Multi-layer sheet

Abstract

The present invention provides a multi-layer sheet that has abrasion resistance equal to or greater than that of conventional sheets and also has excellent formability. [Solution] A multilayer sheet comprising an abrasion-resistant layer (A) containing a metallocene-based linear low-density polyethylene (a) and an olefin-based thermoplastic elastomer (b) containing an olefin-based rubber and an olefin-based resin as main components, wherein the sum of the weights of (a) and (b) is 50% by weight or more, with the weight of the abrasion-resistant layer (A) being 100% by weight, and the weight ratio of (a) to (b) is 80-99:20-1.

Description

[Technical field]

[0001] The present invention relates to a multilayer sheet. [Background technology]

[0002] For example, in manufacturing sites such as factories, trays, boxes, partitions, pallets, and other transport components are widely used to transport workpieces. As the workpieces move and vibrate within the transport components during transport, the surfaces of the transport components that the workpieces come into contact with may peel off, generating dust and soiling the workpieces. For this reason, transport components are required to be wear-resistant, and polyolefins, which have excellent wear resistance, have traditionally been widely used as materials for transport components.

[0003] Patent Document 1 describes a multilayer sheet provided with a surface layer made of a thermoplastic elastomer such as a polyolefin elastomer or a composition thereof. Patent Documents 2 and 3 describe laminated sheets containing 60% by weight or more of a polyolefin-based elastomer in the surface layer. Patent Document 4 describes a multilayer film including a skin layer made of a blend of low-density polyethylene and an ethylene-based elastomer having a density of less than 0.90 g / cc, the content of the low-density polyethylene being 20% ​​by weight or less based on the total weight of the skin layer. It is described that the low-density polyethylene excludes linear low-density polyethylene. Patent Document 5 describes an oriented polypropylene film having a skin layer made of a polypropylene-based resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-276354 A [Patent Document 2] JP 2011-737 A [Patent Document 3] JP 2014-4838 A [Patent Document 4] Special Publication No. 2019-501038 [Patent Document 5] JP 2018-65267 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the above-mentioned conventional techniques have room for further improvement in terms of achieving both wear resistance and moldability.

[0006] An object of one aspect of the present invention is to provide a multilayer sheet having abrasion resistance equal to or greater than that of conventional multilayer sheets and excellent moldability. [Means for solving the problem]

[0007] The present inventors have conducted extensive research to solve the above problems. As a result, they have found that a multilayer sheet having abrasion resistance equal to or higher than that of conventional products and excellent moldability can be obtained by using a metallocene linear low density polyethylene and an olefinic thermoplastic elastomer containing an olefinic rubber and an olefinic resin as main components in a specific blending ratio of 80-99:20-1, and have arrived at the present invention. They have also confirmed that the use of these two components in the above blending ratio improves abrasion resistance compared to the use of only one of the components alone.

[0008] Factors for improving wear resistance include (i) increasing the hardness of the material, (ii) adopting a surface that is less susceptible to frictional forces, and (iii) stress-relaxing the frictional forces within the material. For conveying members that require wear resistance, it is known to use olefin-based thermoplastic elastomers (TPO), as described in the above patent documents. Compared with thermoplastic polyurethane elastomers (TPU), TPO has excellent vacuum formability even in the case of shapes that are difficult to form, such as deep-draw shapes. Therefore, by using TPO, a conveying member with excellent formability can be obtained. Furthermore, TPO is not easily affected by surfactants and oil-based greases. Therefore, it is believed that by using TPO, the performance balance of the conveying member will be improved and its versatility will be increased.

[0009] On the other hand, the addition of TPO reduces the material hardness. There was room for improvement in order to realize a multilayer sheet having abrasion resistance equal to or greater than that of conventional products and excellent moldability. As a result of the studies conducted by the present inventors, it was found that, among polyethylene resins known to have excellent abrasion resistance, metallocene-based linear low-density polyethylene is particularly excellent in abrasion resistance. Furthermore, it was found that the abrasion resistance can be improved and the problem can be solved by using metallocene-based linear low-density polyethylene and TPO in the above-mentioned specific blending ratio. Furthermore, it was also found that the problem can be solved by using a specific type of TPO in consideration of the compatibility (miscibility, etc.) with metallocene-based linear low-density polyethylene. The present invention includes the following configurations.

[0010] A metallocene-based linear low-density polyethylene; An abrasion-resistant layer (A) including an olefin-based thermoplastic elastomer containing an olefin-based rubber and an olefin-based resin as main components, the sum of the weights of the metallocene-based linear low-density polyethylene and the olefin-based thermoplastic elastomer is 50% by weight or more, with the weight of the abrasion-resistant layer (A) being 100% by weight; The weight ratio of the metallocene linear low density polyethylene to the olefin thermoplastic elastomer is 80-99:20-1. Effect of the Invention

[0011] According to one aspect of the present invention, it is possible to provide a multilayer sheet having abrasion resistance equal to or greater than that of conventional multilayer sheets and excellent moldability. [Brief description of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view showing a schematic layer structure of a multilayer sheet according to one embodiment of the present invention. [Diagram 2] 1 is a cross-sectional view showing a schematic layer structure of a multilayer sheet according to one embodiment of the present invention. [Diagram 3] 1 is a cross-sectional view showing a schematic layer structure of a multilayer sheet according to one embodiment of the present invention. [Figure 4] 1 is a cross-sectional view showing a schematic layer structure of a multilayer sheet according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] An embodiment of the present invention will be described below, but the present invention is not limited thereto. In this specification, unless otherwise specified, "A to B" representing a numerical range means "A or more and B or less."

