Styrene resin composition and injection blow molded article using the same

Abstract

To provide a rubber-modified styrene-based resin composition suitable for injection blow molding, which reduces an environmental load by use of biomass raw materials, has excellent injection blow moldability, causes little mold staining during molding, and, when molded, has high impact strength of the neck region and buckling strength.SOLUTION: Provided is a styrene-based resin composition, comprising a styrene-based polymer (A-1); a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more; a higher fatty acid compound (C); and rubbery polymer particles (A-2) having an average particle diameter of 0.9-7.0 μm. Relative to the whole styrene-based resin composition (100 mass%), a content of the rubbery polymer particles (A-2) is 10-30 mass%, a content of the biomass plasticizer is 0.1-15 mass%, and a content of the higher fatty acid compound is 0.02-2.5 mass%.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a styrenic resin composition suitable for injection blow molding. More specifically, it is a styrenic resin composition containing a biomass plasticizer with a biomass content of 10% or more for the purpose of reducing environmental impact, and capable of efficiently producing a hollow container with excellent strength by injection blow molding.

Background Art

[0002] Styrenic resins typified by rubber-modified styrenic resins are processed or molded into various forms for use in a wide variety of applications such as sundries, food packaging, and household appliances according to their moldability and mechanical strength. Among them, when processing or molding into a hollow container using a styrenic resin, injection blow molding, in which a deeper container is easier to mold and has high productivity, is widely used. Also, in injection blow molding, since only the mouth part of the hollow container can be made thick, it is suitable for manufacturing a hollow container with a heat-sealed mouth part. Also, from the perspective of reducing environmental impact, biomass raw materials have attracted attention, and the development of injection blow molding materials in which styrenic resins and naturally derived raw materials are combined has been underway. For example, Patent Document 1 discloses a styrenic resin composition containing a rubber-modified styrenic resin and polylactic acid and suitable for injection blow molding.

[0003] In recent years, in the technical field of injection blow molding, there has been a demand for the development of a molding material with excellent strength that can maintain a certain strength even when the container is thinned. However, thinning causes problems such as a decrease in the mouth impact and cracking during air transportation in a molding factory. Furthermore, thinning also causes a decrease in the buckling strength of the container, and problems such as deformation of the container when transporting beverages in the container and not being able to withstand the load occur. Therefore, a molding material with an excellent balance between mouth impact and buckling strength is required. Furthermore, from the perspective of improving the productivity of container molding, reduction of mold fouling is also required. For example, Patent Document 2 discloses a technology for a beverage container having excellent buckling strength and mouth strength. Also, for example, Patent Document 3 discloses a rubber-modified styrene-based resin composition for high-branched injection blow molding, and mentions a technology for reducing the total amount of residual styrene monomer and residual polymerization solvent and reducing mold fouling.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] The technology of the above Patent Document 1 examines a polymer alloy of a styrene-based resin and polylactic acid having a relatively high melting point and toughness among styrene-based resins and plant-derived biodegradable polymers. However, since the compatibility of polylactic acid with the styrene-based resin is very low, there is a problem that it is difficult to perform a product design that satisfies mechanical properties such as impact resistance or stretchability required in the hollow container market. Also, since polylactic acid is incompatible with the styrene-based resin, there is also a problem that it is difficult to recycle the hollow container breaking material.

[0006] The technology of Patent Document 2 above is examining a beverage container with excellent buckling strength and mouth strength. However, since a large amount of liquid paraffin is used, the volatile components generated during molding increase. As a result, it is conceivable that the mold contamination during molding deteriorates. Further, the technology of Patent Document 3 above is examining a molding material that is excellent in injection blow molding and has a small total amount of residual styrene monomer and residual polymerization solvent. However, since a large amount of white oil is used, the effect of reducing mold contamination is considered insufficient. Furthermore, in Patent Documents 2 and 3, biomass raw materials for reducing environmental impact are not used. Therefore, the technologies of Patent Documents 1 to 3 above do not examine technologies that are excellent in injection blow moldability, reduce mold contamination during molding, while maintaining high levels of mouth impact and buckling strength of the hollow container while using biomass raw materials. Therefore, the present invention provides a styrene resin composition suitable for injection blow molding that reduces environmental impact by using biomass raw materials, has high mouth impact strength and buckling strength when injection blow molded, and has little mold contamination during the molding.

Means for Solving the Problems

[0007] In view of the above problems, the present inventor conducted intensive research and repeated experiments. As a result, by using a styrene resin composition in which a rubber-modified styrene resin (A) containing a styrene polymer (A-1) and rubber-like polymer particles (A-2), a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more, and a higher fatty acid compound (C) are mixed at a specific ratio, it was found that the above problems can be solved, and the present invention has been completed. The present invention relates to a styrenic resin composition containing a rubber-modified styrenic polymer (A-1) and rubbery polymer particles (A-2), a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more, and a higher fatty acid compound (C). The styrenic resin composition contains 10 to 30% by mass of the rubbery polymer particles (A-2), 0.1 to 15.0% by mass of the biomass plasticizer (B), and 0.02 to 2.5% by mass of the higher fatty acid compound (C) serving as a mold release agent, based on the total amount of the styrenic resin composition.

Effect of the Invention

[0008] According to the present invention, it is possible to provide a styrenic resin composition that reduces the environmental load, is excellent in injection blow moldability, exhibits high mouth impact strength and buckling strength when injection blow molded, and has less mold fouling during the molding, and a hollow container molded article made of the styrenic resin composition.

Modes for Carrying Out the Invention

[0009] Hereinafter, embodiments of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. However, the present invention is not limited to the following description and can be variously modified and implemented within the scope of the gist.

[0010] [Styrenic Resin Composition] The styrenic resin composition of the present embodiment contains a styrenic polymer (A-1), rubbery polymer particles (A-2) having an average particle diameter of 0.9 to 7.0 μm, a biomass plasticizer (B) having a biomass carbon ratio (pMC ratio) of 10% or more, and a higher fatty acid compound (C). And, based on the total amount of the styrenic resin composition, 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 15.0% by mass, and the content of the higher fatty acid compound (C) is 0.02 to 2.5% by mass. As a result, it is possible to provide a styrenic resin composition that reduces environmental impact, has high mouth impact strength and buckling strength during container molding, is excellent in injection blow molding, and has little mold fouling during molding. Further, the styrenic polymer (A-1) and the rubber-like polymer particles (A-2) can be blended into the styrenic resin composition of the present embodiment as a rubber-modified styrenic resin (A) containing the styrenic polymer (A-1) and the rubber-like polymer particles (A-2). The rubber-modified styrenic resin (A) blended into the styrenic resin composition of the present embodiment preferably contains a polymer matrix phase containing the styrenic polymer (A-1) and the rubber-like polymer particles (A-2) dispersed in the polymer matrix phase. Furthermore, the rubber-modified styrenic resin (A) containing 10 to 30% by mass of the rubber-like polymer particles (A-2) with respect to the rubber-modified styrenic resin (A) is preferably contained in an amount of 82.5 to 99.88% by mass with respect to the entire styrenic resin composition (100% by mass). Note that the higher fatty acid compound (C) can be contained as a mold release agent. In other words, the styrenic resin composition of the present embodiment preferably contains 82.5 to 99.88% by mass of the rubber-modified styrenic resin (A) and 0.1 to 15.0% by mass of the biomass plasticizer (B), and 0.02 to 2.5% by mass of the higher fatty acid compound (C) with respect to the entire styrenic resin composition (100% by mass). As a result, it is possible to provide a styrenic resin composition that reduces environmental impact, has high mouth impact strength and buckling strength during container molding, is excellent in injection blow molding, and has little mold fouling during molding.

[0011] <Rubber-modified styrenic resin (A) (hereinafter also referred to as component (A))> The rubber-modified styrenic resin (A) of the present embodiment essentially contains a styrenic polymer (A-1) and rubber-like polymer particles (A-2). And in the present embodiment, the rubber-modified styrene-based resin (A) may be one in which rubber-like polymer particles (referred to as rubber-like polymer particles (A-2)) are dispersed in a styrene-based polymer (A-1) as a polymer matrix phase. Further, the rubber-modified styrene-based resin (A) can be produced by polymerizing a styrene-based monomer in the presence of a rubber-like polymer. Therefore, the styrene-based resin composition in the present embodiment may contain the styrene-based polymer (A-1) and the rubber-like polymer particles (A-2) separately, or may contain the styrene-based polymer (A-1) and the rubber-like polymer particles (A-2) as the rubber-modified styrene-based resin (A). And in the present embodiment, the content of the rubber-modified styrene-based resin (A) can be 82.5 to 99.88% by mass with respect to the entire styrene-based resin composition (100% by mass). Further, the content of the rubber-modified styrene-based resin (A) can preferably be 83 to 99% by mass, more preferably 84 to 98% by mass, still more preferably 85 to 97% by mass, and even more preferably 86 to 96% by mass. Hereinafter, as an example of the styrene-based resin composition in the present embodiment, an embodiment using the rubber-modified styrene-based resin (A) will be described.

