Styrenic resin composition and molded body thereof

Abstract

The present disclosure aims to provide a styrene-based resin composition and a molded body thereof, which reduce environmental load by using a biomass raw material and are excellent in mechanical strength. The present disclosure is a styrene-based resin composition, wherein the styrene-based resin composition contains 82.5 to 99.9 mass% of a styrene-based resin (A) containing a styrene-based monomer unit and 0.1 to 15 mass% of a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more.

Description

Technical Field

[0001] The present invention relates to styrene-based resin compositions and molded articles comprising the styrene-based resin compositions. Background Technology

[0002] Styrene-based resins are used in various applications, including grocery goods and household appliances, due to their moldability and mechanical strength. Furthermore, from the perspective of achieving a low-carbon and circular society, biomass materials are attracting attention, and composite materials of styrene-based resins and naturally derived biomass materials are being researched.

[0003] For example, Patent Document 1 discloses a styrene-based resin composition comprising rubber-modified polystyrene, polylactic acid, and a thermoplastic elastomer containing styrene monomer units. Patent Document 2 discloses a method for manufacturing heat-resistant resin foam sheets by adding epoxidized soybean oil and / or linseed oil and higher fatty acid metal salts to a resin composition whose main component is a styrene-methacrylic acid copolymer. Furthermore, Patent Document 3 discloses a styrene-based resin composition containing plant-derived polyethylene and a compatibilizer.

[0004] In the field of styrene resins, in recent years, for injection molding applications, there has been a demand for improved resin flowability and shorter molding cycle times to increase productivity. Furthermore, by improving resin flowability, residual stress and residual strain generated in the molded body during injection molding cooling are reduced. It is known that reduced residual strain leads to increased mechanical strength of the molded body; therefore, by improving resin flowability, an increase in mechanical strength can also be expected.

[0005] Typically, large amounts of liquid paraffin are used as plasticizers to improve resin flowability. However, this results in the volatilization of low-boiling-point components during molding, causing fouling on the mold or molded body. For example, Patent Document 4 discloses a method for manufacturing a rubber-modified styrene resin that achieves an excellent balance between surface impact, rigidity, and flowability. Furthermore, methods for adjusting the resin's molecular weight and molecular weight distribution can be devised to improve resin flowability while preventing mold contamination during molding. For example, Patent Document 5 discloses a method for manufacturing a styrene resin with high flowability and minimal mold residue by adjusting the molecular weight and molecular weight distribution without adding liquid paraffin.

[0006] Styrene-based resins, due to their transparency and excellent rigidity, have been widely used in recent years for biaxially stretched sheets and food containers obtained through secondary processing of biaxially stretched sheets. For biaxially stretched sheets using styrene-based resins, low flowability leads to reduced productivity and uneven sheet thickness. Conversely, high flowability of styrene-based resins can cause sagging during sheet forming, resulting in poor sheet formability. Therefore, styrene-based resins used in biaxially stretched sheet applications need to possess flowability suitable for biaxially stretched sheet forming.

[0007] To control the flowability of styrene-based resins in this way, there are methods for adding liquid paraffin. For example, Patent Document 6 discloses an example of adding liquid paraffin to a highly branched styrene-based resin.

[0008] As a technique for controlling resin flowability using other methods, there are methods for adjusting the molecular weight and molecular weight distribution of the resin. For example, Patent Document 7 discloses a styrene-based resin composition that has flowability suitable for biaxial stretching sheets by adjusting the molecular weight and molecular weight distribution of the styrene-methacrylic acid copolymer.

[0009] Furthermore, in the processing or molding of hollow containers using styrene-based resins, injection blow molding, which is easy to mold into deep containers and has high productivity, is widely used. Moreover, injection blow molding allows for thickening only the opening of the hollow container, making it suitable for manufacturing hollow containers with heat-sealed openings. In recent years, in the field of injection blow molding, there has been a demand for molding materials with excellent strength that maintain a certain level of strength even when the container walls are thinned. However, due to thinning, the impact strength at the opening decreases, leading to cracking problems during empty transport in the molding plant. Furthermore, due to thinning, the flexural strength of the container decreases, causing the container to deform under load when filled with beverages and transported. Therefore, a molding material with an excellent balance between opening impact strength and flexural strength is required. In addition, from the viewpoint of improving the productivity of container molding, it is also necessary to reduce mold contamination. As examples of injection blow molding technologies involving such processes, those described in Patent Documents 8-10 can be cited.

[0010] Patent Document 8 discloses a styrene-based resin composition comprising rubber-modified styrene-based resin and polylactic acid, suitable for injection blow molding. Next, Patent Document 9 discloses a technique for producing molded beverage containers with excellent flexural strength and mouth impact strength. Furthermore, Patent Document 10 discloses a rubber-modified styrene-based resin composition for highly branched injection blow molding, and mentions techniques for reducing the total amount of residual styrene monomer and residual polymerization solvent, and reducing mold contamination.

[0011] Existing technical documents

[0012] Patent documents

[0013] Patent Document 1: Japanese Patent Application Publication No. 2016-199652

[0014] Patent Document 2: Japanese Patent Application Publication No. 2005-239914

[0015] Patent Document 3: Japanese Patent Application Publication No. 2020-193274

[0016] Patent Document 4: Japanese Patent Application Publication No. 10-251355

[0017] Patent Document 5: Japanese Patent Application Publication No. 2017-222770

[0018] Patent Document 6: Japanese Patent Application Publication No. 2013-100430

[0019] Patent Document 7: International Publication No. 2017 / 122775

[0020] Patent Document 8: International Publication No. 2021 / 132692

[0021] Patent Document 9: Japanese Patent Application Publication No. 10-76565

[0022] Patent Document 10: Japanese Patent Application Publication No. 2013-100435 Summary of the Invention

[0023] The problem that the invention aims to solve

[0024] The technology in Patent Document 1 described above investigated polymer alloys of styrene-based resins and polylactic acid (PLA), a biodegradable polymer derived from plants, which exhibits relatively high melting point, toughness, and transparency. However, due to the very low compatibility and poor flowability of PLA in styrene-based resins, there are challenges in designing products that meet market requirements for mechanical properties such as impact resistance and elasticity. Furthermore, the incompatibility between PLA and styrene-based resins also presents difficulties in recycling the scrap material.

[0025] Next, Patent Document 2 described a cross-linked styrene-(meth)acrylic acid copolymer resin obtained by reacting epoxidized soybean oil, a component with a cross-linked structure, with a styrene-(meth)acrylic acid copolymer. The method of manufacturing a free-bubble styrene resin foam by controlling the flowability or viscoelasticity of the melt state through the introduction of a cross-linking agent is a common foam forming method. However, since compatibility varies significantly depending on the type of styrene resin and the type of cross-linking agent used, it is difficult to manufacture molded articles that possess both elasticity and mechanical strength. Furthermore, in systems where (meth)acrylic acid polymers and modified vegetable oils such as epoxidized soybean oil coexist, the modified groups react with (meth)acrylic acid and gel, making it difficult to control the cross-linking density and reducing moldability. In addition, gelation may also impair the appearance of the molded article.

[0026] In addition, the technology research in the aforementioned Patent Document 3 studied polystyrene resins containing plant-derived polyethylene and compatibilizers. However, due to the low compatibility between polystyrene and polyethylene, the mechanical strength is low, and even with the use of compatibilizers, it is difficult to maintain high transparency.

[0027] Furthermore, the technology in Patent Document 4 described above involved a method for manufacturing a rubber-modified styrene resin that achieves an excellent balance between impact resistance, rigidity, and flowability. However, due to the use of a large amount of liquid paraffin, low-boiling-point components volatilize during injection molding, resulting in an increase in the amount of volatile components during molding. This leads to new problems such as mold contamination or molded body contamination during molding.

[0028] Furthermore, the technology in Patent Document 5 investigated styrene-based resins with high fluidity and low molecular weight material adhesion to molds. However, due to the low molecular weight of the resin, it is difficult to design products without reducing the impact strength of simply supported beams or the rigidity of the molded body. Additionally, biomass raw materials, which have received attention in recent years for their environmental impact reduction, were not used.

[0029] Furthermore, the technology in Patent Document 6 described above was studied for highly branched styrene resin compositions with excellent biaxial stretching sheet formability and productivity. However, it was found that the addition of liquid paraffin led to exudation and the generation of volatile gases during molding, resulting in a deterioration in the sheet appearance.

[0030] Furthermore, in the technology of Patent Document 7 mentioned above, a styrene-based resin composition was studied, which controlled the flowability by adjusting the molecular weight of the styrene-methacrylic acid copolymer and exhibited excellent biaxial stretching sheet molding properties and productivity. However, since the molecular weight was relatively low in order to improve flowability, there were concerns about a reduction in mechanical strength. In addition, in Patent Documents 6 and 7 mentioned above, biomass feedstocks, which have received attention in recent years for the purpose of reducing environmental impact, were not used.

[0031] Furthermore, the technology in Patent Document 8 investigated polymer alloys between styrene-based resins and polylactic acid (PLA), a biodegradable polymer derived from plants, which has a relatively high melting point and toughness. However, due to the very low compatibility of PLA with styrene-based resins, it is difficult to design products that meet the mechanical properties such as impact resistance or elasticity required in the hollow container market. Additionally, the incompatibility between PLA and styrene-based resins also presents challenges in recycling hollow container scraps.

[0032] Patent Document 9 investigated a molded beverage container with excellent flexural strength and mouth impact strength, both considered mechanical strengths. However, it was found that the use of a large amount of liquid paraffin increased the amount of volatile components generated during molding, resulting in worse mold contamination. Patent Document 10 investigated a molding material with excellent injection blow molding properties and low levels of residual styrene monomer and polymer solvent. However, due to the use of a large amount of white oil, it was deemed insufficient in reducing mold contamination. Furthermore, neither Patent Document 9 nor Patent Document 10 used biomass raw materials intended to reduce environmental impact.

[0033] Therefore, none of the technologies in the aforementioned patent documents 1 to 10 have studied plasticizers that use biomass raw materials while reducing environmental impact and maintaining high mechanical strength.

[0034] Therefore, the purpose of this disclosure is to provide a styrene-based resin composition and its molded articles that use biomass raw materials to reduce environmental impact and maintain high mechanical strength during molding.

[0035] Another objective of this disclosure is to provide styrene-based resin compositions and molded articles thereof that reduce environmental impact through the use of biomass raw materials, result in less mold contamination during injection molding, and possess high mechanical strength and excellent molding cycle.

[0036] Another objective of this disclosure is to provide a highly transparent styrene resin composition and its molded articles that reduce environmental impact by using biomass raw materials, result in less mold contamination during injection molding, and have high fluidity and high mechanical strength.

[0037] Another aspect of this disclosure aims to provide a styrene-based resin composition and its molded articles that reduce environmental impact by using biomass raw materials, maintain high mechanical strength, and have excellent formability, sheet appearance, and transparency when molded into biaxially stretched sheets.

[0038] Another aspect of this disclosure aims to provide a rubber-modified styrene resin composition suitable for injection blow molding, which reduces environmental impact through the use of biomass raw materials, exhibits excellent injection blow molding properties and minimal mold contamination during molding, and possesses high mouth impact strength and flexural strength.

[0039] means for solving problems

[0040] The inventors conducted in-depth research and repeated experiments to address the aforementioned problems. The results showed that a styrene resin composition obtained by mixing a styrene resin (A) and a biomass plasticizer (B) with a high-boiling-point biomass carbon ratio (pMC%) of 10% or more in a specific ratio can solve these problems, thus completing the present invention. In particular, when the biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more has low compatibility with the styrene resin (A), the biomass plasticizer (B) is difficult to disperse in the styrene resin (A) (e.g., the two separate), thus exhibiting a tendency to reduce mechanical strength. Therefore, regarding the compatibility of the biomass plasticizer (B) with the styrene resin (A), a solubility test was performed using the following turbidity evaluation experiment. The results showed that when the SP values ​​of the biomass plasticizer (B) and the styrene resin (A) are within a specific range, the biomass plasticizer (B) dissolves uniformly in the styrene resin (A), thereby obtaining excellent mechanical strength.

[0041] [Turbidity Evaluation Experiment]

[0042] Relative to 100 parts by weight of polystyrene resin (manufactured by PS Japan Co., Ltd., product name "685", equivalent to styrene resin (A)) or acrylonitrile styrene resin (manufactured by Asahi Kasei Corporation, product name "Stylac (registered trademark) 789", equivalent to styrene resin (A)), 5 or 10 parts by weight of each of the plasticizers shown in Table 1 or Table 2 below were added and compounded in a twin-screw extruder. A twin-screw extruder "TEM-26SS" (screw diameter 26 mm) manufactured by Nippon Steel Works Co., Ltd. was used. Melt extrusion was performed at a melt temperature of 220°C and an extrusion speed of 10 kg / h. The extruded filament was cooled and solidified in a cooling tank and then cut to obtain a granular resin composition.

[0043] Then, the total light transmittance of a 2mm thick board was measured according to JIS K7361-1. A total light transmittance of 85% or more was rated as transparent "○", a total light transmittance of 65% or more but less than 85% was rated as translucent "△", and a total light transmittance of less than 65% was rated as white and cloudy "×". The total light transmittance of the 2mm thick board was measured in the following manner.

[0044] Measurement of total transmittance

[0045] (I) Conditions for preparing the test piece

[0046] A sheet body was produced by injection molding the obtained styrene-based resin composition under the following conditions using a flat molding die.

[0047] Molding machine: EC60N manufactured by Toshiba Machine Co., Ltd.

[0048] Barrel temperature: 220℃

[0049] Injection pressure: 45 MPa, Injection time: 10 seconds

[0050] Cooling time: 15 seconds, mold temperature: 45℃

[0051] (II) Conditions for determining total transmittance

[0052] The total transmittance (%) of the test sheet prepared above was determined according to JIS K7361-1.

[0053] The turbidity evaluation results for the cases where each plasticizer was added to the above-mentioned polystyrene resin are shown in Table 1 below. On the other hand, the turbidity evaluation results for the cases where each plasticizer was added to acrylonitrile styrene resin are shown in Table 2 below.

[0054] [Table 1]

[0055]

[0056] [Table 2]

[0057]

[0058] The experimental results in Tables 1 and 2 confirm that when the difference in SP values ​​is greater than 2.5, the effect of the amount of plasticizer added decreases, and the plasticizer produces a white turbidity in styrene resins such as polystyrene and acrylonitrile styrene resins. Therefore, it is considered that at least an insoluble plasticizer in styrene resins requires a difference in SP value of 2.5 or more from the styrene resin. On the other hand, the experimental results in Tables 1 and 2 confirm that when the difference in SP value with styrene resins such as polystyrene and acrylonitrile styrene resins is approximately less than 1, the effect of the amount of plasticizer added decreases, and the plasticizer dissolves relatively stably in the aforementioned styrene resins.

[0059] As can be seen from the above, in this specification, plasticizers with a SP value difference of 2.5 or more from styrene-based resins will produce white turbidity regardless of the amount of plasticizer added. Therefore, plasticizers with a SP value difference of 2.5 or more are completely insoluble in styrene-based resins.

[0060] On the other hand, in systems using plasticizers with an SP value difference of 1.3 or greater and less than 2.5 from styrene-based resins, since the resin is not transparent, it is assumed that some insoluble components exist within it. Therefore, in this specification, plasticizers with an SP value difference of 1.3 or greater and less than 2.5 from styrene-based resins are partially insoluble in styrene-based resins.

[0061] The present invention is described below.

[0062] (1) This disclosure is a styrene resin composition, wherein the styrene resin composition contains: 82.5% to 99.9% by mass of a styrene resin (A) comprising styrene monomer units and 0.1% to 15% by mass of a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more.

[0063] (2) In this embodiment, a styrene resin composition containing 90% to 99.9% by mass of a styrene resin (A) containing styrene monomer units and 0.1% to 10% by mass of a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more is preferred.

[0064] (3) In this embodiment, preferably:

[0065] The aforementioned styrene resin (A) is a styrene polymer (a-3) containing the aforementioned styrene monomer units, or the aforementioned styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase and rubbery polymer particles (a-2), wherein the polymer matrix phase is composed of a styrene polymer (a-1) containing the aforementioned styrene monomer units, and

[0066] The absolute value of the difference between the SP value of the aforementioned styrene polymer (a-1) or the aforementioned styrene polymer (a-3) and the SP value of the aforementioned biomass plasticizer (B) is less than 2.5 (cal / cm). 3 ) 1 / 2 .

[0067] (4) In this embodiment, the SP value of the above-mentioned biomass plasticizer (B) is preferably 7.4 (cal / cm³). 3 ) 1 / 2 ~10.5 (cal / cm) 3 ) 1 / 2 .

[0068] (5) In this embodiment, preferably:

[0069] The aforementioned styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase composed of styrene polymers (a-1) and rubber-like polymer particles (a-2).

[0070] The content of the rubber-like polymer particles (a-2) is 3% to 36% by mass relative to the total amount (100% by mass) of the styrene resin (A) mentioned above, and the average particle size of the rubber-like polymer particles (a-2) is 0.3 μm to 7.0 μm.

[0071] (6) In this embodiment, preferably:

[0072] The aforementioned styrene resin (A) is a rubber-modified styrene resin containing a styrene polymer (a-1) comprising the aforementioned styrene monomer unit and rubber-like polymer particles (a-2) with an average particle size of 0.9 μm to 7.0 μm. The aforementioned styrene resin composition further contains a higher fatty acid compound (C), and relative to the total styrene resin composition (100% by mass), the content of the aforementioned rubber-like polymer particles (a-2) is 10% to 30% by mass, the content of the aforementioned biomass plasticizer (B) is 0.1% to 15% by mass, and the content of the aforementioned higher fatty acid compound (C) is 0.02% to 2.5% by mass.

[0073] (7) In this embodiment, preferably:

[0074] The content of the styrene monomer units contained in the styrene resin (A) is 50% by mass or more relative to the total amount (100% by mass) of the styrene resin (A).

[0075] (8) In this embodiment, preferably:

[0076] The styrene resin (A) mentioned above is a styrene polymer (a-3), and the total light transmittance of the 2mm plate of the styrene resin composition mentioned above is 70% or more.

[0077] (9) In this embodiment, preferably:

[0078] The content of the above-mentioned biomass plasticizer (B) is greater than or equal to 0.1% by mass and less than 3.0% by mass, and the Vicat softening temperature of the above-mentioned styrene resin composition is 90°C or higher.

[0079] (10) In this embodiment, preferably:

[0080] The composition also contains 0.1 to 0.5 parts by weight of a higher fatty acid compound, relative to 100 parts by weight of the above-mentioned styrene resin composition.

[0081] (11) This embodiment is an injection blow molded body obtained by injection blow molding the above-mentioned styrene resin composition.

[0082] (12) This embodiment is an injection molded body obtained by injection molding the above-mentioned styrene resin composition.

[0083] (13) This embodiment is a sheet containing the above-mentioned styrene resin composition.

[0084] Invention Effects

[0085] According to the present invention, a styrene-based resin composition and its molded articles using biomass raw materials are provided, which reduce environmental impact and maintain high mechanical strength by using biomass raw materials.

[0086] According to the present invention, a styrene-based resin composition and its molded articles are provided, which reduce environmental impact by using biomass raw materials, have less mold contamination during injection molding, and have high mechanical strength and excellent molding cycle.

[0087] According to the present invention, a styrene-based resin composition and its molded articles are provided that reduce environmental impact by using biomass raw materials, minimize mold contamination during injection molding, and have high fluidity and high mechanical strength.

[0088] According to the present invention, a styrene-based resin composition and its molded articles are provided that reduce environmental impact by using biomass raw materials, maintain high mechanical strength, and have excellent formability and sheet appearance when molded into biaxially stretched sheets, exhibiting high transparency.

