JP2022165148A - Biomass-derived polymer-containing resin sheet and container made of molding thereof - Google Patents

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 The present invention relates to a biomass-derived polymer-containing resin sheet and a container made of the molded product.

In recent years, in order to reduce the environmental load, it has been studied to partially replace resins mainly composed of fossil fuel-derived components with biomass-derived resins as resin raw materials.

For example, a laminate film using bio-polyethylene containing plant-derived ethylene as an intermediate layer and a wrap film using both surface layers have been proposed (Patent Documents 1 and 2). In food containers, replacement with biomass-derived resins is being considered, but oil resistance is required for food containers.

JP 2014-189748 A WO2018/163835

Therefore, from the viewpoint of oil resistance, it was considered to blend acrylonitrile styrene (AS) resin, which is used for lids of food containers, with biomass-derived resin. However, according to our investigation, not only is the strength insufficient even if blended as described above, but by blending with biomass-derived resin, the oil resistance inherent in AS resin may be impaired. It became clear.

An object of the present invention is to provide a resin sheet containing a biomass-derived resin and having a certain level of film impact strength and oil resistance.

As a result of examining various means, the present inventors have found that a styrene-based copolymer containing a vinyl cyanide monomer unit and a styrene-based monomer unit, a biomass-derived polyethylene, a diene component, or a hydrogenated component of a diene By using a styrene-based thermoplastic elastomer containing at least one of, it was found that a resin sheet having a certain level of film impact strength and oil resistance can be easily obtained, and the present invention has been completed.

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

According to the present invention, it is possible to provide a resin sheet containing a biomass-derived resin and having a certain level of film impact strength and oil resistance.

1 is a TEM photograph of a resin sheet of one embodiment of the present invention. It is a figure which shows an example of the food container manufactured using the resin sheet of this invention.

An embodiment of the present invention will be described in detail below. The present invention is not limited to the following embodiments, and can be implemented with appropriate modifications within the scope that does not impair the effects of the present invention.

[First embodiment]
The resin sheet according to the first embodiment of the present invention comprises a styrene copolymer (A) containing a vinyl cyanide monomer unit and a styrene monomer unit, a biomass-derived polyethylene (B), and a diene component. or a styrenic thermoplastic elastomer (C) containing at least one hydrogenated component of a diene.

(Layer formed from resin composition)
In the present embodiment, the layer formed from the resin composition comprises a styrene-based copolymer (A) containing vinyl cyanide monomer units and styrene-based monomer units, and biomass-derived polyethylene (B). , and a styrenic thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated component of the diene.
The layer formed from the resin composition comprises a styrenic copolymer (A), a biomass-derived polyethylene (B), and a styrenic thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated component of the diene. It can be produced by putting it into an extruder, melt-kneading it, and then extruding it 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. can.

(Styrene-based copolymer (A))
In the present embodiment, the styrenic copolymer is a copolymer containing vinyl cyanide monomer units and styrenic monomer units. That is, the styrenic copolymer of the present embodiment contains, as monomer units, at least vinyl cyanide monomer units and styrenic monomer units.

Examples of the vinyl cyanide monomer constituting the vinyl cyanide monomer unit include acrylonitrile, methacrylonitrile, cyano(meth)acrylate and the like. These vinyl cyanide monomers may be used singly or in combination of two or more. Among these, acrylonitrile is preferably included as the vinyl cyanide monomer from the viewpoint of easily improving the oil resistance.
The proportion of vinyl cyanide monomer units in the styrene copolymer is preferably 10 to 40% by mass, more preferably 18 to 35% by mass, relative to the total mass of the styrene copolymer. More preferably, 24 to 32% by mass is even more preferable.
The monomer composition ratio can be obtained from 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.
・ Pyrolyzer: Nippon Analytical Industry Co., Ltd. Product name: “JPS-220”
・Thermal decomposition temperature: 590℃
・Gas chromatography: manufactured by Hewlett-Packard Product name: “5890SERIESI”
・ Column: Slightly polar column manufactured by Agilent Technologies, Inc., product name: “DB-5”
・Carrier gas: He pressure 2 psi
・Temperature condition: After holding at 50°C for 5 minutes, the temperature was raised to 250°C at 18°C/min and held at 250°C for 7 minutes ・Detection: FID
The proportion of vinyl cyanide monomer units in the resin composition is preferably 5 to 25% by mass, more preferably 5 to 12% by mass, based on the total mass of the resin composition. More preferably, it is up to 9% by mass.

