Polymer microparticles, resin modifier, and resin composition

Abstract

The purpose of the present invention is to provide polymer microparticles capable of providing a resin composition capable of providing a cured product or molded article having an excellent elastic modulus and impact resistance. The purpose is achieved by providing polymer microparticles having a volume average particle size of 0.01-1.00 μm and comprising a graft copolymer having: a crosslinked core layer containing a polymer having a specific glass transition temperature; and a shell layer graft-bonded to the crosslinked core layer, the shell layer containing a polymer having a specific glass transition temperature.

Description

Polymer microparticles, resin modifiers, and resin compositions

[0001] The present invention relates to polymer fine particles, a resin modifier, and a resin composition.

[0002] Thermosetting resins have various excellent properties, such as high heat resistance and mechanical strength, and are therefore used in a variety of fields. However, thermosetting resins suffer from the problem of insufficient impact resistance, which is a characteristic of thermosetting resins. To improve the impact resistance of thermosetting resins, a method of adding an elastomer to a thermosetting resin is widely used. Examples of such elastomers include polymer fine particles. Various particles have been developed as polymer fine particles having a core-shell structure (e.g., Patent Documents 1 and 2).

[0003] International Publication No. 2019 / 189621 Japanese Patent Publication No. 2015-182248

[0004] However, the above-mentioned conventional techniques have room for further improvement in terms of (i) the elastic modulus of a cured product obtained by curing a resin composition containing polymer microparticles or a molded product obtained by molding the resin composition, and (ii) the impact resistance of the cured product or the molded product.

[0005] One aspect of the present invention has been made in consideration of the above-mentioned problems, and its object is to provide polymer microparticles that can provide a resin composition that can provide a cured product or molded article that has excellent elastic modulus and impact resistance.

[0006] The present inventors have conducted extensive research to solve the above problems and have completed the present invention.

[0007] That is, polymer microparticles according to one embodiment of the present invention are polymer microparticles containing a graft copolymer having a crosslinked core layer and a shell layer graft-bonded to the crosslinked core layer, wherein the crosslinked core layer contains polymer C1 having a glass transition temperature of 75°C or higher, the shell layer contains polymer S having a glass transition temperature of 0°C or lower, and the volume average particle diameter is 0.01 μm to 1.00 μm.

[0008] According to one aspect of the present invention, polymer fine particles can be provided that can provide a resin composition that can provide a cured product or molded article that is excellent in elastic modulus and impact resistance.

[0009] An embodiment of the present invention will be described below, but the present invention is not limited thereto. The present invention is not limited to the respective configurations described below, and various modifications are possible within the scope of the claims. Furthermore, embodiments or examples obtained by combining the technical means disclosed in different embodiments or examples are also included in the technical scope of the present invention. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment. All academic literature and patent documents described in this specification are incorporated herein by reference. Furthermore, unless otherwise specified in this specification, the term "A to B" representing a numerical range means "greater than or equal to A (including and greater than A) and less than or equal to B (including and less than B)."

[0010] In this specification, a "structural unit derived from an X monomer" and a "structural unit derived from an X compound" contained in a polymer, copolymer, or resin may be referred to as an "X unit."

[0011] 1. Technical Concept of One Embodiment of the Present Invention As described above, the prior art such as that described in Patent Documents 1 and 2 has room for further improvement in terms of (i) the modulus of elasticity of a cured product obtained by curing a resin composition containing polymer microparticles or a molded article obtained by molding the resin composition, and (ii) the impact resistance of the cured product or the molded article.

[0012] Therefore, the present inventors have conducted extensive research with the aim of providing polymer microparticles capable of providing a resin composition capable of providing a cured product or molded article having excellent elastic modulus and impact resistance. As a result, the present inventors have independently discovered the following novel finding, which has led to the completion of the present invention: the discovery that a resin composition capable of providing a cured product or molded article having excellent elastic modulus and impact resistance can be provided by polymer microparticles containing a graft copolymer having a crosslinked core layer and a shell layer graft-bonded to the crosslinked core layer, wherein the crosslinked core layer and the shell layer each contain polymers having a specific glass transition temperature and have a specific volume average particle size.

[0013] [2. Polymer Microparticles] Polymer microparticles according to one embodiment of the present invention are polymer microparticles containing a graft copolymer having a crosslinked core layer and a shell layer graft-bonded to the crosslinked core layer, wherein the crosslinked core layer contains polymer C1 having a glass transition temperature of 75°C or higher, and the shell layer contains polymer S having a glass transition temperature of 0°C or lower, and the volume average particle size is 0.01 μm to 1.00 μm.

[0014] In this specification, "glass transition temperature" may also be referred to as "Tg." In this specification, "polymer microparticles according to one embodiment of the present invention" may also be simply referred to as "polymer microparticles of the present invention."

[0015] The polymer microparticles of the present invention have the above-mentioned constitution, and therefore have the advantage of being able to provide a resin composition that can provide a cured product or molded article that is excellent in elastic modulus and impact resistance.

[0016] Furthermore, the present polymer microparticles surprisingly have the advantage of being able to provide a resin composition that is easy to handle.

[0017] In this specification, "elastic modulus" and "impact resistance" are evaluated by "flexural modulus" and "Charpy strength", respectively. The higher the flexural modulus value of a cured product or molded product, the better the elastic modulus of the cured product or molded product. The higher the Charpy strength value of a cured product or molded product, the better the impact resistance of the cured product or molded product. In this specification, the "handleability" of a resin composition is evaluated by the "viscosity" of the resin composition (for example, the viscosity of the resin composition at 50°C). The lower the viscosity value of a resin composition, for example, at 50°C, the better the handleability of the resin composition. Methods for measuring the "flexural modulus" and "Charpy strength" of a cured product or molded product, and methods for measuring the viscosity of a resin composition will be described in detail in the examples below.

[0018] (Crosslinked Core Layer) The crosslinked core layer contains a polymer C1 having a glass transition temperature of 75° C. or higher.

[0019] (Polymer C1) The structure of polymer C1 (for example, the type and amount of structural units contained in polymer C1) is not particularly limited as long as the Tg of polymer C1 is 75°C or higher.

[0020] The Tg of a polymer can be determined by the composition of the structural units that make up the polymer, etc. In other words, the Tg of the resulting polymer can be adjusted by changing the composition of the monomers used when producing (polymerizing) the polymer.

[0021] Here, when a homopolymer is prepared by polymerizing only one type of monomer, a group of monomers that provides a homopolymer having a Tg greater than 0°C is referred to as monomer group (a).Furthermore, when a homopolymer is prepared by polymerizing only one type of monomer, a group of monomers that provides a homopolymer having a Tg of 0°C or less is referred to as monomer group (b).

[0022] Monomers that can be included in the monomer group (a) include, but are not limited to, unsubstituted vinyl aromatic compounds such as styrene and 2-vinylnaphthalene; ring-alkylated vinyl aromatic compounds such as α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, and 2,4,6-trimethylstyrene; ring-alkoxylated vinyl aromatic compounds such as 4-methoxystyrene and 4-ethoxystyrene; ring-halogenated vinyl aromatic compounds such as 2-chlorostyrene and 3-chlorostyrene; ring-ester-substituted vinyl aromatic compounds such as 4-acetoxystyrene; and ring-hydroxylated vinyl aromatic compounds such as 4-hydroxystyrene. 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; acrylic monomers including acrylic acid derivatives such as acrylonitrile, etc. Furthermore, examples of monomers that can be included in the monomer group (a) include monomers that can provide homopolymers having a Tg of 120° C. or higher when made into homopolymers, such as acrylamide, isopropylacrylamide, N-vinylpyrrolidone, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate. These monomers in the monomer group (a) may be used alone or in combination of two or more.

[0023] Examples of the monomer group (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 of the monomer group (b) may be used alone or in combination of two or more. Among these monomers of the monomer group (b), ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate are particularly preferred.

[0024] Polymer C1 may contain structural units derived from one or more monomers selected from the above-mentioned monomer group (a) and / or structural units derived from one or more monomers selected from the above-mentioned monomer group (b), so long as the Tg of the polymer C1 is 75° C. or higher. In other words, polymer C1 can be obtained by preparing a monomer mixture containing one or more monomers selected from the above-mentioned monomer group (a) and / or one or more monomers selected from the above-mentioned monomer group (b) so that the Tg of the resulting polymer is 75° C. or higher, and then polymerizing the monomer mixture.

[0025] The polymer C1 preferably contains a structural unit U1 derived from a monomer M1 that, when made into a homopolymer, gives a glass transition temperature of the homopolymer of at least 60° C. This structure has the advantage of enabling a cured product or molded article with a higher elastic modulus to be obtained.

[0026] In this specification, "a monomer M1 which, when made into a homopolymer, gives a homopolymer having a glass transition temperature of 60°C or higher" may also be referred to as "a monomer M1 whose homopolymer has a glass transition temperature of 60°C or higher" and may also be simply referred to as "monomer M1".

[0027] Examples of the monomer M1 include, among the monomer group (a) described above, (i) unsubstituted vinyl aromatic compounds such as styrene, (ii) ring-alkylated vinyl aromatic compounds such as α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, and 2,4,6-trimethylstyrene, (iii) alkyl methacrylates such as methyl methacrylate, (iv) methacrylates such as isobornyl methacrylate, and (iv) aromatic methacrylates such as phenyl methacrylate. Examples of the monomer M1 also include monomers that, when made into a homopolymer, have a glass transition temperature of 120° C. or higher, such as acrylamide, isopropylacrylamide, N-vinylpyrrolidone, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate.

[0028] It is preferable that the monomer M1 be a highly hydrophobic monomer or compound, since excessive impregnation of the shell layer into the crosslinked core layer is reduced, resulting in a cured product or molded article of polymer microparticles having excellent Charpy strength (in other words, excellent impact resistance).

[0029] The monomer M1 preferably contains (a) one or more selected from the group consisting of unsubstituted vinyl aromatic compounds, ring-alkylated vinyl aromatic compounds, alkyl methacrylates, aromatic methacrylates such as phenyl methacrylate, isobornyl methacrylate, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate, and (b) unsubstituted vinyl aromatic compounds, ring-alkylated vinyl aromatic compounds, alkyl methacrylates, phenyl methacrylate, isobornyl methacrylate, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate, because excessive impregnation of the shell layer into the crosslinked core layer is reduced, and as a result, a cured product or molded article of the polymer fine particles having excellent Charpy strength (in other words, excellent impact resistance) can be provided. It is more preferable that the compound contains one or more selected from the group consisting of substituted vinyl aromatic compounds, ring-alkylated vinyl aromatic compounds, aromatic methacrylates such as phenyl methacrylate, isobornyl methacrylate, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate; it is even more preferable that the compound contains one or more selected from the group consisting of (c) unsubstituted vinyl aromatic compounds and ring-alkylated vinyl aromatic compounds; and it is particularly preferable that the compound contains one or more selected from the group consisting of (d) unsubstituted vinyl aromatic compounds.

[0030] Since excessive impregnation of the shell layer into the crosslinked core layer is reduced, and as a result, a cured product or molded article of the polymer microparticles having excellent Charpy strength (in other words, excellent impact resistance) can be provided, it is preferable that the monomer M1 contains one or more selected from the group consisting of (a) styrene, α-methylstyrene, phenyl methacrylate, isobornyl methacrylate, and dicyclopentanyl methacrylate, it is more preferable that the monomer M1 contains (b) styrene and / or α-methylstyrene, and it is particularly preferable that the monomer M1 contains (c) styrene.

