Thermoplastic resin composition and molded article

Abstract

To provide a resin composition that has superior pigment dispersibility, combines a metallic appearance and low weld lines, and enables formation of molded articles having superior appearance, and also to provide a thermoplastic resin composition having superior mechanical properties, scratch resistance, and light resistance.SOLUTION: Disclosed is a thermoplastic resin composition which contains a photoluminescent pigment (A), carbon black (B), a polyolefin wax (C), and a polyolefin resin (D). The carbon black (B) is contained in an amount of 0.1-10 mass% based on 100 mass% of the thermoplastic resin composition, and the content mass ratio (B) / (C) of the carbon black (B) to the polyolefin wax (C) is 0.1 to 10.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a thermoplastic resin composition and a molded article formed from the thermoplastic resin composition.

Background Art

[0002] Molded articles formed from thermoplastic resin compositions are used in a wide variety of fields such as automotive parts, home appliance parts, OA equipment, building materials, and decorative articles because they are relatively inexpensive and have excellent properties. However, the appearance and touch of such molded articles may give an inexpensive impression compared to molded articles made of metallic materials, inorganic materials, or wood. Therefore, there is a demand for providing highly designed molded articles having a metallic feeling like metal. And, in order to obtain a metallic appearance, a method of applying a metallic paint for painting treatment is known. However, in consideration of simplifying the manufacturing process and reducing the environmental load, there is a demand for molded articles that can exhibit a good metallic appearance without painting.

[0003] As a material corresponding to unpainted, a thermoplastic resin composition in which a bright pigment such as an aluminum pigment is kneaded into a thermoplastic resin has been studied.

[0004] For example, Patent Document 1 describes that a resin composition having a metallic feeling can be obtained by kneading an aluminum pigment into a synthetic resin. Patent Document 2 proposes a method of injection molding a polypropylene-based resin composition containing a bright material using a mold provided with a heat insulating layer on the inner surface of the cavity. Patent Document 3 discloses a polypropylene resin composition having a flip-flop metallic feeling by using carbon black and aluminum flakes. Patent Document 4 discloses a masterbatch containing an aluminum pigment.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0006] By using a phosphorescent pigment in this way, a metallic appearance without painting can be achieved. However, molded articles containing the phosphorescent pigment tend to show molding defects such as weld lines and flow marks more prominently, making it difficult to use them for large parts such as building materials and automotive parts. Furthermore, in the above applications, they are often used outdoors, and light resistance and scratch resistance of the molded articles are also required.

[0007] In conventional molded articles, for example, in Patent Document 2, due to the use of an injection molding die provided with a special heat insulation layer, it takes time to cool the die, and there is a drawback that the molding cycle becomes long. In Patent Document 3, problems such as appearance defects such as color streaks and color unevenness due to poor dispersibility of carbon black and insufficient scratch resistance of the molded article remain. In Patent Document 4, there are problems with the mechanical strength and light resistance of the molded article due to the polyethylene wax contained in a large amount.

[0008] The present invention has been made in view of the above problems, and an object thereof is to obtain a resin composition that is excellent in the dispersibility of pigments, achieves both a metallic appearance and low weld lines, and can form a molded article with an excellent appearance. A further object is to provide a thermoplastic resin composition having good mechanical properties, scratch resistance, and light resistance.

Means for Solving the Problems

[0009] As a result of intensive studies by the present inventors, it has been found that the problems of the present invention can be solved in the following aspects, and the present invention has been completed. [1] A thermoplastic resin composition containing a brilliant pigment (A), carbon black (B), a polyolefin wax (C), and a polyolefin resin (D), based on 100% by mass of the thermoplastic resin composition, containing 0.1 to 10% by mass of carbon black (B), A thermoplastic resin composition characterized in that the mass ratio (B) / (C) of carbon black (B) to polyolefin wax (C) is 0.1 to 10. [2] The thermoplastic resin composition according to [1], containing 15 to 55% by mass of the brilliant pigment (A) based on 100% by mass of the thermoplastic resin composition. [3] The thermoplastic resin composition according to [1] or [2], wherein the brilliant pigment (A) contains aluminum flakes. [4] The thermoplastic resin according to any one of [1] to [3], wherein the average particle diameter of the brilliant pigment (A) is 5 μm to 100 μm. [5] A molded article formed from the thermoplastic resin composition according to any one of [1] to [4].

