Polypropylene multilayer sheet excellent in recyclability and molded article thereof

Abstract

A polypropylene multilayer sheet having a thickness of 0.5 to 5 mm, comprising: a plurality of biaxially-stretched polypropylene layers, and a layer P comprising one or more layers composed of a composition comprising a polypropylene-based resin and an ethylene-C4 to C10 alpha-olefin copolymer; having the following properties: 1) the thickness of the layer P is 0.5 to 500 µm; 2) at least one of the layer P is present at a position satisfying 2% ≤ r / R (with the surface of the multilayer sheet as the origin, r being the distance from the origin to the position of the interface between the layer P and other layers in the thickness direction on the origin side, and R being the total thickness of the multilayer sheet. Here, the origin is the surface at which the r is the smallest.); 3) in the layer P, the content of the ethylene-C4 to C10 alpha-olefin copolymer is 10 to 40% by weight.

Description

Technical Field

[0001] This invention relates to a polypropylene multilayer sheet with excellent recyclability and its molded form. Background Technology

[0002] To improve the appearance of the design, plastics are often coated or covered with decorative films. However, when recycling the molded plastic body, it is necessary to remove the coating and film. As a method for peeling off the coating, etc., a method using ethylene-butene copolymer as a peeling layer is known (for example, Patent Document 1). In addition, Patent Document 2 discloses a polypropylene multilayer sheet with an easy-peeling layer. Existing technical documents Patent documents

[0003] Patent Document 1: Japanese Patent Application Publication No. 2007-237590 Patent Document 2: International Publication No. 2023 / 127972 Summary of the Invention The problem that the invention aims to solve

[0004] If the peel strength of the release layer in an article is too low, the coating or other components will peel off when the article is used. On the other hand, if the peel strength of the release layer in an article is too high, the coating or other components will be difficult to peel off. Especially in the field of automotive exteriors, if the peel strength is too low, the coating may peel off due to external stimuli in the natural environment or high-pressure car washes, while there is a need to peel off the coating during recycling. In view of the above, the object of the present invention is to provide a product with moderate peel strength. Solution for solving the problem

[0005] The inventors discovered that the aforementioned problem can be solved by optimizing the layer structure of multilayer sheets. Specifically, the problem is solved by the following invention. Implementation Method 1 A multilayer polypropylene sheet with a thickness of 0.5–5 mm, comprising: Multiple biaxially stretched polypropylene layers, and One or more layers P, wherein layer P is composed of a composition comprising a polypropylene resin and an ethylene-C4 to C10 α-olefin copolymer. It has the following characteristics: 1) The thickness of layer P is 0.5–500 μm; 2) At least one of the layers P exists at a position satisfying 2% ≤ r / R; (Taking the surface of the multilayer sheet as the origin, r is the distance from the origin to the interface between layer P and other layers in the thickness direction on the side of the origin, and R is the total thickness of the multilayer sheet. The origin is the surface at which r is minimized.) 3) In the composition constituting layer P, the content of the ethylene-C4 to C10 α-olefin copolymer is 10 to 40% by weight. Implementation Method 2 The polypropylene multilayer sheet described in Embodiment 1, wherein, The MFR (230°C, 2.16 kg load) of the composition constituting layer P is 0.5–30 g / 10 minutes. The intrinsic viscosity of the xylene-soluble component in the composition at room temperature is 0.5–4 dL / g. Implementation Method 3 The polypropylene multilayer sheet described in Embodiment 2, wherein, The composition constituting layer P comprises a polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1). The component (A1) is a propylene (co)polymer, comprising 60-90% by weight, which contains 0-5% by weight of comonomer-derived units selected from C2-C10 α-olefins (excluding C3 α-olefins). The component (A2) is an ethylene-C4-C10 α-olefin copolymer containing 10-35% by weight of C4-C10 α-olefin derivative units, accounting for 10-40% by weight. Implementation Method 4 The polypropylene multilayer sheet according to any one of embodiments 1 to 3, wherein layer P is a biaxially stretched layer. Implementation Method 5 The polypropylene multilayer sheet according to any one of embodiments 1 to 4, wherein, The polypropylene multilayer sheet is formed by a method comprising fusing the layers of a precursor obtained by laminating a biaxially stretched polypropylene sheet component forming the biaxially stretched polypropylene layer with a sheet component forming the layer P. The precursor comprises a co-extruded layer in which polypropylene layers are laminated on both sides of layer P, and The layer P is a layer P' containing a polypropylene resin, which has a phase structure in which component (A2) is dispersed in component (A1'). The component (A1') is a propylene polymer, accounting for 60-90% by weight. The component (A2) is an ethylene-C4-C10 α-olefin copolymer containing 10-35% by weight of C4-C10 α-olefin derivative units, accounting for 10-40% by weight. Implementation Method 6 The polypropylene multilayer sheet of embodiment 5, wherein the co-extruded layer is a biaxially stretched layer. Implementation Method 7 The polypropylene multilayer sheet according to any one of embodiments 1 to 4, wherein the polypropylene multilayer sheet is formed by a method including interlayer welding of a precursor obtained by laminating a biaxially oriented polypropylene sheet member forming the biaxially oriented polypropylene layer with a sheet member forming the layer P. The layer P is a layer P” containing a polypropylene resin, which has a phase structure in which component (A2) is dispersed in component (A1”). The component (A1”) is a propylene copolymer, comprising 60-90% by weight, which contains greater than 0 and not more than 5% by weight of comonomer-derived units selected from C2-C10 α-olefins (excluding C3 α-olefins). The component (A2) is an ethylene-C4-C10 α-olefin copolymer containing 10-35% by weight of C4-C10 α-olefin derivative units, accounting for 10-40% by weight. Implementation Method 8 The polypropylene multilayer sheet of embodiment 7, wherein the precursor comprises a co-extruded layer of layer P” laminated on both sides of the biaxially stretched polypropylene layer. Implementation Method 9 The polypropylene multilayer sheet according to any one of embodiments 1 to 8, wherein layer P contains less than 10% by weight of inorganic filler material. Implementation Method 10 A molded body obtained by molding a polypropylene multilayer sheet according to any one of embodiments 1 to 9. Implementation Method 11 The molded body described in Embodiment 10 is an automotive component. Implementation Method 12 A stripping method, In this embodiment, layer P is used as a peeling layer to peel at least one layer from the polypropylene multilayer sheet described in any one of Embodiments 1 to 9 or from the molded body described in Embodiment 10 or 11. Invention Effects

[0006] This invention enables the provision of products with moderate peel strength. Attached Figure Description

[0007] Figure 1 This is a schematic diagram illustrating the general structure of polypropylene multilayer sheets. Figure 2This is a schematic diagram illustrating the polypropylene multilayer sheet of the first embodiment. Figure 3 This is a schematic diagram illustrating the outline of the polypropylene multilayer sheet manufacturing method according to the first embodiment. Figure 4 This is a schematic diagram illustrating the polypropylene multilayer sheet of the second embodiment. Figure 5 This is a schematic diagram illustrating the outline of the polypropylene multilayer sheet manufacturing method according to the second embodiment. Detailed Implementation

[0008] In this disclosure, "X~Y" indicates that the end values ​​are included, that is, including both X and Y. Sheets and films are used as synonyms, but sometimes film-like components with a thickness of 150 μm or more are specifically referred to as sheets, while film-like components with a thickness of less than 150 μm are referred to as films. In addition, sheets and films are sometimes collectively referred to as "sheet-like components".

