Polypropylene resin composition and in-vehicle molded article

Abstract

The present disclosure addresses the problem of providing a polypropylene resin composition having excellent light transmittance, impact resistance, and low shrinkage. The polypropylene resin composition contains a polypropylene resin (A), a styrene-based elastomer (B), and a filler (C). The styrene-based elastomer (B) has a brittle temperature of −25°C or lower. The filler (C) contains scaly glass particles (c1) having an average thickness of 0.1 to 10 μm and an aspect ratio of 1 to 1,000. The content of the scaly glass particles (c1) is 60 mass% or more with respect to the filler (C). The difference in refractive index between the scaly glass particles (c1) and the polypropylene resin (A) is −0.01 to 0.05. The content of the filler (C) is 6 to 30 parts by mass per 100 parts by mass in total of the polypropylene resin (A) and the styrene-based elastomer (B).

Description

Polypropylene resin composition and molded article for vehicle use

[0001] The present disclosure relates generally to a polypropylene resin composition and a molded article for vehicle installation, and more particularly to a polypropylene resin composition and a molded article for vehicle installation comprising the polypropylene resin composition.

[0002] Patent Document 1 discloses a resin composition containing a polypropylene resin, an olefin elastomer, talc, fibrous magnesium sulfate, and a metal soap. The talc has an aspect ratio in the range of 35 to 60. The fibrous magnesium sulfate has an average fiber diameter of 0.1 μm to 2 μm and an average fiber length of 8 μm to 30 μm. The metal soap is at least one of a fatty acid magnesium salt and a fatty acid aluminum salt.

[0003] Patent Document 2 discloses a light-diffusing resin composition containing a polypropylene resin and a silicone powder.

[0004] However, the resin composition described in Patent Document 1 has excellent impact resistance but is insufficient in light transmittance, and the light-diffusing resin composition described in Patent Document 2 is insufficient in impact resistance and low shrinkage.

[0005] Patent No. 7116423 International Publication No. 2023 / 085431

[0006] An object of the present disclosure is to provide a polypropylene resin composition and an in-vehicle molded article that are excellent in light transmittance, impact resistance, and low shrinkage.

[0007] A polypropylene resin composition according to one embodiment of the present disclosure contains a polypropylene resin (A), a styrene-based elastomer (B), and a filler (C). The styrene-based elastomer (B) has a brittle temperature of −25° C. or lower. The filler (C) contains scaly glass particles (c1). The scaly glass particles (c1) have an average thickness t of 0.1 μm or more and 10 μm or less. The ratio of the average particle diameter a to the average thickness t of the scaly glass particles (c1) (aspect ratio: a / t) is 1 or more and 1,000 or less. The content of the scaly glass particles (c1) is 60 mass% or more with respect to the filler (C). The difference (nc1−na) between the refractive index (nc1) of the scaly glass particles (c1) and the refractive index (na) of the polypropylene resin (A) is −0.01 or more and 0.05 or less. The content of the filler (C) is 6 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass in total of the polypropylene resin (A) and the styrene-based elastomer (B).

[0008] An in-vehicle molded article according to one embodiment of the present disclosure includes the polypropylene resin composition.

[0009] Fig. 1 is a schematic diagram of an in-vehicle molded article of the present disclosure. Fig. 2 is a schematic diagram showing a part of the steps related to the method for producing an in-vehicle molded article by film insert molding of the present disclosure. Fig. 3 is a schematic diagram showing a part of the steps related to the method for producing an in-vehicle molded article by film insert molding of the present disclosure. Fig. 4 is a schematic diagram showing a part of the steps related to the method for producing an in-vehicle molded article by film insert molding of the present disclosure. Fig. 5 is a schematic diagram showing a part of the steps related to the method for producing an in-vehicle molded article by film insert molding of the present disclosure.

[0010] [Embodiments] An embodiment of the present disclosure will be described. Note that the present disclosure is not limited to the following embodiments. The following embodiments are merely some of the various embodiments of the present disclosure, and various modifications are possible depending on the design, etc., as long as the object of the present disclosure can be achieved. Furthermore, the mechanism of action described below is a speculation, and the present disclosure is not limited to the explanation of the mechanism of action below. Furthermore, the figures referred to below are schematic diagrams, and the structures or dimensional ratios of the components in the figures do not necessarily reflect the actual structures or dimensional ratios.

