Thermoplastic resin composition and molded article

Abstract

To provide a thermoplastic resin composition for forming a molding having excellent rigidity and heat aging resistance.SOLUTION: Provided is a thermoplastic resin composition that contains a thermoplastic resin (A) having a melt flow rate (230°C, 2.16 kg load) of 1 g / 10 minutes or more by 55 to 69 pts.mass and an inorganic filler (B) by 31 to 45 pts.mass (where the total amount of (A) and (B) is 100 pts.mass), and an antioxidant (C) by 0.38 pts.mass or more, and in which the antioxidant (C) contains a hindered phenol-based antioxidant (C1-1) having neither an ester structure nor an amide structure as a primary antioxidant, and does not contain an antioxidant (C1-2) having an ester structure or an amide structure, or, contains by less than 0.1 pts.mass.SELECTED DRAWING: None

Description

[Technical field]

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

[0002] 2. Description of the Related Art Resin compositions containing a polypropylene resin and an inorganic filler are materials excellent in rigidity, heat resistance, etc., and are used in various applications such as automobile parts. As such a resin composition, for example, Patent Document 1 discloses an inorganic filler-reinforced polyolefin resin composition containing an ethylene-propylene block copolymer, an inorganic filler, a non-alkali metal salt of a fatty acid, an N-methyl hindered amine stabilizer, and a hindered phenol antioxidant, and Patent Documents 2 to 4 also disclose resin compositions containing a polypropylene resin, an inorganic filler, a hindered phenol antioxidant, etc. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-181222 [Patent Document 2] JP 2009-127007 A [Patent Document 3] Japanese Patent Application Publication No. 9-165478 [Patent Document 4] JP 2014-185297 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, molded articles formed from conventional thermoplastic resin compositions have room for further improvement in terms of heat aging resistance. An object of the present invention is to provide a molded article having excellent rigidity and heat aging resistance, and a thermoplastic resin composition for forming such a molded article. [Means for solving the problem]

[0005] The present invention relates to, for example, the following [1]-

[11] . [1] 55 to 69 parts by mass of a thermoplastic resin (A) having a melt flow rate (230°C, 2.16 kg load) of 1 g / 10 min or more, 31 to 45 parts by mass of inorganic filler (B) (wherein the total amount of thermoplastic resin (A) and inorganic filler (B) is 100 parts by mass), and Contains 0.38 parts by mass or more of an antioxidant (C), The antioxidant (C) contains, as a primary antioxidant, a hindered phenol-based antioxidant (C1-1) having neither an ester structure nor an amide structure, and does not contain, or contains less than 0.1 parts by mass of, an antioxidant (C1-2) having an ester structure or an amide structure. Thermoplastic resin composition. [2] The thermoplastic resin composition according to [1] above, wherein the antioxidant (C) contains a sulfur-based antioxidant (C2) as a secondary antioxidant. [3] The thermoplastic resin composition according to [1] or [2] above, which contains two or more kinds of the hindered phenol-based antioxidant (C1-1). [4] The thermoplastic resin composition according to any one of [1] to [3] above, wherein the content of the hindered phenol-based antioxidant (C1-1) is 0.18 parts by mass or more. [5] The thermoplastic resin composition according to any one of the above [1] to [4], wherein the hindered phenol-based antioxidant (C1-1) is at least one compound represented by any one of the following formulas (C11i), (C11j) and (C11k): [ka] [6] The thermoplastic resin composition according to any one of the above [1] to [5], which contains no carbon black or not more than 0.24 parts by mass of carbon black. [7] The thermoplastic resin composition according to any one of the above [1] to [6], wherein the thermoplastic resin (A) is a polypropylene-based resin. [8] A molded article formed from the thermoplastic resin composition of any one of the above [1] to [7]. [9] The molded body according to [8] above, which is an injection molded body.

[10] The molded article according to [8] or [9] above, which is an automotive component.

