Laminated sheet, method for manufacturing the same, sheet molded product, and solar cell sheet

Abstract

The present invention can provide a laminated sheet which exhibits excellent rigidity as a member that can be applied to a large-sized molded article, which exhibits excellent uniformity of in-plane rigidity particularly when the laminated sheet has a large area, and which has less unevenness of physical properties. A laminated sheet according to the present invention has a structure in which a layers that are each made of a biaxially oriented polypropylene film and b layers that are each made of an olefin-based resin having a melting point of 110-160°C are alternately laminated. When the direction of one side of the laminated sheet is regarded as an x direction and the direction orthogonal to this direction is regarded as a y direction, the tensile elastic moduli in the x direction and the y direction at three positions which include the central position in the y direction and two positions that are each located at a distance of 200 mm from the central position in the y direction passing through the central position are each within the range of 2000-5000 MPa.

Description

Technical Field

[0001] The present invention relates to a laminated sheet, a method for producing the same, a sheet molded article, and a solar cell sheet. The present application claims priority based on Japanese Patent Application No. 2023-047359 filed in Japan on March 23, 2023, the content of which is incorporated herein by reference. Background Art

[0002] Polypropylene sheets are widely used mainly for food trays because of their excellent moldability, heat resistance and chemical resistance. However, they have not been used for large molded articles such as construction materials, vehicles, and automobile parts, because as sheet molded articles they are inferior in mechanical strength, and the current situation is that polypropylene molded articles are exclusively obtained by injection molding. On the other hand, polypropylene sheet molded articles have the advantage of being easy to recycle as monomaterial, and are materials that meet the recent needs for reducing environmental load, and are expected to be used in industrial products.

[0003] Accordingly, as a method for increasing the rigidity of polypropylene sheet molded articles, for example, Patent Document 1 discloses a technique for obtaining a moldable laminated sheet by laminating a plurality of two-type three-layer stretched polypropylene films in which low-melting polypropylene films are positioned on both surface layers of a high-melting polypropylene film, followed by heat bonding. Prior Art Documents Patent Documents

[0004] Patent Document 1 International Publication No. 2020 / 75755 Summary of the Invention Problems to be Solved by the Invention

[0005] However, the laminated sheet described in Patent Document 1 is laminated using a roll forming machine, and because the pressure is applied only at the joint point of the nip roll, lamination is difficult, the adhesion of each layer is insufficient, air is trapped throughout, and the resulting sheet is prone to warping and undulation. Furthermore, even when the material was fed slowly to ensure proper bonding, problems arose such as wrinkles forming on the surface due to radiant heat from the roll (165°C).

[0006] In addition, problems such as overall air entrapment, warping, and undulation have made it difficult to apply the material to large-area molded sheets for mobility applications and other uses.

[0007] Therefore, the problem that the present invention aims to solve is to provide a biaxially oriented laminated sheet with excellent rigidity that can be applied to large molded products, in particular a biaxially oriented laminated sheet in which the in-plane rigidity is homogenized when the area is increased and there are few variations in mechanical properties. In addition, the objective is to provide a biaxially oriented laminated sheet that has excellent surface smoothness and small irregularities over a wide area within the surface. [Means for solving the problem]

[0008] The contents of this disclosure include the following embodiments. [1] A laminated sheet having a structure in which layers a, made of biaxially oriented polypropylene film, and layers b, made of an olefin resin with a melting point of 110 to 160°C, are alternately laminated, A laminated sheet characterized in that, when the direction of one side of the laminated sheet is defined as the x-direction and the direction perpendicular thereto as the y-direction, the tensile modulus of elasticity in the x-direction and the y-direction at three positions including the center position in the y-direction and two positions passing through this center position and located 200 mm away from the center position in the y-direction are all within the range of 2000 to 5000 MPa. [2] In a plan view of the laminated sheet, when a 595 mm × 595 mm square is drawn such that the diagonal intersection is at the center in the y direction, the diagonal intersection is α, the midpoint between the diagonal intersection and the corner is β, and the corner is γ. When the surface roughness at positions α, β, and γ are denoted as Ra(α), Ra(β), and Ra(γ), The laminated sheet described in [1], wherein Ra(α), Ra(β), and Ra(γ) satisfy the following equations (1) to (2). Ra(α)-Ra(β)<0.3 (1) Ra(α)-Ra(γ)<0.3 (2) The above-mentioned Ra(α), Ra(β), and Ra(γ) are the average values ​​(average roughness) obtained when the surface roughness of each test piece was measured at two locations on each test piece, which was cut out in the shape of a strip with the y-direction as its longer side from the positions of α, β, and γ, respectively. [3] The laminated sheet is formed by stacking and heat-sealing multiple layers of multilayer biaxially oriented films (X), each of which a biaxially oriented polypropylene film (A) constituting the a layer and a biaxially oriented olefin resin film (B) constituting the b layer are laminated on at least one surface thereof, and The laminated sheet according to [1] or [2], wherein the multilayer biaxially oriented film (X) has a stretching ratio of 2.8 to 8 times in the MD direction and a stretching ratio of 2.8 to 12 times in the TD direction. [4] The multilayer biaxially oriented film (X) is a BAB type film in which the biaxially oriented olefin resin film (B) is included on both surfaces of the biaxially oriented polypropylene film (A), and has a thickness of 30 to 80 μm. The laminated sheet is obtained by laminating 30 to 60 BAB-type films and laminating BA-type films or BAA-type films on both surfaces such that A is on the surface, as described in [3]. [5] The multilayer biaxially oriented film (X) is a BAB type film containing the biaxially oriented olefin resin film (B) on both surfaces of the biaxially oriented polypropylene film (A), and is a two-type three-layer film with a thickness of 100 to 400 μm. The laminated sheet is obtained by laminating 2 to 20 BAB-type films and laminating BA-type films or BAA-type films on both surfaces such that A is on the surface, as described in [4]. [6] A molded product of the laminated sheet described in [1] or [2]. [7] A method for producing a laminated sheet having a structure in which layers a, made of biaxially oriented polypropylene film, and layers b, made of an olefin resin having a melting point of 110 to 160°C, are alternately laminated, A preparation step to form a laminated sheet precursor (pMS) by stacking multiple multilayer biaxially oriented films (X) in which a biaxially oriented polypropylene film (A) constituting the a layer and a biaxially oriented olefin resin film (B) constituting the b layer are laminated on at least one surface thereof, A method for manufacturing a laminated sheet, comprising a pressing step of heating and pressing the laminated sheet precursor (pMS) on its surface. [8] A method for producing a laminated sheet comprising alternating layers of a layer made of biaxially oriented polypropylene film and b layers made of an olefin resin having a melting point of 110 to 160°C, comprising a preparation step of stacking multiple multilayer biaxially oriented films (X) in which a biaxially oriented polypropylene film (A) constituting the a layer and a biaxially oriented olefin resin film (B) constituting the b layer are laminated on at least one surface thereof to form a laminated sheet precursor (pMS), The process includes a continuous press step in which the laminated sheet precursor (pMS) is continuously heated and pressed using a continuous press device, and then cooled. A method for manufacturing a laminated sheet, characterized in that the continuous pressing device has multiple heating zones and cooling zones, and the laminated sheet precursor (pMS) is heated and pressed in the heating zone using upper and lower planar molds, and then continuously pressed in the cooling zone using upper and lower planar molds. [9] A laminated sheet precursor (pMS) is inserted between the upper and lower planar molds that constitute the heating zone in the continuous pressurizing device, A method for manufacturing a laminated sheet as described in [8], comprising: pressing at a pressure of 110 to 170°C and 1 to 40 MPa; then, after releasing the press, feeding the sheet a predetermined length in the direction of travel (MD direction); heating and pressing again; and repeating this process to continuously transfer the sheet from the heating zone to the cooling zone; and subsequently, pressing in the cooling zone at a pressure of 25 to 125°C and 1 to 40 MPa; then, after releasing the press, feeding the sheet in a predetermined direction of travel to continuously remove the heat-fused laminated sheet.

[10] The heating zone is divided into 2 to 10 stages in the MD direction and is composed of a mold with a flat contact surface that sandwiches the sheet from above and below, The method for manufacturing a laminated sheet as described in [9], wherein the cooling zone is divided into one or two to five stages in the MD direction and has a structure composed of molds with flat contact surfaces that sandwich the sheet from above and below.

