Polypropylene multilayer sheet exceptional in recyclability, and molded body thereof

Abstract

Provided is a polypropylene multilayer sheet having a thickness of 0.5-5 mm, the polypropylene multilayer sheet having a plurality of biaxially stretched polypropylene layers and one or more layers P configured from a composition that contains a polypropylene-based resin and an ethylene-C4-C10 α-olefin copolymer, and having the following characteristics: 1) the thickness of the layer P is 0.5-500 μm; 2) at least one layer P is present at a position satisfying 2% ≤ r / R (where r is the distance from the surface of the multilayer sheet serving as an origin to the position of the origin-side interface between the layer P and another layer in the thickness direction, and R is the total thickness of the multilayer sheet, the origin being a surface where r is minimized); and 3) the ethylene-C4-C10 α-olefin copolymer content of the layer P is 10-40 wt%.

Description

Highly recyclable polypropylene multilayer sheet and molded product thereof

[0001] The present invention relates to a polypropylene multilayer sheet and a molded article thereof which are highly recyclable.

[0002] To improve the design, plastics are commonly painted or decorated with films. However, when recycling such plastic molded bodies, the coatings and films must be removed. A method for peeling coatings and the like is known in which an ethylene-butene copolymer is used as a release layer (see, for example, Patent Document 1). Patent Document 2 also discloses a polypropylene multilayer sheet having an easy-peel layer.

[0003] JP 2007-237590 A International Publication No. 2023 / 127972

[0004] If the peel strength of the release layer in an article is too low, the coating film or the like will peel off during use of the article. On the other hand, if the peel strength of the release layer in an article is too high, it becomes difficult to peel off the coating film or the like. Particularly in the field of automotive exteriors, if the peel strength is too low, the paint may peel off due to external stimuli in the natural environment or high-pressure car washes, while there is a demand for peeling off the coating film when recycling. In view of these circumstances, an object of the present invention is to provide a product with an appropriate peel strength.

[0005] The inventors have found that the above-mentioned problems can be solved by optimizing the layer structure of the multilayer sheet. That is, the above-mentioned problems are solved by the following present invention. Aspect 1 A polypropylene multilayer sheet having a thickness of 0.5 to 5 mm, comprising: a plurality of biaxially oriented polypropylene layers; and one or more layers P composed of a composition containing a polypropylene resin and an ethylene-C4 to C10 α-olefin copolymer, and having the following properties: 1) the thickness of each layer P is 0.5 to 500 μm; 2) at least one layer P is located at a position satisfying 2%≦r / R, (r is the distance from the surface of the multilayer sheet as the origin to the interface between layer P and another layer on the side of the origin in the thickness direction, and R is the total thickness of the multilayer sheet, where the origin is the surface at which r is minimum); and 3) the content of the ethylene-C4 to C10 α-olefin copolymer in the composition constituting each layer P is 10 to 40 wt %. Aspect 2: The polypropylene multi-layer sheet according to Aspect 1, wherein the composition constituting Layer P has an MFR (230°C, 2.16 kg load) of 0.5 to 30 g / 10 min, and the intrinsic viscosity of the room temperature xylene soluble matter in the composition is 0.5 to 4 dL / g. Aspect 3: The polypropylene multi-layer sheet according to Aspect 2, wherein the composition constituting Layer P comprises a polypropylene-based resin having a phase structure in which component (A2) is dispersed in component (A1), wherein component (A1) is 60 to 90 wt % of a propylene (co)polymer containing 0 to 5 wt % of units derived from a comonomer selected from C2 to C10 α-olefins (excluding C3-α-olefins), and component (A2) is 10 to 40 wt % of an ethylene-C4 to C10 α-olefin copolymer containing 10 to 35 wt % of units derived from a C4 to C10 α-olefin. Aspect 4: The polypropylene multi-layer sheet according to any of Aspects 1 to 3, wherein Layer P is a biaxially stretched layer.Aspect 5: The polypropylene multilayer sheet according to any one of Aspects 1 to 4, wherein the polypropylene multilayer sheet is formed by a process comprising fusing together layers of a precursor laminated with a biaxially oriented polypropylene sheet member forming the biaxially oriented polypropylene layer and a sheet member forming layer P, wherein the precursor comprises a coextruded layer in which polypropylene layers are laminated on both sides of layer P, and layer P is layer P' comprising a polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1'), wherein component (A1') is 60 to 90% by weight of a propylene polymer, and component (A2) is 10 to 40% by weight of an ethylene-C4 to C10 α-olefin copolymer containing 10 to 35% by weight of units derived from a C4 to C10 α-olefin. Aspect 6: The polypropylene multilayer sheet according to Aspect 5, wherein the coextruded layer is a biaxially oriented layer. Aspect 7: The polypropylene multi-layer sheet according to any one of Aspects 1 to 4, wherein the polypropylene multi-layer sheet is formed by a method comprising fusing together layers of a precursor laminated with a biaxially oriented polypropylene sheet-like member forming the biaxially oriented polypropylene layer and a sheet-like member forming the layer P, wherein the layer P is a layer P″ comprising a polypropylene resin having a phase structure in which component (A2) is dispersed in component (A1″), and the component (A1″) is 60 to 90% by weight of a propylene copolymer containing more than 0 to 5% by weight of units derived from a comonomer selected from C2 to C10 α-olefins (excluding C3-α-olefins), and the component (A2) is 10 to 40% by weight of an ethylene-C4 to C10 α-olefin copolymer containing 10 to 35% by weight of units derived from a C4 to C10 α-olefin. Aspect 8: The polypropylene multi-layer sheet according to Aspect 7, wherein the precursor comprises a coextruded layer in which the layer P″ is laminated on both sides of the biaxially oriented polypropylene layer. Aspect 9: The polypropylene multilayer sheet according to any one of Aspects 1 to 8, wherein Layer P contains 10% by weight or less of an inorganic filler. Aspect 10: A molded article obtained by molding the polypropylene multilayer sheet according to any one of Aspects 1 to 9. Aspect 11: The molded article according to Aspect 10, which is an automobile part. Aspect 12: A method for peeling at least one layer from the polypropylene multilayer sheet according to any one of Aspects 1 to 9 or the molded article according to Aspect 10 or 11, wherein Layer P is used as a release layer.

[0006] The present invention can provide a product having an appropriate peel strength.

[0007] Fig. 1 is a diagram illustrating an outline of a polypropylene multilayer sheet; Fig. 2 is a diagram illustrating a polypropylene multilayer sheet of a first embodiment; Fig. 3 is a diagram illustrating an outline of a method for producing a polypropylene multilayer sheet of a first embodiment; Fig. 4 is a diagram illustrating a polypropylene multilayer sheet of a second embodiment; Fig. 5 is a diagram illustrating an outline of a method for producing a polypropylene multilayer sheet of a second embodiment.

[0008] In this disclosure, "X to Y" includes the end values, i.e., X and Y. Sheet and film are used synonymously, but in particular, a film-like member having a thickness of 150 μm or more may be referred to as a sheet, and a film-like member having a thickness of less than 150 μm may be referred to as a film. Furthermore, sheets and films may be collectively referred to as "sheet-like members."

