Method for producing purified polymer fine particles and method for producing resin composition

Abstract

The present invention addresses the problem of providing a novel method capable of efficiently purifying polymer fine particles from a latex at a reduced environmental burden. Provided is a method for producing purified polymer fine particles (A) that includes an organic solvent mixing step for mixing a latex containing polymer fine particles (A) and an emulsifier having a polyethylene group with an organic solvent (B) and a mixed state maintenance step for stirring and / or allowing to stand the mixture obtained in the organic solvent mixing step.

Description

[Technical Field]

[0001] This invention relates to a method for producing purified polymer fine particles and a method for producing a resin composition. [Background technology]

[0002] Thermosetting resins are used in a wide range of fields due to their excellent properties, such as high heat resistance and mechanical strength. Among thermosetting resins, epoxy resins are widely used in applications such as electronic circuit encapsulants, paints, adhesives, and matrix resins for fiber-reinforced materials. While epoxy resins excel in heat resistance, chemical resistance, and insulation, they suffer from insufficient impact resistance, a characteristic of thermosetting resins. To improve the impact resistance of thermosetting resins, a widely used method involves adding elastomers to the resin.

[0003] Examples of the elastomer include polymer microparticles (for example, crosslinked polymer microparticles). Polymer microparticles generally have a particle size smaller than 1 μm. Here, a powder or granular material of polymer microparticles prepared by collecting several primary polymer microparticles having a particle size smaller than 1 μm is referred to as a secondary particle. While it is possible to disperse secondary polymer microparticles in a thermosetting resin, dispersing primary polymer microparticles in a thermosetting resin is extremely difficult at an industrial level.

[0004] Patent Document 1 discloses a method for producing a resin mixture in which primary polymer microparticles are dispersed in a thermosetting resin, which involves mixing purified polymer microparticles obtained by removing water and impurities (such as emulsifiers) from latex containing polymer microparticles with a thermosetting resin. According to the disclosure in Patent Document 1, polymer microparticle aggregates are obtained by mixing latex containing polymer microparticles with an organic solvent, and then contacting the resulting mixture with water. By separating the obtained aggregates from the aqueous phase containing impurities, purified polymer microparticles with reduced impurities are obtained. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] International Publication No. WO2005 / 028546 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the conventional technologies described above were insufficient from an environmental impact standpoint, and there was room for further improvement.

[0007] One embodiment of the present invention has been made in view of the above-mentioned problems, and its object is to provide a novel method that can efficiently purify polymer fine particles from latex and has a reduced environmental impact. [Means for solving the problem]

[0008] The inventors of this invention have diligently studied and conducted research to solve the aforementioned problems, and as a result, have completed this invention.

[0009] In other words, a method for producing purified polymer fine particles (A) according to one embodiment of the present invention includes an organic solvent mixing step of mixing polymer fine particles (A) and latex containing an emulsifier with an organic solvent (B), and a mixing state maintenance step of either letting the mixture obtained in the organic solvent mixing step stand and / or stirring, wherein the emulsifier contains a lipophilic portion and a hydrophilic portion, and the hydrophilic portion has a polyoxyethylene group.

[0010] A method for producing purified polymer fine particles (A) according to another embodiment of the present invention includes an organic solvent mixing step of mixing polymer fine particles (A) and latex containing an emulsifier with an organic solvent (B), a loose aggregation step of contacting the mixture obtained in the organic solvent mixing step with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in an aqueous phase, and a separation step of separating the aggregates from the aqueous phase, and further includes a step of repeating one or more cycles selected from (i) and (ii) below after the separation step.

[0011] (i) A first step of adding the organic solvent (B) to the aggregate obtained in the separation step, a second step of bringing the mixture obtained in the first step into contact with water to form an aggregate of polymer particles (A) containing the organic solvent (B) in the aqueous phase, and a third step of separating the aggregate obtained in the second step from the aqueous phase, which consists of a first cycle, and (ii) A first step of adding water to the aggregate obtained in the separation step, a second step of bringing the mixture obtained in the first step into contact with the organic solvent (B) to form an aggregate of polymer particles (A) containing the organic solvent (B) in the aqueous phase, and a third step of separating the aggregate obtained in the second step from the aqueous phase, which consists of a second cycle. [Advantages of the Invention]

[0012] According to one aspect of the present invention, it is possible to provide a novel method with reduced environmental impact that can efficiently purify polymer particles from latex. [Brief Description of the Drawings]

[0013] [Figure 1] It is a graph showing the change over time in the viscosity of a mixture of a latex containing a phosphorus-based emulsifier having a polyoxyethylene group or a sulfur-based emulsifier not having a polyoxyethylene group and an organic solvent. [Embodiments for Carrying Out the Invention]

[0014] One embodiment of the present invention is described below, but the present invention is not limited thereto. The present invention is not limited to the configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by appropriately combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Moreover, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic and patent documents mentioned herein are incorporated herein by reference. Furthermore, unless otherwise specified herein, "A to B" representing a numerical range means "A or greater (including A and greater than A) and B or less (including B and less than B)."

[0015] [Embodiment 1] [1-1. Technical Concept of the Invention] In recent years, from the perspective of environmental protection, there have been attempts to replace materials with a greater environmental impact with materials with a smaller environmental impact. Linear alkylbenzene sulfonates (LAS) are widely used as emulsifiers in the production of polymer microparticles due to their polymerization stability, cost, availability, and neutral pH. However, emulsifiers containing linear alkylbenzenes have low degradability and a high environmental impact. Therefore, from the perspective of environmental protection, it is preferable to use emulsifiers containing polyoxyethylene groups with ether bonds that are easily degraded by organisms. Accordingly, we attempted to purify polymer microparticles (A) from latex containing polymer microparticles (A) prepared using an emulsifier containing polyoxyethylene groups instead of an emulsifier containing linear alkylbenzenes, according to the method disclosed in Patent Document 1. As a result, a problem arose in that the aqueous phase (the discharged liquid after separating the aggregates of polymer microparticles (A)) obtained by contacting a mixture of latex and an organic solvent (B) with water became cloudy. Upon investigating the cause of the cloudiness of the aqueous phase, it was found that unaggregated polymer microparticles (A) were mixed into the aqueous phase.

[0016] Therefore, as a result of diligent research by the inventors, the following new findings were discovered, leading to the completion of the present invention: By providing a step of standing and / or stirring for a certain period of time after the organic solvent mixing step of mixing latex and organic solvent (B), and before the slow aggregation step of contacting the mixture with water to generate aggregates, the turbidity of the discharged liquid is eliminated.

[0017] Furthermore, the inventors investigated the reason why standing and / or stirring for a certain period of time resolved the turbidity of the discharged liquid, and independently discovered the following findings.

[0018] (i) In latex, polymer particles (A) and emulsifiers exist bound together in a solvent (latex solvent). When the latex is mixed with an organic solvent (B), the emulsifier migrates to the interface between the latex solvent and the organic solvent (B), and the bond between the polymer particles (A) and the emulsifier dissociates. As a result, the polymer particles (A) move from the latex solvent into the organic solvent (B). When such a mixture is brought into contact with water, the polymer particles (A) form aggregates. The formed aggregates can be separated from the aqueous phase by any separation means.

[0019] (ii) However, when using an emulsifier having a polyoxyethylene group, the transfer of polymer microparticles (A) into the organic solvent (B) takes longer compared to when using an emulsifier having a linear alkylbenzene. The reason for this is not clear, but it is presumed that the emulsifier having a polyoxyethylene group has a higher affinity for polymer microparticles (A) compared to the emulsifier having a linear alkylbenzene, and therefore the dissociation of the bond between polymer microparticles (A) and the emulsifier takes longer. Note that the embodiment of the present invention is not limited to this presumption. If the mixture of latex and organic solvent (B) is brought into contact with water before the transfer of polymer microparticles (A) into the organic solvent (B) is complete, some polymer microparticles (A) cannot form aggregates and cannot be separated from the aqueous phase. As a result, the aqueous phase (discharge liquid) becomes cloudy.

[0020] (iii) The step of allowing the mixture of latex and organic solvent (B) to stand and / or stirring (the step of maintaining the mixed state in the first manufacturing method) promotes the dissociation of the bonds between the polymer microparticles (A) and the emulsifier and the migration of the polymer microparticles (A) into the organic solvent (B). As a result, the viscosity of the mixture increases. After the polymer microparticles (A) have sufficiently migrated into the organic solvent (B), in other words, after the viscosity of the mixture has become constant, when the mixture is brought into contact with water, the polymer microparticles (A) can sufficiently aggregate. Therefore, it is possible to prevent the discharge liquid from becoming cloudy due to the inclusion of unaggregated polymer microparticles (A).

[0021] [1-2. Method for producing purified polymer fine particles (A) (First method of production)] A method for producing purified polymer fine particles (A) according to one embodiment of the present invention includes an organic solvent mixing step of mixing polymer fine particles (A) and latex containing an emulsifier with an organic solvent (B), and a mixing state maintenance step of either letting the mixture obtained in the organic solvent mixing step stand and / or stirring the mixture. The emulsifier contains a lipophilic portion and a hydrophilic portion, and the hydrophilic portion has a polyoxyethylene group.

[0022] In this specification, "method for producing purified polymer fine particles (A)" may also be referred to as "method for purifying polymer fine particles (A)". Furthermore, the method for producing purified polymer fine particles (A) according to one embodiment of the present invention may be referred to as the "first method of production" below.

[0023] In this specification, "standing still" means not intentionally applying any shock, such as vibration, and can also be called "leaving it unattended." In this specification, "stirring" means intentionally applying any shock, including vibration, and the magnitude of the shock is not limited.

[0024] In other words, in this specification, stirring means all cases other than standing, so the state of the mixture falls under either "standing" or "stirring". In this specification, "both standing and stirring of the mixture" means either (i) standing followed by stirring, or (ii) stirring followed by standing. Note that stirring may be continued continuously from the organic solvent mixing step to the mixing state maintenance step.

[0025] The first manufacturing method uses an emulsifier having a polyoxyethylene group. Therefore, compared to the conventional technology that uses an emulsifier having a linear alkylbenzene, the first manufacturing method has the advantage of reducing the environmental impact. Furthermore, according to the first manufacturing method, purified polymer microparticles (A) can be efficiently produced from latex containing polymer microparticles (A) prepared using an emulsifier having a polyoxyethylene group, which has a low environmental impact. In addition, the purified polymer microparticles (A) obtained by the first manufacturing method have the advantage of having a low content of impurities such as emulsifiers, more specifically, elements P and S derived from emulsifiers. Moreover, the wastewater generated by carrying out the first manufacturing method contains very little polymer microparticle (A), meaning that the first manufacturing method has the advantage of being highly efficient in terms of production.

[0026] First, we will explain the raw materials (components) used in the first manufacturing method, and then we will explain each step of the process.

[0027] (1-2-1. Latex) In this specification, "latex" refers to a solution comprising a solvent, polymer microparticles (A), and an emulsifier, wherein the polymer microparticles (A) and the emulsifier are dispersed in the solvent. "Latex" can also be described as a "suspension of polymer microparticles (A)." The solvent for latex is not particularly limited, but water is an example. Latex in which the solvent is water is sometimes referred to as "aqueous latex" and can also be described as an "aqueous suspension of polymer microparticles (A)." In the solvent for latex, it is preferable that the polymer microparticles (A) are dispersed in the form of primary particles.

[0028] Latex containing polymer microparticles (A) and an emulsifier can be produced by known methods, such as emulsion polymerization of polymer microparticles (A) and a method of suspending polymer microparticles (A) and an emulsifier in a solvent. The emulsion polymerization of polymer microparticles (A) will be described in detail in section (2-3. Method for producing polymer microparticles (A)) below.

[0029] (1-2-2. Polymer fine particles (A)) Polymerized fine particles (A) are not particularly limited in other forms, as long as they are fine particles obtained by polymerization.

[0030] (graft section) The polymer microparticles (A) preferably have graft portions. In this specification, "graft portion" refers to a polymer that is graft-bonded to any polymer. Polymer microparticles (A) having graft portions can also be called graft copolymers. That is, it is preferable that the polymer microparticles (A) are graft copolymers. When the polymer microparticles (A) are graft copolymers, there is an advantage that the polymer microparticles (A) can exhibit suitable behavior in the first manufacturing method and in the resin composition manufacturing method described later.

[0031] Preferably, the graft portion is a polymer containing (or includes) a constituent unit derived from one or more monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers, and (meth)acrylate monomers. The graft portion having the above configuration can play various roles. "Various roles" include, for example, (i) improving the compatibility between polymer fine particles (A) and the resin (D) which is the matrix resin of the resin composition, (ii) improving the dispersibility of polymer fine particles (A) in the resin (D), and (iii) enabling the polymer fine particles (A) to be dispersed in the resin composition or its cured product in the state of primary particles.

[0032] Specific examples of aromatic vinyl monomers include styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene.

[0033] Specific examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile.

[0034] Specific examples of (meth)acrylate monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, hydroxyethyl (meth)acrylate, and hydroxybutyl (meth)acrylate. In this specification, (meth)acrylate means acrylate and / or methacrylate.

[0035] The one or more monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers, and (meth)acrylate monomers mentioned above may be used individually or in combination of two or more.

[0036] The graft portion preferably contains, as constituent units, 10 to 95% by weight, more preferably 30 to 92% by weight, even more preferably 50 to 90% by weight, particularly preferably 60 to 87% by weight, and most preferably 70 to 85% by weight, of constituent units derived from aromatic vinyl monomers, vinyl cyanide monomers, and (meth)acrylate monomers in total, per 100% by weight of the graft portion.

[0037] The graft portion preferably includes a constituent unit derived from a monomer having a reactive group. The monomer having a reactive group is preferably a monomer having one or more reactive groups selected from the group consisting of epoxy groups, oxetane groups, hydroxyl groups, amino groups, imide groups, carboxylic acid groups, carboxylic acid anhydride groups, cyclic esters, cyclic amides, benzoxazine groups, and cyanate ester groups, more preferably a monomer having one or more reactive groups selected from the group consisting of epoxy groups, hydroxyl groups, and carboxylic acid groups, and most preferably a monomer having an epoxy group. With this configuration, the graft portion of polymer fine particles (A) and the resin (D) (e.g., a thermosetting resin) can be chemically bonded in the resin composition. This makes it possible to maintain a good dispersion state of polymer fine particles (A) in the resin composition or its cured product without agglomerating the polymer fine particles (A).

[0038] Specific examples of monomers having an epoxy group include glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and glycidyl group-containing vinyl monomers such as allyl glycidyl ether.

[0039] Specific examples of monomers having a hydroxyl group include, for example, (i) hydroxylinear alkyl(meth)acrylates such as 2-hydroxyethyl(meth)acrylate, hydroxypropyl(meth)acrylate, and 4-hydroxybutyl(meth)acrylate (especially hydroxylinear C1-6 alkyl(meth)acrylate); (ii) caprolactone-modified hydroxy(meth)acrylate; (iii) hydroxybranched alkyl(meth)acrylates such as methyl α-(hydroxymethyl)acrylate and ethyl α-(hydroxymethyl)acrylate; and (iv) hydroxyl group-containing (meth)acrylates such as mono(meth)acrylates of polyester diols (especially saturated polyester diols) obtained from divalent carboxylic acids (such as phthalic acid) and divalent alcohols (such as propylene glycol).

[0040] Specific examples of monomers having a carboxylic acid group include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, as well as dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid. Among the monomers having a carboxylic acid group, the aforementioned monocarboxylic acids are preferably used.

[0041] The monomers having the reactive group described above may be used individually or in combination of two or more.

[0042] The graft portion preferably contains 0.5 to 90% by weight, more preferably 1 to 50% by weight, even more preferably 2 to 35% by weight, and particularly preferably 3 to 20% by weight of constituent units derived from monomers having reactive groups, per 100% by weight of the graft portion. When the graft portion contains (i) 0.5% by weight or more of constituent units derived from monomers having reactive groups, per 100% by weight of the graft portion, the resulting resin composition can provide a cured product with sufficient impact resistance, and (ii) when it contains 90% by weight or less, the resulting resin composition can provide a cured product with sufficient impact resistance and has the advantage of good storage stability.

[0043] Constituent units derived from monomers having reactive groups are preferably included in the graft portion, and more preferably included only in the graft portion.

[0044] The graft portion may contain constituent units derived from a polyfunctional monomer as constituent units. When the graft portion contains constituent units derived from a polyfunctional monomer, it has the following advantages: (i) swelling of polymer fine particles (A) can be prevented in the resin composition; (ii) the viscosity of the resin composition is reduced, which tends to improve the handling properties of the resin composition; and (iii) the dispersibility of polymer fine particles (A) in the resin (D) (e.g., a thermosetting resin) is improved.

[0045] When the graft portion does not contain structural units derived from polyfunctional monomers, the resulting resin composition can provide a cured product with superior toughness and impact resistance compared to when the graft portion contains structural units derived from polyfunctional monomers.

[0046] A polyfunctional monomer can also be described as a monomer having two or more radical polymerizable reactive groups within the same molecule. The radical polymerizable reactive groups are preferably carbon-carbon double bonds. Examples of polyfunctional monomers do not include butadiene, but include (meth)acrylates having ethylenically unsaturated double bonds, such as allylalkyl (meth)acrylates and allyloxyalkyl (meth)acrylates. Examples of monomers having two (meth)acrylic groups include ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and polyethylene glycol di(meth)acrylates. Examples of polyethylene glycol di(meth)acrylates include triethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and polyethylene glycol (600) di(meth)acrylate. Examples of monomers having three (meth)acrylic groups include alkoxylated trimethylolpropane tri(meth)acrylates, glycerol propoxy tri(meth)acrylate, pentaerythritol tri(meth)acrylate, and tris(2-hydroxyethyl) isocyanurate tri(meth)acrylate. Examples of alkoxylated trimethylolpropane tri(meth)acrylates include trimethylolpropane tri(meth)acrylate and trimethylolpropane triethoxy tri(meth)acrylate. Furthermore, examples of monomers having four (meth)acrylic groups include pentaerythritol tetra(meth)acrylate and ditrimethylolpropane tetra(meth)acrylate. Also, examples of monomers having five (meth)acrylic groups include dipentaerythritol penta(meth)acrylate. And examples of monomers having six (meth)acrylic groups include ditrimethylolpropane hexa(meth)acrylate.Other examples of polyfunctional monomers include diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene.

[0047] Among the polyfunctional monomers mentioned above, polyfunctional monomers that can be preferably used for polymerization of the graft portion include allyl methacrylate, ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and polyethylene glycol di(meth)acrylates. These polyfunctional monomers may be used individually or in combination of two or more.

[0048] The graft portion preferably contains 1 to 20% by weight, and more preferably 5 to 15% by weight, of constituent units derived from polyfunctional monomers, per 100% by weight of the graft portion.

[0049] In the polymerization of the graft portion, only one type of monomer may be used, or two or more types may be used in combination. Furthermore, the graft portion may contain, as a constituent unit, constituent units derived from other monomers in addition to the constituent units derived from the monomers described above.

[0050] Furthermore, the graft portion is preferably a polymer grafted onto an elastic body, as described later.

[0051] (Glass transition temperature of the graft) The glass transition temperature of the graft portion is preferably 190°C or lower, more preferably 160°C or lower, more preferably 140°C or lower, more preferably 120°C or lower, preferably 80°C or lower, more preferably 70°C or lower, more preferably 60°C or lower, more preferably 50°C or lower, more preferably 40°C or lower, more preferably 30°C or lower, more preferably 20°C or lower, more preferably 10°C or lower, more preferably 0°C or lower, more preferably -20°C or lower, more preferably -40°C or lower, more preferably -45°C or lower, and -50°C. Temperatures below -55°C are more preferable, below -60°C are more preferable, below -65°C are more preferable, below -70°C are more preferable, below -75°C are more preferable, below -80°C are more preferable, below -85°C are more preferable, below -90°C are more preferable, below -95°C are more preferable, below -100°C are more preferable, below -105°C are more preferable, below -110°C are more preferable, below -115°C are more preferable, below -120°C are even more preferable, and below -125°C are particularly preferable.

[0052] The glass transition temperature of the graft portion is preferably 0°C or higher, more preferably 30°C or higher, more preferably 50°C or higher, more preferably 70°C or higher, even more preferably 90°C or higher, and particularly preferably 110°C or lower.

[0053] The Tg of the graft can be determined by factors such as the composition of the constituent units contained in the graft. In other words, the Tg of the resulting graft can be adjusted by changing the composition of the monomers used when manufacturing (polymerizing) the graft.

[0054] The Tg of the graft can be obtained by performing viscoelasticity measurements using a flat plate made of polymer microparticles (A). Specifically, Tg can be measured as follows: (1) A dynamic viscoelasticity measurement is performed on a flat plate made of polymer microparticles (A) under tensile conditions using a dynamic viscoelasticity measuring device (e.g., DVA-200, manufactured by IT Measurement Control Co., Ltd.) to obtain a graph of tanδ; (2) The peak temperature of tanδ in the obtained graph is taken as the glass transition temperature. If multiple peaks are obtained in the graph of tanδ, the highest peak temperature is taken as the glass transition temperature of the graft.

[0055] (Graft rate of the grafted area) In one embodiment of the present invention, polymer fine particles (A) may include polymers having the same structure as the graft portion and that are not graft-bonded to any polymer (for example, an elastic body described later). In this specification, "polymers having the same structure as the graft portion and that are not graft-bonded to any polymer" is also referred to as a non-graft polymer. The non-graft polymer also constitutes a part of polymer fine particles (A) according to one embodiment of the present invention. The non-graft polymer can also be said to be a polymer produced in the polymerization of the graft portion that is not graft-bonded to any polymer.

