Core / shell type graft copolymer particles, production method therefor, and resin composition

Abstract

Core / shell type graft copolymer particles comprising core particles (A) and a shell layer (B) covering each core particle (A). The core particles (A) each comprise a polyorganosiloxane rubber particle (a1) and a poly(alkyl (meth)acrylate) rubber layer (a2) located on the outer side of the rubber particle (a1). The core particles (A) account for 50-65 wt% of the core / shell type graft copolymer particles and have a volume-average particle diameter of 85-150 nm. The shell layer (B) includes a layer (b1) formed from a copolymer including an aromatic vinyl compound unit and a vinyl cyanide compound unit.

Description

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

[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.

[0002] ABS resin (acrylonitrile-butadiene-styrene) has excellent rigidity, impact resistance, heat deformation resistance, etc., and is therefore widely used in a variety of miscellaneous goods, interior and exterior materials for automobiles, housing parts for home appliances such as rice cookers, microwave ovens, and vacuum cleaners, as well as 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 is changed from butadiene rubber, which is unstable against light and heat, to acrylic rubber, which has relatively high stability. However, ASA resin has the problem of being less able to exhibit impact resistance than ABS resin.

[0004] One known method for improving the impact resistance of thermoplastic resins is to use a graft copolymer obtained by graft polymerizing a vinyl monomer onto a composite rubber obtained by compounding a polyorganosiloxane rubber and an acrylic rubber. Patent Document 1 describes blending such a composite rubber-containing graft copolymer with a thermoplastic resin such as an acrylonitrile-styrene resin.

[0005] Japanese Patent Application Laid-Open No. 2015-227399

[0006] When the above-mentioned composite rubber-containing graft copolymer is blended with a thermoplastic resin, the impact resistance of the resin can be improved, but the color development property tends to be reduced, and it has been difficult to satisfy both impact resistance and color development property.

[0007] 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 improve impact resistance while exhibiting good color development, a method for producing the same, and a resin composition containing the particles.

[0008] The present inventors have found that the above problems can be solved by employing a specific structure in a composite rubber-containing graft copolymer, and have arrived at the present invention.

[0009] That is, the present invention relates to core-shell graft copolymer particles comprising core particles (A) and a shell layer (B) covering the core particles (A), wherein the core particles (A) comprise polyorganosiloxane rubber particles (a1) and a polyalkyl(meth)acrylate rubber layer (a2) located on the outside of the rubber particles (a1), the proportion of the core particles (A) in the core-shell graft copolymer particles is 50 to 65 wt %, the volume average particle diameter of the core particles (A) is 85 to 150 nm, and the shell layer (B) comprises a layer (b1) formed from a copolymer containing aromatic vinyl compound units and vinyl cyanide compound units. The present invention also relates to a method for producing the core-shell graft copolymer particles, comprising the steps of: polymerizing a polyorganosiloxane rubber-forming component to form polyorganosiloxane rubber particles (a1); polymerizing an alkyl (meth)acrylate and a crosslinkable monomer in the presence of the polyorganosiloxane rubber particles (a1) to form a polyalkyl (meth)acrylate rubber layer (a2) to obtain core particles (A); and copolymerizing a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound in the presence of the core particles (A) to form a layer (b1) to obtain the core-shell graft copolymer particles. The present invention also relates to a resin composition comprising 100 parts by weight of a thermoplastic resin and 10 to 100 parts by weight of the core-shell graft copolymer particles, or a molded article obtained by molding the resin composition.

[0010] According to the present invention, there are provided core-shell graft copolymer particles that can be blended with a thermoplastic resin to improve impact resistance and exhibit good color development, a method for producing the same, and a resin composition containing the particles. According to a preferred aspect of the present invention, a molded article molded from a thermoplastic resin composition containing the core-shell graft copolymer particles has extremely good color development and can have a good appearance even without painting.

[0011] Embodiments of the present invention are described in detail below. <Core-shell 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 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 constituting 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).

[0012] <Core particle (A)> The core particle (A) comprises a polyorganosiloxane rubber particle (a1) and a polyalkyl (meth)acrylate rubber layer (a2) located outside the rubber particle (a1). Here, "rubber" refers to a polymer having a crosslinked structure (hereinafter also referred to as a crosslinked polymer). Since the core particle (A) is formed from a crosslinked polymer, by blending the core-shell type graft copolymer particles into a matrix resin, it is possible to impart impact resistance to the matrix resin.

[0013] <Polyorganosiloxane rubber particles (a1)> The polyorganosiloxane rubber particles (a1) are mainly composed of polyorganosiloxane rubber (hereinafter also referred to as silicone rubber) having a structure linked by siloxane bonds. The silicone rubber can be obtained by condensation polymerization of organosiloxane and any silane compound.

[0014] The organosiloxane refers to a monomer component that forms the main skeleton of the silicone rubber. Specific examples include cyclic organosiloxanes, linear organosiloxane oligomers, and bifunctional silane compounds. Among these, cyclic organosiloxanes are preferred from the standpoints of applicability to emulsion polymerization systems and economic efficiency.

[0015] The cyclic organosiloxane may be, for example, a 6- to 12-membered ring, and specific examples thereof include hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, trimethyltriphenylcyclotrisiloxane, tetramethyltetraphenylcyclotetrasiloxane, and octaphenylcyclotetrasiloxane. These may be used alone or in combination of two or more. Of these, octamethylcyclotetrasiloxane is preferred.