[0031] The polymer C1 preferably contains 50 wt% to 100 wt% of structural units U1 derived from a monomer M1 that, when converted into a homopolymer, gives a glass transition temperature of 60°C or higher, based on 100 wt% of the polymer C1, more preferably 60 wt% to 100 wt%, more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, and even more preferably 90 wt% to 100 wt%. The higher the content of the structural units U1 in the polymer C1, the more advantageously it is possible to obtain a cured product or molded article with a high modulus of elasticity. The polymer C1 particularly preferably contains 100 wt% of the structural units U1 based on 100 wt% of the polymer C1, i.e., it is particularly preferred that the polymer C1 is composed solely of the structural units U1.

[0032] The polymer C1 contains, in 100% by weight of the polymer C1, (i) an unsubstituted vinyl aromatic compound such as styrene, (ii) a ring-alkylated vinyl aromatic compound such as α-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2,4-dimethylstyrene, 2,5-dimethylstyrene, 3,5-dimethylstyrene, or 2,4,6-trimethylstyrene, (iii) an alkyl methacrylate such as methyl methacrylate, (iv) a methacrylate such as isobornyl methacrylate, (iv) an aromatic methacrylate such as phenyl methacrylate, and (v) a monomer (for example, acrylate) which, when made into a homopolymer, gives a glass transition temperature of the homopolymer of 120° C. or higher.

[0033] The copolymer preferably contains 50% by weight to 100% by weight, more preferably 60% by weight to 100% by weight, even more preferably 70% by weight to 100% by weight, even more preferably 80% by weight to 100% by weight, still more preferably 90% by weight to 100% by weight, and particularly preferably 100% by weight, of one or more structural units U1 derived from one or more monomers M1 selected from the group consisting of: N-vinylpyrrolidone, dicyclopentanyl methacrylate, 2-methyl-2-adamantyl methacrylate, 1-adamantyl acrylate, and 1-adamantyl methacrylate. This configuration has the advantage that (i) excessive impregnation of the shell layer into the crosslinked core layer is further reduced, resulting in a cured product or molded article of the polymer microparticles having even better Charpy strength (in other words, even better impact resistance), and (ii) a cured product or molded article having an even higher elastic modulus can be obtained.

[0033] Polymer C1 preferably contains 50% by weight to 100% by weight, more preferably 60% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, even more preferably 80% by weight to 100% by weight, even more preferably 90% by weight to 100% by weight, and particularly preferably 100% by weight, of one or more structural units U1 derived from one or more monomers M1 selected from the group consisting of styrene, α-methylstyrene, phenyl methacrylate, isobornyl methacrylate, and dicyclopentanyl methacrylate, based on 100% by weight of polymer C1. This configuration has the advantages of (i) particularly reducing excessive impregnation of the shell layer into the crosslinked core layer, thereby providing a cured product or molded article from the polymer microparticles that is particularly excellent in Charpy strength (in other words, particularly excellent in impact resistance), and (ii) particularly high elastic modulus.

[0034] The glass transition temperature of polymer C1 is preferably 76° C. or higher, more preferably 77° C. or higher, even more preferably 78° C. or higher, and particularly preferably 80° C. or higher. This configuration has the advantage that a cured product or molded article having superior heat resistance can be obtained.

[0035] The upper limit of the glass transition temperature of polymer C1 is not particularly limited. Because polymer fine particles tend to aggregate in an aggregation process of the polymer fine particles in the aqueous latex (for example, the first step described later), the glass transition temperature of polymer C1 is preferably 150° C. or lower, more preferably 120° C. or lower, even more preferably 110° C. or lower, and particularly preferably 100° C. or lower.

[0036] When the monomers used in the production (polymerization) of polymer C1 are known, the glass transition temperature (Tg) of polymer C1 can be calculated using the FOX formula (Formula 1) shown below: 1 / Tg=w １ / Tg １ +w ２ / Tg ２ +...+w ｎ / Tg ｎ (Formula 1); where Tg １, Tg ２ , ..., Tg ｎ are the Tg (K) and w of the homopolymers of the components constituting the graft portion (i.e., the monomers used in the production of the graft portion) 1, 2, ..., n, respectively. １ , w ２ ,...,w ｎ are the weight fractions of the components constituting the graft portion (i.e., the monomers used in producing the graft portion) 1, 2, ..., n, respectively. The Tg of the homopolymer can be, for example, the value described in "Polymer Handbook Fourth Edition" (edited by J. Brandup et al., Jphn Wiley & Sons, Inc.).

[0037] Furthermore, when the monomer used in the production (polymerization) of polymer C1 is unknown, viscoelasticity measurement (shear method, measurement frequency: 1 Hz) of polymer fine particles is performed to obtain a graph of loss tangent (tan δ), and the peak temperature in the obtained graph may be used as Tg. Here, when multiple peaks are obtained in the tan δ graph, the glass transition temperature of polymer C1 can be determined by combining the peaks with other analytical data such as composition analysis.

[0038] The crosslinked core layer may be a single layer, or may be a multi-layer consisting of two or more crosslinked core layers.

[0039] When the crosslinked core layer is a multi-layer structure, it is preferred that the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed on the outside of the first crosslinked core layer. This configuration has the advantage that a cured product or molded article having superior toughness can be obtained.

[0040] In this specification, "toughness" is evaluated by "K1c" (fracture toughness value). The higher the K1c value of a cured product or molded body, the more excellent the toughness of the cured product or molded body. The method for measuring the "K1c" of a cured product or molded body will be explained in detail in the Examples below.

[0041] The crosslinked core layer may have three or more layers, including a first crosslinked core layer, a second crosslinked core layer formed on the outside of the first crosslinked core layer, and a third crosslinked core layer formed on the outside of the second crosslinked core layer.

[0042] A case where the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer will be described. In this specification, the phrase "the second crosslinked core layer is formed outside the first crosslinked core layer" means that the second crosslinked core layer is formed after the formation of the first crosslinked core layer. It is preferable that at least a portion of the second crosslinked core layer is present outside the first crosslinked core layer, and the entire second crosslinked core layer does not have to be present outside the first crosslinked core layer. In this specification, "the second crosslinked core layer is present outside the first crosslinked core layer" can also be said to mean "the second crosslinked core layer covers the first crosslinked core layer." In other words, it is preferable that at least a portion of the second crosslinked core layer covers at least a portion of the first crosslinked core layer, and the entire second crosslinked core layer does not have to cover the first crosslinked core layer. The entire second crosslinked core layer may at least partially or entirely cover the first crosslinked core layer, and the entire second crosslinked core layer may be present outside the first crosslinked core layer.

[0043] For example, when obtaining a first crosslinked core layer and a second crosslinked core layer by emulsion polymerization, if, after completing the polymerization of the first crosslinked core layer, the second crosslinked core layer is subsequently polymerized in the presence of the first crosslinked core layer using an aqueous latex containing the first crosslinked core layer, a crosslinked core layer having a first crosslinked core layer and a second core layer, at least a portion of the second crosslinked core layer being present outside the first crosslinked core layer (in other words, at least a portion of the second crosslinked core layer covering at least a portion of the first crosslinked core layer) can be obtained.

[0044] When the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer, it is preferable that the first crosslinked core layer contains polymer C1 and the second crosslinked core layer contains polymer C2 having a glass transition temperature of 0° C. or lower. This configuration has the advantage of being able to obtain a cured product or molded article with superior toughness.

[0045] (Polymer C2) The structure of polymer C2 (for example, the type and amount of structural units contained in polymer C2) is not particularly limited as long as the glass transition temperature of polymer C2 is 0°C or lower.

[0046] Polymer C2 may contain structural units derived from one or more monomers selected from the above-mentioned monomer group (a) and / or structural units derived from one or more monomers selected from the above-mentioned monomer group (b), so long as the Tg is 0° C. or less. In other words, polymer C2 can be obtained by preparing a monomer mixture containing one or more monomers selected from the above-mentioned monomer group (a) and / or one or more monomers selected from the above-mentioned monomer group (b) so that the Tg of the resulting polymer is 0° C. or less, and then polymerizing the monomer mixture.

[0047] Polymer C2 preferably contains a structural unit U2 derived from a monomer M2 that, when made into a homopolymer, results in a homopolymer with a glass transition temperature of 0° C. or lower. This structure has the advantage of enabling a cured product or molded article with superior toughness to be obtained.

[0048] In this specification, "monomer M2 which, when made into a homopolymer, gives a homopolymer with a glass transition temperature of 0°C or lower" may also be referred to as "monomer M2 whose homopolymer has a glass transition temperature of 0°C or lower", and may also be simply referred to as "monomer M2".

[0049] Examples of the monomer M2 include a monomer selected from the above-mentioned monomer group (b).

[0050] On the other hand, from the viewpoint of emulsion polymerization properties, polymer C2 preferably contains one or more structural units selected from the group consisting of an aromatic vinyl unit derived from an aromatic vinyl monomer, a vinyl cyan unit derived from a vinyl cyan monomer, and a (meth)acrylate unit derived from a (meth)acrylate monomer.

[0051] Specific examples of aromatic vinyl monomers include styrene, α-methylstyrene, p-methylstyrene, and divinylbenzene.

[0052] Specific examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile.

[0053] Specific examples of the (meth)acrylate monomer include: (a) alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; (b) aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; and (c) 2-hydroxyethyl methacrylate and 4-hydroxybutyl methacrylate. (d) glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidyl alkyl (meth)acrylate; (e) alkoxyalkyl methacrylates; (f) allyl alkyl methacrylates such as allyl methacrylate and allyl alkyl methacrylate; and (g) polyfunctional (meth)acrylates such as monoethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate.

[0054] Among the monomer group (b) described above, the structural unit U2 preferably contains a (meth)acrylate unit derived from a (meth)acrylate monomer, more preferably contains one or more units selected from the group consisting of ethyl acrylate units, butyl acrylate units, 2-ethylhexyl acrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, 2-hydroxyethyl acrylate units, and 4-hydroxybutyl acrylate units, and particularly preferably contains a butyl acrylate unit. This configuration has the advantages of (i) excellent emulsion polymerization properties, and (ii) the ability to obtain a cured product or molded article with even greater toughness.

[0055] Polymer C2 preferably contains 50 wt% to 100 wt% of the structural unit U2, more preferably 60 wt% to 100 wt%, more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, and even more preferably 90 wt% to 100 wt% of the structural unit U2, based on 100 wt% of the polymer C2. The higher the content of the structural unit U2 in polymer C2, the more advantageously it is possible to obtain a cured product or molded article with superior toughness. Polymer C2 particularly preferably contains 100 wt% of the structural unit U2, based on 100 wt% of the polymer C2. In other words, it is particularly preferable that polymer C2 is composed solely of the structural unit U2.

[0056] Since a cured product or molded article having particularly excellent toughness can be obtained, polymer C2 preferably contains 50 wt% to 100 wt%, more preferably 60 wt% to 100 wt%, more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, even more preferably 90 wt% to 100 wt%, and particularly preferably 100 wt%, of one or more units selected from the group consisting of ethyl acrylate units, butyl acrylate units, 2-ethylhexyl acrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, 2-hydroxyethyl acrylate units, and 4-hydroxybutyl acrylate units, based on 100 wt% of polymer C2.

[0057] Polymer C2 may contain a structural unit derived from a monomer other than monomer M2, as long as the Tg is 0° C. or lower. Polymer C2 may contain, for example, a structural unit derived from the above-mentioned monomer group (a).

[0058] The case where polymer C2 contains a structural unit derived from a monomer other than monomer M2 (hereinafter also referred to as "Case A") will be described. In Case A, the monomer other than monomer M2 is preferably one or more monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyan monomers, and (meth)acrylate monomers.

