Squeak-preventing thermoplastic resin composition and squeak-preventing molded article

Abstract

To provide a thermoplastic resin composition which is excellent in impact resistance, flowability and quietness, and durability of quietness, especially, 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 3-10 pts.wt. of a styrene-isobutylene block copolymer (C) with 100 pts.wt. of a thermoplastic resin composition containing 10-50 pts.wt. of a styrene resin (A) obtained by copolymerization of a monomer mixture containing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer 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 a molded article of the same.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic resin composition having excellent impact resistance, 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 noise reduction include a method of blending an ethylene-vinyl acetate copolymer with a resin composition consisting of a PC resin and an ABS resin (see Patent Document 1), and a method of blending an ethylene-vinyl acetate copolymer with a styrene-based elastomer having a polymer block containing a conjugated diene compound (see Patent Document 2). Also disclosed is a method of obtaining a resin composition with excellent impact resistance and vibration damping properties by blending an isobutylene-based block copolymer consisting of a polymer block mainly composed of isobutylene and a polymer block mainly composed of an aromatic vinyl monomer with a thermoplastic resin (see Patent Document 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-14447 [Patent Document 2] Japanese Patent Publication No. 2020-59827 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-112889 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. Thermal fluctuations can easily cause deformation in molded resin 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 molded parts. 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] Previously proposed methods for imparting noise-reducing properties to thermoplastic resin compositions, such as those disclosed in Patent Documents 1 and 2, are insufficient in terms of the required high level of noise-reducing properties, their sustainability, and mechanical properties, and further improvements are needed. Furthermore, while styrene-based elastomers, which are block copolymers, are generally known to have excellent vibration-damping properties, the structure and properties of styrene-based elastomers that are effective in preventing squeaks are unclear. Furthermore, Patent Document 3 does not specifically describe the vibration-damping improvement effect of incorporating an isobutylene-based block copolymer, and it is unclear whether isobutylene-based block copolymers are particularly effective in preventing squeaks.

[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 impact resistance, fluidity, and quietness, particularly excellent sustainability of quietness even 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 extensive research aimed at solving these problems, the present inventors discovered that by blending a styrene-isobutylene block copolymer into a thermoplastic resin composition, it is possible to obtain a resin composition and a molded article thereof that are excellent in impact resistance, fluidity, and sustained quietness, thereby completing the present invention.

[0012] That is, the present invention has the following configuration. (1) A thermoplastic resin composition characterized by comprising 100 parts by weight of a thermoplastic resin composition containing 10 to 50 parts by weight of a styrene-based resin (A) copolymerized with a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer, and 50 to 90 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 3 to 10 parts by weight of a styrene-isobutylene block copolymer (C). (2) The thermoplastic resin composition according to (1), further comprising an ester compound (E) obtained by reacting an aliphatic carboxylic acid having 12 to 40 carbon atoms with a polyhydric alcohol. (3) The thermoplastic resin composition according to (1) or (2), further comprising an α-olefin oligomer and / or an ethylene and α-olefin co-oligomer (D), wherein the kinematic viscosity of component (D) at 100°C is 30 cSt or more. (4) The thermoplastic resin composition according to (3), which contains 1 to 5 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 obtained by molding the thermoplastic resin composition according to any one of (1) to (4). (6) The molded product according to (5), wherein the coefficient of static friction between the molded products is 0.35 or less. [Effects of the Invention]

[0013] According to the present invention, a thermoplastic resin composition having excellent impact resistance, 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 thermoplastic resin composition and molded article thereof of the present invention will be described in detail below. The thermoplastic resin composition according to the present invention is characterized by comprising 100 parts by weight of a thermoplastic resin composition containing 10 to 50 parts by weight of a styrene-based resin (A) copolymerized with a monomer mixture containing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer, and 50 to 90 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 3 to 10 parts by weight of a styrene-isobutylene block copolymer (C).

[0015] (1) Styrene-based resin (A) The styrene-based resin (A) used in the present invention is a copolymer of a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer. Examples of the aromatic vinyl 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 monomer may be used alone or in combination of two or more. Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, and ethacrylonitrile. Among the vinyl cyanide monomers, acrylonitrile is preferred from the viewpoint of further improving the impact resistance of molded articles. The vinyl cyanide monomer may be used alone or in combination of two or more.

