Polystyrene-based resin laminated foam sheet and polystyrene-based resin laminated foam container

Abstract

To provide: a polystyrene-based resin laminated foam sheet which includes a polystyrene-based resin foam sheet and is excellent in moldability; and a polystyrene-based resin laminated foam container which is molded from the polystyrene-based resin laminated foam sheet.SOLUTION: A PS laminated foam sheet includes a polystyrene-based resin (hereinafter abbreviated as PS) foam sheet (A), wherein the PS foam sheet (A) includes a laminate of a first PS foam layer 11 having a glass transition temperature (Tg) of 110°C or higher and a second PS foam layer 12 having a Tg lower than that of the first PS foam layer, and when an average surface roughness of surface roughness Ra1 (MD) in an MD direction of the first PS foam layer and surface roughness Ra1 (TD) in a TD direction is represented by R1(=(Ra1(MD)+Ra1(TD)) / 2), and an average surface roughness of surface roughness Ra2 (MD) in an MD direction of the second PS foam layer and surface roughness Ra2 (TD) in a TD direction is represented by R2(=(Ra2(MD)+Ra2(TD)) / 2), (R1 / R2) is 1.1 to 3.0.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a laminated polystyrene resin foam sheet and a laminated polystyrene resin foam container. [Background technology]

[0002] A thermoplastic resin laminated foam sheet for molding a container is manufactured by supplying a thermoplastic resin together with a foaming agent, a bubble adjusting agent, etc. into an extruder, heating and melting these materials in the extruder, kneading them, and cooling them to a predetermined temperature, and then extruding the resin into a sheet form from a die, foaming it, and immediately cooling it to produce a foam sheet, on the surface of which a thermoplastic resin film is laminated. To manufacture a container using this thermoplastic resin laminated foam sheet, a thermoplastic resin laminated foam sheet wound into a roll is heated to a constant temperature in the heating zone of a molding machine, and then molded into a desired container shape in the molding zone.

[0003] As such a thermoplastic resin laminated foam sheet, for example, a polystyrene-based resin laminated foam sheet has been reported in which a polystyrene-based foam sheet has a specific polystyrene-based resin containing a specific amount of a specific impact-resistant polystyrene as a base resin and a polyolefin-based resin film is adhesively laminated on one side of the polystyrene-based foam sheet (Patent Document 1).

[0004] Such polystyrene-based resin laminated foam sheets are used in large quantities as materials for containers for prepared foods, boxed lunches, etc., used in convenience stores, supermarkets, etc. In recent years, the number of microwaveable containers made by deep drawing, etc., has been increasing, and high moldability is required.

[0005] In order to obtain a polystyrene-based resin laminated foam sheet with high moldability, it is necessary that the polystyrene-based resin foam sheet as a main component has high moldability. As a means for improving the moldability of the polystyrene-based resin foam sheet, for example, a laminate of a heat-resistant polystyrene-based resin foam layer and a polystyrene-based resin foam layer having lower heat resistance than the heat-resistant polystyrene-based resin foam layer is used. When a polystyrene-based resin foam sheet having such a laminate is used in a molding machine equipped with a cavity and a plug, it is necessary to increase the heater temperature on the heat-resistant polystyrene-based resin foam layer side (plug side) having a high softening temperature. However, if the heater temperature on the plug side is increased, a problem occurs in that the molded product sticks to the plug when it is released from the mold. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2018-44086 A Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention has been made to solve the above-mentioned problems in the conventional art, and an object of the present invention is to provide a polystyrene-based resin laminated foam sheet comprising a polystyrene-based resin foam sheet, which has excellent moldability, and to provide a polystyrene-based resin laminated foam container molded from the polystyrene-based resin laminated foam sheet. [Means for solving the problem]

[0008] The polystyrene-based resin laminated foam sheet according to an embodiment of the present invention is A laminated polystyrene resin foam sheet comprising a polystyrene resin foam sheet (A), The polystyrene-based resin foam sheet (A) includes a laminate of a first polystyrene-based resin foam layer having a glass transition temperature of 110° C. or higher and a second polystyrene-based resin foam layer having a glass transition temperature lower than that of the first polystyrene-based resin foam layer, When the average surface roughness of the surface roughness in the MD direction Ra1 (MD) and the surface roughness in the TD direction Ra1 (TD) of the first polystyrene-based resin foamed layer is R1 (= (Ra1 (MD) + Ra1 (TD)) / 2), and the average surface roughness of the surface roughness in the MD direction Ra2 (MD) and the surface roughness in the TD direction Ra2 (TD) of the second polystyrene-based resin foamed layer is R2 (= (Ra2 (MD) + Ra2 (TD)) / 2), (R1 / R2) is 1.1 to 3.0.

[0009] In one embodiment, the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention has an apparent density of 0.05 g / cm 3 ~0.16g / cm 3 It is.

[0010] In one embodiment, the first polystyrene-based resin foam layer is a heat-resistant polystyrene-based resin foam layer, and the second polystyrene-based resin foam layer is a general-purpose polystyrene-based resin foam layer.

[0011] A polystyrene-based resin laminate foam container according to an embodiment of the present invention is obtained by molding the above-mentioned polystyrene-based resin laminate foam sheet into a container shape. Effect of the Invention

[0012] According to the present invention, it is possible to provide a polystyrene-based resin laminated foam sheet comprising a polystyrene-based resin foam sheet, which has excellent moldability, and to provide a polystyrene-based resin laminated foam container molded from the polystyrene-based resin laminated foam sheet. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic cross-sectional view of one embodiment of the laminated polystyrene resin foam sheet of the present invention. [Diagram 2] FIG. 2 is a typical schematic perspective view of a laminated polystyrene resin foam container according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0015] In this specification, "(meth)acrylic" means acrylic and / or methacrylic, and "(meth)acrylate" means acrylate and / or methacrylate.

[0016] <<Polystyrene resin laminated foam sheet>> The laminated polystyrene resin foam sheet according to the embodiment of the present invention includes a polystyrene resin foam sheet (A).

[0017] The polystyrene resin foam sheet (A) includes a laminate of a first polystyrene resin foam layer having a glass transition temperature of 110° C. or higher and a second polystyrene resin foam layer having a glass transition temperature lower than that of the first polystyrene resin foam layer.

[0018] The first polystyrene-based resin foam layer may be a single layer or may be two or more layers.

[0019] The second polystyrene-based resin foam layer may be only one layer, or may be two or more layers.

[0020] The polystyrene resin foam sheet (A) may consist, for example, of only a laminate of a first polystyrene resin foam layer and a second polystyrene resin foam layer.

[0021] The polystyrene-based resin foam sheet (A) may contain any other appropriate layer as long as it contains a laminate of a first polystyrene-based resin foam layer and a second polystyrene-based resin foam layer, as long as the effects of the present invention are not impaired.

[0022] The polystyrene-based resin laminate foam sheet according to the embodiment of the present invention may contain any other appropriate layer as long as it contains the polystyrene-based resin foam sheet (A) within a range that does not impair the effects of the present invention.

[0023] In the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention, when the average surface roughness of the surface roughness in the MD direction Ra1 (MD) and the surface roughness in the TD direction Ra1 (TD) of the first polystyrene-based resin foam layer is R1 (= (Ra1 (MD) + Ra1 (TD)) / 2), and the average surface roughness of the surface roughness in the MD direction Ra2 (MD) and the surface roughness in the TD direction Ra2 (TD) of the second polystyrene-based resin foam layer is R2 (= (Ra2 (MD) + Ra2 (TD)) / 2), (R1 / R2) is 1.1 to 3.0. By adjusting (R1 / R2) within the above range, the effect of the present invention can be more effectively exhibited.

[0024] (R1 / R2) is preferably 1.1 to 2.9, more preferably 1.1 to 2.8, and further preferably 1.15 to 2.75.

[0025] The average surface roughness R1 is preferably 3.0 μm to 8.0 μm, more preferably 3.3 μm to 7.7 μm, even more preferably 3.6 μm to 7.3 μm, and particularly preferably 4.0 μm to 7.0 μm, in terms of being able to better exhibit the effects of the present invention.

[0026] The average surface roughness R2 is preferably 1.8 μm to 5.0 μm, more preferably 1.9 μm to 4.7 μm, even more preferably 2.0 μm to 4.3 μm, and particularly preferably 2.1 μm to 4.0 μm, in terms of being able to better exhibit the effects of the present invention.

[0027] The thickness of the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention may be any appropriate thickness within a range that does not impair the effects of the present invention. In terms of being able to more effectively exhibit the effects of the present invention, the thickness of the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention is preferably 0.5 mm to 4.0 mm, more preferably 0.8 mm to 3.5 mm, even more preferably 1.0 mm to 3.0 mm, and particularly preferably 1.1 mm to 2.5 mm.

