Thermoplastic resin composition

Abstract

To provide a thermoplastic resin composition which can achieve both impact resistance and color development property in a good balance.SOLUTION: A thermoplastic resin composition comprises: a graft copolymer resin (A) obtained by graft polymerization of a vinyl-based monomer containing a vinyl cyanide-based monomer and an aromatic vinyl-based monomer to a rubbery polymer, where a predetermined requirement with regard to a free resin contained in the graft copolymer resin (A) is satisfied; a graft copolymer resin (B) obtained by graft polymerization of a vinyl-based monomer containing an aromatic vinyl-based monomer to a rubbery polymer containing a constitutional unit derived from (meth)acrylate, where an average particle size of the rubbery polymer in the graft copolymer resin (B) is 50 nm to 150 nm; and a copolymer (C) obtained by copolymerization of a vinyl monomer of an aromatic vinyl-based monomer and a vinyl cyanide-based monomer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic resin composition. [Background technology]

[0002] Rubber-reinforced thermoplastic resin compositions containing acrylic rubber graft copolymers and the like are generally excellent in moldability, impact resistance, weather resistance, chemical resistance, thermal stability, etc., and are therefore used in a wide range of fields, such as the fields of electrical and electronic equipment and office automation equipment. In recent years, their application to applications requiring high-quality appearance has been studied, and there is a demand for rubber-reinforced thermoplastic resin compositions with excellent color development properties.

[0003] For example, Patent Document 1 describes that a thermoplastic resin composition containing an acrylic rubber graft copolymer that meets certain requirements has excellent impact resistance, chemical resistance, surface appearance (gloss and color development) of molded products, and thermal stability during high-temperature molding. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-029545 Summary of the Invention [Problem to be solved by the invention]

[0005] However, as a result of investigations by the present inventors, it has become clear that there is room for improvement in the conventional rubber-reinforced thermoplastic resin compositions of Patent Document 1 and the like in terms of achieving both impact resistance and color development.

[0006] Therefore, an object of the present invention is to provide a rubber-reinforced thermoplastic resin composition that can achieve a good balance between impact resistance and color development. [Means for solving the problem]

[0007] As a result of extensive research conducted by the present inventors to solve the above problems, the present inventors have come up with the inventions described in the following [1] to [5]. [1] A graft copolymer resin (A) obtained by graft polymerizing a vinyl monomer including a vinyl cyanide monomer and an aromatic vinyl monomer onto a rubber-like polymer, wherein the free resin contained in the graft copolymer resin (A) contains 10 to 35 mass% of a structural unit derived from a (meth)acrylic acid alkyl ester, the alkyl group of which has 4 or more carbon atoms, based on the total amount of the free resin, and the graft copolymer resin (A) satisfies at least one of the following requirements (1) and (2): a graft copolymer resin (B) obtained by graft polymerizing a vinyl monomer including an aromatic vinyl monomer onto a rubbery polymer including a structural unit derived from a (meth)acrylic acid ester, wherein the average particle size of the rubbery polymer in the graft copolymer resin (B) is 50 nm to 150 nm; a copolymer (C) obtained by copolymerizing an aromatic vinyl monomer and a vinyl monomer including a vinyl cyanide monomer; A thermoplastic resin composition comprising: (1) The rubber-like polymer in the graft copolymer resin (A) contains structural units derived from a (meth)acrylic acid alkyl ester in which the alkyl group has 4 or more carbon atoms. (2) The vinyl monomer in the graft copolymer resin (A) further contains a (meth)acrylic acid alkyl ester having an alkyl group with 4 or more carbon atoms. [2] The thermoplastic resin composition according to [1], wherein the vinyl monomer in the graft copolymer resin (A) contains 10 to 30 mass% of a (meth)acrylic acid alkyl ester having an alkyl group with 4 or more carbon atoms, based on the total mass of the vinyl monomer. [3] The thermoplastic resin composition according to [1] or [2], wherein the rubbery polymer in the graft copolymer resin (A) contains 50 mass% or more of structural units derived from a (meth)acrylic acid alkyl ester, the alkyl group of which has 4 or more carbon atoms, based on the total amount of the rubbery polymer. [4] The thermoplastic resin composition according to any one of [1] to [3], wherein the gel content of the rubber-like polymer in the graft copolymer resin (A) is 75 to 90%. [5] The thermoplastic resin composition according to any one of claims 1 to 4, wherein the vinyl monomers in the copolymer (C) contain 28 mass% or more of a vinyl cyanide monomer based on the total amount of the vinyl monomers. [Effects of the Invention]

[0008] The rubber-reinforced thermoplastic resin composition of the present invention can achieve a good balance between impact resistance and color development. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, preferred embodiments of the present invention will be described. In this specification, the term "(meth)acrylic acid ester" refers to an acrylic acid ester or a methacrylic acid ester, and the same applies to similar expressions such as "(meth)acrylate."

