Polystyrene-based resin laminated foam sheet and method for producing same, and polystyrene-based resin laminated foam container and method for producing same

Abstract

To provide a polystyrene-based resin laminated foamed sheet which is excellent in peel strength, container strength and impact resistance, can suppress drawdown during molding, and can further enhance moldability and productivity.SOLUTION: There is provided a polystyrene-based resin laminated foamed sheet 1 in which a non-foamed resin layer 20 is laminated on one side or both sides of a polystyrene-based resin foam sheet 10, wherein the non-foamed resin layer 20 contains a mixed resin containing a polystyrene-based resin and a polyolefin-based resin, a content of a styrene component in the mixed resin is 27-95 mass% with respect to the total mass of the mixed resin, a content of a butadiene component in the mixed resin is 2.2-12 mass% with respect to the total mass of the mixed resin, and a content of an olefin component in the mixed resin is 0.1-70 mass% with respect to the total mass of the mixed resin.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a polystyrene-based resin laminate foam sheet and a method for producing the same, and a polystyrene-based resin laminate foam container and a method for producing the same. [Background technology]

[0002] BACKGROUND ART Resin foam sheets obtained by foaming thermoplastic resins such as polystyrene-based resins and molded articles thereof have been used for food containers and the like because of their light weight and high heat insulating properties. A method for molding a polystyrene-based resin foam container (foam container) from a polystyrene-based resin foam sheet (foam sheet) includes heating the foam sheet to soften it, and then sandwiching it between molds to form the desired shape.

[0003] When forming a foam sheet, a phenomenon called "drawdown" may occur, in which the center of the foam sheet sags in the heating zone during the heating process. Drawdown can lead to variations in the weight of each container and poor appearance such as wrinkles.

[0004] To address this problem, for example, Patent Document 1 attempts to suppress drawdown by laminating a commercially available stretched film on the surface. For example, Patent Document 2 attempts to suppress drawdown by blowing cooling air onto the foam sheet during extrusion molding to stretch the foam sheet itself. For example, Patent Document 3 proposes a polystyrene resin laminated foam sheet (laminated foam sheet) in which a non-foamed film is laminated on a foam sheet. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-141772 [Patent Document 2] Japanese Patent Application Laid-Open No. 2006-264024 [Patent Document 3] Japanese Patent Application Laid-Open No. 2013-010299 Summary of the Invention [Problem to be solved by the invention]

[0006] However, with the technology of Patent Document 1, if the foamed sheet has a heavy basis weight, it may not be able to withstand its own weight and may not be able to suppress drawdown. This requires changing to a thicker commercially available film depending on the foamed sheet, which makes moldability difficult. With the technology of Patent Document 2, if the extrusion rate of the foamed sheet is increased to improve productivity, it becomes difficult to control the blowing of cooling air, and there is a risk that a foamed sheet with the desired stretching will not be obtained. This makes it difficult to improve productivity. With the technology of Patent Document 3, insufficient melt tension of the resin causes poor elongation during molding, resulting in problems with moldability and productivity.

[0007] Therefore, an object of the present invention is to provide a polystyrene-based resin laminated foam sheet and a method for producing the same, and a polystyrene-based resin laminated foam container and a method for producing the same, which are excellent in peel strength, container strength, and impact resistance, can suppress drawdown during molding, and can further improve moldability and productivity. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention has the following aspects. [1] A non-foamed resin layer is laminated on one or both sides of a polystyrene-based resin foam sheet, the non-foamed resin layer contains a mixed resin containing a polystyrene-based resin and a polyolefin-based resin, the content of the styrene component in the mixed resin is 27 to 95 mass% based on the total mass of the mixed resin, the content of the butadiene component in the mixed resin is 2.2 to 12 mass% with respect to the total mass of the mixed resin, The polystyrene-based resin laminate foam sheet, wherein the content of the olefin component in the mixed resin is 0.1 to 70 mass % based on the total mass of the mixed resin. [2] The polystyrene-based resin laminate foam sheet according to [1], wherein the mixed resin contains a high-impact polystyrene-based resin, and the mass ratio of the high-impact polystyrene-based resin to the polyolefin-based resin in the mixed resin (the high-impact polystyrene-based resin:the polyolefin-based resin) is 45:55 to 99.9 to 0.1. [3] The polystyrene-based resin laminate foam sheet according to [1] or [2], wherein the polyolefin-based resin in the mixed resin is a polyethylene-based resin. [4] The mixed resin has a crystallization peak, and the peak temperature of the crystallization peak is 90 to 140°C, The laminated polystyrene resin foam sheet according to any one of [1] to [3], wherein the temperature difference between the melting point of the mixed resin and the peak temperature is 1 to 20°C. [5] The laminated polystyrene resin foam sheet according to any one of [1] to [4], wherein the polyolefin resin contains high-density polyethylene and low-density polyethylene. [6] The laminated polystyrene resin foam sheet according to [5], wherein the mass ratio of the high-density polyethylene to the low-density polyethylene (the high-density polyethylene:the low-density polyethylene) is 10:90 to 90:10. [7] The laminated polystyrene resin foam sheet according to any one of [1] to [6], wherein the polyolefin resin in the mixed resin is a plant-derived resin. [8] The polystyrene-based resin laminate foam sheet according to any one of [1] to [7], wherein a thermoplastic resin film layer is located on at least one of one or both sides of the polystyrene-based resin foam sheet and one or both sides of the non-foamed resin layer.

[0009] [9] A method for producing the polystyrene-based resin laminate foam sheet according to any one of [1] to [8], A method for producing a laminated polystyrene resin foam sheet, comprising: a laminating step of extruding and laminating a resin composition containing the mixed resin on one or both surfaces of the polystyrene resin foam sheet.

[0010]

[10] A non-foamed resin layer is laminated on one or both sides of a polystyrene-based resin foam sheet, the non-foamed resin layer contains a mixed resin containing a polystyrene-based resin and a polyolefin-based resin, the content of the styrene component in the mixed resin is 27 to 95 mass% based on the total mass of the mixed resin, the content of the butadiene component in the mixed resin is 2.2 to 12 mass% with respect to the total mass of the mixed resin, A polystyrene-based resin laminated foam container, wherein the content of the olefin component in the mixed resin is 0.1 to 70% by mass with respect to the total mass of the mixed resin.

[11] The polystyrene-based resin laminated foam container according to

[10] , wherein the mixed resin contains a high-impact polystyrene-based resin, and the mass ratio of the high-impact polystyrene-based resin to the polyolefin-based resin in the mixed resin (the high-impact polystyrene-based resin:the polyolefin-based resin) is 45:55 to 99.9 to 0.1.

[12] The polystyrene-based resin laminated foam container according to

[10] or

[11] , wherein the polyolefin-based resin in the mixed resin is a polyethylene-based resin.

[13] The mixed resin has a crystallization peak, and the peak temperature of the crystallization peak is 90 to 140 ° C., The laminated polystyrene resin foam container according to any one of

[10] to

[12] , wherein the temperature difference between the melting point of the mixed resin and the peak temperature is 1 to 20°C.

[14] The polystyrene-based resin laminated foam container according to any one of

[10] to

[13] , wherein the polyolefin-based resin contains high-density polyethylene and low-density polyethylene.

[15] The polystyrene-based resin laminated foam container according to

[14] , wherein the mass ratio of the high-density polyethylene to the low-density polyethylene (the high-density polyethylene:the low-density polyethylene) is 10:90 to 90:10.

[16] The polystyrene-based resin laminated foam container according to any one of

[10] to

[15] , wherein the polyolefin-based resin in the mixed resin is a plant-derived resin.

[17] A polystyrene-based resin laminated foam container according to any one of

[10] to

[16] , wherein a thermoplastic resin film layer is located on at least one side of the polystyrene-based resin foam sheet and one side of the non-foamed resin layer.

[0011]

[18] A method for producing a polystyrene-based resin laminated foam container according to any one of

[10] to

[17] , a lamination step of extruding a resin composition containing the mixed resin onto one or both surfaces of the polystyrene-based resin foam sheet; a molding step of heating and molding the polystyrene-based resin laminate foam sheet obtained in the laminating step. [Effects of the Invention]

[0012] The polystyrene-based resin laminate foam sheet of the present invention is excellent in peel strength, container strength and impact resistance, and can suppress drawdown during molding, thereby further improving moldability and productivity. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a cross-sectional view showing an example of a laminated polystyrene resin foam sheet of the present invention. [Figure 2] 1 is a perspective view showing an example of a laminated polystyrene resin foam container of the present invention. [Figure 3] 1 is a DSC curve of a sample taken from the laminated polystyrene resin foam sheet of Example 1. [Figure 4] 1 is an example of a TMA curve obtained by TMA measurement of a mixed resin. DETAILED DESCRIPTION OF THE INVENTION

[0014] In this specification, the symbol "to" indicates a range that includes the values ​​at both ends as the lower and upper limits. A preferred embodiment of the present invention will be described below taking as an example a polystyrene-based resin laminate foam sheet having a non-foamed resin layer on one side of a sheet-shaped polystyrene-based resin foam sheet. The polystyrene-based resin laminate foam sheet may have a non-foamed resin layer on one side of the polystyrene-based resin foam sheet, or may have non-foamed resin layers on both sides of the polystyrene-based resin foam sheet. The polystyrene-based resin foam sheet may be composed of a single foamed layer, or may have two or more foamed layers. The non-foamed resin layer may be composed of a single non-foamed layer, or may have two or more non-foamed layers.

[0015] [Polystyrene resin laminated foam sheet] The polystyrene-based resin laminated foam sheet of the present invention (hereinafter also simply referred to as "laminated foam sheet") comprises a sheet-shaped polystyrene-based resin foam sheet (hereinafter also simply referred to as "foam sheet") and a non-foamed resin layer laminated on one or both sides of the foam sheet. The non-foamed resin layer contains a mixed resin containing a styrene component, a butadiene component, and an olefin component. An embodiment of the laminated foam sheet will be described with reference to the drawings.

