Thermoforming foamed resin laminated sheets, molded products, and containers

Abstract

To provide a laminated resin foam sheet for thermoforming that is excellent in sheet formability and appearance, and a formed article and a container each of which is obtained by forming the sheet and has a good appearance and rigidity.SOLUTION: The inventive laminated resin foam sheet for thermoforming is predominantly composed of a polypropylene resin and includes a foamed layer and a non-foamed layer. The foamed layer includes a first block polypropylene resin and a homopolypropylene resin. The non-foamed layer includes a second block polypropylene resin and a low-density polyethylene resin. The inventive formed article and container are each obtained by forming the laminated resin foam sheet for thermoforming.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a foamed resin laminate sheet for thermoforming, which is excellent in sheet moldability and appearance, and to a molded article and a container, which are obtained by molding the sheet and are excellent in appearance and rigidity. [Background technology]

[0002] Polypropylene (hereinafter, referred to as "PP")-based resin foam sheets are widely used as various molded products, such as food and beverage containers, due to their excellent physical properties. For example, Patent Document 1 describes a PP-based resin foam using a mixture of an ethylene-propylene block copolymer and linear low-density polyethylene as the base resin.

[0003] In order to achieve various functions, a laminated sheet is used in which other layers are laminated on a PP resin foamed sheet as a base material. However, when laminating molten resin to produce a laminated sheet, the foaming state of the molten kneaded material changes significantly, and as a result, it is known that the bubbles in the foamed sheet become larger or many open bubbles are generated in the foamed sheet, which adversely affects the secondary processability of the laminated sheet. In this regard, Patent Document 2 discloses a method for producing a polyolefin resin laminated foamed sheet to reduce the open cell rate in the foamed sheet.

[0004] In recent years, as plastics are used and discarded in large quantities, problems associated with landfilling and incineration have become a concern. The combustion of plastics causes environmental loads such as the generation of harmful gases during combustion and global warming due to the large amount of heat generated by combustion. In order to reduce such environmental loads, it is known to use biopolyethylene as a non-petroleum-derived resin material. However, Patent Document 3 points out that simply blending biopolyethylene with polypropylene results in poor durability of the molded body obtained, and it is relatively easily damaged by dropping, etc. In order to solve this problem, Patent Document 3 describes a resin molded body consisting of biopolyethylene, polypropylene, and at least one of an olefin-based thermoplastic elastomer and an α-olefin-based copolymer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 63-67810 [Patent Document 2] Patent No. 5714807 [Patent Document 3] JP 2013-227462 A Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, it is known that the foaming state in the foamed sheet adversely affects the secondary processability of the laminated sheet. Therefore, a laminated sheet having a low open cell ratio and excellent sheet moldability is required. In addition, since the molded product obtained by molding the laminated sheet is used as a packaging container, the laminated sheet and the molded product are required to have excellent appearance and rigidity.

[0007] An object of the present invention is to provide a foamed resin laminate sheet for thermoforming, which has excellent sheet moldability and appearance, and a molded article and a container, which are obtained by molding the sheet and have excellent appearance and rigidity. [Means for solving the problem]

[0008] The foamed resin laminate sheet for thermoforming of the present invention is characterized in that it contains a polypropylene-based resin as a main component and includes a foamed layer and a non-foamed layer, the foamed layer contains a first block polypropylene resin and a homopolypropylene resin, and the non-foamed layer contains a second block polypropylene resin and a low-density polyethylene-based resin.

[0009] The molded article and container of the present invention can be obtained by molding the thermoforming foamed resin laminate sheet of the present invention. Effect of the Invention

[0010] The thermoforming foamed resin laminate sheet of the present invention has a low open cell ratio and is excellent in sheet moldability and appearance. Furthermore, the molded article and container of the present invention are excellent in appearance and rigidity. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following describes an embodiment of the present invention. The embodiment is merely an example of implementing the present invention, and the present invention is not limited to the embodiment.