[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, peeling properties are poor, making recycling difficult. Furthermore, if the sheet is too thick, manufacturing 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. In other words, preferred thickness ranges include 0.7 to 4.5 mm or 1 to 4 mm. The thickness of the multilayer sheet is adjusted appropriately depending on the application.

[0010] (2) Multilayer structure The multilayer sheet includes multiple biaxially oriented polypropylene layers and one or more layers P composed of a composition containing a polypropylene-based resin and an ethylene-C4 to C10 α-olefin copolymer. The layers P are non-oriented layers, uniaxially oriented layers, or biaxially oriented layers. The biaxially oriented polypropylene layers are composed of a polypropylene-based resin or a composition thereof. The polypropylene-based resin is a resin whose main component is polypropylene.

[0011] (2-1) Location of Layer P Layer P exists at a specific location and functions as a peeling layer. Therefore, the multilayer sheet can be divided into layers above and below Layer P. Details of the peeling method will be described later; at least one Layer P exists at a location that satisfies 2%≦r / R. As shown in FIG. 1 , r is the distance from the surface of the multilayer sheet as the origin to the interface between Layer P and another layer on the side of the origin in the thickness direction. The multilayer sheet has two surfaces, and the origin is defined as the surface that minimizes r. R is the total thickness of the multilayer sheet. In the figure, 1 represents the multilayer sheet, 10 represents Layer P, and 12 represents the biaxially oriented polypropylene layer. When this relationship is satisfied, an appropriate peel strength is achieved. From this perspective, the lower limit of r / R is preferably 5% or more, more preferably 7% or more. The upper limit of r / R is preferably 40% or less, more preferably 30% or less. Therefore, the preferable range of r / R is, for example, 5 to 40% or 7 to 30%.

[0012] When multiple layers P are present, the position of the layer that exhibits peeling properties with an appropriate peel strength during peeling can be determined by controlling the thickness of each layer, etc. Furthermore, the position can be determined by providing a starting point in a specific layer, as in a peel test. For example, if a starting point is provided in layer P, material fracture occurs in that layer P, and peeling properties are exhibited with an appropriate peel strength. Furthermore, if a starting point is provided in a layer adjacent to layer P, material fracture occurs in the layer P adjacent to that layer, and peeling properties are exhibited with an appropriate peel strength. Hereinafter, the exhibiting of peeling properties with an appropriate peel strength is also referred to as having excellent peeling properties.

[0013] (2-2) Thickness of Layer P The thickness of Layer P is 0.5 to 500 μm. If Layer P is too thin, excellent peeling properties cannot be obtained, making recycling difficult. Furthermore, if Layer P is too thick, the peel strength becomes too high, making recycling difficult. 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, preferred thickness ranges can be 1 to 300 μm or 2 to 200 μm, for example.

[0014] (2-3) Composition Constituting Layer P Layer P is composed of a composition containing 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 wt %. 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 production of the multilayer sheet becomes difficult. From this perspective, the lower limit of this amount is preferably 15 wt % or more. The upper limit of this amount is preferably 35 wt % or less. In other words, a preferred range of the amount is 15 to 35 wt %.

[0015] Layer P may or may not contain an inorganic filler. Layer P preferably does not contain an inorganic filler, but if it does contain an inorganic filler, the amount of the inorganic filler is preferably 10 wt% or less, more preferably 3 wt% or less, and even more preferably 2 wt% or less, based on the weight of Layer P. In this case, the lower limit of the amount of the inorganic filler may be more than 0 wt%, but is preferably 0.1 wt% or more. The inorganic filler is not limited, but the following can preferably be used.

[0016] Powdered fillers such as calcium silicate, aluminum silicate, silicic acid, synthetic silicic acid or silicates such as silicic anhydride; plate-like fillers such as talc, kaolinite, clay, mica; whisker-like fillers such as basic magnesium sulfate whiskers, calcium titanate whiskers, aluminum borate whiskers, sepiolite, PMF (Processed Mineral Filler), xonotlite, potassium titanate, and ellestadite; balloon-like fillers such as glass balloons and fly ash balloons; and fibrous fillers such as glass fiber.

[0017] 1) MFR The MFR (230°C, 2.16 kg load) of the composition constituting Layer P is preferably 0.5 to 30 g / 10 min. If the MFR exceeds the upper limit, it becomes difficult to prepare the polypropylene sheet member used as the raw material for the multilayer sheet, and peel stability may also decrease. Furthermore, if the MFR is below the lower limit, it may become difficult to prepare the polypropylene sheet member. From this perspective, the lower limit of the MFR is preferably 1 g / 10 min or more, more preferably 1.5 g / 10 min or more. The upper limit of the MFR is preferably 15 g / 10 min or less, more preferably 7 g / 10 min or less. In other words, preferred ranges of MFR include 1 to 15 g / 10 min or 1.5 to 7 g / 10 min. The MFR is measured in accordance with JIS K7210-1 and JIS K6921-2 at a temperature of 230°C and a load of 2.16 kg.

[0018] 2) XSIV The intrinsic viscosity (XSIV) of the room temperature xylene soluble portion of the composition is preferably 0.5 to 4 dL / g. If the XSIV exceeds the upper limit, peel stability may decrease. If the XSIV is below the lower limit, 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, a preferred range of XSIV is 1 to 2.5 dL / g, for example.

[0019] XS can be obtained by known methods, but is preferably obtained, for example, by the following method. 2.5 g of polypropylene resin is placed in a flask containing 250 mL of o-xylene (solvent), and the mixture is stirred for 30 minutes at 135°C using a hot plate and reflux condenser while purging with nitrogen, until completely dissolved. The mixture is then cooled (for example, for about 1 hour at 25°C), and the resulting solution is filtered through filter paper to separate the filtrate and the residue on the filter paper. The filtrate from which the solvent has been removed is referred to as the room temperature xylene soluble fraction (XS). The solvent can be removed, for example, by drying the filtrate at 140°C under a nitrogen stream.

[0020] The intrinsic viscosity (IV) can be measured in tetrahydronaphthalene at 135° C. using a capillary viscometer, for example, 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 contains a polypropylene resin having a phase structure in which Component (A2) is dispersed in Component (A1). Component (A1) is 60 to 90 wt% of a propylene (co)polymer containing 0 to 5 wt% of a comonomer-derived unit selected from C2 to C10 α-olefins (excluding C3-α-olefins). Component (A2) is 10 to 40 wt% of an ethylene-C4 to C10 α-olefin copolymer containing 10 to 35 wt% of a C4 to C10 α-olefin-derived unit.

[0022] Comonomers selected from C2 to C10 α-olefins naturally do not contain 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 a comonomer is contained, the lower limit of the comonomer content is preferably more than 0% by weight, more preferably 0.1% by weight or more. When a comonomer is contained, ethylene is preferred from the standpoint of economy. Component (A1) can be broadly divided into embodiments containing comonomer-derived units and embodiments not containing them, which will be described later.