[0016] 1 is a cross-sectional view of a laminated foam sheet 1 of this embodiment. The laminated foam sheet 1 has a sheet-like foam sheet 10 and a non-foamed resin layer 20 laminated on one side of the foam sheet 10.

[0017] The thickness T1 of the laminated foam sheet 1 can be determined taking into consideration the intended use. For example, the thickness T1 is preferably 0.5 to 7.5 mm, more preferably 0.7 to 5.0 mm, and even more preferably 1.0 to 4.0 mm. When the thickness T1 is equal to or greater than the above lower limit, the strength and impact resistance of the container can be further improved. When the thickness T1 is equal to or less than the above upper limit, the moldability of the laminated foam sheet 1 can be further improved. The thickness T1 can be measured using, for example, a dial thickness gauge.

[0018] The basis weight of the laminated foam sheet 1 is, for example, 70 to 850 g / m 2is preferable, and 120 to 700 g / m 2 More preferably, 200 to 550 g / m 2 When the basis weight of the laminated foam sheet 1 is equal to or greater than the above lower limit, the impact resistance of the container can be further improved. When the basis weight of the laminated foam sheet 1 is equal to or less than the above upper limit, the moldability of the laminated foam sheet 1 can be further improved. The basis weight of the laminated foam sheet 1 can be measured by the following method. Excluding 20 mm from both ends of the laminated foam sheet 1 in the width direction (TD direction), ten pieces of 10 cm x 10 cm are cut out at equal intervals in the width direction, and the mass (g) of each piece is measured to the nearest 0.001 g. The average mass (g) of each piece is calculated as 1 m 2 The value converted into the mass per unit area is used as the basis weight (g / m) of the laminated foam sheet 1. 2 )

[0019] The apparent density of the laminated foam sheet 1 is, for example, 0.060 to 0.716 g / cm 3 is preferable, and 0.086 to 0.540 g / cm 3 More preferably, 0.130 to 0.363 g / cm 3 When the apparent density of the laminated foam sheet 1 is equal to or greater than the above lower limit, the impact resistance of the container can be further improved. When the apparent density of the laminated foam sheet 1 is equal to or less than the above upper limit, the container can be made lighter and have better heat insulation properties.

[0020] The apparent density of the laminated foam sheet 1 can be determined by measuring in accordance with JIS K7222:2005 "Foam plastics and rubber - Determination of apparent density". Specifically, the mass and apparent volume of a test piece of the laminated foam sheet 1 cut without changing the original cell structure are measured, and the mass and apparent volume are calculated using the following formula (1). Apparent density of laminated foam sheet 1 (g / cm 3 ) = mass of test piece (g) / apparent volume of test piece (cm 3 )···(1)

[0021] <Foam sheet> Foamed sheet 10 is a layer (foamed resin layer) formed by foaming a foamable resin composition containing a polystyrene resin, and bubbles are formed in the resin. The resin contained in the foamable resin composition (i.e., the resin constituting foamed sheet 10) is a thermoplastic resin.

[0022] Examples of polystyrene resins include homopolymers of styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, chlorostyrene, ethylstyrene, i-propylstyrene, dimethylstyrene, and bromostyrene, or copolymers thereof; copolymers of styrene-based monomers and vinyl monomers polymerizable therewith, which contain styrene-based monomers as the main component; copolymers of styrene-based monomers and rubber components such as butadiene; so-called high impact polystyrenes, which are mixtures or polymers of homopolymers of styrene-based monomers or copolymers thereof, or copolymers of styrene-based monomers and vinyl monomers with diene-based rubber polymers; and the like.

[0023] Examples of vinyl monomers polymerizable with styrene-based monomers include alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, and cetyl (meth)acrylate, and bifunctional monomers such as (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, and alkylene glycol dimethacrylate. These vinyl monomers may be used alone or in combination of two or more. Here, "(meth)acrylate" refers to either or both of "acrylate" and "methacrylate", and "(meth)acrylonitrile" refers to either or both of "acrylonitrile" and "methacrylonitrile".

[0024] Examples of diene rubber polymers include polybutadiene, styrene-butadiene copolymers, and ethylene-propylene-non-conjugated diene three-dimensional copolymers. These polystyrene resins may be used alone or in combination of two or more. As the polystyrene-based resin, a polystyrene-based resin containing 50 mol % or more of units derived from a styrene monomer is preferred, and among these, polystyrene is more preferred.

[0025] The polystyrene-based resin may be a polystyrene-based resin that is not made from recycled raw materials, such as general-purpose polystyrene resin (GPPS), commercially available polystyrene-based resin, or polystyrene-based resin newly prepared by a method such as suspension polymerization, or may be a polystyrene-based resin that is made from recycled raw materials. Examples of recycled raw materials include used polystyrene-based resin foam molded articles, such as fish boxes, cushioning materials for home appliances, and food packaging trays, which are recovered and regenerated by a limonene dissolution method or a thermal volume reduction method. Examples of recycled raw materials include scraps generated after punching food packaging trays from a polystyrene-based resin foam sheet, which are crushed, melt-kneaded, and re-pelletized. Usable recycled raw materials include those obtained by recycling molded bodies such as used foam containers, as well as non-foamed polystyrene resins separated and recovered from home appliances (e.g., televisions, refrigerators, washing machines, air conditioners, etc.), office equipment (e.g., copiers, facsimiles, printers, etc.), etc.

[0026] The mass average molecular weight Mw of the polystyrene resin is preferably 120,000 to 450,000, more preferably 150,000 to 400,000. The mass average molecular weight Mw is a value measured by gel permeation chromatography (GPC) and converted based on a calibration curve using standard polystyrene.

[0027] The melt flow rate (MFR) of the polystyrene resin is preferably 0.5 to 6.0 g / 10 min, more preferably 0.7 to 3.0 g / 10 min. When the MFR of the polystyrene resin is equal to or greater than the lower limit, the strength of the container can be further increased. When the MFR of the polystyrene resin is equal to or less than the upper limit, the moldability of the foamed sheet 10 can be further increased. In this specification, the MFR of a polystyrene-based resin refers to a value measured in accordance with Method B described in JIS K7210:1999 "Test methods for melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of plastics - thermoplastics" under conditions of a test temperature of 200°C, a test load of 49.03 N, and a preheating time of 5 minutes.

[0028] The content of the polystyrene resin per 100 parts by mass of the thermoplastic resin constituting the foamed sheet 10 is preferably 50 parts by mass or more, more preferably 75 parts by mass or more, even more preferably 90 parts by mass or more, and particularly preferably 95 parts by mass or more. When the content of the polystyrene resin is equal to or more than the above-mentioned lower limit, the moldability of the foamed sheet 10 can be further improved, and the rigidity (container strength) of the foamed container, which is the molded product, can be increased. The upper limit of the amount of polystyrene resin contained is not particularly limited, and may be 100 parts by mass per 100 parts by mass of the thermoplastic resin constituting foamed sheet 10 .

[0029] The foamable resin composition may contain a thermoplastic resin other than a polystyrene-based resin. Examples of the thermoplastic resin other than a polystyrene-based resin include polyolefin-based resins such as polyethylene and polypropylene; and polyphenylene ether-based resins such as poly(2,6-dimethylphenylene-1,4-ether), poly(2,6-diethylphenylene-1,4-ether), and poly(2,6-dichlorophenylene-1,4-ether).

[0030] The foamable resin composition contains a foaming agent. Examples of blowing agents include hydrocarbons such as propane, butane, and pentane; halogenated hydrocarbons such as tetrafluoroethane, chlorodifluoroethane, and difluoroethane; and among these, hydrocarbons are preferred, and butane is preferred. As butane, normal butane or isobutane may be used alone, or normal butane and isobutane may be used in combination in any ratio. These blowing agents may be used alone or in combination of two or more.

[0031] The content of the foaming agent in the foamable resin composition is, for example, preferably 0.1 to 10 parts by mass, more preferably 1 to 7 parts by mass, and even more preferably 1 to 5 parts by mass, relative to 100 parts by mass of the thermoplastic resin.

[0032] The foamable resin composition may contain components other than the thermoplastic resin and the foaming agent (hereinafter also referred to as "optional components of the foam layer"). Examples of the optional components of the foam layer include a cell regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant, a deodorizer, a lubricant, a flame retardant, and an antistatic agent. The type of optional component for the foam layer is determined taking into consideration the physical properties required for the foam sheet 10. The optional component for the foam layer may be one type alone or a combination of two or more types.

[0033] Examples of the cell regulator include mixtures of inorganic powders such as talc and silica, etc. These cell regulators increase the closed cell rate of foamed sheet 10 and facilitate the formation of a foamed layer. Examples of the stabilizer include calcium zinc-based heat stabilizers, tin-based heat stabilizers, and lead-based heat stabilizers. Examples of the ultraviolet absorber include cesium oxide-based ultraviolet absorbers and titanium oxide-based ultraviolet absorbers. Examples of antioxidants include cerium oxide, cerium oxide / zirconia solid solution, cerium hydroxide, carbon, carbon nanotubes, titanium oxide, and fullerene. Examples of colorants include titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine, cobalt blue, calcined pigments, metallic pigments, mica, pearl pigments, zinc oxide, precipitated silica, and cadmium red. Examples of deodorizing agents include silica, zeolite, zirconium phosphate, and calcined hydrotalcite.

[0034] The content of the optional component for the foam layer in the foamable resin composition is, for example, preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.3 to 5.0 parts by mass, relative to 100 parts by mass of the thermoplastic resin. When the content of the optional component for the foam layer is equal to or greater than the above-mentioned lower limit, the effects derived from the optional component for the foam layer can be exerted. When the content of the optional component for the foam layer is equal to or less than the above-mentioned upper limit, clogging of the die or the like can be more effectively prevented, and the appearance of the foam sheet 10 can be improved.

[0035] Thickness T of foam sheet 10 10 The thickness T of the foamed sheet 10 is preferably 0.3 to 5.0 mm, more preferably 0.4 to 3.0 mm, and even more preferably 0.5 to 2.5 mm. 10 When the thickness T of the foamed sheet 10 is equal to or greater than the lower limit, the impact resistance of the foamed container can be further improved. 10 When the value is equal to or less than the upper limit, the foamed container can be made lighter and the moldability can be further improved. Thickness T of foam sheet 10 10 is determined in the same manner as the thickness T1 of the laminated foam sheet 1.