[0011] 1. Overview The polypropylene resin composition according to this embodiment (hereinafter also referred to as composition (X)) contains a polypropylene resin (A), a styrene-based elastomer (B), and a filler (C). Although details will be described later, in this embodiment, the quantitative relationship between the above three components, the physical properties of the styrene-based elastomer (B), the type of filler (C), etc. are specified.

[0012] Therefore, according to this embodiment, a molded article 1 for vehicle installation (hereinafter also referred to as molded article (Y)) having excellent light transmittance, impact resistance, and low shrinkage can be produced from composition (X).

[0013] 2. Details (Components) The components contained in composition (X) will be described in detail.

[0014] <Polypropylene Resin (A)> The composition (X) contains a polypropylene resin (A). The polypropylene resin (A) imparts high impact resistance to the composition (X). In addition, the polypropylene resin (A) suppresses a decrease in the light transmittance of the composition (X).

[0015] The polypropylene resin (A) is a polymer having structural units derived from propylene monomers. The polypropylene resin (A) is not particularly limited, but examples thereof include homopolypropylene, random polypropylene, and block polypropylene.

[0016] The homopropylene is a homopolymer obtained by polymerizing propylene alone.

[0017] The random polypropylene is a copolymer obtained by copolymerizing propylene with an olefinic hydrocarbon such as ethylene / butylene.

[0018] The block polypropylene is a copolymer obtained by polymerizing homopolypropylene and subsequently copolymerizing a hydrocarbon such as propylene and ethylene in the presence of the homopolypropylene.

[0019] The degree of polymerization (molecular weight), stereoregularity, etc. of the polypropylene resin (A) are not particularly limited.

[0020] The polypropylene resin (A) preferably contains at least one of homopolypropylene and random polypropylene. The content of the polypropylene resin (A) is preferably 60% by mass or more, more preferably 75% by mass or more, based on the total of the polypropylene resin (A) and the styrene-based elastomer (B). In this case, the decrease in light transmittance of the composition (X) can be suppressed and the impact resistance can be increased. The content of the polypropylene resin (A) is preferably 90% by mass or less, more preferably 85% by mass or less, based on 100% by mass of the total of the polypropylene resin (A) and the styrene-based elastomer (B). In this case, the decrease in light transmittance of the composition (X) can be suppressed and the impact resistance can be increased.

[0021] The refractive index (na) of the polypropylene resin (A) is preferably 1.47 or more. The refractive index (na) of the polypropylene resin (A) is preferably 1.51 or less. If the refractive index (na) is within the above numerical range, a decrease in the light transmittance of the composition (X) can be suppressed.

[0022] <Styrene-based elastomer (B)> The composition (X) contains a styrene-based elastomer (B). The styrene-based elastomer (B) imparts high impact resistance to the composition (X). In addition, the styrene-based elastomer (B) suppresses a decrease in the light transmittance of the composition (X).

[0023] The styrene-based elastomer (B) is a polymer having structural units derived from styrene monomers. Examples of the styrene-based elastomer (B) include, but are not limited to, copolymers in which the hard segment contains styrene and the soft segment contains butadiene, hydrogenated butadiene, isoprene, hydrogenated isoprene, ethylene, ethylene / butylene, ethylene / octene, ethylene / butylene / butadiene, or other olefinic hydrocarbons. The styrene-based elastomer (B) may be hydrogenated or non-hydrogenated. Here, "hydrogenation" refers to hydrogenation or hydrogen addition.

[0024] The brittle temperature of the styrene elastomer (B) is −25° C. or lower, preferably −30° C. or lower, and more preferably −40° C. or lower, in which case the impact resistance of the composition (X) can be increased under low temperature conditions.

[0025] The content of the styrene-derived structure in the styrene-based elastomer (B) is preferably 10% by mass or more, more preferably 13% by mass or more, and even more preferably 15% by mass or more. In this case, the impact resistance of the composition (X) can be increased. The content of the styrene-derived structure in the styrene-based elastomer (B) is preferably 25% by mass or less, more preferably 20% by mass or less. In this case, the styrene-based elastomer (B) is compatible with the polypropylene resin (A), and a decrease in the light transmittance of the composition (X) can be suppressed.