[0059] Polymer C2 preferably contains 50 wt% to 100 wt%, more preferably 60 wt% to 100 wt%, more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, and even more preferably 90 wt% to 100 wt% of one or more structural units selected from the group consisting of aromatic vinyl units, vinyl cyan units, and (meth)acrylate units, based on 100 wt% of polymer C2. Polymer C2 particularly preferably contains 100 wt% of one or more structural units selected from the group consisting of aromatic vinyl units, vinyl cyan units, and (meth)acrylate units, based on 100 wt% of polymer C2, i.e., polymer C2 is particularly preferably composed solely of one or more structural units selected from the group consisting of aromatic vinyl units, vinyl cyan units, and (meth)acrylate units.

[0060] Polymer C2 more preferably (a) contains one or more units selected from the group consisting of (meth)acrylate units, (b) contains a butyl acrylate unit as the structural unit U2, and as a structural unit other than structural unit U2, contains one or more units selected from the group consisting of methyl (meth)acrylate units, ethyl methacrylate units, butyl methacrylate units, 2-ethylhexyl methacrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, stearyl (meth)acrylate units, phenoxyethyl (meth)acrylate units, benzyl (meth)acrylate units, styrene units, α-methylstyrene units, p-methylstyrene units, acrylonitrile units, and methacrylonitrile units, and (c) contains a butyl acrylate unit as the structural unit U2, and as a structural unit other than structural unit U2, contains a methyl acrylate unit. This configuration has the advantage of excellent emulsion polymerizability.

[0061] Polymer C2 preferably contains, based on 100% by weight of polymer C2, 50% by weight to 100% by weight, more preferably 60% by weight to 100% by weight, still more preferably 70% by weight to 100% by weight, even more preferably 80% by weight to 100% by weight, and particularly preferably 90% by weight to 100% by weight, of (a) butyl acrylate units and (b) one or more structural units selected from the group consisting of methyl (meth)acrylate units, ethyl methacrylate units, butyl methacrylate units, 2-ethylhexyl methacrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, stearyl (meth)acrylate units, phenoxyethyl (meth)acrylate units, benzyl (meth)acrylate units, styrene units, α-methylstyrene units, p-methylstyrene units, acrylonitrile units, and methacrylonitrile units in total. This configuration has the advantage of providing even better emulsion polymerization properties.

[0062] The glass transition temperature of polymer C2 is 0° C. or lower, preferably −5° C. or lower, more preferably −10° C. or lower, even more preferably −15° C. or lower, and particularly preferably −20° C. or lower. This configuration has the advantage that a cured product or molded article having superior toughness can be obtained.

[0063] The lower limit of the glass transition temperature of polymer C2 is not particularly limited. The glass transition temperature of polymer C2 is preferably −80° C. or higher, more preferably −70° C. or higher, even more preferably −60° C. or higher, and particularly preferably −50° C. or higher. This configuration has the advantage that the polymer fine particles in the aqueous latex (or the polymer fine particles during polymerization) exist in the state of primary particles without agglomeration, thereby improving the storage stability and stability during polymerization of the aqueous latex.

[0064] When the monomer used in the production (polymerization) of polymer C2 is known, the glass transition temperature (Tg) of polymer C2 can be calculated using the above-mentioned FOX formula (Equation 1). Alternatively, when the monomer used in the production (polymerization) of polymer C2 is unknown, viscoelasticity measurements (shear method, measurement frequency: 1 Hz) are performed on polymer microparticles to obtain a loss tangent (tan δ) graph, and the peak temperature in the obtained graph can be used as Tg. Here, when multiple peaks are obtained in the tan δ graph, the glass transition temperature of polymer C2 can be determined by combining this with other analytical data such as composition analysis.

[0065] The case where the crosslinked core layer is a single layer will be described. In this case, the crosslinked core layer preferably contains 80% or more of polymer C1, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 100% by weight, of the crosslinked core layer. That is, when the crosslinked core layer is a single layer, it is particularly preferable that the crosslinked core layer is composed only of polymer C1. When the crosslinked core layer is a single layer, if the content of polymer C1 in the crosslinked core layer is within the above-mentioned range, there is an advantage that a cured product or molded article with superior toughness can be obtained.

[0066] A case where the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer (hereinafter also referred to as "Case B") will be described. In Case B, the first crosslinked core layer preferably contains 80% or more of polymer C1, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 100% by weight, of the first crosslinked core layer. That is, in Case B, it is particularly preferred that the first crosslinked core layer be composed solely of polymer C1. In Case B, when the content of polymer C1 in the first crosslinked core layer is within the above-mentioned range, it is advantageous to be able to obtain a cured product or molded article with superior toughness. Furthermore, in Case B, the second crosslinked core layer preferably contains 80% or more of polymer C2, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 100% by weight, of the second crosslinked core layer. That is, in Case B, it is particularly preferred that the second crosslinked core layer be composed solely of polymer C2. In Case B, when the content of polymer C2 in the second crosslinked core layer is within the above-mentioned range, there is an advantage that a cured product or molded article with even more excellent toughness can be obtained.

[0067] The crosslinked core layer is crosslinked. Specifically, at least polymer C1 is crosslinked.

[0068] The crosslinked polymer C1 has the advantage that a cured product or molded article having a higher elastic modulus can be obtained.

[0069] It is also preferred that polymer C2 be crosslinked. This has the advantage that a cured product or molded article having superior toughness can be obtained.

[0070] A commonly used method can be used to introduce a crosslinked structure into polymer C1 and polymer C2, for example, by mixing a crosslinkable monomer such as a polyfunctional monomer and / or a mercapto group-containing compound with monomers M1 and M2 as monomers to be used in the production (polymerization) of polymer C1 and polymer C2, and polymerizing the resulting monomer mixture.

[0071] At least polymer C1 has a structural unit derived from a crosslinkable monomer, that is, a crosslinkable unit (for example, a polyfunctional unit and / or a structural unit derived from a mercapto group-containing compound).

[0072] A polyfunctional monomer can also be said to be a monomer having two or more radically polymerizable reactive groups in the same molecule. The radically polymerizable reactive group is preferably a carbon-carbon double bond. Examples of polyfunctional monomers include (meth)acrylates having an ethylenically unsaturated double bond, such as allyl alkyl (meth)acrylates and allyloxy alkyl (meth)acrylates, and do not include butadiene. 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 the 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 the 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. Furthermore, examples of monomers having five (meth)acrylic groups include dipentaerythritol penta(meth)acrylate. Furthermore, examples of monomers having six (meth)acrylic groups include ditrimethylolpropane hexa(meth)acrylate.Polyfunctional monomers also include, for example, diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, divinylbenzene, and the like.

[0073] These polyfunctional monomers may be used alone or in combination of two or more.

[0074] Among the above-mentioned polyfunctional monomers, allyl methacrylate, diallyl phthalate, triallyl isocyanurate, divinylbenzene, etc. are preferably used in crosslinking the polymer C1 and the polymer C2 from the viewpoint of emulsion polymerization properties.

[0075] Polymer C1 preferably contains, as a crosslinkable unit, one or more selected from the group consisting of an allyl methacrylate unit, a diallyl phthalate unit, a triallyl isocyanurate unit, and a divinylbenzene unit. When polymer C2 is crosslinked, polymer C2 preferably contains, as a crosslinkable unit, one or more selected from the group consisting of an allyl methacrylate unit, a diallyl phthalate unit, a triallyl isocyanurate unit, and a divinylbenzene unit.

[0076] The polymer C1 preferably (a) contains the structural unit U1 and a crosslinkable unit or is composed solely of these structural units; (b) more preferably contains (b-1) one or more structural units selected from the group consisting of a styrene unit, an α-methylstyrene unit, a phenyl methacrylate unit, an isobornyl methacrylate unit, and a dicyclopentanyl methacrylate unit, and (b-2) one or more structural units selected from the group consisting of an allyl methacrylate unit, a diallyl phthalate unit, a triallyl isocyanurate unit, and a divinylbenzene unit or is composed solely of these structural units; and it is particularly preferably (c) contains a styrene unit and an allyl methacrylate unit or is composed solely of these structural units.

[0077] Polymer C2 preferably contains (a) (a-1) structural unit U2, (a-2) one or more structural units selected from the group consisting of methyl (meth)acrylate units, ethyl methacrylate units, butyl methacrylate units, 2-ethylhexyl methacrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, stearyl (meth)acrylate units, phenoxyethyl (meth)acrylate units, benzyl (meth)acrylate units, styrene units, α-methylstyrene units, p-methylstyrene units, acrylonitrile units, and methacrylonitrile units, and (a-3) a crosslinkable unit, or is composed solely of these structural units; and (b) (b-1) one or more structural units selected from the group consisting of ethyl acrylate units, butyl acrylate units, 2-ethylhexyl acrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, 2-hydroxyethyl acrylate units, and 4-hydroxybutyl acrylate units. (b-1) one or more structural units selected from the group consisting of acrylate units, (b-2) one or more structural units selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, styrene, α-methylstyrene, p-methylstyrene, acrylonitrile, and methacrylonitrile, and (b-3) one or more structural units selected from the group consisting of allyl methacrylate, diallyl phthalate, triallyl isocyanurate, and divinylbenzene, or being composed solely of these structural units; and (c) it is particularly preferable to include (c) a butyl acrylate unit, a methyl acrylate unit, and an allyl methacrylate unit, or being composed solely of these structural units.

[0078] (Shell Layer) The graft copolymer includes a shell layer grafted to the crosslinked core layer. When the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer, the shell layer may be grafted to at least one of the first crosslinked core layer and the second crosslinked core layer. It is preferable that at least a portion of the shell layer covers at least a portion of the crosslinked core layer. The entire shell layer does not have to cover the entire crosslinked core layer. When the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer, it is preferable that at least a portion of the shell layer covers at least a portion of at least one of the first crosslinked core layer and the second crosslinked core layer. The shell layer may be present in the outermost layer (in other words, the surface) of the graft copolymer, or in the outermost layer (in other words, the surface) of the polymer microparticles.

[0079] The shell layer contains a polymer S having a glass transition temperature of 0° C. or lower.

[0080] (Polymer S) The constitution of the polymer S (for example, the type and amount of structural units contained in the polymer S) is not particularly limited as long as the glass transition temperature of the polymer S is 0° C. or lower.

[0081] Polymer S may contain structural units derived from one or more monomers selected from the above-mentioned monomer group (a) and / or structural units derived from one or more monomers selected from the above-mentioned monomer group (b), so long as the Tg is 0° C. or less. In other words, polymer S can be obtained by preparing a monomer mixture containing one or more monomers selected from the above-mentioned monomer group (a) and / or one or more monomers selected from the above-mentioned monomer group (b) so that the Tg of the resulting polymer is 0° C. or less, and then polymerizing the monomer mixture.

[0082] The polymer S preferably contains a structural unit U3 derived from a monomer M3 that, when made into a homopolymer, results in a homopolymer having a glass transition temperature of 0° C. or lower. This structure has the advantage of enabling a cured product or molded article having superior toughness to be obtained.

[0083] In this specification, "monomer M3 which, when made into a homopolymer, gives a homopolymer with a glass transition temperature of 0°C or lower" may also be referred to as "monomer M3 whose homopolymer has a glass transition temperature of 0°C or lower" and may also be simply referred to as "monomer M3".

[0084] Examples of the monomer M3 include a monomer selected from the above-mentioned monomer group (b).

[0085] On the other hand, from the viewpoint of emulsion polymerization properties, the polymer S preferably contains one or more structural units selected from the group consisting of aromatic vinyl units, vinylcyan units, and (meth)acrylate units.

[0086] Specific examples of the aromatic vinyl monomer, the vinyl cyan monomer, and the (meth)acrylate monomer are the same as those explained in the section (Polymer C2) above, and therefore, the explanation therefor is omitted here.

