Resin composition, molded article, and multilayer sheet

Abstract

Provided are a resin composition having good moldability and the ability to suppress breakage of a resin during molding, and a molded article and a multilayer sheet containing the resin composition.　The present invention is a resin composition comprising an eggshell powder (A) and a styrene-based thermoplastic elastomer (B), wherein the content of the eggshell powder (A) relative to the total mass of the resin composition is 5-75 mass%, the content of the styrene-based thermoplastic elastomer (B) is 25-95 mass%, the melt flow rate of the resin composition at a temperature of 200°C and a load of 5 kg is 0.5-15 g / 10 min, and the tensile elongation at break as measured according to ASTM-D638 is 20-230%.

Description

Resin composition, molded article, and laminated sheet

[0001] The present invention relates to a resin composition, a molded article, and a laminate sheet.

[0002] In recent years, environmental issues such as global warming have become a focus of attention, and attempts have been made to use naturally derived materials as inorganic fillers in resin compositions. For example, Patent Document 1 describes a method for producing a resin composition by kneading inorganic fine particle aggregates derived from inorganic waste with a resin raw material. Patent Document 2 describes a resin composition containing a thermoplastic resin and eggshell powder having predetermined physical properties in a predetermined mass ratio.

[0003] JP 2011-256260 A JP 2021-152129 A

[0004] Polystyrene resin is a typical thermoplastic resin that is highly transparent, moldable, and inexpensive, and therefore widely used in a variety of applications, such as home appliance parts, automotive interior materials, building materials, food containers, packaging materials, and toys. However, polystyrene resin is highly brittle, and is therefore prone to breakage when pulled or impacted, especially when molded into a sheet. Furthermore, resin compositions containing polystyrene resin and eggshell powder exhibit even greater brittleness, making the resin less likely to stretch and also reducing its flowability. When such resin compositions are molded into a sheet, for example, by extrusion molding, it is difficult to obtain the desired moldability, and there is a risk of the resin breaking during molding.

[0005] An object of the present invention is to provide a resin composition that has good moldability and can suppress breakage of the resin during molding, as well as a molded article and a laminate sheet that contain the resin composition.

[0006] As a result of extensive research, the present inventors have found that the above-mentioned problems can be solved by a resin composition including the following aspects: [1] A resin composition comprising eggshell powder (A) and a styrene-based thermoplastic elastomer (B), wherein the content of the eggshell powder (A) is 5 to 75 mass% and the content of the styrene-based thermoplastic elastomer (B) is 25 to 95 mass% relative to the total mass of the resin composition, and the resin composition has a melt flow rate of 0.5 to 15 g / 10 min at 200°C under a 5 kg load, and a tensile elongation at break of 20 to 230% as measured in accordance with ASTM-D638.

[0007] According to the present invention, it is possible to provide a resin composition that has good moldability and can suppress breakage of the resin during molding, as well as a molded article and a laminate sheet that include the resin composition.

[0008] 1A and 1B are explanatory views of a layer structure of a laminate sheet according to one embodiment and a layer structure of a laminate sheet according to another embodiment.

[0009] An embodiment of the present invention will be described in detail below, but the scope of the present invention is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present invention. Furthermore, when multiple upper and lower limit values ​​are described for a specific parameter, any upper and lower limit values ​​can be combined to form a suitable numerical range. The expression "α to β" indicating a numerical range means "above α and below β." When a specific description given for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0010] The configurations and combinations thereof in each embodiment are merely examples, and additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate without departing from the spirit of the present disclosure. The present disclosure is not limited to the embodiments. Each aspect disclosed in this specification can be combined with any other feature disclosed in this specification.

[0011] [Resin Composition] A first embodiment of the present disclosure relates to a resin composition. The resin composition according to the first embodiment comprises eggshell powder (A) and a styrene-based thermoplastic elastomer (B), wherein the content of the eggshell powder (A) is 5 to 75 mass% and the content of the styrene-based thermoplastic elastomer (B) is 25 to 95 mass% relative to the total mass of the resin composition, and the resin composition has a melt flow rate of 0.5 to 15 g / 10 min at 200°C under a 5 kg load and a tensile elongation at break of 20 to 230% as measured in accordance with ASTM-D638.

[0012] The resin composition according to the first embodiment contains predetermined amounts of eggshell powder (A) and styrene-based thermoplastic elastomer (B), and the melt flow rate (MFR) and tensile elongation at break of the resin composition fall within predetermined ranges, thereby enabling it to have good moldability. Furthermore, such a resin composition can suppress breakage of the resin during molding (particularly during extrusion molding). Furthermore, since the resin composition contains a specific amount of eggshell powder (A), it is possible to utilize naturally derived materials and effectively utilize waste materials such as food waste, thereby contributing to reducing environmental impact.

[0013] MFR The resin composition according to the first embodiment has an MFR at 200°C under a 5 kg load (hereinafter referred to as "MFR (200°C, 5 kg load)") of 0.5 to 15 g / 10 min. When the resin composition has an MFR (200°C, 5 kg load) of 0.5 to 15 g / 10 min, the fluidity required for extrusion molding can be ensured, resulting in good moldability. That is, when the MFR (200°C, 5 kg load) is 0.5 g / 10 min or more, it is possible to prevent the fluidity from becoming too low, which would make it difficult to produce a sheet-shaped molded product. When the MFR (200°C, 5 kg load) is 15 g / 10 min or less, it is possible to prevent drawdown (a phenomenon in which the resin cannot withstand its own weight when heated, resulting in uneven thickness) during molding, particularly extrusion molding, which makes it impossible to produce a uniform sheet.

[0014] In one embodiment, the MFR (200°C, 5 kg load) of the resin composition is preferably 0.5 to 12 g / 10 min, more preferably 1.0 to 11 g / 10 min, and even more preferably 1.5 to 10.5 g / 10 min, from the viewpoint of improving fluidity during molding. In a more preferred embodiment, the MFR (200°C, 5 kg load) of the resin composition may be 1.5 to 6.5 g / 10 min, 2.0 to 6.5 g / 10 min, or 2.5 to 6.0 g / 10 min. The MFR of the resin composition is a value measured in accordance with JIS K 7210-2:2014 (ISO 1133-2:2011).

[0015] The MFR (200°C, 5 kg load) of the resin composition according to the first embodiment can be adjusted to fall within the above range by adjusting the amount of eggshell powder (A) in the resin composition, adjusting the amount of styrene-based thermoplastic elastomer (B), combining multiple styrene-based thermoplastic elastomers (B), or the like. For example, increasing the blending ratio of eggshell powder (A) tends to lower the MFR (200°C, 5 kg load) of the resin composition, whereas decreasing the blending ratio of eggshell powder (A) tends to increase the MFR (200°C, 5 kg load) of the resin composition. For example, when the resin composition contains 50% by mass or more of eggshell powder (A), the MFR (200°C, 5 kg load) value tends to decrease further. Therefore, in order to achieve the desired MFR (200°C, 5 kg load), it is preferable to blend a specific amount of a styrene-butadiene block copolymer as the styrene-based thermoplastic elastomer (B). It is more preferable to combine two or more types of styrene-based thermoplastic elastomers (B), and it is even more preferable to combine two or more types of styrene-butadiene block copolymers. When the resin composition contains less than 50% by mass of eggshell powder (A), it is relatively easy to adjust the MFR (200°C, 5 kg load), so the amount of styrene-based thermoplastic elastomer (B) may be adjusted from the viewpoint of controlling the tensile elongation at break to a high level.

