Styrene-based resin compositions, sheets, and injection blow molded articles

Abstract

To provide a styrenic resin composition that has reduced environmental load and has high elasticity and mechanical strength.SOLUTION: A styrenic resin composition contains 82.5-99.9 mass% of a rubber-modified styrenic resin (A), which contains a polymer matrix phase containing a styrenic resin and a rubber-like polymer dispersed in the polymer matrix phase, and 0.1-15 mass% of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more.SELECTED DRAWING: None

Description

[Technical Field] 【0001】 The present invention relates to a styrene-based resin composition and a sheet and injection-blown molded article made from the styrene-based resin composition. [Background technology] 【0002】 Styrene resins are used in a wide range of applications due to their excellent moldability, dimensional stability, and transparency. Furthermore, with the growing interest in biomass materials from the perspective of realizing a low-carbon and circular economy, composite materials combining styrene resins with naturally derived biomass materials are being investigated. For example, Patent Document 1 discloses a styrene-based resin composition containing rubber-modified polystyrene, polylactic acid, and a thermoplastic elastomer containing styrene monomer units. Patent Document 2 also discloses a method for producing a heat-resistant foamed resin sheet by adding epoxidized soybean oil and / or linseed oil and a higher fatty acid metal salt to a resin composition mainly composed of a styrene-methacrylic acid copolymer. [Prior art documents] [Patent Documents] 【0003】 [Patent Document 1] Japanese Patent Publication No. 2016-199654 [Patent Document 2] Japanese Patent Publication No. 2005-239914 [Overview of the Initiative] [Problems that the invention aims to solve] 【0004】 The technology described in Patent Document 1 above investigates polymer alloys of styrene resin and polylactic acid, which has a relatively high melting point, toughness, and transparency among plant-derived biodegradable polymers. However, the compatibility of polylactic acid with styrene resin is very low, and it has poor fluidity, making it difficult to design products that satisfy the mechanical properties such as impact resistance or elasticity required in the market. 【0005】 Furthermore, the technology described in Patent Document 2 above investigates a crosslinked styrene-(meth)acrylic acid copolymer resin obtained by reacting epoxidized soybean oil as a component having a crosslinked structure with a styrene-(meth)acrylic acid copolymer. The method of producing closed-cell styrene-based resin foam by introducing a crosslinking agent to control the fluidity or viscoelasticity of the molten state is a common foam formation method. However, compatibility varies greatly depending on the type of styrene-based resin and the type of crosslinking agent used, making it difficult to produce molded articles that possess both elasticity and mechanical strength. In addition, in systems where (meth)acrylic polymer resin and modified vegetable oils such as epoxidized soybean oil coexist, the modified group reacts with (meth)acrylic acid to gel, making it difficult to control the crosslinking density and reducing moldability. Furthermore, there is a concern that gelation may impair the appearance of the molded product. The technologies described in Patent Documents 1 and 2 above both involve composite materials of styrene resin and biomass material. However, due to the low compatibility of the chemical structures of the two materials, composite materials obtained by simply melt-mixing styrene resin and biomass material, or by simply reacting styrene resin and biomass material, have difficulty meeting the required mechanical strength requirements. Therefore, the object of the present invention is to provide a styrene-based resin composition that reduces environmental impact and has excellent mechanical strength, as well as a sheet and an injection blow molded article made from the styrene-based resin composition. [Means for solving the problem] 【0006】 In view of the above problems, the inventors conducted diligent research and repeated experiments, and as a result found that the above problems can be solved by using a styrene resin composition obtained by mixing a rubber-modified styrene resin (A) and a biomass plasticizer (B) having a high boiling point and a biomass carbon ratio (pMC%) of 10% or more in a specific ratio, thus completing the present invention. In particular, when the compatibility between the biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more and the polymer matrix phase of the rubber-modified styrene resin (A) is low, the biomass plasticizer (B) is difficult to disperse (for example, the two separate), which tends to lead to a decrease in mechanical strength. Therefore, regarding the compatibility between the biomass plasticizer (B) and the polymer matrix phase of the rubber-modified styrene resin (A), a solubility test was conducted using the following turbidity evaluation experiment. The results showed that when the SP value difference between the biomass plasticizer (B) and the polymer matrix phase of the rubber-modified styrene resin (A) is within a specific range, the biomass plasticizer (B) dissolves uniformly in the rubber-modified styrene resin (A), resulting in excellent mechanical strength. 【0007】 [Turbidity evaluation experiment] To 100 parts by mass of polystyrene resin (manufactured by PS Japan Co., Ltd., trademark name "685", corresponding to styrene-based resin (a)) or acrylonitrile styrene resin (manufactured by Asahi Kasei Corporation, trademark name "Stylac® 789", corresponding to styrene-based resin (a)), 5 parts by mass or 10 parts by mass of each plasticizer shown in Table 1 or Table 2 below were added and kneaded in a twin-screw extruder. The twin-screw extruder used was a Japan Steel Works Ltd. twin-screw extruder "TEM-26SS" (screw diameter 26 mm). Melt extrusion was performed under conditions of a melting temperature of 220°C and an extrusion speed of 10 kg / hr. After the extruded strands were cooled and solidified in a cooling tank, they were cut to obtain pellet-shaped resin compositions. Subsequently, the total light transmittance of the 2mm thick plate was measured in accordance with JIS K7361-1, and evaluated as transparent ("○") if the total light transmittance was 85% or higher, semi-transparent ("△") if it was between 65% and less than 85%, and opaque ("×") if it was less than 65% (as shown in Tables 1 and 2 below). The measurement of the total light transmittance of the 2mm thick plate was carried out as follows. Measurement of total light transmittance (I) Conditions for preparing test specimens A styrene-based resin composition obtained under the following conditions was injection-molded using a mold for flat plate molded products to produce a 2 mm thick flat plate, and then a sheet was produced. Molding machine: EC60N manufactured by Toshiba Machine Co., Ltd. Cylinder temperature: 220℃ Injection pressure: 45 MPa, Injection time: 10 seconds Cooling time: 15 seconds, Mold temperature: 45℃ (II) Measurement conditions for total light transmittance The total light transmittance (%) was measured using the sheet specimen prepared as described above, in accordance with JIS K7361-1. Table 1 below shows the turbidity evaluation results when each plasticizer is added to the polystyrene resin described above. On the other hand, Table 2 below shows the turbidity evaluation results when each plasticizer is added to the acrylonitrile styrene resin described above. [Table 1] [Table 2] From the experimental results in Tables 1 and 2 above, it was confirmed that when the difference in SP values ​​exceeds 2.5, the effect of the amount of plasticizer added decreases, and the plasticizer becomes cloudy in styrene-based resins such as polystyrene resin and acrylonitrile styrene resin. Therefore, it is considered that insolubility in styrene-based resins requires a difference in SP value of 2.5 or more with the styrene-based resin. On the other hand, from the experimental results in Tables 1 and 2 above, it was confirmed that when the difference between the SP value of styrene-based resins such as polystyrene resin and acrylonitrile styrene resin and the SP value of the added plasticizer is less than approximately 1, the effect of the amount of plasticizer added decreases, and the plasticizer dissolves relatively stably in the styrene-based resin. Based on the above, in this specification, plasticizers with an SP value difference of 2.5 or more from styrene-based resins caused turbidity regardless of the amount of plasticizer added. Therefore, plasticizers with an SP value difference of 2.5 or more are considered completely insoluble in styrene-based resins. On the other hand, in systems using plasticizers with an SP value difference of 1.3 or more and less than 2.5 compared to styrene-based resins, the system was not transparent, suggesting that some insoluble material was present in the resin. Therefore, in this specification, plasticizers with an SP value difference of 1.3 or more and less than 2.5 compared to styrene-based resins are considered to be partially insoluble in styrene-based resins. 【0008】 In other words, the present invention is as follows. [1] The present invention relates to a styrene resin composition comprising 82.5 to 99.9% by mass of a rubber-modified styrene resin (A) containing a polymer matrix phase containing a styrene resin (a) and a rubbery polymer dispersed in the polymer matrix phase, and 0.1 to 15% by mass of a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more. [2] In the present invention, it is preferable that the styrene resin composition contains 90 to 99.9% by mass of a rubber-modified styrene resin (A) containing a polymer matrix phase containing a styrene resin (a) and a rubbery polymer dispersed in the polymer matrix phase, and 0.1 to 10% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more. [3] In the present invention, the absolute value of the difference between the SP value of the styrene resin (a) and the SP value of the biomass plasticizer (B) is 2.5 (cal / cm³). 3 ) 1 / 2 It is preferable that it be less than [a certain value]. [4] In the present invention, the SP value of the biomass plasticizer (B) is 7.4 to 10.5 (cal / cm³). 3 ) 1 / 2 It is preferable that this be the case. [5] In the present invention, the biomass plasticizer (B) is preferably a natural vegetable oil, a modified vegetable oil, or a mixture of a modified vegetable oil and mineral oil. [6] In the present invention, the biomass plasticizer (B) is preferably a modified vegetable oil modified by epoxy groups, amino groups, or ester bonds. [7] In the present invention, it is preferable that the modification rate of the modified vegetable oil per gram of the modified vegetable oil is 1 mol% to 50 mmol%. [8] In the present invention, it is preferable that the styrene resin composition contains 2% by mass or less of a hydroxyl group-containing compound. [9] In the present invention, it is preferable that the sheet is made of the styrene resin composition described in [1] to [8] above.