[0087] Among the monomer group (b) described above, the structural unit U3 preferably contains a (meth)acrylate unit derived from a (meth)acrylate monomer, more preferably contains one or more selected from the group consisting of an ethyl acrylate unit, a butyl acrylate unit, a 2-ethylhexyl acrylate unit, an octyl (meth)acrylate unit, a dodecyl (meth)acrylate unit, a 2-hydroxyethyl acrylate unit, and a 4-hydroxybutyl acrylate unit, and particularly preferably contains a butyl acrylate unit. This configuration has the advantages of (i) excellent emulsion polymerization properties and (ii) the ability to obtain a cured product or molded article with even greater toughness.

[0088] Polymer S preferably contains 50 wt% to 100 wt% of the structural unit U3, more preferably 60 wt% to 100 wt%, more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, and even more preferably 90 wt% to 100 wt% of the structural unit U3, based on 100 wt% of the polymer S. The higher the content of the structural unit U3 in polymer S, the more advantageously it is possible to obtain a cured product or molded article with superior toughness. Polymer S particularly preferably contains 100 wt% of the structural unit U3, based on 100 wt% of the polymer S; that is, it is particularly preferred that polymer S is composed solely of structural unit U3.

[0089] Since a cured product or molded article having particularly excellent toughness can be obtained, Polymer S preferably contains 50 wt% to 100 wt%, more preferably 60 wt% to 100 wt%, even more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, even more preferably 90 wt% to 100 wt%, and particularly preferably 100 wt% of one or more units selected from the group consisting of ethyl acrylate units, butyl acrylate units, 2-ethylhexyl acrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, 2-hydroxyethyl acrylate units, and 4-hydroxybutyl acrylate units, based on 100 wt% of Polymer S.

[0090] Polymer S may contain a structural unit derived from a monomer other than monomer M3, as long as the Tg is 0° C. or lower. Polymer S may contain, for example, a structural unit derived from the above-mentioned monomer group (a).

[0091] The case where polymer S contains a structural unit derived from a monomer other than monomer M3 (hereinafter also referred to as "case C") will be described. In case C, the monomer other than monomer M3 is preferably one or more monomers selected from the group consisting of aromatic vinyl monomers, vinyl cyan monomers, and (meth)acrylate monomers.

[0092] Polymer S preferably contains 50 wt% to 100 wt%, more preferably 60 wt% to 100 wt%, more preferably 70 wt% to 100 wt%, even more preferably 80 wt% to 100 wt%, and even more preferably 90 wt% to 100 wt% of one or more structural units selected from the group consisting of aromatic vinyl units, vinyl cyan units, and (meth)acrylate units, based on 100 wt% of the polymer S. Polymer S particularly preferably contains 100 wt% of one or more structural units selected from the group consisting of aromatic vinyl units, vinyl cyan units, and (meth)acrylate units, based on 100 wt% of the polymer S, i.e., it is particularly preferred that polymer S is composed solely of one or more structural units selected from the group consisting of aromatic vinyl units, vinyl cyan units, and (meth)acrylate units.

[0093] Polymer S more preferably contains (a) one or more units selected from the group consisting of (meth)acrylate units, (b) a butyl acrylate unit as structural unit U3, and more preferably contains one or more structural units selected from the group consisting of methyl (meth)acrylate units, ethyl methacrylate units, butyl methacrylate units, 2-ethylhexyl methacrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, stearyl (meth)acrylate units, phenoxyethyl (meth)acrylate units, benzyl (meth)acrylate units, styrene units, α-methylstyrene units, p-methylstyrene units, acrylonitrile units, and methacrylonitrile units as structural units other than structural unit U3, and (c) a butyl acrylate unit as structural unit U3, and even more preferably contains a methyl acrylate unit as a structural unit other than structural unit U3. This configuration has the advantage of excellent emulsion polymerizability.

[0094] Polymer S preferably contains, based on 100% by weight of polymer S, 50% by weight to 100% by weight, more preferably 60% by weight to 100% by weight, even more preferably 70% by weight to 100% by weight, even more preferably 80% by weight to 100% by weight, and particularly preferably 90% by weight to 100% by weight, of (a) butyl acrylate units and (b) one or more structural units selected from the group consisting of methyl (meth)acrylate units, ethyl methacrylate units, butyl methacrylate units, 2-ethylhexyl methacrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, stearyl (meth)acrylate units, phenoxyethyl (meth)acrylate units, benzyl (meth)acrylate units, styrene units, α-methylstyrene units, p-methylstyrene units, acrylonitrile units, and methacrylonitrile units in total. This configuration has the advantage of providing even better emulsion polymerization properties.

[0095] The glass transition temperature of the polymer S is 0° C. or lower, preferably −5° C. or lower, more preferably −10° C. or lower, even more preferably −15° C. or lower, and particularly preferably −20° C. or lower. This configuration has the advantage that a cured product or molded article having superior toughness can be obtained.

[0096] There is no particular limitation on the lower limit of the glass transition temperature of the polymer S. The glass transition temperature of the polymer S is preferably −80° C. or higher, more preferably −70° C. or higher, even more preferably −60° C. or higher, and particularly preferably −50° C. or higher. This configuration has the advantage that the polymer fine particles in the aqueous latex (or the polymer fine particles during polymerization) exist in the state of primary particles without agglomeration, thereby improving the storage stability and stability during polymerization of the aqueous latex.

[0097] When the monomer used in the production (polymerization) of polymer S is known, the glass transition temperature (Tg) of polymer S can be calculated using the above-mentioned FOX formula (Equation 1). Alternatively, when the monomer used in the production (polymerization) of polymer S is unknown, viscoelasticity measurements (shear method, measurement frequency: 1 Hz) are performed on polymer microparticles to obtain a loss tangent (tan δ) graph, and the peak temperature in the obtained graph can be used as Tg. Here, when multiple peaks are obtained in the tan δ graph, the glass transition temperature of polymer S can be determined by combining this with other analytical data such as composition analysis.

[0098] The shell layer preferably contains 80% or more of polymer S, more preferably 90% or more, even more preferably 95% or more, and particularly preferably 100% by weight, of the shell layer. That is, it is particularly preferable that the shell layer is composed only of polymer S. When the content of polymer S in the shell layer is within the above-mentioned range, there is an advantage that a cured product or molded article with superior toughness can be obtained.

[0099] The shell layer may contain a polymer other than the polymer S.

[0100] The shell layer preferably contains a structural unit having an epoxy group. This allows the shell layer of the polymer microparticles to be chemically bonded to the matrix resin in the resin composition. This allows the polymer microparticles to be maintained in a well-dispersed state without agglomeration in the resin composition or in a cured or molded product thereof.

[0101] To obtain a shell layer containing a structural unit having an epoxy group, a monomer having an epoxy group may be used in the production of the shell layer (for example, in the polymerization of polymer S). Specific examples of the monomer having an epoxy group include glycidyl group-containing vinyl monomers such as glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and allyl glycidyl ether. In this specification, (meth)acrylate refers to acrylate and / or methacrylate.

[0102] The above-mentioned epoxy group-containing monomers may be used alone or in combination of two or more.

[0103] The shell layer preferably contains, based on 100% by weight of the shell layer, more preferably from 0% to 50% by weight of structural units having an epoxy group, more preferably from 1% to 40% by weight, even more preferably from 3% to 30% by weight, particularly preferably from 3% to 20% by weight, and most preferably from 3% to 16% by weight. When the shell layer contains, based on 100% by weight of the shell layer, (a) more than 0% by weight of structural units derived from a monomer having an epoxy group, the resulting resin composition can provide a cured product or molded article having sufficient impact resistance, and when (b) 50% by weight or less, the resulting resin composition can provide a cured product or molded article having sufficient impact resistance, and has the advantage of having good storage stability.

[0104] The structural unit having an epoxy group is preferably contained in the polymer S. In other words, the polymer S preferably contains a structural unit having an epoxy group. This configuration has the advantage of improving the dispersibility of the polymer microparticles.

[0105] Polymer S preferably contains more than 0 wt% and not more than 50 wt%, more preferably 1 wt% to 40 wt%, even more preferably 3 wt% to 30 wt%, particularly preferably 3 wt% to 20 wt%, and most preferably 3 wt% to 16 wt%, of structural units having an epoxy group, based on 100 wt% of polymer S. When polymer S contains (a) more than 0 wt% of structural units derived from a monomer having an epoxy group, based on 100 wt% of polymer S, the resulting resin composition can provide a cured product or molded article having sufficient impact resistance, and when (b) not more than 50 wt%, the resulting resin composition can provide a cured product or molded article having sufficient impact resistance, and has the advantage of having good storage stability.

[0106] The shell layer is preferably not crosslinked, in other words, is preferably non-crosslinked.

[0107] The content of crosslinkable monomers such as polyfunctional monomers and / or mercapto group-containing compounds in the shell layer is preferably as low as possible. For example, the content is preferably 5.0 wt % or less, more preferably 3.0 wt % or less, even more preferably 1.0 wt % or less, and particularly preferably 0.1 wt % or less, based on 100 wt % of the shell layer.

[0108] The polymer S is preferably not crosslinked, in other words, is preferably non-crosslinked.

[0109] The content of crosslinkable monomers such as polyfunctional monomers and / or mercapto group-containing compounds in the polymer S is preferably as small as possible. For example, the content is preferably 5.0% by weight or less, more preferably 3.0% by weight or less, even more preferably 1.0% by weight or less, and particularly preferably 0.1% by weight or less, based on 100% by weight of the polymer S.

[0110] The polymer S preferably contains (a) (a-1) the structural unit U3, (a-2) one or more structural units selected from the group consisting of a methyl (meth)acrylate unit, an ethyl methacrylate unit, a butyl methacrylate unit, a 2-ethylhexyl methacrylate unit, an octyl (meth)acrylate unit, a dodecyl (meth)acrylate unit, a stearyl (meth)acrylate unit, a phenoxyethyl (meth)acrylate unit, a benzyl (meth)acrylate unit, a styrene unit, an α-methylstyrene unit, a p-methylstyrene unit, an acrylonitrile unit, and a methacrylonitrile unit, and (a-3) a glycidyl group-containing vinyl unit, or is composed solely of these structural units; and (b) (b-1) an ethyl acrylate unit, a butyl acrylate unit, a 2-ethylhexyl acrylate unit, an octyl (meth)acrylate unit, a dodecyl (meth)acrylate unit, a 2-hydroxyethyl acrylate unit, and a 4-hydroxybutyl acrylate unit. (b-1) is a methyl acrylate copolymer having a structure similar to that of (b-1), (b-2) one or more structural units selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, styrene, α-methylstyrene, p-methylstyrene, acrylonitrile, and methacrylonitrile, and (b-3) one or more structural units selected from the group consisting of glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and allyl glycidyl ether, or is composed solely of these structural units; and (c) is particularly preferably composed solely of butyl acrylate units, methyl acrylate units, and glycidyl methacrylate units.

[0111] The content ratio of the crosslinked core layer and the shell layer in the graft copolymer is preferably 30% by weight to 90% by weight of the crosslinked core layer and 10% by weight to 70% by weight of the shell layer, more preferably 35% by weight to 90% by weight of the crosslinked core layer and 10% by weight to 65% by weight of the shell layer, still more preferably 40% by weight to 85% by weight of the crosslinked core layer and 15% by weight to 60% by weight of the shell layer, particularly preferably 45% by weight to 85% by weight of the crosslinked core layer and 15% by weight to 55% by weight of the shell layer, and most preferably 50% by weight to 80% by weight of the crosslinked core layer and 20% by weight to 50% by weight of the shell layer, relative to 100% by weight of the graft copolymer.

[0112] The polymer fine particles may be composed solely of the graft copolymer.