[11] The method for manufacturing a laminated sheet according to [9] or

[10] , wherein the temperature conditions of the heating zones, which are divided into 2 to 10 stages in the MD direction, are such that the temperature of the first heating zone closest to the sheet entrance is 110 to 160°C, the temperature of the second heating zone that follows is 10 to 40°C above the set temperature of the first heating zone, and the maximum temperature of the heating zones is 170°C.

[12] The multilayer biaxially oriented film (X) has a stretching ratio of 2.8 to 8 times in the MD direction and a stretching ratio of 2.5 to 12 times in the TD direction. A method for manufacturing a laminated sheet as described in [7] or [8].

[13] The multilayer biaxially oriented film (X) is a BAB type film in which the biaxially oriented olefin resin film (B) is bonded to both surfaces of the biaxially oriented polypropylene film (A), Furthermore, the thickness of the biaxially oriented polypropylene film (A) is 30 to 80 μm. The method for manufacturing a laminated sheet according to

[12] , wherein the laminated sheet precursor (pMS) is obtained by laminating 30 to 60 BAB type films and laminating BA type films or BAA type films on both surfaces such that A is on the surface.

[14] The method for producing a laminated sheet according to [7], wherein a single-wafer vacuum laminating apparatus having planar metal plates arranged vertically in a chamber is used, the laminated sheet precursor (pMS) is placed on the lower metal plate in the chamber, hot pressing is performed while the degree of vacuum in the chamber is kept at 170 Pa or lower, and after pressing is released, the product is clamped by cooling metal plates.

[15] The method for producing a laminated sheet according to

[14] , wherein the hot pressing is performed under conditions that the temperature of the metal plates is 140 to 160°C and the cylinder pressure is 0.1 to 1 MPa.

[16] A solar cell sheet obtained by laminating a flexible solar cell module to the laminated sheet according to any one of [1] to [5]. Effects of the Invention

[0009] According to the present invention, there can be provided a biaxially stretched laminated sheet having excellent rigidity applicable to large molded articles, particularly a biaxially stretched laminated sheet in which in-plane rigidity is homogenized when the area is increased and which has little unevenness in mechanical physical properties. In addition, there can be provided a biaxially stretched laminated sheet that is excellent in surface smoothness and has small unevenness over a wide range in the plane. Brief Description of the Drawings

[0010] [Figure 1] It is a diagram showing a pressing apparatus having a continuous pressure molding mechanism. [Figure 2] As an example of the continuous pressure molding mechanism of the present disclosure, it is a diagram showing a planar mold having a plurality of thermally partitioned zones. [Figure 3] As another example of the continuous pressure molding mechanism of the present disclosure, it is a diagram showing a planar mold having a plurality of thermally partitioned zones. [Figure 4] It is a diagram showing the temperature settings of upper and lower molds in a pressing apparatus in Example 1. [Figure 5] It is a plan view of the transparent laminated sheet obtained in Example 1, showing the cut-out positions of test pieces for evaluating mechanical properties. [Figure 6]This is a plan view of the transparent laminated sheet obtained in Example 4 (sheet-wafer vacuum lamination), and shows the cutting positions of the test specimens for evaluating mechanical properties. [Figure 7] (a) This figure shows the shape and size of a dumbbell-shaped test specimen for measuring tensile modulus. (b) This figure shows the shape and size of a strip-shaped test specimen for measuring flexural modulus. [Figure 8] This is a plan view of the transparent laminated sheet obtained in Example 1, showing the cutting positions of the test specimens used to evaluate surface smoothness. [Figure 9] This is a plan view of the transparent laminated sheet obtained in Example 4 (single-wafer vacuum lamination), and shows the cutting positions of the test specimens used to evaluate surface smoothness. [Figure 10] This is a diagram showing the size of test specimens used for evaluating smoothness. [Figure 11] This diagram shows the temperature settings for the upper and lower molds in the pressurizing device in Example 2. [Figure 12] This is a plan view of the transparent laminated sheet obtained in Example 2, showing the cutting positions of the test specimens used to evaluate surface smoothness. [Figure 13] This is a plan view of the transparent laminated sheet obtained in Example 2, showing the cutting positions of the test specimens used to evaluate surface smoothness. [Figure 14] This is a conceptual diagram showing a cross-section of the single-wafer vacuum laminating apparatus used in Example 4. [Figure 15] This is a conceptual diagram showing a cross-section of the cooling device used in Example 4. [Figure 16] This diagram shows the temperature settings for the upper and lower molds in the pressurizing device in Example 3. [Figure 17] This is a conceptual diagram showing the state before and after bonding according to the present invention. [Figure 18] This is a schematic cross-sectional view showing a cross-section of a solar cell sheet according to one embodiment of the present invention. [Figure 19] This is a perspective view showing an example of a solar-powered carport using the laminated sheet of the present invention. [Modes for carrying out the invention]

[0011] The present invention will be described in more detail below. However, the present invention is not limited to the embodiments shown below.

[0012] Note that "~" means the value up to and including the value before the "~", and the value up to and including the value after the "~".

[0013] (Laminated sheet) The laminated sheet of the present invention is a laminated sheet in which a layer made of biaxially oriented polypropylene film and a layer made of olefin resin with a melting point of 110 to 160°C are alternately laminated. In the present invention, when the direction of one side of the laminated sheet is defined as the x direction and the direction perpendicular thereto as the y direction, the tensile modulus of elasticity in the x direction and the y direction at three positions including the center position in the y direction and two positions passing through this center position and located 200 mm away from the center position in the y direction are all within the range of 2000 to 5000 MPa. Furthermore, in the present invention, the biaxially oriented film used as the raw material for the laminated sheet is preferably stretched to a ratio of 2.8 × 2.8 times or more, and particularly to 3 × 3 times or more. Here, it is desirable that the x and y directions in the laminated sheet coincide with the stretching direction in the biaxially oriented film, for example, the MD direction is preferably the x direction and the TD direction is preferably the y direction.

[0014] Here, the tensile modulus in the x and y directions at the three positions mentioned above are values ​​evaluated on the test specimens cut out with these three positions as the center. Specifically, using the example of the laminated sheet shown in Figure 5 obtained in Example 1 described later, the three positions mentioned above refer to the three positions (1), (2), and (3) when, for example, the longitudinal direction of the sheet in Figure 5 is the x direction (MD direction), the point located at the center of the imaginary straight line in the y direction (TD direction) is (2), and the points located 200 mm to the left and right of (2) are (1) and (3), respectively. Note that the imaginary straight line in the y direction (TD direction) can be at any position, and the three positions (1), (2), and (3) can be determined by appropriately moving it up or down in the x direction depending on the sampling position of the test specimen. Here, as shown by the dotted lines in the figure, the test specimens for measuring the tensile modulus are dumbbell-shaped specimens with the y-direction (TD direction) as the longer side and dumbbell-shaped specimens with the x-direction (MD direction) as the longer side, cut out at (1), (2), and (3) and used for measuring the bending modulus. Here, the cutting position for the dumbbell-shaped specimen with the y-direction (TD direction) as the longer side is such that the center of the longitudinal length of the dumbbell shape coincides with (1), (2), and (3), and the cutting position for the dumbbell-shaped specimen with the x-direction (MD direction) as the longer side is such that the central axis of the dumbbell shape (for example, the dashed line in Figure 7(a)) coincides with (1), (2), and (3). The shape and size of the dumbbell-shaped specimens are shown in Figure 7(a). Furthermore, tensile modulus measurement can be performed in accordance with JIS K7161.

[0015] The present invention is characterized by the fact that, since the tensile modulus of elasticity is within a predetermined range in both the orthogonal x and y directions, the physical properties change little over a wide area within the plane, resulting in a sheet with uniform physical properties.

