Polypropylene-based graft polymer, thermoplastic resin composition and molded article thereof

Abstract

To provide a polypropylene-based graft polymer and a thermoplastic resin composition which can give a thermoplastic resin molding that is excellent in appearance while holding and improving mechanical characteristics such as impact resistance inherent in a thermoplastic resin, and can give an excellent two-color molding that has high adhesive strength by two-color molding with a polypropylene-based resin, and a molding of the same.SOLUTION: A polypropylene-based graft polymer is obtained by graft polymerization of a vinyl-based monomer (D) with polypropylene-based resin particles (C) that contain 100 pts.mass of a polypropylene resin and 5-25 pts.mass of an acid-modified olefin resin (B) and have a volume average particle diameter of 50-850 nm. A thermoplastic resin composition contains the polypropylene-based graft polymer. A molding is obtained by molding the thermoplastic resin composition.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polypropylene-based graft polymer, a thermoplastic resin composition containing the polypropylene-based graft polymer, and a molded article thereof. [Background technology]

[0002] Although polypropylene has excellent performance, it is not compatible with other resins. Therefore, various studies have been conducted on compatibilizers for other resins and on modifying polypropylene itself, as disclosed in, for example, Patent Documents 1 to 3 listed below.

[0003] Patent Document 1 discloses an aromatic random copolymer obtained by polymerizing an aromatic vinyl compound, a vinyl cyanide compound, and an aromatic vinyl compound having a specific functional group, and discloses that this copolymer is also useful as a modifier for other resins, or as a compatibilizer for polymer alloys of a resin selected from polyolefins and a styrene-based resin such as ABS.

[0004] Patent Document 2 discloses a polypropylene resin composition for coating, which is obtained by mixing a modified propylene polymer obtained by subjecting a hydroxyl-containing α,β-unsaturated carboxylate and an aromatic vinyl compound to a graft copolymerization process with a propylene polymer having a polar group selected from a hydroxyl group, a carboxyl group, an acid anhydride group, an epoxy group, and an amino group, and which discloses that the composition has excellent paint adhesion and high mechanical strength without requiring the application of a primer and / or cleaning with an organic solvent such as trichloroethane during coating.

[0005] Patent Document 3 discloses styrene-modified polypropylene-based resin particles obtained by polymerizing styrene around polypropylene-based resin particles as a nucleus, and discloses that this makes it possible to provide a styrene-modified polypropylene-based resin foamed molding having excellent mechanical properties, chemical resistance, and the like. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 6-279545 [Patent Document 2] Japanese Patent Application Publication No. 8-60076 [Patent Document 3] JP 2011-58008 A Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, various proposals have been made so far regarding the modification of polypropylene and compatibilizers with other resins. However, the techniques described in Patent Documents 1 and 2 are somewhat effective as compatibilizers or modifiers in improving impact strength and paintability, but are still insufficient. In addition, the technology of Patent Document 3 involves impregnating polypropylene-based resin particles with styrene and then polymerizing the particles. However, since the polypropylene-based resin particles are impregnated with styrene, sufficient strength cannot be obtained, and the function of the polypropylene-based resin as a compatibilizer is also not sufficient. In particular, the prior art has not provided fully satisfactory results with respect to the modifying effect, or the adhesiveness between resins in two-color molding of a polypropylene-based resin and a thermoplastic resin as a compatibilizer.

[0008] An object of the present invention is to provide a polypropylene-based graft polymer and a thermoplastic resin composition which can provide a thermoplastic resin molded article having excellent appearance while maintaining or improving the inherent mechanical properties of the thermoplastic resin, such as impact resistance, and which can provide an excellent two-color molded article having high adhesion strength in two-color molding with a polypropylene-based resin, and a molded article thereof. [Means for solving the problem]

[0009] As a result of extensive investigations aimed at solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a polypropylene-based graft polymer obtained by graft polymerizing a vinyl-based monomer (D) onto polypropylene-based resin particles (C) having a specific particle size and containing a polypropylene resin (A) and an acid-modified olefin resin (B) in a predetermined ratio.

[0010] That is, the present invention relates to the following.

[0011] [1] A polypropylene-based graft polymer obtained by graft polymerizing a vinyl-based monomer (D) onto polypropylene-based resin particles (C) having a volume average particle diameter of 50 to 850 nm, the polypropylene-based graft polymer comprising 100 parts by mass of a polypropylene resin (A) and 5 to 25 parts by mass of an acid-modified olefin resin (B).

[0012] [2] The polypropylene-based graft polymer according to [1], wherein the graft ratio of the polypropylene-based graft polymer is 10 to 70 mass %.

[0013] [3] The polypropylene-based graft polymer according to [1] or [2], wherein, of 100% by mass of the vinyl-based monomer (D), 50 to 90% by mass is an aromatic vinyl compound and 10 to 50% by mass is a vinyl cyanide compound.

[0014] [4] The polypropylene-based graft polymer according to any one of [1] to [3], which is obtained by graft polymerization of 20 to 70 mass% of a vinyl-based monomer (D) (the total of the polypropylene-based resin particles (C) and the vinyl-based monomer (D) is 100 mass%) in the presence of 30 to 80 mass% of a polypropylene-based resin particle (C).

[0015] [5] The polypropylene-based resin particles (C) are obtained by melt-kneading the polypropylene resin (A) and the acid-modified olefin resin (B) and dispersing the resulting kneaded mixture in an aqueous medium. The polypropylene-based graft polymer according to any one of [1] to [4].

[0016] [6] A thermoplastic resin composition comprising the polypropylene-based graft polymer according to any one of [1] to [5].

[0017] [7] The thermoplastic resin composition according to [6], wherein the content of the polypropylene-based graft polymer is 3 to 70 mass% based on 100 mass% of all resin components contained in the thermoplastic resin composition.