[0010] The thermoplastic resin composition of the present embodiment contains a graft copolymer resin (A), a graft copolymer resin (B), and a copolymer (C). Each component will be described below.

[0011] [Graft copolymer resin (A)] The graft copolymer resin (A) is obtained by graft polymerizing a vinyl monomer onto a rubbery polymer. The graft copolymer resin (A) contains not only a graft copolymer in which a vinyl monomer is graft polymerized onto a rubbery polymer, but also a free resin in which vinyl monomers are polymerized together, and may contain unreacted vinyl monomers, etc. The free resin contained in the graft copolymer resin (A) may be one produced during the production of the rubbery polymer, or may be a free resin produced by the reaction of a monomer that was unreacted during the production of the rubbery polymer during graft polymerization.

[0012] Examples of the rubbery polymer include butadiene-based rubbery polymers such as polybutadiene, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer; ethylene-propylene-based rubbery polymers such as ethylene-propylene copolymer and ethylene-propylene-diene copolymer; (meth)acrylic rubbery polymers mainly composed of (meth)acrylic acid ester-based monomers such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate; silicone-based rubbery polymers; composite rubbery polymers of butadiene-based rubbery polymers / (meth)acrylic rubbery polymers; composite rubbery polymers of silicone-based rubbery polymers / (meth)acrylic rubbery polymers; and chlorinated polyethylene rubber. These may be used alone or in combination of two or more.

[0013] Among these rubbery polymers, (meth)acrylic rubbery polymers are preferred from the viewpoint of further improving weather resistance, and (meth)acrylic rubbery polymers containing structural units derived from (meth)acrylic acid alkyl esters in which the alkyl group has 4 or more carbon atoms are preferred. From the viewpoint of further improving weather resistance, the content of structural units derived from (meth)acrylic acid alkyl esters in which the alkyl group has 4 or more carbon atoms in the (meth)acrylic rubbery polymer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. The upper limit of the content of structural units derived from (meth)acrylic acid alkyl esters in which the alkyl group has 4 or more carbon atoms in the (meth)acrylic rubbery polymer is not particularly limited, but can be, for example, 95% by mass or less.

[0014] Examples of (meth)acrylic acid alkyl esters in which the alkyl group has 4 or more carbon atoms include butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, etc. The upper limit of the number of carbon atoms in the alkyl group in a (meth)acrylic acid alkyl ester in which the alkyl group has 4 or more carbon atoms is not particularly limited, but can be, for example, 15 or less or 10 or less.

[0015] The acrylic rubber-like polymer may be crosslinked with a crosslinking agent, such as divinylbenzene, allyl (meth)acrylate, ethylene glycol di(meth)acrylate, diallyl phthalate, dicyclopentadiene di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, triallyl cyanurate, or triallyl isocyanurate.

[0016] The content of structural units derived from the crosslinking agent in the rubber-like polymer crosslinked with the crosslinking agent can be, for example, 0.1 to 5% by mass.

[0017] The acrylic rubber-like polymer may have structural units derived from monomers other than the above-mentioned monomers, such as structural units derived from conjugated diene monomers, aromatic vinyl monomers, and vinyl cyanide monomers.

[0018] Examples of the conjugated diene monomer include 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene, chloroprene, 2-methyl-1,3-butadiene, and 2,3-dimethyl-1,3-butadiene, and these can be used alone or in combination.

[0019] Examples of the aromatic vinyl monomer include styrene, α-methylstyrene, paramethylstyrene, and bromostyrene, and one or more of these can be used.

[0020] Examples of vinyl cyanide monomers include acrylonitrile, methacrylonitrile, ethacrylonitrile, fumaronitrile, etc., and these may be used alone or in combination.

[0021] The content of the structural units derived from the conjugated diene monomer, aromatic vinyl monomer, or vinyl cyanide monomer in the rubbery polymer can be each independently set to, for example, 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. When the rubbery polymer contains these structural units, the lower limit of the content is not particularly limited, but each independently set to, for example, 1% by mass or more.

[0022] The rubber-like polymer can be produced by a conventional method, for example, emulsion polymerization, in which a polymerization initiator, an emulsifier, a polymerization modifier, etc. may be used.

[0023] Examples of the polymerization initiator include water-soluble polymerization initiators such as potassium persulfate, sodium persulfate, and ammonium persulfate, and oil-soluble polymerization initiators such as cumene hydroperoxide, benzoyl peroxide, t-butyl hydroperoxide, acetyl peroxide, diisopropylbenzene hydroperoxide, and 1,1,3,3-tetramethylbutyl hydroperoxide.

[0024] Examples of the emulsifier include carboxylates, sulfates, sulfonates, etc. Specific examples of preferably used emulsifiers include potassium oleate, dipotassium alkenyl succinate, sodium rosinate, potassium rosinate, and sodium dodecylbenzenesulfonate.

[0025] Examples of the polymerization regulator include alkyl mercaptans such as n-dodecyl mercaptan and t-dodecyl mercaptan.

