Multilayer sheet and method for manufacturing the same

Abstract

A multilayer sheet having simultaneously improved wear resistance and impact resistance is disclosed. According to one aspect, a multilayer sheet is provided comprising: a core sheet comprising a polyolefin; and a thermoplastic elastomer (TPE) disposed on both sides of the core sheet, wherein the polyolefin comprises homopolypropylene (HOMO PP), a polypropylene copolymer, and high-density polyethylene (HDPE).

Description

Technology Field

[0001] The present invention relates to a multilayer sheet, and more specifically, to a multilayer sheet and a method for manufacturing the same. Background Technology

[0002] In the past, materials such as PP (Polypropylene), SEBS (Styrene Ethylene / Butylene Styrene), PVC (Polyvinyl chloride), TPU (Thermoplastic Polyurethane), ABS (Acrylonitrile butadiene styrene copolymer), and thermoplastic elastomers such as EPDM (Ethylene Propylene Diene Monomer, e.g., TPV, or TPO) were used in various fields including automotive interior materials, protective covers for electronic products, waterproof panels for construction, packaging materials, protective materials for medical devices, and protective materials for sports.

[0003] However, single-layer PP sheets had the problem of low impact resistance and elasticity, while single-layer SEBS or EPDM (TPV, TPO) sheets lacked wear resistance and heat resistance. To solve this, multi-layer sheets were introduced, but the use of adhesives to bond the layers resulted in a complex manufacturing process and increased manufacturing costs. Prior art literature

[0004] Korean Published Patent Application No. 10-2013-0096387 (Published August 30, 2013) The problem to be solved

[0005] According to one aspect of the present invention, a multilayer sheet is provided in which impact resistance, wear resistance, heat resistance, and chemical resistance are simultaneously enhanced.

[0006] According to another aspect of the present invention, a method for manufacturing a multilayer sheet is provided, which simplifies the manufacturing process and reduces manufacturing costs by eliminating the need for adhesives.

[0007] According to another aspect of the present invention, an article comprising a multilayer sheet applicable to various industrial fields such as automobiles, home appliances, packaging, and medical is provided.

[0008] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention may be understood from the following description and will be more clearly understood by the embodiments of the present invention. Furthermore, it will be readily apparent that the objects and advantages of the present invention can be realized by the means and combinations thereof described in the specification. means of solving the problem

[0009] According to one aspect of the present invention, a core sheet comprising a polyolefin; and disposed on both sides of the core sheet A multilayer sheet is provided, comprising a coating layer including a thermoplastic elastomer (TPE), wherein the polyolefin includes homopolypropylene (HOMO PP), polypropylene copolymer, and high-density polyethylene (HDPE).

[0010] Preferably, the content of the homopolypropylene with respect to 100 parts by weight of the core sheet may be 30 parts by weight or more and 70 parts by weight or less.

[0011] Preferably, the content of the polypropylene copolymer with respect to 100 parts by weight of the core sheet may be 5 parts by weight or more and 45 parts by weight or less.

[0012] Preferably, the content of the high-density polyethylene with respect to 100 parts by weight of the core sheet may be 5 parts by weight or more and 45 parts by weight or less.

[0013] Preferably, the thermoplastic elastomer may include one or more selected from the group consisting of SEBS (Styrene-Ethylene-Butylene-Styrene), SEPS (Styrene-Ethylene-Propylene-Styrene), TPU (Thermoplastic Polyurethane), TPEE (Thermoplastic Copolyester Elastomer), EPDM-based TPO (Ethylene Propylene Diene Monomer-based Thermoplastic Polyolefin), and EPDM-based TPV (Thermoplastic Vulcanizate of Ethylene Propylene Diene Monomer).

[0014] Preferably, the interface between the core sheet and the coating layer may include an interpenetrating polymer network (IPN) in which the thermoplastic elastomer and the polyolefin are intertwined.

[0015] Preferably, the multilayer sheet may, in accordance with ASTM D638, have a yield tensile strength of 19 MPa or more, a maximum tensile strength of 19 MPa or more, and an elongation at break of 560% or more.

[0016] Preferably, the multilayer sheet may have a heat deflection temperature (HDT) of 110°C or higher.

[0017] Preferably, the mass change of the multilayer sheet measured 1,000 times by a rotary wear tester under a measurement condition of a load of 1,000 g may be 119 mg / 1,000 cycles or less.

