Thermoplastic resin composition and molded article

Abstract

To provide a thermoplastic resin composition which is excellent in mechanical strength, flowability and quietness, especially, impact strength and durability of quietness when exposed at high temperatures for a long time, and a molded article of the same.SOLUTION: There are provided a thermoplastic resin composition which is obtained by blending 1-5 pts.wt. of an α-olefin oligomer and / or a cooligomer of ethylene and α-olefin (C) with 100 pts.wt. of a thermoplastic resin composition containing 10-50 pts.wt. of a styrene resin (A) and 50-90 pts.wt. of a polycarbonate resin (B) when the total of the styrene resin (A) and the polycarbonate resin (B) is 100 pts.wt, and has kinetic viscosity at 100°C of the component (C) of 30 cSt or more; and a molded article of the same.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic resin composition having excellent mechanical strength, fluidity and quietness (creak noise suppression effect), and a resin molded article. [Background technology]

[0002] Polymer alloys, which are blends of ABS resin, which is made by polymerizing diene rubber polymers, aromatic vinyl monomers, vinyl cyanide monomers, methacrylate ester monomers, etc., with polycarbonate (PC) resin, have excellent impact resistance, moldability, and appearance, and are widely used in a variety of applications, including automobile parts, office equipment, home appliances, gaming machine parts, and general merchandise.

[0003] In recent years, automotive interior components, such as console panels, dashboards, car navigation systems, air conditioners, and other products, are manufactured by fitting together and assembling molded resin parts to reduce weight. For example, when these components have a housing structure, fitting portions for fitting are typically molded integrally at various locations on upper and lower halves of a container-like molded part, and the housing molded product is manufactured by fitting the outer edges of the upper and lower molded parts together using almost no or minimal screws.

[0004] Meanwhile, previously reported techniques for improving sliding properties include a method of blending an α-olefin oligomer and / or an ethylene and α-olefin co-oligomer into a resin composition made of ABS resin (see Patent Document 1), and a method of blending an α-olefin lubricant into a polyacetal resin (see Patent Document 2).Also previously reported techniques for improving noise reduction include a method of blending an ethylene-vinyl acetate copolymer into a resin composition made of PC resin and ABS resin (see Patent Document 3), and a method of blending an ethylene-vinyl acetate copolymer and oxidized polyethylene wax into a resin composition made of PC resin and ABS resin (see Patent Document 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 10-204252 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-29713 [Patent Document 3] Japanese Patent Application Publication No. 2019-199602 [Patent Document 4] Japanese Patent Application Publication No. 2018-141078 Summary of the Invention [Problem to be solved by the invention]

[0006] When a molded housing, obtained by fitting the outer edges of upper and lower molded parts, is installed in a vehicle, the temperature inside the vehicle fluctuates drastically from low to high. The thermal fluctuations can easily cause deformation in the molded plastic parts due to contraction and expansion. Even slight deformation at the fitting points can easily cause squeaking noises due to vibrations while the vehicle is in motion. Squeaking noises significantly reduce passenger comfort, and luxury cars, in particular, require even higher levels of interior quietness, making squeaking noise prevention an extremely important issue. Squeaking noises occur when components rub against each other. Effective methods for preventing or reducing squeaking noises include applying grease or fluororesin to the surface of the molded part. However, this method is difficult to automate and requires manual labor. Furthermore, the effect is short-lived, making it a non-permanent solution. Therefore, technology to impart quietness (to prevent squeaking noises) to resins is needed.

[0007] Furthermore, in recent years, these resin molded products have become thinner in order to reduce their weight, and therefore they are required to have high fluidity for molding and high impact strength even in a thin-walled state, and technologies for improving fluidity and impact strength have been developed.

[0008] Methods to improve noise reduction have included applying grease to parts or attaching nonwoven fabric, but there were issues with volatile organic compounds (VOCs) being generated during the manufacturing process and from the assembled product, as well as the difficulty of automating the process, which increases manufacturing costs, so improvements were needed.

[0009] Conventional methods proposed for imparting noise-reducing properties to thermoplastic resin compositions are insufficient in terms of the required high level of noise-reducing properties, their sustainability, and mechanical properties, and further improvements are required.