Advantages of the Invention

[0010] With the thermoplastic resin composition of the present invention, it is possible to obtain a molded article with excellent pigment dispersibility, suppressing weld lines while maintaining a metallic appearance. Furthermore, a thermoplastic resin composition with good mechanical properties, scratch resistance, and light resistance can be obtained, and the molded article formed from the thermoplastic resin composition is very useful in various fields such as automotive interior and exterior materials, building materials, and the exteriors of household appliances.

Embodiments for Carrying Out the Invention

[0011] Hereinafter, an example of an embodiment to which the present invention is applied will be described. However, the present invention is not limited to this embodiment, and other embodiments can also belong to the scope of the present invention as long as they conform to the gist of the present invention. Also, the numerical range "A to B" specified in this specification means a range that satisfies a value greater than numerical value A and a value smaller than numerical value B. Also, in this specification, "film", "sheet", and "plate" are synonymous and are not distinguished by thickness. In addition, the "thermoplastic resin composition" may be represented as "resin composition", "carbon black" as "CB", "polyolefin wax (C)" as "wax (C)", and "polyolefin resin (D)" as "resin (D)". Unless otherwise noted, each of the various components appearing in this specification may be used alone or in combination of two or more. Note that the numerical values specified in this specification are determined by the methods disclosed in the embodiments or examples.

[0012] ≪Thermoplastic Resin Composition≫ The thermoplastic resin composition of the present invention contains a bright pigment (A), carbon black (B), polyolefin wax (C), and polyolefin resin (D). Further, based on 100% by mass of the thermoplastic resin composition, it contains 0.1 to 10% by mass of carbon black (B), and the content mass ratio (B) / (C) of carbon black (B) and polyolefin wax (C) is 0.1 to 10. By using such a resin composition, it has excellent dispersibility of pigments such as bright pigment (A) and carbon black (B), maintains a metallic appearance, and can suppress weld lines, which are molding defects where the confluence part of the molten resin in the mold forms a linear trace during injection molding. Furthermore, it can be made into a thermoplastic resin composition with good mechanical properties, scratch resistance, and light resistance.

[0013] <Bright Pigment (A)> A bright pigment is a pigment having a pearl-like luster or metallic luster. Examples of the bright pigment (A) of the present invention include metal flakes such as aluminum flakes; metal foils such as aluminum foils; mica such as pearl mica, interference mica, and mica coated with a metal such as titanium dioxide; metal powders such as zinc powder, bronzes powder, stainless steel powder, and aluminum powder; glass flakes coated with a metal (such as silver, silver alloy, etc.) or a metal oxide (such as titanium dioxide), preferably glass flakes coated with titanium dioxide. Preferably, it is selected from the group consisting of metal flakes, pearl mica, interference mica, and glass flakes coated with a metal oxide containing titanium dioxide. From the viewpoint of excellent brightness and suppressing weld lines, aluminum flakes are more preferable.

[0014] The average particle diameter of the bright pigment (A) is preferably 5 to 100 μm, more preferably 20 to 60 μm. When the average particle diameter is 5 μm or more, the generation of weld lines can be further suppressed. When the average particle diameter is 100 μm or less, the bright pigment is not too conspicuous, both the brightness and the weld line can be balanced, and the high-class feeling is not impaired, which is preferable. In addition, the decrease in impact performance can be further suppressed.

