Molding die, and method for producing extrusion-foaming molded body using the same

Abstract

To provide a molding die capable of molding an extrusion-foaming molded body with a small density variation in a thickness direction and a small strength anisotropy, and a method for producing an extrusion-foaming molded body using the same.SOLUTION: A molding die 10 for molding an extrusion-foaming body comprises an upper mold member 10a and a lower mold member 10b, which are disposed for facing each other. Each of the upper mold member 10a and the lower mold member 10b includes a plurality of rolls 11 and a gap filling member 12 disposed in at least one of the gaps between the plurality of the rolls 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a molding die and a method for producing an extruded foam using the same. [Background technology]

[0002] Taking advantage of their properties such as light weight, high thermal insulation performance, and high strength, extruded foams are widely used in fields such as thermal insulation materials for building materials, flooring materials and cushioning materials, and interior and exterior materials for automobiles. In particular, extruded styrene resin foams have good thermal insulation properties and are therefore used as thermal insulation materials for houses and buildings. Extruded styrene resin foams are continuously produced, for example, by melt-kneading a styrene resin and a blowing agent in an extruder, optionally cooling the resulting composition, and extruding it into a low-pressure region through a die lip (e.g., a slit in a die).

[0003] For example, Patent Document 1 discloses a method in which a composition containing a styrene-based resin and a foaming agent is extruded into a low-pressure region, molded in a mold, and then molded using a roll. The mold used is a molding die equipped with a pair of upper and lower flat plate-shaped mold members. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 7-17022 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the technique described in Patent Document 1 may result in a large variation in density in the thickness direction of the resulting extruded styrene resin foam. Furthermore, the technique described in Patent Document 1 may result in a large difference between the planar compressive strength (compressive strength in the thickness direction) and the compressive strength in other directions of the resulting extruded styrene resin foam. Hereinafter, the property of a large difference between the planar compressive strength and the compressive strength in other directions may be referred to as "strength anisotropy."

[0006] It may be difficult to apply a styrene-based resin extrusion foam molded product having a large variation in density in the thickness direction or a styrene-based resin extrusion foam molded product having a large strength anisotropy to a thermal insulating material.

[0007] In view of the above, an object of the present invention is to provide a molding die capable of molding an extruded foam having small density variation in the thickness direction and small strength anisotropy, and a method for producing an extruded foam using the same. [Means for solving the problem]

[0008] <Aspects of the present invention> The present invention includes the following aspects.

[0009] [1] A molding die for molding an extruded foam obtained by extruding a resin composition containing a resin and a foaming agent from a high-pressure region to a low-pressure region through a die lip having a rectangular opening, A pair of mold members are disposed opposite each other, The mold member includes a plurality of rolls and a gap filling member disposed in at least one gap between the plurality of rolls.

[0010] [2] The mold according to [1] above, wherein the flow path side ends of the plurality of rolls are arranged on the same imaginary plane.

[0011] [3] The molding die according to [1] or [2], wherein the gap filling member is arranged upstream of the center of the molding member in the extrusion direction.

[0012] [4] The molding die according to any one of the above [1] to [3], wherein at least one of the plurality of rolls is a non-driven roll.

[0013] [5] The molding die according to any one of [1] to [4] above, wherein the flow channel side end of the gap filling member is substantially flat and / or curved.

[0014] [6] The molding die according to [2], wherein the flow path side end of the gap filling member is substantially planar and substantially parallel to the imaginary plane.

[0015] [7] The molding die according to any one of [1] to [6] above, wherein the flow channel side end of the roll protrudes further toward the flow channel than the flow channel side end of the gap filling member.

[0016] [8] The mold described in [7] above, wherein the protruding height of the flow path side end of the roll when the flow path side end of the gap filling member is used as a reference is 1% or more and 15% or less of the roll diameter of the roll closest to the gap filling member.

[0017] [9] The flow path side end of the roll protrudes toward the flow path further than the flow path side end of the gap filling member, The forming mold according to [2], wherein the distance between the flow path side end of the gap filling member and the imaginary plane is 1% to 15% of the roll diameter of the roll closest to the gap filling member.

[0018]

[10] A step Sa of extruding a thermoplastic resin composition containing a thermoplastic resin and a foaming agent from a high-pressure region to a low-pressure region through a die lip having a rectangular opening to obtain an extruded foam; and a step Sb of molding the extruded foam obtained in the step Sa using a molding die. A method for producing an extruded foam, wherein the mold is the mold according to any one of the above [1] to [9].

[0019]

[11] The method for producing an extruded foam according to

[10] above, further comprising, after step Sb, step Sc of molding the extruded foam in a roll molding machine having a drive roll. [Effects of the Invention]

[0020] According to the present invention, it is possible to provide a molding die capable of molding extruded foams with small density variation in the thickness direction and small strength anisotropy, and a method for producing extruded foams using the same. [Brief explanation of the drawings]

[0021] [Figure 1] FIG. 1 is a cross-sectional view showing an example of a molding die according to the present invention. [Figure 2] 1 is a schematic diagram illustrating an example of a method for producing an extruded foam according to the present invention. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0022] Preferred embodiments of the present invention will be described in detail below, but the present invention is not limited thereto. In addition, all academic and patent documents described in this specification are incorporated herein by reference.

[0023] First, the terms used in this specification will be explained. "Flow path" refers to the flow path (conveyance path) of the extruded foam when it is molded. "Driven roll" refers to a roll that rotates by rotating the roll shaft. "Non-driven roll" refers to a roll that rotates by friction with the extruded foam, without rotating the roll shaft. "Spacing" refers to the shortest distance between the ends. "Extrusion direction" refers to the extrusion direction of the extruded foam. "Upstream side" refers to the die lip side of the mold member in the extrusion direction.

[0024] Hereinafter, the compound and its derivatives may be collectively referred to by adding "based" after the compound name. Furthermore, when the compound name is followed by "based" to represent the name of a polymer, unless otherwise specified, it means that the repeating unit of the polymer is derived from the compound or its derivative. Furthermore, acrylic and methacrylic may be collectively referred to as "(meth)acrylic." Furthermore, acrylonitrile and methacrylonitrile may be collectively referred to as "(meth)acrylonitrile."

[0025] Unless otherwise specified, the components, functional groups, etc. exemplified in this specification may be used alone or in combination of two or more kinds.

