Styrene-based resin composition and molded article thereof

Abstract

To provide a styrenic resin composition that employs biomass material to reduce environmental load, exhibits superior mechanical strength, and can be molded at low temperatures, and a molded article thereof.SOLUTION: A styrenic resin composition comprises 30-84.9 mass% of a styrenic resin (A) comprising a styrenic monomer unit, and more than 15 mass% and 70 mass% or less 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 molded article made from the styrene-based resin. [Background technology] 【0002】 Due to its moldability and mechanical strength, styrene resins are used in a wide range of applications, including general merchandise and home appliances. Furthermore, with the realization of a low-carbon and circular economy, biomass materials are attracting attention, and 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 discloses a styrene-based resin composition containing 0.1 to 15% by mass of a biomass plasticizer with a biomass carbon ratio (pMC%) of 10% or more. 【0003】 Styrene resins have a wider melting temperature range compared to other thermoplastic resins, and the molding temperature can be set according to the viscosity of the resin and the shape of the molded product. However, when the molding temperature is high, volatile components are more likely to be released from the resin, leading to mold contamination during injection molding and the formation of deposits during sheet molding. In addition, at high molding temperatures, the resin tends to burn in the molding machine cylinder, resulting in a stronger yellowish tint. Furthermore, when molding on an industrial scale, higher molding temperatures consume significantly more power than lower molding temperatures, which is undesirable from an economic and environmental perspective. Therefore, there is a need for resins that can be molded at low temperatures. For example, Patent Document 3 discloses a styrene resin composition with excellent low-temperature moldability. Patent Document 4 also discloses a resin composition for sheet molding that allows for secondary processing at low temperatures after sheet molding. [Prior art documents] [Patent Documents] 【0004】 [Patent Document 1] Japanese Patent Publication No. 2016-199652 [Patent Document 2] International Publication No. 2022 / 114221 [Patent Document 3] Japanese Patent Publication No. 2009-256502 [Patent Document 4] Japanese Patent Application Publication No. 11-228777 [Overview of the Initiative] [Problems that the invention aims to solve] 【0005】 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, making it difficult to design products that satisfy the impact resistance or elasticity required in the market. Furthermore, since polylactic acid is incompatible with styrene resin, recycling of waste materials is difficult. In addition, since polylactic acid is not a plasticizer, it has little effect on improving the fluidity of styrene resin. Therefore, alloys of polylactic acid and styrene resin have low fluidity and are difficult to mold at low temperatures. 【0006】 The technology described in Patent Document 2 above investigates a styrene-based resin composition containing 0.1 to 15% by mass of a biomass plasticizer with a biomass carbon ratio (pMC%) of 10% or more. However, when the content is 0.1 to 15% by mass, it is difficult to significantly lower the molding temperature, which leads to a problem of increased yellowing due to resin burning during melt mixing in the molding machine cylinder or extruder. In addition, volatile components during molding may cause mold contamination and sheet residue. 【0007】 The technology described in Patent Document 3 above investigates a styrene-based resin composition containing a styrene-based resin and a flame retardant, with a melt mass flow rate of 4.0 to 10.0 g / min at 200°C. However, since the melt mass flow rate is within the range of typical styrene-based resins, it is considered that the low-temperature moldability is insufficient. Furthermore, it does not contain biomass materials that take into consideration the reduction of environmental impact. 【0008】 The technology described in Patent Document 4 above investigates a resin composition for sheet molding in which liquid paraffin is added to a rubber-modified styrene resin. However, liquid paraffin has poor compatibility with styrene resins, and high concentrations lead to bleed-out problems. Furthermore, with liquid paraffin, there are concerns that it will volatilize during injection molding or sheet molding, leading to worsening mold contamination in injection molding machines and the generation of resin in the sheet. In addition, it does not contain biomass materials that take into consideration the reduction of environmental impact. Therefore, the above-mentioned Patent Documents 1 to 4 do not consider styrene-based resins using biomass raw materials that reduce environmental impact, have excellent mechanical strength, and can be molded at low temperatures. Therefore, the present disclosure aims to provide a styrene-based resin composition and a molded article thereof that can be molded at low temperatures, have excellent mechanical strength, and reduce environmental impact by using biomass raw materials. [Means for solving the problem] 【0009】 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-based resin composition obtained by mixing a styrene-based 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, thereby completing the present invention. 【0010】 [Changes in morphology due to biomass plasticizer (B) content] In particular, when the compatibility between a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more and a styrene resin (A) is low, increasing the content of the biomass plasticizer (B) in the overall styrene resin composition resulted in significant bleed-out and other issues, making production difficult in some cases. Therefore, the changes in the physical properties (morphology, shear viscosity) of the styrene resin composition at various biomass plasticizer (B) content levels were investigated as follows. When the biomass plasticizer (B) content exceeds 15% by mass, the styrene resin (A) and the biomass plasticizer (B) become less miscible, and it is thought that the morphology changes. As a result, when the biomass plasticizer (B) content is 15% by mass or less, the Vicat softening temperature, which indicates heat resistance, decreases linearly with decreasing content. However, when it exceeds 15% by mass, it has been confirmed that the decrease in the Vicat softening temperature becomes smaller even when the biomass plasticizer (B) content is increased. On the other hand, it has been confirmed that the shear viscosity at the same temperature (180°C, 1000 / sec) decreases with increasing biomass plasticizer (B) content. Therefore, when the biomass plasticizer (B) content increases beyond 15% by mass, molding and processing at lower temperatures becomes possible while maintaining the overall heat resistance of the composition. Table 1 shows the relationship between shear viscosity (180°C, 1000 / sec) and Vicat softening temperature with respect to the biomass plasticizer (B) content. By maintaining the heat resistance of the entire composition, the molded product can maintain its shape without shrinking or deforming due to heat during transportation or the coloring and drying process. [Table 1] Based on the results of the studies in Table 1 above, if phenomena such as bleed-out of the styrene-based resin composition, shrinkage and deformation of molded products due to heat occur significantly, it is more preferable to control the SP value of the biomass plasticizer (B) and the SP value of the styrene-based resin (A) within a specific range. We found that when the SP value of the biomass plasticizer (B) and the SP value of the styrene resin (A) are within a specific range, their compatibility increases, and production is possible without bleed-out even when the content of biomass plasticizer (B) is increased. 【0011】 The present invention is as follows: (1) The present disclosure relates to a styrene resin composition containing 30 to 84.9% by mass of a styrene resin (A) containing styrene monomer units, and more than 15% by mass and 70% by mass or less of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more. 【0012】 (2) In the styrene-based resin composition of this embodiment, it is preferable that the Vicat softening temperature of the styrene-based resin composition is 65°C or lower. 【0013】 (3) In the styrene-based resin composition of this embodiment, it is preferable that the melt viscosity of the styrene-based resin composition, measured at a resin temperature of 180°C and a shear rate of 1000 / sec, is 140 (Pa·sec) or less. 