[0026] From the viewpoint of improving the impact resistance of the graft copolymer resin (A), the rubbery polymer preferably has a gel content of 75 to 90%. The gel content of the rubbery polymer is measured, for example, by the method described in the Examples below.

[0027] The average particle size of the rubber polymer is not particularly limited, but can be, for example, more than 100 nm and not more than 800 nm, preferably more than 150 nm and not more than 500 nm. In this specification, the average particle size of the rubber polymer can be measured by dynamic light scattering using a photon correlation method in accordance with JIS Z8826, for example.

[0028] From the viewpoint of the balance between impact resistance and color development, the graft copolymer resin (A) preferably contains 10 to 90 mass %, more preferably 30 to 80 mass %, and even more preferably 40 to 70 mass % of the rubber-like polymer.

[0029] The vinyl monomer used in the graft polymerization includes a vinyl cyanide monomer and an aromatic vinyl monomer. The vinyl monomer preferably further includes a (meth)acrylic acid alkyl ester having an alkyl group with 4 or more carbon atoms. The vinyl cyanide monomer, aromatic vinyl monomer, and (meth)acrylic acid alkyl ester having an alkyl group with 4 or more carbon atoms can be the same as those described above.

[0030] The content of the vinyl cyanide monomer used in the graft polymerization can be, for example, 10 to 40 mass%, preferably 15 to 35 mass%, more preferably 20 to 30 mass%, based on the total amount of vinyl monomers. The content of the aromatic vinyl monomer used in the graft polymerization can be, for example, 40 to 80 mass%, preferably 45 to 75 mass%, more preferably 50 to 70 mass%, based on the total amount of vinyl monomers.

[0031] The content of the (meth)acrylic acid alkyl ester in which the alkyl group has 4 or more carbon atoms in the vinyl-based monomer used in the graft polymerization is preferably 10 to 30 mass % based on the total amount of the vinyl-based monomer, from the viewpoint of further improving chemical resistance.

[0032] The free resin contained in the graft copolymer resin (A) contains 10 to 35 mass% of structural units derived from (meth)acrylic acid alkyl esters, the alkyl group of which has 4 or more carbon atoms, based on the total amount of the free resin. By satisfying this requirement, chemical resistance is improved.

[0033] The graft copolymer resin (A) can be produced by a conventionally known method, such as emulsion polymerization, suspension polymerization, or bulk polymerization. When emulsion polymerization is used, the rubber-like polymer is graft-polymerized with the vinyl monomer to obtain a latex of the graft copolymer resin (A). The latex of the graft copolymer resin (A) is coagulated by a known method, and then washed, dehydrated, and dried to obtain a powder of the graft copolymer resin (A).

[0034] In this specification, the free resin refers to a resin that can be separated from the graft copolymer resin (A) by the following procedures (a) and (b). (A) Acetone is added to the graft copolymer resin (A), and then the insoluble matter is separated from the soluble matter by centrifugation or the like. This separates the graft copolymer as the insoluble matter. (a) The resulting solution is reprecipitated using a poor solvent such as methanol, and the precipitate is recovered by filtration or other methods. This separates the unreacted vinyl monomers and other components into the solution. The remaining precipitate is dried to obtain the free resin to be analyzed.

[0035] The types of structural units contained in the free resin can be determined by applying known techniques such as pyrolysis gas chromatography. Furthermore, the content of structural units contained in the free resin, particularly the content of structural units derived from vinyl cyanide monomers, aromatic vinyl monomers, and (meth)acrylic acid alkyl esters, can be calculated by determining the content of each structural unit using CHN analysis, oxygen analysis, etc. described in the examples.

[0036] The free resin content in the graft copolymer resin (A) can be adjusted, for example, by the following methods (a) to (c). (A) The content of the (meth)acrylic acid alkyl ester in which the alkyl group has 4 or more carbon atoms in the vinyl monomer used in the graft polymerization is adjusted to, for example, 10 to 30 mass %. (a) As an emulsifier used in the production of a rubbery polymer, for example, rosin acid or a derivative thereof is used. (c) When producing a rubbery polymer, a polymerization regulator, such as t-dodecyl mercaptan, is added.

[0037] The content of the graft copolymer resin (A) in the thermoplastic resin composition can be, for example, 5 to 60 mass%, preferably 10 to 50 mass%, and more preferably 15 to 40 mass%, based on the total amount of the thermoplastic resin composition.

[0038] [Graft copolymer resin (B)] The graft copolymer resin (B) is obtained by graft polymerizing a vinyl monomer including an aromatic vinyl monomer onto a rubbery polymer containing a structural unit derived from a (meth)acrylic acid ester. The graft copolymer resin (B) includes a graft copolymer in which a vinyl monomer is graft polymerized onto a rubbery polymer, as well as a free resin in which vinyl monomers are polymerized together, and may contain unreacted vinyl monomers, etc.