[0026] The drawings referred to in the following description mainly show each component in a schematic manner for ease of understanding, and the size, number, shape, etc. of each component shown may differ from the actual size, number, shape, etc. of each component due to the convenience of creating the drawings. Furthermore, for convenience of explanation, in drawings described later, the same components as those in previously described drawings may be assigned the same reference numerals, and their explanation may be omitted.

[0027] <First embodiment: molding die> The molding die according to the first embodiment of the present invention is a molding die for molding an extruded foam obtained by extruding a resin composition containing a resin and a foaming agent from a high-pressure region to a low-pressure region through a die lip having a rectangular opening. The molding die according to the first embodiment includes a pair of mold members arranged opposite each other. The mold members include multiple rolls and a gap filling member arranged in at least one of the gaps between the multiple rolls.

[0028] The molding die according to the first embodiment can mold extruded foams with small density variations in the thickness direction and small strength anisotropy. The reason for this is presumed to be as follows.

[0029] Typically, when a pair of flat mold members is used as a molding die for an extruded foam, the extruded foam tends to expand excessively toward the flat mold members as it passes through the flat mold members due to poor sliding properties of the extruded foam relative to the flat mold members. Meanwhile, the flat mold members tend to suppress the expansion of the surface layer of the extruded foam in the thickness direction. Therefore, when flat mold members are used, the density of the surface layer of the extruded foam tends to be excessively high compared to the density of the middle layer (density near the center) of the extruded foam, resulting in a large density variation in the thickness direction of the extruded foam. Furthermore, when the extruded foam expands excessively toward the flat mold members, the shape of the cells in the interior (regions other than the surface layer) of the extruded foam becomes elongated in the thickness direction. This increases the compressive strength in the thickness direction (planar compressive strength), but decreases the compressive strength in other directions, resulting in increased strength anisotropy. In contrast, the molding die according to the first embodiment has a pair of mold members each equipped with multiple rolls, thereby enhancing the sliding properties of the extruded foam relative to the mold members. Therefore, by using the molding die according to the first embodiment, it is possible to suppress excessive expansion of the extruded foam while mitigating the suppression of expansion in the surface layer of the extruded foam. Furthermore, the molding die according to the first embodiment includes a gap filling member disposed in at least one of the gaps formed between adjacent rolls, thereby suppressing excessive expansion of the extruded foam between the rolls. Therefore, the molding die according to the first embodiment can uniformly suppress excessive expansion of the extruded foam while mitigating the suppression of expansion in the surface layer of the extruded foam, thereby enabling the molding of extruded foams with small density variation in the thickness direction and small strength anisotropy.

[0030] The mold according to the first embodiment is suitable for producing extruded foam molded articles. A method for producing extruded foam molded articles using the mold according to the first embodiment will be described later.

[0031] An example of the molding die according to the first embodiment will be described below with reference to the drawings as appropriate. Figure 1 is a cross-sectional view showing an example of the molding die according to the first embodiment.

[0032] The molding die 10 shown in FIG. 1 includes a pair of mold members (upper mold member 10a and lower mold member 10b). The upper mold member 10a and the lower mold member 10b are arranged facing each other. Each of the upper mold member 10a and the lower mold member 10b includes a plurality of rolls 11 (four rolls 11 in FIG. 1) and gap filling members 12 arranged in the gaps between the rolls 11 (gaps formed between adjacent rolls 11). Each of the upper mold member 10a and the lower mold member 10b further includes a frame-shaped fixing member 13 for fixing the widthwise ends of the rolls 11 and the gap filling members 12, and a cover 14 for covering the rolls 11. The length of each of the upper mold member 10a and the lower mold member 10b in the extrusion direction (the length in the left-right direction in FIG. 1) can be appropriately set depending on the size of the extruded foam, but is preferably 100 mm or more and 1000 mm or less, and more preferably 100 mm or more and 700 mm or less. Unless otherwise specified, the following will describe the contents applicable to the upper mold member 10a and the lower mold member 10b.

[0033] As shown in Fig. 1, it is preferable that the surface 13a of the fixing member 13 on the flow path FP side at one end on the upstream side (the left end in Fig. 1) is a curved surface. If the surface 13a of one end of the fixing member 13 on the flow path FP side is a curved surface, it becomes easier to adjust (pre-adjust) the thickness of the extruded foam, which will be described later. The curved surface may be provided on a member separate from the fixing member 13. The material of the curved surface and the fixing member 13 is not particularly limited, and examples thereof include metal, ceramic, and resin.

[0034] The multiple rolls 11 may be driven rolls or non-driven rolls, or a combination of driven rolls and non-driven rolls may be used. Preferably, at least one of the multiple rolls 11 is a non-driven roll, and more preferably, all of the multiple rolls 11 are non-driven rolls. When at least one of the multiple rolls 11 is a non-driven roll, it becomes easier to adjust the roll rotation speed between the roll 11 and forming rolls 310 and 320 (see FIG. 2) of the roll forming machine 300, which will be described later. When all of the multiple rolls 11 are non-driven rolls, it becomes easier to adjust the roll rotation speed between the roll 11 and forming rolls 310 and 320 of the roll forming machine 300.

[0035] The number of rolls 11 in each of the upper mold member 10a and the lower mold member 10b is not particularly limited as long as it is at least 2. From the viewpoint of reducing manufacturing costs, the number of rolls 11 in each of the upper mold member 10a and the lower mold member 10b is preferably 10 or less.

[0036] The material of the roll 11 is not particularly limited, and examples thereof include metal, ceramic, and resin. From the viewpoint of improving the strength of the roll 11, the material of the roll 11 is preferably metal or ceramic, more preferably metal, and even more preferably stainless steel. When the roll 11 is made of metal or ceramic, the surface of the roll 11 is preferably coated with a fluororesin or the like to improve the sliding property of the extruded foam relative to the roll 11. The roll diameter of the roll 11 can be appropriately set depending on the size of the extruded foam to be obtained, and is, for example, in the range of 5 mm to 200 mm, and preferably in the range of 10 mm to 100 mm. The width of the roll 11 can also be appropriately set depending on the size of the extruded foam to be obtained, and is, for example, in the range of 100 mm to 1500 mm, and preferably in the range of 200 mm to 1300 mm. From the viewpoint of improving the sliding property of the extruded foam, it is preferable that the end portions 11a of the multiple rolls 11 on the flow path FP side are arranged on the same imaginary plane VP.