[0089] According to the present invention, a styrene-based resin composition suitable for injection blow molding is provided, which reduces environmental impact by using biomass raw materials, has excellent injection blow molding properties, and exhibits high mouth impact strength and flexural strength during injection blow molding, with minimal mold contamination during the molding process. Detailed Implementation

[0090] Hereinafter, embodiments of the present invention (hereinafter referred to as "this embodiment") will be described in detail. However, the present invention is not limited to the following description and can be implemented in various modifications within the scope of its spirit.

[0091] [Styrene-based resin compositions]

[0092] The styrene resin composition of this embodiment contains 82.5% to 99.9% by mass of a styrene resin (A) comprising styrene monomer units and 0.1% to 15% by mass of a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more.

[0093] This provides styrene-based resin compositions that reduce environmental impact and have high mechanical strength during molding.

[0094] Depending on the intended use, the styrene-based resin composition can be further endowed with properties. For example, in one preferred embodiment of the styrene-based resin composition, where high mechanical strength is important, the styrene-based resin composition may contain rubber-like polymer particles (hereinafter referred to as rubber-like polymer particles (a-2)).

[0095] On the other hand, in cases where transparency is important, in another preferred embodiment of the styrene-based resin composition, the total light transmittance of the plate with a thickness of 2 mm can be 70% or more.

[0096] The following explanations are divided into two types: one containing rubber-like polymer particles (a-2) and the other having a total light transmittance of 70% or more for a 2mm thick plate.

[0097] "Methods involving rubber-like polymer particles (a-2)"

[0098] The preferred styrene resin composition disclosed herein contains 82.5% to 99.9% by mass of a styrene resin (A) comprising styrene monomer units and 0.1% to 15% by mass of a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more. The styrene resin (A) may be a rubber-modified styrene resin containing a polymer matrix phase and rubbery polymer particles (a-2), wherein the polymer matrix phase is composed of a styrene polymer (a-1) comprising the aforementioned styrene monomer units.

[0099] In other words, the styrene resin composition of this embodiment contains, relative to the total styrene resin composition (100% by mass), 82.5% to 99.9% by mass of rubber-modified styrene resin and 0.1% to 15% by mass of biomass plasticizer (B). The rubber-modified styrene resin may contain a polymer matrix phase and rubber-like polymer particles (a-2). The polymer matrix phase has a styrene polymer (a-1) containing styrene monomer units as a constituent component.

[0100] This enables the provision of excellent styrene-based resin compositions that offer reduced environmental impact and higher mechanical strength.

[0101] <Rubber-modified styrene resin>

[0102] The styrene-based resin composition in this embodiment may contain rubber-modified styrene-based resin. Furthermore, in this embodiment, the content of rubber-modified styrene-based resin relative to the total styrene-based resin composition (100% by mass) may be 82.5% to 99.9% by mass, preferably 82.5% to 99.88% by mass, more preferably 83% to 99% by mass, further preferably 84% to 98% by mass, even more preferably 85% to 97% by mass, even more preferably 86% to 97% by mass, even more preferably 88% to 97% by mass, and even more preferably 90% to 97% by mass. Alternatively, in another embodiment, the content of rubber-modified styrene-based resin relative to the total styrene-based resin composition (100% by mass) is 85.0% to 99.9% by mass, preferably 90.0% to 99.0% by mass, 91.0% to 98.3% by mass, and more preferably 92.0% to 97.3% by mass. By setting this content to 82.5% by mass or more, impact resistance can be improved. On the other hand, by setting this content to 99.9% by mass or less, rigidity and other properties can be improved.

[0103] In this embodiment, the rubber-modified styrene resin refers to a resin in which rubber-like polymer particles (a-2) are dispersed in a styrene polymer (a-1) containing styrene monomer units as the polymer matrix phase, and can be manufactured by polymerizing styrene monomers in the presence of rubber-like polymers.

[0104] -Polymer matrix phase-

[0105] 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. As the monomer units constituting the styrene polymer (a-1) of this embodiment, styrene monomer units and / or vinyl monomer units (i) capable of copolymerizing with the aforementioned styrene monomers are preferred. Therefore, the aforementioned styrene polymer (a-1) is preferably one or more selected from the group consisting of polystyrene and styrene copolymer resins. As described later, examples of such styrene-(meth)acrylate copolymers include, for instance.

[0106] It should be noted that "composition" means that the styrene polymer (a-1) accounts for 50% or more by mass of the total polymer matrix phase, preferably 70% or more by mass, and more preferably 90% or more by mass.

[0107] In the monomer units constituting the styrene polymer (a-1) of this embodiment, the content of styrene monomer units relative to the styrene polymer (a-1) as a whole 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. The content of styrene monomer units in the styrene polymer (a-1) and vinyl monomer units (i) other than styrene monomer units that can copolymerize with styrene monomers can each be determined by proton nuclear magnetic resonance (NMR) analysis. 1 The integral ratio of the spectrum measured by the H-NMR instrument is obtained.

[0108] In addition to styrene, other styrene monomers used in this embodiment may include, for example, α-methylstyrene, α-methyl-p-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and tert-butylstyrene, or styrene derivatives such as bromostyrene and indene. Styrene is particularly preferred. One or more of these styrene monomers may be used.

[0109] In this embodiment, the vinyl monomer (i) described above is preferably one or more selected from the group consisting of unsaturated carboxylic acid monomers and unsaturated carboxylic acid ester monomers, without particular limitation. 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 alone or in combination of two or more.

[0110] It should be noted that the term "(meth)acrylic acid" includes both acrylic acid and methacrylic acid.

[0111] --Polystyrene--

[0112] In this embodiment, polystyrene refers to a homopolymer obtained by polymerizing styrene monomers, and polystyrene that is generally available can be appropriately selected. Examples of styrene monomers constituting polystyrene, similar to those described above, include styrene, α-methylstyrene, α-methyl-p-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and tert-butylstyrene, or styrene derivatives such as bromostyrene and indene. From an industrial point of view, styrene is preferred. One or more of these styrene monomers can be used. Polystyrene may contain monomer units other than those described above without impairing the effects of the invention, but it is typically composed of styrene monomer units.

[0113] --Styrene-based copolymer resins--

[0114] 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.

[0115] In the styrene copolymer resin of the present invention, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is set to 100% by mass, the content of styrene monomer units is preferably 51% to 98% by mass, more preferably 54% to 96% by mass, more preferably 57% to 93% by mass, and even more preferably in the range of 60% to 90% by mass. By setting this content to 51% by mass or more, the refractive index of the styrene resin (A) can be increased. On the other hand, by setting this content to 98% by mass or less, the desired amount of unsaturated carboxylic acid ester monomer units can be present.

[0116] In another approach, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is set to 100% by mass, the preferred content range of styrene monomer units can be 69% to 98% by mass, 74% to 96% by mass, or 77% to 92% by mass.

[0117] Furthermore, in the styrene copolymer resin of the present invention, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is set to 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 in the range of 10% to 40% by mass. In another embodiment, when the total content of styrene monomer units and unsaturated carboxylic acid ester monomer units is set to 100% by mass, the preferred content range of unsaturated carboxylic acid ester monomer units can be 2% to 31% by mass, 4% to 26% by mass, or 8% to 23% by mass.

[0118] In this embodiment, the contents of styrene monomer units (e.g., styrene monomer units) and unsaturated carboxylic acid ester monomer units (e.g., methyl methacrylate monomer units) in the styrene copolymer resin can each be determined by proton nuclear magnetic resonance (NMR). 1 The integral ratio of the spectrum measured by the H-NMR instrument is obtained.

[0119] As a specific example of the styrene monomer constituting the styrene copolymer resin of this embodiment, it is the same as the styrene monomers described above, and therefore omitted.

[0120] There are no particular limitations on the unsaturated carboxylic acid ester monomers used to constitute the styrene-based copolymer resin of this embodiment, and examples include: methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, etc. As a (meth)acrylate monomer, methyl methacrylate is preferred from the viewpoint of minimizing the impact on heat resistance. These unsaturated carboxylic acid ester monomers can be used alone or in combination of two or more.

[0121] As the styrene-based copolymer resin of this embodiment, styrene-(meth)acrylate copolymer, styrene-(meth)acrylate ethyl acrylate copolymer, styrene-(meth)acrylate propyl acrylate copolymer, or styrene-(meth)acrylate butyl acrylate copolymer, or styrene-(meth)acrylate methyl acrylate-(meth)acrylate butyl acrylate copolymer are preferred.

[0122] 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 between mechanical strength and flowability can be obtained, and the inclusion of gelling agents is also less. Furthermore, in another embodiment of this invention, when mouth impact strength and flexural strength are important, 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. It should be noted that the weight-average molecular weight (Mw) is a value obtained by gel permeation chromatography and converted according to standard polystyrene.

[0123] The styrene resin (A) in this embodiment can be a mixture obtained by blending one or more of the above-mentioned rubber-modified styrene resins with one or more of the styrene copolymer resins. In this case, the mixing ratio of the rubber-modified styrene resin to the styrene copolymer resin can be appropriately changed according to the intended use. For example, in a system where the rubber-modified styrene resin is less than the styrene copolymer resin, it is preferable to contain 0.1% to 30% by mass of the rubber-modified styrene resin relative to the total amount (100% by mass) of the styrene resin (A). On the other hand, in a system where the rubber-modified styrene resin is more than the styrene copolymer resin, it is preferable to contain 70% to 99.9% by mass of the rubber-modified styrene resin relative to the total amount (100% by mass) of the styrene resin (A).

[0124] In this embodiment, the weight-average molecular weight (Mw) of the styrene polymer (a-1) constituting the polymer matrix phase is preferably 100,000 to 300,000, more preferably 110,000 to 270,000, and even more preferably 120,000 to 250,000. When the weight-average molecular weight (Mw) is 100,000 to 300,000, a resin with a better balance between mechanical strength and flowability can be obtained, and the inclusion of gelling agents is also less. It should be noted that the weight-average molecular weight (Mw) is a value obtained using gel permeation chromatography and converted to standard polystyrene.

[0125] In this embodiment, it is preferable that the styrene polymer (a-1) or the styrene resin composition of this embodiment does not substantially contain cyanide vinyl monomer units such as acrylonitrile monomer units and methacrylonitrile monomer units. Specifically, relative to the total amount of the styrene polymer (a-1) or the styrene resin composition of this embodiment, it is preferable that it contains 10% by mass or less of cyanide vinyl monomer units, more preferably 5% by mass or less of cyanide vinyl monomer units, and even more preferably 2% by mass or less of cyanide vinyl monomer units.

[0126] Relative to the total styrene-based resin composition (100% by mass), the content of the styrene-based polymer (a-1) in this embodiment is preferably 65% ​​to 99.88% by mass, more preferably 70% to 99% by mass, 72% to 98% by mass, even more preferably 74% to 97% by mass, and even more preferably 75% to 95% by mass. Alternatively, in another embodiment, the preferred content range of the styrene-based polymer (a-1) relative to the total styrene-based resin composition (100% by mass) may be 85% to 99.88% by mass, 87% to 99.5% by mass, 88% to 98% by mass, 89% to 97% by mass, or 90% to 96.5% by mass.

[0127] -Rubber-like polymer-

[0128] In the styrene resin composition of this embodiment, the rubber-like polymer particles (a-2) may be included in the styrene resin composition as part of the rubber-modified styrene resin, or the styrene polymer (a-1) may be further incorporated with rubber-like polymer particles (a-2) that are different from the rubber-like polymer particles (a-2) contained in the rubber-modified styrene resin and included in the styrene resin composition.

[0129] The rubber-modified styrene resin of this embodiment contains rubber-like polymer particles (a-2), for example, with styrene polymer (a-1) internally and / or with styrene polymer (a-1) grafted onto its external side. Furthermore, the rubber-like polymer particles (a-2) of this embodiment include not only core-shell structures composed of a styrene polymer (a-1) as a core and a rubber-like polymer as a shell enclosing the core, but also salami structures composed of multiple styrene polymers (a-1) as cores and rubber-like polymers as shells enclosing the multiple styrene polymers (a-1).

[0130] As the material for the rubbery polymer or rubbery polymer particles (a-2) in this embodiment, for example, polybutadiene, polybutadiene containing polystyrene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc., can be used, with polybutadiene or styrene-butadiene copolymer being preferred. As the polybutadiene, both high-cis polybutadiene with a high cis content and low-cis polybutadiene with a low cis content can be used. Furthermore, as the structure of the styrene-butadiene copolymer, both random structure and block structure can be used. One or more of these rubbery polymers can be used. Additionally, saturated rubber obtained by hydrogenating butadiene-based rubber can also be used.

[0131] 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).

[0132] In this embodiment, relative to the total amount (100% by mass) of the rubber-modified styrene resin, the content of the rubber-like polymer contained in the rubber-modified styrene resin (the content of the rubber-like polymer (e.g., the content of the conjugated diene polymer such as polybutadiene) itself, excluding the styrene polymer (a-1) contained within the rubber-like polymer particles (a-2)) is preferably 1.0% to 15% by mass, more preferably 1.2% to 12% by mass, even more preferably 1.5% to 10% by mass, even more preferably 2.0% to 10% by mass, and even more preferably 3% to 8% by mass. When the content of the rubber-like polymer is less than 1.0% by mass, the overall impact resistance of the styrene resin composition may decrease. Furthermore, when the content of the rubber-like polymer is greater than 15% by mass, the overall flowability of the styrene resin composition may decrease.

[0133] It should be noted that, in this disclosure, the content of rubbery polymer in the rubber-modified styrene resin is a value calculated using the method described in the Example 1 column.

[0134] In this embodiment, relative to the total styrene resin composition (100% by mass), the content of rubber-like polymer particles (a-2) contained in the rubber-modified styrene resin (including the content of the rubber-like polymer (e.g., conjugated diene polymers such as polybutadiene) itself and the content of styrene polymer (a-1) contained within the rubber-like polymer particles (a-2) is preferably 3% to 36% by mass, more preferably 4% to 30% by mass, even more preferably 5% to 28% by mass, even more preferably 6% to 25% by mass, even more preferably 6% to 20% by mass, and even more preferably 8% to 18% by mass.

[0135] From the perspective of emphasizing injection blow molding, the content of rubbery polymer particles (a-2) (including the content of the rubbery polymer (e.g., conjugated diene polymers such as polybutadiene) itself and the content of styrene polymer (a-1) contained within the rubbery polymer particles (a-2)) relative to the total styrene resin composition (100% by mass) is preferably 10% to 30% by mass, more preferably 11% to 28% by mass, even more preferably 12% to 27% by mass, even more preferably 12% to 26% by mass, and even more preferably 13% to 25% by mass.

[0136] In this embodiment, relative to 100% by mass of the rubber-modified styrene resin, the content of the rubber-like polymer contained in the rubber-modified styrene resin (the content of the rubber-like polymer (e.g., the content of the conjugated diene polymer such as polybutadiene) itself, excluding the styrene polymer (a-1) contained within the rubber-like polymer particles (a-2)) is preferably 1.0% to 15% by mass, more preferably 1.2% to 12% by mass, even more preferably 1.5% to 10% by mass, more preferably 2% to 10% by mass, and even more preferably 3% to 8% by mass. When the content of the rubber-like polymer is less than 1.0% by mass, the overall impact resistance of the styrene resin composition may decrease. Furthermore, when the content of the rubber-like polymer is greater than 15% by mass, the overall flowability of the styrene resin composition may decrease.

[0137] From the perspective of emphasizing injection blow molding, the content of rubbery polymers contained in the rubber-modified styrene resin (the content of the rubbery polymers themselves, such as polybutadiene and other conjugated diene polymers, excluding the styrene polymers (a-1) contained within the rubbery polymer particles (a-2)) is preferably 2.2% to 9.5% by mass, more preferably 2.4% to 9.0% by mass, even more preferably 2.5% to 8.5% by mass, even more preferably 2.6% to 8.0% by mass, even more preferably 2.7% to 7.5% by mass, even more preferably 2.8% to 7.0% by mass, and even more preferably 3.1% to 6.5% by mass, relative to the total amount of rubber-modified styrene resin (100% by mass).

[0138] It should be noted that, in this disclosure, the content of rubbery polymer in the rubber-modified styrene resin is a value calculated using the method described in the Example 1 column.

[0139] It should be noted that, in this disclosure, the content of rubbery polymer particles (a-2) contained in the rubber-modified styrene resin is a value calculated using the method described in the Example 1 column.

[0140] In this embodiment, the average particle size of the rubber-like polymer particles (a-2) contained in the rubber-modified styrene resin is preferably 0.3 μm to 7.0 μm, more preferably 0.4 μm to 5.0 μm, and even more preferably 0.5 μm to 3.5 μm. From the viewpoint of impact resistance, it is preferably 0.8 μm to 3.5 μm, and even more preferably 0.8 μm to 3.0 μm. Considering the balance between mouth impact strength and flexural strength, in this embodiment, the lower limit of the average particle size of the rubber-like polymer particles (a-2) contained in the rubber-modified styrene resin is preferably 0.9 μm, more preferably 1.0 μm, more preferably 1.1 μm, more preferably 1.2 μm, more preferably 1.3 μm, more preferably 1.4 μm, and even more preferably 1.5 μm. Furthermore, the upper limit of the average particle size of the rubber-like polymer particles (a-2) is preferably 7.0 μm, more preferably 6.5 μm, even more preferably 6.0 μm, even more preferably 5.5 μm, even more preferably 5.0 μm, and even more preferably 4.5 μm. Additionally, the preferred range of the average particle size of the rubber-like polymer particles (a-2) can be any combination of the aforementioned upper and lower limits of the average particle size.

[0141] It should be noted that, in this disclosure, the average particle size of the rubber-like polymer particles (a-2) contained in the rubber-modified styrene resin is a value calculated by the method described in the first section of the examples or by the following method.

[0142] Using a COULTER MULTISIZER III (trade name) manufactured by Beckman Coulter with a 30 μm diameter perforated tube, 0.05 g of rubber-modified styrene resin particles were added to approximately 5 ml of dimethylformamide and left to stand for approximately 2 to 5 minutes. The dissolved dimethylformamide content was then measured as an appropriate particle concentration, and the median particle size on a volume basis was taken as the average particle size. Furthermore, the method described above for determining the average particle size of the rubber-like polymer particles (a-2) can also be used to determine the average particle size of the rubber-like polymer particles (a-2) contained in the entire styrene resin composition.

[0143] In this embodiment, the specific viscosity (an indicator of the molecular weight of the styrene polymer (a-1) contained in the rubber-modified styrene resin) is preferably in the range of 0.50 dL / g to 0.85 dL / g, more preferably in the range of 0.55 dL / g to 0.80 dL / g. When the specific viscosity of the styrene polymer (a-1) is less than 0.50 dL / g, the impact strength decreases; when the specific viscosity is greater than 0.85 dL / g, the flowability decreases.

[0144] It should be noted that, in this disclosure, the specific viscosity of the styrene polymer (a-1) is the value measured in toluene solution at 30°C and a concentration of 0.5 g / dL.

[0145] In this embodiment, when the styrene resin (A) is a rubber-modified styrene resin (HIPS resin), polybutadiene and styrene-butadiene rubber are particularly preferred among these rubbery polymers, with polybutadiene being the most preferred.