[0026] <Filler (C)> The composition (X) contains a filler (C). The filler (C) suppresses a decrease in the light transmittance of the composition (X). Furthermore, the filler (C) suppresses a decrease in the shrinkage of the composition (X) and the molded article (Y).

[0027] The filler (C) contains scaly glass particles (c1). Here, "scaly" refers to a thin, plate-like shape, such as a flake or flat shape. The planar shape is not particularly limited, but examples include circular, elliptical, rectangular, and irregular shapes. The scaly glass particles (c1) have a large surface area and are laminated within the composition (X), as described above, and therefore can suppress a decrease in the molding shrinkage and anisotropy of the composition (X).

[0028] The average thickness t of the scaly glass particles (c1) is 0.1 μm or more, preferably 0.5 μm or more, and more preferably 1.0 μm or more. The average thickness t of the scaly glass particles (c1) is 10 μm or less, preferably 5 μm or less, and more preferably 2 μm or less. Here, the average thickness t refers to the length of the short side of the scaly glass particles (c1). The measurement method can be, for example, to select any number of scaly glass particles (c1) from a scanning electron microscope image and calculate the arithmetic average of the lengths of the short sides of each.

[0029] The ratio of the average particle diameter a to the average thickness t of the scaly glass particles (c1) (aspect ratio: a / t) is 1 or more, preferably 2 or more, more preferably 30 or more, and even more preferably 100 or more. In this case, deterioration in the shrinkage and anisotropy of the composition (X) and the molded article (Y) can be suppressed. Furthermore, the aspect ratio is 1,000 or less, preferably 700 or less, and more preferably 500 or less. In this case, deterioration in the shrinkage and anisotropy of the composition (X) and the molded article (Y) can also be suppressed. Here, the average particle diameter a is the volume-based median diameter (D50). The median diameter (D50) is calculated from the particle size distribution obtained by measurement using a laser diffraction / scattering method. The particle size distribution can be measured, for example, using a laser diffraction particle size distribution analyzer. The aspect ratio here is the value obtained by dividing the average particle diameter a of the scaly glass particles (c1) by the average thickness t.

[0030] The content of the scaly glass particles (c1) relative to the filler (C) is 60% by mass or more, preferably 65% ​​by mass or more, and more preferably 70% by mass or more, which can suppress a decrease in the shrinkage of the composition (X) and the molded article (Y).

[0031] The refractive index (nc1) of the scaly glass particles (c1) and the refractive index (na) of the polypropylene resin (A) are physical properties related to the light transmittance of the composition (X). It is most preferable that the refractive index (nc1) of the scaly glass particles (c1) and the refractive index (na) of the polypropylene resin (A) are the same, with no difference between them. In this case, good light transmittance is imparted to the composition (X). The difference (nc1-na) between the refractive index (nc1) of the scaly glass particles (c1) and the refractive index (na) of the polypropylene resin (A) is -0.01 or more. In this case, a decrease in the light transmittance of the composition (X) can be suppressed. Furthermore, the refractive index difference is 0.05 or less, preferably 0.03 or less, and more preferably 0.02 or less. In this case, a decrease in the light transmittance of the composition (X) can also be suppressed. Here, the refractive index refers to the refractive index when light with a wavelength of 587 nm is irradiated onto the object to be measured. Measurement can be performed, for example, using an Abbe refractometer.

[0032] The content of the filler (C) is 6 parts by mass or more, preferably 10 parts by mass or more, more preferably 15 parts by mass or more, per 100 parts by mass of the total of the polypropylene resin (A) and the styrene-based elastomer (B). In this case, a decrease in the shrinkability of the composition (X) and the molded article (Y) can be suppressed. The content of the filler (C) is 30 parts by mass or less, preferably 27 parts by mass or less, more preferably 25 parts by mass or less, per 100 parts by mass of the total of the polypropylene resin (A) and the styrene-based elastomer (B). In this case, a decrease in the light transmittance of the composition (X) can be suppressed.

[0033] The refractive index (nc1) of the scaly glass particles (c1) is preferably 1.47 or more, more preferably 1.48 or more, and even more preferably 1.49 or more. The refractive index (nc1) of the scaly glass particles (c1) is preferably 1.53 or less, more preferably 1.52 or less, and even more preferably 1.51 or less. Within the above numerical range, a decrease in the light transmittance of the composition (X) can be suppressed.