Examples of styrene monomers constituting styrene monomer units include styrene, α-methylstyrene, p-methylstyrene, o-methylstyrene, m-methylstyrene, ethylstyrene, and pt-butylstyrene. etc. These styrene-based monomers may be used singly or in combination of two or more. Among these, it is preferable that styrene is included.
The proportion of styrene monomer units in the styrene copolymer is preferably 60 to 90% by mass, more preferably 65 to 82% by mass, relative to the total mass of the styrene copolymer. Preferably, 68 to 76% by mass is more preferable.

In one embodiment of the present invention, the styrenic copolymer optionally contains monomer units other than vinyl cyanide monomer units and styrenic monomer units (other monomer units (x )). Other monomeric units (x) include vinyl-based monomeric units such as (meth)acrylic acid, maleic anhydride, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl ( (Meth)acrylates such as meth)acrylate, 2-methylhexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, decyl (meth)acrylate, dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, and the like. be done. These may be used individually by 1 type, and may use 2 or more types together. In addition, "(meth)acrylic acid" means acrylic acid and methacrylic acid. Moreover, "(meth)acrylate" means acrylate and methacrylate.
When the styrenic copolymer contains other monomer units (x), it is preferably less than 10% by mass, preferably 1 to 5% by mass, based on the total mass of the styrenic copolymer. more preferred.

In one embodiment of the invention, the styrenic copolymer is an acrylonitrile-styrene copolymer. That is, the resin sheet of the present embodiment preferably contains an acrylonitrile-styrene copolymer. If the styrene-based copolymer is an acrylonitrile-styrene copolymer, the oil resistance can be more easily improved. Preferred proportions of acrylonitrile units and styrene units in the acrylonitrile-styrene copolymer are the same as the aforementioned vinyl cyanide monomer units and styrene monomer units.

The styrenic copolymer is obtained by polymerizing a monomer mixture containing a vinyl cyanide monomer and a styrenic monomer, preferably acrylonitrile and styrene. Although the polymerization method is not particularly limited, bulk continuous polymerization is preferable from the viewpoint of easily reducing odor.
In one embodiment, the styrenic copolymer may be a mixture of copolymers. In this case, after each copolymer is polymerized by an arbitrary method, a plurality of copolymers may be mixed to form a styrenic copolymer.

A well-known method can be employ|adopted as bulk continuous polymerization. Among these, it is preferable to add 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 for polymerization. Moreover, conventionally known organic peroxides, molecular weight modifiers, and the like can be added at the time of polymerization, if necessary.
The polymerization temperature is preferably 80 to 170°C, more preferably 100 to 160°C.

The weight average molecular weight (Mw) of the styrenic copolymer is preferably 50,000 to 250,000, more preferably 100,000 to 200,000. If the copolymer (A) has an Mw of 50,000 to 250,000, the strength of the resin sheet tends to be good. In addition, the film formability tends to be good. In addition, polydispersity (Mw/Mn), which is the ratio of Mw and number average molecular weight (Mn) of the styrene copolymer, is preferably 2.0 to 3.0, and is 2.1 to 2.5. is more preferable. If the polydispersity of the styrene-based copolymer is 2.0 to 3.0, the strength of the resin sheet is unlikely to decrease, and the oil resistance tends to be better. In addition, Mw and Mn of a styrenic copolymer point out the value calculated by polystyrene conversion by GPC (gel permeation chromatography). Specifically, it refers to the value measured under the following conditions.
<Method for measuring Mw and Mn of styrene copolymer>
Apparatus: manufactured by Shodex Co., Ltd., product name: “Shodex SYSTEM-21”
Column: PLgel MIXED-B
Measurement temperature: 40°C
Solvent: Tetrahydrofuran Flow rate: 1.0 mL/min Detection method: RI
Sample concentration: 0.2% by mass
Injection volume: 100 μL
Calibration curve: standard polystyrene (manufactured by Polymer Laboratories)

The content of the styrenic copolymer in the resin sheet is preferably 10 to 70% by mass, more preferably 10 to 50% by mass, particularly preferably 15 to 45% by mass, relative to the total mass of the resin sheet. When the content of the styrene-based copolymer is within the above range, it becomes easy to maintain high oil resistance and improve impact strength. In addition, the "total mass of the resin sheet" means the total mass of the resin composition forming the resin sheet.