[0015] When the bright pigment (A) is in the form of flakes, the thickness in the thickness direction is preferably 0.2 to 10 μm, more preferably 0.7 to 3 μm. When the thickness is 0.2 μm or more, the generation of weld lines can be further suppressed. When the thickness is 10 μm or less, the bright pigment is not too conspicuous, both the brightness and the weld line can be balanced, and the high-class feeling is not impaired, which is preferable. In addition, the decrease in impact performance can be further suppressed. Preferably, the average particle diameter of the bright pigment (A) is 5 to 100 μm and the thickness is 0.2 to 10 μm.

[0016] The average particle and thickness of the bright pigment (A) can be determined by image analysis using a transmission electron microscope. Specifically, it can be determined by the method described in the examples.

[0017] In the present invention, the content of the phosphorescent pigment (A) is preferably 15 to 55% by mass, more preferably 20 to 45% by mass, and still more preferably 25 to 35% by mass based on 100% by mass of the thermoplastic resin composition. When the content of the phosphorescent pigment (A) is 15% by mass or more, a more excellent metallic appearance can be exhibited in the molded article. If the content exceeds 55% by mass, the addition effect of the phosphorescent pigment (A) may saturate. Further, when it is 55% by mass or less, the mechanical properties can be made more excellent.

[0018] <Carbon black (B)> Carbon black is amorphous carbon having conductivity, which is produced by incomplete combustion of oil or gas or by thermal decomposition of hydrocarbons. Carbon black (B) is not particularly limited, and any of acetylene black, furnace black, hollow carbon black, ketjen black, etc. can be used.

[0019] The average particle diameter of the carbon black (B) is preferably 15 nm or more. More preferably, it is 20 to 90 nm, and still more preferably 30 to 40 nm. Generally, as the particle diameter of carbon black decreases, the specific surface area increases, so the light resistance of the molded article tends to improve. On the other hand, as a result, carbon black particles are likely to form aggregates, resulting in a difference in the dispersion state of carbon black in the molded article, and it is easy to form streaks and color unevenness. Therefore, the average particle diameter is preferably 15 nm or more. Further, when the average particle diameter is 90 nm or less, the coloring power of carbon black is sufficiently exhibited. Furthermore, whitening derived from the phosphorescent pigment and the resin when the molded article is damaged can be suppressed, and the scratch resistance can also be further improved. The average particle diameter of carbon black can be determined by image analysis using a transmission electron microscope. Specifically, it can be determined by the method described in the examples.

[0020] In the present invention, the content of carbon black (B) is 0.1 to 10% by mass based on 100% by mass of the thermoplastic resin composition. Preferably it is 0.3 to 8% by mass, more preferably 0.5 to 5% by mass, and still more preferably 1.1 to 5% by mass. If it is less than 0.1% by mass, the light resistance becomes weak, and when the molded product is damaged, whitening derived from the fluorescent pigment and the resin becomes prominent, and the scratch resistance also decreases. If it is 1.1% by mass or more, the generation of weld lines can be more suppressed. If it exceeds 10% by mass, the overall lightness decreases due to the hiding power of carbon black (B), and the luminance sense decreases.

[0021] <Polyolefin wax (C)> The wax is a solid at normal temperature (25°C) and becomes a liquid when heated. The polyolefin wax (C) of the present invention is not particularly limited as long as it is a wax composed of polyolefin.

[0022] From the viewpoints of processability and dispersibility, the melt flow rate (MFR) of the polyolefin wax (C) is preferably more than 100 g / 10 min (MFR, also referred to as melt flow rate and melt viscosity). The melt flow rate (MFR) can be determined in accordance with JIS K-7210. From the viewpoint of pigment dispersibility, the melting point of the polyolefin wax (C) is preferably 130°C or lower. More preferably it is 120°C or lower. Also, it is preferably 70°C or higher. By using the wax (C) having a melting point within the above range, the dispersibility of carbon black (B) is further improved, and the processability during melt-kneading of the thermoplastic resin and the wax also becomes good. The melting point can be determined by a differential scanning calorimeter. Specifically, for example, it can be determined by using a differential scanning calorimeter DSC6200 manufactured by Seiko Instruments Inc., using alumina as a standard substance, measuring in a temperature range of 40 to 200°C at a heating rate of 10°C / min.