[0016] Tensile Break Elongation The resin composition according to the first embodiment has a tensile break elongation of 20 to 230% as measured according to ASTM-D638. If the resin composition has a tensile break elongation of 20% or more, breakage of the resin can be suppressed during molding, particularly extrusion molding. From this viewpoint, the tensile break elongation of the resin composition is preferably 25% or more, more preferably 30% or more, even more preferably 35% or more, and particularly preferably 40% or more. Furthermore, if the resin composition has a tensile break elongation of 230% or less, drawdown (a phenomenon in which the resin cannot withstand its own weight when heated, resulting in thickness deviation) can be prevented during molding, particularly extrusion molding, which makes it impossible to form a uniform sheet. From this viewpoint, the tensile break elongation of the resin composition is preferably 190% or less, more preferably 170% or less, even more preferably 150% or less, even more preferably 130% or less, and particularly preferably 120% or less.

[0017] In the resin composition according to the first embodiment, the tensile elongation at break can be adjusted by the blending amount of the styrene-based thermoplastic elastomer (B). In one embodiment, when the content of eggshell powder (A) in the resin composition is 50% by mass or more, it is preferable that the thermoplastic resin contains only the styrene-based thermoplastic elastomer (B) and does not contain any other styrene-based resins. This configuration makes it easier to adjust the tensile elongation at break to the above range.

[0018] <Eggshell powder (A)> The raw material of the eggshell powder (A) is not particularly limited as long as it is obtained by powdering eggshells, but eggshells from animals are preferred, and eggshells from chickens are more preferred. From the viewpoint of further reducing the environmental load, eggshells from waste are preferred, and eggshells from food waste may also be used.

[0019] The content of eggshell powder (A) is 5 to 75% by mass, relative to the total mass of the resin composition. In one embodiment, from the viewpoints of easily obtaining a molded article with a uniform film thickness and easily obtaining a high tensile modulus of elasticity of the resulting molded article, the content of eggshell powder (A) relative to the total mass of the resin composition is preferably 5% by mass or more but less than 50% by mass, more preferably 5 to 45% by mass, even more preferably 6 to 45% by mass, and particularly preferably 7 to 40% by mass. Note that, from the viewpoint of obtaining a molded article with a lower environmental impact, it is preferable to set the content of eggshell powder (A) in the resin composition to a high level. From this viewpoint, the content of eggshell powder (A) relative to the total mass of the resin composition is preferably 50 to 75% by mass, more preferably more than 50% by mass but not more than 70% by mass, and even more preferably 51 to 68% by mass.

[0020] When the content of eggshell powder (A) in the resin composition is 50% by mass or more, the resin becomes more brittle, making it more susceptible to molding defects and resin breakage during molding. After extensive research, the present inventors discovered that a resin composition that exhibits good moldability and suppresses resin breakage during molding can be obtained by combining eggshell powder (A) with a styrene-based thermoplastic elastomer (B) in the resin composition, setting the lower limit of the proportion of the styrene-based thermoplastic elastomer (B) to 25% by mass or more, and further controlling the MFR and tensile elongation at break within predetermined ranges. The resin composition according to the first embodiment more preferably contains only the styrene-based thermoplastic elastomer (B) as the thermoplastic resin. It is even more preferable that the styrene-based thermoplastic elastomer (B) contains a styrene-butadiene block copolymer, as described below. It has also been discovered that the above effects can be more easily achieved by combining two or more types of styrene-butadiene block copolymers.

[0021] In one embodiment, the content of the eggshell powder (A) is 5 to 300 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (B). From the viewpoint of obtaining a resin composition with a lower environmental impact, the content may be 100 to 300 parts by mass, 104 to 300 parts by mass, 106 to 300 parts by mass, 110 to 300 parts by mass, or 113 to 300 parts by mass relative to 100 parts by mass of the styrene-based thermoplastic elastomer (B).

[0022] In one embodiment, the average particle size of the eggshell powder (A) is preferably greater than 3 μm and less than 70 μm, more preferably 3.5 to 65 μm, and even more preferably 4 to 60 μm, from the viewpoint of easily adjusting the fluidity of the resin composition to a range suitable for extrusion sheet molding and enhancing the dispersibility of the eggshell powder (A) in the resin. In one embodiment, the average particle size of the eggshell powder (A) may be greater than 3 μm and less than 40 μm, 4 to 30 μm, 5 to 25 μm, or 10 to 20 μm. The average particle size of the eggshell powder (A) can be adjusted according to the "sieving method" and evaluated by measuring the laser diffraction and scattering state under wet conditions using water as a dispersion medium using a particle size distribution analyzer. In one embodiment, the resin composition may contain 50 to 75 mass% of eggshell powder (A) having an average particle size of 4 to 30 μm, based on the total mass of the resin composition.

[0023] In one embodiment, the density (g / cm ) of the eggshell powder (A) ３ ) is preferably 1.5 to 3.0 g / cm from the viewpoint of minimizing the content of eggshell membrane. ３ and more preferably 1.7 to 2.8 g / cm ３ and more preferably 2.0 to 2.7 g / cm ３ is.

[0024] Eggshell powder (A) can be prepared by a conventionally known production method. For example, eggshells may be pulverized by a known method and then classified to obtain eggshell powder (A) having a desired average particle size. Specifically, after removing the eggshell membrane from the eggshell, the eggshell is dried. The eggshell is then pulverized using a pulverizer or the like to obtain eggshell powder. The resulting mixture is then classified using a sieve with an appropriate mesh size to obtain eggshell powder.

[0025] Commercially available eggshell powder (A) can also be used, such as those manufactured by Green Techno 21 Co., Ltd. under the trade name "GT-31," those manufactured by Green Techno 21 Co., Ltd. under the trade name "GT-26," and those manufactured by Kewpie Egg Corporation under the trade name "Calhope (registered trademark)."

[0026] In one embodiment, the resin composition may contain an inorganic filler other than the eggshell powder (A) within a range that does not impair the effects of the present invention. Examples of inorganic fillers other than the eggshell powder (A) include inorganic fillers derived from minerals such as calcium carbonate, talc, and zeolite; inorganic fillers derived from biominerals such as pearls, shells, bones, and the exoskeletons of crustaceans; and inorganic fillers such as glass fibers and glass beads.

[0027] When eggshell powder (A) is used in combination with the aforementioned inorganic filler, it is preferable to adjust the total content of eggshell powder (A) and the inorganic filler to a range not exceeding 75% by mass relative to the total mass of the resin composition. From the viewpoint of more easily achieving the combined effect with the styrene-based thermoplastic elastomer (B) described below, the content of eggshell powder (A) in the inorganic filler is preferably 60% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 98% by mass or more, relative to the total amount of the inorganic filler. In one embodiment, the inorganic filler can be configured to consist solely of eggshell powder (A).

[0028] <Styrene-based thermoplastic elastomer (B)> The resin composition according to the first embodiment is characterized by containing predetermined amounts of eggshell powder (A) and styrene-based thermoplastic elastomer (B). The styrene-based thermoplastic elastomer (B) is a block copolymer of an aromatic vinyl compound and a conjugated diene, or a hydrogenated product thereof.

