Core-shell type graft copolymer particles, production method thereof, and resin composition

Abstract

To provide core-shell type graft copolymer particles which enable formation of a resin composition that is good in both impact resistance and weather resistance by being blended with a thermoplastic resin.SOLUTION: Core-shell type graft copolymer particles contain core particles (A), and a shell layer (B) coating the core particles (A). The core particles (A) contain polyalkyl (meth)acrylate rubber, and a reactive ultraviolet absorber represented by formula (1) is copolymerized with at least a part of the polyalkyl (meth)acrylate rubber. A volume average particle diameter of the core particles (A) is 400-800 nm. A ratio occupied by the core particles (A) in the core-shell type graft copolymer particles is 50-80 wt.%. The shell layer (B) includes a layer (b1) of a copolymer including an aromatic vinyl compound unit and a vinyl cyanide compound unit.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to core-shell type graft copolymer particles, a method for producing the same, and a resin composition containing the particles. [Background technology]

[0002] ABS resin (acrylonitrile-butadiene-styrene) has excellent rigidity, impact resistance, and heat deformation resistance, so it is widely used for various miscellaneous goods, interior and exterior materials for automobiles, housing parts for home appliances such as rice cookers, microwave ovens, and vacuum cleaners, and housings and parts for office equipment such as telephones and facsimiles.However, it has the disadvantage of being poorly weatherable.

[0003] To improve the weather resistance of ABS resin, ASA resin (acrylonitrile-styrene-acrylic) has been developed, in which the rubber component of ABS resin has been changed from butadiene rubber, which is unstable against light and heat, to acrylic rubber, which is relatively stable. However, ASA resin has the problem of being less impact resistant than ABS resin.

[0004] Patent Document 1 describes blending an acrylonitrile-styrene resin with a graft copolymer obtained by graft polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer, or an unsaturated acid ester monomer in the presence of crosslinked acrylic acid ester rubber particles.

[0005] On the other hand, additives for acrylic resins are known in which a core-shell type graft copolymer is copolymerized with a reactive ultraviolet absorber (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 58-222139 [Patent Document 2] International Publication No. 2015 / 133153 Summary of the Invention [Problem to be solved by the invention]

[0007] Although blending a graft copolymer containing an acrylic rubber with a thermoplastic resin such as an acrylonitrile-styrene resin can improve the impact resistance of the resin, further improvements are needed, including improvements in weather resistance.

[0008] In view of the above-described current situation, the present invention aims to provide core-shell graft copolymer particles that can be blended with a thermoplastic resin to form a resin composition having good impact resistance and weather resistance, a method for producing the same, and a resin composition containing the particles.

[0009] The present inventors have discovered that the above-mentioned problems can be solved by adopting a specific structure in acrylic rubber-containing graft copolymer particles to be added to thermoplastic resins such as acrylonitrile-styrene resins, and have arrived at the present invention.

[0010] That is, the present invention provides a core-shell graft copolymer particle comprising a core particle (A) and a shell layer (B) covering the core particle (A), the core particle (A) contains a polyalkyl(meth)acrylate rubber, At least a part of the polyalkyl(meth)acrylate rubber is copolymerized with a reactive ultraviolet absorber represented by the following formula (1): The core particles (A) have a volume average particle diameter of 400 to 800 nm, the proportion of the core particles (A) in the core-shell type graft copolymer particles is 50 to 80% by weight, The shell layer (B) relates to core-shell type graft copolymer particles, which include a layer (b1) of a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit.

[0011] [ka]

[0012] In formula (1), X represents hydrogen or halogen, and R 1 represents hydrogen, a methyl group, or a t-alkyl group having 4 to 6 carbon atoms; R 2 represents a linear or branched alkylene group having 2 to 10 carbon atoms, and R 3 represents hydrogen or a methyl group. Preferably, the core particles (A) are configured so that the degree of crosslinking on the particle surface is higher than the degree of crosslinking inside the particle. Preferably, the core particle (A) is composed of an inner layer, one or more intermediate layers, and an outer layer, The outer layer has a higher degree of crosslinking than the inner layer and the intermediate layer. Preferably, the reactive ultraviolet absorber is copolymerized with the polyalkyl(meth)acrylate rubber of the intermediate layer. Preferably, the reactive ultraviolet absorber is not copolymerized with the polyalkyl(meth)acrylate rubber of the outer layer. Preferably, the shell layer (B) further includes an outer layer (b2) located outside the layer (b1), The outer layer (b2) is formed from a polymer containing an aromatic vinyl compound unit. The present invention also provides a method for producing the core-shell graft copolymer particles, comprising the steps of: a step of polymerizing a monomer component containing alkyl (meth)acrylate with a crosslinkable monomer to form core particles (A) composed of a polyalkyl (meth)acrylate rubber; The present invention also relates to a production method comprising the step of copolymerizing a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound in the presence of the core particle (A) to form a shell layer (B), thereby obtaining the core-shell graft copolymer particle. Preferably, in the step of forming the core particle (A), a core particle (A) composed of an inner layer, one or more intermediate layers, and an outer layer is formed by multistage polymerization of a monomer component containing an alkyl(meth)acrylate and a crosslinkable monomer. The present invention further relates to a thermoplastic resin composition comprising: 100 parts by weight of a thermoplastic resin containing a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit; The present invention also relates to a resin composition containing 10 to 100 parts by weight of the core-shell type graft copolymer particles, or a molded article obtained by molding the resin composition. [Effects of the Invention]

[0013] According to the present invention, it is possible to provide acrylic rubber-containing graft copolymer particles that can be blended with a thermoplastic resin to form a resin composition that has good impact resistance and weather resistance, a method for producing the same, and a resin composition containing the particles. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, embodiments of the present invention will be described in detail. <Core-shell type graft copolymer particles> The core-shell graft copolymer particles according to the present disclosure have a core-shell structure comprising a core particle (A) and a shell layer (B) covering the core particle (A). The core particle (A) refers to a rubber particle located inside the core-shell graft copolymer particle. On the other hand, the shell layer (B) refers to a polymer layer located on the surface side of the core-shell graft copolymer particle and covering the surface of the core particle (A), and is also referred to as a graft layer. The shell layer (B) covers the surface of the core particle (A), but is not limited to covering the entire surface of the core particle (A), as long as it covers at least a portion of the surface of the core particle (A).