[0113] (Volume average particle diameter (Mv) of polymer microparticles) The volume average particle diameter of the present polymer microparticles is 0.01 μm to 1.00 μm. This configuration has the advantage of being able to obtain a cured product or molded article with superior toughness. The volume average particle diameter of the present polymer microparticles is preferably 0.05 μm to 0.80 μm, more preferably 0.10 μm to 0.60 μm, even more preferably 0.13 μm to 0.40 μm, and particularly preferably 0.15 μm to 0.30 μm. The method for measuring the volume average particle diameter of the polymer microparticles will be described in detail in the Examples below.

[0114] (Method for Producing Polymer Microparticles (Graft Copolymers)) Polymer microparticles (graft copolymers) can be produced by known methods (e.g., emulsion polymerization, suspension polymerization, microsuspension polymerization, etc.). Specifically, the polymerization of the crosslinked core layer (e.g., polymer C1 and optionally polymer C2) and the graft polymerization of the polymer constituting the shell layer (e.g., polymer S) can both be carried out by known methods (e.g., emulsion polymerization, suspension polymerization, microsuspension polymerization, etc.). Among these, emulsion polymerization is particularly preferred as a method for producing polymer microparticles (graft copolymers). Emulsion polymerization has the following advantages: (a) the composition of the polymer microparticles (graft copolymers) can be easily designed; (b) industrial production of the polymer microparticles (graft copolymers) is easy; and (c) a latex containing polymer microparticles (graft copolymers) that can be suitably used in the production of the present resin composition can be easily obtained. As a method for obtaining polymer microparticles by emulsion polymerization, for example, the method described in International Publication WO 2005 / 028546 can also be used.

[0115] As an example, polymer microparticles (graft copolymers) can be produced by polymerizing a crosslinked core layer (e.g., polymer C1 and optionally polymer C2) and then graft polymerizing a polymer (e.g., polymer S) that constitutes a shell layer in the presence of the crosslinked core layer. A crosslinked core layer having a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer can be produced by polymerizing the first crosslinked core layer and then polymerizing a polymer that constitutes the second crosslinked core layer in the presence of the first crosslinked core layer. For example, a crosslinked core layer having a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer can be obtained by polymerizing polymer C1 and then polymerizing polymer C2 in the presence of polymer C1.

[0116] A known polymerization initiator can be used to produce the polymer microparticles. A known surfactant can be used to produce the polymer microparticles. When the polymer microparticles are produced by emulsion polymerization, a known emulsifier can be used.

[0117] In the production of polymer microparticles, conditions within known numerical ranges can be applied to the polymerization conditions such as polymerization temperature, pressure, and deoxidation.

[0118] [3. Resin Modifier] A resin modifier according to one embodiment of the present invention contains the polymer fine particles described in the above section [2. Polymer Fine Particles].

[0119] In this specification, the "resin modifier according to one embodiment of the present invention" may hereinafter be simply referred to as the "modifier of the present invention."

[0120] The present modifier has the advantage that the resin composition obtained by mixing the modifier with a thermosetting resin can provide a cured product or molded article having excellent elastic modulus and impact resistance. The present modifier also has the advantage that the resin composition obtained by mixing the modifier with a thermosetting resin has excellent handleability.

[0121] The thermosetting resin to which this modifier is to be blended will be explained in the section below (Matrix Resin).

[0122] The present modifier may contain, as additives other than the polymer fine particles, for example, inorganic fillers, organic fillers, antiblocking agents, curing agents, colorants such as pigments and dyes, extender pigments, ultraviolet absorbers, antioxidants, heat stabilizers (antigelling agents), plasticizers, leveling agents, antifoaming agents, silane coupling agents, antistatic agents, flame retardants, lubricants, viscosity reducers, shrinkage reducing agents, drying agents, and dispersants.

[0123] (Method for producing a resin modifier) ​​The polymer microparticles obtained by the method described in the above section (Method for producing polymer microparticles (graft copolymers)) can be used as a resin modifier. For example, an aqueous latex containing polymer microparticles obtained by the method described in the above section (Method for producing polymer microparticles) can be used as a resin modifier. In addition, an aqueous latex obtained by adding the above-mentioned additives to an aqueous latex containing polymer microparticles can be used as a resin modifier.

[0124] [4. Resin Composition] A resin composition according to one embodiment of the present invention contains the polymer microparticles described in the section [2. Polymer Microparticles] above and a matrix resin, and the polymer microparticles account for 15 to 50% by weight and the matrix resin for 50 to 85% by weight, relative to 100% by weight of the total of the polymer microparticles and the matrix resin.

[0125] Alternatively, a resin composition in one embodiment of the present invention contains the resin modifier described in the above section [3. Resin Modifier] and a matrix resin, and the polymer fine particles account for 15 to 50% by weight and the matrix resin for 50 to 85% by weight, relative to 100% by weight of the total of the polymer fine particles and the matrix resin.

[0126] In this specification, the "resin composition according to one embodiment of the present invention" may hereinafter be simply referred to as the "resin composition".

[0127] The resin composition has the advantage that it can provide a cured product or molded article having excellent elastic modulus and impact resistance. The resin composition also has the advantage of being easy to handle.

[0128] (Matrix Resin) The matrix resin is not particularly limited, but is preferably a thermosetting resin, since it can provide a cured product with an excellent balance between elastic modulus and strength.

[0129] The thermosetting resin preferably includes at least one thermosetting resin selected from the group consisting of resins containing polymers obtained by polymerizing ethylenically unsaturated monomers, epoxy resins, epoxidized oils and fats, phenolic resins, polyol resins, and amino-formaldehyde resins (melamine resins). Other examples of thermosetting resins include resins containing polymers obtained by polymerizing aromatic polyester raw materials. These thermosetting resins may be used alone or in combination of two or more.

[0130] (Epoxy Resin) The epoxy resin is not particularly limited as long as it has at least one epoxy bond in the molecule.

[0131] Specific examples of epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AD ​​type epoxy resins, bisphenol S type epoxy resins, glycidyl ester type epoxy resins, glycidylamine type epoxy resins, novolac type epoxy resins, glycidyl ether type epoxy resins of bisphenol A propylene oxide adducts, hydrogenated bisphenol A (or F) type epoxy resins, fluorinated epoxy resins, rubber-modified epoxy resins containing polybutadiene or NBR, flame-retardant epoxy resins such as glycidyl ether of tetrabromobisphenol A, p-oxybenzoic acid glycidyl ether ester type epoxy resins, m-aminophenol type epoxy resins, diaminodiphenylmethane-based epoxy resins, urethane-modified epoxy resins having a urethane bond, various alicyclic epoxy resins, glycidyl ethers of polyhydric alcohols, hydantoin type epoxy resins, epoxidized products of unsaturated polymers such as petroleum resins, and amino-containing glycidyl ether resins. Examples of the polyhydric alcohol include N,N-diglycidylaniline, N,N-diglycidyl-o-toluidine, triglycidyl isocyanurate, polyalkylene glycol diglycidyl ether, and glycerin. Examples of the epoxy resin include epoxy compounds obtained by subjecting the above-mentioned epoxy resins to an addition reaction with bisphenol A (or F), polybasic acids, or the like. The epoxy resin is not limited to these, and commonly used epoxy resins can be used. These epoxy resins may be used alone or in combination of two or more.

[0132] Among the above-mentioned epoxy resins, those having at least two epoxy groups per molecule are preferred because they have high reactivity during 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 containing bisphenol-type epoxy resin as the main component are preferred because of their excellent economic efficiency and ease of availability.

[0133] Examples of epoxidized fats and oils include epoxidized soybean oil and epoxidized linseed oil. The epoxidized fats and oils may be used alone or in combination of two or more.

[0134] The matrix resin is particularly preferably an epoxy resin, since it is possible to obtain a cured product that has an excellent balance between elastic modulus and strength.

[0135] (Ratio of polymer microparticles to matrix resin) In the resin composition, the ratio of polymer microparticles to matrix resin is, relative to the total of 100 wt% of polymer microparticles and matrix resin, preferably (a) 15 wt% to 50 wt% of polymer microparticles and 50 wt% to 85 wt% of matrix resin, (b) 15 wt% to 45 wt% of polymer microparticles and 55 wt% to 85 wt% of matrix resin, more preferably (c) 17 wt% to 40 wt% of polymer microparticles and 60 wt% to 83 wt% of matrix resin, more preferably (d) 20 wt% to 30 wt% of polymer microparticles and 70 wt% to 80 wt% of matrix resin, more preferably (e) 23 wt% to 27 wt% of polymer microparticles and 73 wt% to 77 wt% of matrix resin. When the polymer microparticles are 15 wt% or more relative to the total of 100 wt% of polymer microparticles and matrix resin, it has the advantage that a cured product or molded product with superior toughness can be obtained. When the polymer microparticles are 50% by weight or less relative to 100% by weight of the total of the polymer microparticles and the matrix resin, the resin composition has the advantage of having a low viscosity. A resin composition in which the polymer microparticles are 15% by weight or more relative to 100% by weight of the total of the polymer microparticles and the matrix resin can be called a masterbatch.

[0136] The content ratio of the polymer microparticles and the matrix resin in the resin composition may be, relative to 100% by weight of the total of the polymer microparticles and the matrix resin, (a) 15% by weight to 50% by weight of the polymer microparticles and 50% by weight to 85% by weight of the matrix resin; (b) 17% by weight to 50% by weight of the polymer microparticles and 50% by weight to 83% by weight of the matrix resin; (c) 20% by weight to 50% by weight of the polymer microparticles and 50% by weight to 80% by weight of the matrix resin; (d) 23% by weight to 50% by weight of the polymer microparticles and 50% by weight to 77% by weight of the matrix resin; or (e) 25% by weight to 50% by weight of the polymer microparticles and 50% by weight to 75% by weight of the matrix resin.

[0137] (Other Optional Components) The resin composition may contain other optional components in addition to the components described above, as necessary. Examples of other optional components include inorganic fillers, organic fillers, antiblocking agents, curing agents, colorants such as pigments and dyes, extender pigments, UV absorbers, antioxidants, heat stabilizers (antigelling agents), plasticizers, leveling agents, antifoaming agents, silane coupling agents, antistatic agents, flame retardants, lubricants, viscosity reducers, shrinkage reducing agents, desiccants, and dispersants.

[0138] Other optional components can be added in any step in the manufacturing method of the resin composition. For example, other optional components can be added to the aqueous latex or mixture in the first step described below (Method for manufacturing a resin composition), or to the aggregate of recovered polymer microparticles in the second step. Other optional components can be added to the resin composition.

[0139] (Physical Properties of Resin Composition) The present resin composition has the advantage of having low viscosity and therefore excellent handleability. The viscosity of the present resin composition at 50°C is preferably less than 10,000 mPa·s, more preferably 9,000 mPa·s or less, more preferably 8,000 mPa·s or less, still more preferably 7,000 mPa·s or less, even more preferably 6,000 mPa·s or less, and particularly preferably 5,000 mPa·s or less. The "viscosity of the resin composition at 50°C" can also be referred to as the "viscosity of the resin composition at 50°C."

[0140] The viscosity of the resin composition at 50°C may be 4,800 mPa·s or less, 4,600 mPa·s or less, 4,400 mPa·s or less, 4,200 mPa·s or less, or 4,000 mPa·s or less.

[0141] There is no particular lower limit to the viscosity of the resin composition at 50° C. From the viewpoint of handleability, the viscosity is preferably 100 mPa·s or more, more preferably 200 mPa·s or more, even more preferably 300 mPa·s or more, and particularly preferably 500 mPa·s or more.

