Method for manufacturing an emulsion composition

Abstract

The present invention aims to provide a method for producing an emulsion composition which is excellent in storage stability and can be used as a single-component liquid from the viewpoint of operability, and which forms a coating film on a substrate such as paper or film, the coating film being excellent in water vapor barrier properties. A method for producing an emulsion composition is a method for producing an emulsion composition obtained by emulsion polymerization of a vinyl group-containing monomer mixture (D) in the presence of water (A), a surfactant (B), and paraffin (C) having a melting point in the range of 57°C to 71°C, characterized in that the temperature at which the emulsion polymerization is performed is higher than the melting point of the paraffin (C) present at the time of the emulsion polymerization, and that the following (1) or (2) is satisfied. (1) The surfactant (B) contains a low-molecular emulsifier (B1) having a sodium sulfonate group. (2) Glycerol methacrylate (E) is contained at the time of the emulsion polymerization.

Description

Technical Field

[0001] This invention relates to a method for manufacturing an emulsion composition that forms a coating film with excellent water vapor barrier properties and excellent storage stability on a substrate such as paper or film. Background Technology

[0002] Paper or film, particularly food packaging materials, are required to have water vapor barrier properties. This property is considered important to prevent the deterioration or discoloration of the contents, the proliferation of bacteria, or the growth of mold. Methods for imparting water vapor barrier properties to paper or film widely employ coating methods involving inorganic compounds such as mica, organic compounds such as waxes, polymers such as polyvinylidene chloride, and articles combining these compounds.

[0003] Among these, research has been conducted on water vapor barrier agents that use inexpensive and safe paraffin wax. For example, there are water vapor barrier emulsions containing styrene-acrylic emulsions obtained by emulsifying and polymerizing vinyl-containing monomers in the presence of paraffin wax and a polymer emulsifier. Although water vapor barrier properties can be obtained in this technology, paraffin wax will separate over time at high temperatures, and the storage stability of the water vapor barrier emulsion is problematic (Patent Document 1).

[0004] In addition, in order to solve the problem of exudation caused by wax, there is a water vapor barrier emulsion for paper coating obtained by emulsifying and polymerizing vinyl-containing monomers in the presence of wax emulsion and low molecular weight emulsifier, but the water vapor barrier property obtained is not sufficient (Patent Document 2).

[0005] As a method to solve the problem of storage stability, an invention has been made that exhibits water vapor barrier properties by blending wax emulsion with polymer emulsion. However, the storage stability of the blended water vapor barrier emulsion is poor, so it becomes a two-component liquid formulation that is blended just before use, which is complicated from the point of view of operability (Patent Document 3).

[0006] The development of water vapor barrier emulsions requires products that exhibit excellent water vapor barrier properties, can be used as single-component liquids from an operational point of view, and have excellent storage stability.

[0007] [Existing technical documents]

[0008] [Patent Literature]

[0009] Patent Document 1: Japanese Patent Application Publication No. 2000-119528

[0010] Patent Document 2: Japanese Patent Application Publication No. 2002-138394

[0011] Patent Document 3: Japanese Patent Application Publication No. 8-176992 Summary of the Invention

[0012] [The problem the invention aims to solve]

[0013] The object of the present invention is to provide a method for manufacturing an emulsion composition that forms a coating film with excellent water vapor barrier properties on a substrate such as paper or film, can be used as a single-component liquid from an operability point of view, and has excellent storage stability.

[0014] [Technical means to solve the problem]

[0015] The inventors have diligently studied the aforementioned problem and have discovered a method for manufacturing an emulsion composition that exhibits excellent water vapor barrier properties and storage stability.

[0016] That is, the present invention is

[0017] <1> A method for manufacturing an emulsion composition, characterized in that, is a method for manufacturing an emulsion composition by emulsifying and polymerizing a mixture (D) of vinyl-containing monomers in the presence of water (A), a surfactant (B), and paraffin (C) with a melting point in the range of 57°C to 71°C.

[0018] The emulsion polymerization is carried out at a temperature above the melting point of the paraffin (C) present during emulsion polymerization, and the following conditions (1) or (2) are met.

[0019] (1) The surfactant (B) contains a low-molecular-weight emulsifier (B1) with a sodium sulfonate group.

[0020] (2) Contains glycidyl methacrylate (E) during emulsification polymerization.

[0021] <2> A method for manufacturing an emulsion composition, characterized in that, is a method for manufacturing an emulsion composition by emulsifying and polymerizing a mixture (D) of vinyl-containing monomers in the presence of water (A), a surfactant (B), and paraffin (C) with a melting point in the range of 57°C to 71°C.

[0022] The emulsification polymerization is carried out at a temperature above the melting point of the paraffin (C) present during the emulsification polymerization, and the surfactant (B) contains a low-molecular-weight emulsifier (B1) with sodium sulfonate groups.

[0023] <3> A method for manufacturing an emulsion composition, characterized in that, is a method for manufacturing an emulsion composition by emulsifying and polymerizing a mixture (D) of vinyl-containing monomers in the presence of water (A), a surfactant (B), and paraffin (C) with a melting point in the range of 57°C to 71°C.

[0024] The emulsion polymerization is carried out at a temperature above the melting point of the paraffin (C) present during emulsion polymerization, and the emulsion polymerization contains glycidyl methacrylate (E).

[0025] <4> According to the above <1> to <3> The method for manufacturing the emulsion composition according to any one of the following is characterized in that the ratio of paraffin (C) to the polymer component contained in the emulsion composition is 2% to 10% by mass.