[0018] [8] A molded article obtained by molding the thermoplastic resin composition according to [6] or [7].

[0019] [9] A two-color molded product obtained by two-color molding of the thermoplastic resin composition of [6] or [7] and a polypropylene-based resin. Effect of the Invention

[0020] The polypropylene graft polymer of the present invention has excellent production stability and, since it has a relatively small particle size dispersed in an emulsified state, it also has excellent dispersibility in thermoplastic resins. According to the thermoplastic resin composition containing the polypropylene-based graft polymer of the present invention, it is possible to provide a thermoplastic resin molded article having excellent appearance while maintaining or improving mechanical properties such as impact resistance, and the composition can be effectively used in a wide range of applications, including products and parts in which polypropylene-based resins are used, such as vehicle interior and exterior parts. Furthermore, the thermoplastic resin composition containing the polypropylene-based graft polymer of the present invention has high adhesion strength in two-color molding with a polypropylene-based resin, and can provide an excellent two-color molded product, so that a high-quality product can be efficiently obtained without the need for an adhesion process or the like. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the preferred embodiments.

[0022] [Polypropylene-based graft polymer] The polypropylene-based graft polymer of the present invention is obtained by graft polymerizing a vinyl-based monomer (D) onto polypropylene-based resin particles (C) having a volume average particle size of 50 to 850 nm, the volume average particle size being 50 to 850 nm and including 100 parts by mass of a polypropylene resin (A) and 5 to 25 parts by mass of an acid-modified olefin resin (B). According to the polypropylene-based graft polymer of the present invention, a thermoplastic resin molded article having excellent impact resistance and appearance can be obtained. Furthermore, a thermoplastic resin composition containing this is also suitable as a two-color molding material with a polypropylene resin.

[0023] <Polypropylene resin (A)> The polypropylene resin (A) may be any resin containing propylene units as the main component at a content of 50 mol % or more, preferably 80 to 100 mol %, of all constituent units. Examples of such resins include homopolymers, which are homopolymers of propylene; random copolymers obtained by copolymerizing propylene with copolymerizing components such as ethylene and α-olefins such as 1-butene; and block copolymers obtained by homopolymerizing propylene and then copolymerizing propylene with copolymerizing components such as ethylene and α-olefins such as 1-butene. Any of these may be used.

[0024] Commercially available products can be used as the homopolymer of polypropylene resin (A). Examples of the commercially available products include Prime Polypro J105G, Prime Polypro J106G, Prime Polypro J106MG, Prime Polypro J108M, and Prime Polypro J-700GP, manufactured by Prime Polymer Co., Ltd., and Noblen FS2011DG3, Noblen WF836DG3, Noblen D101, Noblen W101, and Noblen Z101A, manufactured by Sumitomo Chemical Co., Ltd.

[0025] As the random copolymer of polypropylene resin (A), commercially available products can be used. Examples of the commercially available products include Prime Polypro J226T, Prime Polypro J229E, Prime Polypro J-721GR, Prime Polypro J-2021GR, Prime Polypro J-2023GR, Prime Polypro J-2041GA, and Prime Polypro J-3021GR, manufactured by Prime Polymer Co., Ltd., and Noblen FL6632G, Noblen FL6737, and Noblen S131, manufactured by Sumitomo Chemical Co., Ltd.

[0026] As the block copolymer of polypropylene resin (A), commercially available products can be used. Examples of the commercially available products include Prime Polypro BJS-MU, Prime Polypro J704LB, Prime Polypro J704UG, Prime Polypro U705UG, Prime Polypro J715M, Prime Polypro J707G, Prime Polypro J707EG, Prime Polypro J830HV, Prime Polypro J708UG, and Prime Polypro J709QG, manufactured by Prime Polymer Co., Ltd., and Noblen AD571, Noblen AW564, and Noblen AZ564, manufactured by Sumitomo Chemical Co., Ltd.

[0027] The degree of polymerization (molecular weight) of the polypropylene resin (A) is not particularly limited, but the melt mass flow rate (hereinafter also referred to as MFR) measured in accordance with JIS K7210 at a measurement temperature of 230°C and a load of 50N is preferably 40 to 70g / 10min, more preferably 45 to 65g / 10min. By having the MFR in this range, the emulsified state during the production of the polypropylene-based resin particles (C) can be more stably achieved. If the MFR is out of this range, the formation of the emulsion is likely to be insufficient, and the stabilization time of the emulsified state is likely to be shortened.

[0028] Such polypropylene resin (A) may be used alone or in combination of two or more kinds having different physical properties, types of copolymerization components, copolymerization compositions, and the like.

[0029] The polypropylene resin (A) used can be selected depending on the purpose. In producing the polypropylene-based graft polymer of the present invention, it is preferable to use a random copolymer, particularly a propylene-ethylene random copolymer or a propylene-1-butene random copolymer, from the viewpoint of emulsion stability.

[0030] <Acid-modified olefin resin (B)> The acid-modified polyolefin resin (B) is, for example, a polyolefin resin that is a polymer or copolymer of one or more olefins such as ethylene, propylene, 1-butene, 2-butene, isobutene, 1-pentene, 2-pentene, cyclopentene, 1-hexene, 2-hexene, cyclohexene, 1-heptene, 2-heptene, cycloheptene, 1-octene, 2-octene, cyclooctene, vinylcyclopentene, vinylcyclohexene, vinylcycloheptene, vinylcyclooctene, etc., which is modified with an acid. As the polyolefin resin, only one of these may be used, or two or more of these may be used, but among these, it is particularly preferable to use polypropylene.