[0015] <Core particle (A)> The core particles (A) are formed from a polyalkyl(meth)acrylate rubber. Here, "rubber" refers to a polymer having a crosslinked structure (hereinafter also referred to as a crosslinked polymer). Since the core particles (A) are formed from a crosslinked polymer, blending the core-shell graft copolymer particles into a thermoplastic resin can impart impact resistance to the thermoplastic resin.

[0016] The core particle (A) may contain other rubbers (e.g., siloxane-based rubbers, butadiene-based rubbers, etc.) in addition to the polyalkyl(meth)acrylate rubber, but preferably consists essentially of the polyalkyl(meth)acrylate rubber alone. Specifically, the proportion of the polyalkyl(meth)acrylate rubber in the core particle (A) is preferably 90 to 100% by weight, more preferably 95 to 100% by weight, and particularly preferably 99 to 100% by weight.

[0017] The polyalkyl(meth)acrylate rubber is a crosslinked product obtained by polymerizing a monomer component containing alkyl(meth)acrylate and a crosslinkable monomer. Note that "(meth)acrylic" is a general term for acrylic and methacrylic.

[0018] The alkyl (meth)acrylate is not particularly limited, but examples thereof include alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate; and alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, 2-ethylhexyl methacrylate, and lauryl methacrylate. These monomers may be used alone or in combination of two or more.

[0019] The alkyl (meth)acrylate is preferably an acrylic acid alkyl ester. The content of the acrylic acid alkyl ester in the monomer components (excluding crosslinkable monomers) for forming the polyalkyl (meth)acrylate rubber is preferably 50 to 100% by weight, more preferably 70 to 100% by weight, even more preferably 80 to 100% by weight, still more preferably 90 to 100% by weight, and particularly preferably 95 to 100% by weight.

[0020] The number of carbon atoms in the alkyl group of the alkyl acrylate is preferably 1 to 22, more preferably 1 to 18, even more preferably 2 to 12, and still more preferably 2 to 8. The alkyl acrylate is particularly preferably butyl acrylate.

[0021] From the viewpoints of low glass transition temperature of the resulting polymer and economic efficiency, the content of butyl acrylate among the monomer components is preferably 40 to 100% by weight, more preferably 60 to 100% by weight. As the alkyl (meth)acrylate to be used in combination with butyl acrylate, methyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate are preferred.

[0022] The monomer component for forming the polyalkyl(meth)acrylate rubber may consist solely of the alkyl(meth)acrylate, or may further contain another monomer having one unsaturated bond copolymerizable with the alkyl(meth)acrylate in one molecule. The other monomer is not particularly limited, but examples thereof include (meth)acrylic monomers other than alkyl(meth)acrylate, aromatic vinyl compounds, vinyl cyanide compounds, halogenated vinyl compounds such as vinyl chloride and chloroprene, vinyl acetate, and alkenes such as ethylene and propylene.

[0023] The crosslinkable monomer used to form the polyalkyl(meth)acrylate rubber is a compound having two or more unsaturated bonds in one molecule that are copolymerizable with the alkyl(meth)acrylate. Specific examples include, but are not limited to, (meth)acrylates having an allyl group, such as allyl (meth)acrylate, allyl alkyl (meth)acrylate, and allyloxy alkyl (meth)acrylate; polyfunctional (meth)acrylates having two or more (meth)acryloyl groups, such as diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, (poly)ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and butanediol di(meth)acrylate; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. The crosslinkable monomers may be used alone or in combination of two or more. Of these, allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene are preferred, and allyl methacrylate is particularly preferred.

[0024] According to this embodiment, in order to improve the weather resistance of the resin composition, a reactive UV absorber represented by the following formula (1) is copolymerized with the polyalkyl(meth)acrylate rubber. This significantly improves the weather resistance of the resin composition obtained by blending core-shell graft copolymer particles with a thermoplastic resin. If the reactive UV absorber is not copolymerized in the core layer (A) and is copolymerized only in the shell layer (B), the effect of improving weather resistance cannot be substantially expected.

[0025] The reactive ultraviolet absorber may be copolymerized only in the core layer (A) or may be copolymerized in both the core layer (A) and the shell layer (B). However, since the effect of improving weather resistance cannot be expected even if the reactive ultraviolet absorber is copolymerized in the shell layer (B), it is preferable from the viewpoint of cost reduction that the reactive ultraviolet absorber is copolymerized only in the core layer (A) and not in the shell layer (B).

[0026] The reactive ultraviolet absorber may be copolymerized with the entire polyalkyl (meth)acrylate rubber, but it is sufficient that it is copolymerized with at least a part of the polyalkyl (meth)acrylate rubber. The copolymerization method is not particularly limited, and may be either random copolymerization or block copolymerization, but random copolymerization is preferred.

[0027] [ka]

[0028] In the formula (1), X represents hydrogen or halogen. 1 represents hydrogen, a methyl group, or a t-alkyl group having 4 to 6 carbon atoms. 2 represents a linear or branched alkylene group having 2 to 10 carbon atoms, and is preferably an ethylene group or a propylene group. 3 represents hydrogen or a methyl group.

[0029] Specific examples of the reactive ultraviolet absorber include 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazoles, such as 2-(2'-hydroxy-5'-acryloyloxyethylphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole, 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-5-chloro-2H-benzotriazole, 2-(2'-hydroxy-5'-methacryloyloxypropylphenyl)-2H-benzotriazole, and 2-(2'-hydroxy-5'-methacryloyloxyethyl-3'-t-butylphenyl)-2H-benzotriazole. In view of cost and ease of handling, 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole is more preferred.

[0030] From the viewpoint of a balance between weather resistance and impact resistance, the amount of the reactive ultraviolet absorber used is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 8 parts by weight, even more preferably 0.4 to 5 parts by weight, and particularly preferably 0.5 to 3 parts by weight, relative to 100 parts by weight of the core-shell graft copolymer particles.

[0031] The proportion of the core particles (A) in the entire core-shell graft copolymer particles is 50% by weight or more and 80% by weight or less from the viewpoint of impact resistance. The lower limit is preferably 55% by weight or more, more preferably 60% by weight or more, even more preferably 65% ​​by weight or more, and particularly preferably 68% by weight or more. The upper limit is preferably 78% by weight or less, more preferably 75% by weight or less, and even more preferably 73% by weight or less.