【0014】 (4) In the styrene-based resin composition of this embodiment, it is preferable that the melt viscosity of the styrene-based resin composition, measured at a resin temperature of 180°C and a shear rate of 40 / sec, is 1200 (Pa·sec) or less. 【0015】 (5) In the styrene resin composition of this embodiment, the styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase and rubbery polymer particles (a-2) which are composed of a styrene polymer (a-1) containing the styrene monomer units. The absolute difference between the SP value of the styrene polymer (a-1) 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]. 【0016】 (6) In the styrene resin composition of this embodiment, 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. 【0017】 (7) In the styrene-based resin composition of this embodiment, the SP value of the styrene-based polymer (a-1) is 7.0 to 11.0 (cal / cm²). 3 ) 1 / 2 It is preferable that this be the case. 【0018】 (8) In the styrene resin composition of this embodiment, the styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase composed of a styrene polymer (a-1) and rubbery polymer particles (a-2), Furthermore, it is preferable that the content of the rubbery polymer particles (a-2) is 2 to 40% by mass relative to the total amount (100% by mass) of the styrene-based resin (A), and that the average particle diameter of the rubbery polymer particles (a-2) is 0.3 to 7.0 μm. 【0019】 (9) In the styrene-based resin composition of this embodiment, it is preferable that the content of the styrene monomer units contained in the styrene-based polymer (a-1) is 50% by mass or more relative to the total amount (100% by mass) of the styrene-based polymer (a-1). 【0020】 (10) This embodiment is an injection-molded article obtained by injection molding a styrene-based resin composition described in any one of the above items (1) to (9). 【0021】 (11) This embodiment is a sheet made of the styrene resin composition described in any one of the above items (1) to (9). [Effects of the Invention] 【0022】 According to the present invention, a styrene-based resin composition and a molded article thereof are provided that can be molded at low temperatures while reducing environmental impact and maintaining high mechanical strength by using biomass raw materials. [Modes for carrying out the invention] 【0023】 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. 【0024】 [Styrene resin composition] The styrene resin composition according to this embodiment contains 30 to 84.9% by mass of a styrene resin (A) containing styrene monomer units, and more than 15% to 70% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more. This makes it possible to provide a styrene-based resin composition that reduces environmental impact and enables low-temperature molding with high mechanical strength during molding. Depending on the intended use, further properties may be imparted to the styrene-based resin composition. For example, one preferred embodiment of the styrene-based resin composition of this embodiment is that, when high mechanical strength is important, the styrene-based resin composition may contain rubbery polymer particles (hereinafter referred to as rubbery polymer particles (a-2)). In the case where the styrene-based resin composition of this embodiment contains rubbery polymer particles (a-2), examples include further containing rubbery polymer particles (a-2), such as so-called MBS resin particles, as the styrene-based resin (A), or using a rubber-modified styrene-based resin in which rubbery polymer particles (a-2) are dispersed in a styrene-based polymer (a-1) containing styrene monomer units as a polymer matrix phase as the styrene-based resin (A). 【0025】 "Form containing rubbery polymer particles (a-2)" A preferred styrene resin composition of this disclosure contains 30 to 84.9% by mass of a styrene resin (A) containing styrene monomer units and more than 15% to 70% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, wherein the styrene resin (A) may be a rubber-modified styrene resin containing a polymer matrix phase and rubbery polymer particles (a-2) which are composed of a styrene polymer (a-1) containing the styrene monomer units. In other words, the styrene-based resin composition of this embodiment contains 30 to 84.9% by mass of rubber-modified styrene-based resin and more than 15% to 70% by mass of biomass plasticizer (B) based on the total styrene-based resin composition (100% by mass), and the rubber-modified styrene-based resin may contain a polymer matrix phase and rubbery polymer particles (a-2) having a styrene-based polymer (a-1) containing styrene monomer units as constituent components. This makes it possible to provide a styrene-based resin composition with reduced environmental impact, higher mechanical strength, and superior properties. 【0026】 <Rubber-modified styrene resin> The styrene-based resin composition in this embodiment may contain rubber-modified styrene-based resin. In this embodiment, the content of rubber-modified styrene-based resin is 30 to 84.9% by mass relative to the total styrene-based resin composition (100% by mass), with a lower limit of preferably 35% by mass or more, more preferably 40% by mass or more, even more preferably 45% by mass or more, even more preferably 47.5% by mass or more, even more preferably 50% by mass or more, even more preferably 52.5% by mass or more, even more preferably 55% by mass or more, even more preferably 57.5% by mass or more, and even more preferably 60% by mass or more. The upper limit is preferably 82.5% by mass or less, more preferably 80% by mass or less, even more preferably 78% by mass or less, and even more preferably 76% by mass or less. By setting the content to 30% by mass or more, impact resistance is improved. On the other hand, by setting the content to 84.9% by mass or less, fluidity is improved, and low-temperature moldability can be improved. 【0027】 In this embodiment, the rubber-modified styrene resin is a styrene polymer (a-1) containing styrene monomer units as a polymer matrix phase, in which rubbery polymer particles (a-2) are dispersed. It can be produced by polymerizing styrene monomers in the presence of the rubbery polymer. 【0028】 -Polymer Matrix Phase- The polymer matrix phase of the rubber-modified styrene resin of this embodiment is preferably composed of a styrene polymer (a-1) containing styrene monomer units. The monomer units constituting the styrene polymer (a-1) of this embodiment preferably contain styrene monomer units as essential and optionally contain vinyl monomer units (i) copolymerizable with the styrene monomer units. Therefore, the styrene polymer (a-1) is preferably one or more selected from the group consisting of polystyrene and styrene copolymer resins. Examples of the styrene copolymer resin include styrene-(meth)acrylic acid ester copolymers, as described later. Furthermore, "composed of" means that 50% or more, preferably 70% or more, and more preferably 90% or more, of the total amount of the polymer matrix phase is occupied by the styrene-based polymer (a-1). In this embodiment, the content of styrene monomer units among the monomer units constituting the styrene polymer (a-1) 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 polymer (a-1). The content of styrene monomer units and vinyl monomer units (i) copolymerizable with styrene monomers other than said styrene monomer units in the styrene polymer (a-1) 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, in addition to styrene, examples of styrene-based monomers include 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-based monomers can be used. 【0029】 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. 【0030】 --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. 【0031】 --Styrene-based copolymer resin-- In this embodiment, the styrene copolymer resin 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 monomer units 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, when the total content of styrene monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units in the styrene copolymer resin is taken as 100% by mass, the content of styrene monomer units is preferably in the range of 51 to 98% by mass, more preferably 54 to 96% by mass, more preferably 57 to 93% by mass, and even more preferably 60 to 90% by mass. By setting the content to 51% by mass or more, the refractive index of the styrene copolymer resin (A) can be improved. On the other hand, by setting the content to 98% by mass or less, it becomes difficult to create a desired amount of unsaturated carboxylic acid ester monomer units. In another embodiment, when the total content of styrene monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units is taken as 100% by mass, the preferred content range for styrene monomer units may be 69-98% by mass, 74-96% by mass, or 77-92% by mass. Furthermore, in the styrene copolymer resin of the present invention, when the total content of styrene monomer units, unsaturated carboxylic acid 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 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, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is taken as 100% by mass, the preferred content range for unsaturated carboxylic acid ester monomer units may be 2 to 31% by mass, 4 to 26% by mass, or 8 to 23% by mass. In the styrene copolymer resin of the present invention, when the total content of styrene monomer units, unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units is taken as 100% by mass, the content of unsaturated carboxylic acid monomer units is preferably in the range of 0 to 20% by mass, more preferably 0 to 15% by mass, and even more preferably 0 to 13% by mass. In this embodiment, the content of styrene monomer units (e.g., styrene monomer units), unsaturated carboxylic acid monomer units, and unsaturated carboxylic acid ester monomer units (e.g., methyl methacrylate monomer units) in the styrene copolymer resin 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. 