Biomass-derived polymer-containing resin sheet and container made of molded product thereof

Abstract

To provide a resin sheet that contains a biomass-derived resin and has film impact strength and oil resistance above a certain level.SOLUTION: A biomass-derived polymer-containing resin sheet is a resin sheet that comprises a layer formed from a resin composition containing a styrene-based copolymer (A) containing vinyl cyanide monomer unit and styrene-based monomer unit, a biomass-derived polyethylene (B), and a styrene-based thermoplastic elastomer (C) containing at least one of a diene component and a diene hydrogenated component, and has a film impact strength of 2.0 J / mm or more as measured according to ASTM-D3420.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a biomass-derived polymer-containing resin sheet and a container formed therefrom. [Background technology]

[0002] In recent years, in order to reduce the environmental load, it has been considered to replace a portion of the resin raw materials from resins mainly composed of fossil fuel-derived components with biomass-derived resins.

[0003] For example, a laminated film using biopolyethylene containing plant-derived ethylene in the middle layer and a wrap film using it in both surface layers have been proposed (Patent Documents 1 and 2). The replacement of food containers with biomass-derived resins is also being considered, but food containers require oil resistance. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-189748 A [Patent Document 2] International Publication No. 2018 / 163835 Summary of the Invention [Problem to be solved by the invention]

[0005] From the viewpoint of oil resistance, it was considered to blend the acrylonitrile styrene (AS) resin used in the lid material of food containers with biomass-derived resin. However, our investigation revealed that not only was the strength insufficient even when blended as described above, but the oil resistance inherent to AS resin could be impaired by blending it with biomass-derived resin.

[0006] An object of the present invention is to provide a resin sheet which contains a biomass-derived resin and has at least a certain level of film impact strength and oil resistance. [Means for solving the problem]

[0007] As a result of examining various means, the present inventors found that a resin sheet having a certain level of film impact strength and oil resistance can be easily obtained by using a styrene-based copolymer containing vinyl cyanide monomer units and styrene-based monomer units, biomass-derived polyethylene, and a styrene-based thermoplastic elastomer containing at least one of a diene component and a hydrogenated diene component, and thus completed the present invention.

[0008] The present invention relates to the following: [1] A resin sheet comprising a layer formed from a resin composition containing: a styrenic copolymer (A) containing vinyl cyanide monomer units and styrenic monomer units; a biomass-derived polyethylene (B); and a styrenic thermoplastic elastomer (C) containing at least one of a diene component or a hydrogenated diene component, the resin sheet having a film impact strength of 2.0 J / mm or more as measured in accordance with ASTM-D3420. [2] The resin sheet according to [1], comprising a layer formed from a resin composition containing, relative to 100% by mass of the total mass of the resin composition, 10 to 70% by mass of a styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units, 5 to 70% by mass of a biomass-derived polyethylene (B), and 10 to 45% by mass of a styrene-based thermoplastic elastomer (C) containing at least one of a diene component or a hydrogenated diene component. [3] The resin sheet according to [1] or [2], wherein the vinyl cyanide monomer unit contained in the styrene-based copolymer (A) containing the vinyl cyanide monomer unit and the styrene-based monomer unit is 5 to 25 mass% relative to 100 mass% of the total mass of the resin composition. [4] The resin sheet according to any one of [1] to [3], wherein the content of the styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units is 10% by mass or more and less than 50% by mass. [5] The resin sheet according to any one of [1] to [4], wherein the styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units is an acrylonitrile-styrene copolymer. [6] The resin sheet according to any one of [1] to [5], wherein the styrene-based thermoplastic elastomer (C) contains at least one elastomer selected from the group consisting of styrene-butadiene block copolymers and hydrogenated styrene-based thermoplastic elastomers. [7] The resin sheet according to any one of [1] to [6], wherein the styrene-based copolymer (A) contains a recycled material of a styrene-based copolymer containing vinyl cyanide monomer units and styrene-based monomer units. [8] The resin sheet according to any one of [1] to [7], wherein the resin sheet has a tensile modulus of elasticity of 400 MPa or more as measured in accordance with ASTM-D638. [9] A container comprising a molded body of any one of the resin sheets described in [1] to [8].

[10] A container as described in [9], which is for storing food. Effect of the Invention

[0009] According to the present invention, it is possible to provide a resin sheet which contains a biomass-derived resin and has at least a certain level of film impact strength and oil resistance. [Brief description of the drawings]

[0010] [Figure 1] 1 is a TEM photograph of a resin sheet according to one embodiment of the present invention. [Diagram 2] FIG. 1 is a diagram showing an example of a food container manufactured using the resin sheet of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiment, and can be carried out by making appropriate modifications within the scope that does not impair the effects of the present invention.