[0032] From the viewpoint of impact resistance and productivity, the volume average particle diameter of the core particles (A) is 400 nm or more and 800 nm or less. If the particle diameter is less than 400 nm, the impact resistance becomes insufficient when the core-shell graft copolymer particles are blended with a thermoplastic resin. On the other hand, if the particle diameter exceeds 800 nm, the productivity of the core-shell graft copolymer particles tends to decrease. The lower limit is preferably 430 nm or more, more preferably 450 nm or more, even more preferably 480 nm or more, and particularly preferably 500 nm or more. The upper limit is preferably 750 nm or less, more preferably 700 nm or less, and even more preferably 650 nm or less.

[0033] The volume average particle diameter of the core particles (A) is a value measured in the state of a latex of the polymer particles using a particle diameter measuring device, as shown in the Examples section. The particle diameter of the core particles (A) can be controlled by the types and amounts of initiators, reducing agents, emulsifiers, etc. used in the polymerization, the polymerization temperature, the polymerization time, etc.

[0034] From the viewpoint of improving impact resistance, the core particles (A) are preferably configured so that the degree of crosslinking on the surface of the particle is higher than the degree of crosslinking inside the particle. By adopting such a specific configuration for the degree of crosslinking of the core particles (A), it becomes possible to significantly improve the impact resistance of the thermoplastic resin by incorporating the core-shell graft copolymer particles. The degree of crosslinking refers to the density of the crosslinked structure introduced into the polymer by the crosslinkable monomer. The degree of crosslinking can be controlled by adjusting the ratio of the amount of crosslinkable monomer to the amount of monomer component (concentration of crosslinkable monomer), and the higher the ratio of the amount of crosslinkable monomer, the higher the degree of crosslinking.

[0035] According to one aspect of this embodiment, the core particle (A) may have a multilayer structure consisting of at least two layers. In this multilayer structure, the degree of crosslinking in each layer can be adjusted so that the degree of crosslinking on the surface of the core particle (A) is higher than the degree of crosslinking inside the core particle (A). Specifically, the core particle (A) preferably includes at least an inner core layer located inside the particle and an outer core layer located on the surface side of the particle, and the degree of crosslinking of the outer core layer is preferably higher than the degree of crosslinking of the inner core layer.

[0036] The core particle (A) may have a two-layer structure consisting of only the inner core layer and the outer core layer. However, from the viewpoint of improving impact resistance, it is preferable that the core particle (A) further comprises at least one intermediate core layer between the inner core layer and the outer core layer, and in this case, it is preferable that the degree of crosslinking of the outer core layer is higher than the degrees of crosslinking of the inner core layer and the intermediate core layer.

[0037] The core inner layer, the core intermediate layer, and the core outer layer each preferably consist essentially of the polyalkyl(meth)acrylate rubber. Specifically, the proportion of the polyalkyl(meth)acrylate rubber in each layer is preferably 90 to 100 wt %, more preferably 95 to 100 wt %, and particularly preferably 99 to 100 wt %. The types or amounts of the monomer components constituting each layer and the types of crosslinkable monomers used in each layer may be the same or different.

[0038] The ratio of the amount of crosslinkable monomer in each layer is preferably selected within the range of 0.01 to 20 parts by weight relative to 100 parts by weight of the monomer components constituting each layer, more preferably 0.05 to 15 parts by weight, even more preferably 0.08 to 12 parts by weight, and particularly preferably 0.1 to 10 parts by weight.

[0039] Specifically, the ratio of the amount of crosslinkable monomer in the core inner layer is preferably 0.01 to 3 parts by weight, more preferably 0.05 to 2 parts by weight, even more preferably 0.08 to 1 part by weight, and even more preferably 0.1 to 0.5 parts by weight, relative to 100 parts by weight of the monomer components constituting the core inner layer.

[0040] The ratio of the crosslinkable monomer in the intermediate core layer is preferably greater than that in the inner core layer and less than that in the outer core layer. Specifically, the ratio of the crosslinkable monomer in the intermediate core layer is preferably 0.05 to 5 parts by weight, more preferably 0.1 to 3 parts by weight, even more preferably 0.15 to 2 parts by weight, and even more preferably 0.2 to 1 part by weight, per 100 parts by weight of the monomer components constituting the intermediate core layer.

[0041] There may be multiple core intermediate layers, and in this case, the ratio of the crosslinkable monomer content in the first intermediate layer located closer to the core inner layer (i.e., closer to the inside) is preferably lower than the ratio of the crosslinkable monomer content in the second intermediate layer located farther from the core inner layer (i.e., closer to the surface).

[0042] The ratio of the crosslinkable monomer in the outer core layer is preferably greater than the ratio of the crosslinkable monomer in the inner core layer and the ratio of the crosslinkable monomer in the intermediate core layer. Specifically, the ratio of the crosslinkable monomer in the outer core layer is preferably 0.1 to 20 parts by weight, more preferably 1 to 15 parts by weight, even more preferably 3 to 12 parts by weight, and even more preferably 5 to 10 parts by weight, per 100 parts by weight of the monomer components constituting the outer core layer.

[0043] The proportion of each layer of the core particle (A) in the entire core-shell graft copolymer particle is not particularly limited, but from the viewpoint of impact resistance, the total proportion of the core inner layer and the core intermediate layer is preferably 30 to 79% by weight, more preferably 40 to 70% by weight, and even more preferably 50 to 65% by weight. The proportion of the core outer layer is preferably 1 to 30% by weight, more preferably 2 to 20% by weight, and even more preferably 3 to 10% by weight.

[0044] The reactive UV absorber may be copolymerized in at least one of the inner core layer, the intermediate core layer, and the outer core layer. In particular, because of its significant effect in improving weather resistance, the reactive UV absorber is preferably copolymerized in at least the polyalkyl(meth)acrylate rubber in the intermediate core layer, and more preferably in both the polyalkyl(meth)acrylate rubber in the inner core layer and the polyalkyl(meth)acrylate rubber in the intermediate core layer. On the other hand, it is preferable that the reactive ultraviolet absorber is not copolymerized with the polyalkyl(meth)acrylate rubber of the core outer layer, because even if the reactive ultraviolet absorber is copolymerized with the core outer layer, the effect of improving weather resistance is relatively low.

[0045] According to another aspect of this embodiment, the core particle (A) may be configured so that the degree of crosslinking increases from the center to the surface of the particle. The degree of crosslinking may be configured so that it increases continuously or discontinuously. Core particles (A) having such a configuration can be produced by controlling the amounts of the monomer components and the crosslinkable monomer added during particle formation so that the ratio of the amount of the crosslinkable monomer to the amount of the monomer components increases over time.

