Sheet and container body

Abstract

To provide a small sheet that resists heat deformation and has small environmental load.SOLUTION: A sheet has at least one resin composition layer predominantly composed of styrenic resin. The resin composition layer further contains polylactic acid of 10-42 mass% and acrylic resin of 1-7 mass%.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a sheet and a container body. [Background technology]

[0002] Containers made of polystyrene resins are widely used as containers for selling foodstuffs, processed foods, etc. in stores such as supermarkets, convenience stores, department stores, and bento shops. In particular, containers made of extruded polystyrene resin sheets formed by thermoforming, vacuum forming, etc. are widely used because they are lightweight, have high thermal insulation properties, are inexpensive, etc.

[0003] However, polystyrene resins have poor oil resistance and are prone to thermal deformation due to the oil in foods.

[0004] Therefore, various studies have been made to improve the oil resistance of polystyrene resins, such as a method of blending an olefin resin, such as polyethylene or polypropylene, with a polystyrene resin (see, for example, Patent Documents 1 to 3). Also, a molded article has been proposed in which a styrene-based block copolymer rubber and a styrene-acrylonitrile copolymer are blended with polystyrene (Patent Document 4). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 5-186660 [Patent Document 2] Japanese Patent Application Publication No. 6-192493 [Patent Document 3] JP 2000-186177 A [Patent Document 4] JP 2010-222448 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, in resin compositions consisting of polystyrene-based resins and olefin-based resins as in Patent Documents 1 to 3, the compatibility between the two resins is poor, and simple blends are not practical because they suffer from reduced mechanical strength and layer peeling. In order to improve compatibility, styrene-butadiene block copolymer rubber or its hydrogenated polymer, styrene-isoprene block copolymer or its hydrogenated polymer, or ethylene-octene copolymer, etc. are further added, but the results are not fully satisfactory.

[0007] Furthermore, in a resin composition consisting of a polystyrene resin and an olefin resin, it is necessary to knead a considerable amount of the olefin resin in order to improve the oil resistance, which may result in a loss of the rigidity and heat resistance that are characteristic of the polystyrene resin.

[0008] The molded article of Patent Document 4 lacks heat resistance, and there is a problem of thermal deformation of the container, particularly when it is heated using a high-output microwave oven, which has become the standard in convenience stores in recent years.

[0009] In addition, in recent years, there has been a demand to reduce carbon dioxide emissions in order to curb global warming, and polylactic acid has been attracting attention as one of the "carbon-neutral" polyester resins that apparently do not emit carbon dioxide. However, polylactic acid is not very practical in terms of durability. Therefore, if polylactic acid can be effectively utilized by alloying it with styrene-based resins, it would be very significant from the perspective of reducing the environmental burden.

[0010] In view of the above, an object of the present invention is to provide a sheet that is less susceptible to thermal deformation and has a small environmental impact. [Means for solving the problem]

[0011] As a result of intensive research to solve the above problems, the inventors have found that by making the main component of the resin composition layer a styrene-based resin and containing a specific proportion of polylactic acid and a specific acrylic-based resin, the polylactic acid exerts an effect of reducing the environmental load, and the acrylic resin prevents oil from coming into direct contact with the styrene-based resin, thereby reducing thermal deformation caused by oil, and have completed the present invention. That is, the present invention is as follows.

[0012] [1] A sheet comprising at least one resin composition layer containing a styrene-based resin as a main component, the resin composition layer further comprising 10 to 42 mass % of polylactic acid and 1 to 7 mass % of an acrylic resin. [2] The sheet according to [1], wherein the acrylic resin has a peak top molecular weight (Mp) of 1,000,000 to 6,000,000 as determined by gel permeation chromatography (GPC). [3] The sheet according to [1] or [2], wherein the styrene-based resin is a rubber-modified polystyrene. [4] A container body comprising a molded product of the sheet according to any one of [1] to [3]. [5] The container body described in [4], which is for storing food. Effect of the Invention