【0032】 Specific examples of the styrene monomers constituting the styrene copolymer resin of this embodiment are the same as those described above, so they will be omitted. The unsaturated carboxylic acid ester monomers constituting the styrene copolymer resin of this embodiment are not particularly limited, but examples include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, and cyclohexyl (meth)acrylate. As a (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. The unsaturated carboxylic acid monomer constituting the styrene copolymer resin of this embodiment is not particularly limited, but (meth)acrylic acid is preferred. 【0033】 In this embodiment, the styrene-based copolymer resin is preferably styrene-(meth)acrylate methyl copolymer, styrene-(meth)acrylate ethyl copolymer, styrene-(meth)acrylate propane copolymer, or styrene-(meth)acrylate butyl copolymer, or styrene-(meth)acrylate methyl-meth)acrylate butyl copolymer. 【0034】 In this embodiment, the weight-average molecular weight (Mw) of the styrene copolymer resin 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. Furthermore, in another embodiment of this model, when importance is placed on impact strength and buckling strength at the mouth, the weight-average molecular weight (Mw) of the styrene copolymer resin is preferably 100,000 to 300,000, more preferably 120,000 to 260,000, even more preferably 140,000 to 240,000, and even more preferably 150,000 to 230,000. The weight-average molecular weight (Mw) is a value obtained using gel permeation chromatography and converted to standard polystyrene. 【0035】 The styrene-based resin (A) in this embodiment may be any resin containing styrene monomer units, and may contain resins containing two or more different styrene monomer units. For example, the styrene-based resin (A) may be a mixture of one or more types of polystyrene and one or more types of styrene copolymer resins, or a mixture of one or more types of polystyrene and one or more types of rubber-modified styrene-based resins. Alternatively, the styrene-based resin (A) in this embodiment may be a mixture of one or more types of rubber-modified styrene-based resins and one or more types of styrene copolymer resins. In this case, the mixing ratio of the rubber-modified styrene-based resin and the styrene copolymer resin can be appropriately changed depending on the intended use. For example, in a system where the amount of rubber-modified styrene-based resin is greater than the amount of styrene copolymer resin, it is preferable that the styrene copolymer resin is contained in an amount of 0.1 to 30% by mass relative to the total amount (100% by mass) of the styrene-based resin (A). On the other hand, in systems where the amount of rubber-modified styrene resin is less than the amount of styrene copolymer resin, it is preferable that the styrene copolymer resin is contained in an amount of 70 to 99.9% by mass relative to the total amount (100% by mass) of styrene resin (A). 【0036】 In this embodiment, it is preferable that the styrene polymer (a-1) 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 the styrene polymer (a-1) or polymer matrix. 【0037】 The content of the styrene polymer (a-1) in this embodiment is preferably 10 to 82.9% by mass, more preferably 15 to 80% by mass, 20 to 75% by mass, even more preferably 25 to 70% by mass, and even more preferably 30 to 65% by mass, based on the total mass (100% by mass) of the styrene resin composition. 【0038】 -Rubber-like polymer- In the styrene-based resin composition of this embodiment, the rubbery polymer particles (a-2) may be included in the styrene-based resin composition as part of the rubber-modified styrene-based resin, or different rubbery polymer particles (a-2) may be further blended with the styrene-based polymer (a-1) and included in the styrene-based resin composition. The rubbery polymer particles (a-2) contained in the rubber-modified styrene resin of this embodiment may, for example, contain a styrene polymer (a-1) on the inside, and / or have a styrene polymer (a-1) grafted onto the outside. Furthermore, the rubbery polymer particles (a-2) of this embodiment include not only a core-shell structure composed of a styrene polymer (a-1) as a core and a rubbery polymer as a shell enclosing the core, but also a salami structure composed of multiple styrene polymers (a-1) as cores and a rubbery polymer as a shell enclosing the multiple styrene polymers (a-1) as cores. 【0039】 As the rubbery polymer or rubbery polymer particles (a-2) or material for the rubbery polymer in this embodiment, 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 structures 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 include HIPS (high-impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), and AES (acrylonitrile-ethylene propylene rubber-styrene copolymer). 【0040】 In this embodiment, the content of the rubbery polymer contained in the rubber-modified styrene resin (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 polymer (a-1) encapsulated within the rubbery polymer particles (a-2)) is more preferably 1.0 to 15% by mass, more preferably 1.2 to 12% by mass, even more preferably 1.5 to 11% by mass, even more preferably 2.0 to 10% by mass, and even more preferably 3 to 9.0% by mass, based on the total amount (100% by mass) of the rubber-modified styrene resin. If the content of the rubbery polymer is less than 1.0% by mass, there is a concern 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 concern that the fluidity of the entire styrene resin composition will decrease. In this disclosure, the content of the rubbery polymer contained in the rubber-modified styrene resin is the value calculated using the method described in the Examples section. 【0041】 In this embodiment, the content of rubbery polymer particles (a-2) contained in the rubber-modified styrene resin (including the content of the rubbery polymer itself (e.g., a conjugated diene polymer such as polybutadiene) and the content of the styrene polymer (a-1) encapsulated within the rubbery polymer particles (a-2)) is preferably 2 to 40% by mass, more preferably 3 to 36% by mass, even more preferably 4 to 32% by mass, even more preferably 5 to 30% by mass, even more preferably 6 to 28% by mass, and even more preferably 7 to 26% by mass, based on the total styrene resin composition (100% by mass). 【0042】 In this embodiment, the average particle size of the rubbery polymer particles (a-2) contained in the rubber-modified styrene resin 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 impact resistance, preferably 0.8 to 3.5 μm, and more preferably 0.8 to 3.0 μm. In this disclosure, the average particle size of the rubbery polymer particles (a-2) contained in the rubber-modified styrene resin is the value calculated by the method described in the Examples section or 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 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 method for measuring the average particle diameter of the rubber-like polymer particles (a-2) described above can be applied to the method for measuring the average particle diameter of rubber-like polymer particles (a-2) contained in the entire styrene resin composition. 【0043】 In this embodiment, the reduced viscosity of the styrene polymer (a-1) contained in the rubber-modified styrene resin (this is an indicator of the molecular weight of the styrene polymer (a-1)) is preferably in the range of 0.50 to 0.85 dL / g, and more preferably in the range of 0.55 to 0.80 dL / g. If the reduced viscosity of the styrene polymer (a-1) is less than 0.50 dL / g, the impact strength decreases, and if the reduced viscosity exceeds 0.85 dL / g, the fluidity decreases. In this disclosure, the reduced viscosity of the styrene polymer (a-1) is the value measured in a toluene solution at 30°C and a concentration of 0.5 g / dL. 