[0009] 1. Polypropylene multilayer sheet (1) Thickness In one embodiment, the thickness of the polypropylene multilayer sheet (hereinafter also simply referred to as "multilayer sheet") is 0.5 to 5 mm. If the sheet is too thin, its peelability is poor, leading to difficulties in recycling. Conversely, if the sheet is too thick, the manufacture of the multilayer sheet becomes difficult. From this perspective, the lower limit of the thickness is preferably 0.7 mm or more, more preferably 1 mm or more. The upper limit of the thickness is preferably 4.5 mm or less, more preferably 4 mm or less. That is, as a preferred thickness range, it can be, for example, 0.7 to 4.5 mm or 1 to 4 mm. The thickness of the multilayer sheet can be appropriately adjusted according to the application.

[0010] (2) Multi-layer structure The multilayer sheet comprises multiple biaxially stretched polypropylene layers and one or more layers P consisting of a composition comprising a polypropylene resin and an ethylene-C4 to C10 α-olefin copolymer. Layer P can be a non-stretched layer, a uniaxially stretched layer, or a biaxially stretched layer. The biaxially stretched polypropylene layers are composed of a polypropylene resin or a composition thereof. The polypropylene resin is a resin with polypropylene as its main component.

[0011] (2-1) Location of layer P Layer P exists at a specific location and acts as a release layer. Therefore, in multilayer sheets, there can be layers above layer P and layers below layer P. Although the details of the release method will be described later, at least one layer P exists at a location satisfying 2% ≤ r / R. Figure 1As shown, with the surface of the multilayer sheet as the origin, r is the distance from the origin to the interface between layer P and other layers in the thickness direction on the side of the origin. The multilayer sheet has two surfaces, but the origin is defined as the surface that minimizes r. R is the total thickness of the multilayer sheet. In the figure, 1 is the multilayer sheet, 10 is layer P, and 12 is a biaxially stretched polypropylene layer. If the above relationship is satisfied, a suitable peel strength can be obtained. From this point of view, the lower limit of r / R is preferably 5% or more, more preferably 7% or more. Furthermore, the upper limit of r / R is preferably 40% or less, more preferably 30% or less. Therefore, the preferred range of r / R can be, for example, 5 to 40% or 7 to 30%.

[0012] When multiple layers P exist, the location of the layer exhibiting moderate peel strength during peeling can be determined by controlling the thickness of each layer. Furthermore, as in peel tests, the location can be determined by setting a starting point within a specific layer. For example, if a starting point is set in layer P, material failure occurs in that layer P, resulting in moderate peel strength and good peel performance. Similarly, if a starting point is set in a layer adjacent to layer P, material failure occurs in the layer P closest to that layer, resulting in moderate peel strength and good peel performance. Hereinafter, exhibiting moderate peel strength will be referred to as excellent peel performance.

[0013] (2-2) Thickness of layer P The thickness of layer P is 0.5–500 μm. If layer P is too thin, excellent peelability cannot be obtained, leading to difficulties in recycling. Conversely, if layer P is too thick, the peel strength is too high, also leading to difficulties in recycling. From this perspective, the lower limit of the thickness of layer P is preferably 1 μm or more, more preferably 2 μm or more. The upper limit of the thickness is preferably 300 μm or less, more preferably 200 μm or less. That is, the preferred thickness range is, for example, 1–300 μm or 2–200 μm.

[0014] (2-3) The composition constituting layer P Layer P is composed of a composition comprising a polypropylene resin and an ethylene-C4 to C10 α-olefin copolymer. The content of the ethylene-C4 to C10 α-olefin copolymer in layer P is 10 to 40% by weight. If this content is too low, the peelability of the multilayer sheet becomes unstable. If this content is too high, the peel strength decreases, or the manufacture of the multilayer sheet becomes difficult. From this viewpoint, the lower limit of this amount is preferably 15% by weight or more. The upper limit of this amount is preferably 35% by weight or less. That is, a preferred range is, for example, 15 to 35% by weight.

[0015] Layer P may or may not contain inorganic filler. While layer P is preferably free of inorganic filler, if it does contain inorganic filler, the amount of inorganic filler is preferably 10% by weight or less, more preferably 3% by weight or less, and even more preferably 2% by weight or less, based on the weight of layer P. In this case, the lower limit of the amount of inorganic filler only needs to be more than 0% by weight, but is preferably 0.1% by weight or more. Although there is no limitation on the inorganic filler, the following materials are preferred.

[0016] Powdered fillers such as synthetic silicate or silicates, such as calcium silicate, aluminum silicate, silicic acid, anhydrous silicic acid, etc.; plate-shaped fillers such as talc, kaolin, clay, mica, etc.; whisker-shaped fillers such as basic magnesium sulfate whiskers, calcium titanate whiskers, aluminum borate whiskers, sepiolite, PMF (Processed Mineral Filler), hard calcium silicate, potassium titanate, and diazoapatite, etc.; spherical fillers such as glass microspheres, fly ash microspheres, etc.; and fibrous fillers such as glass fiber, etc.

[0017] 1) MFR The mass flow rate (MFR) of the composition constituting layer P (230°C, 2.16 kg load) is preferably 0.5 to 30 g / 10 minutes. If the MFR exceeds the upper limit, the preparation of polypropylene sheet components as raw materials for multilayer sheets becomes difficult, which may lead to a decrease in peel stability. Conversely, if the MFR is below the lower limit, the preparation of polypropylene sheet components may also become difficult. From this perspective, the lower limit of the MFR is preferably 1 g / 10 minutes or more, more preferably 1.5 g / 10 minutes or more. The upper limit of the MFR is preferably 15 g / 10 minutes or less, more preferably 7 g / 10 minutes or less. That is, the preferred range of the MFR can be, for example, 1 to 15 g / 10 minutes or 1.5 to 7 g / 10 minutes. The MFR is measured according to JISK 7210-1 and based on JISK 6921-2, at a temperature of 230°C and a load of 2.16 kg.

[0018] 2) XSIV The intrinsic viscosity (XSIV) of the xylene-soluble component of the composition at room temperature is preferably 0.5 to 4 dL / g. If the XSIV exceeds the upper limit, the peel stability may decrease. Conversely, if the XSIV is below the lower limit, the peel strength may decrease excessively. From this perspective, the lower limit of XSIV is preferably 1 dL / g or more, and the upper limit is preferably 2.5 dL / g or less. That is, the preferred range of XSIV is, for example, 1 to 2.5 dL / g.

[0019] XS can be obtained by known methods, such as preferably by the following methods. 2.5 g of polypropylene resin was placed in a flask containing 250 mL of o-xylene (solvent). Using a heated plate and reflux apparatus, the solution was stirred for 30 minutes at 135 °C while purging with nitrogen until completely dissolved. Subsequently, the solution was cooled (e.g., at 25 °C for approximately 1 hour), and the resulting solution was filtered through filter paper to separate the filtrate from the residue on the filter paper. The substance remaining in the filtrate after solvent removal was defined as the xylene-soluble substance at room temperature (XS). Solvent removal can be carried out, for example, by drying the filtrate at 140 °C under a nitrogen stream.

[0020] In tetrahydronaphthalene, the intrinsic viscosity (IV) can be measured at 135°C using a capillary viscometer, such as an automatic capillary viscosity measuring device (SS-780-H1, manufactured by Shibayama Scientific Instruments Co., Ltd.).

[0021] 3) Composition The composition constituting layer P preferably comprises a polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1). Component (A1) is a propylene (co)polymer, comprising 60-90% by weight, which contains 0-5% by weight of comonomer-derived units selected from C2-C10 α-olefins (excluding C3 α-olefins). Furthermore, component (A2) is an ethylene-C4-C10 α-olefin copolymer, comprising 10-40% by weight, which contains 10-35% by weight of C4-C10 α-olefin-derived units.