[0013] According to the present invention, a sheet with little thermal deformation and small environmental impact can be provided. In addition to the above, according to the present invention, a sheet with improved impact resistance can be provided. Furthermore, the sheet of the present invention can be made to have a pearl-like texture by adjusting the peak top molecular weight (Mp) of the acrylic resin, for example, and can impart a luxurious feel when used as a container body. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, an embodiment of the present invention will be described in detail. Sheet The sheet according to the present embodiment includes at least one resin composition layer containing a styrene resin as a main component, and the resin composition layer further contains 10 to 42 mass % of polylactic acid and 1 to 7 mass % of an acrylic resin. The peak top molecular weight (Mp) of the acrylic resin obtained by gel permeation chromatography (GPC) is preferably 1 to 6 million.

[0015] In this specification, the term "main component" refers to the component that has the largest mass ratio among the constituent components. For example, when a resin composition layer containing a styrene-based resin, polylactic acid, and an acrylic resin is described as "containing a styrene-based resin as a main component," this means that the mass ratio of the styrene-based resin is the largest among the above three components. The resin composition and the like will be described below.

[0016] (1) Resin composition layer (styrene resin) The styrene-based resin is obtained by polymerizing a monomer of an aromatic vinyl compound. The aromatic vinyl compound monomer may be a known one such as styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, or 2,4-dimethylstyrene, but is preferably styrene. These monomers may be used alone or in combination. In addition, monomers such as acrylonitrile, (meth)acrylic acid, (meth)acrylic acid esters, and maleic anhydride that are copolymerizable with these monomers may be added and polymerized as long as they do not impair the performance of the styrene-based resin.

[0017] The styrene resin may be modified with a conjugated diene rubber polymer as required. Examples of the conjugated diene rubber polymer used for rubber modification include polybutadiene, random or block copolymer of styrene-butadiene, polyisoprene, random, block or graft copolymer of styrene-isoprene, ethylene-propylene rubber, ethylene-propylene-diene rubber, etc., and polybutadiene, random or block copolymer of styrene-butadiene are particularly preferred. These may also be partially hydrogenated.

[0018] Examples of such styrene-based resins include polystyrene (GPPS), rubber-modified polystyrene (HIPS), ABS resin (acrylonitrile-butadiene-styrene copolymer), AS resin (acrylonitrile-styrene copolymer), MS resin (methyl methacrylate-styrene copolymer), AAS resin (acrylonitrile-acrylic rubber-styrene copolymer), AES resin (acrylonitrile-ethylene propylene-styrene copolymer), etc. Among these, rubber-modified polystyrene is preferred because it can increase the impact resistance of the resin composition.

[0019] The molecular weight of the styrene resin is preferably a peak top molecular weight (Mp) of 10,000 to 500,000, and more preferably 30,000 to 400,000. When the peak top molecular weight (Mp) is 10,000 to 500,000, a resin composition having an excellent balance between fluidity and heat resistance can be obtained. In this specification, the peak top molecular weight (Mp) is calculated as a polystyrene-equivalent molecular weight by gel permeation chromatography (GPC) measurement, calculating the molecular weight at each elution time from the elution curve of monodisperse polystyrene by the following method. Model: Showa Denko Co., Ltd. Shodex GPC-101 Column: Polymer Laboratories PLgel 10μm MIXED-B Mobile phase: Tetrahydrofuran Flow rate: 1.0ml / min Sample concentration: 0.2% by mass Injection volume: 100μl Temperature: oven 40℃, injection port 35℃, detector 35℃ Detector: Differential refractometer

[0020] Here, the peak top molecular weight (Mp) is determined from the position of the apex of the peak in the molecular weight distribution obtained by the above-mentioned gel permeation chromatography (GPC). When there are multiple peaks in this GPC, the peak top molecular weight (Mp) is the molecular weight of the peak corresponding to the peak having the largest area ratio.