[0012] [First embodiment] The resin sheet according to the first embodiment of the present invention is a resin sheet including a layer formed from a resin composition containing a styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units, a biomass-derived polyethylene (B), and a styrene-based thermoplastic elastomer (C) containing at least one of a diene component or a hydrogenated diene component.

[0013] (Layer formed from resin composition) In this embodiment, the layer formed from the resin composition is formed from a resin composition containing a styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units, a biomass-derived polyethylene (B), and a styrene-based thermoplastic elastomer (C) containing at least one of a diene component or a hydrogenated diene component. The layer formed from the resin composition can be produced by feeding the styrene copolymer (A), the biomass-derived polyethylene (B), and the styrene thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated diene component into an extruder, melt-kneading the mixture, and then extruding the mixture through a die (preferably a T-die). The temperature during melt-kneading is preferably 180 to 260°C, more preferably 200 to 240°C. In one embodiment of the present invention, the thickness of the layer formed from the resin composition can be, for example, 0.25 to 0.60 mm, more preferably 0.35 to 0.50 mm.

[0014] (Styrene-based copolymer (A)) In this embodiment, the styrene copolymer is a copolymer containing a vinyl cyanide monomer unit and a styrene monomer unit. That is, the styrene copolymer of this embodiment contains at least a vinyl cyanide monomer unit and a styrene monomer unit as monomer units.

[0015] Examples of the vinyl cyanide monomer constituting the vinyl cyanide monomer unit include acrylonitrile, methacrylonitrile, and cyano(meth)acrylate. These vinyl cyanide monomers may be used alone or in combination of two or more. Among these, it is preferable that the vinyl cyanide monomer contains acrylonitrile, from the viewpoint of easier improvement of oil resistance. The proportion of vinyl cyanide monomer units in the styrene-based copolymer is preferably 10 to 40 mass %, more preferably 18 to 35 mass %, and even more preferably 24 to 32 mass %, relative to the total mass of the styrene-based copolymer. The monomer composition ratio can be determined by pyrolysis gas chromatography. More specifically, 0.3 mg of a sample is weighed and measured under the following conditions, and the monomer composition ratio is determined from the peak area ratio of the detected components. ·Pyrolysis device: Manufactured by Japan Analytical Industry Co., Ltd. Product name: “JPS-220” ·Thermal decomposition temperature: 590℃ Gas chromatograph: Hewlett-Packard, product name: "5890SERIESI" Column: Slightly polar column (Agilent Technologies, Inc., product name: "DB-5") Carrier gas: He pressure 2psi Temperature conditions: After holding at 50°C for 5 minutes, heat to 250°C at 18°C / min and hold at 250°C for 7 minutes Detection: FID The proportion of vinyl cyanide monomer units in the resin composition is preferably 5 to 25 mass %, more preferably 5 to 12 mass %, and further preferably 5 to 9 mass %, relative to the total mass of the resin composition.

[0016] Examples of styrene monomers constituting the styrene monomer unit include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, ethylstyrene, pt-butylstyrene, etc. These styrene monomers may be used alone or in combination of two or more. Among these, it is preferable to include styrene. The proportion of the styrene monomer units in the styrene copolymer is preferably 60 to 90 mass %, more preferably 65 to 82 mass %, and even more preferably 68 to 76 mass %, based on the total mass of the styrene copolymer.

[0017] In one embodiment of the present invention, the styrene-based copolymer may contain a monomer unit (other monomer unit (x)) other than the vinyl cyanide monomer unit and the styrene-based monomer unit, as necessary. Examples of the other monomer units (x) include vinyl-based monomer units, such as (meth)acrylic acid, maleic anhydride, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-methylhexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dicyclopentanyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more. In addition, "(meth)acrylic acid" means acrylic acid and methacrylic acid. In addition, "(meth)acrylate" means acrylate and methacrylate. When the styrene-based copolymer contains other monomer units (x), the content thereof is preferably less than 10% by mass, more preferably 1 to 5% by mass, based on the total mass of the styrene-based copolymer.

[0018] In one embodiment of the present invention, the styrene copolymer is an acrylonitrile-styrene copolymer. That is, the resin sheet of this embodiment preferably contains an acrylonitrile-styrene copolymer. If the styrene copolymer is an acrylonitrile-styrene copolymer, the oil resistance is more likely to be improved. The preferred ratio of the acrylonitrile unit and the styrene unit in the acrylonitrile-styrene copolymer is the same as the above-mentioned vinyl cyanide monomer unit and the styrene monomer unit.