[0016] Furthermore, the styrene-based resin (A) may contain a vinyl-based copolymer obtained by copolymerizing, in addition to the aromatic vinyl-based monomer and the vinyl cyanide-based monomer, other vinyl-based monomer copolymerizable with them, in order to impart properties such as chemical resistance and heat resistance. Examples of these other vinyl monomers include (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, phthalic acid, N-methylmaleimide, and the like. Examples of suitable methacrylates include methyl methacrylate, 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-acroyloxazoline, and 2-styryloxazoline. Among these, methyl methacrylate is particularly preferred.

[0017] The proportion of the aromatic vinyl monomer contained in the styrene resin (A) is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, from the viewpoint of moldability.

[0018] The proportion of the vinyl cyanide monomer contained in the styrene resin (A) is preferably 3 to 40% by weight, more preferably 20 to 35% by weight, from the viewpoints of moldability, impact resistance, and noise reduction due to the incorporation of the styrene-isobutylene block copolymer (C).

[0019] 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).

[0020] The method for producing the styrene-based 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-based resin (A) may be produced by melt-kneading one or more styrene-based resins obtained by any of these methods.

[0021] 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 copolymer. That is, a rubber-modified styrene-based resin containing a graft copolymer obtained by graft polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer, and, if necessary, other vinyl monomers copolymerizable therewith onto a rubbery polymer can be preferably used as the styrene-based resin. Also preferred are aromatic vinyl copolymers obtained by graft polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer, and, if necessary, other vinyl monomers copolymerizable therewith, and rubber-modified styrene-based resins containing a graft copolymer obtained by graft polymerizing an aromatic vinyl monomer, a vinyl cyanide monomer, and, if necessary, other vinyl monomers copolymerizable therewith onto a rubbery polymer.

[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 aromatic vinyl copolymer matrix. Therefore, 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 obtained by graft-polymerizing a mixture of an aromatic vinyl monomer and a vinyl cyanide monomer onto the rubbery polymer. The monomers used in the graft polymerization are preferably the same as those in the aromatic vinyl (co)polymer matrix, and in the same proportions.

[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 AS resin, AAS resin, AES resin, ABS resin, MAS resin, MABS resin, etc., as well as alloys of these resins with other resins.

[0031] (2) Polycarbonate resin (B) 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.

[0032] Examples of aromatic polycarbonate resins include those with a bisphenol A skeleton as shown below, as well as those with a bisphenol S skeleton.

[0033] Commercially available polycarbonate resins (B) include polycarbonate resins "Iupilon" (registered trademark) S-2000 and H-3000 manufactured by Mitsubishi Engineering Plastics Corporation, and polycarbonate resins "Toughlon" (registered trademark) A2200, FN2200, and A1900 manufactured by Idemitsu Kosan Co., Ltd.

[0034] 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.

[0035] 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.

[0036] 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).

[0037] (3) Styrene-isobutylene block copolymer (C) The styrene-isobutylene block copolymer (C) used in the present invention has a polymer block mainly composed of isobutylene and a polymer block mainly composed of an aromatic vinyl monomer. Examples of the aromatic vinyl 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 monomer may be used alone or in combination of two or more.

[0038] The monomer component mainly composed of isobutylene may or may not contain a monomer other than isobutylene, and is usually a monomer component containing 60% by weight or more, preferably 80% by weight or more, of isobutylene. The monomer other than isobutylene is not particularly limited as long as it is a monomer capable of cationic polymerization, and examples thereof include the above-mentioned monomers.

[0039] The structure of the styrene-isobutylene block copolymer (C) used in the present invention is not particularly limited, and any block copolymer can be used. For example, block copolymers having a linear, branched, star-shaped structure, etc., as well as diblock copolymers, triblock copolymers, and multiblock copolymers can be selected. From the viewpoint of balance of physical properties, a preferred block copolymer is a triblock copolymer consisting of a polymer block mainly composed of an aromatic vinyl monomer, a polymer block mainly composed of isobutylene, and a polymer block mainly composed of an aromatic vinyl monomer. These may be used alone or in combination of two or more.