[0021] The content of the styrene-based resin in the first resin composition layer is preferably 55 to 89% by mass, and more preferably 65 to 80% by mass. When the content is 55 to 89%, it is possible to achieve both oil resistance and impact resistance.

[0022] (Polylactic acid) As the polylactic acid, it is preferable to use poly(L-lactic acid). From the viewpoint of reducing carbon dioxide emissions, it is preferable to use plant-derived raw materials.

[0023] When the polylactic acid is poly(L-lactic acid), the crystallization rate varies depending on the ratio of the D-lactic acid component. Considering the moldability when forming a molded article such as a food container, the ratio of the D-lactic acid component is preferably 0.01 to 5.0 mol%, and more preferably 0.01 to 1.5 mol%.

[0024] The molecular weight of the polylactic acid is preferably a peak top molecular weight (Mp) of 50,000 to 400,000, more preferably 100,000 to 300,000. If the peak top molecular weight (Mp) is 50,000 or more, the mechanical properties and heat resistance of the molded article will be good, and if it is 400,000 or less, the moldability of the molded article can be maintained good.

[0025] The content of polylactic acid in the first resin composition layer is 10 to 42% by mass, preferably 15 to 35% by mass, and more preferably 20 to 30% by mass. If the content of polylactic acid is less than 10% by mass, the heat distortion resistance decreases. If it exceeds 40% by mass, the impact resistance decreases.

[0026] (Acrylic resin) The acrylic resin is obtained by polymerization of acrylic monomers and the like. Here, as described above, the peak top molecular weight (Mp) of the acrylic resin is preferably 1 million to 6 million, more preferably 1.5 million to 4.5 million, and even more preferably 3 million to 4.5 million. If the peak top molecular weight (Mp) is less than 1 million, the luxurious feel may be lost. If it exceeds 6 million, moldability may be deteriorated, making film formation difficult.

[0027] The type of acrylic monomer is not particularly limited as long as it does not impair the effects of the present invention. For example, homopolymers of acrylate monomers such as methyl acrylate, ethyl acrylate, isopropyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, benzyl acrylate, cyclohexyl acrylate, phenyl acrylate, and chloroethyl acrylate, and homopolymers of methacrylate monomers such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and chloroethyl methacrylate, and copolymers obtained by copolymerizing two or more of these monomers can be used.

[0028] The structural unit of the acrylic resin is mainly composed of methyl methacrylate units, the content of which is preferably 60% by mass or more, and more preferably 70% by mass or more.

[0029] Examples of the polymerization method of the acrylic resin include known polymerization methods such as emulsion polymerization, soap-free emulsion polymerization, fine suspension polymerization, suspension polymerization, bulk polymerization, and solution polymerization. Among these polymerization methods, emulsion polymerization is preferred because it is easy to produce a high molecular weight substance. Known emulsifiers can be used as the emulsifier when producing the acrylic resin by emulsion polymerization. Examples include anionic emulsifiers, nonionic emulsifiers, polymeric emulsifiers, and reactive emulsifiers having a radically polymerizable unsaturated double bond in the molecule.

[0030] The acrylic resin may be one obtained by adding and polymerizing, in addition to the above-mentioned acrylic monomers, a vinyl monomer copolymerizable therewith, so long as the effect of the present invention is not impaired. For example, monomers such as α-olefins, vinyl aromatics, unsaturated nitriles, unsaturated carboxylic acids or esters thereof, and polyunsaturated compounds such as ethylene glycol di(meth)acrylate may be added.

[0031] The content of the acrylic resin in the resin composition layer is 1 to 7% by mass, preferably 2 to 4% by mass, and more preferably 2.5 to 3.5% by mass. If the content of the acrylic resin is less than 1% by mass, the luxurious feel is reduced. If the content of the acrylic resin is more than 7% by mass, the moldability is deteriorated, making film formation difficult.