[0010] Therefore, an object of the present invention is to solve the problems of the prior art and to provide a thermoplastic resin composition having excellent mechanical strength, fluidity, and quietness, particularly excellent impact strength and the durability of quietness when exposed to high temperatures for a long period of time, and a molded article made from the same. [Means for solving the problem]

[0011] As a result of intensive research to solve these problems, the present inventors discovered that by blending an α-olefin oligomer and / or an ethylene and α-olefin co-oligomer having a specific kinematic viscosity into a thermoplastic resin composition, it is possible to obtain a resin composition and a molded article thereof that have excellent mechanical strength, fluidity, and sustained quietness, and this led to the present invention.

[0012] That is, the present invention has the following configuration. (1) The total of the styrene resin (A) and the polycarbonate resin (B) is 100 parts by weight. 40 50 parts by weight of polycarbonate resin (B) 60 A thermoplastic resin composition comprising 100 parts by weight of a thermoplastic resin composition containing 1 to 5 parts by weight of an α-olefin oligomer and / or an ethylene and α-olefin co-oligomer (C), wherein the kinematic viscosity of component (C) at 100°C is 30 cSt or more. (2) The thermoplastic resin composition according to (1), which contains 1 to 3 parts by weight of component (C) relative to 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B). (3) The thermoplastic resin composition according to (1) or (2), further comprising 1 to 5 parts by weight of an ethylene-vinyl acetate copolymer (D) having a styrene-based (co)polymer segment, based on 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B). (4) The thermoplastic resin composition according to (3), which contains 1 to 3 parts by weight of component (D) relative to 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B). (5) A molded article made of the thermoplastic resin composition according to any one of (1) to (4). [Effects of the Invention]

[0013] According to the present invention, a thermoplastic resin composition having excellent mechanical strength, fluidity and long-lasting quietness can be obtained, and the composition can be used for automobile parts, office automation equipment, home appliances, general merchandise and the like. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below with reference to embodiments. The thermoplastic resin composition of the present invention is a styrene-based resin (A) containing 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B). 40 50 parts by weight of polycarbonate resin (B) 60 The thermoplastic resin composition is characterized in that it is obtained by blending 1 to 5 parts by weight of an α-olefin oligomer and / or an ethylene and α-olefin co-oligomer (C) with 100 parts by weight of a thermoplastic resin composition containing 100 parts by weight of an α-olefin co-oligomer, and that the kinematic viscosity of component (C) at 100°C (measured according to JIS K2833 (2000)) is 30 cSt or more.

[0015] The styrene-based resin (A) used in the present invention is a polymer containing an aromatic vinyl-based monomer as a component. Examples of the aromatic vinyl-based monomer include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, t-butylstyrene, o-ethylstyrene, o-chlorostyrene, and o,p-dichlorostyrene, with styrene and α-methylstyrene being preferred. The aromatic vinyl-based monomer may be used alone or in combination of two or more.

[0016] Furthermore, the styrene-based resin (A) may contain a vinyl copolymer obtained by copolymerizing an aromatic vinyl-based monomer with another vinyl-based monomer copolymerizable with the aromatic vinyl-based monomer, in order to impart properties such as chemical resistance and heat resistance. Examples of these other vinyl monomers include acrylonitrile, methacrylonitrile, ethacrylonitrile, (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, t-butyl (meth)acrylate, n-hexyl (meth)acrylate, glycidyl (meth)acrylate, allyl glycidyl ether, styrene-p-glycidyl ether, p-glycidylstyrene, 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth)acrylate, 2,3,4,5-tetrahydroxypentyl acrylate, maleic acid, maleic anhydride, maleic acid monoethyl ester, itaconic acid, itaconic anhydride, Examples of suitable acrylates include phthalic acid, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, acrylamide, methacrylamide, N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, aminoethyl acrylate, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, phenylaminoethyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, p-aminostyrene, 2-isopropenyloxazoline, 2-vinyloxazoline, 2-acryloyloxazoline, and 2-styryloxazoline. Among these, acrylonitrile and methyl methacrylate are particularly preferred.

[0017] The proportion of the aromatic vinyl monomer contained in the styrene resin (A) is preferably 10 to 100 parts by weight, more preferably 20 to 90 parts by weight, from the viewpoint of moldability.