[11] The molded article according to

[10] , wherein the automotive component is a component around an automobile engine. Effect of the Invention

[0006] According to the thermoplastic resin composition of the present invention, a molded article having excellent rigidity and heat aging resistance can be formed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0007] The present invention will now be described in further detail. [Thermoplastic resin composition] The thermoplastic resin composition according to the present invention is characterized by containing predetermined amounts of a thermoplastic resin (A), an inorganic filler (B), and a predetermined antioxidant (C).

[0008] <Thermoplastic resin (A)> The thermoplastic resin composition of the present invention contains a thermoplastic resin (A). From the viewpoint of moldability of the thermoplastic resin composition according to the present invention, the melt flow rate (230°C, 2.16 kg load) of the thermoplastic resin (A) is 1 g / 10 min or more, preferably 5 to 40 g / 10 min, and more preferably 10 to 25 g / 10 min.

[0009] Examples of the thermoplastic resin (A) include polyolefin-based resins, polyamide-based resins, and polystyrene-based resins. Examples of polyolefin resins include polypropylene resins such as propylene homopolymers, propylene-α-olefin random copolymers, and propylene block copolymers. Among these, polypropylene resins are preferred because of their excellent rigidity and flowability, and propylene homopolymers and propylene block copolymers are more preferred.

[0010] The propylene-α-olefin random copolymer includes a random copolymer of propylene and an α-olefin having 2 to 20 carbon atoms (excluding propylene). Examples of the α-olefin include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, 1-heptene, 1-octene, 1-nonene, 1-decene, and 1-dodecene, preferably ethylene and 1-butene, and particularly preferably ethylene. The amount of structural units derived from the α-olefin in the propylene-α-olefin random copolymer is preferably 10% by mass or less, more preferably 5% by mass or less.

[0011] The propylene-based block copolymer is preferably composed of a propylene homopolymer portion and a propylene-α-olefin random copolymer portion. A specific embodiment of the propylene-α-olefin random copolymer portion is the same as that of the propylene-α-olefin random copolymer.

[0012] When the propylene-based block copolymer is fractionated with an n-decane solvent, it is fractionated into a component soluble in n-decane at 23° C. (hereinafter also referred to as a "decane-soluble portion") and a component insoluble in n-decane at 23° C. (hereinafter also referred to as a "decane-insoluble portion") The content of the decane-soluble portion is usually 5 to 30 mass%, preferably 5 to 25 mass%, and more preferably 8 to 18 mass%, and the content of the decane-insoluble portion is usually 70 to 95 mass%, preferably 75 to 95 mass%, and more preferably 82 to 92 mass%.

[0013] Polyamide resins are obtained by ring-opening polymerization or polycondensation of polymerizable aminocarboxylic acids or their lactams, or dicarboxylic acids and diamines, etc. as raw materials.

[0014] Examples of polyamide resins include nylon 6, nylon 66, nylon 6 / 66 copolymers, nylon 66 / 6T copolymers (T: terephthalic acid), nylon 6T / 6I copolymers (I: isophthalic acid), and nylon 6T / M5T copolymers (M5: 2-methylpentamethylenediamine, T: terephthalic acid).

[0015] Examples of polystyrene-based resins include homopolymers of styrene, random copolymers of styrene and other copolymerizable monomers, block copolymer resins consisting of polystyrene blocks and other polymer blocks, and graft copolymer resins in which styrene is graft-polymerized onto other polymers.

[0016] The thermoplastic resin (A) may be used alone or in combination of two or more kinds. As the thermoplastic resin (A), from the viewpoint of the remarkable improvement in heat aging resistance due to the antioxidant (C) described below, a polyolefin resin is preferable, and a polypropylene resin is more preferable.

[0017] The content of the thermoplastic resin (A) in the thermoplastic resin composition of the present invention is 55 to 69 parts by mass, preferably 55 to 65 parts by mass, and more preferably 60 to 65 parts by mass, per 100 parts by mass of the total of the thermoplastic resin (A) and the inorganic filler (B).