[0012] (1) Thermoforming foam resin laminate sheet A foamed resin laminate sheet for thermoforming according to one embodiment of the present invention (hereinafter simply referred to as "the laminate sheet") contains a polypropylene (hereinafter referred to as "PP")-based resin as a main component and includes a foamed layer and a non-foamed layer, the foamed layer contains a first block PP resin and a homo PP resin, and the non-foamed layer contains a second block PP resin and a low-density polyethylene (hereinafter referred to as "PE")-based resin.

[0013] The laminate sheet is mainly composed of a PP-based resin. The PP-based resin refers to the first and second block PP resins, the homo PP resin, and any other PP-based resins that may be included. Here, the term "main component" refers to an embodiment in which the content of the PP-based resin is greater than that of other resins in both the foamed layer and the non-foamed layer, or is the same as that of the other resin with the greatest content. More specifically, the term "main component" refers to an embodiment in which the content of the PP-based resin is 50% by weight or more, preferably 60% by weight or more, in both the foamed layer and the non-foamed layer, when the total resin components are 100% by weight.

[0014] The foam layer contains a first block PP resin and a homo PP resin. The contents of the first block PP resin and the homo PP resin are not particularly limited and can be appropriately selected as necessary. For example, when the total resin components in the foam layer are taken as 100% by weight, the content of the first block PP resin can be 50 to 80% by weight and the content of the homo PP resin can be 50 to 20% by weight, and preferably the content of the block PP resin can be 50 to 70% by weight and the content of the homo PP resin can be 50 to 30% by weight.

[0015] The homo PP resin is not particularly limited in terms of its specific physical properties, so long as it is a homopolymer of propylene. As the homo PP resin, for example, a homo PP resin having an MFR value of 50 to 70 g / 10 min can be used.

[0016] The first block PP resin is a propylene-ethylene block copolymer in which a polymer mainly composed of ethylene and an ethylene-propylene rubber-like copolymer are dispersed in a linear polymer mainly composed of propylene to form an island structure. The block PP resin can usually be obtained by polymerizing homopolypropylene and then copolymerizing propylene and ethylene in the presence of homopolypropylene. There is no particular limitation on the specific physical properties of the first block PP resin. For example, a block PP resin having an MFR value of 1 to 6 g / 10 min can be used as the first block PP resin. The MFR values ​​in this specification are measured according to the method of JIS K7210:1999 under the conditions of a measurement temperature of 230°C and a load of 2.16 kg for PP resin and a measurement temperature of 190°C and a load of 2.16 kg for PE resin.

[0017] The foamed layer may contain, as a resin component, a resin other than the first block PP resin and the homo PP resin. Specific examples of the other resin include polyolefin resins other than PP resins (e.g., PE resins). When a PE resin is used as the other resin, the PE resin may be the same as the low-density PE resin contained in the non-foamed layer, or may be a different PE resin.

[0018] The PE resin is preferably a PE resin obtained by polymerization (homopolymerization or copolymerization) of non-petroleum-derived ethylene, for example, plant-derived ethylene. By using such a resin, the amount of CO generated from fossil-derived raw materials during combustion is reduced. 2 This is preferable because it can suppress the generation of pollutants and reduce the environmental load. Plant-derived ethylene can be obtained, for example, by distilling and separating alcohol components, particularly ethyl alcohol, from a fermented product of sugar or cellulose extracted from plant raw materials (such as sugarcane and corn) and subjecting the alcohol components to a dehydration reaction. The plant-derived ethylene can be polymerized alone or with other monomers by a conventional polymerization method to obtain a plant-derived PE resin.

[0019] There is no particular limitation on the specific structure of the plant-derived PE resin, so long as it is obtained by polymerization of the plant-derived ethylene. When the PE resin is a copolymer, the proportion of ethylene units can be 80% by weight or more, 90% by weight or more, or 95% by weight or more. Specific examples of the plant-derived PE resin include low-density polyethylene (LDPE; density 0.910 to 0.930 g / cm) obtained by polymerizing the plant-derived ethylene alone. 3 ), and linear low-density polyethylene (LLDPE; density 0.910-0.925 g / cm3) copolymerized with plant-derived ethylene and α-olefins such as 1-butene and 1-hexene refined from fossil raw materials such as naphtha. 3 These PEs can be produced by known methods.