[0031] The modifying group introduced by the acid modification of the polyolefin resin is preferably a sulfo group, a carboxyl group, a phosphoric acid group, a hydroxyl group, a thiol group, etc., and is particularly preferably a carboxyl group. The acid-modified olefin resin (B) having a carboxyl group introduced as an acid-modifying group can be obtained by modifying a polyolefin resin with a saturated or unsaturated carboxylic acid having a carboxyl group and a compound containing an acid anhydride group thereof.

[0032] Examples of saturated or unsaturated carboxylic acids having a carboxyl group include formic acid, acetic acid, propionic acid, acrylic acid, methacrylic acid, oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, phthalic acid, terephthalic acid, etc. Examples of compounds containing an acid anhydride group include maleic anhydride, acetic anhydride, propionic anhydride, succinic anhydride, phthalic anhydride, etc. These may be used alone or in combination of two or more.

[0033] The acid value of the acid-modified polyolefin resin (B) is preferably 1 to 60 mgKOH / g, more preferably 5 to 50 mgKOH / g. When the acid value is 1 mgKOH / g or more, the stability in the emulsified state is good, and when it is 60 mgKOH / g or less, excellent compatibility is easily obtained. From the same viewpoint, for example, in the case of maleic anhydride-modified polyolefin resin, the graft amount of maleic anhydride is preferably 1 to 20 mass%, more preferably 1 to 10 mass%. When the graft amount of maleic anhydride is 1 mass% or more, the stability in the emulsified state becomes good, and when it is 20 mass% or less, excellent compatibility is easily obtained.

[0034] As the acid-modified polyolefin resin (B), a commercially available product can be used. Examples of the commercially available acid-modified polyolefin resin (B) include UMEX 1001 (manufactured by Sanyo Chemical Industries, Ltd.) and HIWAX NP0555A and HIWAX NP50605A (manufactured by Mitsui Chemicals, Inc.).

[0035] The acid-modified polyolefin resin (B) may be used alone or in combination of two or more types differing in the type or amount of acid-modified groups introduced, acid value, type of polyolefin resin, etc.

[0036] The acid-modified polyolefin resin (B) is used in an amount of 5 to 25 parts by mass per 100 parts by mass of the polypropylene resin (A), and the blending amount is preferably 7 to 22 parts by mass. By including 5 to 25 parts by mass of the acid-modified polyolefin resin (B) per 100 parts by mass of the polypropylene resin (A), the emulsified state is stabilized, and this makes it possible to reduce the influence of the properties when blended into a thermoplastic resin composition.

[0037] <Polypropylene resin particles (C)> The polypropylene-based resin particles (C) according to the present invention are prepared by emulsifying and dispersing a polypropylene-based resin composition containing 100 parts by mass of a polypropylene resin (A) and 5 to 25 parts by mass, preferably 7 to 22 parts by mass of an acid-modified olefin resin (B) in an aqueous medium, with the polypropylene-based resin composition having a volume average particle diameter within a specific range.

[0038] The preparation method of polypropylene-based resin particles (C) is not particularly limited.The preparation method of polypropylene-based resin particles (C) can be, for example, melt-kneading polypropylene resin (A) and acid-modified olefin resin (B) with known melt-kneading means (kneader, Banbury mixer, multi-screw extruder, etc.), dispersing by applying mechanical shear force, and adding to aqueous medium containing emulsifier;The method of dissolving polypropylene resin (A) and acid-modified olefin resin (B) in a hydrocarbon solvent (pentane, hexane, heptane, benzene, toluene, xylene, etc.) together with an emulsifier, adding this to an aqueous medium to emulsify, then stirring thoroughly, and then distilling off the hydrocarbon solvent;etc.

[0039] As a method for producing polypropylene-based resin particles (C), a method in which polypropylene resin (A) and acid-modified olefin resin (B) are melt-kneaded at a temperature of about 180 to 240°C, dispersed by applying mechanical shear force, and added to an aqueous medium containing an emulsifier is preferred, since production without using organic solvents makes it possible to avoid the odor of residual solvents and the impact on health and the environment due to volatile substances, and furthermore, no special equipment is required for ventilation of organic solvent components during production.

[0040] The emulsifier may be any of the known emulsifiers, such as long-chain alkyl carboxylates, alkyl sulfosuccinates, and alkylbenzene sulfonates.

[0041] The amount of emulsifier added is preferably 1 to 15 parts by mass per 100 parts by mass of polypropylene resin (A) in the case where an anionic emulsifier such as potassium oleate is used as the emulsifier, because this can suppress thermal coloration of the resulting polypropylene resin particles (C) and makes it easy to control the particle size of the polypropylene resin particles (C). From the viewpoints of improving the dispersibility of the polypropylene resin particles (C) and the stability of the emulsion, it is preferable to previously mix the emulsifier with the polypropylene resin (A) and the acid-modified olefin resin (B) prior to melt-kneading.

[0042] In addition, during melt kneading, an alkali such as potassium hydroxide or sodium hydroxide is added as an aqueous solution. Adding an aqueous alkali solution makes it easier to control the volume average particle diameter of the resulting polypropylene resin particles (C). The alkali is preferably added as an aqueous solution with a concentration of about 5 to 20% by mass, and the amount added varies depending on other conditions and the desired volume average particle diameter, but is preferably about 1 to 10 parts by mass per 100 parts by mass of the polypropylene resin (A).

[0043] The polypropylene resin (A) and the acid-modified olefin resin (B) are melt-kneaded and dispersed by applying a mechanical shear force to the resulting kneaded mixture, which is then cooled to 60 to 120°C and then added to an aqueous medium for emulsification. Water is usually used as the aqueous medium. The temperature of the aqueous medium when the kneaded mixture is added is preferably 80 to 90°C from the viewpoint of dispersibility.

[0044] The solids concentration (polypropylene resin particle (C) concentration) of the aqueous dispersion of polypropylene resin particles (C) thus obtained is preferably about 20 to 60 mass % from the viewpoints of handleability during the subsequent graft polymerization reaction, productivity, long-term emulsion stability, etc.