[10] In the present invention, it is preferable that the injection blow molded article is made of the styrene resin composition described in [1] to [8] above. [Effects of the Invention] 【0009】 According to the present invention, it is possible to provide a styrene-based resin composition that is excellent in reducing environmental impact and mechanical strength, and has an excellent appearance when molded, or a sheet and injection blow molded article made from the styrene-based resin composition. [Modes for carrying out the invention] 【0010】 The embodiments of the present invention (hereinafter referred to as "these embodiments") will be described in detail below, but the present invention is not limited to the following description and can be implemented in various ways within the scope of its gist. 【0011】 [Styrene resin composition] The styrene resin composition of this embodiment contains 82.5 to 99.9% by mass, preferably 90 to 99.9% by mass, of a rubber-modified styrene resin (A) containing a polymer matrix phase containing a styrene resin (a) and a rubbery polymer dispersed in the polymer matrix phase, and 0.1 to 15% by mass, preferably 0.1 to 10% by mass, of a biomass plasticizer (B) having a biomass carbon ratio (pMC ratio) of 10% or more. In other words, the styrene-based resin composition of this embodiment contains 82.5 to 99.9% by mass of rubber-modified styrene-based resin (A), preferably 90 to 99.9% by mass, and 0.1 to 15% by mass of biomass plasticizer (B), preferably 0.1 to 10% by mass, based on the total styrene-based resin composition (100% by mass), wherein the rubber-modified styrene-based resin (A) contains a polymer matrix phase containing styrene-based resin (a) and a rubbery polymer. This makes it possible to provide a styrene-based resin composition with reduced environmental impact and excellent elongation and strength. 【0012】 <Rubber-modified styrene resin (A) (hereinafter also referred to as component (A))> The styrene-based resin composition in this embodiment contains a rubber-modified styrene-based resin (A). In this embodiment, the content of the rubber-modified styrene-based resin (A) is 82.5 to 99.9% by mass of the total styrene-based resin composition (100% by mass), preferably 82.5 to 99.88% by mass, more preferably 83 to 99% by mass, even more preferably 84 to 98% by mass, even more preferably 85 to 97% by mass, even more preferably 86 to 97% by mass, and even more preferably 88 to 97% by mass. By setting the content to 82.5% by mass or more, impact resistance is improved. On the other hand, by setting the content to 99.9% by mass or less, rigidity and other properties can be improved. In another embodiment, the content of the rubber-modified styrene resin (A) is 90.0 to 99.9% by mass, preferably 91.0 to 98.3% by mass, and more preferably 92.0 to 97.3% by mass, based on the total styrene resin composition (100% by mass). By setting the content to 90.0% by mass or more, impact resistance is further improved. On the other hand, by setting the content to 99.9% by mass or less, rigidity and other properties can be improved. 【0013】 In this embodiment, the rubber-modified styrene resin (A) is a styrene resin (a) as a polymer matrix phase in which rubbery polymer particles (hereinafter referred to as rubbery polymer particles) are dispersed, and can be produced by polymerizing a styrene monomer in the presence of the rubbery polymer. 【0014】 -Polymer Matrix Phase- The polymer matrix phase of the rubber-modified styrene resin (A) in this embodiment is preferably composed of a styrene resin (a) containing styrene monomer units (for example, polystyrene or a copolymer (b) of styrene monomer units and repeating units copolymerizable with said styrene monomer units). The monomer units constituting the styrene resin (a) in this embodiment are preferably styrene monomer units and / or vinyl monomer units (i) copolymerizable with said styrene monomers. Therefore, the styrene resin (a) is preferably one or more selected from the group consisting of polystyrene and styrene copolymer resin (b). As described later, the styrene copolymer resin (b) is, for example, a styrene-(meth)acrylic acid ester copolymer. Furthermore, "composed of" means that 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more of the total amount of the polymer matrix phase is occupied by styrene-based resin (a). 【0015】 In this embodiment, the weight-average molecular weight (Mw) of the styrene-based resin (a) constituting the polymer matrix phase is preferably 100,000 to 300,000, more preferably 110,000 to 270,000, and even more preferably 120,000 to 250,000. When the weight-average molecular weight (Mw) is 100,000 to 300,000, a resin with a better balance of mechanical strength and fluidity is obtained, and the inclusion of gel material is also reduced. The weight-average molecular weight (Mw) is a value obtained using gel permeation chromatography on a standard polyethylene basis. 【0016】 In this embodiment, it is preferable that the styrene resin (a) or the styrene resin composition of this embodiment does not substantially contain vinyl cyanide monomers such as acronitrile monomer units or methacrylonitrile monomer units. Specifically, it is preferable that vinyl cyanide monomers are contained in 10% by mass or less, more preferably 5% by mass or less, and even more preferably 2% by mass or less, relative to the total amount of styrene resin (a) or polymer matrix phase. 【0017】 The content of styrene resin (a) in this embodiment is preferably 65 to 99.88% by mass, more preferably 70 to 99% by mass, 72 to 98% by mass, even more preferably 74 to 97% by mass, and even more preferably 75 to 95% by mass, based on the total mass (100% by mass) of the styrene resin composition. In this embodiment, the content of styrene monomer units among the monomer units constituting the styrene resin (a) is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, even more preferably 70 to 100% by mass, even more preferably 80 to 100% by mass, and even more preferably 90 to 100% by mass, relative to the total amount of styrene resin (a). The content of styrene monomer units and vinyl monomer units (i) copolymerizable with styrene monomers other than said styrene monomer units in the styrene resin (a) is determined by proton nuclear magnetic resonance ( 1 It can be determined from the integral ratio of the spectrum measured with a 1H-NMR detector. In this embodiment, the styrene monomers constituting the polymer matrix phase of the rubber-modified styrene resin (A) include, in addition to styrene, α-methylstyrene, α-methylp-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and styrene derivatives such as t-butylstyrene or bromostyrene and indene. Styrene is particularly preferred. One or more of these styrene monomers can be used. 【0018】 In this embodiment, the vinyl monomer (i) is preferably one or more selected from the group consisting of unsaturated carboxylic acid monomers and unsaturated carboxylic acid ester monomer units, and is not particularly limited, but examples include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. These monomers can be used individually or in combination of two or more. The term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid. 【0019】 The rubbery polymer contained in the rubber-modified styrene resin (A) of this embodiment is preferably in particulate form. For example, it may contain a styrene resin (a) containing styrene monomer units obtained from the above-mentioned styrene monomer on the inside (for example, polystyrene or a copolymer of styrene monomer units and repeating units copolymerizable with said styrene monomer units (b)), and / or a polymer (a) composed of styrene monomer units (for example, polystyrene or a copolymer of styrene monomer units and repeating units copolymerizable with said styrene monomer units (b)) may be grafted onto the outside. The polymer (a) composed of styrene monomer units, as used herein, is a styrene-based resin (a) or a component of a styrene-based resin (a), and may be a homopolymer or copolymer. The copolymer (b) of styrene monomer units and repeating units copolymerizable with said styrene monomer units is a component of the styrene-based copolymer resin (b) or styrene-based copolymer resin (b) described later, and refers to, for example, a styrene-(meth)acrylic acid copolymer. 【0020】 --polystyrene-- In this embodiment, polystyrene is a homopolymer obtained by polymerizing styrene monomers, and commonly available ones can be appropriately selected and used. Examples of styrene monomers constituting polystyrene are the same as those described above, and include styrene, α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene or bromostyrene and styrene derivatives such as indene. Styrene is particularly preferred from an industrial standpoint. One or more of these styrene monomers can be used. Polystyrene may further contain monomer units other than the styrene monomer units described above, as long as it does not impair the effects of the present invention, but it typically consists of styrene monomer units. 【0021】 --Styrene copolymer resin (b)-- In this embodiment, the styrene copolymer resin (b) is preferably a resin containing styrene monomer units and vinyl monomer units (i), more preferably a resin containing styrene monomer units and one or more monomer units selected from the group consisting of unsaturated carboxylic acid monomers and unsaturated carboxylic acid ester monomer units, and even more preferably a resin containing styrene monomer units and unsaturated carboxylic acid ester monomer units. In the present invention, the styrene copolymer resin (b) preferably contains 51 to 98% by mass of styrene monomer units, more preferably 54 to 96% by mass, more preferably 57 to 93% by mass, and even more preferably 60 to 90% by mass, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is taken as 100% by mass. By setting the content to 51% by mass or more, the refractive index of the polymer matrix phase can be improved. On the other hand, by setting the content to 98% by mass or less, it becomes difficult to have a desired amount of unsaturated carboxylic acid ester monomer units present. In another embodiment, the styrene copolymer resin (b) in the present invention preferably has a styrene monomer unit content of 69 to 98% by mass, more preferably 74 to 96% by mass, and even more preferably 77 to 92% by mass, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is taken as 100% by mass. By setting the content to 69% by mass or more, the refractive index of the styrene resin (a) can be improved. On the other hand, by setting the content to 98% by mass or less, it becomes difficult to have a desired amount of unsaturated carboxylic acid ester monomer units present. Furthermore, in the styrene copolymer resin (b) of the present invention, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is taken as 100% by mass, the content of unsaturated carboxylic acid ester monomer units is preferably in the range of 2 to 49% by mass, more preferably 4 to 46% by mass, more preferably 7 to 43% by mass, and even more preferably 10 to 40% by mass. In another embodiment, the styrene copolymer resin (b) in the present invention preferably has a content of 2 to 31% by mass of unsaturated carboxylic acid ester monomer units, more preferably 4 to 26% by mass, and even more preferably 8 to 23% by mass, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is taken as 100% by mass. In this embodiment, the content of styrene monomer units (e.g., styrene monomer units) and unsaturated carboxylic acid ester monomer units (e.g., methyl methacrylate monomer units) in the styrene copolymer resin (b) is determined by proton nuclear magnetic resonance ( 1 It can be determined from the integral ratio of the spectrum measured with a 1H-NMR detector. 