[0029] Examples of aromatic vinyl compounds include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, ethylstyrene, and p-t-butylstyrene. These aromatic vinyl compounds may be used alone or in combination of two or more. In one embodiment, the aromatic vinyl compound preferably contains styrene.

[0030] Examples of conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene, and it is preferable to include one or more selected from these. One type of conjugated diene may be used alone, or two or more types may be used in combination. In one embodiment, it is preferable that the conjugated diene includes 1,3-butadiene and / or isoprene.

[0031] Specific examples of the styrene-based thermoplastic elastomer (B) include block copolymers such as styrene-butadiene (SB), styrene-isoprene (SI), styrene-butadiene-butylene (SBB), styrene-butadiene-isoprene (SBI), styrene-butadiene-styrene (SBS), styrene-butadiene-butylene-styrene (SBBS), styrene-isoprene-styrene (SIS), and styrene-butadiene-isoprene-styrene (SBIS), as well as hydrogenated block copolymers thereof. These may be used alone or in combination of two or more. In one embodiment, the styrene-based thermoplastic elastomer (B) preferably contains a styrene-butadiene block copolymer and a partially or fully hydrogenated polymer thereof. In a preferred embodiment, the styrene-based thermoplastic elastomer (B) may contain only a styrene-butadiene block copolymer. In this disclosure, the term "styrene-butadiene block copolymer" may also include its hydrogenated product.

[0032] From the viewpoint of easily adjusting the MFR and tensile elongation at break of the resin composition within predetermined ranges, the proportion of the diene component in the styrene-based thermoplastic elastomer (B) is preferably 10 to 35% by mass, more preferably 15 to 35% by mass, even more preferably 20 to 35% by mass, and particularly preferably 20 to 30% by mass, relative to the total mass of the styrene-based thermoplastic elastomer (B). The content of the conjugated diene component may be a value calculated from the charged amount of the conjugated diene, or may be a value measured by potentiometric titration using iodine monochloride, potassium iodide, and sodium thiosulfate standard solutions.

[0033] The weight average molecular weight (Mw) of the styrene-based thermoplastic elastomer (B) is preferably 100,000 to 200,000, more preferably 110,000 to 180,000, and even more preferably 110,000 to 160,000. When the Mw of the styrene-based thermoplastic elastomer (B) is within the above range, its mixability with the eggshell powder (A) is likely to be improved. The Mw of the styrene-based thermoplastic elastomer is measured by GPC under the same conditions as those for the polystyrene resin described above.

[0034] From the viewpoint of easily adjusting the MFR of the resin composition within a predetermined range, the MFR (200°C, 5 kg load) of the styrene-based thermoplastic elastomer (B) is preferably 3.0 to 25 g / 10 min, more preferably 4.0 to 22 g / 10 min, and even more preferably 5.0 to 19 g / 10 min. In one embodiment, the MFR (200°C, 5 kg load) of the styrene-based thermoplastic elastomer (B) may be in the range of 8.0 to 16 g / 10 min. The MFR (200°C, 5 kg load) of the styrene-based thermoplastic elastomer (B) can be measured under the same conditions as those for the MFR (200°C, 5 kg load) of the resin composition described above.

[0035] The content of the styrene-based thermoplastic elastomer (B) in the resin composition is 25 to 95% by mass, preferably 30 to 95% by mass, more preferably 35 to 95% by mass, and even more preferably 40 to 95% by mass. In one embodiment, the content of the styrene-based thermoplastic elastomer (B) in the resin composition may be 25 to 50% by mass, 30 to 50% by mass, or 35 to 50% by mass, relative to the total mass of the resin composition. In another embodiment, the styrene-based thermoplastic elastomer (B) may be blended in such a range that the total amount of the eggshell powder (A) and the styrene-based thermoplastic elastomer (B) is 100% by mass.

[0036] In one embodiment, the styrene-based thermoplastic elastomer (B) preferably contains at least two types of styrene-butadiene block copolymers. "Containing at least two types of styrene-butadiene block copolymers" means containing two or more types of styrene-butadiene block copolymers that differ in at least one physical property among MFR (200°C, 5 kg load), tensile elongation at break, conjugated diene content, and Mw. The at least two types of styrene-butadiene block copolymers preferably include the following styrene-butadiene block copolymers (b1) and (b2).

[0037] (Styrene-Butadiene Block Copolymers (b1) and (b2)) The styrene-butadiene block copolymer (b1) (hereinafter sometimes referred to as "resin (b1)") preferably has an MFR (200°C, 5 kg load) of 3.0 to 10 g / 10 min and a tensile elongation at break measured in accordance with ASTM-D638 of 250 to 400%. The MFR (200°C, 5 kg load) of resin (b1) may be 3.0 to 9.0 g / 10 min, 4.0 to 8.0 g / 10 min, or 5.0 to 8.0 g / 10 min. The tensile elongation at break of resin (b1) may be 250 to 380%, 280 to 370%, or 300 to 370%. The Mw of the resin (b1) is preferably from 140,000 to 200,000, more preferably from 140,000 to 190,000, and even more preferably from 145,000 to 180,000.

[0038] The styrene-butadiene block copolymer (b2) (hereinafter sometimes referred to as "resin (b2)") preferably has an MFR (200°C, 5 kg load) of more than 10 g / 10 min and not more than 30 g / 10 min, and a tensile elongation at break measured in accordance with ASTM-D638 of 20% or more and less than 250%. The MFR (200°C, 5 kg load) of resin (b2) may be 12 to 28 g / 10 min, 12 to 25 g / 10 min, 15 to 24 g / 10 min, or 17 to 22 g / 10 min. The tensile elongation at break of resin (b1) may be 50% or more and less than 250%, 100 to 245%, 150 to 245%, or 180 to 245%. Furthermore, the Mw of the resin (b2) is preferably 110,000 or more and less than 140,000, more preferably 110,000 to 135,000, and even more preferably 115,000 to 130,000.

[0039] When a resin composition contains 50% by mass or more of eggshell powder (A), including the above-mentioned resin (b1) and resin (b2) as the styrene-based thermoplastic elastomer (B) makes it easier to obtain a resin composition that has good moldability and can suppress resin breakage during molding (particularly during extrusion molding). As mentioned above, as the content of eggshell powder (A) in a resin composition increases, the resin becomes more brittle, making it more likely to suffer from molding defects or resin breakage during molding. After extensive research, the present inventors have found that high fluidity and high tensile elongation at break can be achieved by combining at least two types of styrene-based thermoplastic elastomers, particularly by combining the above-mentioned resin (b1) and resin (b2). Such a resin composition has good moldability and is more likely to suppress resin breakage during molding.

[0040] When the resin composition contains resin (b1) and resin (b2), they are blended so that the total content of resin (b1) and resin (b2) is 25 to 95% by mass relative to the total mass of the resin composition. In one embodiment, the mass ratio of resin (b1) to resin (b2) in the resin composition (resin (b1):resin (b2)) is preferably 5:1 to 1:2, more preferably 4:1 to 1:1.5. In a preferred embodiment, they may be blended so that the mass ratio is resin (b1) > resin (b2). By blending resin (b1) > resin (b2), the MFR (200°C, 5 kg load) and tensile elongation at break tend to fall within the specified range, making it easier to obtain a resin composition with good moldability.