[0045] In the present invention, the volume average particle diameter of the polypropylene resin particles (C) is 50 to 850 nm, preferably 150 to 750 nm, and more preferably 250 to 650 nm, from the viewpoints of excellent emulsion stability, dispersibility in thermoplastic resins, and physical properties of the resulting molded products. The volume average particle size of the polypropylene resin particles (C) is a value measured by the method described in the Examples section below.

[0046] Methods for controlling the volume average particle diameter of the polypropylene resin particles (C) include adjusting the type or amount of emulsifier, addition of alkali during melt kneading, shear force applied during kneading, temperature conditions, and the like.

[0047] <Vinyl Monomer (D)> Examples of the vinyl monomer (D) include aromatic vinyl compounds, vinyl cyanide compounds, (meth)acrylic acid ester compounds, maleimide compounds, unsaturated acid anhydrides, carboxyl group-containing unsaturated compounds, amino group-containing unsaturated compounds, amide group-containing unsaturated compounds, hydroxyl group-containing unsaturated compounds, oxazoline group-containing unsaturated compounds, etc. These compounds may be used alone or in combination of two or more.

[0048] The vinyl monomer (D) is preferably one containing an aromatic vinyl compound, and more preferably a monomer mixture containing a vinyl cyanide compound.

[0049] Examples of aromatic vinyl compounds include styrene, α-methylstyrene, o-, m- or p-methylstyrene, vinylxylene, pt-butylstyrene, ethylstyrene, etc. From the viewpoint of impact resistance and appearance of the resulting molded product, styrene and α-methylstyrene are preferred. The aromatic vinyl compounds may be used alone or in combination of two or more.

[0050] Examples of the vinyl cyanide compound include acrylonitrile, methacrylonitrile, etc. The vinyl cyanide compound may be used alone or in combination of two or more kinds.

[0051] The content of the aromatic vinyl compound is preferably 50 to 90 mass%, more preferably 60 to 85 mass%, and even more preferably 70 to 80 mass% based on 100 mass% of the vinyl monomer (D). When the content of the aromatic vinyl compound is within the above range, the color development, transparency, and impact resistance of the obtained molded article are further improved. The content of the vinyl cyanide compound is preferably 10 to 50 mass%, more preferably 15 to 40 mass%, and even more preferably 20 to 30 mass%, based on 100 mass% of the vinyl monomer (D). If the content of the vinyl cyanide compound is within the above range, the impact resistance and appearance of the molded article will be further improved.

[0052] The vinyl monomer (D) may contain, in addition to the aromatic vinyl compound and the vinyl cyanide compound, other monomers copolymerizable therewith, for example, in an amount of 30 mass% or less per 100 mass% of the vinyl monomer (D), as long as the effect of the present invention is not impaired. Examples of the other monomers include (meth)acrylic acid ester compounds (methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, etc.), maleimide compounds (N-cyclohexylmaleimide, N-phenylmaleimide, etc.), etc. One type of the other monomers may be used alone, or two or more types may be used in combination.

[0053] <Polypropylene-based graft polymer> The polypropylene graft polymer of the present invention can be obtained by graft polymerizing a vinyl monomer (D) in the presence of polypropylene resin particles (C).

[0054] The polypropylene-based graft polymer is preferably one obtained by graft polymerization of 20 to 70 mass % of a vinyl-based monomer (D) (wherein the total of the polypropylene-based resin particles (C) and the vinyl-based monomer (D) is 100 mass %) in the presence of 30 to 80 mass % of a polypropylene-based resin particle (C) because the resulting molded article has excellent impact resistance and appearance.

[0055] The graft ratio of the polypropylene-based graft polymer is preferably 10 to 70% by mass, more preferably 15 to 60% by mass, and even more preferably 20 to 50% by mass, in terms of excellent impact resistance and appearance of the resulting molded article. The graft ratio herein is a value measured by the method described in the Examples section below.

[0056] The graft polymerization method of the vinyl monomer (D) onto the polypropylene resin particles (C) may be a known polymerization method (emulsion polymerization method, solution polymerization method, suspension polymerization method, bulk polymerization method, etc.). As the graft polymerization method, the emulsion polymerization method is particularly preferred because the obtained molded article has better impact resistance and appearance.

[0057] As a method for producing a polypropylene-based graft polymer by emulsion polymerization, for example, an organic peroxide is mixed with a vinyl-based monomer (D), and then the vinyl-based monomer (D) is continuously added to an aqueous dispersion of polypropylene-based resin particles (C) to perform graft polymerization at about 70 to 95°C. The organic peroxide is preferably used as a redox initiator in which an organic peroxide, a transition metal, and a reducing agent are combined. During graft polymerization, a chain transfer agent, an emulsifier, etc. may be used depending on the situation.

[0058] As the redox initiator, a combination of an organic peroxide and ferrous sulfate-chelating agent-reducing agent is preferred, since it does not require high temperature polymerization reaction conditions, it avoids deterioration of the polypropylene resin particles (C), and it avoids a decrease in the impact resistance of the resulting molded product. Examples of the organic peroxide include cumene hydroperoxide, diisopropylbenzene hydroperoxide, and t-butyl hydroperoxide, and the amount of the organic peroxide added is preferably about 0.5 to 4 parts by mass based on 100 parts by mass of the vinyl monomer (D). More preferably, the redox initiator comprises cumene hydroperoxide, ferrous sulfate, sodium pyrophosphate, and dextrose and / or lactose.