[0016] Examples of the optional silane compound include a crosslinking agent and a graft crosslinking agent. The crosslinking agent is a component that copolymerizes with the organosiloxane to introduce a crosslinked structure into the silicone rubber, thereby exhibiting rubber elasticity, and is used as a crosslinking agent for the silicone rubber. Specific examples include tetrafunctional or trifunctional alkoxysilane compounds, such as tetramethoxysilane, tetraethoxysilane, methyltriethoxysilane, methyltrimethoxysilane, ethyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 4-aminobutyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, heptadecafluorodecyltrimethoxysilane, trifluoropropyltrimethoxysilane, and octadecyltrimethoxysilane. These may be used alone or in combination of two or more. Among these, tetraethoxysilane is preferred due to its high crosslinking efficiency.

[0017] The grafting agent is a component that introduces polymerizable unsaturated bonds or mercapto groups into the side chains and / or ends of the silicone rubber by copolymerizing with the organosiloxane and / or the crosslinking agent. The polymerizable unsaturated bonds or mercapto groups can serve as active grafting sites for alkyl (meth)acrylates. Furthermore, the polymerizable unsaturated bonds or mercapto groups can also serve as crosslinking sites when a radical reaction is carried out using a radical polymerization initiator. Even when crosslinking is carried out by a radical reaction, some remain as active grafting sites, making grafting possible.

[0018] Specific examples of the grafting agent include reactive silane compounds having a polymerizable unsaturated bond or a mercapto group, and organosiloxanes having a polymerizable unsaturated bond or a mercapto group.

[0019] Examples of the reactive silane compound having a polymerizable unsaturated bond include β-methacryloyloxyethyldimethoxymethylsilane, γ-methacryloyloxypropyldimethoxymethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyldimethylmethoxysilane, γ-methacryloyloxypropyltriethoxysilane, γ-methacryloyloxypropyldiethoxymethylsilane, γ-methacryloyloxypropyltripropoxysilane, γ-methacryloyloxypropyldipropoxymethylsilane, p-vinylphenyldimethoxymethylsilane, p-vinylphenyltrimethoxysilane, p-vinylphenyltriethoxysilane, p-vinylphenyldiethoxymethylsilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allylmethyldimethoxysilane, allylmethyldiethoxysilane, allyltrimethoxysilane, and allyltriethoxysilane.

[0020] Examples of the reactive silane compound having a mercapto group include mercaptopropyltrimethoxysilane and mercaptopropyldimethoxymethylsilane.

[0021] The proportions of the organosiloxane, crosslinking agent, and graft crossing agent used may be, for example, 70 to 99.9 wt%, preferably 85 to 99.5 wt%, of the organosiloxane, 0 to 10 wt%, preferably 0 to 5 wt%, of the crosslinking agent, and 0 to 10 wt%, preferably 0.3 to 5 wt%, of the total amount of the polyorganosiloxane rubber-forming components. It is preferable to use 0.1 wt% or more of either the crosslinking agent or the graft crossing agent.

[0022] The method for producing the polyorganosiloxane rubber particles (a1) is not particularly limited, but a preferred method is to emulsify and disperse a mixture of organosiloxane and any crosslinking agent and grafting agent in water by mechanical shearing in the presence of an emulsifier, and then polymerize under specific conditions to obtain a latex of the polyorganosiloxane rubber particles (a1). Details will be described later.

[0023] The polyorganosiloxane rubber particles (a1) may be composed of only a polyorganosiloxane rubber component, or may contain a vinyl polymer in addition to the polyorganosiloxane rubber component.

[0024] In particular, polyorganosiloxane rubber particles (a1) containing the vinyl polymer as seed particles inside are preferred because the emulsion stability during production is good and the particle size can be controlled to be small. Such polyorganosiloxane rubber particles (a1) can be obtained by first obtaining seed particles made of a vinyl polymer by emulsion polymerization or the like, and then polymerizing a polyorganosiloxane rubber-forming component in the presence of the seed particles.

[0025] The monomer used in producing the vinyl polymer is not particularly limited, and examples thereof include aromatic vinyl monomers such as styrene, α-methylstyrene, paramethylstyrene, and parabutylstyrene, vinyl cyanide monomers such as acrylonitrile and methacrylonitrile, halogenated vinyl monomers such as vinyl chloride, vinylidene chloride, and vinylidene fluoride, (meth)acrylic acid ester monomers such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, glycidyl acrylate, hydroxyethyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, lauryl methacrylate, glycidyl methacrylate, and hydroxyethyl methacrylate, carboxyl group-containing vinyl monomers such as itaconic acid, (meth)acrylic acid, fumaric acid, and maleic acid, and conjugated diene monomers such as butadiene, chloroprene, and isoprene. These may be used alone or in combination of two or more. Among these, those containing 20 to 100% by weight, or even 30 to 100% by weight, of at least one of butyl acrylate, 2-ethylhexyl acrylate, butyl methacrylate, butadiene, and acrylonitrile are preferred because the emulsion has high stability during production and the particle size of the resulting polyorganosiloxane rubber particles (a1) tends to be small.

[0026] The vinyl polymer constituting the seed particles may be a polymer containing a crosslinked structure, but is preferably a non-crosslinked polymer, since this results in a smaller particle size of the polyorganosiloxane rubber particles (a1).