[0026] <5> According to the above <1> or <2> The method for manufacturing the emulsion composition is characterized in that the ratio of the low-molecular-weight emulsifier (B1) having a sodium sulfonate group to the vinyl-containing monomer mixture (D) is 0.5% to 5% by mass.

[0027] <6> According to the above <1> or <3> The method for manufacturing the emulsion composition is characterized in that the ratio of glycidyl methacrylate (E) to the vinyl-containing monomer mixture (D) is 0.5% to 10% by mass.

[0028] <7> According to the above <1> to <3> The method for manufacturing the emulsion composition according to any one of the following methods is characterized in that the surfactant (B) comprises a carboxyl-containing vinyl polymer (B2), and the ratio of the vinyl-containing monomer mixture (D) to the carboxyl-containing vinyl polymer (B2) is 60-80 / 20-40 (wt%).

[0029] <8> According to the above <1> to <7> The method for manufacturing the emulsion composition according to any one of the following is characterized in that, relative to the emulsion composition after standing at 40°C for 1 day, the viscosity change rate (%) of the emulsion composition after standing at 40°C for 28 days is -10% to 10% at 25°C.

[0030] [The effects of the invention]

[0031] By using the emulsion obtained in this invention, the water vapor barrier properties of paper or film substrates can be improved. The emulsion has excellent storage stability and can achieve the target performance as a single-component liquid, thus improving operability. Detailed Implementation

[0032] The method for manufacturing the emulsion composition of the present invention will be described in detail below.

[0033] The raw materials used in the method for manufacturing the emulsion composition of the present invention are at least water (A), surfactant (B), paraffin wax with a melting point in the range of 57°C to 71°C (C), and a mixture of vinyl monomers (D).

[0034] <Water(A)>

[0035] The water (A) used in this invention is used in the emulsification polymerization of a vinyl-containing monomer mixture (D), and is therefore preferably ion-exchanged water or soft water that does not hinder free radical polymerization.

[0036] <Surfactant (B)>

[0037] The surfactant (B) used in this invention can be appropriately selected according to the conditions described in (1) and (2) below, provided that it does not impair the effect of the invention. Ionic surfactants or their chemical types, molecular weights, and amounts can be used without particular restrictions. Furthermore, in this invention, both low-molecular-weight emulsifiers and high-molecular-weight emulsifiers refer to surfactants that can be used for emulsification polymerization. High-molecular-weight emulsifiers refer to emulsifiers that contain polymers synthesized through free radical polymerization and naturally occurring high-molecular-weight emulsifiers, while low-molecular-weight emulsifiers refer to emulsifiers other than those mentioned above.

[0038] <Paraffin (C) with a melting point in the range of 57℃ to 71℃>

[0039] The paraffin wax (C) used in this invention with a melting point in the range of 57°C to 71°C is not particularly limited as long as its melting point falls within the range specified in this invention. Furthermore, the term "paraffin wax" in this invention refers to a mixture of normal paraffins with 20 or more carbon atoms that are solid (waxy) at room temperature and insoluble in water. Examples of obtainable paraffin waxes with a melting point in the range of 57°C to 71°C include, for example, the "Paraffin Wax" series (135 (melting point 59°C), 140 (melting point 61°C), 145 (melting point 63°C), 150 (melting point 66°C), 155 (melting point 69°C)) manufactured by Nippon Seika Co., Ltd.

[0040] Regarding the paraffin (C) used in this invention with a melting point in the range of 57°C to 71°C, from the viewpoint of water vapor barrier properties, the ratio of paraffin (C) to the polymer component contained in the emulsion composition is preferably 2% to 10% by mass. Furthermore, the polymer component contained in the emulsion composition as used in this invention refers to the copolymer obtained by emulsifying and polymerizing the vinyl-containing monomer mixture (D) described later, and the carboxyl-containing vinyl polymer (B2) as a high-molecular-weight emulsifier.

[0041] <Mixtures of vinyl monomers (D)>

[0042] In this invention, the term "vinyl-containing monomer" refers to vinyl-containing monomers other than glycidyl methacrylate (E) described later. There are no particular limitations as long as the effects of this invention are not impaired; hydrophobic monomers with a solubility in water of less than 2% by mass at 20°C are preferred. Preferably, they are styrene-based or alkyl (meth)acrylates with 1 to 8 carbon atoms. Examples of styrene-based monomers include styrene and α-methylstyrene; examples of alkyl (meth)acrylates with 1 to 8 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. One or more of these vinyl-containing monomers may be used. More preferably, one or more of styrene, methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate may be used. Furthermore, as monomers other than hydrophobic monomers, anionic monomers such as acrylic acid and methacrylic acid, and nonionic monomers such as acrylamide and diacetone acrylamide may be used.

[0043] In the method for manufacturing the emulsion composition of the present invention, when a vinyl-containing monomer mixture (D) is emulsified and polymerized in the presence of water (A), a surfactant (B), and paraffin wax (C) with a melting point in the range of 57°C to 71°C, the temperature for emulsification polymerization needs to be above the melting point of the paraffin wax (C) present during emulsification polymerization. If polymerization is carried out under conditions below the melting point of paraffin wax, the paraffin wax is not in a liquid state and therefore difficult to incorporate into the polymer particles. Consequently, the obtained emulsion composition may separate over time.

[0044] In addition, in the method for manufacturing the emulsion composition of the present invention, from the viewpoint of preservation stability, it is also necessary to satisfy at least the following conditions (1) or (2).