[0014] [1. Multi-layer sheet] The multilayer sheet according to one embodiment of the present invention comprises a metallocene-based linear low density polyethylene, The abrasion-resistant layer (A) includes an olefin-based thermoplastic elastomer containing an olefin-based rubber and an olefin-based resin as main components.

[0015] The structure of the multilayer sheet is not particularly limited, but may include a base layer as described in detail below, or may have an abrasion-resistant layer (A) on one surface of the base layer (B), for example, a two-layer structure as shown in FIG. 1. Alternatively, it may have an abrasion-resistant layer (A) on both surfaces of the base layer (B), for example, a three-layer structure as shown in FIG. 2. The multilayer sheet may further include an adhesive layer (C) as described in detail below, or may have an abrasion-resistant layer (A) on one surface of the base layer (B) via the adhesive layer (C), for example, a three-layer structure as shown in FIG. 3. Alternatively, it may have an abrasion-resistant layer (A) on both surfaces of the base layer (B) via the adhesive layer (C), for example, a five-layer structure as shown in FIG. 4.

[0016] When the multilayer sheet does not include an adhesive layer, the ratio of each layer constituting the multilayer sheet is preferably 5 to 30% for the abrasion-resistant layer and 70 to 95% for the base layer, when the total thickness of the sheet is taken as 100%. On the other hand, when the multilayer sheet includes an adhesive layer, the ratio of each layer constituting the multilayer sheet is preferably 5 to 25% for the abrasion-resistant layer, 70 to 85% for the base layer, and 3 to 10% for the adhesive layer, when the total thickness of the sheet is taken as 100%.

[0017] <1.1. Wear-resistant layer> In the present specification, the abrasion-resistant layer (A) is at least one of the outermost layers of the multilayer sheet. For example, in the multilayer sheet shown in Figures 1 and 3, the abrasion-resistant layer is one outermost layer, and in the multilayer sheet shown in Figures 2 and 4, the abrasion-resistant layer is two outermost layers.

[0018] The abrasion-resistant layer (A) contains metallocene-based linear low-density polyethylene (also referred to as "m-LLDPE" in this specification). In this specification, metallocene-based linear low-density polyethylene refers to linear low-density polyethylene polymerized using a metallocene catalyst. As described above, metallocene-based linear low-density polyethylene has particularly high abrasion resistance among many polyethylene resins. Therefore, by using metallocene-based linear low-density polyethylene, the abrasion resistance of the obtained sheet is improved.

[0019] The melt mass flow rate (MFR) value of m-LLDPE, measured according to JIS K 7210-1 (2014) under conditions of a test temperature of 190°C and a load of 2.16 kg (21.2 N), is preferably 0.1 to 20 g / 10 min, more preferably 0.3 to 15 g / 10 min, and even more preferably 0.5 to 10 / 10 min. If the MFR value of m-LLDPE is within the above range, the formability and appearance of the resulting multilayer sheet are excellent. On the other hand, if the MFR value of m-LLDPE is too high, the adjustability of the material flow in the extrusion process is poor. Also, if the MFR value of m-LLDPE is too low, interface roughness and / or screw marks occur.

[0020] The abrasion-resistant layer (A) further contains an olefin-based thermoplastic elastomer (TPO) containing an olefin-based rubber and an olefin-based resin as main components. In this specification, the TPO containing an olefin-based rubber and an olefin-based resin as main components is also referred to as "TPO(I)". TPOs having specific conditions such as TPO(I) have better abrasion resistance than polyolefins such as polypropylene, and therefore the abrasion resistance of the resulting conveying member is thought to be improved.

[0021] "Containing olefin-based rubber and olefin-based resin as main components" means that the sum of the weights of the olefin-based rubber and olefin-based resin exceeds 50% by weight when the weight of TPO (I) is 100% by weight. The sum of the weights of the olefin-based rubber and olefin-based resin in TPO (I) is preferably 70% by weight or more, more preferably 90% by weight or more, and most preferably 99% by weight or more. In addition to the main components, examples of components contained in TPO (I) include softeners such as styrene-based elastomers and mineral oils.

[0022] TPO(I) has a sea-island structure including an island phase containing the olefin-based rubber and a sea phase containing the olefin-based resin. In TPO(I), the weight ratio of the olefin-based rubber to the olefin-based resin is not particularly limited. In consideration of compatibility with m-LLDPE, TPO(I) is preferably an ethylene-based thermoplastic elastomer.

[0023] As the olefin-based rubber, for example, one or more selected from the group consisting of ethylene-propylene-diene copolymer (EPDM), ethylene-propylene rubber (EPR), ethylene-octene copolymer, and the like can be used.

[0024] The olefin resin may be, for example, one or more selected from the group consisting of propylene resin, ethylene resin, other α-olefin resin, etc. Furthermore, a copolymer of various monomers such as a propylene-ethylene random copolymer may be used as the olefin resin. The other α-olefin resin is not particularly limited, but examples of the monomer include 1-butene and 1-hexene. As the TPO(I), two types of TPOs having different olefin resins may be used. For example, a TPO(I) in which the olefin resin is a propylene resin and a TPO(I) in which the olefin resin is an ethylene resin may be used in combination.