[0027] When the polyorganosiloxane rubber particles (a1) contain the vinyl polymer in addition to the polyorganosiloxane rubber component, the proportion of the polyorganosiloxane rubber component in the total of both components is preferably 55% by weight or more and 99.9% by weight or less, more preferably 65% ​​by weight or more and 99.4% by weight or less, and even more preferably 88% by weight or more and 99% by weight or less. The proportion of the vinyl polymer is preferably 0.1% by weight or more and 45% by weight or less, more preferably 0.6% by weight or more and 35% by weight or less, and even more preferably 1% by weight or more and 12% by weight or less. Within this range, the particle size of the polyorganosiloxane rubber particles (a1) can be made smaller while exhibiting the properties of silicone rubber.

[0028] The proportion of the polyorganosiloxane rubber particles (a1) in the core particles (A) can be appropriately set, but from the viewpoint of impact resistance, color development, and weather resistance, it is preferably 5% by weight or more and 40% by weight or less, more preferably 8% by weight or more and 30% by weight or less, and even more preferably 10% by weight or more and 25% by weight or less. The lower limit may be 15% by weight or more, or may be 20% by weight or more.

[0029] The volume average particle diameter of the polyorganosiloxane rubber particles (a1) may be appropriately set in consideration of the ratio of the particles (a1) in the core particles (A) and the volume average particle diameter of the core particles (A) described later. Specifically, it may be about 40 nm or more and 120 nm or less, preferably 40 nm or more and 110 nm or less, more preferably 50 nm or more and 100 nm or less.

[0030] <Polyalkyl(meth)acrylate Rubber Layer (a2)> The polyalkyl(meth)acrylate rubber layer (a2) is located outside the polyorganosiloxane rubber particle (a1) and constitutes the core particle (A) together with the polyorganosiloxane rubber particle (a1).

[0031] The polyalkyl(meth)acrylate rubber layer (a2) is preferably grafted to the polyorganosiloxane rubber particles (a1). The grafting can be achieved by using the above-mentioned grafting agent.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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. Butyl acrylate is particularly preferred as the alkyl acrylate.

[0036] From the viewpoints of a 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.

[0037] 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.

[0038] The crosslinkable monomer used to form the polyalkyl (meth)acrylate rubber is a compound having two or more unsaturated bonds copolymerizable with the alkyl (meth)acrylate in one molecule. 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)acrylic groups, such as (poly)ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butanediol di(meth)acrylate, triethylene glycol di(meth)acrylate, and tetraethylene glycol di(meth)acrylate; diallyl phthalate, triallyl cyanurate, triallyl isocyanurate, and divinylbenzene. Only one type of crosslinkable monomer may be used, or two or more types may be used in combination. Of these, allyl methacrylate, triallyl isocyanurate, butanediol di(meth)acrylate, and divinylbenzene are preferred, and allyl methacrylate is particularly preferred.

[0039] The proportion of the polyalkyl(meth)acrylate rubber layer (a2) in the core particle (A) can be appropriately set, but from the viewpoints of impact resistance, color development, and weather resistance, it is preferably 60% by weight or more and 95% by weight or less, more preferably 70% by weight or more and 92% by weight or less, and even more preferably 75% by weight or more and 90% by weight or less. The upper limit may be 85% by weight or less, or may be 80% by weight or less.

[0040] From the viewpoint of the balance between impact resistance and color development, the proportion of core particles (A) in the core-shell graft copolymer particles is set to the range of 50% by weight to 65% by weight. If the proportion of core particles (A) is less than 50% by weight, impact resistance becomes insufficient. On the other hand, if the proportion of core particles (A) exceeds 65% by weight, the compatibility between the core-shell graft copolymer particles and the matrix resin decreases, which may result in a decrease in impact resistance or color development.

[0041] In order to achieve particularly excellent impact resistance, the proportion of the core particles (A) is preferably 53% by weight or more, more preferably 55% by weight or more, even more preferably 58% by weight or more, and particularly preferably 60% by weight or more. The upper limit of the proportion may be 64% by weight or less.

[0042] From the viewpoint of the balance between impact resistance and color development and productivity, the volume average particle diameter of the core particles (A) is set to 85 nm or more and 150 nm or less. Core particles (A) with a volume average particle diameter of less than 85 nm tend to produce unstable emulsions during production, making production difficult. Core particles (A) with a volume average particle diameter of more than 150 nm tend to produce insufficient color development.

[0043] From the viewpoint of productivity, the lower limit of the volume average particle diameter of the core particles (A) is preferably 90 nm or more, more preferably 95 nm or more, and the upper limit of the volume average particle diameter of the core particles (A) is preferably 140 nm or less, more preferably 130 nm or less, even more preferably 120 nm or less, even more preferably 115 nm or less, and particularly preferably 110 nm or less, in order to achieve better color development.

[0044] The volume average particle diameter of the core particles (A) and the polyorganosiloxane rubber particles (a1) is a value measured by using a particle diameter measuring device in the state of the latex of the polymer particles, as shown in the Examples. The particle diameter of the core particles (A) and the polyorganosiloxane rubber particles (a1) can be controlled by the type and amount of emulsifier, polymerization initiator, reducing agent, etc. used during production, polymerization temperature, polymerization time, etc.

[0045] <Shell Layer (B)> The shell layer (B) is a polymer layer that coats the core particle (A) and is located on the surface of the graft copolymer particle. At least a portion of the shell layer (B) is preferably graft-bonded to the core particle (A), but a non-graft-bonded shell layer (B) may also be included. The shell layer (B) improves the compatibility between the graft copolymer particle and the matrix resin, allowing the graft copolymer particle to be dispersed in the resin composition as primary particles.