[0023] The polyolefin wax (C) of the present invention is a polymer of olefin monomers such as ethylene, propylene, and butylene, and may be a block, random copolymer, or terpolymer. Specifically, it is a polymer of α-olefins such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), and polypropylene (PP). The waxes can be used alone or in combination of two or more.

[0024] The number average molecular weight of the polyolefin wax (C) is preferably from 1,000 to 30,000, more preferably from 2,000 to 25,000. Becomes good. The number average molecular weight can be measured by gel permeation chromatography (GPC method) using polystyrene as a standard substance and tetrahydrofuran as an eluent.

[0025] In the present invention, the content of the polyolefin wax (C) is preferably from 0.1 to 20% by mass, more preferably from 0.5 to 15% by mass, and even more preferably from 1 to 10% by mass based on 100% by mass of the thermoplastic resin composition. When the content of the polyolefin wax (C) is within this range, the mechanical properties and light resistance can be made more excellent.

[0026] The content mass ratio (B) / (C) of the carbon black (B) and the polyolefin wax (C) is preferably from 0.1 to 10, more preferably from 0.3 to 8, and even more preferably from 0.5 to 5. By being within this range, the occurrence of streaks and color unevenness due to poor dispersion of the carbon black (B) can be further reduced, and a molded product with more excellent appearance can be obtained.

[0027] <Polyolefin resin (D)> The polyolefin resin (D) is a polymer mainly composed of olefins, and examples thereof include polyethylene, polypropylene, and polybutene. However, the case of the polyolefin wax (C) is excluded. The polyolefin resin (D) used in the present invention is not particularly limited. Specifically, polypropylene, propylene-ethylene block copolymers, and random copolymers thereof, high-density polyethylene, linear low-density polyethylene, low-density polyethylene, etc., which are widely marketed for injection molding and extrusion molding, can be mentioned. Among these, polypropylene resin is preferred, and propylene-ethylene block copolymer is more preferred because better mechanical strength of the molded product can be obtained.

[0028] From the viewpoints of processability and appearance, the melt flow rate (MFR) of the polyolefin resin (D) (also referred to as melt flow rate and melt viscosity) is preferably 5 to 100 g / 10 min, and more preferably 10 to 60 g / 10 min. The melt flow rate (MFR) can be determined in accordance with JIS K-7210.

[0029] The melting point of the polyolefin resin (D) is preferably above 130°C. Also, it is preferably 180°C or lower, and more preferably 170°C or lower. The melting point can be determined by a differential scanning calorimeter. Specifically, for example, it can be determined by using a differential scanning calorimeter DSC6200 manufactured by Seiko Instruments Inc., using alumina as a standard substance, measuring in the temperature range of 40 to 200°C at a heating rate of 10°C / min.

[0030] In the present invention, the content of the polyolefin resin (D) is preferably 25% by mass or more, more preferably 40% by mass or more, based on 100% by mass of the thermoplastic resin composition. Also, it is preferably 80% by mass or less. By the content of the polyolefin resin (D) being within this range, excellent mechanical properties can be achieved.

[0031] <Other pigments> Within the range that does not impair the effects of the present invention, other pigments such as organic pigments and inorganic pigments other than carbon black (B) and bright pigment (A) can be used according to the required hue. For example, examples of organic pigments include pigments such as azo-based, anthraquinone-based, phthalocyanine-based, quinacridone-based, isoindolinone-based, dioxazine-based, and quinophthalone-based pigments. Examples of inorganic pigments include iron oxide, cobalt blue, ultramarine blue, lead yellow, talc, mica, calcium carbonate, barium sulfate, glass fiber, gypsum, magnesium carbonate, magnesium oxide, and titanium oxide. Among them, talc is preferred.