[0020] There is no particular limitation on the method for forming the foam layer. The foam layer can be formed by a known method, for example, by melt-kneading the PP resin as the main component with the foaming component and extrusion foaming. There is no particular limitation on the conditions for melt-kneading and foaming, and they can be set appropriately as needed. There is no particular limitation on the type of the foaming component, as long as it can foam the PP resin. As the foaming component, physical foaming agents (propane, n-butane, etc.) and chemical foaming agents that decompose to generate gas such as carbon dioxide gas (for example, organic chemical foaming agents such as sodium citrate and inorganic chemical foaming agents such as sodium bicarbonate) can be used.

[0021] The expansion ratio of the foamed layer is not particularly limited. Usually, the higher the expansion ratio, the higher the open cell ratio, but the less material is used. The expansion ratio is preferably 2 times or more, more preferably 3 times or more. When the expansion ratio is within the above range, the amount of resin is small for the same thickness, which reduces the environmental load, and it is possible to obtain a laminated sheet and a molded product that are lightweight and excellent in heat insulation, which is preferable.

[0022] The open cell ratio of the laminate sheet is usually 30% or less, preferably 25% or less, and more preferably 20% or less. When the open cell ratio is within the above range, the laminate sheet has excellent mechanical strength such as heat resistance and impact resistance, and can suppress fluctuation in sheet thickness and deterioration of the appearance such as the occurrence of blisters or flow marks, and can further enhance moldability, which is preferable. The open cell ratio can be calculated, for example, by the method described in the Examples.

[0023] The non-foamed layer contains a second block PP resin and a low-density PE resin. The contents of the second block PP resin and the low-density PE resin are not particularly limited and can be appropriately selected as needed. When the total resin components in the non-foamed layer are taken as 100% by weight, the content of the second block PP resin can be 70 to 90% by weight and the content of the low-density PE resin can be 10 to 30% by weight.

[0024] The second block PP resin is not particularly limited in structure and physical properties as long as it is a block PP resin having a structure or physical properties different from those of the first block PP resin. Unless otherwise specified, the details of the second block PP resin are the same as those of the first block PP resin. As the second block PP resin, for example, a block PP resin having a different MFR value from that of the first block PP resin, more specifically, a block PP resin having a higher MFR value (for example, 8 to 20 g / 10 min) than that of the first block PP resin, can be used.

[0025] Generally, low-density PE resins are obtained by polymerizing ethylene under high-temperature and high-pressure conditions. By polymerizing under such conditions, ethylene does not bond in a simple chain shape, but has many long-chain branches and short-chain branches. The density of the low-density PE resin is in the range of 0.910 to 0.930. There is no particular limitation on the specific structure of the low-density PE resin, as long as the density is within the above range. However, the low-density PE resin does not include linear low-density PE resins. Linear low-density PE resins are produced by copolymerizing ethylene with a small amount of α-olefin using a Ziegler catalyst or the like, and have a linear molecular skeleton and short-chain branches. Specific examples of the linear low-density PE resins include PE resins with a density of 0.910 to 0.925 and a branched chain with 8 or less carbon atoms or 6 or less carbon atoms.

[0026] Specifically, the low-density PE resin may have an MFR value of 3 to 15 g / 10 min.

[0027] The low-density PE resin is preferably a low-density PE resin obtained by polymerizing non-petroleum-derived ethylene, for example, a plant-derived low-density PE resin obtained by polymerizing plant-derived ethylene alone or copolymerizing it with other monomers by a conventional polymerization method. By using such a resin, the CO generated from the fossil-derived raw material during combustion can be reduced. 2 The above explanation is applicable to the plant-derived ethylene.

