Resin aqueous dispersion composition

Abstract

Provided is a resin aqueous dispersion composition that has a suitable viscosity and excellent handling properties and that exhibits excellent barrier properties (water resistance and water vapor barrier property) when a film is formed (for example, when the coating film is formed). More specifically, the following aqueous dispersion composition is provided. An aqueous dispersion composition according to the present invention contains a copolymer containing a constituent unit derived from a compound having an ethylene skeleton and a constituent unit derived from acrylic acid, and ammonia, wherein the content of the constituent units derived from acrylic acid in the copolymer is 5-19 mass%, and the degree of resin neutralization calculated by the following formula is 5-10 mass%. (Formula) Degree of resin neutralization (mass%)=[content (mass%) of constituent units derived from acrylic acid in the copolymer] ×[molar ratio (mol%) of ammonia to constituent units derived from acrylic acid in the copolymer] / 100

Description

Resin aqueous dispersion composition

[0001] The present disclosure relates to an aqueous dispersion composition containing a copolymer, etc. In particular, the present disclosure relates to an aqueous dispersion composition containing a copolymer including structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid, and ammonia.

[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 with, and therefore 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 has been 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.

[0004] JP-A-50-135141 Patent No. 6426751 Patent No. 4364983

[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, improvements in the handleability of the aqueous resin dispersion composition and the barrier properties (water resistance and water vapor barrier properties) of the resulting film may be required.

[0006] The present disclosure includes, for example, the subject matter described in the following items. Item 1. An aqueous dispersion composition comprising a copolymer containing structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid, and ammonia, wherein the content of the structural units derived from acrylic acid relative to the copolymer is 5 to 19% by mass, and the resin neutralization degree calculated by the following formula is 5 to 10% by mass: Resin neutralization degree (mass %) = Content (mass %) of structural units derived from acrylic acid relative to the copolymer × mol % of ammonia relative to the structural units derived from acrylic acid in the copolymer / 100 (Formula) Item 2. The aqueous dispersion composition according to Item 1, which contains 10 to 40% by mass of the copolymer. Item 3. The aqueous dispersion composition according to Item 1 or 2, wherein the viscosity of the aqueous dispersion composition at 25°C is 1,000 mPa s or less. Item 4. The aqueous dispersion composition according to Item 1, wherein the compound having an ethylene skeleton is a compound represented by Formula (1): CHR １ = CHR ２ (1) (wherein, R １ and R ２ and are the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. Item 5. The aqueous dispersion composition according to any one of Items 1 to 3, wherein the copolymer is an ethylene / acrylic acid copolymer. Item 6. A laminate comprising a substrate and a coating on the substrate, wherein the coating is formed by coating the aqueous dispersion composition according to any one of Items 1 to 5 on the substrate. Item 7. Coated paper formed by coating paper with the aqueous dispersion composition according to any one of Items 1 to 5.

[0007] According to the present disclosure, there is provided an aqueous resin dispersion composition that has a suitable viscosity for excellent handleability and is capable of forming a film that exhibits excellent water resistance and water vapor barrier properties. In a preferred embodiment, the film formed by the aqueous resin dispersion composition further exhibits blocking resistance and / or heat sealability sufficient for practical use.

[0008] Each embodiment of the present disclosure will be described in more detail below. The present disclosure preferably includes, but is not limited to, an aqueous resin dispersion composition containing a specific resin and ammonia under specific conditions, and the present disclosure includes all inventions disclosed herein that would be recognizable to a person skilled in the art.

[0009] As described above, the resin aqueous dispersion composition encompassed by the present disclosure contains a specific resin and ammonia. This resin aqueous dispersion composition may be referred to as the aqueous dispersion composition of the present disclosure. The specific resin is a copolymer containing structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid. The specific resin (i.e., a copolymer containing structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid) may be referred to as the polymer of the present disclosure.

[0010] As described above, the polymer of the present disclosure is a copolymer containing a structural unit derived from a compound having an ethylene skeleton and a structural unit derived from acrylic acid (in other words, a copolymer in which a compound having an ethylene skeleton and acrylic acid are monomers).