[0032] <Optional component> In the resin composition of the present invention, within the range that does not inhibit the effects of the present invention, metal soaps of alkali metals, alkaline earth metals or zinc, hydrotalcite, nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, antistatic agents, flame retardants such as halogen-based, phosphorus-based or metal oxides, antioxidants, ultraviolet absorbers, fillers and other additives can be contained as optional components.

[0033] <Method for producing resin composition> The resin composition of the present invention can be produced by blending and mixing the above-described respective compounding components at the above-described compounding ratios and then melt-kneading them. At this time, known methods related to the production of the resin composition can be used. For example, melt-kneading can be carried out using ordinary kneaders such as single-screw extruders, twin-screw extruders, Banbury mixers, roll mixers, Brabender plastographs, kneaders, etc. to knead and granulate into a resin composition in the form of pellets, powders, granules or beads.

[0034] The resin composition may be used in either the form of a masterbatch or a compound. In the case of a compound, after producing the compound, the compound can be used as it is to produce a molded article by the method described below.

[0035] In the case of a masterbatch, after manufacturing the masterbatch, as the main component of the molded article, for example, the same polyolefin resin (D) as that used in the manufacture of the masterbatch can be used as the diluting resin, and the masterbatch can be compounded to manufacture the molded article. As the content of the masterbatch, it is preferably 1 to 15 parts by mass, more preferably 3 to 10 parts by mass, based on 100 parts by mass of the polyolefin resin (D) which is the diluting resin. At this time, the polyolefin resin (D) used as the diluting resin may be the same as that used in the manufacture of the masterbatch or may be different, but it is preferable that they are the same polyolefin resin because the compatibility between the resins is excellent. In the case of the brilliant pigment (A), from the viewpoints of operability and dispersibility, it is preferable to pass through a masterbatch. The content rate of the brilliant pigment (A) is preferably 15 to 65% by mass, more preferably 20 to 55% by mass, based on 100% by mass of the masterbatch, from the viewpoints of impact strength and dispersibility.

[0036] As a mixing method of the brilliant pigment (A), carbon black (B), polyolefin wax (C), and polyolefin resin (D), known methods can be used. For example, a dry grinder such as a fluid energy mill or an impact mill, or a high-speed stirrer such as a Henschel mixer or a super mixer is used to stir and mix the pigment, polyolefin wax (C), and polyolefin resin (D), or a method of melt-kneading using a kneader, a roll mill, a Banbury mixer, etc. can be mentioned.

[0037] ≪Molded article≫ The molded article can be obtained by molding the thermoplastic resin composition of the present invention. The molding method is not particularly limited, and it can be obtained by extrusion molding, compression molding, injection molding, blow molding etc. When the resin composition of the present invention is a masterbatch, it can be kneaded with a diluting resin at a specified magnification during molding of the molded body to form a molded article. The diluting resin may be blended with an inorganic filler and used as a resin composition for dilution. The type of the inorganic filler is not particularly limited, and known inorganic materials can be used.

Examples

[0038] Next, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. Hereinafter, "parts" means parts by mass and "%" means mass %. In addition, the compounding amounts in the table are "parts by mass" and the contents are "mass %", and the blanks in the table indicate that they are not compounded.

[0039] The methods for measuring the number average molecular weight and melting point of the polyolefin wax are as follows. <Number average molecular weight of polyolefin wax> It was measured by gel permeation chromatography (GPC method) using polystyrene as a standard substance and tetrahydrofuran as an eluent.

[0040] <Melting point of polyolefin wax> It was measured with a differential scanning calorimeter DSC6200 manufactured by Seiko Instruments Inc., using alumina as a standard substance, in a temperature range of 40 to 200 °C and at a heating rate of 10 °C / min.