[0012] -Styrene-based polymer (A-1) and polymer matrix phase- In the present embodiment, the monomer constituting the styrene-based polymer (A-1) is preferably a styrene-based monomer (a) or a vinyl-based monomer (b) copolymerizable with a styrene-based compound. Among the monomers constituting the styrene-based polymer (A-1), the content of the styrene-based monomer (a) is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, still 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 can be determined from the integration ratio of the spectrum measured by a proton nuclear magnetic resonance ( 1 1H-NMR) measuring instrument. As the styrene monomer (a), in addition to styrene, for example, styrene derivatives such as α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene or bromostyrene and indene can be mentioned. Particularly, styrene is preferred. These styrene monomers can be used alone or in combination of two or more.

[0013] In this embodiment, the vinyl monomer (b) is not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, cyclohexyl (meth)acrylate, and the like. These unsaturated carboxylic acid ester monomers can be used alone or in combination of two or more.

[0014] In this embodiment, polystyrene is a homopolymer obtained by polymerizing the styrene monomer (a), and a generally available one can be appropriately selected and used. As the styrene monomer (a) constituting polystyrene, in addition to styrene, styrene derivatives such as α-methylstyrene, α-methyl-p-methylstyrene, ο-methylstyrene, m-methylstyrene, p-methylstyrene, vinyltoluene, ethylstyrene, isobutylstyrene, and t-butylstyrene or bromostyrene and indene can be mentioned. Particularly, styrene is preferred from an industrial perspective. These styrene monomers (a) can be used alone or in combination of two or more. Polystyrene does not exclude further containing monomer units other than the above styrene monomer (a) units as long as the effects of the present invention are not impaired, but typically consists of styrene monomer (a) units.

[0015] In this embodiment, the weight average molecular weight (Mw) of the styrenic polymer (A-1) is preferably from 100,000 to 300,000, more preferably from 120,000 to 260,000, still more preferably from 140,000 to 240,000, and even more preferably from 150,000 to 230,000. When the weight average molecular weight (Mw) is from 100,000 to 300,000, a resin excellent in the balance between mechanical strength and fluidity can be obtained, and the incorporation of gel-like substances is also small. The weight average molecular weight (Mw) is a value obtained in terms of standard polystyrene using gel permeation chromatography.

[0016] In this embodiment, it is preferable that the styrenic polymer (A-1) or the styrenic resin composition of this embodiment substantially does not contain vinyl cyanide monomers such as acrylonitrile monomer units and methacrylonitrile monomer units. Specifically, with respect to the total amount of the styrenic polymer (A-1) or the polymer matrix phase, it is preferable that the vinyl cyanide monomer is contained in an amount of 10% by mass or less, more preferably 5% by mass or less, and still more preferably 2% by mass or less. The content of the styrenic polymer (A-1) in this embodiment is preferably 65 to 99.88% by mass, more preferably 85 to 99.88% by mass, 87 to 99.5% by mass, still more preferably 88 to 98% by mass, even more preferably 89 to 97% by mass, and still more preferably 90 to 96.5% by mass, based on the entire styrenic resin composition (100% by mass).

[0017] - Rubber-like polymer - The styrenic resin composition of this embodiment essentially contains particles of a rubber-like polymer (= rubber-like polymer particles (A-2)). As described above, the rubber-like polymer particles (A-2) may be contained in the styrenic resin composition as part of the rubber-modified styrenic resin (A), or another rubber-like polymer particles (A-2) different from the rubber-like polymer particles (A-2) contained in the rubber-modified styrenic resin (A) may be further blended with the styrenic polymer (A-1) and contained in the styrenic resin composition. The rubbery polymer particles (A-2) contained in the rubber-modified styrene resin (A) or the styrene resin composition of the present embodiment may, for example, encapsulate a styrene polymer (A-1) inside, and / or a styrene polymer (A-1) may be grafted on the outside. Further, the rubbery polymer particles (A-2) of the present embodiment are not only core-shell structures composed of a styrene polymer (A-1) as a core and a rubbery polymer as a shell encapsulating the core, but also include salami structures composed of a plurality of styrene polymers (A-1) as cores and a rubbery polymer as a shell encapsulating the plurality of styrene polymers (A-1) as cores. In the present embodiment, with respect to the entire styrene resin composition (100% by mass), the content of the rubbery polymer particles (A-2) (including the content of the rubbery polymer itself (for example, a conjugated diene polymer such as polybutadiene) and the content of the styrene polymer (A-1) encapsulated in the rubbery polymer particles (A-2)) is preferably 10 to 30% by mass, more preferably 11 to 28% by mass, still more preferably 12 to 27% by mass, and still more preferably 13 to 25% by mass.

[0018] As the material of the rubbery polymer or rubbery polymer particles (A-2) of the present embodiment, for example, polybutadiene, polybutadiene encapsulating polystyrene, polyisoprene, natural rubber, polychloroprene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, etc. can be used, but polybutadiene or styrene-butadiene copolymer is preferred. For polybutadiene, both high-cis polybutadiene with a high cis content and low-cis polybutadiene with a low cis content can be used. Also, as the structure of the styrene-butadiene copolymer, both random structures and block structures can be used. These rubbery polymers can be used alone or in combination of two or more. Also, a saturated rubber obtained by hydrogenating a butadiene-based rubber can be used. Examples of such rubber-modified styrene resins (A) include HIPS (high impact polystyrene), ABS resin (acrylonitrile-butadiene-styrene copolymer), AES (acrylonitrile-ethylene propylene rubber-styrene copolymer), and the like.

[0019] In this embodiment, the content of the rubber-like polymer contained in the rubber-modified styrene resin (A) (which is the content of the rubber-like polymer itself (for example, a conjugated diene polymer such as polybutadiene), and does not include the styrene-based polymer (A-1) encapsulated in the rubber-like polymer particles (A-2)) is preferably 2.2 to 9.5% by mass, more preferably 2.4 to 9.0% by mass, more preferably 2.5 to 8.5% by mass, more preferably 2.6 to 8.0% by mass, more preferably 2.7 to 7.5% by mass, more preferably 2.8 to 7.0% by mass, and even more preferably 3.1 to 6.5% by mass with respect to the total amount (100% by mass) of the rubber-modified styrene resin (A). When the content of the rubber-like polymer is less than 2.2% by mass, there is a risk that the impact strength of the mouth part of the injection blow molded container will decrease. Also, when the content of the rubber-like polymer exceeds 9.5% by mass, there is a risk that the buckling strength of the container will decrease. In the present disclosure, the content of the rubber-like polymer contained in the rubber-modified styrene resin (A) is a value calculated using the method described in the Examples section.

[0020] In this embodiment, the content of the rubber-like polymer particles (A-2) contained in the rubber-modified styrene resin (A) (which includes the content of the rubber-like polymer itself (for example, a conjugated diene polymer such as polybutadiene) and the content of the styrene-based polymer (A-1) encapsulated in the rubber-like polymer particles (A-2)) is preferably 10 to 30% by mass, more preferably 11 to 28% by mass, even more preferably 12 to 26% by mass, and even more preferably 13 to 25% by mass with respect to the total amount (100% by mass) of the rubber-modified styrene resin (A). In the present disclosure, the content of the rubber-like polymer particles (A-2) contained in the rubber-modified styrene resin (A) is a value calculated using the method described in the Examples section.

[0021] In this embodiment, from the viewpoint of the balance between the mouth impact strength and the buckling strength, the lower limit of the average particle diameter of the rubber-like polymer particles (A-2) contained in the rubber-modified styrene resin (A) is preferably 0.9 μm, more preferably 1.0 μm, more preferably 1.1 μm, more preferably 1.2 μm, more preferably 1.3 μm, more preferably 1.4 μm, and even more preferably 1.5 μm. Further, the upper limit of the average particle diameter of the rubber-like polymer particles (A-2) is preferably 7.0 μm, more preferably 6.5 μm, more preferably 6.0 μm, more preferably 5.5 μm, more preferably 5.0 μm, and even more preferably 4.5 μm. In the present disclosure, the average particle diameter of the rubber-like polymer particles (A-2) contained in the rubber-modified styrene resin (A) is a value calculated using the method described in the Examples section.