[0032] Furthermore, the resin composition layer according to this embodiment may contain additives, such as plasticizers, spreading agents, solvents, UV absorbers, antioxidants, antiaging agents, light stabilizers, antistatic agents, colorants, dyes and pigments, fillers, color inhibitors, reinforcing agents, compatibilizers, crystallization accelerators, flame retardants, and flame retardant assistants, within the scope of the invention.

[0033] Since the sheet according to the present embodiment contains an acrylic resin in the resin composition layer, it has a good gloss and can give a luxurious feel when used as a container body. Therefore, the sheet is preferably a single-layer structure composed of only the resin composition layer, but other resin composition layers may be laminated thereon as long as the object of the present invention is not impaired.

[0034] In this case, the other resin composition layer is preferably also mainly composed of a styrene-based resin, and the styrene-based resin is preferably a rubber-modified styrene-based resin. This can improve the impact resistance of the sheet. In addition, it is preferable that the other resin composition layer contains polylactic acid and an acrylic resin.

[0035] That is, the sheet may include two or more resin composition layers containing a styrene resin as a main component, and each resin composition layer may contain 10 to 42 mass% of polylactic acid and 1 to 7 mass% of acrylic resin in the same or different blends. The peak top molecular weight (Mp) of the acrylic resin is preferably 1 to 6 million.

[0036] In the above case, the preferred specific examples and blending of the styrene-based resin, polylactic acid and acrylic-based resin are the same as those in the first resin composition layer, but it is not necessary to have the same composition as the first resin composition layer.

[0037] The sheet according to the present embodiment may be, for example, a two-layer multilayer sheet having a second resin composition layer on a first resin composition layer, or a three-layer multilayer sheet having a second resin composition layer and a third resin composition layer in this order on a first resin composition layer, where the first resin composition is the resin composition layer according to the present embodiment described above.

[0038] In the case of a two-layer multilayer sheet, the second resin composition layer may have a configuration such as (a) a configuration containing a styrene-based resin and not containing polylactic acid and an acrylic-based resin, (b) a configuration containing a styrene-based resin and polylactic acid and not containing an acrylic-based resin, (c) a configuration containing a styrene-based resin and an acrylic-based resin and not containing polylactic acid, or (c) a configuration containing a styrene-based resin, polylactic acid, and an acrylic resin. From the viewpoint of improving the impact resistance of the sheet, however, the configuration (a) containing a styrene-based resin and not containing polylactic acid and an acrylic resin is preferred.

[0039] In the case of a two-layered multilayer sheet, the thickness ratio (T2 / T1) between the thickness T1 of the first resin composition layer and the thickness T2 of the second resin composition layer is preferably 90 / 10 to 50 / 50, and more preferably 85 / 15 to 75 / 25. By having the thickness ratio (T2 / T1) of 90 / 10 to 50 / 50, it is possible to produce a sheet having impact resistance without impairing the appearance of the sheet.

[0040] In the case of a three-layer multilayer sheet, the second resin composition layer may be (a) a composition containing a styrene-based resin and not containing polylactic acid or an acrylic-based resin, (b) a composition containing a styrene-based resin and polylactic acid and not containing an acrylic-based resin, (c) a composition containing a styrene-based resin and an acrylic-based resin and not containing polylactic acid, or (d) a composition containing a styrene-based resin, polylactic acid, and an acrylic resin. In addition, the third resin composition layer may have a configuration such as (a) a configuration containing a styrene-based resin and not containing polylactic acid and an acrylic-based resin, (b) a configuration containing a styrene-based resin and polylactic acid and not containing an acrylic-based resin, (c) a configuration containing a styrene-based resin and an acrylic-based resin and not containing polylactic acid, or (d) a configuration containing a styrene-based resin, polylactic acid, and an acrylic resin.

[0041] From the viewpoint of maintaining the impact resistance of the sheet and improving the biomass content, it is preferable that the second resin composition layer is (a) a composition containing a styrene-based resin and not containing polylactic acid and an acrylic-based resin, or (d) a composition containing a styrene-based resin, polylactic acid, and an acrylic-based resin, and the third resin composition layer is (d) a composition containing a styrene-based resin, polylactic acid, and an acrylic resin.