[0019] The styrene copolymer is obtained by polymerizing a monomer mixture containing a vinyl cyanide monomer and a styrene monomer, preferably acrylonitrile and styrene. The polymerization method is not particularly limited, but from the viewpoint of easy reduction of odor, bulk continuous polymerization is preferred. In one embodiment, the styrene copolymer may be a mixture of multiple copolymers. In this case, each copolymer may be polymerized by any method, and then the multiple copolymers may be mixed to obtain a styrene copolymer.

[0020] A known method can be adopted for the bulk continuous polymerization. Among them, it is preferable to carry out the polymerization by adding 10 to 40 parts by mass of a solvent such as ethylbenzene, toluene, or methyl ethyl ketone to 100 parts by mass of the monomer mixture. In addition, conventionally known organic peroxides, molecular weight modifiers, etc. can be added during the polymerization as necessary. The polymerization temperature is preferably from 80 to 170°C, and more preferably from 100 to 160°C.

[0021] The weight average molecular weight (Mw) of the styrene copolymer is preferably 50,000 to 250,000, more preferably 100,000 to 200,000. If the Mw of the copolymer (A) is 50,000 to 250,000, the strength of the resin sheet is likely to be good. Also, the film formability is likely to be good. Also, the polydispersity (Mw / Mn), which is the ratio of the Mw to the number average molecular weight (Mn) of the styrene copolymer, is preferably 2.0 to 3.0, more preferably 2.1 to 2.5. If the polydispersity of the styrene copolymer is 2.0 to 3.0, the strength of the resin sheet is unlikely to decrease, and the oil resistance is likely to be better. The Mw and Mn of the styrene copolymer refer to values ​​calculated in terms of polystyrene by GPC (gel permeation chromatography). Specifically, they refer to values ​​measured under the following conditions. <Method for measuring Mw and Mn of styrene copolymer> Equipment: Shodex Co., Ltd., Product name: "Shodex SYSTEM-21" Column: PLgel MIXED-B Measurement temperature: 40℃ Solvent: Tetrahydrofuran Flow rate: 1.0mL / min Detection method: RI Sample concentration: 0.2% by mass Injection volume: 100μL Calibration curve: Standard polystyrene (Polymer Laboratories)

[0022] The content of the styrene copolymer in the resin sheet is preferably 10 to 70 mass%, more preferably 10 to 50 mass%, and particularly preferably 15 to 45 mass%, based on the total mass of the resin sheet. If the content of the styrene copolymer is within the above range, high oil resistance is maintained and impact strength is easily improved. Note that the "total mass of the resin sheet" means the total mass of the resin composition constituting the resin sheet.

[0023] (Biomass-derived polyethylene (B)) In the present embodiment, the biomass-derived polyethylene may be any polyethylene containing biomass-derived ethylene as a monomer component, and may contain a petroleum-derived monomer component as a copolymer component, such as biomass-derived low-density polyethylene or plant-derived linear low-density polyethylene. Here, biomass refers to reusable organic resources (excluding fossil fuels such as petroleum) derived from plants and animals, and mainly includes plants (crops, wood, seaweed, etc.), food waste, paper, animal carcasses / excrement, and plankton.

[0024] Biomass-derived polyethylene refers to a homopolymer of ethylene produced using biomass as a raw material, or a copolymer of ethylene and an α-olefin produced using biomass as a raw material. Such a polymer can be synthesized by a known production method.

[0025] The α-olefin is preferably at least one compound selected from the group consisting of α-olefins having 3 to 20 carbon atoms, more preferably α-olefins having 4 to 6 carbon atoms, or a mixture thereof. The group consisting of α-olefins having 3 to 20 carbon atoms is, for example, propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-decene, 1-dodecene, 4-methyl-1-pentene, and 4-methyl-1-hexene, and the α-olefins having 4 to 6 carbon atoms are, for example, 1-butene and 1-hexene, respectively. It is preferable that the α-olefin is contained in an amount of 1 to 20 parts by mass per 100 parts by mass of the total of the plant-derived ethylene and α-olefin. Petroleum-derived α-olefins may be used as the α-olefin.

[0026] In one embodiment of the present invention, the biomass-derived polyethylene preferably has a bio-based content (%) of 80 to 100%, more preferably 82 to 98%, as measured in accordance with ASTM D6866. When the bio-based content is 80% or more, it is possible to reduce CO2 emissions by approximately 70 to 74% compared to petroleum-derived polyethylene, making it possible to effectively utilize exhaustible resources and significantly reduce the amount of CO2 generated, which is a cause of greenhouse gases.