(Biomass-derived polyethylene (B))
In the present embodiment, the biomass-derived polyethylene may be polyethylene containing biomass-derived ethylene as a monomer component, and may contain a petroleum-derived monomer component as a copolymerization component. For example, biomass-derived low-density polyethylene or plant-derived linear low-density polyethylene.
Here, biomass means reusable organic resources (excluding fossil fuels such as petroleum) born from animals and plants. Includes paper, animal carcasses and manure, and plankton.

Biomass-derived polyethylene means an ethylene homopolymer produced using biomass as a raw material, or a copolymer of ethylene produced using biomass as a raw material and an α-olefin. Such polymers can be synthesized by known production methods.

The α-olefin is preferably at least one or more compounds selected from the group consisting of α-olefins having 3 to 20 carbon atoms, α-olefins having 4 to 6 carbon atoms, or these A mixture is more preferred. The group consisting of α-olefins having 3 to 20 carbon atoms includes, 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 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 with respect to a total of 100 parts by mass of the plant-derived ethylene and the α-olefin. As the α-olefin, a petroleum-derived α-olefin may be used.

In one embodiment of the present invention, the biomass-derived polyethylene preferably has a biobased content (%) of 80 to 100%, more preferably 82 to 98%, as measured according to ASTM D6866. When the degree of bio-based content is 80% or more, it is possible to reduce _CO2 by about 70-74% compared to petroleum-derived polyethylene, effectively using exhaustible resources and significantly reducing the amount of _CO2 that causes greenhouse gases. can be reduced to

The density of biomass-derived polyethylene is preferably 0.90 to 0.98 g/cm ³ , more preferably 0.95 to 0.97 g/cm ³ .
In addition, the melt flow rate (MFR) of biomass-derived polyethylene is 0.1 under the measurement conditions of 190 ° C. and 2.16 kgf from the viewpoint of extrusion processability, biaxial stretchability, and thickness uniformity in thermoforming. It is preferably in the range of ~3.0 g/10 min, more preferably in the range of 0.3 to 1.0 g/10 min.

In the present embodiment, biomass-derived polyethylene that is suitably used includes, for example, the trade name “SGF4960” (density 0.961 g/cm ³ , MFR 0.34 g/10 min, bio-based degree 96%), the trade name “ SBC818" (density 0.918 g/cm ³ , MFR 8.3 g/10 min, bio-based content 95%), trade name "STN7006" (density 0.924 g/cm ³ , MFR 0.6 g/10 min, bio-based content 95 %), trade name “SPB681” (density 0.922 g/cm ³ , MFR 3.8 g/10 min, bio-based content 95%), a product obtained using ethylene and an α-olefin having 4 carbon atoms Name “SLL118” (density 0.916 g/cm ³ , MFR 1.0 g/10 min, bio-based degree 87%), “SLL118/21” (density 0.918 g/cm ³ , MFR 1.0 g/10 min, bio-based degree 95%), and trade name “SLH118” (density 0.916 g/cm ³ , MFR 1.0 g /10 minutes, bio-based content 84%) (both manufactured by Braskem).