[0028] The polystyrene-based resin laminate foam sheet according to the embodiment of the present invention may have any suitable basis weight as long as the effects of the present invention are not impaired. In order to more effectively exhibit the effects of the present invention, the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention preferably has a basis weight of 120 g / m 2 ~280g / m 2 and more preferably 130 g / m 2 ~270g / m 2 and more preferably 140 g / m 2 ~260g / m 2 and particularly preferably 150 g / m 2 ~250g / m 2 It is.

[0029] The apparent density of the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention may be any appropriate apparent density within a range that does not impair the effects of the present invention. In order to more effectively exhibit the effects of the present invention, the apparent density of the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention is preferably 0.05 g / cm. 3 ~0.16g / cm 3 and more preferably 0.06 g / cm 3 ~0.15g / cm 3 and more preferably 0.07 g / cm 3 ~0.15g / cm 3 and particularly preferably 0.08 g / cm 3 ~0.14g / cm 3 It is.

[0030] The average bubble diameter of the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention may be any appropriate average bubble diameter within a range that does not impair the effects of the present invention. The average bubble diameter of the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention is preferably 80 μm to 450 μm, more preferably 120 μm to 420 μm, further preferably 160 μm to 370 μm, and particularly preferably 200 μm to 350 μm, in terms of further exhibiting the effects of the present invention.

[0031] The average cell diameter of the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention is calculated by the cube root of (dM×dT×dV) using the average cell diameter dM (mm) in the MD direction, the average cell diameter dT (mm) in the TD direction, and the average cell diameter dV (mm) in the VD direction. Average bubble diameter d(mm)=(dM(mm)×dT(mm)×dV(mm)) (1 / 3)

[0032] In the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention, the first polystyrene-based resin foam layer is preferably a heat-resistant polystyrene-based resin foam layer, and the second polystyrene-based resin foam layer is preferably a general-purpose polystyrene-based resin foam layer.

[0033] The polystyrene-based resin laminated foam sheet according to the embodiment of the present invention may be provided with a non-foamed film containing a thermoplastic resin. When the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention is provided with a non-foamed film containing a thermoplastic resin, the non-foamed film containing a thermoplastic resin may be disposed on the first polystyrene-based resin foam layer side or on the second polystyrene-based resin foam layer side. When the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention is provided with an impact-resistant polystyrene-based resin film described below, the non-foamed film containing a thermoplastic resin may be provided on the opposite side of the impact-resistant polystyrene-based resin film from the polystyrene-based resin foam sheet (A) or on the opposite side of the impact-resistant polystyrene-based resin film from the polystyrene-based resin foam sheet (A).

[0034] The polystyrene-based resin laminate foam sheet according to the embodiment of the present invention may be provided with an impact-resistant polystyrene-based resin film. When the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention is provided with the non-foamed film containing the thermoplastic resin, the impact-resistant polystyrene-based resin film may be provided on the side of the polystyrene-based resin foam sheet (A) opposite to the non-foamed film containing the thermoplastic resin, or may be provided on the side of the polystyrene-based resin foam sheet (A) opposite to the non-foamed film containing the thermoplastic resin. The impact-resistant polystyrene-based resin film is preferably disposed on the first polystyrene-based resin foam layer side of the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention.

[0035] Fig. 1 is a schematic cross-sectional view of one embodiment of the polystyrene-based resin laminated foam sheet of the present invention. In Fig. 1, the polystyrene-based resin laminated foam sheet 100 according to one embodiment of the present invention includes a polystyrene-based resin foam sheet (A) 10 which is a laminate of a first polystyrene-based resin foam layer 11 and a second polystyrene-based resin foam layer 12, a non-foamed film 30 containing a thermoplastic resin on one side thereof, and a non-foamed film 40 containing a thermoplastic resin on the other side thereof. In Fig. 1, the first polystyrene-based resin foam layer 11 is a heat-resistant polystyrene-based resin foam layer, and the second polystyrene-based resin foam layer 12 is a general-purpose polystyrene-based resin foam layer. In Fig. 1, the surface of the non-foamed film 30 is 30a, and the surface of the non-foamed film 40 is 40a.

[0036] The glass transition temperature of the second polystyrene-based resin foam layer is lower than the glass transition temperature of the first polystyrene-based resin foam layer, and in order to more effectively exhibit the effects of the present invention, the glass transition temperature of the second polystyrene-based resin foam layer is preferably 80°C or higher and lower than 110°C, more preferably 90°C to 109°C, even more preferably 95°C to 107°C, and particularly preferably 98°C to 105°C.

[0037] In the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention, the density of the surface layer (a portion 200 μm thick from the surface) on the first polystyrene-based resin foam layer side of the polystyrene-based resin foam sheet (A) (hereinafter, sometimes referred to as the surface layer density) is preferably higher than the apparent density of the entire polystyrene-based resin foam sheet (A). This enhances the impact resistance of the polystyrene-based resin foam sheet (A). The surface layer having a density higher than the entire apparent density may be formed on one side or both sides of the polystyrene-based resin foam sheet (A). The surface layer density can be adjusted to an arbitrary range by adjusting the temperature or air volume of the cooling air, the temperature of the circular die, or the cooling temperature at the mandrel when producing the polystyrene-based resin foam sheet (A). The ratio expressed by (surface layer density / overall apparent density) (hereinafter, sometimes referred to as the surface layer density ratio) is preferably 1.5 to 2.5, more preferably 1.8 to 2.2. When the surface layer density ratio is within the above range, the impact resistance of the polystyrene-based resin foamed sheet (A) is increased and foamability suitable for molding can be exhibited.

[0038] <First polystyrene resin foam layer> The first polystyrene-based resin foam layer is typically formed by foaming a polystyrene-based resin (I). The first polystyrene-based resin foam layer is typically obtained by extruding and foaming a resin composition containing a polystyrene-based resin (I) and a foaming agent. More specifically, the first polystyrene-based resin foam layer is typically formed by heating and melting and kneading the polystyrene-based resin (I), the foaming agent, and various additives such as a cell regulator added as necessary together in an extruder, cooling to a predetermined temperature, extruding the resulting mixture from a die into a sheet shape, foaming the resulting mixture, and immediately cooling the resulting mixture. The polystyrene-based resin foam sheet according to the embodiment of the present invention is a polystyrene-based resin laminated foam sheet including a polystyrene-based resin foam sheet (A) which is a laminate of a first polystyrene-based resin foam layer and a second polystyrene-based resin foam layer, and the first polystyrene-based resin foam layer is typically obtained as the polystyrene-based resin foam sheet (A) by co-extrusion with the second polystyrene-based resin foam layer.

[0039] The thickness of the first polystyrene-based resin foam layer may be any appropriate thickness within a range that does not impair the effects of the present invention. In order to further exhibit the effects of the present invention, the thickness of the first polystyrene-based resin foam layer is preferably 0.50 mm to 1.50 mm, more preferably 0.60 mm to 1.35 mm, even more preferably 0.70 mm to 1.30 mm, and particularly preferably 0.65 mm to 1.25 mm.

[0040] The apparent density of the first polystyrene-based resin foam layer may be any appropriate apparent density within a range that does not impair the effects of the present invention. In order to more effectively exhibit the effects of the present invention, the apparent density of the first polystyrene-based resin foam layer is preferably 0.01 g / cm. 3 ~0.30g / cm 3 and more preferably 0.03 g / cm 3 ~0.25g / cm 3 and more preferably 0.05 g / cm 3 ~0.2g / cm 3 and particularly preferably 0.06 g / cm 3 ~0.15g / cm 3 The apparent density of the first polystyrene-based resin foam layer is measured, for example, by the method described in JIS K7222:1999 "Foamed plastics and rubber - Measurement of apparent density".

[0041] The glass transition temperature of the first polystyrene-based resin foam layer is 110°C or higher. In order to further exert the effects of the present invention, the glass transition temperature of the first polystyrene-based resin foam layer is preferably 110°C to 150°C, more preferably 113°C to 140°C, even more preferably 115°C to 130°C, and particularly preferably 117°C to 125°C.

[0042] The polystyrene resin (I) may be one type of polystyrene resin or a mixture of two or more types of polystyrene resins.

[0043] In obtaining the first polystyrene-based resin foam layer, in order to more effectively exhibit the effects of the present invention, the content of the foaming agent relative to 100 parts by mass of the polystyrene-based resin (I) is preferably 0.5 parts by mass to 6.0 parts by mass, more preferably 1.0 parts by mass to 5.5 parts by mass, even more preferably 1.5 parts by mass to 5.0 parts by mass, and particularly preferably 2.0 parts by mass to 4.5 parts by mass.