[0045] (1) The surfactant (B) contains a low-molecular-weight emulsifier (B1) with a sodium sulfonate group.

[0046] (2) During emulsion polymerization, it contains glycidyl methacrylate (E).

[0047] If neither of the conditions (1) nor (2) is met, the resulting emulsion composition has poor storage stability and may thicken or separate over time at high temperatures. Hereinafter, the forms of the manufacturing method of the present invention corresponding to the conditions (1) and (2) will be described.

[0048] Morphology under the condition of (1)

[0049] Under the conditions described in (1), the surfactant (B) needs to contain a low-molecular-weight emulsifier (B1) having a sodium sulfonate group. Examples of low-molecular-weight emulsifiers (B1) having a sodium sulfonate group include sodium alkylbenzene sulfonate, sodium dialkyl sulfosuccinate, sodium alkyl allyl sulfosuccinate, and formaldehyde condensates of sodium naphthalene sulfonate. From the viewpoint of the water resistance of the coating film, it is preferable to use a low-molecular-weight emulsifier having a sodium sulfonate group that does not have a polyoxyethylene (polyoxyethylene, polyoxypropylene, etc.) alkyl (or alkenyl) ether structure, and more preferably, formaldehyde condensates of sodium alkylbenzene sulfonate, sodium dioctyl sulfosuccinate, and sodium naphthalene sulfonate with an alkyl group having 10 to 14 carbon atoms. The ratio of the low-molecular-weight emulsifier (B1) having a sodium sulfonate group to the vinyl-containing monomer mixture (D) is preferably 0.5% to 5% by mass.

[0050] Morphology under the condition of (2)

[0051] Under the conditions described in (2), glycidyl methacrylate (E) needs to be included during emulsification polymerization. The ratio of glycidyl methacrylate (E) to the vinyl-containing monomer mixture (D) is preferably 0.5% to 10% by mass.

[0052] From the viewpoint of the water resistance of the coating, conditions (1) and (2) are both preferably that the surfactant (B) includes a carboxyl-containing vinyl polymer (B2) as a polymeric emulsifier. In particular, if conditions (1) and (2) are met simultaneously, and the coating also contains a carboxyl-containing vinyl polymer (B2), the water vapor barrier properties of the coating formed by applying the emulsion composition obtained in this invention to the substrate are even better.

[0053] Regarding the carboxyl-containing vinyl polymer (B2) used as a polymeric emulsifier, examples include styrene-acrylic resins or acrylic resins, styrene-maleic resins, etc., which use carboxyl-containing vinyl monomers such as (meth)acrylic acid or maleic acid as copolymer components. In the emulsion manufacturing method of the present invention, the carboxyl-containing vinyl polymer (B2) is used by neutralizing it with an alkaline substance such as ammonia, organic amine, or sodium hydroxide and then dissolving it in water. From the viewpoint of emulsion polymerization stability, or the concentration and processability of the obtained emulsion, the weight average molecular weight is preferably in the range of 5000 to 30000, the acid value is preferably in the range of 100 to 300, and from the viewpoint of water resistance, neutralization with ammonia or organic amine is preferred.

[0054] When the surfactant (B) is a carboxyl-containing vinyl polymer (B2), regardless of the conditions described in (1) and (2), from the viewpoint of the water resistance of the coating film, it is preferred that the vinyl-containing monomer mixture (D) / carboxyl-containing vinyl polymer (B2) = 60 to 80 / 20 to 40 (mass%).

[0055] In the method for manufacturing the emulsion composition of the present invention, conventionally known emulsion polymerization methods can be applied. For example, water (A), surfactant (B), and paraffin (C) are charged into a reaction vessel including a stirrer and a nitrogen inlet pipe. As polymerization initiators, peroxides such as ammonium persulfate, potassium persulfate, and hydrogen peroxide, or any redox initiator comprising a combination of these peroxides and reducing agents such as ferrous sulfate, sodium bisulfite, ascorbic acid, and sodium ascorbate, are used. A vinyl-containing monomer mixture (D) is added dropwise over 60 to 180 minutes, and the reaction is continued for 60 to 480 minutes after the addition is completed, thereby obtaining the emulsion composition. If necessary, a known chain transfer agent such as an alkyl thiol may also be used in conjunction with the reaction of the vinyl-containing monomer mixture (D). However, the reaction temperature for emulsion polymerization must be above the melting point of paraffin (C).

[0056] Regarding the emulsion composition obtained by the manufacturing method of the emulsion composition of the present invention, from the viewpoint of storage stability, which is the subject of the present invention, as an indicator, it is preferable that the viscosity change rate (%) of the emulsion composition after standing at 40°C for 28 days at 25°C is -10% to 10% relative to the emulsion composition after standing at 40°C for 1 day.

[0057] The emulsion composition obtained in this invention can be effectively used as an aqueous coating agent. As needed, common organic solvents such as isopropyl alcohol (IPA) or butyl cellosolve, or fillers, waxes, film-forming aids, leveling agents, defoamers, and preservatives can be added.

[0058] When the emulsion composition obtained in this invention is used as a raw material for an aqueous coating agent, the substrate to be used can be not only absorbent substrates such as paper, but also non-absorbent substrates such as polyethylene terephthalate (PET), polyethylene, and polypropylene.

[0059] [Example]

[0060] The present invention will now be described in detail through examples and comparative examples. Furthermore, unless otherwise specified, % refers to mass%.

