Polystyrene resin multilayer foam board

Abstract

To provide a polystyrene resin multilayer foam board that allows for the complete and complete removal of the thermoplastic resin layer from the polystyrene resin foam layer. [Solution] The thermoplastic resin layer is composed of a mixed resin of polystyrene resin and polyolefin resin, and contains a lubricant, the amount of the lubricant in the thermoplastic resin layer is 0.1 to 5 parts by mass per 100 parts by mass of the total amount of polystyrene resin and polyolefin resin, and the peel strength when peeling the thermoplastic resin layer from the polystyrene resin foam layer is 0.2 N / 25 mm or more and 4 N / 25 mm or less, resulting in a polystyrene resin multilayer foam board.

Description

[Technical Field]

[0001] This invention relates to a polystyrene resin multilayer foam board. [Background technology]

[0002] Conventionally, sheet-shaped polystyrene foam has been used as a material for displays, packaging, and food containers, taking advantage of its rigidity, lightweight properties, and other characteristics. Furthermore, multilayer polystyrene foam, in which a thermoplastic resin layer is laminated onto a polystyrene foam layer, is being considered to provide functionalities such as antistatic properties.

[0003] On the other hand, in recent years, from the perspective of reducing environmental burden such as waste disposal and resource conservation, attempts have been made to recover and reuse the foamed layer of the core material of thermoplastic resin multilayer foams. For example, Patent Document 1 proposes a peelable thermoplastic resin laminated foam sheet in which a thermoplastic resin foam sheet has a diameter in the short axis direction of air bubbles on the surface of 0.005 to 0.5 mm and a surface smoothness Rmax of 5 to 200 μm, and a thermoplastic resin film is laminated, and the peel strength between the thermoplastic resin foam sheet and the film is 5 to 400 g / 25 mm width. In this thermoplastic resin laminated foam sheet, it is said that the foam sheet (foamed layer) can be reused by peeling off the resin film (resin layer) from the foam sheet (foamed layer). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-96572 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, in the thermoplastic resin laminated foam sheet described in Patent Document 1, the release properties of the resin film are ensured by interposing an adhesive layer, such as ethylene vinyl acetate copolymer (EVA) or ethylene-methacrylic acid copolymer (EMA), between the foam sheet and the resin film. In such thermoplastic resin laminated foam sheets, the adhesive layer may remain on the foam sheet after the resin film has been peeled off. In this case, for example, there is a risk that components derived from the adhesive layer may be mixed in during the recycling process of the foam sheet, and there was room for improvement in this respect.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a polystyrene resin multilayer foam board that allows for the peeling of the thermoplastic resin layer from the polystyrene resin foam layer, and furthermore, that leaves little residue on the foam layer after the resin layer has been peeled off. [Means for solving the problem]

[0007] To solve the above problems, the following polystyrene resin multilayer foam board is provided.

[0008] [1] A polystyrene resin multilayer foam board having a polystyrene resin foam layer and a thermoplastic resin layer laminated and bonded to one or both sides of the polystyrene resin foam layer by co-extrusion, The thermoplastic resin layer is composed of a mixed resin of polystyrene resin and polyolefin resin, and also contains a lubricant. The amount of the lubricant in the thermoplastic resin layer is 0.1 to 5 parts by mass per 100 parts by mass of the total amount of the polystyrene resin and the polyolefin resin. The peel strength when peeling the thermoplastic resin layer from the polystyrene-based resin foam layer is 0.2 N / 25 mm or more and 4 N / 25 mm or less. Polystyrene resin multilayer foam board. [2] The polystyrene resin multilayer foam board according to [1], wherein the lubricant is a hydrocarbon lubricant and / or a fatty acid lubricant. [3] The polystyrene-based resin multilayer foamed board according to [2], wherein the hydrocarbon-based lubricant contains liquid paraffin. [4] The polystyrene-based resin multilayer foamed board according to any one of [1] to [3], wherein the ratio of the blending amount of the polyolefin-based resin to the blending amount of the polystyrene-based resin in the thermoplastic resin layer is 0.1 or more and 3 or less. [5] The thermoplastic resin layer contains a compatibilizer for the polystyrene-based resin and the polyolefin-based resin, The polystyrene-based resin multilayer foamed board according to any one of [1] to [4], wherein the blending amount of the compatibilizer in the thermoplastic resin layer is 1 to 10 parts by mass with respect to a total of 100 parts by mass of the blending amount of the polystyrene-based resin and the blending amount of the polyolefin-based resin. [6] The thickness of the polystyrene-based resin multilayer foamed board is 1 mm or more and 30 mm or less, The density of the polystyrene-based resin multilayer foamed board is 30 kg / m 3 or more and 400 kg / m 3 or less. The polystyrene-based resin multilayer foamed board according to any one of [1] to [5]. [7] The basis weight per side of the thermoplastic resin layer is 1 g / m 2 or more and 30 g / m 2 or less. The polystyrene-based resin multilayer foamed board according to any one of [1] to [6]. [Effect of the Invention]

[0009] The present invention can provide a polystyrene-based resin multilayer foamed board in which the thermoplastic resin layer can be peeled off from the polystyrene-based resin foamed layer, and furthermore, after the resin layer is peeled off, it is difficult for a residue to remain on the foamed layer. That is, the polystyrene-based resin multilayer foamed board of the present invention has good peelability of the thermoplastic resin layer. [Embodiments for Carrying out the Invention]

[0010] Hereinafter, an embodiment of the polystyrene-based resin multilayer foamed board of the present invention will be described.