[0022] The comonomers selected from C2 to C10 α-olefins naturally do not include C3 α-olefins. The upper limit of the comonomer content is preferably 5% by weight or less, more preferably 4% by weight or less, and even more preferably 3% by weight or less. When comonomers are included, the lower limit of the comonomer content is preferably greater than 0% by weight, more preferably 0.1% by weight or more. From an economic point of view, ethylene is preferred when comonomers are included. The composition (A1) can be broadly divided into embodiments containing comonomer-derived units and embodiments not containing comonomer-derived units, which will be described later.

[0023] In the polypropylene resin, the content of component (A1) is 60-90% by weight. If the content of component (A1) is too low, the manufacture of the polypropylene resin will become difficult, and the peel strength may decrease. Therefore, the upper limit of the content of component (A1) is preferably 85% by weight or less, and the lower limit is preferably 65% ​​by weight or more. Therefore, as a preferred range, it can be, for example, 65-85% by weight.

[0024] Component (A2) is an ethylene-C4-C10 α-olefin copolymer containing 10-35% by weight of C4-C10 α-olefin derivative units. While there are no limitations on the C4-C10 α-olefin, 1-butene, 1-hexene, or 1-octene are preferred, and 1-butene is more preferred.

[0025] If the content of the C4-C10 α-olefin derivative units is too high, the peel strength will decrease; if it is too low, the peel stability may decrease. From this perspective, the lower limit of this amount is preferably 15% by weight or more, more preferably 18% by weight or more. Furthermore, the upper limit is preferably 32% by weight or less, more preferably 27% by weight or less. Therefore, as a preferred range, it can be, for example, 15-32% by weight or 18-27% by weight.

[0026] In the polypropylene resin, the content of component (A2) is 10-40% by weight. If the content of component (A2) is too high, the manufacture of the polypropylene resin will become difficult, and the peel strength may decrease. If the content is too low, the peel stability may decrease. From this point of view, the lower limit of this content is preferably 15% by weight or more, and the upper limit is preferably 35% by weight or less. Therefore, the preferred range of the content is, for example, 15-35% by weight.

[0027] The total ethylene content and the content of ethylene-derived units in component (A1) of polypropylene resins can be measured by known methods. The preferred measurement methods are described below. For copolymer samples dissolved in a mixed solvent containing 1,2,4-trichlorobenzene / deuterated benzene, AVANCE III HD400 manufactured by Bruker was used. 13 The C resonance frequency was 100MHz. The measurement was conducted at a temperature of 120℃, a flip angle of 45 degrees, a pulse interval of 7 seconds, a sample rotation speed of 20Hz, and a cumulative number of cycles of 6000. 13 C-NMR spectrum. The preferred mixed solvent is 1,2,4-trichlorobenzene / deuterated benzene / hexamethyldisiloxane = 30 / 10 / 1 (volume ratio).

[0028] Using the spectrum obtained by the above method, the total ethylene content (wt%) of the polypropylene resin is determined according to the method described in Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 15, 1150-1152 (1982). When component (A1) is used as the sample for measurement, the total ethylene content (wt%) obtained by the above method is the ethylene unit content (wt%) of component (A1).

[0029] When component (A1) contains comonomer-derived units other than ethylene, the content of such comonomer units can be determined using the same method as that used for the content of ethylene-derived units.

[0030] In polypropylene resins composed of component (A1) and component (A2), although the ethylene unit content in component (A2) is also measured by known methods, the preferred measurement method will be described below. When component (A1) is a propylene homopolymer, except that the integral intensity T'ββ obtained by the following formula is used instead of the integral intensity Tββ obtained when measuring the total ethylene content of polypropylene resin in the method described in the above literature, the ethylene unit content (wt%) of component (A2) is calculated by the same method as the total ethylene content. T'ββ=0.98×Sαγ×A' / (1-0.98×A') Here, A'=Sαγ / (Sαγ+Sαδ), calculated based on Sαγ and Sαδ as recorded in the aforementioned literature.

[0031] In a polypropylene resin composed of component (A1) and component (A2), where component (A1) contains ethylene units, the content of ethylene-derived units in component (A2) can be calculated using the following formula when the weight ratio (component (A2) / [component (A1) + component (A2)]) can be determined from the polymerization conditions. In the formula, "resin" refers to a polypropylene resin.

[0032] Content of ethylene-derived units in component (A2) (in weight %) = [Total ethylene content of resin - Ethylene-derived unit content of component (A1) × Proportion of component (A1) in resin] / (Proportion of component (A2) in resin)

[0033] When component (A1) is a propylene homopolymer, the weight ratio of component (A2) / [component (A1) + component (A2)] can be calculated using the following formula: Component (A2) / [Component (A1) + Component (A2)] (Unit: weight %) = Total ethylene content of resin / (Ethylene unit content in component (A2) / 100)

[0034] 4) Mechanism of excellent peeling performance Layer P contains a specific amount of component (A2), thus exhibiting excellent peelability. While the rationale is not limited, it is hypothesized that the interfacial bonding strength between components (A1) and (A2) in layer P is lower than the breaking strength of the composition constituting layer P itself, and also lower than the interfacial bonding strength of each layer. Therefore, when an external force is applied to peel off the layer above layer P, cracks preferentially form at the interfaces between components (A1) and (A2) in layer P. These cracks propagate sequentially to the array-dispersed components (A2). It is hypothesized that this results in material failure of layer P, thereby exhibiting excellent peelability.

[0035] As described above, the multilayer sheet involved in this embodiment can be roughly divided into two preferred types according to its composition (A1). Hereinafter, each embodiment will be described separately.

[0036] [First Implementation Method] In this embodiment, component (A1) is a propylene homopolymer. For convenience, component (A1) in this embodiment is referred to as component (A1'), and layer P is referred to as layer P'. That is, in this embodiment, layer P is layer P' containing a polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1'). The polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1') is a multiphase polypropylene in which component (A2) is dispersed in a propylene homopolymer matrix.

[0037] exist Figure 1 In the illustrated embodiment, the biaxially oriented polypropylene layer 12 other than layer P' can be made of known materials. The biaxially oriented polypropylene layer 12 is preferably made of a composition comprising a propylene homopolymer or a composition comprising an ethylene-propylene copolymer, wherein the ethylene-propylene copolymer contains greater than 0 and no more than 5% by weight of ethylene-derived units.

[0038] A more preferred structure of the multilayer sheet in this embodiment is as follows: Figure 2 (1) is shown. In the figure, 12H represents the first biaxially stretched polypropylene layer, 12L represents the second biaxially stretched polypropylene layer, and 10P' represents layer P'. The figure shows a portion of the structure of a multilayer sheet. The multilayer sheet has alternating layers of 12H and 12L, with layer 10P' between the two 12L layers. Layer 12H constitutes the main layer of the multilayer sheet, and layer 12L has the function of bonding the main layers together. Therefore, the softening point Tsh of layer 12H is higher than the softening point Tsl of layer 12L. The softening point Tsp' of layer 10P' preferably satisfies the relationship Tsh≥Tsp'>Tsl. The melting point can be used as an indicator of the softening point. The melting point is defined as the peak temperature of the melting curve measured by DSC when the sample is heated from 30°C to 230°C at a heating rate of 10°C / min.

[0039] To further improve the adhesion between layer 10P' and layer 12L, a polypropylene layer 13 with a softening point lower than Tsp' can be placed between layer 10P' and layer 12L in the multilayer sheet. Figure 2 (2) The polypropylene layer 13 may be made of known materials. Preferably, the polypropylene layer 13 is made of a composition comprising an ethylene-propylene copolymer containing more than 1% by weight and less than 5% by weight of ethylene-derived units.

[0040] Multiple layers 10P' may exist. Layer 10P' can be a non-stretched layer, or a layer that is uniaxially stretched or biaxially stretched. From the viewpoint of improving the rigidity of the multilayer sheet, all layers 10P' are preferably biaxially stretched layers. Furthermore, from the viewpoint of improving the rigidity of the multilayer sheet, when multiple layers 10P' exist, the number of non-stretched layers 10P' is preferably one or less.