【0022】 Specific examples of the styrene monomer constituting the styrene copolymer resin (b) of this embodiment are the same as those described above, so they are omitted. The unsaturated carboxylic acid ester monomer constituting the styrene copolymer resin (b) of this embodiment is not particularly limited, but examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and cyclohexyl (meth)acrylate. As the (meth)acrylate ester monomer, methyl (meth)acrylate is preferred because it has little effect on the reduction of heat resistance. These unsaturated carboxylic acid ester monomers can be used individually or in combination of two or more. 【0023】 In this embodiment, the styrene-based copolymer resin (b) is preferably a styrene-(meth)acrylate methyl copolymer, a styrene-(meth)acrylate ethyl copolymer, a styrene-(meth)acrylate propane copolymer, or a styrene-(meth)acrylate butyl copolymer, or a styrene-(meth)acrylate methyl-meth)acrylate butyl copolymer. 【0024】 In this embodiment, the weight-average molecular weight (Mw) of the styrene copolymer resin (b) is preferably 100,000 to 400,000, more preferably 120,000 to 390,000, and even more preferably 140,000 to 380,000. When the weight-average molecular weight (Mw) is 100,000 to 400,000, a resin with a better balance of mechanical strength and fluidity is obtained, and the inclusion of gel material is also reduced. The weight-average molecular weight (Mw) is a value obtained using gel permeation chromatography on a standard polyethylene basis. 【0025】 In this embodiment, the rubber-modified styrene resin (A) may be used by mixing one or more types of the rubber-modified styrene resin (A), or a mixture of one or more types of rubber-modified styrene resin (A) and one or more types of styrene copolymer resin (b) may be used. In this case, the mixing ratio of the rubber-modified styrene resin (A) and the styrene copolymer resin (b) can be appropriately changed depending on the intended use. For example, in a system where the polymer matrix phase of the rubber-modified styrene resin (A) is less than that of the styrene copolymer resin (b), it is preferable to contain 0.1 to 30% by mass of the styrene copolymer resin (b) relative to the total amount (100% by mass) of the styrene resin (a) in the polymer matrix phase. On the other hand, in a system where the polymer matrix phase of the rubber-modified styrene resin (A) is more than that of the styrene copolymer resin (b), it is preferable to contain 70 to 99.9% by mass of the styrene copolymer resin (b) relative to the total amount (100% by mass) of the styrene resin (a). 【0026】 -Rubber-like polymer- In the styrene-based resin composition of this embodiment, rubbery polymer particles, i.e., rubbery polymer particles, may be included in the styrene-based resin composition as part of the rubber-modified styrene-based resin (A). The rubber-like polymer particles contained in the rubber-modified styrene resin (A) of this embodiment may, for example, contain a styrene resin on the inside, and / or have a styrene resin (a) grafted onto the outside. Furthermore, the rubber-like polymer particles of this embodiment include not only a core-shell structure composed of a styrene resin (a) as a core and a rubber-like polymer as a shell enclosing the core, but also a salami structure composed of multiple styrene resin (a) as cores and a rubber-like polymer as a shell enclosing the multiple styrene resin (a) as cores. 【0027】 As the material for the rubbery polymer or rubbery polymer particles, for example, polybutadiene, polystyrene-encapsulated polybutadiene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc., can be used, but polybutadiene or styrene-butadiene copolymer is preferred. For polybutadiene, both high-cis polybutadiene with a high cis content and low-cis polybutadiene with a low cis content can be used. Furthermore, both random and block structures can be used for the styrene-butadiene copolymer. One or more of these rubbery polymers can be used. Also, saturated rubber obtained by hydrogenating butadiene-based rubber can be used. Examples of such rubber-modified styrene resins (A) include HIPS (high-impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), and AES resin (acrylonitrile-ethylene propylene rubber-styrene copolymer). 【0028】 In this embodiment, when the rubber-modified styrene resin (A) is a HIPS resin, among these rubbery polymers, high-cis polybutadiene composed of 90 mol% or more cis-1,4 bonds is particularly preferred. In the high-cis polybutadiene, it is preferable that the vinyl-1,2 bonds are composed of 6 mol% or less, and particularly preferable that they be composed of 3 mol% or less. Furthermore, the content of isomers having cis 1,4, trans 1,4, or vinyl 1,2 structures as constituent units of the high-cis polybutadiene can be calculated by measuring with an infrared spectrophotometer and processing the data using the Morello method. Furthermore, the high-cis polybutadiene can be easily obtained by polymerizing 1,3-butadiene using a known production method, for example, a catalyst containing an organoaluminum compound and a cobalt or nickel compound. 【0029】 In one embodiment of this product, the content of the rubbery polymer in the rubber-modified styrene resin (A) is preferably 1.0 to 15% by mass, more preferably 1.2 to 12% by mass, even more preferably 1.5 to 10% by mass, even more preferably 2 to 10% by mass, and even more preferably 3 to 8% by mass, based on 100% by mass of the rubber-modified styrene resin (A). If the content of the rubbery polymer is less than 1.0% by mass, there is a risk that the impact resistance of the entire styrene resin composition will decrease. Also, if the content of the rubbery polymer exceeds 15% by mass, there is a risk that the fluidity of the entire styrene resin composition will decrease. In particular, if the content of the rubbery polymer is less than 2% by mass, there is a risk that the impact resistance of the entire styrene resin composition will decrease. Also, if the content of the rubbery polymer exceeds 10% by mass, there is a risk that the light transmittance will decrease. In this disclosure, the content of the rubbery polymer contained in the rubber-modified styrene resin (A) refers to the content of the rubbery polymer itself (for example, a conjugated diene polymer such as polybutadiene), and does not include the styrene resin (a) encapsulated within the rubbery polymer particles. Furthermore, the content of the rubbery polymer is a value calculated using the method described in the Examples section. 【0030】 In this embodiment, the content of rubbery polymer particles contained in the rubber-modified styrene resin (A) (including the content of the rubbery polymer itself (e.g., a conjugated diene polymer such as polybutadiene) and the content of the styrene resin (a) encapsulated within the rubbery polymer particles) is preferably 3 to 36% by mass, more preferably 4 to 30% by mass, even more preferably 6 to 20% by mass, and even more preferably 8 to 18% by mass, based on the total styrene resin composition (100% by mass). When considering injection blow molding, the content of rubbery polymer particles (including the content of the rubbery polymer itself (e.g., a conjugated diene polymer such as polybutadiene) and the content of the styrene-based resin (a) encapsulated within the rubbery polymer particles) relative to the entire styrene-based resin composition (100% by mass) is preferably 10 to 30% by mass, more preferably 11 to 28% by mass, even more preferably 12 to 27% by mass, even more preferably 12 to 26% by mass, and even more preferably 13 to 25% by mass. In this embodiment, the content of the rubbery polymer contained in the rubber-modified styrene resin (A) (this refers to the content of the rubbery polymer itself (for example, a conjugated diene polymer such as polybutadiene), and does not include the styrene resin (a) encapsulated within the rubbery polymer particles) is preferably 1.0 to 15% by mass, more preferably 1.2 to 12% by mass, even more preferably 1.5 to 10% by mass, even more preferably 2 to 10% by mass, and even more preferably 3 to 8% by mass, based on 100% by mass of the rubber-modified styrene resin (A). If the content of the rubbery polymer is less than 1.0% by mass, there is a risk that the impact resistance of the entire styrene resin composition will decrease. Furthermore, if the content of the rubbery polymer exceeds 15% by mass, there is a risk that the fluidity of the entire styrene resin composition will decrease. Furthermore, if the content of the rubbery polymer exceeds 10% by mass, there is a risk that the light transmittance will decrease. In this disclosure, the content of the rubbery polymer contained in the rubber-modified styrene resin (A) is a value calculated using the method described in the Examples section. In this disclosure, the content of rubbery polymer particles in the rubber-modified styrene resin (A) is a value calculated using the method described in the Examples section. 【0031】 In this embodiment, the rubbery polymer contained in the rubber-modified styrene resin (A) is preferably rubbery polymer particles, i.e., rubbery polymer particles. In this embodiment, the average particle size of the rubbery polymer particles contained in the rubber-modified styrene resin (A) is preferably 0.3 to 7.0 μm, more preferably 0.4 to 5.0 μm, even more preferably 0.5 to 3.5 μm, and from the viewpoint of light transmittance or impact resistance, preferably 0.8 to 3.5 μm, and even more preferably 0.8 to 3.0 μm. When considering the balance between mouth impact strength and buckling strength, in this embodiment, the lower limit of the average particle size of the rubbery polymer particles contained in the rubber-modified styrene resin (A) is preferably 0.9 μm, more preferably 1.0 μm, more preferably 1.1 μm, more preferably 1.2 μm, more preferably 1.3 μm, more preferably 1.4 μm, and even more preferably 1.5 μm. Furthermore, the upper limit of the average particle size of the rubbery polymer particles is preferably 7.0 μm, more preferably 6.5 μm, more preferably 6.0 μm, more preferably 5.5 μm, more preferably 5.0 μm, and even more preferably 4.5 μm. Furthermore, the preferred range for the average particle diameter may be a range obtained by arbitrarily combining the upper limit and lower limit of the average particle diameter. In this disclosure, the average particle size of the rubbery polymer contained in the rubber-modified styrene resin (A) can be measured by the following method. Using a COULTER MULTISIZER III (product name) manufactured by Beckman Coulter, Inc., equipped with a 30 μm diameter aperture tube, 0.05 g of rubber-modified styrene resin (A) pellets were placed in approximately 5 ml of dimethylformamide and left for about 2 to 5 minutes. Next, the dissolved dimethylformamide was measured as an appropriate particle concentration, and the median diameter based on volume was taken as the average particle diameter. Furthermore, the above method for measuring the average particle diameter of the rubbery polymer can be applied to the method for measuring the average particle diameter of the rubbery polymer contained in the entire styrene resin composition. 【0032】 In this embodiment, the reduced viscosity of the rubber-modified styrene resin (A) (which is an indicator of the molecular weight of the rubber-modified styrene resin (A)) is preferably in the range of 0.5 to 0.85 dL / g, and more preferably in the range of 0.55 to 0.80 dL / g. If it is less than 0.50 dL / g, there is a risk of reduced impact strength, and if it exceeds 0.85 dL / g, there is a risk of reduced moldability due to reduced fluidity. In this disclosure, the reduced viscosity of the rubber-modified styrene resin (A) is the value measured in a toluene solution at 30°C and a concentration of 0.5 g / dL. In this embodiment, among the rubbery polymers, polybutadiene and styrene-butadiene rubber are particularly preferred, with polybutadiene being the most preferred. 