[0041] <Measurement of average particle diameter and thickness of pigment> For the fluorescent pigment (A), the major axis was taken as the particle diameter and the thinnest part was taken as the thickness, and the particle diameters and thicknesses of about 30 particles that could be observed from an enlarged image (for example, 500 to 10,000 times) of a transmission electron microscope (TEM) were measured, and the average value was obtained. The average particle diameters of carbon black (CB) and inorganic pigments were measured by measuring the particle diameters or thicknesses of about 30 particles that could be observed from an enlarged image (for example, 500 to 10,000 times) of a transmission electron microscope (TEM), and the average value was obtained.

[0042] The raw materials used in the examples and comparative examples are shown below. <Fluorescent pigment (A)> (A-1) Metax Neo NME040T3 (aluminum flakes, average thickness 0.9 μm, average particle size 40 μm, manufactured by Toyo Aluminum Co., aluminum concentration = 70%, carrier resin LDPE = 30%) (A-2) Iriodin 153 Flash Pearl (pearl mica, average particle size 100 μm, manufactured by Merck) (A-3) Metax Neo NME060T4 (aluminum flakes, average thickness 1.1 μm, average particle size 60 μm, manufactured by Toyo Aluminum Co., aluminum concentration = 70%, carrier resin LDPE = 30%) (A-4) Metax Neo NME005N1 (aluminum flakes, average thickness 0.2 μm, average particle size 5 μm, manufactured by Toyo Aluminum Co., aluminum concentration = 70%, carrier resin LDPE = 30%) <Carbon Black (B)> (B-1) Mitsubishi Carbon Black #40, average particle size 24 nm

[0043] <Polyolefin Wax (C)> (C-1) Sun Wax 131P (polyethylene wax manufactured by Sanyo Chemical Industries, number average molecular weight 3,500, MFR > 100 g / 10 min, melting point 105 °C) (C-2) Hi Wax NP056 (polypropylene wax manufactured by Mitsui Chemicals, number average molecular weight 7200, MFR > 100 g / 10 min, melting point 130 °C)

[0044] <Polyolefin Resin (D)> (D-1) Sun Allomer PMA60Z (manufactured by Sun Allomer, MFR = 45 g / 10 min) (D-2) Prime Polypro J226T (manufactured by Prime Polymer, melting point 141 °C, MFR = 20 g / 10 min) (D-3) Novatech PP BC03C (manufactured by Japan Polypropylene, melting point 161 °C, MFR = 30 g / 10 min)

[0045] <Other Components> (E-1) Dispersant, calcium stearate (manufactured by Nitto Kasei Kogyo Co.) (E-2) Talc, Micro Ace P-3 (manufactured by Nippon Talc Co., particle size: 5 μm)

[0046] [Production of Dilution Resin Composition] (E-2) 20 parts by mass of talc (Micro Ace P-3, manufactured by Nippon Talc Co., Ltd., average particle diameter 5 μm) and 80 parts by mass of polyolefin resin (D-3) were blended, extruded at 220 °C using a twin-screw extruder (manufactured by Japan Steel Works, Ltd.), pelletized to obtain a pelletized dilution resin composition.

[0047] [Example 1] 40 parts of a bright pigment (A-1) (28 parts of aluminum flakes), 2 parts of carbon black (B-1), 2 parts of polyolefin wax (C-1), and 56 parts of polyolefin resin (D-1) were blended and preliminarily mixed using a Henschel mixer. Subsequently, after melt-kneading at 220 °C using a single-screw extruder with a screw diameter of 30 mm (manufactured by Japan Steel Works), it was pelletized to obtain a pelletized resin composition (F-1).

[0048] [Examples 2 to 12, Examples 14 to 18, Comparative Examples 1 to 3, 5] Pelletized resin compositions (F-2 to 12, F-14 to 21, F-23) were obtained in the same manner as in Example 1, except that the materials and blending amounts (parts by mass) shown in Table 1 were changed respectively.

[0049] [Example 13] 2 parts of a bright pigment (A-1), 0.1 part of carbon black (B-1), 0.2 part of polyolefin wax (C-1), 78.7 parts of polyolefin resin (D-1), and 19 parts of talc as other component (E-2) were blended, melt-kneaded at 220 °C using a twin-screw extruder (manufactured by Japan Steel Works, Ltd.), and then pelletized to obtain a pelletized resin composition (F-13).