[0018] According to another aspect of the present invention, a method for manufacturing a multilayer sheet is provided, comprising: (S1) a step of preparing a core melt by melting a first raw material including homopolypropylene (HOMO PP), polypropylene copolymer, and high-density polyethylene (HDPE) using a first extruder; (S2) a step of preparing a first coating melt by melting a second raw material including a thermoplastic elastomer (TPE) using a second extruder; (S3) a step of preparing a second coating melt by melting a third raw material including a thermoplastic elastomer (TPE) using a third extruder; and (S4) a step of manufacturing a multilayer sheet of some of the above-described embodiments by layering the core melt and the first and second coating melts using a feedblock, wherein in step (S4), the internal pressure of the feedblock is 30 bar or more and 80 bar or less.

[0019] The means for solving the above problem are not all of the features of the present invention and may be combined with some embodiments of this specification. Various features of the present invention and the advantages and effects derived therefrom may be understood in more detail by referring to the specific description below. Effects of the invention

[0020] According to one aspect of the present invention, a multilayer sheet with simultaneously enhanced impact resistance, wear resistance, heat resistance, and chemical resistance can be realized.

[0021] According to another aspect of the present invention, the use of adhesive is unnecessary, thereby simplifying the manufacturing process and reducing manufacturing costs.

[0022] According to another aspect of the present invention, an article applicable to various industrial fields such as semiconductors, automobiles, home appliances, packaging, and medical can be realized.

[0023] In addition to the effects described above, specific effects of the present invention are described together with the following explanation of specific details for implementing the invention. Furthermore, the effects of the present invention are not limited to those mentioned above and can be easily realized by means and combinations thereof described in the specification. Brief explanation of the drawing

[0024] FIG. 1 is a vertical cross-sectional view of a multilayer sheet according to one embodiment of the present invention. FIG. 2 is a vertical cross-sectional view of a multilayer sheet according to another embodiment of the present invention. Specific details for implementing the invention

[0025] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise.

[0026] In this specification, expressions such as "first," "second," "(S1)," "(S2)," etc. may modify various components regardless of order and / or importance, and do not limit such components. These expressions may be used to distinguish one component from another. For example, without departing from the scope of the rights of this disclosure, the first component may be named the second component, and similarly, the second component may be renamed the first component.

[0027] In the present specification, if multiple numerical values ​​are disclosed for the upper and lower limits of any numerical range, the numerical range disclosed in the present specification may be understood as a range of any numerical values ​​in which any one of the multiple lower limit values ​​and any one of the multiple upper limit values ​​are respectively the lower limit value and the upper limit value. For example, if a or greater, or b or greater; and c or less, or d or less is described, it may be understood as a or greater and c or less, a or greater and d or less, b or greater and c or less, or b or greater and d or less.

[0028] According to one aspect of the present invention, a multilayer sheet is provided comprising: a core sheet comprising a polyolefin; and a coating layer disposed on both sides of the core sheet and comprising a thermoplastic elastomer (TPE), wherein the polyolefin comprises homopolypropylene (HOMO PP), a polypropylene copolymer, and high-density polyethylene (HDPE). According to one aspect of the present invention, by disposing of a coating layer having the composition described above on both sides of a core sheet having the composition described above, the effect of simultaneously enhancing impact resistance, wear resistance, heat resistance, and chemical resistance can be achieved.

[0029] Hereinafter, the configuration of the present invention will be described in more detail with reference to the drawings.

[0030] FIG. 1 is a vertical cross-sectional view of a multilayer sheet according to one embodiment of the present invention.

[0031] Referring to FIG. 1, the multilayer sheet (100) according to the present invention includes a core sheet (10) and a coating layer (20).

[0032] Core Sheet

[0033] In this specification, polyolefin is defined as a polymer compound produced by polymerizing olefins, which are hydrocarbons having double bonds.

[0034] The core sheet (10) according to the present invention includes polyolefin to improve the tensile strength and heat resistance of the multilayer sheet (100).

[0035] In this specification, a polypropylene copolymer is defined as a copolymer of propylene and another olefin copolymerized with said propylene. In some non-limiting examples, said polypropylene copolymer may comprise one or more selected from the group consisting of a random copolymer in which propylene and ethylene are randomly copolymerized; a block copolymer in which propylene blocks and ethylene blocks are arranged separately; a random copolymer in which propylene, ethylene, and butene are randomly copolymerized; and a block copolymer in which propylene blocks, ethylene blocks, and butene blocks are arranged separately.