[0023] The content of component (A1) in the polypropylene-based resin is 60 to 90% by weight. If the content of component (A1) is low, it becomes difficult to produce the polypropylene-based resin, 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, a preferred range is 65 to 85% by weight.

[0024] Component (A2) is an ethylene-C4 to C10 α-olefin copolymer containing 10 to 35% by weight of units derived from a C4 to C10 α-olefin. The C4 to C10 α-olefin is not limited, but is preferably 1-butene, 1-hexene, or 1-octene, and more preferably 1-butene.

[0025] If the amount of the C4 to C10 α-olefin-derived units is too high, the peel strength may decrease, and if it is too low, the peel stability may decrease. From this perspective, the lower limit of the amount is preferably 15% by weight or more, more preferably 18% by weight or more. The upper limit is preferably 32% by weight or less, more preferably 27% by weight or less. Therefore, preferred ranges include 15 to 32% by weight or 18 to 27% by weight.

[0026] The content of component (A2) in the polypropylene resin is 10 to 40% by weight. If the content of component (A2) is too high, it becomes difficult to produce the polypropylene resin and the peel strength may decrease. If the content is too low, the peel stability may decrease. From this perspective, the lower limit of the amount is preferably 15% by weight or more, and the upper limit is preferably 35% by weight or less. Therefore, a preferred range for the content is 15 to 35% by weight, for example.

[0027] The total ethylene content in the polypropylene resin and the content of ethylene-derived units in component (A1) are measured by known methods, but a preferred measurement method is described below. A copolymer sample dissolved in a mixed solvent containing 1,2,4-trichlorobenzene and deuterated benzene is subjected to a spectrometry using an AVANCE III HD400 (manufactured by Bruker). １３ The conditions were: measurement temperature 120°C, flip angle 45°, pulse interval 7 seconds, sample rotation speed 20 Hz, and cumulative number 6000. １３ A C-NMR spectrum is obtained using a mixed solvent of preferably 1,2,4-trichlorobenzene / deuterated benzene / hexamethyldisiloxane in a volume ratio of 30 / 10 / 1.

[0028] Using the spectrum obtained above, the total ethylene content (wt%) of the polypropylene resin is determined by the method described in Kakugo, Y. Naito, K. Mizunuma and T. Miyatake, Macromolecules, 15, 1150-1152 (1982). When component (A1) is used as a 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 units derived from a comonomer other than ethylene, the content of the comonomer units can be determined in the same manner as the content of the ethylene-derived units.

[0030] In a polypropylene resin comprising components (A1) and (A2), the ethylene unit content in component (A2) can also be measured by known methods, but a preferred measurement method is described below. When component (A1) is a propylene homopolymer, the ethylene unit content (wt%) of component (A2) is determined by the same calculation method as for the total ethylene content, except that the integrated intensity T'ββ calculated by the following formula is used instead of the integrated intensity Tββ calculated when measuring the total ethylene content of the polypropylene resin by the method described in the above document: T'ββ = 0.98 x Sαγ x A' / (1 - 0.98 x A'), where A' = Sαγ / (Sαγ + Sαδ), and is calculated from Sαγ and Sαδ as described in the above document.

[0031] In a polypropylene resin composed of components (A1) and (A2), when component (A1) contains ethylene units, the content of ethylene-derived units in component (A2) can be calculated by the following formula, provided that the weight ratio (component (A2) / [component (A1)+component (A2)]) is clear from the polymerization conditions: In the formula, "resin" means a polypropylene resin.

[0032] Ethylene-derived unit content of component (A2) (unit: wt%) = [total ethylene content of resin - ethylene-derived unit content of component (A1) x content of component (A1) in resin] / (content 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 by 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 for the Development of Excellent Peeling Properties Layer P contains a specific amount of component (A2), which results in the development of excellent peeling properties. The reason for this is not limited, but is presumed to be as follows: The bond strength at the interface between component (A1) and component (A2) in layer P is lower than the fracture strength of the composition constituting layer P itself, and is also lower than the bond strength at the interface of each layer. Therefore, when an external force is applied in an attempt to peel off a layer located above layer P, cracks preferentially occur at the interface between component (A1) and component (A2) in layer P. These cracks then propagate to the arrayed and dispersed components (A2) one after another. As a result, layer P undergoes material fracture, which is thought to develop excellent peeling properties.

[0035] As described above, the multilayer sheet according to this embodiment can be broadly divided into two preferred embodiments depending on the component (A1). Each embodiment will be explained below.

[0036] [First Aspect] In this aspect, the component (A1) is a propylene homopolymer. For convenience, the component (A1) in this aspect will be referred to as component (A1'), and the layer P will be referred to as layer P'. That is, in this aspect, the layer P is a layer P' containing a polypropylene-based resin having a phase structure in which the component (A2) is dispersed in the component (A1'). The polypropylene-based resin having a phase structure in which the component (A2) is dispersed in the component (A1') is a heterophasic polypropylene in which the component (A2) is dispersed in a propylene homopolymer matrix.

[0037] 1, the biaxially oriented polypropylene layers 12 other than layer P' may be composed of known materials, and are preferably composed of a composition containing a propylene homopolymer or a composition containing an ethylene-propylene copolymer containing from 0 to 5% by weight of ethylene-derived units.

[0038] A more preferred structure of the multilayer sheet of this embodiment is shown in Figure 2(1). In the figure, 12H represents the first biaxially oriented polypropylene layer, 12L represents the second biaxially oriented polypropylene layer, and 10P' represents layer P'. This figure shows a partial structure of the multilayer sheet. The multilayer sheet comprises alternating layers in which layers 12H and 12L are alternately laminated, and a layer 10P' is provided between the two layers 12L. Layer 12H constitutes the main layer of the multilayer sheet, and layer 12L functions to bond 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. Melting point can be used as an indicator of softening point. The melting point is defined as the peak temperature of the melting curve obtained by measuring a sample by DSC from 30° C. to 230° C. at a heating rate of 10° C. / min.

[0039] To further enhance the adhesion between layer 10P' and layer 12L, the multilayer sheet may have a polypropylene layer 13 between layer 10P' and layer 12L, the polypropylene layer 13 having a softening point lower than Tsp' (FIG. 2(2)). The polypropylene layer 13 may be made of a known material. Preferably, the polypropylene layer 13 is made of a composition including an ethylene-propylene copolymer containing more than 1 wt % and not more than 5 wt % of ethylene-derived units.

[0040] There may be a plurality of layers 10P'. The layers 10P' may be unstretched layers or uniaxially or biaxially stretched layers. From the viewpoint of increasing the rigidity of the multilayer sheet, it is preferable that all of the layers 10P' are biaxially stretched layers. Furthermore, from the viewpoint of increasing the rigidity of the multilayer sheet, when there are a plurality of layers 10P', it is preferable that the number of unstretched layers 10P' is one or less.