[0011] The polystyrene-based resin multilayer foamed board of the present invention (hereinafter, may be simply referred to as "multilayer foamed board") has a polystyrene-based resin foamed layer (hereinafter, may be simply referred to as "foamed layer") and a thermoplastic resin layer laminated and adhered to one or both sides of this foamed layer by coextrusion (hereinafter, may be simply referred to as "resin layer"). The polystyrene-based resin multilayer foamed board of the present invention can peel the thermoplastic resin layer from the polystyrene-based resin foamed layer and can suppress the remaining peeling of the resin layer or the like on the foamed layer. In the following, the term "good peelability (or good peelability)" may include that the thermoplastic resin layer can be peeled from the polystyrene-based resin foamed layer and that there is little remaining peeling of the thermoplastic resin layer or the like on the foamed layer after peeling.

[0012] <Polystyrene-based resin foamed layer> The polystyrene-based resin foamed layer uses a polystyrene-based resin as the base resin. The polystyrene-based resin in the polystyrene-based resin foamed layer is a resin in which the content of component units derived from styrene is 50% by weight or more. The content of component units derived from styrene in the polystyrene-based resin is preferably 60% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more.

[0013] Specifically, examples of the polystyrene-based resin include one or more of polystyrene (GPPS), rubber-modified polystyrene (impact-resistant polystyrene), styrene-α-methylstyrene copolymer, styrene-p-methylstyrene copolymer, styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-maleic anhydride copolymer, styrene-methyl methacrylate copolymer, styrene-ethyl methacrylate copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-acrylonitrile copolymer, and a mixture of polystyrene and polyphenylene ether. Among these, it is preferable to use polystyrene (GPPS) as the polystyrene-based resin.

[0014] The polystyrene-based resin foam layer may contain other components as long as they do not hinder the objectives of the present invention. Examples of other components include polypropylene resins such as propylene homopolymers and ethylene-propylene copolymers, polyethylene resins such as high-density polyethylene and low-density polyethylene, thermoplastic elastomers such as styrene-conjugated diene block copolymers and their hydrogenated products, and rubbers such as ethylene-propylene rubber and butadiene rubber. The amount of other components added is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, and even more preferably 10 parts by mass or less, per 100 parts by mass of the polystyrene-based resin.

[0015] <Thermoplastic resin layer> The thermoplastic resin layer is composed of a mixed resin of polystyrene resin and polyolefin resin.

[0016] The polystyrene resin contained in the thermoplastic resin layer can be the same polystyrene resin as that used in the polystyrene foam layer described above. Polystyrene (GPPS) is preferably used as the polystyrene resin in the thermoplastic resin layer.

[0017] Examples of polyolefin resins included in the thermoplastic resin layer include polyethylene resins and polypropylene resins. Examples of polyethylene resins include low-density polyethylene (PE-LD), linear low-density polyethylene (PE-LLD), and high-density polyethylene (PE-HD). Furthermore, polypropylene resins include propylene homopolymers or polypropylene copolymers containing 50% by weight or more of propylene-derived structural units. Examples of polypropylene copolymers include copolymers of propylene and ethylene and / or α-olefins having 4 or more carbon atoms, such as propylene-ethylene copolymers, propylene-butene copolymers, and propylene-ethylene-butene copolymers. From the viewpoint of facilitating good lamination of the resin layer onto the foam layer by co-extrusion and facilitating the formation of a resin layer with appropriate adhesive strength, the polyolefin resin is preferably a polyethylene resin. Furthermore, the polyethylene resin is preferably low-density polyethylene (PE-LD) and / or linear low-density polyethylene (PE-LLD).

[0018] The ratio of polyolefin resin to polystyrene resin in the thermoplastic resin layer (polyolefin resin / polystyrene resin) is preferably 0.1 or higher, and more preferably 0.2 or higher. When the above ratio is within this range, the resin layer can be peeled off from the foamed layer more stably. Furthermore, from the viewpoint of ensuring release properties while increasing the adhesive strength between the foam layer and the resin layer, the ratio of the amount of polyolefin resin to the amount of polystyrene resin in the thermoplastic resin layer (polyolefin resin / polystyrene resin) is preferably 3 or less, more preferably 2 or less, and even more preferably 1 or less. Furthermore, in applications such as display materials, printed paper or the like may be attached to the surface of the thermoplastic resin layer. In this case, it is preferable that adhesives for polystyrene resins, which have been used for conventional polystyrene resin foams, can be used for multilayer foam boards. From this viewpoint, it is preferable that the ratio of the amount of polyolefin resin to the amount of polystyrene resin in the thermoplastic resin layer (polyolefin resin / polystyrene resin) be 1 or less, more preferably 0.8 or less, and even more preferably 0.6 or less.

[0019] The thermoplastic resin layer contains a lubricant. Because the thermoplastic resin layer is composed of the above-mentioned mixed resin and contains a specific amount of the lubricant described later, a multilayer foam board is formed that ensures good adhesive strength between the resin layer and the foam layer while maintaining good release properties.

[0020] Lubricants are compounds that enhance the fluidity of resins and reduce friction between resins and processing equipment during resin molding, thereby improving the moldability of resins. Specifically, examples of lubricants include hydrocarbon lubricants, fatty acid lubricants, higher alcohol lubricants, and ester lubricants, and it is preferable to use at least one lubricant selected from hydrocarbon lubricants and fatty acid lubricants.