[0046] In this embodiment, the ratio of the amount of the crosslinkable monomer is preferably adjusted within a range of 0.01 to 20 parts by weight relative to 100 parts by weight of the monomer components constituting the core particles (A), more preferably 0.05 to 15 parts by weight, even more preferably 0.08 to 12 parts by weight, and particularly preferably 0.1 to 10 parts by weight.

[0047] <Shell layer (B)> The shell layer (B) is a polymer layer that covers the surface of the core particle (A) and is located on the surface side of the core-shell graft copolymer particle. At least a portion of the shell layer (B) is preferably graft-bonded to the core particle (A), but the shell layer (B) also contains a polymer that is not graft-bonded. The shell layer (B) improves the compatibility between the core-shell graft copolymer particle and the thermoplastic resin, allowing the core-shell graft copolymer particle to be dispersed in the resin composition as primary particles.

[0048] The shell layer (B) contains at least a layer (b1) formed from a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit to improve compatibility with the thermoplastic resin. The copolymer may further contain a (meth)acrylic acid ester unit.

[0049] The aromatic vinyl compound is not particularly limited, but examples thereof include styrene, α-methylstyrene, p-methylstyrene, p-isopropylstyrene, o-chlorostyrene, p-chlorostyrene, dichlorostyrene, etc. Among these, styrene is preferred.

[0050] The vinyl cyanide compound is not particularly limited, but examples thereof include acrylonitrile, methacrylonitrile, etc. Among these, acrylonitrile is preferred.

[0051] The (meth)acrylic acid ester is not particularly limited, and examples thereof include (meth)acrylic acid alkyl esters such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate; aromatic ring-containing (meth)acrylates such as phenoxyethyl (meth)acrylate and benzyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate; glycidyl (meth)acrylates such as glycidyl (meth)acrylate and glycidyl alkyl (meth)acrylate; and alkoxyalkyl (meth)acrylates.

[0052] From the viewpoint of compatibility with thermoplastic resins, the proportion of aromatic vinyl compound units in the entire copolymer constituting layer (b1) is preferably 30% by weight to 95% by weight, more preferably 50% by weight to 90% by weight, even more preferably 60% by weight to 85% by weight, and particularly preferably 70% by weight to 82% by weight. The proportion of vinyl cyanide compound units is preferably 5% by weight to 70% by weight, more preferably 10% by weight to 50% by weight, even more preferably 15% by weight to 40% by weight, and particularly preferably 18% by weight to 30% by weight. Furthermore, the proportion of the (meth)acrylic acid ester is preferably 0% by weight to 20% by weight, more preferably 10% by weight to 5% by weight, even more preferably 5% by weight to 1% by weight.

[0053] The shell layer (B) may be composed of only the layer (b1), or may further include an outer layer (b2) located outside the layer (b1) in addition to the layer (b1). The outer layer (b2) is preferably formed from a polymer containing an aromatic vinyl compound unit. By including such an outer layer (b2), the impact resistance of the thermoplastic resin can be further improved.

[0054] The aromatic vinyl compound that can be used in the outer layer (b2) is not particularly limited, and specific examples of the aromatic vinyl compound that can be used in the outer layer (b2) include those mentioned above in relation to the layer (b1). The polymer constituting the outer layer (b2) may be composed only of aromatic vinyl compound units, but may also contain vinyl cyanide compound units and / or (meth)acrylic acid ester units.

[0055] The proportion of aromatic vinyl compound units in the entire polymer constituting the outer layer (b2) is preferably higher than the proportion of aromatic vinyl compound units in the entire copolymer constituting the layer (b1). By providing an outer layer (b2) with a relatively high proportion of aromatic vinyl compound units, it is possible to further improve the impact resistance of the thermoplastic resin. Specifically, the proportion of aromatic vinyl compound units in the entire polymer constituting the outer layer (b2) is preferably 50% by weight or more and 100% by weight or less, more preferably 70% by weight or more, even more preferably 75% by weight or more, and particularly preferably 80% by weight or more.

[0056] The weight ratio of layer (b1) to outer layer (b2) is not particularly limited, but may be, for example, about 30:70 to 99:1. From the viewpoint of improving compatibility with thermoplastic resins and enhancing impact resistance, it is preferably 40:60 to 95:5, more preferably 50:50 to 90:10.

[0057] The shell layer (B) may be composed of only the layer (b1) and the outer layer (b2), or may further include, in addition to these two layers, a layer that does not fall into either the layer (b1) or the outer layer (b2).

[0058] The shell layer (B), layer (b1), and outer layer (b2) may be formed from a polymer having a crosslinked structure, but are preferably formed from a polymer not having a crosslinked structure, i.e., the shell layer (B), layer (b1), and outer layer (b2) are preferably formed from a polymer produced without using a crosslinkable monomer.

[0059] From the viewpoint of impact resistance, the proportion of the shell layer (B) in the entire core-shell graft copolymer particles is preferably 20% by weight or more and 50% by weight or less. The lower limit is more preferably 22% by weight or more, even more preferably 25% by weight or more, and most preferably 27% by weight or more. The upper limit is more preferably 45% by weight or less, even more preferably 40% by weight or less, even more preferably 35% by weight or less, and particularly preferably 32% by weight or less.

[0060] <Method for producing core-shell graft copolymer particles> The core-shell graft copolymer particles may be produced by any method, including, but not limited to, emulsion polymerization, miniemulsion polymerization, microemulsion polymerization, and emulsifier-free (soap-free) emulsion polymerization. Of these, emulsion polymerization is preferred.

[0061] The emulsifier that can be used in emulsion polymerization is not particularly limited, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, amphoteric surfactants, etc. Dispersants such as polyvinyl alcohol, alkyl-substituted cellulose, polyvinylpyrrolidone, and polyacrylic acid derivatives may also be used in combination.