[0022] In this embodiment, the reduced viscosity of the styrene polymer (A-1) contained in the rubber-modified styrene resin (A) (which serves as an index of the molecular weight of the styrene polymer (A-1)) is preferably in the range of 0.50 to 0.85 dL / g, more preferably in the range of 0.55 to 0.80 dL / g. When the reduced viscosity of the styrene polymer (A-1) is less than 0.50 dL / g, the impact strength decreases, and when the reduced viscosity exceeds 0.85 dL / g, the fluidity decreases. In the present disclosure, the reduced viscosity of the styrene polymer (A-1) is a value measured under the conditions of 30 °C and a concentration of 0.5 g / dL in a toluene solution.

[0023] - Method for Producing Rubber-Modified Styrene Resin (A)- In this embodiment, the method for producing the rubber-modified styrene-based resin (A) is not particularly limited, but bulk polymerization (or solution polymerization) in which a styrene-based monomer (and a solvent) is polymerized in the presence of a rubber-like polymer, or bulk-suspension polymerization that shifts to suspension polymerization during the reaction, or emulsion graft polymerization in which a styrene-based monomer is polymerized in the presence of a latex of a rubber-like polymer can be used for production. In bulk polymerization, a mixed solution obtained by adding a rubber-like polymer, a styrene-based monomer, and, if necessary, an organic solvent, an organic peroxide, and / or a chain transfer agent can be continuously supplied to a polymerization apparatus configured by connecting in series a completely mixed reactor or a tank reactor and a plurality of tank reactors to produce the rubber-modified styrene-based resin (A).

[0024] In this embodiment, the polymerization method of the styrene-based polymer (A-1) which is the polymer matrix phase of the rubber-modified styrene-based resin (A) is not particularly limited. For example, as a radical polymerization method, a bulk polymerization method or a solution polymerization method can be preferably employed. The polymerization method mainly includes a polymerization step of polymerizing a polymerization raw material (monomer component) and a devolatilization step of removing volatile components such as unreacted monomers and polymerization solvents from the polymerization product.

[0025] Hereinafter, an example of the polymerization method of the styrene-based polymer (A-1) that can be used in this embodiment will be described. When polymerizing the polymerization raw material to obtain the styrene-based polymer (A-1), a polymerization initiator and a chain transfer agent are typically contained in the polymerization raw material composition. As the polymerization initiator used for the polymerization of the styrene polymer (A-1), organic peroxides such as 2,2-bis(t-butylperoxy)butane, 1,1-di(t-butylperoxy)cyclohexane (Perhexa C), peroxyketals such as n-butyl-4,4-bis(t-butylperoxy)valerate, dialkyl peroxides such as di-t-butyl peroxide (Perbutyl D), t-butylcumyl peroxide, dicumyl peroxide, diacyl peroxides such as acetyl peroxide, isobutyryl peroxide, peroxydicarbonates such as diisopropyl peroxydicarbonate, peroxy esters such as t-butyl peroxyacetate, ketone peroxides such as acetylacetone peroxide, hydroperoxides such as t-butyl hydroperoxide, etc. can be mentioned. From the viewpoints of the decomposition rate and the polymerization rate, among them, 1,1-di(t-butylperoxy)cyclohexane (Perhexa C) is preferable. It is preferably added in an amount of 0.005 to 0.08% by mass based on the total amount of the monomers. As the chain transfer agent used for the polymerization of the styrene polymer (A-1), for example, mercaptans such as α-methylstyrene linear dimer, n-dodecyl mercaptan, t-dodecyl mercaptan, 1-phenyl-2-fluorene, dibentene, chloroform, terpenes, halogen compounds, terpenes such as terpinolene, etc. can be mentioned. The amount of use of this chain transfer agent is not particularly limited, but generally, it is preferably added in an amount of about 0.005 to 0.3% by weight based on the monomer.

[0026] As a polymerization method of the styrenic polymer (A-1), solution polymerization using a polymerization solvent can be adopted as necessary. Examples of the polymerization solvent used include aromatic hydrocarbons such as ethylbenzene, and dialkyl ketones such as methyl ethyl ketone. Each of them may be used alone or in combination of two or more. Other polymerization solvents such as aliphatic hydrocarbons can be further mixed with aromatic hydrocarbons as long as the solubility of the polymerization product is not decreased. These polymerization solvents are preferably used in a range not exceeding 25 parts by mass with respect to 100 parts by mass of all monomers. When the polymerization solvent exceeds 25 parts by mass with respect to 100 parts by mass of all monomers, the polymerization rate is significantly decreased, and the mechanical strength of the resulting resin tends to be greatly reduced. It is preferable to add at a ratio of 5 to 20 parts by mass with respect to 100 parts by mass of all monomers before polymerization, as the quality is easily homogenized and it is also preferable in terms of polymerization temperature control.

[0027] In the present embodiment, the apparatus used in the polymerization step for obtaining the styrenic polymer (A-1) is not particularly limited and may be appropriately selected according to the polymerization method of the styrenic resin. For example, when bulk polymerization is adopted, a polymerization apparatus in which one or a plurality of completely mixed reactors are connected can be used. Also, there is no particular limitation on the devolatilization step. For example, when bulk polymerization is adopted, polymerization is advanced until the unreacted monomer finally becomes preferably 50% by mass or less, more preferably 40% by mass or less, and a known method is used for devolatilization treatment to remove volatile components such as such unreacted monomers. More specifically, for example, ordinary devolatilization apparatuses such as a flash drum, a twin-screw devolatilizer, a thin-film evaporator, and an extruder can be used, but a devolatilization apparatus with less residence part is preferable. The temperature of the devolatilization treatment is usually about 190 to 280°C, more preferably 190 to 260°C. The pressure of the devolatilization treatment is usually about 0.13 to 4.0 kPa, preferably 0.13 to 3.0 kPa, more preferably 0.13 to 2.0 kPa. As the devolatilization method, for example, a method of removing volatile components by reducing the pressure under heating and a method of removing through an extruder or the like designed for the purpose of removing volatile components are desirable.

[0028] <Biomass plasticizer (B) (hereinafter also referred to as component (B))> The styrene resin composition in this embodiment contains a biomass plasticizer (B). And the biomass plasticizer (B) has a biomass carbon ratio (pMC%) of 10% or more. If the biomass carbon ratio (pMC%) is within the above range, the amount of fossil fuel used can be reduced, so that a styrene resin composition capable of reducing the environmental load can be provided. In this embodiment, the lower limit of the biomass carbon ratio (pMC%) is preferably 10% or more, more preferably 25% or more, still more preferably 50% or more, and even more preferably 75% or more. In this embodiment, based on the total amount (100% by mass) of the styrene resin composition, the content of the biomass plasticizer (B) is 0.1 to 15.0% by mass. The lower limit of the content of the biomass plasticizer (B) is preferably 0.5% by mass or more, more preferably 1.0% by mass or more. The upper limit of the content of the biomass plasticizer (B) is preferably 12.0% by mass or less, more preferably 10.0% by mass or less, still more preferably 8.0% by mass or less, and even more preferably 6.0% by mass or less. If the content of the biomass plasticizer (B) is too high, the fluidity of the resin increases, and stringing may occur during injection blow molding, which may damage the appearance of the molded product. In addition, it causes slide jamming and blow defects are likely to occur frequently. On the other hand, if the content of the biomass plasticizer (B) is too low, the impact strength of the mouth part decreases. In addition, since the fluidity decreases, a decrease in productivity is a concern. The biomass plasticizer (B) is preferably uniformly dispersed in the styrene resin composition. More specifically, for example, it is preferably not an external lubricant (for example, a lubricant insoluble in the polymer melt) that forms a single layer of the biomass plasticizer (B) on the surface of the styrene resin composition. Examples of the method for uniformly dispersing the biomass plasticizer (B) in the styrene resin composition include a method of kneading the rubber-modified styrene resin (A) and the biomass plasticizer (B) with an extruder, and a method of including the biomass plasticizer (B) in the polymerization raw material composition when polymerizing the polymerization raw material.