[0021] Examples of hydrocarbon lubricants include petroleum waxes such as liquid paraffin, paraffin wax, and polyolefin wax (polyethylene wax, etc.), as well as natural waxy substances such as carnauba wax, montan wax, candelilla wax, microcrystalline wax, beeswax, and pine resin. Among these, liquid paraffin is preferably used. Liquid paraffin is paraffin that is liquid at room temperature and pressure (for example, 25°C and 1 atm). Liquid paraffin as defined in JIS K 2231:1993 is particularly preferred. Furthermore, the average carbon number of liquid paraffin is preferably 15 to 50, and more preferably 20 to 35.

[0022] Examples of fatty acid-based lubricants include fatty acids with 12 or more carbon atoms such as stearic acid, behenic acid, and 12-hydroxystearic acid; fatty acid amides such as stearic acid amide, oleic acid amide, erucic acid amide, methylenebisstearate amide, and ethylenestearate amide; and fatty acid metal salts such as zinc stearate, calcium stearate, magnesium stearate, sodium stearate, zinc laurate, zinc oleate, calcium laurate, calcium oleate, magnesium laurate, and magnesium oleate. Among these, it is preferable to use at least one selected from fatty acid amides and fatty acid metal salts as the fatty acid-based lubricant.

[0023] From the viewpoint of reducing residue after peeling off the resin layer, the lubricant is preferably a hydrocarbon-based lubricant. Furthermore, the hydrocarbon-based lubricant is preferably a liquid paraffin.

[0024] The amount of lubricant in the thermoplastic resin layer is 0.1 parts by mass or more and 5 parts by mass or less per 100 parts by mass of the total amount of polystyrene resin and polyolefin resin. If the amount of lubricant is too low, the adhesive strength between the resin layer and the foam layer may become excessively high, making it difficult to peel the resin layer from the foam layer. From this viewpoint, the amount of lubricant in the thermoplastic resin layer is preferably 0.2 parts by mass or more, and more preferably 0.4 parts by mass or more. On the other hand, if the amount of lubricant is too high, the lamination of the resin layer may deteriorate, potentially causing uneven lamination. Also, when printing paper or the like is attached to the resin layer, it may not be possible to peel the printing paper or the like off together with the resin layer, potentially leaving residue on the foam layer. From this viewpoint, the amount of lubricant in the thermoplastic resin layer is preferably 4 parts by mass or less, and more preferably 3 parts by mass or less.

[0025] Furthermore, when liquid paraffin is used as a lubricant, the amount of liquid paraffin in the thermoplastic resin layer is preferably 0.1 parts by mass or more and 5 parts by mass or less, more preferably 0.2 parts by mass or more and 4 parts by mass or less, and even more preferably 0.4 parts by mass or more and 3 parts by mass or less, based on 100 parts by mass of the total amount of polystyrene resin and polyolefin resin.

[0026] Furthermore, it is preferable that the thermoplastic resin layer contains a compatibilizer between the polystyrene resin and the polyolefin resin. By including a compatibilizer in the resin layer, the polyolefin resin can be well dispersed in the polystyrene resin, improving the peelability of the resin layer even when the amount of polyolefin resin is relatively small, and also making it easier to suppress residue remaining on the foam layer when the resin layer is peeled off.

[0027] Examples of compatibilizers include compounds that can reduce the interfacial tension between polystyrene-based resins and polyolefin-based resins and disperse the polyolefin-based resins more finely in the polystyrene-based resins. The compatibilizer is preferably a styrene-based elastomer. Specifically, styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), and hydrogenated products thereof, such as styrene-ethylene-butylene-styrene copolymer (SEBS), can be mentioned. Among these, styrene-ethylene-butylene-styrene copolymer (SEBS) can be preferably used as the compatibilizer.

[0028] From the perspective of facilitating the improvement of the peelability of the thermoplastic resin layer, the blending amount of the compatibilizer in the thermoplastic resin layer is preferably 1 to 15 parts by mass, more preferably 2 to 12 parts by mass, based on 100 parts by mass in total of the blending amount of the polystyrene-based resin and the blending amount of the polyolefin-based resin.

[0029] Additives can be added to the thermoplastic resin layer within a range that does not inhibit the object of the present invention. The type of the additive is not particularly limited, and antistatic agents, weathering agents, ultraviolet absorbers, flame retardants, inorganic fillers, antibacterial agents, colorants, etc. can also be added.

[0030] <Polystyrene-based resin multi-layer foamed board> The polystyrene-based resin multi-layer foamed board of the present invention has a polystyrene-based resin foamed layer and a thermoplastic resin layer laminated and adhered by coextrusion on one or both sides of the polystyrene-based resin foamed layer.

[0031] (Density) The density of the polystyrene-based resin multi-layer foamed board is preferably 30 kg / m 3 or more and 400 kg / m 3 or less, more preferably 40 kg / m<00000​​​​​​The following is even more preferable: When the overall density of the multilayer foam board is within the above range, it becomes easier to obtain a multilayer foam that is both lightweight and has excellent rigidity.