[0016] Furthermore, in this invention, the preferred range of tensile modulus varies depending on the film thickness and stretching ratio of the biaxially oriented film used as the raw material. For example, when a film with a thickness of 20 μm or more and less than 100 μm is used as the biaxially oriented film forming the non-surface core layer, it is possible to make the biaxially oriented film itself have a high stretching ratio, and it is preferable that the biaxially oriented film has a stretching ratio of 2.8 to 8 times in the MD direction and 8 to 12 times in the TD direction. In this case, in the case of a laminated sheet manufactured by Method 1 (pressing method using a continuous press device) described later, when the longitudinal direction is the x direction, Tensile modulus in the x-direction (MD direction): 2000-3000 MPa Tensile modulus in the y-direction (TD-direction): 3000-5000 MPa It is preferable that it be within the range of, In the case of laminated sheets manufactured by Method 2 (sheet-fed press method) described later, when the direction of one side is defined as the x-direction, Tensile modulus in the x-direction: 2000-3000 MPa Tensile modulus in the y-direction: 3000-5000 MPa It is preferable that it be within the range of [specify range]. In particular, when manufacturing by Method 2 (sheet-fed press method), when the MD direction / TD direction of the stretched raw material film is aligned and laminated, Tensile modulus in the x-direction (MD direction of the stretched film): 2000-3000 MPa Tensile modulus in the y-direction (TD direction of the stretched film): 3000-5000 MPa It is preferable that the range be within this range.

[0017] On the other hand, when a film with a thickness of 100 to 400 μm is used as the raw material stretched film that forms the core layer, which is the non-surface layer, the stretching ratio during the production of the raw material stretched film is preferably 2.8 to 8 times, preferably 3 to 6 times, in the MD direction and 2.8 to 8 times, preferably 3 to 6 times, in the TD direction. In this case, in the case of a laminated sheet produced by method 1 (pressing method using a continuous press device) described later, when the longitudinal direction is the x direction, Tensile modulus in the x-direction (MD direction): 2000~3200 MPa Tensile modulus in the y-direction (TD-direction): 2000~3200 MPa It is preferable that it be within the range of [specify range].

[0018] Furthermore, for the three y-directions tensile moduli evaluated at the aforementioned three positions, it is preferable that the coefficient of variation be 6% or less, particularly 5% or less, and especially 4.5% or less, from the viewpoint of excellent uniformity of sheet rigidity. The coefficient of variation may also be 0.5% or more. Here, the coefficient of variation is calculated by dividing the standard deviation by the mean [(standard deviation / mean) × 100 (%)].

[0019] Furthermore, for the three tensile moduli in the x-direction evaluated at the aforementioned three positions, the coefficient of variation is preferably 3% or less, more preferably 2.5% or less, and particularly preferably 2% or less. The coefficient of variation may also be 0.2% or more.

[0020] Furthermore, the bending modulus at the three positions can be explained, for example, using the example of the laminated sheet shown in Figure 5 obtained in Example 1 described later. As shown in Figure 5, strip-shaped test pieces with the y-direction as the longer side and strip-shaped test pieces with the x-direction as the longer side can be cut out at (1), (2), and (3) and used for tensile modulus measurement. In the case of a strip-shaped test piece with the y-direction as the longer side, the midpoint of the long side of the test piece coincides with the three positions (1), (2), and (3), and in the case of a strip-shaped test piece with the x-direction as the longer side, the midpoint of the short side of the test piece coincides with the three positions (1), (2), and (3). The shape and size of the cut strip-shaped test pieces are shown in Figure 7(b). Here, the bending modulus measurement can be performed in accordance with JIS K7171. Specifically, when using a biaxially oriented film as the raw material for forming the non-surface core layer, with a thickness of 20 μm or more and less than 100 μm, and a ratio of 2.8 to 8 times in the MD direction and 8 to 12 times in the TD direction, and in the case of a laminated sheet manufactured by Method 1 (pressing method using a continuous press device) described later, when the longitudinal direction is the x-direction, Flexural modulus in the x-direction (MD direction): 2000~3500 MPa Flexural modulus in the y-direction (TD-direction): 3500~6000 MPa It is preferable that it be within the range of, In the case of laminated sheets manufactured by Method 2 (sheet-fed press method) described later, when the direction of one side is defined as the x-direction, Flexural modulus in the x-direction: 2000~3500 MPa Flexural modulus in the y-direction: 3500~6000 MPa It is preferable that it be within the range of [specify range]. In particular, when the MD direction and TD direction of the stretched raw material film are aligned and laminated, Flexural modulus in the x-direction (MD direction of the raw film): 2000~3500 MPa Flexural modulus in the y-direction (direction of the raw material film TD): 3500~6000 MPa It is preferable that it be within the range of [specify range].

[0021] On the other hand, in the case of a laminated sheet manufactured by Method 1 (pressing method using a continuous press device), a biaxially oriented film with a thickness of 100 to 400 μm is used as the raw material for forming the non-surface core layer, and the biaxially oriented film has a biaxial stretching ratio of 2.8 to 8 times, preferably 3 to 6 times, in the MD direction and 2.8 to 8 times, preferably 3 to 6 times, in the TD direction. Flexural modulus in the x-direction (MD direction): 2500~3500 MPa Flexural modulus in the y-direction (TD-direction): 2500~3500 MPa It is preferable that it be within the range of [specify range].

[0022] Furthermore, for the three y-direction flexural moduli evaluated at the aforementioned three positions, the coefficient of variation is preferably 6.5% or less, more preferably 5.5% or less, and particularly preferably 4.8% or less. The coefficient of variation may also be 0.5% or more.

[0023] Furthermore, for the three flexural moduli evaluated at the aforementioned three positions, the coefficient of variation of the three x-directions is preferably 4% or less, more preferably 3.5% or less, and particularly preferably 3% or less. The coefficient of variation may also be 0.2% or more.

[0024] As described above, the laminated sheet of the present invention is characterized by its large surface area and physical homogeneity. Therefore, it is preferable that the length of one side be 400 mm or more, and in particular, sheets with a length of 500 mm or more, 600 mm or more, 1300 mm or more, or 2000 mm or more are possible. In particular, when manufacturing the laminated sheet by Method 1 (press method using a continuous press device) described below, if the sheet feeding direction is the x-direction, the length in the y-direction perpendicular to this, i.e., the laminated sheet width, can be 400 mm or more, 500 mm or more, 600 mm or more, 1300 mm or more, or 2000 mm or more. In this case, with Method 1 (press method using a continuous press device), if the biaxially oriented film used as raw material is supplied from a roll, there is no restriction on the length in the x-direction, and it can be appropriately selected according to the purpose.

[0025] Furthermore, the laminated sheet of the present invention preferably has the following characteristics.

[0026] The laminated sheet of the present invention is further preferably made uniform in surface smoothness for superior appearance. For example, by laminating or sandwiching a decorative film between layers, it can be made into a highly aesthetic, paint-free design material. Specifically, in a plan view of the laminated sheet, a square measuring 595 mm x 595 mm is drawn such that the intersection of its diagonals is the center position in the x or y direction, and one side of the square is parallel to one side of the laminated sheet. If the intersection of the diagonals is denoted as α, the midpoint between the corners of the square from the intersection of the diagonals is denoted as β, and the corner of the square is denoted as γ, then it is preferable that the difference (ΔRa) between Ra(α) and Ra(β) or Ra(γ) (ΔRa) satisfies the following equations (1) and (2). The positions of α, β, and γ mentioned above can be explained using, for example, the laminated sheet shown in Figure 8 obtained in Example 1 described later. For example, these are the positions of α, β, and γ shown in Figure 8.

[0027] △Ra(α,β)=Ra(α)-Ra(β)<0.3 (1) △Ra(α,γ)=Ra(α)-Ra(γ)<0.3 (2)

[0028] The above-mentioned Ra(α), Ra(β), and Ra(γ) are the average values ​​(average roughness) obtained when the surface roughness of each test piece is measured at two locations on each test piece, which is cut out in the shape of a strip with the MD direction as its longer side from the positions of α, β, and γ, respectively. Examples of test pieces include those shown in Figure 10. The two measurement locations on a single test piece are measurement location (1) and measurement location (2) shown in Figure 10.

[0029] Furthermore, using Ra(α) as a reference, the relative roughness ΔRa(β) and ΔRa(γ) at β and γ can be expressed as follows:

[0030] ΔRa(β)=[(Ra(β)−Ra(α)) / Ra(α)]×100 (3) ΔRa(γ)=[(Ra(γ)−Ra(α)) / Ra(α)]×100 (4) Preferably, ΔRa(β) is 100% or less, and ΔRa(γ) is 100% or less.