[0028] The thickness of the non-foamed layer is not particularly limited and can be appropriately set as necessary. The thickness of the non-foamed layer is usually 0.1 to 50%, preferably 0.1 to 20%, of the total thickness of the laminated sheet. If the thickness of the non-foamed layer is within the above range, a high corrugation suppression effect can be obtained even under conditions where corrugation is likely to become significant during production, for example, when the laminated sheet is thick or when a large amount of foaming material is introduced, and since the degree of suppression of bubble growth in the foamed layer is low, a high expansion ratio of the foamed layer can be achieved and the light weight of the sheet can be maintained, which is preferable. In addition, when the non-foamed layer is two or more layers, the total thickness of each non-foamed layer may be within the above range.

[0029] In the laminate sheet, the non-foamed layer may be provided on any surface of the foamed layer. For example, the non-foamed layer may be provided on the outer surface of the foamed layer. This is preferable because the appearance of the sheet and the molded product is excellent. In this case, the non-foamed layer may be laminated directly on the foamed layer, or may be laminated on the foamed layer via another layer.

[0030] The layer structure of the laminate sheet is not particularly limited as long as it includes the foamed layer and the non-foamed layer. The laminate sheet may be composed of only the foamed layer and the non-foamed layer, or may further include other layers as necessary. The foamed layer may be a single layer, or may have a multi-layer structure in which two or more layers having different compositions or physical properties are laminated. Similarly, the non-foamed layer may be a single layer, or may have a multi-layer structure in which two or more layers having different compositions or physical properties are laminated.

[0031] Specific examples of the layer structure of the laminated sheet include an embodiment in which the foamed layer is present between the non-foamed layers (sandwich structure). This embodiment is preferable because the appearance and strength of the sheet and molded product are excellent. In the sandwich structure, both non-foamed layers may be directly laminated to the foamed layer, or one or both of the non-foamed layers may be laminated to the foamed layer via another layer. In the sandwich structure, at least one of the non-foamed layers may have a multi-layer structure of two or more layers.

[0032] The laminate sheet may contain other components as necessary within a range that does not significantly impair moldability. Specific examples of the other components include additives used in known resin sheets, such as flame retardants, ultraviolet absorbers, fluorescent whitening agents, antistatic agents, antifogging agents, lubricants, antiblocking agents, flow improvers, plasticizers, dispersants, and antibacterial agents. The other components may be contained in either the foamed layer or the non-foamed layer, or in both.

[0033] In conventional laminate sheets, organic or inorganic fillers have been used to improve physical properties such as impact resistance or heat resistance. The laminate sheet may or may not contain such fillers, particularly inorganic fillers. It is preferable for molded products such as food and beverage containers to be lightweight, and by not containing a filler, the weight of the laminate sheet and molded products can be reduced, which is preferable. Note that "containing no filler" includes not only an embodiment in which no filler is contained at all, but also an embodiment in which an amount of filler that does not substantially affect the weight of the laminate sheet is contained, for example, an embodiment in which the filler is contained in an amount of 0.1% by weight or less, preferably 0.05% by weight or less, and more preferably 0.01% by weight or less, based on 100% by weight of the laminate sheet.

[0034] Specific examples of organic fillers include PMMA beads, cellulose fibers, polyamide fibers, aramid fibers, polyester fibers, rice husks, wood flour, soybean pulp, tapioca powder, rice flour, and kenaf fibers. Specific examples of inorganic fillers include talc, calcium carbonate, silica, diatomaceous earth, alumina, titanium oxide, magnesium oxide, aluminum hydroxide, magnesium hydroxide, calcium silicate, glass beads, bentonite, glass flakes, glass fibers, carbon fibers, aluminum powder, molybdenum sulfide, boron fibers, potassium titanate, calcium titanate, hydrotalcite, carbon fibers, pumice powder, mica, calcium phosphate, and aluminum phosphate.

[0035] The specific shape of the laminate sheet is not particularly limited. The specific shape of the resin sheet can be appropriately determined as needed. Therefore, the term "sheet" also includes a film-like shape. The thickness of the sheet can be, for example, 0.1 to 3 mm, or 0.5 to 2 mm.

[0036] There is no particular limitation on the specific use of the laminate sheet, but as described later, the laminate sheet can be used to obtain molded products such as containers by various molding methods.