[0032] The density of a polystyrene resin multilayer foam board can be determined from the relationship between the weight and volume of the multilayer foam board, for example, as follows. First, the weight of a test specimen cut to an appropriate size from a polystyrene resin multilayer foam board (for example, a test specimen obtained by cutting the entire width of the polystyrene resin multilayer foam board in the width direction with a length of 10 cm in the extrusion direction) is divided by the area of ​​the test specimen to obtain the basis weight of the test specimen [g / m²]. 2 The density of the test specimen [kg / m³] is calculated by dividing the basis weight of the test specimen by the thickness of the test specimen. 3 Calculate the value and use this value as the density of the polystyrene resin multilayer foam board.

[0033] (Thickness) From the viewpoint of lightness and productivity, the thickness of the polystyrene resin multilayer foam board is preferably 1 mm to 30 mm, more preferably 2 mm to 25 mm, and even more preferably 3 mm to 20 mm.

[0034] The thickness of a polystyrene-based multilayer foam board can be determined as the arithmetic mean of the thickness (mm) measured at 1 cm intervals in the width direction across the entire width of the multilayer foam board.

[0035] (Percentage of closed cells) The closed-cell ratio of the polystyrene resin foam layer is preferably 60% or more, more preferably 70% or more, even more preferably 80% or more, and particularly preferably 85% or more, from the viewpoint of obtaining excellent physical properties such as rigidity and impact resistance.

[0036] The above closed-cell ratio: S(%) is measured in accordance with procedure C described in ASTM D2856-70 using a Toshiba Beckmann 930 air-comparison hydrometer or similar device, and is the actual volume of the test specimen (sum of closed-cell volume and resin volume): Vx(cm³). 3) can be calculated using the following formula (1). S(%)=(Vx-W / ρ)×100 / (Va-W / ρ)···(1) However, Va, W, and ρ in the above formula are as follows: Va: Apparent volume (cm³) of the test specimen used for measurement. 3 ) W: Weight of the test specimen (g) ρ: Density of the resin composition constituting the test specimen (g / cm³) 3 ) The density of the resin composition is ρ (g / cm³). 3 ) is determined by measuring the weight W (g) of the test specimen and the volume (cm³) of the sample obtained by removing air bubbles from the test specimen used for measurement by heating and pressing, and then cooling it. 3 It can be calculated from ).

[0037] (Basis weight per side of the resin layer) The basis weight per side of the thermoplastic resin layer is 1 g / m². 2 More than 30g / m 2 The following is preferable. By setting the basis weight per side of the thermoplastic resin layer within this range, the thermoplastic resin layer can be laminated more stably, and a polystyrene-based resin multilayer foam board with good peelability of the thermoplastic resin layer can be stably obtained. Furthermore, from the viewpoint of good peelability of the thermoplastic resin layer, the basis weight per side of the thermoplastic resin layer should be 2 g / m². 2 Preferably, it is 3 g / m 2 It is more preferable that the above is true. Also, the basis weight per side of the thermoplastic resin layer is 25 g / m². 2 Preferably, it is 20 g / m 2 Preferably, it is 15 g / m 2 The following is even more preferable:

[0038] The basis weight per side of a thermoplastic resin layer can be determined by directly measuring the basis weight of the resin layer, or by calculating it using the following formula (2) based on the relationship between the basis weight of the polystyrene resin multilayer foam board and the discharge volume of each layer during foam board manufacturing.

[0039] Basis weight per side of thermoplastic resin layer [g / m²] 2 ] = Basis weight of polystyrene resin multilayer foam board [g / m²] 2 ] × (Discharge rate per side of the thermoplastic resin layer [kg / hr] / Total discharge rate of the polystyrene foam layer and thermoplastic resin layer [kg / hr]) ... (2)

[0040] (Peel strength between foam layer and resin layer) The peel strength when separating the thermoplastic resin layer from the polystyrene foam layer is between 0.2 N / 25 mm and 4 N / 25 mm. This range of peel strength allows for good adhesion between the resin layer and the foam layer while enabling smooth separation of the resin layer. From the viewpoint of increasing the adhesive strength between the resin layer and the foam layer, the peel strength when peeling the thermoplastic resin layer from the polystyrene-based resin foam layer is preferably 0.3 N / 25 mm or more, and more preferably 0.4 N / 25 mm or more. Furthermore, from the viewpoint of making the resin layer easier to peel off more stably, the peel strength when peeling the thermoplastic resin layer from the polystyrene-based resin foam layer is preferably 3 N / 25 mm or less, and more preferably less than 2 N / 25 mm. The peel strength when separating the thermoplastic resin layer from the polystyrene-based resin foam layer can be adjusted to the above range by setting a predetermined relationship between the amount of polystyrene-based resin and the amount of polyolefin-based resin in the thermoplastic resin layer, and by incorporating a predetermined amount of lubricant into the thermoplastic resin layer. Furthermore, for example, increasing the amount of polyolefin-based resin in the thermoplastic resin layer makes it easier to adjust the peel strength to a lower level.

[0041] The peel strength can be measured by performing a 90-degree peel test in accordance with JIS K 6854-1:1999, as follows. First, a test specimen with a width of 25 mm and a length of 150 mm or more and a thickness of multilayer foam board is cut from the multilayer foam board. Next, in accordance with JIS K 6854-1:1999, the test specimen is placed in a peel test apparatus, and a cloth adhesive tape is adhered to the surface of the resin layer on the test specimen as a flexible non-adhesive material. The peel strength (N / 25 mm) is measured by performing a 90-degree peel test of the cloth adhesive tape. The test speed in the peel test is set to 400 mm / min. The measurement is performed five or more times on different test specimens, and the arithmetic mean is taken as the peel strength when separating the thermoplastic resin layer from the polystyrene foam layer.