[0036] In this specification, high-density polyethylene refers to polyethylene having a density of 0.941 g / cm³ 3 It is defined as polyethylene.

[0037] The polyolefin according to the present invention comprises homopolypropylene (HOMO PP), polypropylene copolymer, and high-density polyethylene (HDPE). Specifically, by including homopolypropylene (HOMO PP), polypropylene copolymer, and high-density polyethylene (HDPE) in the polyolefin, the tensile strength of the multilayer sheet can be further improved due to high crystallinity and regular molecular arrangement.

[0038] In some embodiments of the present invention, the content of the homopolypropylene with respect to 100 parts by weight of the core sheet may be 30 parts by weight or more and 70 parts by weight or less. Specifically, the content of the homopolypropylene with respect to 100 parts by weight of the core sheet may be 30 parts by weight or more, 35 parts by weight or more, 40 parts by weight or more, 45 parts by weight or more, or 50 parts by weight or more; and 55 parts by weight or less, 60 parts by weight or less, 65 parts by weight or less, or 70 parts by weight or less. In some embodiments of the present invention, by controlling the content of the homopolypropylene to the above numerical range, the tensile strength of the multilayer sheet can be further improved due to high crystallinity and regular molecular arrangement.

[0039] In some embodiments of the present invention, the content of the polypropylene copolymer with respect to 100 parts by weight of the core sheet may be 5 parts by weight or more and 45 parts by weight or less. Specifically, with respect to 100 parts by weight of the core sheet, the content of the polypropylene copolymer may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more; and 30 parts by weight or less, 35 parts by weight or less, 40 parts by weight or less, or 45 parts by weight or less. In some embodiments of the present invention, by controlling the content of the polypropylene copolymer to the above numerical range, the impact strength and toughness of the multilayer sheet can be supplemented, and at the same time, the interfacial bonding strength between the core sheet and the coating layer can be further improved.

[0040] In some embodiments of the present invention, the content of the high-density polyethylene with respect to 100 parts by weight of the core sheet may be 5 parts by weight or more and 45 parts by weight or less. Specifically, with respect to 100 parts by weight of the core sheet, the content of the high-density polyethylene may be 5 parts by weight or more, 10 parts by weight or more, 15 parts by weight or more, 20 parts by weight or more, or 25 parts by weight or more; and 30 parts by weight or less, 35 parts by weight or less, 40 parts by weight or less, or 45 parts by weight or less. In some embodiments of the present invention, by controlling the content of the high-density polyethylene to the above numerical range, the molecular chains are densely arranged, thereby increasing the tensile strength of the multilayer sheet and achieving an excellent effect in distributing tensile load.

[0041] In some embodiments of the present invention, the average thickness of the core sheet (10) may be 0.2 mm or more and 3 mm or less. Specifically, the average thickness of the core sheet (10) may be 0.2 mm or more, 0.7 mm or more, 0.8 mm or more, or 0.85 mm or more; and 0.90 mm or less, 1.00 mm or less, 1.1 mm or less, 1.2 mm or less, or 3 mm or less. In some embodiments of the present invention, by adjusting the average thickness of the core sheet (10) to the above numerical range, the rigidity, tensile strength, and dimensional stability of the multilayer sheet can be maximized, and at the same time, the weight of the multilayer sheet can be achieved.

[0042] coating layer

[0043] In this specification, a “layer” or “film” may include cases where, when observing the region in which the layer or film exists, it is formed over the entire region, or cases where it is formed only in a part of the region. For example, the surface of the layer or film may be defined as having a flat shape, a non-flat shape, and combinations thereof; or a continuous shape, a discontinuous shape, and combinations thereof. For example, when another member is composed of a layer or film directly on a member, the coverage of the other member on the surface of the member may be defined as 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 99% or more. For example, it may also be defined as a “layer” or “film” when a plurality of particles form a clustered structure.

[0044] In this specification, when another member is placed directly on top of one member, it may be defined that no member is interposed between the one member and the other member.

[0045] The coating layer (20) according to the present invention is disposed on both sides of the core sheet (10). Specifically, the coating layer (20) may include a first coating layer (20a) disposed on the upper surface of the core sheet (10) and a second coating layer (20b) disposed on the lower surface of the core sheet (10). Specifically, the first coating layer (20a) may be disposed directly above the core sheet (10), and the second coating layer (20b) may be disposed directly below the core sheet (10).