[0041] In one embodiment, the resin composition may contain only eggshell powder (A) and resin (b1) and resin (b2) as thermoplastic resins. In a more preferred embodiment, the content of eggshell powder (A) may be 50 to 70 mass%, the content of resin (b1) may be 20 to 40 mass%, and the content of resin (b2) may be 10 to 30 mass%, relative to the total mass of the resin composition (provided that the total of eggshell powder (A), resin (b1), and resin (b2) does not exceed 100 mass%).

[0042] In one embodiment, the coefficient (f) of the resin composition, expressed as MFR (200°C, 5 kg load) x tensile elongation at break (ASTM-D638), may be 65 to 1500, 80 to 1400, 100 to 1300, or 140 to 1200. A resin composition having a coefficient (f) within the above range has a good balance between MFR (200°C, 5 kg load) and tensile elongation at break, has better moldability, and is less likely to break during molding.

[0043] <Other Thermoplastic Resins> The resin composition according to the first embodiment may contain a thermoplastic resin other than the styrene-based thermoplastic elastomer (B) within a range that does not impair the effects of the present invention. Examples of other thermoplastic resins include polystyrene resins.

[0044] (Polystyrene Resin) The polystyrene resin refers to a polymer of an aromatic vinyl compound, a copolymer of an aromatic vinyl compound and a compound copolymerizable with the aromatic vinyl compound (excluding a block copolymer of an aromatic vinyl compound and a conjugated diene), or a polymer obtained by graft polymerization of these in the presence of a rubber polymer. Examples of the aromatic vinyl compound include the same compounds as those described above for the styrene-based thermoplastic elastomer (B), and styrene is preferred.

[0045] Examples of rubbery polymers include conjugated diene rubber, copolymers of conjugated dienes and aromatic vinyl compounds, and ethylene-propylene copolymer rubbers. More specifically, examples include polybutadiene, styrene-butadiene random copolymers, styrene-butadiene block copolymers, and partially or fully hydrogenated polymers thereof. The polystyrene resin does not include the styrene-based thermoplastic elastomer (B) described above. In one embodiment, the polystyrene resin may contain a polymer containing monomer units derived from the aromatic vinyl compound, monomer units derived from the unsaturated nitrile compounds, and the rubbery polymer described above. As such a polymer, a copolymer of acrylonitrile, styrene, and conjugated diene rubber is preferred, and an acrylonitrile-butadiene-styrene copolymer is more preferred.

[0046] The polystyrene resin may be general-purpose polystyrene (homopolystyrene, hereinafter also referred to as "GPPS") or high-impact polystyrene (hereinafter also referred to as "HIPS"). In one embodiment, the polystyrene resin preferably includes at least one resin selected from general-purpose polystyrene and high-impact polystyrene, and preferably includes HIPS.

[0047] In one embodiment, when the content of eggshell powder (A) in the resin composition is less than 50% by mass relative to the total mass of the resin composition, the resin composition may contain at least one polystyrene resin selected from GPPS and HIPS, and may also contain HIPS. On the other hand, when the content of eggshell powder (A) in the resin composition is 50% by mass or more, it is preferable that the resin composition does not contain these polystyrene resins, from the viewpoint of easily achieving a predetermined MFR and tensile elongation at break. When the resin composition contains a polystyrene resin, the content is preferably 40% by mass or less, more preferably 30% by mass or less, and particularly preferably 20% by mass or less, relative to the total mass of the resin composition. Furthermore, the content of polystyrene resin in the resin composition may be 10% by mass or less, or may be 5% by mass or less.

[0048] From the viewpoint of the MFR of the resin composition, the weight average molecular weight (Mw) of the polystyrene resin may be 10,000 to 500,000, or 100,000 to 400,000. The Mw of the polystyrene resin refers to a value calculated in terms of polystyrene by GPC (gel permeation chromatography).

[0049] The MFR (200°C, 5 kg load) of the polystyrene resin may be 1.0 to 10 g / 10 min, 1.3 to 6.0 g / 10 min, or 1.5 to 5.5 g / 10 min. The MFR (200°C, 5 kg load) of the polystyrene resin is a value measured in accordance with the standard JIS K 7210-2:2014 (ISO 1133-2:2011).

[0050] The resin composition according to the first embodiment may contain a thermoplastic resin other than the polystyrene resin and the styrene-based thermoplastic elastomer (B) described above.

[0051] <Other Components> In one embodiment, the resin composition may contain optional components such as ultraviolet absorbers, light stabilizers, antioxidants, lubricants, plasticizers, colorants, antistatic agents, flame retardants, and mineral oils, as well as reinforcing fibers such as glass fibers, carbon fibers, and aramid fibers, as long as the effects of the present invention are not impaired. Among these, it is preferable to contain the additive (C) described below. Furthermore, these other components may be used alone or in combination of two or more.

[0052] (Additive (C)) In one embodiment, the resin composition may contain additive (C) containing at least one compound selected from fatty acid amide (c1), fatty acid sodium salt (c2), and fatty acid ester (c3). In this case, it is preferable that the combined content of fatty acid amide (c1), fatty acid sodium salt (c2), and fatty acid ester (c3) exceeds 50% by mass relative to the total mass of additive (C), and that the combined content of additive (C) is 10 parts by mass or less relative to 100 parts by mass of eggshell powder (A) and styrene-based thermoplastic elastomer (B). By incorporating additive (C) in such an amount, it becomes easier to control the MFR (200°C, 5 kg load) and / or tensile elongation at break within a predetermined range. In particular, it is preferable to incorporate additive (C) when the content of eggshell powder (A) in the resin composition exceeds 50% by mass.

[0053] In one embodiment, the content of additive (C) may be 9 parts by mass or less, 8 parts by mass or less, or 7 parts by mass or less, relative to 100 parts by mass of the total of the eggshell powder (A) and the styrene-based thermoplastic elastomer (B). The lower limit of the content of additive (C) may be 0.5 parts by mass or more, or 1 part by mass or more, relative to 100 parts by mass of the total of the eggshell powder (A) and the styrene-based thermoplastic elastomer (B), from the viewpoint of MFR (200°C, 5 kg load) and / or tensile elongation at break. That is, the content of additive (C) may be 0.5 to 10 parts by mass, 0.5 to 9 parts by mass, 0.5 to 8 parts by mass, 1 to 8 parts by mass, or 1 to 6 parts by mass, relative to 100 parts by mass of the total of the eggshell powder (A) and the styrene-based thermoplastic elastomer (B).

[0054] (Fatty acid amide (c1)) The additive (C) may contain a fatty acid amide (c1) (hereinafter, also referred to as "compound (c1)"). The fatty acid amide (c1) has "R １ It is a compound having an amide group represented by the formula "-C(=O)-N-". The term "fatty acid amide" includes primary amides, secondary amides, tertiary amides, and those having two or more nitrogen atoms in one molecule. On the other hand, the fatty acid amide (c1) in this embodiment does not include polymers such as aliphatic polyamides typified by nylon-6.