[0042] The multilayer foam board of the present invention can be suitably used in display material applications such as promotional POP displays, where printed paper or the like is attached to the surface of the thermoplastic resin layer. As with the conventional technology described above, when bonding the resin layer and the foam layer with an adhesive layer made of adhesives such as ethylene vinyl acetate copolymer or ethylene-methacrylic acid copolymer, the adhesive layer may remain on the foam sheet when the resin layer is peeled off. In this case, when recycling the foam layer, components derived from the adhesive layer are more likely to be mixed into the recycled material, which may lead to a decrease in the physical properties of the recycled material or the generation of odors. In the multilayer foam board of the present invention, a multilayer foam having a peelable resin layer can be obtained without providing an adhesive layer, thus providing excellent recyclability of the foam layer.

[0043] (Method for manufacturing polystyrene resin multilayer foam boards) An embodiment of the polystyrene resin multilayer foam board of the present invention will be described below. The polystyrene resin multilayer foam board of the present invention can be manufactured using an extrusion foaming apparatus comprising a foam layer forming extruder, a resin layer forming extruder, and a co-extrusion die. The co-extrusion die is located downstream of the foam layer forming extruder and is connected to the resin layer forming extruder downstream of the resin layer forming extruder, and has a structure that allows for the lamination of each layer-forming resin molten material within the co-extrusion die. An annular die can be used as the co-extrusion die. An example of a method for manufacturing a multilayer foam board using an extrusion foaming apparatus will be described below. First, polystyrene resin for forming the polystyrene foam layer, along with additives such as foam regulators added as needed, are supplied to an extruder for foam layer formation and heated and kneaded. Then, a foaming agent is added and kneaded further to prepare a foamable resin molten product for foam layer formation.

[0044] Meanwhile, polystyrene resin, polyethylene resin, lubricant, and other compatibilizers added as needed are supplied to a resin layer forming extruder, heated and kneaded to prepare a resin molten material for forming the resin layer.

[0045] Next, the foaming resin molten material for foam layer formation and the resin molten material for resin layer formation are introduced into an annular die and combined and laminated, and then co-extruded. This produces a tubular laminated foam in which the foaming resin molten material for foam layer formation is foamed and a resin layer is laminated and bonded to the outer surface. This tubular laminated foam is then passed through a pinch roll while being taken up, and the inner surfaces of the tubular laminated foam are fused together to form a plate, thereby obtaining a polystyrene resin multilayer foam board having a polystyrene resin foam layer and a thermoplastic resin layer laminated and bonded to the polystyrene resin foam layer.

[0046] Various devices such as annular dies and extruders used in the manufacture of polystyrene resin multilayer foam boards can be those that have been known and used in the field of conventional extrusion foaming. Alternatively, a tubular laminated foam can be manufactured by co-extrusion, in which a resin layer is laminated and bonded to the outer and / or inner surface of a foam layer. This tubular laminated foam can then be placed along a mandrel, which is a tubular cooling device, cut open to obtain a sheet-like laminated foam, and then flattened in a heating furnace or the like to obtain a polystyrene resin multilayer foam board.

[0047] The foaming temperature when foaming a foaming resin molten material for forming a foamed layer depends on the type of polystyrene resin, the melt viscosity, and the type and amount of foaming agent added, but is usually in the range of 130°C to 170°C, preferably 135°C to 150°C.

[0048] The melt flow rate (MFR) of the polystyrene resin used to form the polystyrene resin foam layer is preferably 0.1 to 5 g / 10 min, and more preferably 1 to 4 g / 10 min. Having the MFR within this range allows for the production of polystyrene resin multilayer foam boards with a closed-cell structure and excellent mechanical strength over a wide range of manufacturing conditions. In this specification, the melt flow rate of the polystyrene resin refers to the melt mass flow rate measured by test method A of JIS K 7210-1 (2014), using test conditions of a temperature of 200°C and a load of 5 kg.

[0049] The melt flow rate (MFR) of the polystyrene resin used to form the thermoplastic resin layer is preferably 1 g / 10 min to 20 g / 10 min, and more preferably 2 g / 10 min to 10 g / 10 min. A good resin layer can be stably formed when the MFR of the polystyrene resin used to form the thermoplastic resin layer is within the above range. In this specification, the melt flow rate of the polystyrene resin refers to the melt mass flow rate measured by method A of JIS K 7210-1 (2014), with a test temperature of 200°C and a load of 5 kg.

[0050] The melt flow rate (MFR) of the polyolefin resin used to form the thermoplastic resin layer is preferably 0.4 g / 10 min to 20 g / 10 min, and more preferably 1 g / 10 min to 15 g / 10 min. A good resin layer can be stably formed when the MFR of the polyolefin resin used to form the thermoplastic resin layer is within the above range. In this specification, the melt flow rate of the polyolefin resin refers to the melt mass flow rate measured by method A of JIS K 7210-1 (2014), with a test temperature of 190°C and a load of 2.16 kg.