[0034] The filler (C) may contain only the scaly glass particles (c1), or may further contain fillers other than the scaly glass particles (c1). The fillers other than the scaly glass particles (c1) may contain at least one of an inorganic filler and an organic filler. Examples of inorganic fillers include, but are not limited to, glass, talc, silica, barium sulfate, alumina, glass beads, glass balloons, calcium carbonate, zinc sulfide, and titanium oxide. Examples of organic fillers include, but are not limited to, silicone powder, polystyrene particles, and polymethyl methacrylate particles. The shape of the other fillers is not particularly limited, but may be, for example, spherical, fibrous, acicular, plate-like, crushed, or irregular.

[0035] (Physical Properties of Polypropylene Resin Composition) The physical properties of the composition (X) and molded article (Y) according to this embodiment will be described.

[0036] <Production Method> The production method of the composition (X) is not particularly limited, and examples thereof include a method in which the polypropylene resin (A), the styrene-based elastomer (B), and the filler (C) are melt-kneaded, and if necessary, pulverized and pelletized. In the case of pelletization, the size and shape of the resulting pellets are not particularly limited.

[0037] The melt-kneading device is not particularly limited, but examples thereof include a kneading granulator, a single-screw extruder, a multi-screw extruder, a co-kneader, a roll mill, and a Banbury mixer.

[0038] The molded article (Y) of this embodiment is produced from a substrate layer 11 containing the composition (X) of this embodiment and a film layer 12 .

[0039] The method for producing the molded article (Y) is not particularly limited, but examples thereof include film insert molding, in-mold molding, multi-material injection molding, and TOM molding.

[0040] The film layer 12 may have a surface decorated to improve design, impart functionality, or the like, although there are no particular limitations thereon.

[0041] The term "decorating" as used herein refers to adding design, functionality, etc. to the surface of the film layer 12 by painting, plating, printing, coloring, etc.

[0042] Furthermore, the film layer 12 may or may not have an adhesive layer 13 on the surface on which the base layer 11 is overlaid, in order to improve adhesion to the base layer 11 containing the composition (X).

[0043] The film layer 12 is not particularly limited, but examples thereof include an acrylic film, a polycarbonate film, a polyolefin film, a polyethylene film, a polyamide film, a polyimide film, a polystyrene film, a polyethylene terephthalate film, and a thermoplastic urethane film.

[0044] The adhesive layer 13 is not particularly limited, but examples thereof include olefin-based resins.

[0045] Here, an example of a method for producing the molded article (Y) will be described with reference to Fig. 1 and Fig. 2 to Fig. 5. Fig. 1 shows an example of the molded article (Y). Fig. 2 to Fig. 5 show each step of producing an on-vehicle molded article 1 by film insert molding.

[0046] First, the structure of the molded article (Y) will be described. As shown in Fig. 1, the molded article (Y) is configured so that a substrate layer 11 containing the composition (X), an adhesive layer 13, and a film layer 12 are stacked in this order. In this manner, the substrate layer 11 and the film layer 12 are bonded together by the adhesive layer 13.

[0047] Next, a method for producing the molded product (Y) by film insert molding using an injection mold 2 will be described. The injection mold 2 is composed of a first injection mold 21 (core side) and a second injection mold 22 (cavity side). The first injection mold 21 has a spool 23.

[0048] First, a film layer 12 is prepared that has been pre-formed and trimmed to the shape of the molded product (Y) to be completed (a generally U-shaped cross section). This film layer 12 has an adhesive layer 13 on the surface that overlaps with the base layer 11 (the inner surface facing right in FIG. 2). The film layer 12 is inserted into a heated second injection mold 22 (see FIG. 2).

[0049] Next, the heated first injection mold 21 is brought close to the second injection mold 22, and the molds are clamped. At this time, a space into which the composition (X) flows exists between the surface of the film layer 12 on the adhesive layer 13 side and the first injection mold 21 (see FIG. 3).

[0050] Next, pellets of the composition (X) are placed in an injection molding machine and heated to melt them, and then the heated and melted composition (X) is injected through the spool 23 of the first injection mold 21 to fill the space above (see FIG. 4).