[0039] Although the graft copolymer resin (B) may conceptually overlap with the graft copolymer resin (A), they must each be present as an independent component in the thermoplastic resin composition. That is, even when a graft copolymer resin satisfying the requirements of the graft copolymer resin (A) and the graft copolymer resin (B) is used, the thermoplastic resin composition must further contain the graft copolymer resin (A) or the graft copolymer resin (B).

[0040] Examples of the rubbery polymer include (meth)acrylic rubbery polymers containing as the main component a (meth)acrylic acid ester monomer such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, or 2-ethylhexyl (meth)acrylate; a composite rubbery polymer of a butadiene rubbery polymer / (meth)acrylic rubbery polymer; a composite rubbery polymer of a silicone rubbery polymer / (meth)acrylic rubbery polymer; etc. These may be used alone or in combination of two or more.

[0041] Among these rubbery polymers, (meth)acrylic rubbery polymers are preferred from the viewpoint of further improving weather resistance, (meth)acrylic rubbery polymers containing structural units derived from (meth)acrylic acid alkyl esters are more preferred, and (meth)acrylic rubbery polymers containing structural units derived from (meth)acrylic acid alkyl esters in which the alkyl group has 4 or more carbon atoms are even more preferred. From the viewpoint of further improving weather resistance, the content of structural units derived from (meth)acrylic acid alkyl esters (particularly (meth)acrylic acid alkyl esters in which the alkyl group has 4 or more carbon atoms) in the (meth)acrylic rubbery polymer is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more. There are no particular limitations on the upper limit of the content of structural units derived from (meth)acrylic acid alkyl esters in the (meth)acrylic rubbery polymer. For example, the entire amount may be structural units derived from (meth)acrylic acid alkyl esters, or the content of structural units derived from (meth)acrylic acid alkyl esters may be 95% by mass or less.

[0042] Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and octyl (meth)acrylate.

[0043] The rubber-like polymer may be crosslinked with a crosslinking agent, such as divinylbenzene, allyl (meth)acrylate, ethylene glycol di(meth)acrylate, diallyl phthalate, dicyclopentadiene di(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritol hexa(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, triallyl cyanurate, or triallyl isocyanurate.

[0044] The content of structural units derived from the crosslinking agent in the rubber-like polymer crosslinked with the crosslinking agent can be, for example, 0.1 to 5% by mass.

[0045] The rubber-like polymer may have a structural unit derived from a monomer other than the (meth)acrylic acid alkyl ester, such as a structural unit derived from a conjugated diene monomer, an aromatic vinyl monomer, or a vinyl cyanide monomer. As the conjugated diene monomer, aromatic vinyl monomer, and vinyl cyanide monomer, the same ones as those exemplified for the graft copolymer resin (A) can be used.

[0046] The content of the structural units derived from the conjugated diene monomer, aromatic vinyl monomer, or vinyl cyanide monomer in the rubbery polymer can be each independently set to, for example, 30% by mass or less, more preferably 20% by mass or less, and even more preferably 10% by mass or less. When the rubbery polymer contains these structural units, the lower limit of the content is not particularly limited, but each independently set to, for example, 1% by mass or more.

[0047] The rubber-like polymer can be produced by a conventionally known method, such as emulsion polymerization, in the same manner as the graft copolymer resin (A).

[0048] The average particle size of the rubbery polymer is 50 nm to 150 nm, preferably 55 nm to 135 nm, and more preferably 60 nm to 120 nm, which allows for a well-balanced improvement in impact resistance and color development.

[0049] From the viewpoint of balance of impact resistance, the graft copolymer resin (B) preferably contains 10 to 90 mass % of the rubber-like polymer, more preferably 30 to 80 mass %, and even more preferably 40 to 70 mass %.

[0050] The vinyl monomer used in the graft polymerization includes an aromatic vinyl monomer. Preferably, the vinyl monomer further includes a vinyl cyanide monomer. The aromatic vinyl monomer and the vinyl cyanide monomer may be the same as those described above.

[0051] The content of the aromatic vinyl monomer used in the graft polymerization can be, for example, 50 to 90 mass%, preferably 55 to 85 mass%, more preferably 60 to 80 mass%, based on the total amount of vinyl monomers. The content of the vinyl cyanide monomer used in the graft polymerization can be, for example, 10 to 40 mass%, preferably 15 to 35 mass%, more preferably 20 to 30 mass%, based on the total amount of vinyl monomers.

[0052] The graft copolymer resin (B) can be produced by a conventionally known method, as in the case of the graft copolymer resin (A), and examples of polymerization methods that can be used include emulsion polymerization, suspension polymerization, and bulk polymerization. When emulsion polymerization is used, a latex of the graft copolymer resin (B) can be obtained by graft polymerizing the vinyl monomer described above onto the rubber-like polymer. The latex of the graft copolymer resin (B) can be coagulated by a known method, and then subjected to washing, dehydration, and drying steps to obtain a powder of the graft copolymer resin (B).