[0041] The polypropylene layer 13 can be a non-stretched layer, or a uniaxially stretched or biaxially stretched layer. From the viewpoint of improving the rigidity of the multilayer sheet, all polypropylene layers 13 are preferably biaxially stretched layers. Furthermore, from the viewpoint of improving the rigidity of the multilayer sheet, when there are multiple polypropylene layers 13, the number of non-stretched polypropylene layers 13 is preferably two or less.

[0042] Because the layers are fused together, the multilayer sheet is a single, integrated sheet. Whether the layers of this sheet are fused together can be confirmed, for example, by cross-sectional observation using a polarizing microscope, as described in International Publication No. 2020 / 075755. Furthermore, the integrated multilayer sheet is manufactured, for example, according to the method described in International Publication No. 2022 / 102705. That is, the multilayer sheet is manufactured from a main layer having high rigidity and relatively difficult to melt, and an adhesive layer that is relatively easy to melt and fuses the main layers together. Hereinafter, a preferred manufacturing method in this embodiment will be described.

[0043] The preferred manufacturing method in this embodiment includes: fusing the layers of a precursor formed by laminating a biaxially stretched polypropylene sheet component that forms a biaxially stretched polypropylene layer with a sheet component that forms layer P'.

[0044] 1) Preparation of precursors Figure 3 A summary of the manufacturing method is provided. In the figure, 1' represents the precursor. This precursor 1' is prepared by laminating the following co-extruded layers. These co-extruded layers are prepared according to known methods. Two-layer biaxially oriented polypropylene co-extruded layer Co-extruded layers of polypropylene layer 13 are laminated on both sides of layer 10P'. Three-layer biaxially oriented polypropylene co-extruded layer Two-layer biaxially oriented polypropylene co-extruded layer For ease of understanding, in the figure, the co-extruded layers of precursor 1' have spaces between each other, but in reality, the co-extruded layers are in contact with each other.

[0045] 2) Heating and welding Next, the heating element is brought into contact with the outermost layer of the precursor 1' to heat and fuse the layers together. The melting point Tm of the outermost layer... out The temperature T of the heating element preferably satisfies Tm. out The temperature difference must be at least 4°C (T ≥ 4°C). By satisfying this relationship, good interlayer bonding is achieved. From this perspective, a temperature difference of 6°C or more is more preferable. While there is no upper limit to this temperature difference, from the viewpoint of polypropylene manufacturing, 40°C or less is preferred, and 30°C or less is more preferable. T can be measured by any method, but it is preferable to use a non-contact thermometer such as a radiation thermometer. out This is equivalent to the melting point of the outermost layer. The melting point is defined as the peak temperature of the melting curve measured by DSC at a heating rate of 10°C / min from 30°C to 230°C.

[0046] The temperature T preferably satisfies the relationship Tmh ≥ T ≥ Tml, and more preferably Tmh ≥ T ≥ Tml + 10 (°C). Tmh is the melting point of layer 12H, and Tml is the melting point of layer 12L. If T exceeds the upper limit, the laminate may melt, resulting in a decrease in mechanical properties. Furthermore, if T is less than the lower limit, the layers cannot be sufficiently fused, and the mechanical properties may also decrease. The temperature of the specific heating element is preferably about 120–190°C, more preferably 140–170°C, and even more preferably 150–165°C.

[0047] This process is preferably carried out continuously using a heating roller as the heating element. Specifically, the precursor of the multilayer sheet is passed between two heated rollers to weld the layers together. Alternatively, two rollers can be grouped together, and a heating roller consisting of two or more groups of rollers can be used as the heating element for welding. The applied pressure can be adjusted appropriately. The traction speed during roll forming is not limited, but is preferably about 0.05 to 10 m / min.

[0048] Other methods besides roll forming include press forming and welding forming. Furthermore, when heating and welding sheet-like parts, it is preferable to apply pressure to further promote orientation while suppressing thermal shrinkage. This pressure is adjusted according to the welding temperature.

[0049] The layer on both sides of layer 10P' having polypropylene layers 13 laminated thereon is preferably a co-extruded layer formed by co-extrusion. The total number of layers in the co-extruded layer having the structure of polypropylene layers 13 laminated on both sides of layer 10P' is preferably 3 to 7, more preferably 3 to 5, and even more preferably 3. The thickness of a single layer of layer 10P' is 0.5 μm to 500 μm, preferably 1 μm to 300 μm, and more preferably 2 μm to 200 μm. The thickness of a single layer of polypropylene layer 13 is preferably 2 μm to 200 μm. From the viewpoint of ease of manufacture, in the co-extruded layer in which polypropylene layers 13 are laminated on both sides of layer 10P', when the layers constituting the co-extruded layer are referred to as "structural layers", it is preferable that all structural layers are biaxially stretched layers, all structural layers are uniaxially stretched layers, or all structural layers are non-stretched layers.

[0050] Layers 12H and 12L are preferably co-extruded layers. The total number of layers in the co-extruded layer is preferably 2 to 6, more preferably 2 to 5, further preferably 2 to 4, and particularly preferably 2 to 3. The thickness of a single layer of layer 12H is preferably 20 μm to 300 μm. The thickness of a single layer of layer 12L is preferably 2 μm to 200 μm.

[0051] In the multilayer sheet of this embodiment, the layers corresponding to the main layers are layer 10P' and layer 12H, and the layers corresponding to the adhesive layers are layer 12L and polypropylene layer 13. Let the total thickness (total thickness) of the layers corresponding to the main layers be Dh, and the total thickness (total thickness) of the layers corresponding to the adhesive layers be Dl. If Dh / Dl is too small, the rigidity of the multilayer sheet is insufficient; if this value is too large, the interlayer weldability of the multilayer sheet is insufficient. From the perspective of balancing weldability and rigidity, the ratio is preferably 1 to 30, more preferably 1 to 25, and even more preferably 4 to 15. The thickness of each layer can be the same or different. Furthermore, the thickness of each layer can be appropriately adjusted so that the ratio is within the aforementioned range.

[0052] [Second Implementation] The second embodiment will be described below. For matters not specifically mentioned in the second embodiment, the matters described in the first embodiment will be followed. In this embodiment, component (A1) is a propylene copolymer containing more than 0% by weight and less than 5% by weight of comonomer-derived units selected from C2 to C10 α-olefins (excluding C3 α-olefins). For convenience, component (A1) in this embodiment is referred to as component (A1”), and layer P is referred to as layer P”. That is, in this embodiment, layer P is layer P” containing a polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1”). The polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1”) is a multiphase polypropylene in which component (A2) is dispersed in a propylene homopolymer matrix. In addition, component (A1) may also be a blend of the above-mentioned component (A1’) (propylene homopolymer) and component (A1”). In this case, the weight ratio of component (A1’): component (A1”) is preferably 10 to 50: 90 to 50, more preferably 20 to 40: 80 to 60.

[0053] A more preferred structure of the multilayer sheet in this embodiment is as follows: Figure 4 As shown in (1). In the figure, 10P” represents layer P”. The figure illustrates a portion of the structure of a multilayer sheet. The multilayer sheet has alternating layers of layers 12H and 12L, with layer 10P” between the two layers 12L. The softening point Tsp” of layer 10P” preferably satisfies the relationship Tsh>Tsp”≥Tsl or Tsh>Tsl>Tsp”. Alternatively, although not shown, a polypropylene layer 15 other than layers 12L and 12H may be present between layers 12L and layer 10P”. The polypropylene layer 15 may be made of known materials. Preferably, the polypropylene layer 15 is made of a composition comprising an ethylene-propylene copolymer containing 1 to 5% by weight of ethylene-derived units. The softening point of the polypropylene layer 15 may be higher than Tsl.