[0046] The shell layer (B) includes 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 matrix resin. The copolymer may further include a (meth)acrylic acid ester unit.

[0047] 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.

[0048] The vinyl cyanide compound is not particularly limited, but examples thereof include acrylonitrile, methacrylonitrile, etc. Among these, acrylonitrile is preferred.

[0049] 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.

[0050] From the viewpoint of compatibility with the matrix resin, 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.

[0051] 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. The inclusion of such an outer layer (b2) can further improve the impact resistance of the thermoplastic resin.

[0052] The aromatic vinyl compound usable in the outer layer (b2) is not particularly limited, and examples of the aromatic vinyl compound include those described above for the layer (b1). The polymer constituting the outer layer (b2) may be composed only of aromatic vinyl compound units, or may further contain vinyl cyanide compound units and / or (meth)acrylic acid ester units.

[0053] 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 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 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 95% by weight or more.

[0054] The weight ratio of layer (b1) to outer layer (b2) is not particularly limited, but may be, for example, about 50:50 to 99:1. From the viewpoint of improving compatibility with the matrix resin and enhancing impact resistance, the ratio is preferably 60:40 to 98:2, more preferably 70:30 to 97:3, and particularly preferably 80:20 to 95:5.

[0055] 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).

[0056] 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.

[0057] From the viewpoint of the balance between impact resistance and color development, the proportion of the shell layer (B) in the core-shell graft copolymer particles is preferably 35% by weight or more and 50% by weight or less, more preferably 47% by weight or less, even more preferably 45% by weight or less, even more preferably 42% by weight or less, and particularly preferably 40% by weight or less. The lower limit of this proportion may be 36% by weight or more.

[0058] <Method for Producing Core-Shell Graft Copolymer Particles> The 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. Among these, emulsion polymerization is preferred.

[0059] 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.

[0060] 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 alkylphosphates; phosphate ester salts such as sodium polyoxyethylene lauryl ether phosphate; sodium salts of naphthalenesulfonate-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, and the like.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] These emulsifiers may be used alone or in combination of two or more. The amount of the emulsifier used may be set appropriately, and by adjusting the amount used, the average particle size of the polymer particles can be controlled.

[0065] 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.

[0066] Alternatively, a redox initiator can be used in which a peroxide, such as an organic peroxide such as t-butylperoxyisopropyl carbonate, paramenthane hydroperoxide, cumene hydroperoxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, or t-hexyl peroxide; or an inorganic peroxide such as hydrogen peroxide, potassium persulfate, or ammonium persulfate, is used in combination with at least one reducing agent selected from the group consisting of sodium formaldehyde sulfoxylate, glucose; transition metal salts such as iron (II) sulfate; chelating agents such as disodium ethylenediaminetetraacetate; and pyrophosphates such as sodium pyrophosphate.

[0067] 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 amounts 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, and this is also within known ranges.

[0068] 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.

[0069] 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.

[0070] More specifically, the core-shell graft copolymer particles according to the present disclosure can be produced by sequentially carrying out the following steps (I) to (V), although steps (I) and (V) are optional and may not be performed.

[0071] Step (I): In the presence of water, an emulsifier, an initiator, etc., a monomer component for forming seed particles is polymerized to form seed particles composed of a vinyl polymer.

[0072] Step (II): The polyorganosiloxane rubber-forming component is polymerized to form polyorganosiloxane rubber particles (a1). The polymerization of the polyorganosiloxane rubber-forming component can be carried out by mixing the polyorganosiloxane rubber-forming component, an emulsifier, and water to form an emulsion, and then heating under acidic or basic conditions. This allows for the production of a latex containing polyorganosiloxane rubber particles (a1). In particular, polymerization under acidic conditions can reduce the particle size of the resulting polyorganosiloxane rubber particles (a1).

[0073] When step (I) is carried out, add polyorganosiloxane rubber-forming components to the system containing seed particles obtained in step (I), and polymerize the polyorganosiloxane rubber-forming components in the presence of seed particles, thereby forming polyorganosiloxane rubber particles (a1) containing seed particles inside.In this case, it is preferable to add the emulsion of polyorganosiloxane rubber-forming components to the system containing seed particles obtained in step (I), and then heat under acidic or basic conditions to carry out polymerization.The addition of the emulsion can be carried out all at once or in portions.

[0074] The emulsion of the polyorganosiloxane rubber-forming component can be prepared by mixing a mixture of the polyorganosiloxane rubber-forming component, an emulsifier, and water using a high-speed agitator such as a homomixer, or a disperser such as a high-pressure homogenizer or an ultrasonic disperser.

[0075] When polymerization is carried out under acidic conditions, the pH of the system may be adjusted to, for example, 1.0 to 3, preferably 1.2 to 2.5, by adding an inorganic acid such as sulfuric acid or hydrochloric acid, or an organic acid such as alkylsulfonic acid, alkylbenzenesulfonic acid, or trifluoroacetic acid to the system. The emulsifier used under acidic conditions is preferably an anionic surfactant or a nonionic surfactant.

[0076] When polymerization is carried out under basic conditions, an inorganic base such as sodium hydroxide, potassium hydroxide, or ammonia, or an organic base such as pyridine or benzylmethyldodecylammonium hydroxide may be added to the system to adjust the pH of the system to, for example, 11 to 13.5, preferably 11.5 to 13. The emulsifier used under basic conditions is preferably a cationic surfactant.