[0044] Examples of the polystyrene-based resin (I) include homopolymers of styrene-based monomers such as styrene, α-methylstyrene, vinyltoluene, ethylstyrene, i-propylstyrene, t-butylstyrene, dimethylstyrene, bromostyrene, and chlorostyrene; copolymers of the above-mentioned styrene-based monomers; copolymers of the above-mentioned styrene-based monomers and (meth)acrylic acid; copolymers of the above-mentioned styrene-based monomers and (meth)acrylic acid esters (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cetyl (meth)acrylate, etc.); copolymers of the above-mentioned styrene-based monomers and bifunctional styrene monomers (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cetyl (meth)acrylate, etc.); Examples of the styrene monomer include copolymers of styrene monomers and functional monomers (e.g., (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, alkylene glycol dimethacrylate, etc.); copolymers of styrene monomers and rubber components such as butadiene, and mixtures or polymers of homopolymers of styrene monomers or copolymers thereof, copolymers of styrene monomers and vinyl monomers copolymerizable with the styrene monomers, and diene rubber-like polymers, which are so-called high impact polystyrenes (high impact polystyrene, HIPS); etc. The styrene monomer preferably contains at least styrene. The content of styrene relative to the total amount of the styrene monomers is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and particularly preferably 95% by mass or more.

[0045] Examples of vinyl monomers polymerizable with the above-mentioned styrene-based monomers include (meth)acrylic acid esters (e.g., methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, cetyl (meth)acrylate, etc.), bifunctional monomers (e.g., (meth)acrylonitrile, dimethyl maleate, dimethyl fumarate, diethyl fumarate, ethyl fumarate, divinylbenzene, alkylene glycol dimethacrylate, etc.), etc. These may be used alone or in combination of two or more kinds.

[0046] Examples of the diene rubber-like polymer include polybutadiene, styrene-butadiene copolymer, styrene-butadiene-styrene copolymer (SBS), styrene-butadiene-butylene-styrene copolymer (SBBS), styrene-ethylene-butylene-styrene block copolymer (SEBS), styrene-ethylene-propylene-styrene block copolymer (SEPS), styrene-isoprene-styrene block copolymer (SIPS), ethylene-propylene-non-conjugated diene three-dimensional copolymer, acrylonitrile-butadiene-styrene copolymer, etc. These may be used alone or in combination of two or more kinds.

[0047] In one embodiment, the polystyrene resin (I) may be a composite resin of a polystyrene resin and a polyolefin resin. The content ratio of the polystyrene resin to the polyolefin resin in the composite resin (polystyrene resin / polyolefin resin: mass ratio) is preferably 50 / 50 to 90 / 10, more preferably 60 / 40 to 85 / 15. If the content of the polystyrene resin is too low, the foamability and / or moldability may be insufficient. If the content of the polystyrene resin is too high, the impact resistance and / or flexibility may be insufficient.

[0048] As the polyolefin resin, any suitable olefin resin may be adopted as long as it does not impair the effects of the present invention. The polyolefin resin may be one type or two or more types. Specific examples of the polyolefin resin include polyethylene resins such as branched low density polyethylene, linear low density polyethylene, medium density polyethylene, high density polyethylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, and crosslinked bodies of these polymers; polypropylene resins such as propylene homopolymer, propylene-vinyl acetate copolymer, ethylene-propylene random copolymer, propylene-1-butene copolymer, and ethylene-propylene-butene random copolymer; and the like. Among these polyolefin resins, preferred are ethylene-vinyl acetate copolymer, high density polyethylene, linear low density polyethylene, and mixtures thereof. The low density is preferably 0.91 g / cm 3 ~0.94g / cm 3 and more preferably 0.91 g / cm 3 ~0.93g / cm 3 The high density is preferably 0.95 g / cm 3 ~0.97g / cm 3 and more preferably 0.95 g / cm 3 ~0.96g / cm 3 Medium density is a density between low and high density.

[0049] The polystyrene-based resin (I) may be a polystyrene-based resin made from recycled raw materials.

[0050] As the polystyrene resin (I) forming the first polystyrene resin foam layer, any suitable polystyrene resin may be used as long as the effects of the present invention are not impaired. As such a polystyrene resin (I), a heat-resistant polystyrene resin may be preferably used.

[0051] The polystyrene resin (I) forming the first polystyrene resin foam layer preferably contains at least one selected from the group consisting of a styrene-acrylic acid copolymer and a styrene-methacrylic acid copolymer. The content of at least one selected from the group consisting of a styrene-acrylic acid copolymer and a styrene-methacrylic acid copolymer in the polystyrene resin (I) forming the first polystyrene resin foam layer is preferably 50% by mass to 99% by mass, more preferably 60% by mass to 98% by mass, even more preferably 70% by mass to 97% by mass, and particularly preferably 75% by mass to 96% by mass, in order to further exhibit the effects of the present invention.

[0052] The polystyrene-based resin (I) forming the first polystyrene-based resin foam layer more preferably contains at least one selected from the group consisting of a copolymer of a styrene-based monomer and a diene-based monomer (such as butadiene), and a so-called high impact polystyrene (HIPS), which is a homopolymer of a styrene-based monomer or a copolymer thereof, or a copolymer of a styrene-based monomer and a vinyl monomer copolymerizable with the styrene-based monomer, and a mixture or polymer of a diene-based rubber polymer.

[0053] The content of at least one selected from the group consisting of a copolymer of a styrene monomer and a diene monomer, and a homopolymer of a styrene monomer or a copolymer thereof, or a copolymer of a styrene monomer and a vinyl monomer copolymerizable with the styrene monomer, and a mixture or polymer of a diene rubber polymer in the polystyrene resin (I) forming the first polystyrene resin foam layer is preferably 1% by mass to 50% by mass, more preferably 2% by mass to 40% by mass, even more preferably 3% by mass to 30% by mass, and particularly preferably 4% by mass to 25% by mass, in order to further exhibit the effects of the present invention.

[0054] The first polystyrene-based resin foam layer is typically obtained by extrusion foaming a resin composition containing a polystyrene-based resin (I) and a foaming agent.

[0055] As the blowing agent, any appropriate blowing agent can be used as long as it does not impair the effects of the invention. Examples of such blowing agents include propane, i-butane, n-butane, i-pentane, n-pentane, N 2 , CO 2 , N 2 / CO 2 , water, water and -OH, -COOH, -CN, -NH 3 , -OSO 3 H, -NH, CO, NH 2 , -CONH 2 , -COOR, -CHSO 3 H, -SO 3 H, -COONH 4 and mixtures thereof. In terms of being able to more effectively exhibit the effects of the present invention, the foaming agent is preferably at least one selected from i-butane and n-butane. As the foaming agent, an organic foaming agent may be used. Examples of the organic foaming agent include azodicarboxylic acid amide, dinitropentamethylenetetramine, and 4,4'-oxybis(benzenesulfonylhydrazide).

[0056] In the present invention, it is preferable that the foaming agent contains as little dimethyl ether as possible. By containing as little dimethyl ether as possible, it is possible to safely mass-produce polystyrene resin foamed sheets without using dimethyl ether, which is a highly flammable, explosive, and harmful combustible high-pressure gas. The content of dimethyl ether in the foaming agent is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably substantially 0% by mass.

[0057] The resin composition containing the polystyrene resin (I) and the foaming agent may contain additives such as a cell regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant (including a pigment), a deodorant, a foam nucleating agent, a nucleating agent, a lubricant, a flame retardant, an antistatic agent, etc. The additives may be of only one kind or of two or more kinds.

[0058] Examples of the foam regulator include inorganic powders such as talc and silica; acid salts of polycarboxylic acids; and reaction mixtures of polycarboxylic acids with sodium carbonate or sodium bicarbonate.

[0059] Examples of the stabilizer include calcium zinc-based heat stabilizers, tin-based heat stabilizers, and lead-based heat stabilizers.

[0060] Examples of the ultraviolet ray absorbent include cesium oxide-based ultraviolet ray absorbents and titanium oxide-based ultraviolet ray absorbents.

[0061] Examples of the antioxidant include cerium oxide, cerium oxide / zirconia solid solution, cerium hydroxide, carbon, carbon nanotubes, titanium oxide, and fullerene.

[0062] Examples of colorants include titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine blue, cobalt blue, calcined pigments, metallic pigments, mica, pearl pigments, zinc oxide, precipitated silica, and cadmium red.

[0063] Examples of deodorants include silica, zeolite, zirconium phosphate, and calcined hydrotalcite.

[0064] <Second polystyrene resin foam layer> The second polystyrene-based resin foam layer is typically formed by foaming the polystyrene-based resin (II). The second polystyrene-based resin foam layer is typically obtained by extruding and foaming a resin composition containing the polystyrene-based resin (II) and a foaming agent. More specifically, the second polystyrene-based resin foam layer is typically formed by heating and melting the polystyrene-based resin (II), the foaming agent, and various additives such as a cell regulator added as necessary together in an extruder, kneading the mixture, cooling to a predetermined temperature, extruding the mixture from a die into a sheet shape, foaming the mixture, and immediately cooling the mixture. The polystyrene-based resin foam sheet according to the embodiment of the present invention is a polystyrene-based resin laminated foam sheet including the polystyrene-based resin foam sheet (A) which is a laminate of the first polystyrene-based resin foam layer and the second polystyrene-based resin foam layer, and the second polystyrene-based resin foam layer is typically obtained as the polystyrene-based resin foam sheet (A) by co-extrusion with the first polystyrene-based resin foam layer.