【0033】 -Method for manufacturing rubber-modified styrene resin (A)- In this embodiment, the method for producing the rubber-modified styrene resin (A) is not particularly limited, but it can be produced by bulk polymerization (or solution polymerization) in which a styrene monomer, optionally added vinyl monomer (i), and optionally added solvent are polymerized in the presence of a rubbery polymer, or by bulk-suspension polymerization that transitions to suspension polymerization during the reaction, or by emulsion graft polymerization in which a styrene monomer and optionally added vinyl monomer (i) are polymerized in the presence of a rubbery polymer latex. In bulk polymerization, it can be produced by continuously supplying a mixed solution containing the rubbery polymer, styrene monomer, optionally added vinyl monomer (i), and optionally an organic solvent, organic peroxide, and / or chain transfer agent to a polymerization apparatus configured by connecting a fully mixed reactor or a tank reactor and a plurality of tank reactors in series. 【0034】 In this embodiment, there are no particular limitations on the polymerization method of the styrene resin (a), which is the polymer matrix phase of the rubber-modified styrene resin (A). For example, a bulk polymerization method or a solution polymerization method can be suitably employed as a radical polymerization method. The polymerization method mainly comprises a polymerization step of polymerizing the polymerization raw materials (monomer components) and a defoliation step of removing volatile components such as unreacted monomers and polymerization solvents from the polymerization product. 【0035】 The styrene-based resin (a) that can be used in this embodiment may be any polymer having styrene monomer units, or it may be a copolymer (b) having styrene monomer units and monomer units other than said styrene monomer units. In other words, the styrene-based resin (a) may be a styrene copolymer resin (b) obtained by polymerizing a styrene monomer with one or more monomers selected from other vinyl monomers and rubbery polymers copolymerizable with said styrene monomer. The styrene-based resin (a) in the present invention is not particularly limited, but examples include polystyrene, a styrene copolymer resin (b) having styrene monomer units, or mixtures thereof. 【0036】 -Method for producing styrene copolymer resin (b)- In this embodiment, there are no particular restrictions on the polymerization method of the styrene copolymer resin (b), but for example, a bulk polymerization method or a solution polymerization method can be suitably employed as a radical polymerization method. The polymerization method mainly comprises a polymerization step of polymerizing the polymerization raw materials (monomer components) and a defoliation step of removing volatile components such as unreacted monomers and polymerization solvents from the polymerization product. The following describes an example of a polymerization method for the styrene copolymer resin (b) that can be used in this embodiment. When polymerizing the polymerization raw materials to obtain the styrene copolymer resin (b), the polymerization raw material composition typically contains a polymerization initiator and a chain transfer agent. Examples of polymerization initiators used in the polymerization of styrene copolymer resin (b) include organic peroxides, such as peroxyketals like 2,2-bis(t-butylperoxy)butane, 1,1-bis(t-butylperoxy)cyclohexane (perhexa-C), and n-butyl-4,4-bis(t-butylperoxy)valerate; dialkyl peroxides like di-t-butylperoxide (perbutyl-D), t-butylcumylperoxide, and dicumylperoxide; diacyl peroxides like acetylperoxide and isobutyrylperoxide; peroxydicarbonates like diisopropylperoxydicarbonate; peroxyesters like t-butylperoxyacetate; ketone peroxides like acetylacetone peroxide; and hydroperoxides like t-butylhydroperoxide. Of these, 1,1-bis(t-butylperoxy)cyclohexane is preferred from the viewpoint of decomposition rate and polymerization rate. It is preferable to add 0.005 to 0.08% by mass relative to the total amount of monomers. Examples of chain transfer agents used in the polymerization of styrene copolymer resin (b) include mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, and n-octyl mercaptan, α-methylstyrene linear dimer, 1-phenyl-2-fluorene, dibentene, chloroform, terpenes, halogen compounds, and turpentines such as terepinolene. There are no particular restrictions on the amount of this chain transfer agent used, but it is generally preferable to add about 0.005 to 0.3% by weight relative to the monomer. The polymerization initiator and chain transfer agent described above can be used not only in the production of styrene copolymer resin (b) but also in the production of rubber-modified styrene resin (A). 【0037】 As a polymerization method for the styrene copolymer resin (b), solution polymerization using a polymerization solvent can be employed as needed. Examples of polymerization solvents that can be used include aromatic hydrocarbons, such as ethylbenzene and dialkyl ketones, such as methyl ethyl ketone, which may be used individually or in combination of two or more. Other polymerization solvents, such as aliphatic hydrocarbons, can be further mixed with aromatic hydrocarbons as long as they do not reduce the solubility of the polymerization product. It is preferable that these polymerization solvents are used in an amount not exceeding 25 parts by mass per 100 parts by mass of total monomers. If the amount of polymerization solvent exceeds 25 parts by mass per 100 parts by mass of total monomers, the polymerization rate tends to decrease significantly, and the mechanical strength of the resulting resin tends to decrease significantly. Adding 5 to 20 parts by mass per 100 parts by mass of total monomers before polymerization is preferable in terms of quality uniformity and polymerization temperature control. 【0038】 In this embodiment, there are no particular restrictions on the apparatus used in the polymerization step to obtain the styrene copolymer resin (b), and it can be appropriately selected according to general polymerization methods for styrene resins. For example, when bulk polymerization is employed, a polymerization apparatus consisting of one or more fully mixed reactors can be used. There are also no particular restrictions on the devolatilization step. For example, when bulk polymerization is employed, polymerization is carried out until the unreacted monomer is preferably 50% by mass or less, more preferably 40% by mass or less, and then devolatilization is performed by a known method to remove volatile components such as the unreacted monomer. More specifically, conventional devolatilization apparatus such as a flash drum, twin-screw devolatilizer, thin-film evaporator, or extruder can be used, but a devolatilization apparatus with a small retention area is preferred. The temperature of the devolatilization treatment is usually around 190 to 280°C, more preferably 190 to 260°C. The pressure of the devolatilization treatment is usually around 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, and more preferably 0.13 to 2.0 kPa. Preferred defloration methods include removing volatile components by reducing the pressure under heating, and removing them by passing them through an extruder or the like designed for the purpose of removing volatile components. 【0039】 In the present invention, the MFR (at 200°C, 5kg) of the styrene-based resin (a) is preferably 1.0 or more and 10.0 or less. More preferably 1.5 or more and 8.0 or less, and even more preferably 2.0 or more and 7.0 or less. The styrene resin (a) used in this embodiment may be one type or a blend of two or more types. In the case of a blend, the refractive index or MFR is the value of the blend. The MFR used herein is the value measured in accordance with ISO 1133. 【0040】 <Biomass plasticizer (B) (hereinafter also referred to as component (B))> The styrene-based resin composition in this embodiment contains a biomass plasticizer (B). The biomass plasticizer (B) has a biomass carbon ratio (pMC%) of 10% or more. If the biomass carbon ratio (pMC%) is within the above range, the amount of fossil fuels used can be reduced, thus providing a styrene-based resin composition that can reduce the environmental burden. In this embodiment, the lower limit of the biomass carbon ratio (pMC%) is preferably 10% or more, more preferably 25% or more, even more preferably 50% or more, and even more preferably 75% or more. 【0041】 In this embodiment, the content of biomass plasticizer (B) is 0.1 to 15% by mass relative to the total amount (100% by mass) of the styrene-based resin composition. The lower limit of the biomass plasticizer (B) content is preferably 0.1% by mass or more, more preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass or more. The upper limit of the biomass plasticizer (B) content is preferably 15% by mass or less, preferably 14% by mass or less, preferably 13% by mass or less, more preferably 12% by mass or less, preferably 11% by mass or less, more preferably 10% by mass or less, even more preferably 9% by mass or less, 8% by mass or less, even more preferably 7% by mass or less, and particularly preferably 6% by mass or less. In another form, the preferred lower limits for the content of biomass plasticizer (B) are 0.3% by mass or more, 0.7% by mass or more, 0.9% by mass or more, 1.1% by mass or more, 1.2% by mass or more, 1.3% by mass or more, 1.4% by mass or more, 1.5% by mass or more, 1.7% by mass or more, 1.9% by mass or more, 2.3% by mass or more, 2.4% by mass or more, 2.5% by mass or more, 2.7% by mass or more, 2.9% by mass or more, 3.3% by mass or more, 3.4% by mass or more, and 3.5% by mass or more. If the biomass plasticizer (B) content is too high, volatile components increase, leading to increased mold fouling. Furthermore, if the biomass plasticizer (B) content exceeds 15%, bleed-out tends to occur. On the other hand, if the biomass plasticizer (B) content is too low (less than 0.1% by mass), fluidity decreases, leading to an increase in molding temperature, resulting in longer cooling times and reduced productivity. It is preferable that the biomass plasticizer (B) is uniformly dispersed in the styrene-based resin composition. More specifically, it is preferable that it is not an external lubricant (e.g., a lubricant insoluble in the polymer molten material) that forms a single layer of biomass plasticizer (B) on the surface of the styrene-based resin composition. Methods for uniformly dispersing the biomass plasticizer (B) in the styrene-based resin composition include, for example, kneading the rubber-modified styrene-based resin (A) and the biomass plasticizer (B) in an extruder, or including the biomass plasticizer (B) in the polymerization raw material composition when polymerizing the polymerization raw materials. 【0042】 The biomass carbon ratio (pMC%) in this specification indicates the carbon concentration (mass ratio) of biomass-derived components. More specifically, it is the value of the 14 C content obtained by the radiocarbon 14 measurement method in accordance with ASTM-D6866. This radiocarbon 14 measurement method does not contain 14 C in fossil fuels, and since biomass (or biological) - derived carbon absorbs 14 C in the atmosphere during the growth period, it is a method of estimating the biomass carbon ratio (pMC%) from the 14 C ratio in the carbon contained in biomass materials (or organisms). Therefore, by measuring the proportion of 14 C contained in all carbon atoms in the plasticizer of this embodiment, the proportion of biomass - derived carbon can be calculated. In the present invention, the biomass carbon ratio (pMC%) is calculated by the following formula (1) using the method described in the Examples section below. Formula (1): Biomass carbon ratio (pMC%) = ( 14 C plasticizer / 12 C plasticizer) / ( 14 C standard substance / 12 C standard substance) × 100 Also, the standard substance used is oxalic acid (SRM4990), and ([[]] 14 C plasticizer / 12 C plasticizer) / ( 14 C standard substance / 12 C standard substance) was calculated by the AMS method. 