[0054] Multilayer sheets can also have a structure such as 10P layer / 14-layer polypropylene / 10P layer. Figure 4 (2) The polypropylene layer 14 can have a softening point higher than Tsp". The polypropylene layer 14 can be made of known materials. Preferably, the polypropylene layer 14 is made of a composition comprising a (ethylene-)propylene (co)polymer containing 0 to 2% by weight of ethylene-derived units. The polypropylene layer 14 can also be layer 12H.

[0055] Multiple layers "10P" may exist. Layer "10P" can be a non-stretched layer, or a layer subjected to uniaxial or biaxial stretching. From the viewpoint of improving the rigidity of the multilayer sheet, all layers "10P" are preferably biaxially stretched layers. Furthermore, from the viewpoint of improving the rigidity of the multilayer sheet, when multiple layers "10P" exist, the number of non-stretched layers "10P" is preferably one or less.

[0056] The polypropylene layer 14 can be a non-stretched layer, or a uniaxially stretched or biaxially stretched layer. From the viewpoint of improving the rigidity of the multilayer sheet, all polypropylene layers 14 are preferably biaxially stretched layers. Furthermore, from the viewpoint of improving the rigidity of the multilayer sheet, when there are multiple polypropylene layers 14, the number of non-stretched polypropylene layers 14 is preferably one or less.

[0057] The preferred manufacturing method in this embodiment includes: fusing the layers of a precursor formed by laminating a biaxially stretched polypropylene sheet component that forms a biaxially stretched polypropylene layer with a sheet component that forms layer P”.

[0058] 1) Preparation of precursors Figure 5 A summary of the manufacturing method is provided. In the figure, 1' represents the precursor. This precursor 1' is prepared by laminating the following co-extruded layers. These co-extruded layers are prepared according to known methods. Two-layer biaxially oriented polypropylene co-extruded layer A co-extruded layer of 10P” is laminated on both sides of the polypropylene layer 14. Three-layer biaxially oriented polypropylene co-extruded layer Two-layer biaxially oriented polypropylene co-extruded layer For ease of understanding, in the figure, the co-extruded layers of precursor 1' have spaces between each other, but in reality, the co-extruded layers are in contact with each other.

[0059] 2) Heating and welding Next, the heating element is brought into contact with the outermost layer of the precursor 1' to heat and fuse the layers together. This process is the same as that described in the first embodiment.

[0060] Layers of 10P” are laminated on both sides of the polypropylene layer 14, preferably co-extruded layers. The total number of layers in the co-extruded layer having the structure of layers of 10P” laminated on both sides of the polypropylene layer 14 is preferably 3 to 7, more preferably 3 to 5, and even more preferably 3. The thickness of a single layer of the polypropylene layer 14 is preferably 20 μm to 300 μm. The thickness of a single layer of 10P” is 0.5 μm to 500 μm, preferably 1 μm to 300 μm, and more preferably 2 μm to 200 μm. From the viewpoint of ease of manufacture, in the co-extruded layer of layers of 10P” laminated on both sides of the polypropylene layer 14, when the layer formed by this co-extruded layer is called a “structural layer”, it is preferable that all structural layers are biaxially stretched layers, all structural layers are uniaxially stretched layers, or all structural layers are non-stretched layers.

[0061] Layers 12H and 12L are preferably composed of co-extruded layers. The total number of layers in the co-extruded layers is preferably 2 to 6, more preferably 2 to 5, further preferably 2 to 4, and particularly preferably 2 to 3. The thickness of a single layer of layer 12H is preferably 20 μm to 300 μm. The thickness of a single layer of layer 12L is preferably 2 μm to 200 μm.

[0062] In the multilayer sheet of this embodiment, the layers corresponding to the main layers are polypropylene layer 14 and layer 12H, and the layers corresponding to the adhesive layers are layer 10P” and layer 12L. Let the total thickness (total thickness) of the layers corresponding to the main layers be Dh, and the total thickness (total thickness) of the layers corresponding to the adhesive layers be Dl. If Dh / Dl is too small, the rigidity of the multilayer sheet is insufficient; if this value is too large, the interlayer weldability of the multilayer sheet is insufficient. From the perspective of balancing weldability and rigidity, the ratio is preferably 1 to 30, more preferably 1 to 25, and even more preferably 4 to 15. The thickness of each layer may be the same or different. Furthermore, the thickness of each layer can be appropriately adjusted so that the ratio is within the specified range.

[0063] [Other layers] Multilayer sheets can have a top layer. The top layer can be applied using known methods. For example, these layers can be applied by coating. There are no restrictions on the type of coating; generally, anything used in the coating industry is acceptable.

[0064] The top layer is preferably the coating used in vehicle body painting. Examples of such coatings include epoxy coatings, polyurethane coatings, or polyester coatings. Depending on the needs, a lower coating (primer), a middle coating, or a top coating (clear coat) may also be provided. When using multi-layer sheets as coating sheets (coating sheets), the surfaces to be coated preferably have functional groups.

[0065] Multilayer sheets can have a surface-active layer applied using standard methods. For example, oxygen-containing functional groups can be imparted to the surface of the multilayer sheet by plasma treatment or corona treatment, thus using it as a surface-active layer. Alternatively, a polypropylene film with functional groups can be prepared and disposed as the outermost layer of the precursor, thereby imparting oxygen-containing functional groups to the surface of the multilayer sheet. This layer can also be used as a surface-active layer.

[0066] The polypropylene film containing oxygen-containing functional groups is obtained by molding known polypropylene, such as maleic anhydride-modified polypropylene or epoxy-modified polypropylene, into a film. While the thickness of this functionalized film is not limited, it is preferably less than 150 μm. Furthermore, the functionalized film may or may not undergo biaxial stretching. In the lamination process, the polypropylene film containing functional groups and the polypropylene sheet without functional groups can be laminated simultaneously, or a laminated sheet can be manufactured by laminating the polypropylene sheet without functional groups beforehand, and then the polypropylene film containing functional groups can be laminated onto the surface of this sheet. However, considering workability, the method of simultaneous lamination is preferred.

[0067] The manufacturing method described above may also include known steps such as cooling the multilayer sheet obtained in the previous process. While the cooling method is not limited, examples include natural cooling at room temperature and cold pressing at room temperature or 10–20°C.

[0068] (3) Mechanical properties and heat resistance Multilayer sheets and molded bodies such as containers obtained from multilayer sheets possess excellent mechanical properties. For example, the sheets and molded bodies are rigid, and the flexural modulus (JIS K 7171) is preferably 2,000 MPa or more, more preferably 2,500 MPa or more. Furthermore, multilayer sheets also exhibit excellent cold-impact resistance. For example, multilayer sheets and molded bodies preferably have a flexural modulus of 10 KJ / m². 2 The above Charpy impact strength (-30℃, JISK7111-1) is preferred. Furthermore, the multilayer sheet preferably has a strength of 0.90–0.93 g / cm³ (0.90–1.0 g / cm³ when containing inorganic fillers). 3 The density.

[0069] (4) Surface Functional groups can be imparted to the surface of the multilayer sheet. Oxygen-containing functional groups are preferred. Examples of oxygen-containing functional groups include carboxyl groups, carboxylic acid ester groups, acid anhydride groups, hydroxyl groups, aldehyde groups, or epoxy groups. These functional groups improve the adhesion of the multilayer sheet to other materials. In particular, when a coating is applied to a layer containing functional groups, it is preferred because the adhesion between the layer and the coating is improved.

[0070] (5) Nucleating agent Layer P and other layers can be composed of a composition containing a nucleating agent, or of a composition or polymer without a nucleating agent. A nucleating agent is an additive used to increase the crystalline component in a resin to improve rigidity. Known additives can be used as such additives. From an economic point of view, the amount of nucleating agent is preferably 1 part by weight or less relative to 100 parts by weight of the polymer.