[0025] The TPO(I) preferably has a melt mass flow rate (MFR) value of 0.1 g / 10 min or more, measured according to JIS K 7210-1 (2014) at a test temperature of 230° C. and a load of 2.16 kg (21.2 N). The MFR value is more preferably 0.5 to 20 g / 10 min, and even more preferably 0.5 to 17 g / 10 min. Two types of TPO having different MFR values ​​within the above range may be used as the TPO(I). By using a TPO(I) having a low MFR value and a TPO(I) having a high MFR value in combination, it becomes easier to adjust the flow of the material in the extrusion process.

[0026] When two types of TPO(I) having different MFR values ​​are used as TPO(I), the weight ratio of TPO(I) having a lower MFR value:TPO(I) having a higher MFR value is preferably 30-100:70-0.

[0027] TPO(I) can be produced, for example, by mixing an olefinic rubber and an olefinic resin, and optionally a softener, an inorganic filler, etc., and / or an additive to obtain a mixture, and kneading the mixture in a molten state. If necessary, the obtained TPO(I) may contain components other than the olefinic rubber and the olefinic resin to the extent that the effects of the present invention are not impaired.

[0028] As the TPO (I), for example, an olefin-based thermoplastic elastomer obtained by the above-mentioned method or a commercially available product can be used.

[0029] The lower limit of the sum of the weights of m-LLDPE and TPO (I) is 50% by weight or more, preferably 60% by weight or more, more preferably 70% by weight or more, even more preferably 80% by weight or more, even more preferably 90% by weight or more, and particularly preferably 99.5% by weight or more, with the weight of the abrasion-resistant layer (A) being 100% by weight. The upper limit of the sum of the weights of m-LLDPE and TPO (I) is not particularly limited, and may be, for example, 100% by weight, 99.5% by weight, or 99.0% by weight, with the weight of the abrasion-resistant layer (A) being 100% by weight. That is, the abrasion-resistant layer (A) may contain only m-LLDPE and TPO (I), or may further contain additives in addition to m-LLDPE and TPO (I). If the sum of the weights of m-LLDPE and TPO (I) is within the above range, a multilayer sheet having excellent abrasion resistance and moldability can be obtained.

[0030] When the wear-resistant layer (A) further contains additives, examples of the additives include, but are not limited to, softeners (liquid paraffin), modifiers, lubricants (wax), etc. The additives can be used appropriately depending on the purpose such as adjusting the hardness of the wear-resistant layer, adjusting the balance between moldability and appearance, etc. In addition, an anti-adhesive agent such as silicone can be added to prevent tack. Furthermore, an antistatic agent (low molecular weight antistatic agent, polymeric antistatic agent, etc.) and a conductive material (carbon black, carbon nanotubes, etc.) can be added to prevent the generation of static electricity that causes dust adhesion. Note that, from the viewpoint of preventing a decrease in wear resistance, it is preferable to add these additives in small amounts. Therefore, it is preferable to select additives that can express their function with the addition of a small amount. For example, as the antistatic agent, a low molecular weight antistatic agent that bleeds to the sheet surface and expresses its function is preferable. As the conductive material, carbon nanotubes are preferable.

[0031] The weight ratio of m-LLDPE to TPO (I) in the abrasion-resistant layer (A) is 80-99:20-1, more preferably 85-97:15-3, more preferably 85-95:15-5, and even more preferably 90-95:10-5. When the weight ratio of m-LLDPE to TPO (I) is within the above range, the resulting multilayer sheet can better balance abrasion resistance and moldability.

[0032] The abrasion-resistant layer (A) preferably has a durometer D hardness of D35 to D65 measured according to JIS K 6253-3 (2012) from the viewpoint of abrasion resistance. The upper limit of the durometer D hardness is more preferably D58 or less. The lower limit of the durometer D hardness is more preferably D48 or more, and even more preferably D54 or more, from the viewpoint of making tackiness less likely to occur. The durometer D hardness can be measured using a GS 720N (manufactured by Techlock).

[0033] The abrasion-resistant layer (A) preferably has a melt mass flow rate (MFR) value of 0.5 g / 10 min or more, more preferably 1 g / 10 min or more, measured according to JIS K 7210-1 (2014) under the conditions of a test temperature of 230 ° C and a load of 2.16 kg (21.2 N). The upper limit of the MFR value is preferably 10 g / 10 min or less, more preferably 6 g / 10 min or less. The MFR value of the abrasion-resistant layer (A) can be adjusted to a desired value, for example, by adjusting the MFR value of TPO (I) used in combination with m-LLDPE, or by adjusting the weight ratio of m-LLDPE to TPO (I). The MFR value of the abrasion-resistant layer (A) can also be adjusted by adding a lubricant, softener, etc. Furthermore, the MFR value of the abrasion-resistant layer (A) may be lowered by adding an additive with a lower MFR value. However, care must be taken when adding additives to adjust the MFR value, as this may result in a decrease in performance such as wear resistance.

[0034] If the MFR value of the abrasion-resistant layer (A) is within the above range, the moldability and appearance of the resulting multilayer sheet are excellent. On the other hand, if the MFR value of the abrasion-resistant layer (A) is too high, the adjustability of the flow of the material in the extrusion process is poor. If the MFR value of the abrasion-resistant layer (A) is too low, the interface roughness and / or screw marks will occur. In this specification, the term "screw marks" refers to patterns such as traces of resin flow that appear on the surface of the resulting multilayer sheet when a screw is used.