[0029] The biomass carbon ratio (pMC%) in this specification indicates the carbon concentration (mass ratio) of biomass-derived components. More specifically, it is the value of the 14 C content obtained by the radiocarbon 14 C measurement method in accordance with ASTM-D6866. The radiocarbon 14 C measurement method utilizes the fact that fossil fuels do not contain 14 C and that carbon derived from biomass (or organisms) absorbs 14 C in the atmosphere during the growth period, and is a method for estimating the biomass carbon ratio (pMC%) from the 14 C ratio in the carbon contained in biomass materials (or organisms). Therefore, by measuring the proportion of 14 C contained in all carbon atoms in the plasticizer of this embodiment, the proportion of carbon derived from biomass can be calculated. In the present invention, the biomass carbon ratio (pMC%) is calculated by the following formula (1) using the method described in the Examples section below. Formula (1): Biomass carbon ratio (pMC%) = ( 14 C plasticizer / 12 C plasticizer) / ( 14 C standard substance / 12 C standard substance) × 100 Also, oxalic acid (SRM4990) is used as the standard substance, and ([[]] 14 C plasticizer / 12 C plasticizer) / ( 14 C standard substance / 12 C standard substance) is calculated by the AMS method.

[0030] The weight average molecular weight (Mw) of the biomass plasticizer (B) in this embodiment is preferably from 200 to 7500, more preferably from 300 to 5000, and even more preferably from 400 to 3000. When the weight average molecular weight (Mw) of the biomass plasticizer is from 200 to 7500, a styrenic resin composition excellent in the balance between mechanical strength and fluidity can be obtained, and the incorporation of gel substances is also small. The weight average molecular weight (Mw) is a value obtained in terms of standard polystyrene using gel permeation chromatography as described in the Examples section below.

[0031] The biomass plasticizer (B) in this embodiment refers to a plasticizer using a biomass material as part or all of the raw materials, and a plasticizer having a biomass carbon ratio (pMC%) of 10% or more. The biomass plasticizer (B) of this embodiment uses a plant-derived biomass material as at least part of the raw materials, and is a plasticizer having a biomass carbon ratio (pMC%) of 10% or more, and is preferably a vegetable oil, a mixture of a vegetable oil and a mineral oil, or a polyester-based plasticizer, and more preferably a natural vegetable oil, a modified vegetable oil, a mixture of a natural vegetable oil and a mineral oil, a mixture of a modified vegetable oil and a mineral oil, a mixture of a natural vegetable oil, a modified vegetable oil and a mineral oil, or a polyester-based plasticizer. Note that the vegetable oil in this specification is a general term for plant-derived oils and fats, and includes natural vegetable oils and modified vegetable oils.

[0032] In this embodiment, a modified vegetable oil may be used as the biomass plasticizer (B). The modified vegetable oil refers to a compound using a vegetable oil as a raw material. More specifically, it is a product obtained by modifying a part of a hydrocarbon-based oil of plant origin with a functional group, and it is preferable that the vegetable oil is modified with an epoxy group, an amino group or an ester bond. Examples of the vegetable oil include triester compounds of glycerin and fatty acids, fatty acid monoesters obtained by adding a monoalcohol to a vegetable oil and subjecting it to a transesterification reaction, fatty acid monoesters obtained by subjecting a fatty acid and a monoalcohol to an esterification reaction, and ethers derived from fatty acids. In the present embodiment, the modifying group of the modified vegetable oil (epoxy group, amino group or functional group of ester bond) preferably does not substantially polymerize with other components (including styrenic resin (A)) or modified vegetable oils in the styrenic resin composition. Further, in the present embodiment, the modification rate of the modified vegetable oil per 1 g of the modified vegetable oil is preferably 1 mmol% to 50 mmol%. The modification rate of the above modified vegetable oil is as described in the examples described later 1 and is calculated by the 1H-NMR measurement method.

[0033] Specific examples of the natural vegetable oil include, for example, cottonseed oil, castor oil, shea oil, alfalfa oil, poppy oil, pumpkin oil, winter pumpkin oil, cereal oil, barley oil, quinoa oil, rye oil, kukui oil, asparagus oil, shea butter, aloe vera oil, sweet almond oil, peach kernel oil, soybean oil, cashew oil, peanut oil, avocado oil, baobab oil, ruru oil, broccoli oil, safflower oil, linseed oil, rape seed oil, cottonseed oil, coconut oil, pumpkin seed oil, wheat germ oil, jojoba oil, lily oil, macadamia oil, corn oil, meadowfoam oil, monoi oil, hazelnut oil, apricot oil, walnut oil, olive oil, evening primrose oil, palm oil, blackcurrant seed oil, kiwi seed oil, grape seed oil, pistachio oil, jasmine oil, sesame oil, soybean oil, sunflower oil, castor oil, watermelon oil or a mixture of these oils. In the present embodiment, the modified vegetable oil includes oils obtained by hydrogenating the above-exemplified natural vegetable oils (for example, hydrogenated castor oil); oils obtained by epoxidizing the above-exemplified natural vegetable oils (for example, modified epoxidized oils); and oils obtained by aminating the above-exemplified natural vegetable oils (for example, modified aminated oils). The modified epoxidized oils include oils in which epoxy functional groups typified by hydroxylated modified soybean oil are ring-opened, oils directly hydroxylated in advance, and cashew oil-based polyols.

[0034] Specific examples of the biomass plasticizer (B) of the present embodiment include, for example, palm oil, epoxidized soybean oil, epoxidized linseed oil, castor hardened oil, polyoxyethylenated castor oil, polyoxyethylenated hardened castor oil, oleic acid ester, or lauric acid ester, "Polysizer W-1810-BIO" and "Epoxysizer" manufactured by DIC Corporation; "New Sizer 510R" and "New Sizer 512" manufactured by NOF Corporation; "Pionin D series" manufactured by Takemoto Yushi Co., Ltd.; "Multi Ace 20(S)" and "Refined Palm Oil (S)" manufactured by Nisshin Oillio Group Co., Ltd., and "Castor Hardened Oil" manufactured by Ito Oil Co., Ltd.

[0035] In the present embodiment, the viscosity of the vegetable oil (including natural vegetable oil and modified vegetable oil) is preferably 1000 mPa·s or less at 25°C, more preferably 20 to 1000 mPa·s, and even more preferably 50 to 800 mPa·s.

[0036] The melting point of the biomass plasticizer (B) in the present embodiment is preferably -30 to 80°C, more preferably -25 to 77°C, even more preferably -22°C to 74°C, still 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) exceeds 80°C, the biomass plasticizer (B) is difficult to melt with respect to the styrene resin (A), and the addition or mixing operation becomes difficult. On the other hand, when the melting point of the biomass plasticizer (B) is less than -30°C, it is necessary to use a compound containing a large number of unsaturated bonds as the type of biomass plasticizer (B) that can be used, so it is easily oxidized and deteriorated and the physical properties are easily reduced. In general, since all the double bond portions of natural vegetable oils are cis-type, it is considered that the more double bonds there are, the lower the intermolecular force and the lower the melting point tend to be.