[0146] - Manufacturing method of rubber-modified styrene resin-

[0147] In this embodiment, there are no particular limitations on the method for manufacturing rubber-modified styrene resins. It can be manufactured through bulk polymerization (or solution polymerization) in the presence of a rubber-like polymer, polymerizing styrene monomers, vinyl monomers (i) added as needed, and solvents added as needed; bulk-suspension polymerization, which transforms into suspension polymerization during the reaction; or emulsion graft polymerization, in the presence of a rubber-like polymer latex, polymerizing styrene monomers and vinyl monomers (i) added as needed. In bulk polymerization, it can be manufactured by continuously feeding a mixed solution of a rubber-like polymer, styrene monomers, vinyl monomers (i) added as needed, and organic solvents, organic peroxides, and / or chain transfer agents added as needed, into a polymerization apparatus consisting of a fully mixed reactor or a tank reactor connected in series with multiple tank reactors.

[0148] In this embodiment, there are no particular limitations on the polymerization method of the styrene polymer (a-1) that serves as the polymer matrix phase of the rubber-modified styrene resin. For example, bulk polymerization or solution polymerization can be appropriately employed as a free radical polymerization method. The polymerization method mainly includes a polymerization step that polymerizes the polymeric raw materials (monomer components) and a devolatilization step that removes unreacted monomers, polymerization solvents, and other volatile components from the polymerization product.

[0149] - Manufacturing method of styrene copolymer resin-

[0150] In this embodiment, there are no particular limitations on the polymerization method for styrene-based copolymer resins. For example, bulk polymerization or solution polymerization can be appropriately used as a free radical polymerization method. The polymerization method mainly includes a polymerization step that polymerizes the polymerizing raw materials (monomer components) and a devolatilization step that removes unreacted monomers, polymerization solvents, and other volatile components from the polymerization product.

[0151] Hereinafter, an example of a polymerization method for a styrene-based copolymer resin that can be used in this embodiment will be described.

[0152] When polymerizing the raw materials to obtain the styrene copolymer resin, the raw material composition typically contains a polymerization initiator and a chain transfer agent.

[0153] Examples of polymerization initiators used in the polymerization of styrene-based copolymers include: organic peroxides, such as ketal peroxides like 2,2-bis(tert-butylperoxy)butane, 1,1-bis(tert-butylperoxy)cyclohexane (Perhexa C), and n-butyl 4,4-bis(tert-butylperoxy)valerate; dialkyl peroxides like di-tert-butyl peroxide (Perbutyl D), tert-butylcumyl peroxide, and dicumyl peroxide; diacyl peroxides like acetyl peroxide and isobutyryl peroxide; dicarbonate peroxides like diisopropyl percarbonate; ester peroxides like tert-butyl peracetate; ketal peroxides like acetylacetone peroxide; and hydroperoxides like tert-butyl hydrogen peroxide. From the viewpoint of decomposition and polymerization rates, 1,1-bis(tert-butylperoxy)cyclohexane is preferred. The addition of 0.005% to 0.08% by mass of the polymerization initiator is preferred relative to the total amount of monomers.

[0154] Examples of chain transfer agents used in the polymerization of styrene-based copolymers include: thiols such as n-dodecyl mercaptan, tert-dodecyl mercaptan, and n-octyl mercaptan; linear dimers of α-methylstyrene, 1-phenyl-2-fluorene, terpinene, chloroform, terpenes, halogen compounds, and turpentine. There are no particular limitations on the amount of this chain transfer agent used; generally, it is preferred to add about 0.005% to about 0.3% by weight of the chain transfer agent relative to the monomer.

[0155] The aforementioned polymerization initiators and chain transfer agents can be used not only in the manufacture of styrene copolymer resins, but also in the manufacture of the aforementioned rubber-modified styrene resins.

[0156] As a polymerization method for styrene-based copolymer resins, solution polymerization using a polymerization solvent can be employed as needed. Examples of polymerization solvents include aromatic hydrocarbons such as ethylbenzene and dialkyl ketones such as methyl ethyl ketone. These solvents can be used individually or in combination of two or more. Other polymerization solvents, such as aliphatic hydrocarbons, can be further mixed into the aromatic hydrocarbons without reducing the solubility of the polymerized product. These polymerization solvents are preferably used in amounts not exceeding 25 parts by mass relative to 100 parts by mass of all monomers. When the amount of polymerization solvent exceeds 25 parts by mass relative to 100 parts by mass of all monomers, the polymerization rate decreases significantly, and the decrease in the mechanical strength of the resulting resin tends to increase. Adding the polymerization solvent in advance at a ratio of 5 to 20 parts by mass relative to 100 parts by mass of all monomers before polymerization facilitates homogenization of the quality and is also preferred for controlling the polymerization temperature.

[0157] In this embodiment, there are no particular limitations on the apparatus used in the polymerization process for obtaining styrene-based copolymer resins; it can be appropriately selected according to a general polymerization method for styrene-based resins. For example, in the case of bulk polymerization, a polymerization apparatus consisting of one or more fully mixed reactors connected together can be used. Furthermore, there are no particular limitations on the devolatilization process. For example, in the case of bulk polymerization, polymerization is carried out until the final unreacted monomer content is preferably 50% by mass or less, more preferably 40% by mass or less, and devolatilization is performed by known methods to remove volatile components such as unreacted monomers. More specifically, conventional devolatilization apparatus such as flash tanks, twin-screw devolatilizers, thin-film evaporators, and extruders can be used, with devolatilization apparatuses having a small retention area being preferred. It should be noted that the temperature of the devolatilization treatment is typically about 190°C to about 280°C, more preferably 190°C to 260°C. Additionally, the pressure of the devolatilization treatment is typically about 0.13 kPa to about 4.0 kPa, preferably 0.13 kPa to 3.0 kPa, more preferably 0.13 kPa to 2.0 kPa. As devolatilization methods, preferred methods include removing volatile components by reducing pressure under heating, and removing them by using an extruder designed for the purpose of removing volatile components.

[0158] "A method where the total light transmittance of a 2mm thick board is over 70%"

[0159] The preferred styrene resin composition of this disclosure contains a styrene resin (A) comprising styrene monomer units and a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, ranging from 0.1% to 15% by mass. The preferred styrene resin composition of this disclosure has a total light transmittance of 70% or more for a plate with a thickness of 2 mm.

[0160] In other words, when the total light transmittance of the plate with a thickness of 2 mm of the preferred styrene resin composition disclosed herein is 70% or more, the content of rubber-like polymer particles (a-2) in the styrene resin composition may be less than 3% by mass relative to the total amount (100% by mass) of the styrene resin (A) described above.

[0161] This allows for the suppression of diffuse reflection caused by rubbery polymer particles (a-2), thus imparting transparency.

[0162] Therefore, the styrene resin (A) in this embodiment is a styrene polymer (a-3) containing styrene monomer units.

[0163] <Styrene polymers (a-3)>

[0164] The styrene-based resin composition in this embodiment contains a styrene-based polymer (a-3) as styrene-based resin (A). Furthermore, in this embodiment, the content of the styrene-based polymer (a-3) relative to the total styrene-based resin composition (100% by mass) is preferably 85.0% to 99.9% by mass, more preferably 85.0% to 97.0% by mass, and even more preferably 90.0% to 97.0% by mass. From other viewpoints, 97.0% to 99.9% by mass is preferred, and more preferably 97.5% to 99.5% by mass.

[0165] In this embodiment, the monomer unit constituting the styrene polymer (a-3) must have a styrene monomer unit, and may have a vinyl monomer unit (ii) that can copolymerize with the styrene monomer as needed.

[0166] In the monomer units constituting the styrene polymer (a-3), the content of styrene monomer units 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. The content of the styrene monomers, i.e., the content of the styrene monomer units, can be determined using proton nuclear magnetic resonance (NMR)... 1 The integral ratio of the spectrum measured by the H-NMR instrument is obtained. Additionally, the integral ratio is calculated using... 1 When quantification is difficult with H-NMR, quantification can be achieved by Fourier transform infrared spectroscopy (FTIR).

[0167] In addition to styrene, other styrene monomers mentioned above may include, for example, α-methylstyrene, α-methyl-p-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and tert-butylstyrene or bromostyrene and indene, etc. Styrene is particularly preferred. One or more of these styrene monomers may be used.

[0168] In this embodiment, there are no particular limitations on the vinyl monomer (ii), and examples include methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, etc. These unsaturated carboxylic acid ester monomers can be used alone or in combination of two or more.

[0169] In this embodiment, polystyrene refers to a homopolymer obtained by polymerizing styrene monomers, and commonly available substances can be appropriately selected. Besides styrene, other styrene monomers constituting polystyrene include: α-methylstyrene, α-methyl-p-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and tert-butylstyrene or bromostyrene and indene, etc. From an industrial point of view, styrene is preferred. One or more of these styrene monomers can be used. It is not excluded that polystyrene may contain monomer units other than the above-mentioned styrene monomer units without impairing the effects of the present invention, but it is typically composed of styrene monomer units.

[0170] As a preferred embodiment of the styrene polymer (a-3), it is preferable to control the SP value of the biomass plasticizer (B) such that the ratio of the styrene polymer (a-3) to biomass carbon (pMC%) is 10% or more within a specified range. Therefore, for example, the type of monomer unit constituting the styrene polymer (a-3), the content of styrene monomers, or the content of vinyl monomers (ii) can be adjusted according to the SP value of the biomass plasticizer (a-3) used.

[0171] As a result, the biomass plasticizer (B) in the composition is easily and uniformly dispersed, thus further improving transparency and mechanical strength.

[0172] In this embodiment, the weight-average molecular weight (Mw) of the styrene polymer (a-3) is preferably 100,000 to 450,000, more preferably 120,000 to 420,000, and even more preferably 150,000 to 400,000. When the weight-average molecular weight (Mw) is 100,000 to 450,000, a resin with a better balance between mechanical strength and flowability can be obtained, and the inclusion of gelling agents is also less. It should be noted that the weight-average molecular weight (Mw) is a value obtained using gel permeation chromatography and converted to standard polypropylene.

[0173] In addition, relative to the total amount (100% by mass) of the styrene polymer (a-3), the styrene polymer (a-3) in this embodiment preferably contains less than 1.0% by mass of a rubbery polymer (e.g., polybutadiene, polybutadiene containing polystyrene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer) or structural units having a conjugated diene structure.

[0174] In the case where the total light transmittance of the styrene-based resin composition of this embodiment is 70% or more for a plate with a thickness of 2 mm (where transparency is of paramount importance), the content of the toluene-insoluble component (= rubber-like polymer particles (a-2)) in the styrene-based resin composition is preferably less than 3% by mass, more preferably less than 1% by mass. It should be noted that the content of the toluene-insoluble component is determined by the method described in the Example 1 section below.

[0175] In this embodiment, it is preferable that the styrene polymer (a-3) or the styrene resin composition of this embodiment does not substantially contain cyanide vinyl monomer units such as acrylonitrile monomer units and methacrylonitrile monomer units. Specifically, relative to the total amount of the styrene polymer (a-3), it is preferable to contain 10% by mass or less of cyanide vinyl monomer units, more preferably 5% by mass or less of cyanide vinyl monomer units, and even more preferably 2% by mass or less of cyanide vinyl monomer units.

[0176] In this embodiment, there are no particular limitations on the polymerization method for the styrene polymer (a-3). For example, the same method as that used for the styrene polymer (a-1) described above can be used, such as free radical polymerization, and bulk polymerization or solution polymerization can be appropriately employed. The polymerization method mainly includes a polymerization step that polymerizes the polymerizing raw materials (monomer components) and a devolatilization step that removes unreacted monomers, polymerization solvents, and other volatile components from the polymerization product.

[0177] Hereinafter, an example of a polymerization method for the styrene polymer (a-3) that can be used in this embodiment will be described.

[0178] When polymerizing the raw materials to obtain the styrene polymer (a-3), the raw material composition typically contains a polymerization initiator and a chain transfer agent.

[0179] Examples of polymerization initiators used in the polymerization of styrene-based polymers (a-3) include: organic peroxides, such as 1,1-bis(tert-butylperoxy)cyclohexane (Perhexa C), 2,2-bis(tert-butylperoxy)butane, 2,2-bis(4,4-di-tert-butylperoxycyclohexyl)propane (Pertetra A), and peroxyketals such as 4,4-bis(tert-butylperoxy)valerate; dialkyl peroxides such as di-tert-butyl peroxide, tert-butylcumyl peroxide, and dicumyl peroxide; diacyl peroxides such as acetyl peroxide and isobutyryl peroxide; dicarbonates such as diisopropyl peroxide; ester peroxides such as tert-butyl peracetate; ketone peroxides such as acetylacetone peroxide; and hydroperoxides such as tert-butyl hydrogen peroxide. From the viewpoint of decomposition and polymerization rates, 1,1-bis(tert-butylperoxy)cyclohexane is preferred. Relative to the total amount of monomers, it is preferable to add 0.005% to 0.08% by mass of polymerization initiator.

[0180] Examples of chain transfer agents used in the polymerization of styrene-based polymers (a-3) include: linear dimers of α-methylstyrene, thiols such as n-dodecyl mercaptan and tert-dodecyl mercaptan, 1-phenyl-2-fluorene, terpinene, chloroform, terpenes, halogen compounds, and turpentine oils such as terpinene. There are no particular limitations on the amount of this chain transfer agent used; generally, it is preferred to add about 0.005% to about 0.3% by weight of the chain transfer agent relative to the monomer.

[0181] As a polymerization method for styrene-based polymers (a-3), solution polymerization using a polymerization solvent can be employed as needed. Examples of polymerization solvents include aromatic hydrocarbons such as ethylbenzene and dialkyl ketones such as methyl ethyl ketone. These solvents can be used individually or in combination of two or more. Other polymerization solvents, such as aliphatic hydrocarbons, can be further mixed into the aromatic hydrocarbons without reducing the solubility of the polymerized product. These polymerization solvents are preferably used in amounts not exceeding 25 parts by mass relative to 100 parts by mass of all monomers. When the amount of polymerization solvent exceeds 25 parts by mass relative to 100 parts by mass of all monomers, the polymerization rate decreases significantly, and the decrease in the mechanical strength of the resulting resin tends to increase. Adding the polymerization solvent in advance at a ratio of 5 to 20 parts by mass relative to 100 parts by mass of all monomers before polymerization facilitates homogenization of quality and is also preferred for controlling the polymerization temperature.

[0182] In this embodiment, there are no particular limitations on the apparatus used in the polymerization process for obtaining the styrene polymer (a-3), and it can be appropriately selected according to the polymerization method of the styrene resin. For example, in the case of bulk polymerization, a polymerization apparatus consisting of one or more fully mixed reactors connected together can be used. Furthermore, there are no particular limitations on the devolatilization process. For example, in the case of bulk polymerization, polymerization is carried out until the final unreacted monomer content is preferably 50% by mass or less, more preferably 40% by mass or less, and devolatilization is performed by known methods to remove volatile components such as unreacted monomers. More specifically, conventional devolatilization apparatus such as flash tanks, twin-screw devolatilizers, thin-film evaporators, and extruders can be used, with devolatilization apparatus having a small retention area being preferred. It should be noted that the temperature of the devolatilization process is typically about 190°C to about 280°C, more preferably 190°C to 260°C. Additionally, the pressure of the devolatilization process is typically about 0.13 kPa to about 4.0 kPa, preferably 0.13 kPa to 3.0 kPa, more preferably 0.13 kPa to 2.0 kPa. As devolatilization methods, preferred methods include removing volatile components by reducing pressure under heating, and removing volatile components by using an extruder designed for the purpose of removing volatile components.

[0183] <Biomass plasticizer (B) (hereinafter also referred to as component (B))>

[0184] The styrene-based resin composition in this embodiment contains a biomass plasticizer (B). Furthermore, the biomass plasticizer (B) has a biomass carbon percentage (pMC%) of 10% or more. If the biomass carbon percentage (pMC%) is within the above range, the use of fossil fuels can be reduced, thus providing a styrene-based resin composition that can reduce environmental impact.

[0185] In one embodiment of this invention, 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.

[0186] In this embodiment, the content of biomass plasticizer (B) is 0.1% to 15% by mass relative to the total amount (100% by mass) of the styrene-based resin composition. The lower limit of the content of biomass plasticizer (B) is preferably 0.1% by mass or more, more preferably 1% by mass or more, more preferably 1.5% by mass or more, and even more preferably 2% by mass or more. The upper limit of the content of biomass plasticizer (B) is preferably 15% by mass or less, preferably 14% by mass or less, preferably 13% by mass or less, more preferably 12% by mass or less, preferably 11% by mass or less, more preferably 10% by mass or less, even more preferably 9% by mass or less, 8% by mass or less, even more preferably 7% by mass or less, and particularly preferably 6% by mass or less. In other methods, the preferred lower limit for the content of biomass plasticizer (B) is 0.3% by mass or more, 0.7% by mass or more, 0.9% by mass or more, 1.1% by mass or more, 1.2% by mass or more, 1.3% by mass or more, 1.4% by mass or more, 1.5% by mass or more, 1.7% by mass or more, 1.9% by mass or more, 2.3% by mass or more, 2.4% by mass or more, 2.5% by mass or more, 2.7% by mass or more, 2.9% by mass or more, 3.3% by mass or more, 3.4% by mass or more, and 3.5% by mass or more.

[0187] When the content of biomass plasticizer (B) is too high, the volatile components increase, leading to increased mold contamination. Furthermore, when the content of biomass plasticizer (B) exceeds 15%, a tendency for exudation occurs. On the other hand, when the content of biomass plasticizer (B) is too low, fluidity decreases, thus increasing molding temperature, resulting in longer cooling times and reduced productivity.

[0188] Especially when used in the case of transparent styrene-based resin compositions for sheets (for example, to ensure transparency, the total light transmittance of a 2mm thick sheet of styrene-based resin composition is 70% or more), from the viewpoint of emphasizing sheet appearance, the content of biomass plasticizer (B) relative to the overall styrene-based resin composition is greater than or equal to 0.1% by mass and less than 3.0% by mass, preferably 0.1% to 2.5% by mass, more preferably 0.2% to 2.2% by mass, even more preferably 0.3% to 2.0% by mass, and even more preferably 0.3% to 1.7% by mass. When the amount of biomass plasticizer (B) is 3% by mass or more, the Vicat softening temperature is less than 90°C, making it unsuitable for stretch sheet applications and food packaging applications. Furthermore, when the amount of biomass plasticizer is less than 0.1% by mass, the fluidity decreases, thus raising concerns about uneven thickness during molding. Additionally, the decrease in fluidity raises concerns about reduced productivity. Therefore, while emphasizing that the styrene-based resin composition of this embodiment maintains high mechanical strength and exhibits good formability, excellent sheet appearance, and excellent transparency when molded into biaxially stretched sheets, as an example of a preferred embodiment of the styrene-based resin composition, the styrene-based resin composition may contain a styrene polymer (a-3) and 0.1% to 3.0% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, the styrene-based resin composition has a Vicat softening temperature of 90°C or more, and the total light transmittance of a 2 mm thick sheet of the styrene-based resin composition is 70% or more.

[0189] On the other hand, when using a transparent styrene resin composition for injection molding (for example, to ensure transparency, the total light transmittance of a 2mm thick styrene resin composition is 70% or more), from the viewpoint of minimizing mold contamination, the content of biomass plasticizer (B) is preferably 3.0% to 15% by mass relative to the total amount (100% by mass) of the styrene resin composition. Furthermore, the upper limit of the biomass plasticizer (B) content is more preferably 15% by mass or less, more preferably 14% by mass or less, more preferably 13% by mass or less, further preferably 12% by mass or less, further preferably 11% by mass or less, further preferably 10% by mass or less, further preferably 9% by mass or less, and even more preferably 7% by mass or less. When the content of biomass plasticizer (B) is too high, the volatile components increase, and mold contamination increases. Additionally, when the content of biomass plasticizer (B) is greater than 15%, there is a tendency for exudation. On the other hand, when the content of biomass plasticizer (B) is too low, the fluidity decreases, thus making it easy to cause underfilling during injection molding, resulting in reduced injection moldability. Therefore, considering that the styrene-based resin composition of this embodiment exhibits low mold contamination during molding and displays high fluidity, high mechanical strength, and excellent transparency, as an example of a preferred embodiment of the styrene-based resin composition, the styrene-based resin composition may contain a styrene polymer (a-3) and 3.0% to 15% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, and the total light transmittance of a 2 mm thick plate of the styrene-based resin composition is 70% or more.