[0018] In order to maintain a balance of physical properties, the polystyrene-equivalent weight average molecular weight of the styrene resin (A) is preferably 50,000 to 300,000. The weight average molecular weight can be measured by a commonly known method such as gel permeation chromatography (GPC).

[0019] The method for producing the styrene resin (A) is not particularly limited, and any conventional production method such as bulk polymerization, suspension polymerization, emulsion polymerization, bulk-suspension polymerization, etc. Alternatively, the styrene resin (A) may be produced by melt-kneading one or more styrene resins obtained by any of these methods.

[0020] When the objective is to dramatically improve the impact resistance and other properties of the styrene-based resin (A), it is preferable to use a rubber-modified styrene-based resin in which a rubbery polymer is dispersed in a matrix of an aromatic vinyl (co)polymer. That is, a rubber-modified styrene-based resin containing a graft copolymer obtained by graft polymerizing an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer onto a rubbery polymer can be preferably used as the styrene-based resin. Also preferred are vinyl copolymers obtained by copolymerizing an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer, and rubber-modified styrene-based resins containing a graft copolymer obtained by graft polymerizing an aromatic vinyl monomer and another vinyl monomer copolymerizable with the aromatic vinyl monomer onto a rubbery polymer.

[0021] In the present invention, when the term "(co)polymer" is used as mentioned above, it means a polymer and / or a copolymer.

[0022] Examples of rubbery polymers include diene rubbers such as polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, styrene-butadiene block copolymer, and butyl acrylate-butadiene copolymer, acrylic rubbers such as polybutyl acrylate, polyisoprene, and ethylene-propylene-diene terpolymers, among which polybutadiene and butadiene copolymers are preferably used.

[0023] From the viewpoint of excellent impact resistance, the rubber polymer is preferably rubber particles having an average particle size in the range of 0.15 to 0.60 μm, more preferably rubber particles having an average particle size in the range of 0.2 to 0.55 μm. Among them, a rubber polymer having a weight ratio of rubber particles having an average particle size in the range of 0.20 to 0.25 μm to rubber particles having an average particle size in the range of 0.50 to 0.65 μm of 90:10 to 60:40 is particularly preferred, because it has remarkably excellent impact resistance and falling weight impact resistance of thin-walled molded products.

[0024] Here, the weight average particle size of the rubber particles can be measured by the method described in "Rubber Age, Vol. 88, pp. 484-490, (1960), by E. Schmidt, P.H. Biddison," which determines the particle size at a cumulative weight fraction of 50% from the cumulative weight fraction of sodium alginate concentration.

[0025] When the above-mentioned rubber-modified styrene resin is used as the styrene resin (A), the rubbery polymer is incompatible with the matrix styrene resin, so impact resistance can be further improved by graft polymerizing a component compatible with the matrix onto the rubbery polymer. That is, it is preferable to use a graft copolymer in which an aromatic vinyl monomer or a monomer mixture is graft polymerized onto the rubbery polymer. As the monomers used in the graft polymerization, it is preferable to use the same monomer components in the same ratio as the monomer components in the matrix aromatic vinyl (co)polymer.

[0026] The composition and graft amount are preferably adjusted so as not to impair the dispersibility of the rubber polymer. The graft ratio is preferably 5 to 200%, more preferably 20 to 100%. The graft ratio here is a value calculated by the following formula: Graft ratio = Amount of vinyl copolymer grafted onto rubber polymer ÷ Rubber content of graft copolymer × 100

[0027] Regarding the properties of the non-graft-polymerized (co)polymer, from the viewpoint of obtaining a resin composition having excellent impact resistance, the intrinsic viscosity [η] (measured at 30°C) of the methyl ethyl ketone-soluble matter is preferably in the range of 0.25 to 0.60 dL / g, more preferably in the range of 0.25 to 0.50 dL / g.

[0028] Specifically, a method for producing a rubber-modified styrene-based resin is industrially and economically suitable, in which a graft copolymer obtained by graft polymerizing a monomer or a monomer mixture containing an aromatic vinyl monomer onto a rubber polymer, and a styrene-based (co)polymer obtained by polymerizing a monomer or a monomer mixture containing an aromatic vinyl monomer are melt-kneaded to produce the rubber-modified styrene-based resin.