[0031] The biaxially oriented film used as the raw material for the laminated sheet of the present invention may be prepared by adjusting the biaxially oriented polypropylene film (A) that constitutes the a layer and the biaxially oriented olefin resin film (B) that constitutes the b layer. However, it is preferable to use a multilayer biaxially oriented film (X) in which the biaxially oriented polypropylene film (A) that constitutes the a layer and the biaxially oriented olefin resin film (B) that constitutes the b layer are laminated on at least one surface thereof. Here, it is particularly preferable that the multilayer biaxially oriented film (X) is manufactured by co-extrusion, as this provides excellent adhesion between (A) and (B). That is, in the present invention, it is preferable to manufacture the laminated sheet by stacking multiple multilayer biaxially oriented films (X) and heat-sealing them together. Therefore, it is preferable that the stretching ratios in the MD direction and TD direction of the biaxially oriented film used as the raw material are the stretching ratios of the multilayer biaxially oriented film (X).

[0032] In the present invention, as described above, it is preferable that the biaxially oriented film used as the raw material, particularly the multilayer biaxially oriented film (X), has a stretching ratio of 2.8 to 8 times in the MD direction and a stretching ratio of 2.8 to 12 times in the TD direction, as this maintains a high degree of orientation of the biaxially oriented polypropylene film (A) in the laminated sheet, resulting in excellent rigidity. Such a laminated sheet of the present invention can be manufactured by the manufacturing method described in the "Method for Manufacturing a Laminated Sheet" below.

[0033] The multilayer biaxially oriented film (X) can be an AB type in which a biaxially oriented olefin resin film (B) is laminated on one side of a biaxially oriented polypropylene film (A), an AAB type in which film (A) and then film (B) are laminated on one side of a biaxially oriented polypropylene film (A), or a BAB type in which film (B) is laminated on both sides of a biaxially oriented polypropylene film (A). These can be used in combination as appropriate, but it is particularly preferable to stack multiple BAB type films and laminate an AB type film or an AAB type film on both surfaces such that layer A is on the surface.

[0034] The size of the laminated sheet of the present invention can be appropriately selected depending on the application. The present invention has the unprecedented features of being able to produce a large-area laminated sheet and having high rigidity. As mentioned above, it is preferable to have a sheet with a side length of 400 mm or more, particularly 500 mm or more, 600 mm or more, 1300 mm or more, or 2000 mm or more. In particular, when manufacturing the laminated sheet by method 1 below (press method using a continuous press device), when the sheet feeding direction is the x direction, it is preferable to have a laminated sheet with a length in the y direction perpendicular to it, i.e., a laminated sheet width of 400 mm or more, 500 mm or more, 600 mm or more, 1300 mm or more, or 2000 mm or more. For example, it is preferable to have a laminated sheet with at least one side length of 500 to 2000 mm and a side length perpendicular to it that is greater than or equal to that.

[0035] For example, in the case of laminated sheets manufactured by Method 1 (pressing method using a continuous press device) described later, it is preferable that the length in the y direction (TD direction) is 500 to 2000 mm and the length in the x direction (MD direction) is longer than that. Furthermore, according to the manufacturing method (Method 1) described later, it is possible to manufacture sheets with lengths of several meters in the x direction (MD direction) freely, as they can be manufactured continuously. However, when used in industrial products, housing, or automobile exterior components, it is preferable that the length in the x direction (MD direction) is 1000 to 3000 mm, as this results in good processability for secondary molding and other processes. Furthermore, when manufacturing laminated sheets using Method 2 (sheet-fed press method) described later, it is preferable that the length of one side (length in the x or y direction) be 500 to 2000 mm, as this is a batch manufacturing method.

[0036] (Method of manufacturing laminated sheets) The method for manufacturing the above-described laminated sheet includes a preparation step of forming a laminated sheet precursor (pMS) by alternately stacking multiple sheets of biaxially oriented polypropylene film (A) and biaxially oriented olefin resin film (B), preferably manufactured by co-extrusion, and stacking multiple sheets of multilayer biaxially oriented film (X), which is made by laminating a biaxially oriented polypropylene film (A) and a biaxially oriented olefin resin film (B) on at least one surface thereof, to form a laminated sheet precursor (pMS); The method includes a pressing step in which the laminated sheet precursor (pMS) is heated and pressed across its surface. In this invention, since the laminated sheet precursor (pMS) is heated and pressed on a surface rather than in a roll, a laminated sheet can be obtained that has high rigidity, excellent homogeneity, and minimal variations in physical properties depending on the area.

[0037] <Preparation process for laminated sheet precursor (pMS)> The aforementioned preparation steps for the laminated sheet precursor (pMS) are, specifically, Preparation step 1: A step of alternately stacking multiple sheets of biaxially oriented polypropylene film (A) and biaxially oriented olefin resin film (B) to form a laminated sheet precursor (pMS), and, Preparation step 2: A step to form a laminated sheet precursor (pMS) by stacking multiple multilayer biaxially oriented films (X) in which a biaxially oriented polypropylene film (A) and a biaxially oriented olefin resin film (B) are laminated on at least one surface thereof. These are some examples. Among these, preparation step 2 is particularly preferred because it provides good adhesion between (A) and (B). Furthermore, the multilayer biaxially oriented film (X) may be manufactured by laminating a biaxially oriented polypropylene film (A) and a biaxially oriented olefin resin film (B), but it is preferable that it be manufactured by co-extrusion because it provides good adhesion between the layers.

[0038] Here, it is preferable that the biaxially oriented polypropylene film (A) has a stretching ratio of 2.8 to 8 times in the MD direction and a stretching ratio of 2.8 to 12 times in the TD direction during film production, while the biaxially oriented olefin resin film (B) has a stretching ratio of 2.8 to 8 times in the MD direction and a stretching ratio of 2.5 to 12 times in the TD direction, as this dramatically improves the rigidity of the final laminated sheet and also exhibits appropriate secondary moldability.

[0039] When the multilayer biaxially oriented film (X) is manufactured by co-extrusion, if the multilayer biaxially oriented film (X) is 20 μm or more and less than 100 μm thick, it is possible to highly stretch the film itself, and a stretch ratio of 2.8 to 8 times in the MD direction and 8 to 12 times in the TD direction during the production of the raw film is preferable in terms of good rigidity of the laminated sheet. Furthermore, biaxial stretching can be carried out by sequential stretching or simultaneous stretching. On the other hand, when manufacturing a film of 100 to 400 μm thickness, it is preferable to have a stretch ratio of 2.8 to 8 times in the MD direction and 2.8 to 8 times in the TD direction during the production of the film, and in particular, a stretch ratio of 3 to 6 times in the MD direction and 3 to 6 times in the TD direction is preferable.

[0040] Furthermore, the multilayer biaxially oriented film (X) can be any of the following: a BA-type film having a structure in which the biaxially oriented olefin resin film (B) is laminated only on one surface of the biaxially oriented polypropylene film (A); a BAA-type film having a structure in which two biaxially oriented polypropylene films (A) are stacked and the biaxially oriented olefin resin film (B) is laminated only on one surface; a BAB-type film having a structure in which the biaxially oriented olefin resin film (B) is laminated on both surfaces of the biaxially oriented polypropylene film (A); or a BAC-type film having the biaxially oriented olefin resin film (B) laminated on one surface of the biaxially oriented polypropylene film (A) and a modified polypropylene resin film (C) laminated on the other surface.

[0041] Such multilayer biaxially oriented films (X) can be appropriately selected and combined to obtain a precursor (pMS) depending on the purpose. However, in the present invention, it is preferable to use multiple BAB-type films stacked together, as shown below, with BA-type and BAA-type films used so that film (A) is located on the surface layer.