[0051] Thereafter, the injection mold 2 is sufficiently cooled to solidify the composition (X) filled in the space. The mold is then opened, and the molded article (Y) is removed from the injection mold 2. In this manner, the molded article (Y) is obtained (see FIG. 5).

[0052] <Light Transmittance> The composition (X) exhibits good light transmittance. For example, as a specific physical property value, a total light transmittance of 65% or more is preferred. Details of the method for measuring the total light transmittance are shown in the Examples.

[0053] <Impact Resistance> Composition (X) exhibits good impact resistance at room temperature and at low temperature. Here, room temperature and low temperature refer to 23°C and -30°C, respectively. For example, specific physical property values ​​include Charpy impact strengths of 5 kJ / m at 23°C and -30°C, respectively. ２ or more and 3 kJ / m ２ The details of the method for measuring the Charpy impact strength are shown in the Examples.

[0054] <Low Shrinkage> The composition (X) and the molded article (Y) exhibit good low shrinkage, where low shrinkage refers to the molding shrinkage rate and flatness.

[0055] <<Molding shrinkage>> Composition (X) exhibits a good molding shrinkage. For example, the molding shrinkage in the parallel and perpendicular directions is preferably 1.7% or less. Details of the method for measuring the molding shrinkage are given in the Examples.

[0056] <Flatness> The molded article (Y) comprises a substrate layer 11 containing at least the composition (X) and a film layer 12, and the cooling rates of each layer vary depending on the material, molding conditions, etc. Generally, the slower the cooling rate, the greater the molding shrinkage. Here, if there is a difference in the cooling rates between the substrate layer 11 and the film layer 12 of the molded article (Y), the molding shrinkage rates of the two layers will differ, resulting in warpage, deformation, dents, etc., and thus poor flatness. The molded article (Y) of the present disclosure exhibits good flatness. For example, if the molded article (Y) is placed on a smooth and level surface (horizontal surface), and viewed from the side, the distance between the molded article (Y) and the horizontal surface due to warpage of the molded article (Y) is 0.5 mm or less, it can be said to have good flatness. Details of the flatness measurement method are shown in the examples.

[0057] 3. Aspects As is clear from the above embodiments, the present disclosure includes the following aspects. In the following, reference numerals are given in parentheses only to clarify the correspondence with the embodiments.

[0058] The polypropylene resin composition according to the first aspect contains a polypropylene resin (A), a styrene-based elastomer (B), and a filler (C), wherein the styrene-based elastomer (B) has a brittle temperature of −25° C. or lower, the filler (C) contains scaly glass particles (c1), and the scaly glass particles (c1) have an average thickness t of 0.1 μm or more and 10 μm or less, and the ratio of the average particle diameter a to the average thickness t of the scaly glass particles (c1) (aspect ratio: a / t) is , 1 or more and 1000 or less, the content of the scaly glass particles (c1) is 60 mass% or more relative to the filler (C), the difference (nc1-na) between the refractive index (nc1) of the scaly glass particles (c1) and the refractive index (na) of the polypropylene resin (A) is -0.01 or more and 0.05 or less, and the content of the filler (C) is 6 parts by mass or more and 30 parts by mass or less relative to 100 parts by mass in total of the polypropylene resin (A) and the styrene-based elastomer (B).

[0059] According to the first aspect, it is possible to suppress a decrease in the light transmittance of the polypropylene resin composition, to increase the impact resistance under normal temperature conditions and low temperature conditions, and to suppress a decrease in shrinkage.

[0060] In the second aspect, in the first aspect, the content of the polypropylene resin (A) is 60% by mass or more and 90% by mass or less with respect to the total of the polypropylene resin (A) and the styrene-based elastomer (B).

[0061] According to the second aspect, the decrease in light transmittance of the polypropylene resin composition can be further suppressed, and the impact resistance under room temperature conditions and low temperature conditions can be further improved.

[0062] In a third aspect, in the first or second aspect, the polypropylene resin (A) contains at least one selected from a homopolypropylene resin and a random polypropylene resin.

[0063] According to the third aspect, it is possible to further suppress the decrease in light transmittance of the polypropylene resin composition and further increase the impact resistance.

[0064] In a fourth aspect, in any one of the first to third aspects, the refractive index (nc1) of the scaly glass particles (c1) is 1.47 or more and 1.53 or less.