[0011] The compound having an ethylene skeleton in the present disclosure is a compound having an ethylene skeleton and no carboxyl group. Preferably, the compound has a structure represented by the formula (1): １ = CHR ２ (1) (wherein, R １ and R ２ and are the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms. The compound of formula (1) may be a cis or trans isomer.

[0012] Examples of halogen atoms include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms, with fluorine atoms and chlorine atoms being particularly preferred. Furthermore, alkyl groups having 1 to 6 carbon atoms (1, 2, 3, 4, 5, or 6) may be linear or branched, with linear groups being preferred. The alkyl group more preferably has 1 to 4 carbon atoms. More specific examples include methyl groups, ethyl groups, n-propyl groups, isopropyl groups, n-butyl groups, isobutyl groups, sec-butyl groups, isobutyl groups, and tert-butyl groups. Examples of aryl groups having 6 to 10 carbon atoms (6, 7, 8, 9, or 10) include phenyl groups, toluyl groups, xylyl groups, and naphthyl groups.

[0013] The compound having an ethylene skeleton is more preferably a compound represented by formula (1a): CHR １ =CH ２ (1a) (wherein, R １ is the same as above).

[0014] Particularly preferred compounds having an ethylene skeleton include ethylene and styrene, with ethylene being particularly preferred.

[0015] In the polymer of the present disclosure, the compound having an ethylene skeleton can be used alone or in combination of two or more kinds, and it is more preferable to use one kind alone.

[0016] The polymer of the present disclosure may contain structural units other than structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid, as long as the effects of the present invention are not impaired. 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 butadiene and isoprene. When these are used, they may be used alone or in combination of two or more.

[0017] Although not particularly limited, of all the structural units of the polymer of the present disclosure, the total of structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid is preferably 80 mol% or more, and more preferably 85, 90, 95, 96, 97, 98, or 99 mol% or more. The total of structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid may be 100 mol%. Note that when 100 mol% are structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid, and the compound having an ethylene skeleton is ethylene, the polymer of the present disclosure is an ethylene / acrylic acid copolymer. Furthermore, when 100 mol% are structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid, and the compound having an ethylene skeleton is styrene, the polymer of the present disclosure is a styrene / acrylic acid copolymer.

[0018] The polymer of the present disclosure has a content of constitutional units derived from acrylic acid of 5 to 19% by mass. The upper or lower limit of this range may be, for example, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13, 13.5, 14, 14.5, 15, 15.5, 16, 16.5, 17, 17.5, 18, or 18.5% by mass. For example, it may be 5.5 to 18.5% by mass.

[0019] The content (mass%) of structural units derived from acrylic acid in the acrylic acid copolymer of the present disclosure can be calculated from the amount of acrylic acid relative to the total amount of monomers that contribute to the constitution of the copolymer.

[0020] In addition, in order to adjust the content of structural units derived from acrylic acid in the polymer of the present disclosure, two or more types of polymers (preferably 2, 3, 4, or 5 types, more preferably 2 or 3 types, and even more preferably 2 types) that fall under the polymer of the present disclosure and have different contents of structural units derived from acrylic acid may be mixed and used. The mixing is preferably melt-kneading, particularly from the viewpoint of uniform mixing. A composition obtained by mixing two or more polymers of the present disclosure can also be preferably used as the polymer of the present disclosure. For example, by mixing equal amounts of a polymer of the present disclosure having a structural unit content of 20% by mass and a polymer of the present disclosure having a structural unit content of acrylic acid of 15% by mass, the polymer can be used as the polymer of the present disclosure having a structural unit content of 17.5% by mass.

[0021] Although not particularly limited, the mass ratio of the structural units derived from a compound having an ethylene skeleton and the structural units derived from acrylic acid in the polymer of the present disclosure (structural units derived from a compound having an ethylene skeleton:structural units derived from acrylic acid) is preferably about 95:5 to 81:19.

[0022] Although not particularly limited, the polymer 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 the polymer more easily emulsifiable, and a melt index of 500 g / 10 min or less makes the polymer 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.

[0023] In the present disclosure, the melt index is a value obtained by heating and pressurizing a resin placed in a cylindrical extrusion-type 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.