[0055] The R １ is a hydrocarbon group which may have a substituent. The term "optionally having a substituent" means that one or more hydrogen atoms in the hydrocarbon group may be substituted with a substituent. １ is preferably an alkyl group having 2 or more carbon atoms, which may have a substituent, or an alkenyl group, which may have a substituent. The fatty acid amide (c1) is not particularly limited as long as it has the effect of the present invention. However, from the viewpoint of compatibility with the styrene-based thermoplastic elastomer (B), R １is preferably a higher fatty acid amide in which R is an alkyl group having 10 or more carbon atoms, which may have a substituent, or an alkenyl group, which may have a substituent. Specific examples include saturated fatty acid monoamides such as lauric acid amide, palmitic acid amide, stearic acid amide, and behenic acid amide; unsaturated fatty acid monoamides such as oleic acid amide and erucic acid amide; substituted amides such as N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, and N-stearyl erucic acid amide; methylene bisstearic acid amide, ethylene biscapric acid amide, ethylene biscapric acid amide, and ethylene biscapric acid amide. Examples of the compound (c1) include saturated fatty acid bisamides such as ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bisbehenic acid amide, hexamethylene bisstearic acid amide, and N,N'-distearyl adipamide; and unsaturated fatty acid bisamides such as ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, and N,N'-dioleyl adipamide. These may be used alone or in combination of two or more. Among these, from the viewpoint of easily suppressing breakage of the resin during molding, particularly extrusion molding, compound (c1) preferably contains a saturated fatty acid bisamide having 10 or more carbon atoms, and more preferably contains ethylene bisstearic acid amide.

[0056] (Fatty acid sodium salt (c2)) The additive (C) can contain a fatty acid sodium salt (c2). The fatty acid sodium salt (c2) (hereinafter sometimes referred to as "compound (c2)") is a compound represented by "R ２ -C(=O)-O-Na" and R ２ is R １ Examples of the fatty acid sodium salt (c2) include those shown in the above, and preferably an alkyl group having two or more carbon atoms, which may have a substituent, or an alkenyl group, which may have a substituent. There are no particular limitations on the fatty acid sodium salt (c2) as long as it has the effects of the present invention. In one embodiment, from the viewpoint of easily improving compatibility with the styrene-based thermoplastic elastomer (B) and easily obtaining a resin composition having excellent tensile elongation at break, R２ is preferably a sodium salt of a higher fatty acid in which is an alkyl group having 10 or more carbon atoms, which may have a substituent, or an alkenyl group, which may have a substituent. Specific examples include sodium salts of higher fatty acids having 10 to 20 carbon atoms, such as sodium laurate, sodium myristate, sodium palmitate, sodium oleate, and sodium stearate. These may be used alone or in combination of two or more. That is, the fatty acid sodium salt (c2) may be a mixture of the above-mentioned sodium salts of higher fatty acids having 10 to 20 carbon atoms.

[0057] (Fatty Acid Ester (c3)) The additive (C) can contain a fatty acid ester (c3). The fatty acid ester (c3) (hereinafter sometimes referred to as "compound (c3)") can have "R ３ It is an ester containing a fatty acid group represented by the formula -C(=O)O-. In one embodiment, the fatty acid ester (c3) is preferably a higher fatty acid ester obtained by reacting a higher fatty acid having 10 or more carbon atoms with a polyhydric alcohol. The higher fatty acid is preferably an alkyl or alkenyl group having 10 or more carbon atoms, which may have a substituent. In addition, examples of the polyhydric alcohol include dihydric to hexahydric polyhydric alcohols such as ethylene glycol, glycerin, 1,2,4-butanetriol, diglycerin, pentaerythritol, sorbitol, erythritol, and hexanetriol.

[0058] In a preferred embodiment, the higher fatty acid ester may include a glycerin fatty acid ester. Examples of the glycerin fatty acid ester include lauric acid monoglyceride, lauric acid diglyceride, lauric acid triglyceride, palmitic acid monoglyceride, palmitic acid diglyceride, palmitic acid triglyceride, stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, stearic acid tetraglyceride, hydroxystearic acid monoglyceride, hydroxystearic acid diglyceride, hydroxystearic acid triglyceride, and hydroxystearic acid tetraglyceride. These may be used alone or in combination. Among these, it is preferable to include hydroxystearic acid glyceride, from the viewpoint of more easily improving the compatibility between the eggshell powder (A) and the resin component and more easily obtaining a resin composition having excellent tensile elongation at break.

[0059] In one embodiment, the additive (C) preferably contains any one of compound (c1), compound (c2), or compound (c3). From the viewpoint of easily improving the tensile elongation at break, it is preferable to contain compound (c2). Furthermore, from the viewpoint of easily obtaining a resin composition with a higher MFR (200°C, 5 kg load), it is preferable to contain compound (c1).

[0060] In one embodiment, the total content of the compounds (c1) to (c3) in the additive (C) is more than 50% by mass, may be more than 50% by mass and not more than 100% by mass, may be 55 to 100% by mass, may be 60 to 100% by mass, or may be 65 to 100% by mass, based on the total mass of the additive (C).

[0061] [Method for producing resin composition] The resin composition according to the first embodiment can be produced by melt-kneading the eggshell powder (A), the styrene-based thermoplastic elastomer (B), and, if necessary, the other components described above (preferably the additive (C)), and / or other thermoplastic resins. Specifically, the components are fed into a twin-screw extruder, melt-kneaded at a temperature of 200 to 250°C, and then extruded into strands to prepare a pellet-shaped resin composition.

[0062] [Uses] The resin composition according to the first embodiment has good moldability and can suppress breakage of the resin during molding, particularly breakage of the resin during extrusion molding. Such a resin composition can be suitably used as a resin composition for molded products by extrusion molding (a resin composition for extrusion molding). Furthermore, as a molded product by extrusion molding, it is particularly suitable as a resin composition for sheet-shaped molded products. In one embodiment, the resin composition is preferably a resin composition for extrusion sheet molding. It should be noted that the use of the resin composition according to the first embodiment is not limited to extrusion molding or sheet-shaped molded products.

[0063] [Molded Article] The second embodiment of the present disclosure relates to a molded article containing the resin composition according to the first embodiment. The molded article according to the second embodiment has good moldability because it contains a resin composition containing a predetermined amount of eggshell powder (A) and a styrene-based thermoplastic elastomer (B) and having a predetermined MFR and tensile elongation at break. Furthermore, the resin is less likely to break during molding, particularly extrusion molding. Furthermore, the molded article according to the second embodiment contains a certain amount of eggshell powder (A) as an inorganic filler, which reduces the environmental impact. Such molded articles can be used in a variety of applications, such as home appliance parts, automotive interior materials, building materials, food containers, toys, and packaging materials.

[0064] In one embodiment, the molded article may be in the form of a sheet. A preferred method for producing a sheet-shaped molded article is an extrusion sheet molding method in which a resin composition is extruded using an extruder equipped with a T-die. When producing a sheet-shaped molded article by the extrusion sheet molding method, a step of winding up the sheet-shaped molded article extruded from the molding machine using a winder is generally included. If a highly brittle resin composition is used, the resin is likely to break when extruded from the molding machine. In addition, the sheet may be damaged by being pulled when wound up by the winder. The resin composition according to the first embodiment can prevent breakage or damage to the resin when producing a sheet-shaped molded article.

[0065] The sheet-shaped molded product may be further molded by vacuum pressure forming, pressure forming, or the like. If a highly brittle resin composition is used, the sheet may be damaged by the external force applied during vacuum pressure forming or pressure forming. The resin composition according to the first embodiment can prevent damage to the sheet-shaped molded product during vacuum pressure forming or pressure forming. The resin composition according to a preferred embodiment can produce a vacuum pressure forming product or pressure forming product with a uniform film thickness.