【0044】 In this embodiment, when the styrene resin (A) is a rubber-modified styrene resin (HIPS resin), among these rubbery polymers, polybutadiene and styrene-butadiene rubber are particularly preferred, with polybutadiene being the most preferred. 【0045】 -Method for manufacturing rubber-modified styrene resin- In this embodiment, the method for producing the rubber-modified styrene resin 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, the resin 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. 【0046】 In this embodiment, there are no particular limitations on the polymerization method of the styrene polymer (a-1), which is the polymer matrix phase of the rubber-modified styrene resin. 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. 【0047】 -Method for producing styrene copolymer resin- In this embodiment, there are no particular limitations on the polymerization method of the styrene copolymer resin, 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 styrene copolymer resins that can be used in this embodiment. When polymerizing the polymerization raw materials to obtain the styrene copolymer resin, the polymerization raw material composition typically contains a polymerization initiator and a chain transfer agent. Polymerization initiators used in the polymerization of styrene copolymer resins 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 such as di-t-butylperoxide (perbutyl-D), t-butylcumylperoxide, and dicumylperoxide; diacyl peroxides such as acetylperoxide and isobutyrylperoxide; peroxydicarbonates such as diisopropylperoxydicarbonate; peroxyesters such as t-butylperoxyacetate; ketone peroxides such as acetylacetone peroxide; and hydroperoxides such as 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 resins 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 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 resins but also in the production of rubber-modified styrene resins. 【0048】 As a polymerization method for styrene copolymer resins, 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. These 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, provided that 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 greatly. 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. 【0049】 In this embodiment, there are no particular restrictions on the apparatus used in the polymerization step to obtain the styrene copolymer resin, and it may 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 known methods 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. 【0050】 <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 environmental impact. In one embodiment of this product, 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. Furthermore, in this specification, "plasticizer" mainly refers to low-molecular-weight substances with a molecular weight of less than 10,000, which, when added to styrene-based resins, modify the resin and have the effect of improving its fluidity, impact resistance, elasticity, etc. 【0051】 In this embodiment, with respect to the total amount (100% by mass) of the styrenic resin composition, the content of the biomass plasticizer (B) is more than 15% by mass and up to 70% by mass. The lower limit of the content of the biomass plasticizer (B) is preferably 16% by mass or more, more preferably 17% by mass or more, still more preferably 18% by mass or more, and even more preferably 19% by mass or more. The upper limit of the content of the biomass plasticizer (B) is preferably 70% by mass or less, more preferably 65% by mass or less, still more preferably 60% by mass or less, still more preferably 55% by mass or less, still more preferably 52.5% by mass or less, still more preferably 50% by mass or less, still more preferably 47.5% by mass or less, still more preferably 45% by mass or less, still more preferably 42.5% by mass or less, and even more preferably 40% by mass or less. If the content of the biomass plasticizer (B) is too large, depending on the difference in the SP values of the styrenic resin (A) and the biomass plasticizer (B), there is a tendency to easily bleed out. Also, the molded product becomes soft and is likely to deform. On the other hand, if the content of the biomass plasticizer (B) is too small, the fluidity decreases, so the molding temperature rises, and there are concerns about problems such as mold fouling, sheet eye lacquer, and resin burning. As a method of incorporating the biomass plasticizer (B) into the styrenic resin composition, there may be mentioned a method of kneading the styrenic resin (A) (for example, a rubber-modified styrenic resin) and the biomass plasticizer (B) with an extruder, or a method of incorporating the biomass plasticizer (B) into the polymerization raw material composition when polymerizing the polymerization raw materials. 【0052】 The biomass carbon ratio (pMC%) in this specification indicates the carbon concentration (mass ratio) of the biomass-derived component. More specifically, it is the value of the 14 C content obtained by the radiocarbon ( 14 C) measurement method conforming to ASTM-D6866. The radiocarbon ( 14 C) measurement method utilizes the fact that fossil fuels do not contain 14 C and that carbon derived from biomass (or organisms) absorbs 14 C in the atmosphere during the growth period, to measure the 14This method estimates the biomass carbon ratio (pMC%) from the C ratio. Therefore, the C contained in the total carbon atoms in the plasticizer of this embodiment 14 By measuring the proportion of biomass-derived carbon, the proportion of biomass-derived carbon can be calculated. In this invention, the biomass carbon ratio (pMC%) is calculated using the following formula (1) with the method described in the Examples section below. Formula (1): Biomass carbon ratio (pMC%) = ( 14 C plasticizer / 12 C plasticizer) / ( 14 C standard material / 12 C standard material)×100 Furthermore, oxalic acid (SRM4990) was used as the standard substance, and the AMS method was used. 14 C plasticizer / 12 C plasticizer) / ( 14 C standard material / 12 The C standard substance was calculated. 【0053】 The weight-average molecular weight (Mw) of the biomass plasticizer (B) 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 (B) 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. 【0054】 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 specification, "vegetable oil" refers to a general term for oils and fats derived from plants, and includes natural vegetable oils and modified vegetable oils. 【0055】 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. 【0056】 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. 【0057】 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. 【0058】 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. 【0059】 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 modified 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 the styrene resin (A)) or with each other in the styrene resin composition. 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. 【0060】 In this embodiment, the SP value of the styrene polymer (a-1) and the SP value of the biomass plasticizer (B) ((cal / cm) 3 ) 1 / 2The 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. When the difference between the SP value of the styrene polymer (a-1) and the SP value of the biomass plasticizer (B) is ±2.5 or more, the two become less compatible. As a result, when the difference between the SP values ​​of the styrene polymer (a-1) and the biomass plasticizer (B) is large, or when the content of biomass plasticizer (B) is high, the biomass plasticizer (B) tends to bleed out more easily from the styrene resin composition. Therefore, the styrene resin (A) and the biomass plasticizer (B) become difficult to mix, making production difficult. Furthermore, the SP value of the styrene polymer (a-1) in this embodiment is 7-11 ((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 / cm3 ) 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 ) or less, more preferably 10.0 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 9.8 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 9.6 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 9.4 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 9.2 ((cal / cm 3 ) or less, more preferably 9.0 ((cal / cm 3 ) or less, and more preferably 8.8 ((cal / cm 3 ) 1 / 2 ) is less than or equal to the above. Furthermore, in this embodiment, the preferred range of SP values ​​for the styrene polymer (a-1), the styrene polymer (a-3), and the biomass plasticizer (B) may be a range obtained by arbitrarily combining the upper limit of the SP value and the lower limit of the SP value. The solubility parameter (SP value) defined in this embodiment is calculated using the cohesive energy density function shown in the following equation. 