[0062] The anionic surfactant is not particularly limited, and examples thereof include the following compounds: fatty acid soaps such as potassium laurate, potassium coconut fatty acid, potassium myristate, potassium oleate, potassium oleate diethanolamine salt, sodium oleate, potassium palmitate, potassium stearate, sodium stearate, mixed fatty acid soda soap, semi-hardened beef tallow fatty acid soda soap, and castor oil potassium soap; alkyl sulfates such as sodium dodecyl sulfate, higher alcohol sodium sulfate, triethanolamine dodecyl sulfate, ammonium dodecyl sulfate, sodium polyoxyethylene alkyl ether sulfate, triethanolamine polyoxyethylene alkyl ether sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate, and sodium 2-ethylhexyl sulfate; Acid ester salts; sodium alkylbenzenesulfonates such as sodium dodecylbenzenesulfonate; sodium dialkylsulfosuccinates such as sodium di-2-ethylhexyl sulfosuccinate; sodium alkylnaphthalenesulfonates; sodium alkyldiphenyletherdisulfonates; potassium alkylphosphate salts; phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate; sodium salts of naphthalenesulfonic acid formalin condensates; polycarboxylic acid type polymeric anions; sodium acyl (beef tallow) methyl taurate; sodium acyl (coconut) methyl taurate; sodium cocoyl isethionate; sodium α-sulfofatty acid ester salts; sodium amidoethersulfonate; oleyl sarcosine; sodium lauroyl sarcosine; rosin acid soap, etc.

[0063] The nonionic surfactant is not particularly limited, and examples thereof include the following compounds: polyoxyethylene alkyl allyl ethers or polyoxyethylene alkyl ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene oleyl ether, and polyoxyethylene lauryl ether; polyoxyethylene sorbitan esters such as polyoxyethylene sorbitan monolaurate and polyoxyethylene sorbitan monostearate; polyoxyethylene fatty acid esters such as polyethylene glycol monolaurate, polyethylene glycol monostearate, and polyethylene glycol monooleate; and oxyethylene / oxypropylene block copolymers.

[0064] The cationic surfactant is not particularly limited, and examples thereof include the following compounds: alkylamine salts such as coconut amine acetate, stearyl amine acetate, octadecyl amine acetate, and tetradecyl amine acetate; and quaternary ammonium salts such as lauryl trimethyl ammonium chloride, stearyl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, distearyl dimethyl ammonium chloride, alkyl benzyl dimethyl ammonium chloride, hexadecyl trimethyl ammonium chloride, and behenyl trimethyl ammonium chloride.

[0065] The amphoteric surfactant is not particularly limited, and examples thereof include the following compounds: alkyl betaines such as lauryl betaine, stearyl betaine, and dimethyl lauryl betaine; sodium lauryl diaminoethyl glycine; amido betaine; imidazoline; and lauryl carboxymethyl hydroxyethyl imidazolinium betaine.

[0066] These emulsifiers may be used alone or in combination of two or more. As the emulsifier, sodium dialkyl sulfosuccinate or a surfactant having an oxyethylene structure is preferred, and sodium polyoxyethylene lauryl ether phosphate is particularly preferred. The average particle size of the polymer particles can be controlled by adjusting the amount of the emulsifier used.

[0067] When emulsion polymerization is employed, known polymerization initiators, such as 2,2'-azobisisobutyronitrile, hydrogen peroxide, potassium persulfate, and ammonium persulfate, can be used as thermal decomposition initiators.

[0068] Alternatively, a redox initiator can be used which is a combination of a peroxide, such as an organic peroxide (e.g., t-butyl peroxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, or t-hexyl peroxide); or an inorganic peroxide (e.g., hydrogen peroxide, potassium persulfate, or ammonium persulfate), with at least one reducing agent selected from the group consisting of sodium formaldehyde sulfoxylate, glucose; transition metal salts (e.g., iron (II) sulfate); chelating agents (e.g., disodium ethylenediaminetetraacetate); and pyrophosphates (e.g., sodium pyrophosphate).

[0069] When a redox initiator is used, polymerization can be carried out even at a low temperature where the peroxide does not substantially decompose thermally, and the polymerization temperature can be set within a wide range, which is preferable. Among these, organic peroxides such as cumene hydroperoxide, dicumyl peroxide, and t-butyl hydroperoxide are preferably used as the redox initiator. The amount of the initiator used, and when a redox initiator is used, the amount of the reducing agent, transition metal salt, chelating agent, etc. used may be within known ranges. Furthermore, when polymerizing the crosslinkable monomer, known chain transfer agents can be used in known amounts. A surfactant can also be used, but this is also within known ranges.

[0070] The solvent used during emulsion polymerization may be any solvent that allows the emulsion polymerization to proceed stably, and for example, water can be suitably used.

[0071] The temperature during emulsion polymerization is not particularly limited as long as the emulsifier is dissolved uniformly in the solvent, but is, for example, 40 to 75°C, preferably 45 to 70°C, and more preferably 49 to 65°C.

[0072] Specifically, the core-shell graft copolymer particles according to the present disclosure can be produced by carrying out the following steps (I) to (III) in order, except that step (III) is an optional step and may not be carried out. Step (I): First, in the presence of an emulsifier and an initiator, a monomer component containing alkyl (meth)acrylate and the reactive UV absorber, and a crosslinkable monomer are polymerized to form core particles (A) of polyalkyl (meth)acrylate rubber copolymerized with the reactive UV absorber. At this time, it is preferable to form rubber particles configured so that the degree of crosslinking on the surface of the rubber particle is higher than the degree of crosslinking inside the rubber particle.

[0073] According to one aspect of this embodiment, in step (I), a core particle (A) composed of an inner layer, one or more intermediate layers, and an outer layer can be formed by multistage polymerization of a monomer component containing an alkyl(meth)acrylate and the reactive UV absorber, and a crosslinkable monomer.

[0074] For example, first, a monomer component containing alkyl (meth)acrylate and the reactive UV absorber, a crosslinkable monomer, an initiator, etc. are added and polymerized to form particles of the inner core layer. Next, a monomer component containing alkyl (meth)acrylate and the reactive UV absorber, a crosslinkable monomer, and an initiator, etc., are added to the system containing the particles of the inner core layer and further polymerized to form a core intermediate layer that covers the inner core layer. Next, a monomer component containing alkyl (meth)acrylate and a crosslinkable monomer, and an initiator, etc., are added to the system containing the inner core layer and the intermediate core layer and further polymerized to form a core outer layer that covers the intermediate core layer. In this case, by setting the ratio of the amount of crosslinkable monomer to the monomer component when forming the outer core layer higher than the ratio of the amount of crosslinkable monomer to the monomer component when forming the inner core layer or the intermediate core layer, rubber particles can be formed that have a higher degree of crosslinking on the surface than in the interior.