[0037] In this embodiment, the difference between the SP value of the styrenic polymer (A-1) and the SP value of the biomass plasticizer (B) ((cal / cm 3 ) 1 / 2 ) is preferably less than ±2.5, more preferably less than 2.4, still more preferably less than ±2.3, still more preferably less than 2.2, still more preferably less than 2.1, still more preferably less than 2.0, still more preferably less than 1.9, still more preferably less than 1.8, still more preferably less than 1.7, still more preferably less than 1.6, still more preferably less than 1.5, still more preferably less than 1.4, still more preferably less than 1.3, still more preferably less than 1.2, even more preferably less than ±1.1, still even more preferably less than ±1.0, still even more preferably less than ±0.9, and still even more preferably less than ±0.8. If the difference between the SP value of the styrenic polymer (A-1) and the SP value of the biomass plasticizer (B) is 2.5 or more, it becomes difficult for the two to be compatible. In addition, the SP value of the styrenic polymer (A-1) in this embodiment is preferably 7 to 11 ((cal / cm 3 ) 1 / 2 ), more preferably 7.5 to 10.5 ((cal / cm 3 ) 1 / 2 ), still more preferably 7.8 to 10.2 ((cal / cm 3 ) 1 / 2 ), still even more preferably 8.0 to 10.0 ((cal / cm 3 ) 1 / 2 ), still even more preferably 8.0 to 9.8 ((cal / cm 3 ) 1 / 2 ), still more preferably 8.0 to 9.6 ((cal / cm 3 ) 1 / 2 ), still even more preferably 8.0 to 9.4 ((cal / cm 3 ) 1 / 2 ), still even more preferably 8.0 to 9.2 ((cal / cm 3 ) 1 / 2 ), still even more preferably 8.0 to 9.0 ((cal / cm 3 ) 1 / 2 ). In addition, the lower limit of the SP value of the biomass plasticizer (B) in this embodiment is 7.4 ((cal / cm 3 )1 / 2 )It is more preferably the above, more preferably 7.5 ((cal / cm 3 ) 1 / 2 ) or more, more preferably 7.6 ((cal / cm 3 ) 1 / 2 ) and more preferably 7.7 ((cal / cm 3 ) 1 / 2 ) or more, even more preferably 7.8 ((cal / cm 3 ) 1 / 2 ) or more. The upper limit of the 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, more preferably 9.8 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 9.6 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 9.4 ((cal / cm 3 ) 1 / 2 ) or less, more preferably 9.2 ((cal / cm 3 ) or less, more preferably 9.0 ((cal / cm 3 ) or less, even more preferably 8.8 ((cal / cm 3 ) 1 / 2 ) or less. Also, the preferable range of the SP value of the biomass plasticizer (B) in the present embodiment can be a range arbitrarily combining the upper limit of the above SP value and the lower limit of the above SP value. The solubility parameter (SP value) defined in the present embodiment is calculated using the function of the cohesive energy density shown in the following formula. SP value ((cal / cm 3 ) 1 / 2 ) = (△E / V) 1 / 2 Formula (1) (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.) In addition, the heat quantity change ΔHm due to mixing is expressed by the following equation using the SP value. ΔHm = V(δ1 - δ2)·Φ1·Φ2 ··· Equation (2) (δ1 represents the SP value of the solvent, δ2 represents the SP value of the solute, Φ1 represents the volume fraction of the solvent, and Φ2 represents the volume fraction of the solute.) From the above equations (1) and (2), the closer the values of δ1 and δ2 are, the smaller ΔHm becomes, and the Gibbs free energy becomes smaller. Therefore, those with a smaller difference in SP values have higher affinity. As a method for obtaining the SP value in this specification, the SP value of an unknown resin is calculated from the SP value of the solvent that is most compatible by comparing the solubility of the resin with various solvents whose SP values are known. Specifically, it is calculated using the turbidity titration method. In this embodiment, mainly the value obtained by calculation from the monomer composition is used. Since the amount of gas generated during molding is reduced when the biomass plasticizer (B) of this embodiment has a high boiling point, it is preferably relatively high boiling (for example, 260 °C or higher, which is the molding temperature of injection blow) from the viewpoint of being advantageous for reducing mold fouling. When the SP value of the biomass plasticizer (B) is within the above range, the intermolecular cohesive energy, that is, the heat of vaporization can be controlled within a predetermined range, and thus it tends to have a high boiling point to the extent that the amount of gas generated during molding can be reduced.

[0038] In this embodiment, examples of the mineral oil include atmospheric residue obtained by atmospheric distillation of crude oils such as paraffinic crude oil (including liquid paraffin), intermediate-base crude oil, and naphthenic crude oil; distillate oil obtained by vacuum distillation of these atmospheric residues; mineral oil obtained by subjecting the distillate oil to one or more purification treatments such as solvent deasphalting, solvent extraction, hydrocracking, solvent dewaxing, catalytic dewaxing, and hydrorefining; mineral oil obtained by isomerizing wax (GTL wax) produced by the Fischer-Tropsch method, etc. These mineral oils may be used alone or in combination of two or more. In this embodiment, when a vegetable oil and a mineral oil are mixed and used as the biomass plasticizer (B), there is no particular limitation as long as the biomass carbon ratio (pMC ratio) of the entire biomass plasticizer (B) is 10% or more.

[0039] <Higher fatty acid compound (C) (hereinafter, also referred to as component (C).)> The styrenic resin composition of this embodiment contains a higher fatty acid compound (C) as an essential component in an amount of 0.02 to 2.5% by mass based on the entire styrenic resin composition. The higher fatty acid compound (C) acts as a release agent and can 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) is preferably 0.04 to 2% by mass, more preferably 0.06 to 1.7% by mass, still more preferably 0.08 to 1.4% by mass, and even more preferably 0.1 to 1.0% by mass based on the entire styrenic resin composition. When the higher fatty acid compound (C) is 0.02% by mass or less, the releasability is poor, leading to a decrease in productivity, which is not preferable. Also, when the higher fatty acid compound (C) is contained in an amount exceeding 2.5% by mass, the releasability is not improved further, and there is a concern that problems such as discoloration of the resin due to decomposition deterioration of the higher fatty acid, burning, charring of the molded product, and deterioration of mold fouling may occur. The above-mentioned higher fatty acid is a saturated straight-chain carboxylic acid having 12 to 22 carbon atoms, and examples thereof include stearic acid, lauric acid, myristic acid, palmitic acid, and behenic acid. The metal salt of the higher fatty acid is a metal salt of a saturated straight-chain carboxylic acid having 12 to 22 carbon atoms. Examples of the metal include zinc, calcium, magnesium, aluminum, barium, lead, lithium, potassium, sodium, etc. When a higher fatty acid and a higher fatty acid salt are used in combination as the higher fatty acid compound (C), the total amount of the higher fatty acid and the higher fatty acid salt may be within the range of 0.02 to 2.5% by mass, and these higher fatty acids or higher fatty acid salts can be used alone or as a mixture of two or more. It can also be used as a release agent in combination with polyethylene glycol or fatty alcohol, or a silicone-based additive.

[0040] <Optional additive components> In addition to the components (A) and (B), the styrene resin composition of the present embodiment may contain optional additive components such as known additives and processing aids, etc., as long as the effects of the present invention are not impaired. Examples of these optional additive components include flame retardants, dispersants, antioxidants, weathering agents, antistatic agents, fillers, antiblocking agents, colorants, blooming inhibitors, surface treatment agents, antibacterial agents, and anti-fogging agents (anti-fogging agents such as silicone oils, monoamide compounds of higher aliphatic carboxylic acids, and monoester compounds obtained by reacting higher aliphatic carboxylic acids with monohydric to trihydric alcohol compounds described in JP-A-2009-120717). In the present embodiment, the styrene resin composition may contain a known flame retardant (phosphorus-based flame retardant, halogen-based flame retardant such as bromine-based). However, from the viewpoint of fear of generating gases such as hydrogen bromide by the reaction with the biomass plasticizer (B) contained in the styrene resin composition, the content of the halogen-based flame retardant is preferably less than 3% by mass, more preferably less than 1% by mass, based on the total amount (100% by mass) of the styrene resin composition.

[0041] The styrene resin composition in the present embodiment preferably does not contain metal elements, excluding inevitable impurities. More specifically, the content of the metal element is preferably less than 3% by mass, more preferably less than 1% by mass, and even more preferably less than 0.5% by mass, based on the total amount (100% by mass) of the styrene resin composition. When the styrene resin composition contains a metal element, particularly metal particles, not only the mold used in molding is damaged, but also there is a high possibility that metal powder of the mold will be mixed into the styrene resin composition. The above metal elements refer to the elements of Groups 2 to 12 of the periodic table, Group 1 other than hydrogen atoms, Group 13 other than boron atoms, and the elements represented by Ge, As, Sn, Pb, As, Sb, Bi, Se, Te, Po, and At. These metal elements can be used alone or in the form of alloys or mixtures of two or more kinds. In this embodiment, as the dispersant, a fatty acid ester compound, a polyethylene glycol compound, a terpene compound, a rosin compound, a fatty acid amide, a fatty acid compound, a fatty acid metal salt, etc. can be used. Examples of the antioxidant include phenolic compounds, phosphorus compounds, thioether compounds, etc. The total content of the optional additive components may be 0.05 to 5% by mass based on the entire styrene resin composition.

[0042] When a modified vegetable oil is used as the biomass plasticizer (B) contained in the styrene resin composition of this embodiment, the content of the hydroxyl group-containing compound is preferably less than 3% by mass, more preferably less than 1% by mass, based on the total amount (100% by mass) of the styrene resin composition. The hydroxyl group-containing compound in this embodiment refers to a compound having a hydroxyl group in the polymer, such as (meth)acrylic acid, maleic acid, phthalic acid. When the hydroxyl group-containing compound is 3% by mass or more, it reacts with the modified vegetable oil, causing gelation, which deteriorates the moldability or the appearance of the molded product. When a natural vegetable oil is used as the biomass plasticizer contained in the styrene resin composition, the amount of the hydroxyl group-containing compound is not specified.