[0061] <Determination of the melting point of paraffin (C)>

[0062] For melting point, a differential scanning calorimeter was used to determine it under the following conditions.

[0063] Device: DISCOVERY DSC25 manufactured by TA Instruments Japan

[0064] Heating rate: 10℃ / minute

[0065] Measurement temperature range: 0℃~200℃

[0066] <Determination of molecular weight>

[0067] The weight-average molecular weight was determined using gel permeation chromatography (GPC) under the following conditions.

[0068] Device: HLC-8320GPC

[0069] The tubing is used by connecting the TSK-gel Super Multipore (SMULTIPORE) HZ-H and Super Multipore (SMULTIPORE) HZ-M manufactured by Tosoh.

[0070] Eluent: Tetrahydrofuran, 0.35 mL / min

[0071] <Determination of Acid Value>

[0072] For the acid value, a 0.1g sample was collected, dissolved in 50mL of tetrahydrofuran, and a few drops of phenolphthalein were added as an indicator. Then, 0.5N potassium hydroxide ethanol solution was added dropwise while stirring until the solution turned pale red.

[0073] Acid value =

[0074] The volume of 0.5N potassium hydroxide ethanol solution added (mL) × 0.5 × 56.11 / sample (g)

[0075] <Viscosity Measurement>

[0076] The viscosity was measured using type B viscosity at 25°C.

[0077] Synthesis of Carboxyl-Containing Vinyl Polymers (B2)

[0078] (Synthesis example 1)

[0079] 500 g of propylene glycol monomethyl ether acetate was placed in a separable flask equipped with a thermometer, cooling tube, and stirrer, and heated to 145 °C under nitrogen purging. Then, a mixture of 175 g of styrene, 200 g of α-methylstyrene, 125 g of acrylic acid, and 7.5 g of di-tert-butyl peroxide was added dropwise over 120 minutes. Sixty minutes after the addition was completed, atmospheric and vacuum distillation was performed to remove the propylene glycol monomethyl ether acetate, yielding a carboxyl-containing vinyl polymer (B2a) with a weight average molecular weight of 10,000 and an acid value of 195 mg KOH / g.

[0080] (Synthesis example 2)

[0081] 500 g of propylene glycol monomethyl ether acetate was placed in a separable flask equipped with a thermometer, cooling tube, and stirrer, and heated to 145 °C under nitrogen purging. Then, a mixture of 250 g of styrene, 125 g of 2-ethylhexyl acrylate, 125 g of acrylic acid, and 7.5 g of di-tert-butyl peroxide was added dropwise over 120 minutes. Sixty minutes after the addition was completed, atmospheric and vacuum distillation was performed to remove the propylene glycol monomethyl ether acetate, yielding a carboxyl-containing vinyl polymer (B2b) with a weight average molecular weight of 14500 and an acid value of 196 mg KOH / g.

[0082] <Preparation of Emulsion Compositions>

[0083] (Example 1)

[0084] 500g of deionized water, 121g of carboxyl-containing vinyl polymer (B2a), and 25.6g of 28% ammonia were added to a separable flask equipped with a thermometer, cooling tube, and stirrer. The mixture was heated at 90°C for 120 minutes to prepare an aqueous solution of the carboxyl-containing vinyl polymer. Subsequently, under nitrogen purging, 28.3g of Neogen S20 (sodium dodecylbenzenesulfonate, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., 20% active ingredient) as a low-molecular-weight emulsifier (B1) and 20.2g of paraffin wax (manufactured by Nippon Seika Co., Ltd., trade name ParaffinWAX 155) with a melting point of 69°C (5% by mass relative to the polymer content in the emulsion composition) were added, and the mixture was maintained at 80°C. A diluted solution prepared by dissolving 1.7 g of ammonium persulfate as a polymerization initiator in 17 g of deionized water was added. After 5 minutes, a mixture of 142 g of styrene and 142 g of 2-ethylhexyl acrylate, which is a vinyl monomer mixture (D), was added dropwise over a period of 120 minutes to carry out emulsification polymerization. 60 minutes after the end of the dropwise addition, a diluted solution prepared by dissolving 0.3 g of ammonium persulfate in 3 g of deionized water was added. 120 minutes after the end of the dropwise addition, the mixture was cooled and diluted with deionized water to a concentration of 41% to obtain the emulsion composition (1).

[0085] (Example 2)

[0086] Using 8.1g of Rikasurf P-10 (sodium dioctyl sulfosuccinate, manufactured by Shin Nippon Rikken Co., Ltd., 70% active ingredient) as a low molecular weight emulsifier (B1), the same procedure as in Example 1 was followed to obtain the emulsion composition (2).

[0087] (Example 3)

[0088] Using 14.3 g of Celluflow 110 (formaldehyde condensate of sodium naphthalene sulfonate, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd., 40% active ingredient) as a low molecular weight emulsifier (B1), the same procedure as in Example 1 was followed to obtain the emulsion composition (3).

[0089] (Example 4)

[0090] During the emulsification polymerization of the vinyl-containing monomer mixture (D), without using a low-molecular-weight emulsifier (B1), 5.7 g of glycidyl methacrylate (E) at 2% by mass relative to the vinyl-containing monomer mixture (D) was added, otherwise the process was carried out in the same manner as in Example 1 to obtain the emulsion composition (4).