[0029] The graft copolymer contained in the rubber-modified styrene-based resin can be obtained by known polymerization methods such as emulsion polymerization, bulk polymerization, etc. Among them, a method of emulsion polymerization in which a mixture of a monomer or a monomer mixture, a radical generator, and a chain transfer agent is continuously supplied to a polymerization vessel in the presence of a rubber polymer latex is preferred from the viewpoint of operation.

[0030] Specific examples of the styrene-based resin (A) used in the present invention include polystyrene, high-impact polystyrene, AS resin, AAS resin, AES resin, ABS resin, MAS resin, MS resin, MABS resin, and MBS resin, as well as alloys of these resins with other resins.

[0031] The blending ratio of the styrene resin (A) used in the present invention is 10 to 50 parts by weight, more preferably 25 to 50 parts by weight, based on 100 parts by weight of the total of the styrene resin (A) and the polycarbonate resin (B). If the styrene resin (A) is less than 10 parts by weight, the proportion of the polycarbonate resin (B) will be high, which tends to result in poor fluidity. If the styrene resin (A) is more than 50 parts by weight, the proportion of the polycarbonate resin (B) will be low, which tends to result in poor impact resistance.

[0032] The polycarbonate resin (B) used in the present invention may suitably be an aromatic polycarbonate resin, an aliphatic polycarbonate resin, or an aliphatic-aromatic polycarbonate resin, which may be used alone or in combination of two or more. Aromatic polycarbonate resins, which have an excellent balance of mechanical properties, are particularly preferred.

[0033] Examples of aromatic polycarbonate resins include those with a bisphenol A skeleton as shown below, as well as those with a bisphenol S skeleton.

[0034] Commercially available polycarbonate resins (B) include polycarbonate resins "Panlite" (registered trademark) 1250WP manufactured by Teijin Chemicals Co., Ltd., and polycarbonate resins "Toughlon" (registered trademark) A2200, FN2200, and A1900 manufactured by Idemitsu Kosan Co., Ltd.

[0035] The method for producing the polycarbonate resin (B) is not particularly limited, and known methods can be used. For example, to produce a polycarbonate of 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), a phosgene method can be used in which 2,2-bis(4-hydroxyphenyl)propane is used as a dioxy compound and phosgene is blown into the compound in the presence of an aqueous caustic alkali solution and a solvent.

[0036] The polycarbonate resin (B) preferably has a viscosity average molecular weight in the range of 10,000 to 40,000, particularly in the range of 15,000 to 30,000. If the viscosity average molecular weight is less than 10,000, the mechanical properties tend to be reduced, and if the viscosity average molecular weight exceeds 40,000, the moldability tends to be poor.

[0037] The viscosity average molecular weight (Mv) of the polycarbonate resin (B) can be determined by measuring the intrinsic viscosity (intrinsic viscosity) in methylene chloride at 20° C. and using the following Mark-Houwink viscosity formula. Intrinsic viscosity [η]=K(Mv)a (In the formula, K=1.23×10 -4 , a=0.83)

[0038] Monomers used in the α-olefin oligomer and / or ethylene and α-olefin co-oligomer (C) used in the present invention include ethylene and α-olefins having 3 to 20 carbon atoms, such as propylene, 1-butene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1-tetradecene, 1-hexadecene, 1-octadecene, and 1-eicosene.

[0039] The α-olefin oligomer and / or ethylene and α-olefin co-oligomer (C) are commercially available and can be selected from the "Lucant (registered trademark)" series manufactured by Mitsui Chemicals, Inc., for example.

[0040] From the viewpoints of quietness and productivity, the α-olefin oligomer and / or ethylene and α-olefin co-oligomer (C) used in the present invention preferably has a kinematic viscosity at 100°C of 30 to 1000 cSt. A kinematic viscosity at 100°C of less than 30 cSt tends to result in insufficient quietness, while a kinematic viscosity at 100°C of more than 1000 cSt tends to result in reduced productivity when mixing the resin composition. The kinematic viscosity at 100°C can be measured for each α-olefin oligomer and / or ethylene and α-olefin co-oligomer (C) used in the present invention, but if products under the trade name "Lucant (registered trademark)" series manufactured by Mitsui Chemicals, Inc. are used, the kinematic viscosity at 100°C for each product is clearly stated as a catalog value.