[0024] The aqueous dispersion composition of the present disclosure has a resin neutralization degree of 5 to 10% by mass, calculated by the following formula: Resin neutralization degree (mass%) = [Content (mass%) of structural units derived from acrylic acid relative to the polymer of the present disclosure] × [mol % of ammonia relative to the structural unit portion derived from acrylic acid in the polymer of the present disclosure] / 100. The upper or lower limit of this range (5 to 10% by mass) may be, for example, 5.5, 6, 6.5, 7, 7.5, 8, 8.5, 9, or 9.5% by mass. For example, it may be 5.5 to 9.5% by mass.

[0025] Furthermore, in the aqueous dispersion composition of the present disclosure, the degree of neutralization of acrylic acid in the copolymer of the present disclosure contained therein is preferably 35 to 65 mol%, more preferably 40 to 60 mol%, and even more preferably 45 to 55 mol%.

[0026] The degree of neutralization of acrylic acid is a value calculated by the following formula: Degree of neutralization of acrylic acid (mol %)=[number of moles of ammonia]÷[number of moles of structural units derived from acrylic acid in the copolymer]×100

[0027] The aqueous dispersion composition of the present disclosure may contain a base other than ammonia, as long as the effects of the invention according to the present disclosure are not impaired. Examples of such bases include organic amines and alkali metal hydroxides. Examples of organic amines include methylamine, ethylamine, diethylamine, diethanolamine, triethanolamine, etc. Examples of alkali metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, etc. When these are used, they may be used alone or in combination of two or more. However, since the effects may be impaired when a base other than ammonia is used, it is preferable to set the amount used relatively small, and it is more preferable that the only base contained in the aqueous dispersion composition of the present disclosure is ammonia.

[0028] Although not particularly limited as long as the effects of the invention according to the present disclosure are not impaired, the aqueous dispersion composition of the present disclosure preferably contains approximately 10 to 40% by mass of the polymer of the present disclosure. 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.

[0029] The viscosity of the aqueous dispersion composition of the present disclosure is preferably 1000 mPa·s or less. The lower limit is not particularly limited, but may be, for example, 10 mPa·s. The upper or lower limit of this range (10 to 1000 mPa·s) may be, for example, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, or 950 mPa·s. For example, the range may be 20 to 950 mPa·s or 50 to 900 mPa·s.

[0030] In the present disclosure, the viscosity of a composition is measured at 25°C using a Brookfield type rotational viscometer. Specifically, the viscosity is measured at 25°C by setting the rotation speed of the spindle rotor to 60 revolutions per minute and reading the viscosity value one minute after the rotor starts rotating. The rotor can be appropriately selected depending on the viscosity. As a guideline, rotor No. 3 is used for viscosity less than 2000 mPa·s, rotor No. 4 is used for viscosity from 2000 mPa·s to less than 5000 mPa·s, rotor No. 5 is used for viscosity from 5000 mPa·s to less than 15000 mPa·s, rotor No. 6 is used for viscosity from 15000 mPa·s to less than 40000 mPa·s, and rotor No. 7 is used for viscosity of 40000 mPa·s or more.

[0031] In the aqueous dispersion composition of the present disclosure, the aqueous medium is preferably water, and various types of water can be used, such as tap water, industrial water, ion-exchanged water, deionized water, pure water, etc. Deionized water or pure water is particularly preferred.

[0032] 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.

[0033] The aqueous dispersion composition of the present disclosure can be prepared, for example, by mixing the polymer of the present disclosure, ammonia, and an aqueous medium so that the polymer has a specific concentration and a specific resin neutralization degree, and then applying pressure and / or heat as necessary. Alternatively, the composition can be further diluted with water so that the polymer has a specific concentration.

[0034] The aqueous dispersion composition of the present disclosure is useful, for example, as a binder or coating agent. The aqueous dispersion composition of the present disclosure can be applied to a substrate and dried to form a film. A preferred example of the substrate is paper, and more preferred is food and beverage packaging paper. The film can prevent food and beverage from coming into direct contact with the paper (wrapping paper). Furthermore, the film is preferred because it has little adverse effect on the food and beverage.

[0035] 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.

[0036] When the substrate is paper, an example of the laminate is coated paper, which can be obtained, for example, by coating paper with the aqueous dispersion composition of the present disclosure.