[0037] The position of the roll 11 in the extrusion direction of the upper mold member 10a and the lower mold member 10b is not particularly limited. From the viewpoint of increasing the slipperiness of the extruded foam and promoting the expansion of the surface layer portion of the extruded foam in the extrusion direction, it is preferable that the roll 11 with which the extruded foam first comes into contact (the roll 11 located at the leftmost position in FIG. 1 ) is located upstream of the center of each of the upper mold member 10a and the lower mold member 10b in the extrusion direction. The multiple rolls 11 may be arranged so that the gaps La between the rolls 11 are uniform, or may be arranged so that the gaps La vary. From the viewpoint of suppressing the expansion of the extruded foam into the gaps La and increasing the slipperiness of the extruded foam and promoting the expansion of the surface layer portion of the extruded foam in the extrusion direction, the gap La is preferably 0.5 mm or more and 10.0 mm or less, and more preferably 0.5 mm or more and 5.0 mm or less.

[0038] The gap filling members 12 are disposed in at least one of the gaps formed between adjacent rolls 11. To further suppress expansion of the extruded foam into the gaps La, the gap filling members 12 are preferably disposed upstream of the center in the extrusion direction of each of the upper mold member 10a and the lower mold member 10b, and more preferably disposed in all of the gaps formed between adjacent rolls 11. The maximum number of gap filling members 12 in each of the upper mold member 10a and the lower mold member 10b is "the number of rolls 11 - 1".

[0039] The shape of the end 12a of the gap filling member 12 on the flow path FP side is not particularly limited, but examples include a substantially flat, curved, uneven, wavy, etc. In order to reduce frictional resistance between the extruded foam and the gap filling member 12, the end 12a of the gap filling member 12 on the flow path FP side is preferably substantially flat or curved, and more preferably substantially flat. The end 12a of the gap filling member 12 on the flow path FP side may all have the same shape or different shapes. Hereinafter, when the flow path side end of the gap filling member is substantially flat, the flow path side end of the gap filling member may be referred to as the "flow path side end face of the gap filling member."

[0040] To improve the slipperiness of the extruded foam, it is preferable that the flow path FP-side ends 11a of the rolls 11 protrude further toward the flow path FP than the flow path FP-side ends 12a of the gap filling members 12. Specifically, it is preferable that the flow path FP-side end 11a of each roll 11 protrude further toward the flow path FP than the flow path FP-side end 12a of the adjacent gap filling member 12. In this case, the protrusion height H of the flow path FP-side end 11a of each roll 11, when taken as the reference point for the flow path FP-side end 12a of the gap filling member 12, is preferably 1% to 15% of the roll diameter of the roll 11 adjacent to the gap filling member 12, more preferably 1% to 10%, and even more preferably 1% to 5%. Here, when the roll diameters of two adjacent rolls 11 are different, the larger roll diameter is used as the reference point.

[0041] 1, in a configuration in which the flow path FP-side end 12a of the gap filling member 12 is substantially planar and the flow path FP-side end 11a of the multiple rolls 11 are arranged on the same imaginary plane VP, it is preferable that the flow path FP-side end 12a of the gap filling member 12 be substantially parallel to the imaginary plane VP from the viewpoint of uniforming the foaming state of the extruded foam and uniforming the slipperiness of the extruded foam in the vicinity of the gap filling member 12. At least one of the flow path FP-side end 12a of the gap filling member 12 may be arranged substantially parallel to the imaginary plane VP, but in order to more uniformly uniform the foaming state of the extruded foam in the vicinity of the gap filling member 12 and uniforming the slipperiness of the extruded foam, it is preferable that all of the flow path FP-side end 12a of the gap filling member 12 be arranged substantially parallel to the imaginary plane VP.

[0042] 1, in a configuration in which the end portions 11a of the rolls 11 on the flow path FP side protrude further toward the flow path FP side than the end portions 12a of the gap filling members 12 on the flow path FP side and are arranged on the same imaginary plane VP, the distance Lb between the end portions 12a of the gap filling members 12 on the flow path FP side and the imaginary plane VP is preferably 1% to 15% of the roll diameter of the roll 11 closest to the gap filling member 12, more preferably 1% to 10%, and even more preferably 1% to 5%. Here, when the roll diameters of two adjacent rolls 11 are different, the larger roll diameter is used as the reference.

[0043] The overall shape of the gap filling member 12 is not particularly limited as long as it can fill the gap formed between adjacent rolls 11, and examples thereof include a cylindrical shape, a flat plate shape, a triangular prism shape, and a prismatic shape other than a triangular prism. In order to increase the strength of the gap filling member 12, the overall shape of the gap filling member 12 is preferably a triangular prism shape as shown in FIG. 1.

[0044] The material of the gap filling member 12 is not particularly limited, and examples thereof include metal, ceramic, and resin. From the viewpoint of improving the strength of the gap filling member 12, the material of the gap filling member 12 is preferably metal or ceramic, more preferably metal, and even more preferably stainless steel. When the material of the gap filling member 12 is metal or ceramic, the surface of the gap filling member 12 on the flow path FP side is preferably coated with a fluororesin or the like to improve the sliding property of the extruded foam relative to the gap filling member 12. The length of the gap filling member 12 (the length in the extrusion direction in the extrusion step described below) can be appropriately set depending on the size of the extruded foam to be obtained, and is, for example, in the range of 5 mm to 200 mm, and preferably in the range of 10 mm to 100 mm. The width of the gap filling member 12 can also be appropriately set depending on the size of the extruded foam to be obtained, and is, for example, in the range of 100 mm to 1500 mm, and preferably in the range of 200 mm to 1300 mm. In order to obtain an extruded foam having smaller density variation in the thickness direction and smaller strength anisotropy, the distance Lc between the gap filling member 12 and the roll 11 is preferably 0.5 mm or more and 5.0 mm or less, more preferably 0.5 mm or more and 3.0 mm or less, and even more preferably 0.5 mm or more and 1.5 mm or less.