[0051] When a compatibilizer such as a styrene-based thermoplastic elastomer is incorporated into a thermoplastic resin layer, its MFR is preferably 1 g / 10 min or more and 10 g / 10 min or less. Having the compatibilizer's MFR within this range allows for more stable and improved release properties of the thermoplastic resin layer. In this specification, the melt flow rate of the compatibilizer refers to the melt mass flow rate measured according to Test Method A of JIS K 7210-1 (2014), with a test temperature of 230°C and a load of 2.16 kg.

[0052] (Bubble regulator) Both organic and inorganic foam regulators can be used as additives to the foaming resin molten material for forming the foam layer. Examples of inorganic foam regulators include metal borate salts such as zinc borate, magnesium borate, and borax, sodium chloride, aluminum hydroxide, talc, zeolite, silica, calcium carbonate, and sodium bicarbonate. Examples of organic foam regulators include sodium 2,2-methylenebis(4,6-tert-butylphenyl) phosphate, sodium benzoate, calcium benzoate, aluminum benzoate, and sodium stearate. Combinations of citric acid and sodium bicarbonate, or alkali salts of citric acid and sodium bicarbonate, can also be used as foam regulators. Two or more of these foam regulators can be used in combination.

[0053] The amount of foam regulator added is approximately 0.05 to 10 parts by mass, preferably 0.1 to 5 parts by mass, per 100 parts by mass of polystyrene resin constituting the polystyrene resin foam layer.

[0054] (Foaming agent) Examples of blowing agents include organic physical blowing agents such as aliphatic hydrocarbons with 2 to 6 carbon atoms, such as propane, n-butane, isobutane, n-pentane, isopentane, isohexane, and cyclohexane; halogenated aliphatic hydrocarbons with 1 to 3 carbon atoms, such as methyl chloride, ethyl chloride, 1,1,1,2-tetrafluoroethane, and 1,1-difluoroethane; aliphatic alcohols with 1 to 4 carbon atoms, such as methanol, ethanol, propanol, butanol, isopropyl alcohol, isobutyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; or aliphatic ethers with 2 to 8 carbon atoms, such as methyl ether, ethyl ether, propyl ether, isopropyl ether, and methyl ethyl ether; and inorganic physical blowing agents such as nitrogen, carbon dioxide, and water. Two or more of these blowing agents can be used in combination. Among the blowing agents mentioned above, organic physical blowing agents are preferred because they easily foam polystyrene resins, and those mainly composed of n-butane, isobutane, or mixtures thereof are particularly preferred.

[0055] When using an organic physical blowing agent such as a butane mixture of 30% by mass of isobutane and 70% by mass of n-butane as the blowing agent, the amount of blowing agent added is preferably about 0.5 to 10 parts by mass, more preferably 1 to 8 parts by mass, and even more preferably 2 to 6 parts by mass, per 100 parts by mass of polystyrene resin constituting the foamed layer.

[0056] (Volatile plasticizer) In the method for manufacturing polystyrene resin multilayer foam boards of the present invention, when co-extruding the foamable resin molten material for forming the foam layer and the resin molten material for forming the resin layer, it is preferable to add a volatile plasticizer to the resin molten material for forming the resin layer in order to improve the melt elongation of the resin molten material for forming the resin layer near the foaming temperature and to allow the elongation of the resin molten material for forming the resin layer to closely follow the elongation of the foamable resin molten material for forming the foam layer.

[0057] Preferably, a volatile plasticizer is used that, when present in the molten resin for resin layer formation, has the property of reducing the melt viscosity, and after the resin layer is formed, it volatilizes from the resin layer and does not easily remain in the resin layer.

[0058] As volatile plasticizers, it is preferable to use one or more selected from, for example, aliphatic hydrocarbons having 2 to 6 carbon atoms, halogenated aliphatic hydrocarbons having 1 to 3 carbon atoms, aliphatic alcohols having 1 to 4 carbon atoms, or aliphatic ethers having 2 to 8 carbon atoms. Among these, aliphatic hydrocarbons having 2 to 6 carbon atoms are preferred from the viewpoint of high solubility in thermoplastic resins and ease of handling, and in particular, those mainly composed of n-butane, isobutane, or mixtures thereof are more preferred.

[0059] The amount of volatile plasticizer added is preferably about 1 to 10 parts by mass per 100 parts by mass of the total thermoplastic resin used to form the thermoplastic resin layer.

[0060] The polystyrene resin multilayer foam board of the present invention is not limited in any way to the embodiments described above. [Examples]

[0061] The polystyrene resin multilayer foam board of the present invention will be described below with reference to examples, but the polystyrene resin multilayer foam board of the present invention is not limited in any way to the following examples.

[0062] <Preparation of polystyrene resin multilayer foam board> Polystyrene resin multilayer foam boards were fabricated using the following equipment and materials.

[0063] As a manufacturing apparatus, a co-extrusion device was used, which consisted of a tandem-type foam layer forming extruder comprising an extruder with a barrel inner diameter of 65 mm and another extruder with a barrel inner diameter of 90 mm connected to the first extruder, with a co-extrusion annular die (lip diameter 60 mm) attached to the outlet, and further connected to the co-extrusion annular die, a resin layer forming extruder with a barrel inner diameter of 40 mm.

[0064] The following materials were used for the foam layer and resin layer introduced into the above manufacturing apparatus.