[0035] By setting the MFR value of the abrasion-resistant layer (A) within the above range, the appearance of the sheet surface is good and uniform extrusion in the width direction is possible, and extrusion under an overload state is avoided, making it possible to more effectively prevent drawdown.

[0036] <1.2. Base material layer> The multilayer sheet according to one embodiment of the present invention may further comprise a base layer (B) containing polypropylene (PP) or polystyrene (PS) as a main component. "Containing polypropylene or polystyrene as a main component" means that the amount of polypropylene or polystyrene is more than 50% by weight when the weight of the base layer (B) is taken as 100% by weight. The proportion of polypropylene or polystyrene in the base layer (B) is more preferably 70% by weight or more, and even more preferably 80% by weight or more. Moreover, the proportion is preferably 90% by weight or more, and may be 100% by weight.

[0037] When the base layer (B) contains PP as a main component, the base layer (B) may further contain polyethylene (PE). In this case, the weight ratio of PP and PE contained in the base layer (B) may be 70-95:30-5. By blending PE in the base layer (B), the adhesion with the PE-based abrasion-resistant layer (A) containing m-LLDPE is improved, and the interlayer strength between the abrasion-resistant layer (A) and the base layer (B) is increased.

[0038] When the base layer (B) contains PS as a main component, all or a part of the PS is preferably high impact polystyrene (HIPS).

[0039] The base layer (B) may further contain a compatibilizer, a filler such as talc, a styrene-based thermoplastic elastomer (TPS) and the like in addition to PP or PS. When the base layer (B) contains TPS, when the resulting multilayer sheet has an adhesive layer (C), the adhesion between the adhesive layer (C) and the base layer (B) is further improved. As the TPS, a styrene-butadiene-styrene block copolymer (SBS) is preferable. The addition of SBS has the effect of improving impact resistance.

[0040] The base layer (B) can be prepared, for example, by kneading, granulating, and mixing PP or PS with the above-mentioned compatibilizer, etc. The base layer (B) may contain inorganic filler and / or reinforcing material, etc., in addition to PP or PS. The addition of these can improve the rigidity of the base layer (B).

[0041] Examples of reinforcing materials that can be added to improve the rigidity of the base layer (B) include fibrous reinforcing materials, plate-shaped reinforcing materials, and granular reinforcing materials. Examples of fibrous reinforcing materials include glass fiber and carbon fiber. Examples of plate-shaped reinforcing materials include mica, talc, clay, and glass flakes. Examples of granular reinforcing materials include metal oxides such as silica, calcium carbonate, and calcium silicate, carbonates, sulfates, and powders such as glass beads, and carbon black. In addition, recycled materials may be used as the resin of the base layer.

[0042] The base layer (B) may also contain other amorphous resins, such as polyvinyl chloride (PVC), acrylonitrile styrene (AS), acrylonitrile-butadiene-styrene copolymer (ABS resin), polymethyl methacrylate (PMMA), polycarbonate (PC), etc.

[0043] <1.3.Adhesive layer> When the base layer (B) contains PS as a main component, the multilayer sheet may further include an adhesive layer (C) that bonds the abrasion-resistant layer (A) and the base layer (B) in order to improve the adhesion between the m-LLDPE and TPO (I) contained in the abrasion-resistant layer (A) and the PS contained in the base layer (B). The adhesive layer (C) contains polyethylene (PE), polystyrene (PS), and a styrene-based thermoplastic elastomer (TPS). TPS is highly compatible with both the m-LLDPE and TPO (I) contained in the abrasion-resistant layer (A) and the PS contained in the base layer (B). By including, in addition to TPS, PE contained as m-LLDPE in the abrasion-resistant layer (A) and PS that may be contained in the base layer (B) in the adhesive layer (C), the adhesiveness is improved compared to when TPS is included alone. In addition, a uniform layer can be obtained during extrusion molding. That is, by including PE, PS, and TPS in the adhesive layer (C), better adhesion and moldability can be obtained.

[0044] The polyethylene is preferably linear low density polyethylene (LLDPE) or low density polyethylene (LDPE). The polystyrene is preferably all or partly high impact polystyrene (HIPS). The TPS is not particularly limited, and examples thereof include styrene-butadiene-styrene block copolymer (SBS) and styrene-isoprene-styrene block copolymer (SIS). Furthermore, the TPS is preferably all or partly a styrene-butadiene thermoplastic elastomer, and more preferably a hydrogenated styrene-butadiene thermoplastic elastomer. Examples of hydrogenated styrene-butadiene thermoplastic elastomers include styrene-butadiene-butylene-styrene block copolymer (SBBS) and styrene-ethylene-butylene-styrene block copolymer (SEBS). From the viewpoint of compatibility with PE and PS, the TPS is preferably a styrene-ethylene-butylene-styrene block copolymer (SEBS).

[0045] In the adhesive layer (C), the lower limit of the PE content is preferably 5% by weight or more, more preferably 15% by weight or more, and even more preferably 20% by weight or more, based on the weight of the adhesive layer (C) being 100% by weight. In the adhesive layer (C), the upper limit of the PE content is preferably 70% by weight or less, more preferably 50% by weight or less, and even more preferably 40% by weight or less, based on the weight of the adhesive layer (C) being 100% by weight.