[0045] In the first embodiment, in order to obtain a molding die that can easily produce extruded foams with small density variation in the thickness direction and small strength anisotropy, each of a pair of mold members of the molding die according to the first embodiment preferably satisfies the following condition 1, more preferably satisfies the following condition 2, and even more preferably satisfies the following condition 3 or 4: Condition 1: At least one of the rolls is a non-driven roll, and the end of the gap filling member on the flow path side is substantially flat. Condition 2: The above condition 1 is satisfied, and the flow path side ends of the multiple rolls are arranged on the same imaginary plane. Condition 3: The above condition 2 is satisfied, and the flow path side end of the gap filling member is approximately parallel to the above virtual plane, and the flow path side ends of the multiple rolls protrude further toward the flow path than the flow path side end of the gap filling member. Condition 4: The above condition 2 is satisfied, and the distance between the flow path side end of the gap filling member and the above imaginary plane is 1% to 15% of the roll diameter of the roll closest to the gap filling member.

[0046] <Second embodiment: Method for producing extruded foam> Next, a description will be given of a method for producing an extruded foam according to a second embodiment of the present invention. In the following description, the description of the same content as in the first embodiment may be omitted.

[0047] The method for producing an extruded foam according to the second embodiment includes steps Sa and Sb. In step Sa, an extruded foam is obtained by extruding a thermoplastic resin composition containing a thermoplastic resin and a blowing agent from a high-pressure region to a low-pressure region through a die lip having a rectangular opening. In step Sb, the extruded foam obtained in step Sa is molded using the molding die according to the first embodiment. Because the production method according to the second embodiment uses the molding die according to the first embodiment, it is possible to mold extruded foams with small density variation in the thickness direction and small strength anisotropy.

[0048] The method for producing an extruded foam according to the second embodiment may include steps (other steps) other than step Sa and step Sb, such as step Sc, which follows step Sb and involves molding the extruded foam using a roll molding machine having a drive roll, a resin composition preparation step, and a melt-kneading step.

[0049] Hereinafter, "Step Sa" may be referred to as "extrusion step", "Step Sb" may be referred to as "first shaping step", and "Step Sc" may be referred to as "second shaping step".

[0050] An example of the method for producing an extruded foam molded product according to the second embodiment will be described below with reference to the drawings as appropriate. Figure 2 is a schematic diagram for explaining the example of the method for producing an extruded foam molded product according to the second embodiment.

[0051] 2, in the second embodiment, a thermoplastic resin composition containing a thermoplastic resin and a foaming agent is extruded from a high-pressure region to a low-pressure region through a die lip 110 of an extrusion device 100 to obtain an extruded foam 200 (extrusion step). At this time, the pressure inside the extrusion device 100 is made higher than the pressure in the region where the thermoplastic resin composition is extruded (e.g., atmospheric pressure), and the thermoplastic resin composition is extruded from the high-pressure region of the extrusion device 100 to the low-pressure region, causing the thermoplastic resin composition to foam and become the extruded foam 200.

[0052] The die lip 110 has a rectangular opening (not shown). The longitudinal length of the opening of the die lip 110 is, for example, 50 mm or more and 600 mm or less, and the lateral length of the opening of the die lip 110 is, for example, 0.5 mm or more and 7.0 mm or less.

[0053] 2, after the extruded foam 200 is obtained, the thickness and width of the extruded foam 200 are roughly adjusted (pre-adjusted) using the molding die 10 (upper mold member 10a and lower mold member 10b) placed in close contact with or close to the die lip 110. More specifically, the thickness and width of the extruded foam 200 are roughly adjusted by the extruded foam 200 passing through the flow path FP between the upper mold member 10a and the lower mold member 10b (first molding step).

[0054] The thickness and width of the extruded foam 200 that has passed through the molding die 10 are adjusted (post-adjustment) by a roll forming machine 300. More specifically, the thickness and width of the extruded foam 200 that has passed through the molding die 10 are adjusted by passing between forming rolls 310 and 320 of the roll forming machine 300 that is installed downstream of the molding die 10 (second forming step). The forming rolls 310 and 320 are both drive rolls. The roll forming machine 300 is equipped with at least one pair of drive rolls. The thickness and width of the extruded foam 200 are adjusted by the second forming step, and an extruded foam 400 is obtained. Note that, although a roll forming machine is used in the example shown in FIG. 2, a roll forming machine need not be used in the present invention.

[0055] Next, each step included in an example of a manufacturing method according to the second embodiment will be described.

[0056] [Resin composition preparation process] In the resin composition preparation step, the materials for the extruded foam are blended to prepare a thermoplastic resin composition. The thermoplastic resin composition contains at least a thermoplastic resin and a blowing agent. The blowing agent may be injected into a thermoplastic resin composition containing materials other than the blowing agent in a subsequent melt-kneading step. The thermoplastic resin is not particularly limited, but examples include polystyrene-based resins, polyolefin-based resins, and polyester-based resins. The thermoplastic resins may be used alone or in combination of two or more. In order to improve strength and heat insulation, polystyrene-based resins (styrene-based resins) are preferred as the thermoplastic resin. An example of a material constituting the styrene-based resin composition will be described below.

[0057] (styrene resin) Examples of styrene-based resins include homopolymers of styrene-based monomers, copolymers of two or more styrene-based monomers, and copolymers of styrene-based monomers with other monomers. The content of structural units derived from styrene-based monomers in the styrene-based resin is preferably 70% by weight or more, more preferably 80% by weight or more, and even more preferably 90% by weight or more. Examples of copolymers include random copolymers, block copolymers, and graft copolymers.

[0058] Examples of styrene-based monomers include styrene, methylstyrene, dimethylstyrene, ethylstyrene, diethylstyrene, isopropylstyrene, bromostyrene, dibromostyrene, tribromostyrene, chlorostyrene, dichlorostyrene, trichlorostyrene, vinyltoluene, and vinylxylene. Other monomers include polyfunctional vinyl compounds such as divinylbenzene; (meth)acrylic acid; (meth)acrylic acid ester compounds such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, and butyl methacrylate; vinyl cyanide compounds such as (meth)acrylonitrile; diene compounds such as butadiene; unsaturated carboxylic acid anhydrides such as maleic anhydride and itaconic anhydride; and N-alkyl-substituted maleimide compounds such as N-methylmaleimide, N-butylmaleimide, N-cyclohexylmaleimide, and N-phenylmaleimide. These may be used alone or in combination of two or more.