[0043] The styrene resin composition of this embodiment may consist essentially of only the component (A), component (B), component (C) and optional additive components. It may also consist of only the component (A), component (B) and component (C), or only the component (A), component (B), component (C) and optional additive components. "Consisting essentially of only the component (A), component (B), component (C) and optional additive components" means that, based on the total amount of the styrene resin composition, preferably 85 to 100% by mass, more preferably 90 to 100% by mass, still more preferably 95 to 100% by mass, even more preferably 98 to 100% by mass, is the component (A), component (B) and component (C), or the component (A), component (B), component (C) and optional additive components. In addition, the styrene resin composition of the present embodiment may contain inevitable impurities in addition to the components (A), (B), (C) and optional components as long as the effects of the present invention are not impaired.

[0044] [Physical properties of styrene resin composition] <Melt mass flow rate (MFR)> The melt mass flow rate (measured under the conditions of 200°C and a load of 49 N) of the styrene resin composition of the present embodiment is 3.0 to 13.0, preferably 3.3 to 11.5, preferably 3.5 to 10.0, and more preferably 4.0 to 9.5. If the melt mass flow rate is lower than 3.0, the fluidity is poor and it is likely to cause insufficient filling during molding. Although it can be molded by raising the molding temperature and the core temperature, the release balance is disrupted, uneven wall thickness is likely to occur, and good products cannot be obtained. On the other hand, if the melt mass flow rate exceeds 11.0, a defective phenomenon such as stringing is likely to occur between the injection mold and the parison, making continuous molding difficult.

[0045] <Vicat softening temperature> The Vicat softening temperature of the styrene resin composition of the present embodiment is preferably 75°C to 100°C, more preferably 78°C to 98°C, and even more preferably 80°C to 96°C.

[0046] <Swelling index of rubber-like polymer particles (A-2)> 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 from the viewpoint of impact strength. The swelling index is an index representing the degree of crosslinking of the rubber particles. By setting the swelling index within the above range, the styrene resin composition of the present invention will have excellent impact properties. In the present disclosure, the swelling index of the styrene resin composition is a value calculated using the method described in the Examples section.

[0047] [Injection blow molded product] As a method for manufacturing an injection blow molded article using the styrene resin composition of the present embodiment as a raw material, it is not particularly limited and can be molded by a known method. Specifically, in injection blow molding, first, an intermediate (for example, a bottomed parison) is molded from the styrene resin composition by injection molding, and then this intermediate is transferred into a blow molding die while being attached to a core (male mold for injection molding) in a softened state, and then, by sending compressed air from the core and expanding it to the inner wall surface of the blow molding die, a hollow molded article (for example, a container) can be molded. In the above molding method, in the step of blow molding the intermediate, the mold temperature is preferably 35 to 75 ° C, more preferably 40 to 60 ° C, and even more preferably 45 to 55 ° C. Further, the temperature of the styrene resin composition is preferably 210 to 260 ° C, and more preferably 220 to 250 ° C. The magnification of the volume of the container with respect to the volume of the intermediate (volume draw ratio) is preferably 1.5 to 7 times, and more preferably 2 to 5 times.

Examples

[0048] <Measurement and Evaluation Methods> The physical property evaluations of the resin compositions and injection blow molded articles obtained in each example and comparative example were carried out based on the following methods.

[0049] (1) Measurement of the weight average molecular weight of the styrene polymer (A-1) and the biomass plasticizer (B) in the rubber-modified styrene resin (A) used in the examples and comparative examples The weight average molecular weights of the styrene polymer (A-1) and the biomass plasticizer (B) were measured under the following conditions and procedures. · Sample preparation: 5 mg of the measurement sample was dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 μm filter. · Measurement conditions Equipment: TOSOH HLC-8220GPC (Gel Permeation Chromatography) Columns: Two SHODEX GPC KF-606M columns were connected in series Guard column: SHODEX GPC KF-G 4A Temperature: 40 °C Carrier: THF 0.50 mL / min Detector: RI, UV: 254 nm Calibration curve: For the preparation of the calibration curve, 11 types of Tosoh TSK standard polystyrenes (F-850, F-450, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000) were used. The calibration curve was prepared using a third-degree linear approximation formula.

[0050] (2) Melt mass-flow rate (MFR) The melt mass-flow rate (g / 10 min) of the styrenic polymer (A-1) in the rubber-modified styrenic resin (A) used in the examples and comparative examples was measured in accordance with ISO 1133 (200 °C, load 49 N).

[0051] (3) Measurement of Vicat softening temperature (°C) The Vicat softening temperature (°C) of the rubber-modified styrenic resin (A) and the styrenic resin composition used in this example and the comparative examples was measured at a load of 49 N in accordance with ISO 306.

[0052] (4) Measurement of the content and swelling index of the rubbery polymer particles (A-2) The content (mass %) and swelling index of the rubber-modified styrene resin (A) or the rubber-like polymer particles (A-2) in the styrene resin composition were measured as follows. 1.00 g of the rubber-modified styrene resin (A) or the styrene resin composition was precisely weighed into a precipitation tube (this mass is designated as W1), 20 milliliters of toluene was added, and the mixture was shaken at 23°C for 1 hour. Then, it was centrifuged at a temperature of 4°C, a rotational speed of 20,000 rpm, and a centrifugal acceleration of 45,100×G for 60 minutes using a centrifuge (manufactured by Sakuma Seisakusho, model SS-2050A, rotor: 6B-N6L). The precipitation tube was slowly tilted to about 45 degrees, and the supernatant was removed by decantation. The mass of the insoluble matter containing toluene was precisely weighed (this mass is designated as W2). Subsequently, it was vacuum dried at 160°C under a pressure of 3 kPa or less for 1 hour, cooled to room temperature in a desiccator, and then the mass of the toluene-insoluble matter was precisely weighed (this mass is designated as W3). The content and swelling index of the rubber-like polymer particles (A-2) in the rubber-modified styrene resin (A) or the styrene resin composition, that is, the content and swelling index of the rubber-like polymer particles (A-2) in the rubber-modified styrene resin (A) or the styrene resin composition, were determined by the following formula. Content of rubber-like polymer particles (A-2) = W3 / W1 × 100 Swelling index of rubber-like polymer particles (A-2) = W2 / W3

[0053] (5) Measurement of average particle size The average particle size (μm) of the rubber-like polymer particles (A-2) in the rubber-modified styrene resin (A) or the styrene resin composition used in the examples and comparative examples was measured by the following method. Using a COULTER MULTISIZER III (trade name) manufactured by Beckman Coulter, Inc. equipped with a 30-μm aperture tube, 0.05 g of the pelletized rubber-modified styrene resin (A) or the pelletized styrene resin composition was placed in about 5 ml of dimethylformamide and left for about 2 to 5 minutes. Next, the dimethylformamide-soluble portion was measured at an appropriate particle concentration, and the volume-based median diameter was determined.

[0054] (6) Measurement of the content of the rubber-like polymer 0.25 g of the rubber-modified styrene resin (A) or styrene resin composition used in the examples and comparative examples was dissolved in 50 mL of chloroform, iodine monochloride was added to react with the double bonds in the rubber component, potassium iodide was then added to convert the remaining iodine monochloride to iodine, and back-titration was performed with sodium thiosulfate (iodine monochloride method). By this method, the mass of the rubber (designated as W4) contained in the rubber-modified styrene resin (A) or styrene resin composition was measured, and from this value and the mass of the rubber-modified styrene resin (A) or styrene resin composition (designated as W1), the content (% by mass) of the rubbery polymer in the rubber-modified styrene resin (A) or styrene resin composition was determined by the following formula. Content (% by mass) of rubbery polymer in rubber-modified styrene resin (A) or styrene resin composition = W4 / W1 × 100