[0018] <Inorganic filler (B)> The thermoplastic resin composition of the present invention contains an inorganic filler (B). Examples of the inorganic filler (B) include talc, mica, calcium carbonate, calcium sulfate, clay minerals, glass fibers, carbon fibers, glass flakes, silica, mica, calcium silicate, aluminum hydroxide, magnesium hydroxide, aluminum oxide, and magnesium oxide. Among these, talc is preferred from the viewpoint of the remarkable improvement in heat aging resistance due to the antioxidant (C) described below.

[0019] The inorganic filler (B) may be used alone or in combination of two or more kinds. The average particle size (D50 value measured by a laser diffraction / scattering method) of the inorganic filler (B) is usually about 1 μm to 200 μm.

[0020] The content of the inorganic filler (B) in the thermoplastic resin composition of the present invention is 31 to 45 parts by mass, preferably 35 to 45 parts by mass, and more preferably 35 to 40 parts by mass, based on 100 parts by mass of the total of the thermoplastic resin (A) and the inorganic filler (B). When the content is within the above range, high rigidity is exhibited while excellent toughness is achieved.

[0021] <Antioxidants (C)> The thermoplastic resin composition of the present invention contains an antioxidant (C). The content of the antioxidant (C) in the thermoplastic resin composition of the present invention is 0.38 parts by mass or more, preferably 0.39 parts by mass or more, more preferably 0.40 parts by mass or more, based on 100 parts by mass of the total of the thermoplastic resin (A) and the inorganic filler (B). When the content is within the above range, the thermoplastic resin composition according to the present invention has excellent heat aging resistance. The upper limit of the content may be, for example, 1 part by mass.

[0022] <Hindered phenol-based antioxidant having neither an ester structure nor an amide structure (C1-1)> The antioxidant (C) contains a hindered phenol-based antioxidant (C1-1) having neither an ester structure nor an amide structure as a primary antioxidant. A primary antioxidant is one that captures radicals and has the effect of preventing autoxidation.

[0023] The hindered phenol-based antioxidant (C1-1) is a hindered phenol compound having neither an ester structure nor an amide structure. In the present invention, an ester structure refers to a structure formed by losing water from an oxoacid and an alcohol, a phenol, or the like, and examples of such structures include structures represented by RC(=O)(OR), RC(=S)(OR), RC(=O)(SR), RS(=O)2(OR), RP(=O)(OH)(OR), and (RS)2C(=O) (each R is independently a hydrocarbon group (e.g., a methylene group)).

[0024] In the present invention, the amide structure refers to a structure in which the acidic hydroxy group of an oxoacid is replaced with an amino group or a substituted amino group, and examples thereof include structures represented by RC(=O)(NR'R'), RC(=O)NHC(=O)R, RC(=O)N(C(=O)R)(C(=O)R), RS(=O)2(NR'R'), and RP(=O)(OH)(NR'R') (each R is independently a hydrocarbon group (e.g., a methylene group), and each R' is independently a hydrocarbon group (e.g., a methylene group) or a hydrogen atom).

[0025] Examples of the hindered phenol-based antioxidant (C1-1) include compounds represented by any of the following formulas (C11a) to (C11L).

[0026] [ka]

[0027] [ka]

[0028] [ka]

[0029] [ka]

[0030] Among these, the compounds represented by any one of the above formulas (C11i), (C11j) and (C11k) are preferred.

[0031] Examples of commercially available products of the hindered phenol-based antioxidant (C1-1) include IRGANOX (registered trademark) 1330 (a compound represented by the above formula (C11i)), IRGANOX 3114 (a compound represented by the above formula (C11j)) (both manufactured by BASF), and Cyanox 1790 (a compound represented by the above formula (C11k)).