[0059] The styrene resin may be a blend of a homopolymer or copolymer of the styrene monomer and a homopolymer or copolymer of the other monomer. For example, the styrene resin may be blended with rubber-reinforced polystyrene (e.g., diene-based rubber-reinforced polystyrene, acrylic-based rubber-reinforced polystyrene, etc.), polyphenylene ether-based resin, etc.

[0060] As the styrene-based resin, polystyrene (a homopolymer of styrene), a styrene-acrylonitrile copolymer, a styrene-(meth)acrylic acid copolymer, a styrene-maleic anhydride copolymer, and a styrene-diene compound copolymer (for example, a styrene-butadiene copolymer) are preferred from the viewpoints of being relatively inexpensive and suitable for extrusion foam molding, etc. From the viewpoint of cost, polystyrene is particularly preferred.

[0061] The styrene-based resin may also have a branched structure for the purpose of adjusting the melt flow rate, melt viscosity during molding, melt tension, etc. Hereinafter, melt flow rate will be referred to as MFR. The MFR of the styrene-based resin is preferably 40 g / 10 min or less, and more preferably 1 g / 10 min or more and 30 g / 10 min or less. If the MFR of the styrene-based resin is 40 g / 10 min or less, it is easy to uniformly disperse the blowing agent in the styrene-based resin in the extrusion device, allowing stable extrusion and foam molding, resulting in improved production stability. In this specification, the MFR of the styrene-based resin is a value measured in accordance with the measurement method specified in JIS K7210 under conditions of a temperature of 200°C and a load of 5 kg.

[0062] (foaming agent) Examples of blowing agents include water, dimethyl ether, saturated hydrocarbons having 3 to 5 carbon atoms, alcohols having 1 to 4 carbon atoms, inorganic gases (more specifically, carbon dioxide, nitrogen, etc.), and organic fluorine compounds with low global warming potential (more specifically, hydrofluoroolefins, hydrochlorofluoroolefins, etc.). These may be used alone or in combination of two or more.

[0063] Examples of saturated hydrocarbons having 3 to 5 carbon atoms include propane, normal butane, isobutane, normal pentane, isopentane, and neopentane. From the viewpoint of foamability, propane, normal butane, isobutane, and mixtures thereof are preferred. Furthermore, from the viewpoint of the heat insulating performance of extruded foams, normal butane, isobutane, and mixtures thereof are preferred.

[0064] Examples of alcohols having 1 to 4 carbon atoms include ethanol, methanol, propyl alcohol, isopropyl alcohol, butyl alcohol, isobutyl alcohol, and tert-butyl alcohol.

[0065] The amount of the blowing agent used (when multiple blowing agents are used, the total amount used) is preferably 1 part by weight to 20 parts by weight, more preferably 5 parts by weight to 10 parts by weight, per 100 parts by weight of the styrene-based resin. When the amount of the blowing agent used is 1 part by weight to 20 parts by weight, the foaming power of the styrene-based resin composition is ensured, and extruded foam molded articles having the desired thickness can be stably obtained.

[0066] (Flame retardant) As the flame retardant, a brominated flame retardant is preferably used. Specific examples of the brominated flame retardant include brominated bisphenol compounds such as tetrabromobisphenol A-bis(2,3-dibromo-2-methylpropyl)ether and tetrabromobisphenol A-bis(2,3-dibromopropyl)ether; bromine-containing polymers such as brominated styrene-butadiene block copolymers, brominated styrene-butadiene random copolymers, and brominated styrene-butadiene graft copolymers; tetrabromocyclooctane; hexabromocyclododecane; tris(2,3-dibromopropyl)isocyanurate; and the like. These may be used alone or in combination of two or more.

[0067] From the viewpoint of economic efficiency and its influence on other required physical properties, the amount of the flame retardant used is preferably 0.5 parts by weight or more and 10 parts by weight or less, and more preferably 0.5 parts by weight or more and 7 parts by weight or less, per 100 parts by weight of the styrene-based resin.

[0068] The styrene-based resin composition may contain, as other additives, water-absorbing substances (bentonite, silica, etc.), cell size adjusters (talc, etc.), lubricants (sodium stearate, calcium stearate, etc.), radical generators (2,3-dimethyl-2,3-diphenylbutane, poly-1,4-diisopropylbenzene, etc.), flame retardant aids (triphenylphosphine oxide, etc.), stabilizers (epoxy compounds, polyhydric alcohol ester compounds, phenolic stabilizers, phosphite stabilizers, etc.), surfactants, flame retardant adjusters (iron oxide, iron complexes, diphenylalkanes, diketones, etc.), processing aids (fatty acid metal salts, fatty acid amides, fatty acid esters, liquid paraffin, olefin-based waxes, etc.), antistatic agents, colorants (pigments, dyes, etc.), radiative heat transfer inhibitors, ultraviolet absorbers, fluorescent brighteners, plasticizers, fillers, etc.

[0069] [Melting and kneading process] In the melt-kneading step, the thermoplastic resin composition is supplied to an extruder, and the thermoplastic resin composition is melt-kneaded in the extruder. Examples of the extruder include an extruder equipped with an extruder using a screw. Examples of the extruder using a screw include a single-screw extruder and a twin-screw extruder. The L / D (effective length of the screw / diameter of the screw) of the extruder is, for example, 10 or more and 50 or less. When a twin-screw extruder is used, the rotation directions of the screws may be the same or opposite.

[0070] The extrusion device may also include a first extruder that melt-kneads a foaming agent and a material other than the foaming agent, and a second extruder that further melt-kneads and cools the melt-kneaded mixture obtained in the first extruder. When the extrusion device includes the second extruder, the foaming agent may be supplied to the second extruder. The types of the first extruder and the second extruder may be the same or different. The extrusion device may also include a cooler downstream of the extruder for adjusting the temperature to a temperature suitable for foaming the thermoplastic resin composition. A die lip is provided at the most downstream end of the extrusion device as an opening through which the thermoplastic resin composition is extruded.

[0071] The temperature at which the thermoplastic resin composition is melt-kneaded is, for example, 150° C. or higher and 250° C. or lower. When a cooler is used, the melt-kneaded product is preferably cooled in the cooler to a temperature of, for example, 100° C. or higher and 150° C. or lower.