[0041] The polypropylene layers 13 may be unstretched layers or uniaxially or biaxially stretched layers. From the viewpoint of increasing the rigidity of the multilayer sheet, it is preferable that all of the polypropylene layers 13 are biaxially stretched layers. Also, from the viewpoint of increasing the rigidity of the multilayer sheet, when there are multiple polypropylene layers 13, it is preferable that the number of unstretched polypropylene layers 13 is two or less.

[0042] Since the layers are fused together, the multilayer sheet is an integrated sheet. Whether the layers of the sheet are fused together and integrated can be confirmed by cross-sectional observation using a polarizing microscope, as described in WO 2020 / 075755, for example. Furthermore, the integrated multilayer sheet is manufactured, for example, according to the method described in WO 2022 / 102705. That is, the multilayer sheet is manufactured from a main layer that has high rigidity and is relatively difficult to melt, and an adhesive layer that is relatively easy to melt and fuses the main layers together. A preferred manufacturing method in this embodiment will be described below.

[0043] A preferred production method in this embodiment includes fusing the layers of a precursor in which a biaxially oriented polypropylene sheet member forming the biaxially oriented polypropylene layer and a sheet member forming the layer P' are laminated together.

[0044] 1) Preparation of Precursor Figure 3 outlines the manufacturing method. In the figure, 1' denotes a precursor. Precursor 1' is prepared by laminating the following coextruded layers. These coextruded layers are prepared according to known methods: Two-layer biaxially oriented polypropylene coextruded layer Coextruded layer in which polypropylene layers 13 are laminated on both sides of layer 10P' Three-layer biaxially oriented polypropylene coextruded layer Two-layer biaxially oriented polypropylene coextruded layer For ease of understanding, the figure shows a space between the coextruded layers of precursor 1', but in reality, the coextruded layers are in contact with each other.

[0045] 2) Heat Fusion Next, a heater is brought into contact with the outermost layer of the precursor 1' to heat fuse the layers together. ｏｕｔ and the temperature T of the heater is Tm ｏｕｔ It is preferable that the relationship -T≧4 (°C) is satisfied. By satisfying this relationship, the layers can be well fused together. From this viewpoint, it is more preferable that the temperature difference is 6°C or more. There is no upper limit to the temperature difference, but from the viewpoint of the production of polypropylene, it is preferably 40°C or less, more preferably 30°C or less. T can be measured by any method, but it is preferable to measure it using a non-contact thermometer such as a radiation thermometer. Tm ｏｕｔcorresponds to the melting point of the outermost layer, and is defined as the peak temperature of the melting curve obtained by measuring by DSC from 30°C to 230°C at a heating rate of 10°C / min.

[0046] The temperature T preferably satisfies the relationship Tmh ≥ T ≥ Tml, and more preferably satisfies the relationship Tmh ≥ T ≥ Tml + 10 (°C). Tmh is the melting point of the layer 12H, and Tml is the melting point of the layer 12L. If T exceeds the upper limit, the laminate may melt and the mechanical properties may deteriorate. If T is below the lower limit, the layers may not be sufficiently fused together, and the mechanical properties may deteriorate. The specific temperature of the heater is preferably about 120 to 190°C, more preferably 140 to 170°C, and even more preferably 150 to 165°C.

[0047] This step is preferably carried out continuously using a heated roll as a heating element. Specifically, the precursor of the multilayer sheet is passed between two heated rolls to fuse the layers. Two rolls form a set, and two or more sets of heated rolls may be used as the heating element to fuse the layers. The pressure applied during this step is adjusted appropriately. The take-up speed during roll molding is not limited, but is preferably about 0.05 to 10 m / min.

[0048] Methods other than roll molding include pressure molding and fusion molding. When heat-fusion bonding the sheet-like member, it is preferable to apply pressure to suppress thermal shrinkage and further promote orientation. The pressure is adjusted depending on the fusion temperature.

[0049] The layer in which polypropylene layers 13 are laminated on both sides of layer 10P' is preferably a coextruded layer formed by coextrusion. The total number of layers in the coextruded layer having a structure in which polypropylene layers 13 are 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 one 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 one layer of polypropylene layer 13 is preferably 2 μm to 200 μmm. From the viewpoint of ease of production, in a coextruded layer in which polypropylene layers 13 are laminated on both sides of layer 10P', when the layers constituting the coextruded layer are referred to as "constituent layers," it is preferable that all of the constituent layers are biaxially stretched layers, all of the constituent layers are uniaxially stretched layers, or all of the constituent layers are non-stretched layers.

[0050] Layers 12H and 12L are also preferably coextruded layers. The total number of layers in the coextruded layers is preferably 2 to 6, more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 2 to 3. The thickness of one layer of layer 12H is preferably 20 μm to 300 μm. The thickness of one 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. When the total thickness (total thickness) of the layers corresponding to the main layers is Dh and the total thickness (total thickness) of the layers corresponding to the adhesive layers is Dl, if the Dh / Dl ratio is too small, the rigidity of the multilayer sheet will be insufficient, and if the value is too large, the fusion strength between the layers of the multilayer sheet will be insufficient. From the perspective of balancing fusion strength and rigidity, the ratio is preferably 1 to 30, more preferably 1 to 25, and even more preferably 4 to 15. The thicknesses of the layers may be the same or different. The thicknesses of the layers are appropriately adjusted so that the ratio falls within the ranges specified above.

[0052] [Second Aspect] The second aspect will be described below. The details of the first aspect are incorporated herein by reference for matters not specifically mentioned in the second aspect. In this aspect, the component (A1) is a propylene copolymer containing more than 0% by weight and not more than 5% by weight of comonomer-derived units selected from C2 to C10 α-olefins (excluding C3 α-olefins). For convenience, the component (A1) in this aspect will be referred to as component (A1"), and the layer P will be referred to as layer P". That is, in this aspect, the layer P is a layer P" containing a polypropylene-based resin having a phase structure in which the component (A2) is dispersed in the component (A1"). The polypropylene-based resin having a phase structure in which the component (A2) is dispersed in the component (A1") is a heterophasic polypropylene in which the component (A2) is dispersed in a propylene homopolymer matrix. Alternatively, the component (A1) may be a blend of the component (A1'), which is a propylene homopolymer, and the component (A1"). In this case, the weight ratio of component (A1'):component (A1'') is preferably 10-50:90-50, more preferably 20-40:80-60.

[0053] A more preferred structure of the multilayer sheet of this embodiment is shown in Figure 4(1). In the figure, 10P" represents layer P". This figure shows the structure of a portion of the multilayer sheet. The multilayer sheet comprises alternating layers in which layers 12H and layers 12L are alternately laminated, and a layer 10P" is provided between two layers 12L. The softening point Tsp" of layer 10P" preferably satisfies the relationship Tsh > Tsp" ≥ Tsl or Tsh > Tsl > Tsp". Although not shown, a polypropylene layer 15 other than layers 12L and 12H may also be provided between layer 12L and layer 10P". The polypropylene layer 15 may be made of a known material. Preferably, the polypropylene layer 15 is made of a composition containing an ethylene-propylene copolymer containing 1 to 5 wt% of ethylene-derived units. The softening point of the polypropylene layer 15 may be higher than Tsl.