[0077] The heating temperature during polymerization may be, for example, about 60 to 120 ° C., and from the viewpoint of achieving a moderate polymerization rate, about 70 to 100 ° C. is preferable. From the viewpoint of stability, it is preferable that the polyorganosiloxane rubber particle (a1)-containing latex obtained by polymerization is neutralized by adding a basic aqueous solution or an acidic aqueous solution. For details of step (II), see, for example, JP-A-11-293115.

[0078] Step (III): In step (II), the system containing the polyorganosiloxane rubber particles (a1) is added with a monomer component containing alkyl (meth) acrylate, a crosslinkable monomer, an initiator, etc., and in the presence of the polyorganosiloxane rubber particles (a1), the alkyl (meth) acrylate and the crosslinkable monomer are polymerized to form a polyalkyl (meth) acrylate rubber layer (a2).Thereby, the core particle (A) containing the polyorganosiloxane rubber particles (a1) and the polyalkyl (meth) acrylate rubber layer (a2) can be obtained.

[0079] Step (IV): To the system containing the core particles (A) obtained in step (III), a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound, and an initiator, etc., are added, and the monomer component is copolymerized in the presence of the core particles (A) to form a layer (b1) composed of a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit. 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).

[0080] Step (V): To the system containing the core-shell graft copolymer particles obtained in step (IV), 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, thereby obtaining core-shell graft copolymer particles containing core particles (A) and a layer (b1) and an outer layer (b2) as the shell layer (B).

[0081] After the core-shell graft copolymer particles are formed, the latex is coagulated by adding one or more coagulants selected from the group consisting of acids and salts, and the coagulated particles are then heat-treated at a temperature of, for example, 40°C or higher and 110°C or lower, washed and dehydrated, dried, and passed through a sieve of a predetermined size, whereby the core-shell graft copolymer particles can be separated.

[0082] <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 of the thermoplastic resin is improved and the resin composition exhibits good color development properties.

[0083] The thermoplastic resin is not particularly limited, but preferably contains a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit (hereinafter also referred to as a copolymer) and / or an acrylic resin.

[0084] 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. Of these, styrene and α-methylstyrene are preferred, and styrene is particularly preferred.

[0085] 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.

[0086] 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.

[0087] The copolymerizable other vinyl compound is 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 may be used alone or in combination of two or more.

[0088] 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.

[0089] 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.

[0090] The acrylic resin is not particularly limited, and examples thereof include poly(meth)acrylic acid esters such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymers, methyl methacrylate-(meth)acrylic acid ester copolymers, methyl methacrylate-acrylic acid ester-(meth)acrylic acid copolymers, methyl methacrylate-styrene copolymers (such as MS resins), and polymers having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymers, methyl methacrylate-norbornyl (meth)acrylate copolymers).

[0091] As the thermoplastic resin, the copolymer and the acrylic resin may be used alone or in combination. When the copolymer and the acrylic resin are used in combination, the ratio of their use is not particularly limited, but for example, the weight ratio of the copolymer to the acrylic resin is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30.

[0092] The resin composition may further contain a thermoplastic resin other than the copolymer and the acrylic resin. Such a thermoplastic resin is not particularly limited, but examples thereof include vinyl chloride resins, polycarbonate resins, amide resins, and polyester resins. These may be used alone or in combination of two or more.

[0093] From the viewpoints of impact resistance and color development, the content of the core-shell graft copolymer particles in the resin composition is preferably 10 parts by weight or more and 100 parts by weight or less, more preferably 15 parts by weight or more and 80 parts by weight or less, even more preferably 20 parts by weight or more and 70 parts by weight or less, and particularly preferably 25 parts by weight or more and 60 parts by weight or less, relative to 100 parts by weight of the total amount of the thermoplastic resin.

[0094] 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.

[0095] 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.

[0096] 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, a pellet, or a combination thereof. When the core-shell graft copolymer particles and the thermoplastic resin are in the form of a latex, for example, an alkaline earth metal salt such as calcium chloride, magnesium chloride, or magnesium sulfate, an alkali metal salt such as sodium chloride or sodium sulfate, or an inorganic or organic acid such as hydrochloric acid, sulfuric acid, phosphoric acid, or acetic acid may be added to the latex to coagulate the latex into a slurry, which may then be dehydrated and dried. A spray drying method can also be used. In this case, some additives such as stabilizers can be added to the latex or slurry in the form of a dispersion.

[0097] 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.

[0098] The resin composition can be used in various applications such as electrical and electronic applications, construction applications, and vehicle applications. Specifically, the resin composition can be used in electrical and electronic applications such as personal computers, liquid crystal displays, projectors, PDAs, printers, copy machines, 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 light-transmitting 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.