[0190] The biomass plasticizer (B) is preferably uniformly dispersed in the styrene-based resin composition. More specifically, for example, an external lubricant (e.g., a lubricant insoluble in the polymer melt) that does not form a monolayer of the biomass plasticizer (B) on the surface of the styrene-based resin composition is preferred. Methods for uniformly dispersing the biomass plasticizer (B) in the styrene-based resin composition include, for example, methods of compounding a rubber-modified styrene-based resin and the biomass plasticizer (B) in an extruder, and methods of including the biomass plasticizer (B) in the polymer raw material composition during polymerization.

[0191] The biomass carbon ratio (pMC%) in this specification refers to the carbon concentration (mass ratio) of the components derived from biomass, and more specifically, it is measured by radioactive carbon according to ASTM-D6866. 14 C) Determination method 14 The value of C content. This radioactive carbon ( 14 C) The determination method is as follows: utilizing fossil fuels that do not contain... 14C, and carbon derived from biomass (or organisms) absorbs carbon from the atmosphere during the growth period. 14 C, based on the carbon content in biomass materials (or organisms). 14 The C ratio is used to estimate the biomass carbon ratio (pMC%).

[0192] Therefore, by measuring the C content of all carbon atoms in the plasticizer of this embodiment... 14 The proportion of carbon derived from biomass can be calculated. In this invention, the method described in the Examples section below is used and the biomass carbon ratio (pMC%) is calculated using the following formula (1).

[0193] Equation (1):

[0194] Biomass carbon ratio (pMC%) = ( 14 C plasticizer / 12 C plasticizer) / ( 14 C standard reference / 12 (C standard reference) × 100

[0195] In addition, using oxalic acid (SRM4990) as a standard, the results were calculated by AMS. 14 C plasticizer / 12 C plasticizer) / ( 14 C standard reference / 12 (C standard reference).

[0196] 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 resin composition with a better balance between mechanical strength and flowability can be obtained, and the inclusion of gelling agents is also less. It should be noted that, as described in the Examples section below, the weight-average molecular weight (Mw) is a value obtained using gel permeation chromatography and converted to standard polystyrene.

[0197] In this embodiment, the biomass plasticizer (B) refers to a plasticizer that uses biomass material in part or all of the raw material, and specifically refers to a plasticizer with 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 in at least a part of the raw material and has a biomass carbon ratio (pMC%) of 10% or more. Preferably, it is a vegetable oil, a mixture of vegetable oil and mineral oil, or a polyester plasticizer. More preferably, it is a natural vegetable oil, a 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 and modified vegetable oil and mineral oil, or a polyester plasticizer.

[0198] It should be noted that the term "vegetable oil" in this instruction manual refers to a general term for oils derived from plants, including natural vegetable oils and modified vegetable oils.

[0199] In this embodiment, the biomass plasticizer (B) may be a modified vegetable oil. Modified vegetable oil refers to a compound obtained using vegetable oil as a raw material. More specifically, modified vegetable oil is a substance obtained by modifying a portion of a plant-derived hydrocarbon oil using functional groups; preferably, the vegetable oil is modified using epoxy, amino, or ester bonds. Such vegetable oil includes glycerol and fatty acid triesters, fatty acid monoesters obtained by adding a monohydric alcohol to the vegetable oil and undergoing transesterification, fatty acid monoesters obtained by esterification of fatty acids with a monohydric alcohol, and ethers derived from fatty acids.

[0200] In this embodiment, the modifying groups (functional groups such as epoxy, amino, or ester bonds) of the modified vegetable oil preferably do not substantially polymerize with other components (including styrene resin (A)) or the modified vegetable oil in the styrene resin composition. Furthermore, in this embodiment, the modification rate of the modified vegetable oil is preferably 1 mmol% to 50 mmol% per 1g of the modified vegetable oil.

[0201] As described in the examples described later, the modification rate of the above-mentioned modified vegetable oil is determined by... 1 Calculated using H-NMR determination method.

[0202] Specific examples of the aforementioned natural plant oils include: cottonseed oil, tung oil, shea butter, alfalfa oil, poppy seed oil, pumpkin oil, winter melon oil, mixed grain oil, barley oil, quinoa oil, rye oil, kukui oil, passion fruit oil, avocado oil, aloe vera oil, almond oil, peach kernel oil, soybean oil, cashew oil, peanut oil, avocado oil, baobab oil, borage oil, cauliflower oil, calendula oil, camellia oil, rapeseed oil, carrot oil, and red... Flower oil, flaxseed oil, rapeseed oil, cottonseed oil, coconut oil, pumpkin seed oil, wheat germ oil, jojoba oil, lily oil, macadamia nut oil, corn oil, meadowfoam seed oil, gardenia oil, hazelnut oil, almond 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.

[0203] In this embodiment, examples of modified vegetable oils include: oils obtained by hydrogenating the natural vegetable oils exemplified above (e.g., hydrogenated castor oil), oils obtained by epoxidizing the natural vegetable oils exemplified above (e.g., modified epoxidized oil), and oils obtained by amination of the natural vegetable oils exemplified above (e.g., modified amination oil). These modified epoxidized oils include oils obtained by ring-opening of epoxy functional groups, such as hydrogenated soybean oil, as well as oils obtained by direct hydroxylation beforehand, and cashew oil-based polyols.

[0204] Specific examples of the biomass plasticizer (B) in this embodiment include: palm oil, epoxidized soybean oil, epoxidized linseed oil, hardened castor oil, polyethylene oxide castor oil, polyethylene oxide hardened castor oil, oleic acid ester or laurate ester; examples include: "Polycizer W-1810-BIO" and "Epocizer" manufactured by DIC Corporation; "Newcizer 510R" and "Newcizer 512" manufactured by Nichiyu Corporation; "PioninD series" manufactured by Takemoto Oils & Fats Co., Ltd.; "multi-ace 20(S)" and "purified palm oil(S)" manufactured by Nissin Oils & Fats Co., Ltd.; and "hardened castor oil" manufactured by Ito Oils & Fats Co., Ltd.

[0205] In this embodiment, the viscosity of the vegetable oil (including natural vegetable oil and modified vegetable oil) is preferably below 1000 mPa·s at 25°C, more preferably 20 mPa·s to 1000 mPa·s, even more preferably 50 mPa·s to 1000 mPa·s, and even more preferably 100 mPa·s to 800 mPa·s.

[0206] The biomass plasticizer (B) in this embodiment can be a modified vegetable oil obtained by modification using epoxy, amino, or ester bonds. In this case, the modified groups (functional groups such as epoxy, amino, or ester bonds) in the biomass plasticizer (B) of this embodiment do not substantially polymerize with other components (including styrene resin (A)) or modified vegetable oil in the styrene resin composition.

[0207] The preferred melting point of the biomass plasticizer (B) in this embodiment is -30°C to 80°C, more preferably -25°C to 77°C, even more preferably -22°C to 74°C, even more preferably -18°C to 70°C, even more preferably -15°C to 67°C, even more preferably -10°C to 64°C, even more preferably -8°C to 61°C, even more preferably -5°C to 58°C, even more preferably -3°C to 55°C, and particularly preferably -1°C to 52°C. When the melting point of the biomass plasticizer (B) is greater than 80°C, it is difficult for the biomass plasticizer (B) to melt into the styrene resin (A), making addition or mixing difficult. On the other hand, when the melting point of the biomass plasticizer (B) is less than -30°C, compounds containing a large number of unsaturated bonds are required as the type of biomass plasticizer (B) that can be used, thus making it prone to oxidation and deterioration, and its physical properties are easily reduced. It should be noted that, generally speaking, since all the double bonds in natural vegetable oils are cis, the more double bonds there are, the lower the intermolecular forces, and the lower the melting point tends to be.

[0208] In this embodiment, the SP value of the styrene polymer (a-1) and the SP value of the biomass plasticizer (B) (cal / cm²) are compared. 3 ) 1 / 2 The absolute value of the difference 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, further 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.

[0209] When the SP value of the styrene polymer (a-1) differs from that of the biomass plasticizer (B) by more than ±2.5, the two are difficult to be compatible. As a result, the biomass plasticizer (B) is difficult to disperse uniformly in the styrene resin composition, showing a tendency to reduce the overall mechanical strength of the styrene resin composition.

[0210] Similarly, in this embodiment, the SP value of the styrene polymer (a-3) and the SP value of the biomass plasticizer (B) (cal / cm²) are compared. 3 ) 1 / 2The absolute value of the difference is 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, further 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.

[0211] When the SP value of the styrene polymer (a-3) differs from that of the biomass plasticizer (B) by more than ±2.5, the two are difficult to be compatible. As a result, the biomass plasticizer (B) is difficult to disperse uniformly in the styrene resin composition, showing a tendency to reduce the overall mechanical strength of the styrene resin composition and the total light transmittance of the molded article.

[0212] Furthermore, the SP value of the styrene polymer (a-1) in this embodiment is preferably 7 (cal / cm). 3 ) 1 / 2 )~11((cal / cm 3 ) 1 / 2 ), more preferably 7.5 (cal / cm 3 ) 1 / 2 )~10.5((cal / cm 3 ) 1 / 2 ), further preferably 7.8 (cal / cm 3 ) 1 / 2 )~10.2((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~10.0((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.8((cal / cm 3 ) 1 / 2 ), further preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.6((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.4((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3) 1 / 2 )~9.2((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.0((cal / cm 3 ) 1 / 2 ).

[0213] Furthermore, the SP value of the styrene polymer (a-3) in this embodiment is preferably 7 (cal / cm). 3 ) 1 / 2 )~11((cal / cm 3 ) 1 / 2 ), more preferably 7.5 (cal / cm 3 ) 1 / 2 )~10.5((cal / cm 3 ) 1 / 2 ), further preferably 7.8 (cal / cm 3 ) 1 / 2 )~10.2((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~10.0((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.8((cal / cm 3 ) 1 / 2 ), further preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.6((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.4((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.2((cal / cm 3 ) 1 / 2 ), and more preferably 8.0 ((cal / cm) 3 ) 1 / 2 )~9.0((cal / cm 3 ) 1 / 2 ).

[0214] Furthermore, the lower limit of the SP value of the biomass plasticizer (B) in this embodiment is more preferably 7.4 (cal / cm³). 3 ) 1 / 2 ) or more, preferably 7.5 ((cal / cm) 3 ) 1 / 2 ) or above, more preferably 7.6 (cal / cm 3 ) 1 / 2 ) or higher, more preferably 7.7 ((cal / cm) 3 ) 1 / 2 ) or above, and more preferably 7.8 ((cal / cm) 3 ) 1 / 2 The upper limit of this SP value is preferably 10.5 (cal / cm). 3 ) or less, more preferably 10.4 ((cal / cm) 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, preferably 9.8 ((cal / cm) 3 ) 1 / 2 ) or less, preferably 9.6 ((cal / cm) 3 ) 1 / 2 ) or less, preferably 9.4 ((cal / cm) 3 ) 1 / 2 ) or less, preferably 9.2 ((cal / cm) 3 ) or less, preferably 9.0 ((cal / cm) 3 Below ), and more preferably 8.8 (cal / cm) 3 ) 1 / 2 Below that. Furthermore, the preferred range of SP values ​​for the styrene polymer (a-1), styrene polymer (a-3), and biomass plasticizer (B) in this embodiment can be a range obtained by arbitrarily combining the upper limit and the lower limit of the aforementioned SP values.

[0215] The solubility parameter (SP value) specified in this embodiment is calculated using a function of cohesive energy density as shown in the following formula.

[0216] SP value (cal / cm) 3 ) 1 / 2 )=(△E / V) 1 / 2 Equation (2)

[0217] (ΔE represents the intermolecular cohesive energy (heat of vaporization), V represents the total volume of the mixture, and ΔE / V represents the cohesive energy density.)

[0218] In addition, the heat change ΔHm caused by mixing is expressed using the SP value by the following formula.

[0219] △Hm=V(δ1-δ2)·φ1·φ2...Equation (3)

[0220] (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.)

[0221] According to equations (2) and (3) above, the closer the values ​​of δ1 and δ2 are, the smaller ΔHm is, and the smaller the Gibbs free energy is. Therefore, the affinity between the two with small differences in SP values ​​increases.

[0222] As a method for determining the SP value in this specification, the SP value of the unknown resin is calculated from the SP value of the solvent with the best compatibility by comparing the solubility of the resin with various solvents whose SP values ​​are known. Specifically, the turbidity titration method described in the Example section is used for calculation. In this embodiment, the value obtained by calculation based on the monomer composition is mainly used.

[0223] When the biomass plasticizer (B) of this embodiment has a high boiling point, the amount of gas generated during molding is reduced. Therefore, from the viewpoint of reducing mold contamination, a higher boiling point (e.g., 260°C or higher, which is the molding temperature for injection blow molding) is preferred. When the SP value of the biomass plasticizer (B) is within the above range, the intermolecular cohesive energy, i.e., the heat of vaporization, can be controlled within a specified range, thus showing a tendency to become a high-boiling point product capable of reducing the amount of gas generated during molding.

[0224] In this embodiment, examples of mineral oils include: atmospheric residue obtained by atmospheric distillation of crude oils such as paraffinic crude oil (including liquid paraffin), intermediate-based crude oil, and naphthenic crude oil; distillate obtained by vacuum distillation of these atmospheric residues; mineral oil obtained by purifying the distillate through one or more processes such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrogenation purification; and mineral oil obtained by isomerizing waxes (GTL waxes) produced using the Fischer-Tropsch process or similar methods. These mineral oils can be used alone or in combination of two or more.

[0225] In this embodiment, when vegetable oil and mineral oil are used together as biomass plasticizer (B), there are no particular limitations as long as the overall biomass carbon ratio (pMC%) of biomass plasticizer (B) is 10% or more. For example, it is preferable to mix 10 to 100 parts by mass of mineral oil relative to 100 parts by mass of vegetable oil, and more preferably 10 to 50 parts by mass of mineral oil.

[0226] In this embodiment, when vegetable oil and mineral oil are used together as biomass plasticizer (B), there are no particular limitations as long as the overall biomass carbon ratio (pMC%) of biomass plasticizer (B) is 10% or more.

[0227] <Higher fatty acid compounds (C) (hereinafter also referred to as (C) components)>

[0228] The styrene-based resin composition of this embodiment may contain, as needed, 0.02% to 2.5% by mass of a higher fatty acid compound (C) relative to the total styrene-based resin composition. This higher fatty acid compound (C) functions as a release agent and may be one or more selected from the group consisting of higher fatty acids and metal salts of higher fatty acids. The content of the higher fatty acid compound (C) relative to the total styrene-based resin composition is preferably 0.04% to 2% by mass, more preferably 0.06% to 1.7% by mass, more preferably 0.08% to 1.4% by mass, and even more preferably 0.1% to 1.0% by mass.

[0229] When the content of higher fatty acid compounds (C) is below 0.02% by mass, the mold release properties are poor, leading to reduced productivity, which is not preferable. Furthermore, when the content of higher fatty acid compounds (C) is greater than 2.5% by mass, the mold release properties cannot be further improved; instead, there are concerns about problems such as resin discoloration, yellowing or blackening of molded products, and mold contamination caused by the decomposition and degradation of higher fatty acids.

[0230] When injection blow molding performance is important, the styrene resin composition of this embodiment preferably contains a rubber-modified styrene resin as a styrene resin (A), a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, and a higher fatty acid compound (C). In this case, the rubber-modified styrene resin may contain a styrene polymer (a-1) and rubber-like polymer particles (a-2) with an average particle size of 0.9 μm to 7.0 μm. Furthermore, relative to the total styrene resin composition (100% by mass), the content of the rubber-like polymer particles (a-2) may be 10% to 30% by mass, the content of the biomass plasticizer (B) may be 0.1% to 15% by mass, and the content of the higher fatty acid compound (C) may be 0.02% to 2.5% by mass.

[0231] The aforementioned higher fatty acids refer to saturated straight-chain carboxylic acids with 12 to 22 carbon atoms, such as stearic acid, lauric acid, myristic acid, palmitic acid, and behenic acid. Furthermore, metal salts of higher fatty acids refer to metal salts of saturated straight-chain carboxylic acids with 12 to 22 carbon atoms. Examples of such metals include zinc, calcium, magnesium, aluminum, barium, lead, lithium, potassium, and sodium. When using both higher fatty acids and higher fatty acid salts as higher fatty acid compounds (C), as long as the total amount of higher fatty acids and higher fatty acid salts is in the range of 0.02% to 2.5% by mass, these higher fatty acids or higher fatty acid salts can be used alone or in mixtures of two or more.

[0232] In addition, the aforementioned higher fatty acid compounds (C) can also be used as mold release agents in combination with polyethylene glycol or fatty acid alcohols and silicon additives.

[0233] <Optional Added Ingredients>

[0234] In the styrene-based resin composition of this embodiment, in addition to the above-mentioned components (A) and (B) and component (C) as optional components, known additives, processing aids, and other optional additives may be added as needed, without impairing the effects of the present invention. These optional additives may include mold release agents, flame retardants, dispersants, antioxidants, weathering agents, antistatic agents, fillers, anti-blocking agents, colorants, anti-frosting agents, surface treatment agents, antibacterial agents, and anti-fouling agents (such as silicone oil disclosed in Japanese Patent Application Publication No. 2009-120717, monoamide compounds of higher aliphatic carboxylic acids, and monoester compounds obtained by reacting higher aliphatic carboxylic acids with mono- to tri-membered alcohol compounds).

[0235] In this embodiment, the styrene-based resin composition may contain known flame retardants (phosphorus-containing flame retardants, halogen-containing flame retardants such as bromine-containing flame retardants). However, from the viewpoint of concerns about the generation of gases such as hydrogen bromide due to reaction with the biomass plasticizer (B) contained in the styrene-based resin composition, the content of halogen-containing flame retardants is preferably less than 3% by mass, more preferably less than 1% by mass, relative to the total amount (100% by mass) of the styrene-based resin composition.

[0236] The styrene-based resin composition in this embodiment preferably does not contain any metal elements except for unavoidable impurities. More specifically, the content of metal elements relative to the total amount (100% by mass) of the styrene-based resin composition is preferably less than 3% by mass, more preferably less than 1% by mass, and even more preferably less than 0.5% by mass. When the styrene-based resin composition contains metal elements, especially metal particles, not only will the mold used during molding be damaged, but metal powder from the mold may also easily mix into the styrene-based resin composition.

[0237] The aforementioned metallic elements refer to elements in Groups 2 to 12 of the periodic table, Group 1 excluding hydrogen, 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 alone or in the form of alloys or mixtures of two or more.

[0238] In this embodiment, fatty acid ester compounds, polyethylene glycol compounds, terpene compounds, rosin compounds, fatty acid amides, fatty acid compounds, or fatty acid metal salts can be used as dispersants.

[0239] As the aforementioned release agent, fatty acid compounds or fatty acid metal salts can be used.

[0240] Examples of antioxidants mentioned above include phenolic compounds, phosphorus-containing compounds, and thioether compounds.

[0241] The total content of the above-mentioned optional additives may be 0.05% to 5% by mass relative to the styrene resin composition as a whole.