[0056] In this specification, the proportion of polymers produced in the polymerization of the graft portion that are grafted to any polymer, i.e., the graft portion, is referred to as the graft ratio. The graft ratio can also be expressed as a value represented by (weight of graft portion) / {(weight of graft portion) + (weight of non-grafted polymer)} × 100.

[0057] The grafting rate of the grafted portion is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. When the grafting rate is 70% or more, it has the advantage that the viscosity of the resin composition does not become too high.

[0058] In this specification, the method for calculating the graft rate is as follows. First, an aqueous suspension containing polymer microparticles (A) is obtained, and then granular polymer microparticles (A) are obtained from the aqueous suspension. Specifically, a method for obtaining granular polymer microparticles (A) from an aqueous suspension is to (i) coagulate the polymer microparticles (A) in the aqueous suspension, (ii) dehydrate the resulting coagulation, and (iii) further dry the coagulation to obtain granular polymer microparticles (A). Next, 2 g of granular polymer microparticles (A) are dissolved in 50 mL of methyl ethyl ketone (hereinafter also referred to as MEK). After that, the obtained MEK solution is separated into MEK-soluble components and MEK-insoluble components. Specifically, the following steps (1) to (3) are performed: (1) Using a centrifuge (Hitachi Koki Co., Ltd., CP60E), the obtained MEK solution is subjected to centrifugation at a rotation speed of 30,000 rpm for 1 hour to separate the solution into MEK-soluble and MEK-insoluble components; (2) The obtained MEK-soluble components and MEK are mixed, and the resulting MEK mixture is subjected to centrifugation using the above-mentioned centrifuge at a rotation speed of 30,000 rpm for 1 hour to separate the MEK mixture into MEK-soluble and MEK-insoluble components; (3) The operation in (2) is repeated once (i.e., centrifugation is performed a total of three times). Concentrated MEK-soluble components are obtained by this operation. Next, 20 ml of the concentrated MEK-soluble components is mixed with 200 ml of methanol. An aqueous calcium chloride solution, obtained by dissolving 0.01 g of calcium chloride in water, is added to the resulting mixture, and the resulting mixture is stirred for 1 hour. Subsequently, the resulting mixture is separated into methanol-soluble and methanol-insoluble components, and the weight of the methanol-insoluble component is taken as the amount of free polymer (FP).

[0059] The graft ratio is calculated using the following formula. Grafting rate (%) = 100 - [(FP amount) / {(FP amount) + (weight of MEK insoluble portion)}] / (weight of polymer in the grafted portion) × 10000.

[0060] The weight of the polymer other than the graft portion is the amount of monomers that make up the polymer other than the graft portion. The polymer other than the graft portion is, for example, an elastic material. Also, if the polymer fine particles (A) contain a surface crosslinked polymer as described later, the polymer other than the graft portion includes both the elastic material and the surface crosslinked polymer. The weight of the polymer in the graft portion is the amount of monomers that make up the polymer in the graft portion. Furthermore, the method of coagulating the polymer fine particles (A) in calculating the graft rate is not particularly limited, and methods using solvents, methods using coagulants, methods using aqueous suspension spraying, etc., can be used.

[0061] (Torture of the graft area) In one embodiment of the present invention, the graft portion may consist of only one type of graft portion having the same compositional unit. In another embodiment of the present invention, the graft portion may consist of multiple types of graft portions, each having a different compositional unit.

[0062] In one embodiment of the present invention, a case in which the graft portion consists of multiple types of graft portions will be described. In this case, each of the multiple types of graft portions is called graft portion 1, graft portion 2, ..., graft portion n Let n be an integer greater than or equal to 2. The graft portion consists of graft portion 1, graft portion 2, ..., and graft portion, each separately superimposed. n It may also include a composite of the following: The graft portion is graft portion 1, graft portion 2, ..., and graft portion n The polymer may also contain a single polymer obtained by sequentially polymerizing each of the components. This sequential polymerization of multiple polymerized portions (graft portions) is also called multi-stage polymerization. A polymer obtained by multi-stage polymerization of multiple types of graft portions is also called a multi-stage polymerized graft portion. The method for producing the multi-stage polymerized graft portion will be described in detail later.

[0063] When the graft part consists of a plurality of types of graft parts, not all of these plurality of types of graft parts need to be graft-bonded to the elastic body. It is sufficient that at least a part of at least one type of graft part is graft-bonded to the elastic body, and the other type (the other plurality of types) of graft parts may be graft-bonded to the graft part that is graft-bonded to the elastic body. Also, when the graft part consists of a plurality of types of graft parts, it may have a plurality of polymers (a plurality of non-grafted polymers) that have the same configuration as the plurality of types of graft parts and are not graft-bonded to the elastic body.

[0064] Graft part 1, graft part 2, ···, and graft part n The multi-stage polymerization graft part composed of will be described. In the multi-stage polymerization graft part, graft part n can cover at least a part of graft part n-1 or can cover the whole of graft part n-1 . In the multi-stage polymerization graft part, a part of graft part n may enter inside graft part n-1 .

[0065] In the multi-stage polymerization graft part, each of the plurality of graft parts may form a layer structure. For example, when the multi-stage polymerization graft part consists of graft part 1, graft part 2, and graft part 3, a mode in which graft part 1 forms the innermost layer in the graft part, a layer of graft part 2 is formed outside graft part 1, and a layer of graft part 3 is formed as the outermost layer outside the layer of graft part 2 is also an aspect of the present invention. Thus, the multi-stage polymerization graft part in which each of the plurality of graft parts forms a layer structure can also be said to be a multi-layer graft part. That is, in one embodiment of the present invention, the graft part may include (i) a composite of a plurality of types of graft parts, (ii) a multi-stage polymerization graft part and / or (iii) a multi-layer graft part.

[0066] When polymer nanoparticles (A) are polymerized in this order with an arbitrary polymer (for example, an elastic material described later) and a graft portion, at least a portion of the graft portion in the resulting polymer nanoparticles (A) can cover at least a portion of the arbitrary polymer. Polymerization of an arbitrary polymer and a graft portion in this order can also be described as multi-stage polymerization of an arbitrary polymer and a graft portion. Polymer nanoparticles (A) obtained by multi-stage polymerization of an arbitrary polymer and a graft portion can also be called multi-stage polymers.

[0067] When the polymer microparticles (A) are a multi-stage polymer, the graft portion may cover at least a portion of any polymer (for example, an elastic body described later), or it may cover the entire polymer. When the polymer microparticles (A) are a multi-stage polymer, a portion of the graft portion may also penetrate inside any polymer. It is preferable that at least a portion of the graft portion covers at least a portion of the elastic body. In other words, it is preferable that at least a portion of the graft portion is located on the outermost surface of the polymer microparticles (A).

[0068] When the polymer nanoparticles (A) are a multi-stage polymer, any polymer (e.g., an elastic body described later) and graft portion may form a layered structure. For example, one embodiment of the present invention is in which the elastic body forms the innermost layer (also referred to as the core layer), and the graft portion layer is formed outside the elastic body as the outermost layer (also referred to as the shell layer). A structure in which the elastic body is the core layer and the graft portion is the shell layer can also be called a core-shell structure. In this way, polymer nanoparticles (A) in which the elastic body and graft portion form a layered structure (core-shell structure) can also be called a multilayer polymer or a core-shell polymer. That is, in one embodiment of the present invention, the polymer nanoparticles (A) may be a multi-stage polymer and / or a multilayer polymer or a core-shell polymer. However, as long as they have a graft portion, the polymer nanoparticles (A) are not limited to the above configuration.

[0069] (Elastic body) The polymer fine particles (A) preferably further have an elastic body. The graft portion described above is preferably a polymer graft-bonded to the elastic body. That is, it is more preferable that the polymer fine particles (A) are a rubber-containing graft copolymer having an elastic body and a graft portion graft-bonded to the elastic body. The following describes one embodiment of the present invention, using the case where the polymer fine particles (A) are a rubber-containing graft copolymer as an example.

[0070] The elastic body preferably contains one or more selected from the group consisting of diene rubber, (meth)acrylate rubber, and organosiloxane rubber. In addition to the rubbers mentioned above, the elastic body may also contain natural rubber. The elastic body can also be referred to as an elastic part or rubber particles.

[0071] The case where the elastic body contains a diene rubber (Case A) will be described. In Case A, the resulting resin composition can provide a cured product with excellent toughness and impact resistance. A cured product with excellent toughness and / or impact resistance can also be said to be a cured product with excellent durability.

[0072] The diene rubber is an elastic body that contains constituent units derived from diene monomers as constituent units. The diene monomer can also be referred to as a conjugated diene monomer. In case A, the diene rubber may contain 50 to 100% by weight of constituent units derived from diene monomers and 0 to 50% by weight of constituent units derived from vinyl monomers other than diene monomers copolymerizable with diene monomers, out of 100% by weight of constituent units. In case A, the diene rubber may also contain constituent units derived from (meth)acrylate monomers in a smaller amount than the constituent units derived from diene monomers.

[0073] Examples of diene monomers include 1,3-butadiene, isoprene(2-methyl-1,3-butadiene), and 2-chloro-1,3-butadiene. These diene monomers may be used individually or in combination of two or more.

[0074] Examples of vinyl monomers other than diene monomers that can copolymerize with diene monomers (hereinafter also referred to as vinyl monomer A) include vinylarenes such as styrene, α-methylstyrene, monochlorostyrene, and dichlorostyrene; vinyl carboxylic acids such as acrylic acid and methacrylic acid; vinyl cyanides such as acrylonitrile and methacrylonitrile; vinyl halides such as vinyl chloride, vinyl bromide, and chloroprene; vinyl acetate; alkenes such as ethylene, propylene, butylene, and isobutylene; and polyfunctional monomers such as diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. One type of vinyl monomer A may be used, or two or more types may be used in combination. Among the vinyl monomer A described above, styrene is particularly preferred. In the diene rubber in case A, the constituent units derived from vinyl monomer A are optional components. In case A, the diene rubber may be composed solely of constituent units derived from the diene monomer.

[0075] In case A, the diene rubber is preferably butadiene rubber (also called polybutadiene rubber) consisting of structural units derived from 1,3-butadiene, or butadiene-styrene rubber (also called polystyrene-butadiene), which is a copolymer of 1,3-butadiene and styrene, with butadiene rubber being more preferred. With the above configuration, the desired effects due to the polymer fine particles (A) containing the diene rubber can be more effectively exhibited. Furthermore, butadiene-styrene rubber is more preferred because the transparency of the resulting cured product can be improved by adjusting the refractive index.

[0076] Case B describes the case where the elastic material includes (meth)acrylate rubber. In Case B, a wide range of polymer designs for the elastic material are possible by combining various monomers.

[0077] The (meth)acrylate-based rubber is an elastic body that contains constituent units derived from (meth)acrylate monomers as constituent units. In case B, the (meth)acrylate-based rubber may contain 50 to 100% by weight of constituent units derived from (meth)acrylate monomers and 0 to 50% by weight of constituent units derived from vinyl monomers other than (meth)acrylate monomers that can copolymerize with (meth)acrylate monomers, based on 100% by weight of constituent units. In case B, the (meth)acrylate-based rubber may also contain constituent units derived from diene monomers in a smaller amount than the constituent units derived from (meth)acrylate monomers.

[0078] Examples of (meth)acrylate monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; and 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate. Examples include hydroxyalkyl (meth)acrylates such as acrylate; glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidylalkyl (meth)acrylate; alkoxyalkyl (meth)acrylates; allylalkyl (meth)acrylates such as allyl (meth)acrylate and allylalkyl (meth)acrylate; and polyfunctional (meth)acrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate. These (meth)acrylate monomers may be used individually or in combination of two or more. Among these (meth)acrylate monomers, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate are preferred, and butyl (meth)acrylate is more preferred.

[0079] In case B, the (meth)acrylate rubber is preferably one or more selected from the group consisting of ethyl (meth)acrylate rubber, butyl (meth)acrylate rubber, and 2-ethylhexyl (meth)acrylate rubber, with butyl (meth)acrylate rubber being more preferred. Ethyl (meth)acrylate rubber is a rubber composed of structural units derived from ethyl (meth)acrylate, butyl (meth)acrylate rubber is a rubber composed of structural units derived from butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate rubber is a rubber composed of structural units derived from 2-ethylhexyl (meth)acrylate. With this configuration, the glass transition temperature (Tg) of the elastic body is lowered, so polymer fine particles (A) and resin compositions with low Tg can be obtained. As a result, (i) the obtained resin composition can provide a cured product with excellent toughness, and (ii) the viscosity of the resin composition can be further reduced.

[0080] Examples of vinyl monomers other than (meth)acrylate monomers that can copolymerize with (meth)acrylate monomers (hereinafter also referred to as vinyl monomer B) include the monomers listed in vinyl monomer A above. Vinyl monomer B may be used alone or in combination of two or more types. Among vinyl monomer B, styrene is particularly preferred. In case B, the constituent units derived from vinyl monomer B are arbitrary components. In case B, the (meth)acrylate rubber may be composed only of constituent units derived from (meth)acrylate monomers.

[0081] Case C, where the elastic body contains an organosiloxane-based rubber, will be described. In Case C, the resulting resin composition can provide a cured product that has sufficient heat resistance and excellent impact resistance at low temperatures.

[0082] Examples of organosiloxane-based rubbers include (i) organosiloxane polymers composed of alkyl or aryl 2-substituted silyloxy units such as dimethylsilyloxy, diethylsilyloxy, methylphenylsilyloxy, diphenylsilyloxy, and dimethylsilyloxy-diphenylsilyloxy, and (ii) organosiloxane polymers composed of alkyl or aryl 1-substituted silyloxy units such as organohydrogensilyloxy, in which part of the alkyl in the side chain is substituted with a hydrogen atom. These organosiloxane polymers may be used individually or in combination of two or more.

[0083] In this specification, polymers composed of dimethylsilyloxy units are referred to as dimethylsilyloxy rubber, polymers composed of methylphenylsilyloxy units are referred to as methylphenylsilyloxy rubber, and polymers composed of dimethylsilyloxy units and diphenylsilyloxy units are referred to as dimethylsilyloxy-diphenylsilyloxy rubber. In case C, the organosiloxane rubber is preferably one or more selected from the group consisting of dimethylsilyloxy rubber, methylphenylsilyloxy rubber, and dimethylsilyloxy-diphenylsilyloxy rubber, because (i) the resin composition containing the resulting powder and granules can provide a cured or molded article with excellent heat resistance, and (ii) dimethylsilyloxy rubber is more preferably selected because it is readily available and economical.

[0084] In case C, the polymer fine particles (A) preferably contain 80% by weight or more of organosiloxane-based rubber, and more preferably 90% by weight or more, of the elastic material contained in 100% by weight of the polymer fine particles (A). According to the above configuration, the resulting resin composition can provide a cured product with excellent heat resistance.

[0085] The elastic body may further contain elastic bodies other than diene rubber, (meth)acrylate rubber, and organosiloxane rubber. Examples of elastic bodies other than diene rubber, (meth)acrylate rubber, and organosiloxane rubber include natural rubber.

[0086] In one embodiment of the present invention, the elastic body is preferably one or more selected from the group consisting of butadiene rubber, butadiene-styrene rubber, butadiene-(meth)acrylate rubber, ethyl(meth)acrylate rubber, butyl(meth)acrylate rubber, 2-ethylhexyl(meth)acrylate rubber, dimethylsilyloxy rubber, methylphenylsilyloxy rubber, and dimethylsilyloxy-diphenylsilyloxy rubber, and more preferably one or more selected from the group consisting of butadiene rubber, butadiene-styrene rubber, butyl(meth)acrylate rubber, and dimethylsilyloxy rubber.

[0087] (Elastomer cross-linking structure) From the viewpoint of maintaining the dispersion stability of polymer fine particles (A) in a thermosetting resin, it is preferable that a crosslinked structure is introduced into the elastic body. As a method for introducing a crosslinked structure into the elastic body, commonly used methods can be employed, for example, the following method: In the production of the elastic body, a method can be used in which a crosslinkable monomer such as a polyfunctional monomer and / or a mercapto group-containing compound is mixed with monomers that can constitute the elastic body, and then polymerized. In this specification, the production of polymers such as elastic bodies is also referred to as polymerizing polymers.

[0088] Furthermore, the following methods can be used to introduce a crosslinked structure into organosiloxane rubber: (A) a method of polymerizing organosiloxane rubber in combination with a polyfunctional alkoxysilane compound and other materials; (B) a method of introducing reactive groups (e.g., (i) mercapto groups and (ii) reactive vinyl groups, etc.) into organosiloxane rubber, and then adding (i) an organic peroxide or (ii) a polymerizable vinyl monomer to the resulting reaction product to carry out a radical reaction; or (C) a method of polymerizing organosiloxane rubber by mixing a crosslinkable monomer such as a polyfunctional monomer and / or a mercapto group-containing compound with other materials, and then carrying out polymerization.

[0089] Examples of polyfunctional monomers include those exemplified in the (graft portion) section above.

[0090] Examples of mercapto group-containing compounds include alkyl group-substituted mercaptans, allyl group-substituted mercaptans, aryl group-substituted mercaptans, hydroxyl group-substituted mercaptans, alkoxy group-substituted mercaptans, cyano group-substituted mercaptans, amino group-substituted mercaptans, silyl group-substituted mercaptans, acid group-substituted mercaptans, halo group-substituted mercaptans, and acyl group-substituted mercaptans. Among alkyl group-substituted mercaptans, alkyl group-substituted mercaptans having 1 to 20 carbon atoms are preferred, and alkyl group-substituted mercaptans having 1 to 10 carbon atoms are more preferred. Among aryl group-substituted mercaptans, phenyl group-substituted mercaptans are preferred. Among alkoxy group-substituted mercaptans, alkoxy group-substituted mercaptans having 1 to 20 carbon atoms are preferred, and alkoxy group-substituted mercaptans having 1 to 10 carbon atoms are more preferred. Preferably, the acid group-substituted mercaptan is an alkyl group-substituted mercaptan having 1 to 10 carbon atoms and a carboxyl group, or an aryl group-substituted mercaptan having 1 to 12 carbon atoms and a carboxyl group.

[0091] (Glass transition temperature of an elastic material) The glass transition temperature of the elastic material is preferably 80°C or lower, more preferably 70°C or lower, more preferably 60°C or lower, more preferably 50°C or lower, more preferably 40°C or lower, more preferably 30°C or lower, more preferably 20°C or lower, more preferably 10°C or lower, more preferably 0°C or lower, more preferably -20°C or lower, more preferably -40°C or lower, more preferably -45°C or lower, more preferably -50°C or lower, more preferably -55°C or lower, more preferably -60°C or lower, more preferably -65°C or lower, more preferably -70°C or lower, more preferably -75°C or lower, more preferably -80°C or lower, more preferably -85°C or lower, more preferably -90°C or lower, more preferably -95°C or lower, more preferably -100°C or lower, more preferably -105°C or lower, more preferably -110°C or lower, more preferably -115°C or lower, even more preferably -120°C or lower, and particularly preferably -125°C or lower. In this specification, "glass transition temperature" may also be referred to as "Tg". According to this configuration, polymer fine particles (A) having a low Tg and a resin composition having a low Tg can be obtained. As a result, the obtained resin composition can provide a cured product with excellent toughness. Furthermore, according to this configuration, the viscosity of the obtained resin composition can be made even lower. The Tg of the elastic body can be obtained by performing viscoelasticity measurements using a flat plate made of polymer fine particles (A). Specifically, Tg can be measured as follows: (1) A dynamic viscoelasticity measurement is performed on a flat plate made of polymer fine particles (A) under tensile conditions using a dynamic viscoelasticity measuring device (e.g., DVA-200 manufactured by IT Measurement Control Co., Ltd.) to obtain a graph of tanδ; (2) The peak temperature of tanδ in the obtained graph is taken as the glass transition temperature. Here, if multiple peaks are obtained in the graph of tanδ, the lowest peak temperature is taken as the glass transition temperature of the elastic body.

[0092] On the other hand, a decrease in the elastic modulus (stiffness) of the resulting cured product can be suppressed, that is, a cured product with sufficient elastic modulus (stiffness) can be obtained. Therefore, the Tg of the elastic body is preferably greater than 0°C, more preferably 20°C or higher, even more preferably 50°C or higher, particularly preferably 80°C or higher, and most preferably 120°C or higher.

[0093] The Tg of an elastic material can be determined by factors such as the composition of the constituent units contained within the elastic material. In other words, the Tg of the resulting elastic material can be adjusted by changing the composition of the monomers used when manufacturing (polymerizing) the elastic material.

[0094] Here, monomer group a is defined as the group of monomers that, when polymerized using only one type of monomer, provide a homopolymer having a Tg greater than 0°C. Monomer group b is defined as the group of monomers that, when polymerized using only one type of monomer, provide a homopolymer having a Tg less than 0°C. Elastic body G is defined as an elastic body containing 50 to 100% by weight (more preferably 65 to 99% by weight) of constituent units derived from at least one monomer selected from monomer group a, and 0 to 50% by weight (more preferably 1 to 35% by weight) of constituent units derived from at least one monomer selected from monomer group b. Elastic body G has a Tg greater than 0°C. Furthermore, when the elastic body contains elastic body G, the resulting resin composition can provide a cured product with sufficient rigidity.

[0095] Even when the Tg of the elastic material is greater than 0°C, it is preferable that a cross-linking structure is introduced into the elastic material. The method described above is an example of how to introduce the cross-linking structure.