[0027] The density of biomass-derived polyethylene is 0.90 to 0.98 g / cm 3 is preferable, and 0.95 to 0.97 g / cm 3 is more preferred. Furthermore, from the viewpoints of extrusion processability, biaxial orientation, and thickness uniformity in thermoforming, the melt flow rate (MFR) of the biomass-derived polyethylene is preferably within the range of 0.1 to 3.0 g / 10 min, and more preferably within the range of 0.3 to 1.0 g / 10 min, under measurement conditions of 190°C and 2.16 kgf.

[0028] In the present embodiment, a suitable example of the biomass-derived polyethylene is a polyethylene having a trade name of "SGF4960" (density 0.961 g / cm 3, MFR 0.34g / 10min, bio-based content 96%), product name "SBC818" (density 0.918g / cm 3 , MFR 8.3g / 10min, bio-based content 95%), product name "STN7006" (density 0.924g / cm 3 , MFR 0.6g / 10min, bio-based content 95%), product name "SPB681" (density 0.922g / cm 3 , MFR 3.8g / 10min, bio-based content 95%), product name "SLL118" (density 0.916g / cm 3 , MFR 1.0g / 10min, bio-based content 87%), "SLL118 / 21" (density 0.918g / cm 3 , MFR 1.0 g / 10 min, bio-based content 95%), and the product name "SLH118" (density 0.916 g / cm 3 , MFR 1.0 g / 10 min, bio-based content 84%) (all manufactured by Braskem).

[0029] The content of the biomass-derived polyethylene in the resin sheet is preferably 5 to 70 mass %, more preferably 10 to 60 mass %, and particularly preferably 25 to 40 mass %, based on the total mass of the resin sheet. When the content of the biomass-derived polyethylene is within the above range, the heat resistance of the resin sheet is likely to be improved.

[0030] (Styrene-based thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated diene component) In this embodiment, the styrene-based thermoplastic elastomer containing at least one of a diene component or a hydrogenated diene component means a styrene-based thermoplastic elastomer produced using a diene as a raw material or a hydrogenated product thereof. The styrene-based thermoplastic elastomer does not have to act as a compatibilizer. Here, the diene component means a monomer unit derived from a diene constituting the styrene-based thermoplastic elastomer. The hydrogenated diene component means a hydrogenated monomer unit derived from a diene constituting the styrene-based thermoplastic elastomer. Examples of styrene-based thermoplastic elastomers containing at least one of a diene component and a hydrogenated diene component include block copolymers such as styrene / butadiene (SB), styrene / isoprene (SI), styrene / butadiene / butylene (SBB), styrene / butadiene / isoprene (SBI), styrene / butadiene / styrene (SBS), styrene / butadiene / butylene / styrene (SBBS), styrene / isoprene / styrene (SIS), and styrene / butadiene / isoprene / styrene (SBIS), as well as hydrogenated block copolymers thereof. In this embodiment, it is possible to use only one type of the above-mentioned styrene-based thermoplastic elastomers, or to use a combination of two or more types of them.

[0031] The weight average molecular weight (Mw) of the styrene-based thermoplastic elastomer is preferably 100,000 to 200,000, more preferably 120,000 to 180,000. If the Mw of the styrene-based thermoplastic elastomer is 100,000 to 200,000, the strength tends to be good. In addition, the processability into sheets and films tends to be good. The weight average molecular weight Mw and the number average molecular weight (Mn) are measured by GPC under the same conditions as those for the above-mentioned styrene-based copolymer (A).

[0032] The content of the styrene-based thermoplastic elastomer in the resin sheet is preferably 10 to 45 mass%, more preferably 10 to 35 mass%, and particularly preferably 10 to 30 mass%, based on the total mass of the resin sheet. When the content of the styrene-based thermoplastic elastomer is within the above range, the film impact strength of the resin sheet is easily improved.

[0033] (Other Ingredients) In one embodiment of the present invention, the resin sheet may contain other resins other than the styrene copolymer (A), the biomass-derived polyethylene (B), and the styrene thermoplastic elastomer (C) containing at least one of a diene component or a hydrogenated diene component. Examples of the other resins include rubber-reinforced resins such as high-impact polystyrene, ABS resin, AES resin, and styrene-butadiene block copolymer resin. When the resin sheet contains other resins, the amount of the other resins is preferably less than 5% by mass with respect to the total mass of the resin sheet.

[0034] Furthermore, the resin sheet may contain, as necessary, other additives such as ultraviolet absorbers, light stabilizers, antioxidants, lubricants, plasticizers, colorants, antistatic agents, flame retardants, and mineral oils, reinforcing fibers such as glass fibers, carbon fibers, and aramid fibers, and fillers such as talc, silica, mica, and calcium carbonate. These may be used alone or in combination of two or more.