[0055] (7) Quantification of biomass plasticizer (B) content For the quantification of the content of biomass plasticizer (B) in the styrene resin compositions used in the examples and comparative examples, either of the following procedures (1) or (2) was used. Equivalent numerical values were obtained when the value obtained from (1) was compared with the value obtained from (2). (7-1) Calculation using NMR Vegetable oil (glycerin fatty acid ester) was dissolved in deuterated chloroform (containing 1% TMS) containing 2-dimethoxyethane as an internal standard substance, 1 and 1H-NMR measurement was performed. When the peak of TMS was used as a reference at 0 ppm, peaks derived from protons bonded to carbon adjacent to the ester group of the vegetable oil were detected at δ 4.0 - 4.4 ppm and peaks derived from 1,2-dimethoxymethane were detected at 3.4 - 3.6 ppm. The peak area of the vegetable oil-derived peak was calculated when the peak area of 1,2-dimethoxymethane-derived peak was set to 1. By performing this operation while changing the concentration of the vegetable oil, a calibration curve for the vegetable oil concentration was created. The pelletized styrene resin composition obtained in the example or comparative example was dissolved in deuterated chloroform (containing 1% TMS), 1 1H-NMR measurement was performed, and by using the above calibration curve, the vegetable oil content in the styrene resin composition was quantified. In the above method, when other peaks overlap with the peak of the internal standard substance and it is difficult to quantify, an appropriate substance may be used as the internal standard substance as appropriate. In addition, it is also possible to quantify the peak derived from triglyceride detected in vegetable oil at 5.0 to 5.5 ppm. (2) Calculation from methanol-soluble content 1.0 g of the pelletized styrene resin composition obtained in the example or comparative example (this weight is designated as W11) was placed in a screw bottle with a capacity of 20 mL, and 10 mL of methyl ethyl ketone was added. Then, after completely dissolving the pellets with a shaker, 5 mL of methanol was further added to precipitate the styrene polymer (A-1) as an insoluble substance, and centrifuged at 2000 G for 10 minutes using a centrifuge to sediment the insoluble substance. Next, the sedimented insoluble matter was pre-dried in a dryer heated to 140 °C for 40 minutes, and then vacuum dried at the same temperature for 20 minutes to completely volatilize the solvent. The mass of the dried insoluble matter was measured, and this mass was designated as W12. Using the measured masses W11 and W12, the methanol-soluble content (W13) was defined as follows. The methanol-soluble content (W13) was defined as W13 = W11 - W12. In addition, in this operation, the supernatant after centrifugal sedimentation with a centrifuge was subjected to GC-MS measurement to quantify the contents of styrene oligomers, residual monomers, residual solvents, and other low molecular substances other than plasticizers soluble in methanol, and the mass (W14) contained in 1.0 g of the styrene resin composition was calculated. Using the calculated masses W13 and W14, the content of the biomass plasticizer (B) in the styrene resin composition was determined as follows. The content of the biomass plasticizer (B) = W13 - W14

[0056] (8) Calculation of the modification rate In the styrene resin containing the modified vegetable oil, the modification rate of the modified vegetable oil can be calculated using either of the following procedures (8-1) or (8-2). 1 It is possible to calculate the modification rate of the modified vegetable oil by 1H-NMR. (8-1) The pelletized styrene resin composition obtained in the example or comparative example was dissolved in deuterated chloroform (containing 1% TMS).1 Perform H-NMR measurement. When TMS is used as the reference at 0 ppm, a peak derived from the epoxy group is observed at δ 2.8 - 3.2 ppm, and a peak derived from the proton bonded to the carbon adjacent to the ester group of the vegetable oil is observed at δ 4.0 - 4.4 ppm. From the peak area ratio of these two peaks, the epoxy modification rate was calculated. Although a peak derived from the epoxy group is detected at δ 2.8 - 3.2 ppm and a peak derived from the proton bonded to the carbon adjacent to the ester group of the vegetable oil is detected at δ 4.0 - 4.4 ppm, if these peaks overlap with other peaks and quantification becomes difficult, quantification is performed by the method in (2). (8-2) Weigh 1 g of the pelletized styrene resin composition obtained in the example or comparative example into a 20 mL screw vial, and add 10 mL of methyl ethyl ketone. After completely dissolving the pellets with a shaker, add 5 mL of methanol, and the styrene resin composition precipitates as an insoluble component in the solution. Next, remove the insoluble part, transfer the solution part to a eggplant flask, and evacuate for 2 hours with an evaporator to volatilize methyl ethyl ketone and methanol. Then, add the liquid (vegetable oil) remaining in the eggplant flask to deuterated chloroform (containing 1% TMS). 1 Perform H-NMR measurement. When TMS is used as the reference at 0 ppm, a peak derived from the epoxy group is observed at δ 2.8 - 3.2 ppm, and a peak derived from the proton bonded to the carbon adjacent to the ester group of the vegetable oil is observed at δ 4.0 - 4.4 ppm. From the peak area ratio of these two peaks, the epoxy modification rate was calculated.

[0057] (9) Mouth impact strength Lay the injection blow molded container horizontally so that the parting line is vertical, place the container so that a falling weight hits the mouth, and measure the falling weight impact strength (DuPont impact strength) using a DuPont impact tester (No451) manufactured by Toyo Seisakusho Co., Ltd. The mass of the falling weight was 200 g, the radius of the impact tip was 9.4 mm, the test was performed with n = 30, and the falling weight impact strength was determined from the 50% fracture height. And a value of 3.0 kg·cm or more was regarded as passing.

[0058] (10) Mouth compression strength The injection blow molded container was laid horizontally so that the parting line was vertical, and compressed at a speed of 200 mm / min so that the mouth flange hit vertically. The load until it deformed by 10 mm was defined as the mouth compression strength. For this measurement, containers for two shots were used, and the measured values were averaged. And the container mouth compression strength was considered qualified if it was 23 or more. As the measuring device, a tabletop precision universal testing machine (Autograph AGS-5kNX) manufactured by Shimadzu Corporation was used.

[0059] (11) Buckling strength The injection blow molded container was fixed to the lower platen for the compression test, and the compression strength when a load was applied at a pressing speed of 200 mm / min with a compression load jig protruding from the movable part of the compression testing machine was measured. As the measuring device, a tabletop precision universal testing machine (Autograph AGS-5kNX) manufactured by Shimadzu Corporation was used. The measured results were evaluated according to the following criteria. If the buckling strength was less than 120 N, the rigidity was insufficient, and adverse effects such as the container buckling in practical applications occurred, so 120 N or more was considered qualified.

[0060] (12) Moldability (number of times of stringing) The method for evaluating the number of times of stringing in this example and the comparative example was to evaluate whether stringing could be visually confirmed at the bottom of the molded product when molding a cylindrical rigid container with an injection blow molding machine. The injection blow molding machine used was SG125NP manufactured by Sumitomo Heavy Industries, Ltd. Molding was performed at a cylinder and hot runner temperature of 240 °C and a mold temperature of 50 °C. After molding 140 containers for 10 shots, the evaluation was performed based on the number of containers in which stringing was confirmed.

[0061] (13) Moldability (number of blow defects) The evaluation method for the number of blow molding defects in this example and the comparative examples was to evaluate whether the parison formed by injection molding separated from the mold when forming a cylindrical rigid container using an injection blow molding machine. The injection blow molding machine used was the SG125NP manufactured by Sumitomo Heavy Industries, Ltd. Molding was carried out at a cylinder and hot runner temperature of 240°C and a mold temperature of 50°C. When it was confirmed that the parison after molding adhered to the mold and could not be completely removed, it was counted as one, and the evaluation was carried out based on the number of mold release defects when molding a total of 100 times. Since the productivity decreases when the number of blow molding defects exceeds 10, a result of 10 or less was considered a pass.

[0062] (14) Moldability (Number of shots until mold fouling occurs) The evaluation method for the number of blow molding defects in this example and the comparative examples was to evaluate the number of shots until deposits were visually confirmed on the mold when forming a cylindrical rigid container using an injection blow molding machine. The injection blow molding machine used was the SG125NP manufactured by Sumitomo Heavy Industries, Ltd. Molding was carried out at a cylinder and hot runner temperature of 240°C and a mold temperature of 50°C, and it was checked whether there were mold deposits every 5 shots, and molding was carried out up to 150 shots. If mold deposits were confirmed in less than 100 shots, it would require time for mold maintenance and the productivity would decrease, so a result of 100 shots or more was considered a pass.