[0096] The monomers that may be included in the monomer group a are not limited to the following, but include, for example, unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; vinyl-substituted aromatic compounds such as α-methylstyrene; cyclic alkylated vinyl aromatic compounds such as 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, and 2,4,6-trimethylstyrene; cyclic alkoxylated vinyl aromatic compounds such as 4-methoxystyrene and 4-ethoxystyrene; cyclic halogenated vinyl aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; cyclic ester-substituted vinyl aromatic compounds such as 4-acetoxystyrene; and cyclic hydroxylated compounds such as 4-hydroxystyrene. Examples include vinyl aromatic compounds; vinyl esters such as vinyl benzoate and vinylcyclohexanoate; vinyl halides such as vinyl chloride; aromatic monomers such as acenaphthalene and indene; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, and isopropyl methacrylate; aromatic methacrylates such as phenyl methacrylate; methacrylates such as isobornyl methacrylate and trimethylsilyl methacrylate; methacrylic monomers including methacrylic acid derivatives such as methacrylonitrile; certain acrylic acid esters such as isobornyl acrylate and tert-butyl acrylate; and acrylic monomers including acrylic acid derivatives such as acrylonitrile. Furthermore, monomers that may be included in the monomer group a include acrylamide, isopropylacrylamide, N-vinylpyrrolidone, isobornyl methacrylate, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate, which can provide a homopolymer having a Tg of 120°C or higher when formed as a homopolymer. These monomers a may be used individually or in combination of two or more.

[0097] Examples of monomer b include ethyl acrylate, butyl acrylate (also known as butyl acrylate), 2-ethylhexyl acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, 2-hydroxyethyl acrylate, and 4-hydroxybutyl acrylate. These monomers b may be used individually or in combination of two or more. Among these monomers b, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate are particularly preferred.

[0098] (Volume-average particle diameter of an elastic body) The volume-average particle diameter of the elastic material is preferably 0.03 μm to 50.00 μm, more preferably 0.05 μm to 10.00 μm, more preferably 0.08 μm to 2.00 μm, even more preferably 0.10 μm to 1.00 μm, even more preferably 0.10 μm to 0.80 μm, and particularly preferably 0.10 μm to 0.50 μm. When the volume-average particle diameter of the elastic material is (i) 0.03 μm or more, an elastic material having the desired volume-average particle diameter can be stably obtained, and when it is 50.00 μm or less, the resulting cured or molded product will have good heat resistance and impact resistance. The volume-average particle diameter of the elastic material can be measured using a dynamic light scattering particle size distribution analyzer or the like, with an aqueous suspension containing the elastic material as the sample. The method for measuring the volume-average particle diameter of the elastic material will be described in detail in the following examples.

[0099] (Percentage of elastic material) The proportion of elastic material in polymer fine particles (A) is preferably 40 to 97% by weight, more preferably 60 to 95% by weight, and even more preferably 70 to 93% by weight, based on 100% by weight of the total polymer fine particles (A). When the proportion of elastic material is (i) 40% by weight or more, the resulting resin composition can provide a cured product with excellent toughness and impact resistance, and when it is 97% by weight or less, the polymer fine particles (A) do not easily aggregate, so the resin composition does not become highly viscous, and as a result, the resulting resin composition can be easy to handle.

[0100] (Gel content of the elastic material) The elastic material is preferably capable of swelling in a suitable solvent but is substantially insoluble. It is also preferable that the elastic material is insoluble in the thermosetting resin used.

[0101] The elastic body preferably has a gel content of 60% by weight or more, more preferably 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more. When the gel content of the elastic body is within the above range, the resulting resin composition can provide a cured product with excellent toughness.

[0102] In this specification, the method for calculating the gel content is as follows. First, an aqueous suspension containing polymer microparticles (A) is obtained, and then granular polymer microparticles (A) are obtained from the aqueous suspension. The method for obtaining granular polymer microparticles (A) from the aqueous suspension is not particularly limited, but for example, one method is to obtain granular polymer microparticles (A) by (i) agglutinating the polymer microparticles (A) in the aqueous suspension, (ii) dehydrating the resulting agglutination, and (iii) further drying the agglutination. Next, 2.0 g of granular polymer microparticles (A) is dissolved in 50 mL of methyl ethyl ketone (MEK). Subsequently, the obtained MEK solution is separated into MEK-soluble components (MEK-soluble components) and MEK-insoluble components (MEK-insoluble components). Specifically, a centrifuge (Hitachi Koki Co., Ltd., CP60E) is used to centrifuge the obtained MEK solution at a rotation speed of 30,000 rpm for 1 hour, separating the solution into MEK-soluble and MEK-insoluble components. A total of three sets of centrifugation are performed. The weights of the obtained MEK-soluble and MEK-insoluble components are measured, and the gel content is calculated using the following formula. Gel content (%) = (weight of methyl ethyl ketone insoluble portion) / {(weight of methyl ethyl ketone insoluble portion) + (weight of methyl ethyl ketone soluble portion)} × 100 (Modified example of an elastic body) In one embodiment of the present invention, the "elastic body" of the polymer fine particles (A) may consist of only one type of elastic body having the same composition of constituent units. In this case, the "elastic body" of the polymer fine particles (A) is one type selected from the group consisting of diene rubber, (meth)acrylate rubber, and organosiloxane rubber.

[0103] In one embodiment of the present invention, the "elastic body" of the polymer fine particles (A) may consist of multiple types of elastic bodies, each with a different composition of constituent units. In this case, the "elastic body" of the polymer fine particles (A) may consist of two or more types selected from the group consisting of diene rubber, (meth)acrylate rubber, and organosiloxane rubber. Alternatively, in this case, the "elastic body" of the polymer fine particles (A) may consist of one type selected from the group consisting of diene rubber, (meth)acrylate rubber, and organosiloxane rubber. In other words, the "elastic body" of the polymer fine particles (A) may consist of multiple types of diene rubber, (meth)acrylate rubber, or organosiloxane rubber, each with a different composition of constituent units.

[0104] In one embodiment of the present invention, the case in which the "elastic body" of polymer fine particles (A) consists of multiple types of elastic bodies, each having a different composition of constituent units, will be described. In this case, each of the multiple types of elastic bodies is referred to as elastic body 1, elastic body 2, ..., and elastic body n Let n be an integer greater than or equal to 2. The "elastic body" of the polymer microparticles (A) is elastic body 1, elastic body 2, ..., and elastic body, which are polymerized separately. n It may also contain a composite of the following. The "elastic body" of the polymer fine particles (A) is elastic body 1, elastic body 2, ..., and elastic body n The material may include one elastic body obtained by sequentially polymerizing each of the other materials. This sequential polymerization of multiple elastic bodies (polymers) is also called multi-stage polymerization. An elastic body obtained by multi-stage polymerization of multiple types of elastic bodies is also called a multi-stage polymerized elastic body. The method for producing a multi-stage polymerized elastic body will be described in detail later.

[0105] Elastic body 1, elastic body 2, ..., and elastic bodyn A multi-stage polymerized elastic body consisting of the following will be described. In this multi-stage polymerized elastic body, the elastic body n is an elastic body n-1 It may cover at least a portion of the elastic body n-1 The entire body can be covered. In the multi-stage polymerized elastic body, the elastic body n Part of it is elastic n-1 It can sometimes be found inside.

[0106] In a multi-stage polymerized elastic body, each of the multiple elastic bodies may form a layered structure. For example, in a multi-stage polymerized elastic body consisting of elastic body 1, elastic body 2, and elastic body 3, elastic body 1 forms the innermost layer, the layer of elastic body 2 is formed outside of elastic body 1, and the layer of elastic body 3 is formed outside the layer of elastic body 2 as the outermost layer of the elastic body. This is also one embodiment of the present invention. In this way, a multi-stage polymerized elastic body in which each of the multiple elastic bodies forms a layered structure can also be called a multilayer elastic body. That is, in one embodiment of the present invention, the "elastic body" of the polymer fine particles (A) may include (i) a composite of multiple types of elastic bodies, (ii) a multi-stage polymerized elastic body, and / or (iii) a multilayer elastic body.

[0107] (Surface crosslinked polymer) The rubber-containing graft copolymer preferably further comprises a surface crosslinked polymer in addition to the elastic body and the graft portion grafted to the elastic body. In other words, the polymer fine particles (A) preferably further comprises a surface crosslinked polymer in addition to the elastic body and the graft portion grafted to the elastic body. Below, an embodiment of the present invention will be described using the case in which the polymer fine particles (A) (for example, a rubber-containing graft copolymer) further comprises a surface crosslinked polymer as an example. In this case, (i) the blocking resistance can be improved in the production of the polymer fine particles (A), and (ii) the dispersibility of the polymer fine particles (A) in the thermosetting resin is improved. The reasons for these are not particularly limited, but can be inferred as follows: The surface crosslinked polymer coats at least a part of the elastic body, reducing the exposure of the elastic portion of the polymer fine particles (A), and as a result, the elastic bodies are less likely to stick together, thus improving the dispersibility of the polymer fine particles (A).

[0108] If the polymer fine particles (A) have a surface crosslinked polymer, they may also have the following effects: (i) an effect of reducing the viscosity of the resin composition described later, (ii) an effect of increasing the crosslink density in the elastic body, and (iii) an effect of improving the graft efficiency of the graft portion. The crosslink density in the elastic body refers to the degree of the number of crosslinked structures in the entire elastic body.

[0109] The surface crosslinked polymer consists of a polymer containing 30-100% by weight of structural units derived from polyfunctional monomers and 0-70% by weight of structural units derived from other vinyl monomers, totaling 100% by weight.

[0110] Polyfunctional monomers that can be used in the polymerization of surface crosslinked polymers include the same monomers as those described above. Among these polyfunctional monomers, polyfunctional monomers that can be preferably used in the polymerization of surface crosslinked polymers include allyl methacrylate, ethylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate (e.g., 1,3-butylene glycol dimethacrylate), butanediol di(meth)acrylate, hexanediol di(meth)acrylate, cyclohexanedimethanol di(meth)acrylate, and polyethylene glycol di(meth)acrylates. These polyfunctional monomers may be used individually or in combination of two or more.

[0111] Polymeric fine particles (A) may include a surface crosslinked polymer polymerized independently of the polymerization of the rubber-containing graft copolymer, or may include a surface crosslinked polymer polymerized together with the rubber-containing graft copolymer. Polymeric fine particles (A) may also be a multi-stage polymer obtained by multi-stage polymerization of an elastic body, a surface crosslinked polymer, and a graft portion in this order. In any of these embodiments, the surface crosslinked polymer can coat at least a portion of the elastic body.

[0112] The surface crosslinked polymer can also be considered as part of the elastic body. In other words, the surface crosslinked polymer can also be considered as part of the rubber-containing graft copolymer, or it can be called the surface crosslinked polymer portion. When polymer fine particles (A) contain the surface crosslinked polymer, the graft portion may (i) be graft-bonded to an elastic body other than the surface crosslinked polymer, (ii) be graft-bonded to the surface crosslinked polymer, or (iii) be graft-bonded to both the elastic body other than the surface crosslinked polymer and the surface crosslinked polymer. When polymer fine particles (A) contain the surface crosslinked polymer, the volume-average particle diameter of the elastic body described above refers to the volume-average particle diameter of the elastic body containing the surface crosslinked polymer.

[0113] Case D describes the case where the polymer fine particles (A) are a multi-stage polymer obtained by multi-stage polymerization of an elastic body, a surface crosslinked polymer, and a graft portion in this order. In Case D, the surface crosslinked polymer may cover a part of the elastic body or the entire elastic body. In Case D, a part of the surface crosslinked polymer may penetrate inside the elastic body. In Case D, the graft portion may cover a part of the surface crosslinked polymer or the entire surface crosslinked polymer. In Case D, a part of the graft portion may penetrate inside the surface crosslinked polymer. In Case D, the elastic body, the surface crosslinked polymer, and the graft portion may have a layered structure. For example, one embodiment of the present invention is in which the elastic body is the innermost layer (core layer), a layer of surface crosslinked polymer exists outside the elastic body as an intermediate layer, and a layer of graft portion exists outside the surface crosslinked polymer as the outermost layer (shell layer).

[0114] (Volume-average particle size (Mv) of polymer microparticles (A)) The volume-average particle size (Mv) of the polymer fine particles (A) is preferably 0.03 μm to 50.00 μm, more preferably 0.05 μm to 10.00 μm, more preferably 0.08 μm to 2.00 μm, even more preferably 0.10 μm to 1.00 μm, even more preferably 0.10 μm to 0.80 μm, and particularly preferably 0.10 μm to 0.50 μm, in order to obtain a resin composition with the desired viscosity and high stability. When the volume-average particle size (Mv) of the polymer fine particles (A) is within the above range, there is also the advantage that the dispersibility of the polymer fine particles (A) in the resin (D) (e.g., thermosetting resin) is good. In this specification, "volume-average particle size (Mv) of polymer fine particles (A)" refers to the volume-average particle size of the primary particles of the polymer fine particles (A), unless otherwise specified. The volume-average particle size of polymer microparticles (A) can be measured using a dynamic light scattering particle size distribution analyzer or the like, with aqueous latex containing polymer microparticles (A) as the sample.

[0115] (1-2-3. Method for producing polymer microparticles (A)) The following describes an example of a method for producing polymer fine particles (A), using as an example the case in which polymer fine particles (A) include a rubber-containing graft copolymer having an elastic body and a graft portion graft-bonded to the elastic body. Polymer fine particles (A) can be produced, for example, by polymerizing the elastic body and then graft polymerizing the polymer constituting the graft portion to the elastic body in the presence of the elastic body.

[0116] Polymeric microparticles (A) can be manufactured by known methods, such as emulsion polymerization, suspension polymerization, and microsuspension polymerization. Specifically, the polymerization of the elastic body, the polymerization of the graft portion (graft polymerization), and the polymerization of the surface crosslinked polymer in polymeric microparticles (A) can be carried out by known methods, such as emulsion polymerization, suspension polymerization, and microsuspension polymerization. Among these, emulsion polymerization is particularly preferred as a method for manufacturing polymeric microparticles (A). Emulsion polymerization has the advantages of (i) easy composition design of polymeric microparticles (A), (ii) easy industrial production of polymeric microparticles (A), and (iii) easy acquisition of latex suitable for use in the first manufacturing method. The following describes methods for manufacturing elastic bodies, graft portions, and surface crosslinked polymers of any configuration that may be included in polymeric microparticles (A).

[0117] (Method of manufacturing an elastic body) Consider the case where the elastic body includes at least one selected from the group consisting of diene rubbers and (meth)acrylate rubbers. In this case, the elastic body can be manufactured by methods such as emulsion polymerization, suspension polymerization, and microsuspension polymerization, and as a manufacturing method, for example, the method described in WO2005 / 028546 can be used.

[0118] Let's consider the case where the elastic body contains organosiloxane-based rubber. In this case, the elastic body can be manufactured by methods such as emulsion polymerization, suspension polymerization, or microsuspension polymerization, and as a manufacturing method, for example, the method described in WO2006 / 070664 can be used.

[0119] The "elastic body" of the polymer microparticles (A) is composed of multiple types of elastic bodies (for example, elastic body 1, elastic body 2, ..., elastic body n The following describes the case where the components consist of: elastic body 1, elastic body 2, ..., elastic body n Each of these materials may be polymerized separately by the method described above, and then mixed and compounded to produce a composite consisting of multiple types of elastic materials. Alternatively, elastic material 1, elastic material 2, ..., elastic material n These materials may be polymerized sequentially in multiple stages to produce a single elastic body composed of multiple types of elastic materials.

[0120] The multi-stage polymerization of elastic bodies will be explained in detail. For example, a multi-stage polymerized elastic body can be obtained by performing the following steps (1) to (4) in order: (1) Polymerize elastic body 1 to obtain elastic body 1; (2) Then polymerize elastic body 2 in the presence of elastic body 1 to obtain a two-stage elastic body. 1+2 (3) obtain an elastic body 1+2 In the presence of [unclear], the elastic body 3 is polymerized to form a three-stage elastic body. 1+2+3 (4) After performing the same procedure, the elastic body 1+2+···+(n-1) Elastic body in the presence of n Polymerizing to form a multi-stage polymerized elastic body 1+2+···+n To obtain.

[0121] (Method of manufacturing the graft) The graft portion can be formed, for example, by polymerizing the monomer used to form the graft portion by known radical polymerization in the presence of any polymer (e.g., an elastic material). When (i) an elastic material, or (ii) a polymer fine particle precursor containing an elastic material and a surface crosslinked polymer is obtained as an aqueous suspension, polymerization of the graft portion is preferably carried out by emulsion polymerization. The graft portion can be produced, for example, according to the method described in WO2005 / 028546.

[0122] The graft portion consists of multiple types of graft portions (for example, graft portion 1, graft portion 2, ..., graft portion nThe method for manufacturing the graft portion when it consists of ) is described below. In this case, graft portion 1, graft portion 2, ..., graft portion n Each of these may be polymerized separately by the method described above, and then mixed and compounded to produce a graft (composite) consisting of multiple types of graft parts. Alternatively, graft part 1, graft part 2, ..., graft part n These may be polymerized sequentially in multiple stages to produce a single graft portion consisting of multiple types of graft portions.

[0123] The multi-stage polymerization of the graft portion will be explained in detail. For example, a multi-stage polymerized graft portion can be obtained by performing the following steps (1) to (4) in order: (1) Polymerize graft portion 1 to obtain graft portion 1; (2) Then polymerize graft portion 2 in the presence of graft portion 1 to obtain a two-stage graft portion 1+2 (3) Next, the graft portion 1+2 In the presence of [unclear], the graft section 3 is superimposed to form a three-stage graft section. 1+2+3 (4) After performing the same procedure below, the graft portion 1+2+···+(n-1) In the presence of the graft n Polymerize to form a multi-stage polymerized graft section 1+2+···+n To obtain.

[0124] If the graft portion consists of multiple types of graft portions, polymer fine particles (A) may be produced by polymerizing the graft portion having multiple types of graft portions and then graft polymerizing those graft portions onto an elastic body. Alternatively, polymer fine particles (A) may be produced by sequentially graft polymerizing multiple types of polymers constituting the graft portion onto an elastic body in the presence of an elastic body.

[0125] (Method for producing surface crosslinked polymers) Surface crosslinked polymers can be formed by polymerizing monomers used to form the surface crosslinked polymer by known radical polymerization in the presence of any polymer (e.g., an elastic material). When the elastic material is obtained as an aqueous suspension, polymerization of the surface crosslinked polymer is preferably carried out by emulsion polymerization.

[0126] When employing emulsion polymerization as a method for producing polymer microparticles (A), known emulsifiers (dispersants) can be used as emulsifiers (dispersants) for producing polymer microparticles (A). Preferably, the emulsifier is one having a polyoxyethylene group. Emulsifiers having a polyoxyethylene group will be described in detail in section (2-4. Emulsifiers) below. By using an emulsifier having a polyoxyethylene group as the emulsifier in the production of polymer microparticles (A) by emulsion polymerization, the following advantages are obtained: (i) a latex suitable for use in the first production method can be easily obtained, and (ii) the environmental impact can be reduced.

[0127] When emulsion polymerization is used as a method for producing polymer microparticles (A), a thermal decomposition initiator can be used for the production of polymer microparticles (A). Examples of known thermal decomposition initiators include (i) 2,2'-azobisisobutyronitrile and (ii) peroxides such as organic peroxides and inorganic peroxides. Examples of organic peroxides include t-butyl peroxyisopropyl carbonate, paramentane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, and t-hexyl peroxide. Examples of inorganic peroxides include hydrogen peroxide, potassium persulfate, and ammonium persulfate.

[0128] A redox-type initiator can also be used in the production of polymer microparticles (A). The redox-type initiator is an initiator comprising (i) a peroxide such as an organic peroxide or an inorganic peroxide, and (ii) a reducing agent such as a transition metal salt such as iron(II) sulfate, sodium formaldehyde sulfoxylate, and glucose. A chelating agent such as disodium ethylenediaminetetraacetate may be used in addition as needed, and a phosphorus-containing compound such as sodium pyrophosphate may be used in addition as needed.

[0129] When a redox-type initiator is used, polymerization can be carried out even at low temperatures in which the peroxide does not substantially decompose thermally, allowing the polymerization temperature to be set over a wide range. For this reason, it is preferable to use a redox-type initiator. Among redox-type initiators, those using organic peroxides such as cumene hydroperoxide, dicumyl peroxide, paramenthane hydroperoxide, and t-butyl hydroperoxide as peroxides are preferred. The amount of the initiator used, and the amounts of the reducing agent, transition metal salt, and chelating agent used when a redox-type initiator is used, can be used within known ranges.

[0130] When using polyfunctional monomers in the polymerization of an elastic body, graft portion, or surface crosslinked polymer for the purpose of introducing a crosslinked structure into the elastic body, graft portion, or surface crosslinked polymer, known chain transfer agents can be used within known usage amounts. By using chain transfer agents, the molecular weight and / or degree of crosslinking of the resulting elastic body, graft portion, or surface crosslinked polymer can be easily adjusted.

[0131] In addition to the components described above, surfactants can also be used in the production of polymer microparticles (A). The type and amount of the surfactant used are within a known range.

[0132] In the production of polymer fine particles (A), the polymerization temperature, pressure, and deoxygenation conditions can be appropriately applied from known numerical ranges.

[0133] The method for producing polymer microparticles (A) described above can be used to obtain latex containing polymer microparticles (A) and an emulsifier. In other words, the description in section (2-3. Method for producing polymer microparticles (A)) can be used as a description of a method for producing latex.

[0134] (1-2-4. Emulsifiers) The emulsifier contained in the latex contains a lipophilic portion and a hydrophilic portion, the hydrophilic portion having a polyoxyethylene group. In this specification, "an emulsifier containing a lipophilic portion and a hydrophilic portion, the hydrophilic portion having a polyoxyethylene group" may also be simply referred to as "an emulsifier having a polyoxyethylene group." The origin of the polyoxyethylene group emulsifier contained in the latex is not particularly limited. If the latex is a latex obtained by emulsion polymerization of polymer fine particles (A), the polyoxyethylene group emulsifier contained in the latex may originate from the emulsifier used in the production of the polymer fine particles (A).