[0142] (Method for Producing Resin Composition) The resin composition is preferably a composition in which polymer microparticles are dispersed in the form of primary particles in a matrix resin. Various methods can be used to obtain such a composition in which polymer microparticles are dispersed in the form of primary particles in a matrix resin (i.e., a method for producing the resin composition). Examples of methods for producing the resin composition include: (i) contacting polymer microparticles obtained in an aqueous latex state with a matrix resin and then removing unnecessary components such as water; and (i) extracting the polymer microparticles obtained in an aqueous latex state with an organic solvent, mixing the resulting organic solvent solution of the polymer microparticles with the matrix resin, and then removing the organic solvent. The method described in International Publication No. 2005 / 028546 is preferably used to produce the resin composition. The specific production method includes, in order, (i) a first step of mixing an aqueous latex containing polymer microparticles (specifically, a reaction mixture obtained after producing polymer microparticles by emulsion polymerization) with an organic solvent having a solubility in water of 5% by weight to 40% by weight at 20°C, and then adding excess water to the resulting mixture and mixing to aggregate the polymer microparticles, (ii) a second step of separating and recovering the aggregated polymer microparticles from the mixture (liquid phase), and then mixing the recovered polymer microparticles again with an organic solvent to obtain an organic solvent solution of the polymer microparticles, and (iii) a third step of mixing the resulting organic solvent solution with a matrix resin, and then distilling off the organic solvent. The resin composition is preferably prepared by a production method including the above-mentioned first, second, and third steps.

[0143] [Cured Product] A cured product obtained by curing the present resin composition, or a cured product obtained by curing a composition obtained by blending the present modifier with a thermosetting resin, is also one embodiment of the present invention.

[0144] The cured product according to one embodiment of the present invention is obtained by curing the resin composition or a composition obtained by blending the modifier with a thermosetting resin, and therefore has the advantages of excellent elastic modulus and impact resistance. The cured product according to one embodiment of the present invention also has the advantage of excellent toughness.

[0145] [Uses] The polymer microparticles, the modifier, the resin composition, and the cured product according to one embodiment of the present invention can be used in a variety of applications, and these applications are not particularly limited. The polymer microparticles, the modifier, the resin composition, and the cured product according to one embodiment of the present invention are each preferably used in applications such as adhesives, coating materials, binders for reinforcing fibers, composite materials, 3D printer molding materials, sealants, electronic substrates, ink binders, wood chip binders, rubber chip binders, foam chip binders, foundry binders, rock consolidation materials for flooring and ceramics, and urethane foams.

[0146] The present polymer microparticles, the present modifier, the present resin composition and the cured product according to one embodiment of the present invention are particularly preferably used in composite materials used in the manufacture of aircraft, among the above-mentioned applications.

[0147] One embodiment of the present invention provides a composite material comprising the resin composition.

[0148] An embodiment of the present invention includes the following configuration.

[0149] [1] Polymer microparticles containing a graft copolymer having a crosslinked core layer and a shell layer graft-bonded to the crosslinked core layer, wherein the crosslinked core layer contains a polymer C1 having a glass transition temperature of 75°C or higher, and the shell layer contains a polymer S having a glass transition temperature of 0°C or lower, and the polymer microparticles have a volume average particle diameter of 0.01 μm to 1.00 μm.

[0150] [2] The polymer microparticles according to [1], wherein the polymer C1 contains, per 100% by weight of the polymer C1, 50% by weight to 100% by weight of a structural unit U1 derived from a monomer M1 that, when made into a homopolymer, gives a glass transition temperature of the homopolymer of 60°C or higher.

[0151] [3] The polymer microparticles according to [1] or [2], wherein the polymer S contains one or more structural units selected from the group consisting of aromatic vinyl units, vinylcyan units, and (meth)acrylate units.

[0152] [4] The polymer microparticles according to any one of [1] to [3], wherein the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer.

[0153] [5] The polymer microparticles described in [4], wherein the first crosslinked core layer contains the polymer C1, and the second crosslinked core layer contains a polymer C2 having a glass transition temperature of 0°C or lower.

[0154] [6] The polymer microparticles according to any one of [1] to [5], wherein the shell layer contains, based on 100% by weight of the shell layer, more than 0% by weight and 50% by weight or less of a structural unit having an epoxy group.

[0155] [7] The polymer microparticles according to any one of [1] to [6], wherein the polymer C1 has a glass transition temperature of 150° C. or lower.

[0156] [8] The polymer microparticles according to any one of [1] to [7], wherein the polymer C1 comprises (i) one or more structural units selected from the group consisting of a styrene unit, an α-methylstyrene unit, a phenyl methacrylate unit, an isobornyl methacrylate unit, and a dicyclopentanyl methacrylate unit, and (ii) one or more structural units selected from the group consisting of an allyl methacrylate unit, a diallyl phthalate unit, a triallyl isocyanurate unit, and a divinylbenzene unit.

[0157] [9] The polymer microparticles according to [5], wherein the glass transition temperature of the polymer C2 is −80° C. or higher.

[0158]

[10] The polymer microparticles according to [5] or [9], wherein the polymer C2 contains, per 100 wt% of the polymer C2, 50 wt% to 100 wt% of a structural unit U2 derived from a monomer M2 that, when made into a homopolymer, gives a glass transition temperature of the homopolymer of 0°C or less.

[0159]

[11] The polymer C2 contains (i) one or more structural units selected from the group consisting of an ethyl acrylate unit, a butyl acrylate unit, a 2-ethylhexyl acrylate unit, an octyl (meth)acrylate unit, a dodecyl (meth)acrylate unit, a 2-hydroxyethyl acrylate unit, and a 4-hydroxybutyl acrylate unit, (ii) one or more structural units selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, The polymer microparticles according to any one of claims [5], [9] and

[10] , comprising (iii) one or more structural units selected from the group consisting of allyl methacrylate, diallyl phthalate, triallyl isocyanurate and divinylbenzene.

[0160]

[12] The polymer microparticles according to any one of [1] to

[11] , wherein the glass transition temperature of the polymer S is −80° C. or higher.

[0161]

[13] The polymer microparticles according to any one of [1] to

[12] , wherein the polymer S contains, per 100 wt% of the polymer S, 50 wt% to 100 wt% of a structural unit U3 derived from a monomer M3 that, when converted into a homopolymer, results in a glass transition temperature of the homopolymer being 0°C or lower.

[0162]

[14] The polymer S contains (i) one or more structural units selected from the group consisting of an ethyl acrylate unit, a butyl acrylate unit, a 2-ethylhexyl acrylate unit, an octyl (meth)acrylate unit, a dodecyl (meth)acrylate unit, a 2-hydroxyethyl acrylate unit, and a 4-hydroxybutyl acrylate unit, (ii) one or more structural units selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl (meth)acrylate, dodecyl (meth)acrylate (iii) one or more structural units selected from the group consisting of glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and allyl glycidyl ether; and (iv) one or more structural units selected from the group consisting of methyl acrylate, methyl acrylate, methyl methacrylate, methyl ...

[0163]

[15] A resin modifier comprising the polymer fine particles according to any one of [1] to

[14] .

[0164]

[16] A resin composition comprising the polymer microparticles according to any one of [1] to

[14] or the resin modifier according to [8], and a matrix resin, wherein the polymer microparticles account for 15% by weight to 50% by weight and the matrix resin accounts for 50% by weight to 85% by weight, relative to 100% by weight of the total of the polymer microparticles and the matrix resin.

[0165]

[17] The resin composition according to

[16] , wherein the matrix resin is a thermosetting resin.

[0166]

[18] The resin composition according to

[16] or

[17] , wherein the matrix resin is an epoxy resin.

[0167]

[19] The resin composition according to any one of

[16] to

[18] , wherein the polymer microparticles account for 20% by weight to 50% by weight relative to 100% by weight of the total of the polymer microparticles and the matrix resin, and the viscosity at 50°C is 8,000 mPa s or less.

[0168]

[20] A composite material comprising the resin composition according to any one of

[16] to

[19] .

[0169] Hereinafter, one embodiment of the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these. One embodiment of the present invention can be practiced with appropriate modifications within the scope of the above-mentioned or below-mentioned gist, and all such modifications are included in the technical scope of the present invention.

[0170] [Evaluation Methods] First, the evaluation methods for the resin compositions produced in the Examples and Comparative Examples will be described below.

[0171] <Measurement of Volume Average Particle Diameter> The volume average particle diameter (Mv) of the core layer dispersed in the aqueous latex and the polymer microparticles dispersed in the aqueous latex was measured using a Microtrac UPA150 (manufactured by Nikkiso Co., Ltd.). Aqueous latex diluted with deionized water was used as the measurement sample. The measurement was performed by inputting the refractive index of water, the refractive index of the core layer obtained in each Production Example, or the refractive index of the polymer microparticles obtained in each Production Example, and adjusting the sample concentration so that the measurement time was 600 seconds and the signal level was within the range of 0.6 to 0.8.

[0172] <Glass Transition Temperature> The Tg of Polymer C1, Polymer C2, and Polymer S was calculated according to the above-mentioned FOX formula (Equation 1) using the Tg values ​​of homopolymers of the following monomers: Styrene (St) 80°C; Butadiene (Bd) -80°C; n-butyl acrylate (BA) -55°C; Methyl acrylate (MA) 8°C; Methyl methacrylate (MMA) 105°C; Glycidyl methacrylate (GMA) 46°C. Note that although a crosslinkable monomer was used in the polymerization of some polymers, the amount used was small (in other words, the amount of crosslinkable units in the obtained polymer was small). Therefore, since the effect of the crosslinkable monomer on the Tg of the polymer was small, the use of the crosslinkable monomer was not taken into consideration in calculating the Tg according to the FOX formula.

[0173] <Measurement of physical properties of cured epoxy products> The cured products (cured plates) obtained in each example and comparative example were cut to prepare samples. Using the prepared samples, bending tests and Charpy tests were carried out under conditions of a support distance of 80 mm and a test speed of 2 mm / min to determine the flexural modulus and Charpy strength.

[0174] Furthermore, the cured products (cured plates) obtained in each of the Examples and Comparative Examples were cut to a length of 2.5 inches, a width (b) of 0.5 inches, and a thickness (h) of 5 mm to prepare test specimens. A V-notch was made in the obtained test specimens using a notching machine. A crack was then made from the tip of the V-notch to the center of the test specimen using a razor blade. The test specimens were cured at 23°C for 48 hours, and then subjected to a three-point bending test using an Autograph AG-2000E (manufactured by Shimadzu Corporation) with a support distance (L) of 50 mm and a test speed of 1 mm / min. Using the maximum strength F (kN) obtained from the three-point bending test, the fracture toughness value K1c (MPa m ０．５ where a is the sum of the V-notch depth and the length from the tip of the V-notch to the tip of the crack, and L, h, a, and b are in cm (ASTM D5045): K1c = (F × L / (h × b ３／２) × f (Equation 3); f = 3 (a / b) １／２ × AA / BB (Equation 4); (In Equation 4, AA = 1.99 - (a / b) {1 - (a / b)} {2.15 - 3.93 (a / b) + 2.7 (a / b) ２ )}, and BB = 2{1 + 2(a / b)} {1 - (a / b)} ３／２ is.