[0091] (Example 5)

[0092] The following steps were performed as in Example 1: 123 g of carboxyl-containing vinyl polymer (B2a), 26.0 g of 28% ammonia, 28.7 g of Neogen S20, 8.4 g of paraffin wax with a melting point of 69°C (2% by mass relative to the polymer content in the emulsion composition), 143 g of styrene, 143 g of 2-ethylhexyl acrylate, and 5.7 g of glycidyl methacrylate (E) (2% by mass relative to the vinyl-containing monomer mixture (D)) were added to obtain the emulsion composition (5).

[0093] (Example 6)

[0094] The following steps were performed: 120 g of carboxyl-containing vinyl polymer (B2a), 25.3 g of 28% ammonia, 27.9 g of Neogen S20, 20.3 g of paraffin wax with a melting point of 69°C, 140 g of styrene, 140 g of 2-ethylhexyl acrylate, and 5.6 g of glycidyl methacrylate (E) at 5% by mass relative to the vinyl-containing monomer mixture (D). Otherwise, the procedure was the same as in Example 1 to obtain the emulsion composition (6).

[0095] (Example 7)

[0096] 114 g of carboxyl-containing vinyl polymer (B2a), 24.0 g of 28% ammonia, 26.6 g of Neogen S20, 38.8 g of paraffin wax with a melting point of 69°C (10% by mass relative to the polymer content in the emulsion composition), 133 g of styrene, 133 g of 2-ethylhexyl acrylate, and 5.3 g of glycidyl methacrylate (E) (10% by mass relative to the vinyl-containing monomer mixture (D)) were added. Emulsification polymerization was started using a diluent prepared by dissolving 1.6 g of ammonium persulfate in 16 g of deionized water. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the emulsion composition (7).

[0097] (Example 8)

[0098] Using 20.3g of paraffin wax (manufactured by Nippon Seika Co., Ltd., trade name ParaffinWAX 135) with a melting point of 59°C as paraffin wax (C), the same procedure as in Example 6 was followed to obtain emulsion composition (8).

[0099] (Example 9)

[0100] The carboxyl-containing vinyl polymer (B2a) was set at 122g, 28% ammonia water at 25.7g, Neogen S20 at 7.1g (0.5% by mass relative to the vinyl-containing monomer mixture (D)), paraffin wax with a melting point of 69°C at 20.4g, styrene at 143g, and 2-ethylhexyl acrylate at 143g. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the emulsion composition (9).

[0101] (Example 10)

[0102] The following steps were performed as in Example 1: 450 g of ion-exchanged water, 119 g of carboxyl-containing vinyl polymer (B2a), 25.1 g of 28% ammonia, 69.4 g of Neogen S20 (5% by mass relative to the vinyl-containing monomer mixture (D), 19.8 g of paraffin wax with a melting point of 69°C, 139 g of styrene, and 139 g of 2-ethylhexyl acrylate. The emulsion composition (10) was obtained.

[0103] (Example 11)

[0104] In the emulsification polymerization of the vinyl-containing monomer mixture (D), without using a low-molecular-weight emulsifier (B1), 122 g of carboxyl-containing vinyl polymer (B2a), 25.7 g of 28% ammonia, 20.5 g of paraffin wax with a melting point of 69°C, 143 g of styrene, 143 g of 2-ethylhexyl acrylate, and 1.4 g of glycidyl methacrylate (E) at 0.5% by mass relative to the vinyl-containing monomer mixture (D) were added. Otherwise, the process was carried out in the same manner as in Example 1 to obtain an emulsion composition (11).

[0105] (Example 12)

[0106] In the emulsification polymerization of the vinyl-containing monomer mixture (D), without using a low-molecular-weight emulsifier (B1), 115 g of carboxyl-containing vinyl polymer (B2a), 24.3 g of 28% ammonia, 21.0 g of paraffin wax with a melting point of 69°C, 134 g of styrene, 134 g of 2-ethylhexyl acrylate, and 26.8 g of glycidyl methacrylate (E) at 10% by mass relative to the vinyl-containing monomer mixture (D) were added. Emulsification polymerization was started using a diluent prepared by dissolving 1.6 g of ammonium persulfate in 16 g of deionized water. Otherwise, the process was carried out in the same manner as in Example 1 to obtain an emulsion composition (12).

[0107] (Example 13)

[0108] Using a carboxyl-containing vinyl polymer (B2b) as the carboxyl-containing vinyl polymer (B2), the process was otherwise carried out in the same manner as in Example 6 to obtain an emulsion composition (13).

[0109] (Example 14)

[0110] Using 95g of methyl methacrylate, 92g of butyl acrylate, and 92g of 2-ethylhexyl acrylate as a vinyl-containing monomer mixture (D), the process was otherwise carried out in the same manner as in Example 6 to obtain an emulsion composition (14).

[0111] (Example 15)

[0112] In a separable flask equipped with a thermometer, cooling tube, and stirrer, under nitrogen purging, 440 g of deionized water, 39.4 g of Neogen S20 as a low-molecular-weight emulsifier (B1), and 20.1 g of paraffin wax (C) with a melting point of 69°C were added, and the temperature was maintained at 80°C. A dilution solution prepared by dissolving 2.4 g of ammonium persulfate in 24 g of deionized water was added. After 5 minutes, a mixture of 173 g of methyl methacrylate, 150 g of butyl acrylate, 55 g of 2-ethylhexyl acrylate, 16 g of acrylic acid, and 7.9 g of glycidyl methacrylate (E) at 2% by mass relative to the vinyl monomer mixture (D) was added dropwise over a period of 120 minutes. 60 minutes after the end of the dropwise addition, a dilution solution prepared by dissolving 0.4 g of ammonium persulfate in 4 g of deionized water was added. 120 minutes after the addition was completed, 13.2 g of 28% ammonia solution was added, and then the mixture was cooled and diluted to a concentration of 39% with deionized water to obtain the emulsion composition (15).