[0135] Lipophilic sites are sites with a chemical structure that has high affinity for organic solvents. Since the particle surface of polymer microparticles (A) has many hydrophobic parts, lipophilic sites also have high affinity for polymer microparticles (A). Examples of lipophilic sites include sites having aliphatic groups and aromatic groups. Among these, from the viewpoint of availability, it is preferable that lipophilic sites are sites having aliphatic groups. The aliphatic groups constituting the lipophilic sites may be linear or cyclic, and may be saturated or unsaturated. If the aliphatic group is linear, it may be linear or branched. Examples of linear aliphatic groups include alkyl groups and alkenyl groups having 2 to 20 carbon atoms. Examples of cyclic aliphatic groups include cycloalkyl groups having 3 to 10 carbon atoms. Hydrogen atoms bonded to linear aliphatic groups may be substituted with one or more substituents. Examples of such substituents include halogen atoms.

[0136] The hydrophilic portion is a portion having a chemical structure with high affinity for water, and has a polyoxyethylene group (-CH2-CH2-O-). From the viewpoint of stability in emulsion polymerization, the number of moles of ethylene oxide added (n in the structural formula shown below) of the polyoxyethylene group is preferably 1 to 15, more preferably 1 to 10, even more preferably 2 to 10, and particularly preferably 4 to 10.

[0137] [ka] As the emulsifier having a polyoxyethylene group, emulsifiers containing a sulfate ester moiety as the hydrophilic portion (hereinafter, emulsifiers containing a sulfate ester moiety as the hydrophilic portion are also referred to as "sulfur-based emulsifiers") or emulsifiers containing a phosphate ester moiety as the hydrophilic portion (hereinafter, emulsifiers containing a phosphate ester moiety as the hydrophilic portion are also referred to as "phosphorus-based emulsifiers") are preferred. From the viewpoint of ease of purification of polymer fine particles (A), sulfur-based emulsifiers containing a sulfate ester moiety as the hydrophilic portion are more preferred. Furthermore, from the viewpoint of low environmental impact, phosphorus emulsifiers containing a phosphate ester moiety are more preferred. Specific examples of phosphorus-based emulsifiers having polyoxyethylene groups and phosphate ester moieties as hydrophilic portions include polyoxyethylene alkyl ether phosphate, polyoxyethylene alkyl ether sodium phosphate, and polyoxyethylene alkyl ether potassium phosphate. These emulsifiers having polyoxyethylene groups may be used individually or in combination of two or more.

[0138] (1-2-5. Amount of polymer microparticles (A) and amount of emulsifier) The amount of polymer fine particles (A) in the latex is not particularly limited, and should be an amount that allows the polymer fine particles (A) to be stably dispersed in the latex and to form aggregates in the aqueous phase in the slow aggregation step described later. From the viewpoint of efficiently producing purified polymer fine particles (A), the amount of polymer fine particles (A) in the latex is preferably 10% to 50% by weight, more preferably 15% to 50% by weight, even more preferably 25% to 50% by weight, and particularly preferably 30% to 50% by weight, based on 100% by weight of the latex. When the amount of polymer fine particles (A) in the latex is within the above range, purified polymer fine particles (A) can be produced efficiently.

[0139] The amount of emulsifier in the latex is not particularly limited, but it is preferable to use as little as possible without impairing the emulsification stability of the polymer fine particles (A).

[0140] (1-2-6. Organic solvents (B)) The organic solvent (B) is not particularly limited, but it is preferably an organic solvent that is partially soluble in water. In this specification, "an organic solvent that is partially soluble in water" means an organic solvent whose solubility in water at 20°C is 5% to 40% by weight. The solubility of the organic solvent (B) at 20°C in water at 20°C is preferably 5% to 40% by weight, and more preferably 5% to 30% by weight. When the solubility of the organic solvent (B) at 20°C in water at 20°C is 40% by weight or less, the polymer fine particles (A) do not substantially solidify and precipitate in the organic solvent (B) when the latex containing polymer fine particles (A) and an emulsifier is mixed with the organic solvent (B). Therefore, it has the advantage that the mixing operation can be carried out smoothly. When the solubility of the organic solvent (B) at 20°C in water at 20°C is 5% by weight or more, the organic solvent (B) has sufficient miscibility with the latex containing polymer fine particles (A) and an emulsifier. Therefore, it has the advantage of allowing for smooth mixing operations. In other words, if the organic solvent (B) is an organic solvent that is partially soluble in water, it has the advantage of allowing for smooth mixing operations between the polymer microparticles (A) and the latex containing the emulsifier and the organic solvent (B).

[0141] The organic solvent (B) is preferably an organic solvent that, when mixed with the polymer microparticles (A) and the latex containing the emulsifier, allows mixing to be achieved without the polymer microparticles (A) substantially coagulating and precipitating in the organic solvent (B). This configuration has the advantage of allowing the mixing operation between the polymer microparticles (A) and the latex containing the emulsifier and the organic solvent (B) to be carried out smoothly.

[0142] Specific examples of organic solvent (B) include one or more organic solvents selected from the group consisting of esters (e.g., methyl acetate, ethyl acetate, propyl acetate, butyl acetate, etc.), ketones (e.g., acetone, methyl ethyl ketone, diethyl ketone, methyl isobutyl ketone, etc.), alcohols (e.g., ethanol, propanol, isopropanol, butanol, etc.), ethers (e.g., tetrahydrofuran, tetrahydropyran, dioxane, diethyl ether, etc.), aromatic hydrocarbons (e.g., benzene, toluene, xylene, etc.), and halogenated hydrocarbons (e.g., methylene chloride, chloroform, etc.), or mixtures thereof. Methyl ethyl ketone has high affinity for organic solvent (C) and resin (D) described later, and is readily available. Therefore, organic solvent (B) preferably contains 50% or more by weight of methyl ethyl ketone, more preferably 75% or more by weight, and particularly preferably 85% or more by weight.

[0143] (1-2-7. Organic solvent mixing step) The organic solvent mixing step is a step of mixing latex containing polymer microparticles (A) and an emulsifier with an organic solvent (B). The organic solvent mixing step can also be described as simply combining latex containing polymer microparticles (A) and an emulsifier with the organic solvent (B). In this specification, the organic solvent mixing step does not include a step of letting the mixture obtained by combining the latex and the organic solvent (B) stand for 5 minutes or more, nor does it include a step of stirring the mixture for 5 minutes or more. In other words, in this specification, the organic solvent mixing step may include a step of letting the mixture obtained by combining the latex and the organic solvent (B) stand for less than 5 minutes, and / or a step of stirring the mixture for less than 5 minutes.

[0144] No special apparatus or method is required for mixing the latex and organic solvent (B); any known apparatus or method that can achieve a good mixture can be used. If standing is required after the organic solvent mixing step, common apparatuses include a stirring tank with agitators. If stirring is required after the organic solvent mixing step, common apparatuses include a stirring tank with agitators, a static mixer, and a line mixer (a system in which a stirring device is incorporated into a part of the piping).

[0145] When using a stirring tank with a stirring blade in the organic solvent mixing step, (i) after putting the latex into the stirring tank, the organic solvent (B) may be added to the latex while stirring the latex; (ii) after putting the organic solvent (B) into the stirring tank, the latex may be added to the organic solvent (B) while stirring the organic solvent (B); or (iii) the latex and organic solvent (B) may be added together (simultaneously) to an empty stirring tank while stirring the mixture in the tank.

[0146] The preferred amount of organic solvent (B) used in the organic solvent mixing step varies depending on the amount of polymer fine particles (A) in the latex and the type of polymer fine particles (A), and is not particularly limited. In one embodiment, the amount of organic solvent (B) used in the organic solvent mixing step is preferably 50 to 400 parts by weight, more preferably 70 to 300 parts by weight, more preferably 70 to 200 parts by weight, more preferably 70 to 150 parts by weight, more preferably 70 to 140 parts by weight, more preferably 70 to 130 parts by weight, even more preferably 70 to 120 parts by weight, and particularly preferably 70 to 110 parts by weight, per 100 parts by weight of latex. When the amount of organic solvent (B) used in the organic solvent mixing step is 50 parts by weight or more, it has the advantages that (i) the polymer fine particles (A) can be stably dispersed in the organic solvent (B), and (ii) the mixture of latex and organic solvent (B) tends to have low viscosity and be easy to handle. Furthermore, if the amount of organic solvent (B) used in the organic solvent mixing process is 400 parts by weight or less, it has the advantage that the organic solvent (B) can be efficiently removed in the production of the resin composition described later.

[0147] The temperature of the latex and organic solvent (B) subjected to the organic solvent mixing step is not particularly limited, as long as it is a temperature at which the latex and organic solvent (B) can be uniformly mixed.

[0148] (1-2-8. Mixing state maintenance process) The mixing state maintenance step is a step in which the mixture obtained in the organic solvent mixing step is either left to stand, stirred, or both. The mixing state maintenance step can also be described as a step in which the emulsifier having polyoxyethylene groups is dissociated from the polymer microparticles (A) and the polymer microparticles (A) are moved into the organic solvent (B) by leaving the mixture of latex and organic solvent (B) to stand, stirring, or both.

[0149] In the mixing state maintenance step, it is preferable to either let the mixture stand and / or stir it until the viscosity of the mixture obtained in the organic solvent mixing step becomes constant.

[0150] The inventors have made the following new findings regarding the viscosity of a mixture of latex and an organic solvent (B). When latex containing polymer microparticles (A) and linear alkylbenzene is mixed with an organic solvent (B), the viscosity of the mixture remains constant from immediately after mixing until a certain period of time has elapsed, and does not change. This is presumed to be because, when the latex contains linear alkylbenzene, almost the entire amount of polymer microparticles (A) in the latex moves into the organic solvent (B) immediately after mixing with the organic solvent (B), but one embodiment of the present invention is not limited to this presumption. On the other hand, when latex containing polymer microparticles (A) and a phosphorus-based emulsifier having a polyoxyethylene group is mixed with an organic solvent (B), the viscosity of the mixture increases from immediately after mixing until it becomes constant after standing and / or stirring for a predetermined period of time, and eventually stops changing completely (saturates).

[0151] In this specification, "viscosity becomes constant" means the viscosity of the mixture at a certain point in time (V t1 ) and V t1 The viscosity (V) of the mixture after standing and / or stirring for 5 minutes from that point. t2 ) difference (V t2 -V t1 The absolute value of ) is divided by the difference (V1-V0) between the viscosity at the start of mixing (0 mins) (V0) and the viscosity at saturation (V1) where the viscosity no longer changes completely, and then multiplied by 100 to obtain the value (%) (|(V t2 -V t1 This means that (V1-V0) × 100 is 10% or less. In other words, it does not mean that the viscosity difference is strictly constant (0). Therefore, in the mixing state maintenance step, "to allow the mixture to stand and / or stir it until the viscosity of the mixture becomes constant" can also be said to mean to allow the mixture to stand and / or stir it until the viscosity of the mixture obtained in the organic solvent mixing step becomes approximately constant.

[0152] By allowing the mixture to stand and / or stirring until its viscosity becomes constant, the emulsifier having polyoxyethylene groups can be sufficiently dissociated from the polymer fine particles (A), and the polymer fine particles (A) can be sufficiently moved into the organic solvent (B). As a result, the amount of polymer fine particles (A) mixed into the aqueous phase (discharge liquid) separated and removed in the separation step described later can be significantly reduced. The change in viscosity of the mixture when it contains an emulsifier having polyoxyethylene groups is presumed to be due to the slow dissociation rate between the polymer fine particles (A) and the emulsifier having polyoxyethylene groups, but one embodiment of the present invention is not limited to this presumption.

[0153] In the mixing state maintenance step, the viscosity change of the mixture of latex and organic solvent (B) may be monitored while the mixture is allowed to stand and / or stirred. Various methods can be used to monitor the viscosity change of the mixture, and are not particularly limited, but for example, the mixture can be sampled at any time while it is standing and / or stirred, and the viscosity of the obtained sample can be measured with a viscometer. The method for measuring the viscosity of the mixture with a viscometer will be described in detail in the following examples.

[0154] In one embodiment, a mixture of 100 parts by weight of latex (solid content concentration of polymer fine particles (A) in 100% by weight of latex: 10-50% by weight) and 50 to 400 parts by weight of an organic solvent (B) is left to stand in a tank for 30 minutes or more until the viscosity of the mixture becomes constant.

[0155] In another embodiment, a mixture of 100 parts by weight of latex (solid content concentration of polymer fine particles (A) in 100% by weight of latex: 10-50% by weight) and 50 to 400 parts by weight of an organic solvent (B) is stirred in a stirring tank equipped with a stirring blade at a stirring speed of 10 rpm to 5000 rpm for a stirring time of 10 minutes or more until the viscosity of the mixture becomes constant.

[0156] In the mixing state maintenance step, the time required for the mixture to stand varies depending on the type of polymer fine particles (A), the emulsifier having polyoxyethylene groups, and the organic solvent (B), the amount (concentration) of polymer fine particles (A) in the mixture, and the concentration of the emulsifier having polyoxyethylene groups in the mixture, and is not particularly limited. In one embodiment, the time required for the mixture to stand in the mixing state maintenance step is preferably 30 minutes or more, more preferably 45 minutes or more, even more preferably 60 minutes or more, and particularly preferably 120 minutes or more. By standing the mixture for 30 minutes or more, the emulsifier having polyoxyethylene groups can be sufficiently dissociated from the polymer fine particles (A), and the polymer fine particles (A) can be sufficiently moved into the organic solvent (B). As a result, the amount of polymer fine particles (A) mixed into the aqueous phase (discharge liquid) separated and removed in the separation step described later can be significantly reduced. There is no particular upper limit to the time required for the mixture to stand in the mixing state maintenance step, but from the viewpoint of efficiency, it is preferably 5 hours or less, and more preferably 2 hours or less.

[0157] In the mixing state maintenance step, the preferred temperature of the mixture is not particularly limited and depends on the type of polymer fine particles (A), the emulsifier having polyoxyethylene groups, and the organic solvent (B), the solid content concentration of polymer fine particles (A) in the mixture, the concentration of the emulsifier having polyoxyethylene groups in the mixture, etc. In one embodiment, the temperature of the mixture when subjected to the mixing state maintenance step is preferably, for example, 10°C to 50°C, more preferably 15°C to 40°C, and even more preferably 20°C to 40°C. When the temperature of the mixture when subjected to the mixing state maintenance step and / or the temperature of the mixture obtained by the mixing state maintenance step is within the above range, there is an advantage that the emulsifier having polyoxyethylene groups can be sufficiently dissociated from the polymer fine particles (A). Note that "the temperature of the mixture obtained by the mixing state maintenance step" can also be said to be "the temperature of the mixture after the mixing state maintenance step".

[0158] The mixing state maintenance step may be performed in the same apparatus used for the organic solvent mixing step (e.g., a stirring tank, static mixer, line mixer, etc.), or it may be performed in an apparatus different from the one used for the organic solvent mixing step.

[0159] (1-2-9. Slow agglomeration process) The first manufacturing method may further include a slow aggregation step after the mixing state maintenance step. The slow aggregation step is a step in which the mixture obtained through the mixing state maintenance step is brought into contact with water to generate aggregates of polymer fine particles (A) containing an organic solvent (B) in the aqueous phase. The slow aggregation step can also be described as a step in which impurities such as water and emulsifiers are transferred from the mixture of latex and organic solvent (B) into the aqueous phase.

[0160] By bringing the mixture, which has undergone a mixing state maintenance step, into contact with water, a portion of the organic solvent (B) contained in the mixture dissolves in the water, forming an aqueous phase. At the same time, impurities such as water derived from latex and emulsifiers contained in the mixture are also removed into the aqueous phase. As a result, the mixture becomes a form in which polymer fine particles (A) are concentrated in the organic solvent (B) containing water, and consequently forms aggregates.

[0161] The slow agglomeration process is preferably carried out under stirring or flow conditions that can impart fluidity equivalent to stirring, from the viewpoint of preventing the partial generation of unaggregated polymer fine particles (A). The slow agglomeration process can be carried out, for example, by batch or continuous operation in a stirring tank equipped with a stirrer.

[0162] The method of bringing the mixture into contact with water is not particularly limited as long as the mixture and water come into contact. For example, (i) water can be added to the mixture by (i-1) continuously adding a fixed amount, (i-2) adding it in installments, and (i-3) adding it all at once, and (ii) the mixture can be added to the water by (ii-1) continuously adding a fixed amount, (ii-2) adding it in installments, and (ii-3) adding it all at once.

[0163] From the viewpoint of efficiently generating aggregates, it is preferable to continuously supply the mixture and water to a device equipped with a stirring function to bring them into contact, thereby continuously obtaining aggregates and an aqueous phase. The shape of the stirring blades and the device for stirring is not particularly limited. In one embodiment, since aggregates generally float relative to the aqueous phase, it is preferable to supply the mixture and water from the bottom of the stirring tank and extract the aggregates and aqueous phase from the top of the stirring tank. Here, the bottom of the device means a position less than 1 / 3 of the way from the bottom to the liquid surface, and the top of the device means a position more than 2 / 3 of the way from the bottom to the liquid surface. By making the slow aggregation process continuous, it is possible to reduce equipment costs by miniaturizing the device and improve productivity.

[0164] The amount of water brought into contact with the mixture in the loose aggregation step may vary depending on the type of polymer fine particles (A), the solid content concentration of the polymer fine particles (A) in the latex, and the type and amount of organic solvent (B). However, the amount of water is preferably 40 to 350 parts by weight, and more preferably 60 to 250 parts by weight, per 100 parts by weight of the organic solvent (B) used in the organic solvent mixing step. When the amount of water is 40 parts by weight or more, it has the advantage that aggregates of polymer fine particles (A) are more easily formed. Furthermore, when the amount of water is 350 parts by weight or less, the concentration of organic solvent (B) in the formed aggregates is within a suitable range, which has the advantage that the aggregates are easier to redisperse in organic solvent (C) in the redispersion step described later.

[0165] The preferred temperatures of the mixture and water when subjected to the slow flocculation process vary depending on the type of polymer fine particles (A), emulsifier, and organic solvent (B), the concentration of polymer fine particles (A) and emulsifier in the mixture, and are not particularly limited. In one embodiment, the temperature of the mixture and water when subjected to the slow flocculation process, and / or the temperature of the aggregates and aqueous phase obtained by the slow flocculation process, are preferably, for example, 10°C to 50°C, more preferably 15°C to 40°C, and even more preferably 20°C to 40°C. When the temperature of the mixture and water when subjected to the slow flocculation process, and / or the temperature of the aggregates and aqueous phase obtained by the slow flocculation process are within the above range, the flocculation state is good, and the organic solvent used is less likely to volatilize, which is an advantage.

[0166] (1-2-10. Separation process) The first manufacturing method may further include a separation step after the slow agglomeration step, in which the aggregates generated in the slow agglomeration step are separated from the aqueous phase. By separating the aggregates generated in the slow agglomeration step from the aqueous phase, water contained in the organic solvent (B) accompanying the aggregates can be removed, and most of the latex-derived impurities (such as emulsifiers and electrolytes) can be separated and removed from the polymer microparticles (A) together with the aqueous phase. This makes it possible to obtain aggregates of polymer microparticles (A) from which most of the impurities have been separated and removed (i.e., purified polymer microparticles (A)).

[0167] The method for separating aggregates from the aqueous phase is not particularly limited. Examples include common filtration methods such as filtration using filter paper, filter cloth, or a metal screen with a relatively coarse mesh.

[0168] The amount of polymer fine particles (A) contained in the aqueous phase separated and removed in the separation process is preferably 5% by weight or less, more preferably 3% by weight or less, even more preferably 2% by weight or less, and particularly preferably 1% by weight or less, with the most preferable being that polymer fine particles (A) are substantially not present in the aqueous phase.

[0169] Furthermore, the permeability of the aqueous phase separated and removed in the separation process is preferably 5% or more, more preferably 10% or more, even more preferably 15% or more, even more preferably 20% or more, and particularly preferably 30% or more. If the permeability of the aqueous phase is 5% or more, it can be said that the aqueous phase has good permeability. Also, in many cases, no turbidity is observed visually in an aqueous phase with a permeability of 30% or more. The method for measuring the permeability of the aqueous phase will be described in detail in the examples below.

[0170] The preferred temperatures for the aggregates and aqueous phase when subjected to the separation process are the same as the preferred temperatures for the aggregates and aqueous phase obtained by the slow aggregation process, as described in section (1-2-9. Slow Aggregation Process) above.

[0171] (1-2-11. Washing process) The first manufacturing method may further include, after the separation step, a step (also referred to as the washing step) of repeating one or more cycles selected from (i) and (ii) below.

[0172] (i) A first cycle comprising: a first step of adding the organic solvent (B) to the aggregate obtained in the separation step; a second step of contacting the mixture obtained in the first step with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in an aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase, (ii) A second cycle comprising: a first step of adding water to the aggregates obtained in the separation step; a second step of contacting the mixture obtained in the first step with the organic solvent (B) to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregates obtained in the second step from the aqueous phase.

[0173] The first manufacturing method is a method using an organic solvent (B) to obtain purified polymer microparticles (A) from latex containing polymer microparticles (A). In the first manufacturing method, the aggregates of polymer microparticles (A) obtained in the separation step are loose aggregates that are reversible with respect to the coalescing dispersion of particles. The term "loose aggregates" will be explained in detail in the section [1-3. Aggregates of Polymer Microparticles (A)] below. The aggregates obtained in the separation step (i.e., loose aggregates) are, for example, lumps with a size of several centimeters or more. The aggregates obtained in the separation step (i.e., loose aggregates) have the properties of (i) being prone to forming smaller lumps in water (but still lumps of a size that can be seen with the naked eye), and (ii) being prone to forming very small lumps in organic solvents (lumps that cannot be seen with the naked eye), and / or being prone to the polymer microparticles (A) contained in the aggregates being easily dispersed again as primary particles. Therefore, by performing the washing step of adding water or an organic solvent to the aggregates, it is possible to efficiently wash and remove impurities inside the aggregates.