[0046] In the adhesive layer (C), the lower limit of the PS content is preferably 25% by weight or more, more preferably 40% by weight or more, and even more preferably 50% by weight or more, based on the weight of the adhesive layer (C) being 100% by weight. In the adhesive layer (C), the upper limit of the PS content is preferably 92% by weight or less, more preferably 80% by weight or less, and even more preferably 70% by weight or less, based on the weight of the adhesive layer (C) being 100% by weight.

[0047] In the adhesive layer (C), the lower limit of the TPS content is preferably 3% by weight or more, more preferably 4% by weight or more, and even more preferably 6% by weight or more, based on the weight of the adhesive layer (C) being 100% by weight. In the adhesive layer (C), the upper limit of the TPS content is preferably 40% by weight or less, more preferably 20% by weight or less, and even more preferably 15% by weight or less, based on the weight of the adhesive layer (C) being 100% by weight.

[0048] The material for preparing the adhesive layer (C) can be prepared, for example, by kneading, granulating, and mixing PE, PS, and TPS. The adhesive layer (C) may contain other components to the extent that the effect of the present invention is not impaired.

[0049] 2. Manufacturing method of multilayer sheet The method for producing a multilayer sheet according to one embodiment of the present invention is not particularly limited, but examples of the coextrusion multilayer T-die include a feed block system, a multi-manifold system, a multi-throttle die system, etc. The feed block system is inexpensive, has a relatively simple mold structure, and is easy to maintain, so it has excellent production efficiency, but is inferior in terms of control over the thickness of each layer and the flow in the width direction, etc., because the resin materials of each layer join together in the feed block.

[0050] On the other hand, the multilayer sheet of one embodiment of the present invention has the configuration already described and, as mentioned above, has the advantage that sufficiently uniform multilayer coextrusion can be easily achieved even with the inexpensive feed block method.

[0051] The manufacturing method can be exemplified by the following method. That is, first, the necessary materials are kneaded, granulated, and mixed to prepare the materials for preparing the abrasion-resistant layer, the materials for preparing the base layer, and, if necessary, the materials for preparing the adhesive layer. Next, each of the prepared materials is fed to a different extruder, and the set temperature conditions of each extruder are gradually increased from about 130°C to about 180°C to 230°C toward the die tip, and then kneaded, melted, and homogenized and extruded. Next, the extruded materials for each layer are merged in a feed block provided immediately before the T-die under a temperature condition of 190°C to 220°C, and then fed to the T-die, and the width is expanded by a single manifold in the T-die to obtain a multilayer sheet in which the base layer and the abrasion-resistant layer are bonded together, or a multilayer sheet in which the base layer and the abrasion-resistant layer are bonded together by an adhesive layer.

[0052] [3.Applications] The multilayer sheet according to one embodiment of the present invention can be used, for example, as a tray forming sheet, a transport case and its partition plate, or a sheet for transport. One embodiment of the present invention also includes a sheet for forming a tray or a sheet for transport having the above-mentioned multilayer sheet. The multilayer sheet has the above-mentioned configuration, and therefore the protective plate for covering the frame of the tray forming sheet, transport case, partition plate, or transport rack, has excellent multilayer co-extrusion properties, moldability, and adhesiveness, and has excellent abrasion resistance. Therefore, it is easy to form into a desired shape by a vacuum forming method, a pressure forming method, or cutting processing, and can also show excellent resistance to contact with metals, etc. Therefore, the multilayer sheet can be suitably used for manufacturing transport members such as trays, boxes, partition plates, metal or plastic racks, pallets, etc. for transporting heavy objects such as products and parts, which are used at manufacturing sites such as factories.

[0053] [4. Summary] The present invention includes the following aspects. <1> A metallocene-based linear low-density polyethylene; An abrasion-resistant layer (A) including an olefin-based thermoplastic elastomer containing an olefin-based rubber and an olefin-based resin as main components, the sum of the weights of the metallocene-based linear low-density polyethylene and the olefin-based thermoplastic elastomer is 50% by weight or more, with the weight of the abrasion-resistant layer (A) being 100% by weight; The weight ratio of the metallocene linear low density polyethylene to the olefin thermoplastic elastomer is 80-99:20-1. <2> Further comprising a base layer (B) containing polypropylene or polystyrene as a main component; <1> The multilayer sheet according to claim 1. <3> When the base layer (B) contains polystyrene as a main component, the base layer (B) further includes an adhesive layer (C) that adheres the abrasion-resistant layer (A) and the base layer (B), The adhesive layer (C) contains polyethylene, polystyrene, and a styrene-based thermoplastic elastomer, With the weight of the adhesive layer (C) being 100% by weight, the content of the polyethylene is 5% by weight or more and 70% by weight or less, the content of the polystyrene is 25% by weight or more and 92% by weight or less, and the content of the styrene-based thermoplastic elastomer is 3% by weight or more and 40% by weight or less. <2> The multilayer sheet according to claim 1. <4> The abrasion-resistant layer (A) has a durometer D hardness of D35 to D65 measured in accordance with JIS K 6253-3 (2012). <1> ~ <3> 13. The multilayer sheet according to claim 12 . <5> The abrasion-resistant layer (A) has a melt mass-flow rate value of 0.5 g / 10 min or more, measured according to JIS K 7210-1 (2014) at a test temperature of 230° C. and a load of 2.16 kg (21.2 N); <1> ~ <4> 13. The multilayer sheet according to claim 12 . <6> <1> ~ <5> A sheet for forming or transporting a tray, comprising the multilayer sheet according to any one of claims 1 to 5. EXAMPLES

[0054] Specific examples of the present invention are described below, but the present invention is not limited to the following examples.