[0059] Examples of the chain transfer agent include mercaptans (octyl mercaptan, n- or t-dodecyl mercaptan, n-hexadecyl mercaptan, n- or t-tetradecyl mercaptan, etc.), allyl compounds (allylsulfonic acid, methallylsulfonic acid, sodium salts thereof, etc.), α-methylstyrene dimer, etc. Mercaptans are preferred because they are easy to adjust the molecular weight. The chain transfer agent may be used alone or in combination of two or more. The chain transfer agent may be added all at once, in portions, or continuously.

[0060] The amount of the chain transfer agent added is preferably 2.0 parts by mass or less based on 100 parts by mass of the vinyl monomer (D).

[0061] The emulsifier includes anionic surfactants, nonionic surfactants, amphoteric surfactants, and the like. Examples of the anionic surfactant include sulfate esters of higher alcohols, alkylbenzene sulfonates, fatty acid sulfonates, phosphoric acid salts, fatty acid salts, and amino acid derivative salts. Examples of the nonionic surfactant include ordinary polyethylene glycol alkyl ester type, alkyl ether type, alkyl phenyl ether type, and the like. Examples of amphoteric surfactants include those having a carboxylate, sulfate, sulfonate, phosphate, or the like at the anion moiety, and an amine salt, quaternary ammonium salt, or the like at the cation moiety.

[0062] The amount of the emulsifier added is preferably 10 parts by mass or less based on 100 parts by mass of the vinyl monomer (D).

[0063] The polypropylene-based graft polymer obtained by the emulsion polymerization method is in a state of being dispersed in an aqueous medium. As a method for recovering the polypropylene-based graft polymer from an aqueous dispersion containing the polypropylene-based graft polymer, for example, a precipitation method in which a precipitating agent is added to the aqueous dispersion, the mixture is heated and stirred, the precipitating agent is separated, and the precipitated polypropylene-based graft polymer is washed with water, dehydrated, and dried can be mentioned. Examples of the precipitating agent include aqueous solutions of sulfuric acid, acetic acid, calcium chloride, magnesium sulfate, etc. The precipitating agent may be used alone or in combination of two or more kinds.

[0064] If necessary, an antioxidant may be added to the aqueous dispersion containing the polypropylene-based graft polymer.

[0065] [Thermoplastic resin composition] <Thermoplastic resin> The thermoplastic resin composition of the present invention contains the polypropylene-based graft polymer of the present invention. The thermoplastic resin contained in the thermoplastic resin composition of the present invention together with the polypropylene-based graft polymer of the present invention may be, for example, one or more of polyvinyl chloride, polystyrene, ABS resin, ASA resin, AES resin, SAS resin derived from silicone rubber, AS copolymer, acrylonitrile-styrene-methyl methacrylate copolymer, styrene-acrylonitrile-N-phenylmaleimide copolymer, α-methylstyrene-acrylonitrile copolymer, polymethyl methacrylate, methyl methacrylate-styrene copolymer, methyl methacrylate-N-phenylmaleimide copolymer, polycarbonate, polyamide, polyester such as polyethylene terephthalate and polybutylene terephthalate, polyolefin such as polypropylene and polyethylene, polyphenylene ether-polystyrene complex, etc.

[0066] <Content of polypropylene-based graft polymer> The amount of the polypropylene-based graft polymer of the present invention to be blended with these thermoplastic resins can be selected depending on the purpose and application, such as using the polypropylene-based graft polymer of the present invention as a modifier or a compatibilizer, and the content of the polypropylene-based graft polymer is preferably 3 to 70 mass%, more preferably 5 to 50 mass%, based on 100 mass% of all resin components contained in the thermoplastic resin composition. If the content of the polypropylene-based graft polymer is equal to or more than the lower limit, the compatibilizing effect and the modifying effect due to the inclusion of the polypropylene-based graft polymer can be sufficiently obtained. If the content of the polypropylene-based graft polymer is equal to or less than the upper limit, the deterioration of mechanical properties such as impact resistance and appearance due to the inclusion of the polypropylene-based graft polymer can be suppressed.

[0067] Furthermore, the total proportion of polypropylene resin components in 100% by mass of all resin components in the thermoplastic resin composition of the present invention (the total proportion of polypropylene resin (A) in the polypropylene-based graft polymer and propylene resins contained in the thermoplastic resin composition as other thermoplastic resins) is preferably 1 to 60% by mass, particularly 5 to 40% by mass, from the viewpoints of mechanical properties such as impact resistance, appearance, adhesion strength in two-color molded products, and the like.

[0068] <Additives> The thermoplastic resin composition of the present invention may contain additives as necessary. Examples of the additives include one or more of colorants such as pigments and dyes, fillers (carbon black, silica, titanium oxide, etc.), flame retardants, stabilizers, reinforcing agents, processing aids, heat resistance agents, antioxidants, weather resistance agents, release agents, plasticizers, and antistatic agents.

[0069] [Molded products] The molded article of the present invention is obtained by molding the thermoplastic resin composition of the present invention, and has excellent impact resistance and appearance.

[0070] Examples of methods for molding the thermoplastic resin composition of the present invention include injection molding, injection compression molding, extrusion, blow molding, vacuum molding, pressure molding, calendar molding, inflation molding, etc. Among these, injection molding and injection compression molding are preferred because they are excellent in mass productivity and can give molded products with high dimensional accuracy.

[0071] The molded article of the present invention obtained by molding the thermoplastic resin composition of the present invention has excellent impact resistance and appearance, and is therefore suitable for vehicle interior and exterior parts, office automation equipment, building materials, and the like.

[0072] In addition, since the thermoplastic resin composition of the present invention contains the polypropylene-based graft polymer of the present invention, it has excellent adhesion (tightness) between the resins in two-color molding with a polypropylene-based resin, and can give two-color molded articles with good appearance, and is therefore useful as a two-color molding material for polypropylene-based resin / thermoplastic resin. Such two-color molded products can be suitably used for applications such as vehicle interior and exterior parts and electrical appliances, due to the excellent properties of the polypropylene-based resin, such as light weight and chemical resistance, and the bonding strength provided by the thermoplastic resin composition molded with this two-color resin.