[0041] The thermoplastic resin composition according to the present invention may further contain an α-olefin oligomer and / or an ethylene and α-olefin cooligomer (C). The content of the α-olefin oligomer and / or ethylene and α-olefin cooligomer (C) used in the present invention is 1 to 5 parts by mass, more preferably 1 to 4 parts by mass, and even more preferably 1 to 3 parts by mass, per 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B). If the amount is less than 1 part by weight, sufficient quietness tends to be insufficient. If the amount is more than 5 parts by weight, rigidity and heat resistance tend to decrease, and mold contamination and the appearance of the molded article tend to deteriorate.

[0042] The ethylene-vinyl acetate copolymer (D) having a styrene-based (co)polymer segment used in the present invention is not limited as long as it is a copolymer consisting of a styrene-based (co)polymer portion (segment) and an ethylene-vinyl acetate copolymer portion (segment), but is preferably a graft copolymer consisting of a styrene-based (co)polymer segment and an ethylene-vinyl acetate copolymer segment, and more preferably a graft copolymer having an ethylene-vinyl acetate copolymer main chain and a styrene-based (co)polymer segment as a side chain.

[0043] The proportion of vinyl acetate units in the ethylene-vinyl acetate copolymer is preferably 1 to 20% by mass, more preferably 3 to 10% by mass.

[0044] The styrene-based (co)polymer segment is a homopolymer of a styrene-based monomer or a copolymer with another vinyl-based monomer. Examples of styrene-based monomers include styrene, methylstyrene, dimethylstyrene, ethylstyrene, isopropylstyrene, and chlorostyrene, with styrene being particularly preferred. Preferred examples of other vinyl-based monomers include vinyl cyanide monomers; glycidyl esters of acrylic acid or methacrylic acid; and alkyl esters of acrylic acid or methacrylic acid. Examples of vinyl cyanide monomers include acrylonitrile and methacrylonitrile, with acrylonitrile being particularly preferred. Examples of glycidyl esters of acrylic acid or methacrylic acid include glycidyl esters of acrylic acid and glycidyl esters of methacrylic acid, with glycidyl esters of methacrylic acid being preferred. The alkyl ester of acrylic acid or methacrylic acid is preferably an alkyl ester having 1 to 8 carbon atoms, and examples thereof include methyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, etc. As the other vinyl monomer, among the above, glycidyl ester of acrylic acid or methacrylic acid and vinyl cyanide monomer are preferred, glycidyl ester of acrylic acid or methacrylic acid are more preferred, and glycidyl ester of methacrylic acid is particularly preferred.

[0045] The contents of the styrene-based monomer and other vinyl-based monomer in the styrene-based (co)polymer segment are not particularly limited, but the content of the styrene-based monomer is preferably 50 to 100 parts by mass based on 100 parts by mass of the total of the styrene-based monomer and other vinyl-based monomer. Furthermore, the content of the styrene-based (co)polymer segment is preferably 10 to 50 parts by mass, assuming that the entire ethylene-vinyl acetate copolymer (D) is 100% by mass.

[0046] The ethylene-vinyl acetate copolymer (D) having a styrene-based (co)polymer segment can be produced by various known methods, including a preferred method in which a styrene-based monomer or other vinyl-based monomer and a radical-polymerizable organic peroxide are mixed into an aqueous suspension of an ethylene-vinyl acetate copolymer to which a suspending agent has been added, and the mixture is heated and stirred to impregnate the ethylene-vinyl acetate copolymer with the above components, and then the mixture is heated to polymerize.

[0047] Furthermore, the ethylene-vinyl acetate copolymer (D) having a styrene-based (co)polymer segment is commercially available, and can be obtained by selecting from, for example, the "Modiper (registered trademark)" series of products manufactured by NOF Corporation.

[0048] The content of the ethylene-vinyl acetate copolymer (D) having a styrene (co)polymer segment is preferably 1 to 5 parts by weight, more preferably 1 to 4 parts by weight, and even more preferably 1 to 3 parts by weight, based on 100 parts by weight of the total of the styrene resin (A) and the polycarbonate resin (B). If the content is less than 1 part by weight, the squeak noise suppression effect tends to decrease, while if it exceeds 5 parts by weight, the impact resistance, heat resistance, and mold contamination during molding tend to be poor.