[0063] (15) Calculation of SP value The SP value of each material used in the examples and comparative examples was the solubility parameter using the Hildebrand method (including the Hansen method), and was calculated by the turbidity titration method with reference to literature values ( "Fundamentals of Biomaterials", edited by Kazuhiko Ishizuka, Takao Tsutsumi, and Mizuho Maeda, published by Nippon Medical School) or "J. Appl. Polym. Sci., 12, 2359 (1968)". In addition, in the styrene resin compositions of the examples and comparative examples, since each component blended in the composition is known, the SP value can be easily calculated by the above method. On the other hand, when the details of the styrene polymer or plasticizer contained in the unknown styrene resin composition are unknown, the SP value can be calculated by the following procedures (i) to (iv). Procedure (i): A sample to be targeted (styrene polymer or plasticizer) recovered or separated from the styrene 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. Procedure (ii): Next, the SP values of the solvents used in the dissolution test of procedure (i) are plotted three-dimensionally. Procedure (iii): The operations of procedure (i) and procedure (ii) are carried out with 15 to 20 types of solvents. Procedure (iv): By calculating a sphere that includes the coordinates of the solvents in which the sample dissolved and does not include the coordinates of the solvents in which it did not dissolve, the center coordinates of the sphere represent the Hansen's SP value, and the distance from the origin represents the Hildebrand's SP value, thereby calculating the solubility parameter using the Hildebrand method (including the Hansen method). The SP values calculated by the above procedures (i) to (iv) are generally in agreement with the above literature values or the SP values calculated by the turbidity titration method.

[0064] The respective materials used in the examples and comparative examples are as follows. (Butadiene rubber) Polybutadiene rubber (Diene 55 manufactured by Asahi Kasei Chemicals Corporation), Polybutadiene rubber UBEPOL BR (BR15HB manufactured by UBE Elastomers Co., Ltd.)

[0065] [Biomass plasticizer (B)] (Modified vegetable oil) Epoxidized soybean oil (product name "New Saizer 510R" (manufactured by NOF Corporation), weight average molecular weight (Mw = 1500), biomass carbon ratio (pMC%) 100%, melting point: 5°C, SP value (calculated value by the Hansen method, distance from the origin in the three-component coordinates of the dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 9.0 ((cal / cm 3 ) 1 / 2) Epoxy modification rate: 5 mmol per 1 g Epoxidized linseed oil (product name "O-180A" (ADEKA Corporation), weight average molecular weight (Mw = 1500), biomass carbon ratio (pMC%) 100%, melting point: -2 °C, SP value (calculated value by Hansen method, distance from the origin in the three-component coordinates of dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 9.3 ((cal / cm 3 ) 1 / 2 ), Epoxy modification rate: 8 mmol per 1 g (Natural vegetable oil) Palm oil (product name "Multi Ace 20(S)" (Nisshin Oillio Group Ltd.), weight average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point: 22 °C, SP value (calculated value by Hansen method, distance from the origin in the three-component coordinates of dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 8.2 ((cal / cm 3 ) 1 / 2 ) Soybean oil (product name "Soybean White Squeezed Oil(S)" (Nisshin Oillio Group Ltd.) weight average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point -8 °C, SP value (calculated value by Hansen method, distance from the origin in the three-component coordinates of dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 8.2 ((cal / cm 3 ) 1 / 2 ) Castor hardened oil (product name "Castor hardened oil" (Ito Oil Co., Ltd.), weight average molecular weight (Mw = 1000), biomass carbon ratio (pMC%) 100%, melting point 85 °C, SP value (calculated value by Hansen method, represents the distance from the origin in the three-component coordinates of dispersion force term (δD), polar term (δP) and hydrogen bond term (δH)): 10.1 ((cal / cm 3 ) 1 / 2 )

[0066] [Others] (Liquid paraffin) Liquid paraffin, product name "PS350S" (manufactured by Sanko Chemical Industries, Ltd.), weight average molecular weight (Mw = 250), biomass carbon ratio (pMC%) 0%, pour point: -12.5 °C, SP value (literature value): 7.3 (cal / cm 3 ) 1 / 2 (polylactic acid) Polylactic acid, product name "LX175" (manufactured by Total Corbinion PLA), biomass carbon ratio (pMC%) 100%, melting point: 155 °C, SP value (literature value): 10.3 (cal / cm 3 ) 1 / 2

[0067] [Method for producing styrene resin composition] [Example 1] (Method for producing composition (PS-1)) A polymerization solution prepared by mixing and dissolving 92.1% by mass of styrene, 6.0% by mass of ethylbenzene, 3.2% by mass of polybutadiene rubber (diene 55 manufactured by Asahi Kasei Chemicals Corporation), and 0.8% by mass of Multi Ace 20(S) (manufactured by Nisshin Oillio Group, Ltd.) was continuously charged into a 6.2-liter laminar flow reactor-1 equipped with a stirrer and capable of temperature control in 3 zones at a rate of 3.24 liters / Hr, and the temperature was adjusted to 121 °C / 125 °C / 131 °C. The rotation speed of the stirrer was set at 70 revolutions per minute. The reaction rate at the reactor outlet was 26%. Subsequently, the reaction solution was sent to a 6.2-liter laminar flow reactor-2 equipped with a stirrer and connected in series with the laminar flow reactor-1 and capable of temperature control in 3 zones. The stirring speed of the stirrer was set at 40 revolutions per minute, and the temperature was set at 136 °C / 140 °C / 144 °C. Subsequently, the reaction solution was sent to a 6.2-liter laminar flow reactor-3 equipped with a stirrer and capable of temperature control in 3 zones. The rotation speed of the stirrer was set at 10 revolutions per minute, and the temperature was set at 146 °C / 148 °C / 150 °C. The polymer solution continuously discharged from the polymerization reactor (laminar flow reactor-3) was heated to 230 °C and pelletized under a reduced pressure of 0.8 kPa using an extruder with a vacuum vent to produce a pellet-like composition (PS-1). Next, a 3:1 mixture of stearic acid / calcium stearate was blended at 0.25% by mass based on the entire styrene resin composition, and kneaded with an extruder to produce the styrene resin composition of Example 1. Further, the polymer matrix phase of the styrene resin composition contains polystyrene, and the SP value of the polystyrene is 8.6 (cal / cm 3 ) 1 / 2 .

[0068] [Examples 2 to 36] (Manufacturing methods of compositions (PS-2) to (PS-35) and (PS-44)) Compositions (PS-2) to (PS-35) were produced in the same manner as composition (PS-1), except that the polymerization conditions were changed as shown in Table 1-1. The styrene resin composition of Example 36 (composition (PS-44)) was produced by kneading composition (PS-36) with an extruder so that the content of palm oil was 3% by mass and the content of a 3:1 mixture of stearic acid / calcium stearate as a release agent was 0.25% by mass based on the entire styrene resin composition after producing composition (PS-36).

[0069] [Comparative Examples 1 to 9] <Manufacturing methods of compositions (PS-36) to (PS-43) and (PS-45)> Compositions (PS-36) to (PS-43) were produced in the same manner as composition (PS-1), except that the polymerization conditions were changed as shown in Table 1-2. The styrene resin composition of Comparative Example 7 (composition (PS-45)) was prepared by adding poly(lactic acid) (PLA) to composition (PS-36) so that the content was 3% by mass based on the entire styrene resin composition, adding a 3:1 mixture of stearic acid / calcium stearate as a release agent, and kneading with a twin-screw extruder.

[0070]

Table 1-1

[0071]

Table 1-2

[0072]

Table 1-3

[0073]

Table 2-1

[0074]

Table 2-2

[0075]

Table 2-3

[0076]

Table 2-4

Industrial Applicability

[0077] The present invention provides a styrene resin composition that has a low environmental impact, excellent injection blow moldability, and excellent mechanical strength of the molded article when injection blow molded, and an injection blow molded article made of the styrene resin composition. The molded article obtained from the styrene resin composition can be suitably used for beverage containers and the like.

Claims

1. A styrenic resin composition containing a styrenic polymer (A-1) and rubber-like polymer particles (A-2) having an average particle diameter of 0.9 to 7.0 μm, a biomass plasticizer (B) having a biomass carbon ratio (pMC%) of 10% or more, and a higher fatty acid compound (C), wherein with respect to the entire styrenic resin composition (100% by mass), the content of the rubber-like 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. Styrenic resin composition.

2. The styrenic resin composition according to claim 1, wherein the SP value of the biomass plasticizer (B) is 7.4 to 10.

5.

3. The styrenic resin composition according to claim 1 or 2, wherein the SP value of the styrenic polymer (A-1) is 7.0 to 11.

0.

4. The styrenic resin composition according to any one of claims 1 to 3, wherein the weight average molecular weight of the styrenic polymer (A-1) is 140,000 to 240,000.

5. The styrenic polymer (A-1) is contained in an amount of 65 to 99.88% by mass with respect to the entire styrenic resin composition (100% by mass), and the content of the styrenic monomer unit with respect to the total amount of the styrenic polymer (A-1) is 50% by mass or more. The styrenic resin composition according to any one of claims 1 to 4.

6. An injection blow molded article obtained by injection blow molding the styrenic resin composition according to any one of claims 1 to 5.

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