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 mixture, and △E / V represents the cohesive energy density.) Furthermore, the change in heat quantity ΔHm due to mixing is expressed 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 equations (2) and (3) above, the closer the values ​​of δ1 and δ2, the smaller ΔHm becomes, and the smaller the Giems free energy. Therefore, materials with a small difference in SP values ​​have a higher affinity for each other. 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. 【0061】 The styrene-based resin composition of this embodiment may, if necessary, contain mineral oil as a mixture of vegetable oil and mineral oil, in addition to the biomass plasticizer (B), as described above. Furthermore, if the biomass plasticizer (B) is a mixture of vegetable oil and mineral oil, it is sufficient if the biomass carbon ratio (pMC%) of the mixture as a whole is 10% or more. Also, when the biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more is a mixture, the content refers to the total amount of the mixture of vegetable oil and mineral oil. Examples of mineral oils in this embodiment include atmospheric residues obtained by atmospheric distillation of crude oils 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 oils 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 oils 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 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. For example, it is preferable to mix 10 to 100 parts by mass of the biomass plasticizer (B) with 100 parts by mass of 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. 【0062】 <Optional additives> The styrene resin composition of this embodiment may contain, in addition to components (A) and (B) above, any known additives, processing aids, or other additive components as needed, provided that they do not impair the effects of the present invention. These additive components may include release agents, flame retardants, dispersants, antioxidants, weathering agents, antistatic agents, fillers, antiblocking agents, colorants, bluing agents, surface treatment agents, antibacterial agents, eye discharge inhibitors (such as silicone oil described in Japanese Patent Publication No. 2009-120717, monoamide compounds of higher aliphatic carboxylic acids, and monoester compounds obtained by reacting higher aliphatic carboxylic acids with monovalent to trivalent alcohol compounds). In this embodiment, the styrene resin composition may contain known flame retardants (phosphorus-based flame retardants, bromine-based halogen-based flame retardants, etc.). However, from the viewpoint of concern about the generation of gases such as hydrogen bromide due to reaction with the biomass plasticizer (B) contained in the styrene resin composition, the content of the halogen-based flame retardant is preferably less than 3% by mass, and more preferably less than 1% by mass, based on the total amount (100% by mass) of the styrene resin composition. 【0063】 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. 【0064】 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. As the above-mentioned release agent, fatty acid compounds or fatty acid metal salts can be used. Examples of the above-mentioned antioxidants include phenolic compounds, phosphorus compounds, and thioether compounds. The total content of the above optional additives may be 0.05 to 5% by mass relative to the entire styrene resin composition. 【0065】 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. More specifically, the styrene resin composition of this embodiment contains a styrene resin (A), a biomass plasticizer (B), and additive components, and the total content of the styrene resin (A), the biomass plasticizer (B), and the additive components is preferably 85 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, even more preferably 98 to 100% by mass, and even more preferably 99 to 100% by mass, based on the total styrene resin composition (100% by mass). Furthermore, the additive components preferably contain one or more selected from the group consisting of mineral oil, mold release agents, flame retardants, dispersants, antioxidants, weathering agents, antistatic agents, fillers, antiblocking agents, colorants, blooming agents, surface treatment agents, antibacterial agents, and anti-eye discharge agents. The styrene resin composition of this embodiment contains a styrene resin (A), a biomass plasticizer (B), and additive components, and the total content of the styrene resin (A) and the biomass plasticizer (B) is preferably 85 to 100% by mass, more preferably 90 to 100% by mass, even more preferably 95 to 100% by mass, even more preferably 98 to 100% by mass, and even more preferably 99 to 100% by mass, based on the total styrene resin composition (100% by mass). Furthermore, the additive components preferably contain one or more selected from the group consisting of mineral oil, mold release agents, flame retardants, dispersants, antioxidants, weathering agents, antistatic agents, fillers, antiblocking agents, colorants, blooming agents, surface treatment agents, antibacterial agents, and anti-eye discharge agents. "Substantially consisting only of component (A), component (B), and additive components" 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, even more preferably 98 to 100% by mass, and even more preferably 99 to 100% by mass, is component (A) and component (B), or component (A), component (B), and optional additive components. Furthermore, the styrene-based resin composition of this embodiment may contain unavoidable impurities in addition to component (A), component (B), and additive components, as long as the effects of the present invention are not impaired. 【0066】 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, and 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. 【0067】 "Physical properties of styrene-based resin compositions" The following describes the preferred physical properties of the styrene-based resin composition according to this embodiment. 【0068】 <Melting viscosity> The melt viscosity (shear viscosity) of the styrene-based resin composition of this embodiment, measured using a Malvern Instruments Model RH10 twin capillary rheometer at a resin temperature of 180°C and a shear rate of 1000 (1 / s), is preferably 140 (Pa·sec) or less, more preferably 130 (Pa·sec) or less, even more preferably 120 (Pa·sec) or less, even more preferably 115 (Pa·sec) or less, even more preferably 110 (Pa·sec) or less, even more preferably 105 (Pa·sec) or less, even more preferably 100 (Pa·sec) or less, even more preferably 95 (Pa·sec) or less, even more preferably 90 (Pa·sec) or less, even more preferably 85 (Pa·sec) or less, even more preferably 80 (Pa·sec) or more, and even more preferably 75 (Pa·sec) or less. When the melt viscosity, measured at a resin temperature of 180°C and a shear rate of 1000 (1 / s), is 140 (Pa·sec) or less, it has the effect of making molding easier, especially at low temperatures in injection molding. Furthermore, the melt viscosity (shear viscosity) measured at a resin temperature of 180°C and a shear rate of 40 (1 / s) is preferably 1200 (Pa·sec) or less, more preferably 1100 (Pa·sec) or less, even more preferably 1000 (Pa·sec) or less, even more preferably 950 (Pa·sec) or less, even more preferably 900 (Pa·sec) or less, even more preferably 850 (Pa·sec) or less, even more preferably 800 (Pa·sec) or less, even more preferably 750 (Pa·sec) or less, even more preferably 700 (Pa·sec) or less, even more preferably 650 (Pa·sec), and even more preferably 600 (Pa·sec) or less. When the melt viscosity, measured at a resin temperature of 180°C and a shear rate of 40 (1 / s), is 1200 (Pa·sec) or less, it has the effect of making the material easier to mold, especially at low temperatures, in sheet molding. Furthermore, the higher the content of biomass plasticizer (B) in the styrene-based resin composition of this embodiment, the more likely it is to have the effect of lowering the overall melt viscosity of the styrene-based resin composition. However, it has been found that if the compatibility between the styrene-based resin (A) and the biomass plasticizer (B) is low, that is, if the SP values ​​of the styrene-based resin (A) and the biomass plasticizer (B) are not within the specified range, problems such as bleed-out are more likely to occur during the manufacture of the styrene-based resin composition or during the production of molded products from the composition, making it difficult to simply increase the content of biomass plasticizer (B) in the styrene-based resin composition. As a result, if the SP values ​​of the styrene-based resin (A) and the biomass plasticizer (B) are not within the specified range, it becomes difficult to lower the melt viscosity of the styrene-based resin composition to the aforementioned range. 