[0049] The thermoplastic resin composition of the present invention can be produced by any method without particular limitation, for example, by melt-kneading using a Banbury mixer, roll, extruder, kneader, etc. However, from the viewpoint of dispersibility of the blended components, it is preferable to use a twin-screw extruder. The temperature during melt-kneading is usually about 200 to 300°C, although it depends on the blended components.

[0050] The molding method for the molded article made from the thermoplastic resin composition of the present invention can be any known method such as injection molding, extrusion molding, blow molding, vacuum molding, compression molding, gas-assisted molding, etc., and is not particularly limited, but is preferably injection molding. The injection molding temperature is preferably 230°C to 300°C from the viewpoint of moldability.

[0051] The thermoplastic resin composition of the present invention may be blended with various thermoplastic resin compositions within the scope of the present invention. For example, by blending polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins such as nylon 6 and nylon 6,6, modified PPE resins, polyacetal resins, or modified versions of these, plant-derived resins such as polylactic acid, and elastomers, the performance of the molded article can be further improved.

[0052] The thermoplastic resin composition of the present invention may contain various additives, such as antioxidants (e.g., hindered phenols, sulfur-containing organic compounds, and phosphorus-containing organic compounds), heat stabilizers (e.g., phenols and acrylates), UV absorbers (e.g., benzotriazoles, benzophenones, and salicylates), and light stabilizers (e.g., organonickel and hindered amines), lubricants (e.g., metal salts of higher fatty acids and higher fatty acid amides), plasticizers (e.g., phthalates and phosphates), halogen-containing compounds (e.g., polybrominated diphenyl ether, tetrabromobisphenol-A, brominated epoxy oligomers, and brominated polycarbonate oligomers), phosphorus-containing compounds, flame retardants and flame retardant aids (e.g., antimony trioxide), antistatic agents, carbon black, titanium oxide, pigments and dyes, and liquids (e.g., water and liquid paraffin), provided that the additives do not impair the effects of the present invention. The method of adding these additives is not particularly limited, and various methods can be used. [Example]

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0054] (1) Graft ratio A predetermined amount (m; approximately 1 gram) of the obtained graft copolymer was added to 200 ml of acetone and refluxed in a water bath at 70°C for 3 hours. The solution was centrifuged at 8,800 rpm (10,000 G) for 40 minutes, and the insoluble matter was then filtered. The obtained acetone-insoluble matter was dried under reduced pressure at 60°C for 5 hours, and its mass (m; units: grams) was measured. The graft ratio was calculated using the following formula: where L is the rubber content of the graft copolymer (a real number greater than 0 and less than 1). Grafting rate (mass%) = {[(n)-{(m) × L}] / [(m) × L]} × 100

[0055] (2) Weight average molecular weight The weight average molecular weight of the methyl ethyl ketone soluble portion of the obtained vinyl copolymer was measured as a polystyrene-equivalent weight average molecular weight using a gel permeation chromatography (GPC) apparatus manufactured by Water Corporation, a differential refractometer as a detector (Water 2414), MIXED-B columns (two manufactured by Polymer Laboratories), a distillate of tetrahydrofuran, a flow rate of 1 ml / min, and a column temperature of 40°C.

[0056] (3) Reduced viscosity 200 ml of acetone was added to 1 g of sample and refluxed for 3 hours. The solution was centrifuged at 8800 r / min (1000 G) for 40 minutes, and then the unnecessary material was filtered. The filtrate was concentrated using a rotary evaporator, and the precipitate was dried under reduced pressure at 60°C for 5 hours. The solution was then adjusted to 0.4 g / 100 ml (methyl ethyl ketone, 30°C). The reduced viscosity was measured using an Ubbelohde viscometer.

[0057] (4) MFR (Melt Flow Rate) The MFR was measured at 240°C and 98N in accordance with ISO1133:2011.