[0042] AB / BAB / BAB / BAB / / BAB / BAB / BAB / BA AAB / BAB / BAB / BAB / ··· / BAB / BAB / BAB / BAA

[0043] Alternatively, when further laminating a decorative film or applying printing, it is preferable to use a BAC-type film on the surface layer such that film (C) is positioned on the surface forming the laminated surface or printed surface, as shown below. CAB / BAB / BAB / BAB / / BAB / BAB / BAB / BAA

[0044] Examples of multilayer biaxially oriented films (X) include a BAB-type film consisting of two types of three layers with a thickness of 30 μm or more and less than 100 μm (x1), or a two types of three layers with a thickness of 100 to 400 μm (x2). Furthermore, while the thickness ratio of B / A / B in the BAB type film is preferably, for example, B / A / B = 2~20 / 96~60 / 2~20, it is desirable to ensure as much thickness of the A layer as possible from the standpoint of increasing rigidity, and in particular, B / A / B = 2~15 / 96~70 / 2~15 is preferred. When the multilayer biaxially oriented film (X) is a two-type, three-layer film (x1) with a thickness of 30 μm or more and less than 100 μm, it is preferable to laminate 30 to 60 sheets and then overlay a BA-type film or a BAA-type film on the surface with the A layer facing outwards. Alternatively, when printing is applied to the laminated sheet or a decorative film is laminated, it is preferable to use a BAC-type film instead of a BA-type or BAA-type film, with the C layer facing outwards. On the other hand, if the multilayer biaxially oriented film (X) is a two-type three-layer film (x2) with a thickness of 100 to 400 μm, it is preferable to laminate 2 to 20 sheets and then layer a BA-type film and a BAA-type film on the surface with the A layer facing outwards. Alternatively, if printing is applied to the laminated sheet or a decorative film is laminated, it is preferable to use a BAC-type film instead of a BA-type film and a BAA-type film, with the C layer facing outwards.

[0045] The thickness of the BA type film is preferably 20 to 300 μm, and the thickness ratio of each layer [B / A] is preferably 5 to 20 / 95 to 80. The thickness of the BAA type film is preferably 30 to 300 μm. 、 The thickness ratio of each layer [B / A / A] is 5~20 / 95~80 (Total of [A / A]) It is preferable that the BAC type film has a thickness of 30 to 300 μm, and the thickness ratio of each layer [B / A / C] is preferably 2 to 20 / 96 to 60 / 2 to 20.

[0046] The size of the laminated sheet precursor (pMS) in this invention can be appropriately selected to match the size of the laminated sheet to be manufactured in the pressing process of Method 1 (pressing method using a continuous press device) or Method 2 (single-wafer pressing method), as described later.

[0047] When laminating multilayer biaxially oriented films (X), they may be laminated with their MD / TD directions aligned, or they may be laminated so that they intersect each other. However, when manufacturing a laminated sheet by Method 1 (pressing method using a continuous press device), it is preferable to laminate them with their MD / TD directions aligned, as this allows the multilayer biaxially oriented films (X) to be supplied to the continuous press machine in a roll state.

[0048] On the other hand, when manufacturing laminated sheets by method 2 (sheet-fed press method) described later, it is preferable to laminate them with the MD direction and TD direction aligned from the viewpoint of workability and productivity, while on the other hand, from the viewpoint of homogeneity of orientation, it is preferable to laminate them so that they intersect each other.

[0049] [Biaxially oriented polypropylene film (A)] Here, the biaxially oriented polypropylene film (A) can be obtained by biaxially stretching a polypropylene polymer or a polypropylene composition containing the polypropylene polymer and a nucleating agent or other additives using a known method. For example, an unstretched sheet can be obtained by extruding the polypropylene or the like, and a biaxially oriented film can be obtained by biaxially stretching the sheet. However, as mentioned above, in the present invention, it is preferable to form and stretch the film together with other layers by co-extrusion.

[0050] The polypropylene polymers used here specifically include propylene homopolymers, propylene random copolymers obtained by polymerizing monomer components containing at least one selected from C2-C10-α-olefins (excluding C3-α-olefins) in an amount of 1% by weight or less, and mixtures thereof.

[0051] Among these, a propylene random copolymer (hereinafter sometimes simply referred to as "propylene random copolymer") obtained by polymerizing a monomer component containing ethylene at a concentration of 1% by weight or less is particularly preferred because it can impart excellent stretchability to the sheet while maintaining high rigidity and toughness.

[0052] Here, the polypropylene polymer is preferable because its Mw / Mn ratio has a relatively wide molecular weight distribution of 6 to 20, resulting in good thickness-to-thinness accuracy, as well as the ability to combine high rigidity and high stretchability, and furthermore, ease of film formation.

[0053] Furthermore, it is preferable that the amount of xylene-insoluble content in the polypropylene polymer is greater than 96.5% by mass and less than or equal to 99.5% by mass. The xylene-insoluble components of polypropylene correspond to crystalline isotactic components. In contrast, the xylene-soluble components contained in small amounts in polypropylene correspond to non-crystalline atactic components, and have a lower molecular weight compared to the xylene-insoluble components. Moreover, the statement that the amount of xylene-insoluble content in the polypropylene polymer is greater than 96.5% by mass and less than or equal to 99.5% by mass is equivalent to the crystalline components of the polypropylene resin material being greater than 96.5% by mass and less than or equal to 99.5% by mass. Furthermore, from the standpoint of obtaining good rigidity and heat resistance, particularly rigidity, of the (secondary) molded product obtained by thermoforming the sheet, it is especially preferable that the amount of xylene-insoluble content is in the range of greater than 97.0% by mass and less than or equal to 99.5% by mass.

[0054] Furthermore, the crystalline component of the polypropylene polymer preferably has a stereoregularity (mmmm) of 97.5 to 99.5%. If the mmmm is less than 97.5%, the rigidity and heat resistance, especially the heat resistance, of the (secondary) molded product obtained by thermoforming a sheet made of the polypropylene composition will decrease.

[0055] When using the propylene random copolymer as the polypropylene polymer, the ethylene content in the raw material monomer component is preferably 0.1% by mass or more and less than 1% by mass, preferably 0.1% by mass or more and less than 0.6% by mass, and particularly preferably 0.1% by mass or more and less than 0.3% by mass, in order to enhance the stretchability while maintaining the toughness and rigidity of the sheet.

[0056] Herein, the propylene random copolymer also has the characteristic of improved transparency due to the random copolymerization of propylene with ethylene. Furthermore, if the ethylene content in the raw material monomer components is less than 1% by mass, it will have excellent rigidity. The lower limit of the ethylene content is not particularly limited and is greater than 0% by mass, but 0.1% by mass or more is preferred in that the effect of improving transparency is easily obtained.

[0057] The MFR of the polypropylene polymer is 1 to 15 g / 10 min, with 2 to 6 g / 10 min being preferred. When the MFR is within this range, the moldability of the polypropylene composition when forming it into a sheet is excellent. While the aforementioned polypropylene polymer is preferably used as a polypropylene composition containing a nucleating agent from the viewpoint of transparency, in the present invention, by using a smaller amount of this nucleating agent than usual, haze can be reduced and transparency can be further improved.

[0058] The content of the nucleating agent in the polypropylene composition is preferably less than 0.18 parts by mass, and particularly preferably 0.15 parts by mass or less, per 100 parts by mass of the ethylene-containing propylene polymer. Below the above upper limit, excellent thickness-to-thinness accuracy is easily obtained, resulting in a polypropylene composition with excellent film-forming properties while maintaining toughness and rigidity. Here, there is no particular lower limit to the content of the nucleating agent, but it is preferably 0.01 parts by mass or more in terms of the effect of improving transparency.

[0059] The polypropylene composition of the present invention preferably has a crystallization rate parameter (t1 / 2) greater than 1 second, and more preferably 2 seconds or more. Reducing the amount of nucleating agent tends to decrease the crystallization rate and increase (t1 / 2). When (t1 / 2) is greater than the lower limit mentioned above, excellent thickness-to-thinness accuracy is easily obtained. Furthermore, there is no particular upper limit to (t1 / 2), but it is preferably about 5 seconds or less.