[0040] In the styrene-isobutylene block copolymer (C) used in the present invention, there are no particular restrictions on the ratio of the polymer block mainly composed of isobutylene to the polymer block mainly composed of an aromatic vinyl monomer. However, in terms of various physical properties, it is preferable that the polymer block mainly composed of isobutylene is 95 to 40% by weight and the polymer block mainly composed of an aromatic vinyl monomer is 5 to 60% by weight, and it is particularly preferable that the polymer block mainly composed of isobutylene is 85 to 50% by weight and the polymer block mainly composed of an aromatic vinyl monomer is 15 to 50% by weight.

[0041] The number average molecular weight of the styrene-isobutylene block copolymer (C) used in the present invention is not particularly limited, but is preferably 30,000 to 500,000, and particularly preferably 50,000 to 400,000, in terms of fluidity, processability, physical properties, etc. If the number average molecular weight of the styrene-isobutylene block copolymer (C) is lower than the above range, sufficient impact resistance is not exhibited, while if it exceeds the above range, it is disadvantageous in terms of fluidity and processability.

[0042] Commercially available styrene-isobutylene block copolymers (C) include isobutylene-based thermoplastic elastomers "SIBSTAR" (registered trademark) 062H, 062M, 062T, 072T, 073T, 102T, and 103T manufactured by Kaneka Corporation.

[0043] (4) α-olefin oligomers and / or ethylene and α-olefin co-oligomers with a kinematic viscosity of 30 cSt or more at 100°C (D) The thermoplastic resin of the present invention preferably contains (D) (hereinafter referred to as olefin oligomer (D)), which is an α-olefin oligomer and / or a co-oligomer of ethylene and α-olefin and has a kinematic viscosity of 30 cSt or more at 100° C. Monomers used in the olefin oligomer (D) 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-hexesecene, 1-octazecene, and 1-eicosene.

[0044] The olefin oligomer (D) used in the present invention preferably has a kinematic viscosity at 100°C of 30 cSt or more. Within this range, the resin molded product can exhibit high noise reduction even after aging. If the kinematic viscosity is less than 30 cSt, noise reduction after aging is not sufficiently exhibited. Furthermore, if the kinematic viscosity at 100°C exceeds 1000 cSt, productivity during mixing of the resin composition tends to decrease. The kinematic viscosity at 100°C can be measured for each olefin oligomer (D) used in the present invention (for example, measured according to JIS K2833 (2000)), but when using commercially available products, the kinematic viscosity at 100°C is specified as a catalog value for each product.

[0045] The amount of the olefin oligomer (D) used in the present invention is preferably 1 to 5 parts by weight, more preferably 1 to 3 parts by weight, per 100 parts by weight of the total of the styrene resin (A) and the polycarbonate resin (B). Within this range, high noise reduction can be achieved, even after deterioration over time. If the amount is less than 1 part by weight, the noise reduction is not fully achieved. 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 product tend to deteriorate.

[0046] (5) Ester compounds (E) obtained by reacting aliphatic carboxylic acids having 12 to 40 carbon atoms with polyhydric alcohols The thermoplastic resin composition of the present invention preferably contains an ester compound (E) obtained by reacting an aliphatic carboxylic acid having 12 to 40 carbon atoms with a polyhydric alcohol. The ester compound of component (E) is an ester compound obtained by reacting an aliphatic carboxylic acid having 12 to 40 carbon atoms with a polyhydric alcohol. Examples of the aliphatic carboxylic acid having 12 to 40 carbon atoms include long-chain aliphatic carboxylic acids such as stearic acid, olefinic acid, pehenic acid, and montanic acid, and examples of the polyhydric alcohol include ethylene glycol, pentaerythritol, polypentaerythritol, glycerin, trimethylolpropane, and polytrimethylolpropane. It is preferable to use an ester compound obtained by reacting these, and specific examples thereof include ethylene glycol distearate, pentaerythritol tetrastearate, polypentaerythritol polystearate, glycerin tristearate, trimethylolpropane tristearate, polytrimethylolpropane polystearate, ethylene glycol dimontanate, pentaerythritol tetramontanate, polypentaerythritol polymontanate, glycerin trimontanate, trimethylolpropane trimontanate, and polytrimethylolpropane polymontanate, and among these, pentaerythritol tetrastearate is preferred.

[0047] The amount of the ester compound (E) used in the present invention is preferably 0.5 to 5 parts by weight, more preferably 1 to 3 parts by weight, per 100 parts by weight of the total of the styrene resin (A) and the polycarbonate resin (B). Within this range, high noise reduction can be achieved, even after deterioration over time. If the amount is less than 0.5 parts by weight, the noise reduction is not sufficiently achieved, and if the amount is more than 5 parts by weight, the mechanical properties of the resulting thermoplastic resin composition are reduced.