[0058] (5) Impact resistance The pellets obtained in each of the Examples and Comparative Examples were dried for 3 hours in a hot air dryer at 105°C, and then molded into multipurpose test pieces Type A1 as specified in JIS K 7139:2009 using an injection molding machine with a cylinder temperature set to 250°C and a mold temperature set to 60°C. Type B2 test pieces cut out from these were used to measure Charpy impact strength in accordance with ISO179:2010 / 1eA.

[0059] (6) Flexural modulus The pellets obtained in each of the Examples and Comparative Examples were dried for 3 hours in a hot air dryer at 105°C, and then molded into multipurpose test pieces Type A1 as specified in JIS K 7139:2009 using an injection molding machine with a cylinder temperature set to 250°C and a mold temperature set to 60°C. Type B2 test pieces cut out from these were used to measure the flexural modulus in accordance with ISO178.

[0060] (7) HDT (deflection temperature under load) The pellets obtained in each of the Examples and Comparative Examples were dried for 3 hours in a hot air dryer at 105°C, and then molded into multipurpose test pieces Type A1 as specified in JIS K 7139:2009 using an injection molding machine with a cylinder temperature set to 250°C and a mold temperature set to 60°C. Type B2 test pieces cut out from these were used to measure the deflection temperature under load at a load of 1.80 MPa in accordance with ISO75.

[0061] (8) Quietness The pellets obtained in each example and comparative example were dried for 3 hours in a hot air dryer at 105°C, and then molded into test pieces measuring 50 mm (length) x 25 mm (width) x 2 mm (thickness) and 80 mm x 80 mm x 2 mm using an injection molding machine with a cylinder temperature set to 250°C and a mold temperature set to 60°C. The 50 mm x 25 mm x 2 mm test pieces were deburred after molding.

[0062] The noise reduction was evaluated as the initial noise reduction by measuring the risk of abnormal noise when the above two test pieces were rubbed together under conditions of a load of 40N and a speed of 1mm / s using a Ziegler stick-slip measuring device SSP-04, and when they were rubbed together under conditions of a load of 40N and a speed of 20mm / s.The smaller the noise reduction risk value, the smaller the risk of squeaking noise generation, and the evaluation criteria are as follows: Noise risk score 1-3: Low risk of creaking noise Noise risk score 4-5: Slightly high risk of creaking noise Abnormal noise risk score 6-10: High risk of creaking noise.

[0063] Furthermore, as a test to simulate the aging of resin molded bodies, the above two types of test pieces for evaluating noise reduction were left standing in a hot air dryer at 80°C for 500 hours, and then left standing in a thermostatic chamber at 23°C x 50% RH for 24 hours, after which the risk value of abnormal noise was measured. This allowed the sustainability of noise reduction to be evaluated.

[0064] (9) Mold contamination The pellets obtained in each example and comparative example were dried for 3 hours in a hot air dryer at 105°C, and then molded 1000 times in succession into multipurpose test specimens type A1 as specified in JIS K 7139:2009 using an injection molding machine with a cylinder temperature set to 300°C and a mold temperature set to 60°C. Mold contamination was evaluated by visually observing the mold for contamination after molding. The evaluation criteria were as follows: ○: No cloudiness is observed on the mold design surface ×: Cloudiness is observed on the mold design surface

[0065] (10) Appearance (9) The appearance of 1,000 molded articles molded in the mold contamination evaluation was visually observed and evaluated. The evaluation criteria were as follows: ○ to △ were considered to be acceptable. ○: The percentage of molded products with appearance defects is less than 1% △: The percentage of molded products with appearance defects is 1% or more but less than 5% ×: The percentage of molded products with appearance defects is 5% or more.

[0066] (Reference Example 1) Preparation of styrene-based resin Preparation of graft copolymer (A-1) A nitrogen-purged reactor was charged with 120 parts by weight of purified water, 0.5 parts by weight of glucose, 0.5 parts by weight of sodium pyrophosphate, 0.005 parts by weight of ferrous sulfide, and 60 parts by weight (solids content equivalent) of polybutadiene latex (weight average particle size 0.3 μm, gel content 85%). The temperature inside the reactor was raised to 65°C with stirring. Polymerization began when the internal temperature reached 65°C. A mixture of monomers (30 parts by weight of styrene and 10 parts by weight of acrylonitrile) and 0.3 parts by weight of t-dodecyl mercaptan was continuously added dropwise over 5 hours. Simultaneously, an aqueous solution of 0.25 parts by weight of cumene hydroperoxide, 2.5 parts by weight of potassium oleate, and 25 parts by weight of purified water was continuously added dropwise over 7 hours to complete the reaction. The resulting styrene copolymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered, and dried to obtain graft copolymer A-1. The graft ratio of this styrene-based graft copolymer A-1 was 35%, and the reduced viscosity of the resin component was 0.35 dl / g.