[0035] Examples of the ultraviolet absorber include 2-(5'-methyl-2'-hydroxyphenyl)benzotriazole, 2-(5'-t-butyl-2'-hydroxyphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzyl)phenyl]benzotriazole, 2-(3',5'-di-t-butyl-2'-hydroxyphenyl)benzotriazole, 2-(3'-t-butyl-5'-methyl-2'-hydroxyphenyl)-5-chlorobenzotriazole, 2-(3',5'-di-t-butyl-2'-hydroxyphenyl)benzotriazole, 2-(3',5'-di-t-amyl-2'-hydroxyphenyl)benzotriazole, 2-[3'-(3”,4”,5”,6”-tetrahydrophthalimidomethyl)-5'-methyl-2'-hydroxyphenyl]benzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole-2-yl)phenol] and other benzotriazole-based ultraviolet absorbers; 2-ethoxy-2'-ethyl oxalic acid bisanilide, 2-ethoxy-5-t-butyl oxalic acid anilide ultraviolet absorbers such as 2-ethyl-2'-ethyl oxalic acid bisanilide and 2-ethoxy-4'-isodecylphenyl oxalic acid bisanilide; 2-hydroxy-4-n-octoxybenzophenone, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-sulfobenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and 2-hydroxy-4-methoxy-2'-carboxybenzophenone; Examples of the ultraviolet absorbing agent include benzophenone-based ultraviolet absorbers; salicylic acid-based ultraviolet absorbers such as phenyl salicylate, pt-butylphenyl salicylate, and p-octylphenyl salicylate; cyanoacrylate-based ultraviolet absorbers such as 2-ethylhexyl-2-cyano-3,3'-diphenylacrylate and ethyl-2-cyano-3,3'-diphenylacrylate; and titanium oxide-based ultraviolet stabilizers such as rutile titanium oxide, anatase titanium oxide, alumina, silica, titanium oxide treated with a surface treatment agent such as a silane coupling agent or a titanium-based coupling agent.These may be used alone or in combination of two or more.

[0036] Examples of light stabilizers include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, dimethyl succinate·1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, and poly[[6,(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl] [(2,2,6,6-tetramethyl-4-piperidyl)imino]-hexamethylene-[(2,2,6,6-tetramethyl-4-piperidyl)imino]], 1-[2-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]ethyl]-4-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-2,2,6,6-tetramethylpiperidine, etc. These may be used alone or in combination of two or more.

[0037] Examples of the antioxidant include triethylene glycol bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 2,4-bis(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, pentaerythrityl tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl -4-hydroxyphenyl)propionate, 2,2-thiobis(4-methyl-6-t-butylphenol) and 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene and other phenol-based antioxidants; ditridecyl-3,3'-thiodipropionate, dilauryl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, Sulfur-based antioxidants such as dioctyl-3,3'-thiodipropionate and dioctyl-3,3'-thiodipropionate; trisnonylphenyl phosphite, 4,4'-butylidene-bis(3-methyl-6-t-butylphenyl-di-tridecyl)phosphite, (tridecyl)pentaerythritol diphosphite, bis(octadecyl)pentaerythritol diphosphite, bis(di-t-butylphenyl)pentaerythritol diphosphite, bis(di Examples of phosphorus-based antioxidants include tetrakis(2,4-di-t-butyl-4-methylphenyl)pentaerythritol diphosphite, dinonylphenyl octyl phosphonite, tetrakis(2,4-di-t-butylphenyl)1,4-phenylene diphosphonite, tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylene diphosphonite, and 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene. These may be used alone or in combination of two or more.

[0038] (Resin sheet) In this embodiment, the resin sheet includes a layer formed from a resin composition containing a styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units, a biomass-derived polyethylene (B), and a styrene-based thermoplastic elastomer (C) containing at least one of a diene component or a hydrogenated diene component. In one embodiment of the present invention, the resin sheet is composed of a layer formed from the aforementioned resin composition. In another embodiment, the resin sheet may be a laminate sheet including, in addition to the layer formed from the aforementioned resin composition, one or two layers formed from another thermoplastic resin composition. The film impact strength of the resin sheet measured according to ASTM-D3420 is 2.0 J / mm or more. It is also preferable that it is 3.0 J / mm or more, and more preferably 4.0 J / mm or more. If the film impact strength of the resin sheet is 2.0 J / mm or more, it is strong enough to be used as a food storage container.