[0036] The basis weight of the foam sheet 10 is, for example, 50 to 600 g / m 2 is preferable, and 90 to 500 g / m 2 More preferably, 150 to 400 g / m 2 is more preferable. When the basis weight of the foamed sheet 10 is equal to or greater than the above lower limit, the impact resistance of the foamed container can be further improved. When the basis weight of the foamed sheet 10 is equal to or less than the above upper limit, the foamed container can be made lighter and the moldability can be further improved. In addition, when the basis weight of the foamed sheet 10 is equal to or less than the above upper limit, the heating time during thermoforming is not too long, and the productivity of the foamed container can be further improved. The basis weight of foam sheet 10 is determined in the same manner as the basis weight of laminated foam sheet 1.

[0037] The apparent density of the foamed sheet 10 is, for example, 0.050 to 0.666 g / cm 3 is preferable, and 0.066 to 0.500 g / cm 3More preferably, 0.100 to 0.333 g / cm 3 When the apparent density of the foamed sheet 10 is equal to or greater than the above lower limit, the impact resistance of the foamed container can be further improved. When the apparent density of the foamed sheet 10 is equal to or less than the above upper limit, the foamed container can be made lighter and have higher heat insulation properties. The apparent density of foamed sheet 10 is determined in the same manner as the apparent density of laminated foamed sheet 1.

[0038] The expansion ratio of the foamed sheet 10 is, for example, preferably 1.5 to 20 times, more preferably 2 to 15 times, and even more preferably 3 to 10 times. When the expansion ratio of the foamed sheet 10 is equal to or greater than the above lower limit, the impact resistance of the foamed container can be further improved. When the expansion ratio of the foamed sheet 10 is equal to or less than the above upper limit, the moldability of the foamed sheet 10 can be further improved. The expansion ratio of the foamed sheet 10 is calculated by dividing 1 by the apparent density (g / cm) of the foamed sheet 10. 3 ) is the value divided by

[0039] The average cell diameter of the foamed sheet 10 is, for example, preferably 80 to 450 μm, more preferably 150 to 400 μm, and even more preferably 200 to 350 μm. When the average cell diameter of the foamed sheet 10 is equal to or greater than the above lower limit, the impact resistance of the foamed container can be further improved. When the average cell diameter of the foamed sheet 10 is equal to or less than the above upper limit, the surface smoothness of the foamed container can be further improved. The average cell diameter of the foamed sheet 10 can be measured in accordance with the method described in ASTM D2842-69.

[0040] The closed cell ratio of the foamed sheet 10 is preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and may be 100%. The closed cell ratio of the foamed sheet 10 can be measured in accordance with the method described in JIS K7138:2006 "Rigid foamed plastics - Determination of open cell ratio and closed cell ratio."

[0041] <Non-foamed resin layer> The non-foamed resin layer 20 contains a mixed resin containing a polystyrene resin and a polyolefin resin, and is a layer in which substantially no bubbles are formed. In addition, the non-foamed resin layer 20 is a layer that does not substantially contain a foaming agent. Although the non-foamed resin layer 20 is a layer in which substantially no bubbles are formed, it may contain a small amount of a foaming agent when the non-foamed resin layer 20 is formed by a co-extrusion method, for example.

[0042] The mixed resin contains a polystyrene-based resin and a polyolefin-based resin. In this specification, the term “mixed resin” refers to all resin components in the resin composition that constitutes the non-foamed resin layer 20 . The MFR of the polystyrene resin is the same as the MFR of the polystyrene resin constituting the foamed sheet 10 described above.

[0043] When the polyolefin resin is a polyethylene resin, the MFR of the polyethylene resin is preferably 0.1 to 15.0 g / 10 min, more preferably 0.2 to 8.0 g / 10 min. When the MFR of the polyethylene resin is equal to or greater than the lower limit, the fluidity during melting is good, and productivity can be further improved. When the MFR of the polyethylene resin is equal to or less than the upper limit, the elongation during molding is good, and moldability can be further improved. In this specification, the MFR of a polyethylene resin refers to a value measured in accordance with Method B described in JIS K7210:1999 "Test methods for melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of plastics - thermoplastics" under conditions of a test temperature of 190°C, a test load of 21.18 N, and a preheating time of 5 minutes.

[0044] When the polyolefin resin is a polypropylene resin, the MFR of the polypropylene resin is preferably 2.0 to 20.0 g / 10 min, more preferably 4.0 to 14.0 g / 10 min. When the MFR of the polypropylene resin is equal to or greater than the lower limit, the flowability during melting is good, and productivity can be further improved. When the MFR of the polypropylene resin is equal to or less than the upper limit, the elongation during molding is good, and moldability can be further improved. In this specification, the MFR of a polypropylene-based resin refers to a value measured in accordance with Method B described in JIS K7210:1999 "Test methods for melt mass-flow rate (MFR) and melt volume-flow rate (MVR) of plastics - thermoplastics" under conditions of a test temperature of 230°C, a test load of 21.18 N, and a preheating time of 5 minutes.

[0045] In this specification, the styrene component refers to a styrene monomer obtained when the mixed resin is heated and decomposed. The styrene component is derived from the polystyrene resin contained in the mixed resin. Examples of the polystyrene resin include resins similar to the polystyrene resin constituting the foam sheet 10. Among them, those containing a high-impact polystyrene resin are preferred. When the mixed resin contains a high-impact polystyrene resin, the impact resistance of the foamed container can be further improved.

[0046] In this specification, the butadiene component refers to butadiene monomer and 4-vinyl-1-cyclohexene monomer obtained by heating and decomposing the mixed resin. The butadiene component is derived from the polystyrene resin contained in the mixed resin.

[0047] In this specification, the olefin component refers to an olefin monomer obtained when a mixed resin is heated and decomposed. The olefin component is derived from a polyolefin resin contained in the mixed resin. Examples of polyolefin resins include polyethylene resins and polypropylene resins. As the polyolefin resin, a polyethylene resin is preferred because the mixed resin has good moldability when mixed with a polystyrene resin. Examples of polyethylene resins include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), etc. Of the polyethylene resins, HDPE is preferred because it can further increase the strength of the container. In this specification, high density polyethylene refers to polyethylene having a resin density of 0.940 g / cm 3 More than 0.970g / cm3 The following polyethylene resins are referred to: Medium density polyethylene has a resin density of 0.930 g / cm 3 Super 0.940g / cm 3 Low-density polyethylene refers to polyethylene resins with a resin density of less than 0.910 g / cm 3 More than 0.930g / cm 3 It refers to the following polyethylene resins: Linear low-density polyethylene refers to linear low-density polyethylene. The resin density of the polyethylene resin can be measured in accordance with the method described in Method B (pycnometer method) of JIS K7112:1999 "Plastics - Method for measuring density and specific gravity of non-foamed plastics."

[0048] The polyolefin resin preferably contains high-density polyethylene and low-density polyethylene, as this further improves lamination processability. When the polyolefin resin contains high-density polyethylene and low-density polyethylene, the mass ratio of the high-density polyethylene to the low-density polyethylene (high-density polyethylene:low-density polyethylene) is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and even more preferably 30:70 to 70:30. When the mass ratio of the high-density polyethylene to the low-density polyethylene is 10:90 or more, drawdown during molding of the foamed sheet 10 can be further suppressed. When the mass ratio of the high-density polyethylene to the low-density polyethylene is 90:10 or less, the melt elongation of the mixed resin can be further increased, and the take-up stability can be further improved. Here, the "lamination processability" is one of the indices for evaluating the formability of the non-foamed resin layer 20 when extruding the mixed resin, and can be evaluated from neck-in and take-up stability. In this specification, "neck-in" refers to a neck-in phenomenon, which is a phenomenon in which the thickness of both ends in the width direction (TD) of the non-foamed resin layer 20 increases. "Haul-up stability" refers to suppressing fluctuations in the thickness of the non-foamed resin layer 20 when the take-up speed during take-up of the non-foamed resin layer 20 is increased. By improving the lamination processability, the formability of the non-foamed resin layer 20 can be further improved, and the productivity of the laminated foam sheet 1 can be further increased.

[0049] The polyolefin resin contained in the mixed resin is preferably a plant-derived resin, since this can reduce the environmental impact. Examples of plant-derived resins include polymers derived from plant materials such as sugarcane and corn. "Derived from plant materials" includes polymers synthesized or extracted from plant materials. Furthermore, "derived from plant materials" includes polymers obtained by polymerizing monomers synthesized or extracted from plant materials. "Monomers synthesized or extracted from plant materials" includes monomers synthesized using compounds synthesized or extracted from plant materials. Plant-derived resins include those in which some of the monomers are "derived from plant materials." Examples of plant-derived resins include so-called bio-PE, bio-PP, and the like, plant-derived polyethylene-based resins, plant-derived polypropylene-based resins, and the like.

[0050] The content of the styrene component in the mixed resin is 27 to 95 mass %, preferably 40 to 93 mass %, and more preferably 50 to 90 mass %, based on the total mass of the mixed resin. When the content of the styrene component in the mixed resin is equal to or greater than the lower limit, the peel strength can be further increased. When the content of the styrene component in the mixed resin is equal to or less than the upper limit, drawdown during molding of the foamed sheet 10 can be further suppressed. The content of the styrene component in the mixed resin can be determined by the method described in the examples.

[0051] The content of the butadiene component in the mixed resin is 2.2 to 12 mass%, preferably 3.2 to 10 mass%, and more preferably 4.1 to 8.0 mass%, relative to the total mass of the mixed resin. When the content of the butadiene component in the mixed resin is equal to or greater than the lower limit, the impact resistance and moldability of the container can be further improved. When the content of the butadiene component in the mixed resin is equal to or less than the upper limit, the strength of the container can be further improved. The content of the butadiene component in the mixed resin can be determined by the method described in the examples.