[0053] The content of the graft copolymer resin (B) in the thermoplastic resin composition can be, for example, 0.5 to 40 mass%, preferably 1 to 35 mass%, and more preferably 1.5 to 30 mass%, based on the total amount of the thermoplastic resin composition.

[0054] [Copolymer (C)] The copolymer (C) is obtained by polymerizing vinyl monomers including an aromatic vinyl monomer and a vinyl cyanide monomer.

[0055] As the aromatic vinyl monomer and the vinyl cyanide monomer, the same ones as those described above can be suitably used.

[0056] The content of the aromatic vinyl monomer in the vinyl monomers can be, for example, 50 to 95 mass%, preferably 55 to 90 mass%, more preferably 60 to 85 mass%, based on the total amount of vinyl monomers. The content of the vinyl cyanide monomer in the vinyl monomers can be, for example, 5 to 50 mass%, preferably 10 to 45 mass%, more preferably 15 to 40 mass%, based on the total amount of vinyl monomers.

[0057] The vinyl monomer may further contain a (meth)acrylic acid ester monomer and a maleimide monomer. As the (meth)acrylic acid ester monomer, the same monomers as those described above can be suitably used. As the maleimide monomer, for example, N-phenylmaleimide, N-cyclohexylmaleimide, etc. can be mentioned. These can be used alone or in combination of two or more.

[0058] When the vinyl monomer contains a (meth)acrylic acid ester monomer and / or a maleimide monomer, the content thereof can be, for example, independently, 50% by mass or less, preferably 30% by mass or less, and more preferably 10% by mass or less. When these monomers are contained, the lower limit of the content is not particularly limited, but can be, for example, independently, 1% by mass or more.

[0059] Specific examples of copolymer (C) include styrene-acrylonitrile copolymer (AS resin), α-methylstyrene-acrylonitrile copolymer (αMS-ACN resin), methyl methacrylate-acrylonitrile-styrene copolymer (MAS resin), and styrene-N-phenylmaleimide-acrylonitrile copolymer (SA-NPMI resin).

[0060] The copolymer (C) can be obtained by polymerizing the vinyl monomers by a conventional method, for example, emulsion polymerization. During emulsion polymerization, a polymerization initiator, an emulsifier, a polymerization regulator, etc. may be used, as in the case of the graft copolymer resin (A). The copolymer (C) can also be powdered, as in the case of the graft copolymer resin (A).

[0061] The content of copolymer (C) in the thermoplastic resin composition can be, for example, 40 to 90 mass%, preferably 45 to 85 mass%, and more preferably 50 to 80 mass%, based on the total amount of the thermoplastic resin composition.

[0062] Various additives, such as known antioxidants, light stabilizers, lubricants, plasticizers, antistatic agents, colorants, flame retardants, matting agents, fillers, and glass fibers, may be added to the thermoplastic resin composition of the present embodiment as needed.

[0063] The thermoplastic resin composition of this embodiment can be obtained in the form of pellets by melt-kneading using a known device such as a Banbury mixer, a roll mill, a twin-screw extruder, etc. The thermoplastic resin composition thus obtained can be molded by injection molding, extrusion molding, compression molding, injection-compression molding, blow molding, etc.

[0064] The molded article molded from the thermoplastic resin composition of this embodiment has excellent impact resistance, color development, and the like, and can therefore be suitably applied to vehicle interior and exterior parts, office automation equipment, building materials, and the like. [Example]

[0065] 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 examples, percentages are based on mass.

[0066] [Production of cross-linked butyl acrylate rubber latex (a-1)] A nitrogen-purged glass reactor was charged with 219 parts by mass of deionized water, 10 parts by mass of styrene, 5.0 parts by mass of butyl acrylate, 0.035 parts by mass of allyl methacrylate, 0.011 parts by mass of t-dodecyl mercaptan, 0.15 parts by mass of sodium dodecylbenzenesulfonate (solid content equivalent), and 0.15 parts by mass of potassium persulfate, and the mixture was reacted at 65°C for 1 hour. Then, a mixed solution of 85 parts by mass of butyl acrylate, 0.60 parts by mass of allyl methacrylate, and 0.189 parts by mass of t-dodecyl mercaptan and an emulsifier aqueous solution prepared by dissolving 0.75 parts by mass (solid content equivalent) of sodium dodecylbenzenesulfonate in 24 parts by mass of deionized water were continuously added over 3 hours. After the dropwise addition, the mixture was maintained for 3.5 hours to obtain a crosslinked butyl acrylate rubber latex (a-1).