[0075] According to another aspect of this embodiment, in step (I), polymerization is carried out while adding a monomer component and a crosslinkable monomer to the reaction system, and the amounts of the monomer component and the crosslinkable monomer added are controlled so that the ratio of the amount of the crosslinkable monomer to the monomer component increases over time. This makes it possible to form rubber particles in which the degree of crosslinking increases from the center to the surface of the rubber particle. The ratio of the amount of the crosslinkable monomer to the monomer component may be increased continuously or discontinuously. It may also be increased linearly or nonlinearly. The monomer component and the crosslinkable monomer may be added separately or as a mixture.

[0076] Step (II): To the system containing the core particles (A) obtained in Step (I), monomer components containing an aromatic vinyl compound and a vinyl cyanide compound, and optionally an initiator, are added, and the monomer components are copolymerized in the presence of the core particles (A) to form a layer (b1) composed of a copolymer containing aromatic vinyl compound units and vinyl cyanide compound units. This allows the production of core-shell graft copolymer particles containing the core particles (A) and the layer (b1) that is the shell layer (B).

[0077] Step (III): To the system containing the core-shell graft copolymer particles obtained in Step (II), a monomer component containing an aromatic vinyl compound, and optionally an initiator, etc., are added, and the monomer component is copolymerized in the presence of the core-shell graft copolymer particles to form an outer layer (b2) composed of a polymer containing an aromatic vinyl compound unit. This allows the production of core-shell graft copolymer particles containing core particles (A) and layers (b1) and (b2) as shell layers (B).

[0078] By carrying out the steps (I) to (III), a latex of the core-shell graft copolymer particles can be obtained. By agglomerating the polymer particles in the latex, a powder of the polymer particles can be obtained. The method for aggregating the polymer microparticles is not particularly limited, and known methods can be applied. For example, (a) a method of contacting (e.g., mixing) latex with a flocculant (e.g., alkaline earth metal salts such as calcium chloride, magnesium chloride, and magnesium sulfate; alkali metal salts such as sodium chloride and sodium sulfate; acids such as hydrochloric acid, sulfuric acid, phosphoric acid, and acetic acid) or an aqueous solution containing the flocculant to form a slurry, followed by heat treatment as necessary and dehydration and drying, (b) a method of mixing latex with a highly hydrophobic organic solvent (e.g., methyl ethyl ketone), (c) a method of freezing latex and then thawing it, (d) a method of applying shear stress to latex, and (e) a method of spray-drying latex, etc., can be mentioned.

[0079] <Resin composition> By blending the core-shell graft copolymer particles according to the present disclosure with a thermoplastic resin to form a resin composition, the impact resistance and weather resistance of the thermoplastic resin can be improved.

[0080] The thermoplastic resin preferably contains a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit. The aromatic vinyl compound constituting the copolymer is not particularly limited, but examples thereof include styrene, α-methylstyrene, p-methylstyrene, p-isopropylstyrene, o-chlorostyrene, p-chlorostyrene, dichlorostyrene, etc. These may be used alone or in combination of two or more. Among these, styrene and α-methylstyrene are preferred, and styrene is particularly preferred.

[0081] The vinyl cyanide compound constituting the copolymer is not particularly limited, but examples thereof include acrylonitrile, methacrylonitrile, etc. These may be used alone or in combination of two or more. Acrylonitrile is preferred.

[0082] The copolymer may be a copolymer composed only of aromatic vinyl compound units and vinyl cyanide compound units, or may be a copolymer containing other copolymerizable vinyl compound units in addition to these two types of units.

[0083] The other copolymerizable vinyl compounds are not particularly limited, and examples thereof include (meth)acrylic acid alkyl esters having an alkyl group of 1 to 12 carbon atoms, such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, maleimide compounds such as maleimide, N-phenylmaleimide, and cyclohexylmaleimide, acrylic acid, methacrylic acid, isopropenylnaphthalene, acrylamide, methacrylamide, glycidyl acrylate, and glycidyl methacrylate. These compounds may be used alone or in combination of two or more.

[0084] The content of the aromatic vinyl compound in the copolymer is not particularly limited, but is preferably 60 to 85% by weight, more preferably 65 to 80% by weight. The content of the vinyl cyanide compound is also not particularly limited, but is preferably 15 to 40% by weight, more preferably 20 to 35% by weight. The content of the other copolymerizable vinyl compound is also not particularly limited, but is preferably 0 to 25% by weight, more preferably 0 to 15% by weight.

[0085] Specific examples of the copolymer include styrene-acrylonitrile copolymer, α-methylstyrene-acrylonitrile copolymer, styrene-α-methylstyrene-acrylonitrile copolymer, styrene-maleimide-acrylonitrile copolymer, styrene-α-methylstyrene-maleimide-acrylonitrile copolymer, styrene-acrylonitrile-methyl methacrylate copolymer, α-methylstyrene-acrylonitrile-methyl methacrylate copolymer, styrene-α-methylstyrene-acrylonitrile-methyl methacrylate copolymer, styrene-maleimide-acrylonitrile-methyl methacrylate copolymer, styrene-α-methylstyrene-maleimide-acrylonitrile-methyl methacrylate copolymer, etc. These may be used alone or in combination of two or more.

[0086] The thermoplastic resin contained in the resin composition may be the copolymer alone, or may further contain a thermoplastic resin other than the copolymer. Examples of such thermoplastic resins include, but are not limited to, acrylic resins such as polymethyl methacrylate, vinyl chloride resins, polycarbonate resins, amide resins, and polyester resins. These may be used alone or in combination of two or more. The content of the thermoplastic resin other than the copolymer may be approximately 0 to 50% by weight, 0 to 30% by weight, 0 to 10% by weight, 0 to 5% by weight, or 0 to 1% by weight, based on the total weight of the thermoplastic resin.

[0087] From the viewpoint of improving impact resistance and weather resistance, the content of the core-shell graft copolymer particles in the resin composition is preferably 10 to 100 parts by weight, more preferably 15 to 80 parts by weight, even more preferably 20 to 60 parts by weight, and particularly preferably 25 to 50 parts by weight, relative to 100 parts by weight of the thermoplastic resin.

[0088] The resin composition may contain, as needed, flame retardants, antibacterial agents, release agents, nucleating agents, plasticizers, antioxidants, heat stabilizers, light stabilizers, UV absorbers, compatibilizers, pigments, dyes, antistatic agents, lubricants, etc. The amount of each additive to be added can be determined appropriately by those skilled in the art. These additives may be used alone or in combination of two or more.