[0073] Examples of industrial applications of the molded article of the present invention obtained by molding the thermoplastic resin composition of the present invention and the two-color molded article of the present invention using the thermoplastic resin composition of the present invention include various exterior and interior parts as vehicle parts, building material parts such as wall materials and window frames, tableware, toys, home appliance parts such as vacuum cleaner housings, television housings and air conditioner housings, interior materials, ship materials, and communication device housings. EXAMPLES

[0074] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to the following examples in any way as long as the gist of the present invention is not exceeded. In the following description, "parts" means "parts by mass" and "%" means "% by mass".

[0075] [Measurement, evaluation and operation methods] The various measurements, evaluations and procedures therefor in the following Examples and Comparative Examples are as follows:

[0076] <Measurement of average particle size> The volume average particle size (MV) measured using a Microtrac (Nanotrac 150 manufactured by Nikkiso Co., Ltd.) and pure water as the measurement solvent was taken as the average particle size.

[0077] <Calculation of graft ratio> 1 g of the polypropylene-based graft polymer was added to 80 mL of acetone, heated under reflux at 65 to 70° C. for 3 hours, and the resulting acetone suspension was centrifuged at 14,000 rpm for 30 minutes in a centrifuge (manufactured by Hitachi Koki, “CR21E”) to separate the precipitate (acetone insoluble component) and the acetone solution (acetone soluble component). The precipitate (acetone insoluble component) was then dried to measure its mass (Y(g)), and the graft ratio was calculated from the following formula (1). In the formula (1), Y is the mass (g) of the acetone insoluble component of the polypropylene-based graft polymer, X is the total mass (g) of the polypropylene-based graft polymer used to determine Y, and the particle mass fraction is the content of the polypropylene-based resin particles (C) in the polypropylene-based graft polymer in terms of solid content. Graft rate (%) = {(YX×particle mass fraction) / X×particle mass fraction}×100...(1)

[0078] <Melt mixing> The resin components were mixed according to the resin component composition shown in Table 1, and melt-kneaded in a 30 mmφ vacuum vented twin-screw extruder (Ikegai Corporation's "PCM30") at a cylinder temperature of 200 to 260°C and a vacuum of 93.325 kPa to obtain a transparent thermoplastic resin composition. After melt-kneading, the mixture was pelletized using a pelletizer (Soken Corporation's "SH-type pelletizer").

[0079] <Melt Volume Rate (MVR) Measurement> The MVR of the thermoplastic resin composition obtained by melt kneading was measured at 220° C. and 10 kgf in accordance with ISO 1133. The MVR is an index of the fluidity of a thermoplastic resin composition.

[0080] <Injection molding 1 (physical property evaluation)> The pellets of the thermoplastic resin composition obtained by melt kneading were molded into a molded product with a length of 80 mm, a width of 10 mm and a thickness of 4 mm using an injection molding machine (Toshiba Machine Co., Ltd.'s "IS55FP-1.5A") at a cylinder temperature of 200 to 270°C and a mold temperature of 60°C, to obtain molded product 1 for physical property measurement. Separately, 100 parts of the thermoplastic resin composition pellets and 0.8 parts of carbon black were mixed using a Henschel mixer, and this mixture was fed into an extruder heated to 240°C and kneaded to obtain black pellets. These black pellets were then molded in the same manner as above to obtain molded product 2 for appearance evaluation.

[0081] <Injection molding 2 (two-color molding)> First, homopolypropylene resin (FY4 manufactured by Japan Polypropylene Corporation) was used to mold a plate measuring 100 mm in length, 100 mm in width, and 1 mm in thickness using an injection molding machine (Toshiba Machine Co., Ltd.'s "IS55FP-1.5A") at a cylinder temperature of 200 to 270°C and a mold temperature of 60°C. Next, the above plate was fixed in a mold measuring 100 mm in length, 100 mm in width, and 3 mm in thickness, and pellets of the thermoplastic resin composition obtained by melt kneading were injection molded to create a two-color molding evaluation sample in which a layer of the thermoplastic resin composition obtained by melt kneading was adhered to one side of a homopolypropylene resin plate.

[0082] <Injection molding 3 (molded products for painting)> Using an injection molding machine (Toshiba Machine Co., Ltd.'s "IS55FP-1.5A"), a cylinder temperature of 200 to 270°C and a mold temperature of 60°C were used to mold a plate 100 mm long, 100 mm wide and 3 mm thick, which was used as the molded product 3 to be painted.

[0083] <Density measurement> The density of the molded product 1 obtained by injection molding 1 was measured in accordance with the ISO1183 standard.

[0084] <Charpy impact strength measurement> The molded product 1 obtained by the injection molding 1 was subjected to a Charpy impact test (with a notch) at 23° C. according to the ISO 179 standard to measure the Charpy impact strength.

[0085] <Measurement of deflection temperature under load> For the molded product 1 obtained by injection molding 1, the deflection temperature under load (HDT) (° C.) was measured by the edgewise method according to the ASTM D648 standard.

[0086] <Hardness measurement> For the molded product 1 obtained by injection molding 1, the Rockwell hardness was measured according to ISO2039.

[0087] <Appearance evaluation of molded products> The molded product 2 obtained by the injection molding 1 was visually evaluated, and the evaluation results were as follows. None: No defects in molding appearance, no practical problems. Peeling: Peeling has occurred on the surface of the molded product, making it unusable. Surface unevenness: The surface of the molded product is uneven, making it unusable.

[0088] Moreover, the following measurements were carried out on this molded product 2.