[0060] [Crystallizing agent] The amount of the nucleating agent described above is preferably more than 0 parts by weight and 1.0 part by weight or less, more preferably 0.05 to 0.5 parts by weight, per 100 parts by weight of polypropylene. A nucleating agent is an additive (transparent nucleating agent) used to control the size of crystalline components in the resin to reduce transparency. The nucleating agent is not particularly limited, and those commonly used in this field may be used, but it is preferable to select from nonitol-based nucleating agents, sorbitol-based nucleating agents, phosphate ester-based nucleating agents, triaminobenzene derivative nucleating agents, carboxylate metal salt nucleating agents, and xylitol-based nucleating agents. An example of a nonitol-based nucleating agent is 1,2,3-trideoxy-4,6:5,7-bis-[(4-propylphenyl)methylene]-nonitol. An example of a sorbitol-based nucleating agent is 1,3:2,4-bis-o-(3,4-dimethylbenzylidene)-D-sorbitol. Examples of phosphate ester-based nucleating agents include lithium phosphate-2,2'-methylenebis(4,6-di-tert-butylphenyl) salt-based nucleating agents.

[0061] [Other additives] The polypropylene composition of the present invention may contain other additives besides the nucleating agent, as long as they do not impair the effects of the present invention. Other examples of additives include common additives typically used in polyolefins, such as antioxidants, neutralizing agents, chlorine absorbers, heat stabilizers, light stabilizers, UV absorbers, internal lubricants, external lubricants, antiblocking agents, antistatic agents, antifogging agents, flame retardants, dispersants, copper pollution inhibitors, plasticizers, crosslinking agents, peroxides, oil spreaders, and other organic and inorganic pigments. The amount of each additive may be a known amount.

[0062] [Preparation of polypropylene polymers or polypropylene compositions] The polypropylene polymers or polypropylene compositions described in detail above can be prepared, for example, by Production Examples 2 to 7 of Japanese Patent No. 6845001.

[0063] <Biaxially oriented olefin resin film (B)>

[0064] The biaxially oriented olefin resin film (B) with a melting point of 110 to 160°C used in the method for manufacturing the laminated sheet of the present invention can be obtained by biaxially oriented an olefin resin or an olefin resin composition containing the olefin resin and additives using a known method. For example, an unoriented sheet can be obtained by extruding the olefin resin, etc., and then a biaxially oriented film can be obtained by biaxially oriented the sheet. However, as described above, in the present invention, it is preferable to form and stretch the film together with other layers by co-extrusion. The olefin resin constituting the biaxially oriented olefin resin film (B) has a melting point of 110 to 160°C. Here, the melting point is measured using DSC under the condition of heating from 30°C to 230°C at a heating rate of 10°C / min. Since this melting point range is sufficiently lower than that of the polypropylene constituting layer A, good fusion properties are obtained when heated and pressed. Specifically, such an olefin resin is preferably formed from a propylene homopolymer (HOMO); a propylene random copolymer (RACO) containing 5% by weight or less of at least one comonomer selected from C2-C10-α olefins (excluding C3-α olefins); or a resin composition containing HOMO or RACO. If the comonomer content is too low, the fusion properties with the first layer may not be sufficient, and if it is too high, the rigidity of the laminated sheet may decrease. From this viewpoint, the comonomer content is preferably more than 0% by weight and 4.5% by weight or less. Ethylene (C2-α olefin) is preferred as the comonomer. The MFR (at 230°C and under a load of 2.16 kg) of the polymer or resin composition constituting the second layer is not limited, but is preferably 1 to 15 g / 10 min, more preferably 2 to 10 g / 10 min, and even more preferably 3 to 8 g / 10 min. The above-mentioned olefin resin may contain a nucleating agent, or it may consist of a resin composition or polymer that does not contain a nucleating agent. If a nucleating agent is included, from an economic standpoint, the amount of the nucleating agent is preferably 1 part by weight or less per 100 parts by weight of the polymer forming the second layer. Therefore, the biaxially oriented olefin resin film (B) is preferably composed of a resin composition containing HOMO and a nucleating agent, or a resin composition containing RACO and a nucleating agent. The thickness of the biaxially oriented olefin resin film described above is preferably in the range of 1 to 20 μm per layer, and more preferably in the range of 2 to 10 μm.

[0065] <Modified olefin resin film (C)> Next, the modified olefin resin film (C) can be obtained by biaxially stretching a modified olefin resin or an olefin resin composition containing the olefin resin and additives using a known method. For example, the modified olefin resin can be extruded to obtain an unstretched sheet, and the sheet can be biaxially stretched to obtain a biaxially oriented film. However, as described above, in the present invention, it is preferable to produce and stretch the film together with other layers by co-extrusion. The modified olefin resin constituting the biaxially oriented olefin resin film (B) includes, for example, polypropylene having various functional groups such as carboxyl groups, acid anhydride groups, sulfonic acid groups, phosphate groups, phosphate ester groups, imino groups, and amino groups in its molecular structure. Polypropylene having carboxyl groups, acid anhydride groups, and imino groups is particularly preferred because it exhibits excellent adhesion to the printed layer or to other components. Examples of such functionally group-containing modified olefins include Mitsui Chemicals' "Admer Film QB515," "Admer Film QB550," "Admer Film QF500," "Admer Film QF551," "Admer Film QF580," "Admer Film QE840," and "Admer Film QE060."

[0066] <Pressing Process>

[0067] The process of heating and pressing the laminated sheet precursor (pMS) obtained in this manner can be carried out by either Method 1 or Method 2, which are detailed below.

[0068] [Method 1] Continuous pressure pressing method Method 1 involves continuously heating and pressing a laminated sheet precursor (pMS) in a flat mold using a continuous pressurizing device, followed by a cooling and pressing step. The flat mold refers to a mold with a flat contact surface.

[0069] When such method 1 is adopted, the surface condition of the resulting laminated sheet is good, the surface irregularities that appear as so-called surface waviness are reduced, and the transparency of the laminated sheet itself is also excellent, which is preferable.

[0070] Method 1 will be described in more detail below.

[0071] The continuous compression device used in Method 1 is a continuous compression molding (CCM) device with a continuous compression molding mechanism, and has multiple heating zones and cooling zones. It has a mechanism for heating and pressing the laminated sheet precursor (pMS) with upper and lower planar molds in the heating zone, and a mechanism that can subsequently and continuously cool and press the laminated sheet with upper and lower planar molds in the cooling zone to age it.

[0072] Using such a continuous pressurizing device increases the design flexibility for the size in the MD direction. Furthermore, because the material is continuously transferred and pressed from the heating zone to the cooling zone, it is possible to obtain laminated sheets with excellent rigidity and uniform strength, as well as superior surface condition and transparency.

[0073] A specific method for pressing a laminated sheet precursor (pMS) using the continuous pressurizing device involves continuously or intermittently introducing the laminated sheet precursor (pMS) into the gap between the upper and lower planar molds constituting the heating zone of the continuous pressurizing device, heating it to 110-170°C, and pressing it under pressure conditions of 1-40 MPa. After releasing the press, the sheet is fed forward for a predetermined length in a predetermined direction, and heating and pressing are performed again. This process is repeated to continuously or intermittently transfer the sheet from the heating zone to the cooling zone. In the cooling zone, pressing, pressure release, and transfer are performed at a temperature of 25-125°C and a pressure of 1-40 MPa, thereby gradually discharging the heat-fused laminated sheet from the gap between the upper and lower planar molds. In the cooling zone, it is preferable to age the sheet at a relatively high temperature, and the temperature of the cooling zone is particularly preferably 60-125°C.

[0074] Here, the size (pitch) of the laminated sheets fed out when the press is released is not particularly limited, but it is preferably in the range of 10 to 300 mm. Also, the press release time is preferably 0.5 to 3 seconds from the viewpoint of uniformity of bonding.

[0075] To further describe the pressurizing device (continuous pressurizing device) with a continuous pressure molding mechanism, the continuous pressurizing device 100 has a pair of upper and lower molds 2 formed in a planar shape, as shown in Figure 1. Each of the upper and lower molds 2 has a pair of upper and lower heating / cooling plate modules 4, respectively, which can heat / cool the upper and lower molds 2. In addition, the upper flat mold is configured to be pressurized from above by a hydraulic cylinder 6, a lifting unit 8, and a lifting guide 10.

[0076] Furthermore, the mold unit in the direction of travel has a drawer unit 12 at its front that has the function of drawing out the laminated sheet (MLS) by moving back and forth in the MD direction (machine direction).