[0032] The hindered phenol-based antioxidant (C1-1) may be used alone or in combination of two or more. Since high heat aging resistance can be imparted to a molded article, it is preferable to use two or more in combination, and it is more preferable to use a compound represented by the above formula (C11i) in combination with a compound represented by the above formula (C11j). For example, when two types of compounds are used in combination as the hindered phenol-based antioxidant (C1-1), the mass ratio of the compounds (mass of one compound (e.g., a compound represented by formula (C11j)) / mass of the other compound (e.g., a compound represented by formula (C11i))) is preferably 1 or less, more preferably 0.5 to 1.

[0033] The content of the hindered phenol-based antioxidant (C1-1) in the thermoplastic resin composition of the present invention is preferably 0.18 parts by mass or more, more preferably 0.19 parts by mass or more, and even more preferably 0.20 parts by mass or more, based on 100 parts by mass of the total of the thermoplastic resin (A) and the inorganic filler (B). When the content of the hindered phenol-based antioxidant (C1-1) is within the above range, the thermoplastic resin composition according to the present invention has excellent heat aging resistance. The upper limit of the content may be, for example, 1 part by mass.

[0034] <<Ester / amide structure-containing antioxidants (C1-2)>> The antioxidant (C) does not contain an antioxidant (C1-2) having an ester structure or an amide structure (hereinafter also referred to as "antioxidant (C1-2) containing an ester / amide structure") as a primary antioxidant, or if it contains one, the amount thereof is less than 0.1 part by mass, preferably 0.02 part by mass or less, relative to 100 parts by mass of the total of the thermoplastic resin (A) and the inorganic filler (B).

[0035] The ester / amide structure-containing antioxidant (C1-2) is an antioxidant consisting of a compound having an ester structure or an amide structure. Examples of the ester / amide structure-containing antioxidant (C1-2) include compounds represented by any of the following formulae (C12a) to (C12h).

[0036] [ka]

[0037] [ka]

[0038] It is considered that the ester / amide structure-containing antioxidant (C1-2) is adsorbed to inorganic fillers such as talc in the thermoplastic resin composition, and the heat aging resistance of the thermoplastic resin composition cannot be sufficiently improved. The thermoplastic resin composition of the present invention contains a hindered phenol-based antioxidant (C1-1) having neither an ester structure nor an amide structure as a primary antioxidant, while it does not contain an ester / amide structure-containing antioxidant (C1-2), or if it does, the amount is small. Therefore, the thermoplastic resin composition of the present invention exhibits excellent heat aging resistance.

[0039] Sulfur-based antioxidants (C2) The antioxidant (C) may contain a sulfur-based antioxidant (C2) as a secondary antioxidant, which has the effect of decomposing peroxides generated by the action of the primary antioxidant.

[0040] Examples of the sulfur-based antioxidant (C2) include conventionally known sulfur-based antioxidants used as secondary antioxidants, such as Dialkyl thiodipropionates such as dilauryl thiodipropionate (DLTP), dimyristyl thiodipropionate (DMTP) and distearyl thiodipropionate (DSTP) (the alkyl group is preferably a linear alkyl group having 8 to 32 carbon atoms), and Esters (e.g., pentaerythritol tetrakis(3-laurylthiopropionate)) of alkylthiopropionic acids (such as butylthiopropionic acid, octylthiopropionic acid, laurylthiopropionic acid, and stearylthiopropionic acid, where the alkyl group is preferably a linear alkyl group having 8 to 32 carbon atoms) and polyhydric alcohols (e.g., glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and trishydroxyethyl isocyanurate). Examples include:

[0041] The sulfur-based antioxidant (C2) may be used alone or in combination of two or more kinds. In the thermoplastic resin composition of the present invention, the mass ratio of the sulfur-based antioxidant (C2) to the primary antioxidant (mass of sulfur-based antioxidant (C2) / total mass of antioxidant (C1-1) and antioxidant (C1-2)) is preferably 0 to 1, and more preferably 0 to 0.8. A mass ratio of 0 means that the antioxidant (C) does not contain the sulfur-based antioxidant (C2). When the mass ratio is in the above range, the thermoplastic resin composition of the present invention has excellent heat aging resistance.