[0054] The multilayer sheet may have a structure of layer 10P" / polypropylene layer 14 / layer 10P" (Figure 4 (2)). The polypropylene layer 14 may have a softening point higher than Tsp". The polypropylene layer 14 may be made of a known material. Preferably, the polypropylene layer 14 is made of a composition containing an (ethylene-)propylene (co)polymer containing 0 to 2 wt% of ethylene-derived units. The polypropylene layer 14 may be layer 12H.

[0055] There may be a plurality of layers 10P". The layers 10P" may be unstretched layers or uniaxially or biaxially stretched layers. From the viewpoint of increasing the rigidity of the multilayer sheet, it is preferable that all of the layers 10P" are biaxially stretched layers. Also, from the viewpoint of increasing the rigidity of the multilayer sheet, when there are a plurality of layers 10P", it is preferable that the number of unstretched layers 10P" is one or less.

[0056] The polypropylene layers 14 may be unstretched layers or uniaxially or biaxially stretched layers. From the viewpoint of increasing the rigidity of the multilayer sheet, it is preferable that all of the polypropylene layers 14 are biaxially stretched layers. Also, from the viewpoint of increasing the rigidity of the multilayer sheet, when there are multiple polypropylene layers 14, it is preferable that the number of unstretched polypropylene layers 14 is one or less.

[0057] A preferred production method in this embodiment includes fusing the layers of a precursor in which a biaxially oriented polypropylene sheet member forming the biaxially oriented polypropylene layer and a sheet member forming the layer P″ are laminated together.

[0058] 1) Preparation of Precursor FIG. 5 outlines the manufacturing method. In the figure, 1' denotes a precursor. Precursor 1' is prepared by laminating the following coextruded layers. These coextruded layers are prepared according to known methods: Two-layer biaxially oriented polypropylene coextruded layer A coextruded layer in which layers 10P" are laminated on both sides of polypropylene layer 14 A three-layer biaxially oriented polypropylene coextruded layer A two-layer biaxially oriented polypropylene coextruded layer For ease of understanding, the figure shows a space between the coextruded layers of precursor 1', but in reality, the coextruded layers are abutting each other.

[0059] 2) Heat Fusion Next, a heater is brought into contact with the outermost layer of the precursor 1' to heat fuse the layers together. This step is the same as that described in the first embodiment.

[0060] The layer in which layers 10P" are laminated on both sides of the polypropylene layer 14 is preferably a coextruded layer. The total number of layers in the coextruded layer having a structure in which layers 10P" are 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 one layer of the polypropylene layer 14 is preferably 20 μm to 300 μm. The thickness of one layer of the layer 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 production, in a coextruded layer in which layers 10P" are laminated on both sides of the polypropylene layer 14, when the layers constituting the coextruded layer are referred to as "constituent layers," it is preferable that all of the constituent layers are biaxially oriented layers, all of the constituent layers are uniaxially oriented layers, or all of the constituent layers are non-oriented layers.

[0061] Layers 12H and 12L are preferably composed of coextruded layers. The total number of layers in the coextruded layers is preferably 2 to 6, more preferably 2 to 5, even more preferably 2 to 4, and particularly preferably 2 to 3. The thickness of one layer of layer 12H is preferably 20 μm to 300 μm. The thickness of one 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. When the total thickness (total thickness) of the layers corresponding to the main layers is Dh and the total thickness (total thickness) of the layers corresponding to the adhesive layers is Dl, if Dh / Dl is too small, the rigidity of the multilayer sheet will be insufficient, and if the value is too large, the fusion properties between the layers of the multilayer sheet will be insufficient. In view of the balance between fusion properties 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. The thickness of each layer is appropriately adjusted so that the ratio falls within the above range.

[0063] [Other Layers] A top layer can be provided in the multilayer sheet. The top layer can be provided by a known method. For example, these layers can be provided by applying a coating. The type of coating is not limited, and is not limited as long as it is one that is normally used in the coating field.

[0064] The top layer is preferably a coating film used in vehicle body painting. Examples of such coating films include epoxy coating films, urethane coating films, and polyester coating films. If necessary, a lower coating film (primer coating film), a middle coating film, or a top coating film (clear coating film) may be provided. When the multilayer sheet is used as a sheet for applying coating (coated sheet), it is preferable that the surface to be painted has functional groups.

[0065] A surface active layer can be provided on the multilayer sheet according to a standard method. For example, the surface of the multilayer sheet can be subjected to plasma treatment or corona treatment to impart oxygen-containing functional groups to the surface, which can then be used as the surface active layer. Alternatively, a polypropylene film having functional groups can be prepared and placed 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 the surface active layer.

[0066] A polypropylene film having oxygen-containing functional groups can be obtained by molding a known polypropylene, such as maleic anhydride-modified polypropylene or epoxy-modified polypropylene, into a film. The thickness of the functional group-containing film is not limited, but is preferably less than 150 μm. The functional group-containing film may or may not be biaxially stretched. In the lamination process, a polypropylene film having functional groups and a polypropylene sheet having no functional groups may be laminated simultaneously, or a polypropylene sheet having no functional groups may be laminated in advance to produce a laminate sheet, and then a polypropylene film having functional groups may be laminated on the surface of the sheet. However, considering workability, a simultaneous lamination method is preferred.

[0067] The production method may further include a known step of cooling the multilayer sheet obtained in the previous step, etc. The cooling method is not limited, but examples include a method of leaving it to cool at room temperature and a method of cold pressing it at room temperature or at 10 to 20°C.

[0068] (3) Mechanical Properties, Heat Resistance The multilayer sheet and molded articles such as containers obtained from the multilayer sheet have excellent mechanical properties. For example, the sheet and molded articles preferably have a flexural modulus (JIS K7171) of 2,000 MPa or more, more preferably 2,500 MPa or more in terms of rigidity. The multilayer sheet also has excellent cold impact resistance. For example, the multilayer sheet and molded articles preferably have a flexural modulus (JIS K7171) of 10 KJ / m ２ Furthermore, the multilayer sheet preferably has a Charpy impact strength of 0.90 to 0.93 g / cm (0.90 to 1.0 g / cm when an inorganic filler is contained). ３ It has a density of

[0069] (4) Surface Functional groups can be added to the surface of the multilayer sheet. Oxygen-containing functional groups are preferred. Examples of oxygen-containing functional groups include carboxyl groups, carboxylate groups, acid anhydride groups, hydroxyl groups, aldehyde groups, and epoxy groups. These functional groups improve the adhesion between the multilayer sheet and other materials. In particular, providing a coating film on a layer having functional groups is preferred because it improves the adhesion between the layer and the coating film.

[0070] (5) Nucleating Agent Layer P and other layers may be composed of a composition containing a nucleating agent, or may be composed of a composition or polymer that does not contain a nucleating agent. A nucleating agent is an additive used to increase the crystalline component in the resin to enhance rigidity. Known additives can be used as such additives. From an economical standpoint, the amount of nucleating agent is preferably 1 part by weight or less per 100 parts by weight of the polymer.