[0067] <Gel content measurement method> The gel content of the crosslinked butyl acrylate rubber latex (a-1) was measured by the following method. After drying the cross-linked butyl acrylate rubber latex (a-1), 0.25 g of the latex was immersed in 100 ml of toluene for 48 hours, filtered through a 300-mesh wire net, and the filtration residue was completely dried. The weight (W0) before immersion in toluene and after drying and the weight (W1) of the completely dried filtration residue were measured, and the gel content was calculated using the following formula. As a result, the gel content of the cross-linked butyl acrylate rubber latex (a-1) was found to be 85%. (W1 / W0) x 100 = gel content [%]

[0068] [Production of Graft Copolymer Resin (a-2)] A nitrogen-purged glass reactor was charged with 50 parts by weight (solids equivalent) of crosslinked butyl acrylate rubber latex (a-1) and subjected to nitrogen purge. After nitrogen purge, the temperature inside the reactor was raised to 60°C, and an aqueous solution of 0.40 parts by weight of glucose, 0.025 parts by weight of anhydrous sodium pyrophosphate, and 0.001 parts by weight of ferrous sulfate dissolved in 9.0 parts by weight of deionized water was added. After the temperature reached 65°C, a mixture of 11.7 parts by weight of acrylonitrile (ACN), 33.3 parts by weight of styrene (STY), 5 parts by weight of butyl acrylate, and 0.1 parts by weight of t-dodecyl mercaptan and an emulsifier aqueous solution of 1.0 part by weight of potassium oleate and 0.28 parts by weight of t-butyl hydroperoxide (solids equivalent) dissolved in 16 parts by weight of deionized water were continuously added dropwise over 6 hours. After the dropwise addition, the mixture was maintained for 2 hours to obtain graft copolymer resin (a-2).

[0069] [Production of Graft Copolymer Resin Powder (A)] Deionized water was added to a single-tank coagulation tank equipped with a stirring blade, so that the slurry concentration would be 18% when 100 parts by mass of graft copolymer resin (a-2) was added to the tank (solid content equivalent). Then, 4.0 parts by mass of magnesium sulfate was added, and the temperature was raised to 85°C. After reaching 85°C, 100 parts by mass of graft copolymer resin (a-2) and 1.3 parts by mass of disproportionated potassium rosinate were added. After the addition, the temperature was raised to 95°C and held for 1 minute, followed by washing with water, dehydration, and drying in a hot air dryer at 90°C for 14 hours to obtain graft copolymer resin powder (A).

[0070] <Free resin composition analysis> A free resin composition analysis was performed on the graft copolymer resin powder (A). Specifically, for a measurement sample prepared by the following method, the amount of acrylonitrile was calculated from the amount of nitrogen using the CHN analysis described below, and the amount of butyl acrylate was calculated from the amount of oxygen using the oxygen (O) analysis described below. The total of acrylonitrile, styrene, and butyl acrylate was set at 100%, and the amount of styrene was calculated by subtracting the calculated amounts of acrylonitrile and butyl acrylate. The amount of butyl acrylate in the free resin was calculated based on the amount of acrylonitrile, the amount of butyl acrylate, and the amount of styrene. As a result, the amount of butyl acrylate in the free resin of the graft copolymer resin powder (A) was 14.0%.

[0071] (Preparation of measurement sample) 4.0 g of graft copolymer resin powder was weighed, 50 mL of acetone was added, and the mixture was left for 16 hours. After that, the insoluble matter was separated from the soluble matter by centrifugation (20,000 rpm for 1 hour). The soluble matter was concentrated, dissolved in acetone, reprecipitated with methanol, filtered, and the residue was dried to obtain a solid. This solid was used as the measurement sample.

[0072] (CHN analysis conditions) Equipment: JM10 manufactured by J Science Lab Co., Ltd. Standard samples: acetanilide, phenacetin, antipyrine Temperature: 1000℃

[0073] (Oxygen analysis conditions) Equipment: Yanaco Analysis Industry Co., Ltd. MO-20 Standard sample: cholesterol Temperature: 1000℃

[0074] [Production of cross-linked butyl acrylate rubber latex (b-1)] A nitrogen-substituted glass reactor was charged with 206 parts by mass of deionized water, 100 parts by mass of butyl acrylate, 0.64 parts by mass of allyl methacrylate, 3.0 parts by mass (solid content equivalent) of dipotassium alkenyl succinate, and 0.010 parts by mass (solid content equivalent) of t-butyl hydroperoxide, and the temperature inside the vessel was raised to 40°C. When the temperature inside the tank reached 40°C, an aqueous solution prepared by dissolving 0.020 parts by mass of formaldehyde sodium sulfoxylate, 0.010 parts by mass of ethylenediaminetetraacetic acid tetrasodium salt, and 0.001 parts by mass of ferrous sulfate in 10.0 parts by mass of deionized water was added. After the addition, the mixture was maintained for 5.0 hours to obtain a crosslinked butyl acrylate rubber latex (b-1).