[0048] (6) Static friction coefficient of resin molded body The thermoplastic resin of the present invention preferably has a static friction coefficient of 0.35 or less between molded articles obtained by molding the thermoplastic resin. Within this range, the resin molded article can exhibit high quietness even after aging.

[0049] The static friction coefficient in the present invention is calculated when a test piece of 50 mm × 25 mm × 2 mmt and a test piece of 80 mm × 80 mm × 2 mmt are rubbed together using a Ziegler stick-slip measuring device SSP-04 under conditions of a load of 40 N and a speed of 4 mm / s.

[0050] (7) Other ingredients Other resins may also be added as long as they do not impair the properties of the present invention.Specific examples of resins that can be used depending on the purpose include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polycyclohexylene dimethylene ethylene terephthalate, polyarylate, liquid crystal polymer, polylactic acid, and polycaprolactone, polyamide resins such as nylon 6, nylon 6,6, nylon 6,10, nylon 4,6, nylon 6T, nylon 9T, and nylon 11, and other resins such as polyphenylene sulfide (PPS), polyacetal, crystalline styrene, and polyphenylene ether (PPE).

[0051] Furthermore, as needed, additives may be added, provided that they do not impair the properties of the present invention, such as hindered phenol-based antioxidants, sulfur-containing compound-based antioxidants, phosphorus-containing organic compound-based antioxidants, phenol-based and acrylate-based thermal antioxidants, benzotriazole-based, benzophenone-based and succinate-based ultraviolet absorbers, decabromobiphenyl ether, tetrabromobisphenol A, chlorinated polyethylene, brominated epoxy oligomer, brominated polycarbonate, antimony trioxide and condensed phosphate ester flame retardants and flame retardant aids, antibacterial agents typified by silver-based antibacterial agents, antifungal agents, carbon black, titanium oxide, mold release agents, lubricants, pigments and dyes.

[0052] Various fillers can also be blended. Examples of fillers include fibrous, plate-like, powdery, and granular fillers, and any of these may be used in the present invention. Specific examples include polyacrylonitrile (PAN)-based and pitch-based carbon fibers, metal fibers such as stainless steel fibers, aluminum fibers, and brass fibers, organic fibers such as aromatic polyamide fibers, gypsum fibers, ceramic fibers, asbestos fibers, zirconia fibers, alumina fibers, silica fibers, titanium oxide fibers, silicon carbide fibers, glass fibers, rock wool, potassium titanate whiskers, barium titanate whiskers, aluminum borate whiskers, and silicon nitride whiskers, as well as powdery, granular, or plate-like fillers such as mica, talc, kaolin, silica, calcium carbonate, glass flakes, glass beads, glass microballoons, clay, molybdenum disulfide, wollastonite, montmorillonite, titanium oxide, zinc oxide, barium sulfate, calcium polyphosphate, and graphite. These fillers may be used alone or in combination of two or more.

[0053] (8) Thermoplastic resin composition The thermoplastic resin composition of the present invention is characterized by comprising 100 parts by weight of a thermoplastic resin composition containing 10 to 50 parts by weight of a styrene-based resin (A) copolymerized with a monomer mixture containing an aromatic vinyl-based monomer and a vinyl cyanide-based monomer, and 50 to 90 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 3 to 10 parts by weight of a styrene-isobutylene block copolymer (C) is blended with the thermoplastic resin composition.

[0054] If the styrene-based resin (A) is less than 10 parts by weight, the proportion of polycarbonate resin (B) will be high, which tends to result in poor fluidity. If the styrene-based resin (A) is more than 50 parts by weight, the proportion of polycarbonate resin (B) will be low, which tends to result in poor impact resistance. If the styrene-isobutylene block copolymer (C) in the thermoplastic resin composition is less than 3 parts by weight, the effect of preventing squeak noise will be poor. Even if it is more than 10 parts by weight, the strong tackiness will be expressed, which will easily cause vibrations, and the effect of preventing squeak noise will be poor.

[0055] The amount of the styrene-isobutylene block copolymer (C) can also be defined as the content of the polymer block containing isobutylene as the main component in the thermoplastic resin. In this case, the content of the isobutylene polymer block in the thermoplastic resin composition is preferably in the range of 2 to 8% by weight.