[0039] In this embodiment, the resin sheet has oil resistance. Here, having oil resistance means that the resin sheet is rated at least △ or higher in the oil resistance test in the following examples. More preferably, the resin sheet is rated ◯.

[0040] In this embodiment, the resin sheet has heat resistance. Here, having heat resistance means that the resin sheet is rated at least as good or better in the heat resistance test in the following examples. More preferably, it means that the resin sheet is rated as good.

[0041] In one embodiment of the present invention, the resin sheet has a tensile modulus of elasticity of 400 MPa or more in both MD and TD as measured according to ASTM-D638. Preferably, the lower of the tensile modulus in the MD and TD directions is 700 MPa or more, more preferably, the lower of the tensile modulus in the MD and TD directions is 1000 MPa or more. If the tensile modulus of elasticity of the resin sheet is within the above range, it is difficult to deform when food is stored in it, and it can be used in practical use. In addition, the ratio of the tensile modulus in the MD and TD directions (MD / TD) is preferably 0.7 to 1.8, more preferably 0.8 to 1.7.

[0042] In one embodiment of the present invention, the thickness of the resin sheet is not particularly limited as long as the effects of the present invention are achieved, but it can be, for example, 0.25 to 0.60 mm, and more preferably 0.35 to 0.50 mm.

[0043] In one embodiment of the present invention, the resin sheet contains at least one of a diene component and a hydrogenated diene component in an amount of preferably 5 to 25 mass %, more preferably 5 to 15 mass %, and even more preferably 5 to 10 mass %, based on 100 mass % of the resin composition. The diene content is measured by potentiometric titration using iodine monochloride, potassium iodide and sodium thiosulfate standard solutions, and the diene content is calculated as the diene content. The measurement method is described in, for example, "New Edition Polymer Analysis Handbook" edited by the Polymer Analysis Research Roundtable of the Japan Analytical Chemistry Society, Kinokuniya Shoten (1995 edition), p. 659 (3) Rubber Content. The content of hydrogenated diene components is 1 H-NMR or 13 It can be measured by C-NMR.

[0044] [Manufacturing method of resin sheet] In one embodiment of the present invention, a method for producing a resin sheet is to feed a styrene copolymer (A), a biomass-derived polyethylene (B), and a styrene thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated diene component into an extruder, melt-knead, and then extrude from a die (preferably a T-die) to produce a sheet. The temperature during melt-kneading is preferably 180 to 260°C, more preferably 200 to 240°C. The thickness of the sheet can be 0.25 to 0.60 mm, preferably 0.35 to 0.50 mm, taking into account the thickness suitable for a food storage container. When the resin sheet is a laminated sheet, general methods can be used, such as a method in which each raw resin is melt-extruded using two or more single-screw extruders or twin-screw extruders, and a laminated sheet is obtained using a feed block and a T-die, or a method in which a laminated sheet is obtained using a multi-manifold die.

[0045] [container] In this embodiment, the resin sheet can be made into a container by a known method. For example, the resin sheet can be made into a container by a method such as vacuum molding or pressure forming. Specifically, a molded product with good shape reproducibility can be obtained by hot plate heating pressure forming. The "container" in the present invention includes not only a main container for storing the contents, but also a lid material that can be fitted to the main container. The container in this embodiment has excellent heat resistance and oil resistance, and therefore can be suitably used as a container for storing food, particularly as a container for storing food heated in a microwave oven. However, the use of the container obtained from the resin sheet of this embodiment is not limited to food storage use. EXAMPLES

[0046] The present invention will be described in more detail below by showing examples, but the interpretation of the present invention is not limited to these examples.

[0047] The materials used in the examples and comparative examples are as follows. Styrene copolymer (A-1) Acrylonitrile-styrene copolymer: "AS-EXS" (manufactured by Denka) (A-2) Regenerated granulated acrylonitrile-styrene copolymer (A-3) High impact polystyrene: "H850N" (manufactured by Toyo Styrene Co., Ltd.) Biomass-based polyethylene (B) Biomass polyethylene (HDPE): "SGF4960" (density 0.961 g / cm 3 , MFR 0.34g / 10min, bio-based content 96%, manufactured by Braskem) Styrene-based thermoplastic elastomer (C-1) Styrene-based thermoplastic elastomer (SBS): "TR2000" (manufactured by JSR Corporation, polybutadiene content 60% by mass) (C-2) Styrene-based thermoplastic elastomer (SBC): "220M" (manufactured by Denka, polybutadiene content 28% by mass) (C-3) Styrenic thermoplastic elastomer (SEBS): "H1041" (manufactured by Asahi Kasei Corporation, diene hydrogenation content 70% by mass)

[0048] (Production of regenerated granulated acrylonitrile-styrene copolymer (A-2)) Scraps generated at a molding factory where acrylonitrile-styrene copolymer (AS-EXS, Denka) stretched sheets were molded were pulverized in a pulverizer, and then recycled and granulated in a twin-screw extruder at a cylinder temperature of 240°C to obtain recycled granulated resin (A-2). The MFR of the resulting pellets was 2.0g / min under conditions of 200°C and 5kg load.