[0065] [Polystyrene foam layer] Polystyrene resin (PS): GPPS "HH102-304" manufactured by PS Japan Co., Ltd. [Thermoplastic resin layer] (resin) Polystyrene resin (PS1): GPPS "680" manufactured by PS Japan Co., Ltd. Polystyrene resin (PS2): GPPS "HRM12" manufactured by Toyo Styrene Co., Ltd. Polyethylene resin (PE1): Low-density polyethylene "NUC-8321" manufactured by ENEOS NUC Corporation. Polyethylene resin (PE2): Low-density polyethylene "NUC-8009" manufactured by ENEOS NUC Corporation. (Lubricant) Liquid paraffin (lubricant 1): "Moresco White P-60 (average carbon number 25)" manufactured by MORESCO Corporation. Ethylene bis-stearamide (lubricant 2): "Alflow H-50S" manufactured by NOF Corporation Magnesium stearate (lubricant 3): "Magnesium Stearate G" manufactured by NOF Corporation Zinc stearate (lubricant 4): "Zinc Stearate G" manufactured by NOF Corporation (Compatibilizer) Styrene-based thermoplastic elastomer (TPS): Asahi Kasei Corporation ToughTec H1041 (MFR: 5g / 10min (230℃, load 2.16kg))

[0066] The MFRs for each polystyrene resin are as follows:

[0067] [Table 1]

[0068] The MFRs for each polyolefin resin (polyethylene resin) are as follows:

[0069] [Table 2]

[0070] A polystyrene resin for forming the foam layer and talc as a foam regulator were supplied to a foam layer forming extruder at a ratio of 0.9 parts by mass per 100 parts by mass of the polystyrene resin, and the mixture was heated and kneaded. Next, 5 parts by mass of mixed butane (30% by mass of isobutane and 70% by mass of normal butane) were added as a foaming agent per 100 parts by mass of the polystyrene resin and kneaded further. The temperature was then adjusted to 142°C to form a foamable resin molten material for foam layer formation, which was then introduced into a co-extrusion annular die so that the foam layer discharge rate was 50 kg / hr.

[0071] Meanwhile, polystyrene resins (PS1, PS2), polyethylene resins (PE1, PE2), lubricants 1-4, and compatibilizer (TPS) for forming the resin layer were supplied to the resin layer forming extruder in the proportions shown in Table 3, and then heated and kneaded. Next, mixed butane was added as a volatile plasticizer at a ratio of 4 parts by mass per 100 parts by mass of raw material and kneaded further. The temperature was then adjusted to 142°C to form a resin molten material for resin layer formation, which was then introduced into a co-extrusion annular die so that the total discharge rate of the resin layer was 4 kg / hr.

[0072] In an annular die for co-extrusion, a foaming resin molten material for forming a foam layer and a resin molten material for forming a resin layer were combined and laminated, and then co-extruded into a cylindrical shape to form a cylindrical laminated foam. The cylindrical laminated foam was taken up at a speed of 10 m / min and sandwiched between pinch rolls, and the inner surfaces were fused together to obtain polystyrene resin multilayer foam boards with a width of approximately 330 mm and a thickness of 4 mm, as shown in Examples 1 to 11 and Comparative Examples 1 to 6.

[0073] <Evaluation of polystyrene resin multilayer foam boards> (Basis weight per side of thermoplastic resin layer) Following the method described above, the basis weight of the polystyrene resin multilayer foam board and the amount of each layer extruded during foam board manufacturing were used to calculate the basis weight using equation (2). (Thickness of multilayer foam board) The thickness was determined as the arithmetic mean of the thickness (mm) measured at 1 cm intervals in the width direction across the entire width of the multilayer foam board, according to the method described above. (Apparent density of multilayer foam boards) The following measurements were taken according to the method described above. First, a test specimen was cut from a polystyrene resin multilayer foam board, with a length of 10 cm along the extrusion direction and spanning the entire width of the multilayer foam board. Next, the basis weight of the test specimen [g / m²] was calculated by dividing the weight of the test specimen by the area of ​​the test specimen. 2 The basis weight of the test specimen was divided by the thickness of the test specimen, and the density of the test specimen [kg / m³] was calculated. 3 The value was calculated and this value was taken as the density of the polystyrene resin multilayer foam board. (Peelability test of adhesive paper) A paper-laying adhesive is applied to the surface of the thermoplastic resin layer, and a 25mm x 150mm sheet of adhesive paper (plain paper) is attached, with a density of 1.6g / cm². 2The material was left undisturbed for 24 hours while a load was applied. Afterward, the multilayer foam was placed in a peel test machine, and a 90° peel test was performed by peeling the attached adhesive paper from the edge (the 25mm side). The test speed for the peel test was set to 400 mm / min. The evaluation assessed whether the adhesive paper could be peeled off the polystyrene foam layer together with the thermoplastic resin layer without damage to the paper. For the paper adhesive, products such as "CA-197" and "Super X Hyper Wide" from Cemedyne Co., Ltd. can be used. ○: The adhesive paper peels off cleanly from the foam layer without being damaged. ×: The adhesive paper is damaged or otherwise fails to peel properly from the foam layer, leaving residue on the foam layer. (Peel strength of thermoplastic resin layer) First, a test specimen with a width of 25 mm, a length of 150 mm, and a thickness of 25 mm was cut from the multilayer foam board. At this time, the length direction of the test specimen was aligned with the extrusion direction of the multilayer foam board. Next, in accordance with JIS K 6854-1:1999, the test specimen was placed in a peel test apparatus, and a cloth adhesive tape (Nitto Denko Packaging Cloth Tape No. 750) was adhered to the surface of the resin layer on the test specimen. A 90-degree peel test of the cloth adhesive tape was performed, and the peel strength (N / 25 mm) was measured. The test speed in the peel test was 400 mm / min. The above measurement was performed five times on different test specimens, and the arithmetic mean was defined as the peel strength when separating the thermoplastic resin layer from the polystyrene foam layer. In Table 3, those where the peel strength (N / 25mm) of the thermoplastic resin layer is indicated as ">6" indicate that the adhesive strength between the resin layer and the foam layer exceeded the adhesive strength of the cloth adhesive tape. During the test, the resin layer did not peel off from the foam layer, and only the cloth adhesive tape peeled off from the surface of the resin layer. (Remnants after peeling) In measuring the peel strength of the thermoplastic resin layer described above, the surface of the polystyrene resin foam layer after peeling by the peel test was observed using an electron microscope (Keyence Corporation Digital Microscope VHX-700) (observation area: 80 mm × 80 mm). The area of ​​the resin layer remaining on the foam layer was calculated, and the ratio of the area of ​​the remaining resin layer to the observed area (percentage of remaining resin after peeling) was determined and evaluated according to the following criteria. ◎: Less than 1% ○: 1% or more but less than 10% △: 10% or more but less than 30% ×: 30% or more