[0071] (6) Other Additives The composition constituting each layer may contain, to the extent that the desired effects are not impaired, conventional additives commonly used in polyolefins, such as antioxidants, chlorine absorbers, heat stabilizers, light stabilizers, UV absorbers, internal lubricants, external lubricants, antiblocking agents, antistatic agents, antifogging agents, flame retardants, dispersants, copper inhibitors, neutralizing agents, plasticizers, crosslinkers, peroxides, oil extenders, organic pigments, or inorganic pigments. The amount of each additive may be known. Furthermore, to the extent that the desired effects are not impaired, the composition may contain synthetic resins other than the polypropylene-based resins (e.g., modified polypropylene) or synthetic rubbers. The synthetic resins or synthetic rubbers may be one type or two or more types.

[0072] 2. Applications The multilayer sheet has a high degree of orientation in the in-plane direction and a specific high-order structure, and the degree of orientation is minimally dependent on the thickness direction, resulting in lightweight yet excellent mechanical properties. Furthermore, the multilayer sheet has excellent peelability, allowing the top layer and other layers to be easily peeled off, and is also highly recyclable. Therefore, the multilayer sheet has excellent recyclability and rigidity, making it suitable for use as a steel plate replacement for automotive parts, electrical and electronic parts, housing components, and the like. Furthermore, the multilayer sheet is useful as a food packaging material, container, or lid that can be thinned, reduced in weight, and easily opened. Furthermore, due to its high rigidity, the multilayer sheet is useful for miscellaneous goods, daily necessities, home appliance parts, toy components, furniture components, building materials, packaging components, industrial materials, logistics materials, agricultural materials, and the like.

[0073] The multilayer sheet can be used as a recyclable steel sheet substitute material, and the recycling method will be explained below using automotive materials as an example.

[0074] The peel strength is not limited, but from the viewpoint of a balance between high adhesion and high releasability, in one embodiment it is preferably 15 to 50 N / 15 mm, more preferably 15 to 40 N / 15 mm, and even more preferably 15 to 35 N / 15 mm. The peel strength is determined by a 180-degree peel test using a 15 mm wide strip test piece. In one embodiment, the distance between the grippers is 50 mm, the gripper movement speed is 300 mm / min, the tensile length is 100 mm, and the test values ​​used are the initial load and the integrated average load over a 50 mm stable section during material failure.

[0075] Peel strength is preferably measured by the following method. A 180-degree peel test is performed. The multilayer sheet is cut into 15 mm wide strips to prepare test pieces. The top layer and the bottom layer are clamped between clamps, with the distance between the clamps set to 50 mm. A tensile test is performed by moving the clamps at a speed of 300 mm / min. The test piece is pulled for 100 mm or more, and the initial load and the integrated average load over a 50 mm stable zone during material failure are used as test values ​​to determine the peel strength. An Autocom universal testing machine manufactured by TSE Corporation, for example, can be used as the test device.

[0076] The multilayer sheet has good adhesion between the layers, so there is almost no discontinuity between the layers, and therefore it can be handled as an integrated sheet.

[0077] 1. Production of Polypropylene Resin Composition [Polymer a] The solid catalyst used for polymerization was prepared by the method described in Example 1 of JP-A-2011-500907. ２The solid catalyst was supported on Ti and diethyl-2,3-(diisopropyl)succinate as an internal donor by the method described in the above patent publication. The solid catalyst was contacted with triethylaluminum (TEAL) and dicyclopentyldimethoxysilane (DCPMS) in amounts such that the weight ratio of TEAL to the solid catalyst was 11 and the weight ratio of TEAL / DCPMS was 15 at 12°C for 24 minutes. The resulting catalyst system was suspended in liquid propylene and maintained at 20°C for 5 minutes to carry out prepolymerization. The resulting prepolymer was introduced into a polymerization reactor, and hydrogen, propylene, and ethylene were fed. Polymer a was obtained as a propylene-ethylene copolymer by adjusting the polymerization temperature to 80°C, the hydrogen concentration to 0.17 mol%, and the ethylene concentration to 0.08 mol%, and the polymerization pressure to 100°C. Polymer a (component (A1), hereinafter also referred to simply as the "PP component") contained 0.36 wt% of ethylene-derived units (hereinafter also referred to simply as "C2") and had an MFR (temperature 230°C, load 2.16 kg) of 4.4 g / 10 min.

[0078] [Polymer b] The solid catalyst used for polymerization was prepared by the method described in Example 1 of EP 674991. The solid catalyst was MgCl ２ The solid catalyst was supported on the catalyst by the method described in the above patent publication, with Ti and diisobutyl phthalate as an internal donor. The solid catalyst was contacted with TEAL and dicyclopentyldimethoxysilane (DCPMS) for 5 minutes at -5°C in amounts such that the weight ratio of TEAL to the solid catalyst was 11 and the weight ratio of TEAL to DCPMS was 3. The resulting catalyst system was prepolymerized by maintaining the suspension in liquid propylene at 20°C for 5 minutes. The resulting prepolymer was introduced into a polymerization reactor, followed by feeding hydrogen, propylene, and ethylene. Polymer b was obtained as a propylene-ethylene copolymer by adjusting the polymerization temperature to 75°C, the hydrogen concentration to 0.44 mol%, and the ethylene concentration to 1.07 mol%, and adjusting the polymerization pressure. Polymer b (PP component) contained 4.0 wt% C2 and had an MFR of 7.5 g / 10 min (temperature 230°C, load 2.16 kg).

[0079] [Polymer c] Polymer c was obtained in the same manner as for Polymer B, except that the hydrogen concentration was changed to 0.25 mol% and the ethylene concentration was changed to 0.44 mol%. Polymer c contained 2.0 wt% of C2 and had an MFR (temperature 230°C, load 2.16 kg) of 5.9 g / 10 min.

[0080] [Polymer x １ ] MgCl ２ A solid catalyst having Ti and diisobutyl phthalate as an internal donor supported thereon was prepared by the method described in Example 5 of EP 728769. Next, the solid catalyst was contacted with triethylaluminum (TEAL) as an organoaluminum compound and dicyclopentyldimethoxysilane (DCPMS) as an external electron donor compound at a weight ratio of 20% TEAL to the solid catalyst and a weight ratio of 10% TEAL / DCPMS at 12°C for 24 minutes. The resulting catalyst system was prepolymerized by maintaining the suspension in liquid propylene at 20°C for 5 minutes. The resulting prepolymer was introduced into the first-stage polymerization reactor of a polymerization apparatus equipped with two series-connected polymerization reactors. Ethylene was fed into the liquid-phase propylene to produce a propylene-ethylene random copolymer (component (A1)). An ethylene-1-butene copolymer (component (A2)) was then produced in the second-stage gas-phase polymerization reactor. During the polymerization, the temperature and pressure were adjusted, and hydrogen was used as a molecular weight modifier. The polymerization temperature, hydrogen concentration, and ethylene concentration in the first-stage reactor were 70°C, 0.060 mol%, and 0.84 mol%, respectively. The polymerization temperature, H2 / C2, and C4 / (C2+C4) in the second-stage reactor were 80°C, 0.26 mol%, and 0.48 mol%, respectively. The polymerization times in the first and second stages were adjusted so that the amount of component (A2) was 18 wt%.