[0037] The laminate sheet is not limited in its manufacturing method as long as the foamed layer and the non-foamed layer can be laminated. The laminate sheet can be manufactured by a general lamination molding method such as co-extrusion, injection molding, and hot molding. In the co-extrusion method, any single-screw extruder and twin-screw extruder can be used. In the co-extrusion method, there is no specific limitation as long as the foamed layer and the non-foamed layer are laminated in a molten state just before being extruded from a die. Specific examples of the co-extrusion method include a multi-manifold method in which the raw materials of the foamed layer and the non-foamed layer are melt-kneaded in an extruder and then laminated in a die, and a feed block method (combining adapter method) in which the foamed layer and the non-foamed layer are laminated just before being flowed into a die. The die can be any of a T-type die, a coat hanger type, and an annular die. In the co-extrusion method, the foamed resin laminate sheet extruded from the die is cooled and solidified by a known method, such as a polishing roll, an air knife, or a mandrel. Thereafter, the sheet is wound up by a winding machine or cut to a predetermined size by a cutting machine.

[0038] In the production of the laminated sheet, post-treatment may be performed after cooling and solidifying as necessary. There is no particular restriction on the post-treatment. Specific examples of the post-treatment include a polar group-imparting treatment process such as corona treatment, flame treatment, frame treatment, and plasma treatment, a coating process using an anti-fog agent or an antistatic agent using a coater roll, film lamination, printing, and painting. In particular, the film lamination may be performed by a pre-thermoforming lamination method in which the film is laminated before secondary molding, a hot lamination method in which the film is laminated when cooled during foamed resin laminate sheet molding, or a method in which the foamed resin laminate sheet is cooled once and then heated again with a heated roll or the like and laminated, but any of the known methods can be used for lamination. The type of film to be laminated is not particularly limited, and may include a CPP film, a printed film thereof, a film laminated with EVOH, etc., etc., but it is preferable to use a film having a polyolefin resin arranged on the lamination surface, which is easily adhered to polyolefins, or a film coated with an ink, adhesive, etc., in which chlorinated polypropylene or low molecular weight polyolefin is mixed.

[0039] (2) Molded articles and containers The molded product can be obtained by molding the laminated sheet. The molding can usually be thermoforming. The specific method of the thermoforming is not particularly limited, and known thermoforming methods such as hot plate molding, vacuum molding, pressure molding, vacuum pressure molding, double-sided vacuum molding, plug molding, or press molding can be used. The conditions of the thermoforming are also not particularly limited. The molding conditions can be appropriately determined as needed.

[0040] There are no particular limitations on the shape, dimensions, and specific uses of the molded article. Uses of the molded article include containers such as packaging containers, for example, food and beverage packaging containers. The term "container" includes not only the entire container, but also a part of the container. For example, the term "container" includes not only the main body of the container, but also the lid of the container. EXAMPLES

[0041] The present invention will be specifically described below with reference to examples. Note that the present invention is not limited to the embodiments shown in the examples. The embodiments of the present invention can be modified in various ways within the scope of the present invention depending on the purpose, application, etc.

[0042] 1. Manufacturing of foamed resin laminate sheets for thermoforming The following components were used as raw materials. <High density polyethylene (HDPE)> "SHC7260" (Braskem; MFR 7.2g / 10min) <Low Density Polyethylene (LDPE)> "SBC818" (Braskem; MFR 8.3g / 10min) <Linear low density polyethylene (LLDPE)> "SLH218" (Braskem; MFR 2.3g / 10min) <Block polypropylene (BPP) (I)> "FTS6200" (Japan Polypropylene; MFR 2.5g / 10min) <Block polypropylene (BPP) (II)> "BC3BRFA" (Japan Polypropylene; MFR 12g / 10min) <Homopolypropylene (HPP)> "SA06GA" (Japan Polypropylene; MFR 60g / 10min) <Foaming nucleating agent> "Fine Cell Master PO410K" (manufactured by Dainichi Seika Color & Chemicals Co., Ltd.) <Foaming agent> Carbon dioxide