[0042] In the case of a three-layered multilayer sheet, the thickness ratio (T2 / T1) of the thickness T1 of the first resin composition layer to the thickness T2 of the second resin composition layer is preferably 80 / 10 to 50 / 25, and more preferably 70 / 15 to 50 / 25. By setting the thickness ratio (T2 / T1) to 80 / 10 to 50 / 25, it is possible to produce a sheet having impact resistance without impairing the appearance of the sheet. Furthermore, the thickness ratio (T3 / T1) of the thickness T1 of the first resin composition layer to the thickness T3 of the third resin composition layer is preferably 10 / 25 to 25 / 25, and more preferably 15 / 25 to 25 / 25. By having the thickness ratio (T3 / T1) of 10 / 25 to 25 / 25, it is possible to produce a sheet having impact resistance without impairing the appearance of the sheet.

[0043] In the sheet (including the multilayer sheet) according to the present embodiment as described above, the thickness is preferably 0.1 to 3.0 mm, and more preferably 0.2 to 1.5 mm. When the total thickness is 0.1 to 3.0 mm, a flexible sheet can be produced without insufficient absolute strength.

[0044] Furthermore, the sheet according to this embodiment (even the multilayer sheet) may contain other additives, such as plasticizers, spreading agents, solvents, UV absorbers, antioxidants, antiaging agents, light stabilizers, antistatic agents, colorants, dyes and pigments, fillers, color inhibitors, reinforcing agents, compatibilizers, crystallization promoters, flame retardants, and flame retardant assistants, provided such additives do not impair the object of the present invention.

[0045] [Method of manufacturing the sheet] The sheet according to the present embodiment can be produced by extruding a resin composition layer containing a styrene-based resin as a main component and a specific proportion of polylactic acid and a specific acrylic resin in a die. Details of the styrene-based resin, polylactic acid, acrylic resin, etc. are as described above.

[0046] Here, the resin composition for forming the resin composition layer can be produced by premixing various raw materials including styrene-based resins using a mixing device such as a mixer-type mixer, a V-type blender, and a tumbler-type mixer, and then melt-kneading the mixture. The melt-kneading device is not particularly limited, but examples thereof include a Banbury mixer, a kneader, a roll, a single-screw extruder, a special single-screw extruder, and a twin-screw extruder. Furthermore, other raw materials and additives may be added separately from the middle of the melt-kneading device such as an extruder. As the extrusion molding method, a general extrusion method can be applied. In the case of a multi-layered structure, two or more resin composition layers can be integrated and co-extruded to produce the structure.

[0047] [Container body] The container body according to this embodiment is made of the molded product of the sheet of the present invention described above. Since the resin composition layer constituting the sheet has high oil resistance, a container body with reduced thermal deformation caused by oil can be obtained. Thus, the container body according to this embodiment is suitable for applications requiring oil resistance.

[0048] The container body according to the present embodiment is particularly suitable for applications requiring oil resistance, and is particularly suitable for food storage (i.e., as a packaging container or food container lid containing food). It is particularly suitable for foods containing fats and oils. The food container and food container lid can be used for microwave heating and refrigeration.

[0049] Examples of a molding method for obtaining the container body include known methods such as vacuum forming of a sheet, pressure forming, and vacuum / pressure forming. EXAMPLES

[0050] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0051] The materials used in the examples and comparative examples are as follows: (PLA1) Polylactic acid REVODE190 (D type ratio: 0.5 mol%) manufactured by Kaisei Biomaterials Co., Ltd. (PLA2) Polylactic acid, REVODE110 (D type ratio: 2.5 mol%) manufactured by Kaisei Biomaterials Co., Ltd. (PS1) Rubber modified polystyrene: HIPS E640N manufactured by Toyo Styrene Co., Ltd. (PS2) Rubber modified polystyrene: HIPS H850N manufactured by Toyo Styrene Co., Ltd.