[0066] [Laminate Sheet] A third embodiment of the present disclosure relates to a laminate sheet. The laminate sheet according to the third embodiment has at least a layer (X) containing a polystyrene resin and a layer (Y) containing the resin composition according to the first embodiment. FIG. 1 shows an example of the laminate sheet according to the third embodiment. The laminate sheet 10 has a configuration in which a layer (Y) containing the resin composition according to the first embodiment (hereinafter referred to as "layer (Y)") is laminated on a layer (X) containing a polystyrene resin (hereinafter referred to as "layer (X)"). Since such a laminate sheet 10 has layer (Y), it is an environmentally friendly laminate sheet. Furthermore, the laminate sheet 10 has excellent moldability even when further molded by vacuum pressure molding, pressure molding, or the like.

[0067] <Layer (X) Containing Polystyrene Resin> Examples of the polystyrene resin contained in layer (X) include the same polystyrene resins as those exemplified in the resin composition according to the first embodiment. In one embodiment, the polystyrene resin preferably contains at least one resin selected from GPPS and HIPS. When the resin composition contains a polystyrene resin, the polystyrene resin contained in layer (X) may be the same type of polystyrene resin as the polystyrene resin contained in layer (Y), or may be a different type of polystyrene (e.g., a different type of monomer).

[0068] In one embodiment, the ratio (X:Y) of the total thickness of layer (X) to the total thickness of layer (Y) is preferably 10 to 30:70 to 90. In one embodiment, the total thickness of layer (X) is preferably 30% or less, more preferably 25% or less, of the total thickness of the laminate sheet. In one embodiment, the total thickness of layer (X) can be, for example, more than 0 mm and 0.36 mm or less, or more than 0 mm and 0.3 mm or less. In the present disclosure, the thickness of a layer is a value measured using a constant pressure thickness gauge in accordance with JIS K6783.

[0069] <Layer (Y) Comprising Resin Composition> The layer (Y) comprises eggshell powder (A) and a styrene-based thermoplastic elastomer (B). The descriptions regarding the eggshell powder (A), the styrene-based thermoplastic elastomer (B), and the resin composition in the resin composition according to the first embodiment also apply here.

[0070] The content of eggshell powder (A) is 3.5 to 67.5% by mass, preferably 5 to 50% by mass, and more preferably 5 to 45% by mass, relative to the total mass of the laminate sheet. By adjusting the content of eggshell powder (A) to 3.5 to 67.5% by mass relative to the total mass of the laminate sheet, a laminate sheet with a low environmental impact is likely to be obtained. Furthermore, because the laminate sheet contains the resin composition according to the first embodiment, even if the proportion of eggshell powder (A) in the laminate sheet is increased, good moldability is likely to be achieved, and the resin is less likely to break during molding. The content of eggshell powder (A) in the laminate sheet can be determined by quantifying the proportion of eggshell powder contained in the ash after burning the laminate sheet using TG-DTA.

[0071] The MFR (200°C, 5 kg load) of layer (Y) is preferably 0.5 to 15 g / 10 min, and the tensile elongation at break measured according to ASTM-D638 is preferably 20 to 230%. Because layer (Y) contains the first resin composition (preferably, contains only the resin composition according to the first embodiment), it has a predetermined MFR and tensile elongation at break. Therefore, it has good moldability when made into a laminate sheet. Furthermore, it is possible to suppress resin breakage during molding. Furthermore, because it contains eggshell powder (A), it is possible to make a laminate sheet with a low environmental impact. The MFR (200°C, 5 kg load) and tensile elongation at break can be measured using the same method as for the resin composition described above.

[0072] In one embodiment, the laminate sheet may have a structure having at least three layers. In this case, it is preferable that the layer (X) has a first layer (x-1) (hereinafter referred to as "first layer (x-1)") containing a polystyrene resin and a second layer (x-2) (hereinafter referred to as "second layer (x-2)") containing a polystyrene resin, and the layer (Y) is located between the first layer (x-1) and the second layer (x-2).

[0073] FIG. 2 shows an example of a laminate sheet according to the third embodiment having a structure with at least three layers. The laminate sheet 20 in FIG. 2 has a structure in which a second layer (x-2), a layer (Y), and a first layer (x-1) are laminated in this order. In the laminate sheet 20, the layer (Y) is laminated directly on the second layer (x-2), and the first layer (x-1) is laminated directly on the layer (Y). In the laminate sheet 20 shown in FIG. 2, the first layer (x-1) constitutes one outermost surface of the laminate sheet 20, and the second layer (x-2) constitutes the other outermost surface of the laminate sheet 20. Thus, the laminate sheet according to the third embodiment may have a structure in which two or more layers containing polystyrene resin constitute both surfaces of the laminate sheet. In this case, by arranging the layer (Y) between the first layer (x-1) and the second layer (x-2), a laminate sheet that combines environmental load reduction effects and moldability is likely to be obtained.

[0074] When the laminate sheet has a three-layer structure, the polystyrene resins contained in the first layer (x-1) and the second layer (x-2) may be the same type of polystyrene resin, or different types of polystyrene (e.g., different types of monomers). In one embodiment, the polystyrene resins contained in the first layer (x-1) and the second layer (x-2) are preferably the same type (having the same monomer composition).

[0075] In one embodiment, the thickness ratio (x-1:Y:x-2) of the first layer (x-1), the layer (Y), and the second layer (x-2) is preferably 5 to 15:70 to 90:5 to 15, and more preferably 8 to 13:74 to 84:8 to 13, with the sum of the thickness ratios being 100. The thicknesses of the first layer (x-1) and the second layer (x-2) may be 0.01 to 0.18 mm and 0.016 to 0.156 mm, respectively.

[0076] The layer (X) may contain, as necessary, other additives such as ultraviolet absorbers, light stabilizers, antioxidants, lubricants, plasticizers, colorants, antistatic agents, flame retardants, and mineral oils, as well as reinforcing fibers such as glass fibers, carbon fibers, and aramid fibers, within the range that does not impair the effects of the present invention. These may be used alone or in combination of two or more.

[0077] From the viewpoint of further reducing the environmental load, the thickness of the layer (Y) is preferably 70% or more, more preferably 75% or more, of the total thickness of the laminate sheet. The thickness of the layer (Y) can be, for example, 0.14 to 1.2 mm, or 0.15 to 1.2 mm.

[0078] In one embodiment, the total thickness of the laminate sheet is preferably 0.2 to 1.2 mm, and more preferably 0.3 to 1.0 mm, from the viewpoint of easily suppressing breakage of the resin during molding.

[0079] <Layer structure of laminate sheet> The laminate sheet according to the third embodiment has one or more layers (X) and one or more layers (Y). The laminate sheet is composed of a total of two or more layers, and may be composed of three or more layers, four or more layers, or five or more layers.

[0080] In another embodiment, the laminated sheet may have a structure in which layers (X) and layers (Y) are alternately laminated.

[0081] The laminate sheet may have layers other than the layer (X) and the layer (Y). Examples of such layers include a gas barrier layer containing an ethylene-vinyl alcohol copolymer (EVOH) or the like, and an adhesive layer containing an adhesive or the like. Even when the laminate sheet has such layers, from the viewpoint of further reducing the environmental load and providing a laminate sheet with superior strength, the content of eggshell powder (A) is preferably 3.5 to 67.5% by mass, more preferably 5 to 50% by mass, and even more preferably 5 to 45% by mass, relative to the total mass of the laminate sheet.