【0043】 The weight-average molecular weight (Mw) of the biomass plasticizer in this embodiment is preferably 200 to 7500, more preferably 300 to 5000, and even more preferably 400 to 3000. When the weight-average molecular weight (Mw) of the biomass plasticizer is 200 to 7500, a styrene-based resin composition with a superior balance of mechanical strength and fluidity is obtained, and the inclusion of gel material is also reduced. The weight-average molecular weight (Mw) is a value obtained on a standard polystyrene basis using gel permeation chromatography, as described in the Examples section below. 【0044】 In this embodiment, the biomass plasticizer (B) refers to a plasticizer that uses biomass material as part or all of its raw materials, and has a biomass carbon ratio (pMC%) of 10% or more. The biomass plasticizer (B) in this embodiment is a plasticizer that uses plant-derived biomass material as at least part of its raw materials and has a biomass carbon ratio (pMC%) of 10% or more, and is preferably a vegetable oil, a mixture of vegetable oil and mineral oil, or a polyester-based plasticizer, and more preferably a natural vegetable oil, modified vegetable oil, a mixture of natural vegetable oil and mineral oil, a mixture of modified vegetable oil and mineral oil, a mixture of natural vegetable oil, modified vegetable oil and mineral oil, or a polyester-based plasticizer. In this embodiment, the preferred biomass plasticizer (B) is preferably a natural vegetable oil, a modified vegetable oil, or a mixture of vegetable oil and mineral oil. In this specification, "vegetable oil" refers to a general term for oils and fats derived from plants, and includes natural vegetable oils and modified vegetable oils. 【0045】 In this embodiment, the biomass plasticizer (B) may be a modified vegetable oil. A modified vegetable oil is a compound made from vegetable oil, and more specifically, a compound in which a part of a plant-derived hydrocarbon oil has been modified with a functional group, and it is preferable that the vegetable oil has been modified with epoxy groups, amino groups, or ester bonds. The vegetable oil includes triesters of glycerin and fatty acids, fatty acid monoesters obtained by adding a monoalcohol to a vegetable oil and performing a transesterification reaction, fatty acid monoesters obtained by esterifying a fatty acid with a monoalcohol, and ethers derived from fatty acids. In this embodiment, it is preferable that the modifying groups (epoxy groups, amino groups, or ester-bonded functional groups) of the modified vegetable oil do not substantially polymerize with other components (including styrene resin (a)) or with other modified vegetable oils in the styrene resin composition. Furthermore, in this embodiment, it is preferable that the modification rate of the modified vegetable oil per gram of the modified vegetable oil is 1 mmol% to 50 mmol%. The modification rate of the above-mentioned modified vegetable oil is as described in the examples below. 1 It is calculated using the 1H-NMR measurement method. 【0046】 Specific examples of the above natural plant oils include, for example, cottonseed oil, tung oil, shea oil, alfalfa oil, poppy oil, pumpkin oil, winter pumpkin oil, mixed grain oil, barley oil, quinoa oil, rye oil, kukui oil, passionflower oil, shea butter, aloe vera oil, sweet pea oil, peach kernel oil, soybean oil, cashew oil, peanut oil, avocado oil, baobab oil, borage oil, broccoli oil, calendula oil, camellia oil, canola oil, carrot oil, safflower oil, and more. Examples include hemp oil, rapeseed oil, cottonseed oil, coconut oil, pumpkin seed oil, wheat germ oil, jojoba oil, lily oil, macadamia oil, corn oil, meadowfoam oil, monoi oil, hazelnut oil, apricot kernel oil, walnut oil, olive oil, evening primrose oil, palm oil, blackcurrant seed oil, kiwi seed oil, grapeseed oil, pistachio oil, musk rose oil, sesame oil, soybean oil, sunflower oil, castor oil, watermelon oil, or mixtures of these oils. In this embodiment, modified vegetable oils include oils obtained by hydrogenating the above-executed natural vegetable oils (e.g., hydrogenated castor oil); oils obtained by epoxidizing the above-executed natural vegetable oils (e.g., modified epoxidized oil); and oils obtained by aminating the above-executed natural vegetable oils (e.g., modified aminated oil). The modified epoxidized oils include oils in which epoxy functional groups have been ring-opened, such as hydroxylated soybean oil, and oils that have been directly hydroxylated beforehand, as well as cashew oil-based polyols. 【0047】 Specific examples of the biomass plasticizer (B) in this embodiment include, for example, palm oil, epoxidized soybean oil, epoxidized linseed oil, hydrogenated castor oil, polyoxyethylene-converted castor oil, polyoxyethylene-converted hydrogenated castor oil, oleic acid ester, or lauric acid ester. Examples include "Polysizer W-1810-BIO" and "Eposizer" from DIC Corporation; "Newsizer 510R" and "Newsizer 512" from NOF Corporation; "Pionin D Series" from Takemoto Oil Co., Ltd.; "Multi Ace 20(S)" and "Refined Palm Oil(S)" from Nisshin Oillio Group Ltd.; and "Hydrogenated Castor Oil" from Ito Oil Co., Ltd. 【0048】 In this embodiment, the viscosity of the vegetable oil (including natural vegetable oil and modified vegetable oil) is preferably 1000 mPa·s or less at 25°C, more preferably 20 to 1000 mPa·s, even more preferably 50 to 1000 mPa·s, and even more preferably 100 to 800 mPa·s. 【0049】 In this embodiment, the biomass plasticizer (B) may be a modified vegetable oil modified by epoxy groups, amino groups, or ester bonds. In this case, the modifying groups (epoxy groups, amino groups, or ester bond functional groups) in the biomass plasticizer (B) in this embodiment do not substantially polymerize with other components (including styrene resin (a)) or with each other in the styrene resin composition. 【0050】 In this embodiment, the melting point of the biomass plasticizer (B) is preferably -30 to 80°C, more preferably -25 to 77°C, even more preferably -22 to 74°C, even more preferably -18 to 70°C, even more preferably -15 to 67°C, even more preferably -10 to 64°C, even more preferably -8 to 61°C, even more preferably -5 to 58°C, even more preferably -3 to 55°C, and particularly preferably -1 to 52°C. If the melting point of the biomass plasticizer (B) is above 80°C, the biomass plasticizer (B) will not melt easily in the styrene resin (a), making addition or mixing difficult. On the other hand, if the melting point of the biomass plasticizer (B) is below -30°C, it is necessary to use a compound containing many unsaturated bonds as the type of biomass plasticizer (B) that can be used, which makes it prone to oxidative degradation and deterioration of physical properties. Generally speaking, since all double bonds in natural vegetable oils are in the cis configuration, it is thought that the more double bonds there are, the weaker the intermolecular forces become, and the lower the melting point tends to be. 【0051】 In this embodiment, the SP value of the styrene resin (a) and the SP value of the biomass plasticizer (B) ((cal / cm) 3 ) 1 / 2 The difference from ) is preferably less than ±2.5, more preferably less than 2.4, more preferably less than ±2.3, more preferably less than 2.2, more preferably less than 2.1, more preferably less than 2.0, more preferably less than 1.9, more preferably less than 1.8, more preferably less than 1.7, more preferably less than 1.6, more preferably less than 1.5, more preferably less than 1.4, more preferably less than 1.3, more preferably less than 1.2, even more preferably less than ±1.1, even more preferably less than ±1.0, even more preferably less than ±0.9, and even more preferably less than ±0.8. If the difference between the SP value of the styrene resin (a) and the SP value of the biomass plasticizer (B) is ±2.5 or more, the two become incompatible. As a result, the biomass plasticizer (B) is difficult to disperse uniformly in the styrene resin composition, and the overall mechanical strength of the styrene resin composition tends to decrease. Furthermore, the SP value of the styrene resin (a) in this embodiment is 7 to 11 ((cal / cm²).3 ) 1 / 2 Preferably, it is 7.5 to 10.5 ((cal / cm²) 3 ) 1 / 2 ), more preferably 7.8 to 10.2 ((cal / cm 3 ) 1 / 2 ), more preferably 8.0 to 10.0 ((cal / cm 3 ) 1 / 2 ) and more preferably 8.0 to 9.8 ((cal / cm 3 ) 1 / 2 ), more preferably 8.0 to 9.6 ((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 to 9.4 ((cal / cm 3 ) 1 / 2 ), more preferably 8.0 to 9.2 ((cal / cm 3 ) 1 / 2 ), more preferably 8.0 to 9.0 ((cal / cm 3 ) 1 / 2 ) Furthermore, the lower limit of the SP value of the biomass plasticizer (B) in this embodiment is 7.4 ((cal / cm²). 3 ) 1 / 2 It is more preferable that it be 7.5 (cal / cm³ or higher, and more preferably 7.5 (cal / cm³). 3 ) 1 / 2 ) or more, more preferably 7.6 ((cal / cm 3 ) 1 / 2 ), more preferably 7.7 ((cal / cm 3 ) 1 / 2 ) or more, more preferably 7.8 ((cal / cm 3 ) 1 / 2 ) or more. The upper limit of the SP value is 10.5 ((cal / cm³). 3 Preferably it is 10.4 ((cal / cm²) or less, and more preferably 10.4 ((cal / cm²) 3 ) or less, more preferably 10.3 ((cal / cm 3 ) or less, more preferably 10.2 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 10.1 ((cal / cm 3 ) 1 / 2)Hereinafter, more preferably 10.0 ((cal / cm 3 ) 1 / 2 )Hereinafter, more preferably 9.8 ((cal / cm 3 ) 1 / 2 )Hereinafter, more preferably 9.6 ((cal / cm 3 ) 1 / 2 )Hereinafter, more preferably 9.4 ((cal / cm 3 ) 1 / 2 )Hereinafter, more preferably 9.2 ((cal / cm 3 )Hereinafter, more preferably 9.0 ((cal / cm 3 )Hereinafter, even more preferably 8.8 ((cal / cm 3 ) 1 / 2 )Is as follows. Also, in the present embodiment, the preferable range of the SP values of the styrenic resin (a) and the biomass plasticizer (B) can be a range obtained by arbitrarily combining the upper limit and the lower limit of the above SP values. The solubility parameter (SP value) defined in the present embodiment is calculated using the function of the cohesive energy density shown in the following formula. SP value ((cal / cm 3 ) 1 / 2 ) = (△E / V) 1 / 2 Formula (2) (△E represents the intermolecular cohesive energy (heat of vaporization), V represents the total volume of the mixed solution, and △E / V represents the cohesive energy density.) Also, the heat quantity change △Hm due to mixing is represented by the following formula using the SP value. △Hm = V(δ1 - δ2)·Φ1·Φ2 ··· Formula (3) (δ1 represents the SP value of the solvent, δ2 represents the SP value of the solute, Φ1 represents the volume fraction of the solvent, and Φ2 represents the volume fraction of the solute.) From the above formulas (2) and (3), the closer the values of δ1 and δ2 are, the smaller △Hm becomes, and the smaller the Gibbs free energy becomes. Therefore, those with a small difference in SP values have a high affinity. In this specification, the SP value is determined by comparing the solubility of the resin with various solvents whose SP values ​​are known, and calculating the SP value of the unknown resin from the SP value of the solvent with the best compatibility. Specifically, it was calculated using the turbidity titration method described in the Examples section. In this embodiment, the value mainly used is calculated from the monomer composition. In this embodiment, a high boiling point for the biomass plasticizer (B) is preferable (for example, 260°C or higher, which is the molding temperature for injection blow molding) because a high boiling point reduces the amount of gas generated during molding, thus being advantageous for reducing mold contamination. When the SP value of the biomass plasticizer (B) is within the above range, the intermolecular cohesion energy, i.e., the heat of vaporization, can be controlled within a predetermined range, and thus tends to result in a high boiling point that can reduce the amount of gas generated during molding. 