[0077] Here, the pair of upper and lower molds 2, formed in a planar shape, are thermally divided into a heating zone and a cooling zone with respect to the sheet travel direction (MD direction). Preferably, they are also thermally divided in a direction perpendicular to the sheet travel direction (TD direction). For example, a planar mold having multiple thermally divided zones can be cited, as shown in Figure 2. Note that "thermally divided" here does not necessarily mean that the set temperatures are different; it is sufficient that the zones are divided so that the heat sources are different.

[0078] For example, as shown in Figure 2, zones H1 to H3 are heating zones, and zones C1 to C2 are cooling zones. Furthermore, the TD direction is thermally divided into five sections.

[0079] Furthermore, an example of a structure with multiple thermal zones is shown in Figure 3.

[0080] In Figure 3, zones H1 to H4 are heating zones, and zones C1 to C3 are cooling zones. The heating zones are further divided thermally into 4 sections in the MD direction and 12 sections in the TD direction, while the cooling zones are divided thermally into 3 sections in the MD direction and 5 sections in the TD direction.

[0081] In the present invention, the number of stages in the MD direction of the heating and cooling zones can be appropriately selected depending on the size of the laminated sheet (MLS) to be manufactured. However, it is preferable that the heating zone is thermally divided into 2 to 10 stages, preferably 2 to 6 stages, in the MD direction, and the cooling zone into 1 or 2 to 5 stages, in the MD direction, as this facilitates thermal control, allows for excellent uniformity of in-plane rigidity according to the desired thickness, reduces physical property variations, and enables the manufacture of a laminated sheet with superior surface smoothness.

[0082] Here, "thermally partitioned" means not only that the mold itself is physically divided into individual parts, but also that, although it appears to be a uniformly extended flat metal plate, its temperature is controlled by heaters corresponding to each zone, resulting in a multi-stage thermally controlled state.

[0083] The set temperature for each heating zone is preferably set to 110-160°C for the first heating zone, which is closest to the sheet entrance (insertion opening) of the multi-layered stretched film, and to +10-40°C for the second heating zone relative to the first heating zone, and then sequentially by +0-30°C relative to the previous zone, up to a maximum of 170°C. On the other hand, the set temperature for the cooling zone is preferably set to -2-10°C from the final heating zone, and if there are subsequent cooling zones, to -30-60°C relative to the previous cooling zone. Furthermore, the temperature of the final cooling zone is preferably 25°C-125°C, and particularly preferably 60°C-125°C.

[0084] Furthermore, as described above, the laminated film inserted between the upper and lower molds 2 is pressurized by a plurality of cylinders 6 located on the upper part of the upper mold and pressed by the upper and lower molds 2. As mentioned above, the press pressure at this time is preferably 1 to 40 MPa, and when the press is released, the laminated sheet (MLS) is fed out in a predetermined width.

[0085] Furthermore, in order to improve the surface smoothness of the laminated sheet (MLS), it is preferable to interpose a sheet-like release material between the laminated sheet and the planar mold 2. Examples of sheet-like release materials used here include paper material, polyethylene terephthalate sheet, polycarbonate sheet, polypropylene sheet, and steel plate, but among these, polycarbonate sheet and steel plate are preferred because they can further improve the surface condition of the laminated sheet.

[0086] The laminated sheet obtained in this manner maintains the orientation of the polypropylene constituting each layer appropriately, while the interlayers are sufficiently fused, resulting in a highly rigid laminated sheet overall. As described above, it exhibits unique properties such as excellent uniformity of strength within the plane, minimal variation in physical properties, and particularly uniform strength in the TD direction when applied to a large area.

[0087] [Method 2] Single-wafer press method Next, Method 2 is a method for manufacturing the laminated sheet (MLS) of the present invention by a single-wafer press method, and specifically comprises the steps of: placing the laminated sheet precursor (pMS) on the lower metal plate in the chamber using a single-wafer vacuum bonding apparatus having planar metal plates on the upper and lower sides of the chamber; heating and pressing while maintaining a vacuum of 170 Pa or less in the chamber; and after releasing the press, clamping it with a cooling metal plate.

[0088] Specifically, as schematically shown in Figure 14, a film laminate made by stacking multiple biaxially oriented films is placed between a pair of upper and lower heating plates (204, 205) arranged inside the chamber (202) of a single-wafer vacuum laminating apparatus (200). Then, after closing the lid of the chamber (202), the heating plates (204, 205) are heated to a predetermined temperature while the pressure inside is reduced. Subsequently, pressure is applied from a hydraulic cylinder (203) and held for a predetermined time. Then, the internal pressure is returned to atmospheric pressure and the cylinder pressure is released to remove the laminated sheet (MLS). Next, it is quickly transferred to a cooling device (300) as shown in Figure 15, where it is sandwiched between a pair of upper and lower cooling metal plates (301, 302) and cooled at room temperature. The film laminate may be placed directly in the chamber of the single-wafer vacuum laminating apparatus, but as shown in Figure 14, it is preferable to sandwich its upper and lower surfaces between stainless steel plates (s) before heating and pressurizing, as this results in a better surface condition for the resulting laminated sheet (MLS). Here, the stainless steel plates (s) that sandwich the film laminate are preferably 0.3 to 1 mm thick. Furthermore, as shown in Figure 14, a diaphragm (d) may be interposed directly below the upper heating plate, and a polytetrafluoroethylene sheet (pt) may be interposed between the heating plate and the stainless steel plates (s) for the purpose of protecting the heating plate. The heating plate of such a single-wafer vacuum bonding apparatus is preferably set to a temperature of 140 to 155°C, and the pressure of the hydraulic cylinder is preferably 0.1 to 10 MPa. By manufacturing using this single-wafer pressing method, it is possible to obtain laminated sheets with even higher rigidity and strength, as well as superior uniformity.

[0089] [Laminated Sheet] An example of a laminated sheet (MLS, 70) obtained by Method 1 or Method 2 as described in detail above is shown in Figure 17, in which a laminated sheet precursor (pMS) (60) containing multiple multilayer biaxially oriented films (X) (62, 64a, 64b) is laminated and fused at the B / B boundary, resulting in the fused layer becoming integrated to form layer b, and consequently, a structure in which layers a and b are laminated to each other.

[0090] [Molded products] The molded articles in this invention are obtained by molding the laminated sheet (MLS) of the present invention. Various molded articles can be obtained by molding the laminated sheet of this embodiment. Known molding methods include press molding, hot plate molding, stretch molding, rolling molding, deep drawing, pressure welding, fusion molding, vacuum forming, pressure forming, and vacuum pressure forming. Among these, the present invention has the unprecedented feature of enabling the industrial production of large-area laminated sheets, making it preferable to process them into various molded products by press forming. The temperature conditions for secondary molding of the laminated sheet can be appropriately selected depending on the shape and depth of drawing, but for example, it is possible to mold at a temperature of 100°C or higher but below the melting point of the laminated sheet (MLS), and in particular when molding into molded products with shallow drawing, such as mobility exterior materials and housing building materials, molding can be done at 120 to 150°C.

[0091] [Applications of laminated sheets] The laminated sheet of the present invention, as detailed above, has excellent rigidity as a plastic material and can be widely used industrially as an aluminum substitute, CFRP substitute, or steel plate substitute. Examples include automotive exterior materials, automotive interior materials, automotive structural materials, flying car exterior materials, building exterior wall materials, building interior materials, solar cell substrates, substrate sheets for flexible solar cells, quantum stealth optical materials, logistics drone body materials, surfboards, wind turbine blades, ship exterior wall materials, lithium-ion battery case materials, lithium-ion battery electrode substrates, hydrogen tank structural materials, food trays, medical trays, and the like.

[0092] Among these, for example, by using it as a body material for automobile exteriors, it becomes possible to recycle the body material. Furthermore, by laminating a decorative film onto the polypropylene laminated sheet of the present invention, or by sandwiching it between the layers of the laminated sheet of the present invention, it can be used as a paint-free automobile exterior material. When using such a decorative film, for example, the B-layer surface or C-layer surface of the AB film, BAB film, or BAC film used as the base film can be corona-treated and then printed to create the decorative film. In this case, by laminating the printed surface of the decorative film onto the laminated sheet of the present invention, a decorative sheet with an excellent appearance can be obtained. If the printed layer is prone to peeling, the surface of the laminated sheet of the present invention can be corona-treated, and the printed surface of the decorative film can be superimposed and bonded to the laminated sheet's printed surface so that the printed surfaces are in contact with each other, thereby effectively preventing peeling from the printed surface. Furthermore, the hydrogen tank structural material can be used, for example, as a Type 2 or Type 4 high-pressure hydrogen tank structural material.