【0069】 <Vicat softening temperature> The Vicat softening temperature of the styrene-based resin composition in this embodiment is preferably 30°C to 65°C, more preferably 31°C to 60°C, more preferably 32°C to 58°C, more preferably 33°C to 56°C, more preferably 34°C to 55°C, and even more preferably 35°C to 54°C. If the Vicat softening temperature of the styrene-based resin composition is higher than 60°C, the fluidity decreases, making it difficult to mold at a significantly lower molding temperature. Also, if the Vicat softening temperature of the styrene-based resin composition is low, the molded product tends to shrink and deform more easily due to heat. The Vicat softening temperature (°C) in this disclosure was measured under a load of 49 N in accordance with ISO 306. 【0070】 <Swelling Index> In this embodiment, the swelling index of the styrene-based resin composition containing the rubbery polymer particles (a-2) is preferably 8.5 to 14, more preferably 9.0 to 13, from the viewpoint of impact strength. In another embodiment, the swelling index of the rubbery polymer particles (a-2) of the present invention is preferably 7.0 to 14, more preferably 7.5 to 13.5, and even more preferably 8.0 to 13, from the viewpoint of impact strength. The swelling index is an index representing the degree of crosslinking of the rubber particles. By setting the swelling index within the above range, the styrene-based resin composition of the present invention exhibits excellent impact properties. In this disclosure, the swelling index of the styrene-based resin composition is a value calculated using the method described in the Examples section. 【0071】 [Best Mode] A particularly preferred form of the styrene-based resin composition of this embodiment contains 50 to 80% by mass of a rubber-modified styrene-based resin containing a polymer matrix phase containing a styrene-based resin (A) and a rubbery polymer dispersed in the polymer matrix phase, and more than 20% to 50% 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, has high mechanical strength during molding, and can be molded at low temperatures. 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. 【0072】 [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 alone or in combination. The heating temperature during kneading is usually selected in the range of 120 to 250°C. 【0073】 [Molded body] 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-mentioned 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. 【0074】 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 may be 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) not only containers but also other molded articles. 【0075】 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. 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. 【0076】 "Injection molded body" This disclosure relates to an injection-molded article containing the above-described styrene-based resin composition. A commonly known method can be used to manufacture the injection-molded article using the styrene-based resin composition of this embodiment as a raw material. The molding machine temperature is preferably 110°C to 250°C, more preferably 110°C to 230°C, even more preferably 110°C to 220°C, even more preferably 110°C to 200°C, and even more preferably 110°C to 190°C. If the molding machine temperature is higher than 250°C, the styrene-based resin composition will undergo thermal decomposition, which is undesirable. On the other hand, if the temperature is lower than 110°C, the high viscosity makes molding impossible, which is also undesirable. The styrene resin composition suitable for injection molded articles of this embodiment contains, with respect to the entire styrene resin composition, 10 to 82.9% by mass of a styrene polymer (a-1) and more than 15% to 70% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more. The styrene resin composition preferably contains rubbery polymer particles in an amount of 2 to 40% by mass, and the SP value of the biomass plasticizer (B) is preferably 7.4 to 10.5. 【0077】 Molded articles containing the styrene-based resin composition of this embodiment, particularly injection-molded articles (including injection-compressed articles) and sheets, are suitably used in food packaging 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] 【0078】 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. 【0079】 "1. Measurement and Evaluation Methods" The physical properties of the styrene-based resin compositions, extruded sheets, and injection-molded articles obtained in each example and comparative example were measured and evaluated based on the following methods. 【0080】 (1) Measurement of the weight-average molecular weight of the styrene resin (A) (including rubber-modified styrene resin, styrene polymer (a-1), and the same applies hereinafter), biomass plasticizer (B), and styrene resin composition used in the examples and comparative examples. The weight-average molecular weights of styrene resin (A) and biomass plasticizer (B) were measured under the following conditions and procedures. Sample preparation: 5 mg of the sample was dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 μm filter. • Measurement conditions Equipment: 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℃ Carrier: THF 0.50 mL / min Detector: RI, UV: 254nm Calibration Curve: Eleven types of TSK standard polystyrene manufactured by Tosoh Corporation (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) were used to create the calibration curve. The calibration curve was created using an approximation formula for a cubic straight line. 【0081】 (2) Measurement of the melt viscosity of the resin composition The melt viscosity of the styrene-based resin compositions used in the examples and comparative examples was measured using a Malvern Instruments Model RH10 twin capillary rheometer at a resin temperature of 180°C and shear rates of 40 (1 / s) and 1000 (1 / s). 【0082】 (3) Measurement of Vicat softening temperature (°C) The Vicat softening temperature (°C) of the styrene-based resin compositions used in this example and comparative example was measured at a load of 49 N in accordance with ISO 306. 【0083】 (4) Measurement of the content and swelling index of rubbery polymer particles (a-2) The content (mass%) of rubber-like polymer particles (a-2) and the swelling index in rubber-modified styrene resin 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 1 hour. 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 removed by decantation. The mass of the insoluble matter containing toluene 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 (a-2) 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 (a-2) = W3 / W1 × 100 Swelling index of rubbery polymer particles (a-2) = W2 / W3 【0084】 (5) Measurement of average particle size The average particle size (μm) of the rubbery polymer particles (a-2) in the styrene-based resin (A) or styrene-based 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 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 volume-based median diameter was determined. 【0085】 (6) Measurement of the content of rubbery polymer 0.25 g of the 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 styrene resin (A) or styrene resin composition (denoted as W4) was measured, and the content (mass %) of the rubbery polymer in the styrene resin (A) or styrene resin composition was calculated from this value and the mass of the styrene resin (A) or styrene resin composition (denoted as W1) using the following formula. Content (mass%) of rubbery polymer in styrene resin (A) or styrene resin composition = W4 / W1 × 100 【0086】 (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%) = ( 14C plasticizer / 12 C plasticizer) / ( 14 C standard material / 12 C standard material)×100 In addition, oxalic acid (SRM4990) was used as the standard substance. The biomass carbon ratio in the styrene-based resin composition was calculated in the same manner as described above. 【0087】 (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 【0088】 (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"). 【0089】 (10) Nominal strain at tensile fracture The styrene-based resin compositions obtained in the examples and comparative examples were used to prepare injection-molded pieces at 220°C according to JIS K 7152, and the tensile fracture strain was measured according to JIS K 7161. 【0090】 (11) Minimum temperature at which 2mm thick plate can be formed The styrene-based resin compositions obtained in the examples and comparative examples were used to mold a 2 mm plate using an injection molding machine, EC60N, manufactured by Toshiba Machine Co., Ltd., at a mold temperature of 45°C and an injection pressure of 40 MPa. The lowest temperature at which a molded product could be obtained without short shots was measured. The lower the minimum moldable temperature, the less likely the molded product is to yellow. Furthermore, lower temperatures reduce the release of volatile components from the resin, thus minimizing mold contamination. 