[0046] The coating layer (20) according to the present invention comprises a thermoplastic elastomer (TPE). Specifically, by including the thermoplastic elastomer, the coating layer (20) effectively absorbs and disperses external shocks or pressures due to elasticity similar to rubber, thereby effectively protecting the inner core sheet from damage and improving the restoring force to restore to its original shape even after repeated deformation.

[0047] In some embodiments of the present invention, the density of the thermoplastic elastomer is 0.86 g / cm³ 3 Above 1.3 g / cm³ 3 The following may be possible. In some embodiments of the present invention, the density of the thermoplastic elastomer is controlled to the above numerical range, thereby effectively absorbing and dispersing externally applied shock or pressure due to rubber-like elasticity, effectively protecting the inner core sheet from damage, and further improving the restoring force that restores it to its original shape even after repeated deformation.

[0048] In some embodiments of the present invention, the thermoplastic elastomer may include one or more selected from the group consisting of SEBS (Styrene-Ethylene-Butylene-Styrene), SEPS (Styrene-Ethylene-Propylene-Styrene), TPU (Thermoplastic Polyurethane), TPEE (Thermoplastic Copolyester Elastomer), EPDM-based TPO (Ethylene Propylene Diene Monomer-based Thermoplastic Polyolefin), and EPDM-based TPV (Thermoplastic Vulcanizate of Ethylene Propylene Diene Monomer). Here, EPDM-based TPO may be a blend in which EPDM particles are dispersed within a TPO matrix in an uncrosslinked state, and EPDM-based TPV may be a material with a network structure in which EPDM particles exist in a dynamically crosslinked state within a thermoplastic matrix. In some embodiments of the present invention, the thermoplastic elastomer includes SEBS (Styrene-Ethylene-Butylene-Styrene), EPDM-based TPO, or EPDM-based TPV, thereby effectively absorbing and dispersing externally applied shock or pressure, effectively protecting the inner core sheet from damage, and further improving the restoring force to restore to its original shape even after repeated deformation.

[0049] In some embodiments of the present invention, the average thickness of the coating layer (20) may be independently 0.015 mm or more and 0.15 mm or less. Specifically, the average thickness of the coating layer (20) may be independently 0.015 mm or more, 0.025 mm or more, 0.040 mm or more, 0.050 mm or more, 0.060 mm or more, 0.070 mm or more, or 0.075 mm or more; and 0.080 mm or less, 0.090 mm or less, 0.100 mm or less, 0.125 mm or less, or 0.15 mm or less. In some embodiments of the present invention, by adjusting the average thickness of the coating layer (20) to the above numerical range, the function of absorbing external shock can be maximized, and at the same time, the structural rigidity of the multilayer sheet can be achieved.

[0050] In some examples, the average thickness of the coating layer (20) may be the average thickness of the first coating layer (20a) or the second coating layer (20b) described above.

[0051] In some examples, the average thickness described above can be measured with a microscope or vernier calipers.

[0052] In some embodiments of the present invention, the multilayer sheet (100) may further include a reinforcing layer (15) between the core sheet and the coating layer. Specifically, the reinforcing layer (15) includes an interpenetrating polymer network (IPN) in which a thermoplastic elastomer and a polyolefin are intertwined. Here, an interpenetrating polymer network is defined as a structure or state in which a thermoplastic elastomer and a polyolefin are physically intertwined at the molecular level but are not chemically bonded to each other. In some embodiments of the present invention, by including an interpenetrating polymer network (IPN) in which a thermoplastic elastomer and a polyolefin are intertwined, the reinforcing layer can be realized having the elasticity of the thermoplastic elastomer and the stiffness of the polyolefin simultaneously. Accordingly, the impact resistance and tensile strength of the multilayer sheet can be achieved simultaneously.

[0053] In some embodiments of the present invention, the interface between the core sheet and the coating layer may include an interpenetrating polymer network (IPN) in which the thermoplastic elastomer and the polyolefin are intertwined. Accordingly, impact resistance and tensile strength of the multilayer sheet can be achieved simultaneously.

[0054] In this specification, a feedblock is defined as a device that combines different melts from multiple extruders into multiple layers in one place during a co-extrusion process. In some examples, the feedblock may include an inlet through which melts from multiple extruders are introduced via individual channels; channels in which each melt is arranged in a desired order to form a layered structure; and an outlet through which the combined multilayer melts are combined into a single stream and transported to a die.