[0099] The following items are preferred embodiments of the present disclosure, but the present invention is not limited to them. [Item 1] Core-shell graft copolymer particles comprising a core particle (A) and a shell layer (B) covering the core particle (A), wherein the core particle (A) comprises a polyorganosiloxane rubber particle (a1) and a polyalkyl(meth)acrylate rubber layer (a2) located on the outer side of the rubber particle (a1), the core particle (A) accounts for 50 to 65 wt % of the core-shell graft copolymer particles, the core particle (A) has a volume average particle diameter of 85 to 150 nm, and the shell layer (B) comprises a layer (b1) formed from a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit. [Item 2] The core-shell graft copolymer particle according to Item 1, wherein the shell layer (B) further includes an outer layer (b2) located outside the layer (b1), and the outer layer (b2) is formed from a polymer containing an aromatic vinyl compound unit. [Item 3] The core-shell graft copolymer particle according to Item 1 or 2, wherein the polyorganosiloxane rubber particles (a1) contain 55 to 99.9% by weight of a polyorganosiloxane rubber component and 0.1 to 45% by weight of a vinyl polymer. [Item 4] The core-shell graft copolymer particle according to any one of Items 1 to 3, wherein the polyorganosiloxane rubber particles (a1) account for 10 to 25% by weight of the core particles (A). [Item 5] The core-shell graft copolymer particle according to any one of Items 1 to 4, wherein the core particles (A) have a volume average particle diameter of 85 to 115 nm. [Item 6] The core-shell graft copolymer particles according to any one of Items 1 to 5, wherein the core particles (A) account for 55 to 65% by weight of the core-shell graft copolymer particles.[Item 7] A method for producing the core-shell graft copolymer particles according to any one of Items 1 to 6, comprising the steps of: polymerizing a polyorganosiloxane rubber-forming component to form polyorganosiloxane rubber particles (a1), polymerizing an alkyl(meth)acrylate and a crosslinkable monomer in the presence of the polyorganosiloxane rubber particles (a1) to form a polyalkyl(meth)acrylate rubber layer (a2) to obtain core particles (A), and copolymerizing a monomer component containing an aromatic vinyl compound and a vinyl cyanide compound in the presence of the core particles (A) to form a layer (b1) to obtain the core-shell graft copolymer particles. [Item 8] A resin composition comprising: 100 parts by weight of a thermoplastic resin; and 10 to 100 parts by weight of the core-shell graft copolymer particles according to any one of Items 1 to 6. [Item 9] The resin composition according to Item 8, wherein the thermoplastic resin comprises a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit, and / or an acrylic resin. [Item 10] A molded article obtained by molding the resin composition according to item 8 or 9.

[0100] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0101] (Method for measuring volume average particle diameter of polymer particles) The volume average particle diameter of 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.

[0102] (Polymerization Conversion Rate) A part of the obtained latex was collected and precisely weighed, and dried in a hot air dryer at 120°C for 1 hour, and the weight after drying was precisely weighed as the solid content. Next, the ratio of the weighing results before and after drying was calculated as the solid content ratio in the latex. Finally, using this solid content ratio, the polymerization conversion rate was calculated by the following formula 1. (Formula 1) Polymerization conversion rate = (Total weight of charged raw materials x Solid content ratio - Total weight of raw materials other than monomers) / Charged monomer weight x 100 (%)

[0103] Synthesis Example 1 Production of Polyorganosiloxane-Containing Latex (C-1) A five-neck flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a monomer addition port, and a thermometer was charged with 190 parts by weight of deionized water and 1.5 parts by weight of sodium dodecylbenzenesulfonate (SDBS), and the temperature was raised to 40°C while stirring in a nitrogen stream.

[0104] To this was added a mixture of 1 part by weight of butyl acrylate (BA) and 0.001 part by weight of cumene hydroperoxide (CHP). Next, 0.005 part by weight of a mixture of disodium ethylenediaminetetraacetate and ferrous sulfate in a 4:1 ratio dissolved in deionized water to a concentration of 0.1 wt % and 0.2 part by weight of sodium formaldehyde sulfoxylate at a concentration of 5 wt % were added. Stirring was continued for 60 minutes to obtain a seed particle latex with a polymerization conversion of 92.0%, a solids concentration of 1.3%, and a volume average particle size of 27 nm.

[0105] Separately, a mixture consisting of 70 parts by weight of deionized water, 0.5 parts by weight of SDBS, 94 parts by weight of octamethylcyclotetrasiloxane (D4), 2 parts by weight of γ-methacryloyloxypropyldimethoxymethylsilane (DSMA), and 3 parts by weight of tetraethoxysilane (TEOS) was stirred in a homomixer at 10,000 rpm for 5 minutes to prepare an emulsion of polyorganosiloxane-forming components.

[0106] Next, the seed particle latex was kept at 80 ° C., and 2 parts by weight of 10 wt% dodecylbenzenesulfonic acid (DBSA) was added to the system to adjust the pH of the system to 1.2. The emulsion of the polyorganosiloxane-forming components described above was added equally in 4 portions every hour. After the addition was completed, stirring was continued for 2 hours, then the mixture was cooled to 25 ° C. and left for 20 hours. Thereafter, the pH was adjusted to 7.2 with sodium hydroxide to terminate the polymerization, and a polyorganosiloxane-containing latex (C-1) having a polymerization conversion of 84.3%, a solids concentration of 22.4%, and a volume average particle diameter of 86 nm was obtained.

[0107] (Synthesis Examples 2 and 3) <Production of Polyorganosiloxane-Containing Latex (C-2) or (C-3)> Polyorganosiloxane-containing latex (C-2) or (C-3) was obtained in the same manner as in Synthesis Example 1, except that the amount of each component used was changed according to the description in Table 1.

[0108]

[0109] Example 1 (Rubber Particles) A ​​five-necked flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a monomer addition port, and a thermometer was charged with 35.7 parts by weight (8 parts by weight as solids) of the polyorganosiloxane-containing latex (C-1) obtained in Synthesis Example 1 and 106.6 parts by weight of deionized water and stirred, and then a mixture of 42 parts by weight of BA, 0.59 parts by weight of allyl methacrylate (ALMA) (1.4% by weight concentration relative to BA), and 0.39 parts by weight of CHP was added, and the mixture was heated to 60°C over 30 minutes while stirring in a nitrogen stream.