[0056] 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.

[0057] 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. [Example]

[0058] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0059] (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.

[0060] (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.

[0061] (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 insoluble matter 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 concentration was adjusted to 0.4 g / 100 ml (methyl ethyl ketone, 30°C), and the reduced viscosity was measured using an Ubbelohde viscometer.

[0062] (4) Melt flow rate The melt flow rate was measured at 240°C and 98N in accordance with ISO1133:2011.

[0063] (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.

[0064] (6) Quietness and static friction coefficient 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.

[0065] The noise reduction was evaluated by measuring the noise risk value when the two test pieces mentioned above were rubbed together under a load of 40N and a speed of 4mm / s using a Ziegler stick-slip measuring device SSP-04. The static friction coefficient was also measured using the same measurement. The smaller the noise reduction risk value, the smaller the risk of squeaking noise. 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.

[0066] 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.

[0067] The materials and manufacturing methods used in each of the examples and comparative examples are shown below. <Styrene-based resin (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.

[0068] <Styrene-based resin (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.

[0069] <Styrene-based resin (a-1)> "PSJ-Polystyrene" (registered trademark) H8672 manufactured by PS Japan Co., Ltd. was used. This styrene resin (a-1) is a rubber-reinforced polystyrene resin that does not contain vinyl cyanide monomer units.

[0070] <Polycarbonate resin (B-1)> The polycarbonate resin used was "Iupilon" (registered trademark) S-2000 manufactured by Mitsubishi Engineering Plastics Corp. The viscosity average molecular weight of this polycarbonate resin (B-1) was 23,000.

[0071] <Styrene-isobutylene block copolymer (C-1)> "SIBSTAR" (registered trademark) 102T manufactured by Kaneka Corporation was used. This styrene-isobutylene block copolymer (C-1) was a styrene-isobutylene-styrene triblock copolymer with a number average molecular weight of 92,000 and an isobutylene content of 85%.

[0072] <Styrene-isobutylene block copolymer (C-2)> Kaneka Corporation's "SIBSTAR" (registered trademark) 062M was used. This styrene-isobutylene block copolymer (C-2) was a mixture of a styrene-isobutylene diblock copolymer and a styrene-isobutylene-styrene triblock copolymer, and had a number average molecular weight of 65,000 and an isobutylene content of 77%.

[0073] <Other styrene block copolymers (TPS-1)> We used "Hybler" (registered trademark) 5127 manufactured by Kuraray Co., Ltd. This styrene-based block copolymer (TPS-1) is a styrene-vinyl-polydiene-styrene triblock copolymer (vinyl SIS).

[0074] <Other styrene block copolymers (TPS-2)> We used "Hybler" (registered trademark) 7125F manufactured by Kuraray Co., Ltd. This styrene-based block copolymer (TPS-2) is a hydrogenated styrene-vinyl-polydiene-styrene triblock copolymer (vinyl SEPS).

[0075] <Other styrene block copolymers (TPS-3)> We used "Hybler" (registered trademark) 7311F manufactured by Kuraray Co., Ltd. This styrene-based block copolymer (TPS-3) is a hydrogenated styrene-vinyl-polydiene-styrene triblock copolymer (vinyl SEEPS).

[0076] <Other styrene block copolymers (TPS-4)> Asahi Kasei Corporation's "SOE" (registered trademark) S1605 was used. This styrene-based block copolymer (TPS-4) is a styrene-(ethylene-butylene)-styrene triblock copolymer (SEBS).

[0077] <Ethylene-vinyl acetate copolymer with styrene-based (co)polymer segments> "Modiper" (registered trademark) AS-100 manufactured by NOF Corporation was used.

[0078] <Olefin Oligomer (D-1)> The used product was "Lucant" (registered trademark) HC-100 manufactured by Mitsui Chemicals, Inc. The kinematic viscosity of (D-1) at 100°C was 100 cSt.

[0079] <Olefin Oligomer (D-2)> The used product was "Lucant" (registered trademark) HC-40 manufactured by Mitsui Chemicals, Inc. The kinematic viscosity of (D-2) at 100°C is 40 cSt.

[0080] <Other olefin oligomers (d-1)> The solvent used was "Lucant" (registered trademark) HC-20 manufactured by Mitsui Chemicals, Inc. The kinematic viscosity of (d-1) at 100°C was 20 cSt.