[0042] <Optional ingredients> The thermoplastic resin composition of the present invention may or may not further contain carbon black.

[0043] When the thermoplastic resin composition of the present invention contains carbon black, the content thereof is preferably 0.24 parts by mass or less, more preferably 0.21 parts by mass or less, based on 100 parts by mass of the total of the thermoplastic resin (A) and the inorganic filler (B). When the carbon black content is within this range, the impact resistance is excellent.

[0044] The thermoplastic resin composition of the present invention may contain optional components other than the above (A), (B), (C) and carbon black, as necessary, within the scope of the present invention. Examples of the optional components include heat stabilizers, weather stabilizers, antiaging agents, softeners, dispersants, colorants, pigments, antistatic agents, slip agents, antiblocking agents, antifogging agents, lubricants, natural oils, synthetic oils, and waxes. On the other hand, the thermoplastic resin composition of the present invention preferably does not contain metal soaps from the viewpoints of preventing metal contamination, cost, etc.

[0045] (Method of producing thermoplastic resin composition) The thermoplastic resin composition of the present invention can be produced by mixing the above-mentioned components, preferably by mixing or melt-kneading them with a mixing device such as a Banbury mixer, a single screw extruder, a twin screw extruder, a high-speed twin screw extruder, etc. The components may be mixed in any order, and may be mixed simultaneously or in multiple stages, such as by mixing some components in advance and then mixing the other components.

[0046] [Molded body] The molded article of the present invention is a molded article formed from the thermoplastic resin composition of the present invention. That is, the molded article of the present invention can be obtained by using the thermoplastic resin composition of the present invention as a raw material and molding it.

[0047] The molding method is not particularly limited and may be appropriately selected depending on the desired application. Examples of the molded article of the present invention include injection molded articles, foam molded articles, injection foam molded articles, extrusion molded articles, blow molded articles, vacuum / pressure molded articles, calendar molded articles, stretched films, inflation films, etc., with injection molded articles being particularly preferred.

[0048] The molded article of the present invention has excellent rigidity and heat aging resistance, and can be used as automobile parts (interior and exterior parts), home appliances, machine parts, general miscellaneous goods, etc., and can be preferably used as automobile parts, particularly parts around an automobile engine that require heat aging resistance. Examples of automobile parts include bumpers, pillars, and instrument panels. EXAMPLES

[0049] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples. [Measurement method] Heat aging resistance test: From the compositions produced in the Examples, etc., dumbbell test pieces of 165 mm (total length) × 19 mm (width at both ends) × 3.2 mm (thickness) were produced by injection molding. Using a heating oven (Gear-type aging tester manufactured by ESPEC Co., Ltd.), the time until cracks occurred in the test pieces was measured at 150°C. The measurement was performed three times, and the average time until cracks occurred was calculated.

[0050] Bend test: A test piece having a size of 127 mm (length) × 12.7 mm (width) × 6.35 mm (thickness) was prepared by injection molding from the composition produced in the examples, etc. Using this test piece, the bending elastic stress (FM: MPa) was determined in accordance with ASTM D790, with a bending span of 100 mm and a test speed of 30 mm / min.