【0052】 In this embodiment, examples of mineral oil include atmospheric residue obtained by atmospheric distillation of crude oil such as paraffinic crude oil (including liquid paraffin), intermediate crude oil, and naphthenic crude oil; distillates obtained by vacuum distillation of these atmospheric residues; mineral oil obtained by subjecting the distillates to one or more refining treatments such as solvent delamination, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining; and mineral oil obtained by isomerizing wax (GTL wax) produced by the Fischer-Tropsch process, etc. These mineral oils may be used individually or in combination of two or more types. In this embodiment, when using a mixture of modified vegetable oil and mineral oil as the biomass plasticizer (B), there are no particular restrictions as long as the total biomass carbon ratio (pMC ratio) of the biomass plasticizer (B) is 10% or more. For example, it is preferable to mix 10 to 100 parts by mass of the biomass plasticizer (B) with 100 parts by mass of the modified vegetable oil, and more preferably 10 to 50 parts by mass. In this embodiment, when using a mixture of vegetable oil and mineral oil as the biomass plasticizer (B), there are no particular restrictions as long as the total biomass carbon ratio (pMC%) of the biomass plasticizer (B) is 10% or more. 【0053】 <Optional addition ingredients> In addition to components (A) and (B) described above, the styrene resin composition of this embodiment may contain, as necessary, known additives, processing aids, and other optional additives, provided that they do not impair the effects of the present invention. These optional additives may include dispersants, antioxidants, weathering agents, antistatic agents, fillers, antiblocking agents, colorants, higher fatty acid compound blooming inhibitors, surface treatment agents, antibacterial agents, eye discharge inhibitors (such as silicone oil, higher fatty acid compounds, monoamide compounds of higher aliphatic carboxylic acids, and monoester compounds obtained by reacting higher aliphatic carboxylic acids with monovalent to trivalent alcohol compounds, as described in Japanese Patent Application Publication No. 2009-120717). 【0054】 In this embodiment, the dispersant can be a fatty acid ester compound, polyethylene glycol compound, terpene compound, rosin compound, fatty acid amide, fatty acid compound, or fatty acid metal salt. Examples of the above-mentioned antioxidants include phenolic compounds, phosphorus compounds, and thioether compounds. The above-mentioned higher fatty acid compound acts as a mold release agent and may be one or more selected from the group consisting of higher fatty acids and metal salts of higher fatty acids. The higher fatty acid is a saturated linear carboxylic acid having 12 to 22 carbon atoms, such as stearic acid, lauric acid, myristic acid, palmitic acid, and behenic acid. The metal salt of the higher fatty acid is a metal salt of a saturated linear carboxylic acid having 12 to 22 carbon atoms. Examples of such metals include zinc, calcium, magnesium, aluminum, barium, lead, lithium, potassium, and sodium. When using both a higher fatty acid and a higher fatty acid salt as the higher fatty acid compound, the total amount of the higher fatty acid and the higher fatty acid salt should be within the range of 0.02 to 2.5% by mass, and these higher fatty acids or higher fatty acid salts can be used individually or as a mixture of two or more. The total content of the above optional additives may be 0.05 to 5% by mass relative to the entire styrene resin composition. 【0055】 In this embodiment, the styrene-based resin composition preferably does not contain metal elements, except for unavoidable impurities. More specifically, the content of metal elements is preferably less than 3% by mass, less than 1% by mass, and more preferably less than 0.5% by mass, based on the total amount (100% by mass) of the styrene-based resin composition. If the styrene-based resin composition contains metal elements, especially metal particles, not only will the mold used during molding be damaged, but there is also a risk that metal powder from the mold will be mixed into the styrene-based resin composition. The above-mentioned metallic elements refer to the elements in groups 2 through 12 of the periodic table, the elements in group 1 excluding hydrogen, the elements in group 13 excluding boron, and the elements Ge, As, Sn, Pb, As, Sb, Bi, Se, Te, Po, and At. These metallic elements can be used individually or as alloys or mixtures of two or more elements. 【0056】 The styrene-based resin composition of this embodiment may consist substantially only of component (A), component (B), and an optional additive. Alternatively, it may consist only of component (A) and component (B), or only of component (A), component (B), and an optional additive. "Substantially consisting only of component (A), component (B), and optional additives" means that, with respect to the total amount of the styrene resin composition, preferably 85 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, and even more preferably 98 to 100% by mass, consists of component (A) and component (B), or component (A), component (B), and optional additives. Furthermore, the styrene-based resin composition of this embodiment may contain unavoidable impurities in addition to component (A), component (B), and optional additives, as long as the effects of the present invention are not impaired. 【0057】 When a modified vegetable oil is used as the biomass plasticizer (B) contained in the styrene-based resin composition of this embodiment, the content of the hydroxyl group-containing compound is preferably less than 3% by mass, more preferably less than 2% by mass, and even more preferably less than 1% by mass, relative to the total amount (100% by mass) of the styrene-based resin composition. The hydroxyl group-containing compound in this embodiment refers to compounds that have hydroxyl groups in the polymer, such as (meth)acrylic acid, maleic acid, and phthalic acid. If the hydroxyl group-containing compound is 3% by mass or more, it reacts with the modified vegetable oil, causing gelation, which negatively affects moldability or deterioration of the appearance of the injection-molded article. When a natural vegetable oil is used as the biomass plasticizer contained in the styrene-based resin composition, the amount of the hydroxyl group-containing compound is not specified. 【0058】 [Physical properties of styrene-based resin compositions] <Melt Flow Rate (MFR)> The melt flow rate of the styrene-based resin composition in this embodiment is preferably 1.5 g / 10 min or more, and more preferably 2.0 g / 10 min or more. Below 1.5 g / 10 min, the fluidity is low, and the processing temperature needs to be increased. In another embodiment, the melt flow rate of the styrene-based resin composition is 3.0 to 13.0 g / 10 min, preferably 3.3 to 11.5 g / 10 min, preferably 3.5 to 10.0 g / 10 min, and even more preferably 4.0 to 9.5 g / 10 min. If the melt mass flow rate is lower than 3.0 g / 10 min, the fluidity is poor, and insufficient filling is likely to occur during molding. Molding becomes possible by increasing the molding temperature and core temperature, but the release balance is disrupted, making it easy for uneven wall thickness to occur and resulting in poor quality products. Furthermore, if the melt mass flow rate exceeds 13.0 g / 10 min, a defect called stringing is likely to occur between the injection mold and the parison, making continuous molding difficult. In this disclosure, the melt flow rate is a value measured in accordance with ISO 1133 under conditions of a temperature of 200°C and a load of 49N. <Vicat softening temperature> The Vicat softening temperature of the styrene-based resin composition of this embodiment is preferably 50°C to 100°C, more preferably 55°C to 98°C, more preferably 60°C to 97°C, more preferably 63°C to 96°C, and even more preferably 65°C to 95°C. 【0059】 A particularly preferred form of the styrene-based resin composition of this embodiment contains 90 to 99.9% by mass of a rubber-modified styrene-based resin (A) containing a polymer matrix phase containing a styrene-based resin (a) and a rubbery polymer dispersed in the polymer matrix phase, and 0.1 to 10% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more. The content of (meth)acrylonitrile monomer units is 10% by mass or less relative to the entire polymer matrix phase, and the SP value of the polymer matrix phase is 8.0 to 9.0. The SP value of the aforementioned biomass plasticizer (B) is 7.5 to 8.8. The styrene-based resin composition is characterized in that the absolute difference between the SP value of the polymer matrix phase and the SP value of the biomass plasticizer (B) is 0.8 or less, and the halogen-based flame retardant content is less than 1% by mass. This makes it possible to provide a styrene-based resin composition that reduces environmental impact by using biomass raw materials, exhibits high mechanical strength, excellent appearance characteristics, and superior sheet or injection blow moldability during molding, and is particularly suitable for injection blow molding. The SP value of the polymer matrix phase may be the SP value of the styrene-based polymer (a-1) constituting the polymer matrix phase. Furthermore, the rubbery polymer may be rubbery polymer particles. 【0060】 [Method for producing styrene-based resin compositions] The styrene-based resin composition of this embodiment can be manufactured by directly adding each component as a polymerization raw material to the polymerization process and the defoliation process, or by melt-kneading each component in any way. For example, methods include using a high-speed agitator such as a Henschel mixer, a batch-type kneader such as a Banbury mixer, a single-screw or twin-screw continuous kneader, a roll mixer, etc., either individually or in combination. The heating temperature during kneading is usually selected in the range of 180 to 250°C. 【0061】 [Molded products] The molded article of the present invention is characterized by containing the above-mentioned styrene-based resin composition. The styrene-based resin composition of this embodiment can be used to produce molded articles by the above-described melt-mixing and molding machine, or by using the resulting styrene-based resin composition pellets as raw materials, through injection molding, injection compression molding, extrusion molding, blow molding, press molding, vacuum molding, foam molding, and the like. 【0062】 The molded article of this embodiment can be obtained by molding the styrene-based resin composition of the above embodiment. The molded article of this embodiment is not particularly limited as long as it is obtained by molding the styrene-based resin composition according to the present invention as described above, but it is preferable that the molded article has a portion with a thickness of 1 mm or less. The above styrene-based resin composition can be suitably used in a molded article having a portion with a thickness of 1 mm or less. Furthermore, the molded article of this embodiment is not particularly limited, but is preferably a container or a sheet. The container of this embodiment may be manufactured (molded) directly from a styrene-based resin composition, or it may be manufactured by further molding a sheet obtained by molding a styrene-based resin composition. In addition, the sheet of this embodiment can be used to manufacture (mold) other molded articles as well as containers. 【0063】 The sheet of this embodiment is a non-foamed extruded sheet, and its thickness is not particularly limited but can be, for example, 1.0 mm or less, and preferably 0.2 to 0.8 mm. 【0064】 The sheet of this embodiment may be used in a multilayer structure with a general styrene-based resin such as polystyrene resin, or it may be used in a multilayer structure with a resin other than styrene-based resin in addition to, or instead of, the styrene-based resin layer. Examples of resins other than styrene-based resins include PP resin, PP / PS resin, PET resin, nylon resin, etc. 