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

(Styrenic thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated component of a diene)
In the present embodiment, the styrenic thermoplastic elastomer containing at least one of a diene component and a hydrogenated diene component means a styrenic thermoplastic elastomer produced using a diene as a raw material or a hydrogenated product thereof. . The styrenic thermoplastic elastomer does not have to act as a compatibilizer. Here, the diene component means a diene-derived monomer unit constituting a styrene-based thermoplastic elastomer. The hydrogenated diene component means a hydrogenated diene-derived monomer unit constituting a styrene-based thermoplastic elastomer. Examples of styrene thermoplastic elastomers containing at least one of a diene component and a hydrogenated diene component include styrene/butadiene (SB), styrene/isoprene (SI), styrene/butadiene/butylene (SBB), styrene/butadiene/ Block copolymers such as isoprene (SBI), styrene/butadiene/styrene (SBS), styrene/butadiene/butylene/styrene (SBBS), styrene/isoprene/styrene (SIS) and styrene/butadiene/isoprene/styrene (SBIS) , and hydrogenated block copolymers thereof.
In the present embodiment, it is possible to use only one of the above-described styrene-based thermoplastic elastomers, or to use a combination of multiple types.

The weight average molecular weight (Mw) of the styrenic thermoplastic elastomer is preferably 100,000 to 200,000, more preferably 120,000 to 180,000. If the Mw of the styrenic thermoplastic elastomer is 100,000 to 200,000, the strength tends to be good. In addition, the workability 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 styrenic copolymer (A) described above.

The content of the styrene-based thermoplastic elastomer in the resin sheet is preferably 10-45% by mass, more preferably 10-35% by mass, and particularly preferably 10-30% by mass, relative to the total mass of the resin sheet. If the content of the styrene-based thermoplastic elastomer is within the above range, the film impact strength of the resin sheet is likely to be improved.

(other ingredients)
In one embodiment of the present invention, the resin sheet comprises a styrene copolymer (A), a biomass-derived polyethylene (B), and a styrene thermoplastic elastomer (C ) may contain other resins. Examples of other resins include rubber-reinforced resins such as high-impact polystyrene, ABS resins, AES resins, and styrene-butadiene block copolymer resins. When the resin sheet contains other resins, it is preferably less than 5% by mass with respect to the total mass of the resin sheet.

If necessary, the resin sheet may contain other additives such as ultraviolet absorbers, light stabilizers, antioxidants, lubricants, plasticizers, colorants, antistatic agents, flame retardants, mineral oils, glass fibers, and carbon fibers. , reinforcing fibers such as aramid fibers, fillers such as talc, silica, mica, calcium carbonate, and the like. These may be used individually by 1 type, and may use 2 or more types together.

Examples of UV absorbers 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'-hydroxy Phenyl)-5-chlorobenzotriazole, 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-benzotriazol-2-yl)phenol] and other benzotriazole UV absorbers; 2-ethoxy-2'-ethyl oxalic acid bisanilide, 2-ethoxy-5-t-butyl-2' -Oxalic acid anilide UV absorbers such as ethyl bisanilide oxalate, 2-ethoxy-4'-isodecylphenyl bisanilide oxalate; 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, 2-hydroxy-4- Benzophenone UV absorbers such as methoxy-2′-carboxybenzophenone; Salicylic acid UV absorbers such as phenyl salicylate, pt-butylphenyl salicylate and p-octylphenyl salicylate; 2-ethylhexyl- Cyanoacrylate UV absorbers such as 2-cyano-3,3'-diphenylacrylate and ethyl-2-cyano-3,3'-diphenylacrylate; rutile type titanium oxide, anatase type Examples include titanium oxide UV stabilizers such as titanium oxide, alumina, silica, silane coupling agents, and titanium oxide treated with a surface treatment agent such as a titanium coupling agent. These may be used individually by 1 type, and may use 2 or more types together.

Examples of light stabilizers include bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate and bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate. , dimethyl succinate/1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine polycondensate, 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 and the like. These may be used individually by 1 type, and may use 2 or more types together.

Examples of antioxidants 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, pentaerythrityltetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propione -to], 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 phenolic antioxidants; ditridecyl-3,3'-thiodipropionate, Sulfur antioxidants such as dilauryl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate, distearyl-3,3'-thiodipropionate, and dioctyl-3,3'-thiodipropionate Agent; 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-t-butyl-4-methylphenyl)pentaerythritol diphosphite, dinonylphenyloctyl Phosphonite, Tetrakis(2,4-di-t-butylphenyl)1,4-phenylene-di-phosphonite, Tetrakis(2,4-di-t-butylphenyl)4,4'-biphenylene-di-phosphonite , 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene and other phosphorous antioxidants. These may be used individually by 1 type, and may use 2 or more types together.