[0049] Example 1 20% by mass of styrene copolymer (A-1), 70% by mass of biomass-derived polyethylene (B), and 10% by mass of styrene thermoplastic elastomer (C-1) were melt-kneaded at 230°C and 70 rpm using a single-screw extruder with a screw diameter of 40 mm, and passed through a T-die to obtain a single-layer sheet with a thickness of 0.43 mm. The impact strength, tensile modulus, oil resistance, and heat resistance of the obtained single-layer sheet were evaluated by the following methods. When the viscoelastic spectrum of the obtained resin was examined, peaks of the styrene-based copolymer (A-1) and the biomass-derived polyethylene (B) were observed (not shown). Figure 1 is a TEM photograph of the resin sheet of Example 1. As can be seen from Figure 1, it was revealed that a sea-island structure was formed. The TEM imaging was performed under the following conditions. From the above, it became clear that the styrene-based thermoplastic elastomer did not act as a compatibilizer. <TEM Imaging Conditions> The sheets in the MD and TD directions were stained with a 4% OsO4 aqueous solution and then sliced into thin sections with a cryomicrotome. These thin sections were steam-stained with a 0.5% RuO4 aqueous solution and observed by TEM. · Apparatus: JEM-2100 (transmission electron microscope) manufactured by JEOL · Conditions: Acceleration voltage 120 kV

[0050] <Measurement of Film Impact Strength> Measurement was carried out in accordance with ASTM-D3420 using a film impact tester (manufactured by Yasuda Seiki). Specifically, a single-layer sheet with a thickness of 0.43 mm was cut into 70 mm × 70 mm to prepare a measurement sample for evaluation. Evaluation was also carried out according to the following evaluation criteria. (Evaluation Criteria) A: Impact strength is 3.0 J / mm or more B: Impact strength is 2.0 J / mm or more and less than 3.0 J / mm C: Impact strength is less than 2.0 J / mm In addition, when the elastic modulus of the sheet was low and it was so soft that it could not be punched out during the impact strength measurement, the measurement could not be performed and it was regarded as not feasible.

[0051] <Measurement of Tensile Elastic Modulus> Measurement was carried out in accordance with ASTM D638 using an autograph (AGS-X manufactured by Shimadzu Corporation). Specifically, a single-layer sheet with a thickness of 0.43 mm was cut out in the shape of dumbbell No. 1 in the MD direction and TD direction respectively to prepare a measurement sample for evaluation. Evaluation was also carried out according to the following evaluation criteria. (Evaluation Criteria) A: The lower of the tensile modulus in the MD and TD directions is 700 MPa or more B: The lower of the tensile modulus in the MD and TD directions is 400 MPa or more and less than 700 MPa. C: The lower of the tensile modulus in the MD and TD directions is less than 400 MPa

[0052] <Oil resistance test> The evaluation was performed by the constant strain method. Specifically, a single-layer sheet with a thickness of 0.43 mm was cut out so that it was long in the MD direction with a size of 300 mm x 15 mm. This was wrapped around a pipe with a diameter of 19 mm so that the degree of strain ε = 2.3%, and a 10 cm x 10 cm piece of gauze soaked in mayonnaise (manufactured by Kewpie Corporation) was attached to the distorted part, and the gauze was left to stand for 24 hours in a room at 23 ° C., and the surface of the attached part was observed. In addition, it was evaluated according to the following evaluation criteria. Those with an evaluation of △ or higher were considered to have oil resistance. 〇: No change △: Slightly whitened ×: Significant whitening and cracking

[0053] <Heat resistance test> A single-layer sheet with a thickness of 0.43 mm was molded into a molded product with dimensions of 150 mm length x 130 mm width x 20 mm height using a small vacuum / compressed air single shot molding machine FVS-500 (manufactured by Wakisaka Engineering Co., Ltd.) under molding conditions of heater temperature 500°C, heating time 10 seconds, mold temperature 70°C, and mold retention time 15 seconds. The product was then placed in a hot air dryer set at 110°C for 30 minutes, after which the deformation of the container was observed. Evaluation was also conducted according to the following evaluation criteria. Products with a rating of fair or better were deemed to have heat resistance. Good: No deformation Possible: Slight deformation Not acceptable: Large deformation

[0054] (Examples 2 to 7, Comparative Examples 1 to 6) A sheet was obtained in the same manner as in Example 1, except that the types and amounts of the styrene copolymer (A), biomass-derived polyethylene (B), and styrene thermoplastic elastomer (C) were changed as shown in Table 1. As in Example 1, the impact strength, tensile modulus, oil resistance, and heat resistance of the obtained single-layer sheet were evaluated by the following methods. The results are shown in Table 1.

