) is about 25 to 65%. The upper or lower limit of this range may be, for example, 30, 35, 40, 45, 50, 55, or 60%. For example, this range may be about 30 to 60%.

[0016] The amount of water used is not particularly limited, but is set to, for example, 10 to 1000 parts by mass, preferably 10 to 250 parts by mass, relative to 100 parts by mass of the acrylic acid copolymer of the present disclosure. By using an aqueous medium in such a range, an aqueous dispersion composition with good dispersion stability can be obtained. Furthermore, an aqueous dispersion composition with excellent productivity and practicality can be obtained.

[0017] The resulting aqueous dispersion composition may further contain other components within a range that does not particularly impair the effects of the present invention, such as surfactants, defoamers, viscosity adjusters, pH adjusters, antifungal agents, antioxidants, blocking improvers such as fatty acid amides, waxes, and silicone oils, and alcohols. As described above, the aqueous dispersion composition of the present disclosure can form a film that exhibits excellent blocking resistance. More specifically, the aqueous dispersion composition of the present disclosure has a basis weight of 52 g / m 2 Dry coating weight 5.0g / m on high-quality paper 2 When the coated surfaces of the resulting coated papers were placed together, a sealing pressure of 5 kg / cm was applied. 2 The resulting adhesive paper (test piece) is subjected to a T-peel test (tensile speed: 300 mm / min) in accordance with JIS Z 0238 (1998). The maximum temperature at which interfacial peeling occurs without tearing the paper is preferably 70°C or higher, more preferably 70 to 90°C, even more preferably 70 to 85°C, and even more preferably 70 to 80°C.

[0018] The aqueous dispersion composition of the present disclosure also has excellent dispersibility of the resin (i.e., the acrylic acid copolymer of the present disclosure). More specifically, when the aqueous dispersion composition of the present disclosure is filtered through an 80-mesh polyethylene screen and the residue is dried by heating at 60°C for 2 hours, the amount of the resulting dried residue is preferably 2.5% by mass or less, more preferably 2% by mass or less, even more preferably 1% by mass or less, even more preferably 0.5% by mass or less, and particularly preferably 0.1% by mass or less, based on the total amount of the acrylic acid copolymer of the present disclosure used in producing the aqueous dispersion composition.

[0019] In the aqueous dispersion composition of the present disclosure, the polymer of the present disclosure is preferably about 10 to 40% by mass, although this is not particularly limited as long as the effect is not impaired. The upper or lower limit of this range may be, for example, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, or 39% by mass. For example, the range may be 15 to 35% by mass or 20 to 30% by mass. The aqueous dispersion composition of the present disclosure may contain other components within the scope of not impairing the effects of the present invention, such as a defoaming agent, a viscosity adjuster, a pH adjuster, a surfactant, an antifungal agent, etc., and, if necessary, an antioxidant, a blocking improver such as a fatty acid amide, a wax, or a silicone oil, an alcohol, etc. The aqueous dispersion composition of the present disclosure is useful, for example, as a binder or coating agent. The composition of the present disclosure can be applied to a base and dried to form a film. A preferred example of the base is paper, and more preferred is packaging paper for food and beverages. The film can prevent food and beverages from coming into direct contact with the paper (packaging paper). Furthermore, the film is preferred because it has little adverse effect on food and beverages. The present disclosure also preferably encompasses, for example, a laminate comprising a substrate (preferably paper) and a coating on the substrate, the coating being formed by coating the aqueous dispersion composition of the present disclosure on the substrate.

[0020] It should be noted that in this specification, the term "comprising" includes "consisting essentially of" and "consisting of." Furthermore, the present disclosure encompasses all arbitrary combinations of the constituent elements described in this specification. Furthermore, the various characteristics (properties, structures, functions, etc.) described in each embodiment of the present disclosure above may be combined in any way to specify the subject matter encompassed by the present disclosure, i.e., the present disclosure encompasses all subject matter consisting of any combination of the combinable characteristics described herein. [Example]

[0021] Hereinafter, the embodiments of the present disclosure will be described more specifically with reference to examples, but the embodiments of the present disclosure are not limited to the following examples.