[0055] Multilayer sheets were produced using the constituent materials listed below in the combinations shown in Tables 1 and 2, and were evaluated by the following evaluation methods.

[0056] Materials used in the Examples and Comparative Examples (wear-resistant layer) <m-lldpe> · m-LLDPE(1) (MFR value 0.8 g / 10 min (190 °C, 21.2 N)): Sumikasen E manufactured by Sumitomo Chemical, Evolue manufactured by Mitsui Chemicals, or Kernel manufactured by Japan Polyethylene · m-LLDPE(2) (MFR value 1.9 g / 10 min (190 °C, 21.2 N)): Sumikasen E manufactured by Sumitomo Chemical, Evolue manufactured by Mitsui Chemicals, Kernel manufactured by Japan Polyethylene, or Yumerit manufactured by Ube Maruzen Polyethylene · m-LLDPE(3) (MFR value 2.3 g / 10 min (190 °C, 21.2 N)): Sumikasen E manufactured by Sumitomo Chemical, Evolue manufactured by Mitsui Chemicals, Kernel manufactured by Japan Polyethylene, or Yumerit manufactured by Ube Maruzen Polyethylene Note that the m-LLDPE used had a density measured according to K7112 of 0.90 kg / m 3 ~0.93 kg / m 3 <TPO(I)> · Olefin-based thermoplastic elastomer (TPO(1)) containing olefin rubber and olefin resin as main components (MFR value 0.6 g / 10 min (230 °C, 21.2 N)): Esprec manufactured by Sumitomo Chemical, or Milastomer manufactured by Mitsui Chemicals · Olefin-based thermoplastic elastomer (TPO(3)) containing olefin rubber and olefin resin as main components (MFR value 17 g / 10 min (230 °C, 21.2 N)): Esprec manufactured by Sumitomo Chemical, or Milastomer manufactured by Mitsui Chemicals <TPO other than TPO(I)> · Olefin-based thermoplastic elastomer (TPO(2)) containing propylene-α olefin copolymer as the main component (MFR value 30 g / 10 min (230 °C, 21.2 N)): Toughselen manufactured by Sumitomo Chemical, Toughmer manufactured by Mitsui Chemicals, or Tefablock manufactured by Mitsubishi Chemical (Base layer) · Polypropylene (PP): Sun Allomer manufactured by Sun Allomer, Noblen manufactured by Sumitomo Chemical, Novatec manufactured by Japan Polypropylene, or Prime Polypro manufactured by Prime Polymer ​Polyethylene (PE): Sumikathene made by Sumitomo Chemical, Petrothene made by Tosoh, Novatec LD made by Nippon Polyethylene, or UBE Polyethylene made by Ube Maruzen Polyethylene Polystyrene (PS): PSJ-HIPS or PSJ-GPPS manufactured by PS Japan, or DickStyrene HIPS or DickStyrene GPPS manufactured by DIC (Adhesive layer) Polyethylene (PE): Sumikathene or Sumikathene E from Sumitomo Chemical, Evolue from Mitsui Chemicals, Novatec LD and Kernel from Nippon Polyethylene, or UBE Polyethylene or Yumerit from Ube Maruzen Polyethylene Polystyrene (PS): PSJ-HIPS or PSJ-GPPS manufactured by PS Japan, or DickStyrene HIPS or DickStyrene GPPS manufactured by DIC Styrene-ethylene-butylene-styrene block copolymer (SEBS): Tuftec or Tufprene made by Asahi Kasei, Septon or Hybra made by Kuraray, or TR made by ENEOS Materials [Method for producing multi-layer sheet] In the examples and comparative examples, first, the material for preparing the abrasion-resistant layer, the material for preparing the base layer, and, if necessary, the material for preparing the adhesive layer were each prepared by the following method. Next, each of the materials was fed to a different extruder (Hitachi Zosen, screw diameter φ100, and IKG, screw diameter φ65), and extruded by gradually increasing the temperature from about 130°C. The extruded materials for each layer were merged in a feed block provided just before the T-die and then fed to the T-die, and expanded in a single manifold in the T-die at about 190°C to 220°C to obtain a multilayer sheet.

[0057] In Example 1, m-LLDPE (1) and TPO (1) were blended in a weight ratio of 99:1, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing an abrasion-resistant layer. In this Example 1, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.7 g / 10 min (230°C), and the durometer D hardness was D55. Next, a material for preparing a base layer was prepared by blending 85% by weight of PP and 15% by weight of PE, with the weight of the base layer being 100% by weight.

[0058] In Example 2, m-LLDPE (1) and TPO (1) were blended in a weight ratio of 97:3, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 2, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.7 g / 10 min (230° C.), and the durometer D hardness was D55. For the base layer, a material for preparing the base layer was prepared in the same manner as in Example 1.

[0059] In Example 3, m-LLDPE (1) and TPO (1) were blended in a weight ratio of 95:5, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 3, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.6 g / 10 min (230° C.), and the durometer D hardness was D55. For the base layer, a material for preparing the base layer was prepared in the same manner as in Example 1.