[0065] According to the fourth aspect, the decrease in light transmittance of the polypropylene resin composition can be further suppressed.

[0066] In a fifth aspect, in any one of the first to fourth aspects, the refractive index (na) of the polypropylene resin (A) is 1.47 or more and 1.51 or less.

[0067] According to the fifth aspect, the decrease in light transmittance of the polypropylene resin composition can be further suppressed.

[0068] In a sixth aspect, in any one of the first to fifth aspects, the content of the styrene-derived structure in the styrene-based elastomer (B) is 10% by mass or more and 25% by mass or less.

[0069] According to the sixth aspect, the decrease in light transmittance of the polypropylene resin composition can be further suppressed.

[0070] The molded article (1) for vehicle installation according to the seventh aspect contains the polypropylene resin composition according to any one of the first to sixth aspects.

[0071] The molded article (1) for mounting on a vehicle according to the eighth aspect includes a substrate layer (11) and a film layer (12) laminated on the substrate layer (11). The substrate layer (11) contains a polypropylene resin composition according to any one of the first to sixth aspects.

[0072] More specific examples of this embodiment will be presented below, but the present disclosure is not limited to the following examples.

[0073] The raw materials used in the examples and comparative examples are as follows.

[0074] (1) Polypropylene resin - Polypropylene resin #1: homopolypropylene resin, refractive index 1.49, manufactured by Prime Polymer Co., Ltd., product name "J106MG" - Polypropylene resin #2: random polypropylene resin, refractive index 1.49, manufactured by Japan Polypropylene Corporation, product name "MG03BD".

[0075] (2) Styrene-based elastomers - Styrene-based elastomer #1: styrene-derived structure content 18% by mass, brittle temperature -32°C, manufactured by Asahi Kasei Corporation, product name "Tuftec H1062" - Styrene-based elastomer #2: styrene-derived structure content 12% by mass, brittle temperature -21°C, manufactured by Asahi Kasei Corporation, product name "Tuftec H1221".

[0076] (3) Filler - Filler #1: C glass flake, refractive index 1.51, average thickness 2 μm, aspect ratio 130, manufactured by Nippon Sheet Glass Co., Ltd., product name "RCF-2300" - Filler #2: C glass flake, refractive index 1.51, average thickness 5 μm, aspect ratio 32, manufactured by Nippon Sheet Glass Co., Ltd., product name "RCF-160A" - Filler #3: special glass, refractive index 1.50, average thickness 5 μm, aspect ratio 2 - Filler #4: E glass flake, refractive index 1.55, average thickness 0.7 μm, aspect ratio 229, manufactured by Nippon Sheet Glass Co., Ltd., product name "MEG160FY-M04" - Filler #5: talc, refractive index 1.57, average thickness 7 μm, manufactured by Takehara Chemical Industry Co., Ltd., product name "TT Talc" Filler #6: spherical silica, refractive index 1.46, average thickness 12 μm, aspect ratio 1, manufactured by Denka Co., Ltd., product name "FB-105FC" Filler #7: glass beads, refractive index 1.55, average thickness 30 μm, manufactured by Potters Ballotini Co., Ltd., product name "EGB731A".

[0077] Example 1 75 parts by mass of polypropylene resin, 15 parts by mass of styrene-based elastomer, and 10 parts by mass of filler were blended and melt-kneaded at 200° C. in a kneading granulator to obtain pellets of a polypropylene resin composition.

[0078] Next, the pellets of the polypropylene resin composition and the film layer were placed in an injection molding machine and injection molding was carried out at 200° C. to obtain a molded article for use in a vehicle.

[0079] (Examples 2-10, Comparative Examples 1-8) Polypropylene resin compositions and automotive molded articles were obtained in the same manner as in Example 1, except that the blending amounts of the polypropylene resin, the styrene-based elastomer, and the filler were changed as shown in Table 1 below.

[0080] (Evaluation Test) The polypropylene resin compositions obtained in the Examples and Comparative Examples were evaluated as follows.