[0082] The method for producing the laminate sheet is not limited as long as it does not impair the effects of the present invention. For example, the laminate sheet can be produced by co-extrusion molding the layer (X), the layer (Y), and other layers that are optionally provided, all of which are integrated together. A preferred co-extrusion molding method is a common multilayer co-extrusion method such as a feedblock method or a multi-manifold method, in which all layers of the laminate sheet are integrated, extruded into a single sheet from the lip of the discharge outlet, solidified through a cooling roll, and wound up by a winder. The laminate sheet according to this embodiment can be prevented from being damaged when wound up by a winder. A T-die (also called a T-die) is preferably used as the die. When producing a laminate sheet by a multilayer co-extrusion method, it is preferable to match the fluidity of the resin compositions that make up each layer.

[0083] The laminate sheet has good formability, and the resin is less likely to break during extrusion molding. Therefore, the laminate sheet can be suitably used for vacuum pressure forming or pressure forming. The laminate sheet can be suitably used for applications such as food containers and packaging materials. Of course, the applications of the laminate sheet according to the third embodiment are not limited to these applications.

[0084] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure is described below. [1] A resin composition comprising eggshell powder (A) and a styrene-based thermoplastic elastomer (B), wherein the content of the eggshell powder (A) is 5 to 75 mass% and the content of the styrene-based thermoplastic elastomer (B) is 25 to 95 mass% relative to the total mass of the resin composition, the resin composition has a melt flow rate of 0.5 to 15 g / 10 min at 200°C under a 5 kg load, and a tensile elongation at break measured in accordance with ASTM-D638 of 20 to 230%. [2] The resin composition according to [1], wherein the average particle size of the eggshell powder (A) is greater than 3 μm and less than or equal to 70 μm. [3] The resin composition according to [1] or [2], wherein the styrene-based thermoplastic elastomer (B) comprises a styrene-butadiene block copolymer. [4] The resin composition according to any one of [1] to [3], wherein the styrene-based thermoplastic elastomer (B) contains at least two types of styrene-butadiene block copolymers. [5] The resin composition according to any one of [1] to [4], which is for extrusion molding. [6] A molded product comprising the resin composition according to any one of [1] to [5]. [7] A laminate sheet having at least a layer (X) containing a polystyrene resin and a layer (Y) containing the resin composition according to any one of [1] to [6]. [8] The laminate sheet according to [7], wherein the content of the eggshell powder (A) is 3.5 to 67.5 mass% relative to the total mass of the laminate sheet. [9] The laminate sheet according to [7] or [8], wherein the total thickness of the laminate sheet is 0.2 to 1.2 mm.

[10] The laminate sheet according to any one of [7] to [9], wherein the layer (X) containing a polystyrene resin has a first layer (x-1) containing a polystyrene resin and a second layer (x-2) containing a polystyrene resin, and the layer (Y) containing a resin composition is located between the first layer (x-1) containing a polystyrene resin and the second layer (x-2) containing a polystyrene resin.

[11] The laminate sheet according to

[10] , wherein the first layer (x-1) containing a polystyrene resin constitutes one outermost surface of the laminate sheet, and the second layer (x-2) containing a polystyrene resin constitutes the other outermost surface of the laminate sheet.

[12] The laminate sheet according to

[10] or

[11] , wherein the thickness ratio (x-1:Y:x-2) of the first layer (x-1) containing the polystyrene resin, the layer (Y) containing the resin composition, and the second layer (x-2) containing the polystyrene resin is 5 to 15:70 to 90:5 to 15 (with the proviso that the total of the thickness ratios is 100).

[13] The resin composition according to any one of [1] to [5], wherein the content of the eggshell powder (A) with respect to the total mass of the resin composition is more than 50 mass% and not more than 75 mass%.

[14] The resin composition according to any one of [1] to [5] and

[13] , wherein the styrene-based thermoplastic elastomer (B) comprises a styrene-butadiene block copolymer (b1) and a styrene-butadiene block copolymer (b2), wherein the styrene-butadiene block copolymer (b1) has an MFR (200°C, 5 kg load) of 3.0 to 10 g / 10 min and a tensile break elongation measured in accordance with ASTM-D638 of 250 to 400%, and the styrene-butadiene block copolymer (b2) has an MFR (200°C, 5 kg load) of more than 10 g / 10 min and not more than 30 g / 10 min and a tensile break elongation measured in accordance with ASTM-D638 of 20% or more and less than 250%.

[15] The resin composition according to

[14] , wherein the mass ratio ((b1):(b2)) of the styrene-butadiene block copolymer (b1) to the styrene-butadiene block copolymer (b2) in the resin composition is 5: 1 to 1: 2.

[16] The resin composition according to any one of [1] to [5] or any one of

[13] to

[15] , further comprising an additive (C) containing at least one compound selected from the group consisting of fatty acid amides (c1), fatty acid sodium salts (c2), and fatty acid esters (c3).

[0085] The present invention will be explained in more detail below by showing examples, but the interpretation of the present invention is not limited to these examples.

[0086] [Eggshell powder (A)] Green Techno 21 Co., Ltd., product name "GT-31" (average particle size: 15 μm, density: 2.6 g / cm ３ ).

[0087] [Styrene-based thermoplastic elastomer (B)] The following resins were prepared as the styrene-based thermoplastic elastomer (B): Resin (b1): Styrene-butadiene block copolymer (MFR (200°C, 5 kg load): 5.9 g / 10 min, tensile elongation at break (ASTM-D638): 332%, conjugated diene content: 28.7%, Mw: 148,000). Resin (b2): Styrene-butadiene block copolymer (MFR (200°C, 5 kg load): 21.6 g / 10 min, tensile elongation at break (ASTM-D638): 239%, conjugated diene content: 23.0%, Mw: 119,000).

[0088] [Other thermoplastic resins] Polystyrene resin: HIPS (MFR (200°C, 5 kg load): 2.7 g / 10 min, tensile elongation at break (ASTM-D638): 50%, rubber component content (conjugated diene content): 7%).

[0089] [Other Components] Compound (c1): Ethylene bisstearamide (Kao Corporation, product name "Kaowax EB-FF") Compound (c2): Miyoshi Oil & Fats Co., Ltd., product name "Tankal MH" (a mixture of sodium fatty acids with a mass ratio of lauric acid:myristic acid:palmitic acid:stearic acid:oleic acid=3:2:40:15:30).

[0090] The conjugated diene content and Mw of each component were measured under the following conditions: MFR and tensile elongation at break were measured by the methods described below.

[0091] <Conjugated Diene Amount> The conjugated diene amounts of resin (b1), resin (b2) and polystyrene resin were measured by potentiometric titration using iodine monochloride, potassium iodide and sodium thiosulfate standard solutions.