[0110] To the mixture, 0.0005 parts by weight of a mixture of disodium ethylenediaminetetraacetate and ferrous sulfate in a 4:1 ratio dissolved in deionized water to a concentration of 0.1% by weight, and 0.166 parts by weight of 5% by weight sodium formaldehyde sulfoxylate were added. The mixture was then kept at an internal temperature of 70°C for 1 hour, thereby obtaining a composite rubber latex with a polymerization conversion of 99.4%, a solids concentration of 26.9%, and a volume average particle size of 128 nm.

[0111] (Shell Layer) 31.3 parts by weight of deionized water and 0.25 parts by weight of 5% by weight sodium formaldehyde sulfoxylate were charged thereto, and a mixture of 37.5 parts by weight of styrene (ST), 12.5 parts by weight of acrylonitrile (AN), and 0.2 parts by weight of t-butyl hydroperoxide (t-BH) was added thereto over 100 minutes. After the addition, t-BH and 5% by weight sodium formaldehyde sulfoxylate were appropriately added to form a shell layer (B) consisting of a layer (b1), and a graft copolymer latex having a polymerization conversion rate of 100% and a solids concentration of 35.8% was obtained.

[0112] Example 2 (Rubber Particles) First, in the same manner as in Example 1, a composite rubber latex having a polymerization conversion rate of 100%, a solid content concentration of 27.1%, and a volume average particle diameter of 133 nm was obtained.

[0113] (Shell Layer) 31.3 parts by weight of deionized water and 0.25 parts by weight of 5 wt% sodium formaldehyde sulfoxylate were charged to the mixture, and a mixture of 35 parts by weight of ST, 10 parts by weight of AN, and 0.067 parts by weight of t-BH was added over 90 minutes. After the addition, 0.067 parts by weight of t-BH was added, followed by the addition of a mixture of 5 parts by weight of ST and 0.067 parts by weight of t-BH over 10 minutes. After the addition, t-BH and 5 wt% sodium formaldehyde sulfoxylate were appropriately added to form a shell layer (B) consisting of a layer (b1) and an outer layer (b2), yielding a graft copolymer latex with a polymerization conversion of 100% and a solids concentration of 35.4%.

[0114] Comparative Example 1 (Rubber Particles) A ​​five-neck flask equipped with a stirrer, a reflux condenser, a nitrogen inlet, a monomer addition inlet, and a thermometer was charged with 174.6 parts by weight of deionized water, 0.21 parts by weight of a potassium hydroxide saponification product of 15% by weight beef tallow fatty acid (LUNAC TH manufactured by Kao Corporation), and 0.05 parts by weight of 2% by weight sodium carbonate, and the mixture was heated to 45°C while stirring in a nitrogen stream.

[0115] To this was added a mixture of 5 parts by weight of BA, 0.006 parts by weight of ALMA (0.125% by weight relative to BA), and 0.0089 parts by weight of t-BH, and then 0.00144 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 0.08 parts by weight of 5% by weight sodium formaldehyde sulfoxylate were added.The mixture was then held for 30 minutes.

[0116] To this mixture, 0.12 parts by weight of 5 wt% sodium formaldehyde sulfoxylate was added, and a mixture of 40 parts by weight of BA, 0.05 parts by weight of ALMA (0.125 wt% concentration relative to BA), and 0.0129 parts by weight of t-BH was added over 120 minutes, followed by a 20-minute hold. Subsequently, a mixture of 5 parts by weight of BA, 0.45 parts by weight of ALMA (9 wt% concentration relative to BA), and 0.0089 parts by weight of t-BH was added over 15 minutes. After the addition, 0.012 parts by weight of t-BH was added and the mixture was held for 30 minutes, yielding a rubber latex with a polymerization conversion of 99%, a solids concentration of 20.8%, and a volume average particle size of 122 nm.

[0117] (Shell Layer) 0.00144 parts by weight of a mixed solution prepared by dissolving disodium ethylenediaminetetraacetate and ferrous sulfate in a 5:3 ratio in deionized water to a concentration of 0.5% by weight was added thereto, and the mixture was heated to 70°C, followed by the addition of a mixture of 40 parts by weight of ST, 10 parts by weight of AN, and 0.2 parts by weight of t-BH over 90 minutes. After the addition, t-BH and 5% by weight of sodium formaldehyde sulfoxylate were appropriately added to form a shell layer, yielding a graft copolymer latex with a polymerization conversion of 100% and a solids concentration of 33.1%.

[0118] <Granulation of Graft Copolymer> Each graft copolymer latex obtained above was cooled to 10°C, and an aqueous calcium chloride solution was added to the graft copolymers of Examples 1 and 2, and an aqueous hydrochloric acid solution was added to the graft copolymer of Comparative Example 1 to form a slurry. Thereafter, the slurry was dehydrated in a centrifugal dehydrator, washed with deionized water, and dried at 50°C for 2 days to obtain a powder of each graft copolymer.

[0119] (Examples 3 to 6) In Examples 3 and 4, a graft copolymer powder was obtained in the same manner as in Example 1, except that the amount of each component used was changed according to the descriptions in Tables 2 to 4. In Example 5, a graft copolymer powder was obtained in the same manner as in Example 1, except that the polyorganosiloxane-containing latex (C-2) obtained in Synthesis Example 2 was used according to the descriptions in Tables 2 to 4. In Example 6, a graft copolymer powder was obtained in the same manner as in Example 2, except that the polyorganosiloxane-containing latex (C-2) obtained in Synthesis Example 2 was used according to the descriptions in Tables 2 to 4, and the amount of each component used was changed.