[0075] [Production of cross-linked butyl acrylate rubber latex (b-2)] A nitrogen-substituted glass reactor was charged with 206 parts by mass of deionized water, 3.0 parts by mass (solid content equivalent) of dipotassium alkenyl succinate, and 0.050 parts by mass (solid content equivalent) of t-butyl hydroperoxide, and the temperature inside the vessel was raised to 40°C. When the temperature inside the tank reached 40°C, an aqueous solution prepared by dissolving 0.050 parts by mass of formaldehyde sodium sulfoxylate, 0.010 parts by mass of ethylenediaminetetraacetic acid tetrasodium salt, and 0.001 parts by mass of ferrous sulfate in 10.0 parts by mass of deionized water was added. After the addition, a mixed solution of 100 parts by mass of butyl acrylate and 0.64 parts by mass of allyl methacrylate was continuously added over 3 hours, and the mixture was maintained for 3.5 hours to obtain a crosslinked butyl acrylate rubber latex (b-2).

[0076] [Production of Graft Copolymer Resin (b-3)] A glass reactor was charged with 50 parts by weight (solids equivalent) of cross-linked butyl acrylate rubber latex (b-1) and subjected to nitrogen purge. After nitrogen purge, the temperature inside the reactor was raised to 60°C, and an aqueous solution of 0.80 parts by weight of glucose dissolved in 10.0 parts by weight of deionized water was added. After the temperature reached 65°C, a mixture of 12.5 parts by weight of acrylonitrile (ACN), 37.5 parts by weight of styrene (STY), and 0.05 parts by weight of t-dodecyl mercaptan and an emulsifier aqueous solution of 0.60 parts by weight of dipotassium alkenyl succinate and 0.28 parts by weight of t-butyl hydroperoxide (solids equivalent) dissolved in 10 parts by weight of deionized water were continuously added dropwise over 6 hours. After the dropwise addition, the mixture was maintained for 2 hours to obtain graft copolymer resin (b-3).

[0077] [Production of Graft Copolymer Resin (b-4)] A glass reactor was charged with 70 parts by weight (solids equivalent) of cross-linked butyl acrylate rubber latex (b-2) and subjected to nitrogen purge. After nitrogen purge, the temperature inside the reactor was raised to 60°C, and an aqueous solution of 0.24 parts by weight of glucose dissolved in 10.0 parts by weight of deionized water was added. After the temperature reached 65°C, a mixture of 7.5 parts by weight of acrylonitrile (ACN), 22.5 parts by weight of styrene (STY), and 0.060 parts by weight of t-dodecyl mercaptan and an emulsifier aqueous solution of 0.36 parts by weight of dipotassium alkenyl succinate and 0.17 parts by weight of t-butyl hydroperoxide (solids equivalent) dissolved in 10 parts by weight of deionized water were continuously added dropwise over 4 hours. After the dropwise addition, the mixture was maintained for 2 hours to obtain graft copolymer resin (b-4).

[0078] [Production of Graft Copolymer Resin Powder (B-1)] Deionized water was charged into a single-tank coagulation tank equipped with a stirring blade so that the slurry concentration would be 18% when 100 parts by mass of graft copolymer resin (b-3) was added to the tank in solids content. Then, 4.0 parts by mass of magnesium sulfate was added and the temperature was raised to 70°C. After reaching 70°C, 100 parts by mass of graft copolymer resin (b-3) was added. After the addition, the temperature was raised to 90°C and held for 1 minute, followed by washing with water, dehydration, and drying in a hot air dryer at 90°C for 14 hours to obtain graft copolymer resin powder (B-1).

[0079] [Production of Graft Copolymer Resin Powder (B-2)] A single-tank coagulation tank equipped with a stirring blade was charged with deionized water, so that the slurry concentration would be 18% when the entire amount of graft copolymer resin (b-4) was added to the tank. Then, 4.0 parts by mass of magnesium sulfate was added and the temperature was raised to 70°C. After reaching 70°C, 100 parts by mass of graft copolymer resin (b-4) was added. After the addition, the temperature was raised to 90°C and held for 1 minute, followed by washing with water, dehydration, and drying in a hot air dryer at 90°C for 14 hours to obtain graft copolymer resin powder (B-2).

[0080] [Production of Copolymer (C)] A copolymer (C) consisting of 67.3 parts by mass of styrene and 32.7 parts by mass of acrylonitrile was obtained by a known bulk polymerization method. The reduced viscosity of the obtained copolymer (C) was measured by the following method and found to be 0.52 dL / g. Dissolve in N,N-dimethylformamide to make a solution with a concentration of 0.4 g / 100 ml, and then measure the flow time at 30°C using a Cannon-Fenske viscometer to determine the reduced viscosity.

[0081] [Coloring agents for synthetic resins (D)] Carbon black (Sumika Color Co., Ltd. Black PAB-8A3645, a mixture of AS resin and carbon black, carbon black content 45%)

[0082] <Measurement of average particle size of cross-linked butyl acrylate rubber latex> The cross-linked butyl acrylate rubber latex was diluted with water, and the average particle size was measured using an FPAR-1000 manufactured by Otsuka Electronics Co., Ltd. The results are shown in Table 1.