[0051] [Raw materials] The raw materials used in the examples are as follows. Thermoplastic resin (A): Propylene block copolymer (Prime Polymer Co., Ltd., melt flow rate (230°C, 2.16 kg load): 23 g / 10 min) Inorganic filler (B): talc (a mixture of JM-209 (manufactured by Asada Flour Milling Co., Ltd.) and PKP-53 (manufactured by Fuji Talc Industries Co., Ltd.) in a mass ratio of 1:1)

[0052] Hindered phenol antioxidants (C1-1) having neither an ester structure nor an amide structure: "Irganox 1330" (manufactured by BASF Japan Ltd., chemical name: 3,3',3'',5,5',5''-hexa-t-butyl-α,α',α''-(mesitylene-2,4,6-triyl)tri-p-cresol, hereinafter also referred to as "Irg1330") "Irganox 3114" (manufactured by BASF Japan Ltd., compound name: 1,3,5-tris(3,5-di-t-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, hereinafter also referred to as "Irg3114")

[0053] Antioxidants having an ester or amide structure (C1-2): "Irganox 1010" (manufactured by BASF Japan Ltd., chemical name: pentaerythritol tetrakis(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, hereinafter also referred to as "Irg1010") Sulfur-based antioxidants (C2): DMTP "Yoshitomi" (manufactured by Mitsubishi Chemical Corporation, chemical name: dimyristyl thiodipropionate, hereinafter also referred to as "DMTP")

[0054] [Example 1] A composition was prepared by dry blending 60 parts by mass of a propylene-based block copolymer, 40 parts by mass of talc, 0.20 parts by mass of Irg1330, and 0.20 parts by mass of Irg3114 in a tumbler mixer, and melt-kneading the mixture at 200° C. in a twin-screw kneading extruder. The evaluation results of this composition are shown in Table 1.

[0055] [Examples 2 to 7, Comparative Examples 1 to 5] Compositions were prepared and evaluated in the same manner as in Example 1, except that the types or amounts of raw materials were changed as shown in Table 1. The evaluation results are shown in Table 1.

[0056] [Table 1]

Claims

1. 55 to 69 parts by mass of a thermoplastic resin (A) having a melt flow rate (230° C., 2.16 kg load) of 1 g / 10 min or more, 31 to 45 parts by mass of inorganic filler (B) (wherein the total amount of thermoplastic resin (A) and inorganic filler (B) is 100 parts by mass), and Contains 0.38 parts by mass or more of an antioxidant (C), The inorganic filler (B) is selected from talc, mica, calcium carbonate, calcium sulfate, clay minerals, glass fibers, carbon fibers, glass flakes, silica, mica, calcium silicate, aluminum hydroxide, aluminum oxide, and magnesium oxide; The antioxidant (C) contains, as a primary antioxidant, two or more kinds of hindered phenol-based antioxidants (C1-1) having neither an ester structure nor an amide structure, and does not contain or contains less than 0.1 parts by mass of an antioxidant (C1-2) having an ester structure or an amide structure. Thermoplastic resin composition.

2. The thermoplastic resin composition according to claim 1, wherein the antioxidant (C) contains a sulfur-based antioxidant (C2) as a secondary antioxidant.

3. 3. The thermoplastic resin composition according to claim 1, wherein the content of the hindered phenol-based antioxidant (C1-1) is 0.18 parts by mass or more.

4. A thermoplastic resin composition described in any one of claims 1 to 3, wherein the hindered phenol-based antioxidant (C1-1) is two or more types of compounds represented by any of the following formulas (C11a) to (C11L): 【Chemistry 1】 【Chemistry 2】

5. The thermoplastic resin composition according to any one of claims 1 to 4, wherein the hindered phenol-based antioxidant (C1-1) is two or more compounds represented by any one of the following formulas (C11i), (C11j) and (C11k): 【Chemistry 3】

6. The thermoplastic resin composition according to any one of claims 1 to 5, which contains no carbon black or contains 0.24 parts by mass or less of carbon black.

7. The thermoplastic resin composition according to any one of claims 1 to 6, wherein the thermoplastic resin (A) is a polypropylene-based resin.

8. A molded article formed from the thermoplastic resin composition according to any one of claims 1 to 7.

9. The molded article according to claim 8, which is an injection molded article.

10. The molded article according to claim 8 or 9, which is an automobile part.

11. The molded article according to claim 10, wherein the automobile part is a part around an automobile engine.

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