[0065] The thickness of the second polystyrene-based resin foam layer may be any appropriate thickness within a range that does not impair the effects of the present invention. The thickness of the second polystyrene-based resin foam layer is preferably 0.50 mm to 1.50 mm, more preferably 0.60 mm to 1.35 mm, further preferably 0.70 mm to 1.30 mm, and particularly preferably 0.65 mm to 1.25 mm, in order to further exhibit the effects of the present invention.

[0066] The apparent density of the second polystyrene-based resin foam layer may be any appropriate apparent density within a range that does not impair the effects of the present invention. In order to more effectively exhibit the effects of the present invention, the apparent density of the second polystyrene-based resin foam layer is preferably 0.01 g / cm. 3 ~0.30g / cm 3 and more preferably 0.03 g / cm 3 ~0.25g / cm 3 and more preferably 0.05 g / cm 3 ~0.2g / cm 3 and particularly preferably 0.06 g / cm 3 ~0.15g / cm 3The apparent density of the second polystyrene-based resin foam layer is measured, for example, by the method described in JIS K7222:1999 "Foamed plastics and rubber - Measurement of apparent density".

[0067] The glass transition temperature of the second polystyrene-based resin foam layer is lower than the glass transition temperature of the first polystyrene-based resin foam layer, and in order to more effectively exhibit the effects of the present invention, the glass transition temperature of the second polystyrene-based resin foam layer is preferably less than 110°C, more preferably 80°C or higher and less than 110°C, even more preferably 90°C to 109°C, particularly preferably 95°C to 107°C, and most preferably 98°C to 105°C.

[0068] The polystyrene resin (II) may be one type of polystyrene resin or a mixture of two or more types of polystyrene resins.

[0069] In obtaining the second polystyrene-based resin foam layer, in order to more effectively exhibit the effects of the present invention, the content of the foaming agent relative to 100 parts by mass of the polystyrene-based resin (II) is preferably 0.5 parts by mass to 6.0 parts by mass, more preferably 1.0 parts by mass to 5.5 parts by mass, even more preferably 1.5 parts by mass to 5.0 parts by mass, and particularly preferably 2.0 parts by mass to 4.5 parts by mass.

[0070] As the polystyrene resin (II) forming the second polystyrene resin foam layer, any suitable polystyrene resin may be used as long as the effects of the present invention are not impaired. As such a polystyrene resin (II), a general-purpose polystyrene resin (GPPS) may be preferably used.

[0071] The polystyrene resin (II) forming the second polystyrene resin foam layer preferably contains at least one selected from the group consisting of homopolymers or copolymers of styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, and vinylxylene. The content ratio of at least one selected from the group consisting of homopolymers or copolymers of styrene, methylstyrene, ethylstyrene, isopropylstyrene, dimethylstyrene, paramethylstyrene, chlorostyrene, bromostyrene, vinyltoluene, and vinylxylene in the polystyrene resin (II) forming the second polystyrene resin foam layer is preferably 60% by mass to 99% by mass, more preferably 70% by mass to 98% by mass, even more preferably 80% by mass to 97% by mass, and particularly preferably 90% by mass to 97% by mass, in terms of being able to further exhibit the effects of the present invention.

[0072] The polystyrene resin (II) forming the second polystyrene resin foam layer more preferably contains at least one selected from the group consisting of copolymers of a styrene monomer and a diene monomer (such as butadiene), and so-called high impact polystyrene (HIPS), which is a mixture or polymer of a homopolymer of a styrene monomer, a copolymer thereof, or a copolymer of a styrene monomer and a vinyl monomer copolymerizable with the styrene monomer, and a diene rubber polymer.

[0073] The content of at least one selected from the group consisting of a copolymer of a styrene monomer and a diene monomer, and a homopolymer of a styrene monomer or a copolymer thereof, or a copolymer of a styrene monomer and a vinyl monomer copolymerizable with the styrene monomer, and a mixture or polymer of a diene rubber polymer in the polystyrene resin (II) forming the second polystyrene resin foam layer is preferably 1% by mass to 40% by mass, more preferably 2% by mass to 30% by mass, even more preferably 3% by mass to 20% by mass, and particularly preferably 3% by mass to 10% by mass, in order to further exhibit the effects of the present invention.

[0074] The second polystyrene-based resin foam layer is typically obtained by extrusion foaming a resin composition containing the polystyrene-based resin (II) and a foaming agent.

[0075] As the blowing agent, any appropriate blowing agent can be used as long as it does not impair the effects of the present invention. Examples of such blowing agents include propane, i-butane, n-butane, i-pentane, n-pentane, N 2 , CO 2 , N 2 / CO 2 , water, water and -OH, -COOH, -CN, -NH 3 , -OSO 3 H, -NH, CO, NH 2 , -CONH 2 , -COOR, -CHSO 3 H, -SO 3 H, -COONH 4 and mixtures thereof. In terms of being able to more effectively exhibit the effects of the present invention, the foaming agent is preferably at least one selected from i-butane and n-butane. As the foaming agent, an organic foaming agent may be used. Examples of the organic foaming agent include azodicarboxylic acid amide, dinitropentamethylenetetramine, and 4,4'-oxybis(benzenesulfonylhydrazide).

[0076] In the present invention, it is preferable that the foaming agent contains as little dimethyl ether as possible. By containing as little dimethyl ether as possible, it is possible to safely mass-produce polystyrene resin foamed sheets without using dimethyl ether, which is a highly flammable, explosive, and harmful combustible high-pressure gas. The content of dimethyl ether in the foaming agent is preferably 50% by mass or less, more preferably 30% by mass or less, even more preferably 10% by mass or less, particularly preferably 5% by mass or less, and most preferably substantially 0% by mass.

[0077] The resin composition containing the polystyrene resin (II) and the foaming agent may contain additives such as a cell regulator, a stabilizer, an ultraviolet absorber, an antioxidant, a colorant (including a pigment), a deodorant, a foam nucleating agent, a nucleating agent, a lubricant, a flame retardant, an antistatic agent, etc. The additives may be of only one kind or of two or more kinds.

[0078] Examples of the foam regulator include inorganic powders such as talc and silica; acid salts of polycarboxylic acids; and reaction mixtures of polycarboxylic acids with sodium carbonate or sodium bicarbonate.

[0079] Examples of the stabilizer include calcium zinc-based heat stabilizers, tin-based heat stabilizers, and lead-based heat stabilizers.

[0080] Examples of the ultraviolet ray absorbent include cesium oxide-based ultraviolet ray absorbents and titanium oxide-based ultraviolet ray absorbents.

[0081] Examples of the antioxidant include cerium oxide, cerium oxide / zirconia solid solution, cerium hydroxide, carbon, carbon nanotubes, titanium oxide, and fullerene.

[0082] Examples of colorants include titanium oxide, carbon black, titanium yellow, iron oxide, ultramarine blue, cobalt blue, calcined pigments, metallic pigments, mica, pearl pigments, zinc oxide, precipitated silica, and cadmium red.

[0083] Examples of deodorants include silica, zeolite, zirconium phosphate, and calcined hydrotalcite.

[0084] <Non-foamed film containing thermoplastic resin> The polystyrene-based resin laminated foam sheet according to the embodiment of the present invention may be provided with a non-foamed film containing a thermoplastic resin. When the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention is provided with a non-foamed film containing a thermoplastic resin, the non-foamed film containing a thermoplastic resin may be disposed on the first polystyrene-based resin foam layer side or on the second polystyrene-based resin foam layer side. When the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention is provided with an impact-resistant polystyrene-based resin film described below, the non-foamed film containing a thermoplastic resin may be provided on the opposite side of the impact-resistant polystyrene-based resin film from the polystyrene-based resin foam sheet (A) or on the opposite side of the impact-resistant polystyrene-based resin film from the polystyrene-based resin foam sheet (A).

[0085] By laminating a non-foamed film containing a thermoplastic resin, the surface of the polystyrene-based resin laminated foamed sheet according to the embodiment of the present invention becomes more beautiful, the rigidity becomes higher, and the heat resistance and oil resistance are further improved.

[0086] Examples of thermoplastic resins that form the non-foamed film containing a thermoplastic resin include polystyrene resins, impact-resistant polystyrene resins, polyethylene resins, polypropylene resins, polyethylene terephthalate resins, polyphenylene ether resins, polyvinylidene chloride resins, ethylene-vinyl alcohol copolymer resins, etc. These may be used alone or in combination of two or more kinds.