[0022] Preparation of aqueous dispersion composition Example 1 A hopper was installed at the upstream end of a twin-screw extruder (model: MFU15 (manufactured by Technobel Co., Ltd.), shaft diameter: 15 mm, L / D: 90), and 0.7 kg / hr of ethylene / acrylic acid copolymer (20.0% by mass of structural units derived from acrylic acid, melt index: 300 g / 10 min) and 0.3 kg / hr of ethylene / acrylic acid copolymer (15.0% by mass of structural units derived from acrylic acid, melt index: 60 g / 10 min) were mixed and fed into the extruder. The extruder was melt-mixed at a cylinder temperature of 140°C and a rotation speed of 300 rpm. After melt-kneading, a 2% by mass aqueous ammonia solution (25°C) was fed into the extruder via a second feed port located 530 mm from the upstream end of the extruder at a rate of 1.00 kg / hr. The mixture was kneaded and emulsified from the upstream tip of the twin-screw extruder to a third supply port located 1,175 mm away at a cylinder temperature of 90°C and a rotation speed of 300 rpm. Pure water was then supplied from the third supply port at a rate of 2.0 kg / hr using a plunger pump, and the mixture was kneaded from the third supply port to the outlet of the twin-screw extruder at a cylinder temperature of 90°C and a rotation speed of 300 rpm. The mixture was then discharged from the twin-screw extruder, yielding an aqueous dispersion composition of ethylene / acrylic acid copolymer with an acrylic acid-derived structural unit content of 18.5% by mass.

[0023] Example 2 A hopper was installed at the upstream end of a twin-screw extruder (model: MFU15 (manufactured by Technobel Co., Ltd.), shaft diameter: 15 mm, L / D: 90), and 0.5 kg / hr of ethylene / acrylic acid copolymer (20.0% by mass of structural units derived from acrylic acid, melt index: 300 g / 10 min) and 0.5 kg / hr of ethylene / acrylic acid copolymer (15.0% by mass of structural units derived from acrylic acid, melt index: 60 g / 10 min) were mixed and fed. After melt-kneading at a cylinder temperature of 140 °C and a rotation speed of 300 rpm, a 2% by mass aqueous ammonia solution (25 °C) was fed as a neutralizing agent at a rate of 1.00 kg / hr using a plunger pump through a second feed port located 530 mm from the upstream end of the twin-screw extruder. Kneading and emulsification were carried out from the upstream tip of the twin-screw extruder to a third supply port located 1,175 mm away at a cylinder temperature of 90°C and a rotation speed of 300 rpm, and then pure water was supplied from the third supply port using a plunger pump at a rate of 2.0 kg / hr. Kneading was carried out from the third supply port to the outlet of the twin-screw extruder at a cylinder temperature of 90°C and a rotation speed of 300 rpm, and then the mixture was discharged from the twin-screw extruder, yielding an aqueous dispersion composition of ethylene / acrylic acid copolymer with an acrylic acid-derived structural unit content of 17.5% by mass.

[0024] Example 3 A hopper was installed at the upstream end of a twin-screw extruder (model: MFU15 (manufactured by Technovel Co., Ltd.), shaft diameter: 15 mm, L / D: 90), and ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 20.0% by mass, melt index: 300 g / 10 min) and ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 15.0% by mass, melt index: 60 g / 10 min) were mixed and charged at 0.3 kg / hr and 0.7 kg / hr, respectively. After melt-kneading at a cylinder temperature of 140 °C and a rotation speed of 300 rpm, a 2% by mass aqueous ammonia solution (25 °C) was fed as a neutralizing agent at 1.00 kg / hr using a plunger pump through a second feed port located 530 mm from the upstream end of the twin-screw extruder. Kneading and emulsification were carried out from the upstream tip of the twin-screw extruder to a third supply port located 1,175 mm away at a cylinder temperature of 90°C and a rotation speed of 300 rpm, and then pure water was supplied from the third supply port using a plunger pump at a rate of 2.0 kg / hr. Kneading was carried out from the third supply port to the outlet of the twin-screw extruder at a cylinder temperature of 90°C and a rotation speed of 300 rpm, and then the mixture was discharged from the twin-screw extruder, yielding an aqueous dispersion composition of ethylene / acrylic acid copolymer with an acrylic acid-derived structural unit content of 16.5% by mass.