[0037] The aqueous dispersion composition of the present disclosure has a basis weight of 52 g / m ２ Dry coating amount 5g / m on high-quality paper ２ The moisture permeability (g / (m) of the resulting coated paper was measured according to JIS Z 0208 (1976). ２The moisture permeability (g / (m 24h)) is preferably 200 or less, more preferably 150 or less, even more preferably 100 or less, and even more preferably 80, 70, or 60 or less. ２ The lower the water vapor barrier property, the higher the water vapor barrier property. ２ Dry coating amount 5g / m on high-quality paper ２ The water absorbency (g / m) of the resulting coated paper was measured by the Cobb method (contact time between the coated paper and water was 5 minutes). ２ ) is preferably 5 or less, more preferably 4, 3, or 2 or less, and even more preferably 1 or less. ２ The lower the water resistance, the higher the water resistance. ２ Dry coating amount 5g / 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 When 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 during adhesion at which the paper does not tear and interfacial peeling occurs is preferably 70°C or higher, more preferably 70 to 95°C, even more preferably 70 to 90°C, even more preferably 70 to 85°C, and even more preferably 70 to 80°C. The higher the temperature, the better the blocking resistance. Furthermore, the aqueous dispersion composition of the present disclosure has a basis weight of 52 g / m ２ Dry coating amount 5.0 g / m on high-quality paper ２ When the coated paper was coated so as to have a thickness of 100 μm, the coated paper and the wood-free paper were overlapped and a sealing pressure of 2 kg / cm was applied. ２The test pieces are subjected to a T-peel test (tensile speed: 300 mm / min) in accordance with JIS Z 0238 (1998), and the minimum temperature during the adhesion at which the paper breaks and the substrate is destroyed is preferably 70 to 110°C, and more preferably 80 to 100°C.

[0038] It should be noted that in this specification, the term "comprising" includes "consisting essentially of" and "consisting of." Furthermore, the present disclosure encompasses any and all combinations of the constituent elements described in this specification.

[0039] Furthermore, the various characteristics (properties, structures, functions, etc.) described in each embodiment of the present disclosure above may be combined in any way to identify 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.

[0040] 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.

[0041] Copolymer Production Examples [Production Example 1] A hopper was installed at the upstream tip of a twin-screw extruder (model: KZW15 (manufactured by Technovel Co., Ltd.), shaft diameter: 15 mm, L / D: 45), and 0.75 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 20.0 wt%, melt index: 300 g / 10 min) and 0.25 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 15.0 wt%, 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 content of structural units derived from acrylic acid of 18.75% by mass. This copolymer is hereinafter referred to as the copolymer of Production Example 1.

[0042] [Production Example 2] A hopper was installed at the upstream tip of a twin-screw extruder (model: KZW15 (manufactured by Technovel Co., Ltd.), shaft diameter: 15 mm, L / D: 45), and 0.51 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 20.0 wt%, 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 wt%, 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 content of structural units derived from acrylic acid of 17.5% by mass. This copolymer is hereinafter referred to as the copolymer of Production Example 2.

[0043] [Production Example 3] A hopper was installed at the upstream tip of a twin-screw extruder (model: KZW15 (manufactured by Technovel Co., Ltd.), shaft diameter: 15 mm, L / D: 45), and 0.25 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 20.0 wt%, melt index: 300 g / 10 min) and 0.75 kg / hr of ethylene / acrylic acid copolymer (content of structural units derived from acrylic acid: 15.0 wt%, 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 content of structural units derived from acrylic acid of 16.25% by mass. This copolymer is hereinafter referred to as the copolymer of Production Example 3.

[0044] Preparation of Aqueous Dispersion (Example 1) 75 g of the copolymer of Production Example 1, 5.33 g of 28% by mass ammonia water as a neutralizing agent, and 114.1 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Then, while stirring at 500 rpm, the temperature was raised from 25°C to 95°C, and the vessel was maintained at 95°C and stirred for 4 hours. The vessel was then allowed to cool to 90°C at room temperature, and 105.6 g of pure water was added. The vessel 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.