【0091】 (12) Number of times mold contamination occurs After continuously molding 2 mm thick plates at the minimum moldable temperature indicated in (11) using the styrene-based resin compositions obtained in the examples and comparative examples, mold contamination was evaluated using the number of shots until deposits were observed on the mold as an indicator. If the number of shots until deposits were observed on the mold was less than 100, the frequency of mold cleaning would increase and productivity would decrease, so a number of 100 or more was considered acceptable. 【0092】 (13) Heat shrinkage rate The styrene-based resin compositions obtained in the examples and comparative examples were used to create dumbbell test specimens in accordance with ISO 3167 using an injection molding machine, EC60N, manufactured by Toshiba Machine Co., Ltd., at the minimum moldable temperature indicated in (11). The shrinkage rate after being left at 50°C for 1 hour was measured. The shrinkage rate was defined as (shrinkage rate) = (L1 - L2) / L1, where L1 is the length of the dumbbell test specimen after conditioning at 23°C for 12 hours or more, and L2 is the length of the dumbbell test specimen after conditioning at 50°C for 30 minutes. A shrinkage rate of 0.1% or less was considered acceptable. 【0093】 (14)ΔYI after staying in the molding machine for 30 minutes The difference between the YI value of molded products formed after the styrene-based resin compositions obtained in the examples and comparative examples were left in the molding machine cylinder for 30 minutes at the minimum moldable temperature indicated in (11), and the YI value of molded products formed without leaving them in the cylinder was measured. 【0094】 (14) Minimum temperature at which sheet molding is possible Using a 25mmφ single-screw sheet extruder manufactured by Soken Co., Ltd., the minimum molding temperature at which a 0.3mm thick sheet could be formed without torque overload or vent-up in the screw section was measured when producing a 0.3mm thick sheet at a screw rotation speed of 80 rpm. The lower the minimum moldable temperature, the less deposit (stain) forms on the molded sheet, resulting in a superior sheet appearance. 【0095】 (15) Sheet tensile fracture nominal strain The tensile fracture nominal strain of the extruded sheets prepared in Examples 1-11 and Comparative Examples 1-4 was measured. Specifically, a JIS K6251-3 dumbbell was punched out from the extrusion (MD) 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. 【0096】 (16) Evaluation of the appearance of the seat (number of stains) During the production 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. 【0097】 "2. Ingredients" The materials used in the examples and comparative examples are as follows. [Styrene resin (A)] As the styrene resin (A), a rubber-modified styrene resin (1) obtained by the following manufacturing method was used. (Method for producing rubber-modified styrene resin (1)) A polymerization solution prepared by mixing and dissolving 84.8% by mass of styrene, 8.0% by mass of ethylbenzene, 7.0% by mass of polybutadiene rubber (BR15HB, manufactured by UBE Elastomer Co., Ltd.), and 0.2% of liquid paraffin product name "PS350S" (manufactured by Sanko Chemical Industry Co., Ltd.) was continuously charged at a rate of 3.24 liters / hr into a 6.2-liter laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones, and the temperature was adjusted to 123°C / 128°C / 132°C. The stirrer speed was set to 70 revolutions per minute. The reaction rate at the reactor outlet was 33%. Next, the reaction mixture was sent to a 6.2-liter laminar flow reactor-2, which was equipped with a stirrer connected in series with laminar flow reactor-1 and had three temperature control zones. The stirrer's rotation speed was set to 40 revolutions per minute, and the temperature was set to 141°C / 146°C / 151°C. Subsequently, the reaction mixture was sent to a 6.2-liter laminar flow reactor-3, which was equipped with a stirrer and had three temperature control zones. The stirrer's rotation speed was set to 10 revolutions per minute, and the temperature was set to 156°C / 160°C / 165°C. The polymer solution continuously discharged from the polymerization reactor (laminar flow reactor-3) was heated to 230°C and extruded in a vacuum vented extruder under reduced pressure of 0.8 kPa to produce pelletized rubber-modified styrene resin (1). As the styrene resin (A), a rubber-modified styrene resin (2) obtained by the following manufacturing method was used. (Method for producing rubber-modified styrene resin (2)) A polymerization solution prepared by mixing and dissolving 88.7% by mass of styrene, 6.5% by mass of ethylbenzene, and 4.8% by mass of polybutadiene rubber (Diene 55, manufactured by Asahi Kasei Chemicals) was continuously charged at a rate of 3.24 liters / hr into a 6.2-liter laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones, and the temperature was adjusted to 125°C / 130°C / 135°C. The stirrer speed was set to 70 revolutions per minute. The reaction rate at the reactor outlet was 30%. Next, the reaction mixture was sent to a 6.2-liter laminar flow reactor-2, which was equipped with a stirrer connected in series with laminar flow reactor-1 and had three temperature control zones. The stirrer's rotation speed was set to 40 revolutions per minute, and the temperature was set to 139°C / 142°C / 145°C. Next, the reaction mixture was sent to a 6.2-liter laminar flow reactor-3, which was equipped with a stirrer and had three temperature control zones. The stirrer's rotation speed was set to 10 revolutions per minute, and the temperature was set to 144°C / 151°C / 152°C. The polymer solution continuously discharged from the polymerization reactor (laminar flow reactor-3) was heated to 230°C and extruded in a vacuum vented extruder under reduced pressure of 0.8 kPa to produce pelletized rubber-modified styrene resin (2). (Butadiene rubber) · Polybutadiene rubber (Diene 55 manufactured by Asahi Kasei Chemicals Corporation), Polybutadiene rubber UBEPOL BR (BR15HB manufactured by UBE Elastomers Corporation) [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 dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 9.0 ((cal / cm 3 ) 1 / 2 ), Epoxidation rate: 5 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 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 Twisted 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 dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 8.2 ((cal / cm 3 ) 1 / 2 )) 【0098】 [Others] (Liquid paraffin) · Liquid paraffin, product name "PS350S" (manufactured by Sanko Chemical Industries Co., 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 【0099】 "3. Examples and Comparative Examples" [Examples 1 - 6, Comparative Examples 1 - 2] (Method for producing styrenic resin compositions (PS - 1) - (PS - 6), (PS - 12), (PS - 13)) The styrenic resin composition (PS - 1) was prepared by melt - kneading the rubber - modified styrenic resin (1) using a twin - screw kneading extruder (TEM - 26SS - 12 manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 220 °C, and then adding palm oil in a liquid state so that the rubber - modified styrenic resin (1) contained 17% by mass of palm oil, followed by melt - kneading. The cylinder temperature after adding palm oil in a liquid state was set to 190 °C. The styrenic resin compositions (PS - 2) - (PS - 6), (PS - 12), (PS - 13) were also produced in the same manner as the styrenic resin composition (PS - 1), except for the addition amount of palm oil. After melt - kneading the rubber - modified styrenic resin (1) at 220 °C, palm oil was added in a liquid state. The addition amount of palm oil, the cylinder temperature after adding in a liquid state, and the production feasibility (feasible 〇, not feasible ×) are shown in Table 2. For the obtained styrenic resin compositions (PS - 1) - (PS - 6), (PS - 12), (PS - 13), the physical properties of the styrenic resin compositions shown in Table 3 were measured by the methods described in the column of "1. Measurement and Evaluation Methods" above. 【0100】 [Example 7] (Method for producing styrenic resin composition (PS - 7)) The styrene-based resin composition (PS-7) was produced by melt-kneading a rubber-modified styrene-based resin (2) using a twin-screw compounding extruder (Toshiba Machine Co., Ltd. TEM-26SS-12) at a cylinder temperature of 220°C, and then adding palm oil in liquid form to the rubber-modified styrene-based resin (2) so that it contained 30% by mass, followed by melt-kneading. The cylinder temperature after adding the palm oil was set to 170°C. The feasibility of production (production possible ○, production impossible ×) is shown in Table 2. The physical properties of the obtained styrene-based resin composition (PS-7) were measured using the method described in the "1. Measurement and Evaluation Methods" section above, as shown in Table 3. 