[0113] (Example 16)

[0114] Acrylic acid was set to methacrylic acid, and 28% ammonia solution was set to 11.1 g. Otherwise, the process was carried out in the same manner as in Example 15 to obtain emulsion composition (16).

[0115] (Example 17)

[0116] The emulsion composition (17) was prepared by adding 124g of carboxyl-containing vinyl polymer (B2a), 26.2g of 28% ammonia, 29.0g of Neogen S20, 4.2g of paraffin wax with a melting point of 69°C (1% by mass relative to the polymer content in the emulsion composition), 145g of styrene, 145g of 2-ethylhexyl acrylate, and 5.8g of glycidyl methacrylate (E) (2% by mass relative to the vinyl-containing monomer mixture (D)). Otherwise, the procedure was the same as in Example 1.

[0117] (Example 18)

[0118] 112 g of carboxyl-containing vinyl polymer (B2a), 23.6 g of 28% ammonia, 26.2 g of Neogen S20, 45.8 g of paraffin wax with a melting point of 69°C (12% by mass relative to the polymer content in the emulsion composition), 131 g of styrene, 131 g of 2-ethylhexyl acrylate, and 5.2 g of glycidyl methacrylate (E) (2% by mass relative to the vinyl-containing monomer mixture (D)) were added. Emulsion polymerization was started using a diluent prepared by dissolving 1.6 g of ammonium persulfate in 16 g of deionized water. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the emulsion composition (18).

[0119] (Example 19)

[0120] The carboxyl-containing vinyl polymer (B2a) was set at 123g, 28% ammonia water at 26.0g, Neogen S20 at 1.4g (0.1% by mass relative to the vinyl-containing monomer mixture (D)), paraffin wax with a melting point of 69°C at 20.5g, styrene at 143g, and 2-ethylhexyl acrylate at 143g. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the emulsion composition (19).

[0121] (Example 20)

[0122] The emulsion polymerization was carried out using 390 g of deionized water, 115 g of carboxyl-containing vinyl polymer (B2a), 24.3 g of 28% ammonia, 134.4 g of Neogen S20 (10% by mass relative to the vinyl-containing monomer mixture (D)), 19.2 g of paraffin wax with a melting point of 69°C, 134 g of styrene, and 134 g of 2-ethylhexyl acrylate. The emulsion polymerization was started using a diluted solution prepared by dissolving 1.6 g of ammonium persulfate in 16 g of deionized water. Otherwise, the process was carried out in the same manner as in Example 1 to obtain an emulsion composition (20).

[0123] (Example 21)

[0124] During the emulsification polymerization of the vinyl-containing monomer mixture (D), without using a low-molecular-weight emulsifier (B1), 123 g of the carboxyl-containing vinyl polymer (B2a), 26.0 g of 28% ammonia, 20.5 g of paraffin wax with a melting point of 69°C, 143 g of styrene, 143 g of 2-ethylhexyl acrylate, and 0.3 g of glycidyl methacrylate (E) at 0.1% by mass relative to the vinyl-containing monomer mixture (D) were added. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the emulsion composition (21).

[0125] (Example 22)

[0126] In the emulsification polymerization of the vinyl-containing monomer mixture (D), without using a low-molecular-weight emulsifier (B1), 123g of carboxyl-containing vinyl polymer (B2a), 23.4g of 28% ammonia, 21.3g of paraffin wax with a melting point of 69°C, 129g of styrene, 129g of 2-ethylhexyl acrylate, and 38.8g of glycidyl methacrylate (E) at 15% by mass relative to the vinyl-containing monomer mixture (D) were added. Emulsification polymerization was started using a diluent prepared by dissolving 1.6g of ammonium persulfate in 16g of deionized water. Otherwise, the process was carried out in the same manner as in Example 1 to obtain an emulsion composition (22).

[0127] (Comparative Example 1)

[0128] Using 20.3g of paraffin wax (manufactured by Nippon Seika Co., Ltd., trade name ParaffinWAX 115) with a melting point of 48°C as paraffin wax (C), the same procedure as in Example 6 was followed to obtain an emulsion composition (23).

[0129] (Comparative Example 2)

[0130] Using 20.3g of paraffin wax (manufactured by Nippon Seiwa Co., Ltd., trade name HNP-51) with a melting point of 77°C as paraffin wax (C), the process was carried out in the same manner as in Example 6 to obtain emulsion composition (24).

[0131] (Comparative Example 3)

[0132] Emulsification polymerization was carried out at 65°C (less than the melting point of paraffin (C)), otherwise it was carried out in the same manner as in Example 6, to obtain an emulsion composition (25).

[0133] (Comparative Example 4)

[0134] Without using a low-molecular-weight emulsifier (B1), the following steps were performed as in Example 1: 123g of a carboxyl-containing vinyl polymer (B2a), 26.0g of 28% ammonia, 20.5g of paraffin wax with a melting point of 69°C, 143g of styrene, and 143g of 2-ethylhexyl acrylate, to obtain an emulsion composition (26).