[0242] The styrene-based resin composition of this embodiment may substantially contain only component (A), component (B), and optional additives. Alternatively, it may consist only of components (A) and (B), or only of components (A), (B), and optional additives. Furthermore, it may substantially contain only components (A), (B), (C), and optional additives. Alternatively, it may contain only components (A), (B), and (C), or only of components (A), (B), (C), and optional additives.

[0243] "Substantially containing only component (A), component (B), and optional additives" means that, relative to the total amount of the styrene resin composition, it is preferably 85% to 100% by mass, more preferably 90% to 100% by mass, further preferably 95% to 100% by mass, and even more preferably 98% to 100% by mass of component (A) and component (B), or component (A), component (B), and optional additives.

[0244] Similarly, "substantially containing only (A), (B), (C) and optional additives" means that, relative to the total amount of the styrene resin composition, it is preferably 85% to 100% by mass, more preferably 90% to 100% by mass, further preferably 95% to 100% by mass, and even more preferably 98% to 100% by mass of (A), (B), and (C), or (A), (B), (C) and optional additives.

[0245] It should be noted that, without impairing the effects of the present invention, the styrene resin composition of this embodiment may contain unavoidable impurities in addition to components (A), (B), (C) and optional additives.

[0246] When using modified vegetable oil as the biomass plasticizer (B) in the styrene-based resin composition of this embodiment, the content of hydroxyl-containing compounds is preferably less than 3% by mass, more preferably less than 1% by mass, relative to the total amount (100% by mass) of the styrene-based resin composition. In this embodiment, hydroxyl-containing compounds refer to compounds such as (meth)acrylic acid, maleic acid, and phthalic acid that have hydroxyl groups in the polymer. When the content of hydroxyl-containing compounds is 3% by mass or more, they react with the modified vegetable oil, resulting in gelation and thus adverse effects such as reduced moldability or deterioration of the appearance of the injection-molded article. When using natural vegetable oil as the biomass plasticizer in the styrene-based resin composition, the amount of hydroxyl-containing compounds is not specified.

[0247] Properties of styrene-based resin compositions

[0248] Hereinafter, preferred properties of each suitable embodiment of the styrene-based resin composition will be described.

[0249] <Total transmittance (%)>

[0250] In this embodiment, where transparency is emphasized in the styrene-based resin composition, that is, when the amount of rubbery polymer particles (a-2) contained in the styrene-based resin composition is less than 3% by mass, the total light transmittance (%) of the styrene-based resin composition is preferably 70% or more, more preferably 75% or more, further preferably 80% or more, and even more preferably 85% or more. When the total light transmittance (%) of the styrene-based resin composition is 80% or more, for example, the content of rubbery polymer particles (e.g., rubbery polymer particles (a-2)) contained in the styrene-based resin composition is set to less than 3% by mass relative to the styrene-based resin composition as a whole, or is set to a range that can be used in transparent food containers, packaging materials, or office automation equipment where transparency is required.

[0251] Furthermore, by setting the biomass plasticizer (B) of this embodiment to a specific vegetable oil such as palm oil, epoxidized soybean oil, epoxidized linseed oil, polyoxyethylene castor oil, oleate, or laurate, or by setting the SP value of the biomass plasticizer (B) of this embodiment to less than 10, the mixing state within the composition also changes, thus enabling the total transmittance (%) of the styrene resin composition to be adjusted to a desired value (e.g., 70% or more).

[0252] The specific method for preparing the test pieces used in determining the total transmittance (%) of styrene-based resin compositions is based on K7361-1, and it is confirmed that the test pieces are free from defects such as scratches, bubbles, and impacts, as well as the adhesion of dust or grease, and the adhesion of adhesives from protective materials. Furthermore, there are no visible voids or particles on the surface of the test pieces. Moreover, when preparing the test pieces by injection molding, mirror polishing can be performed as needed, using abrasive paper, oilstone, or free abrasive particles, depending on the condition of the mold surface used.

[0253] The method for determining total transmittance (%) and the method for preparing the test piece used in the method for determining total transmittance (%) are described in the Example 1 section below.

[0254] <Mel flow rate (MFR)>

[0255] The melt flow rate (measured at 200°C and 49N load) of the styrene resin composition of this embodiment is preferably 1.5 g / 10 min or more, more preferably 2.0 g / 10 min or more. When it is less than 1.5 g / 10 min, the fluidity is low, and the processing temperature needs to be increased.

[0256] In particular, considering not only the need for reduced environmental impact and excellent mechanical strength, but also for excellent molding cycle time and reduced mold contamination during injection molding, the melt flow rate (measured under conditions of 200°C and 49N load) of the styrene resin composition of this embodiment is preferably 10 (g / 10 min) to 80 (g / 10 min), more preferably 13 (g / 10 min) to 60 (g / 10 min), further preferably 15 (g / 10 min) to 50 (g / 10 min), and even more preferably 15 (g / 10 min) to 35 (g / 10 min). This provides a styrene resin composition that achieves an excellent balance between reduced environmental impact, high mechanical strength, and excellent molding cycle time, while minimizing mold contamination during injection molding. Furthermore, when the MFR of the styrene resin composition is less than 10, the fluidity decreases, the appropriate molding temperature increases, and therefore the cooling time tends to lengthen. To achieve an MFR higher than 80 for the styrene resin composition, a large amount of plasticizer is required, thus reducing heat resistance. When the heat resistance decreases, the curing temperature decreases, thus exhibiting a tendency for a longer cooling time. It should be noted that when the molding temperature can be lowered, the cooling time becomes shorter, and the molding cycle time increases. When the melt flow rate of the styrene-based resin composition of this embodiment is within the above-mentioned range, the overall fluidity of the composition is maintained at a high level, thereby reducing mold contamination during molding.

[0257] On the other hand, when the total light transmittance of the styrene-based resin composition of this embodiment is 70% or more for a sheet with a thickness of 2 mm, and the styrene-based resin composition is mainly used for sheet applications such as biaxially stretched sheets, from the viewpoint of emphasizing sheet formability or sheet appearance, the melt flow rate (measured under conditions of 200°C and 49N load) of the styrene-based resin composition of this embodiment is preferably 1.0 g / 10 min to 7.0 g / 10 min, more preferably 1.5 g / 10 min to 6.0 g / 10 min, further preferably 1.8 g / 10 min to 5.0 g / 10 min, and even more preferably 2.0 g / 10 min to 4.5 g / 10 min. When the MFR is less than 1.0, the sheet production rate decreases. In addition, uneven sheet thickness is easily generated. When the MFR is greater than 7.0, it is necessary to reduce the molecular weight of the resin or increase the amount of plasticizer. When the molecular weight of the resin is reduced, there is a concern about a decrease in mechanical strength. Furthermore, with an increased amount of plasticizer, the Vicat softening temperature decreases, raising concerns about the possibility of not achieving the required heat resistance.

[0258] Furthermore, considering that the total light transmittance of the styrene resin composition of this embodiment is 70% or more for a 2mm thick plate, and that the styrene resin composition is mainly used for injection molded parts, from the viewpoint of minimizing mold contamination, the melt flow rate (MFR) of the styrene resin composition of this embodiment (measured under conditions of 200°C and 49N load) is 3.0 (g / 10 min) to 60 (g / 10 min), preferably 3.5 (g / 10 min) to 50 (g / 10 min), more preferably 4.0 (g / 10 min) to 40 (g / 10 min), and even more preferably 4.5 (g / 10 min) to 35 (g / 10 min). When the MFR of the styrene resin composition is less than 3.0, the fluidity decreases, and underfilling is easily caused during injection molding, resulting in reduced injection moldability. To achieve an MFR greater than 60 for the styrene resin composition, a large amount of plasticizer is required, thus increasing the volatile components during injection molding, raising concerns about worsening mold contamination.

[0259] Furthermore, considering injection blow molding, the melt flow rate (measured under conditions of 200°C and 49N load) of the styrene resin composition in this embodiment is 3.0 (g / 10 min) to 13.0 (g / 10 min), preferably 3.3 (g / 10 min) to 11.5 (g / 10 min), more preferably 3.5 (g / 10 min) to 10.0 (g / 10 min), and even more preferably 4.0 (g / 10 min) to 9.5 (g / 10 min). When the melt flow rate is less than 3.0, the fluidity is poor, and incomplete filling is likely to occur during molding. Although molding can be achieved by increasing the molding temperature and core temperature, the demolding balance is disrupted, resulting in uneven thickness and unqualified products. In addition, when the melt flow rate is greater than 13.0, stringing is likely to occur between the injection mold and the preform, making continuous molding difficult.

[0260] It should be noted that the melt mass flow rates in this disclosure are all values ​​measured according to ISO 1133 at a temperature of 200°C and a load of 49N.

[0261] <Vicat softening temperature>

[0262] The Vicat softening temperature of the styrene resin composition of this embodiment is preferably 50°C to 100°C, more preferably 55°C to 98°C, more preferably 60°C to 97°C, more preferably 63°C to 96°C, and even more preferably 65°C to 95°C.

[0263] In particular, considering not only the need for reduced environmental impact and excellent mechanical strength, but also for excellent molding cycle time and reduced mold contamination during injection molding, the Vicat softening temperature of the styrene-based resin composition in this embodiment is preferably 50°C to 105°C, more preferably 65°C to 95°C, and even more preferably 75°C to 90°C. When the Vicat softening temperature of the styrene-based resin composition is higher than 105°C, the fluidity decreases, the appropriate molding temperature becomes higher, and therefore a tendency for the cooling time to increase is observed. Conversely, when the Vicat softening temperature of the styrene-based resin composition is lower, the curing temperature becomes lower, and therefore a tendency for the cooling time to increase is observed.

[0264] On the other hand, when the total light transmittance of the styrene-based resin composition of this embodiment is 70% or more for a sheet with a thickness of 2 mm, and the styrene-based resin composition is mainly used for sheet applications such as biaxially stretched sheets, from the viewpoint of emphasizing sheet formability or sheet appearance, the Vicat softening temperature of the styrene-based resin composition of this embodiment is preferably 90°C or higher, more preferably 90°C to 105°C, even more preferably 93°C to 103°C, and even more preferably 95°C to 101°C. When the Vicat softening temperature is less than 90°C, it is difficult to obtain the heat resistance required for biaxially stretched sheets and food packaging applications. In addition, when the Vicat softening temperature is greater than 105°C, the resin fluidity decreases, thus reducing sheet production efficiency. Furthermore, uneven sheet thickness is more likely to occur.

[0265] In this embodiment, where the total light transmittance of the styrene-based resin composition with a thickness of 2 mm is 70% or more, and the styrene-based resin composition is primarily used for injection molded parts, from the viewpoint of minimizing mold contamination, the Vicat softening temperature of the styrene-based resin composition is preferably 50°C to 105°C, more preferably 60°C to 95°C, and even more preferably 65°C to 90°C. When the Vicat softening temperature of the styrene-based resin composition is high, its fluidity decreases, making it prone to underfilling during injection molding and reducing its injection moldability. Furthermore, when the Vicat softening temperature of the styrene-based resin composition decreases, the amount of plasticizer increases, thus raising concerns about worsening mold contamination.

[0266] Taking injection blow molding into account, the Vicat softening temperature of the styrene resin composition of this embodiment is preferably 75°C to 100°C, more preferably 78°C to 98°C, and even more preferably 80°C to 96°C.

[0267] It should be noted that the Vicat softening temperature (°C) in this disclosure is determined according to ISO 306 under a load of 49 N.

[0268] <Swelling Index>

[0269] In this embodiment, from the viewpoint of impact strength, the swelling index of the styrene-based resin composition containing rubber-like polymer particles (a-2) is preferably 8.5 to 14, more preferably 9.0 to 13. Alternatively, from the viewpoint of impact strength, the swelling index of the rubber-like 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. The swelling index is an indicator of the degree of crosslinking of the rubber particles. By adjusting the swelling index to the above range, the styrene-based resin composition of the present invention exhibits excellent impact characteristics. It should be noted that, in this disclosure, the swelling index of the styrene-based resin composition is a value calculated using the method described in the Example 1 section.

[0270] [Best Mode]

[0271] A particularly preferred embodiment of the styrene-based resin composition is a styrene-based resin composition containing 90% to 99.9% by mass of a rubber-modified styrene-based resin and 0.1% to 10% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more. The rubber-modified styrene-based resin comprises a polymer matrix phase containing the styrene-based resin (A) and a rubber-like polymer dispersed within the polymer matrix phase.

[0272] The content of (meth)acrylonitrile monomer units is less than 10% by mass relative to the overall polymer matrix phase, and the SP value of the polymer matrix phase is 8.0 to 9.0.

[0273] The SP value of the above-mentioned biomass plasticizer (B) is 7.5–8.8.

[0274] The absolute value of the difference between the SP value of the polymer matrix phase and the SP value of the biomass plasticizer (B) is less than 0.8, and the content of the halogenated flame retardant is less than 1% by mass.

[0275] Therefore, it is possible to provide a styrene-based resin composition suitable for injection molding, especially injection blow molding, which reduces environmental impact by using biomass raw materials, has high mechanical strength (e.g., mouth impact strength and flexural strength) during molding, excellent injection molding or injection blow molding properties, and less mold contamination during molding.

[0276] It should be noted that the SP value of the polymer matrix phase described above can be the SP value of the styrene-based polymer (a-1) constituting the polymer matrix phase described above. Additionally, the rubber-like polymer described above can be rubber-like polymer particles.

[0277] [Method for manufacturing styrene-based resin compositions]

[0278] 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 or the devolatilization process, or by melt-blending the components using any method. Examples include using, alone or in combination, a high-speed mixer such as a Henschel mixer, a batch mixer such as a Banbury internal mixer, a single-screw or twin-screw continuous mixer, a roller mixer, etc. The heating temperature during blending is typically selected within the range of 180°C to 250°C.

[0279] [Molded body]

[0280] The molded article of the present invention is characterized in that it comprises the above-described styrene-based resin composition.

[0281] The styrene-based resin composition of this embodiment can be used to manufacture molded articles by means of the above-described melt mixing molding machine or by using the particles of the obtained styrene-based resin composition as raw materials, such as injection molding, injection compression molding, extrusion molding, blow molding, compression molding, vacuum molding, and foam molding.

[0282] The molded body of this embodiment can be obtained by molding the styrene-based resin composition of the above embodiment. There are no particular limitations as long as the molded body of this embodiment is obtained by molding the styrene-based resin composition of the present invention described above; however, it is preferable that the molded body has a portion with a thickness of 1 mm or less. The above-described styrene-based resin composition can be appropriately used in molded bodies having a thickness of 1 mm or less.

[0283] Furthermore, there are no particular limitations on the molded body of this embodiment, but containers or sheets are preferred. The container of this embodiment can be directly manufactured (molded) from a styrene-based resin composition, or it can 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 not only to manufacture (molde) containers, but also to manufacture (molde) other molded bodies.

[0284] The sheet in this embodiment is a non-foamed extruded sheet, and there is no particular limitation on the thickness. For example, it can be set to less than 1.0 mm, preferably 0.2 mm to 0.8 mm.

[0285] The sheet of this embodiment can be multilayered with general styrene resins such as polystyrene resin. Alternatively, it can be multilayered with resins other than styrene resins in addition to the styrene resin layer, or it can be multilayered with resins other than styrene resins instead of the styrene resin layer. Examples of resins other than styrene resins include: PP resin, PP / PS resins, PET resin, nylon resin, etc.

[0286] The container in this embodiment is either a container obtained by injection blow molding using the above-described styrene resin composition or a container obtained by sheet molding.

[0287] Specifically, there are no particular limitations on the container obtained by injection blow molding in this embodiment. Examples include containers for storing or containing beverages such as lactic acid bacteria drinks and foods such as fermented milk. The container can be made into a cylindrical vertical shape with a flange surface at the opening and an opening at the top. The container can be made in a size with a height of 50mm to 120mm, a diameter of 30mm to 60mm, and a thickness of 0.2mm to 0.8mm.

[0288] Furthermore, there are no particular limitations on the containers obtained by molding the above-mentioned sheets in this embodiment. Examples include: lids for boxed meals or containers for holding side dishes, which are obtained by molding sheets or multi-layer bodies containing sheets.

[0289] [Biaxial tensile sheet]

[0290] This disclosure pertains to a biaxially stretched sheet comprising the aforementioned styrene-based resin composition. Furthermore, the method for manufacturing the biaxially stretched sheet using the styrene-based resin composition of this embodiment as a raw material can employ conventionally known methods. The forming temperature of the stretch forming machine is preferably 180°C to 280°C, more preferably 200°C to 260°C, and even more preferably 210°C to 250°C.

[0291] Biaxially stretched sheets can be re-formed using thermoforming methods such as vacuum forming and compressed air forming. Applications of the formed biaxially stretched sheets of this invention include various containers, primarily for food packaging containers.

[0292] The styrene-based resin composition suitable for the biaxially stretched sheet of this embodiment contains, relative to the total styrene-based resin composition, 94% to 99.9% by mass, preferably 97% to 99.9% by mass, of a styrene-based polymer (a-3), 0.1% to 3% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, and less than 3% by mass of rubbery polymer particles (a-2). The total light transmittance of the styrene-based resin composition for a 2 mm thick sheet is 70% or more, the Vicat softening temperature of the styrene-based resin composition is 90°C or more, and the SP value of the biomass plasticizer (B) is 7.4 to 10.5. The styrene-based polymer (a-3) is preferably 97.0% to 99.9% by mass relative to the total styrene-based resin composition.

[0293] [Injection Molded Parts]

[0294] This disclosure pertains to injection-molded articles comprising the aforementioned styrene-based resin composition. Furthermore, the method for manufacturing injection-molded articles using the styrene-based resin composition of this embodiment as a raw material can employ conventionally known methods. The temperature of the molding machine is preferably 150°C to 300°C, more preferably 160°C to 260°C, and even more preferably 180°C to 240°C.

[0295] When the temperature of the molding machine exceeds 300°C, the styrene-based resin composition undergoes thermal decomposition, which is therefore undesirable. On the other hand, when the temperature of the molding machine is below 150°C, molding is impossible due to high viscosity, which is also undesirable.

[0296] The styrene-based resin composition suitable for injection-molded articles according to this embodiment contains, relative to the total styrene-based resin composition, 85% to 97% by mass of a styrene-based polymer (a-3) and 3.0% to 15% by mass of a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more.

[0297] Preferably, the composition contains less than 3% by mass of rubbery polymer particles of the styrene-based resin composition, the total light transmittance of the 2mm thick plate of the styrene-based resin composition is 70% or more, and the SP value of the biomass plasticizer (B) is 7.4 to 10.5.

[0298] [Injection blow molded parts]

[0299] This disclosure pertains to injection blow molded articles comprising the aforementioned styrene-based resin composition. Furthermore, the method for manufacturing injection blow molded articles using the styrene-based resin composition of this embodiment as a raw material is not particularly limited, and can be molded using known methods. Specifically, in injection blow molding, an intermediate (e.g., a bottomed preform) is first formed from the styrene-based resin composition by injection molding. Then, the intermediate, in a softened state, is transferred into a blow molding die while mounted on a core (the male mold of the injection molding). Compressed air is then introduced from the core to expand it to the inner wall of the blow molding die, thereby forming a hollow molded article (e.g., a container).

[0300] In the above molding method, during the blow molding stage of the intermediate, the mold temperature is preferably 35°C to 75°C, more preferably 40°C to 60°C, and even more preferably 45°C to 55°C. Furthermore, the temperature of the styrene-based resin composition is preferably 210°C to 260°C, more preferably 220°C to 250°C. The volume ratio of the container to the intermediate (volume stretching ratio) is preferably 1.5 to 7 times, more preferably 2 to 5 times.