[0043] To form the foamed layer and the non-foamed intermediate and surface layers, the above-mentioned raw materials were dry-blended in the ratios shown in Tables 1 to 3 and fed to each extruder. The raw materials dry-blended in each extruder were heated and melted, and the melt-mixed resins were co-extruded to obtain laminated sheets (thickness: 1.5 mm, basis weight: 390 g / m2) of the examples and comparative examples. 2 A laminated structure: surface layer / intermediate layer / foamed layer / intermediate layer / surface layer) was obtained. In the extruder for the foamed layer, melt kneading and plasticization were performed in the first half of the extruder, and then carbon dioxide gas (foaming agent) was injected and kneaded in the middle part of the extruder. The amount of carbon dioxide gas injected for the foamed layer was adjusted so that the thickness of the laminated sheet was 1.5 mm.

[0044] [Table 1]

[0045] [Table 2]

[0046] [Table 3]

[0047] In Tables 1 to 3, the blending amount of the polyolefin resin is expressed in weight %, and the blending amount of the foaming nucleating agent is expressed in parts by weight relative to the total amount of the polyolefin resin.

[0048] The laminate sheets of the examples and comparative examples were subjected to performance evaluation and measurement by the methods described below. The results are shown in Tables 1 to 3. In Tables 1 to 3, "-" means that the laminate sheet was not obtained, so the performance evaluation and measurement were not performed.

[0049] (1) Foaming ratio (times) A test piece was cut out from the laminated sheet, and the weight (g) of the test piece was calculated based on the volume (cm 3 The apparent density of the laminated sheet was calculated by dividing the density of the polypropylene resin (0.91 g / cm 3 The expansion ratio was calculated by dividing the apparent density of the laminated sheet by the apparent density of the laminated sheet.

[0050] (2) Open cell ratio (%) Five samples measuring 2 cm x 2 cm were randomly cut from the laminated sheet, and their weights (weight before immersion) were measured. The samples were then immersed in water and left for 3 minutes under a vacuum of 0.09 MPa or less, and then removed. The moisture on the surface and cross section was then thoroughly wiped off, and the weights of the samples (weight after immersion) were measured. The open cell ratio (%) was then calculated using the following formula. F = {(Mm) / [m×(f-1)] / S 0}×100 F: open cell ratio (%), M: weight after immersion (g), m: weight before immersion (g), f: expansion ratio, S 0 Specific gravity of the solid components of the laminated sheet

[0051] (3)Basic weight (g) The laminated sheet was cut into a size of 100 mm x 100 mm, and its weight (g) was measured using an analytical balance. The measured weight was multiplied by 100 to obtain the basis weight.

[0052] (4) Sheet formability 1.5mm, 390g / m 2 The laminated sheet obtained had an open cell ratio of 20% or less and was evaluated as "good". 2 When no laminate sheet of the above was obtained, the result was evaluated as "x".

[0053] (5) Seat appearance The surface of each laminate sheet in the Examples and Comparative Examples was visually observed, and those with good overall appearance were rated as "◯", and those with defective appearance either partially or entirely were rated as "Δ".

[0054] 2. Manufacturing of molded products Using a vacuum and pressure forming device (manufactured by Asano Laboratories), the laminated sheets of the Examples and Comparative Examples were vacuum-pressure formed under conditions of an upper heater of 325°C and a lower heater of 290°C to produce rectangular containers (upper part: 12 mm x 12 mm, opening: 120 mmφ, bottom: 80 mmφ, depth: 65 mm) of the Examples and Comparative Examples. Performance evaluations and measurements were carried out for the containers of the Examples and Comparative Examples by the methods described below. The results are shown in Tables 1 to 3. In Tables 1 to 3, "-" indicates that performance evaluations and measurements were not carried out because a laminated sheet could not be obtained or a container could not be produced by molding (Comparative Examples 2, 4, and 5).

[0055] (1) Container formability When manufacturing containers using a vacuum and pressure molding device, those that could be molded without any problems or could be molded by adjusting the molding conditions were rated as "Good." On the other hand, those that could not manufacture containers even after adjusting the molding conditions were rated as "Poor."