[0135] (Comparative Example 5)

[0136] The carboxyl-containing vinyl polymer (B2a) was set at 120g, 28% ammonia water at 25.3g, Pluronic (registered trademark) L-31 (ethylene oxide propylene oxide (EOPO) block copolymer, manufactured by ADEKA Inc., 100% active ingredient) (2% by mass relative to the vinyl-containing monomer mixture (D)) was set as a low-molecular-weight emulsifier without sodium sulfonate groups instead of low-molecular-weight emulsifier (B1), paraffin wax with a melting point of 69°C at 20.3g, styrene at 140g, and 2-ethylhexyl acrylate at 140g. Otherwise, the process was carried out in the same manner as in Example 1 to obtain the emulsion composition (27).

[0137] (Comparative Example 6)

[0138] In a separable flask equipped with a thermometer, cooling tube, and stirrer, 500 g of deionized water, 120 g of carboxyl-containing vinyl polymer (B2a), and 25.3 g of 28% ammonia were added, and the mixture was heated at 90°C for 120 minutes. Then, under nitrogen purging, 27.9 g of Neogen S20 as a low-molecular-weight emulsifier (B1) was added, and the temperature was maintained at 80°C. A dilution solution prepared by dissolving 1.7 g of ammonium persulfate in 17 g of deionized water was added. After 5 minutes, a mixture of 140 g of styrene, 140 g of 2-ethylhexyl acrylate, and 5.6 g of glycidyl methacrylate (E) at 2% by mass relative to the vinyl-containing monomer mixture (D) was added dropwise over 120 minutes. Sixty minutes after the end of the dropwise addition, a dilution solution prepared by dissolving 0.3 g of ammonium persulfate in 3 g of deionized water was added. 120 minutes after the addition was completed, the mixture was cooled to 30°C, and then 51g of EMUSTER 1155 (manufactured by Nippon Seika Co., Ltd., with an active ingredient content of 40%), a paraffin emulsion with a melting point of 69°C (C), was added. The mixture was then diluted to a concentration of 41% with deionized water to obtain an emulsion composition (28).

[0139] The composition and properties of each emulsion composition (1) to (28) obtained in Examples 1 to 22 and Comparative Examples 1 to 6 are shown in Table 1.

[0140] [Table 1]

[0141]

[0142] Abbreviations in the table:

[0143] <Surfactant (B)>

[0144] B1a: Sodium dodecylbenzenesulfonate

[0145] B1b: Sodium dioctylsulfosuccinate

[0146] B1c: Formaldehyde condensate of sodium naphthalenesulfonate

[0147] B2a: A copolymer of styrene / α-methylstyrene / acrylic acid = 35 / 40 / 25 (wt%)

[0148] B2b: A copolymer of styrene / 2-ethylhexyl acrylate / acrylic acid = 50 / 25 / 25 (wt%)

[0149] b1d: Ethylene oxide-propylene oxide block copolymer

[0150] <Monomer composition of vinyl-containing monomer mixture (D)>

[0151] Da: Styrene / 2-ethylhexyl acrylate = 50 / 50 (wt%)

[0152] Db: Methyl methacrylate / butyl acrylate / 2-ethylhexyl acrylate = 34 / 33 / 33 (wt%)

[0153] Dc: Methyl methacrylate / butyl acrylate / 2-ethylhexyl acrylate / acrylic acid = 44 / 38 / 14 / 4 (wt%)

[0154] Dd: Methyl methacrylate / butyl acrylate / 2-ethylhexyl acrylate / methacrylic acid = 44 / 38 / 14 / 4 (mass%)

[0155] The storage stability and water vapor barrier properties of each emulsion composition (1) to (28) obtained in Examples 1 to 22 and Comparative Examples 1 to 6 are shown in Table 2.

[0156] <Maintaining Stability>

[0157] The evaluation was conducted by checking for any separation in the viscosity and appearance after the emulsion composition was left to stand at 40°C for 1 day and after standing at 40°C for 28 days at 25°C. Furthermore, in this invention, the absence of separation is a necessary level. Therefore, for the emulsion compositions (25) to (28) of Comparative Examples 3 to 6, whose storage stability was such that separation occurred after standing at 40°C for 1 day, moisture permeability was not evaluated. The viscosity change rate (%) after standing at 40°C for 28 days relative to after standing at 40°C for 1 day was calculated using the following formula.

[0158] Viscosity change rate (%) = (Viscosity after standing at 40℃ for 28 days - Viscosity after standing at 40℃ for 1 day) / (Viscosity after standing at 40℃ for 1 day) × 100

[0159] The viscosity change rate (%) is preferably within -10% to 10%.

[0160] <Application Evaluation>

[0161] Using wire rod #5, on neutral wood pulp paper (basic weight 65g / m²) 2 ), PET (polyester) film single-sided coating emulsion composition (1) to emulsion composition (24). The coating amount of the coating liquid is 9 g / m 2 After application, the water permeability was measured as an indicator of water vapor barrier properties. The results are shown in Table 2.

[0162] <Moisture permeability>

[0163] Evaluation was conducted according to Japanese Industrial Standards (JIS) Z0208 (cup method, 40°C, 90% relative humidity, 24 hours). A lower water permeability value indicates better water vapor barrier properties. Furthermore, in this invention, the practical level of water permeability is 100 or less for neutral wood pulp paper and 15 or less for PET film.

[0164] Moisture permeability can also be improved by increasing the coating amount, but under the evaluation conditions of the present invention, it is preferable to have both storage stability and water vapor barrier properties in a balanced manner, more preferably a viscosity change rate (%) of -7% to 7% or less, and moisture permeability of less than 50 in neutral wood paper and less than 10 in PET film.