[0301] The styrene-based resin composition suitable for injection blow molding of this embodiment contains a styrene-based polymer (a-1), a biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, a higher fatty acid compound (C), and rubbery polymer particles (a-2) with an average particle size of 0.9 μm to 7.0 μm, relative to the total styrene-based resin composition (100% by mass).

[0302] Preferably, the content of the above-mentioned rubbery polymer particles (a-2) is 10% to 30% by mass, the content of the above-mentioned biomass plasticizer (B) is 0.1% to 15% by mass, the content of the above-mentioned higher fatty acid compound is 0.02% to 2.5% by mass, and the weight average molecular weight of the above-mentioned styrene polymer (a-1) is 140,000 to 240,000.

[0303] Molded articles, particularly injection molded articles (including injection compression), sheets, and injection blow molded articles containing the styrene-based resin compositions of this embodiment, can be appropriately used in food packaging containers, copiers, fax machines, personal computers, printers, information terminals and other office automation equipment, refrigerators, vacuum cleaners, microwave ovens, household appliances, housings or various parts of electrical / electronic equipment, interior or exterior parts of automobiles, building materials, foamed insulation materials, insulating films, etc.

[0304] Example

[0305] Hereinafter, embodiments and comparative examples will be described in more detail, but the present invention is not limited to these embodiments.

[0306] 1. Measurement and Evaluation Methods

[0307] The physical properties of the styrene-based resin compositions, extruded sheets, biaxially stretched sheets, injection molded articles, and injection blow molded articles obtained in the various embodiments and comparative examples were determined and evaluated based on the following methods.

[0308] (1) Determination of the weight-average molecular weight of the styrene resins (A) (including rubber-modified styrene resins, styrene polymers (a-1) and styrene polymers (a-3), hereinafter the same), biomass plasticizers (B), and styrene resin compositions used in the Examples and Comparative Examples.

[0309] The weight-average molecular weights of styrene resins (A) and biomass plasticizers (B) were determined according to the following conditions and procedures.

[0310] • Sample preparation: Dissolve 5 mg of the test sample in 10 mL of tetrahydrofuran and filter using a 0.45 μm filter.

[0311] • Measurement conditions

[0312] Equipment: TOSOH HLC-8220GPC

[0313] (Gel permeation chromatography)

[0314] Column: Connect two SHODEX GPC KF-606M in series.

[0315] Protective pillar: SHODEX GPC KF-G 4A

[0316] Temperature: 40℃

[0317] Carrier: THF 0.50 mL / min

[0318] Detector: RI, UV: 254nm

[0319] Calibration curves: Eleven types of TSK standard polystyrene (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) manufactured by Tosoh Corporation were used in the preparation of the calibration curves. An approximation using cubic linearity was employed to create the calibration curves.

[0320] (2) Melt mass flow rate (MFR)

[0321] The melt mass flow rate (g / 10 min) of the styrene resin (A) and the styrene resin composition used in the examples and comparative examples was determined according to ISO 1133 (200°C, load 49 N).

[0322] (3) Determination of Vicat softening temperature (°C)

[0323] The Vicat softening temperature (°C) of the styrene resin (A) and the styrene resin composition used in this example and comparative example was determined according to ISO 306 under a load of 49 N.

[0324] (4) Determination of the content and swelling index of rubbery polymer particles (a-2)

[0325] The content (mass%) and swelling index of rubber-modified styrene resin or styrene resin composition of rubber-like polymer particles (a-2) were determined as follows: 1.00 g of rubber-modified styrene resin or styrene resin composition (this mass is designated W1) was accurately weighed into a precipitation tube, 20 ml of toluene was added, and the mixture was shaken at 23°C for 1 or 2 hours. Then, the mixture was centrifuged for 60 minutes using a centrifuge (manufactured by Sakuma Seisakusho Co., Ltd., SS-2050A rotor: 6B-N6L) at 4°C, 20000 rpm, and a centrifugal acceleration of 45100×G. The precipitation tube was slowly tilted to approximately 45 degrees, and the supernatant was removed by decantation. The mass of the toluene-insoluble component was accurately weighed (this mass is designated W2). The mixture was then vacuum dried at 160°C and below 3 kPa for 1 hour, cooled to room temperature in a desiccator, and the mass of the toluene-insoluble component was accurately weighed (this mass is designated W3).

[0326] It should be noted that in Examples 1, 2a-2d, 3-5 and Comparative Examples 1-4, the vibration was carried out at 23°C for 2 hours, and in other examples, the vibration was carried out for 1 hour.

[0327] The content and swelling index of rubber-like polymer particles (a-2) in styrene resin (A) or styrene resin composition are determined according to the following formula, i.e., the content and swelling index of rubber-like polymer particles (a-2) in styrene resin (A) or styrene resin composition.

[0328] Content of rubbery polymer particles (a-2) = W3 / W1 × 100

[0329] The swelling index of rubbery polymer particles (a-2) = W2 / W3

[0330] It should be noted that in Example 11 described later, when toluene was used as the solvent, the gel component also flowed out during decantation, making it impossible to determine accurate values. Therefore, limited to Example 11 described later, the same treatment was performed using a methyl ethyl ketone / methanol = 9 / 1 solution to determine the content of rubber-like polymer particles (a-2) and the swelling index of rubber-like polymer particles (a-2).

[0331] (5) Determination of average particle size

[0332] The average particle size (μm) of the rubbery polymer particles (a-2) in the styrene resin (A) or styrene resin composition used in the examples and comparative examples was determined by the following method.

[0333] Using a COULTERMULTISIZER III (trade name) manufactured by Beckman Coulter, Ltd., fitted with a 30 μm diameter perforated tube, 0.05 g of styrene-based resin (A) particles or styrene-based resin composition particles were placed in approximately 5 ml of dimethylformamide and left to stand for approximately 2 to 5 minutes. The dissolved dimethylformamide content was then measured as an appropriate particle concentration to determine the median particle size on a volume basis.

[0334] In Example 11 described later, when using the COULTER MULTISIZER III, the average particle size of the rubbery polymer particles (a-2) was smaller than the lower limit of the measurement range, and therefore a proper measurement could not be performed. Therefore, limited to Example 11, after performing the same treatment, the median particle size based on volume was determined using a laser particle size distribution measuring apparatus manufactured by Beckman Coulter Ltd.

[0335] (6) Determination of the content of rubbery polymers

[0336] 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 then added to convert the residual iodine monochloride into iodine, and back titration was performed using sodium thiosulfate (iodine monochloride method). The mass of rubber contained in the styrene resin (A) or styrene resin composition was determined by this method (this mass is set as W4). Based on this value and the mass of the styrene resin (A) or styrene resin composition (this mass is set as W1), the content (mass %) of the rubbery polymer in the styrene resin (A) or styrene resin composition was calculated using the following formula.

[0337] The content (mass%) of the rubbery polymer in styrene resin (A) or styrene resin composition = W4 / W1 × 100

[0338] (7) Method for determining biomass carbon ratio (pMC%)

[0339] The biomass carbon ratio (pMC%) of biomass plasticizer (B) is determined by radiocarbon dating according to ASTM-D6866. 14 C) Determination method, using the following formula (1) to calculate ( using AMS method) 14 C plasticizer / 12 C plasticizer) / ( 14 C standard reference / 12 (C standard reference).

[0340] Equation (1):

[0341] Biomass carbon ratio (pMC%) = ( 14C plasticizer / 12 C plasticizer) / ( 14 C standard reference / 12 (C standard reference) × 100

[0342] In addition, oxalic acid (SRM 4990) was used as a standard substance.

[0343] The biomass carbon ratio in styrene-based resin compositions is calculated in the same manner as described above.

[0344] (8) Quantitative analysis of the content of biomass plasticizer (B)

[0345] In determining the amount of biomass plasticizer (B) in the styrene resin compositions used in the examples and comparative examples, either step (8-1) or (8-2) below was used. It should be noted that comparing the value obtained by step (8-1) with the value obtained by step (8-2) also yields equal values.

[0346] (8-1) Analysis using NMR

[0347] Vegetable oil (glycerol fatty acid ester) was dissolved in deuterated chloroform (with 1% TMS added) containing 1,2-dimethoxyethane as an internal standard, and then... 1 ¹H-NMR determination. When the TMS peak was used as a 0 ppm reference, peaks attributable to protons bonded to carbons adjacent to the ester groups of the vegetable oil were detected in the range of 4.0 ppm to 4.4 ppm, and peaks attributable to 1,2-dimethoxyethane were detected in the range of 3.4 ppm to 3.6 ppm. The peak area attributable to the vegetable oil was calculated when the peak area attributable to 1 was set to 1. This process was repeated with varying vegetable oil concentrations to create a calibration curve for the vegetable oil concentration.

[0348] The particulate styrene resin composition obtained in the examples or comparative examples was dissolved in deuterated chloroform (with 1% TMS added) and subjected to... 1 The content of vegetable oil in the styrene resin composition was quantified by ¹H-NMR determination using the calibration curve described above.

[0349] In the methods described above, when other peaks overlap with the internal standard and are difficult to quantify, an appropriate substance can be used as an internal standard. Additionally, vegetable oils can be quantified using peaks attributed to triglycerides detected in the range of 5.0 ppm to 5.5 ppm.

[0350] (8-2) Calculated from methanol-soluble components

[0351] 1.0 g of the granular styrene resin composition obtained in the examples or comparative examples (this weight is designated W11) was placed in a 20 mL screw-top bottle, and 10 mL of methyl ethyl ketone was added. The granules were then completely dissolved using a shaker, followed by the addition of 5 mL of methanol to precipitate the styrene polymer as an insoluble substance. The precipitate was then centrifuged at 2000 G for 10 minutes to allow it to settle. The settled insoluble component was then pre-dried at 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 component was determined and designated W12. The methanol-soluble component (W13) was defined using the measured masses W11 and W12 as shown below.

[0352] Methanol-soluble component (W13) = W11 - W12.

[0353] In addition, in this operation, the supernatant after centrifugation was subjected to GC-MS analysis to quantify the content of styrene oligomers, residual monomers, residual solvents, and other low-molecular-weight substances soluble in methanol other than plasticizers, and the mass (W14) contained in 1.0 g of 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.

[0354] The content of biomass plasticizer (B) = W13 - W14

[0355] (9) Calculation of SP value

[0356] SP values ​​for each material used in the examples and comparative examples were obtained using the Hilderbrand method (including the Hansen method) and calculated by turbidity titration with reference to literature values ​​(“Fundamentals of Biomaterials”, edited by Kazuhiko Ishizuka, Takao Hanawa, and Mizuo Maeda, published by Nippon Medical School) or with reference to “J. Appl. Polym. Sci., 12, 2359 (1968)”.

[0357] It should be noted that in the styrene-based resin compositions of the examples and comparative examples, since the components incorporated in the compositions are known, the SP value can be easily calculated using the above method. On the other hand, when the details of the styrene polymer or plasticizer contained in an unknown styrene-based resin composition are unknown, the SP value can be calculated using the following steps (i) to (iv). Step (i): The sample (styrene polymer or plasticizer) to be recovered or separated from the styrene-based resin composition is added to a solvent with a known SP value, and a dissolution test is performed to determine whether the sample dissolves in the solvent with a known SP value. Step (ii): Next, a three-dimensional plot of the SP value of the solvent used in the dissolution test of step (i) is generated. Step (iii): Steps (i) and (ii) are performed using 15 to 20 solvents. Step (iv): Calculate a sphere that includes the coordinates of the solvent in which the sample was dissolved but does not include the coordinates of the solvent in which the sample was not dissolved. The center coordinates of this sphere represent the Hansen SP value, and the distance from the origin represents the Hildebrand SP value. The solubility parameter is then calculated using the Hildebrand method (including the Hansen method).

[0358] The SP values ​​calculated through steps (i) to (iv) above are basically consistent with the values ​​in the literature or the SP values ​​calculated by turbidity titration.

[0359] Furthermore, visual confirmation is made that the sample is either soluble in a solvent with a known SP value or insoluble in a solvent with a known SP value. Specifically, if the sample is insoluble, when dissolved in the solvent, a white turbidity is produced, or it forms droplets, and the sample separates from the solvent. On the other hand, if the sample is soluble, when dissolved in the solvent, it mixes uniformly in a transparent state.

[0360] Furthermore, when the biomass plasticizer (B) is of low molecular weight, it is sometimes impossible to calculate using turbidity titration. In this case, Fedors' estimation method or Hoy's calculation method is used instead of the above-mentioned turbidity determination method (for example, see "Coatings Research (Discussion on Solubility Parameters of Additives) Issue 152, October 2010").

[0361] (10) Calculation of modification rate

[0362] For styrene resins containing modified vegetable oils, use either step (10-1) or (10-2) below, through 1 The modification rate of the modified vegetable oil was calculated using H-NMR.

[0363] Step (10-1)

[0364] The particulate styrene resin composition obtained in the examples or comparative examples was dissolved in deuterated chloroform (with 1% TMS added) and subjected to... 1 ¹H-NMR determination. When TMS was used as a 0 ppm reference, peaks belonging to epoxy groups were identified in the range of δ 2.8 ppm to 3.2 ppm, and peaks belonging to protons bonded to carbons adjacent to the ester groups of vegetable oils were identified in the range of δ 4.0 ppm to 4.4 ppm. The epoxy modification rate was calculated from the area ratio of these two peaks. Peaks belonging to epoxy groups were detected in the range of δ 2.8 ppm to 3.2 ppm, and peaks belonging to protons bonded to carbons adjacent to the ester groups of vegetable oils were detected in the range of δ 4.0 ppm to 4.4 ppm. However, when these peaks overlapped with other peaks, quantification was difficult. Therefore, in this case, quantification was performed using the method described in step (10-2).

[0365] Step (10-2)

[0366] One g of the granular styrene resin composition obtained in the examples or comparative examples was placed into a 20 mL screw-top flask, and 10 mL of methyl ethyl ketone (MEK) was added. The granules were then completely dissolved using a shaker, followed by the addition of 5 mL of methanol. At this point, the styrene resin composition precipitated in the solution as an insoluble component. The insoluble portion was then removed, and the remaining solution was transferred to a round-bottom flask and evaporated under vacuum for 2 hours to allow the MEK and methanol to evaporate. The remaining liquid (vegetable oil) in the round-bottom flask was then added to deuterated chloroform (with 1% TMS added) and subjected to further processing. 1 ¹H-NMR determination. With TMS as a 0 ppm reference, peaks attributable to epoxy groups were identified in the range of 2.8 ppm to 3.2 ppm, and peaks attributable to protons bonded to carbons adjacent to the ester groups of the vegetable oil were identified in the range of 4.0 ppm to 4.4 ppm. The epoxy modification rate was calculated from the area ratio of these two peaks. The epoxy modification rate was defined as the number of moles of epoxy groups relative to 1 g of modified vegetable oil.

[0367] (11) Nominal strain at tensile fracture of sheet

[0368] The nominal tensile strain at break of the extruded sheets prepared in Examples 1-5 and Comparative Examples 1-4 was measured. Specifically, a dumbbell of JIS K6251-3 was punched from the extrusion (MD) direction and its orthogonal (TD) direction of the extruded sheet, and a tensile test was performed at a test speed of 50 mm / min and a fixture spacing of 60 mm, and the nominal tensile strain at break was measured.

[0369] (12) Evaluation of the appearance of the piece (number of dirt) (1)

[0370] When producing the extruded sheets obtained in Examples 1, 2a-2d, 3-5 and Comparative Examples 1-4, the sheet surface was visually inspected, and the number of contaminants with a major diameter of 1.0 mm or more per 10 m was measured.

[0371] (13) Impact test of simply supported beam

[0372] The styrene-based resin compositions obtained in the examples and comparative examples were used to prepare injection-molded sheets at 220°C according to JIS K 7152, and the impact strength of simply supported beams was determined according to JIS K 7111-1.

[0373] (14) Mouth impact strength

[0374] The injection blow-molded container was placed horizontally with its parting line aligned vertically, and a drop hammer was used to contact the opening. The drop hammer impact strength (DuPont impact strength) was measured using a DuPont impact testing machine (No. 451) manufactured by Toyo Seisakusho Co., Ltd. The test was conducted under the conditions of a 200g drop hammer, a 9.4mm radius at the center of impact, and n=30. The drop hammer impact strength was calculated from the 50% fracture height. A strength of 3.0 kg·cm or higher was considered acceptable.

[0375] (15) Mouth compression strength

[0376] The injection blow-molded container was placed horizontally with its parting line aligned vertically. It was compressed at a speed of 200 mm / min with the mouth flange in perpendicular contact. The load up to 10 mm of deformation was taken as the mouth compression strength. In this test, containers with two injection volumes were used, and the measured values ​​were averaged. A mouth compression strength of 23 or higher was considered acceptable. It should be noted that a Shimadzu Autograph AGS-5kNX benchtop precision universal testing machine was used as the testing device.

[0377] (16) Bending strength

[0378] The injection blow-molded container is fixed on the lower pressure plate of the compression tester. A compression load clamp protruding from the movable part of the compression testing machine is used to measure the compressive strength when a load is applied at a pressing speed of 200 mm / min. It should be noted that a Shimadzu Autograph AGS-5kNX benchtop precision universal testing machine is used as the testing device. The test results are evaluated according to the following standards. When the buckling strength is less than 120 N, the rigidity is insufficient, which may cause container buckling and other drawbacks in actual use. Therefore, a strength of 120 N or more is considered acceptable.

[0379] (17-1) Formability (cooling time during molding)

[0380] In the evaluation method for cooling time during molding in the embodiments and comparative examples, the cooling time sufficient to allow the molded article to solidify without deformation after molding was measured when 10 2mm plates were injection molded. In these embodiments and comparative examples, an EC60N injection molding machine manufactured by Toshiba Machine Co., Ltd. was used, and molding was performed at a mold temperature of 45°C. In addition, the injection pressure, injection time, and holding pressure were kept constant, and for each embodiment, the barrel temperature was set to a temperature that allowed the plates to be molded without underfill.

[0381] (17-2) Molding properties (injection molding properties)

[0382] In the evaluation of injection molding performance in the examples and comparative examples, when a 2mm sheet was formed using an EC60N injection molding machine manufactured by Toshiba Machine Co., Ltd., under conditions of barrel temperature of 210°C, mold temperature of 45°C, and injection pressure of 45MPa, the following criteria were used for evaluation.

[0383] 〇: Able to form without problems

[0384] Insufficient fill:

[0385] (18) Formability (number of times the material is drawn)

[0386] The evaluation method for the number of string defects used in this embodiment and comparative example is based on whether string defects can be visually observed at the bottom of the molded product when a cylindrical vertical container is molded using an injection blow molding machine. The injection blow molding machine used is an SG125NP manufactured by Sumitomo Heavy Industries, Ltd. Molding is performed under conditions of 240°C barrel and hot runner temperature and 50°C mold temperature. The number of string defects observed was evaluated by confirming 140 molded containers with a volume of 10 injections.

[0387] (19) Formability (number of blow molding defects)

[0388] The evaluation method for the number of blow molding defects used in this embodiment and comparative example is based on whether the preform formed by injection molding detaches from the mold when molding a cylindrical vertical container using an injection blow molding machine. The injection blow molding machine used is an SG125NP manufactured by Sumitomo Heavy Industries, Ltd. Molding is performed under the conditions of a barrel temperature of 240°C, a hot runner temperature of 50°C, and a mold temperature of 50°C. If it can be confirmed that the molded preform adheres to the mold and cannot completely detach, it is counted as one defect, and the number of demolding defects is evaluated based on a total of 100 molding cycles. When the number of blow molding defects exceeds 10, productivity decreases; therefore, 10 or fewer defects are considered acceptable.