(resin sheet)
In the present embodiment, the resin sheet comprises a styrene copolymer (A) containing vinyl cyanide monomer units and styrene monomer units, a biomass-derived polyethylene (B), and a diene component or a diene. and a layer formed from a resin composition containing a styrene-based thermoplastic elastomer (C) containing at least one of hydrogenated components. In one embodiment of the present invention, the resin sheet consists of a layer formed from the resin composition described above. In another embodiment, the resin sheet may be a laminated sheet including one or two layers formed from another thermoplastic resin composition in addition to the layer formed from the resin composition described above.
The film impact strength of the resin sheet measured according to ASTM-D3420 is 2.0 J/mm or more. Moreover, it is preferably 3.0 J/mm or more, more preferably 4.0 J/mm or more. If the film impact strength of the resin sheet is 2.0 J/mm or more, the strength can be used as a food storage container.

In this embodiment, the resin sheet has oil resistance. Here, having oil resistance means an evaluation of at least Δ or higher in the oil resistance test in the following examples. More preferably, it means an evaluation of ◯.

In this embodiment, the resin sheet has heat resistance. Here, having heat resistance means that the evaluation is at least fair or better in the heat resistance test in the following examples. More preferably, it means a good evaluation.

In one embodiment of the present invention, the tensile modulus value of the resin sheet measured according to ASTM-D638 is 400 MPa or more in both MD and TD directions. Preferably, the lower tensile modulus in the MD direction and the TD direction is 700 MPa or more, more preferably the lower tensile modulus in the MD direction and the TD direction 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 storing food, and practical use is possible. Also, the ratio of tensile elastic moduli in the MD direction and the TD direction (MD/TD) is preferably 0.7 to 1.8, more preferably 0.8 to 1.7.

In one embodiment of the present invention, the thickness of the resin sheet is not particularly limited as long as it has the effect of the present invention. .50 mm.

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

[Method for manufacturing resin sheet]
As a method for producing a resin sheet in one embodiment of the present invention, a styrene-based thermoplastic resin containing at least one of a styrene-based copolymer (A), a biomass-derived polyethylene (B), and a diene component or a hydrogenated component of a diene is used. The elastomer (C) is put into an extruder, melt-kneaded, and then extruded through 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, in consideration of the suitable thickness as a food storage container.
When the resin sheet is a laminated sheet, a general method can be used. A method of obtaining a laminated sheet using a block and a T-die and a method of obtaining a laminated sheet using a multi-manifold die can be mentioned.

[container]
In this embodiment, the resin sheet can be made into a container by a known technique. For example, the container can be formed by a method such as vacuum molding or pressure molding. Specifically, it is possible to obtain a molded article with good mold reproducibility by hot plate heating type pressure molding. The "container" in the present invention includes not only the main container for storing the contents, but also a lid material that can be fitted with the main container.
Since the container of the present embodiment is excellent in heat resistance and oil resistance, it can be suitably used as a container for storing food, particularly as a container for storing food heated in a microwave oven. Needless to say, the use of the container obtained from the resin sheet of the present embodiment is not limited to food storage.

EXAMPLES The present invention will be described in more detail with reference to examples below, but the interpretation of the present invention is not limited by these examples.

Materials used in Examples and Comparative Examples are as follows.
・ Styrene-based copolymer (A-1) acrylonitrile-styrene copolymer: "AS-EXS" (manufactured by Denka Co., Ltd.)
(A-2) Regenerated granulated acrylonitrile-styrene copolymer (A-3) High-impact polystyrene: "H850N" (manufactured by Toyo Styrene Co., Ltd.)
Biomass-derived polyethylene (B) Biomass polyethylene (HDPE): "SGF4960" (density 0.961 g/cm ³ , MFR 0.34 g/10 min, bio-based content 96%, manufactured by Braskem)
・ Styrene-based thermoplastic elastomer (C-1) Styrene-based thermoplastic elastomer (SBS): "TR2000" (manufactured by JSR, polybutadiene content 60% by mass)
(C-2) Styrene-based thermoplastic elastomer (SBC): "220M" (manufactured by Denka, polybutadiene content: 28% by mass)
(C-3) Styrene-based thermoplastic elastomer (SEBS): "H1041" (manufactured by Asahi Kasei Corporation, amount of hydrogenated diene component: 70% by mass)