[0071] (6) Other additives The composition constituting each layer may contain, to a extent that does not impair the desired effect, conventional additives commonly used in polyolefins, such as antioxidants, chlorine absorbers, heat stabilizers, light stabilizers, ultraviolet absorbers, internal lubricants, external lubricants, anti-blocking agents, antistatic agents, antifogging agents, flame retardants, dispersants, copper inhibitors, neutralizers, plasticizers, crosslinking agents, peroxides, oils, organic pigments, or inorganic pigments. The amount of each additive can be a known quantity. Furthermore, to a extent that does not impair the desired effect, it may also contain synthetic resins other than the aforementioned polypropylene resins (e.g., modified polypropylene) or synthetic rubbers. This synthetic resin or synthetic rubber may be one type or two or more types.

[0072] 2. Applications Multilayer sheets exhibit high orientation and a specific high-order structure in the in-plane direction, with minimal dependence of orientation on thickness, resulting in lightweight materials and excellent mechanical properties. Furthermore, their excellent peelability, allowing for easy removal of the top layer, contributes to their superior recyclability. Therefore, multilayer sheets combine excellent recyclability and rigidity, making them a viable alternative to steel sheets in automotive parts, electrical and electronic components, and housing components. Additionally, multilayer sheets allow for thin-walled, lightweight construction and excellent resealability, making them useful as food packaging materials, containers, and lids. Moreover, their high rigidity makes them valuable for use in grocery, daily necessities, appliance components, toy components, furniture components, building material components, packaging components, industrial materials, logistics materials, and agricultural materials.

[0073] Since multi-layer sheets can be used as a recyclable alternative to steel sheets, the recycling method will be explained below using automotive materials as an example.

[0074] While the peel strength is not limited, from the viewpoint of balancing high adhesion and high peel strength, in one embodiment it is preferably 15-50 N / 15 mm, more preferably 15-40 N / 15 mm, and even more preferably 15-35 N / 15 mm. The peel strength is determined by performing a 180-degree peel test using a strip test piece with a width of 15 mm. In one embodiment, the distance between the clamps is 50 mm, the clamp moving speed is 300 mm / min, and the tensile length is 100 mm. The test value is the integrated average load of the initial load and the 50 mm stability interval during material failure.

[0075] Peel strength is preferably measured by the following method. A 180-degree peel test was conducted. Multi-layer sheets were cut into strips 15 mm wide to serve as test pieces. The top and bottom layers were clamped in fixtures with a 50 mm distance between the fixtures. A tensile test was performed by moving the fixtures at a speed of 300 mm / min. The test piece was stretched to at least 100 mm, and the result was recorded as the test value. The peel strength was defined as the initial load and the integral average load over the 50 mm stability zone during material failure. For example, an AUTOCOM universal testing machine manufactured by TSE Co., Ltd. could be used as the testing apparatus.

[0076] Because of the good interlayer adhesion of the multilayer sheet, there is almost no discontinuity between the layers. Therefore, it can be processed as a single sheet. Example

[0077] 1. Preparation of polypropylene resin compositions [Polymer a] The solid catalyst used in the polymerization was prepared according to the method described in Example 1 of Japanese Patent Application Publication No. 2011-500907. This solid catalyst was prepared by supporting Ti and diethyl-2,3-(diisopropyl)succinate as an internal electron donor onto MgCl2 using the method described in the aforementioned patent publication. The solid catalyst was contacted with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) at a weight ratio of TEAL to solid catalyst of 11 and a TEAL / DCPMS weight ratio of 15 at 12°C for 24 minutes. The resulting catalyst system was then suspended in liquid propylene at 20°C for 5 minutes to perform prepolymerization. The resulting prepolymer was then introduced into a polymerization reactor, followed by the feeding of hydrogen, propylene, and ethylene. Then, under polymerization conditions of 80°C, a hydrogen concentration of 0.17 mol%, and an ethylene concentration of 0.08 mol%, the polymerization pressure was adjusted to obtain polymer a, which is a propylene-ethylene copolymer. Polymer a (component (A1), hereinafter also referred to as "PP component") contains 0.36% by weight of ethylene-derived units (hereinafter also referred to as "C2"), and has an MFR (temperature 230°C, load 2.16 kg) of 4.4 g / 10 min.

[0078] [Polymer b] A solid catalyst for polymerization was prepared by means of the method described in Example 1 of European Patent No. 674991. This solid catalyst was prepared by supporting Ti and diisobutyl phthalate, as an internal electron donor, on MgCl2 according to the method described in the aforementioned patent publication. The solid catalyst was contacted with TEAL and dicyclopentyldimethoxysilane (DCPMS) at -5°C for 5 minutes in a weight ratio of TEAL to solid catalyst of 1:1 and TEAL / DCPMS of 3. The resulting catalyst system was then suspended in liquid propylene at 20°C for 5 minutes for prepolymerization. The resulting prepolymer was then fed into a polymerization reactor, followed by hydrogen, propylene, and ethylene. Polymer b, a propylene-ethylene copolymer, was obtained by adjusting the polymerization pressure at a polymerization temperature of 75°C, a hydrogen concentration of 0.44 mol%, and an ethylene concentration of 1.07 mol%. Polymer b (PP component) contained 4.0 wt% C2 and had an MFR (temperature 230°C, load 2.16 kg) of 7.5 g / 10 minutes.

[0079] [Polymer c] Except for changing the hydrogen concentration to 0.25 mol% and the ethylene concentration to 0.44 mol%, the same procedure was performed as for polymer b to obtain polymer c. Polymer c contains 2.0 wt% C2 and has an MFR (temperature 230°C, load 2.16 kg) of 5.9 g / 10 min.

[0080] [Polymer x1] A solid catalyst, comprising Ti and diisobutyl phthalate as an internal electron donor, supported on MgCl2, was prepared according to the method described in Example 5 of European Patent No. 728769. Next, the solid catalyst was contacted with triethylaluminum (TEAL) as an organoaluminum compound and dicyclopentyldimethoxysilane (DCPMS) as an external electron donor compound at 12°C for 24 minutes, with a weight ratio of triethylaluminum (TEAL) to the solid catalyst of 20 and a weight ratio of TEAL / DCPMS of 10. The resulting catalyst system was then suspended in liquid propylene at 20°C for 5 minutes to perform prepolymerization. The resulting prepolymer was introduced into the first stage of a polymerization apparatus having two polymerization reactors connected in series, and ethylene was fed into the liquid propylene to produce a propylene-ethylene random copolymer as component (A1). In the second stage gas-phase polymerization reactor, an ethylene-1-butene copolymer as component (A2) was produced. During polymerization, temperature and pressure were adjusted, and hydrogen was used as a molecular weight regulator. The polymerization temperature to reactant ratios were as follows: In the first reactor, the polymerization temperature, hydrogen concentration, and ethylene concentration were 70°C, 0.060 mol%, and 0.84 mol%, respectively; in the second reactor, the polymerization temperature, H2 / C2, and C4 / (C2+C4) ratios were 80°C, 0.26 molar ratio, and 0.48 molar ratio, respectively. Furthermore, by adjusting the polymerization times in the first and second stages, the content of component (A2) was made to reach 18% by weight.

[0081] [Polymer x2] In the first reactor stage, ethylene was not fed, and the hydrogen concentration was changed to 0.05 mol% to polymerize propylene homopolymer. In the second reactor stage, the H2 / C2 and C4 / (C2+C4) ratios were changed to 0.22 and 0.52 molar ratios, respectively. Simultaneously, by adjusting the polymerization times of the first and second stages, the content of the ethylene-1-butene copolymer (as component A2) was increased to 30% by weight. Otherwise, polymer x2 was obtained using the same manufacturing method as polymer x1.