[0175] <Viscosity Measurement> The viscosity of the resin compositions (masterbatches) obtained in each Example and Comparative Example was measured. A Brookfield DV-II+ Pro digital viscometer was used. The viscosity was measured at a measurement temperature of 50°C using a CPE-52 spindle, varying the shear rate as necessary, depending on the viscosity range. The results are shown in Table 1. [Preparation of Polymer Microparticles] (Comparative Example 3) <1. Formation of Core Layer> (Production Example 1-1: Preparation of Polybutadiene Rubber Latex (R-1)) 200 parts by mass of deionized water, 0.03 parts by mass of tripotassium phosphate, 0.002 parts by mass of disodium ethylenediaminetetraacetate (EDTA), 0.001 parts by mass of ferrous sulfate heptahydrate, and 1.55 parts by mass of sodium dodecylbenzenesulfonate (SDBS) as an emulsifier were placed in a pressure polymerization reactor. Next, while stirring the introduced raw materials, the gas inside the pressure-resistant polymerization vessel was replaced with nitrogen, thereby thoroughly removing oxygen from inside the pressure-resistant polymerization vessel. Thereafter, 100 parts by mass of butadiene (Bd) was introduced into the pressure-resistant polymerization vessel, and the temperature inside the pressure-resistant polymerization vessel was raised to 45°C. Thereafter, 0.03 parts by mass of paramenthane hydroperoxide (PHP) was introduced into the pressure-resistant polymerization vessel, followed by 0.10 parts by mass of sodium formaldehyde sulfoxylate (SFS) into the pressure-resistant polymerization vessel to initiate polymerization. Fifteen hours after the start of polymerization, devolatilization was performed under reduced pressure to remove the remaining monomers that had not been used in the polymerization, thereby terminating the polymerization. During the polymerization, PHP, EDTA, and ferrous sulfate heptahydrate were each added to the pressure-resistant polymerization vessel in arbitrary amounts and at arbitrary times. This polymerization yielded a polybutadiene rubber latex (R-1) composed primarily of polybutadiene rubber. The volume average particle size of the polybutadiene rubber contained in the obtained polybutadiene rubber latex (R-1) was 0.08 μm.

[0176] (Production Example 1-2: Preparation of Polybutadiene Rubber Latex (R-2)) 21 parts by mass of the polybutadiene rubber latex (R-1) obtained in Production Example 1-1 (containing 7 parts by mass of polybutadiene rubber), 185 parts by mass of deionized water, 0.03 parts by mass of tripotassium phosphate, 0.002 parts by mass of EDTA, and 0.001 parts by mass of ferrous sulfate heptahydrate were charged into a pressure-resistant polymerization vessel. Next, while stirring the charged raw materials, the gas inside the pressure-resistant polymerization vessel was replaced with nitrogen, thereby sufficiently removing oxygen from inside the pressure-resistant polymerization vessel. Thereafter, 93 parts by mass of Bd were charged into the pressure-resistant polymerization vessel, and the temperature inside the pressure-resistant polymerization vessel was raised to 45°C. Thereafter, 0.02 parts by mass of PHP was charged into the pressure-resistant polymerization vessel, followed by charging 0.10 parts by mass of SFS into the pressure-resistant polymerization vessel, to initiate polymerization. Thirty hours after the start of polymerization, the polymerization was terminated by devolatilization under reduced pressure to remove the remaining monomers not used in the polymerization. During the polymerization, PHP, EDTA, ferrous sulfate heptahydrate, and SDBS were each added to the pressure-resistant polymerization reactor in desired amounts and at desired times. This polymerization yielded a polybutadiene rubber latex (R-2) containing a core layer primarily composed of polybutadiene rubber. The volume average particle diameter of the core layer contained in the obtained polybutadiene rubber latex (R-2) was 0.20 μm. The polybutadiene rubber contained in the polybutadiene rubber latex (R-2) had a Tg of −80° C. Therefore, although the Tg is listed in the column for “Polymer C1” in Comparative Example 3 in Table 1, the core layer of the polymer microparticles of Comparative Example 3 does not contain polymer C1.

[0177] 2. Preparation of Polymer Microparticles (Formation of Shell Layer) (Production Example 2-2: Preparation of Aqueous Latex of Polymer Microparticles (L-2)) 261 parts by mass of the polybutadiene rubber latex (R-2) obtained in Production Example 1-1 (containing 87 parts by mass of polybutadiene rubber particles) and 54 parts by mass of deionized water were charged into a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer addition device. The raw materials charged were stirred at 60°C while the gas in the glass reactor was replaced with nitrogen. Next, 0.004 parts by mass of EDTA, 0.001 parts by mass of ferrous sulfate heptahydrate, and 0.2 parts by mass of SFS were added to the glass reactor. Thereafter, a mixture of 13 parts by mass of methyl methacrylate (MMA) and 0.04 parts by mass of CHP was continuously added to the glass reactor over 85 minutes. After the addition was completed, 0.065 parts by mass of CHP was added to the glass reactor, and the mixture in the glass reactor was further stirred for 1 hour to complete the polymerization. By the above operations, an aqueous latex (L-2) containing polymer microparticles was obtained. The polymerization conversion rate of the monomer components was 99% or more. The volume average particle diameter of the polymer microparticles contained in the obtained aqueous latex (L-2) was 0.19 μm.

[0178] Comparative Example 2 1. Formation of Core Layer Production Example 1-3 Preparation of Aqueous Latex (R-3) 182 parts by mass of deionized water, 0.006 parts by mass of EDTA, 0.0015 parts by mass of ferrous sulfate heptahydrate, 0.2 parts by mass of SFS, and 0.15 parts by mass of SDBS were placed in a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier addition device. The raw materials were stirred at 60°C while the gas in the glass reactor was replaced with nitrogen (i.e., in a nitrogen stream). Next, a mixture of 75 parts by mass of St, 1.5 parts by mass of allyl methacrylate (ALMA), and 0.021 parts by mass of cumene hydroperoxide (CHP) was continuously added dropwise to the glass reactor over 175 minutes. After the addition was completed, the mixture in the glass reactor was stirred for another 0.5 hour to complete the polymerization. By the above operations, an aqueous latex (R-3) containing polymer C1 was obtained. The Tg of polymer C1 is shown in Table 1.

[0179] 2. Preparation of Polymer Microparticles (Formation of Shell Layer) (Production Example 2-3: Preparation of Aqueous Latex (L-1) of Polymer Microparticles) Following the formation of the core layer, a mixture containing the amounts of each monomer listed in the Shell Layer column of Table 1 (i.e., a mixture of 22.5 parts by mass of methyl methacrylate (MMA), 0.5 parts by mass of butyl acrylate (BA), and 2 parts by mass of glycidyl methacrylate (GMA)) and 0.05 parts by mass of CHP was continuously added over 200 minutes to the glass reactor (containing the aqueous latex (R-3)) after the production of the aqueous latex (R-3). After the addition was completed, 0.04 parts by mass of CHP was added to the glass reactor, and the mixture in the glass reactor was further stirred for 1 hour to complete the polymerization. By the above operations, a shell layer grafted to the crosslinked core layer was formed, and an aqueous latex (L-1) containing polymer microparticles was obtained. The polymerization conversion rate of the monomer components was 99% or more. The volume average particle diameter of the polymer microparticles contained in the obtained aqueous latex (L-1) was 0.19 μm. The Tg of the shell layer of the polymer microparticles of Comparative Example 2 contained in the aqueous latex (L-1) was 94° C. In Table 1, the Tg is listed in the column for "Polymer S" for Comparative Example 2, but the shell layer of the polymer microparticles of Comparative Example 2 does not contain Polymer S.

[0180] (Example 1) (Preparation of polymer particle latex (L-3)) An aqueous latex (L-3) containing polymer particles was obtained in the same manner as in Production Example 2-3, except that a mixture containing each monomer shown in the shell layer column of Table 1 in the amount shown in that column was used. The polymerization conversion rate of the monomer was 99% or more. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex was 0.19 μm.

[0181] (Example 2) (Preparation of polymer particle latex (L-4)) An aqueous latex (L-4) containing polymer particles was obtained in the same manner as in Production Example 2-3, except that a mixture containing the amounts of each monomer shown in the shell layer column of Table 1 was used. The polymerization conversion rate of the monomer was 99% or more. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex was 0.19 μm.

[0182] In Examples 1 and 2, the core layer of the polymer microparticles was a crosslinked core layer composed only of crosslinked polymer C1, and in Examples 1 and 2, the shell layer of the polymer microparticles was composed only of non-crosslinked polymer S having a Tg of 0°C or less.

[0183] Example 3 (Preparation of Polymer Particle Latex (L-5)) 182 parts by mass of deionized water, 0.006 parts by mass of EDTA, 0.0015 parts by mass of ferrous sulfate heptahydrate, 0.2 parts by mass of SFS, and 0.15 parts by mass of SDBS were charged into a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier addition device. The raw materials charged were stirred at 60°C while the gas in the glass reactor was replaced with nitrogen (i.e., in a nitrogen stream). Next, a mixture of 55 parts by mass of St, 1.1 parts by mass of allyl methacrylate (ALMA), and 0.015 parts by mass of cumene hydroperoxide (CHP) was continuously added dropwise to the glass reactor over 130 minutes. After the addition was completed, the mixture in the glass reactor was stirred for an additional 0.5 hours to complete the polymerization. The above procedure yielded a first core layer (Polymer C1). Subsequently, a mixture of 20 parts by weight of BA, 0.4 parts by weight of allyl methacrylate (ALMA), and 0.006 parts by weight of cumene hydroperoxide (CHP) was continuously added dropwise to the glass reactor over 50 minutes. After the addition was completed, the mixture in the glass reactor was stirred for an additional 0.5 hours to complete the polymerization. Through the above procedure, an aqueous latex containing a crosslinked core layer was obtained, in which a second core layer (Polymer C2) was formed on the outside of the first core layer (Polymer C1). Subsequently, a mixture containing the monomers listed in the Shell Layer column of Table 1 in the amounts listed in that column (i.e., a mixture of 12.5 parts by weight of methyl acrylate (MA), 10.5 parts by weight of butyl acrylate (BA), and 2 parts by weight of GMA) and 0.05 parts by weight of CHP was continuously added to the glass reactor over 200 minutes. After the addition was completed, 0.04 parts by mass of CHP was added to the glass reactor, and the mixture in the glass reactor was further stirred for 1 hour to complete the polymerization. Through the above operations, a shell layer grafted to the crosslinked core layer was formed, and an aqueous latex (L-5) containing polymer microparticles was obtained. The polymerization conversion rate of the monomer components was 99% or more. The volume average particle diameter of the polymer microparticles contained in the obtained aqueous latex was 0.22 μm.

[0184] Example 4 (Production Example 2-4: Preparation of Polymer Particle Latex (L-6)) 182 parts by mass of deionized water, 0.006 parts by mass of EDTA, 0.0015 parts by mass of ferrous sulfate heptahydrate, 0.2 parts by mass of SFS, and 0.15 parts by mass of SDBS were charged into a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier addition device. The charged raw materials were stirred at 60°C while the gas in the glass reactor was replaced with nitrogen (i.e., in a nitrogen gas flow). Next, a mixture of 55 parts by mass of St, 1.1 parts by mass of allyl methacrylate (ALMA), and 0.015 parts by mass of cumene hydroperoxide (CHP) was continuously added dropwise to the glass reactor over 130 minutes. After the addition was completed, the mixture in the glass reactor was stirred for an additional 0.5 hour to complete the polymerization. This procedure yielded a first core layer (Polymer C1). Subsequently, a mixture containing the monomers listed in the column for Polymer C2 of the Core Layer in Table 1 in the amounts listed in that column (i.e., a mixture of 14.4 parts by weight of BA and 5.6 parts by weight of MA), 0.4 parts by weight of allyl methacrylate (ALMA), and 0.006 parts by weight of cumene hydroperoxide (CHP) was continuously added dropwise to the glass reactor over a period of 50 minutes. After the addition was completed, the mixture in the glass reactor was stirred for an additional 0.5 hour to complete the polymerization. This procedure yielded an aqueous latex containing a crosslinked core layer in which a second core layer (Polymer C2) was formed on the outside of the first core layer (Polymer C1). Subsequently, a mixture containing the respective monomers listed in the "shell layer" column of Table 1 in the amounts listed in that column (i.e., a mixture of 12.5 parts by mass of MA, 10.5 parts by mass of BA, and 2 parts by mass of GMA) and 0.05 parts by mass of CHP were continuously added to the glass reactor over a period of 200 minutes. After the addition was completed, 0.04 parts by mass of CHP was added to the glass reactor, and the mixture in the glass reactor was continuously stirred for an additional hour to complete the polymerization. Through these operations, a shell layer grafted to the crosslinked core layer was formed, and an aqueous latex (L-6) containing polymer microparticles was obtained. The polymerization conversion rate of the monomer components was 99% or higher. The volume average particle diameter of the polymer microparticles contained in the obtained aqueous latex was 0.22 μm.