[0089] (Evaluation of color development) The lightness L* of the molded product 2 obtained by injection molding 1 was measured by the SCE method using a spectrophotometer (Konica Minolta Optips "CM-3500d"). The measured L* was designated as "L* (ma)". The lower the L*, the blacker the color, and the better the color development. "Lightness L*" refers to the lightness value (L*) among the color values ​​in the L*a*b* color system adopted in JIS Z8729. The "SCE method" refers to a method of measuring color using a spectrophotometer conforming to JIS Z8722 and eliminating specular reflected light using a light trap.

[0090] (Measurement of surface gloss) For the molded product 2 obtained by injection molding 1, the reflectance (%) of the molded product surface at an incident angle of 60° and a reflection angle of 60° was measured in accordance with JIS K7105 using a "Digital Variable Gloss Meter UGV-5D" manufactured by Suga Test Instruments Co., Ltd. Higher reflectance indicates better surface appearance.

[0091] <Appearance evaluation of two-color molded products> The appearance of the two-color molding evaluation sample obtained in injection molding 2 was visually observed from the homopolypropylene resin side and evaluated according to the following criteria. ○: The entire surface is in close contact and no air gaps are visible. △: Almost the entire surface is in contact, but there are air pockets in the areas where the surface is not in contact. ×: Not tightly attached, air gaps visible over almost the entire surface

[0092] <Adhesion strength evaluation of two-color molded products> The two-color molding evaluation sample obtained in injection molding 2 was cut into a width of 22 mm along the resin flow direction. The adhesive surface between the homopolypropylene resin plate and the thermoplastic resin composition layer was peeled off by about 20 mm with a cutter knife, and the homopolypropylene resin plate was folded so as to be perpendicular to the plate. Using a Strograph VE50 manufactured by Toyo Seiki Seisakusho, the folded part of the homopolypropylene resin plate was clamped using a free gripping jig, and a tensile test was performed at 5 mm / min so as to be perpendicular to the plate, and the maximum value of the tensile force between a displacement of 2 to 6 mm was taken as the adhesion strength. The higher this adhesion strength, the better the adhesion strength.

[0093] <Evaluation of Paint Appearance> The molded article 3 for painting obtained by injection molding 3 was spray-painted with a urethane paint and evaluated according to the following criteria. ◯: No irregularities were observed on the surface of the molded article, and no practical problems were observed. ×: The molded article surface was uneven all over, and did not reach a practical level.

[0094] <Polypropylene resin (A)> As the polypropylene resin (A), the following was used. Prime Polymer Co., Ltd.: Propylene random copolymer "Prime Polypro J229E" MFR: 50g / 10min (230℃ / load 50N)

[0095] <Acid-modified polyolefin resin (B)> The following was used as the acid-modified olefin polymer (B). Mitsui Chemicals: Maleic anhydride modified polypropylene "Hiwax NP0555A" Maleic anhydride graft amount: 3% by mass Acid value: 45mgKOH / g

[0096] <Production of Polypropylene Resin Particles (C)> 100 parts of polypropylene resin (A), 20 parts of acid-modified olefin polymer (B), and 5 parts of potassium oleate as an anionic emulsifier were mixed. This mixture was fed at 4 kg / h from the hopper of a twin-screw extruder (manufactured by Ikegai Corporation, "PCM30", L / D=40), and was heated to 220°C, melt-kneaded, and extruded while continuously feeding an aqueous solution of 0.63 parts of potassium hydroxide and 3.87 parts of ion-exchanged water from a feed port provided at the vent of the twin-screw extruder. The melt-kneaded product was continuously fed to a cooling device attached to the tip of the twin-screw extruder and cooled to 90°C. The solid discharged from the tip of the twin-screw extruder was then poured into 80°C warm water, continuously dispersed, and diluted to a solid concentration of about 40%, to obtain an aqueous dispersion of polypropylene-based resin particles (C). The volume average particle diameter of this polypropylene-based resin particles (C) was 500 nm.

[0097] <Production of polypropylene-based graft polymer> In a stainless steel polymerization tank equipped with a stirrer, 60 parts of the aqueous dispersion of polypropylene-based resin particles (C) was placed as solids, ion-exchanged water was added so that the solids concentration became 30%, 0.008 parts of ferrous sulfate, 0.35 parts of sodium pyrophosphate, and 0.35 parts of fructose were charged, and the temperature was adjusted to 80° C. 30 parts of styrene, 10 parts of acrylonitrile, and 0.62 parts of cumene hydroperoxide were continuously added for 150 minutes, and emulsion polymerization was carried out while maintaining the polymerization temperature at 80° C., to obtain an aqueous dispersion containing a polypropylene-based graft polymer having a volume average particle diameter of 510 nm. An antioxidant was added to the aqueous dispersion containing this polypropylene-based graft polymer, and the solid content was precipitated with sulfuric acid. After undergoing the steps of washing, dehydration, and drying, a powdery polypropylene-based graft polymer was obtained. When the graft ratio of this polypropylene-based graft polymer was measured, it was 30%. Since no organic solvent was used in this powdery polypropylene-based graft polymer, there was no solvent odor.

[0098] <Manufacture of ABS Resin> 50 parts of polybutadiene (gel content 94%, average particle diameter 290 nm), 35 parts of styrene, 15 parts of acrylonitrile (5% in the monomer component), 0.1 part of t-dodecyl mercaptan, 1.0 part of sodium rosinate, 0.05 part of potassium hydroxide, and 160 parts of pure water were charged into a reactor. After heating to 60°C and impregnating for 60 minutes, 0.3 part of t-hexyl peroxypivalate was added, and the temperature was raised to 75°C and polymerization was carried out for 2 hours. An antioxidant was added to the obtained latex, which was then poured into an aqueous calcium chloride solution for coagulation, followed by washing, dehydration, and drying to obtain an ABS resin.