[0081] [Polymer x ２In the first-stage reactor, ethylene was not fed, and the hydrogen concentration was changed to 0.05 mol %, to polymerize a propylene homopolymer. In the second-stage reactor, the H2 / C2 and C4 / (C2+C4) molar ratios were changed to 0.22 and 0.52, respectively, and the polymerization times in the first and second stages were adjusted so that the amount of ethylene-1-butene copolymer, which is component (A2), was 30% by weight. １ Polymer x is produced by the same method as in the case of ２ obtained.

[0082] [Polymer x ３ In the first reactor, the hydrogen concentration was changed to 0.83 mol%, and in the second reactor, the H2 / C2 and C4 / (C2+C4) molar ratios were changed to 0.30 and 0.40, respectively, and the polymerization times in the first and second stages were adjusted so that the amount of ethylene-1-butene copolymer, component (A2), was 32% by weight. １ Polymer x is produced by the same method as in the case of ３ obtained.

[0083] [Polymer compositions A to C, X １ ~X ３ 100 parts by weight of each of the polymers (a to c, x １ ~x ３ ), 0.2 parts by weight of an antioxidant (B225 manufactured by BASF) and 0.05 parts by weight of a neutralizer (calcium stearate manufactured by Tannan Chemical Industry Co., Ltd.), 0.05 parts by weight of Millad NX8000J (manufactured by Milliken Japan Co., Ltd.) as a nucleating agent, 0.10 parts by weight of Adeka Stab NA-21 (manufactured by ADEKA Corporation) as a nucleating agent, and 0.10 parts by weight of a nucleating agent. １ 0.25 parts by weight of Adeka Stab NA-71 (manufactured by ADEKA Corporation) was blended into the resin composition, and the mixture was mixed by stirring for 1 minute using a Henschel mixer. The mixture was melt-kneaded at a cylinder temperature of 230°C using an NVC φ50 mm single-screw extruder manufactured by Nakatani Machinery Co., Ltd., and the extruded strand was cooled in water and then cut with a pelletizer to obtain a pellet-shaped resin composition (polymer compositions A to C, X). １ ~X ３ ) was obtained.

[0084] [Resin composition Y３ , Y ５ ~Y ８ , Z] in the weight ratio shown in Table 1 １ ~X ３ The above ingredients were blended, and 0.1 parts by weight of dimyristyl thiodipropionate (dimyristyl thiodipropionate (DMTP) manufactured by Mitsubishi Chemical Corporation) was further added as an antioxidant, followed by stirring for 1 minute with a Henschel mixer to obtain a mixture. The mixture was then melt-kneaded (twin-screw melt-kneading) in an extruder (TEX-30α co-rotating twin-screw extruder manufactured by The Japan Steel Works, Ltd.) with a screw temperature set to 230°C. The molten mixture was then discharged from the extruder and cooled to form strands, which were then cut to prepare pellets of the resin composition.

[0085] 2. Preparation of Biaxially Stretched Sheet [Biaxially Stretched Sheet AAB] Using a 25 mm diameter, three-type, three-layer film / sheet molding machine (manufactured by Thermo Plastics Industries Co., Ltd.), polymer composition A / polymer composition A / polymer composition B were coextruded at a molding temperature of 230°C to obtain a raw sheet (size 10 cm x 10 cm or more) having a thickness of 2.5 mm. Using a film stretching device (KARO-IV, manufactured by Bruckner), the raw sheet was simultaneously biaxially stretched (3.5 times x 3.5 times) at 165°C to obtain a coextruded biaxially oriented sheet having a thickness of 0.20 mm. The thickness ratio was 1:18:1. Since the two polymer composition A layers were integrated, this sheet was technically a two-layer sheet.

[0086] [Other biaxially oriented sheets] Biaxially oriented sheets were produced in the same manner as for biaxially oriented sheet AAB, except that the polymers and conditions used were changed as shown in Table 2. Hereinafter, biaxially oriented sheet AAB will also be referred to simply as "AAB." The same applies to other sheets.

[0087] [Unstretched sheet CX ２ C Ｕ -3] Using a 25 mm diameter 3-type 3-layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), polymer composition C / polymer composition X were mixed at a molding temperature of 230°C. ２The resulting mixture was coextruded to obtain a 0.060 mm thick sheet (10 cm x 10 cm or larger) with a thickness ratio of 1:1:1.

[0088] [Unstretched Sheet X ３Ｕ Using a 25 mmφ single layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), polymer composition X was molded at a molding temperature of 230°C. ３ was extruded to obtain a sheet (size 10 cm x 10 cm or more) having a thickness of 0.060 mm.

[0089] [Unstretched sheet Y ８Ｕ Using a 25 mmφ single layer film / sheet molding machine (manufactured by Thermo Plastics Industry Co., Ltd.), polymer composition Y was molded at a molding temperature of 230°C. ８ was extruded to obtain a sheet (size 10 cm x 10 cm or more) having a thickness of 0.060 mm.

[0090] 3. Production of Multilayer Sheet [Example 2-1] A precursor having the following layer structure was prepared: AAB / X １ AX １ / / X １ AX １ / 9 sheets of BAB / BAA " / / " indicates the interface where a 55 μm thick polyimide tape was inserted. Since polyimide tape and polypropylene do not fuse together, the area where the polyimide tape was inserted was used as the gripping part in the peel test.

[0091] A Shoji Co., Ltd. press molding machine heated to 163°C was used as a heating body to heat-seal the layers of the precursor to produce a multilayer sheet as a laminate. During pressing, both sides of the precursor were sandwiched between 3 mm thick aluminum plates and 1 mm thick steel plates from the outside, and pressure was applied at 4 MPa for 2 minutes. In this way, a 2.3 mm thick multilayer sheet was produced. The peel strength of the multilayer sheet was measured using the method described below. The results are shown in Table 3. Layer X adjacent to the " / / " and located on the AAB side １The peel strength was 34.9 N / 15 mm for the initial load and 33.2 N / 15 mm for the integrated average load for a 50 mm peel, demonstrating that the film had both excellent adhesion and excellent peeling properties.

[0092] [Examples 2-2 to 2-10] Multilayer sheets were produced and evaluated in the same manner as in Example 2-1, with the layer structures shown in Table 3. The multilayer sheets shown in Table 3 correspond to the multilayer sheets of the second embodiment. In Examples 2-2 to 2-7, layer Y ７ , layer Z, layer Y ５ , layer Y ７ In Examples 2-8 to 2-10, Layer X, Layer Z, and Layer Z functioned as peeling layers. ３Ｕ , layer Y ８Ｕ , and layer Y ３ It was revealed that the multilayer sheet had both excellent adhesion and excellent peeling properties.