[0083] [Table 1]

[0084] <Evaluation of Thermoplastic Resin Composition> Graft copolymer resin powders (A), (B-1), and (B-2), copolymer (C), and synthetic resin colorant (D) were mixed in the amounts (unit: parts by mass) shown in Table 2, and then melt-kneaded at 240°C using a 26 mmφ twin-screw extruder and pelletized to obtain pellets of a thermoplastic resin composition. Various molded articles were molded from the resulting pellets using an injection molding machine set at 250°C, and the following measurements and evaluations were performed. The evaluation results are shown in Table 2.

[0085] <Charpy impact strength (NC)> The pellets were used to mold various test pieces in accordance with ISO294, and the impact resistance (unit: kJ / m 2Specifically, the notched Charpy impact value was measured at a thickness of 4 mm in accordance with ISO 179. The impact resistance was evaluated according to the following criteria. A: 10kJ / m 2 End B: 4kJ / m 2 More than 10kJ / m 2 less than C: 4kJ / m 2 less than

[0086] <Evaluation of color development (jet blackness)> The pellets were used to mold various test pieces in an injection molding machine. The mold used was a 55mm x 90mm x 2.5mm thick flat mold for measuring jet blackness, with the mold surface polished to a mirror finish with a #1,500 grit, under molding conditions of a cylinder temperature of 250°C, a mold temperature of 60°C, and an injection pressure of 3 MPa. The jet blackness of the flat mirror surface of the obtained molded product was measured using a CMS-35SPJC2 manufactured by Murakami Color Research Laboratory Co., Ltd. The smaller the L* value (SCE), the better the jet blackness. Good jet blackness also means that the color development is excellent when the same amount of the same colorant is added. The color development (jet blackness) was evaluated according to the following criteria. A: L* value less than 5 B: L* value 5 or more

[0087] [Table 2]

Claims

1. a graft copolymer resin (A) obtained by graft polymerizing a vinyl monomer including a vinyl cyanide monomer and an aromatic vinyl monomer onto a rubber-like polymer, wherein the free resin contained in the graft copolymer resin (A) contains 10 to 35 mass % of a structural unit derived from a (meth)acrylic acid alkyl ester, the alkyl group of which has 4 or more carbon atoms, based on the total amount of the free resin; a graft copolymer resin (B) obtained by graft polymerizing a vinyl monomer including an aromatic vinyl monomer onto a rubbery polymer including a structural unit derived from a (meth)acrylic acid ester, wherein the average particle size of the rubbery polymer in the graft copolymer resin (B) is 50 nm to 150 nm (however, the graft copolymer resin (B) is a resin different from the graft copolymer resin (A)); a copolymer (C) obtained by copolymerizing an aromatic vinyl monomer and a vinyl monomer including a vinyl cyanide monomer (provided that the copolymer (C) is a resin different from the free resin contained in the graft copolymer resin (A)); A thermoplastic resin composition comprising: the rubber-like polymer in the graft copolymer resin (A) contains a structural unit derived from a (meth)acrylic acid alkyl ester in which the alkyl group has 4 or more carbon atoms, The content of the graft copolymer resin (A) is based on the total amount of the thermoplastic resin composition. 15 to 40% by mass, the content of the graft copolymer resin (B) is 1.5 to 30 mass% based on the total amount of the thermoplastic resin composition, the content of the copolymer (C) is 50 to 80 mass% based on the total amount of the thermoplastic resin composition, the vinyl monomer in the graft copolymer resin (B) contains 60 to 80 mass% of an aromatic vinyl monomer based on the total amount of the vinyl monomer; the vinyl monomer in the copolymer (C) contains 60 to 85 mass% of an aromatic vinyl monomer based on the total amount of the vinyl monomer; A thermoplastic resin composition, wherein the vinyl monomers in the copolymer (C) contain 15 to 40 mass % of a vinyl cyanide monomer based on the total amount of the vinyl monomers.

2. 2. The thermoplastic resin composition according to claim 1, wherein the vinyl monomer in the graft copolymer resin (A) further comprises a (meth)acrylic acid alkyl ester having an alkyl group having 4 or more carbon atoms.

3. 3. The thermoplastic resin composition according to claim 2, wherein the vinyl-based monomer in the graft copolymer resin (A) contains 10 to 30 mass% of a (meth)acrylic acid alkyl ester having an alkyl group having 4 or more carbon atoms, based on the total amount of the vinyl-based monomer.

4. The thermoplastic resin composition according to any one of claims 1 to 3, wherein the rubber-like polymer in the graft copolymer resin (A) contains 50 mass% or more of structural units derived from a (meth)acrylic acid alkyl ester, the alkyl group of which has 4 or more carbon atoms, based on the total amount of the rubber-like polymer.

5. 5. The thermoplastic resin composition according to claim 1, wherein the gel content of the rubber-like polymer in the graft copolymer resin (A) is 75 to 90%.

6. The thermoplastic resin composition according to any one of claims 1 to 5, wherein the vinyl monomers in the copolymer (C) contain 28% by mass to 40% by mass of a vinyl cyanide monomer based on the total amount of the vinyl monomers.

Images