(Production of regenerated granulated acrylonitrile-styrene copolymer (A-2))
After pulverizing scraps, etc. generated from a molding factory where stretched sheets of acrylonitrile-styrene copolymer (“AS-EXS” manufactured by Denka) were formed, they are recycled with a twin-screw extruder at a cylinder temperature of 240°C. Granulation was carried out to obtain regenerated granulated resin (A-2). The repellet obtained had an MFR of 2.0 g/min at 200° C. under a load of 5 kg.

(Example 1)
With respect to the total mass of the resin composition, 20% by mass of a styrene copolymer (A-1), 70% by mass of biomass-derived polyethylene (B), and 10% by mass of a styrene thermoplastic elastomer (C-1), Using a single-screw extruder with a screw diameter of 40 mm, the mixture was melt-kneaded at 230° C. and 70 rpm, 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 resulting single layer sheet were evaluated by the following methods.
When the viscoelastic spectrum of the obtained resin was confirmed, peaks were observed for each of the styrene copolymer (A-1) and the biomass-derived polyethylene (B) (not shown). 1 is a TEM photograph of the resin sheet of Example 1. FIG. As can be seen from FIG. 1, it has become clear that the structure has a sea-island structure. TEM imaging was performed under the following conditions. From the above, it was clarified that the styrene-based thermoplastic elastomer does not act as a compatibilizer.
<TEM imaging conditions>
After staining the sheets in MD and TD with 4% OsO ₄ aqueous solution, they were sectioned with a cryomicrotome. This thin section was vapor-stained with a 0.5% RuO ₄ aqueous solution and observed with a TEM.
・Apparatus JEM-2100 manufactured by JEOL (transmission electron microscope)
・Conditions Accelerating voltage 120 kV

<Measurement of film impact strength>
It was measured according to ASTM-D3420 using a film impact tester (manufactured by Yasuda Seiki). Specifically, a single-layer sheet having a thickness of 0.43 mm was cut into a size of 70 mm×70 mm to prepare and evaluate a measurement sample. Moreover, it evaluated along the following evaluation criteria.
(Evaluation criteria)
A: Impact strength of 3.0 J/mm or more B: Impact strength of 2.0 J/mm or more and less than 3.0 J/mm C: Impact strength of less than 2.0 J/mm The elastic modulus of the sheet is low and impact strength If it was so soft that it could not be punched out during measurement, it could not be measured and was judged as unacceptable.

<Measurement of tensile modulus>
It was measured according to ASTM D638 using an autograph (AGS-X manufactured by Shimadzu Corporation). Specifically, a single-layer sheet having a thickness of 0.43 mm was cut out in the MD direction and the TD direction in the shape of a dumbbell No. 1, and a measurement sample was prepared and evaluated. Moreover, it evaluated according to the following evaluation criteria.
(Evaluation criteria)
A: Lower tensile modulus in MD direction and TD direction is 700 MPa or more B: Lower tensile modulus in MD direction and TD direction is 400 MPa or more and less than 700 MPa C: Lower tensile modulus in MD direction and TD direction is less than 400MPa

<Oil resistance test>
It was evaluated by the constant strain method. Specifically, a single-layer sheet having a thickness of 0.43 mm was cut into a size of 300 mm×15 mm and elongated in the MD direction. 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 × 10 cm piece of gauze impregnated with mayonnaise (manufactured by Kewpie) was attached to the strained portion. After standing for 24 hours, the surface of the adhered portion was observed. Moreover, it evaluated along the following evaluation criteria. Those with an evaluation of Δ or higher were considered to have oil resistance.
〇: No change △: Slight whitening ×: Significant whitening and cracking