[0045] Example 2: 75 g of the copolymer of Production Example 2, 5.33 g of 28% by mass aqueous ammonia as a neutralizing agent, and 118.3 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. The temperature was then raised from 25°C to 95°C while stirring at 500 rpm, and the vessel was stirred for 4 hours while maintaining the temperature at 95°C. The vessel was then allowed to cool to 90°C at room temperature, and 101.1 g of pure water was added. The vessel 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.

[0046] Example 3: 75 g of the copolymer of Production Example 3, 5.65 g of 28% by mass aqueous ammonia as a neutralizing agent, and 120.9 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. The temperature was then raised from 25°C to 95°C while stirring at 500 rpm, and the vessel was stirred for 4 hours while maintaining the temperature at 95°C. The vessel was then allowed to cool to 90°C at room temperature, and 98.5 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.

[0047] (Example 4) 75 g of ethylene / acrylic acid copolymer (EAA; content of structural units derived from acrylic acid: 15% by mass, melt index: 60 g / 10 min), 5.21 g of 28% by mass aqueous ammonia as a neutralizing agent, and 111.6 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Then, while stirring at 500 revolutions per minute, the temperature was raised from 25°C to 95°C, and the vessel was maintained at 95°C and stirred for 4 hours. The mixture was then allowed to cool to 90°C at room temperature, and 108.2 g of pure water was added. Then, the mixture was 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.

[0048] (Comparative Example 1) 75 g of ethylene / acrylic acid copolymer (EAA; content of structural units derived from acrylic acid: 20% by mass, melt index: 300 g / 10 min), 5.69 g of 28% by mass ammonia water as a neutralizing agent, and 121.7 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Thereafter, while stirring at 500 revolutions per minute, the temperature was raised from 25 ° C to 95 ° C, and the inside of the vessel was maintained at 95 ° C and stirred for 4 hours. Next, it was cooled at room temperature to 90 ° C, and 97.6 g of pure water was added. Thereafter, it was cooled at room temperature to 50 ° C, and the contents were filtered through an 80-mesh polyethylene mesh to obtain an aqueous dispersion.

[0049] (Comparative Example 2) 75 g of the copolymer of Production Example 2, 9.95 g of 28% by mass ammonia water as a neutralizing agent, and 213.0 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Then, while stirring at 500 rpm, the temperature was raised from 25°C to 95°C, and the vessel was maintained at 95°C and stirred for 4 hours. The mixture was then allowed to cool to 90°C at room temperature, and 2.1 g of pure water was added. Then, the mixture was 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.

[0050] (Comparative Example 3) 75 g of the copolymer of Production Example 3, 7.70 g of 28% by mass ammonia water as a neutralizing agent, and 164.8 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Then, while stirring at 500 rpm, the temperature was raised from 25°C to 95°C, and the vessel was maintained at 95°C and stirred for 4 hours. The mixture was then allowed to cool to 90°C at room temperature, and 52.5 g of pure water was added. Then, the mixture was 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.

[0051] (Comparative Example 4) 75 g of the copolymer of Production Example 3, 9.76 g of 28% by mass ammonia water as a neutralizing agent, and 208.8 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Then, while stirring at 500 rpm, the temperature was raised from 25°C to 95°C, and the vessel was maintained at 95°C and stirred for 4 hours. The mixture was then allowed to cool to 90°C at room temperature, and 6.5 g of pure water was added. Then, the mixture was allowed to cool to 50°C at room temperature, and the contents were filtered through an 80-mesh polyethylene mesh to obtain an aqueous dispersion.

[0052] (Comparative Example 5) 75 g of ethylene / acrylic acid copolymer (EAA; content of structural units derived from acrylic acid: 15% by mass, melt index: 60 g / 10 min), 8.06 g of 28% by mass aqueous ammonia as a neutralizing agent, and 172.4 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Thereafter, while stirring at 500 revolutions per minute, the temperature was raised from 25 ° C to 95 ° C, and the inside of the vessel was maintained at 95 ° C and stirred for 4 hours. Next, it was cooled at room temperature to 90 ° C, and 44.5 g of pure water was added. Thereafter, it was cooled at room temperature to 50 ° C, and the contents were filtered through an 80-mesh polyethylene mesh to obtain an aqueous dispersion.