[0055] FIG. 2 is a vertical cross-sectional view of a multilayer sheet according to another embodiment of the present invention.

[0056] Referring to FIG. 2, in some embodiments of the present invention, the reinforcing layer (15) may be disposed between the core sheet (10) and the coating layer (20).

[0057] In some non-limiting examples, the interpenetrating polymer network (IPN) may be formed by controlling the pressure inside a feed block that combines the core melt and the first and second coating melts in layers at one location during the co-extrusion process. In this case, the pressure inside the feed block may be increased to overcome the difference in melt indices between the core melt and the coating melts.

[0058] In some embodiments of the present invention, an adhesive layer may not be disposed between the core sheet (10) and the coating layer (20). In some embodiments of the present invention, manufacturing costs can be significantly reduced by not disposing of an adhesive layer between the core sheet and the coating layer.

[0059] Relationships between components

[0060] In some embodiments of the present invention, the ratio of the average thickness of the coating layer (20) to the average thickness of the core sheet (10) (coating layer:core sheet) may be 1:2 to 1:50. Specifically, the ratio of the average thickness of the coating layer (20) to the average thickness of the core sheet (10) (coating layer:core sheet) may be 1:2 or more, 1:4 or more, 1:5 or more, or 1:10 or more, and may be 1:12 or less, 1:20 or less, 1:30 or less, 1:40 or less, or 1:50 or less. In some embodiments of the present invention, by adjusting the ratio of the average thickness of the coating layer (20) to the average thickness of the core sheet (10) (coating layer:core sheet) to the above numerical range, the effect of simultaneously achieving tensile strength and impact resistance of the multilayer sheet can be realized. Here, the average thickness of the coating layer may be the individual thickness of the coating layer disposed on one side of the core sheet.

[0061] Physical properties

[0062] In some embodiments of the present invention, in accordance with ASTM D638: the yield tensile strength of the multilayer sheet (100) may be 19 MPa or more, the max tensile strength may be 19 MPa or more, and the elongation at break may be 560% or more.

[0063] In some embodiments of the present invention, the heat deflection temperature (HDT) of the multilayer sheet (100) may be 110°C or higher.

[0064] In some embodiments of the present invention, under measurement conditions of a load of 1,000 g, the mass change of the multilayer sheet (100) measured 1,000 times by a rotary wear tester may be 119 mg / 1,000 cycles or less.

[0065] In some embodiments of the present invention, when a 5,000g falling ball is free-falling from a height of 2m into the center of a multilayer sheet and impact is applied, the impact strength of the falling ball of the multilayer sheet (100) may be 90J or more.

[0066] Application

[0067] In some non-limiting examples, the multilayer sheet may be included in automotive interior materials or automotive shock protection parts in the semiconductor and automotive fields; membranes and filter supports for air and liquid filtration in the filter industry; protective covers, exterior materials, or anti-vibration pads in the electronics and home appliance fields; waterproof panels, shock-absorbing flooring, or wall materials in the construction and interior fields; protective sheets, food packaging materials, or waterproof sheets for protecting electronic products in the packaging and protection fields; protective materials for medical devices, reusable packaging materials, or antimicrobial films in the medical and hygiene fields; and helmet protective materials, sports mats, or handles for exercise equipment in the sports and leisure fields.

[0068] 2. Method for manufacturing a multilayer sheet

[0069] In this specification, an extruder is defined as comprising a screw that rotates after heating and melting raw materials. Here, the extruder may be a device distinguished from a feed block, which is a device that combines different molten materials from multiple extruders into multiple layers in one place in a co-extrusion process.

[0070] In this specification, a feedblock is defined as a device that combines different melts from multiple extruders into multiple layers in one place in a co-extrusion process. In some examples, the feedblock may include an inlet into which melts from multiple extruders are introduced through individual channels; channels in which each of the melts is arranged in a desired order to form a layered structure; and an outlet into which the combined multilayer melts are combined into a single stream and transferred to a die.