[0050] [Comparative Example 4] 40 parts of a bright pigment (A-1), 1 part of carbon black (B-1), 58 parts of polyolefin resin (D-1), and 1 part of optional component (E) were blended and preliminarily mixed using a Henschel mixer. Next, after melt-kneading at 220 °C using a single-screw extruder with a screw diameter of 30 mm (manufactured by Japan Steel Works), it was pelletized to obtain a pelletized resin composition (F-22).

[0051] In Table 1, the “content of (A)” is the content (%) of the luminescent pigment (A) based on 100% by mass of the thermoplastic resin composition, and the “content of (B)” is the content (%) of the carbon black (B) based on 100% by mass of the thermoplastic resin composition.

[0052]

Table 1

[0053] [Evaluation Items and Evaluation Methods] The appearance, mechanical properties, scratch resistance, and light resistance of the thermoplastic resin composition of the present invention were evaluated by the following methods. The results are shown in Table 2. <Preparation of Test Molded Articles> (Test Piece 1) For Examples 1 to 12, Examples 14 to 18, and Comparative Examples 1 to 5, 5 parts of the obtained resin composition and 100 parts of the diluting resin composition were mixed and molded at 220° C. using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) to obtain an appearance test piece 1 having a length of 150 mm, a width of 125 mm, and a thickness of 2.5 mm. The resin composition obtained in Example 13 was directly molded at 220° C. using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) to obtain an appearance test piece 1 having a length of 150 mm, a width of 125 mm, and a thickness of 2.5 mm.

[0054] (Test Piece 2) For Examples 1 to 12, Examples 14 to 18, and Comparative Examples 1 to 5, 5 parts of the obtained resin composition and 100 parts of the diluting resin composition were mixed and molded at 220° C. using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) to obtain a test piece 2 having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm. The resin composition obtained in Example 13 was directly molded at 220° C. using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) to obtain a test piece 2 having a length of 80 mm, a width of 10 mm, and a thickness of 4 mm.

[0055] (Test Piece 3) For Examples 1 to 12, Examples 14 to 18, and Comparative Examples 1 to 5, 5 parts of the obtained resin composition and 100 parts of the resin composition for dilution were mixed, and molded at 220 °C using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) to obtain 3 test pieces with a length of 45 mm × width of 45 mm × thickness of 2.5 mm. The resin composition obtained in Example 13 was directly molded at 220 °C using an injection molding machine (manufactured by Toshiba Machine Co., Ltd.) to obtain 3 test pieces with a length of 45 mm × width of 45 mm × thickness of 2.5 mm.

[0056] <Appearance Evaluation> (Dispersibility) Test piece 1 was observed at a magnification of 50 times using an optical microscope "Digital Microscope VHX-100" (manufactured by Keyence Corporation). The dispersibility was evaluated based on the size of the black dot aggregates observed in the field of view. The better the dispersibility, the fewer large particles there are, and it can be said that the appearance is excellent. [Judgment Criteria] ◎: There are no black dot aggregates of 100 μm or more. Very good 〇: There are black dot aggregates of 100 μm or more, but there are no black dot aggregates of 200 μm or more. Good △: There are black dot aggregates of 200 μm or more, but there are no black dot aggregates of 300 μm or more. Practical level ×: There are black dot aggregates of 300 μm or more in the field of view. Not practical

[0057] (Brightness Sensation) Using test piece 1, the metallic appearance (brightness sensation) was evaluated visually based on the glittery feeling. [Judgment Criteria] ◎: There is a strong glittery feeling with depth. Very good 〇: There is a glittery feeling. Good △: There is a slightly less glittery feeling. Practical level ×: There is almost no glittery feeling. Not practical