[0052] The content of the olefin component in the mixed resin is 0.1 to 70 mass%, preferably 2 to 50 mass%, and more preferably 3 to 40 mass%, based on the total mass of the mixed resin. When the content of the olefin component in the mixed resin is equal to or greater than the above lower limit, drawdown during molding can be further suppressed. When the content of the olefin component in the mixed resin is equal to or less than the above upper limit, container strength and peel strength can be further increased. The content of the olefin component in the mixed resin can be determined by the method described in the examples.

[0053] When the mixed resin contains a high-impact polystyrene resin, the mass ratio of the high-impact polystyrene resin to the polyolefin resin in the mixed resin (high-impact polystyrene resin:polyolefin resin) is 45:55 to 99.9. : The mass ratio of the high-impact polystyrene resin to the polyolefin resin in the mixed resin is preferably 0.1, more preferably 50:50 to 98:2, and even more preferably 60:40 to 95:5. When the mass ratio of the high-impact polystyrene resin to the polyolefin resin in the mixed resin is within the above range, the container strength and impact resistance are excellent, and drawdown during molding can be further suppressed.

[0054] The resin composition constituting the non-foamed resin layer 20 contains a mixed resin. The resin composition containing a mixed resin preferably contains a compatibilizer to improve the dispersibility of the polyolefin resin in the polystyrene resin. The compatibilizer may be any agent capable of compatibilizing the polystyrene resin and the polyolefin resin, and conventionally known compatibilizers can be used. Styrenic thermoplastic elastomers are particularly preferred as compatibilizers. Styrenic thermoplastic elastomers have excellent flexibility and elasticity, and rubber-like properties. Examples of styrenic thermoplastic elastomers include elastomers of styrene, butadiene, and styrene (SBS-based), elastomers of styrene, isoprene, and styrene (SIS-based), and hydrogenated styrenic thermoplastic elastomers obtained by hydrogenating these. Examples of hydrogenated styrenic thermoplastic elastomers include elastomers of styrene, ethylene, butylene, and styrene (SEBS-based), elastomers of styrene, butadiene, butylene, and styrene (SBBS-based), and elastomers of styrene, ethylene, propylene, and styrene (SEPS-based). Among these, SEBS-based hydrogenated styrenic thermoplastic elastomers are preferred as compatibilizers because they can further improve the dispersibility of polyolefin resins in high-impact polystyrene resins.

[0055] When the resin composition contains a compatibilizer, the content of the compatibilizer is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 3 to 10 parts by mass, per 100 parts by mass of the total amount of the polystyrene-based resin and the polyolefin-based resin. When the content of the compatibilizer is within the above numerical range, the dispersibility of the polyolefin-based resin in the polystyrene-based resin can be further improved.

[0056] In the non-foamed resin layer 20, the peak temperature (Tc) of the crystallization peak of the mixed resin measured using a heat flux differential scanning calorimetry (DSC) device is preferably 90 to 140°C, more preferably 95 to 130°C, and even more preferably 100 to 125°C. When the peak temperature (Tc) of the crystallization peak of the mixed resin is equal to or higher than the above lower limit, drawdown during molding can be further suppressed. When the peak temperature (Tc) of the crystallization peak of the mixed resin is equal to or lower than the above upper limit, moldability can be further improved. The peak temperature (Tc) of the crystallization peak of the mixed resin can be determined by the method described in the Examples. The peak temperature (Tc) of the crystallization peak of the mixed resin can be adjusted by the type of the mixed resin, the composition of the mixed resin, or a combination thereof.

[0057] The melting point (Tm) of the mixed resin in the non-foamed resin layer 20 is preferably 100 to 160° C., more preferably 105 to 150° C., and even more preferably 110 to 140° C. When the melting point (Tm) of the mixed resin in the non-foamed resin layer 20 is within the above range, moldability can be further improved. The melting point (Tm) of the mixed resin in the non-foamed resin layer 20 is determined by the method described in the Examples. The melting point (Tm) of the mixed resin in the non-foamed resin layer 20 can be adjusted by the type of mixed resin, the composition of the mixed resin, or a combination thereof.

[0058] The temperature difference (Tm-Tc) between the melting point (Tm) of the mixed resin in the non-foamed resin layer 20 and the peak temperature (Tc) of the crystallization peak of the mixed resin (hereinafter also referred to as "supercooling temperature difference") is preferably 1 to 20° C., more preferably 5 to 17° C., and even more preferably 11 to 14° C. When the supercooling temperature difference (Tm-Tc) is within the above range, drawdown during molding can be further suppressed. The supercooling temperature difference (Tm-Tc) can be calculated from the melting point (Tm) of the mixed resin and the peak temperature (Tc) of the crystallization peak of the mixed resin.

[0059] The softening temperature of the mixed resin in the non-foamed resin layer 20 is preferably 96 to 140°C, more preferably 98 to 130°C, and even more preferably 100 to 120°C. When the softening temperature of the mixed resin in the non-foamed resin layer 20 is equal to or higher than the above lower limit, drawdown during molding can be further suppressed. When the softening temperature of the mixed resin in the non-foamed resin layer 20 is equal to or lower than the above upper limit, moldability can be further improved. The softening temperature of the mixed resin in the non-foamed resin layer 20 can be measured in accordance with the method described in JIS K7196:1991 "Softening temperature test method by thermomechanical analysis of thermoplastic plastic films and sheets." The softening temperature of the mixed resin in the non-foamed resin layer 20 can be adjusted by the type of mixed resin, the composition of the mixed resin, and a combination thereof.

[0060] The resin density of the mixed resin in the non-foamed resin layer 20 is 0.990 to 1.039 g / cm 3 is preferred, and 1.000 to 1.038 g / cm 3 More preferably, 1.010 to 1.037 g / cm 3 When the resin density of the mixed resin in the non-foamed resin layer 20 is equal to or greater than the above lower limit, the container strength can be further increased. When the resin density of the mixed resin in the non-foamed resin layer 20 is equal to or less than the above upper limit, drawdown during molding can be further suppressed. The resin density of the mixed resin in the non-foamed resin layer 20 is determined by the method described in the examples. The resin density of the mixed resin in the non-foamed resin layer 20 can be adjusted by the type of mixed resin, the composition of the mixed resin, or a combination thereof.

[0061] The melt tension of the non-foamed resin layer 20 is preferably 2.1 cN or more, more preferably 2.6 cN or more, and even more preferably 3.4 cN or more. When the melt tension of the non-foamed resin layer 20 is equal to or greater than the above-mentioned lower limit, the non-foamed resin layer 20 exhibits good elongation during molding, and the moldability can be further improved. The upper limit of the melt tension of the non-foamed resin layer 20 is not particularly limited, and is, for example, 8 cN or less. The melt tension of the non-foamed resin layer 20 is determined by the method described in the Examples. The melt tension of the non-foamed resin layer 20 can be adjusted by the type of mixed resin, the composition of the mixed resin, and a combination thereof.

[0062] Thickness T of the non-foamed resin layer 20 20 The thickness T of the non-foamed resin layer 20 is preferably 15 to 400 μm, more preferably 30 to 300 μm, further preferably 50 to 200 μm, and particularly preferably 90 to 160 μm. 20 When the thickness T of the non-foamed resin layer 20 is equal to or greater than the above lower limit, the strength of the container can be further increased. 20 When it is equal to or less than the upper limit, the moldability can be further improved. Thickness T of the non-foamed resin layer 20 20 is determined by observing a cross section of the laminated foam sheet 1 cut in the thickness direction with a microscope or the like.

[0063] The resin composition constituting the non-foamed resin layer 20 may contain components other than the mixed resin (hereinafter also referred to as "optional components"). Examples of the optional components include the same components as those of the foamed layer described above. When the resin composition contains an optional component, the content of the optional component is, for example, preferably 0.05 to 10 parts by mass, more preferably 0.1 to 5.0 parts by mass, and even more preferably 0.3 to 3.0 parts by mass, relative to 100 parts by mass of the total amount of the polystyrene-based resin and the polyolefin-based resin. When the content of the optional component is equal to or greater than the above-mentioned lower limit, the effects derived from the optional component can be exerted. When the content of the optional component is equal to or less than the above-mentioned upper limit, the fluidity during melting is good, and productivity can be further improved.

[0064] [Method of manufacturing laminated foam sheet] A method for manufacturing the laminated foam sheet 1 includes, for example, manufacturing a raw sheet that will become the foam sheet 10 (raw sheet manufacturing process), and then extruding and laminating a resin composition containing a mixed resin onto one or both sides of the raw sheet (lamination process).

[0065] As the raw sheet manufacturing process, a conventionally known manufacturing method can be adopted. First, a raw material composition containing a thermoplastic resin and other components, and a foaming agent are fed into an extruder, melted, and kneaded to form a foamable resin composition. The temperature at which the thermoplastic resin is melted (melting temperature: set temperature) is preferably, for example, 180 to 270°C. When the melting temperature is equal to or higher than the lower limit, the resin and other raw materials can be uniformly mixed. When the melting temperature is equal to or lower than the upper limit, decomposition of the resin can be suppressed.

[0066] Examples of lamination processes include a method of extruding a resin composition onto the surface of an original sheet using an extruder (T-die) (T-die method), and a method of obtaining a laminated foamed sheet 1 in which a non-foamed resin layer 20 is provided on a foamed sheet 1 by co-extrusion (co-extrusion method).

[0067] In the lamination step, the basis weight of the resin composition extruded from the extruder is, for example, 15 to 400 g / m 2is preferable, and 30 to 300 g / m 2 More preferably, 50 to 200 g / m 2 More preferably, 90 to 160 g / m 2 is particularly preferred. When the basis weight of the resin composition extruded from the extruder is equal to or greater than the above lower limit, a laminated foamed sheet 1 having a sufficient thickness of the non-foamed resin layer 20 can be obtained. This can further suppress drawdown during molding. When the basis weight of the resin composition extruded from the extruder is equal to or less than the above upper limit, moldability can be further improved.