[0174] Specifically, in the first cycle of the washing process, by adding an organic solvent (B) to the aggregates, aggregates that are, for example, several centimeters or larger in size become very fine clumps (clumps too small to be seen with the naked eye), and / or at least a portion of the polymer microparticles (A) contained in the aggregates are redispersed as primary particles. At this time, impurities inside the aggregates are released into the organic solvent (B) (first step of the first cycle). Subsequently, by bringing the mixture obtained in the first step of the first cycle into contact with water, the polymer microparticles (A) aggregate, and aggregates that are, for example, several centimeters or larger in size are regenerated (second step of the first cycle). The amount of impurities inside the aggregates can be reduced before and after performing the first and second steps of the first cycle.

[0175] Furthermore, in the second cycle of the washing process, by adding water to the aggregates, aggregates that are, for example, several centimeters or larger in size become smaller clumps (but still clumps that are visible to the naked eye). At this time, impurities inside the aggregates are released into the water (first step of the second cycle). Subsequently, by bringing the mixture into contact with the organic solvent (B) in the first step of the second cycle, the smaller clumps aggregate, and larger aggregates (for example, several centimeters or larger) are regenerated (second step of the second cycle). The amount of impurities inside the aggregates can be reduced before and after performing the first and second steps of the second cycle.

[0176] As described above, the aggregates obtained after the washing process have a reduced impurity content compared to the aggregates obtained before the washing process. Furthermore, since the aggregates obtained after the washing process are loose aggregates, they can reversibly (i) return to primary polymer fine particles (A) or form finer clumps, and agglomerate or form larger clumps. Therefore, by repeating the washing process, the impurity content of the aggregates can be further reduced.

[0177] Furthermore, aggregates obtained by general methods for agglomerating polymer microparticles (A) without using organic solvents (for example, methods using coagulants) are irreversible with respect to the coalescing dispersion of polymer microparticles. Therefore, it is difficult to reduce or increase the size of aggregates of polymer microparticles obtained by agglomeration through subsequent operations (for example, the addition of water or organic solvents). Consequently, even if water or organic solvents are added to the aggregates, only the surface of the aggregates is cleaned, and it is not easy to clean and remove impurities from inside the aggregates.

[0178] In the washing process, productivity can be increased by repeating one or more cycles selected from the first and second cycles. For example, to reduce the amount of impurities such as emulsifiers (e.g., the content of elements P and S derived from emulsifiers) in the ultimately obtained purified polymer microparticles (A), one could consider increasing the amount of organic solvent (B) used in the organic solvent mixing step and the amount of water used in the slow aggregation step. However, such a method would require reducing the amount of polymer microparticles (A) produced, such as by reducing the amount of monomers used in the manufacture of polymer microparticles (A), due to the limitations of the container capacity. On the other hand, when the washing process described above is performed, the amount of impurities such as emulsifiers in the ultimately obtained purified polymer microparticles (A) can be reduced without increasing the amount of organic solvent (B) used in the organic solvent mixing step and the amount of water used in the slow aggregation step, that is, without reducing the amount of polymer microparticles (A) produced. In other words, by performing the washing process, aggregates of polymer microparticles (A) (i.e., purified polymer microparticles (A)) with an even lower content of impurities such as emulsifiers, more specifically, elements P and S derived from emulsifiers, can be efficiently produced.

[0179] The number of cycles by which the cycle selected from the first cycle and the second cycle is repeated is not particularly limited, and the more cycles there are, the more the amount of impurities contained in the aggregate can be reduced. From the viewpoint of obtaining aggregates with an extremely low impurity content, it is more preferable to repeat the cycle selected from the first cycle and the second cycle two or more times in the washing process, even more preferable to repeat it three or more times, and particularly preferable to repeat it four or more times. When the cycle selected from the first cycle and the second cycle is repeated two or more times in the washing process, (i) the first cycle may be performed two or more times and the second cycle may not be performed, (ii) the second cycle may be performed two or more times and the first cycle may not be performed, or (iii) the first cycle and the second cycle may each be performed one or more times.

[0180] (First step of the first cycle) The first step of the first cycle is to add an organic solvent (B) to the aggregates separated from the aqueous phase. This step causes the aggregates to break down into very fine clumps (clumps too small to be seen with the naked eye), and / or at least some of the polymer microparticles (A) contained in the aggregates to be redispersed as primary particles, and impurities inside the aggregates to be released into the organic solvent (B). The apparatus and method for adding the organic solvent (B) to the aggregates separated from the aqueous phase are those described in section (1-2-7. Organic Solvent Mixing Step).

[0181] The preferred amount of organic solvent (B) to be added to the aggregate in the first step of the first cycle varies depending on the amount of polymer fine particles (A) in the aggregate and the type of polymer fine particles (A), and is not particularly limited. In one embodiment, the amount of organic solvent (B) to be added to the aggregate in the first step of the first cycle is preferably 1 to 400 parts by weight, more preferably 1 to 300 parts by weight, and even more preferably 10 to 100 parts by weight, per 100 parts by weight of the aggregate. When the amount of organic solvent (B) added to the aggregate in the first step of the first cycle is 1 part by weight or more, it has the advantages that (i) the polymer fine particles (A) can be stably dispersed in the organic solvent (B), and (ii) the mixture of the aggregate and the organic solvent (B) tends to have low viscosity and be easy to handle. Furthermore, when the amount of organic solvent (B) added to the aggregate in the first step of the first cycle is 400 parts by weight or less, it has the advantage that the amount of water added in the second step of the first cycle can be reduced.

[0182] The temperature of the aggregate and organic solvent (B) used in the first step of the first cycle is not particularly limited, as long as it is a temperature at which the aggregate and organic solvent (B) can be uniformly mixed.

[0183] (Second step of the first cycle) The second step of the first cycle is to bring the mixture obtained in the first step of the first cycle into contact with water. This step regenerates aggregates of polymer fine particles (A) containing an organic solvent (B) (for example, aggregates with a size of several centimeters or more) into the newly formed aqueous phase. This step can also be described as a step in which impurities such as water and emulsifiers are transferred from the mixture of aggregates and organic solvent (B) into the aqueous phase.

[0184] The preferred amount of water to be added to the aggregate in the second step of the first cycle varies depending on the amount and type of polymer microparticles (A) in the aggregate, and is not particularly limited. In one embodiment, the amount of water added to the aggregate in the second step of the first cycle is preferably 50 to 500 parts by weight, more preferably 50 to 400 parts by weight, and even more preferably 50 to 300 parts by weight, per 100 parts by weight of the aggregate. When the amount of water added to the aggregate in the second step of the first cycle is 50 parts by weight or more, it has the advantage of reducing the amount of impurities such as emulsifiers (for example, the content of elements P and S derived from emulsifiers) in the ultimately obtained purified polymer microparticles (A). Also, when the amount of water added to the aggregate in the second step of the first cycle is 500 parts by weight or less, it has the advantage of reducing the amount of organic solvent (B) added in the first step of the first cycle. The temperature of the aggregate and water used in the second step of the first cycle is not particularly limited.

[0185] (Third step of the first cycle) The third step of the first cycle is the separation of the aggregates obtained in the second step of the first cycle from the aqueous phase. This step can be carried out in the same manner as the separation step. The apparatus and method for carrying out this step, as well as the preferred conditions for carrying out this step, are as described in section (1-2-10. Separation Step) above.

[0186] (First step of the second cycle) The first step of the second cycle is to add water to the aggregates separated from the aqueous phase. This step causes the aggregates to break down into smaller clumps (but still large enough to be visible to the naked eye), and also releases impurities from within the aggregates into the water.

[0187] The method of adding water to the aggregate is not particularly limited. For example, methods such as continuously adding water to the aggregate or adding water all at once can be applied.

[0188] The apparatus for adding water to the aggregate is not particularly limited. For example, a stirring tank with agitators can be used.

[0189] When using a stirring tank with an agitator in the first step of the second cycle, (i) after placing the aggregate in the stirring tank, water may be added to the aggregate while stirring the aggregate; (ii) after placing the water in the stirring tank, the aggregate may be added to the water while stirring the water; or (iii) the aggregate and water may be added together (simultaneously) to an empty stirring tank while stirring the mixture in the tank.

[0190] The preferred amount of water to be added to the aggregate in the first step of the second cycle varies depending on the amount and type of polymer microparticles (A) in the aggregate, and is not particularly limited. In one embodiment, the amount of water added to the aggregate in the first step of the second cycle is preferably 50 to 500 parts by weight, more preferably 50 to 400 parts by weight, and even more preferably 50 to 300 parts by weight, per 100 parts by weight of the aggregate. When the amount of water added to the aggregate in the first step of the second cycle is 50 parts by weight or more, it has the advantage of reducing the amount of impurities such as emulsifiers (for example, the content of elements P and S derived from emulsifiers) in the ultimately obtained purified polymer microparticles (A). Furthermore, when the amount of water added to the aggregate in the first step of the second cycle is 500 parts by weight or less, it has the advantage of reducing the amount of organic solvent added in the second step of the second cycle. The temperature of the aggregate and water used in the first step of the second cycle is not particularly limited.

[0191] (Second step of the second cycle) The second step of the second cycle is to bring the mixture obtained in the first step of the second cycle into contact with an organic solvent (B). This step causes the fine clumps in the mixture to aggregate, regenerating aggregates of a larger size (e.g., several centimeters or larger).

[0192] The method of bringing the mixture into contact with the organic solvent (B) is not particularly limited. For example, methods such as continuously adding the organic solvent (B) to the mixture, or adding the organic solvent (B) all at once, can be applied.

[0193] The apparatus for adding the organic solvent (B) to the mixture is not particularly limited. For example, the apparatus used in the first step of the second cycle (e.g., a stirred tank with agitators) can be used as is.

[0194] The preferred amount of organic solvent (B) to be added to the mixture in the second step of the second cycle varies depending on the type of polymer fine particles (A), the amount of polymer fine particles (A) in the mixture, and the amount of water in the mixture, and is not particularly limited. In one embodiment, the amount of organic solvent (B) to be added to the mixture in the second step of the second cycle is preferably 1 to 400 parts by weight, more preferably 1 to 300 parts by weight, and even more preferably 1 to 10 parts by weight, relative to 100 parts by weight of water added in the first step of the second cycle. When the amount of organic solvent (B) is 1 part by weight or more, it has the advantage that aggregates of polymer fine particles (A) are more easily formed. Also, when the amount of organic solvent (B) is 400 parts by weight or less, the concentration of organic solvent (B) in the formed aggregates is within a suitable range, and it has the advantage that the aggregates are more easily redispersed in organic solvent (C) in the redispersion step described later.

[0195] The preferred temperature of the mixture and organic solvent (B) when subjected to the second step of the second cycle varies depending on the type of polymer fine particles (A), emulsifier and organic solvent (B), the concentration of polymer fine particles (A) and emulsifier in the mixture, and is not particularly limited. In one embodiment, the temperature of the mixture and organic solvent (B) when subjected to the second step of the second cycle, and / or the temperature of the aggregate and aqueous phase obtained by the second step of the second cycle, is preferably, for example, 10°C to 50°C, more preferably 15°C to 40°C, and even more preferably 20°C to 40°C. When the temperature of the mixture and organic solvent (B) when subjected to the second step of the second cycle, and / or the temperature of the aggregate and aqueous phase obtained by the second step of the second cycle are within the above range, the aggregation state is good, and the organic solvent used is less likely to volatilize, which is an advantage.

[0196] (Third step of the second cycle) The third step of the second cycle is the separation of the aggregates obtained in the second step of the second cycle from the aqueous phase. This step can be carried out in the same manner as the separation step. The apparatus and method for carrying out this step, as well as the preferred conditions for carrying out this step, are as described in section (1-2-10. Separation Step) above.

[0197] [1-3. Aggregates of polymer microparticles (A)] The aggregates of polymer fine particles (A) obtained by the first manufacturing method have the following characteristics.

[0198] (i) Method A is a general method for agglomerating polymer microparticles (A), such as using a coagulant or heating latex. In Method A, most of the impurities (emulsifiers and electrolytes, etc.) originating from the production of latex and the agglomeration of polymer microparticles (A) are often adsorbed on the surface of the aggregates or contained within the aggregates. Therefore, in Method A, it is not easy to remove these impurities from the aggregates, even when washing them with water. In contrast, in the first manufacturing method, all or most of the impurities originating from the production of latex and the agglomeration of polymer microparticles (A) are released from the aggregates and migrate to the aqueous phase. Therefore, in the first manufacturing method, these impurities can be easily removed from the aggregates.

[0199] (ii) The aggregates obtained by method A are strong aggregates that are difficult to redisperse from the aggregates to the primary particle state of polymer fine particles (A) even by mechanical shearing. In contrast, the aggregates obtained by the first manufacturing method can be redispersed as primary particles, for example, by mixing them with an organic solvent (C) that has affinity for polymer fine particles (A) under stirring. That is, the aggregates obtained by the first manufacturing method are reversible in organic solvents with respect to the coalential dispersion of particles. In this specification, such "reversible aggregates" are referred to as "loose aggregates".

[0200] When aggregates obtained by the separation or washing step are subjected to the redispersion step and resin mixing step described later, the amount of organic solvent (B) contained in the aggregates is preferably 30% by weight or more, and more preferably 35% by weight or more, of 100% by weight of the aggregates. The presence of organic solvent (B) in the aggregates allows the redispersion step and resin mixing step to be carried out smoothly. When the content of organic solvent (B) in the aggregates is 30% by weight or more of 100% by weight of the aggregates, there are advantages such as (i) the time required for the redispersion step and resin mixing step can be shortened, (ii) irreversible residue of aggregates can be prevented, and (iii) as a result of (i) and (ii), good dispersibility of polymer fine particles (A) in the resin (D) can be easily obtained.

[0201] Alternatively, purified polymer fine particles (A) can be obtained as a dried powder by dehydrating and / or desolventing the aggregates, and then further drying the aggregates. By washing the aggregates with water that does not contain an organic solvent (B) before drying them, it is possible to prevent the particles from coalescing during the drying process. Through this operation, a dried powder of purified polymer fine particles (A) with extremely low levels of impurities can be obtained.

[0202] (1-3-1.Element content) The aggregates obtained by the first manufacturing method preferably have an element S content of 1000 ppm or less, more preferably 500 ppm or less, even more preferably 200 ppm or less, and particularly preferably 100 ppm or less, relative to the weight of the aggregates. The aggregates obtained by the first manufacturing method preferably have an element P content of 1000 ppm or less, more preferably 500 ppm or less, even more preferably 200 ppm or less, and particularly preferably 100 ppm or less, relative to the weight of the aggregates. The aggregates obtained by the first manufacturing method preferably have a total element S and P content of 2000 ppm or less, more preferably 1000 ppm or less, more preferably 400 ppm or less, even more preferably 200 ppm or less, and particularly preferably 100 ppm or less, relative to the weight of the aggregates. The lower the element S and / or P content in the aggregates obtained by the first manufacturing method, the less adverse effect there is on the long-term reliability of the resin composition mixed with resin (D). The content of elements S and / or P in the aggregates obtained by the first manufacturing method can also be said to be the content of impurities (contaminants) in the aggregates.

[0203] If the aggregates obtained by the first manufacturing method contain elements S and / or P, the origin of these elements is not particularly limited. The sources of elements S and / or P in the aggregates may be (i) emulsifiers used in the production of polymer fine particles (A), or (i) trace elements contained in the water and monomers used in the production of polymer fine particles (A), as well as the organic solvent (B). The content of elements S and / or P in the aggregates obtained by the first manufacturing method can be measured using an X-ray fluorescence analyzer, liquid chromatography, or ICP emission spectrometer.

[0204] [1-4. Method for producing resin compositions] A method for producing a resin composition according to one embodiment of the present invention includes a redispersion step of redispersing the aggregates separated from the aqueous phase (for example, aggregates separated in the separation step or washing step) in an organic solvent (C), and a resin mixing step of mixing the dispersion obtained in the redispersion step with a resin (D).

[0205] A method for producing a resin composition according to one embodiment of the present invention can also be said to include a method for producing purified polymer fine particles (A) according to one embodiment of the present invention (first method of production) as one step. In the method for producing a resin composition according to one embodiment of the present invention, aggregates of purified polymer fine particles (A) are formed as an intermediate product.

[0206] In a method for producing a resin composition according to one embodiment of the present invention, an aggregate of purified polymer fine particles (A) is used to obtain a resin composition through a redispersion step and a resin mixing step. Therefore, it has the advantage of being able to efficiently provide a resin composition with few impurities and excellent dispersibility of polymer fine particles (A) with minimal environmental impact. The ability to "efficiently provide a resin composition" is also referred to as "improved productivity." Furthermore, in a method for producing a resin composition according to one embodiment of the present invention, the organic solvent mixing step, the mixing state maintenance step, the loose aggregation step, the separation step, the redispersion step, and the resin mixing step can be carried out continuously (a washing step may be optionally carried out between the separation step and the redispersion step), making it possible to create a continuous manufacturing method suitable for the production of large quantities of a small variety of products.

[0207] The following describes each step of the method for producing a resin composition according to one embodiment of the present invention. Except for matters described in detail below, refer to the descriptions in sections [1-2. Method for producing purified polymer fine particles (A)] and [1-3. Aggregates] as appropriate.

[0208] (1-4-1.Redispersion process) The redispersion step is a step in which the aggregates separated in the separation step or washing step are redispersed in an organic solvent (C). The redispersion step can also be described as a step in which the organic solvent (C) is added to the aggregates separated in the separation step or washing step and the resulting mixture is mixed. Through the redispersion step, a dispersion can be obtained in which the purified polymer fine particles (A) in the aggregates are dispersed in the organic solvent (C) in a substantially primary particle state.

[0209] The organic solvent (C) is not particularly limited, and any organic solvent capable of redispersing polymer microparticles (A) can be used. The organic solvent (C) may consist of only one type of organic solvent or may be a mixture of two or more types of organic solvents.

[0210] Specific examples of organic solvent (C) include, for example, the solvents exemplified in organic solvent (B), aliphatic hydrocarbons (e.g., hexane, heptane, octane, cyclohexane, ethylcyclohexane, etc.), and mixtures of these solvents. Furthermore, from the viewpoint of ensuring more reliable redispersibility of aggregates, it is preferable to use the same type of organic solvent as organic solvent (B) used in the organic solvent mixing step.

[0211] The amount of organic solvent (C) used in the redispersion step is not particularly limited and can be appropriately set depending on the type and amount of polymer fine particles (A) contained in the aggregate, the type and amount of organic solvent (B) contained in the aggregate, and the type of organic solvent (C). In one embodiment, the amount of organic solvent (C) used in the redispersion step is preferably 100 to 500 parts by weight, more preferably 150 to 400 parts by weight, even more preferably 200 to 350 parts by weight, and particularly preferably 250 to 300 parts by weight, per 100 parts by weight of aggregate. When the amount of organic solvent (C) used in the redispersion step is 100 parts by weight or more per 100 parts by weight of aggregate, it has the advantages of (i) the polymer fine particles (A) being more easily dispersed uniformly in the organic solvent (C), (ii) preventing the remaining aggregate clumps, and (iii) the dispersion having low viscosity and being easy to handle. Furthermore, when the amount of organic solvent (C) used in the redispersion process is 500 parts by weight or less, it has the advantage of allowing for efficient evaporation and distillation of the final volatile components.

[0212] No special apparatus or method is required for mixing the aggregate with the organic solvent (C); it can be carried out using a general apparatus with a stirring and mixing function.

[0213] The preferred temperatures for the aggregates and the organic solvent (C) when subjected to the redispersion process are not particularly limited. In one embodiment, the temperature of the aggregates and the organic solvent (C) when subjected to the redispersion process, and / or the temperature of the dispersion obtained in the redispersion process, is preferably, for example, 10°C to 50°C, more preferably 15°C to 40°C, and even more preferably 20°C to 40°C. When the temperature of the aggregates and the organic solvent (C) when subjected to the redispersion process, and / or the temperature of the dispersion obtained in the redispersion process are within the above ranges, the obtained dispersion has the advantage that the polymer fine particles (A) are well dispersed in the organic solvent (C), and the organic solvent used is less likely to volatilize.

[0214] (1-4-2. Resin mixing process) The resin mixing step is a step of mixing the dispersion obtained in the redispersion step with the resin (D). The resin mixing step makes it possible to obtain a resin composition in which polymer fine particles (A) are substantially dispersed in the resin (D) in a primary particle state and which contains almost no impurities derived from latex (such as emulsifiers and electrolytes).

[0215] (1-4-3.Resin (D)) The resin (D) is not particularly limited, but is preferably a thermosetting resin. The thermosetting resin preferably contains at least one selected from the group consisting of resins containing polymers obtained by polymerizing ethylenically unsaturated monomers, epoxy resins, phenolic resins, polyol resins, and amino-formaldehyde resins (melamine resins). Also, as a thermosetting resin, a resin containing a polymer obtained by polymerizing aromatic polyester raw materials is also an example. Examples of aromatic polyester raw materials include aromatic vinyl compounds, (meth)acrylic acid derivatives, vinyl cyanide compounds, maleimide compounds and other radical polymerizable monomers, dimethyl terephthalate, alkylene glycol, etc. Only one of these thermosetting resins may be used, or two or more may be used in combination.

[0216] (Ethylene-unsaturated monomer) The ethylenically unsaturated monomer is not particularly limited as long as it has at least one ethylenically unsaturated bond in its molecule.