[0072] [Extrusion process] In the extrusion step, a thermoplastic resin composition (e.g., the molten mixture obtained in the melt-kneading step) is extruded from a high-pressure region through a die lip into a low-pressure region (e.g., into the atmosphere) to foam the thermoplastic resin composition and obtain an extruded foam. The pressure (pressure in the high-pressure region) applied to the thermoplastic resin composition immediately before it is extruded through the die lip is, for example, 1.5 MPa or more and 15 MPa or less. Hereinafter, the pressure applied to the thermoplastic resin composition immediately before it is extruded through the die lip may be referred to as the "foaming pressure."

[0073] [First molding process and second molding process] In the first molding step, the thickness and width of the extruded foam are roughly adjusted (pre-adjusted) using the molding die according to the first embodiment. In the second molding step, the thickness and width of the extruded foam after the first molding step are post-adjusted by molding with a roll molding machine to obtain an extruded foam. The take-up speed of the roll molding machine depends on the linear velocity of the thermoplastic resin composition extruded from the die lip, but is preferably 1.0 m / min or more and 20.0 m / min or less to obtain an extruded foam with smaller density variation in the thickness direction and smaller strength anisotropy.

[0074] The production method according to the second embodiment may include, after the second molding step, a step of cutting the obtained extruded foam according to the intended use.

[0075] [Extruded foam obtained by the production method according to the second embodiment] Next, the extruded foam molded product obtained by the production method according to the second embodiment (hereinafter, may be referred to as "extruded foam molded product FM") will be described.

[0076] The extruded foam FM is produced by the production method according to the second embodiment, and therefore has small density variations in the thickness direction and small strength anisotropy.

[0077] In order to obtain an extruded foam molded product FM with a smaller density variation in the thickness direction, the difference between the surface layer density and the middle layer density of the extruded foam molded product FM should be 25.0 kg / m 3 It is preferable that the saturation is 23.0 kg / m or less. 3 The surface layer density and the middle layer density are measured by the same method as in the examples described below or a method equivalent thereto.

[0078] To obtain extruded foam molded products FM with smaller strength anisotropy, the strength anisotropy value of the extruded foam molded products FM is preferably 2.0 or less, and more preferably 1.9 or less. The strength anisotropy value is measured by the same method as in the examples described below or a method equivalent thereto.

[0079] The thickness of the extruded foam FM is not particularly limited and is selected appropriately depending on the application. For example, in the case of a heat insulating material used in applications such as building materials, the thickness of the extruded foam FM is preferably 10 mm or more, more preferably 20 mm or more, in order to impart preferable heat insulating properties, bending strength, and compressive strength. Furthermore, from the viewpoint of the processability of the extruded foam FM, the thickness of the extruded foam FM is preferably 150 mm or less, more preferably 100 mm or less.

[0080] In the case of extruded foam molded products, after foam molding to give them a shape, the surface layer (skin layer) that was in contact with the molding die may be removed by about 5 mm in the thickness direction to produce a finished product, but the thickness of the extruded foam molded product FM is the thickness of the extruded foam molded product before the skin layer is removed.

[0081] In order to obtain a lightweight extruded foam molded product FM that is excellent in heat insulation, bending strength, and compressive strength, the overall density of the extruded foam molded product FM is 15 kg / m 3 More than 70kg / m 3 It is preferable that the saturation is 20 kg / m or less.3 More than 60kg / m 3 The overall density is more preferably the following: The method for measuring the overall density is the same as or similar to the method described in the Examples below.

[0082] To obtain extruded foam molded products FM with excellent thermal insulation properties, bending strength, and compressive strength, the average cell diameter of the extruded foam molded products FM is preferably 0.05 mm or more and 1.00 mm or less, more preferably 0.10 mm or more and 1.00 mm or less, even more preferably 0.20 mm or more and 0.80 mm or less, and particularly preferably 0.20 mm or more and 0.60 mm or less. To obtain extruded foam molded products FM with high thermal insulation properties, the closed cell ratio of the extruded foam molded products FM is preferably 70% or more, more preferably 80% or more, and even more preferably 90% or more. The average cell diameter and closed cell ratio are measured according to the method described in WO 2015 / 170602. [Example]

[0083] Examples of the present invention will be described below, but the present invention is not limited to the following examples.

[0084] <Material preparation> The following materials were prepared as materials for producing extruded foam molded articles of Examples and Comparative Examples.

[0085] [Styrene-based resin] Styrene-based resin (PS Japan "680", MFR: 7.0g / 10min)

[0086] [Flame retardant] Brominated styrene-butadiene block copolymer (LANXESS "EMERALD INNOVATION 3000", bromine content: 65% by weight)

[0087] [Water-absorbing substance] Bentonite (BYK "Bentolite L") Silica (Evonik Degussa Japan "Carplex BS-304F")

[0088] [Radical generator] Poly-1,4-diisopropylbenzene (CUROX CC-P3 manufactured by United Initiators)

[0089] [Stabilizer] Bisphenol A diglycidyl ether (ADEKA "EP-13") Reaction mixture of dipentaerythritol and adipic acid (Ajinomoto Fine-Techno Co., Ltd. "Plenriser ST210") Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)] (Rianlon "RIANOX 1010FF") 3,9-bis(2,4-di-tert-butylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane (SONGNOX 6260FF manufactured by SONGWON) Orthocresol novolac epoxy resin (DIC "EPICLON N-680")

[0090] [Lubricant] Calcium stearate (Sakai Chemical Industry Co., Ltd. "SC-P")

[0091] [Bubble size adjuster] Talc (Hayashi Kasei "KHP-400")

[0092] [Foaming agent] Odorless butane (Iwatani Corporation, a mixture of isobutane and normal butane, weight ratio: isobutane / normal butane = 30 / 70) Dimethyl ether (manufactured by Iwatani Corporation) Water (tap water)

[0093] <Preparation of extruded foam> The methods for producing the extruded foams of Example 1 and Comparative Examples 1 and 2 will be described below.

[0094] [Example 1] (Resin composition preparation process) 100 parts by weight of styrene-based resin, 2.50 parts by weight of brominated styrene-butadiene block copolymer, 0.20 parts by weight of poly-1,4-diisopropylbenzene, 0.20 parts by weight of a reaction mixture of dipentaerythritol and adipic acid, 0.25 parts by weight of pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyhydrocinnamate)], and 3,9-bis(2,4-di-tert-butylphenoxy) A resin composition was prepared by dry-blending 0.0125 parts by weight of (hydroxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane, 0.125 parts by weight of orthocresol novolac epoxy resin, 0.15 parts by weight of bisphenol A diglycidyl ether, 0.10 parts by weight of talc, 0.20 parts by weight of calcium stearate, 0.40 parts by weight of bentonite, and 0.10 parts by weight of silica.