[0055] [Table 1]

[0056] As can be seen from Table 1, the resin sheets according to the examples were shown to solve the problems. On the other hand, in Comparative Example 1, high impact polystyrene was used, and although there was no problem in terms of film impact strength, it was shown that the oil resistance was insufficient. In Comparative Example 2, a resin sheet was produced using only acrylonitrile-styrene copolymer and biomass-derived polyethylene. Not only was the strength insufficient, but it was also shown that blending with biomass-derived polyethylene impaired the oil resistance inherent to the acrylonitrile-styrene copolymer. The resin sheet of Comparative Example 3 was rated as × in the oil resistance test. The reason for this is presumably that the resin sheet of Comparative Example 3 has a high tensile modulus, and therefore the strain on the sheet was high when a pipe with a diameter of 19 mm was used in the test. In addition, it was shown that the evaluation of the resin sheet using (A-2) the recycled granulated acrylonitrile-styrene copolymer was equivalent to the evaluation of the resin sheet using (A-1) the acrylonitrile-styrene copolymer: "AS-EXS" (manufactured by Denka Company, Ltd.).

[0057] Although the present invention has been described above using various embodiments, it goes without saying that the technical scope of the present invention is not limited to the scope described in the above embodiments. It is clear to those skilled in the art that various modifications and improvements can be made to the above embodiments. In addition, it is clear from the description of the claims that forms with such modifications or improvements can also be included in the technical scope of the present invention. [Explanation of symbols]

[0058] 1. Styrene copolymer (A) 2. Biomass-derived polyethylene (B) 3. Styrenic thermoplastic elastomer (C)

Claims

1. A resin sheet comprising a layer formed from a resin composition containing a styrenic copolymer (A) containing vinyl cyanide monomer units and styrenic monomer units, a biomass-derived polyethylene (B), and a styrenic thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated diene component, the resin sheet having a film impact strength measured in accordance with ASTM-D3420 of 2.0 J / mm or more, and having an island-sea structure in which the styrenic copolymer (A) constitutes a sea portion and the polyethylene (B) and the styrenic thermoplastic elastomer (C) constitute island portions, the island portions having a sea-island structure in which the polyethylene (B) constitutes the sea portion and the styrenic thermoplastic elastomer (C) constitute the island portions.

2. 2. The resin sheet according to claim 1, comprising a layer formed from a resin composition containing, relative to 100% by mass of the total mass of the resin composition, 10 to 70% by mass of a styrene-based copolymer (A) containing a vinyl cyanide monomer unit and a styrene-based monomer unit, 5 to 70% by mass of a biomass-derived polyethylene (B), and 10 to 45% by mass of a styrene-based thermoplastic elastomer (C) containing at least one of a diene component or a hydrogenated diene component.

3. The vinyl cyanide monomer unit contained in the styrene-based copolymer (A) containing the vinyl cyanide monomer unit and the styrene-based monomer unit is 5 to 25 mass% with respect to 100 mass% of the total mass of the resin composition. The resin sheet according to claim 1 or 2.

4. The resin sheet according to any one of claims 1 to 3, wherein the content of the styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units is 10% by mass or more and less than 50% by mass.

5. The resin sheet according to any one of claims 1 to 4, wherein the styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units is an acrylonitrile-styrene copolymer.

6. The styrene-based thermoplastic elastomer (C) comprises at least one elastomer selected from the group consisting of styrene-butadiene block copolymers and hydrogenated styrene-based thermoplastic elastomers. The resin sheet according to any one of claims 1 to 5.

7. The resin sheet according to any one of claims 1 to 6, wherein the styrene-based copolymer (A) contains a recycled material of a styrene-based copolymer containing a vinyl cyanide monomer unit and a styrene-based monomer unit.

8. The resin sheet according to any one of claims 1 to 7, wherein the resin sheet has a tensile modulus of elasticity of 400 MPa or more as measured according to ASTM-D638.

9. A container comprising a molded article of the resin sheet according to any one of claims 1 to 8.

10. The container according to claim 9, which is for containing food.

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