[0081] (1) Total Light Transmittance Test pieces measuring 60 mm x 60 mm x 2 mm were prepared from the obtained polypropylene resin composition under the conditions of a mold temperature of 40°C, an injection pressure of 50 to 70 MPa, and a holding time of 10 seconds. The total light transmittance of the prepared test pieces was measured in accordance with JIS K7136 using a measuring device model "NDH5000" manufactured by Nippon Denshoku Industries Co., Ltd. The values ​​obtained by the measurement are shown in Table 1.

[0082] (2) Charpy Impact Strength ISO multipurpose test pieces A were prepared from the obtained polypropylene resin composition under the conditions of a mold temperature of 40°C, an injection pressure of 60 to 80 MPa, and a holding time of 40 seconds. The Charpy impact strength of the prepared test pieces was measured at 23°C and -30°C in accordance with ISO 179 using a "Digital Impact Tester DG-UB" manufactured by Toyo Seiki Seisaku-sho, Ltd. as a measuring device. The values ​​obtained by the measurement are shown in Table 1.

[0083] (3) Mold shrinkage rate Test pieces measuring 60 mm x 60 mm x 2 mm were prepared from the obtained polypropylene resin composition under the conditions of a mold temperature of 40°C, an injection pressure of 50 to 70 MPa, and a holding time of 10 seconds. The mold shrinkage rates of the prepared test pieces in the parallel and perpendicular directions to the test pieces were measured in accordance with ISO 294-4. The values ​​obtained by the measurement are shown in Table 1.

[0084] (4) Flatness Test pieces measuring 60 mm x 60 mm x 2 mm were prepared from the obtained polypropylene resin composition and film (material: polypropylene resin, manufactured by Sanvic Co., Ltd.) under conditions of a mold temperature of 40°C, an injection pressure of 50 to 70 MPa, and a holding time of 10 seconds. The prepared test pieces were placed on a smooth and level surface (horizontal surface) with the thickness direction of the test piece facing up and down. The placed test piece was viewed from the side (thickness surface of the test piece), and the distance at which the test piece was furthest from the horizontal surface due to warping of the test piece was measured using a vernier caliper. A distance of 0.5 mm or less was considered to be good flatness, with good flatness being rated "A" and poor flatness being rated "B." The evaluation results are shown in Table 1.

[0085]

[0086] REFERENCE SIGNS LIST 1 molded article for vehicle use 11 substrate layer 12 film layer 13 adhesive layer 2 injection molding die

Claims

1. A polypropylene resin (A), a styrene-based elastomer (B), and a filler (C), wherein the styrene-based elastomer (B) has a brittle temperature of -25°C or lower, the filler (C) contains scaly glass particles (c1), the average thickness t of the scaly glass particles (c1) is 0.1 μm or more and 10 μm or less, the ratio of the average particle diameter a to the average thickness t of the scaly glass particles (c1) (aspect ratio: a / t) is 1 or more and 1,000 or less, the content of the scaly glass particles (c1) is 60 mass% or more relative to the filler (C), and the difference (nc1 - na) between the refractive index (nc1) of the scaly glass particles (c1) and the refractive index (na) of the polypropylene resin (A) is -0.01 or more and 0.05 or less, A polypropylene resin composition, wherein the content of the filler (C) is 6 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the total of the polypropylene resin (A) and the styrene-based elastomer (B).

2. The polypropylene resin composition according to claim 1, wherein the content of the polypropylene resin (A) is 60% by mass or more and 90% by mass or less based on the total of the polypropylene resin (A) and the styrene-based elastomer (B).

3. The polypropylene resin composition according to claim 1, wherein the polypropylene resin (A) contains at least one selected from a homopolypropylene resin and a random polypropylene resin.

4. The polypropylene resin composition according to claim 1, wherein the refractive index (nc1) of the scaly glass particles (c1) is 1.47 or more and 1.53 or less.

5. The polypropylene resin composition according to claim 1, wherein the refractive index (na) of the polypropylene resin (A) is 1.47 or more and 1.51 or less.

6. The polypropylene resin composition according to claim 1, wherein the content of the styrene-derived structure in the styrene-based elastomer (B) is 10% by mass or more and 25% by mass or less.

7. A molded article for use in a vehicle, comprising the polypropylene resin composition according to any one of claims 1 to 6.

8. A molded article for use in a vehicle, comprising a substrate layer and a film layer superimposed on the substrate layer, wherein the substrate layer contains the polypropylene resin composition according to any one of claims 1 to 6.

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