[0217] Examples of ethylenically unsaturated monomers include acrylic acid, α-alkylacrylic acid, α-alkylacrylic acid esters, β-alkylacrylic acid, β-alkylacrylic acid esters, methacrylic acid, acrylic acid esters, methacrylic acid esters, vinyl acetate, vinyl esters, unsaturated esters, polyunsaturated carboxylic acids, polyunsaturated esters, maleic acid, maleic acid esters, maleic anhydride, and acetoxystyrene. These may be used individually or in combination of two or more.

[0218] (Epoxy resin) The epoxy resin is not particularly limited as long as it has at least one epoxy bond in its molecule.

[0219] Specific examples of epoxy resins include, for example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AD ​​type epoxy resin, bisphenol S type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, novolac type epoxy resin, glycidyl ether type epoxy resin of bisphenol A propylene oxide adduct, hydrogenated bisphenol A (or F) type epoxy resin, fluorinated epoxy resin, rubber-modified epoxy resin containing polybutadiene or NBR, flame-retardant epoxy resins such as glycidyl ether of tetrabromobisphenol A, p-oxybenzoic acid glycidyl ether type epoxy resin, m-aminophenol type epoxy resin, diaminodiphenylmethane-based epoxy resin, urethane-modified epoxy resin having urethane bonds, various alicyclic epoxy resins, glycidyl ethers of polyhydric alcohols, hydantoin type epoxy resins, epoxidized products of unsaturated polymers such as petroleum resins, and aminoglycidyl ether resins. Examples of the polyhydric alcohols include N,N-diglycidylaniline, N,N-diglycidyl-o-toluidine, triglycidyl isocyanurate, polyalkylene glycol diglycidyl ether, and glycerin. Examples of epoxy resins include epoxy compounds obtained by adding bisphenol A (or F) compounds or polybasic acids to the epoxy resins mentioned above. The epoxy resins are not limited to these, and commonly used epoxy resins may be used. These epoxy resins may be used individually or in combination of two or more.

[0220] Among the epoxy resins mentioned above, those having at least two epoxy groups per molecule are preferred because they exhibit high reactivity in the curing of the resin composition and the resulting cured product easily forms a three-dimensional network. Furthermore, among epoxy resins having at least two epoxy groups per molecule, those primarily composed of bisphenol-type epoxy resins are preferred due to their economic efficiency and ease of availability.

[0221] (Phenolic resin) The phenolic resin is not particularly limited as long as it is a compound obtained by reacting phenols with aldehydes. The phenols are not particularly limited, but examples include phenol, orthocresol, metacresol, paracresol, xylenol, paratertiary-butylphenol, paraoctylphenol, paraphenylphenol, bisphenol A, bisphenol F, and resorcinol. Particularly preferred phenols include phenol and cresol.

[0222] The aldehydes are not particularly limited, but examples include formaldehyde, acetaldehyde, butyraldehyde, and acrolein, as well as mixtures thereof. The aldehydes can also be the substances that generate the aldehydes mentioned above, or solutions of these aldehydes. Formaldehyde is preferred as the aldehyde because the reaction between phenols and aldehydes is easy.

[0223] When reacting phenols with aldehydes, the molar ratio (F / P) of phenols (P) to aldehydes (F) (hereinafter also referred to as the reaction molar ratio) is not particularly limited. When an acid catalyst is used in the reaction, the reaction molar ratio (F / P) is preferably 0.4 to 1.0, and more preferably 0.5 to 0.8. When an alkali catalyst is used in the reaction, the reaction molar ratio (F / P) is preferably 0.4 to 4.0, and more preferably 0.8 to 2.5. When the reaction molar ratio is above the lower limit, the yield will not be too low, and there is no risk of the molecular weight of the resulting phenol resin being too small. On the other hand, when the reaction molar ratio is below the upper limit, the molecular weight of the phenol resin will not be too high, and the softening point will not be too high, so sufficient fluidity can be obtained when heated. Also, when the reaction molar ratio is below the upper limit, the molecular weight is easy to control, and there is no risk of gelation or partial gelation due to the reaction conditions.

[0224] (Polyol resin) Polyol resins are compounds having two or more active hydrogen atoms at their ends, and are bifunctional or more polyols with a molecular weight of approximately 50 to 20,000. Examples of polyol resins include aliphatic alcohols, aromatic alcohols, polyether-type polyols, polyester-type polyols, polyolefin polyols, and acrylic polyols.

[0225] Aliphatic alcohols may be dihydric alcohols or trihydric or higher alcohols (trihydric alcohols, tetrahydric alcohols, etc.). Examples of dihydric alcohols include alkylene glycols such as ethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, neopentyl glycol (especially alkylene glycols with about 1 to 6 carbon atoms), and dehydration condensates of two or more molecules (e.g., about 2 to 6 molecules) of such alkylene glycols (e.g., diethylene glycol, dipropylene glycol, tripropylene glycol, etc.). Examples of trihydric alcohols include glycerin, trimethylolpropane, trimethylolethane, 1,2,6-hexanetriol (especially trihydric alcohols with about 3 to 10 carbon atoms). Examples of tetrahydric alcohols include pentaerythritol and diglycerin. Other examples include sugars such as monosaccharides, oligosaccharides, and polysaccharides.

[0226] Aromatic alcohols include bisphenols such as bisphenol A and bisphenol F; biphenyls such as dihydroxybiphenyl; polyhydric phenols such as hydroquinone and phenol-formaldehyde condensates; and naphthalenediol.

[0227] Examples of polyether-type polyols include random copolymers or block copolymers obtained by ring-opening polymerization of ethylene oxide, propylene oxide, butylene oxide, styrene oxide, etc., in the presence of one or more initiators containing active hydrogen, and mixtures of these copolymers. Examples of initiators containing active hydrogen used in ring-opening polymerization of polyether-type polyols include diols such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, and bisphenol A; triols such as trimethylolethane, trimethylolpropane, and glycerin; sugars such as monosaccharides, oligosaccharides, and polysaccharides; sorbitol; and amines such as ammonia, ethylenediamine, urea, monomethyldiethanolamine, and monoethyldiethanolamine.

[0228] Examples of polyester-type polyols include polymers obtained by polycondensing (i) polybasic acids and / or their acid anhydrides, such as maleic acid, fumaric acid, adipic acid, sebacic acid, phthalic acid, dodecanediic acid, isophthalic acid, and azelaic acid, with (ii) polyhydric alcohols, such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, and 3-methyl-1,5-pentanediol, in the presence of an esterification catalyst at a temperature range of 150 to 270°C. Furthermore, examples of (i) polyester-type polyols include ring-opening polymers of ε-caprolactone and valerolactone, and (ii) active hydrogen compounds having two or more active hydrogens, such as polycarbonate diols and castor oil.

[0229] Examples of polyolefin-type polyols include polybutadiene polyols, polyisoprene polyols, and their hydrogenated products.

[0230] Examples of acrylic polyols include (i) copolymers of hydroxyl group-containing monomers such as hydroxyethyl (meth)acrylate, hydroxybutyl (meth)acrylate, and vinylphenol, and (ii) copolymers of common monomers such as n-butyl (meth)acrylate and 2-ethylhexyl (meth)acrylate, as well as mixtures of these copolymers.

[0231] Among these polyol resins, polyether-type polyols are preferred because the resulting resin composition has low viscosity and excellent workability, and the resulting cured product exhibits an excellent balance between hardness and toughness. Furthermore, among these polyol resins, polyester-type polyols are preferred because the resulting resin composition provides a cured product with excellent adhesion.

[0232] (Amino-formaldehyde resin) The amino-formaldehyde resin is not particularly limited as long as it is a compound obtained by reacting an amino compound with an aldehyde under an alkaline catalyst. Examples of the amino compound include melamine; 6-substituted guanamines such as guanamine, acetoguanamine, and benzoguanamine; amine-substituted triazine compounds such as CTU guanamine (3,9-bis[2-(3,5-diamino-2,4,6-triazaphenyl)ethyl]-2,4,8,10-tetraoxaspiro[5,5]undecane) and CMTU guanamine (3,9-bis[(3,5-diamino-2,4,6-triazaphenyl)methyl]-2,4,8,10-tetraoxaspiro[5,5]undecane); and ureas such as urea, thiourea, and ethyleneurea. Furthermore, as the amino compound, substituted melamine compounds obtained by substituting the hydrogen of the amino group of melamine with an alkyl group, an alkenyl group, and / or a phenyl group (described in U.S. Patent No. 5,998,573 (corresponding Japanese Publication No. 9-143238)), and substituted melamine compounds obtained by substituting the hydrogen of the amino group of melamine with a hydroxyalkyl group, a hydroxyalkyloxyalkyl group, and / or an aminoalkyl group (described in U.S. Patent No. 5,322,915 (corresponding Japanese Publication No. 5-202157)) can also be used. Among the above-mentioned compounds, melamine, guanamine, acetoguanamine, and benzoguanamine, which are polyfunctional amino compounds, are preferred as the amino compound because they are industrially produced and inexpensive, and melamine is particularly preferred. The above-mentioned amino compound may be used alone or in combination of two or more. In addition to these amino compounds, (i) phenols such as phenol, cresol, alkylphenol, resorcinol, hydroquinone, and pyrogallol, and (ii) aniline may also be used.

[0233] Examples of the aldehydes include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde, and furfural. Among the aldehydes, formaldehyde and paraformaldehyde are preferred because they are inexpensive and have good reactivity with the amino compounds mentioned above. In the production of amino-formaldehyde resin, it is preferable to use an amount of aldehyde such that there are 1.1 to 6.0 moles of active aldehyde groups per mole of amino compound, and it is particularly preferable that there are 1.2 to 4.0 moles of active aldehyde groups.

[0234] (1-4-4. Physical properties of resin (D)) The properties of resin (D) are not particularly limited. Resin (D) preferably has a viscosity of 100 mPa·s to 1,000,000 mPa·s at 25°C. More preferably, the viscosity of resin (D) is 50,000 mPa·s or less, even more preferably 30,000 mPa·s or less, and particularly preferably 15,000 mPa·s or less at 25°C. According to the above configuration, resin (D) has the advantage of excellent fluidity. Resin (D) having a viscosity of 100 mPa·s to 1,000,000 mPa·s at 25°C can also be considered a liquid.

[0235] The greater the fluidity of the resin (D), in other words, the lower the viscosity, the more difficult it becomes to disperse the polymer fine particles (A) in the resin (D) in a primary particle state. Conventionally, it has been extremely difficult to disperse polymer fine particles (A) in a primary particle state in a resin (D) having a viscosity of 1,000,000 mPa·s or less at 25°C. However, according to the method for producing a resin composition according to one embodiment of the present invention, a resin composition can be obtained in which polymer fine particles (A) having the above-described structure are well dispersed in a resin (D) having a viscosity of 1,000,000 mPa·s or less at 25°C.

[0236] Furthermore, the viscosity of the resin (D) is more preferably 100 mPa·s or higher, even more preferably 500 mPa·s or higher, even more preferably 1000 mPa·s or higher, and particularly preferably 1500 mPa·s or higher at 25°C. With this configuration, the resin (D) penetrates into the polymer fine particles (A), preventing the polymer fine particles (A) from fusing together.

[0237] The resin (D) may have a viscosity greater than 1,000,000 mPa·s. The resin (D) may be semi-solid (semi-liquid) or solid. When the resin (D) has a viscosity greater than 1,000,000 mPa·s, the resulting resin composition has the advantage of being less sticky and easier to handle.

[0238] The resin (D) preferably has an endothermic peak at 25°C or below in a differential thermal scanning calorimetry (DSC) thermogram, and more preferably has an endothermic peak at 0°C or below. According to the above configuration, the resin (D) has the advantage of excellent fluidity.

[0239] (1-4-5. Mixing ratio of polymer fine particles (A) and resin (D)) In the resin mixing process, the blending ratio of polymer fine particles (A) in the dispersion to the resin (D) to be mixed with the dispersion is not particularly limited. In one embodiment, when the total of polymer fine particles (A) and resin (D) in the dispersion is 100% by weight, it is preferable that polymer fine particles (A) are 10% to 50% by weight and resin (D) is 50% to 90% by weight, more preferably that polymer fine particles (A) are 25% to 40% by weight and resin (D) is 60% to 75% by weight, and even more preferably that polymer fine particles (A) are 30% to 40% by weight and resin (D) is 60% to 70% by weight. When the blending ratio of polymer fine particles (A) and resin (D) is as described above, there is an advantage that the resin composition has good fluidity after the volatile components have been removed by distillation.

[0240] No special equipment or method is required for mixing the dispersion and resin (D); it can be carried out using general equipment with stirring and mixing capabilities.

[0241] The preferred temperatures of the dispersion and resin (D) when subjected to the resin mixing process are not particularly limited. In one embodiment, the temperature of the dispersion and resin (D) when subjected to the resin mixing process, and / or the temperature of the resin composition obtained by the resin mixing process, is preferably, for example, 10°C to 80°C, more preferably 15°C to 80°C, and even more preferably 20°C to 80°C. When the temperature of the dispersion and resin (D) when subjected to the resin mixing process, and / or the temperature of the resin composition obtained by the resin mixing process are within the above ranges, there is the advantage that mixing is facilitated.

[0242] (1-4-6. Distillation Process) A method for producing a resin composition according to one embodiment of the present invention may further include a distillation step in which, after a resin mixing step, volatile components such as organic solvent (B), organic solvent (C), and water are distilled off from a mixture (resin composition) obtained by mixing a dispersion liquid and resin (D).

[0243] Known methods can be applied to remove volatile components by distillation. For example, methods include charging the mixture into a tank and distilling it under reduced pressure and heating, bringing a dry gas into countercurrent contact with the mixture in a tank, using a continuous method such as a thin-film evaporator, or using an extruder or continuous stirring tank equipped with a defoliation mechanism. The temperature and time required for distillation of volatile components can be appropriately selected within a range that does not impair the quality of the resin composition. Furthermore, the amount of volatile components remaining in the resin composition can be appropriately selected within a range that does not pose a problem, depending on the intended use of the resin composition.

[0244] A method for producing a resin composition according to another embodiment of the present invention includes a resin mixing step of mixing the aggregates separated in the separation step or washing step with resin (D). In a method for producing a resin composition according to another embodiment of the present invention, which includes a resin mixing step of mixing the aggregates with resin (D), the aggregates are directly mixed with resin (D) without going through a redispersion step, that is, without redispersing the aggregates obtained in the separation step or washing step in an organic solvent (C). A resin composition according to one embodiment of the present invention can also be obtained by such a production method.

[0245] [1-5. Resin composition] The resin composition obtained by the method for producing a resin composition according to one embodiment of the present invention has polymer fine particles (A) uniformly dispersed in the resin (D) in the state of primary particles, and furthermore, contains few impurities.

[0246] The resin composition obtained by the method for producing a resin composition according to one embodiment of the present invention may optionally contain other optional components other than polymer fine particles (A) and resin (D). Examples of other optional components include antiblocking agents, curing agents, colorants such as pigments and dyes, extender pigments, ultraviolet absorbers, antioxidants, heat stabilizers (gelling inhibitors), plasticizers, leveling agents, defoaming agents, silane coupling agents, antistatic agents, flame retardants, lubricants, viscosity reducers, low shrinkage agents, inorganic fillers, organic fillers, thermoplastic resins, desiccants, and dispersants.

[0247] The aforementioned other optional components may be added as appropriate in any step of the method for producing a resin composition according to one embodiment of the present invention. For example, the additive may be added to the dispersion and / or resin (D) in the resin mixing step.

[0248] The resin composition obtained by the method for producing the resin composition according to one embodiment of the present invention may further contain a known thermosetting resin other than resin (D), or a known thermoplastic resin.

[0249] The cured product obtained by curing the resin composition obtained by the method for producing a resin composition according to one embodiment of the present invention has high dispersion stability of polymer fine particles (A) and low impurity content. The cured product obtained by curing the resin composition obtained by the method for producing a resin composition according to one embodiment of the present invention is also one embodiment of the present invention.

[0250] The resin composition obtained by the method for producing a resin composition according to one embodiment of the present invention can be used for a variety of applications, and these applications are not particularly limited. The resin composition is preferably used in applications such as adhesives, coatings, binders for reinforcing fibers, composite materials, 3D printing materials, sealants, electronic circuit boards, ink binders, wood chip binders, rubber chip binders, foam chip binders, casting binders, rock solidification materials for flooring and ceramics, and urethane foam. Examples of urethane foam include automobile seats, automobile interior parts, sound absorbing materials, vibration damping materials, shock absorbers, heat insulating materials, and construction floor cushions. Among the above-mentioned applications, the resin composition is more preferably used as an adhesive, coating, binder for reinforcing fibers, composite materials, 3D printing materials, sealants, and electronic circuit boards.

[0251] [Embodiment 2] [2. Method for producing purified polymer fine particles (A) (Second manufacturing method)] One embodiment of the present invention provides a novel method for efficiently producing aggregates of polymer fine particles (A) with reduced impurity content.

[0252] A method for producing purified polymer fine particles (A) according to one embodiment of the present invention includes an organic solvent mixing step of mixing polymer fine particles (A) and latex containing an emulsifier with an organic solvent (B), A loose aggregation step is performed in which the mixture obtained in the organic solvent mixing step is brought into contact with water to form aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase, and The separation step includes separating the aggregate from the aqueous phase, After the separation step, the method further includes repeating, one or more times, a cycle selected from the following (i) and (ii).

[0253] (i) A first cycle including: a first step of adding the organic solvent (B) to the aggregate obtained in the separation step; a second step of bringing the mixture obtained in the first step into contact with water to form an aggregate of the polymer microparticles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase, and (ii) A second cycle including: a first step of adding water to the aggregate obtained in the separation step; a second step of bringing the mixture obtained in the first step into contact with the organic solvent (B) to form an aggregate of the polymer microparticles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase.

[0254] In this specification, the "method for producing the purified polymer microparticles (A)" can also be referred to as the "method for purifying the polymer microparticles (A)". Further, the method for producing the purified polymer microparticles (A) according to an embodiment of the present invention may be hereinafter referred to as the "second production method".

[0255] In the second production method, after the separation step, a washing step of repeating, one or more times, a cycle selected from the first cycle and the second cycle is performed, whereby aggregates of polymer microparticles (A) (that is, purified polymer microparticles (A)) with reduced contents of impurities such as emulsifiers, more specifically, elements P and S derived from the emulsifier, can be efficiently produced.

[0256] Hereinafter, the emulsifier used in the second production method and the elemental amounts of the obtained aggregates will be described. Except for the matters described in detail below, the descriptions regarding the raw materials (components) and each step of Embodiment 1 are incorporated as appropriate.

[0257] (Emulsifier) In the second production method, the emulsifier contained in the latex may be a known emulsifier (dispersant). Examples of known emulsifiers include anionic emulsifiers, nonionic emulsifiers, polyvinyl alcohol, alkyl-substituted cellulose, polyvinyl pyrrolidone, and polyacrylic acid derivatives. Examples of anionic emulsifiers include sulfur-based emulsifiers, phosphorus-based emulsifiers, sarcosine-based emulsifiers, and carboxylic acid-based emulsifiers. Examples of sulfur-based emulsifiers include sodium dodecylbenzenesulfonate (abbreviation: SDBS). Examples of phosphorus-based emulsifiers include sodium polyoxyethylene lauryl ether phosphate.

[0258] From the perspective of environmental load, in the second production method, the emulsifier contained in the latex preferably contains a lipophilic moiety and a hydrophilic moiety, and the hydrophilic moiety preferably has a polyoxyethylene group. From the perspective of ease of purification of the polymer fine particles (A), the emulsifier is more preferably a sulfur-based emulsifier in which the hydrophilic moiety contains a sulfate ester moiety. Also, from the perspective of low environmental load, the emulsifier is more preferably a phosphorus emulsifier containing a phosphate ester moiety. The description of the emulsifier containing a lipophilic moiety and a hydrophilic moiety, where the hydrophilic moiety has a polyoxyethylene group, shall incorporate the description in the section of (1-2-4. Emulsifier).

[0259] (Elemental amount of the aggregate) The aggregates obtained by the second manufacturing method preferably have an element S content of 500 ppm or less, more preferably 200 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less, relative to the weight of the aggregates. The aggregates obtained by the second manufacturing method preferably have an element P content of 500 ppm or less, more preferably 200 ppm or less, even more preferably 100 ppm or less, and particularly preferably 50 ppm or less, relative to the weight of the aggregates. The aggregates obtained by the second manufacturing method preferably have a total element S and P content of 1000 ppm or less, more preferably 400 ppm or less, more preferably 200 ppm or less, even more preferably 100 ppm or less, even more preferably 50 ppm or less, and particularly preferably 25 ppm or less, relative to the weight of the aggregates. The lower the element S and / or P content in the aggregates obtained by the second manufacturing method, the less adverse effect it has on the long-term reliability (long-term stability) of the resin composition obtained by mixing the aggregates with resin (D). The content of elements S and / or P in the aggregates obtained by the second manufacturing method can also be said to be the content of impurities (contaminants) in the aggregates.

[0260] If the aggregates obtained by the second manufacturing method contain elements S and / or P, the origin of these elements is not particularly limited. The sources of elements S and / or P in the aggregates may be (i) emulsifiers used in the production of polymer fine particles (A), or (i) trace elements contained in the water and monomers used in the production of polymer fine particles (A), as well as the organic solvent (B). The content of elements S and / or P in the aggregates obtained by the second manufacturing method can be measured using an X-ray fluorescence analyzer, liquid chromatography, or ICP emission spectrometer.

[0261] One embodiment of the present invention may have the following configuration:

[0262] [1] A step of mixing an organic solvent with a latex containing polymer fine particles (A) and an emulsifier, and The process includes a mixing state maintenance step in which the mixture obtained in the organic solvent mixing step is either allowed to stand or stirred, or both, A method for producing purified polymer fine particles (A), wherein the emulsifier contains a lipophilic portion and a hydrophilic portion, and the hydrophilic portion has a polyoxyethylene group.