[0165] [Table 2]

[0166]

[0167] Compared with comparative examples such as Comparative Example 1 and Comparative Example 2, where the melting point of paraffin (C) is outside the range, Comparative Example 3, where the temperature for emulsification polymerization is outside the range, Comparative Example 4 and Comparative Example 5, where conditions (1) and (2) are not met, and Comparative Example 6, where emulsification polymerization is not carried out in the presence of paraffin (C), which do not meet all the constituent requirements of the present invention, it can be seen that the emulsions of Examples 1 to 22, which meet all the constituent requirements of the present invention, do not separate and are stable, and have excellent water vapor barrier properties.

[0168] According to Examples 5, 7, 17, and 18, if the ratio of paraffin (C) to the polymer component contained in the emulsion composition is in the range of 2% to 10% by mass, the water vapor barrier properties are better and the viscosity change rate is smaller.

[0169] According to Examples 9, 10, 19, and 20, if the ratio of the low-molecular-weight emulsifier (B1) with sodium sulfonate group to the vinyl-containing monomer mixture (D) is in the range of 0.5% to 5% by mass, the water vapor barrier properties are better and the viscosity change rate is smaller.

[0170] According to Examples 11, 12 and 21, 22, if the amount of glycidyl methacrylate (E) relative to the vinyl-containing monomer mixture (D) is in the range of 0.5% to 5% by mass, the viscosity change rate is small, which is more preferable.

Claims

1. A method for manufacturing an emulsion composition with excellent water vapor barrier properties, comprising emulsifying and polymerizing a mixture (D) of vinyl monomers other than glycidyl methacrylate (E) in the presence of water (A), a surfactant (B), and paraffin (C) with a melting point in the range of 57°C to 71°C, characterized in that... Surfactant (B) comprises a carboxyl-containing vinyl polymer (B2). The carboxyl-containing vinyl polymer (B2) is selected from at least one of styrene-acrylic resins and acrylic resins that use carboxyl-containing vinyl monomers as copolymer components. The vinyl-containing monomer mixture (D) is a styrene-based or an alkyl (meth)acrylate with 1 to 8 carbon atoms. The emulsion polymerization is carried out at a temperature above the melting point of the paraffin (C) present during the emulsion polymerization, and the following conditions (1) or (2) are met. (1) The surfactant (B) contains a low-molecular-weight emulsifier (B1) with a sodium sulfonate group. (2) During emulsification polymerization, glycidyl methacrylate (E) is further included.

2. A method for manufacturing an emulsion composition with excellent water vapor barrier properties, comprising emulsifying and polymerizing a mixture (D) of vinyl monomers other than glycidyl methacrylate (E) in the presence of water (A), a surfactant (B), and paraffin (C) with a melting point in the range of 57°C to 71°C, characterized in that... The temperature at which emulsification polymerization takes place is above the melting point of the paraffin (C) present during emulsification polymerization, and the surfactant (B) comprises a low-molecular-weight emulsifier (B1) having sodium sulfonate groups and a carboxyl-containing vinyl polymer (B2). The carboxyl-containing vinyl polymer (B2) is selected from at least one of styrene-acrylic resins and acrylic resins that use carboxyl-containing vinyl monomers as copolymer components. The vinyl-containing monomer mixture (D) is a styrene-based or an alkyl (meth)acrylate with 1 to 8 carbon atoms.

3. A method for manufacturing an emulsion composition with excellent water vapor barrier properties, comprising emulsifying and polymerizing a mixture (D) of vinyl monomers (excluding glycidyl methacrylate (E)) in the presence of water (A), a surfactant (B), and paraffin (C) with a melting point in the range of 57°C to 71°C, characterized in that... Surfactant (B) comprises a carboxyl-containing vinyl polymer (B2). The carboxyl-containing vinyl polymer (B2) is selected from at least one of styrene-acrylic resins and acrylic resins that use carboxyl-containing vinyl monomers as copolymer components. The vinyl-containing monomer mixture (D) is a styrene-based or an alkyl (meth)acrylate with 1 to 8 carbon atoms, and The emulsion polymerization is carried out at a temperature above the melting point of the paraffin (C) present during emulsion polymerization, and further contains glycidyl methacrylate (E) during emulsion polymerization.

4. The method for manufacturing the emulsion composition according to any one of claims 1 to 3, characterized in that, The ratio of paraffin (C) to the polymer component contained in the emulsion composition is 2% to 10% by mass.

5. The method for manufacturing the emulsion composition according to claim 1 or 2, characterized in that, The ratio of the low-molecular-weight emulsifier (B1) with sodium sulfonate group to the vinyl-containing monomer mixture (D) other than glycidyl methacrylate (E) is 0.5% to 5% by mass.

6. The method for manufacturing the emulsion composition according to claim 1 or 3, characterized in that, The ratio of glycidyl methacrylate (E) to the vinyl-containing monomer mixture (D) other than glycidyl methacrylate (E) is 0.5% to 10% by mass.

7. The method for manufacturing the emulsion composition according to any one of claims 1 to 3, characterized in that, Mixture of vinyl monomers other than glycidyl methacrylate (E) (D) / Carboxyl-containing vinyl polymer (B2) = 60-80 / 20-40 by mass.

8. The method for manufacturing the emulsion composition according to any one of claims 1 to 3, characterized in that, Compared to the emulsion composition after standing at 40°C for 1 day, the viscosity change rate (%) of the emulsion composition after standing at 40°C for 28 days at 25°C is -10% to 10%.

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