[0071] According to another aspect of the present invention, a method for manufacturing a multilayer sheet is provided, comprising: (S1) a step of preparing a core melt by melting a first raw material including homopolypropylene (HOMO PP), polypropylene copolymer, and high-density polyethylene (HDPE) using a first extruder; (S2) a step of preparing a first coating melt by melting a second raw material including a thermoplastic elastomer (TPE) using a second extruder; (S3) a step of preparing a second coating melt by melting a third raw material including a thermoplastic elastomer (TPE) using a third extruder; and (S4) a step of manufacturing a multilayer sheet of some embodiment by layering the core melt and the first and second coating melts using a feedblock, wherein in step (S4), the internal pressure of the feedblock is 30 bar or more and 80 bar or less. According to another aspect of the present invention, by adjusting the internal pressure of the feed block to the numerical range, a multilayer sheet can be easily implemented without an adhesive, thereby significantly reducing manufacturing costs and simultaneously achieving the effect of tensile strength and impact resistance of the multilayer sheet.

[0072] In some non-limiting examples, the first to third extruders may be different extruders, and specifically may be extruders including a uniaxial or biaxial screw.

[0073] In some non-limiting examples, the cylinder temperature for melting the first raw material may be 170 to 215°C.

[0074] In this specification, the Melt Flow Index (MFI) is a physical property indicating how well a molten polymer flows under certain conditions (fluidity), and is defined as the mass of a polymer extruded through a standard die for 10 minutes.

[0075] In some non-limiting examples, the Melt Flow Index (MFI) of the first raw material may be 1.0 to 4.0 / 10 min under measurement conditions of a temperature of 230°C and a load of 2.16 kg.

[0076] In some non-limiting examples, the Melt Flow Index (MFI) of the second and third raw materials may each be independently 2.0 to 10.0 g / 10 min under measurement conditions of a temperature of 230°C and a load of 2.16 kg.

[0077] In some non-limiting examples, the cylinder temperature for melting the second and third raw materials may be 180 to 235°C.

[0078] In some examples, ASTM D12380 test standard may be used to measure the melt index of the first to third raw materials.

[0079] In some embodiments of the present invention, the internal pressure of the feed block in step (S4) may be 30 bar or more, 40 bar or more, 50 bar or more, or 60 bar or more, and 65 bar or less, 70 bar or less, or 80 bar or less. In some embodiments of the present invention, by controlling the internal pressure of the feed block to the above numerical range, the interfacial bonding strength can be further improved by forming an interpenetrating polymer network (IPN) in which the thermoplastic elastomer and the polyolefin are intertwined at the interface between the core sheet and the coating layer, even though the sheet is implemented with first to third raw materials having different dissolution indices.

[0080] In some non-limiting examples, the above step (S4) may include the step of transferring a combination of the core melt and the first and second coating melts into a layered structure to a die to form a multilayer sheet.

[0081] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the present invention; however, this is merely an example, and the scope of the present invention is not limited by the following.

[0082] In this specification, terms such as “about” or “substantially” refer to a reasonable amount of variation of a term modified so as not to significantly alter the final result. Such terms may be interpreted to include a variation of at least ±5% or at least ±10% to the extent that the variation does not alter or invalidate the meaning of the word.

[0083] [Manufacturing Example 1: Preparation of Sheet]

[0084] <Comparative Example 1: Manufacture of PP Single-Layer Sheet>

[0085] A single layer of polypropylene with an average thickness of about 1 mm was prepared.

[0086] <Comparative Example 2: Manufacture of SEBS Single-Layer Sheet>

[0087] A single layer of SEBS (Styrene Ethylene / Butylene Styrene) with an average thickness of about 1 mm was prepared.

[0088] <Example: Multilayer sheet manufactured by co-extrusion method>

[0089] Raw material preparation stage:

[0090] Homopolypropylene (Density: 0.905 g / cm³ 3 ) 50 wt%; polypropylene copolymer of propylene and ethylene (density: 0.900 g / cm³ 3 ) 25 wt% and high-density polyethylene (density: 0.950 g / cm³ 3 A raw material containing 25% by weight was prepared.

[0091] Melting stage:

[0092] After feeding the above raw material into a hopper equipped with a twin-screw extruder, the temperature of the cylinder was set to 180~200℃ to melt the raw material and produce a core molten material. At this time, the rotational speed of the screw was controlled to 50~80 rpm.

[0093] Preparation steps of the coating melt:

[0094] A hopper equipped in a separate twin-screw extruder with a density of 3–10 g / cm³ 3 After introducing SEBS (Styrene Ethylene / Butylene Styrene), the temperature of the cylinder was set to 180–235°C, and the SEBS was melted to produce a first coating melt. At this time, the rotational speed of the screw was controlled to 50–80 rpm.