[0052] (AR1) Acrylic resin produced by the following manufacturing method -Manufacturing method- In a separable flask (capacity 5 liters) equipped with a thermometer, a nitrogen inlet tube, a cooling tube and a stirrer, 300 parts by mass of ion-exchanged water as a dispersion medium, 1.1 parts by mass of sodium dodecylbenzenesulfonate as an emulsifier, 0.007 parts by mass of n-octyl mercaptan as a chain transfer agent, 85 parts by mass of methyl methacrylate as a monomer, and 15 parts by mass of butyl acrylate were added. The atmosphere in the flask was replaced with nitrogen by passing a nitrogen stream through the separable flask. Next, the internal temperature was raised to 60°C, and 0.15 parts by mass of potassium persulfate and 5 parts by mass of ion-exchanged water were added. After that, the polymerization was terminated by continuing heating and stirring for 2 hours, and an acrylic resin latex was obtained. The obtained acrylic resin latex was cooled to 25°C, dropped into 500 parts by mass of 70°C warm water containing 5 parts by mass of calcium acetate, and then heated to 90°C to cause coagulation. The obtained coagulated material was separated and washed, and then dried at 60°C for 12 hours to obtain an acrylic resin (AR1). The peak top molecular weight (Mp) of the acrylic resin (AR1) was 1.5 million.

[0053] (AR2, AR3, ar1,) Acrylic resins AR2, AR3 and ar1 were produced under the same production conditions as in the above-mentioned AR1 production method, except that the peak top molecular weight (Mp) was changed by adjusting the amounts of various raw materials charged. The peak top molecular weights (Mp) obtained by gel permeation chromatography (GPC) of the acrylic resins AR2, AR3, and ar1 were 4.5 million, 3 million, and 900,000, respectively.

[0054] [Example 1] The resin composition to be the resin composition layer was prepared by the following method. That is, 30 parts by mass of polylactic acid (PLA1), 67 parts by mass of rubber-modified polystyrene (PS1), and 3 parts by mass of acrylic resin (AR1) were premixed in a Henschel mixer, then melt-kneaded using a twin-screw extruder (Toshiba Machine Co., Ltd., TEM26SS), and the strand was passed through a pelletizer to obtain pellets of the resin layer composition. The twin-screw extruder used was TEM26SS (Toshiba Machine Co., Ltd.), and was operated under the conditions of a cylinder setting temperature of 200°C and a discharge rate of the resin composition of 30 kg / hour.

[0055] Next, a 65 mm extruder was used to extrude pellets of the resin composition as a resin composition layer, and the pellets were fed into a T-die with a width of 700 mm to extrude a monolayer sheet having a total thickness of 0.4 mm after cooling. The monolayer sheet of Example 1 extruded from the lip of the T-die was then cooled using three rolls and wound up by a winder. The cylinder and die set temperatures for sheet extrusion were set at 200° C., and the discharge rate of the monolayer sheet was set at 30 kg / hour.

[0056] [Examples 2 to 10, Comparative Examples 1 to 4] Each of the sheets of Examples 2 to 10 and Comparative Examples 1 to 4 was produced by setting the composition and blending ratio of each resin of the resin composition forming the sheet as shown in Table 1, and adjusting the heater temperature, discharge amount, and lip width of the film-forming device as appropriate, but basically by the same procedure and using the same device as Example 1.

[0057] <Calculation of biomass ratio> For the sheets of Examples 1 to 10 and Comparative Examples 1 to 4, the content of PLA (polylactic acid) was taken as the biomass degree. The biomass degree can be determined from the blending amount of PLA. It can also be calculated using the following measurement method. 1 g of sheet (referred to as A(g)) was precisely weighed, methyl ethyl ketone was added, and the mixture was shaken for 2 hours. After filtration through a filter, chloroform was added to the filtrate and the mixture was shaken for 2 hours. Methanol was added to the supernatant after centrifugation (1400 rpm, 30 minutes) to re-precipitate the resin. After filtration through a filter, the mass of the sample (referred to as B(g)) was measured after drying in a vacuum dryer (125°C, 2 hours). The biomass degree was calculated from the measured A and B using the following formula. Biomass ratio (%) = B / A x 100 The results are shown in Table 1.