【0065】 The container of this embodiment is a container obtained by injection blow molding using the above-mentioned styrene-based resin composition, or a container obtained by molding the above-mentioned sheet. Specifically, the container obtained by injection blow molding in this embodiment is not particularly limited, but examples include a container for storing or containing beverages such as lactic acid bacteria beverages or foods such as fermented milk. The container can be a vertical cylindrical shape with a flange surface at the opening and the opening facing upwards. The container can be made up to 50-120 mm in height, 30-60 mm in diameter, and 0.2-0.8 mm in thickness. Furthermore, the container obtained by molding the above-mentioned sheet in this embodiment is not particularly limited, and examples include a lid for a bento box or a container for holding side dishes, etc., molded from the sheet or a multilayer body containing the same. 【0066】 Molded articles containing the styrene-based resin composition of this embodiment, particularly injection-molded articles (including injection-compressed articles), are suitably used in food containers, photocopiers, fax machines, personal computers, printers, information terminals, office automation equipment such as refrigerators, vacuum cleaners, and microwave ovens, household electrical appliances, housings and various parts for electrical and electronic equipment, interior and exterior components for automobiles, construction materials, foamed insulation materials, insulating films, and the like. [Examples] 【0067】 The embodiments of the present invention will be described in more detail below based on examples and comparative examples, but the present invention is not limited in any way by these embodiments. 【0068】 "1. Measurement and Evaluation Methods" The physical property measurements and evaluations of the styrene resin compositions, sheets, and injection blow molded articles obtained in each of the examples and comparative examples were carried out based on the following methods. 【0069】 (1) Measurement of the weight average molecular weight of the styrene resin (a) in the rubber-modified styrene resin (A) used in the examples and comparative examples The weight average molecular weight of the styrene resin (a) was measured under the following conditions and procedures. · Sample preparation: 5 mg of the measurement sample was dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 μm filter. · Measurement conditions Apparatus: TOSOH HLC-8220GPC (Gel Permeation Chromatography) Columns: Two SHODEX GPC KF-606M columns connected in series Guard column: SHODEX GPC KF-G 4A Temperature: 40 °C Carrier: THF 0.50 mL / min Detector: RI, UV: 254 nm Calibration curve: For the preparation of the calibration curve, eleven types of TSK standard polystyrenes (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) manufactured by Tosoh Corporation were used. A calibration curve was prepared using a third-order linear approximation formula. 【0070】 (2) Melt mass flow rate (MFR) The melt mass flow rate (g / 10 min) of the styrene resin (a) in the rubber-modified styrene resin (A) used in the examples and comparative examples was measured in accordance with ISO 1133 (200 °C, load 49 N). 【0071】 (3) Measurement of Vicat softening temperature (°C) The Vicat softening temperature (°C) of the rubber-modified styrene resin (A) and the styrene resin composition used in this example and comparative examples was measured at a load of 49 N in accordance with ISO 306. 【0072】 (4) Measurement of the content and swelling index of rubbery polymer particles (toluene-insoluble matter) The content (mass%) of rubber-like polymer particles and the swelling index in rubber-modified styrene resin (A) or styrene resin composition were measured as follows. 1.00 g of rubber-modified styrene resin or styrene resin composition was accurately weighed into a sedimentation tube (this mass is denoted as W1), 20 ml of toluene was added, and the mixture was shaken at 23°C for 2 hours. Then, it was centrifuged in a centrifuge (Sakuma Seisakusho Co., Ltd., SS-2050A, rotor: 6B-N6L) at a temperature of 4°C, a rotation speed of 20,000 rpm, and a centrifugal acceleration of 45,100 × G for 60 minutes. The sedimentation tube was slowly tilted to approximately 45 degrees, and the supernatant was decanted and removed. The mass of the toluene-insoluble matter was accurately weighed (this mass is denoted as W2), and subsequently, it was vacuum-dried at 160°C and below 3 kPa for 1 hour. After cooling to room temperature in a desiccator, the mass of the toluene-insoluble matter was accurately weighed (this mass is denoted as W3). The content of rubbery polymer particles and the swelling index in the styrene-based resin (A) or styrene-based resin composition were determined using the following formula. Content of rubbery polymer particles = W3 / W1 × 100 Swelling index of rubbery polymer particles = W2 / W3 【0073】 (5) Measurement of average particle size The average particle size (μm) of the rubbery polymer in the rubber-modified styrene resin (A) or styrene resin composition used in the examples and comparative examples was measured by the following method. Using a COULTER MULTISIZER III (product name) manufactured by Beckman Coulter, Inc., equipped with a 30 μm diameter aperture tube, 0.05 g of rubber-modified styrene resin (A) pellets or styrene resin composition pellets were placed in approximately 5 ml of dimethylformamide and left for approximately 2 to 5 minutes. Next, the dissolved content in dimethylformamide was measured at an appropriate particle concentration, and the median diameter based on volume was determined. 【0074】 (6) Measurement of the content of rubbery polymer 0.25 g of the rubber-modified styrene resin (A) or styrene resin composition used in the examples and comparative examples was dissolved in 50 mL of chloroform, iodine monochloride was added to react the double bonds in the rubber component, potassium iodide was added to convert the remaining iodine monochloride into iodine, and the mixture was back-titrated with sodium thiosulfate (iodine monochloride method). By this method, the mass of rubber contained in the rubber-modified styrene resin (A) or styrene resin composition (denoted as W4) was measured, and the content (mass %) of the rubber-like polymer in the rubber-modified styrene resin (A) or styrene resin composition was calculated from this value and the mass of the rubber-modified styrene resin (A) or styrene resin composition (denoted as W1) using the following formula. Content (mass%) of rubber-like polymer in rubber-modified styrene resin (A) or styrene resin composition = W4 / W1 × 100 【0075】 (7) Method for measuring the biomass carbon ratio (pMC%) The biomass carbon ratio (pMC%) of biomass plasticizer (B) is based on radiocarbon (in accordance with ASTM-D6866). 14 C) Depending on the measurement method, the following formula (1) is used by the AMS method ( 14 C plasticizer / 12 C plasticizer) / ( 14 C standard material / 12 The C standard substance was calculated. Formula (1): Biomass carbon ratio (pMC%) = ( 14 C plasticizer / 12 C plasticizer) / ( 14 C standard material / 12 C standard material)×100 In addition, oxalic acid (SRM4990) was used as the standard substance. 【0076】 (8) Determination of the content of biomass plasticizer (B) The content of biomass plasticizer (B) in the styrene-based resin compositions used in the examples and comparative examples was determined using either procedure (8-1) or (8-2) below. The values ​​obtained using procedure (8-1) and procedure (8-2) yielded comparable results. (8-1) Analysis using NMR Vegetable oil (glycerin fatty acid ester) is dissolved in deuterated chloroform (containing 1% TMS) with 2-dimethoxyethane as an internal standard. 1 ¹H-NMR measurements were performed. Using the TMS peak as the baseline of 0 ppm, peaks originating from protons bonded to carbons adjacent to the ester group of the vegetable oil were detected at δ 4.0–4.4 ppm, and peaks originating from 1,2-dimethoxymethane were detected at 3.4–3.6 ppm. The peak area originating from the vegetable oil was calculated, with the peak area originating from 1,2-dimethoxymethane set to 1. By performing this operation while varying the concentration of the vegetable oil, a calibration curve for vegetable oil concentration was created. Dissolve the pelletized styrene resin composition obtained in the example or comparative example in deuterated chloroform (containing 1% TMS), 1 The vegetable oil content in the styrene-based resin composition was quantified by performing 1H-NMR measurements and using the calibration curve described above. In the above method, if other peaks overlap with the internal standard peak, making quantification difficult, a suitable substance may be used as the internal standard. Furthermore, vegetable oil can also be quantified using the triglyceride-derived peak detected at 5.0–5.5 ppm. (8-2) Calculation from methanol-soluble content 1.0 g (denoted as W11) of the pelletized styrene resin composition obtained in the example or comparative example was placed in a 20 mL screw-top bottle, and 10 mL of methyl ethyl ketone was added. After completely dissolving the pellet using a shaker, 5 mL of methanol was added to precipitate the styrene polymer as an insoluble substance, and the mixture was centrifuged at 2000 G for 10 minutes to allow the insoluble substance to settle. The settled insoluble substance was then pre-dried in a dryer heated to 140 °C for 40 minutes, followed by vacuum drying at the same temperature for 20 minutes to completely evaporate the solvent. The mass of the dried insoluble substance was measured and designated as W12. The methanol-soluble content (W13) was defined as follows using the measured masses W11 and W12. The methanol-soluble portion (W13) was calculated as W11 - W12. Furthermore, in this procedure, the supernatant liquid after centrifugation was measured by GC-MS to quantify the content of styrene oligomers, residual monomers, residual solvents, and other low-molecular-weight substances other than methanol-soluble plasticizers, and the mass (W14) contained in 1.0 g of the styrene resin composition was calculated. Using the calculated masses W13 and W14, the content of biomass plasticizer (B) in the styrene resin composition was determined as follows. Biomass plasticizer (B) content = W13 - W14 【0077】 (9) Calculation of SP value The SP values ​​of each material used in the examples and comparative examples were obtained using the Hilderbrand method (including the Hansen method), and were calculated by turbidity titration with reference to literature values ​​("Fundamentals of Biomaterials," edited by Kazuhiko Ishizuka, Takao Hanawa, and Mizuo Maeda, Nippon Igakukan Publishing) or "J.Appl.Polym.Sci., 12, 2359 (1968)". In the case of the styrene-based resin compositions of the examples and comparative examples, since each component blended in the composition is known, the SP value can be easily calculated using the method described above. On the other hand, if the details of the styrene-based polymer or plasticizer contained in an unknown styrene-based resin composition are unknown, the SP value can be calculated by the following procedure (i) to (iv). Procedure (i): A dissolution test is performed to determine whether the sample (styrene-based polymer or plasticizer) to be recovered or separated from the styrene-based resin composition has dissolved in a solvent with a known SP value. Procedure (ii): Next, the SP values ​​of the solvents used in the dissolution test in procedure (i) are plotted in three dimensions. Procedure (iii): Procedures (i) and (ii) are performed with 15 to 20 different solvents. Procedure (iv): A sphere is calculated that includes the coordinates of the solvent in which the sample dissolved, but does not include the coordinates of the solvent in which the sample did not dissolve. The coordinates of the center of this sphere represent the Hansen SP value, and the distance from the origin represents the Hildebrand SP value. Thus, the solubility parameter is calculated using the Hildebrand method (including the Hansen method). The SP values ​​calculated by the above procedures (i) to (iv) are in general agreement with the values ​​in the above literature or the SP values ​​calculated by the turbidity titration method. Furthermore, it is visually confirmed whether the sample is soluble or insoluble in a solvent with a known SP value. Specifically, if the sample is insoluble, when it is dissolved in the solvent, it will become cloudy or form droplets, causing the sample and solvent to separate. On the other hand, if it is soluble, when the sample is dissolved in the solvent, it will mix uniformly while remaining transparent. Furthermore, if the biomass plasticizer (B) is low molecular weight, it may not be possible to calculate it using the turbidity titration method. In that case, Fedors' estimation method or Hoy's calculation method should be used instead of the above turbidity measurement method (see, for example, "Research on Paints (Considerations on Solubility Parameters of Additives) No. 152 Oct. 2010"). 