[0092] <Mw> Measured by GPC under the following conditions: (GPC measurement conditions) Apparatus: Shodex Co., Ltd., product name "Shodex SYSTEM-21" Column: PLgel MIXED-B Measurement temperature: 40°C Solvent: tetrahydrofuran Flow rate: 1.0 mL / min Detection method: RI Sample concentration: 0.2 mass% Injection volume: 100 μL Calibration curve: standard polystyrene (Polymer Laboratories)

[0093] Example 1: 39 parts by mass of resin (b1) and 10 parts by mass of resin (b2) were blended as the styrene-based thermoplastic elastomer (B). 51 parts by mass of eggshell powder (A) was then blended, and the resulting mixture was melt-kneaded at 200°C and 350 rpm using a twin-screw extruder (manufactured by Toshiba Machine Co., Ltd., product name "TEM35-B") and extruded into a strand shape at a throughput of 20 kg / h to obtain a pellet-shaped resin composition. The MFR (200°C, 5 kg load), tensile elongation at break, and tensile modulus of elasticity of the resulting resin composition were measured under the following conditions. The coefficient (f) (MFR (200°C, 5 kg load) × tensile elongation at break) was calculated from the MFR (200°C, 5 kg load) and tensile elongation at break. Furthermore, the moldability of the resulting resin composition and its effect of suppressing resin breakage during molding were evaluated under the following conditions. The results are shown in Table 1.

[0094] <Melt flow rate (MFR)> The MFR of the resin composition pellets obtained in the examples and comparative examples was measured at 200°C under a load of 5 kg in accordance with JIS K 7210-2:2014 (ISO 1133-2:2011). The results are shown in Table 1.

[0095] <Tensile elongation at break and tensile modulus> Measurements were made in accordance with ASTM-D638 using an autograph (manufactured by Shimadzu Corporation, product name "AGS-X"). Specifically, a plate-shaped sample with a thickness of 0.40 mm was prepared under the following conditions, and then cut out in the shape of a No. 1 dumbbell to prepare a measurement sample. Thereafter, the tensile elongation at break and tensile modulus of the sample were measured at a measurement temperature of 23°C and a humidity of 50%, at a pulling rate of 5 mm / min. The arithmetic mean value was calculated from the measurement results of 10 measurement samples. Equipment used: heat press (manufactured by Tester Sangyo Co., Ltd., SA-303) Temperature: 200°C

[0096] <Moldability Evaluation> A sample having an MFR (200°C, 5 kg load) of 0.5 to 15 g / 10 min and a tensile elongation at break of 20 to 230% was rated as "pass." A sample having an MFR (200°C, 5 kg load) and / or tensile elongation at break outside the above range was rated as "fail."

[0097] <Resin Breakage Suppression> If the MFR and tensile break elongation are equal to or greater than a predetermined value, it becomes easier to suppress breakage of the resin due to brittleness during molding (particularly during extrusion molding). On the other hand, if the MFR and / or tensile break elongation are too high, drawdown may occur during extrusion molding, causing the resin to break. Therefore, the resin breakage suppression during molding was evaluated based on the coefficient (f) in accordance with the following evaluation criteria (note that the following evaluation criteria are evaluation indicators for the resin compositions of the present examples and comparative examples). (Evaluation Criteria) Good: The coefficient (f) was 150 to 1,000. Fair: The coefficient (f) was 65 or more but less than 150, or more than 1,000 and 1,500 or less. Poor: The coefficient (f) was less than 65 or more than 1,500.

[0098] [Examples 2 to 11 and Comparative Examples 1 to 7] Pellet-shaped resin compositions were obtained in the same manner as in Example 1, except that the formulations of the resin compositions were as shown in Table 1. The MFR, tensile elongation at break, and tensile modulus of elasticity of the obtained resin compositions were evaluated in the same manner as in Example 1. Furthermore, moldability and inhibition of resin breakage were evaluated in the same manner as in Example 1. The results are shown in Tables 1 and 2.

[0099]

[0100]

[0101] As shown in Table 1, the resin compositions of Examples 1 to 11 had MFR (200°C, 5 kg load) and tensile elongation at break within the specified range. Such resin compositions have good moldability. Furthermore, since the coefficient (f) was also within the specified range, resin breakage during molding, particularly extrusion molding, can be suppressed. Furthermore, the resin compositions of Examples 1 to 11 had good MFR and tensile elongation at break, while also possessing a tensile modulus sufficient for molded products. Therefore, even when molded into sheet-like products, the molded products can be prevented from breaking. On the other hand, the resin compositions of Comparative Examples 2 to 7 exhibited good MFR (200°C, 5 kg load) values ​​but poor tensile elongation at break values. Such resin compositions cannot achieve good moldability. Furthermore, since the coefficient (f) value was low, it is thought that resin breakage occurs during molding, particularly extrusion molding. Note that the resin composition of Comparative Example 1 had poor fluidity, making it impossible to measure MFR (200°C, 5 kg load). From the above results, it was confirmed that the resin composition according to the first embodiment has good moldability and can suppress breakage of the resin during molding. Such a resin composition is suitable as a raw material for molded products, particularly sheet-shaped molded products. In addition, such a resin composition can be suitably used as a raw material resin for laminate sheets.

[0102] 10, 20 Laminate sheet X Layer containing polystyrene resin x-1 First layer containing polystyrene resin x-2 Second layer containing polystyrene resin Y Layer containing the resin composition according to the first embodiment

Claims

1. A resin composition comprising eggshell powder (A) and a styrene-based thermoplastic elastomer (B), wherein the content of the eggshell powder (A) is 5 to 75 mass% and the content of the styrene-based thermoplastic elastomer (B) is 25 to 95 mass% relative to the total mass of the resin composition, wherein the melt flow rate of the resin composition at 200°C under a 5 kg load is 0.5 to 15 g / 10 min, and wherein the tensile elongation at break measured in accordance with ASTM-D638 is 20 to 230%.

2. The resin composition according to claim 1, wherein the eggshell powder (A) has an average particle size of more than 3 μm and not more than 70 μm.

3. The resin composition according to claim 1 or 2, wherein the styrene-based thermoplastic elastomer (B) comprises a styrene-butadiene block copolymer.

4. The resin composition according to claim 1 or 2, wherein the styrene-based thermoplastic elastomer (B) comprises at least two types of styrene-butadiene block copolymers.

5. The resin composition according to claim 1 or 2, which is for extrusion molding.

6. A molded article comprising the resin composition according to claim 1 or 2.

7. A laminated sheet having at least a layer (X) containing a polystyrene resin and a layer (Y) containing the resin composition according to claim 1 or 2.

8. The laminate sheet according to claim 7, wherein the content of the eggshell powder (A) is 3.5 to 67.5 mass% relative to the total mass of the laminate sheet.

9. The laminate sheet according to claim 7, wherein the total thickness of the laminate sheet is 0.2 to 1.2 mm.

10. The laminate sheet according to claim 7, wherein the layer (X) containing a polystyrene resin has a first layer (x-1) containing a polystyrene resin and a second layer (x-2) containing a polystyrene resin, and the layer (Y) containing a resin composition is located between the first layer (x-1) containing a polystyrene resin and the second layer (x-2) containing a polystyrene resin.

11. The laminate sheet according to claim 10, wherein the first layer (x-1) containing polystyrene resin constitutes one outermost surface of the laminate sheet, and the second layer (x-2) containing polystyrene resin constitutes the other outermost surface of the laminate sheet.

12. The laminate sheet according to claim 10, wherein the thickness ratio (x-1:Y:x-2) of the first layer (x-1) containing a polystyrene resin, the layer (Y) containing a resin composition, and the second layer (x-2) containing a polystyrene resin is 5-15:70-90:5-15 (with the sum of the thickness ratios being 100).

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