[0067] (Reference Example 2) Preparation of vinyl copolymer (A-2) A monomer mixture consisting of 72% by weight of styrene and 28% by weight of acrylonitrile was suspension polymerized, and the resulting slurry was washed, dehydrated, and dried to prepare vinyl copolymer A-2. The weight-average molecular weight of the resulting vinyl copolymer A-2 was 100,000.

[0068] (Reference Example 3) Polycarbonate resin (B-1) "Iupilon (registered trademark)" S-2000 (viscosity average molecular weight 23,000) manufactured by Mitsubishi Engineering Plastics Corporation was used.

[0069] (Reference Example 4) α-Olefin Oligomer and / or Ethylene and α-Olefin Co-oligomer (C-1): Mitsui Chemicals "Lucant (registered trademark)" HC-10 (kinematic viscosity at 100 ° C. 10 cSt) (C-2): Mitsui Chemicals "Lucant (registered trademark)" HC-20 (kinematic viscosity at 100 ° C. 20 cSt) (C-3): Mitsui Chemicals "Lucant (registered trademark)" HC-40 (kinematic viscosity at 100 ° C. 40 cSt) (C-4): Mitsui Chemicals "Lucant (registered trademark)" HC-600 (kinematic viscosity at 100 ° C. 600 cSt) were used, respectively.

[0070] (Reference Example 5) Ethylene-vinyl acetate copolymer (D-1) having styrene-based (co)polymer segments NOF Corporation's "Modiper (registered trademark)" AS-100 (a graft copolymer with an ethylene-vinyl acetate copolymer main chain and a styrene polymer side chain) was used.

[0071] (Examples 1 to 6, Comparative Examples 1 to 9) The styrene resins (A-1) and (A-2), polycarbonate resin (B-1), oligomers (C-1) to (C-4), and copolymer (D-1) prepared in Reference Examples 1 to 5 above were blended in the blending ratios shown in Table 1 and mixed in a Henschel mixer at 23°C. The resulting mixture was then melt-kneaded in a co-rotating twin-screw extruder with a screw diameter of 30 mm (temperature range: 240 to 260°C) to obtain pellets. The resulting pellets were evaluated by the methods described above.

[0072] [Table 1] [Industrial Applicability]

[0073] The thermoplastic resin composition of the present invention has excellent mechanical strength, fluidity, and quietness, particularly excellent impact strength and the sustainability of quietness when exposed to high temperatures for a long period of time, and can therefore be suitably used for any molded product requiring these properties, particularly automobile parts, as well as office automation equipment, home appliances, general merchandise, etc.

Claims

1. A thermoplastic resin composition comprising 100 parts by weight of a thermoplastic resin composition containing 40 to 50 parts by weight of a styrene-based resin (A) and 50 to 60 parts by weight of a polycarbonate resin (B), where the total of the styrene-based resin (A) and the polycarbonate resin (B) is 100 parts by weight, and 1 to 5 parts by weight of an α-olefin oligomer and / or an ethylene and α-olefin co-oligomer (C), wherein the kinematic viscosity of component (C) at 100°C is 30 cSt or more.

2. 2. The thermoplastic resin composition according to claim 1, comprising 1 to 3 parts by weight of component (C) relative to 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B).

3. The thermoplastic resin composition according to claim 1 or 2, further comprising 1 to 5 parts by weight of an ethylene-vinyl acetate copolymer (D) having a styrene-based (co)polymer segment, based on 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B).

4. 4. The thermoplastic resin composition according to claim 3, comprising 1 to 3 parts by weight of component (D) relative to 100 parts by weight of the total of the styrene-based resin (A) and the polycarbonate resin (B).

5. A molded article made of the thermoplastic resin composition according to any one of claims 1 to 4.

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