【0078】 (10) Calculation of the degeneration rate For styrene resins containing modified vegetable oil, use either procedure (10-1) or (10-2) below. 1 The degree of modification of modified vegetable oil is calculated using 1H-NMR. Procedure (10-1) Dissolve the pelletized styrene resin composition obtained in the example or comparative example in deuterated chloroform (containing 1% TMS), 1 ¹H-NMR measurements were performed. Using TMS as the reference (0 ppm), peaks originating from epoxy groups were observed at δ2.8–3.2 ppm, and peaks originating from protons bonded to carbons adjacent to the ester groups of the vegetable oil were observed at δ4.0–4.4 ppm. The epoxy modification rate was calculated from the area ratio of these two peaks. Peaks originating from epoxy groups were detected at δ2.8–3.2 ppm, and peaks originating from protons bonded to carbons adjacent to the ester groups of the vegetable oil were detected at δ4.0–4.4 ppm. However, if these peaks overlap with other peaks, quantification becomes difficult, so in that case, quantification is performed using the method described in the following procedure (10-2). Procedure (10-2) One g of the pelletized styrene resin composition obtained in the example or comparative example was placed in a 20 mL screw-top bottle, and 10 mL of methyl ethyl ketone was added. After completely dissolving the pellets with a shaker, 5 mL of methanol was added, causing the styrene resin composition to precipitate as insoluble matter in the solution. Next, the insoluble matter was removed, and the solution was placed in a round-bottom flask. The solution was then vacuum-evaporated for 2 hours using an evaporator to volatilize the methyl ethyl ketone and methanol. Subsequently, the liquid remaining in the round-bottom flask (vegetable oil) was added to deuterated chloroform (containing 1% TMS), 1 ¹H-NMR measurements were performed. Using TMS as the baseline of 0 ppm, peaks originating from epoxy groups were observed at δ2.8–3.2 ppm, and peaks originating from protons bonded to carbons adjacent to ester groups in the vegetable oil were observed at δ4.0–4.4 ppm. The epoxy modification rate was calculated from the ratio of the areas of these two peaks. 【0079】 (11) Nominal strain at sheet tensile fracture The tensile fracture nominal strain of the extruded sheets prepared in the examples and comparative examples was measured. Specifically, a JIS K6251-3 dumbbell was punched out from the extrusion (MD) direction and the orthogonal (TD) direction of the extruded sheet, and a tensile test was performed under the conditions of a test speed of 50 mm / min and a grip distance of 60 mm, and the tensile fracture nominal strain was measured. 【0080】 (10) Evaluation of the seat appearance During the preparation of the extruded sheets obtained in the examples and comparative examples, the sheet surface was visually inspected, and the number of stains with a major axis of 1.0 mm or more per 10 m was measured. 【0081】 "2. Ingredients" The materials used in the examples and comparative examples are as follows. [Rubber-modified styrene resin (A) (HIPS)] ·The rubber-modified styrene resin (A)(1) with MFR 3.0 (HIPS, manufactured by PS Japan Co., Ltd., HT478) was used. The styrene resin (a) which is the polymer matrix phase of the rubber-modified styrene resin (A)(1) is polystyrene (Mw = 180,000), and the average particle diameter of the rubber-like polymer (salami structure encapsulating polystyrene) was 1.7 μm. ·The rubber-modified styrene resin (A)(2) with MFR 2.3 (HIPS, manufactured by PS Japan Co., Ltd., 475D) was used. The styrene resin (a) which is the polymer matrix phase of the rubber-modified styrene resin (A)(1) is polystyrene (Mw = 220,000), and the average particle diameter of the rubber-like polymer (salami structure encapsulating polystyrene) was 2.3 μm. 【0082】 [Biomass plasticizer (B)] (Modified vegetable oil) ·Epoxidized soybean oil (product name "New Sizer 510R" (manufactured by NOF Corporation), weight average molecular weight (Mw = 1500), biomass carbon ratio (pMC%) 100%, melting point: 5 °C, SP value (calculated value by Hansen method, distance from the origin in the three-component coordinates of the dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 9.0 ((cal / cm 3 ) 1 / 2 )), epoxy modification rate: 5 mmol per 1 g ·Epoxidized linseed oil (product name "New Sizer 512" (manufactured by NOF Corporation), weight average molecular weight (Mw = 1500), biomass carbon ratio (pMC%) 100%, melting point: 5 °C) SP value (calculated value by Hansen method, distance from the origin in the three-component coordinates of the dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 9.3 ((cal / cm 3 ) 1 / 2 )), epoxy modification rate: 8 mmol per 1 g (Natural vegetable oil) · Palm oil (product name "Multi Ace 20(S)" (Nisshin Oillio Group, Ltd.), weight-average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point: 22 °C, SP value (calculated value by Hansen method, distance from the origin in the three-component coordinates of the dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 8.2 ((cal / cm 3 ) 1 / 2 )) · Soybean oil (product name "Soybean White Strained Oil (S)" (Nisshin Oillio Group, Ltd.), weight-average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point -8 °C, SP value (calculated value by Hansen method, distance from the origin in the three-component coordinates of the dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 8.2 ((cal / cm 3 ) 1 / 2 )) · Castor oil (product name "Castor Oil" (Ito Oil Co., Ltd.), weight-average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point 85 °C, SP value (calculated value by Hansen method, representing the distance from the origin in the three-component coordinates of the dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 10.1 ((cal / cm 3 ) 1 / 2 )) 【0083】 [Others] (Liquid paraffin) · Liquid paraffin, product name "PS350S" (manufactured by Sanko Chemical Industries, Ltd.), weight-average molecular weight (Mw = 250), biomass carbon ratio (pMC%) 0%, pour point: -12.5 °C, SP value (literature value): 7.3 (cal / cm 3 ) 1 / 2 (Polylactic acid) · Polylactic acid, product name "LX175" (manufactured by Total Corbinion PLA), biomass carbon ratio (pMC%) 100%, melting point: 155 °C, SP value (literature value): 10.3 (cal / cm 3 ) 1 / 2 【0084】 "3. Examples and Comparative Examples" [Examples 1-8 and Comparative Examples 1-4] The rubber-modified styrene resin (A) and biomass plasticizer (B) were dry-blended in the proportions shown in Table 3 below. The mixture was then extruded using a twin-screw extruder (TEM-26SS-12, manufactured by Toshiba Machine Co., Ltd.) at a resin temperature of 220°C to produce the styrene resin compositions of Examples 1-8 and Comparative Examples 1-4, respectively. The physical properties of the obtained styrene-based resin composition were measured using the method described in "1. Measurement and Evaluation Methods" above, as shown in Table 3. Furthermore, each of the obtained styrene-based resin compositions was supplied to a single-screw extruder, and extruded sheets with a thickness of 0.3 mm and a width of 125 mm were produced under conditions of a resin composition temperature of 200°C and a roller temperature of 90°C. The sheet properties of the obtained extruded sheets were then measured using the method described in the "1. Measurement and Evaluation Methods" section above. The sheet thickness (MD direction and TD direction) was measured at five arbitrary positions using a microgauge, and the average value was used. Furthermore, the styrene resin composition obtained in Example 1 was used to form a cylindrical vertical container using an injection blow molding machine (Sumitomo Heavy Industries, Ltd., SG125NP). In this process, injection blow molding was performed with a cylinder and hot runner temperature of 240°C and a mold temperature of 50°C. A 65mm section from the bottom of the resulting cylindrical vertical container was cut horizontally (TD direction) parallel to the bottom surface to serve as a test specimen. A tensile test was performed under the same conditions as the sheet tensile fracture nominal strain measurement described above. The results showed a high fracture point in the TD direction, similar to the sheet. 【0085】 [Table 3] [Industrial applicability] 【0086】 The present invention provides a styrene-based resin composition that reduces environmental impact and exhibits excellent mechanical strength, as well as sheets and injection-blown molded articles made from the styrene-based resin composition. Molded articles obtained from the styrene-based resin composition can be suitably used for sheets, food containers, films, foams, etc., for electrical and electronic equipment such as food containers, computer parts or mobile phone parts, portable information terminals, home appliance parts, automobile parts, industrial materials, and building materials.

Claims

[Claim 1] A polymer matrix phase containing a styrene-based resin (a) and rubber-like polymer particles dispersed in the polymer matrix phase, comprising 82.5 to 99.9% by mass of a rubber-modified styrene-based resin (A), It contains 0.1 to 15% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, The rubbery polymer particles are particles containing a rubbery polymer, and the rubbery polymer is one or more selected from the group consisting of polybutadiene, polybutadiene containing polystyrene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer. The average particle size of the rubbery polymer particles is 0.3 to 7.0 μm. The biomass plasticizer (B) is a styrene-based resin composition comprising a natural vegetable oil, a modified vegetable oil, a mixture of a natural vegetable oil and mineral oil, a mixture of a modified vegetable oil and mineral oil, or a mixture of a natural vegetable oil, a modified vegetable oil, and a mineral oil. [Claim 2] A polymer matrix phase containing styrene resin (a) and rubbery polymer particles dispersed in the polymer matrix phase, comprising 90 to 99.9% by mass of rubber-modified styrene resin (A), The styrene-based resin composition according to claim 1, comprising 0.1 to 10% by mass of a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more. [Claim 3] The absolute value of the difference between the SP value of the styrene resin (a) and the SP value of the biomass plasticizer (B) is 2.5 (cal / cm³). ３ ) １／２ A styrene-based resin composition according to claim 1 or 2, wherein the value is less than [amount missing]. [Claim 4] The SP value of the biomass plasticizer (B) is 7.4 to 10.5 (cal / cm³). ３ ) １／２ The styrene-based resin composition according to any one of claims 1 to 3. [Claim 5] A sheet comprising the styrene-based resin composition according to any one of claims 1 to 4. [Claim 6] An injection blow molded article comprising the styrene-based resin composition according to any one of claims 1 to 4.

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