[0089] In particular, phenol-based, sulfur-based, phosphorus-based, and hindered amine-based antioxidants or stabilizers; benzophenone-based and benzotriazole-based ultraviolet absorbers; and internal and external lubricants such as organopolysiloxanes, aliphatic hydrocarbons, esters of higher fatty acids and higher alcohols, amides or bisamides of higher fatty acids and modified products thereof, oligoamides, and metal salts of higher fatty acids can be suitably added.

[0090] The resin composition can be produced, for example, by mixing the core-shell graft copolymer particles and the thermoplastic resin in the form of a latex, a slurry, a solution, a powder, pellets, or a combination thereof. In the case of a latex containing the core-shell graft copolymer particles and the thermoplastic resin, a powder containing the polymer particles and the thermoplastic resin can be obtained by aggregating the polymer particles and the thermoplastic resin in the latex. Known methods can be used to aggregate the polymer particles and the thermoplastic resin. Specifically, the methods described above can be used to aggregate the polymer fine particles.

[0091] The resin composition can be prepared by blending any additives as needed with the core-shell graft copolymer particles and the thermoplastic resin powder, pellets, or the like, kneading the mixture in a known melt kneader such as a Banbury mixer, a roll mill, a single-screw extruder, or a twin-screw extruder, and shaping the mixture into a desired molded product by a known molding method such as injection molding, extrusion molding, or blow molding.

[0092] The resin composition can be used in a variety of applications, including electrical and electronic applications, construction applications, and vehicle applications. Specifically, it can be used in electrical and electronic applications such as personal computers, liquid crystal displays, projectors, PDAs, printers, copiers, fax machines, video cameras, digital cameras, mobile phones (smartphones), portable audio devices, game consoles, DVD recorders, microwave ovens, and rice cookers; construction applications such as road translucent panels, skylights, carports, lighting lenses, lighting covers, building sizing, and doors; and vehicle applications such as steering wheels, shift levers, and vibration-proofing materials for automobiles and trains, as well as displays, lighting, and driver's seat panels. [Example]

[0093] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In the following, "%" means "% by weight" unless otherwise specified.

[0094] (Method for measuring volume average particle size of polymer particles) The volume average particle diameter of the polymer particles was measured in the state of polymer particle latex. The measuring device used was Nanotrac Wave manufactured by Nikkiso Co., Ltd. The calculation mode was set to UPA compatible mode.

[0095] (polymerization conversion rate) A portion of the obtained latex was sampled and weighed, and dried in a hot air oven at 120°C for 1 hour. The weight after drying was then weighed as the solid content. The ratio of the weighed weights before and after drying was calculated as the solid content in the latex. Finally, the polymerization conversion rate was calculated using the solid content ratio according to the following formula. Polymerization conversion rate = (total weight of raw materials charged × solid component ratio - total weight of raw materials other than monomers) / weight of charged monomer × 100 (%)

[0096] Example 1 (core inner layer) 180 parts by weight of deionized water and 0.00075 parts by weight of dioctyl sodium sulfosuccinate (Pelex OT-P manufactured by Kao Corporation) were charged into an 8 L polymerization reactor, the temperature was raised to 45° C., and nitrogen was flowed through.

[0097] A mixture of 5 parts by weight of butyl acrylate (abbreviated "BA"), 0.00625 parts by weight of allyl methacrylate (abbreviated "ALMA") (0.125% based on the monomer), and 0.015 parts by weight of 69% t-butyl hydroperoxide was added to the polymerization reactor, and 0.0033 parts by weight of a mixture of disodium ethylenediaminetetraacetate and ferrous sulfate in a 5:3 ratio dissolved in deionized water to a concentration of 0.5% by weight and 0.04 parts by weight of 5% by weight sodium formaldehyde sulfoxylate were added and stirred for 30 minutes. The particle size of the resulting particles was 200 nm. Then, a mixture of 19.77 parts by weight of butyl acrylate, 0.23 parts by weight of the reactive UV absorber represented by formula (1) (DAINSORB T-31 manufactured by Daiwa Kasei Co., Ltd., chemical name: 2-(2'-hydroxy-5'-methacryloxyethylphenyl)-2H-benzotriazole, hereinafter referred to as "RUVA"), 0.025 parts by weight of allyl methacrylate (0.125% based on the monomer), and 0.006 parts by weight of 69% t-butyl hydroperoxide was added over 60 minutes. This formed particles corresponding to the core inner layer.

[0098] (Core middle layer) Next, a mixture of 19.77 parts by weight of butyl acrylate, 0.23 parts by weight of RUVA, 0.05 parts by weight of allyl methacrylate (0.25% based on the monomer), and 0.006 parts by weight of 69% t-butyl hydroperoxide was added over 60 minutes to form the first intermediate layer of the core particles. Then, a mixture of 19.77 parts by weight of butyl acrylate, 0.23 parts by weight of RUVA, 0.1 parts by weight of allyl methacrylate (0.50% based on the monomer), and 0.006 parts by weight of 69% t-butyl hydroperoxide was added over 60 minutes to form the second intermediate layer of the core particles.

[0099] (Core outer layer) After 30 minutes, a mixture of 5 parts by weight of butyl acrylate, 0.45 parts by weight of allyl methacrylate (9% based on the monomer), and 0.01 parts by weight of 69% t-butyl hydroperoxide was added over 15 minutes, followed by the addition of 0.012 parts by weight of 69% t-butyl hydroperoxide and stirring for 30 minutes. This formed a core outer layer, yielding core particles (A). The volume average particle diameter of the core particles was 500 nm.

[0100] (shell layer) Next, a mixture of 22.5 parts by weight of styrene (abbreviated as "ST"), 7.5 parts by weight of acrylonitrile (abbreviated as "AN"), 0.15 parts by weight of 69% t-butyl hydroperoxide, and 1.46 parts by weight of 25% polyoxyethylene lauryl ether phosphate (Phosphanol RD-510Y manufactured by Toho Chemical Industry Co., Ltd.) saponified with sodium hydroxide was added over 120 minutes. Appropriate amounts of t-butyl hydroperoxide and sodium formaldehyde sulfoxylate were added to form the layer (b1) which is the shell layer (B), thereby obtaining a core-shell graft copolymer latex with a conversion rate of 100% and a solids concentration of 32.3%.

[0101] Example 2 The core particles (A) were prepared in the same manner as in Example 1.

[0102] (layer(b1)) Next, a mixture of 17.5 parts by weight of styrene, 7.5 parts by weight of acrylonitrile, 0.1 parts by weight of 69% t-butyl hydroperoxide, and 1.46 parts by weight of 25% polyoxyethylene lauryl ether phosphate (Phosphanol RD-510Y manufactured by Toho Chemical Industry Co., Ltd.) saponified with sodium hydroxide was added over 100 minutes to form layer (b1).