[0082] [Polymer x3] In the first reactor stage, the hydrogen concentration was changed to 0.83 mol%. In the second reactor stage, the H2 / C2 and C4 / (C2+C4) ratios were changed to 0.30 and 0.40 molar ratios, respectively. Simultaneously, by adjusting the polymerization times of the first and second stages, the content of the ethylene-1-butene copolymer (as component A2) was increased to 32% by weight. Otherwise, polymer x3 was obtained using the same manufacturing method as polymer x1.

[0083] [Preparation of polymer compositions A-C, X1-X3] Relative to the 100 parts by weight of each polymer (a-c, x1-x3) obtained above, 0.2 parts by weight of antioxidant (BASF, B225), 0.05 parts by weight of neutralizing agent (calcium stearate, Danan Chemical Industry Co., Ltd.), and as crystal nucleating agents: 0.05 parts by weight of Millad NX8000J (Milliken Japan), polymer a; 0.10 parts by weight of ADK STAB NA-21 (ADEKA), polymer c; and 0.25 parts by weight of ADK STAB NA-71 (ADEKA), polymer x1 were mixed using a Henschel mixer for 1 minute. The mixture was then stirred using an NVC mixer manufactured by Nakatani Machinery Co., Ltd. A 50mm single-screw extruder was used to melt and knead the mixture at a barrel temperature of 230°C. The extruded filaments were then cooled in water and cut using a granulator to obtain granular resin compositions (polymer compositions A to C, X1 to X3).

[0084] [Resin compositions Y3, Y5-Y8, Z] Polymer compositions X1 to X3 were prepared according to the weight ratios shown in Table 1. 0.1 parts by weight of dimyristicol dithiodipropionate (DMTP, manufactured by Mitsubishi Chemical Corporation) was further added as an antioxidant, and the mixture was stirred for 1 minute using a Henschel mixer to obtain a mixture. Next, this mixture was fed to an extruder (TEX-30α co-rotating twin-screw extruder manufactured by Nippon Steel Corporation, with the screw temperature set at 230°C) for melt mixing (twin-screw melt mixing). Furthermore, the molten mixture was extruded from the extruder, cooled to form a filament, and the filament was cut to prepare granules of the resin composition.

[0085] 2. Preparation of biaxially stretched sheets [Biaxially stretched sheet AAB] Use 25mm Three types of 3-layer film / sheet forming machines (manufactured by Thermo Plastics Industry Co., Ltd.) were used to co-extrude unstretched sheets (10cm x 10cm or larger) with a thickness of 2.5mm using polymer composition A / polymer composition A / polymer composition B at a forming temperature of 230°C. Using a film stretching device (Brückner KARO-IV), the unstretched sheet was simultaneously biaxially stretched (3.5x x 3.5x) at 165°C to obtain a co-extruded biaxially stretched sheet with a thickness of 0.20mm. The thickness ratio was 1:18:1. Furthermore, since the two polymer composition A layers are integrated, this sheet is technically a two-layer sheet.

[0086] [Other biaxial stretch sheets] As shown in Table 2, biaxially oriented sheets were manufactured in the same manner as biaxially oriented sheet AAB, except for changes in the polymer and conditions used. Hereinafter, biaxially oriented sheet AAB will also be abbreviated as "AAB". The same applies to other sheets.

[0087] Unstretched Sheet CX2C U -3] Use 25mm Three types of 3-layer film / sheet forming machines (manufactured by ThermoPlastics Industrial Co., Ltd.) are used to co-extrude polymer compositions C / X2 / C at a forming temperature of 230°C to obtain sheets with a thickness of 0.060 mm (size 10 cm × 10 cm or more). The thickness ratio is 1:1:1.

[0088] [Unstretched sheet X] 3U ] Use 25mm A single-layer film / sheet forming machine (manufactured by ThermoPlastics Industrial Co., Ltd.) extrudes a polymer composition X3 at a forming temperature of 230°C to obtain a sheet with a thickness of 0.060 mm (size 10 cm × 10 cm or more).

[0089] Unstretched sheet Y 8U ] Use 25mm A single-layer film / sheet forming machine (manufactured by ThermoPlastics Industrial Co., Ltd.) extrudes polymer composition Y8 at a forming temperature of 230°C to obtain sheets with a thickness of 0.060 mm (size 10 cm × 10 cm or more).

[0090] 3. Manufacturing of multi-layer sheets [Example 2-1] A precursor with the following layer structure was prepared: AAB / X1AX1 / / X1AX1 / 9 pieces BAB / BAA " / / " indicates the interface where a 55μm thick polyimide tape was inserted. Since the polyimide tape does not fuse with polypropylene, the location where the polyimide tape was inserted is used as the clamping point in the peel test.

[0091] Using a molding machine manufactured by Shoji Corporation, heated to 163°C as the heating element, the layers of the precursor were heated and fused together to produce a multilayer sheet as a laminate. During molding, the two sides of the precursor were clamped from the outside using a 3mm thick aluminum plate and a 1mm thick steel plate, and then pressed at 4MPa for 2 minutes. This produced a multilayer sheet with a thickness of 2.3mm. The peel strength of this multilayer sheet was measured using the method described later. The results are shown in Table 3. Material failure was observed in layer X1, adjacent to the " / / " and located on the AAB side, confirming that this layer served as a peel layer. The results show that the peel strength is 34.9 N / 15mm at the initial load, and the average peel load over a length of 50mm is 33.2 N / 15mm, clearly demonstrating both excellent adhesion and excellent peelability.

[0092] [Examples 2-2 to 2-10] The layer structure design is shown in Table 3. Multilayer sheets were manufactured and evaluated in the same manner as in Example 2-1. The multilayer sheets shown in Table 3 are equivalent to the multilayer sheets of the second embodiment. In Examples 2-2 to 2-7, layers Y7, Z, Y5, Y7, Z, and Z respectively function as release layers. In Examples 2-8 to 2-10, layer X... 3U Layer Y 8ULayers Y1 and Y2, and Y3, respectively act as release layers. The results show that these multilayer sheets possess both excellent adhesion and excellent peelability.

[0093] [Examples 1-1 to 1-3] The multilayer sheets were manufactured and evaluated in the same manner as in Example 2-1, with the layer structure shown in Table 4. The multilayer sheets shown in Table 4 are equivalent to the multilayer sheets of the first embodiment. In these examples, layer X2 serves as a release layer. The results show that these multilayer sheets all possess both excellent adhesion and excellent peelability.

[0094] [Comparative Examples 1-7] The multilayer sheet was manufactured and evaluated in the same manner as in Example 2-1, with the layer structure shown in Table 5. The results showed that the multilayer sheet had poor peelability.

[0095] The layer structure of each example is shown below: Example 1-1: AAB / CX2C / / BAB×9 / BAA Example 1-2: AAB / CX2C / / BAB×2 / BAA Examples 1-3: AAB / CX2C U -3 / / BAB×9 / BAA Example 2-1: AAB / X1AX1 / / X1AX1 / BAB×9 / BAA Example 2-2: AAB / Y7AY7 / / Y7AY7 / BAB×9 / BAA Example 2-3: AAB / ZAZ / / ZAZ / BAB×9 / BAA Examples 2-4: AAB / CY5C / / BAB×9 / BAA Examples 2-5: AAB / CY7C / / BAB×9 / BAA Examples 2-6: AAB / CZC / / BAB×9 / BAA Examples 2-7: CAC×4 / CZC / / BAB×9 / BAA Examples 2-8: AAB / X 3U / / BAB×9 / BAA Examples 2-9: AAB / Y 8U / / BAB×9 / BAA Example 2-10: AAB / BAB / Y3AY3 / / Y3AY3 / BAB×9 / BAA

[0096] Comparative Example 1: X2AX2 / / X2AX2 / BAB×9 / BAA Comparative Example 2: Y3AY3 / / Y3AY3 / BAB×9 / BAA Comparative Example 3: Y6AY6 / / Y6AY6 / BAB×9 / BAA Comparative Example 4: Y7AY7 / / Y7AY7 / BAB×9 / BAA Comparative Example 5: ZAZ / / ZAZ / BAB×9 / BAA Comparative Example 6: CX2C-2 / / BAB×9 / BAA Comparative Example 7: AAB / / BAB × 4 / BAA

[0097] [Table 1-1] Table 1 [Table 1-2]

[0098] [Table 2]

[0099] [Table 3-1]

[0100] [Table 3-2]

[0101] [Table 4]

[0102] [Table 5]

[0103] [Evaluation Method] 1) Total ethylene content of component (A1) + component (A2) and ethylene-derived unit content of component (A1). The measurement shall be performed in accordance with the aforementioned method. 2) Ethylene unit content in component (A2) The measurements were performed according to the aforementioned method. The content (wt%) of α-olefin units (C4–C10) of component (A2) was calculated from the content (wt%) of 100-ethylene units.