【0101】 [Example 8] (Method for producing styrene-based resin composition (PS-8)) The styrene-based resin composition (PS-8) was produced by melt-kneading a rubber-modified styrene-based resin (1) using a twin-screw compounding extruder (Toshiba Machine Co., Ltd. TEM-26SS-12) at a cylinder temperature of 220°C, and then adding soybean oil in liquid form to the rubber-modified styrene-based resin (1) so that it contained 30% by mass, followed by melt-kneading. The cylinder temperature after adding the soybean oil was set to 170°C. The feasibility of production (production possible ○, production impossible ×) is shown in Table 2. The physical properties of the obtained styrene-based resin composition (PS-8) were measured using the method described in the "1. Measurement and Evaluation Methods" section above, as shown in Table 3. 【0102】 [Example 9, Comparative Example 3] (Method for producing styrene-based resin compositions (PS-9) and (PS-14)) Styrene resin composition (PS-9) was produced by melt-kneading rubber-modified styrene resin (1) using a twin-screw extruder (TEM-26SS-12, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 220°C, and then adding epoxidized soybean oil in liquid form to the rubber-modified styrene resin (1) so that 16% by mass of epoxidized soybean oil was contained in the rubber-modified styrene resin (1), and then melt-kneading. The cylinder temperature after adding the epoxidized soybean oil was set to 190°C. Styrene resin composition (PS-14) was produced in the same manner as styrene resin composition (PS-9), except for the amount of epoxidized soybean oil added, by melt-kneading rubber-modified styrene resin (1) at 220°C and then adding epoxidized soybean oil in liquid form. The amount of epoxidized soybean oil added, the cylinder temperature after addition, and the feasibility of production (production possible ○, production impossible ×) are shown in Table 2. The physical properties of the obtained styrene-based resin compositions (PS-9) and (PS-14) were measured using the method described in the "1. Measurement and Evaluation Methods" section above. 【0103】 [Example 10] The styrene-based resin composition (PS-10) was produced by melt-kneading a rubber-modified styrene-based resin (1) using a twin-screw extruder (Toshiba Machine Co., Ltd. TEM-26SS-12) at a cylinder temperature of 220°C, and then adding palm oil and liquid paraffin in liquid form to the rubber-modified styrene-based resin (1) so that it contained 16% by mass of palm oil and 4% by mass of liquid paraffin, and then melt-kneading. The cylinder temperature after adding the palm oil was set to 185°C. The feasibility of production (production possible ○, production impossible ×) is shown in Table 2. The physical properties of the obtained styrene-based resin composition (PS-10) were measured using the method described in the "1. Measurement and Evaluation Methods" section above, as shown in Table 3. 【0104】 [Example 11] The styrene-based resin composition (PS-11) was produced by melt-kneading a rubber-modified styrene-based resin (1) using a twin-screw compounding extruder (TEM-26SS-12, manufactured by Toshiba Machine Co., Ltd.) at a cylinder temperature of 220°C. Then, palm oil and liquid paraffin were added to the rubber-modified styrene-based resin (1) so that the composition contained 12% by mass of palm oil and 5% by mass of liquid paraffin, and the mixture was melt-kneaded again. The cylinder temperature after the addition of palm oil was set to 190°C. The feasibility of production (production possible ○, production impossible ×) is shown in Table 2. The physical properties of the obtained styrene-based resin composition (PS-11) were measured using the methods described in the "1. Measurement and Evaluation Methods" section above, as shown in Table 3. 【0105】 [Comparative Example 4] (Method for producing styrene-based resin composition (PS-15)) The styrene-based resin composition (PS-15) was manufactured by melt-mixing 80% by mass of rubber-modified styrene-based resin (1) and 20% by mass of polylactic acid using a twin-screw extruder (Toshiba Machine Co., Ltd. TEM-26SS-12) at a cylinder temperature of 220°C. The feasibility of production (production possible ○, production impossible ×) is shown in Table 2. The physical properties of the obtained styrene-based resin composition (PS-15) were measured using the methods described in the "1. Measurement and Evaluation Methods" section above, as shown in Table 3. 【0106】 [Comparative Example 5] (Method for producing styrene-based resin composition (PS-16)) The styrene-based resin composition (PS-16) was manufactured by melt-kneading a rubber-modified styrene-based resin (1) using a twin-screw extruder (Toshiba Machine Co., Ltd. TEM-26SS-12) at a cylinder temperature of 220°C, and then adding liquid paraffin to the rubber-modified styrene-based resin (1) so that it contained 17% by mass of liquid paraffin, followed by melt-kneading. However, due to poor compatibility between the styrene-based resin and the liquid paraffin, significant bleed-out was observed, making production impossible. The cylinder temperature after adding the liquid paraffin was set to 190°C. 【0107】 [Table 2] 【0108】 Table 3

Claims

[Claim 1] 30 to 84.9% by mass of styrene-based resin (A) containing styrene monomer units, It contains a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, in an amount of more than 15% by mass and 70% by mass or less. The material contains the styrene resin (A), the biomass plasticizer (B), and additive components, and the total content of the styrene resin (A), the biomass plasticizer (B), and the additive components is 99 to 100% by mass. The aforementioned additive component is one or more selected from the group consisting of mineral oil, mold release agent, flame retardant, dispersant, antioxidant, weathering agent, antistatic agent, antiblocking agent, colorant, blooming agent, surface treatment agent, antibacterial agent, and eye discharge inhibitor. The styrene-based resin (A) is one of the following: polystyrene, which is a homopolymer obtained by polymerizing the styrene-based monomers; a rubber-modified styrene-based resin containing a styrene-based polymer (a-1) and rubbery polymer particles (a-2) as a polymer matrix phase; or a styrene-based copolymer resin containing the styrene-based monomer units and one or more monomer units selected from the group consisting of unsaturated carboxylic acid monomer units and unsaturated carboxylic acid ester monomer units. A styrene-based resin composition wherein the SP value of the biomass plasticizer is 7.4 to 8.8 ((cal / cm³) 1 / 2). [Claim 2] The styrene-based resin composition according to claim 1, wherein the Vicat softening temperature is 65°C or lower. [Claim 3] The styrene-based resin composition according to claim 1 or 2, wherein the melt viscosity measured at a resin temperature of 180°C and a shear rate of 1000 / sec is 140 (Pa·sec) or less. [Claim 4] The styrene-based resin composition according to claim 1 or 2, wherein the melt viscosity measured at a resin temperature of 180°C and a shear rate of 40 / sec is 1200 (Pa·sec) or less. [Claim 5] The styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase composed of a styrene polymer (a-1) containing the styrene monomer units and rubbery polymer particles (a-2). The absolute value of the difference between the SP value of the styrene polymer (a-1) 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 6] The SP value of the biomass plasticizer (B) is 7.8 to 8.8 (cal / cm³). ３ ) １／２ The styrene-based resin composition according to any one of claims 1 or 2. [Claim 7] The styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase composed of a styrene polymer (a-1) containing the styrene monomer units and rubbery polymer particles (a-2). The styrene-based resin composition according to claim 1 or 2, wherein the content of the rubbery polymer particles (a-2) is 2 to 40% by mass relative to the total amount (100% by mass) of the styrene-based resin (A), and the average particle diameter of the rubbery polymer particles (a-2) is 0.3 to 7.0 μm. [Claim 8] The styrene resin composition according to claim 1 or 2, wherein the content of the styrene monomer units contained in the styrene resin (A) is 50% by mass or more with respect to the total amount (100% by mass) of the styrene resin (A). [Claim 9] An injection-molded article obtained by injection molding a styrene-based resin composition according to any one of claims 1 or 2. [Claim 10] A sheet comprising the styrene-based resin composition according to any one of claims 1 or 2.

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