[0025] Example 4 A hopper was installed at the upstream end of a twin-screw extruder (model: MFU15 (manufactured by Technobel Co., Ltd.), shaft diameter: 15 mm, L / D: 90), and ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 15.0% by mass, melt index: 60 g / 10 min) was added at a rate of 1.0 kg / hr. After melt-kneading at a cylinder temperature of 140 °C and a rotation speed of 900 rpm, a 2% by mass aqueous ammonia solution (25 °C) was added as a neutralizing agent at a rate of 2.00 kg / hr using a plunger pump through a second feed port located 530 mm from the upstream end of the twin-screw extruder. The mixture was kneaded and emulsified from the upstream tip of the twin-screw extruder to a third supply port located 1,175 mm away at a cylinder temperature of 90°C and a rotation speed of 900 rpm. Pure water was then supplied from the third supply port at a rate of 1.0 kg / hr using a plunger pump, and the mixture was kneaded from the third supply port to the outlet of the twin-screw extruder at a cylinder temperature of 90°C and a rotation speed of 900 rpm. The mixture was then discharged from the twin-screw extruder, yielding an aqueous dispersion composition of ethylene / acrylic acid copolymer with an acrylic acid-derived structural unit content of 15% by mass.

[0026] (Comparative Example 1) A hopper was installed at the upstream end of a twin-screw extruder (model: KZW15 (manufactured by Technobel Co., Ltd.), shaft diameter: 15 mm, L / D: 45), and 0.7 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 20.0% by mass, melt index: 300 g / 10 min) and 0.3 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 15.0% by mass, melt index: 60 g / 10 min) were mixed and charged. After melt-kneading at a cylinder temperature of 120 ° C and a rotation speed of 50 rpm, the resin discharged from the twin-screw extruder was cooled in a water bath at 25 ° C and cut into pellets using a pelletizer to obtain an ethylene / acrylic acid copolymer with a structural unit content of 18.5% by mass derived from acrylic acid. A 1000 ml pressure vessel (autoclave) equipped with a stirrer was charged with 75 g of the obtained copolymer, 5.38 g of 28% by mass ammonia water as a neutralizing agent, and 115.1 g of water, and sealed. The mixture was then heated from 25°C to 95°C while stirring at 500 rpm, and the vessel was maintained at 95°C for 4 hours while stirring. The mixture was then allowed to cool to 90°C at room temperature, and 104.5 g of pure water was added. The mixture was then allowed to cool to 50°C at room temperature, and the contents were filtered through an 80-mesh polyethylene screen to obtain an aqueous dispersion composition of ethylene / acrylic acid copolymer with an acrylic acid-derived structural unit content of 18.5% by mass.

[0027] (Comparative Example 2) A hopper was installed at the upstream end of a twin-screw extruder (model: KZW15 (manufactured by Technobel Co., Ltd.), shaft diameter: 15 mm, L / D: 45), and 0.5 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 20.0% by mass, melt index: 300 g / 10 min) and 0.5 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 15.0% by mass, melt index: 60 g / 10 min) were mixed and charged. After melt-kneading at a cylinder temperature of 120 ° C and a rotation speed of 50 rpm, the resin discharged from the twin-screw extruder was cooled in a water bath at 25 ° C and cut into pellets using a pelletizer to obtain an ethylene / acrylic acid copolymer with a structural unit content of 17.5% by mass derived from acrylic acid. A 1000 ml pressure vessel (autoclave) equipped with a stirrer was charged with 75 g of the obtained copolymer, 5.36 g of 28% by weight ammonia water as a neutralizing agent, and 114.8 g of water, and sealed. The mixture was then heated from 25°C to 95°C while stirring at 500 rpm, and the temperature inside the vessel was maintained at 95°C for 4 hours. The mixture was then allowed to cool to 90°C at room temperature, and 104.9 g of pure water was added. The contents were then allowed to cool to 50°C at room temperature, and the contents were filtered through an 80-mesh polyethylene screen to obtain an aqueous dispersion composition of ethylene / acrylic acid copolymer with an acrylic acid-derived structural unit content of 17.5% by weight.