[0093] [Examples 1-1 to 1-3] Multilayer sheets were produced and evaluated in the same manner as in Example 2-1, with the layer structures shown in Table 4. The multilayer sheets shown in Table 4 correspond to the multilayer sheets of the first embodiment. In these examples, layer X ２ It was revealed that the multilayer sheet had both excellent adhesion and excellent peeling properties.

[0094] Comparative Examples 1 to 7 Multilayer sheets were produced and evaluated in the same manner as in Example 2-1, with layer structures as shown in Table 5. It was revealed that the multilayer sheets did not have good peeling properties.

[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 Example 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 Example 2-4: AAB / CY5C / / BAB×9 / BAA Example 2-5: AAB / CY7C / / BAB×9 / BAA Example 2-6: AAB / CZC / / BAB×9 / BAA Example 2-7: CAC×4 / CZC / / BAB×9 / BAA Example 2-8: AAB / X 3U / / BAB×9 / BAA Example 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]

[0098]

[0099]

[0100]

[0101]

[0102]

[0103] [Evaluation Methods] 1) Total ethylene content (component (A1) + component (A2)) and ethylene-derived unit content in component (A1) Measured as described above. 2) Ethylene unit content in component (A2) Measured as described above. The C4 to C10 α-olefin unit content (wt%) in component (A2) was calculated from the 100-ethylene unit content (wt%).

[0104] 3) Weight ratio Component (A2) / [Component (A1)+Component (A2)] Measured as described above. When Component (A1) contains an ethylene unit, it was estimated from the polymerization conditions.

[0105] 4) MFR The MFR of a polypropylene resin was measured by adding 0.05 g of H-BHT manufactured by Honshu Chemical Industry Co., Ltd. to 5 g of a sample, homogenizing by dry blending, and then measuring the MFR at a temperature of 230°C and a load of 2.16 kg in accordance with JIS K7210-1 and JIS K6921-2. The MFR of a polypropylene resin composition was measured at a temperature of 230°C and a load of 2.16 kg in accordance with JIS K7210-1 and JIS K6921-2.

[0106] 5) Peel Test A 180-degree peel test was performed using an Autocom universal testing machine manufactured by TSE Corporation. The sheet produced in the above example was cut into 15 mm wide strips to prepare test pieces. The top layer and the bottom layer were each clamped between clamps. The distance between the clamps was 50 mm, and the clamps were moved at a speed of 300 mm / min to perform a tensile test. The test was performed for a distance of 100 mm or more, and the average test force in the stable section of 50 mm during material failure was used as the test value.

[0107] 6) Flexural modulus: This was measured in accordance with JIS K7171. The multilayer sheet was cut to a width of 10 mm and a length of 80 mm to prepare a test piece. The flexural modulus was measured using a precision universal testing machine (Autograph AG-X 10kN) manufactured by Shimadzu Corporation under the conditions of a temperature of 23°C, a relative humidity of 50%, a support distance of 32 mm, and a test speed of 2 mm / min.

[0108] 7) Charpy Impact Strength Measurement was performed using a multilayer sheet cut to a width of 10 mm and a length of 80 mm, obtained using the same procedure as the test specimen used in the flexural modulus measurement. That is, in accordance with JIS K7111-1, a multilayer sheet cut to a width of 10 mm and a length of 80 mm was notched in the width direction using a notching tool A-4 manufactured by Toyo Seiki Seisaku-sho, Ltd., to obtain a measurement specimen of shape A. The Charpy impact strength (edgewise impact, 1 eA method) of the measurement specimen was measured at a temperature of -30°C using a fully automatic impact tester with a low-temperature chamber (No. 258-ZA) manufactured by Yasuda Seiki Seisaku-sho, Ltd.

[0109] 8) Density: According to JIS K7112

[0110] REFERENCE SIGNS LIST 1 multilayer sheet 10 Layer P 10P' Layer P 10P" Layer P" 12 biaxially oriented polypropylene layer 12H First biaxially oriented polypropylene layer 12L Second biaxially oriented polypropylene layer 13 Polypropylene layer 14 Polypropylene layer 1' Precursor

Claims

1. A polypropylene multilayer sheet having a thickness of 0.5 to 5 mm, comprising a plurality of biaxially stretched polypropylene layers and one or more layers P composed of a composition containing a polypropylene-based resin, an ethylene-C4 to C10 α-olefin copolymer, and having the following characteristics: 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 (where r is the distance from the surface of the multilayer sheet as the origin to the position of the interface on the origin side between the layer P and the other layer in the thickness direction from the origin, and R is the total thickness of the multilayer sheet. However, the origin is the surface where r is minimized); 3) the content of the ethylene-C4 to C10 α-olefin copolymer in the composition constituting the layer P is 10 to 40% by weight. Polypropylene multilayer sheet.

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

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

4. The polypropylene multilayer sheet according to claim 1 or 2, wherein the layer P is a biaxially stretched layer.

5. It is formed by a method including fusing the interfaces of a precursor in which a biaxially stretched polypropylene sheet-like member forming the biaxially stretched polypropylene layer and a sheet-like member forming the layer P are laminated. The precursor includes a coextruded layer in which polypropylene layers are laminated on both sides of the layer P. The layer P is a layer P' including a polypropylene-based resin having a phase structure in which the component (A2) is dispersed in the component (A1'). The component (A1') is 60 to 90% by weight of a propylene polymer. The component (A2) is 10 to 40% by weight of an ethylene-C4 to C10 α-olefin copolymer containing 10 to 35% by weight of units derived from C4 to C10 α-olefins. The polypropylene multilayer sheet according to claim 1 or 2.

6. The polypropylene multilayer sheet according to claim 5, wherein the coextruded layer is a biaxially stretched layer.

7. It is formed by a method including fusing the interfaces of a precursor in which a biaxially stretched polypropylene sheet-like member forming the biaxially stretched polypropylene layer and a sheet-like member forming the layer P are laminated. The layer P is a layer P" including a polypropylene-based resin having a phase structure in which the component (A2) is dispersed in the component (A1"). The component (A1") is 60 to 90% by weight of a propylene copolymer containing more than 0 to 5% by weight of units derived from a comonomer selected from C2 to C10-α olefins (excluding C3-α olefins). The component (A2) is 10 to 40% by weight of an ethylene-C4 to C10 α-olefin copolymer containing 10 to 35% by weight of units derived from C4 to C10 α-olefins. The polypropylene multilayer sheet according to claim 1 or 2.

8. The polypropylene multilayer sheet according to claim 7, wherein the precursor includes a coextruded layer in which the layer P" is 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 includes an inorganic filler of 10% by weight or less.

10. A molded article formed by molding the polypropylene multilayer sheet according to claim 1.

11. The molded article according to claim 10, which is a component for an automobile.

12. A peeling method of peeling at least one layer from the polypropylene multilayer sheet according to claim 1 or 2, or the molded article according to claim 10, using the layer P as a peeling layer.

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