[0095] (Melting and kneading process) The resulting resin composition was fed into the first extruder of an extrusion apparatus connected in series in this order: a twin-screw extruder (first extruder) with a diameter of 40 mm and an L / D of 32; a single-screw extruder (second extruder) with a diameter of 90 mm and an L / D of 30; and a cooler. The resulting resin composition was fed into the first extruder so that the die lip discharge rate (amount extruded from the die lip) was 50 kg / h. The resin composition was then melt-kneaded in the first extruder while being heated at a temperature of 200°C to obtain a melt-kneaded product. Next, 3.50 parts by weight of odorless butane, 3.00 parts by weight of dimethyl ether, and 0.50 parts by weight of water per 100 parts by weight of styrene-based resin were injected into the melt-kneaded product near the center of the first extruder. The mixture was then kneaded in the second extruder connected to the first extruder, and subsequently cooled to 120°C in a cooler connected to the second extruder.

[0096] (Extrusion process) Next, the molten kneaded material (styrene-based resin composition) was extruded into the atmosphere at a foaming pressure of 2.5 MPa from a die lip having a rectangular opening (longitudinal length of opening: 150 mm, lateral length of opening: 1.0 mm) provided at the tip of the cooling machine, and foamed.

[0097] (First molding process and second molding process) The resulting extruded foam was then molded using a mold placed in close contact with the die lip (first molding step) and a roll molding machine placed downstream of the mold (second molding step) to obtain an extruded foam having a rectangular cross-sectional shape of 32 mm thick x 312 mm wide (the extruded foam of Example 1). The mold used included a pair of mold members (spacing between mold members: 28 mm, length of mold member in the extrusion direction: 150 mm). Each of the pair of mold members included three non-driven rolls (roll diameter: 38 mm, width: 497 mm, material: stainless steel, gap between rolls: 1.0 mm) and two gap filling members (shape: triangular prism, length in the extrusion direction: 25 mm, width: 497 mm, height from the flow path side end face to the top: 5 mm, material: stainless steel) positioned in the gap between the three rolls. In each pair of mold members, the flow path side ends of the three rolls were arranged on the same imaginary plane, and the gap between the rolls and the gap filling members was 1.0 mm. In addition, in each of the pair of molding members, the flow path side end face of the gap filling member was parallel to the above-mentioned imaginary plane, and the flow path side ends of the three rolls protruded 1.0 mm toward the flow path side from the flow path side end face of the gap filling member. That is, in each of the pair of molding members, the distance between the flow path side end face of the gap filling member and the above-mentioned imaginary plane was 1.0 mm. In addition, the roll forming machine had a gap between the upper and lower forming rolls (drive rolls) of 23 mm, and the take-up speed was set to 1.8 m / min.

[0098] [Comparative Example 1] An extruded foam molded article of Comparative Example 1 was obtained in the same manner as in Example 1, except that a pair of flat plate-like mold members (with a gap of 28 mm between the flat plate-like mold members) was used instead of the mold member equipped with rolls, and the take-up speed of the roll molding machine was set to 1.7 m / min. The flat plate-like mold member used in Comparative Example 1 was 150 mm long and 508 mm wide, and was made of carbon steel for mechanical structures. The flow path side end surface of the flat plate-like mold member used in Comparative Example 1 was coated with a fluororesin.

[0099] Comparative Example 2 An extruded foam molded product of Comparative Example 2 was obtained in the same manner as in Example 1, except that no gap filling member was used.

[0100] <Measurement method> The methods for measuring the density and compressive strength of extruded foams are described below. For both methods, the extruded foams were used after being left to stand for 16 hours or more in a standard atmosphere of JIS K 7100:1999, Class 3 (temperature 23±5°C, relative humidity 40-70%) to condition the extruded foams.

[0101] [density] (Total density) First, each extruded foam was cut at the center of its width to obtain a test piece with a length of 50 mm in the longitudinal direction (the extrusion direction in the extrusion process) and a length of 30 mm in the width direction. The weight of the test piece was then measured, and the test piece was submerged in a measuring cylinder containing water. The volume of the test piece was calculated from the rise in the liquid level in the measuring cylinder (submersion method). The overall density was then calculated from the weight and volume obtained.

[0102] (middle layer density) First, each extruded foam was cut at the center in the width direction to a length of 50 mm in the longitudinal direction (the extrusion direction in the extrusion process) and a length of 30 mm in the width direction. After that, the surface layers (5 mm-thick skin layers) on both sides of the extruded foam were removed so that 11 mm regions remained above and below the center in the thickness direction of the cut extruded foam, thereby obtaining test pieces. The weight of each test piece was then measured, and the volume of the test piece was determined by the above-mentioned water immersion method. The middle layer density was then calculated from the weight and volume obtained.

[0103] (Surface density) First, each extruded foam was cut at the center in the width direction so that the length in the longitudinal direction (the extrusion direction in the extrusion process) was 50 mm and the length in the width direction was 30 mm. After that, the skin layers (regions up to 5 mm from the surface) on both sides of the cut extruded foam were cut to obtain test pieces consisting of two skin layers. Next, the weights of the two test pieces were measured, and the volumes of the two test pieces were determined by the above-mentioned water immersion method. The surface layer density was then calculated from the obtained weights and volumes.

[0104] (difference between surface and mid-layer density) From the surface layer density and middle layer density obtained by the above procedure, the difference between the surface layer density and the middle layer density (surface layer density - middle layer density) was calculated and used as an index of density variation in the thickness direction. 3 The case where the density variation in the thickness direction is small is evaluated as follows: On the other hand, the difference between the surface layer density and the middle layer density is 25.0 kg / m 3 When the density variation in the thickness direction was greater than 100%, it was evaluated as "large variation in density in the thickness direction."