[0389] (20) Molding properties (mold contamination)

[0390] (20-1) Mold contamination during injection molding

[0391] When injection-molded sheets were produced at 220°C according to JIS K 7152 using the styrene resin compositions obtained in the Examples and Comparative Examples, mold contamination was evaluated using the number of injections from the end of continuous molding until adhesion was confirmed on the mold as an indicator. When the number of injections until adhesion was confirmed on the mold was less than 100, the mold cleaning frequency increased and the productivity decreased; therefore, a number of injections above 100 was considered acceptable.

[0392] (20-2) Mold contamination during injection blow molding

[0393] The evaluation method for mold contamination used in the examples and comparative examples evaluates the number of injections required until contaminants are visually confirmed on the mold when molding cylindrical vertical containers using an injection blow molding machine. The injection blow molding machine used is an SG125NP manufactured by Sumitomo Heavy Industries, Ltd. Molding is performed at a barrel and hot runner temperature of 240°C and a mold temperature of 50°C. Mold contaminants are checked every 5 injections until 150 injections are completed. If mold contaminants are confirmed after fewer than 100 injections, mold maintenance requires time and productivity decreases; therefore, 100 or more injections are considered acceptable.

[0394] (21) Determination of total transmittance

[0395] (I) Conditions for preparing the test piece

[0396] Using a mold for flat panel molding, the styrene resin compositions of the obtained examples and comparative examples were injection molded under the following conditions to produce a flat panel with a thickness of 2 mm, thereby producing a sheet body.

[0397] Molding machine: EC60N manufactured by Toshiba Machine Co., Ltd.

[0398] Barrel temperature: 220℃

[0399] Injection pressure: 45 MPa, Injection time: 10 seconds

[0400] Cooling time: 15 seconds, mold temperature: 45℃

[0401] (II) Conditions for determining total transmittance

[0402] The total transmittance (%) of the test sheet prepared above was determined according to JIS K7361-1.

[0403] (22) Thickness determination of biaxial tensile sheet

[0404] Using a 25mmφ single-screw extruder manufactured by Soken Co., Ltd., sheets with a thickness of 0.95mm to 1.05mm were produced from the styrene-based resin compositions manufactured in the Examples and Comparative Examples. Sheets of 8cm × 8cm size were cut from the produced sheets. Biaxially stretched sheets were then produced by simultaneously biaxially stretching the cut sheets using a biaxial stretching apparatus (EX6-S1) manufactured by Toyo Seiki Co., Ltd. under the following conditions. The thickness of the stretched sheets was measured using a micrometer.

[0405] Tensile temperature: Vicat softening temperature +20℃

[0406] Stretching speed: 170% / minute

[0407] Stretch ratio: 2.0 times

[0408] (23) Determination of impact strength (kgf·cm) of biaxial tensile sheet

[0409] The impact strength of the sheet produced by the method described in (22) above was determined using a membrane impact tester (A121807502) manufactured by Toyo Seiki Co., Ltd.

[0410] (24) Evaluation of the appearance of the film (2)

[0411] Using a 25mmφ single-screw sheet extruder manufactured by Soken Co., Ltd., sheets with a thickness of 0.3mm were produced. The number of foreign objects, bubbles, transparent or opaque attachments with an average diameter of 1mm or more within 5m of the sheet (major diameter + minor diameter) / 2 was counted.

[0412] (25) Thickness uniformity of biaxial stretch sheets

[0413] As one of the indicators of formability for biaxially stretched sheets, the thickness uniformity of biaxially stretched sheets is evaluated by the following methods.

[0414] Thickness was measured using a micrometer at nine intersection points on the film prepared by the method described in (22) above, where three straight lines were drawn in a grid pattern at 5 cm intervals in both the longitudinal and transverse directions. The same thickness measurement was performed on three films, and the thickness uniformity of the film was evaluated by the number of points outside the range of 0.23 mm to 0.27 mm out of a total of 27 points.

[0415] "2. Raw materials"

[0416] The materials used in the embodiments and comparative examples are described below.

[0417] [Styrene-based resins (A)]

[0418] (Rubber-modified polystyrene resin (HIPS))

[0419] • A rubber-modified styrene resin (1) with an MFR of 3.0 was used (HIPS, manufactured by PS Japan Co., Ltd., HT478). The styrene resin (a) of the polymer matrix phase of the rubber-modified styrene resin (1) is polystyrene (Mw = 180,000), and the average particle size of the rubber-like polymer (a salami structure containing polystyrene) is 1.7 μm.

[0420] • A rubber-modified styrene resin (2) with an MFR of 2.3 was used (HIPS, manufactured by PS Japan Co., Ltd., 475D). The styrene resin (a) of the polymer matrix phase of the rubber-modified styrene resin (1) was polystyrene (Mw = 220,000), and the average particle size of the rubber-like polymer (a salami structure containing polystyrene) was 2.3 μm.

[0421] (Butadiene rubber)

[0422] • Polybutadiene rubber (manufactured by Asahi Kasei Chemicals Co., Ltd., Diene 55), Polybutadiene rubber UBEPOL BR (manufactured by UBE Elastomer Co., Ltd., BR15HB)

[0423] [Biomass plasticizer (B)]

[0424] (Modified vegetable oil)

[0425] • Epoxidized soybean oil (product name "Newcizer 510R" (manufactured by Nippon Oil Co., Ltd.), weight-average molecular weight (Mw = 1500), biomass carbon ratio (pMC%) 100%, melting point: 5℃, SP value (calculated using the Hansen method, representing the distance from the origin in a three-component coordinate system of dispersion force (δD), polarity (δP), and hydrogen bonding (δH): 9.0 (cal / cm³) 3 ) 1 / 2 ), Epoxy modification rate: 5 mmol / g

[0426] • Epoxidized linseed oil (1) (Product name "Newsizer 512" (manufactured by Nippon Oil Co., Ltd.), weight-average molecular weight (Mw = 1500), biomass carbon ratio (pMC%) 100%, melting point: 5℃) SP value (calculated using the Hansen method, representing the distance from the origin in the three-component coordinate system of dispersion force (δD), polarity (δP), and hydrogen bonding (δH): 9.3 (cal / cm 3 ) 1 / 2 )), Epoxy modification rate: 8 mmol per 1g

[0427] • Epoxidized linseed oil (2) (Product name "O-180A" (ADEKA Co., Ltd.), weight-average molecular weight (Mw = 1500), biomass carbon ratio (pMC%) 100%, melting point: -2℃, SP value (calculated using the Hansen method, representing the distance from the origin in the three-component coordinate system of dispersion force (δD), polarity (δP), and hydrogen bonding (δH): 9.3 (cal / cm) 3 ) 1 / 2 )), Epoxy modification rate: 8 mmol per 1g

[0428] (Natural plant oil)

[0429] Palm oil (product name "multi-ace 20(S)" (Nissin Oligoo Group Co., Ltd.), weight-average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point: 22℃, SP value (calculated using the Hansen method, representing the distance from the origin in a three-component coordinate system of dispersion force (δD), polarity (δP), and hydrogen bonding (δH): 8.2 (cal / cm³) 3 ) 1 / 2 ))

[0430] • Soybean oil (product name "Soybean White Oil (S)" (Nissin Oligoo Group Co., Ltd.), weight average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point -8℃, SP value (calculated using the Hansen method, representing the distance from the origin in a three-component coordinate system of dispersion force (δD), polarity (δP), and hydrogen bonding (δH): 8.2 (cal / cm³) 3 ) 1 / 2 ))

[0431] • Hardened castor oil (product name "Hardened Castor Oil" (Ito Oil Co., Ltd.), weight-average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point 85℃, SP value (calculated using the Hansen method, representing the distance from the origin in a three-component coordinate system of dispersion force (δD), polarity (δP), and hydrogen bonding (δH): 10.1 (cal / cm³) 3 ) 1 / 2 ))

[0432] [other]

[0433] (Liquid paraffin)

[0434] • Liquid paraffin, product name "PS350S" (manufactured by Sanko Chemical Industry Co., Ltd.), weight average molecular weight (Mw = 250), biomass carbon ratio (pMC%) 0%, pour point: -12.5℃, SP value (literature value): 7.3 (cal / cm³) 3 ) 1 / 2

[0435] (Polylactic acid)

[0436] Polylactic acid (PLA), product name "LX175" (manufactured by Total Corbinion PLA), biomass carbon ratio (pMC%) 100%, melting point: 155℃, SP value (literature value): 10.3 (cal / cm³). 3 ) 1 / 2

[0437] 3. Examples and Comparative Examples

[0438] [Examples 1, 2a-2d, 3-5, and Comparative Examples 1-4]

[0439] Rubber-modified styrene resin (component (A)) and biomass plasticizer (component (B)) were dry-mixed according to the mixing ratios shown in Tables 3-1 and 3-2 below, and then extruded using a twin-screw compounding extruder (manufactured by Toshiba Machine Co., Ltd., TEM-26SS-12) at a resin temperature of 220°C, thereby producing styrene resin compositions of Examples 1, 2a-2d, 3-5 and Comparative Examples 1-4, respectively.

[0440] Then, for the obtained styrene-based resin compositions, the physical properties of the styrene-based resin compositions shown in Tables 3-1 and 3-2 were determined by the methods described in the “1. Determination and Evaluation Methods” section above.

[0441] Furthermore, the obtained styrene-based resin compositions were fed into a single-screw extruder, and extruded sheets with a thickness of 0.3 mm and a width of 125 mm were produced under conditions where the resin composition temperature was 200°C and the roll temperature was 90°C. Then, for the obtained extruded sheets, the sheet properties shown in Tables 3-1 and 3-2 were measured using the methods described in the "1. Measurement and Evaluation Methods" section above. It should be noted that regarding the sheet thickness (MD direction and TD direction), measurements were taken at 5 arbitrary locations using a micrometer, and the average value was taken as the sheet thickness.

[0442]

[0443]

[0444] [Example 6]

[0445] (Method for manufacturing styrene-based resin composition (PS-1))

[0446] A polymerization solution was prepared by mixing and dissolving 83.4% by weight of styrene, 1.8% by weight of polybutadiene rubber (Diene 35 manufactured by Asahi Kasei Chemicals Co., Ltd.), 10% by weight of ethylbenzene, 4.8% by weight of Newcizer 510R (manufactured by Nippon Oil Co., Ltd.), 0.016% by weight of 1,1-bis(tert-butylperoxy)cyclohexane, 0.10% by weight of α-methylstyrene dimer, and 0.1% by weight of antioxidant (Irganox 1076 (manufactured by BASF Japan Co., Ltd.)). This polymerization solution was continuously fed at a rate of 0.78 L / h into a 1.5 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones, with the temperature adjusted to 110 °C / 118 °C / 124 °C. The stirrer speed was set to 200 rpm. The reaction rate at the reactor outlet was 31%.

[0447] Next, the reaction solution was fed into a 1.5-liter laminar flow reactor-2, which was connected in series with the laminar flow reactor-1 and had a stirrer capable of controlling the temperature in three zones. The stirrer speed was set to 40 revolutions per minute, and the temperature was set to 129°C / 137°C / 147°C. Additionally, 0.04% by mass of α-methylstyrene dimer was added from the upper section of the laminar flow reactor-2. Next, the reaction solution was fed into a 1.5-liter laminar flow reactor-3, which was also equipped with a stirrer and had a temperature control in three zones. The stirrer speed was set to 10 revolutions per minute, and the temperature was set to 152°C / 156°C / 160°C.

[0448] A styrene-based resin composition (PS-1) was manufactured by devolatilizing a polymer solution continuously discharged from a polymerization reactor (laminar flow reactor-3) under reduced pressure of 0.8 kPa using an extruder equipped with a vacuum exhaust port. The resulting solution was then granulated. It should be noted that the extruder temperature was set to 230°C. Furthermore, the polymer matrix phase of the styrene-based resin composition (PS-1) contains polystyrene with an SP value of 8.6 (cal / cm³). 3 ) 1 / 2 The physical properties of the obtained styrene resin composition (PS-1) shown in Table 4 were determined by the methods described in the “1. Determination and Evaluation Methods” section above.

[0449] [Examples 7-21, 23, 24]

[0450] <Preparation of Styrene-based Resin Compositions (PS-2) to (PS-19)>

[0451] Except for changes in polymerization conditions as shown in Tables 4 and 5, styrene resin compositions (PS-2) to (PS-16), (PS-18), and (PS-19) were manufactured in the same manner as styrene resin composition (PS-1). The physical properties of the styrene resin compositions shown in Tables 6 and 7 were determined by the methods described in the “1. Determination and Evaluation Methods” section above.

[0452] [Example 22]

[0453] <Preparation of Styrene-based Resin Composition (PS-17)>

[0454] Except for changes in polymerization conditions as shown in Tables 4 and 5, a rubber-modified styrene resin (A-17) was manufactured in the same manner as the styrene resin composition (PS-1). Then, the rubber-modified styrene resin (component A) and biomass plasticizer (component B) were dry-blended in the proportions shown in Table 7 below (epoxidized soybean oil (product name Newcizer 510R, manufactured by Nippon Oil Co., Ltd.) was added to the rubber-modified styrene resin (A-17), and the content of epoxidized soybean oil was 6% by mass relative to the total styrene resin composition (PS-1). The mixture was then extruded using a twin-screw compounding extruder (manufactured by Toshiba Machine Co., Ltd., TEM-26SS-12) at a resin temperature of 220°C to manufacture the styrene resin composition (PS-17). The physical properties of the styrene resin compositions shown in Table 7 were determined by the methods described in the “1. Determination and Evaluation Methods” section above.

[0455] [Comparative Examples 5-6]

[0456] <Preparation of styrene-based resin compositions (PS-20) to (PS-21)>

[0457] Except for changes in polymerization conditions as shown in Tables 4 and 5, styrene resin compositions (PS-20) to (PS-21) were manufactured in the same manner as styrene resin composition (PS-1). The physical properties of the styrene resin compositions shown in Table 7 were determined by the methods described in the “1. Determination and Evaluation Methods” section above.

[0458] [Comparative Example 7]

[0459] <Preparation of Styrene-based Resin Composition (PS-22)>

[0460] For the styrene resin composition (PS-22), the polylactic acid (product name: LX175, manufactured by Total Corbinion PLA) was dry-mixed with the aforementioned rubber-modified styrene resin (A-17) prepared using the raw materials shown in Table 5 and manufactured in a laminar flow reactor, with the polylactic acid content being 6% by mass relative to the total styrene resin composition (PS-22). The mixture was then extruded using a twin-screw compounding extruder (manufactured by Toshiba Machine Co., Ltd., TEM-26SS-12) at a resin temperature of 220°C, thereby producing the styrene resin composition (PS-22). The physical properties of the styrene resin compositions shown in Table 7 were determined by the methods described in the "1. Determination and Evaluation Methods" section above.

[0461]

[0462]

[0463]

[0464]

[0465] [Example 25]

[0466] (Method for manufacturing the styrene resin composition of Example 25 using resin composition (PS-23))

[0467] A polymerization solution was prepared by mixing and dissolving 92.1% by mass styrene, 6.0% by mass ethylbenzene, 3.2% by mass polybutadiene rubber (Diene 55 manufactured by Asahi Kasei Chemicals Co., Ltd.), and 0.8% by mass multi-ace20(S) (manufactured by Nissin Oligoo Group Co., Ltd.). This polymerization solution was continuously fed at a rate of 3.24 L / h into a 6.2 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones. The temperature was adjusted to 121°C / 125°C / 131°C. The stirrer speed was set to 70 rpm. The reaction rate at the reactor outlet was 26%.

[0468] Next, the reaction mixture was fed into a 6.2-liter laminar flow reactor-2, which was connected in series with the laminar flow reactor-1 and had a stirrer capable of controlling the temperature in three zones. The stirrer speed was set to 40 revolutions per minute, and the temperature was set to 136°C / 140°C / 144°C. Then, the reaction mixture was fed into a 6.2-liter laminar flow reactor-3, which was also equipped with a stirrer and had a temperature control in three zones. The stirrer speed was set to 10 revolutions per minute, and the temperature was set to 146°C / 148°C / 150°C.

[0469] The polymer solution continuously discharged from the polymerization reactor (laminar flow reactor-3) was devolatilized under reduced pressure of 0.8 kPa using an extruder with a vacuum exhaust port heated to 230°C, and then granulated to produce the composition (PS-23).

[0470] Next, a 3:1 mixture of stearic acid and calcium stearate, used as a release agent (a higher fatty acid compound), was incorporated into the composition (PS-23) at 0.25% by mass relative to the total styrene resin composition, and the mixture was compounded using an extruder to produce the styrene resin composition of Example 25. The physical properties of the styrene resin compositions shown in Table 9-1 were then determined using the methods described in the “1. Determination and Evaluation Methods” section above.

[0471] It should be noted that the polymer matrix phase of the composition (PS-23) contains polystyrene as a styrene polymer (a-1), and the SP value of this polystyrene is 8.6 (cal / cm). 3 ) 1 / 2 .

[0472] [Examples 26-60]

[0473] (Methods for manufacturing styrene-based resin compositions of Examples 26-60)

[0474] Except for changes in polymerization conditions as shown in Tables 8-1 to 8-3, compositions (PS-24) to (PS-57) were manufactured in the same manner as composition (PS-23), and then a specified amount of a 3:1 mixture of stearic acid and calcium stearate was added to produce the styrene resin compositions of Examples 26 to 59. Furthermore, the styrene resin composition of Example 60 (composition (PS-66)) was manufactured as follows: after manufacturing composition (PS-58), it was compounded with palm oil content of 3% by mass and the content of a 3:1 mixture of stearic acid and calcium stearate (as a release agent, a higher fatty acid compound) of 0.25% by mass relative to the total styrene resin composition, and then compounded using an extruder. The physical properties of the styrene resin compositions shown in Tables 9-1 to 9-3 were then determined using the methods described in the “1. Determination and Evaluation Methods” section above.

[0475] [Comparative Examples 8-16]

[0476] <Methods for manufacturing styrene-based resin compositions of Comparative Examples 8-16>

[0477] Except for changing the polymerization conditions as shown in Table 8-3, compositions (PS-58) to (PS-65) were manufactured in the same manner as the above composition (PS-23).

[0478] The styrene resin composition of Comparative Example 14 (=Composition (PS-67)) was prepared by adding the polylactic acid and the 3:1 mixture of stearic acid and calcium stearate to composition (PS-58) in such a manner that the content of polylactic acid (PLA) was 3% by mass relative to the total styrene resin composition and the content of the 3:1 mixture of stearic acid and calcium stearate as a release agent was as described in Tables 9-4, and then mixing the mixture using a twin-screw extruder.

[0479] Then, the physical properties of the styrene resin compositions shown in Table 9-4 were determined by the methods described in the “1. Determination and Evaluation Methods” section above.

[0480]

[0481]

[0482]

[0483]

[0484]

[0485]

[0486]

[0487] [Example 61]

[0488] (Method for manufacturing styrene-based resin composition (PS-68))

[0489] A polymerization solution was prepared by mixing and dissolving 92.1% by mass styrene, 5.5% by mass ethylbenzene, and 0.4% by mass multi-ace20(S) (manufactured by Nissin Oligoo Group Co., Ltd.). This polymerization solution was continuously fed at a rate of 0.78 L / h into a 1.5 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones, with the temperature adjusted to 120°C / 125°C / 129°C. The stirrer speed was set to 80 rpm. The reaction rate at the reactor outlet was 30%.

[0490] Next, the reaction solution was fed into a 1.5-liter laminar flow reactor-2, which was connected in series with the laminar flow reactor-1 and had a stirrer capable of controlling the temperature in three zones. The stirrer speed was set to 40 revolutions per minute, and the temperature was set to 131°C / 133°C / 135°C. Then, the reaction solution was fed into a 1.5-liter laminar flow reactor-3, which was also equipped with a stirrer and had a temperature control in three zones. The stirrer speed was set to 10 revolutions per minute, and the temperature was set to 145°C / 148°C / 150°C.