[0185] Example 5 Preparation of Polymer Particle Latex (L-7) An aqueous latex (L-7) containing polymer particles was obtained in the same manner as in Production Example 2-4, except that a mixture containing the amounts of each monomer listed in the column for Polymer C2 for the core layer in Table 1 was used, and a mixture containing the amounts of each monomer listed in the column for the shell layer in Table 1 was used. The polymerization conversion rate of the monomer components was 99% or more. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex was 0.22 μm.

[0186] Example 6 Preparation of Polymer Particle Latex (L-8) An aqueous latex (L-8) containing polymer particles was obtained in the same manner as in Production Example 2-4, except that a mixture containing the amounts of each monomer listed in the column for Polymer C2 for the core layer in Table 1 was used, and a mixture containing the amounts of each monomer listed in the column for the shell layer in Table 1 was used. The polymerization conversion rate of the monomer components was 99% or more. The volume average particle diameter of the polymer particles contained in the obtained aqueous latex was 0.22 μm.

[0187] Example 7 Preparation of Polymer Particle Latex (L-9) 182 parts by mass of deionized water, 0.006 parts by mass of EDTA, 0.0015 parts by mass of ferrous sulfate heptahydrate, 0.2 parts by mass of SFS, and 0.15 parts by mass of SDBS were charged into a glass reactor. The glass reactor was equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet, and a monomer and emulsifier addition device. The raw materials charged were stirred at 60°C while the gas in the glass reactor was replaced with nitrogen (i.e., in a nitrogen stream). Next, a mixture of 65 parts by mass of St, 1.3 parts by mass of allyl methacrylate (ALMA), and 0.018 parts by mass of cumene hydroperoxide (CHP) was continuously added dropwise to the glass reactor over 150 minutes. After the addition was completed, the mixture in the glass reactor was stirred for an additional 0.5 hours to complete the polymerization. The above procedure yielded a first core layer (Polymer C1). Subsequently, a mixture containing the monomers listed in the column for Polymer C2 of the Core Layer in Table 1 in the amounts listed in that column (i.e., a mixture of 5.4 parts by weight of BA and 4.6 parts by weight of MA), 0.2 parts by weight of allyl methacrylate (ALMA), and 0.003 parts by weight of cumene hydroperoxide (CHP) was continuously added dropwise to the glass reactor over a period of 25 minutes. After the addition was completed, the mixture in the glass reactor was stirred for an additional 0.5 hours to complete the polymerization. The above procedure yielded an aqueous latex containing a crosslinked core layer in which a second core layer (Polymer C2) was formed on the outside of the first core layer (Polymer C1). Subsequently, a mixture containing the respective monomers listed in the "shell layer" column of Table 1 in the amounts listed in that column (i.e., a mixture of 12.5 parts by mass of MA, 10.5 parts by mass of BA, and 2 parts by mass of GMA) and 0.05 parts by mass of CHP were continuously added to the glass reactor over a period of 200 minutes. After the addition was completed, 0.04 parts by mass of CHP was added to the glass reactor, and the mixture in the glass reactor was continuously stirred for an additional hour to complete the polymerization. Through these operations, a shell layer grafted to the crosslinked core layer was formed, and an aqueous latex (L-9) containing polymer microparticles was obtained. The polymerization conversion rate of the monomer components was 99% or higher. The volume average particle diameter of the polymer microparticles contained in the obtained aqueous latex was 0.21 μm.

[0188] In Examples 3 to 7, the core layer of the polymer microparticles was a crosslinked core layer composed only of a crosslinked polymer C1 having a Tg of 70° C. or higher and a crosslinked polymer C2 formed on the outer surface of the polymer C1 and having a Tg of 0° C. or lower. In addition, in Examples 3 to 7, the shell layer of the polymer microparticles was composed only of a non-crosslinked polymer S having a Tg of 0° C. or lower.

[0189] [Preparation of Resin Composition (Masterbatch)] (Examples 1 to 7, Comparative Examples 2 and 3) 132 g of methyl ethyl ketone (MEK) was introduced into a 1 L mixing tank at 25°C. While stirring the MEK, 132 g (equivalent to 40 g of polymer microparticles) of each of the aqueous latexes (L-1) to (L-9) of polymer microparticles obtained in each Example and Comparative Example was added. After uniform mixing, 200 g of water was added at a feed rate of 80 g / min. After the feed was completed, stirring was promptly stopped, yielding a slurry liquid consisting of floating aggregates and an aqueous phase containing a portion of an organic solvent. Next, 360 g of the aqueous phase was discharged from the outlet at the bottom of the tank, leaving behind the aggregates containing a portion of the aqueous phase. 90 g of MEK was added to the obtained aggregates and mixed uniformly to obtain a dispersion in which the polymer microparticles were uniformly dispersed. 120 g of an epoxy resin (JER828EL, manufactured by Mitsubishi Chemical Corporation) serving as a matrix resin was mixed with this dispersion. The MEK was removed from this mixture using a rotary evaporator. In this way, a resin composition (masterbatch) containing polymer microparticles and an epoxy resin was obtained. The viscosity of the resulting resin composition (masterbatch) was measured. The results are shown in Table 1.

[0190] [Preparation of Cured Product (Cured Board)] (Comparative Example 1) In Comparative Example 1, neither polymer microparticles nor a resin composition (masterbatch) was prepared. That is, in Comparative Example 1, 25 parts by weight of "JER WA" (trade name, manufactured by Mitsubishi Chemical Corporation) as a curing agent was added to 100 parts by weight of an epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828) to obtain a mixture. The resulting mixture was mixed at 2000 rpm for 5 minutes using a planetary mixer to obtain a resin composition. The resulting resin composition was poured into a mold and heated at 100°C for 2 hours and then at 175°C for 4 hours to obtain a cured product (cured board). The physical properties of the resulting cured board were measured. The results are shown in Table 1.

[0191] (Examples 1 to 7, Comparative Examples 2 and 3) 25 parts by weight of "JER WA" (trade name, manufactured by Mitsubishi Chemical Corporation) as a curing agent and 26.32 parts by weight of the resin composition (masterbatch) obtained in each Example and Comparative Example were added to 80.26 parts by weight of epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828) to obtain a mixture. The resulting mixture was mixed at 2000 rpm for 5 minutes in a planetary centrifugal mixer to obtain a resin composition. The resulting resin composition was poured into a mold and heated at 100°C for 2 hours, and then further heated at 175°C for 4 hours to obtain a cured product (cured plate). The physical properties of the resulting cured plate were measured. The results are shown in Table 1.

[0192] According to one aspect of the present invention, polymer microparticles can be provided that can provide a resin composition that can provide a cured product with excellent elastic modulus and impact resistance. Therefore, one embodiment of the present invention is preferably used in applications such as adhesives, coating materials, binders for reinforcing fibers, composite materials, 3D printer modeling materials, sealants, electronic substrates, ink binders, wood chip binders, rubber chip binders, foam chip binders, foundry binders, rock consolidation agents for flooring and ceramics, and urethane foam. One embodiment of the present invention is particularly preferably used in composite materials used in aircraft manufacturing, etc.

Claims

1. A polymer microparticle comprising a graft copolymer having a crosslinked core layer and a shell layer graft-bonded to the crosslinked core layer, the crosslinked core layer comprises a polymer C1 having a glass transition temperature of 75°C or higher; the shell layer contains a polymer S having a glass transition temperature of 0°C or lower, The volume average particle size is 0.01 μm to 1.00 μm, the crosslinked core layer has a first crosslinked core layer and a second crosslinked core layer formed outside the first crosslinked core layer, the first crosslinked core layer comprises the polymer C1, The second crosslinked core layer comprises polymer particles containing a polymer C2 having a glass transition temperature of 0° C. or lower.

2. The polymer microparticles according to claim 1, wherein the polymer C1 contains, per 100% by weight of the polymer C1, 50% by weight to 100% by weight of a structural unit U1 derived from a monomer M1 that, when converted into a homopolymer, results in a glass transition temperature of the homopolymer being 60°C or higher.

3. 2. The polymer microparticles according to claim 1, wherein the polymer S comprises one or more structural units selected from the group consisting of an aromatic vinyl unit, a vinylcyan unit, and a (meth)acrylate unit.

4. 2. The polymer microparticles according to claim 1, wherein the shell layer contains more than 0 wt% and 50 wt% or less of a structural unit having an epoxy group, based on 100 wt% of the shell layer.

5. The polymer microparticles according to claim 1, wherein the polymer C1 comprises (i) one or more structural units selected from the group consisting of a styrene unit, an α-methylstyrene unit, a phenyl methacrylate unit, an isobornyl methacrylate unit, and a dicyclopentanyl methacrylate unit, and (ii) one or more structural units selected from the group consisting of an allyl methacrylate unit, a diallyl phthalate unit, a triallyl isocyanurate unit, and a divinylbenzene unit.

6. The polymer microparticles according to claim 1, wherein the polymer C2 comprises: (i) one or more structural units selected from the group consisting of ethyl acrylate units, butyl acrylate units, 2-ethylhexyl acrylate units, octyl (meth)acrylate units, dodecyl (meth)acrylate units, 2-hydroxyethyl acrylate units, and 4-hydroxybutyl acrylate units; (ii) one or more structural units selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, styrene, α-methylstyrene, p-methylstyrene, acrylonitrile, and methacrylonitrile; and (iii) one or more structural units selected from the group consisting of allyl methacrylate, diallyl phthalate, triallyl isocyanurate, and divinylbenzene.

7. The polymer S contains (i) one or more structural units selected from the group consisting of an ethyl acrylate unit, a butyl acrylate unit, a 2-ethylhexyl acrylate unit, an octyl (meth)acrylate unit, a dodecyl (meth)acrylate unit, a 2-hydroxyethyl acrylate unit, and a 4-hydroxybutyl acrylate unit, (ii) one or more structural units selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, 2. The polymer microparticles according to claim 1, comprising (iii) one or more structural units selected from the group consisting of acrylate, stearyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, styrene, α-methylstyrene, p-methylstyrene, acrylonitrile, and methacrylonitrile, and (iii) one or more structural units selected from the group consisting of glycidyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, and allyl glycidyl ether.

8. A resin modifier comprising the polymer fine particles according to claim 1.

9. A polymer fine particle according to any one of claims 1 to 7 or a resin modifier according to claim 8, and a matrix resin, The resin composition comprises 15 to 50% by weight of the polymer fine particles and 50 to 85% by weight of the matrix resin, with respect to 100% by weight of the total of the polymer fine particles and the matrix resin.

10. The resin composition according to claim 9 , wherein the matrix resin is a thermosetting resin.

11. The resin composition according to claim 9 , wherein the matrix resin is an epoxy resin.

12. the polymer fine particles are present in an amount of 20% by weight to 50% by weight relative to 100% by weight of the total of the polymer fine particles and the matrix resin; The resin composition according to claim 9, having a viscosity at 50°C of 8,000 mPa·s or less.

13. A composite material comprising the resin composition according to claim 9.