[0058] <Evaluation of heat deformation resistance> The sheets of Examples 1 to 10 and Comparative Examples 1 to 4 were molded into molded articles measuring 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 80°C, and mold retention time 15 seconds. These were then placed in a hot air dryer set at 110°C for 30 minutes, and the deformation of the container was observed. The containers were rated on a three-point scale: "○" if there was no deformation, "△" if there was deformation but the change in external dimensions was less than 10%, and "×" if the change in external dimensions was 10% or more. The change in external dimensions was shown as the average rate of change in length, width, and height before and after the evaluation. Regarding heat deformation resistance, in this test, if the result was "○" or "△", it was deemed that the effects of the present invention were realized. The results are shown in Table 1.

[0059] <Method of measuring impact resistance> Impact resistance was evaluated by film impact strength according to ASTM-D3420. For the sheets of Examples 1 to 10 and Comparative Examples 1 to 4 having a total thickness of 0.4 mm, a 70 mm x 70 mm piece was cut out and measured. If the impact resistance was 3.0 kJ / mm or more, it was determined that the effect of the present invention was realized. The results are shown in Table 1.

[0060] <Luxury feel (glossiness)> The luxurious feel of the container was evaluated by glossiness. In accordance with JIS Z 8741, a light beam with a specified divergence angle was incident on the sample surface at an incident angle of 60°, and the light beam with the specified divergence angle reflected in the direction of specular reflection was measured with a light receiver. It was considered that the lower the glossiness, the more luxurious the container will be when molded. The glossiness was compared and evaluated in three stages: 15 or less is "○", 16 to 18 is "△", and over 18 is "×". In this test, if it was "○" or "△", it was considered that the effect of the present invention was realized. The results are shown in Table 1.

[0061] <Film forming properties> The film-forming property was evaluated by T-die extrusion. The case where film formation was possible was marked with "○", and the case where film formation was impossible due to too high tension was marked with "×". The results are shown in Table 1.

[0062] [Table 1]

[0063] From the evaluation results of Examples 1 to 10 and Comparative Examples 1 to 4, it was confirmed that this example provides a sheet (single-layer sheet) that has high thermal deformation resistance and low environmental impact, and in Examples 1 to 9, the use of an acrylic resin with a peak top molecular weight (Mp) within a specified range improves gloss, thereby providing a luxurious feel when used as a container body. In Comparative Example 4, when a large amount of acrylic resin was added, a film could not be formed, and the film formability was rated as "x" because nothing worthy of evaluation was obtained.

Claims

1. A sheet for an oil-resistant container body, comprising at least one layer of a resin composition containing a styrene-based resin as a main component, the resin composition layer further contains 20 to 35 mass% of polylactic acid, 2.5 to 3.5 mass% of an acrylic resin, and 62 to 67 mass% of a styrene resin; The acrylic resin has a peak top molecular weight (Mp) of 1,000,000 to 6,000,000 as determined by gel permeation chromatography (GPC); The peak top molecular weight (Mp) of the polylactic acid is 50,000 to 400,000; The peak top molecular weight (Mp) of the styrene-based resin is 10,000 to 500,000; The sheet is molded into a molded product of length 150 mm, width 130 mm, and height 20 mm, and placed in a hot air dryer set at 110°C for 30 minutes. The heat deformation resistance is evaluated by observing the deformation of the container. The sheet has an external dimensional change of less than 10%.

2. 2. The sheet according to claim 1, wherein the styrene-based resin is a rubber-modified polystyrene.

3. A container body comprising a molded product of the sheet according to claim 1 or 2.

4. 4. The container body according to claim 3, which is for storing food.

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