[0120] (Comparative Examples 2 to 3) In Comparative Example 2, a graft copolymer powder was obtained in the same manner as in Example 1, except that the amount of each component used was changed according to the descriptions in Tables 2 to 4. In Comparative Example 3, a graft copolymer powder was obtained in the same manner as in Example 1, except that the polyorganosiloxane-containing latex (C-3) obtained in Synthesis Example 3 was used according to the descriptions in Tables 2 to 4.

[0121] (Method for measuring Izod impact strength) The obtained graft copolymer powder, AS resin (PN-117, manufactured by Chimei Co., Ltd.), PMMA resin (CM-207, manufactured by Chimei Co., Ltd.), and carbon black masterbatch (AS resin blended with 40% carbon black) were added in the blending parts (parts by weight) shown in each table, and kneaded in a twin-screw extruder (TEX44SS manufactured by The Japan Steel Works, Ltd.) to obtain extruded pellets. The pellets were injected into an injection molding machine (160MSP manufactured by Mitsubishi Heavy Industries, Ltd.) to obtain 3 mm 1 / 8 inch bars. Notched Izod impact strength was measured at 23°C in accordance with JIS K-7110. The results are shown in Tables 2, 3, and 4.

[0122] (Method for measuring L value) A 2 mm thick color plate was obtained under the same conditions as those for preparing the Izod impact strength test piece. The reflection L value of the obtained color plate was measured using a color difference meter (model: SE-2000) manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K8722. Note that a lower L value indicates a darker black color and better color development. The results are shown in Tables 2, 3, and 4.

[0123]

[0124] From Table 2, it can be seen that Examples 1-1 to 6-1 (particularly Examples 3-1, 4-1, and 6-1) have larger Izod impact strength values ​​and are excellent in impact resistance compared to Comparative Examples 1-1 and 2-1. Furthermore, it can be seen that Examples 1-1 to 6-1 (particularly Examples 5-1 and 6-1) have smaller L values ​​and are excellent in color development compared to Comparative Example 3-1. In addition, Examples 1-1 to 6-1 contain polyorganosiloxane rubber particles in the core particles, and the core particles (A) account for 50 to 65% by weight of the graft copolymer, and the core particles (A) have a volume average particle diameter of 85 to 150 nm. Core-shell type graft copolymer particles were used.

[0125] On the other hand, Comparative Example 1-1 did not contain polyorganosiloxane rubber particles in the core particles. Comparative Example 2-1 contained polyorganosiloxane rubber particles in the core particles, but the proportion of the core particles was less than 50% by weight of the graft copolymer. Comparative Example 3-1 contained polyorganosiloxane rubber particles in the core particles, and the core particles were in the range of 50 to 65% by weight of the graft copolymer, but the volume average particle diameter of the core particles exceeded 150 nm.

[0126]

[0127]

[0128] In the examples and comparative examples shown in Tables 3 and 4, the type or amount of thermoplastic resin (matrix resin) used in the evaluation differs, but the evaluation was performed on the same core-shell graft copolymer particles as in the examples and comparative examples shown in Table 2. In both Tables 3 and 4, it can be seen that the examples have large Izod impact strength values, small L values, and excellent color development properties.

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) includes a polyorganosiloxane rubber particle (a1) and a polyalkyl(meth)acrylate rubber layer (a2) located outside the rubber particle (a1), the proportion of the core particles (A) in the core-shell type graft copolymer particles is 50 to 65% by weight, the core particles (A) have a volume average particle diameter of 85 to 150 nm; The polyorganosiloxane rubber particles (a1) contain a vinyl polymer as a seed particle therein, The polyorganosiloxane rubber particles (a1) contain 88 to 99% by weight of a polyorganosiloxane rubber component and 1 to 12% by weight of the vinyl polymer, The core-shell type graft copolymer particles, wherein the shell layer (B) includes a layer (b1) formed from a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit.

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

3. The core-shell graft copolymer particles according to claim 1 or 2, wherein the proportion of the polyorganosiloxane rubber particles (a1) in the core particles (A) is 10 to 25% by weight.

4. 3. The core-shell graft copolymer particles according to claim 1, wherein the core particles (A) have a volume average particle diameter of 85 to 115 nm.

5. 3. The core-shell graft copolymer particles according to claim 1, wherein the core particles (A) account for 55 to 65% by weight of the core-shell graft copolymer particles.

6. A method for producing the core-shell graft copolymer particles according to claim 1 or 2, comprising: a step of polymerizing a polyorganosiloxane rubber-forming component in the presence of seed particles made of a vinyl polymer to form polyorganosiloxane rubber particles (a1); a step of polymerizing an alkyl(meth)acrylate and a crosslinkable monomer in the presence of the polyorganosiloxane rubber particles (a1) to form a polyalkyl(meth)acrylate rubber layer (a2) to obtain core particles (A); 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 layer (b1), thereby obtaining the core-shell graft copolymer particle.

7. 100 parts by weight of a thermoplastic resin, and A resin composition comprising 10 to 100 parts by weight of the core-shell type graft copolymer particles according to claim 1 or 2.

8. The resin composition according to claim 7 , wherein the thermoplastic resin comprises a copolymer containing an aromatic vinyl compound unit and a vinyl cyanide compound unit, and / or an acrylic resin.

9. A molded article obtained by molding the resin composition according to claim 7.