[0263] [2] A method for producing purified polymer fine particles (A) according to [1], wherein the hydrophilic portion contains a phosphate ester portion.

[0264] [3] The method for producing purified polymer fine particles (A) according to [1] or [2], wherein in the step of maintaining the mixed state, the mixture is left to stand and / or stirred until the viscosity of the mixture becomes constant.

[0265] [4] A method for producing purified polymer fine particles (A) according to any one of [1] to [3], wherein in the step of maintaining the mixed state, the mixture is left to stand for 30 minutes or more.

[0266] [5] A loose aggregation step in which the mixture obtained through the mixing state maintenance step is brought into contact with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase, and A separation step of separating the aggregate from the aqueous phase, A method for producing purified polymer fine particles (A) according to any one of [1] to [4], further comprising the above.

[0267] [6] A method for producing purified polymer fine particles (A) according to [5], further comprising the step of repeating one or more cycles selected from (i) and (ii) below after the separation step: (i) A first cycle comprising: a first step of adding the organic solvent (B) to the aggregate obtained in the separation step; a second step of contacting the mixture obtained in the first step with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in an aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase, (ii) A second cycle comprising: a first step of adding water to the aggregates obtained in the separation step; a second step of contacting the mixture obtained in the first step with the organic solvent (B) to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregates obtained in the second step from the aqueous phase.

[0268] [7] An organic solvent mixing step in which latex containing polymer fine particles (A) and an emulsifier is mixed with an organic solvent (B), A loose aggregation step is performed in which the mixture obtained in the organic solvent mixing step is brought into contact with water to form aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase, and The separation step includes separating the aggregate from the aqueous phase, A method for producing purified polymer fine particles (A), further comprising the step of repeating one or more cycles selected from (i) and (ii) below after the separation step.

[0269] (i) A first cycle comprising: a first step of adding the organic solvent (B) to the aggregate obtained in the separation step; a second step of contacting the mixture obtained in the first step with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in an aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase, (ii) A second cycle comprising: a first step of adding water to the aggregates obtained in the separation step; a second step of contacting the mixture obtained in the first step with the organic solvent (B) to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregates obtained in the second step from the aqueous phase.

[0270] 〔8〕The method for producing the purified polymer microparticles (A) according to 〔7〕, which includes a mixing state maintenance step of performing either or both of standing and stirring of the mixture obtained in the organic solvent mixing step.

[0271] 〔9〕In the mixing state maintenance step, the method for producing the purified polymer microparticles (A) according to 〔8〕, wherein either or both of standing and stirring of the mixture are performed until the viscosity of the mixture becomes constant.

[0272] 〔10〕In the mixing state maintenance step, the method for producing the purified polymer microparticles (A) according to 〔8〕 or 〔9〕, wherein the mixture is allowed to stand for 30 minutes or longer.

[0273] 〔11〕The polymer microparticles (A) have a graft portion composed of a polymer containing a structural unit derived from at least one monomer selected from the group consisting of an aromatic vinyl monomer, a vinyl cyanide monomer, and a (meth)acrylate monomer as a structural unit. The method for producing the purified polymer microparticles (A) according to any one of 〔1〕 to 〔10〕.

[0274] 〔12〕A method for producing a resin composition, which includes, as one step, the method for producing the purified polymer microparticles (A) according to any one of 〔5〕 to 〔10〕, a redispersion step of redispersing the aggregate separated from the aqueous phase in an organic solvent (C), and a resin mixing step of mixing the dispersion liquid obtained in the redispersion step with a resin (D). The method for producing a resin composition includes the above steps.

[0275] 〔13〕The method for producing a resin composition according to 〔12〕, wherein the resin (D) is a thermosetting resin.

Examples

[0276] 〔Example A〕 Next, an embodiment of the present invention will be described based on Examples A1 to A6 and Comparative Examples A1 to A4, but the present invention is not limited to these Examples A.

[0277] [Evaluation Method] First, we will explain the evaluation methods for the resin compositions produced by Examples A1-A6 and Comparative Examples A1-A4.

[0278] <Element content measurement> After drying the resin composition at 120°C for 60 minutes, the content of each element, P and S, in the resin composition was measured using a JSX-1000S X-ray fluorescence analyzer (manufactured by JEOL Ltd.). The amount of each element is expressed as concentration (ppm) relative to parts by weight of the resin composition.

[0279] <Measurement of permeability of the aqueous phase> The transmittance of the aqueous phase discharged during the separation process was measured using a Hitachi U-3310 spectrophotometer.

[0280] [Manufacturing example] <1. Polymerization of elastic materials> (Manufacturing Example 1-1; Preparation of Polybutadiene Rubber Latex (R-1)) In a pressure polymerizer, 185 parts by weight of deionized water, 0.002 parts by weight of disodium ethylenediaminetetraacetate (EDTA), 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.065 parts by weight of sodium polyoxyethylene lauryl ether phosphate (hydrophobic group: C12 / number of polyoxyethylenes: n=4) were added. Sodium polyoxyethylene lauryl ether phosphate is a phosphorus-based emulsifier having hydrophilic parts consisting of polyoxyethylene groups and phosphate ester parts. Next, while stirring the added raw materials, oxygen was sufficiently removed from inside the pressure polymerizer by purging the gas inside the polymerizer with nitrogen. Then, 100 parts by weight of butadiene (Bd) was added to the pressure polymerizer, and the temperature inside the polymerizer was raised to 45°C. Subsequently, 0.03 parts by weight of paramentane hydroperoxide (PHP) was added to the pressure polymerizer, followed by 0.05 parts by weight of sodium formaldehyde sulfoxylate (SFS), and polymerization was started. Twenty hours after the start of polymerization, polymerization was terminated by defoliation under reduced pressure to remove the monomers that remained unused during polymerization. During polymerization, PHP and sodium polyoxyethylene lauryl ether phosphate were added to the pressure polymerizer in arbitrary amounts and at arbitrary times. This polymerization yielded an aqueous latex (R-1) containing an elastic material mainly composed of polybutadiene rubber. The volume-average particle size of the elastic material contained in the obtained aqueous latex was 150 nm.

[0281] (Manufacturing Example 1-2; Preparation of Polybutadiene Rubber Latex (R-2)) 185 parts by weight of deionized water, 0.03 parts by weight of tripotassium phosphate, 0.002 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.065 parts by weight of sodium dodecylbenzenesulfonate (SDBS) as an emulsifier were added to the pressure polymerizer. SDBS is a sulfur-based emulsifier that has linear alkylbenzene and sulfate ester groups in its hydrophilic portion, but does not have polyoxyethylene groups or phosphate ester groups. Next, while stirring the added raw materials, the gas inside the pressure polymerizer was replaced with nitrogen to sufficiently remove oxygen from inside the pressure polymerizer. Then, 100 parts by weight of Bd was added to the pressure polymerizer and the temperature inside the pressure polymerizer was raised to 45°C. Subsequently, 0.03 parts by weight of PHP was added to the pressure polymerizer, followed by 0.05 parts by weight of SFS, and polymerization was started. Twenty hours after the start of polymerization, the polymerization was terminated by defoliation under reduced pressure to remove any monomers remaining that were not used in polymerization. During polymerization, PHP and SDBS were added to the pressure polymerizer in arbitrary amounts and at arbitrary times. This polymerization yielded an aqueous latex (R-2) containing an elastic material mainly composed of polybutadiene rubber. The volume-average particle size of the elastic material in the obtained aqueous latex was 170 nm.

[0282] <2. Preparation of polymer microparticles (A) (polymerization of the graft portion)> (Manufacturing Example 2-1; Preparation of Polymer Microparticle Latex (L1)) 250 parts by weight of the polybutadiene rubber latex (R-1) (including 87 parts by weight of an elastic body mainly composed of polybutadiene rubber) and 30 parts by weight of deionized water were added to a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. In the following production examples 2-2 and beyond, the same glass reactor used in production example 2-1 was used.

[0283] The gas in the glass reactor was replaced with nitrogen, and the added raw materials were stirred at 60°C. Next, 0.004 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS were added to the glass reactor and stirred for 10 minutes. Then, a mixture of 12.5 parts by weight of methyl methacrylate (MMA), 0.5 parts by weight of styrene (St), and 0.035 parts by weight of t-butyl hydroperoxide (BHP) was continuously added to the glass reactor over 80 minutes. Subsequently, 0.013 parts by weight of BHP was added to the glass reactor, and stirring of the mixture in the glass reactor was continued for another hour to complete the polymerization. Through these operations, polymer fine particles (A) and an aqueous latex (L1) containing a phosphorus-based emulsifier having a polyoxyethylene group (polyoxyethylene lauryl ether sodium phosphate) were obtained. The polymerization conversion rate of the monomer components was 99% or higher. The volume-average particle size of polymer fine particles (A) contained in the obtained aqueous latex was 160 nm. The solid content concentration (concentration of polymer fine particles (A)) in 100% by weight of the obtained aqueous latex (L1) was 34% by weight. In addition, the amount of phosphorus-based emulsifier containing polyoxyethylene groups in 100% by weight of the obtained aqueous latex (L1) was 0.80% by weight.

[0284] (Manufacturing Example 2-2; Preparation of Polymerized Microparticle Latex (L2)) 250 parts by weight of the polybutadiene rubber latex (R-2) (containing 87 parts by weight of an elastic material mainly composed of polybutadiene rubber) and 30 parts by weight of deionized water were added to a glass reactor. The gas in the glass reactor was replaced with nitrogen, and the added raw materials were stirred at 60°C. Next, 0.004 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS were added to the glass reactor and stirred for 10 minutes. Then, a mixture of 12.5 parts by weight of MMA, 0.5 parts by weight of St, and 0.035 parts by weight of BHP was continuously added to the glass reactor over 80 minutes. After that, 0.013 parts by weight of BHP was added to the glass reactor, and stirring of the mixture in the glass reactor was continued for another hour to complete the polymerization. Through the above procedure, an aqueous latex (L2) containing polymer fine particles (A) and a sulfur-based emulsifier (SDBS) without polyoxyethylene groups was obtained. The polymerization conversion rate of the monomer components was 99% or higher. The volume-average particle size of the polymer fine particles (A) contained in the obtained aqueous latex was 181 nm. The solid content concentration (concentration of polymer fine particles (A)) in the obtained aqueous latex (L2) was 34% by weight. The amount of sulfur-based emulsifier in the obtained aqueous latex (L2) was 0.90% by weight.

[0285] (Manufacturing Example 2-3; Preparation of Polymer Microparticle Latex (L3)) 182 parts by weight of deionized water and 0.01 parts by weight of sodium polyoxyethylene lauryl ether phosphate (hydrophobic group: C12 / number of polyoxyethylenes: n=4) as an emulsifier were added to a glass reactor. Next, while stirring the added raw materials, the gas inside the glass reactor was replaced with nitrogen to completely remove oxygen from the inside of the glass reactor. Then, 8.5 parts by weight of MMA, 0.17 parts by weight of allyl methacrylate (AMA), and 0.003 parts by weight of cumene hydroperoxide (QHP) were added to the glass reactor, and the temperature inside the glass reactor was raised to 60°C. Next, 0.002 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS were added, and polymerization was started. Next, 78.5 parts by weight of MMA, 1.57 parts by weight of AMA, and 0.03 parts by weight of QHP were continuously added over 180 minutes. During polymerization, QHP and sodium polyoxyethylene lauryl ether phosphate were added to the glass reactor in arbitrary amounts and at arbitrary times.

[0286] The volume-average particle size of the elastic material contained in the aqueous latex obtained by this polymerization was 170 nm. Subsequently, a mixture of 12.5 parts by weight of MMA, 0.5 parts by weight of St, and 0.035 parts by weight of BHP was continuously added to a glass reactor over 80 minutes. Then, 0.013 parts by weight of BHP was added to the glass reactor, and stirring of the mixture in the glass reactor was continued for another hour to complete the polymerization. Through these operations, an aqueous latex (L3) containing polymer fine particles (A) and a phosphorus-based emulsifier having a polyoxyethylene group (polyoxyethylene lauryl ether sodium phosphate) was obtained. The polymerization conversion rate of the monomer components was 99% or higher. The volume-average particle size of the polymer fine particles (A) contained in the obtained aqueous latex was 180 nm. The solid content concentration (concentration of polymer fine particles (A)) in 100% by weight of the obtained aqueous latex (L3) was 32% by weight. Furthermore, the amount of phosphorus-based emulsifier containing polyoxyethylene groups in 100% by weight of the obtained aqueous latex (L3) was 0.70% by weight.

[0287] (Manufacturing Example 2-4; Preparation of Polymerized Microparticle Latex (L4)) 182 parts by weight of deionized water and 0.01 parts by weight of sodium polyoxyethylene lauryl ether phosphate (hydrophobic group: C13 branched / number of polyoxyethylenes: n=6) as an emulsifier were added to a glass reactor. Next, while stirring the added raw materials, the gas inside the glass reactor was replaced with nitrogen to completely remove oxygen from the inside of the glass reactor. Then, 8.5 parts by weight of MMA, 0.17 parts by weight of AMA, and 0.003 parts by weight of QHP were added to the glass reactor, and the temperature inside the glass reactor was raised to 60°C. Next, 0.002 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS were added, and polymerization was started. Next, 78.5 parts by weight of MMA, 1.57 parts by weight of AMA, and 0.03 parts by weight of QHP were continuously added over 180 minutes. During polymerization, QHP and polyoxyethylene lauryl ether sodium phosphate were added to the glass reactor in arbitrary amounts and at arbitrary times. The volume-average particle size of the elastic material in the resulting aqueous latex was 170 nm. Subsequently, a mixture of 12.5 parts by weight of MMA, 0.5 parts by weight of St, and 0.035 parts by weight of BHP was continuously added to the glass reactor over 80 minutes. Then, 0.013 parts by weight of BHP was added to the glass reactor, and the mixture in the glass reactor was stirred for another hour to complete the polymerization. This procedure yielded an aqueous latex (L4) containing polymer fine particles (A) and a phosphorus-based emulsifier (polyoxyethylene lauryl ether sodium phosphate) having a polyoxyethylene group. The polymerization conversion rate of the monomer components was 99% or higher. The volume-average particle size of the polymer fine particles (A) in the resulting aqueous latex was 180 nm. The solid content concentration (concentration of polymer fine particles (A)) in 100% by weight of the obtained aqueous latex (L4) was 32% by weight. Furthermore, the amount of phosphorus-based emulsifier containing polyoxyethylene groups in 100% by weight of the obtained aqueous latex (L4) was 0.70% by weight.

[0288] (Manufacturing Example 2-5; Preparation of Polymerized Microparticle Latex (L5)) 182 parts by weight of deionized water and 0.01 parts by weight of sodium polyoxyethylene lauryl ether phosphate (hydrophobic group: C13 branched / number of polyoxyethylenes: n=10) as an emulsifier were added to a glass reactor. Next, while stirring the added raw materials, the gas inside the glass reactor was replaced with nitrogen to completely remove oxygen from the inside of the glass reactor. Then, 8.5 parts by weight of MMA, 0.17 parts by weight of AMA, and 0.003 parts by weight of QHP were added, and the temperature inside the glass reactor was raised to 60°C. Next, 0.002 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS were added, and polymerization was started. Next, 78.5 parts by weight of MMA, 1.57 parts by weight of AMA, and 0.03 parts by weight of QHP were continuously added over 180 minutes. During polymerization, QHP and sodium polyoxyethylene lauryl ether phosphate were added to the glass reactor in arbitrary amounts and at arbitrary times. The volume-average particle size of the elastic material in the resulting aqueous latex was 170 nm. Subsequently, a mixture of 12.5 parts by weight of MMA, 0.5 parts by weight of St, and 0.035 parts by weight of BHP was continuously added to the glass reactor over 80 minutes. Then, 0.013 parts by weight of BHP was added to the glass reactor, and stirring of the mixture in the glass reactor was continued for another hour to complete the polymerization. This procedure yielded an aqueous latex (L5) containing polymer fine particles (A) and a phosphorus-based emulsifier (sodium polyoxyethylene lauryl ether phosphate) having a polyoxyethylene group. The polymerization conversion rate of the monomer components was 99% or higher. The volume-average particle size of the polymer fine particles (A) in the resulting aqueous latex was 180 nm. The solid content concentration (concentration of polymer fine particles (A)) in 100% by weight of the obtained aqueous latex (L5) was 32% by weight. Furthermore, the amount of phosphorus-based emulsifier containing polyoxyethylene groups in 100% by weight of the obtained aqueous latex (L5) was 0.70% by weight.

[0289] (Manufacturing Example 2-6; Preparation of Polymerized Microparticle Latex (L6)) 182 parts by weight of deionized water and 0.01 parts by weight of sodium polyoxyethylene alkyl ether sulfate (a sulfur-based emulsifier containing a polyoxyethylene group) were added to a glass reactor. Next, while stirring the added raw materials, the gas inside the glass reactor was replaced with nitrogen to completely remove oxygen from the inside of the glass reactor. Then, 8.5 parts by weight of MMA, 0.17 parts by weight of AMA, and 0.003 parts by weight of QHP were added, and the temperature inside the glass reactor was raised to 60°C. Next, 0.002 parts by weight of EDTA, 0.001 parts by weight of ferrous sulfate heptahydrate, and 0.2 parts by weight of SFS were added, and polymerization was started. Next, 78.5 parts by weight of MMA, 1.57 parts by weight of AMA, and 0.03 parts by weight of QHP were continuously added over 180 minutes. During polymerization, QHP and sodium polyoxyethylene lauryl ether phosphate were added to the glass reactor in arbitrary amounts and at arbitrary times. The volume-average particle size of the elastic material contained in the aqueous latex obtained by this polymerization was 170 nm. Subsequently, a mixture of 12.5 parts by weight of MMA, 0.5 parts by weight of St, and 0.035 parts by weight of BHP was continuously added to a glass reactor over 80 minutes. Then, 0.013 parts by weight of BHP was added to the glass reactor, and stirring of the mixture in the glass reactor was continued for another hour to complete the polymerization. Through these operations, an aqueous latex (L6) containing polymer fine particles (A) and a sulfur-based emulsifier having a polyoxyethylene group (polyoxyethylene alkyl ether sodium sulfate) was obtained. The polymerization conversion rate of the monomer components was 99% or higher. The volume-average particle size of the polymer fine particles (A) contained in the obtained aqueous latex was 180 nm. The solid content concentration (concentration of polymer fine particles (A)) in 100% by weight of the obtained aqueous latex (L6) was 32% by weight. Furthermore, the amount of sulfur-based emulsifier having a polyoxyethylene group in 100% by weight of the obtained aqueous latex (L6) was 0.70% by weight.

[0290] [Example A1] 756 g of methyl ethyl ketone (MEK) (solubility in water at 20°C, 10% by weight) was added as the organic solvent (B) to a 4 L tank with a stirrer (the tank had an inner diameter of 100 mm, and the stirrer consisted of four flat paddle blades with a blade diameter of 75 mm, arranged in three stages in the axial direction). Next, while stirring the raw material (MEK) in the tank at 450 rpm, 1000 g of latex (L1) containing polymer fine particles (A) obtained in Production Example 2-1 was added to the tank and stirred for 5 seconds (organic solvent mixing step). Next, the mixture in the tank (latex (L1) and MEK) was stirred further at 450 rpm for 60 minutes (maintaining mixed state step). As is clear from Figure 1, stirring the above mixture at 300 rpm for 60 minutes resulted in a constant viscosity of the mixture. In Example A1, the above mixture was stirred at 450 rpm for 60 minutes, so it can be said that the viscosity of the mixture was constant. In other words, in the mixing state maintenance step of Example A1, the mixture was stirred until the viscosity of the mixture became constant.

[0291] After the mixing state maintenance step, the mixture in the tank (latex (L1) and MEK) was stirred at 500 rpm while 800 g of purified water was continuously added to the tank at a supply rate of 200 g / min. After the supply of purified water was completed, stirring of the mixture was immediately stopped. This operation yielded a slurry liquid consisting of floating aggregates and an aqueous phase containing some organic solvent (slow aggregation step). Next, 1200 g of the aqueous phase was discharged from the outlet at the bottom of the tank so that some aggregates containing the aqueous phase remained in the tank, yielding aggregates that were purified polymer fine particles (A) and contained some aqueous phase (separation step). Furthermore, when the permeability of the discharged aqueous phase was measured, the permeability of the aqueous phase was 21%, and no turbidity of the aqueous phase was observed.

[0292] To the aggregate of purified polymer microparticles (A) obtained in the separation step, 660 g of MEK was added as the organic solvent (C). The resulting mixture was mixed for 30 minutes under stirring conditions of 500 rpm to obtain a dispersion in which polymer microparticles (A) were uniformly dispersed in MEK (redispersion step). This dispersion was placed in a 1 L tank equipped with a jacket and a stirrer (the tank had an inner diameter of 100 mm, and the stirrer was equipped with 90 mm airfoil anchor blades), and 567 g of epoxy resin (Mitsubishi Chemical Co., Ltd., trade name JER828) was added to the tank as the resin (D). The mixture was mixed until the resulting mixture was uniform (resin mixing step). Then, the jacket temperature (temperature of the hot water in the tank) was set to 60°C, and the mixture was distilled under reduced pressure using a vacuum pump (oil rotary vacuum pump, TSW-150 manufactured by Sato Vacuum Co., Ltd.) until the volatile components in the mixture reached a predetermined concentration (5000 rpm) (distillation step). By this operation, a resin composition containing polymer microparticles (A) and epoxy resin was obtained.

[0293] The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 1 below.