[0068] The take-up speed when the non-foamed resin layer 20 is taken up by a take-up machine is not particularly limited, but is preferably 10 to 30 m / min, more preferably 13 to 28 m / min, and even more preferably 20 to 26 m / min. When the take-up speed is equal to or greater than the above lower limit, the productivity of the non-foamed resin layer 20 can be further improved. When the take-up speed is equal to or less than the above upper limit, the lamination processability of the non-foamed resin layer 20 can be further improved.

[0069] The laminated foam sheet 1 may be produced by separately producing a raw sheet and a raw non-foamed layer sheet that will become the non-foamed resin layer 20, stacking the raw sheet and the non-foamed layer sheet together, and then bonding them under heat and pressure (thermocompression bonding method). Alternatively, the raw sheet and the non-foamed layer sheet may be stacked together, and then bonded together with an adhesive (sticking method).

[0070] The non-foamed layer raw sheet may be produced by melting and mixing two or more resin pellets, which are the raw materials for the non-foamed layer, in advance, forming them into pellets (mixed pellets), feeding them into an extruder, melting them, and kneading them to produce the non-foamed layer raw sheet. The mixed pellets may be subjected to a T-die method or a co-extrusion method to produce the non-foamed layer raw sheet. Alternatively, instead of producing mixed pellets, one or more resin pellets may be fed into an extruder, melted, and kneaded to produce the non-foamed layer raw sheet. From the viewpoint of further improving the dispersibility of the mixed resin and further improving the impact resistance of the foamed container, it is preferable to form the non-foamed resin layer using mixed pellets.

[0071] According to this embodiment, since the non-foamed resin layer 20 is laminated on one or both sides, drawdown during molding can be suppressed. In addition, the non-foamed resin layer 20 of this embodiment has a styrene component content, a butadiene component content, and an olefin component content in the mixed resin that fall within specific ranges, thereby enhancing peel strength. Furthermore, the non-foamed resin layer 20 of this embodiment has a good elongation during molding, thereby further enhancing moldability, since the styrene component content, butadiene component content, and olefin component content in the mixed resin fall within specific ranges.

[0072] The laminated foam sheet 1 of this embodiment preferably has a thermoplastic resin film layer (not shown) on one or both sides. The laminated foam sheet 1 may have a thermoplastic resin film layer on only one side, or on both sides. That is, it is preferable that a thermoplastic resin film layer is located on at least one of one or both sides of the foamed sheet 10 and one or both sides of the non-foamed resin layer 20. When the laminated foam sheet 1 has a thermoplastic resin film layer, it is more preferable that the thermoplastic resin film layer be laminated on both or either one of the surface (outermost surface) 11 of the foamed sheet 10 and the surface (outermost surface) 21 of the non-foamed resin layer 20. By laminating a thermoplastic resin film layer, the strength of the laminated foam sheet 1 and the foamed container can be improved. In addition, the laminated foam sheet 1 and the foamed container can be provided with oil resistance, designability, surface smoothness, printability, oxygen barrier property, water vapor barrier property, etc. A thermoplastic resin film layer may be provided at interface 30 between foamed sheet 10 and non-foamed resin layer 20 as long as the effects of the present invention are not impaired.

[0073] The thermoplastic resin film layer may be configured as a single film layer, or may have two or more film layers. The thermoplastic resin film layer may be an unstretched film, or may be a uniaxially or biaxially stretched film. The thermoplastic resin film layer is preferably made of a plant-derived resin, since this can reduce the environmental impact. The thermoplastic resin film layer preferably has a printed layer on which a printed pattern or the like is applied, since this allows for the layer to be given a design. The thickness of the thermoplastic resin film layer is, for example, preferably from 10 to 200 μm, more preferably from 13 to 150 μm, and even more preferably from 15 to 80 μm.

[0074] Examples of the thermoplastic resin film layer include polystyrene-based resin films, polyolefin-based resin films such as polypropylene-based resins and polyethylene-based resins, polyester-based resin films such as polyethylene terephthalate-based resins, polybutylene terephthalate-based resins, polyethylene furanoate-based resins, polybutylene succinate-based resins and polylactic acid-based resins, polyamide-based resin films, and ethylene vinyl alcohol-based resin films. A polystyrene-based resin film is preferable because it has excellent adhesiveness between foamed sheet 10 and non-foamed resin layer 20 and can be laminated by thermocompression bonding. Polypropylene-based resin films are preferred because they can impart oil resistance to laminated foam sheets and foam containers. Polyolefin resin films such as polyethylene resin and polypropylene resin, polyester resin films, polyamide resin films, and ethylene vinyl alcohol resin films are preferred because they can provide gas barrier properties for oxygen, water vapor, and the like.

[0075] Examples of the method for laminating the thermoplastic resin film layer include the following methods. (1) A method of stacking a thermoplastic resin film layer and a foamed sheet 10 in this order and then heat-pressing them (thermocompression bonding method), or a method of stacking a thermoplastic resin film layer and a non-foamed resin layer 20 in this order and then heat-pressing them (thermocompression bonding method). (2) A method of stacking a thermoplastic resin film layer and a foamed sheet 10 in this order and bonding each layer together with an adhesive (a lamination method), or a method of stacking a thermoplastic resin film layer and a non-foamed resin layer 20 in this order and bonding each layer together with an adhesive (a lamination method). (3) A method in which a resin that is a raw material for the thermoplastic resin film layer is extruded onto the surface of foamed sheet 10 or the surface of non-foamed resin layer 20 using a T-die (T-die method). (4) A method of obtaining a laminate in which a thermoplastic resin film layer is provided on a foamed sheet 10 by coextrusion (coextrusion method), or a method of obtaining a laminate in which a thermoplastic resin film layer is provided on a non-foamed resin layer 20 by coextrusion (coextrusion method).

[0076] [Polystyrene-based resin laminated foam container] The polystyrene resin laminated foam container of the present invention (hereinafter also referred to as "foam container") is produced by molding the above-mentioned laminated foam sheet of the present invention. Examples of the molded article include trays whose planar shape is circular, elliptical, semicircular, polygonal, fan-shaped, etc., bowl-shaped containers, containers in the shape of a cylinder with a bottom or a square cylinder with a bottom, various containers such as containers with lids such as containers for natto, and lids that can be attached to the container body. The preferred uses of these containers are, for example, for food.

[0077] An embodiment of the foaming container of the present invention will be described with reference to the drawings. 2 is a bowl-shaped container with a perfectly circular shape in a plan view. The foaming container 100 has a circular bottom wall 110 and a side wall 120 rising from the periphery of the bottom wall 110. The side wall 120 widens outward toward the upper end. The foaming container 100 has an opening 130 surrounded by the upper end of the side wall 120. The opening 130 surrounded by the upper end of the side wall 120 has a perfect circular shape in plan view. The bottom wall 110 is formed with a convex portion 112 that is convex toward the opening 130 and has a perfect circular shape in plan view, and an annular recessed portion 114 that surrounds the convex portion 112. The foam container 100 is suitable for use as a food container for storing instant noodles or the like, into which hot water is poured to eat.

[0078] Although the foaming container 100 of this embodiment has a perfect circular shape in plan view, the present invention is not limited thereto. The shape of the foaming container in plan view may be elliptical or polygonal.

[0079] The foaming container 100 may have a non-foamed resin layer only on the inner surface, may have a non-foamed resin layer only on the outer surface, or may have a non-foamed resin layer on both the inner and outer surfaces. The foaming container 100 preferably has a thermoplastic resin film layer. The foaming container 100 may have a thermoplastic resin film layer only on the inner surface, may have a thermoplastic resin film layer only on the outer surface, or may have a thermoplastic resin film layer on both the inner and outer surfaces.

[0080] [Method of manufacturing foam containers] Examples of methods for producing foam containers include a method (thermoforming method) in which a laminated foam sheet is heated to soften it (heating step), and then molded by sandwiching it between a female mold and a male mold (molding step).

[0081] The heating step is a step of heating the laminated foam sheet to soften it. The heating temperature in the heating step may be any temperature at which the laminated foam sheet softens, for example, 80 to 150°C.

[0082] The molding process involves sandwiching a heated laminated foam sheet between a female mold and a male mold to obtain a container of any desired shape. In this process, the laminated foam sheet of the present invention has a non-foamed resin layer containing a mixed resin laminated on one or both sides, thereby suppressing drawdown. Additionally, the non-foamed resin layer of this embodiment has specific ranges of styrene component content, butadiene component content, and olefin component content in the mixed resin, thereby improving peel strength, container strength, and impact resistance. Furthermore, the non-foamed resin layer of this embodiment has specific ranges of styrene component content, butadiene component content, and olefin component content in the mixed resin, thereby improving elongation during molding and moldability.

[0083] Examples of the forming method in the forming step include conventionally known thermoforming methods such as vacuum forming, compressed air forming, and their applications such as free drawing forming, plug and ridge forming, ridge forming, matched mold forming, straight forming, drape forming, reverse draw forming, air slip forming, plug assist forming, and plug assist reverse load forming.

[0084] The temperature of the mold in the molding step is not particularly limited, but is preferably 50 to 150°C, more preferably 60 to 130°C. When the temperature of the mold is equal to or higher than the lower limit, the molding speed can be increased, and productivity can be further improved. When the temperature of the mold is equal to or lower than the upper limit, melting of the laminated foam sheet can be prevented.

[0085] After the laminated foam sheet is molded into a desired shape in the mold, the mold is opened and a foam container portion is punched out from the laminated foam sheet, thereby obtaining a foam container.

[0086] As described above, according to the foamed container of the present invention, since a non-foamed resin layer containing a mixed resin is laminated on one or both sides, the strength and impact resistance of the container can be improved. [Example]

[0087] The present invention will be explained in more detail below by showing examples, but the present invention is not limited to these examples.

[0088] (Raw materials used) <Polystyrene resin> E641N: High impact polystyrene, product name "E641N" (manufactured by Toyo Styrene Co., Ltd.), butadiene content: 6% by mass, resin density: 1.04 g / cm 3 . XL5: High impact polystyrene, product name "XL5" (manufactured by Toyo Styrene Co., Ltd.), butadiene content: 13% by mass, resin density: 1.04 g / cm 3 . 475D: High impact polystyrene, product name "475D" (manufactured by PS Japan Co., Ltd.), butadiene content: 3.9% by mass, resin density: 1.04 g / cm 3 . HRM26: General-purpose polystyrene, product name "HRM26" (manufactured by Toyo Styrene Co., Ltd.), resin density: 1.05 g / cm 3 . HP555: General-purpose polystyrene, product name "HP555" (manufactured by DIC Corporation), resin density: 1.05 g / cm 3 .