[0104] 3) Weight ratio of component (A2) / [component (A1) + component (A2)] The measurements were performed using the method described above. When component (A1) contains ethylene units, the values ​​were estimated using the polymerization conditions.

[0105] 4) MFR The MFR of polypropylene resin was determined by adding 0.05 g of H-BHT manufactured by Honshu Chemical Industry Co., Ltd. to 5 g of the sample, homogenizing it by dry mixing, and measuring it at a temperature of 230°C and a load of 2.16 kg according to JISK7210-1 and based on JISK6921-2. The MFR of polypropylene resin compositions was measured according to JISK 7210-1, based on JISK 6921-2, at a temperature of 230°C and a load of 2.16 kg.

[0106] 5) Peel test A 180-degree peel test was performed using an AUTOCOM universal testing machine manufactured by TSE Corporation. The sheet material manufactured in the previous example was cut into strips with a width of 15 mm to serve as test pieces. The top and bottom layers were clamped together with fixtures. The distance between the fixtures was set to 50 mm, and the fixtures were moved at a speed of 300 mm / min to conduct a tensile test. Tension exceeding 100 mm was taken as the test value, and the average value of the test force within the 50 mm stable range during the material failure process was used.

[0107] 6) Flexural modulus Measurements were taken in accordance with JISK7171. Multilayer sheets were cut to a width of 10 mm and a length of 80 mm to serve as test pieces. The flexural modulus was measured using a precision universal testing machine (Autograph AG-X10kN) manufactured by Shimadzu Corporation, under conditions of 23°C, 50% relative humidity, 32 mm distance between support points, and a test speed of 2 mm / min.

[0108] 7) Charpy impact strength The measurement was performed using a multi-layered sheet, cut to a width of 10 mm and a length of 80 mm, obtained through the same procedure as the test piece used for measuring the flexural modulus. Specifically, according to JISK7111-1, a 2 mm notch was punched in the width direction of the multi-layered sheet, cut to a width of 10 mm and a length of 80 mm, using a notching tool A-4 manufactured by Toyo Seiki Co., Ltd., to obtain a test piece of shape A for measurement. The Charpy impact strength (lateral impact, 1eA method) was measured using a fully automatic impact testing machine with a cryogenic bath (No. 258-ZA) manufactured by Yasuda Seiki Co., Ltd., at a temperature of -30°C.

[0109] 8) Density Measurements were taken according to JISK7112. Symbol Explanation

[0110] 1. Multi-layer sheet 10th floor P 10P' layer P 10P" layer P" 12 Biaxially oriented polypropylene layers 12H First biaxially stretched polypropylene layer 12L Second Biaxially Stretched Polypropylene Layer 13 Polypropylene layer 14 Polypropylene layer 1' Precursor

Claims

1. A multilayer polypropylene sheet with a thickness of 0.5–5 mm, comprising: Multiple biaxially stretched polypropylene layers, and Layer P with one or more layers, where... Layer P is composed of a composition comprising a polypropylene resin and an ethylene-C4 to C10 α-olefin copolymer. It has the following characteristics: 1) The thickness of layer P is 0.5–500 μm; 2) At least one of the layers P exists at a position satisfying 2% ≤ r / R. With the surface of the multilayer sheet as the origin, r is the distance from the origin to the interface between layer P and other layers in the thickness direction on the side of the origin, and R is the total thickness of the multilayer sheet, wherein the origin is the surface when r is at its minimum. 3) In the composition constituting layer P, the content of the ethylene-C4 to C10 α-olefin copolymer is 10 to 40% by weight.

2. The polypropylene multilayer sheet according to claim 1, wherein, The MFR (230°C, 2.16 kg load) of the composition constituting layer P is 0.5–30 g / 10 minutes. The intrinsic viscosity of the xylene-soluble component in the composition at room temperature is 0.5–4 dL / g.

3. The polypropylene multilayer sheet according to claim 2, wherein, The composition constituting layer P comprises a polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1). The component (A1) is a propylene (co)polymer, accounting for 60-90% by weight, which contains 0-5% by weight of comonomer-derived units selected from C2-C10 α-olefins but excluding C3 α-olefins. The component (A2) is an ethylene-C4-C10 α-olefin copolymer containing 10-35% by weight of C4-C10 α-olefin derivative units, accounting for 10-40% by weight.

4. The polypropylene multilayer sheet according to claim 1 or 2, wherein, The layer P is a layer that has undergone biaxial stretching.

5. The polypropylene multilayer sheet according to claim 1 or 2, wherein, The polypropylene multilayer sheet is formed by a method comprising fusing the layers of a precursor obtained by laminating a biaxially oriented polypropylene sheet component constituting the biaxially oriented polypropylene layer with a sheet component forming the layer P. The precursor comprises a co-extruded layer in which polypropylene layers are laminated on both sides of layer P, and The layer P is a layer P' containing a polypropylene resin, which has a phase structure in which component (A2) is dispersed in component (A1'). The component (A1') is a propylene polymer, accounting for 60-90% by weight. The component (A2) is an ethylene-C4-C10 α-olefin copolymer containing 10-35% by weight of C4-C10 α-olefin derivative units, accounting for 10-40% by weight.

6. The polypropylene multilayer sheet according to claim 5, wherein, The co-extruded layer is a layer that has undergone biaxial stretching.

7. The polypropylene multilayer sheet according to claim 1 or 2, wherein, The polypropylene multilayer sheet is formed by a method comprising fusing the layers of a precursor obtained by laminating a biaxially oriented polypropylene sheet component constituting the biaxially oriented polypropylene layer with a sheet component forming the layer P. The layer P is a layer P” containing a polypropylene resin, which has a phase structure in which component (A2) is dispersed in component (A1”). The component (A1”) is a propylene copolymer, accounting for 60-90% by weight. This propylene copolymer contains greater than 0 and no more than 5% by weight of comonomer-derived units selected from C2-C10 α-olefins but excluding C3 α-olefins. The component (A2) is an ethylene-C4-C10 α-olefin copolymer containing 10-35% by weight of C4-C10 α-olefin derivative units, accounting for 10-40% by weight.

8. The polypropylene multilayer sheet according to claim 7, wherein, The precursor comprises a co-extruded layer of layer P” laminated on both sides of the biaxially stretched polypropylene layer.

9. The polypropylene multilayer sheet according to claim 1 or 2, wherein, The layer P contains less than 10% by weight of inorganic filler material.

10. A molded body obtained by molding the polypropylene multilayer sheet as described in claim 1.

11. The molded article according to claim 10, which is an automotive part.

12. A stripping method, wherein, Using layer P as a release layer, at least one layer is peeled off from the polypropylene multilayer sheet of claim 1 or 2 or from the molded body of claim 10.

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