[0058] (Weld Line) Using test piece 1, the weld line was evaluated visually. [Judgment Criteria] ◎: Weld line is not noticeable, very good 〇: Weld line can be recognized depending on the viewing angle but is not noticeable, good △: Weld line becomes a black streak and is conspicuous depending on the viewing angle, practical level ×: Weld line is clearly conspicuous as a black streak, not practical

[0059] <Impact strength measurement> The mechanical properties were evaluated by the Charpy impact strength. For test piece 2 and, as a reference, a reference test piece manufactured in the same manner as test piece 2 using only the diluent resin composition, the Charpy impact strength of each was measured according to JIS K7171:2016. From the obtained measured values, the physical property retention rate for each measured value was calculated according to the following formula (1). The higher the value of the physical property retention rate, the better the strength and it can be said to be good. If the evaluation is "△" or higher, breakage of the molded product does not occur. Formula (1) Physical property retention rate (%) = [Charpy impact strength of test piece 2 / Charpy impact strength of reference test piece] × 100 [Judgment criteria] ◎: Physical property retention rate 80% or more, very good 〇: Physical property retention rate is 75% or more and less than 80%, good △: Physical property retention rate is 70% or more and less than 75%, practical level ×: Physical property retention rate is less than 70%, not practical

[0060] <Evaluation of scratch resistance> The surface of test piece 1 was scratched with a scratching needle (SKS2 type tungsten steel needle specified in JISG4404) with a load of 175 g at a scratching speed of 500 mm / min and a pitch of 0.75 mm in the flow direction (MD) using a cross-cut coating peeling tester AD-1110 manufactured by Ueshima Seisakusho Co., Ltd. Five scratches were made. After performing the same test in the direction perpendicular to the flow (TD), the scratch resistance was evaluated visually. [Judgment criteria] ◎: Scratches are not noticeable, very good 〇: Scratches can be recognized depending on the viewing angle, but not noticeable. Good △: Scratches are prominent depending on the viewing angle. Practical level ×: Scratches are clearly prominent. Not practical

[0061] <Light resistance evaluation> Using test piece 3, a sunshine weather meter (model S80, manufactured by Suga Test Instruments Co., Ltd.) was used, with a radiation energy of 255 W / m 2 , a temperature of 63 °C, and a test time of 1000 hours. The color difference (ΔE) on the surface of the sample was measured. The smaller the ΔE, the better the light resistance. The light resistance was evaluated according to the following criteria [Judgment criteria] ◎: After 1000 h, ΔE < 0.5. Very good 〇: After 1000 h, 0.5 ≤ ΔE < 1.0. Good △: After 1000 h, 1.0 ≤ ΔE < 1.5. Practical level ×: After 1000 h, ΔE ≥ 1.5. Not practical

[0062]

Table 2

[0063] As shown in Table 2, by using the resin composition of the present invention, a molded product with excellent dispersibility, a metallic appearance, and an unnoticeable weld line was obtained. Furthermore, it was confirmed that the molded product also had good mechanical properties, light resistance, scratch resistance, and impact resistance.

Claims

1. A thermoplastic resin composition comprising a bright pigment (A), carbon black (B), a polyolefin wax (C), and a polyolefin resin (D), wherein, based on 100% by mass of the thermoplastic resin composition, carbon black (B) is contained in an amount of 0.1 to 10% by mass, and a mass ratio (B) / (C) of carbon black (B) to polyolefin wax (C) is 0.1 to 10, the thermoplastic resin composition being characterized thereby.

2. The thermoplastic resin composition according to Claim 1, wherein, based on 100% by mass of the thermoplastic resin composition, the bright pigment (A) is contained in an amount of 15 to 55% by mass.

3. The thermoplastic resin composition according to Claim 1, wherein the bright pigment (A) contains aluminum flakes.

4. The thermoplastic resin composition according to Claim 1, wherein an average particle diameter of the bright pigment (A) is 5 μm to 100 μm.

5. A molded article formed from the thermoplastic resin composition according to any one of Claims 1 to 4.

Images