[0491] A styrene-based resin composition (PS-68) was manufactured by devolatilizing a polymer solution continuously discharged from a polymerization reactor (laminar flow reactor-3) under reduced pressure of 0.8 kPa using an extruder equipped with a vacuum exhaust port, followed by granulation. It should be noted that the extruder temperature was set to 220°C. Furthermore, the polymer matrix phase of the styrene-based resin composition (PS-68) contains polystyrene with an SP value of 8.6 (cal / cm³). 3 ) 1 / 2 Then, the styrene resin composition (PS-68) of Example 61 was subjected to the various evaluations described above. The evaluation results are shown in Table 11-1.

[0492] [Examples 62-77]

[0493] <Styrene-based resin compositions (PS-69) to (PS-82) and (PS-88) to (PS-89)>

[0494] Except for the changes in polymerization conditions shown in Tables 10-1 and 10-2 below, styrene resin compositions (PS-69) to (PS-82) were manufactured in the same manner as styrene resin composition (PS-68). Furthermore, styrene resin composition (PS-88) was prepared by adding palm oil to styrene resin composition (PS-83) (GPPS without plasticizer) at a rate of 1% by mass relative to the total styrene resin composition (PS-88), and then compounding using a twin-screw extruder. Similarly, styrene resin composition (PS-89) was prepared by adding palm oil to KIBISAN (registered trademark) PN-117C (CHI-MEI product) at a rate of 1% by mass relative to the total styrene resin composition (PS-89), and then compounding using a twin-screw extruder. The styrene resin compositions of Examples 62 to 77 were then subjected to the various evaluations described above. The evaluation results are shown in Tables 11-1 and 11-2.

[0495] [Comparative Examples 17-22]

[0496] <Styrene-based resin compositions (PS-83) to (PS-87) and (PS-90)>

[0497] Except for the changes in polymerization conditions shown in Table 10-2 below, styrene resin compositions (PS-83) to (PS-87) were manufactured in the same manner as styrene resin composition (PS-68).

[0498] The styrene-based resin composition (PS-90) was prepared as follows: polylactic acid (PLA) was added to the styrene-based resin composition (PS-83) at a content of 2% by mass relative to the total styrene-based resin composition (PS-90), and the mixture was compounded using a twin-screw extruder. Then, the styrene-based resin compositions of Comparative Examples 17-22 were subjected to the various evaluations described above. The evaluation results are shown in Tables 11-3.

[0499]

[0500]

[0501]

[0502]

[0503]

[0504] [Method for manufacturing styrene-based resin compositions]

[0505] [Example 78]

[0506] (Method for manufacturing styrene-based resin composition (PS-91))

[0507] A polymerization solution was prepared by mixing and dissolving 92.1% by mass styrene, 5.5% by mass ethylbenzene, and 2.4% by mass multi-ace20(S) (manufactured by Nissin Oligoo Group Co., Ltd.). This polymerization solution was continuously fed at a rate of 0.78 L / h into a 1.5 L laminar flow reactor-1 equipped with a stirrer and capable of temperature control in three zones, with the temperature adjusted to 120°C / 125°C / 129°C. The stirrer speed was set to 80 rpm. The reaction rate at the reactor outlet was 30%.

[0508] Next, the reaction solution is fed into a 1.5-liter laminar flow reactor-2, which is connected in series with the laminar flow reactor-1 and has a stirrer capable of controlling the temperature in three zones. The stirrer speed is set to 40 revolutions per minute, and the temperature is set to 131°C / 133°C / 135°C. Then, the reaction solution is fed into a 1.5-liter laminar flow reactor-3, which is also equipped with a stirrer and can control the temperature in three zones. The stirrer speed is set to 10 revolutions per minute, and the temperature is set to 145°C / 148°C / 150°C (refer to Table 12-1).

[0509] A styrene-based resin composition (PS-91) was manufactured by devolatilizing a polymer solution continuously discharged from a polymerization reactor (laminar flow reactor-3) under reduced pressure of 0.8 kPa using an extruder equipped with a vacuum exhaust port, followed by granulation. It should be noted that the extruder temperature was set to 220°C. Furthermore, the polymer matrix phase of the styrene-based resin composition (PS-91) contains polystyrene with an SP value of 8.6 (cal / cm³). 3 ) 1 / 2 Then, the styrene composition of Example 78 was subjected to the various evaluations described above. The evaluation results are shown in Table 13-1.

[0510] [Examples 79-93]

[0511] <Styrene-based resin compositions (PS-92) to (PS-104) and (PS-113) to (PS-114)>

[0512] Except for the changes in polymerization conditions shown in Tables 12-1 and 12-2, styrene resin compositions (PS-92) to (PS-104) were manufactured in the same manner as styrene resin composition (PS-91). Styrene resin composition (PS-113) was prepared by adding palm oil to styrene resin composition (PS-105) (GPPS without biomass plasticizer) described later, at a palm oil content of 3% by mass relative to the total content of the styrene resin composition (PS-113), and then compounding it using a twin-screw extruder. Styrene resin composition (PS-114) was prepared by adding palm oil to styrene-acrylonitrile (KIBISAN (registered trademark) PN-117C (CHI-MEI product)) at a palm oil content of 3% by mass relative to the total content of the styrene resin composition (PS-114), and then compounding it using a twin-screw extruder. The styrene compositions of Examples 79 to 93 were then subjected to the various evaluations described above. The evaluation results are shown in Tables 13-1 to 13-2.

[0513] [Comparative Examples 23-31]

[0514] <Styrene-based resin compositions (PS-105) to (PS-112) and (PS-115)>

[0515] Except for the changes in polymerization conditions shown in Table 12-2, styrene resin compositions (PS-105) to (PS-112) and (PS-115) were manufactured in the same manner as styrene resin composition (PS-90). When manufacturing PS-22, the polybutadiene rubber used was Diene 55 manufactured by Asahi Kasei Chemicals Co., Ltd. The styrene resin composition (PS-115) was prepared by adding polylactic acid (PLA) to the styrene resin composition (PS-105) at a content of 3% by mass relative to the total styrene resin composition (PS-115), and then compounding using a twin-screw extruder. The styrene compositions of Comparative Examples 23 to 31 were then subjected to the various evaluations described above. The evaluation results are shown in Table 13-3.

[0516]

[0517]

[0518]

[0519]

[0520]

[0521] The contents of all documents described in this specification and applications that form the basis of this application (Japanese Patent Application 2020-198999 (filed November 30, 2020), Japanese Patent Application 2021-130990 (filed August 10, 2021), Japanese Patent Application 2021-166317 (filed October 8, 2021), Japanese Patent Application 2021-166318 (filed October 8, 2021) and Japanese Patent Application 2021-190613 (filed November 24, 2021) are incorporated herein by reference.

[0522] Industrial practicality

[0523] This invention provides a styrene-based resin composition with excellent environmental impact reduction and mechanical strength, and a molded article comprising the styrene-based resin composition. The molded article obtained from the styrene-based resin composition can be suitably used in food packaging containers, groceries, toys, appliance parts, industrial materials, etc.

Claims

1. A styrenic resin composition, wherein, The styrene-based resin composition contains: 82.5% to 99.9% by mass of styrene-based resins (A) containing styrene monomer units, and Biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, ranging from 0.1% to 15% by mass. The styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase and rubbery polymer particles (a-2), wherein the polymer matrix phase is composed of a styrene polymer (a-1) containing the styrene monomer units. The rubber-modified styrene resin contains 3.1% to 6.5% by mass of rubber-like polymer. The biomass plasticizer (B) has an SP value of 9.2 (cal / cm³). 3 ) 1 / 2 the following, The melt flow rate of the styrene-based resin composition, measured at 200°C and 49N load, was 3.0 g / 10 min to 13.0 g / 10 min.

2. The styrenic resin composition of claim 1, wherein, The styrene-based resin composition contains: 90%–99.9% by mass of styrene-based resins (A) containing styrene monomer units, and Biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, ranging from 0.1% to 10% by mass.

3. The styrenic resin composition of claim 1, wherein, The styrene-based resin composition contains: 85%–99.0% by mass of styrene-based resins (A) containing styrene monomer units, and Biomass plasticizer (B) with a biomass carbon ratio (pMC%) of 10% or more, ranging from 1.0% to 15% by mass.

4. The styrenic resin composition according to any one of claims 1 to 3, wherein, The biomass plasticizer (B) has a biomass carbon ratio (pMC%) of 50% or more.

5. The styrenic resin composition according to any one of claims 1 to 3, wherein, The biomass plasticizer (B) has a biomass carbon ratio (pMC%) of 75% or more.

6. The styrenic resin composition according to any one of claims 1 to 3, wherein, 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 less than 2.5 (cal / cm). 3 ) 1 / 2 .

7. The styrenic resin composition of claim 6, wherein, 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 less than 1.0 (cal / cm). 3 ) 1 / 2 .

8. The styrenic resin composition according to any one of claims 1 to 3, wherein, The SP value of the biomass plasticizer (B) is 7.4 (cal / cm³). 3 ) 1 / 2 ~9.2 (cal / cm) 3 ) 1 / 2 .

9. The styrenic resin composition of claim 8, wherein, The SP value of the biomass plasticizer (B) is 7.8 (cal / cm³). 3 ) 1 / 2 ~9.2 (cal / cm) 3 ) 1 / 2 .

10. The styrenic resin composition according to any one of claims 1 to 3, wherein, The SP value of the styrene polymer (a-1) is 7 (cal / cm). 3 ) 1 / 2 ~11 (cal / cm) 3 ) 1 / 2 .

11. The styrenic resin composition of claim 10, wherein, The SP value of the styrenic polymer (a-1) is 8.0 (cal / cm 3 ) 1 / 2 ~ 9.0 (cal / cm 3 ) 1 / 2 .

12. The styrenic resin composition of claim 6, wherein, The styrene polymer (a-1) is one or more selected from the group consisting of polystyrene and styrene copolymer resins.

13. The styrenic resin composition of claim 12, wherein, The polystyrene is a homopolymer obtained by polymerizing styrene monomers.

14. The styrenic resin composition of claim 12, wherein, The styrene copolymer resin is a resin containing styrene monomer units and vinyl monomer units.

15. The styrenic resin composition of claim 14, wherein, The styrene copolymer resin is a resin comprising one or more monomer units selected from the group consisting of styrene monomer units and unsaturated carboxylic acid monomer units and unsaturated carboxylic acid ester monomer units.

16. The styrenic resin composition according to claim 14 or 15, wherein, The styrene copolymer resin is a resin containing styrene monomer units and unsaturated carboxylic acid ester monomer units.

17. The styrenic resin composition according to any one of claims 13 to 15, wherein, The styrene monomers are selected from one or more of the group consisting of styrene, α-methylstyrene, α-methyl-p-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, tert-butylstyrene, bromostyrene, and indene.

18. The styrenic resin composition of claim 15, wherein, The unsaturated carboxylic acid ester monomer is selected from one or more of the group consisting of methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, and cyclohexyl methacrylate.

19. The styrenic resin composition according to any one of claims 12 to 15, wherein, The styrene-based copolymer resin is a styrene-(meth)acrylate copolymer, a styrene-(meth)acrylate ethyl acrylate copolymer, a styrene-(meth)acrylate propyl acrylate copolymer, or a styrene-(meth)acrylate butyl acrylate copolymer or a styrene-(meth)acrylate methyl acrylate-(meth)acrylate butyl acrylate copolymer.

20. The styrenic resin composition of claim 6, wherein, The weight-average molecular weight (Mw) of the styrene polymer (a-1) is 100,000 to 300,000.

21. The styrenic resin composition of claim 20, wherein, The weight-average molecular weight (Mw) of the styrene polymer (a-1) is 120,000 to 250,000.

22. The styrenic resin composition of claim 6, wherein, The rubber-like polymer particles (a-2) are made of one or more materials selected from the group consisting of polybutadiene, polybutadiene containing polystyrene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, and acrylonitrile-butadiene copolymer.

23. The styrenic resin composition of claim 6, wherein, The content of the rubbery polymer particles (a-2) is 3% to 36% by mass relative to the total styrene resin composition (100% by mass).

24. The styrenic resin composition of claim 6, wherein, The content of the rubbery polymer particles (a-2) is 10% to 30% by mass relative to the total styrene resin composition (100% by mass).

25. The styrenic resin composition of claim 6, wherein, The rubber-like polymer particles (a-2) contained in the rubber-modified styrene resin have an average particle size of 0.8 μm to 3.5 μm.

26. The styrenic resin composition of claim 6, wherein, The specific viscosity of the styrene polymer (a-1) is in the range of 0.50 dL / g to 0.85 dL / g.

27. The styrenic resin composition according to any one of claims 1 to 3, wherein, The styrene resin (A) is a rubber-modified styrene resin containing a polymer matrix phase composed of styrene polymers (a-1) and rubber-like polymer particles (a-2). The content of the rubber-like polymer particles (a-2) is 3% to 36% by mass relative to the total amount (100% by mass) of the styrene resin (A), and the average particle size of the rubber-like polymer particles (a-2) is 0.3 μm to 5.0 μm.

28. The styrenic resin composition of claim 1, wherein, The average particle size of the rubbery polymer particles (a-2) is 2.1 μm to 7.0 μm.

29. The styrenic resin composition of claim 1, wherein, The rubbery polymer particles (a-2) are salami sausage structures.

30. The styrenic resin composition according to any one of claims 1 to 3, wherein, The styrene resin (A) is a rubber-modified styrene resin containing a styrene polymer (a-1) comprising styrene monomer units and rubber-like polymer particles (a-2) with an average particle size of 0.9 μm to 7.0 μm. The styrene-based resin composition also contains higher fatty acid compounds (C), and Relative to the styrene-based resin composition as a whole (100% by mass), The content of the rubbery polymer particles (a-2) is 10% to 30% by mass, the content of the biomass plasticizer (B) is 0.1% to 15% by mass, and the content of the higher fatty acid compound is 0.02% to 2.5% by mass.

31. The styrene-based resin composition of claim 30, wherein, The higher fatty acid compound (C) is one or more selected from the group consisting of higher fatty acids and metal salts of higher fatty acids.

32. The styrene-based resin composition of claim 31, wherein, The higher fatty acids are saturated straight-chain carboxylic acids with 12 to 22 carbon atoms.

33. The styrene-based resin composition according to claim 31 or 32, wherein, The higher fatty acids are stearic acid, lauric acid, myristic acid, palmitic acid, or behenic acid.

34. The styrene-based resin composition of claim 31, wherein, The metal salt of the higher fatty acid is a metal salt of a saturated straight-chain carboxylic acid with 12 to 22 carbon atoms.

35. The styrene-based resin composition of claim 34, wherein, The metal is zinc, calcium, magnesium, aluminum, barium, lead, lithium, potassium, or sodium.

36. The styrene resin composition according to any one of claims 1 to 3, wherein, The content of the styrene monomer units contained in the styrene resin (A) is 50% by mass or more relative to the total amount (100% by mass) of the styrene resin (A).

37. The styrene resin composition according to any one of claims 1 to 3, wherein, The content of toluene-insoluble components in the styrene-based resin composition is less than 3% by mass.

38. The styrene resin composition according to any one of claims 1 to 3, wherein, The content of the biomass plasticizer (B) is greater than or equal to 0.1% by mass and less than 3.0% by mass relative to the total amount (100% by mass) of the styrene resin composition.

39. The styrene resin composition according to any one of claims 1 to 3, wherein, The content of the biomass plasticizer (B) is 3.0% to 15% by mass relative to the total amount (100% by mass) of the styrene resin composition.

40. The styrene resin composition according to any one of claims 1 to 3, wherein, The content of the biomass plasticizer (B) is greater than or equal to 0.1% by mass and less than 3.0% by mass, and the Vicat softening temperature of the styrene resin composition is above 90°C.

41. The styrene resin composition according to any one of claims 1 to 3, wherein, The biomass plasticizer (B) is a natural vegetable oil, a 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 and modified vegetable oil and mineral oil, or a polyester plasticizer.

42. The styrene resin composition according to any one of claims 1 to 3, wherein, The biomass plasticizer (B) is palm oil, epoxidized soybean oil, epoxidized linseed oil, hardened castor oil, polyethylene oxide castor oil, polyethylene oxide hardened castor oil, oleic acid ester or laurate ester.

43. The styrene resin composition according to any one of claims 1 to 3, wherein, The biomass plasticizer (B) has a weight-average molecular weight (Mw) of 200 to 7500.

44. The styrene resin composition according to any one of claims 1 to 3, wherein, The melting point of the biomass plasticizer (B) is -30℃ to 80℃.

45. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The styrene-based resin composition was used for injection blow molding.

46. ​​The styrene resin composition according to any one of claims 1 to 3, wherein, The melt flow rate of the styrene-based resin composition, measured at 200°C and 49N load, was 3.0 g / 10 min to 7.0 g / 10 min.

47. The styrene resin composition according to any one of claims 1 to 3, wherein, The Vicat softening temperature of the styrene-based resin composition is 50°C to 105°C.

48. The styrene resin composition according to any one of claims 1 to 3, wherein, The Vicat softening temperature of the styrene-based resin composition is 90°C to 105°C.

49. The styrene resin composition according to any one of claims 1 to 3, wherein, The Vicat softening temperature of the styrene-based resin composition is 75°C to 100°C.

50. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The swelling index of styrene-based resin compositions containing rubber-like polymer particles (a-2) is 8.5 to 14.

51. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The styrene-based resin composition contains only styrene-based resin (A), biomass plasticizer (B), and optional additives, wherein the styrene-based resin (A), biomass plasticizer (B), and optional additives constitute 95% to 100% by mass relative to the total amount of the styrene-based resin composition.

52. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The styrene-based resin composition contains only styrene-based resin (A), biomass plasticizer (B), and optional additives, wherein the styrene-based resin (A), biomass plasticizer (B), and optional additives constitute 98% to 100% by mass relative to the total amount of the styrene-based resin composition.

53. The styrene resin composition according to any one of claims 1 to 3, wherein, The styrene-based resin composition comprises only styrene-based resin (A), biomass plasticizer (B), higher fatty acid compound (C), and optional additives, wherein the styrene-based resin (A), biomass plasticizer (B), higher fatty acid compound (C), and optional additives constitute 95% to 100% by mass relative to the total amount of the styrene-based resin composition.

54. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The styrene resin composition comprises only styrene resin (A), biomass plasticizer (B), higher fatty acid compound (C), and optional additives, wherein the styrene resin (A), biomass plasticizer (B), higher fatty acid compound (C), and optional additives constitute 98% to 100% by mass relative to the total amount of the styrene resin composition.

55. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The content of halogenated flame retardant is less than 1% by mass relative to the total amount (100% by mass) of the styrene resin composition.

56. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The metal content is less than 0.5% by mass relative to the total amount (100% by mass) of the styrene-based resin composition.

57. The styrene-based resin composition according to any one of claims 1 to 3, wherein, The content of hydroxyl compounds is less than 1% by mass relative to the total amount (100% by mass) of the styrene-based resin composition.

58. An injection blow molded article, wherein, The injection blow molded article is obtained by injection blow molding the styrene-based resin composition according to any one of claims 1 to 57.

59. An injection-molded article, wherein, The injection-molded article is obtained by injection molding the styrene-based resin composition according to any one of claims 1 to 57.

60. A type of sheet, wherein, The sheet comprises the styrene-based resin composition according to any one of claims 1 to 57.

61. The sheet as claimed in claim 60, wherein, The sheet is a biaxially stretched sheet.

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