[0028] (Comparative Example 3) A hopper was installed at the upstream end of a twin-screw extruder (model: KZW15 (manufactured by Technobel Co., Ltd.), shaft diameter: 15 mm, L / D: 45), and 0.3 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 20.0% by mass, melt index: 300 g / 10 min) and 0.7 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 15.0% by mass, melt index: 60 g / 10 min) were mixed and charged. After melt-kneading at a cylinder temperature of 120 ° C and a rotation speed of 50 rpm, the resin discharged from the twin-screw extruder was cooled in a water bath at 25 ° C and cut into pellets using a pelletizer to obtain an ethylene / acrylic acid copolymer with a structural unit content of 16.5% by mass derived from acrylic acid. A 1000 ml pressure vessel (autoclave) equipped with a stirrer was charged with 75 g of the obtained copolymer, 5.37 g of 28% by weight aqueous ammonia as a neutralizing agent, and 114.9 g of water, and sealed. The mixture was then heated from 25°C to 95°C while stirring at 500 rpm, and the temperature inside the vessel was maintained at 95°C for 4 hours. The mixture was then allowed to cool to 90°C at room temperature, and 104.7 g of pure water was added. The contents were then allowed to cool to 50°C at room temperature, and the contents were filtered through an 80-mesh polyethylene screen to obtain an aqueous dispersion composition of ethylene / acrylic acid copolymer with an acrylic acid-derived structural unit content of 16.5% by weight.

[0029] The cylinder diameter of the twin-screw extruder (model: MFU15) used was 15.2 mm. Therefore, the diameter (X) of the stirring means (screw shaft diameter) of the twin-screw extruder was 15 mm, and the diameter (Y) of the stirring vessel (cylinder) was 15.2 mm, so X / Y ≈ 0.99.

[0030] The diameter (X) of the stirring blades of the stirrer in the pressure-resistant vessel with a stirrer used was 500 mm, and the diameter (Y) of the heat-resistant vessel was 936 mm, so that X / Y≈0.53.

[0031] How to make coated paper (1) The aqueous dispersion compositions prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were mixed in a 52 g / m 2Wet coating weight 10g / m on high-quality paper 2 , Dry coating amount 2.5g / m 2 The coating was carried out using an automatic applicator, AUTOMATIC FILM APPLICATOR 1811 / 3, manufactured by BEVS, so that the coating thickness would be as follows: (2) The coated paper obtained in (1) above was dried by heating at 125°C for 2 minutes using a heating dryer (DRE320DR manufactured by ADVANTEC). (3) The coated surface of the coated paper obtained in (2) above was again coated with the aqueous dispersion composition in the same manner as in (1). (4) The coated paper obtained in (3) above was dried under the same drying conditions as in (2) above, and finally the dry coating weight was 5.0 g / m 2 Thus, a coated paper having the following properties was obtained.

[0032] Measurement method [Blocking resistance] The two sheets of coated paper were stacked with their coated surfaces facing each other, and a heat seal tester manufactured by Tester Sangyo Co., Ltd. was used to seal the sheets at a pressure of 5 kg / cm. 2 The test pieces were sealed for 2 hours at sealing temperatures of 60, 65, 70, 75, and 80°C. A T-peel test was performed on each test piece according to JIS Z 0238 (1998). The highest temperature at which the paper could be peeled without breaking was determined as the blocking temperature. The higher the blocking temperature, the higher the blocking resistance. The T-peel test was performed using an autograph (Shimadzu Corporation, Model AGS-X) at a tension speed of 300 mm / min.

[0033] [Residue rate] The produced aqueous dispersion composition was filtered through an 80-mesh polyethylene mesh, and the residue was heated and dried in a heating dryer (DRE320DR manufactured by ADVANTEC) at 60°C for 2 hours. The weight of the dried residue was measured, and the residue rate was calculated using the following formula. Residue rate (mass%) = dried residue mass / charged resin mass × 100

[0034] The results are summarized in Table 1. [Table 1] [Industrial Applicability]

[0035] According to the present disclosure, a method for producing an aqueous dispersion composition with a low amount of resin residue can be provided. Such an aqueous dispersion composition can be said to be a material that meets the recent global demand for reducing the amount of plastic used, and is an environmentally friendly material.

Claims

1. A method for producing an aqueous dispersion composition containing a copolymer containing a structural unit derived from acrylic acid and a neutralizing agent, comprising: mixing the copolymer, the neutralizing agent, and water in a stirring vessel equipped with a stirring means by the stirring means; The value of X / Y is 0.8 or more, where X (m) is the diameter of the stirring means and Y (m) is the diameter of the stirring vessel. Method for producing an aqueous dispersion composition.

2. A method for producing an aqueous dispersion composition containing a copolymer containing a structural unit derived from acrylic acid and a neutralizing agent, comprising: mixing the copolymer, the neutralizing agent, and water in a twin-screw extruder; Method for producing an aqueous dispersion composition.

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