[0095] A hopper equipped in a separate twin-screw extruder with a density of 3–10 g / cm³ 3 After introducing SEBS (Styrene Ethylene / Butylene Styrene), the temperature of the cylinder was set to 180–235°C, and the SEBS was melted to produce a second coating melt. At this time, the rotation speed was controlled to 50–80 rpm.

[0096] Co-extrusion step:

[0097] Each melt was combined into a layered structure using a feedblock method in which the core melt from each extruder and the first and second coating melts were combined in a layered manner at one location. Specifically, the core melt and the first and second coating melts were co-extruded in the feedblock at an internal pressure of about 60 bar and a temperature of about 200°C to produce a pre-multilayer sheet (in a molten state) in which each coating layer (average thickness of individual coating layers: about 0.075 mm) placed on both sides of a core sheet (average thickness: about 0.85 mm) was bonded. At this time, due to the pressure range, an interpenetrating polymer network (IPN) in which polyolefin and SEBS were intertwined was formed between the interfaces of the core sheet and each coating layer.

[0098] Cooling phase:

[0099] The above-mentioned pre-multilayer sheet in a molten state was transferred to a die having a predetermined shape, and then cooled at about 30°C to finally produce a multilayer sheet (average thickness: about 1 mm).

[0101] [Experimental Example: Evaluation of Sheet Physical Properties]

[0102] The physical properties of each sheet prepared by the method according to Manufacturing Example 1 above were measured by the following method, and the results are shown in Table 1 below.

[0103] Falling ball impact strength:

[0104] Each sheet prepared by the method according to Manufacturing Example 1 above was sampled to 300 mm X 300 mm with an average thickness of about 1 mm to prepare sheet specimens.

[0105] After placing the above sheet specimens on a flat support, a 500g falling ball was dropped from a height of 2m onto the center of each sheet to apply an impact. As a result, the critical impact energy at which each sheet broke was named the falling ball impact strength and is shown in Table 1 below.

[0106] Yield tensile strength, maximum tensile strength, and elongation at break:

[0107] Yield tensile strength, maximum tensile strength, and elongation at break were measured according to the ASTM D638 test standard. Specifically, each sheet prepared by the method according to Manufacturing Example 1 above was sampled into ASTM D638 Type 1 and Type 4 specimens. After mounting each sheet specimen on a universal testing machine, both ends of the sheet specimen were pulled at a tensile speed of 50 mm / min, and the yield tensile strength, which is the stress value at the point where plastic deformation first begins, and the maximum tensile strength, which is the stress value at the moment the sheet specimen withstands the maximum load, are shown in Table 1 below.

[0108] Heat distortion temperature:

[0109] Sheet specimens were prepared by sampling each sheet manufactured by the method according to Manufacturing Example 1 with dimensions of 300 mm x 300 mm and an average thickness of approximately 1 mm. Specifically, the sheet specimens were placed on a heat deformation temperature tester, and a load of 0.45 MPa was applied to the center of the sheet specimens. While continuously increasing the temperature inside the tester at a constant rate of 2°C / min, the temperature at the moment when the center of the sheet specimen deformed or sagged by 0.25 mm was measured. At this time, a higher heat deformation temperature indicates superior heat resistance.

[0110] Taber wear:

[0111] Sheet specimens were prepared by sampling each sheet manufactured by the method according to Manufacturing Example 1 above, with a diameter of 300 mm and an average thickness of approximately 1 mm. Specifically, the sheet specimens were mounted on a rotary wear tester (equipment name: Taber Co.), a standard wear wheel (CS10) and a load of 1000 g were attached, and the specimens were rotated 1,000 times. The change in mass of the sheet specimens before and after rotation is shown in Table 1 below. In this case, a lower change in mass of the sheet specimen indicates superior wear resistance.

[0112] Measurement of the coefficient of friction:

[0113] Each sheet prepared by the method according to Manufacturing Example 1 above was sampled to a size of 300 mm X 300 mm and an average thickness of approximately 1 mm to produce sheet specimens. Specifically, the static coefficient of friction (μs) and the dynamic coefficient of friction (μd) of the sheet specimens were measured according to the ISO 8295:1995 test standard, and the results are shown in Table 1 below. At this time, the sled mass was fixed at 200 g and the test speed at 100 mm / min.