[0087] The non-foamed film containing a thermoplastic resin may be one layer or two or more layers. When it is two or more layers, the layers may be laminated by, for example, dry lamination.

[0088] A coloring agent (pigment, dye, etc.) may be added to the non-foamed film containing a thermoplastic resin. By adding a coloring agent (pigment, dye, etc.), it can be colored in various colors, and various patterns and designs can be displayed by printing on the surface.

[0089] The thickness of the non-foamed film containing a thermoplastic resin may be any appropriate thickness within a range that does not impair the effects of the present invention. In terms of being able to more effectively exhibit the effects of the present invention, such a thickness is preferably 10 μm to 150 μm, and more preferably 10 μm to 100 μm. If the thickness of the non-foamed film containing a thermoplastic resin is too thin outside the above range, the film may be difficult to stretch during thermoforming, and may be prone to defects. If the thickness of the non-foamed film containing a thermoplastic resin is too thick outside the above range, the cost may increase, and the film may not be laminated at a low temperature during lamination, resulting in a loss of gloss.

[0090] As a method for laminating the non-foamed film containing a thermoplastic resin, any appropriate method can be adopted as long as the effects of the present invention are not impaired. Examples of such a method include a method of laminating the non-foamed film containing a thermoplastic resin by co-extrusion, and a method of laminating the non-foamed film containing a thermoplastic resin using a heating roll, a binder, an adhesive, etc.

[0091] <Impact-resistant polystyrene resin film> The polystyrene-based resin laminate foam sheet according to the embodiment of the present invention may be provided with an impact-resistant polystyrene-based resin film. When the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention is provided with the non-foamed film containing the thermoplastic resin, the impact-resistant polystyrene-based resin film may be provided on the side of the polystyrene-based resin foam sheet (A) opposite to the non-foamed film containing the thermoplastic resin, or may be provided on the side of the polystyrene-based resin foam sheet (A) opposite to the non-foamed film containing the thermoplastic resin. The impact-resistant polystyrene-based resin film is preferably disposed on the first polystyrene-based resin foam layer side of the polystyrene-based resin laminate foam sheet according to the embodiment of the present invention.

[0092] The thickness of the impact-resistant polystyrene resin film may be any appropriate thickness depending on the purpose, as long as the effects of the present invention are not impaired. In consideration of various purposes, the thickness of the impact-resistant polystyrene resin film in the polystyrene resin laminate foam sheet according to the embodiment of the present invention is preferably 80 μm to 180 μm, more preferably 90 μm to 170 μm, further preferably 100 μm to 160 μm, and particularly preferably 120 μm to 150 μm. The thickness of the impact-resistant polystyrene resin film is preferably smaller than the thickness of the laminate of the polystyrene resin foam sheet (A).

[0093] The high impact polystyrene resin film is typically a non-foamed high impact polystyrene resin film.

[0094] The impact-resistant polystyrene resin film is typically formed from a polystyrene resin. More specifically, the polystyrene resin is preferably heated and melted in an extruder together with various additives added as necessary, kneaded, cooled to a predetermined temperature, and extruded from a die into a film shape to be formed. More specifically, in producing the polystyrene resin laminated foam sheet according to the embodiment of the present invention, the polystyrene resin is preferably heated and melted in an extruder together with various additives added as necessary, kneaded, cooled to a predetermined temperature, extruded from a die into a film shape, and laminated on the surface of the polystyrene resin foam sheet (A), as described later.

[0095] The polystyrene resin (III) forming the impact-resistant polystyrene resin film may be the polystyrene resin (I) or polystyrene resin (II) described above. In addition, the polystyrene resin (III) forming the impact-resistant polystyrene resin film may be a mixture of the polystyrene resin (I) or polystyrene resin (II) (other than high impact polystyrene) and high impact polystyrene. As the high impact polystyrene, any suitable high impact polystyrene may be used as long as it does not impair the effects of the present invention. As such high impact polystyrene, for example, one containing a styrene-butadiene copolymer dispersed in a salami structure and having a particle size of 0.3 μm to 10 μm may be mentioned. Further, examples of the polystyrene resin (III) forming the impact-resistant polystyrene resin film include linear low-density polyethylene, high-density polyethylene, low-density polyethylene, propylene homopolymer, ethylene-propylene random polymer, ethylene-propylene block polymer, ethylene-propylene-butene-terpolymer, ethylene-vinyl acetate copolymer, ethylene-unsaturated carboxylic acid ester copolymer (e.g., ethylene-methyl methacrylate copolymer), ethylene-unsaturated carboxylic acid metal salt copolymer (e.g., ethylene-magnesium (or zinc) acrylate copolymer), propylene-vinyl chloride copolymer, propylene-butene copolymer, propylene-maleic anhydride copolymer, propylene-olefin copolymer (propylene-ethylene copolymer, propylene-butene-1 copolymer), unsaturated carboxylic acid (e.g., maleic anhydride) modified polyethylene or polypropylene, ethylene-propylene rubber, atactic polypropylene, polyethylene terephthalate, polybutylene terephthalate, and mixtures thereof.

[0096] The polystyrene resin (III) forming the impact resistant polystyrene resin film is preferably high impact polystyrene, since it can more effectively exhibit the effects of the present invention.

[0097] The Vicat softening temperature of the polystyrene resin (III) forming the impact-resistant polystyrene resin film is preferably 90° C. or higher. The Vicat softening temperature of the polystyrene resin (III) forming the impact-resistant polystyrene resin film is 90° C. or higher, so that the film has not only impact resistance but also sufficient heat resistance. The upper limit of the Vicat softening temperature of the impact-resistant polystyrene is preferably 97° C. The Vicat softening temperature is a value measured by the A50 method based on JIS K7206:1999.

[0098] The polystyrene resin (III) may contain additives such as stabilizers, ultraviolet absorbers, antioxidants, colorants (including pigments), deodorants, lubricants, flame retardants, antistatic agents, etc. The additives may be of one type or of two or more types.

[0099] <<Production method of polystyrene-based resin laminated foam sheet>> The method for producing a polystyrene-based resin laminated foam sheet according to an embodiment of the present invention may employ any appropriate method within the scope of not impairing the effects of the present invention. The method for producing a polystyrene-based resin laminated foam sheet according to an embodiment of the present invention typically includes a step of producing a polystyrene-based resin foam sheet (A) and a step of producing and laminating an impact-resistant polystyrene-based resin film, in that the effects of the present invention can be more effectively exhibited. The method for producing a polystyrene-based resin laminated foam sheet according to an embodiment of the present invention preferably includes a step of producing a polystyrene-based resin foam sheet (A) and a step of producing and laminating an impact-resistant polystyrene-based resin film, in this order.

[0100] In the manufacturing process of the polystyrene-based resin foam sheet (A), typically, the polystyrene-based resin (I) forming the first polystyrene-based resin foam layer is heated and melted in a first extruder together with various additives such as a foaming agent and a bubble regulator added as necessary, and the polystyrene-based resin (II) forming the second polystyrene-based resin foam layer is heated and melted in a second extruder together with various additives such as a foaming agent and a bubble regulator added as necessary, and laminated and foamed by supplying to a joining die, and after cooling to a predetermined temperature as necessary, co-extruded from a die and immediately cooled. In this way, a laminate of the first polystyrene-based resin foam layer and the second polystyrene-based resin foam layer is manufactured. When a foaming gas is used as a foaming agent, the manufactured polystyrene-based resin foam sheet (A) is left for a while, and the foaming gas remaining in the polystyrene-based resin foam sheet (A) is replaced with air.

[0101] In a more specific preferred embodiment of the manufacturing process for the polystyrene-based resin foam sheet (A), the polystyrene-based resin (I) forming the first polystyrene-based resin foam layer is supplied to a first extruder together with a foaming agent and various additives such as a cell regulator added as necessary, and the polystyrene-based resin (II) forming the second polystyrene-based resin foam layer is supplied to a second extruder together with a foaming agent and various additives such as a cell regulator added as necessary, the molten resin extruded from the first extruder and the molten resin extruded from the second extruder are joined at a joining die, the molten resin joined at the joining die is separated into an outer peripheral side and an inner peripheral side, and extruded and foamed into a cylindrical shape, and a cylindrical foam having a two-layer structure is formed using a circular die or the like. The cylindrical foam extruded from the annular outlet of the circular die is fed to a cooling mandrel located downstream of the circular die (forward in the extrusion direction) and has a diameter larger than the outlet. The foam is drawn while the inner surface of the foam is in sliding contact with the outer circumferential surface of the cooling mandrel. The foam is expanded in diameter by the cooling mandrel and cooled from the inside. The foam is continuously cut in the extrusion direction by a cutter located downstream of the cooling mandrel and developed into a flat sheet, and then produced into a long ribbon.