[0099] <Manufacture of AS Copolymer> 120 parts of ion-exchanged water, 0.1 part of polyvinyl alcohol, 0.3 part of azobisisobutyronitrile, 30 parts of acrylonitrile, 70 parts of styrene, and 0.35 part of t-dodecyl mercaptan were charged into a stainless steel polymerization tank equipped with a stirrer with nitrogen substitution. The reaction was carried out at an initial temperature of 60°C for 5 hours. After raising the temperature to 120°C and reacting for 4 hours, the content was taken out, washed, and dried to obtain a powdery AS copolymer.

[0100] [Example 1] Polypropylene graft polymer, ABS resin and AS copolymer were mixed in the amounts shown in Table 1, and melt-kneaded in a 30 mmφ vacuum vented twin screw extruder (Ikegai Corporation's "PCM30") at a cylinder temperature of 200 to 260°C and a vacuum of 93.325 kPa to obtain a transparent thermoplastic resin composition. The content of the polypropylene resin component in the obtained thermoplastic resin composition was 5 mass%. After melt-kneading, the mixture was pelletized using a pelletizer (Soken Corporation's "SH type pelletizer"). The pellets thus obtained were cylindrical with a diameter of 3 mm and a length of 3 mm, and each pellet weighed 21 mg.

[0101] [Examples 2 to 4] Pellets of thermoplastic resin compositions were obtained in the same manner as in Example 1, except that the resin component formulation was as shown in Table 1. The content of the polypropylene resin component in the obtained thermoplastic resin composition was 5 mass% in Example 2, 20 mass% in Example 3, and 30 mass% in Example 4.

[0102] [Comparative Examples 1 and 2] Pellets of thermoplastic resin compositions were obtained in the same manner as in Example 1, except that polypropylene resin (A) was used instead of the polypropylene-based graft polymer, and the resin component blending was as shown in Table 1. The content of the polypropylene resin component in the obtained thermoplastic resin composition was 5 mass% in Comparative Example 1 and 20 mass% in Comparative Example 2.

[0103] [Comparative Example 3] Pellets of a thermoplastic resin composition were obtained in the same manner as in Example 1, except that no polypropylene-based graft polymer was used and the resin components were blended as shown in Table 1.

[0104] The specific gravity and MVR were measured for each of the pellets of Examples 1 to 4 and Comparative Examples 1 to 3. In addition, the pellets of the thermoplastic resin composition were molded into various molded articles and the above-mentioned evaluations were carried out. The results are shown in Table 1.

[0105] [Table 1]

[0106] From Table 1, we can see the following: According to Examples 1 to 4, although the impact strength tends to be lower than that of the ABS resin / AS copolymer composition of Comparative Example 3, it is clear that there is no problem with the appearance even if the polypropylene resin component content is high. In contrast to this, in Comparative Examples 1 and 2 in which polypropylene resin (A) was blended in place of the polypropylene-based graft polymer, the impact strength was significantly reduced and the appearance was also poor. Moreover, the two-color molded products of Examples 1 to 4 are also excellent in appearance and adhesive strength. On the other hand, Comparative Example 1 has poor adhesion strength and appearance, and Comparative Example 2 has good adhesion strength and appearance, but as described above, has poor impact strength and appearance by itself. In Comparative Example 3, the two-color molded product did not have sufficient adhesive strength and also had a poor appearance. [Industrial Applicability]

[0107] The molded article of the present invention obtained by molding the thermoplastic resin composition of the present invention containing the polypropylene-based graft polymer of the present invention has excellent impact resistance and appearance, and can also obtain high adhesion strength and good appearance even in two-color molding with a polypropylene-based resin. Therefore, the molded article can be suitably used for vehicle exterior / interior parts, building material parts such as wall materials and window frames, tableware, toys, home appliance parts such as vacuum cleaner housings, television housings and air conditioner housings, interior parts, ship parts, and communication device housings, etc.

Claims

1. A polypropylene-based graft polymer obtained by graft polymerizing a vinyl-based monomer (D) onto polypropylene-based resin particles (C) having a volume average particle size of 50 to 850 nm, the polypropylene-based graft polymer comprising 100 parts by mass of a polypropylene resin (A) and 5 to 25 parts by mass of an acid-modified olefin resin (B), The polypropylene resin (A) contains 80 to 100 mol % of propylene units in all constitutional units, A polypropylene-based graft polymer, in which 100% by mass of the vinyl-based monomer (D) is an aromatic vinyl compound, 10 to 50% by mass of a vinyl cyanide compound, and 0 to 30% by mass of another vinyl-based monomer copolymerizable therewith.

2. The polypropylene-based graft polymer according to claim 1, wherein the graft ratio of the polypropylene-based graft polymer is 10 to 70 mass%.

3. The polypropylene-based graft polymer according to claim 1 or 2, which is obtained by graft polymerization of 20 to 70 mass% of a vinyl-based monomer (D) (the total of the polypropylene-based resin particles (C) and the vinyl-based monomer (D) is 100 mass%) in the presence of 30 to 80 mass% of a polypropylene-based resin particle (C).

4. The polypropylene-based resin particles (C) are obtained by melt-kneading the polypropylene resin (A) and the acid-modified olefin resin (B) and dispersing the resulting kneaded mixture in an aqueous medium. The polypropylene-based graft polymer according to any one of claims 1 to 3.

5. A thermoplastic resin composition comprising the polypropylene-based graft polymer according to any one of claims 1 to 4.

6. The thermoplastic resin composition according to claim 5, wherein the content of the polypropylene-based graft polymer is 3 to 70% by mass in 100% by mass of all resin components contained in the thermoplastic resin composition.

7. A molded article obtained by molding the thermoplastic resin composition according to claim 5 or 6.

8. 7. A two-color molded product obtained by two-color molding of the thermoplastic resin composition according to claim 5 or 6 and a polypropylene resin.

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