[0114] division Sample Comparative Example 1 Comparative Example 2 Examples sheet - PP single-layer sheet SEBS single-layer sheet SEBS / PP / SEBS multilayer sheet Total average sheet thickness 1.0 mm 1.0 mm 1.0 mm Falling ball impact intensity (J) 30J 60 J 90J Yield tensile strength (MPa) ASTM D638 Type 1 26.4MPa 0 MPa 19.4MPa ASTM D638 Type 4 23.1 MPa 0.1 MPa 19.2MPa Maximum tensile strength (MPa) ASTM D638 Type 1 27.3 MPa 1.3 MPa 19.6 MPa ASTM D638 Type 4 34.6 MPa 3.2 MPa 25.9 MPa Break elongation (%) ASTM D638 Type 1 597% 523% 560% ASTM D638 Type 4 817% 898% 730% Heat distortion temperature (°C) - 100℃ 80℃ 110℃ Taber wear (mg / 1,000 cycles) 120mg / 1,000 cycles 250mg / 1,000 cycles 119 mg / 1,000 cycles coefficient of friction coefficient of static friction 0.433 7.518 7.518 coefficient of dynamic friction 0.274 0.999 0.999

[0115] The features described in the above-described embodiment may be combined with other embodiments unless explicitly stated otherwise. Furthermore, although preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements by those skilled in the art using the basic concept of the present invention as defined in the following claims also fall within the scope of the present invention. Explanation of the symbols

[0116] 100: Multilayer sheet 10: Core Sheet 20: Coating layer 20a: First coating layer 20b: Second coating layer 15: Reinforcement layer

Claims

Claim 1 A multilayer sheet comprising: a core sheet comprising a polyolefin; and a coating layer disposed on both sides of the core sheet and comprising a thermoplastic elastomer (TPE); wherein the polyolefin comprises: homopolypropylene (HOMO PP), polypropylene copolymer, and high-density polyethylene (HDPE); and the interface between the core sheet and the coating layer comprises: an interpenetrating polymer network (IPN) in which the thermoplastic elastomer and the polyolefin are intertwined. Claim 2 A multilayer sheet according to claim 1, wherein, with respect to 100 parts by weight of the core sheet: the content of the homopolypropylene is 30 parts by weight or more and 70 parts by weight or less. Claim 3 A multilayer sheet according to claim 1, wherein, with respect to 100 parts by weight of the core sheet: the content of the polypropylene copolymer is 5 parts by weight or more and 45 parts by weight or less. Claim 4 A multilayer sheet according to claim 1, wherein, with respect to 100 parts by weight of the core sheet: the content of the high-density polyethylene is 5 parts by weight or more and 45 parts by weight or less. Claim 5 A multilayer sheet according to claim 1, wherein the thermoplastic elastomer comprises one or more selected from the group consisting of SEBS (Styrene-Ethylene-Butylene-Styrene), SEPS (Styrene-Ethylene-Propylene-Styrene), TPU (Thermoplastic Polyurethane), TPEE (Thermoplastic Copolyester Elastomer), EPDM-based TPO (Ethylene Propylene Diene Monomer-based Thermoplastic Polyolefin), and EPDM-based TPV (Thermoplastic Vulcanizate of Ethylene Propylene Diene Monomer). Claim 6 delete Claim 7 In claim 1, in accordance with ASTM D638: a multilayer sheet having a yield tensile strength of 19 MPa or more, a maximum tensile strength of 19 MPa or more, and an elongation at break of 560% or more. Claim 8 A multilayer sheet according to claim 1, having a heat deflection temperature (HDT) of 110 ℃ or higher. Claim 9 A multilayer sheet according to claim 1, wherein the mass change measured 1,000 times by a rotary wear tester under measurement conditions of a load of 1,000 g is 119 mg / 1,000 cycles or less. Claim 10 (S1) a step of preparing a core melt by melting a first raw material comprising homopolypropylene (HOMO PP), polypropylene copolymer, and high-density polyethylene (HDPE) using a first extruder; (S2) a step of preparing a first coating melt by melting a second raw material comprising a thermoplastic elastomer (TPE) using a second extruder; (S3) a step of preparing a second coating melt by melting a third raw material comprising a thermoplastic elastomer (TPE) using a third extruder; and (S4) a step of manufacturing a multilayer sheet according to any one of claims 1 to 5 and claims 7 to 9 by layering the core melt and the first and second coating melts using a feedblock; A method for manufacturing a multilayer sheet, comprising, wherein in step (S4), the internal pressure of the feed block is 30 bar or more and 80 bar or less.

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