<Heat resistance test>
A single-layer sheet with a thickness of 0.43 mm is processed using a small vacuum pressure air single shot molding machine FVS-500 (manufactured by Wakisaka Engineering Co., Ltd.), a heater temperature of 500 ° C., a heating time of 10 seconds, a mold temperature of 70 ° C., and a mold holding time of 15 seconds. 150×130×20 mm in height, placed in a hot air dryer set at 110° C. for 30 minutes, and observed for deformation of the container. Moreover, it evaluated along the following evaluation criteria. Those with an evaluation of acceptable or higher were regarded as having heat resistance.
Good: No deformation Acceptable: Slightly non-deformable: Large deformation

(Examples 2 to 7, Comparative Examples 1 to 6)
The same method as in Example 1 except that the types and blending amounts of the styrene copolymer (A), the biomass-derived polyethylene (B), and the styrene thermoplastic elastomer (C) were changed as shown in Table 1. got a seat at. In the same manner 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. Table 1 shows the results.

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, impact-resistant polystyrene was used, and although there was no problem in terms of film impact strength, it was shown that oil resistance was not sufficient.
In Comparative Example 2, a resin sheet was produced using only an acrylonitrile-styrene copolymer and biomass-derived polyethylene. It was shown that the oil resistance inherent in the polymer is impaired.
The resin sheet of Comparative Example 3 was evaluated as x in the oil resistance test. It is presumed that this is due to increased distortion.
In addition, (A-2) the evaluation of the resin sheet using the regenerated granulated acrylonitrile-styrene copolymer was performed using (A-1) acrylonitrile-styrene copolymer: "AS-EXS" (manufactured by Denka Co., Ltd.). It was shown to be equivalent to the evaluation of the resin sheet used.

Although the present invention has been described 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 obvious to those skilled in the art that various modifications or improvements can be made to the above embodiments. Moreover, it is clear from the description of the scope of the claims that the forms with such modifications or improvements can also be included in the technical scope of the present invention.

1 Styrene-based copolymer (A)
2 Biomass-derived polyethylene (B)
3 Styrene-based thermoplastic elastomer (C)

Claims (10)

A styrene copolymer (A) containing a vinyl cyanide monomer unit and a styrene monomer unit, a biomass-derived polyethylene (B), and a styrene containing at least one of a diene component and a hydrogenated component of the diene A resin sheet comprising a layer formed from a resin composition containing a thermoplastic elastomer (C), and having a film impact strength of 2.0 J/mm or more as measured according to ASTM-D3420. With respect to 100% by mass of the total mass of the resin composition, 10 to 70% by mass of a styrene copolymer (A) containing vinyl cyanide monomer units and styrene monomer units, and biomass-derived polyethylene (B ) 5 to 70% by mass and 10 to 45% by mass of a styrenic thermoplastic elastomer (C) containing at least one of a diene component and a hydrogenated component of the diene, and a layer formed from a resin composition containing The resin sheet according to claim 1. 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% with respect to the total mass of 100% by mass of the resin composition. 3. The resin sheet according to claim 1 or 2, which is up to 25% by mass. 4. Any one of claims 1 to 3, wherein the content of the styrenic copolymer (A) containing vinyl cyanide monomer units and styrenic monomer units is 10% by mass or more and less than 50% by mass. The resin sheet described in . The resin according to any one of claims 1 to 4, wherein the styrenic copolymer (A) containing vinyl cyanide monomer units and styrenic monomer units is an acrylonitrile-styrene copolymer. sheet. 6. Any one of claims 1 to 5, wherein the styrenic thermoplastic elastomer (C) comprises at least one elastomer selected from the group consisting of a styrene-butadiene block copolymer and a hydrogenated styrenic thermoplastic elastomer. The resin sheet according to the item. 7. The styrenic copolymer (A) according to any one of claims 1 to 6, wherein the styrenic copolymer (A) contains a recycled styrenic copolymer containing vinyl cyanide monomer units and styrenic monomer units. The resin sheet described. 8. The resin sheet according to any one of claims 1 to 7, wherein the resin sheet has a tensile modulus value of 400 MPa or more as measured according to ASTM-D638. A container comprising the molded resin sheet according to any one of claims 1 to 8. 10. The container according to claim 9, which is for food storage.

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