[0081] <Ester compound (E-1)> The ester compound used was "Unistar" (registered trademark) H-476 manufactured by NOF Corporation. The ester compound (E-1) was pentaerythritol tetrastearate, which is an ester compound obtained by reacting stearic acid, an aliphatic carboxylic acid having 18 carbon atoms, with pentaerythritol, a tetrahydric alcohol.

[0082] <Other ester compounds (e-1)> "Unistar" (registered trademark) M-9676 manufactured by NOF Corporation was used. The ester compound (e-1) was stearyl stearate, and was not an ester compound obtained by reacting an aliphatic carboxylic acid having 12 to 40 carbon atoms with a polyhydric alcohol.

[0083] The above components were mixed in the ratios shown in Tables 1 and 2, then stirred in a blender for 1 minute, and the mixture was melt-kneaded in a 30mm screw diameter co-rotating twin-screw extruder (PCM-30, manufactured by Ikegai Corporation, temperature range: 250-260°C). The molten resin extruded from the die nozzle was taken up by a cutter through a water bath and cut into resin pellets. Tables 1 and 2 show the measurement and evaluation results for each example and comparative example.

[0084] [Table 1]

[0085] [Table 2]

[0086] The following is clear from Tables 1 and 2. All of the thermoplastic resin compositions of the present invention (Examples 1 to 9) were excellent in Charpy impact strength, fluidity, and quietness. Furthermore, Examples 5 and 6, which contain an α-olefin oligomer and / or an ethylene and α-olefin co-oligomer (D) and in which the kinematic viscosity of component (D) at 100°C is 30 cSt or more, and Example 8, which contains an ester compound (E) obtained by reacting an aliphatic carboxylic acid having 12 to 40 carbon atoms with a polyhydric alcohol, had static friction coefficients of 0.35 or less and were excellent in quietness (sustained quietness) even after heat treatment to simulate changes over time.

[0087] On the other hand, Comparative Examples 1 and 2, in which the amount of styrene-isobutylene block copolymer (C) in the thermoplastic resin composition was less than 3 parts by weight, were inferior in quietness. Comparative Example 3, in which the amount of styrene-isobutylene block copolymer (C) in the thermoplastic resin composition was more than 10 parts by weight, was also inferior in quietness. Comparative Examples 4 to 7, in which a styrene-based elastomer having a chemical structure similar to that of the styrene-isobutylene block copolymer (C) and generally considered to have excellent vibration-damping properties was added, were also inferior in quietness. Comparative Example 8, in which an ethylene-vinyl acetate copolymer having a styrene-based (co)polymer segment was added, was inferior in Charpy impact strength and fluidity. Comparative Example 9, in which only a styrene-based resin not containing vinyl cyanide-based monomer units was used, was inferior in Charpy impact strength and quietness. [Industrial Applicability]

[0088] The thermoplastic resin composition of the present invention has excellent Charpy impact strength, fluidity, and quietness. Due to these properties, it can be suitably used in fields where creaking noises may be generated due to vibrations, such as automobile parts, office automation equipment, home appliances, and general merchandise.

Claims

1. A thermoplastic resin composition for preventing squeak noise, comprising 100 parts by weight of a thermoplastic resin composition containing 10 to 50 parts by weight of a styrene-based resin (A) obtained by copolymerizing a monomer mixture containing an aromatic vinyl monomer and a vinyl cyanide monomer, and 50 to 90 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, blended with 3 to 10 parts by weight of a styrene-isobutylene block copolymer (C), and further blended with an α-olefin oligomer and / or an ethylene-α-olefin co-oligomer (D), wherein the kinematic viscosity of component (D) at 100°C is 30 cSt or more.

2. The thermoplastic resin composition for preventing squeak noise according to claim 1, further comprising an ester compound (E) obtained by reacting an aliphatic carboxylic acid having 12 to 40 carbon atoms with a polyhydric alcohol.

3. 2. The thermoplastic resin composition for preventing squeak noise according to claim 1, comprising 1 to 5 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).

4. A squeak-preventing molded article obtained by molding the squeak-preventing thermoplastic resin composition according to any one of claims 1 to 3.

5. 5. The molded article for preventing squeak noise according to claim 4, wherein the coefficient of static friction between the molded articles is 0.35 or less.

Images