[0089] <Polyolefin resin> SGF4960: High-density polyethylene (HDPE), product name "SGF4960" (plant-derived, manufactured by Braskem), MFR: 0.34 g / 10 min, resin density: 0.961 g / cm 3 . SGF4950: High-density polyethylene (HDPE), product name "SGF4950" (plant-derived, manufactured by Braskem), MFR: 0.34 g / 10 min, resin density: 0.956 g / cm 3 . SGE7252NS: High-density polyethylene (HDPE), product name "SGE7252NS" (plant-derived, manufactured by Braskem), MFR: 2.2 g / 10 min, resin density: 0.953 g / cm 3 . SHC7260: High-density polyethylene (HDPE), product name "SHC7260" (plant-derived, manufactured by Braskem), MFR: 7.2 g / 10 min, resin density: 0.959 g / cm 3 . HY540: High-density polyethylene (HDPE), product name "HY540" (petroleum-derived, manufactured by Japan Polyethylene Co., Ltd.), MFR: 1.0 g / 10 min, resin density: 0.946 g / cm 3 . J241: High-density polyethylene (HDPE), product name "J241" (petroleum-derived, manufactured by Asahi Kasei Corporation), MFR: 5.0 g / 10 min, resin density: 0.964 g / cm 3 . SBF0323HC: Low-density polyethylene (LDPE), product name "SBF0323HC" (plant-derived, manufactured by Braskem), MFR: 0.32 g / 10 min, resin density: 0.923 g / cm 3 . SLL118: Linear low-density polyethylene (LLDPE), product name "SLL118" (plant-derived, manufactured by Braskem), MFR: 1.0 g / 10 min, resin density: 0.918 g / cm 3 . PM600A: Homopolypropylene (PP), product name "PM600A" (petroleum-derived, manufactured by SunAllomer Co., Ltd.), MFR: 8.0 g / 10 min, resin density: 0.900 g / cm 3 .

[0090] <Compatibilizer> H1043: Hydrogenated styrene-based thermoplastic elastomer (SEBS-based), product name "Tuftec (registered trademark) H1043" (manufactured by Asahi Kasei Corporation), resin density: 0.970 g / cm 3 The component ratio (mass ratio) "styrene / butadiene / olefin" = 67 / 4 / 29.

[0091] [Examples 1 to 22, Comparative Examples 1 to 4] <Production of raw sheet> The main raw material was a polystyrene resin (trade name "G0002", manufactured by PS Japan Co., Ltd.) with a melt mass-flow rate (MFR) of 1.8 g / 10 min (100 parts by mass), and the cell control agent was a talc masterbatch (trade name "DSM1401A", manufactured by Toyo Styrene Co., Ltd.) (1.0 part by mass). The mixture was mixed, melted, and kneaded in a tandem extruder. After kneading, 3.3 parts by mass of butane gas (isobutane) was injected into the melt at a predetermined position. A cylindrical foam was extruded through a circular die with a diameter of 170 mm, cooled on a predetermined mandrel, slit into a sheet, and wound up. The resulting raw sheet (foam sheet) had a thickness of 1.75 mm and a basis weight of 220 g / m. 2 , apparent density is 0.126g / cm 3 It was.

[0092] <Mixing of resin composition for non-foamed resin layer> Polyolefin resin, polystyrene resin (high impact polystyrene resin, general-purpose polystyrene resin), and compatibilizer were blended in the amounts shown in Tables 1 to 6 and premixed in a mixing drum.

[0093] <Manufacturing laminated foam sheets> The resin composition premixed in the above <<Mixing of Resin Composition for Non-Foamed Resin Layer>> was applied to one side of the raw sheet obtained in the above <<Production of Raw Sheet>> using an extruder (T-die) until the basis weight reached 120 g / m. 2 The mixture was extruded and laminated by a T-die method at a take-up speed of 13 m / min to obtain a laminated foam sheet. The thickness of the obtained laminated foam sheet was 1.84 mm (the thickness of the non-foamed resin layer was 120 μm, and the thickness of the foamed sheet was 1.72 mm), and the basis weight was 340 g / m 2 , apparent density is 0.185g / cm 3 It was.

[0094] [Example 23] A resin composition having the same composition as in Example 4 was extruded onto one side of the raw sheet and laminated using a T-die method to obtain a laminate having the same configuration as the laminated foam sheet of Example 4. A 50 μm-thick CPPS dry laminate film (a dry laminate film formed by laminating a 30 μm-thick unstretched polypropylene film and a 20 μm-thick unstretched polystyrene film via an adhesive layer) was laminated onto the surface (outermost surface) of the non-foamed resin layer of the obtained laminate by thermocompression bonding so that the unstretched polystyrene film side was adhered to the surface of the non-foamed resin layer. Furthermore, a 20 μm-thick CPS film (unstretched polystyrene film) with a printed pattern was laminated onto the surface of the foam sheet (foam layer) of the obtained laminate by thermocompression bonding. In this way, a laminated foam sheet having thermoplastic resin film layers on both the surface of the non-foamed resin layer and the surface of the foam sheet (foam layer) was obtained. The thickness of the obtained laminated foam sheet was 1.91 mm (CPPS dry laminate film thickness: 50 μm, non-foamed resin layer thickness: 120 μm, foam sheet thickness: 1.72 mm, CPS film thickness: 20 μm), and the basis weight was 407 g / m 2 , apparent density is 0.212 g / cm 3 It was.

[0095] <Manufacturing foam containers> The laminated foam sheet of each example was left to stand at 27±3° C. and a relative humidity of 60±5% for 24 hours, after which a test piece having a rectangular shape in plan view, measuring 700 mm long and 1040 mm wide, was cut out from the laminated foam sheet. Next, a single-shot molding machine (manufactured by Tosei Sangyo Co., Ltd., product name "FM-3A") was used, and the average temperature of the upper heater of this single-shot molding machine was set to 270°C, the average temperature of the lower heater was set to 220°C, and the ambient temperature was set to 155°C. Next, the test pieces were introduced into the single-shot molding machine and heated for 15 seconds, after which 18 foamed containers having an opening at the top were produced by thermoforming for each Example. The foamed containers of Examples 1 to 16 and Comparative Examples 1 to 4 had a non-foamed resin layer on the inner surface of the container, and the foamed container of Example 17 had a thermoplastic resin film layer (CPPS dry laminated film layer) on the inner surface of the container. The obtained foamed containers were bowl-shaped containers with a circular opening diameter of 190 mm in a plan view, a bottom diameter of 170 mm, and a height of 50 mm.

[0096] The physical properties of the obtained laminated foam sheet, the physical properties of the non-foamed resin layer, and the physical properties of the foamed container were measured and evaluated by the following methods. The results are shown in Tables 1 to 4. In the tables, a "-" in the column for the composition of the non-foamed resin layer indicates that the component was not contained. In the tables, a "-" in the column for the physical properties of the non-foamed resin layer indicates that the item was not measured. In the tables, a "-" in the column for the evaluation indicates that the item was not evaluated.

[0097] <Proportion of each component in the mixed resin (ratio of three components)> The non-foamed resin layer was sliced ​​from the resulting laminated foam sheet using a slicer or razor, and approximately 0.1 to 0.5 mg of the sample was precisely weighed. A test specimen was prepared by wrapping the sample in a ferromagnetic metal body, "Pyrofoil" manufactured by Japan Analytical Industry Co., Ltd., with a Curie point of 590°C. The test specimen was prepared so that the ferromagnetic metal body was pressed against the sample, and the test specimen was heated in a Curie point pyrolyzer, "JPS-700" manufactured by Japan Analytical Industry Co., Ltd., to decompose the sample.

[0098] <Proportion of styrene component> The styrene monomer generated by decomposition was measured using an "Agilent Technologies GC7820" gas chromatograph (detector = FID), and the peak area of the styrene monomer was determined. For the peak area of the styrene monomer, the ratio of the styrene component contained in the sample was calculated from a calibration curve prepared in advance. The standard sample for preparing the calibration curve used suspension-polymerized PS fine particles manufactured by Sekisui Chemical Co., Ltd.

[0099] <Ratio of butadiene component> The butadiene monomer and 4-vinyl-1-cyclohexene monomer generated by decomposition were measured using an "Agilent Technologies GC7820" gas chromatograph (detector = FID), and the total peak area of the butadiene monomer and 4-vinyl-1-cyclohexene monomer was determined. The total of the butadiene monomer and 4-vinyl-1-cyclohexene monomer was regarded as the butadiene component. The ratio of the butadiene component contained in the sample was calculated from a calibration curve prepared in advance. The standard sample for preparing the calibration curve used a standard sample of styrene / butadiene rubber = 85 / 15 (mass ratio).

[0100] The measurement conditions of the gas chromatograph were as follows. <Measurement conditions> · Heating: 590 °C for 5 seconds. · Oven temperature: 300 °C. · Needle temperature: 300 °C. · Column: "DB-5" manufactured by Agilent Technologies (film thickness 0.25 μm × inner diameter 0.25 mm × length 30 m).