[0102] In the manufacturing and laminating process of the impact-resistant polystyrene resin film, typically, the polystyrene resin (III) is heated, melted, and kneaded in an extruder together with various additives added as necessary, cooled to a predetermined temperature, extruded from a die into a film, and laminated on the surface of the polystyrene resin foam sheet (A) before it is completely cooled. This produces a laminate of the polystyrene resin foam sheet (A) and the impact-resistant polystyrene resin film.

[0103] As described above, when laminating a non-foamed film containing a thermoplastic resin on the side opposite the impact resistant polystyrene resin film as viewed from the polystyrene-based resin foam sheet (A) in the polystyrene-based resin laminated foam sheet according to an embodiment of the present invention, or on the side opposite the polystyrene-based resin foam sheet (A) as viewed from the impact resistant polystyrene resin film in the polystyrene-based resin laminated foam sheet according to an embodiment of the present invention, a method of laminating by co-extruding a non-foamed film containing a thermoplastic resin, or a method of laminating a non-foamed film containing a thermoplastic resin using a heated roll, a binder, an adhesive, or the like may be used.

[0104] After a laminate of the polystyrene-based resin foamed sheet (A) and the impact-resistant polystyrene-based resin film (which may further be laminated with a non-foamed film containing the above-mentioned thermoplastic resin, if necessary) is obtained, any appropriate treatment may be performed at any appropriate time depending on the desired physical properties.

[0105] Finally, a winding step may be carried out using a winding device such as a roll, thereby obtaining a roll-shaped laminated polystyrene resin foam sheet.

[0106] <Polystyrene-based resin laminated foam container> The polystyrene-based resin laminated foam container according to the embodiment of the present invention is obtained by forming the polystyrene-based resin laminated foam sheet according to the embodiment of the present invention into a container shape such that the first polystyrene-based resin foam layer side is the inside of the container and the second polystyrene-based resin foam layer side is the outside of the container, as shown in Fig. 2. In Fig. 2, the inside of the container of the polystyrene-based resin laminated foam container 1000 is 200, and the outside of the container is 300. Furthermore, a non-foamed film containing a thermoplastic resin may be disposed on the outermost surface of each of the inside and outside of the container.

[0107] To manufacture a polystyrene-based resin laminated foam container according to an embodiment of the present invention using the polystyrene-based resin laminated foam sheet according to an embodiment of the present invention, the polystyrene-based resin laminated foam sheet wound into a roll is heated to a constant temperature in the heating zone of a molding machine, and then molded into a desired container shape in the molding zone. The container shape can be, for example, a bowl shape, a cup shape, a box shape, a tray shape, or any other shape. EXAMPLES

[0108] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. The methods for measuring and evaluating each property are as follows.

[0109] <Thickness> Twenty-one arbitrary positions in the width direction (direction perpendicular to the extrusion flow direction) were used as measurement points. These measurement points were measured with a thickness measuring device (manufactured by Techlock Corporation, model: SM-125) to the nearest 0.01 mm. The arithmetic mean of these measurements was used as the thickness. In addition, the thicknesses of the first foam layer (first polystyrene-based resin foam layer) and the second foam layer (second polystyrene-based resin foam layer) were measured by slicing the boundaries of each layer with a slicer (splitting machine, model AB-320-D, manufactured by Fortuna, Germany) and using the measurement method described above.

[0110] <Basic weight> Excluding 20 mm from both ends in the width direction (direction perpendicular to the extrusion flow direction), ten pieces of 10 cm x 10 cm were cut out at equal intervals in the width direction, and the mass (g) of each piece was measured to the nearest 0.001 g. The average mass (g) of each piece was calculated using the formula: 2 The converted value is expressed as the mass per unit weight (g / m 2 ) was decided. In addition, the basis weight of the first foam layer (first polystyrene-based resin foam layer) and the second foam layer (second polystyrene-based resin foam layer) was measured by slicing the boundaries of each layer with a slicer (splitting machine, model AB-320-D, manufactured by Fortuna, Germany) and using the measurement method described above.

[0111] <Apparent density> 50cm to avoid changing the bubble structure. 3 The sheet was cut out to prepare a test piece, the mass and volume of the test piece were measured, and the overall apparent density was calculated using the following formula: The test piece was cut out from a sheet that was 72 hours or more old (maximum 90 days) after production, and left for 24 hours in an atmospheric condition of 23°C±2°C and 50RH%±5RH%. Apparent density (g / cm 3 ) = mass of test piece (g) ÷ volume of test piece (cm 3 )

[0112] <Surface density of the first foam layer (first polystyrene-based resin foam layer) and the second foam layer (second polystyrene-based resin foam layer)> Using a slicer (splitting machine, model AB-320-D, manufactured by Fortuna, Germany), each of the first foamed layer (first polystyrene-based resin foamed layer) and the second foamed layer (second polystyrene-based resin foamed layer) was sliced ​​to a thickness of 200 μm from the surface, and cut into a width of 25 mm and a length of 150 mm to obtain a surface layer. The mass and volume of the obtained surface layer were measured, and the surface layer density was calculated by the following formula. Note that the surface layer was cut out from a foamed sheet that had been produced for 72 hours or more (maximum 90 days) and left for 24 hours under atmospheric conditions of 23°C ± 2°C and 50 RH% ± 5 RH%. Surface density (g / cm 3 ) = mass of surface layer (g) ÷ volume of surface layer (cm3 )

[0113] <Average bubble diameter> The sheet was cut out perpendicularly to the surface of the original sheet from the center in the width direction along the MD direction (extrusion direction) and TD direction (direction perpendicular to the extrusion direction on the surface of the sheet). The cross section was photographed at a magnification of 50x using a scanning electron microscope (SU1510, Hitachi High-Technologies Corporation). The microscopic images were photographed so that the specified magnification would be achieved when two images (four images in total) were printed side by side on a single sheet of A4 paper in landscape orientation. Specifically, on the image, 60 mm arbitrary straight lines parallel to each of the MD and TD directions and 60 mm straight lines perpendicular to each direction (VD direction) were drawn, and two microscope images of a total of four fields of view were taken for each of the cross sections cut along the MD direction (MD cross section) and the cross sections cut along the TD direction (TD cross section), and printed on A4 paper. Three arbitrary straight lines (60 mm long) parallel to the MD direction were drawn on each of the two images of the MD cross section, and three arbitrary straight lines (60 mm long) parallel to the TD direction were drawn on each of the two images of the TD cross section. In addition, three straight lines (60 mm long) parallel to the VD direction were drawn on one image of the MD cross section and one image of the TD cross section, and six arbitrary straight lines of 60 mm long parallel to the MD, TD, and VD directions were drawn in each direction. Note that the arbitrary straight lines were made as far as possible so that bubbles would not come into contact only at the contact points, and if there was contact, the bubbles were also counted. The number of bubbles D counted for six arbitrary straight lines in each of the MD, TD, and VD directions was calculated as the arithmetic average, which was used as the number of bubbles in each direction. The average chord length t of the bubbles was calculated from the image magnification at which the number of bubbles was counted and the number of bubbles using the following formula. Average chord length t (mm) = 60 / (number of bubbles x image magnification) The image magnification was calculated by measuring the scale bar on the image to the nearest 1 / 100 mm using a Digimatic Caliper (manufactured by Mitutoyo Corporation) and using the following formula: Image magnification = Scale bar actual value (mm) / Scale bar display value (mm) The bubble diameter in each direction was calculated using the following formula. -Bubble diameter D(mm)=t / 0.616 Furthermore, the cube root of the product was determined as the average bubble diameter. Average bubble diameter (mm) = (DMD x DTD x DVD) 1 / 3 DMD: bubble diameter in MD direction (mm). DTD: bubble diameter in TD direction (mm). DVD: Bubble diameter in the VD direction (mm).

[0114] <Glass transition temperatures of the first foam layer (first polystyrene-based resin foam layer) and the second foam layer (second polystyrene-based resin foam layer)> The glass transition temperatures of the first foamed layer (first polystyrene-based resin foamed layer) and the second foamed layer (second polystyrene-based resin foamed layer) were measured as follows. (Pretreatment) Prior to measuring the glass transition temperature, 5 to 6 g of each of the first foam layer (first polystyrene-based resin foam layer) and the second foam layer (second polystyrene-based resin foam layer) was weighed out on a balance, sandwiched between two polytetrafluoroethylene sheets, and pressed and degassed as described below as a pretreatment. Press equipment: Toyo Seiki Co., Ltd., small press equipment "Lab Press 10T" Upper heater temperature: 180℃ Lower heater temperature: 180℃ Pressing process: pressing at 0.54 MPa for 3 minutes, performing 5 cycles of pressing, with one cycle consisting of "pressing at 0.54 MPa for 2 seconds" and "pressure release for 2 seconds", and then pressing at 15.5 MPa for 2 minutes. (Glass transition temperature: Tg) The glass transition temperature (midpoint glass transition temperature) (Tg) of the sample degassed as described above was measured by the method described in JIS K7121:1987 "Method of measuring glass transition temperature of plastics." However, the sampling method and temperature conditions were as follows. A DSC6220 type (manufactured by SII Nano Technology Co., Ltd.) was used as a differential scanning calorimeter, and about 6 mg of sample was filled into the bottom of an aluminum measurement container so that there were no gaps, and the sample was heated from 30°C to 220°C at a heating rate of 20°C / min under a nitrogen gas flow rate of 20 mL / min, held for 10 minutes, quickly removed, and allowed to cool in an environment of 25±10°C. The midpoint glass transition temperature was calculated from the DSC curve obtained when the sample was heated from 30°C to 220°C at a heating rate of 20°C / min (9.3 "How to determine the glass transition temperature"). Alumina was used as the reference material. The midpoint glass transition temperature was determined according to the standard (9.3 "Determination of glass transition temperature").