[0060] In Example 4, m-LLDPE (1) and TPO (1) were blended in a weight ratio of 92:8, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 4, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.5 g / 10 min (230° C.), and the durometer D hardness was D56. For the base layer, the material for preparing the base layer was prepared in the same manner as in Example 1.

[0061] In Example 5, m-LLDPE (1) and TPO (1) were blended in a weight ratio of 90:10, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 5, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.4 g / 10 min (230° C.), and the durometer D hardness was D55. For the base layer, a material for preparing the base layer was prepared in the same manner as in Example 1.

[0062] In Example 6, m-LLDPE (1) and TPO (1) were blended in a weight ratio of 85:15, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 6, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.4 g / 10 min (230° C.), and the durometer D hardness was D55. For the base layer, the material for preparing the base layer was prepared in the same manner as in Example 1.

[0063] In Example 7, m-LLDPE (1) and TPO (1) were blended in a weight ratio of 80:20, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 7, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.3 g / 10 min (230° C.), and the durometer D hardness was D54. For the base layer, the material for preparing the base layer was prepared in the same manner as in Example 1.

[0064] In Example 8, m-LLDPE (2) and TPO (1) were blended in a weight ratio of 90:10, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 8, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 3.1 g / 10 min (230° C.), and the durometer D hardness was D58. For the base layer, a material for preparing the base layer was prepared in the same manner as in Example 1.

[0065] In Example 9, m-LLDPE (1) and TPO (3) were mixed in a weight ratio of 90:10, and other additives such as softeners, modifiers, lubricants, and anti-tack agents were mixed in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing the abrasion-resistant layer. In this Example 9, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 1.9 g / 10 min (230° C.), and the durometer D hardness was D57. For the base layer, the material for preparing the base layer was prepared in the same manner as in Example 1.

[0066] In Example 10, m-LLDPE (3) and TPO (3) were blended in a weight ratio of 92:8, and further, other additives such as softeners, modifiers, lubricants, and anti-tack agents were blended in an amount of 1% by weight, with the weight of the abrasion-resistant layer being 100% by weight, to prepare a material for preparing an abrasion-resistant layer. In this Example 10, the sum of the weights of m-LLDPE and TPO was 99% by weight, with the weight of the abrasion-resistant layer being 100% by weight. At this time, the MFR value of the abrasion-resistant layer was 5.1 g / 10 min (230°C), and the durometer D hardness was D58. PS was used as a material for preparing a base layer. In this Example, PS was used as the material for the base layer, and therefore the multilayer sheet has an adhesive layer between the abrasion-resistant layer and the base layer. The material for preparing the adhesive layer was prepared by blending 30 wt % of PE, 60 wt % of PS, and 10 wt % of SEBS, with the weight of the adhesive layer being 100 wt %.

[0067] In Comparative Example 1, the material for preparing the abrasion-resistant layer and the material for preparing the base material layer were prepared in the same manner as in Example 1, except that the weight ratio of m-LLDPE (1) and TPO (1) blended in the abrasion-resistant layer was changed to 70:30. The MFR value of the abrasion-resistant layer was 1.3 / 10min (230°C), and the durometer D hardness was D53.

[0068] In Comparative Example 2, the material for preparing the abrasion-resistant layer and the material for preparing the base material layer were prepared in the same manner as in Example 1, except that the weight ratio of m-LLDPE (1) and TPO (1) blended in the abrasion-resistant layer was changed to 50:50. The MFR value of the abrasion-resistant layer was 1.1 / 10 min (230°C), and the durometer D hardness was D50.

[0069] In Comparative Example 3, except that the olefin-based thermoplastic elastomer was not blended in the abrasion-resistant layer, the material for preparing the abrasion-resistant layer and the material for preparing the base layer were prepared in the same manner as in Example 1. The MFR value of the abrasion-resistant layer was 1.7 / 10min (230°C), and the durometer D hardness was D54.

[0070] In Comparative Example 4, except that no metallocene-based linear low-density polyethylene was blended into the abrasion-resistant layer, the material for preparing the abrasion-resistant layer and the material for preparing the base layer were prepared in the same manner as in Example 1. The MFR value of the abrasion-resistant layer was 0.6 / 10 min (230°C), and the durometer D hardness was D47.

[0071] In Comparative Example 5, TPO(2) was used as the olefin-based thermoplastic elastomer to be blended in the abrasion-resistant layer. Except for that, the materials for preparing the abrasion-resistant layer and the materials for preparing the base layer were prepared in the same manner as in Example 5.

[0072] In Comparative Example 6, the material for preparing the abrasion-resistant layer and the material for preparing the base material layer were prepared in the same manner as in Comparative Example 5, except that the weight ratio of m-LLDPE (1) and TPO (2) blended in the abrasion-resistant layer was changed to 70:30.

[0073] In Comparative Example 7, the material for preparing the abrasion-resistant layer and the material for preparing the base layer were prepared in the same manner as in Comparative Example 3, except that m-LLDPE (2) was used as the metallocene-based linear low-density polyethylene to be blended in the abrasion-resistant layer. In other words, no olefin-based thermoplastic elastomer was blended in the material for preparing the abrasion-resistant layer. The MFR value of the abrasion-resistant layer was 3.6 / 10min (230°C), and the durometer D hardness was D58.