[0053] (Comparative Example 6) 75 g of ethylene / acrylic acid copolymer (EAA; content of structural units derived from acrylic acid: 15% by mass, melt index: 60 g / 10 min) was charged into a 1000 ml pressure vessel equipped with a stirrer, 9.48 g of 28% by mass ammonia water as a neutralizing agent, and 202.8 g of water were charged and sealed. Thereafter, while stirring at 500 revolutions per minute, the temperature was raised from 25 ° C to 95 ° C, and the inside of the vessel was maintained at 95 ° C and stirred for 4 hours. Next, it was cooled at room temperature to 90 ° C, and 12.7 g of pure water was added. Thereafter, it was cooled at room temperature to 50 ° C, and the contents were filtered through an 80-mesh polyethylene mesh to obtain an aqueous dispersion.

[0054] (Comparative Example 7) 75 g of the copolymer of Production Example 1, 11.7 g of a 30% by mass aqueous sodium hydroxide solution as a neutralizing agent, and 152.2 g of water were charged into a 1000 ml pressure vessel equipped with a stirrer and sealed. Then, while stirring at 500 rpm, the temperature was raised from 25°C to 95°C, and the vessel was maintained at 95°C and stirred for 4 hours. The mixture was then allowed to cool to 90°C at room temperature, and 61.1 g of pure water was added. Then, the mixture was 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.

[0055] (1) The aqueous dispersions prepared in Examples 1 to 4 and Comparative Examples 1 to 7 were applied to coated paper having a basis weight of 52 g / m ２ Dry coating amount 2.5g / m on high-quality paper ２ (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 aqueous dispersion was again applied to the coated surface of the coated paper obtained in (2) above using the same procedure as in (1). (4) The coated paper obtained in (3) above was dried under the same drying conditions as in (2) above, to a final dry coating amount of 5.0 g / m. ２ A coated paper having the following properties was obtained.

[0056] Measurement Method [Viscosity] The viscosity of the composition was measured using a Brookfield type rotational viscometer. Specifically, the viscosity was measured at 25°C with a spindle rotor speed of 60 revolutions per minute, by reading the viscosity value one minute after the rotor started rotating. The rotor can be appropriately selected depending on the viscosity. As a guideline, rotor No. 3 is used for viscosity less than 2000 mPa·s, rotor No. 4 is used for viscosity from 2000 mPa·s to less than 5000 mPa·s, rotor No. 5 is used for viscosity from 5000 mPa·s to less than 15000 mPa·s, rotor No. 6 is used for viscosity from 15000 mPa·s to less than 40000 mPa·s, and rotor No. 7 is used for viscosity of 40000 mPa·s or more.

[0057] [Blocking Resistance] Two sheets of the prepared 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 paper at a sealing pressure of 5 kg / cm. ２ Five test pieces were prepared for each coated paper by bonding the sheets at sealing temperatures of 60, 65, 70, 75, and 80°C for a sealing time of 2 hours. Each test piece was subjected to a T-peel test in accordance with JIS Z 0238 (1998). The highest temperature at which the paper showed interfacial peeling without tearing was determined as the blocking resistance temperature for the test pieces prepared at sealing temperatures of 60, 65, 70, 75, and 80°C. The higher the blocking resistance temperature, the higher the blocking resistance. The T-peel test was performed using an autograph (AGS-X model, manufactured by Shimadzu Corporation) at a tension speed of 300 mm / min.

[0058] [Water vapor barrier properties] The moisture permeability of the prepared coated paper was measured in accordance with JIS Z 0208 (1976). More specifically, a moisture absorbent (calcium chloride) was placed in an aluminum cup, and the prepared coated paper and an O-ring for keeping the permeation area constant were placed on top of each other, sealed with molten paraffin, and left to stand in a constant temperature and humidity chamber adjusted to the test conditions (temperature 40°C, humidity 90%). The increase in mass after 24 hours was measured, and the moisture permeability was calculated. A test jig manufactured by Yasuda Seiki Seisakusho Co., Ltd. was used. Moisture permeability (g / (m ２ The lower the 24h) value, the higher the water vapor barrier property.

[0059] [Water resistance] As an index of water resistance of coated paper, water absorbency was measured by the Cobb method in accordance with JIS P 8140 (1998) using a water absorbency tester (product name: Gurley Water Absorbency Tester, Yasuda Seiki Seisakusho). The contact time between the coated paper and water was 5 minutes. Water absorbency (g / m ２ ) is lower, the water resistance is higher.