[0101] <GC oven temperature rising conditions> · Initial temperature: 50 °C (held for 0.5 minutes). · First-stage temperature rising rate: 10 °C / min (up to 200 °C, holding time 0 minutes). · Second-stage temperature rising rate: 20 °C / min (up to 320 °C). · Final temperature: 320 °C (held for 0.5 minutes). · Carrier gas: He gas. ·He flow rate: 25mL / min. Inlet pressure: 100kPa. · Column inlet pressure: 100kPa. ·Inlet temperature: 300℃. Detector temperature: 300℃. Split ratio: 1 / 50

[0102] <Olefin component ratio> When the main components contained in the non-foamed resin layer were a three-component system of a styrene component, a butadiene component, and an ethylene component, the proportion of the olefin component (ethylene component) was calculated by the following formula (2). [Ethylene content (mass%)] = 100 - [Styrene content (mass%) measured by gas chromatography] - [Butadiene content (mass%) measured by gas chromatography] (2)

[0103] The fact that the main components contained in the non-foamed resin layer are a three-component system of a styrene component, a butadiene component, and an ethylene component was confirmed by measuring the infrared absorption spectrum using the following measuring device and under the following measuring conditions. <Measurement equipment and conditions> Measurement equipment: Thermo Scientific "Nicolet iS10" Fourier transform infrared spectrophotometer and Thermo Scientific single-reflection horizontal ATR Smart-iTR. ATR crystal: Diamond-attached KRS-5 (angle = 45°). ·Measurement method: Single reflection ATR method. ·Measurement wavenumber range: 4000cm -1 ~400cm -1 . Wavenumber dependence of measurement depth: Uncorrected. · Detector: Deuterated triglycine sulfate (DTGS) detector and KBr beam splitter. ·Resolution: 4cm -1 . -Number of accumulations: 16 (same for background measurement). Number of tests: n = 3 measurements, average value used.

[0104] When the main components contained in the non-foamed resin layer are four or more components, a calibration curve of a standard sample having a predetermined ethylene / styrene mass ratio (for example, three points with ratios of 25 / 50, 50 / 50, and 75 / 50) can be prepared in advance. This allows the ethylene / styrene component ratio in the mixed resin to be calculated from the infrared absorption spectrum obtained by measuring the mixed resin, and the proportion of the olefin component (ethylene component) can be calculated using the following formula (3). [Ethylene content (mass%)] = [Styrene content (mass%) measured by gas chromatography] × [Ethylene / styrene ratio calculated from infrared absorption spectrum] (3)

[0105] <Melting point (Tm), crystallization temperature (Tc), supercooling temperature difference (Tm-Tc)> The melting point (Tm) and crystallization temperature (peak temperature (Tc) of the crystallization peak) of the mixed resin in the non-foamed resin layer were measured in accordance with the method described in JIS K7121:1987 and JIS K7121:2012 "Method for measuring transition temperature of plastics." However, the sampling method and temperature conditions were as follows. The non-foamed resin layer was taken from the laminated foam sheet using a slicer or a razor, and cut into a rectangular shape measuring 10 mm in length and 5 mm in width. The sample was then placed in the bottom of an aluminum measurement container, with the appropriate size cut to leave no gaps, and 5.5±0.5 mg of the sample was then filled, followed by the aluminum lid. Next, differential scanning calorimetry (DSC) was performed using a DSC7000X, AS-3 differential scanning calorimeter manufactured by Hitachi High-Tech Science Corp. In the DSC measurement, the sample was heated and cooled in the following steps under a nitrogen gas flow rate of 20 mL / min to obtain a DSC curve. (Step 1) Lower the temperature from 30°C to -40°C and hold for 10 minutes. (Step 2) Heat from -40°C to 220°C (first heating) and hold for 10 minutes. (Step 3) Cool from 220°C to -40°C and hold for 10 minutes. (Step 4) Heat from -40°C to 220°C (second heating). All temperature increases and decreases were carried out at a rate of 10°C / min. Alumina was used as the reference material.

[0106] Using the analysis software attached to the DSC device, the temperature at the top of the crystallization peak observed during the cooling process (step 3) was read and designated as the crystallization temperature (Tc), and the temperature at the top of the melting peak observed during the second heating process (step 4) was read and designated as the melting temperature (melting point (Tm)). The supercooling temperature difference (Tm-Tc) was calculated by the following formula (4). [Supercooling temperature difference (Tm - Tc) (°C)] = [Melting point (Tm) (°C)] - [Crystallization temperature (Tc) (°C)] (4)

[0107] Figure 3 shows the DSC curve of the sample taken from the laminated foam sheet of Example 1. As shown in Figure 3, curve P is the DSC curve in the second heating process (step 4). The temperature of 131.1°C at the top of the melting peak of curve P is the melting point (Tm) of the mixed resin. Curve Q is the DSC curve for the cooling process (step 3). The temperature at the top of the crystallization peak of curve Q, 119.7°C, is the crystallization temperature (Tc) of the mixed resin. The supercooling temperature difference (Tm-Tc) of the mixed resin is calculated from equation (4) as 131.1-119.7=11.4°C.

[0108] <Melt tension> The melt tension of the non-foamed resin layer was measured using a Rheologic 5000T twin-bore capillary rheometer manufactured by Chiast. A capillary die with a diameter of 2.095 mm, a length of 8 mm, and an inlet angle of 90° (conical) was attached to the measuring device, and the melt tension was measured using a tension detection pulley located 27 cm below the capillary die. First, a test sample was filled into a 15 mm diameter barrel heated to a test temperature of 200°C. The filled test sample was preheated for 5 minutes to melt. The melt was extruded from the capillary die in a string shape while maintaining a constant piston descending speed (0.07730 mm / s). The string-shaped material was passed through a tension detection pulley and then wound up using a take-up roll. The initial winding speed was 4 mm / s, with an acceleration of 12 mm / s. 2 The melt tension (MT) of the measured sample was determined as the average of the maximum and minimum tension values ​​just before the string-like object broke.

[0109] ≪Softening temperature≫ The softening temperature of the mixed resin was measured using an "EXSTRAR TMA / SS6100" heat, stress, strain (TMA) measuring device manufactured by SII Nanotechnology, Inc., in accordance with the method described in JIS K7196:1991 "Softening temperature test method by thermomechanical analysis of thermoplastic plastic films and sheets." However, the sampling method and temperature conditions were as follows. First, a non-foamed resin layer was taken from the laminated foam sheet using a slicer or a razor, and several pieces were cut into squares measuring 25 mm in length and 25 mm in width. These were then heat-pressed at 180°C for 5 minutes to produce disc-shaped test pieces with a thickness of 1 mm and a diameter of 10 mm. The thickness of the test piece was measured before measurement by applying an indenter (needle) with a load of 500 mN to the test piece. The measurement conditions were as follows:

[0110] <Measurement conditions> Mode: Penetration test mode (quartz probe tip φ1mm). Atmosphere: Nitrogen atmosphere. Load: 500mN. Heating rate: 5℃ / min. ·Measurement temperature: 30℃~200℃.

[0111] The TMA curve obtained by TMA measurement was analyzed using the analysis software provided with the instrument, and the TMA curve was corrected using the quartz coefficient setting in the analysis software. Figure 4 shows an example of a TMA curve obtained by TMA measurement of a mixed resin. As shown in Figure 4, curve R represents the penetration depth versus temperature. The straight line portion of the TMA curve, observed on the low-temperature side below where the indenter (needle) begins to penetrate, was extended toward the high-temperature side and set as the baseline L1. The tangent line L2 at the point where the penetration rate is maximum was extended toward the low-temperature side, and the intersection point S with the baseline L1 was determined. The temperature at the intersection point S was taken as the penetration temperature, and the penetration temperature was taken as the softening temperature of the mixed resin.

[0112] <Resin density of mixed resin> The resin density of the mixed resin was determined by the following method. The non-foamed resin layer was taken from the laminated foam sheet using a slicer or a razor, and 30 rectangular pieces measuring 100 mm in length and 25 mm in width were cut out to prepare test pieces. The volume (cm) of these test pieces was measured using a Tokyo Science Co., Ltd. "1000 Type" air comparison hydrometer by the 1-1 / 2-1 atmospheric pressure method. 3 The test pieces were conditioned for 16 hours in a Class 2 environment, 23 / 50, as specified in JIS K7100:1999 "Plastics - Standard atmospheres for conditioning and testing," and then used for the measurements. The measurements were carried out in the same environment. The air comparison hydrometer was used with a standard ball (large, 28.96 cm 3 , small 8.58cm 3 ) was corrected by the resin density of the mixed resin (g / cm 3 ) was calculated using the following formula (5). [Resin density (g / cm 3 )] = [mass of test piece (g)] / [measurement volume with air comparison hydrometer (cm 3 )] ···(5)

[0113] (Evaluation method) <Peel strength> The non-foamed resin layer of the laminated foam sheet obtained in each example was peeled off by hand, and the peel strength was evaluated based on the following evaluation criteria. <Notation Standards> A: The peel strength is strong enough that the non-foamed resin layer cannot be peeled off by hand. B: When the non-foamed resin layer was peeled off, the foamed sheet was bonded so strongly that the material was destroyed. C: When the non-foamed resin layer was peeled off, almost no material damage was observed in the foamed sheet. D: The edge of the non-foamed resin layer is raised and can be peeled off with a slight force.

[0114] <Container impact resistance> 400 g of water was placed in the foamed container obtained in each example, and the opening was sealed. The container was dropped from a height of 1.0 m onto a concrete surface in an environment of 23°C, and the presence or absence of damage to the container was visually confirmed. Tests were conducted on 10 foamed containers for each example, and the impact resistance of the container was evaluated based on the following evaluation criteria. Note that in Comparative Example 4, a foamed container could not be molded, so the impact resistance of the container was not evaluated. Evaluation Criteria A: The number of damaged containers is 0 to 2. B: The number of damaged containers is 3 to 5. C: The number of damaged containers is 6 to 9. D: The number of broken containers is 10.

[0115] <Drawdown during molding> The test piece cut out in the above <<Production of foamed containers>> was introduced into a single-shot molding machine, heated at an atmospheric temperature of 155°C for 15 seconds, and then the sheet shape of the test piece immediately after being taken out without molding was visually observed, and the drawdown during molding was evaluated based on the following evaluation criteria. Evaluation Criteria A: There has been no drawdown at all. B: Slight drawdown is observed inside the molding machine, but no drawdown occurs after removal. C: Slight drawdown. D: There is clearly a drawdown.