[0294] [Example A2] The same method as in Example A1 was used for the organic solvent mixing step, the mixing state maintenance step, the slow aggregation step, and the separation step. After the separation step, a washing step (steps 1 to 3 of the second cycle) was performed. Specifically, while stirring the mixture in the tank (aggregates of purified polymer fine particles (A) containing some aqueous phase) at 500 rpm, 450 g of purified water was continuously added to the tank at a supply rate of 200 g / min (step 1 of the second cycle). Then, 120 g of MEK was added to the tank. Next, the mixture in the tank was stirred at 450 rpm for 5 minutes. This operation yielded a slurry liquid consisting of floating aggregates and an aqueous phase containing some organic solvent (step 2 of the second cycle). Next, 1000 g of the aqueous phase was discharged from the outlet at the bottom of the tank so that aggregates containing some aqueous phase remained in the tank, yielding aggregates that were purified polymer fine particles (A) and contained some aqueous phase (step 3 of the second cycle). Furthermore, when the permeability of the discharged aqueous phase was measured, the permeability of the aqueous phase was 33%, and no turbidity of the aqueous phase was observed.

[0295] Using aggregates of purified polymer fine particles (A) obtained in the third step of the second cycle, a redispersion step, a resin mixing step, and a distillation step were performed in the same manner as in Example A1 to obtain a resin composition containing polymer fine particles (A) and epoxy resin. In other words, in Example A2, the second cycle was performed once as a washing step.

[0296] The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 1 below.

[0297] [Example A3] 1000g of methyl ethyl ketone (MEK) (solubility in water at 20°C, 10% by weight) was added as the organic solvent (B) to a 4L tank with a stirrer (the tank had an inner diameter of 100mm, and the stirrer consisted of four flat paddle blades with a blade diameter of 75mm, arranged in three stages in the axial direction). Next, while stirring the raw material (MEK) in the tank at 450rpm, 1000g of latex (L3) containing polymer fine particles (A) obtained in Production Example 2-3 was added to the tank and stirred for 5 seconds (organic solvent mixing step). Next, the mixture in the tank (latex (L3) and MEK) was stirred further at 450rpm for 60 minutes, stirring the mixture until the viscosity of the mixture became constant (maintaining mixed state step).

[0298] After the mixing maintenance step, the mixture in the tank (latex (L3) and MEK) was stirred at 500 rpm while 500 g of purified water was continuously added to the tank at a supply rate of 200 g / min. After the supply of purified water was completed, stirring of the mixture was immediately stopped. This operation yielded a slurry liquid consisting of floating aggregates and an aqueous phase containing some organic solvent (slow aggregation step (stage 1)). Next, 1320 g of the aqueous phase was discharged from the outlet at the bottom of the tank so that some aggregates containing the aqueous phase remained in the tank, yielding aggregates that were purified polymer fine particles (A) and contained some aqueous phase (separation step). Furthermore, when the permeability of the discharged aqueous phase was measured, the permeability of the aqueous phase was 27%, and no turbidity of the aqueous phase was observed.

[0299] To the aggregate of purified polymer fine particles (A) obtained in the separation step, 600 g of MEK as the organic solvent (C) was added. The resulting mixture was mixed for 30 minutes under stirring conditions of 500 rpm to obtain a dispersion in which polymer fine particles (A) were uniformly dispersed in MEK (redispersion step). This dispersion was placed in a 1 L tank equipped with a jacket and a stirrer (the tank had an inner diameter of 100 mm, and the stirrer was equipped with 90 mm airfoil anchor blades), and 1813 g of epoxy resin (Mitsubishi Chemical Co., Ltd., trade name JER828) as the resin (D) was added to the tank. The mixture was mixed until the resulting mixture was uniform (resin mixing step). Thereafter, the jacket temperature (temperature of the hot water in the tank) was set to 60°C, and the volatile components in the mixture were removed under reduced pressure using a vacuum pump (oil rotary vacuum pump, TSW-150 manufactured by Sato Vacuum Co., Ltd.) until the volatile components reached a predetermined concentration (5000 rpm) (distillation step). By this operation, a resin composition containing polymer fine particles (A) and epoxy resin was obtained. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 1 below.

[0300] [Example A4] Except for using latex (L4) obtained in Production Example 2-4 instead of latex (L3), the same method as in Example A3 was used for the organic solvent mixing step, mixing state maintenance step, slow aggregation step, and separation step to obtain aggregates that were purified polymer fine particles (A) and contained a portion of the aqueous phase. When the permeability of the aqueous phase discharged in the separation step of Example A4 was measured, the permeability of the aqueous phase was 62%, and no turbidity of the aqueous phase was observed.

[0301] Next, using the aggregates of purified polymer fine particles (A) obtained in the separation step, a redispersion step, a resin mixing step, and a distillation step were performed in the same manner as in Example A3 to obtain a resin composition containing polymer fine particles (A) and epoxy resin. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 1 below.

[0302] [Example A5] Except for using latex (L5) obtained in Production Example 2-5 instead of latex (L3), the same method as in Example A3 was used for the organic solvent mixing step, mixing state maintenance step, slow aggregation step, and separation step to obtain aggregates that were purified polymer fine particles (A) and contained a portion of the aqueous phase. When the permeability of the aqueous phase discharged in the separation step of Example A5 was measured, the permeability of the aqueous phase was 22%, and no turbidity of the aqueous phase was observed.

[0303] Next, using the aggregates of purified polymer fine particles (A) obtained in the separation step, a redispersion step, a resin mixing step, and a distillation step were performed in the same manner as in Example A3 to obtain a resin composition containing polymer fine particles (A) and epoxy resin. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 1 below.

[0304] [Example A6] Except for using latex (L6) obtained in Production Example 2-6 instead of latex (L3), the same method as in Example A3 was used for the organic solvent mixing step, mixing state maintenance step, slow aggregation step, and separation step to obtain aggregates that were purified polymer fine particles (A) and contained a portion of the aqueous phase. When the permeability of the aqueous phase discharged in the separation step of Example A6 was measured, the permeability of the aqueous phase was 44%, and no turbidity of the aqueous phase was observed.

[0305] Next, using the aggregates of purified polymer fine particles (A) obtained in the separation step, a redispersion step, a resin mixing step, and a distillation step were performed in the same manner as in Example A3 to obtain a resin composition containing polymer fine particles (A) and epoxy resin. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 1 below.

[0306] [Comparative Example A1] Except for the fact that the organic solvent mixing step, the slow aggregation step, and the separation step were performed immediately after the organic solvent mixing step without performing a mixing state maintenance step, the same method as in Example A1 was used to obtain aggregates containing a portion of the aqueous phase. When the permeability of the aqueous phase discharged in the separation step of Comparative Example A1 was measured, the permeability of the aqueous phase was 0.05%, and it was turbid.

[0307] [Comparative example A2] Except for the fact that the organic solvent mixing step, the slow aggregation step, and the separation step were performed immediately after the organic solvent mixing step without performing a mixing state maintenance step, the same method as in Example A3 was used to obtain aggregates containing a portion of the aqueous phase. When the permeability of the aqueous phase discharged in the separation step of Comparative Example A2 was measured, the permeability of the aqueous phase was 0.11%, and it was turbid.

[0308] [Comparative example A3] The organic solvent mixing step, the slow aggregation step, and the separation step were performed in the same manner as in Example A4, except that the mixing state maintenance step was omitted after the organic solvent mixing step, and the slow aggregation step was performed immediately thereafter, to obtain an aggregate containing a portion of the aqueous phase. When the permeability of the aqueous phase discharged in the separation step of Comparative Example A3 was measured, the permeability of the aqueous phase was 0.12%, and it was turbid.

[0309] [Comparative example A4] Except for the fact that the organic solvent mixing step, the slow aggregation step, and the separation step were performed immediately after the organic solvent mixing step without performing a mixing state maintenance step, the same method as in Example A5 was used to obtain aggregates containing a portion of the aqueous phase. When the permeability of the aqueous phase discharged in the separation step of Comparative Example A4 was measured, the permeability of the aqueous phase was 0.02%, and it was turbid.

[0310] [Measuring the viscosity of mixtures] The organic solvent mixing step was carried out under the same conditions as in Example A1. Specifically, latex containing a phosphorus-based emulsifier having a polyoxyethylene group was mixed with MEK (organic solvent) to obtain a mixture. The obtained mixture (latex (L1) and MEK) (labeled "mixture containing phosphorus-based emulsifier" in Figure 1) was stirred at 300 rpm. The viscosity of the mixture was measured using a viscometer (BROOKFIELD DV-II+Pro digital viscometer) 5 seconds, 5 minutes, 15 minutes, 30 minutes, 45 minutes, 60 minutes, and 90 minutes after the start of stirring. The results are shown as black triangles in Figure 1.

[0311] The organic solvent mixing step was carried out under the same conditions as in Example A1. Specifically, latex containing a sulfur-based emulsifier without polyoxyethylene groups was mixed with MEK (organic solvent) to obtain a mixture. The obtained mixture (latex (L2) and MEK) (labeled "mixture containing sulfur-based emulsifier" in Figure 1) was stirred at 300 rpm. The viscosity of the mixture was measured using a viscometer (BROOKFIELD DV-II+Pro digital viscometer) 5 seconds, 5 minutes, 15 minutes, and 30 minutes after the start of stirring. The results are shown as black circles in Figure 1.

[0312] The viscosity of the mixture was measured using a CPE-52, with the spindle changed as needed depending on the viscosity range, and the shear rate was varied as needed at a measurement temperature of 25°C.

[0313] Figure 1 is a graph showing the change in viscosity over time of a mixture of latex containing a phosphorus-based emulsifier with a polyoxyethylene group or a sulfur-based emulsifier without a polyoxyethylene group, and an organic solvent. In Figure 1, the viscosity of the mixture (latex (L1) and MEK) increased rapidly from the start of mixing until 20 minutes later, then became constant at 30 minutes, and stopped changing at 60 minutes. In contrast, the viscosity of the mixture (latex (L2) and MEK) remained constant from the start of mixing until the end of mixing and did not change.

[0314] Here, the mixtures obtained through each organic solvent mixing step in Examples A2 to A6 were also stirred at 300 rpm, and the viscosity of the mixtures was measured using a viscometer (BROOKFIELD DV-II+Pro digital viscometer) at 5 seconds, 5 minutes, 15 minutes, 30 minutes, 45 minutes, 60 minutes, and 90 minutes after the start of stirring. As a result, the viscosity of each mixture became constant after approximately 30 minutes, and the viscosity stopped changing after 60 minutes. Therefore, in Examples A2 to A6, it can be said that stirring was performed on the mixtures obtained through the organic solvent mixing step until the viscosity of the mixture became constant as a mixing state maintenance step.

[0315] [Table 1] The aqueous phase discharged in the separation steps of Examples A1 to A6, and the aqueous phase discharged in the washing step of Example A2, contained almost no polymer fine particles (A) and had sufficient permeability. Furthermore, the resin compositions obtained in Examples A1 to A6 contained very small amounts of emulsifier-derived elements (P and S). In contrast, the aqueous phase discharged in the separation steps of Comparative Examples A1 to A4 was cloudy and contained a large amount of polymer fine particles (A).

[0316] [Example B] Next, one embodiment of the present invention will be described based on Examples B1 to B3 and Comparative Examples B1 to B2, but the present invention is not limited to these Examples B. Each evaluation in Examples B1 to B3 and Comparative Examples B1 to B2 was performed using the method described in the section [Example A] above.

[0317] [Example B1] 756 g of methyl ethyl ketone (MEK) (solubility in water at 20°C, 10% by weight) was added as the organic solvent (B) to a 4 L tank with a stirrer (the tank had an inner diameter of 100 mm, and the stirrer consisted of four flat paddle blades with a blade diameter of 75 mm, arranged in three stages in the axial direction). Next, while stirring the raw material (MEK) in the tank at 450 rpm, 1000 g of latex (L1) containing polymer fine particles (A) obtained in Production Example 2-1 was added to the tank and stirred for 5 seconds (organic solvent mixing step). Next, the mixture in the tank (latex (L1) and MEK) was stirred further at 450 rpm for 60 minutes (maintaining mixed state step). As is clear from Figure 1, stirring the above mixture at 300 rpm for 60 minutes resulted in a constant viscosity of the mixture. In Example B1, the above mixture was stirred at 450 rpm for 60 minutes, so it can be said that the viscosity of the mixture was constant. In other words, in the mixing state maintenance step of Example B1, the mixture was stirred until the viscosity of the mixture became constant.

[0318] After the mixing state maintenance step, the mixture in the tank (latex (L1) and MEK) was stirred at 500 rpm while 800 g of purified water was continuously added to the tank at a supply rate of 200 g / min. After the supply of purified water was completed, stirring of the mixture was immediately stopped. This operation yielded a slurry liquid consisting of floating aggregates and an aqueous phase containing some organic solvent (slow aggregation step). Next, 1200 g of the aqueous phase was discharged from the outlet at the bottom of the tank so that some aggregates containing the aqueous phase remained in the tank, yielding aggregates that were purified polymer fine particles (A) and contained some aqueous phase (separation step). Furthermore, when the permeability of the discharged aqueous phase was measured, the permeability of the aqueous phase was 21%, and no turbidity of the aqueous phase was observed.

[0319] Following the separation process, a washing process (steps 1 to 3 of the second cycle) was performed. Specifically, while stirring the mixture in the tank after the separation process (aggregates of purified polymer microparticles (A) containing some aqueous phase) at 500 rpm, 450 g of purified water was continuously added to the tank at a supply rate of 200 g / min (step 1 of the second cycle). Subsequently, 120 g of MEK was added to the tank. Then, the mixture in the tank was stirred at 450 rpm for 5 minutes. This operation yielded a slurry liquid consisting of floating aggregates and an aqueous phase containing some organic solvent (step 2 of the second cycle). Next, 1000 g of the aqueous phase was discharged from the outlet at the bottom of the tank so that aggregates containing some aqueous phase remained in the tank, yielding aggregates that were purified polymer microparticles (A) and contained some aqueous phase (step 3 of the second cycle). Furthermore, when the permeability of the discharged aqueous phase was measured, the permeability of the aqueous phase was 33%, and no turbidity of the aqueous phase was observed.

[0320] To the aggregate of purified polymer fine particles (A) obtained in the third step of the second cycle, 660 g of MEK was added as the organic solvent (C). The resulting mixture was mixed for 30 minutes under stirring conditions of 500 rpm to obtain a dispersion in which polymer fine particles (A) were uniformly dispersed in MEK (redispersion step). This dispersion was placed in a 1 L tank equipped with a jacket and a stirrer (the tank had an inner diameter of 100 mm, and the stirrer was equipped with 90 mm airfoil anchor blades), and 567 g of epoxy resin (Mitsubishi Chemical Co., Ltd., trade name JER828) was added to the tank as the resin (D). The mixture was mixed until the resulting mixture was uniform (resin mixing step). Thereafter, the jacket temperature (temperature of the hot water in the tank) was set to 60°C, and the volatile components in the mixture were removed under reduced pressure using a vacuum pump (oil rotary vacuum pump, TSW-150 manufactured by Sato Vacuum Co., Ltd.) until the volatile components reached a predetermined concentration (5000 rpm) (distillation step). This procedure yielded a resin composition containing polymer fine particles (A) and epoxy resin.

[0321] The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 2 below.

[0322] [Example B2] Except for using latex (L2) obtained in Production Example 2-2 instead of latex (L1), the same method as in Example B1 was used for the organic solvent mixing step, mixing state maintenance step, slow aggregation step, separation step, and washing step (steps 1 to 3 of the second cycle) to obtain aggregates that are purified polymer fine particles (A) and contain a portion of the aqueous phase. When the permeability of the aqueous phase discharged in step 3 of the second cycle of Example B2 was measured, the permeability of the aqueous phase was 53%, and no turbidity of the aqueous phase was observed.

[0323] Next, using the aggregates of purified polymer fine particles (A) obtained in the third step of the second cycle, a redispersion step, a resin mixing step, and a distillation step were performed in the same manner as in Example B1 to obtain a resin composition containing polymer fine particles (A) and epoxy resin. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 2 below.

[0324] [Example B3] Except for using latex (L2) obtained in Production Example 2-2 instead of latex (L1), the same method as in Example B1 was used for the organic solvent mixing step, mixing state maintenance step, slow aggregation step, and separation step. Subsequently, after the separation step, the first to third steps of the first cycle were performed as a washing step. Specifically, while stirring the mixture in the tank after the separation step (aggregates containing some aqueous phase) at 500 rpm, 120 g of MEK was continuously added to the tank at a supply rate of 200 g / min (first step of the first cycle). Then, 450 g of purified water was added to the tank at a supply rate of 200 g / min. Next, the mixture in the tank was stirred at 450 rpm for 5 minutes. This operation yielded a slurry liquid consisting of floating aggregates and an aqueous phase containing some organic solvent (second step of the first cycle). Next, 1000g of the aqueous phase was discharged from the outlet at the bottom of the tank so that aggregates containing some of the aqueous phase remained in the tank, thereby obtaining aggregates that were purified polymer fine particles (A) and contained some of the aqueous phase (third step of the first cycle). Furthermore, when the permeability of the discharged aqueous phase was measured, the permeability of the aqueous phase was 54%, and no turbidity of the aqueous phase was observed.

[0325] Next, using the aggregates of purified polymer fine particles (A) obtained in the third step of the first cycle, a redispersion step, a resin mixing step, and a distillation step were performed in the same manner as in Example B1 to obtain a resin composition containing polymer fine particles (A) and epoxy resin. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 2 below.

[0326] [Comparative Example B1] Except for not performing a washing step after the separation step and using the aggregates obtained in the separation step in the subsequent redispersion step, the same method as in Example B1 was used to perform the organic solvent mixing step, mixing state maintenance step, loose aggregation step, separation step, redispersion step, resin mixing step, and distillation removal step to obtain a resin composition containing polymer fine particles (A) and epoxy resin. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 2 below.

[0327] [Comparative example B2] Except for not performing a washing step after the separation step and using the aggregates obtained in the separation step in the subsequent redispersion step, the same method as in Example B2 was used to perform the organic solvent mixing step, mixing state maintenance step, loose aggregation step, separation step, redispersion step, resin mixing step, and distillation removal step to obtain a resin composition containing polymer fine particles (A) and epoxy resin. The amount of each element (phosphorus (P) and sulfur (S)) in the obtained resin composition was measured. The results are shown in Table 2 below.

[0328] [Table 2] The resin compositions obtained in Examples B1 to B3 contained significantly lower amounts of emulsifier-derived elements (P and S), as well as their total amount, compared to the resin compositions obtained in Comparative Examples B1 and B2.

Claims

1. A step of mixing an organic solvent with a latex containing polymer microparticles (A) and an emulsifier, and an organic solvent (B), The process includes a mixing state maintenance step in which the mixture obtained in the organic solvent mixing step is either allowed to stand or stirred, or both. The emulsifier contains a lipophilic portion and a hydrophilic portion, the hydrophilic portion having a polyoxyethylene group. The hydrophilic portion contains a phosphate ester portion, A method for producing purified polymer fine particles (A), wherein in the step of maintaining the mixed state, the mixture is left to stand and / or stirred until the viscosity of the mixture becomes constant.

2. The method for producing purified polymer fine particles (A) according to claim 1, wherein in the step of maintaining the mixed state, the mixture is left to stand for 30 minutes or more.

3. A loose aggregation step is performed by bringing the mixture that has undergone the mixing state maintenance step into contact with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase, and A separation step of separating the aggregate from the aqueous phase, A method for producing purified polymer fine particles (A) according to claim 1 or 2, further comprising:

4. A method for producing purified polymer fine particles (A) according to claim 3, further comprising the step of repeating one or more cycles selected from (i) and (ii) below after the separation step: (i) A first cycle comprising: a first step of adding the organic solvent (B) to the aggregate obtained in the separation step; a second step of contacting the mixture obtained in the first step with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase, (ii) A second cycle comprising: a first step of adding water to the aggregate obtained in the separation step; a second step of contacting the mixture obtained in the first step with the organic solvent (B) to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase.

5. A step of mixing an organic solvent with a latex containing polymer microparticles (A) and an emulsifier, A loose aggregation step is performed by bringing the mixture obtained in the organic solvent mixing step into contact with water to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase, and The separation step includes separating the aggregate from the aqueous phase, The separation step is followed by a step of repeating the following cycle (ii) one or more times: The process includes a mixing state maintenance step in which the mixture obtained in the organic solvent mixing step is either allowed to stand or stirred, or both. A method for producing purified polymer fine particles (A), wherein the mixing state maintenance step involves either letting the mixture stand or stirring it, or both, until the viscosity of the mixture becomes constant: (ii) A second cycle comprising: a first step of adding water to the aggregate obtained in the separation step; a second step of contacting the mixture obtained in the first step with the organic solvent (B) to generate aggregates of polymer fine particles (A) containing the organic solvent (B) in the aqueous phase; and a third step of separating the aggregate obtained in the second step from the aqueous phase.

6. The method for producing purified polymer fine particles (A) according to claim 5, wherein in the step of maintaining the mixed state, the mixture is left to stand for 30 minutes or more.

7. A method for producing purified polymer fine particles (A) according to any one of claims 1 to 6, wherein the polymer fine particles (A) have a graft portion made of a polymer that includes as a constituent unit one or more monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyanide monomers, and (meth)acrylate monomers.

8. A method for producing a resin composition, comprising as one step a method for producing purified polymer fine particles (A) according to any one of claims 3 to 6, A redispersion step in which the aggregates separated from the aqueous phase are redispersed in an organic solvent (C), and A resin mixing step in which the dispersion obtained in the redispersion step is mixed with resin (D), A method for producing a resin composition containing [the specified element].

9. The method for producing the resin composition according to claim 8, wherein the resin (D) is a thermosetting resin.

Images