[0060] [Heat sealability] The coated paper and the wood-free paper were overlapped so that the coated surface and the wood-free paper were in contact with each other, and the heat sealability was measured at a sealing pressure of 2 kg / cm using a heat gradient tester (HEAT GRADIENT TESTER) manufactured by Toyo Seiki Seisaku-sho, Ltd. ２ The test pieces were heat-sealed at a temperature between 70 and 110°C (specifically, 70, 80, 90, 100, or 110°C) for a sealing time of 3 seconds. The test pieces were subjected to a T-peel test in accordance with JIS Z 0238 (1998), and the lowest temperature during adhesion at which the paper broke and the substrate was destroyed was taken as the heat-sealing temperature. A temperature of 140°C or less is generally considered to be practical. The T-peel test was performed using an autograph (AGS-X model, manufactured by Shimadzu Corporation) with a tensile speed set at 300 mm / min.

[0061] The results are summarized in Table 1. In Table 1, AA represents acrylic acid. For example, the AA content represents the content (% by mass) of structural units derived from acrylic acid in the copolymer used.

[0062] The degree of AA neutralization is the degree of neutralization of the "structural units derived from acrylic acid" contained in the copolymer, and is the mole % of ammonia relative to the structural units derived from acrylic acid in the copolymer, and is a value calculated by the following formula: AA neutralization degree (unit: mole %) = [number of moles of ammonia] ÷ [number of moles of structural units derived from acrylic acid in the copolymer] × 100

[0063] The resin neutralization degree is a value calculated by the following formula: Resin neutralization degree (mass%) = [content (mass%) of structural units derived from acrylic acid relative to the copolymer] x [mol% of ammonia relative to the structural unit portion derived from acrylic acid in the polymer of the present disclosure] / 100

[0064] As shown in Table 1, the aqueous dispersion compositions prepared in Comparative Examples 2 to 6 had poor coating properties, making it impossible to evaluate their performance. Poor coating refers to a state in which the coated surface is not smooth, and includes the occurrence of irregularities such as streaks, blurring, orange peel, and pinholes. In particular, if the viscosity of the aqueous dispersion is high, it is thought that the leveling ability decreases, resulting in the aforementioned coating defects.

[0065]

[0066] According to the present disclosure, it is possible to provide an aqueous resin dispersion composition that has a relatively low viscosity and excellent handleability, and that can form a film that exhibits excellent barrier properties (water resistance and water vapor barrier properties). In a preferred embodiment, the film formed by the aqueous resin dispersion composition further exhibits blocking resistance and / or heat sealability that is sufficient for practical use. Such an aqueous resin dispersion composition can be said to be a material that meets the recent global demand for reducing the amount of plastic used, and is therefore an environmentally friendly material.

Claims

1. An aqueous dispersion composition comprising a copolymer containing structural units derived from a compound having an ethylene skeleton and structural units derived from acrylic acid, and ammonia, wherein the content of the structural units derived from acrylic acid relative to the copolymer is 5 to 19% by mass, and the resin neutralization degree calculated by the following formula is 5 to 10% by mass: Resin neutralization degree (mass %) = [content (mass %) of structural units derived from acrylic acid relative to the copolymer] x [mol % of ammonia relative to the structural units derived from acrylic acid in the copolymer] / 100.

2. The aqueous dispersion composition according to claim 1, which contains 10 to 40% by weight of said copolymer.

3. The aqueous dispersion composition according to claim 1 or 2, wherein the viscosity of the aqueous dispersion composition at 25°C is 1000 mPa·s or less.

4. The compound having an ethylene skeleton is represented by the formula (1): CHR １ = CHR ２ (1) (wherein, R １ and R ２ and are the same or different and represent a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms.

5. The aqueous dispersion composition of claim 1 or 2, wherein the copolymer is an ethylene / acrylic acid copolymer.

6. A laminate comprising a substrate and a coating on the substrate, wherein the coating is formed by applying the aqueous dispersion composition according to claim 1 or 2 onto the substrate.

7. Coated paper obtained by coating the aqueous dispersion composition according to claim 1 or 2 on paper.

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