[0103] (Outer layer (b2)) After 15 minutes, a mixture of 5 parts by weight of styrene and 0.05 parts by weight of 69% t-butyl hydroperoxide was added over 20 minutes to form the outer layer (b2), and t-butyl hydroperoxide and sodium formaldehyde sulfoxylate were added appropriately to obtain a core-shell graft copolymer latex with a conversion rate of 100% and a solids concentration of 32.1%. The core-shell graft copolymer had a layer (b1) and an outer layer (b2) as the shell layer (B).

[0104] (Examples 3 to 9 and Comparative Examples 1 to 6) In Examples 3, 5 to 9 and Comparative Examples 2 to 6, core-shell type graft copolymer latexes were obtained in the same manner as in Example 2, except that the amounts of each component added were changed as shown in Table 1. In Example 4 and Comparative Example 1, a core-shell type graft copolymer latex was obtained in the same manner as in Example 2, except that the volume average particle diameter of the core particles (A) was adjusted to the value shown in Table 1 by adjusting the initial amount of dioctyl sodium sulfosuccinate added.

[0105] <Agglomeration of core-shell type graft copolymer> A calcium chloride aqueous solution was added to each of the core-shell graft copolymer latexes obtained above to form a slurry, which was then dehydrated in a centrifugal dehydrator, washed with deionized water, and dried at 50°C for 2 days to obtain a powder of each core-shell graft copolymer.

[0106] (Method for measuring Izod impact strength) 35 parts by weight of the resulting core-shell graft copolymer powder, 64.6 parts by weight of AS resin (PN-117, manufactured by Chimei), and 0.6 parts by weight of carbon black masterbatch (AS resin blended with 40% carbon black) were mixed and kneaded in an extruder (TEX44SS manufactured by The Japan Steel Works, Ltd.) to obtain pellets. These pellets were injected into an injection molding machine (160MSP manufactured by Mitsubishi Heavy Industries, Ltd.) to obtain 1 / 8-inch bars with a thickness of 3 mm. Notched Izod impact strength was measured at 23°C in accordance with JIS K-7110. The results are shown in Table 1.

[0107] (Weather resistance (△E) measurement method) Using an accelerated weathering tester (X75 manufactured by Suga Test Instruments Co., Ltd.) in accordance with GB / T16422.2, the test pieces were left for 1,500 hours, after which the degree of discoloration was measured with a color difference meter and the ΔE value was calculated using the following formula.

[0108] Here, ΔE is the arithmetic mean value of the CIE L, a, and b values ​​before and after the weather resistance experiment, and the closer the value is to 0, the better the weather resistance.

[0109]

number

[0110] [Table 1]

[0111] From Table 1, it can be seen that Examples 1 to 9 have larger Izod impact strength values ​​and better impact resistance than Comparative Examples 1 to 4, and have smaller ΔE values ​​and better weather resistance than Comparative Examples 4 to 6.

[0112] In Comparative Example 1, the volume average particle diameter of the core particles (A) is as small as 350 nm. In Comparative Example 2, the proportion of the core particles (A) in the entire core-shell graft copolymer is as small as 45 wt %. In Comparative Example 3, the proportion of the core particles (A) in the entire core-shell graft copolymer is as large as 85 wt %. In Comparative Examples 4 and 5, RUVA was not copolymerized into the core particles (A), and in Comparative Example 6, RUVA was not copolymerized into the core particles (A) but was copolymerized into the shell layer (B).

Claims

1. A core-shell graft copolymer particle comprising a core particle (A) and a shell layer (B) covering the core particle (A), the core particle (A) contains a polyalkyl(meth)acrylate rubber, a reactive ultraviolet absorber represented by the following formula (1) is copolymerized with at least a part of the polyalkyl(meth)acrylate rubber, the core particles (A) have a volume average particle diameter of 400 to 800 nm; the ratio of the core particles (A) to the core-shell type graft copolymer particles is 50 to 80% by weight, The core-shell type graft copolymer particles, wherein the shell layer (B) comprises a layer (b1) of a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit. 【Chemistry 1】 In formula (1), X represents hydrogen or halogen, and R １ represents hydrogen, a methyl group, or a t-alkyl group having 4 to 6 carbon atoms; R ２ represents a linear or branched alkylene group having 2 to 10 carbon atoms; R ３ represents hydrogen or a methyl group.

2. 2. The core-shell type graft copolymer particle according to claim 1, wherein the core particle (A) is configured so that the degree of crosslinking on the particle surface is higher than the degree of crosslinking inside the particle.

3. the core particle (A) is composed of an inner layer, one or more intermediate layers, and an outer layer, The core-shell graft copolymer particle according to claim 1 or 2, wherein the outer layer has a higher degree of crosslinking than the inner layer and the intermediate layer.

4. 4. The core-shell graft copolymer particle according to claim 3, wherein the reactive ultraviolet absorber is copolymerized with the polyalkyl(meth)acrylate rubber of the intermediate layer.

5. 5. The core-shell graft copolymer particle according to claim 3, wherein the reactive ultraviolet absorber is not copolymerized with the polyalkyl(meth)acrylate rubber of the outer layer.

6. The shell layer (B) further includes an outer layer (b2) located outside the layer (b1), 6. The core-shell type graft copolymer particle according to claim 1, wherein the outer layer (b2) is formed from a polymer containing an aromatic vinyl compound unit.

7. A method for producing the core-shell graft copolymer particles according to any one of claims 1 to 6, comprising: a step of polymerizing a monomer component containing alkyl(meth)acrylate with a crosslinkable monomer to form core particles (A) composed of a polyalkyl(meth)acrylate rubber; a step of copolymerizing a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound in the presence of the core particle (A) to form a shell layer (B), thereby obtaining the core-shell graft copolymer particle.

8. 8. The method according to claim 7, wherein in the step of forming the core particle (A), a core particle (A) comprising an inner layer, one or more intermediate layers, and an outer layer is formed by multistage polymerization of a monomer component containing an alkyl(meth)acrylate and a crosslinkable monomer.

9. 100 parts by weight of a thermoplastic resin containing a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit; and A resin composition comprising 10 to 100 parts by weight of the core-shell graft copolymer particles according to any one of claims 1 to 6.

10. A molded article obtained by molding the resin composition according to claim 9.

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