[0115] <Surface roughness> Using a Mitutoyo Surftest SJ201, the surface roughness of the first polystyrene foam layer and the second polystyrene foam layer was measured in the MD and TD directions at N=5 in the width direction. The average surface roughness of the surface roughness in the MD direction Ra1 (MD) and the surface roughness in the TD direction Ra1 (TD) of the first polystyrene-based resin foamed layer was defined as R1 (= (Ra1 (MD) + Ra1 (TD)) / 2), and the average surface roughness of the surface roughness in the MD direction Ra2 (MD) and the surface roughness in the TD direction Ra2 (TD) of the second polystyrene-based resin foamed layer was defined as R2 (= (Ra2 (MD) + Ra2 (TD)) / 2).

[0116] <Forming foam containers> Using the polystyrene resin laminated foam sheets obtained in the Examples and Comparative Examples, foam containers as shown in FIG. 2 were produced. The container was prepared so that the first polystyrene type resin foam layer was on the inside of the foam container and the second polystyrene type resin foam layer was on the outside of the foam container. The foaming container was a bowl-shaped container with an opening inner diameter of 140 mm, a bottom inner diameter of 100 mm, a depth of 80 mm, and a drawing ratio of 0.57. The preparation of the foam container will now be described in more detail. The foam containers were produced by continuously supplying a polystyrene resin laminated foam sheet to a press molding device having a cavity (concave mold) with 6 x 6 = 36 concave portions corresponding to the outer shape of the foam container, and a plug (convex mold) with the same number of convex portions corresponding to the inner shape of the container. The molding conditions were as follows: molding cycle for one shot (=36 pieces) was 10.0 seconds, heater temperature on the cavity side was set to 300°C, and heater temperature on the plug side was set to 370°C. The timing of molding was set so that the cavity and the plug came into contact with the laminated polystyrene resin foam sheet at almost the same time and molding was started.

[0117] <Plug adhesion evaluation> When the cavity and plug were released from the molded product, those in which there was no sticking between the sheet and the plug on the surface corresponding to the first foam layer were evaluated as "good", and those in which sticking occurred were evaluated as "bad".

[0118] <Moldability evaluation> The appearance of 25 foamed containers from the first shot, which was immediately after the start of operation of the press molding machine, and 25 foamed containers from the 30th shot, when the mold was thought to have been sufficiently warmed up through repeated molding, was observed. The foamed containers were then observed for any abnormalities in appearance, such as wrinkles or cracks (internal cracks). Those in which no abnormality was observed were rated as "○", and those in which abnormality was observed were rated as "×".

[0119] <List of base polymer materials for the first foam layer (first polystyrene-based resin foam layer)> Product name "T080": Toyo Styrene Co., Ltd., styrene-methacrylic acid copolymer resin, styrene monomer content = 92% by mass, methacrylic acid monomer content = 8% by mass Product name "G9001": manufactured by PSJ, styrene-methacrylic acid copolymer resin, styrene monomer content = 92% by mass, methacrylic acid monomer content = 8% by mass Product name "Tufprene 125": Styrene-butadiene block copolymer resin (SBS) manufactured by Asahi Kasei Chemicals Corporation Product name "AMM11": A blend of styrene-methacrylic acid copolymer and MBS resin (containing trans-butadiene block) manufactured by PSJ Product name "H8117": PSJ, cis-styrene-butadiene block copolymer resin

[0120] <List of base polymer materials for the second foam layer (second polystyrene-based resin foam layer)> Product name "HRM12": General-purpose polystyrene resin (GPPS) manufactured by Toyo Styrene Co., Ltd. Product name "E641N": Toyo Styrene Co., Ltd., high impact polystyrene (HIPS)

[0121] [Example 1] As the base polymer for the first foam layer, a mixed resin was prepared by mixing styrene-methacrylic acid copolymer resin (styrene monomer content = 92 mass%, methacrylic acid monomer content = 8 mass%) (product name "T080", manufactured by Toyo Styrene Co., Ltd.) and styrene-butadiene block copolymer resin (SBS: styrene block copolymer) (product name "Tufprene 125", manufactured by Asahi Kasei Chemicals Corporation) in a mass ratio of 95:5 (T080:Tufprene 125). In addition to the base polymer, a master batch (product name "DSM1401M") incorporating talc (air bubble regulator) was also prepared. The master batch was blended in a ratio of 0.6 parts by mass to 100 parts by mass of the mixed resin, and charged into a batch-type continuous mixer. After thorough mixing, the mixture was supplied to the hopper of the upstream extruder (screw diameter 90 mm) of a tandem extruder having a screw diameter of 90 mm and a screw diameter of 115 mm. In the upstream extruder, the maximum cylinder temperature was set to 280°C, and approximately 3.3 parts by mass (to 100 parts by mass of mixed resin) of mixed butane (isobutane:normal butane = 70:30 (mass ratio)) was added as a foaming agent midway, and the mixture was melt-kneaded together with the mixed resin and supplied to the downstream extruder. The downstream extruder was adapted to supply the molten mixture supplied from the upstream extruder to a joining die at a rate of 120 kg / h. Meanwhile, in another tandem extruder having a screw diameter of 90 mm and a screw diameter of 115 mm, the material for forming the second foam layer was melt-kneaded and supplied to the above-mentioned joining die. The material for forming the second foam layer was a mixed resin made by mixing GPPS (product name "HRM12", manufactured by Toyo Styrene) as the base polymer and HIPS (product name "E641N", manufactured by Toyo Styrene, high-impact polystyrene) in a mass ratio of 95:5 (HRM12:E641N). In addition to the base polymer, a master batch (product name "DSM1401M") incorporating talc (a bubble regulator) was also prepared. The master batch was blended in a ratio of 0.5 parts by mass to 100 parts by mass of the mixed resin, and charged into a batch-type continuous mixer. After thorough mixing, the mixture was supplied to the hopper of the upstream extruder (screw diameter 90 mm) of a tandem extruder having a screw diameter of 90 mm and a screw diameter of 115 mm. In the upstream extruder, the maximum cylinder temperature was set to 260°C, and approximately 3.0 parts by mass (to 100 parts by mass of mixed resin) of mixed butane (isobutane:normal butane = 70:30 (mass ratio)) was added as a foaming agent midway, and the mixture was melt-kneaded together with the mixed resin and supplied to the downstream extruder. The downstream extruder was adapted to supply the molten mixture supplied from the upstream extruder to a joining die at a rate of 120 kg / h. The two kinds of molten mixtures fed to the joining die were joined and laminated in the joining die, and the foamed mixture was fed to an annular die with a diameter of 200 mm and a slit clearance of 0.6 mm, and passed through the slit of the die to form a cylindrical foam. Immediately after that, the cylindrical foam was cooled by blowing air on it, and was taken along the outer surface of a cooling device (mandrel) with a diameter of 675 mm, and was further cut into two pieces along the extrusion direction to obtain a raw sheet of polystyrene resin foam (1) with a width of 1050 mm. The air temperature was 34°C, and the amount of air sprayed was 0.021 m on the inner second foam layer side. 3 / m 2 , 0.061m on the outer first foam layer side 3 / m 2 It was decided. In order to replace the foaming gas, the original roll of the obtained polystyrene-based resin laminated foam sheet (1) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene-based resin laminated foam sheet (1) was laminated with CPS 20 μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25 μm (Santox KT) and CPS 20 μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45 μm plain" to produce the polystyrene-based resin laminated foam sheet (1). The results are shown in Table 1.

[0122] [Example 2] A mixed resin of styrene-methacrylic acid copolymer resin (styrene monomer content = 92 mass%, methacrylic acid monomer content = 8 mass%) (product name "G9001", manufactured by PSJ) and styrene-butadiene block copolymer resin (SBS: styrene block copolymer) (product name "Tufprene 125", manufactured by Asahi Kasei Chemicals Corporation) mixed in a mass ratio of 95:5 (T080:Tufprene 125) was used as the base polymer of the first foam layer, and the extrusion conditions were changed as shown in Table 1. The same procedure as in Example 1 was performed to obtain a raw sheet of polystyrene-based resin foam sheet (2). In order to replace the foaming gas, the original roll of the obtained polystyrene-based resin laminated foam sheet (2) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene-based resin laminated foam sheet (2) was laminated with CPS 20 μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25 μm (Santox KT) and CPS 20 μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45 μm plain" to produce the polystyrene-based resin laminated foam sheet (2). The results are shown in Table 1.