[0074] [Table 3]

[0075] As shown in Table 3, the polystyrene resin multilayer foam boards of Examples 1-11 have a thermoplastic resin layer composed of a mixed resin of polystyrene resin and polyolefin resin, and also contain a lubricant, the amount of lubricant in the thermoplastic resin layer is within a specific range, and the peel strength when peeling the thermoplastic resin layer from the polystyrene resin foam layer is within a specific range. It was confirmed that the polystyrene resin multilayer foam boards of Examples 1-11 allowed for good peeling of the thermoplastic resin layer, and that there was significantly less residue left on the foam layer after peeling of the resin layer.

[0076] On the other hand, in Comparative Example 1, a polystyrene resin multilayer foam board that did not contain a lubricant in the thermoplastic resin layer, it was confirmed that the thermoplastic resin layer was difficult to peel off. In Comparative Example 2, a polystyrene resin multilayer foam board that contained an excessive amount of lubricant in the thermoplastic resin layer, the lamination state of the thermoplastic resin layer deteriorated. In addition, it was confirmed that the adhesive paper attached to the resin layer could not be peeled off properly, and that a large amount of residue remained on the foam layer after the resin layer was peeled off. In Comparative Example 3, a polystyrene resin multilayer foam board, it was confirmed that the thermoplastic resin layer was difficult to peel off. In Comparative Examples 4-6, polystyrene resin multilayer foam boards that did not contain polyolefin resin in the thermoplastic resin layer, it was confirmed that the thermoplastic resin layer was difficult to peel off regardless of the amount of lubricant added.

[0077] Furthermore, a peel test of the adhesive paper described above was performed on the polystyrene resin multilayer foam boards of Examples 1-11 using a polystyrene resin adhesive (CA-197, manufactured by Cemedyne Co., Ltd.) as the adhesive. As a result, the polystyrene resin multilayer foam boards of Examples 1-6 and 8-11 were able to adhere the adhesive paper well. On the other hand, the polystyrene resin multilayer foam board of Example 7, which has a high amount of polyolefin resin, could not have the adhesive paper adhered to it.

Claims

1. A polystyrene resin multilayer foam board having a polystyrene resin foam layer and a thermoplastic resin layer laminated and bonded to one or both sides of the polystyrene resin foam layer by co-extrusion, The thermoplastic resin layer is composed of a mixed resin of polystyrene resin and polyolefin resin, and also contains a lubricant. The amount of the lubricant in the thermoplastic resin layer is 0.1 to 5 parts by mass per 100 parts by mass of the total amount of the polystyrene resin and the polyolefin resin. The peel strength when peeling the thermoplastic resin layer from the polystyrene-based resin foam layer is 0.2 N / 25 mm or more and 4 N / 25 mm or less. Polystyrene resin multilayer foam board.

2. The polystyrene resin multilayer foam board according to claim 1, wherein the lubricant is a hydrocarbon-based lubricant and / or a fatty acid-based lubricant.

3. The polystyrene resin multilayer foam board according to claim 2, wherein the hydrocarbon lubricant comprises liquid paraffin.

4. The polystyrene resin multilayer foam board according to claim 1 or 2, wherein the ratio of the amount of polyolefin resin to the amount of polystyrene resin in the thermoplastic resin layer is 0.1 or more and 3 or less.

5. The thermoplastic resin layer contains a compatibilizer for the polystyrene resin and the polyolefin resin, The polystyrene resin multilayer foam board according to claim 1 or 2, wherein the amount of the compatibilizer in the thermoplastic resin layer is 1 to 10 parts by mass with respect to 100 parts by mass of the total amount of polystyrene resin and polyolefin resin.

6. The thickness of the polystyrene resin multilayer foam board is 1 mm or more and 30 mm or less. The density of the polystyrene resin multilayer foam board is 30 kg / m³ ３ More than 400kg / m ３ The polystyrene resin multilayer foam board according to claim 1 or 2, which is as follows:

7. The basis weight per side of the aforementioned thermoplastic resin layer is 1 g / m². ２ 30g / m or more ２ The polystyrene resin multilayer foam board according to claim 1 or 2, which is as follows:

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