[0105] [Compression strength] (Plane compressive strength) First, each extruded foam was cut at its widthwise center to a length of 55 mm in the longitudinal direction (the extrusion direction during the extrusion process) and a length of 55 mm in the widthwise direction. The surface layers (6 mm thick skin layers) on both sides of the extruded foam were then removed, leaving 10 mm regions above and below the center of the thickness direction of the cut extruded foam, to obtain test specimens. The compressive strength of the resulting test specimens in the thickness direction was measured using a precision universal testing machine (Shimadzu Corporation, "Autograph AG-X Refresh") in accordance with JIS K7220:2006, and the measured value was used as the planar compressive strength. The planar compressive strength was measured on the 7th day, assuming the day the extruded foam was obtained was the 1st day.

[0106] (lateral compressive strength) First, each extruded foam was cut at its widthwise center to a length of 55 mm in the longitudinal direction (the extrusion direction during the extrusion process) and a length of 20 mm in the widthwise direction. The surface layers (6 mm thick skin layers) on both sides of the extruded foam were then removed, leaving 10 mm regions above and below the center of the thickness direction of the cut extruded foam, to obtain test specimens. The widthwise compressive strength of the resulting test specimens was measured using a precision universal testing machine (Shimadzu Corporation, "Autograph AG-X Refresh") in accordance with JIS K7220:2006, and the measured value was used as the lateral compressive strength. The lateral compressive strength was measured on the 7th day, assuming that the day the extruded foam was obtained was the 1st day.

[0107] (cross-sectional compressive strength) First, each extruded foam was cut at its widthwise center to a length of 20 mm in the longitudinal direction (the extrusion direction during the extrusion process) and a length of 55 mm in the widthwise direction. The surface layers (6 mm thick skin layers) on both sides of the extruded foam were then removed, leaving 10 mm regions above and below the center of the thickness direction of the cut extruded foam, to obtain test specimens. The compressive strength of the resulting test specimens in the longitudinal direction (the extrusion direction during the extrusion process) was measured using a precision universal testing machine (Shimadzu Corporation, "Autograph AG-X Refresh") in accordance with JIS K7220:2006, and the measured value was used as the cross-sectional compressive strength. The cross-sectional compressive strength was measured on the 7th day, assuming that the day the extruded foam was obtained was the 1st day.

[0108] (Strength anisotropy value) The strength anisotropy value was calculated from the planar compressive strength, lateral compressive strength, and cross-sectional compressive strength obtained by the above procedure using the formula shown below. When the strength anisotropy value was 2.0 or less, it was evaluated as "small strength anisotropy." On the other hand, when the strength anisotropy value was greater than 2.0, it was evaluated as "large strength anisotropy." Strength anisotropy value = plane compressive strength / (plane compressive strength x lateral compressive strength x cross-sectional compressive strength) 1 / 3

[0109] <Result> For Example 1 and Comparative Examples 1 and 2, the type of molding die, presence or absence of gap filling members, overall density, middle layer density, surface layer density, difference between surface layer density and middle layer density, planar compressive strength, lateral compressive strength, cross-sectional compressive strength, and strength anisotropy value are shown in Table 1.

[0110] [Table 1]

[0111] In Example 1, a mold member equipped with a roll and a gap filling member was used as the molding die. In Example 1, the difference between the surface layer density and the middle layer density was 25.0 kg / m 3or less. Therefore, the extruded foam molded product obtained in Example 1 had small density variation in the thickness direction. In Example 1, the strength anisotropy value was 2.0 or less. Therefore, the extruded foam molded product obtained in Example 1 had small strength anisotropy.

[0112] In Comparative Example 1, a flat mold member was used as the forming mold. In Comparative Example 2, a mold member equipped with a roll was used as the forming mold, but the mold member used in Comparative Example 2 did not have a gap filling member. In Comparative Examples 1 and 2, the difference between the surface layer density and the middle layer density was 25.0 kg / m 3 The extruded foams obtained in Comparative Examples 1 and 2 had a large density variation in the thickness direction. The extruded foams obtained in Comparative Examples 1 and 2 had a strength anisotropy value of more than 2.0. The extruded foams obtained in Comparative Examples 1 and 2 had a large strength anisotropy.

[0113] The above results demonstrate that the present invention makes it possible to produce extruded foams having small density variations in the thickness direction and small strength anisotropy. [Explanation of symbols]

[0114] 10: Molding mold 10a: Upper mold member (mold member) 10b: Lower mold member (mold member) 11: Roll 12: Gap filling material 110: Die Lip 200: Extruded foam 300: Roll forming machine 400: Extruded foam molded product FP: Flow path VP: Virtual plane

Claims

1. A molding die for molding an extruded foam obtained by extruding a resin composition containing a resin and a foaming agent from a high-pressure region to a low-pressure region through a die lip having a rectangular opening, A pair of mold members are disposed opposite each other, The mold member includes a plurality of rolls and a gap filling member disposed in at least one gap between the plurality of rolls.

2. The mold according to claim 1 , wherein the flow path side ends of the plurality of rolls are arranged on the same imaginary plane.

3. The molding die according to claim 1 , wherein the gap filling member is disposed upstream of a center portion of the molding member in the extrusion direction.

4. The mold of claim 1 , wherein at least one of the plurality of rolls is a non-driven roll.

5. The molding die according to claim 1 , wherein the flow passage side end of the gap filling member has a substantially flat and / or curved surface.

6. The molding die according to claim 2 , wherein the flow passage side end of the gap filling member is substantially planar and substantially parallel to the imaginary plane.

7. The mold according to claim 1 , wherein the flow channel side end of the roll protrudes further toward the flow channel than the flow channel side end of the gap filling member.

8. The mold according to claim 7, wherein the protruding height of the flow path side end of the roll when the flow path side end of the gap filling member is based on is 1% or more and 15% or less of the roll diameter of the roll closest to the gap filling member.

9. a flow channel side end of the roll protrudes toward the flow channel further than a flow channel side end of the gap filling member, The molding die according to claim 2 , wherein the distance between the flow channel side end of the gap filling member and the imaginary plane is 1% to 15% of the roll diameter of the roll closest to the gap filling member.

10. a step Sa of extruding a thermoplastic resin composition containing a thermoplastic resin and a foaming agent from a high-pressure region to a low-pressure region through a die lip having a rectangular opening to obtain an extruded foam; and a step Sb of molding the extruded foam obtained in the step Sa using a molding die. The method for producing an extruded foam, wherein the mold is the mold according to any one of claims 1 to 9.

11. The method for producing an extruded foam according to claim 10, further comprising, after step Sb, step Sc of molding the extruded foam with a roll molding machine having a drive roll.

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