[0074] In Comparative Example 8, the material for preparing the abrasion-resistant layer and the material for preparing the base layer were prepared in the same manner as in Comparative Example 3, except that m-LLDPE (3) was used as the metallocene-based linear low-density polyethylene to be blended in the abrasion-resistant layer. In other words, no olefin-based thermoplastic elastomer was blended in the material for preparing the abrasion-resistant layer. The MFR value of the abrasion-resistant layer was 4.5 / 10min (230°C), and the durometer D hardness was D58.

[0075] [Evaluation method] (Multi-layer co-extrusion) A comprehensive evaluation was conducted on lamination properties, adhesion to rolls, and load on the extruder when manufacturing multilayer sheets.

[0076] (Evaluation Criteria) a: There is no thickness variation in the width, length, or thickness directions, and the ratio of each layer is uniform in all directions. It is acceptable. b: There are many dimensional variations in each direction. The flow of each layer is uneven. Drawdown occurs. There are other defects and the product is rejected.

[0077] (Interlayer adhesion) After making cuts in the sheet, the wear-resistant layer was peeled off from the cut end surface to check whether peeling occurred.

[0078] (Evaluation Criteria) A: No peeling b: Peeling (Wear resistance) The abrasion resistance was evaluated by measuring the amount of abrasion loss and observing the state of peeling.

[0079] The amount of wear loss was measured using a Taber abrasion tester (model: AB-101) manufactured by Tester Sangyo Co., Ltd., under the conditions of load: 1000 g, abrasion wheel: CS-17, rotation speed: 1000 rpm, and test piece size: 100 mm x 100 mm. In addition, peeling of the abrasion-resistant layer was visually confirmed.

[0080] (Wear amount evaluation criteria) A: Wear loss is 15.0 mg or less b: Wear loss exceeds 15.0 mg The smaller the amount of abrasion loss, the better the abrasion resistance, and if the amount of abrasion loss is 15.0 mg or less, it can be said that the abrasion resistance is sufficient. In addition, the presence or absence of peeling of the abrasion-resistant layer (A) (not powdery abrasion material, but the outer layer peeled up) was visually confirmed and evaluated according to the following evaluation criteria.

[0081] (Evaluation Criteria) A: No peeling b: Peeling (Deep draw formability) The vacuum formability was evaluated by confirming the formability by forming into a deep-draw shape.

[0082] The multilayer sheets of the examples and comparative examples were vacuum molded using a deep-drawing mold, and the molding state of the corners of the mold was then confirmed. The dimensions of the mold were entrance diameter x depth = 64 mm x 115 mm. Vacuum molding was performed under the following conditions.

[0083] (Molding conditions) Heating temperature: 320~350℃ Heating time: 65 to 70 seconds Distance between heater and sheet: 90mm (Evaluation Criteria) a: The molded product was in good contact with the entire surface of the mold. Especially at the corners of the mold, the sheet stretched and adhered to the mold. b: At the corners of the mold, the wear-resistant layer does not stretch well, causing cracks or insufficient adhesion.

[0084] [Table 1]

[0085] [Table 2]

[0086] From Tables 1 and 2, it is clear that the amount of wear loss in the wear-resistant layer of the multilayer sheet obtained can be suppressed by setting the weight ratio of the metallocene linear low-density polyethylene in the wear-resistant layer to the olefinic thermoplastic elastomer containing an olefinic rubber and an olefinic resin as main components within a specific range. In other words, it was confirmed that the multilayer sheet according to one embodiment of the present invention can provide a multilayer sheet excellent in wear resistance and moldability. [Industrial Applicability]

[0087] An aspect of the present invention can be suitably used in the field of sheets used for transporting metal parts and / or heavy objects (trays, etc.). [Explanation of symbols]

[0088] A: Wear-resistant layer B: Base material layer C: Adhesion layer

Claims

1. A metallocene-based linear low-density polyethylene; An abrasion-resistant layer (A) including an olefin-based thermoplastic elastomer containing an olefin-based rubber and an olefin-based resin as main components, the sum of the weights of the metallocene-based linear low-density polyethylene and the olefin-based thermoplastic elastomer is 50% by weight or more, with the weight of the abrasion-resistant layer (A) being 100% by weight; The weight ratio of the metallocene linear low density polyethylene to the olefin thermoplastic elastomer is 80-99:20-1.

2. The multilayer sheet according to claim 1 , further comprising a base layer (B) containing polypropylene or polystyrene as a main component.

3. When the base layer (B) contains polystyrene as a main component, the abrasion-resistant layer (A) and the base layer (B) are further provided with an adhesive layer (C) that adheres the abrasion-resistant layer (A) and the base layer (B), The adhesive layer (C) contains polyethylene, polystyrene, and a styrene-based thermoplastic elastomer, When the weight of the adhesive layer (C) is 100% by weight, the content of the polyethylene is 5% by weight or more and 70% by weight or less, the content of the polystyrene is 25% by weight or more and 92% by weight or less, and the content of the styrene-based thermoplastic elastomer is 3% by weight or more and 40% by weight or less. The multilayer sheet according to claim 2.

4. The abrasion-resistant layer (A) has a durometer D hardness of D35 to D65 measured in accordance with JIS K 6253-3 (2012).

5. The abrasion-resistant layer (A) has a melt mass-flow rate value of 0.5 g / 10 min or more, measured according to JIS K 7210-1 (2014) at a test temperature of 230 ° C. and a load of 2.16 kg (21.2 N). The multilayer sheet according to claim 1.

6. A sheet for forming or transporting a tray, comprising the multilayer sheet according to any one of claims 1 to 5.

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