[0056] (2) Container waist strength (g) Using a "Tensilon Universal Testing Machine RTC-1310A" (manufactured by Orientec Co., Ltd.), the container was held upright in the short direction and the entire long side wall of the container was compressed 18 mm in the width direction (compression speed: 400 mm / min). The maximum stress at this time was recorded as the stiffness.

[0057] (3) Buckling strength (kg) The container body was placed face down on an "Autograph AGS-X" (manufactured by Shimadzu Corporation), an acrylic plate was placed over the entire bottom surface of the container, and the centre was compressed at a speed of 10 mm / min to measure the strength at which the container buckled.

[0058] (4) Fitting strength (g) A lid (inner fitting lid: diameter: 120 mmφ, depth: 17 mm) obtained by separately thermoforming was placed on the container body, and the pressing strength was measured using a spring balance to obtain the fitting strength.

[0059] 3.Results As shown in Table 1, the laminated sheets of Examples 1 to 9, which use a low-density PE resin as the PE resin for the non-foamed intermediate layer, can be foamed to a thickness of 1.5 mm, and have a low open cell ratio of 12% or less, and are excellent in sheet moldability. Furthermore, the laminated sheets of Examples 1 to 9 have almost no blisters or flow marks, and are excellent in appearance. Furthermore, the containers obtained from the laminated sheets of Examples 1 to 9 have high waist strength, buckling strength, and fitting strength, and are excellent in rigidity and container moldability.

[0060] On the other hand, in Comparative Examples 1 to 9 in which a high density PE resin was used as the PE resin for the intermediate layer, which is a non-foamed layer, when the sheet thickness was about 1.3 mm, the open cell ratio became large, and a sheet with a thickness of 1.5 mm could not be formed (Comparative Examples 3, 6 to 9). Even if a sheet was formed, the open cell ratio was 30% or more, so the sheet moldability and container moldability were poor, and a container could not be obtained by molding. Similarly, in Comparative Examples 11, 12, and 14 to 18 in which a linear low density PE resin was used as the PE resin for the intermediate layer, which is a non-foamed layer, the open cell ratio became large, and a sheet with a thickness of 1.5 mm could not be formed. Among the Comparative Examples in which a linear low density PE resin was used, the laminated sheets of Comparative Examples 10 and 13 had a low open cell ratio and were excellent in the rigidity of the container, but the appearance of the sheet was not sufficient compared to the Examples, because the occurrence of blisters or flow marks was observed on the appearance of the sheet.

Claims

1. The laminate includes a foamed layer and a non-foamed layer, The foamed layer contains a first block polypropylene resin and a homopolypropylene resin, and the non-foamed layer contains a second block polypropylene resin and a low-density polyethylene resin, The non-foamed layers are laminated on both sides of the foamed layer, The non-foamed layer does not contain an antistatic agent, When the total amount of the resin components in the foam layer is taken as 100% by weight, the content of the first block polypropylene resin is 50 to 70% by weight, and the content of the homopolypropylene resin is 50 to 30% by weight, A thermoforming foamed resin laminate sheet mainly composed of a polypropylene-based resin, characterized in that, when the entire resin components in the non-foamed layer are taken as 100% by weight, the content of the second block polypropylene resin is 70 to 90% by weight, and the content of the low-density polyethylene-based resin is 10 to 30% by weight.

2. The laminate sheet according to claim 1 , wherein the low-density polyethylene resin is a plant-derived low-density polyethylene resin.

3. 3. The laminate sheet according to claim 1, wherein the first block polypropylene resin has an MFR value of 1 to 6 g / 10 min, the second block polypropylene has an MFR value of 8 to 20 g / 10 min, the homopolypropylene resin has an MFR value of 50 to 70 g / 10 min, and the low-density polyethylene resin has an MFR value of 3 to 15 g / 10 min.

4. 4. The laminate sheet according to claim 1, wherein the open cell ratio is 25% or less.

5. A molded article obtained by molding the laminate sheet according to any one of claims 1 to 4.

6. A container obtained by molding the laminate sheet according to any one of claims 1 to 4.

Images