[0123] [Example 3] A mixed resin of styrene-methacrylic acid copolymer resin (styrene monomer content = 92 mass%, methacrylic acid monomer content = 8 mass%) (product name "T080", manufactured by Toyo Styrene Co., Ltd.) and cis-type styrene-butadiene block copolymer resin (product name "H8117", manufactured by PSJ Co., Ltd.) mixed in a mass ratio of 80:20 (T080:H8117) was used as the base polymer of the first foam layer, and the extrusion conditions were changed as shown in Table 1. The same procedure as in Example 1 was performed to obtain a raw sheet of polystyrene-based resin foam sheet (3). In order to replace the foaming gas, the original roll of the obtained polystyrene-based resin laminated foam sheet (3) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene-based resin laminated foam sheet (3) was laminated with CPS 20 μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25 μm (Santox KT) and CPS 20 μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45 μm plain" to produce the polystyrene-based resin laminated foam sheet (3). The results are shown in Table 1.

[0124] [Example 4] As the base polymer of the first foam layer, a styrene-methacrylic acid copolymer resin (styrene monomer content = 92 mass%, methacrylic acid monomer content = 8 mass%) (product name "T080", manufactured by Toyo Styrene Co., Ltd.), a blend of a styrene-methacrylic acid copolymer and MBS resin (trans-type butadiene block-containing product) (product name "AMM11", manufactured by PSJ Co., Ltd.), and a cis-type styrene-butadiene block copolymer resin (product name "H8117", manufactured by PSJ Co., Ltd.) were used in a mass ratio of 80:11:9 (T080:AMM11:H8117). The same procedure as in Example 1 was repeated except that the extrusion conditions were changed as shown in Table 1 to obtain a raw sheet of polystyrene-based resin foam sheet (4). In order to replace the foaming gas, the original roll of the obtained polystyrene-based resin laminated foam sheet (4) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene-based resin laminated foam sheet (4) was laminated with CPS 20 μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25 μm (Santox KT) and CPS 20 μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45 μm plain" to produce the polystyrene-based resin laminated foam sheet (4). The results are shown in Table 1.

[0125] [Example 5] A mixed resin of styrene-methacrylic acid copolymer resin (styrene monomer content = 92 mass%, methacrylic acid monomer content = 8 mass%) (product name "T080", manufactured by Toyo Styrene Co., Ltd.) and cis-type styrene-butadiene block copolymer resin (product name "H8117", manufactured by PSJ Co., Ltd.) mixed in a mass ratio of 80:20 (T080:H8117) was used as the base polymer of the first foam layer, and the extrusion conditions were changed as shown in Table 1. The same procedure as in Example 1 was performed to obtain a raw sheet of polystyrene-based resin foamed sheet (5). In order to replace the foaming gas, the original roll of the obtained polystyrene-based resin laminated foam sheet (5) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene-based resin laminated foam sheet (5) was laminated with CPS 20 μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25 μm (Santox KT) and CPS 20 μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45 μm plain" to produce the polystyrene-based resin laminated foam sheet (5). The results are shown in Table 1.

[0126] [Example 6] A mixed resin of styrene-methacrylic acid copolymer resin (styrene monomer content = 92 mass%, methacrylic acid monomer content = 8 mass%) (product name "G9001", manufactured by PSJ) and cis-styrene-butadiene block copolymer resin (product name "H8117", manufactured by PSJ) in a mass ratio of 80:20 (T080:H8117) was used as the base polymer of the first foam layer, and the extrusion conditions were changed as shown in Table 1. The same procedure as in Example 1 was performed to obtain a raw sheet of polystyrene-based resin foamed sheet (6). In order to replace the foaming gas, the original roll of the obtained polystyrene-based resin laminated foam sheet (6) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene-based resin laminated foam sheet (6) was laminated with CPS 20 μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25 μm (Santox KT) and CPS 20 μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45 μm plain" to produce the polystyrene-based resin laminated foam sheet (6). The results are shown in Table 1.

[0127] [Comparative Example 1] A master batch containing talc (cell bubble regulator) (product name "DSM1401M") was blended in an amount of 0.2 parts by mass per 100 parts by mass of the mixed resin used as the base polymer of the first foam layer, and the extrusion conditions were changed as shown in Table 1. The same procedure as in Example 1 was carried out to obtain a raw sheet of polystyrene-based resin foamed sheet (C1). In order to replace the foaming gas, the original roll of the obtained polystyrene-based resin laminated foam sheet (C1) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene-based resin laminated foam sheet (C1) was laminated with CPS 20μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25μm (Santox KT) and CPS 20μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45μm plain" to produce the polystyrene-based resin laminated foam sheet (C1). The results are shown in Table 1.

[0128] [Comparative Example 2] A mixed resin of styrene-methacrylic acid copolymer resin (styrene monomer content = 92 mass%, methacrylic acid monomer content = 8 mass%) (product name "T080", manufactured by Toyo Styrene Co., Ltd.) and cis-type styrene-butadiene block copolymer resin (product name "H8117", manufactured by PSJ Co., Ltd.) mixed in a mass ratio of 80:20 (T080:H8117) was used as the base polymer of the first foam layer. The master batch was blended in a ratio of 1.0 part by mass per 100 parts by mass of the mixed resin, and the extrusion conditions were changed as shown in Table 1. The same procedure as in Example 1 was repeated to obtain a raw sheet of polystyrene-based resin foamed sheet (C2). In order to replace the foaming gas, the original roll of the obtained polystyrene resin laminated foam sheet (C2) was stored for 14 days after production. The second foam layer of the original roll of this polystyrene resin laminated foam sheet (C2) was laminated with CPS 20μm (Oishi Sangyo SPH), and the first foam layer was laminated with CPP 25μm (Santox KT) and CPS 20μm (Oishi Sangyo SPH) by dry lamination with a film "CPP / PS 45μm plain" to produce polystyrene resin laminated foam sheet (C2). The results are shown in Table 1.

[0129] [Table 1] [Industrial Applicability]

[0130] The polystyrene-based resin laminated foam sheet according to the embodiment of the present invention can be suitably used as a material for containers for instant cup noodles, etc. The polystyrene-based resin laminated foam container according to the embodiment of the present invention can be suitably used as a container for instant cup noodles, etc. [Explanation of symbols]

[0131] 100 Polystyrene resin laminated foam sheet 10 Polystyrene resin foam sheet (A) 11 First polystyrene resin foam layer 12 Second polystyrene resin foam layer 30 Non-foaming film 30a Surface of non-foamed film 30 40 Non-foaming film 40a Surface of non-foamed film 40 1000 Polystyrene resin laminated foam container 200 Inside the container 300 Outside the container

Claims

1. A laminated polystyrene resin foam sheet comprising a polystyrene resin foam sheet (A), The polystyrene-based resin foam sheet (A) includes a laminate of a first polystyrene-based resin foam layer having a glass transition temperature of 110° C. or higher and a second polystyrene-based resin foam layer having a glass transition temperature lower than that of the first polystyrene-based resin foam layer, the average surface roughness of the surface roughness Ra1(MD) in the MD direction and the surface roughness Ra1(TD) in the TD direction of the first polystyrene-based resin foamed layer is R1 (=(Ra1(MD)+Ra1(TD)) / 2), R1 is 3.0 μm to 8.0 μm, the average surface roughness of the surface roughness Ra2(MD) in the MD direction and the surface roughness Ra2(TD) in the TD direction of the second polystyrene-based resin foamed layer is R2 (=(Ra2(MD)+Ra2(TD)) / 2), R2 is 1.8 μm to 5.0 μm, and (R1 / R2) is 1.1 to 3.0, the apparent density of the first polystyrene-based resin foam layer is 0.01 g / cm 3 to 0.15 g / cm 3 ; the apparent density of the second polystyrene-based resin foam layer is 0.01 g / cm 3 to 0.15 g / cm 3 ; Polystyrene resin laminated foam sheet.

2. Apparent density 0.05 g / cm 3 ~0.16g / cm 3 The laminated polystyrene resin foam sheet according to claim 1,

3. 3. The polystyrene-based resin laminate foam sheet according to claim 1, wherein the first polystyrene-based resin foam layer is a heat-resistant polystyrene-based resin foam layer, and the second polystyrene-based resin foam layer is a general-purpose polystyrene-based resin foam layer.

4. A polystyrene-based resin laminate foam container, comprising the polystyrene-based resin laminate foam sheet according to any one of claims 1 to 3 molded into a container shape.

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