[0116] <Stretching during molding> The foamed container obtained in each example was visually observed and evaluated for elongation during molding based on the following evaluation criteria: The greater the elongation during molding, the better the moldability. Evaluation Criteria A: All 18 pieces were molded neatly. B: In some of the 18 containers, variations in whiteness due to poor stretching of the non-foamed resin layer were observed on the inner surface of the container. C: Variations in whiteness due to poor stretching of the non-foamed resin layer were observed on the inner surface of all 18 containers. D: Cracks or wrinkles were observed in some of the 18 containers.

[0117] <Container strength> The opening of the foamed container obtained in each example was held by hand, and the container strength was evaluated based on the following evaluation criteria. Note that in Comparative Example 4, a foamed container could not be molded, so the container strength was not evaluated. Evaluation Criteria A: There is sufficient strength when you hold the opening with your hand and pull it outward. B: There is adequate strength when you hold the opening with your hand and pull it outward. C: When you hold the opening with your hand and pull it outward, it feels weak. D: When the opening is facing downwards and the bottom surface is pressed from above, the side walls buckle easily.

[0118] <<Overall rating>> The above five items (peel strength, impact resistance of the container, drawdown during molding, elongation during molding, and container strength) were comprehensively evaluated based on the following evaluation criteria. Evaluation Criteria A: Of the five items above, all were rated "A", or all were rated "A" or "B", with one "B". B: Of the five items above, all were rated "A," "B," or "C," with two or more "B"s or one "C." C: Of the five items above, all were rated "A," "B," or "C," with two receiving "C." D: Of the five items above, the item evaluation was either "C" or "D," and there were three or more "C"s or one or more "D"s.

[0119] (Lamination processability evaluation) In addition to the above comprehensive evaluation, the non-foamed resin layer of each example was evaluated for lamination processability in order to confirm the formability and productivity of the non-foamed resin layer. In the evaluation of lamination processability, the following evaluations were performed.

[0120] <Return Stability> The extruder output was adjusted so that the thickness of the non-foamed resin layer was 120 μm. The take-up speed of the take-up machine was then adjusted to a predetermined speed, and a length of 3 m was taken up in the extrusion direction (MD). The thickness variation of the non-foamed resin layer during extrusion lamination was confirmed using a scanning electron microscope (SU1510, manufactured by Hitachi High-Tech Corporation). The thickness variation was considered to be "variable" when the thickness of the taken-up non-foamed resin layer was ±30 μm or more relative to 120 μm. The take-up stability was evaluated based on the following evaluation criteria. The faster the take-up speed at which the thickness of the non-foamed resin layer varied, the better the take-up stability. Evaluation Criteria A: No thickness fluctuation at a take-up speed of 26 m / min. B: There is a thickness fluctuation at a take-up speed of 26 m / min, but there is no thickness fluctuation at a take-up speed of 23 m / min. C: There is a thickness fluctuation at a take-up speed of 23 m / min, but there is no thickness fluctuation at a take-up speed of 20 m / min. D: There is a thickness fluctuation at a take-up speed of 20 m / min, but there is no thickness fluctuation at a take-up speed of 16 m / min. E: There is a thickness fluctuation at a take-up speed of 16 m / min, but there is no thickness fluctuation at a take-up speed of 13 m / min.

[0121] <Neck-in> The cross section of the laminated foam sheet obtained in each example was cut in the thickness direction along the width direction (TD direction) and observed with a scanning electron microscope (SU1510, manufactured by Hitachi High-Technologies Corporation) to confirm the position where the non-foamed resin layer had a thickness of 150 μm or more. The occurrence of neck-in was evaluated based on the following evaluation criteria. The closer the position where the non-foamed resin layer had a thickness of 150 μm or more was to the end in the width direction, the more the neck-in phenomenon was judged to be suppressed. Evaluation Criteria A: The location where the thickness is 150 μm or more is within 5 cm from the edge in the width direction. B: The location where the thickness is 150 μm or more is more than 5 cm and within 10 cm from the edge in the width direction. C: The location where the thickness is 150 μm or more is closer to the center than 10 cm from the edge in the width direction.

[0122] [Table 1]

[0123] [Table 2]

[0124] [Table 3]

[0125] [Table 4]

[0126] [Table 5]

[0127] [Table 6]

[0128] Examples 8 to 10 and 22 are reference examples. As shown in Tables 1 to 6, Examples 1 to 23 to which the present invention was applied received an overall rating of "A," "B," or "C." In contrast, Comparative Example 1, which did not contain a polyolefin-based resin in the non-foamed resin layer, had a drawdown during molding of "D" and an overall evaluation of "D". Comparative Example 2, in which the butadiene component content and the olefin component content were outside the ranges of the present invention, had a peel strength of "D" and an overall evaluation of "D". Comparative Example 3, in which the butadiene component content was outside the range of the present invention, had three item evaluations of "C" and an overall evaluation of "D". Comparative Example 4, in which the butadiene component content was outside the range of the present invention, had an elongation during molding of "D", and a foamed container could not be molded.

[0129] From the above results, it was confirmed that application of the present invention can provide excellent peel strength, container strength, and impact resistance, suppress drawdown during molding, and further improve moldability and productivity. [Explanation of symbols]

[0130] 1 Polystyrene resin laminated foam sheet 10 Polystyrene resin foam sheet 11 Surface of polystyrene resin foam sheet 20 Non-foamed resin layer 21 Surface of non-foamed resin layer 30 Interface between polystyrene resin foam sheet and non-foamed resin layer

Claims

1. A non-foamed resin layer is laminated on one or both sides of a polystyrene-based resin foam sheet, the non-foamed resin layer contains a mixed resin that includes a polystyrene-based resin and a polyolefin-based resin and does not contain linear low-density polyethylene, the content of the styrene component in the mixed resin is 27 to 95% by mass based on the total mass of the mixed resin, the content of the butadiene component in the mixed resin is 2.2 to 8.0 mass% based on the total mass of the mixed resin, The polystyrene-based resin laminate foam sheet, wherein the content of the olefin component in the mixed resin is 0.1 to 48.6 mass% based on the total mass of the mixed resin.

2. 2. The polystyrene-based resin laminate foam sheet according to claim 1, wherein the mixed resin contains a high-impact polystyrene-based resin, and in the mixed resin, a mass ratio of the high-impact polystyrene-based resin to the polyolefin-based resin (the high-impact polystyrene-based resin:the polyolefin-based resin) is 45:55 to 99.9:0.

1.

3. The polystyrene-based resin laminate foam sheet according to claim 1 or 2, wherein the polyolefin-based resin in the mixed resin is a polyethylene-based resin.

4. The mixed resin has a crystallization peak, and the peak temperature of the crystallization peak is 90 to 140°C, The polystyrene-based resin laminate foam sheet according to any one of claims 1 to 3, wherein a temperature difference between the melting point of the mixed resin and the peak temperature is 1 to 20°C.

5. The polystyrene-based resin laminate foam sheet according to any one of claims 1 to 4, wherein the polyolefin-based resin comprises high-density polyethylene and low-density polyethylene.

6. 6. The polystyrene-based resin laminate foam sheet according to claim 5, wherein a mass ratio of the high-density polyethylene to the low-density polyethylene (the high-density polyethylene:the low-density polyethylene) is 10:90 to 90:

10.

7. The polystyrene-based resin laminate foam sheet according to any one of claims 1 to 6, wherein the polyolefin-based resin in the mixed resin is a plant-derived resin.

8. The polystyrene-based resin laminate foam sheet according to any one of claims 1 to 7, wherein a thermoplastic resin film layer is located on at least one surface of the polystyrene-based resin foam sheet and one surface of the non-foamed resin layer.

9. A method for producing the polystyrene-based resin laminate foam sheet according to any one of claims 1 to 8, A method for producing a laminated polystyrene resin foam sheet, comprising: a laminating step of extruding and laminating a resin composition containing the mixed resin on one or both surfaces of the polystyrene resin foam sheet.

10. A non-foamed resin layer is laminated on one or both sides of a polystyrene-based resin foam sheet, the non-foamed resin layer contains a mixed resin that includes a polystyrene-based resin and a polyolefin-based resin and does not contain linear low-density polyethylene, the content of the styrene component in the mixed resin is 27 to 95% by mass based on the total mass of the mixed resin, the content of the butadiene component in the mixed resin is 2.2 to 8.0 mass% based on the total mass of the mixed resin, The polystyrene-based resin laminated foam container has an olefin component content of 0.1 to 48.6 mass % relative to the total mass of the mixed resin.

11. The polystyrene-based resin laminated foam container according to claim 10, wherein the mixed resin contains a high-impact polystyrene-based resin, and in the mixed resin, the mass ratio of the high-impact polystyrene-based resin to the polyolefin-based resin (the high-impact polystyrene-based resin:the polyolefin-based resin) is 45:55 to 99.9:0.

1.

12. The polystyrene-based resin laminated foam container according to claim 10 or 11, wherein the polyolefin-based resin in the mixed resin is a polyethylene-based resin.

13. The mixed resin has a crystallization peak, and the peak temperature of the crystallization peak is 90 to 140°C, The polystyrene-based resin laminated foam container according to any one of claims 10 to 12, wherein the temperature difference between the melting point of the mixed resin and the peak temperature is 1 to 20°C.

14. The polystyrene-based resin laminated foam container according to any one of claims 10 to 13, wherein the polyolefin-based resin comprises high-density polyethylene and low-density polyethylene.

15. The polystyrene-based resin laminated foam container according to claim 14, wherein the mass ratio of the high-density polyethylene to the low-density polyethylene (the high-density polyethylene:the low-density polyethylene) is 10:90 to 90:

10.

16. The polystyrene-based resin laminated foam container according to any one of claims 10 to 15, wherein the polyolefin-based resin in the mixed resin is a plant-derived resin.

17. The polystyrene-based resin laminated foam container according to any one of claims 10 to 16, wherein a thermoplastic resin film layer is located on at least one surface of the polystyrene-based resin foam sheet and one surface of the non-foamed resin layer.

18. A method for producing the polystyrene-based resin laminated foam container according to any one of claims 10 to 17, comprising: a lamination step of extruding a resin composition containing the mixed resin onto one or both surfaces of the polystyrene-based resin foam sheet; a molding step of heating and molding the polystyrene-based resin laminate foam sheet obtained in the laminating step.

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