[0093] (Solar sheet) The solar cell sheet of the present invention is formed by laminating a flexible solar cell module to the laminated sheet of the present invention described above. The solar cell sheet of the present invention may be formed by laminating a flexible solar cell module to the front or back surface of the laminated sheet of the present invention, or by sandwiching and laminating it between the laminated sheets of the present invention described above on both sides. Here, examples of the flexible solar cell module include film-like or sheet-like solar cell modules such as thin-film silicon solar cells, organic thin-film solar cells, and perovskite solar cells. Figure 18 shows one embodiment of the solar cell sheet of the present invention. Figure 18 is a schematic cross-sectional view of the solar cell sheet of the present invention, which has a structure in which a flexible solar cell module is sandwiched and bonded between the laminated sheets of the present invention on both sides.

[0094] The solar cell sheet of the present invention can be pre-shaped to conform to the shape of a building's wall, roofing material, or columnar structure, for example, thereby achieving a sense of visual unity with the object to which it is attached. Compared to conventional panel-type silicon solar cells, the aesthetic appearance when solar panels are installed can be dramatically improved. Furthermore, in this case, the sense of integration with the object to which it is attached, such as a building, is enhanced, making it possible to securely fix it in place for a long period after installation. This allows for longer-term use compared to simply attaching film-type solar cell modules to existing buildings.

[0095] Furthermore, the solar cell sheet of the present invention is preferably used as a solar cell sheet having an arched monocurved surface. Such a solar cell sheet having an arched monocurved surface can be obtained, for example, by forming the laminated sheet of the present invention into a monocurved surface with curvature in only one direction, and then bonding it to a flexible solar cell module on the front or back surface of the laminated sheet, or by sandwiching a flexible solar cell module between two laminated sheets formed into monocurved surfaces, or by bonding a flexible solar cell module to the laminated sheet of the present invention and then bending it in one direction to fix it to the substrate. Such a solar cell sheet having an arched monocurved surface can increase the amount of power generated by allowing for a longer period of time to receive sunlight in a more linear manner.

[0096] The solar cell sheet of the present invention may also be three-dimensionally molded. For example, a solar cell sheet of a desired shape can be obtained by three-dimensionally molding a solar cell sheet in which a flexible solar cell module is bonded to the front or back surface of the laminated sheet of the present invention, particularly a solar cell sheet in which a flexible solar cell module is sandwiched and bonded between the laminated sheets of the present invention on both sides, as shown in Figure 18.

[0097] Furthermore, the laminated sheet constituting the solar cell sheet of the present invention has a water vapor transmission coefficient of 0.10 to 0.13 cc·mm / m². 2Since it exhibits a low value of 25 h / atm compared to other materials, if necessary, applying a barrier deposition to the outermost surface allows the laminated sheet to function as a barrier substrate, thereby enabling durability and long-term reliability as a solar cell. Furthermore, by providing a linear groove structure in the laminated sheet of the present invention that constitutes the solar cell sheet of the present invention, the rigidity and strength of the sheet itself can be dramatically increased.

[0098] Next, the flexible solar cell constituting the solar cell sheet of the present invention is preferably a perovskite solar cell. Perovskite solar cells are lightweight, highly flexible, and resistant to strain, making them applicable to various structures. Furthermore, they have advantages such as being able to generate electricity even in low light conditions and having fewer installation constraints, such as the need to consider sunny locations and orientations. On the other hand, their flexibility makes them difficult to install on the walls and roofs of buildings, and there are concerns that they may easily peel off during storms such as typhoons or earthquakes if simply attached to walls with adhesive. Thus, the challenge has been how to stably fix lightweight film-like solar cells, which are inherently not limited by installation location, to the structure to which they are attached over the long term. Therefore, by using the laminated sheet of the present invention as a mounting sheet for a perovskite solar cell film, it can be stably fixed to buildings and other structures over a long period of time.

[0099] Herein, methods for fixing the solar cell sheet of the present invention to a building or the like include, for example, a method of shaping the end of the sheet into a predetermined shape and fixing it to the structure by fitting it together, a method of fixing it with bolts, a method of fixing it with a sealing material, and a method of adhering and fixing it to the object with an adhesive. Furthermore, another method involves using the laminated sheet itself as a structural material such as an exterior wall material or roofing material. Figure 19 shows an example in which the laminated sheet is used as a carport with integrated solar panels.

[0100] Here, the following methods can be used to manufacture the solar cell sheet of the present invention using a film-like perovskite solar cell. 1. A method of shaping the laminated sheet to conform to the shape of the structure to be attached or to a desired shape as needed, and then laminating the perovskite solar cell film to the surface or back surface of the shaped object. 2. A method of laminating a perovskite solar cell film onto the surface or back surface of the laminated sheet, and then shaping it into a predetermined shape. 3. Prepare two laminated sheets, shaped as necessary to conform to the shape of the structure to be attached or to a desired substantially identical shape, and then sandwich the perovskite solar cell film between these shaped sheets from the upper and lower sides. 4. A method of laminating the laminated sheet onto the upper and lower surfaces of a perovskite solar cell film and shaping it into a predetermined form. 5. A method of forming a perovskite solar cell sheet in which a perovskite solar cell film is embedded by sandwiching a perovskite solar cell film between layers of the precursor (pMS) and heat-fusing them, and then shaping the sheet by press molding or the like. Among these methods, when the solar cell sheet of the present invention is manufactured using the method described in 5 above, the solar cells are completely embedded in the laminated sheet of the present invention, thus completely shielding them from moisture and water, and effectively preventing degradation due to moisture. The resulting solar cell molded body can be used for automobile roofing materials, solar carports, balcony parapets, residential roofing materials, and the like. [Examples]

[0101] The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto.

[0102] (raw material adjustment) Using the following polypropylene A1 (melting point 163°C, MFR 4g / 10 min, ethylene content 0.2% by mass, Mw / Mn=9, xylene insoluble content 98.2% by mass, mmmm=98.3, nucleating agent content 0.05% by mass, t1 / 2:2.3 seconds) and the following ethylene-propylene random copolymer B1 (melting point 153°C, MFR 5g / 10 min) or ethylene-propylene random copolymer B2 (melting point 137°C, MFR 7.5g / 10 min), a co-extruded sheet with the following layer structure was obtained using a T-die molding machine, and then a biaxially oriented film was used, which was stretched to a predetermined stretching ratio using a biaxial stretching device. [BAB co-extruded film 1] Two types of three-layer co-extruded film with layer configuration B / A / B (thickness: 50 μm, B / A / B thickness ratio: 5 / 90 / 5, stretching ratio: 5 × 9 times) A: Polypropylene A1 B: Ethylene-propylene random copolymer B1 [BAB co-extruded film 2] Two types of three-layer co-extruded film with layer configuration B / A / B (thickness: 200 μm, B / A / B thickness ratio: 5 / 90 / 5, stretching ratio: 3.5 × 3.5 times) A: Polypropylene A1 B: Ethylene-propylene random copolymer B2 [BAA Co-extruded Film 1] Two types of three-layer co-extruded film with layer configuration B / A / A (thickness: 50 μm, B / A / A thickness ratio: 5 / 90 / 5, stretching ratio: 5 × 9 times) A: Polypropylene A1 B: Ethylene-propylene random copolymer B1 [BAA Co-extruded Film 2] Two types of three-layer co-extruded film with layer configuration B / A / A (thickness: 50 μm, B / A / A thickness ratio: 5 / 90 / 5, stretching ratio: 3.5 × 3.5 times) A: Polypropylene A1 B: Ethylene-propylene random copolymer B2

[0103] (evaluation) <Tensile Test> In accordance with JIS K7161, the tensile modulus was measured in the x and y directions at the positions indicated in (1), (2), and (3) of Figures 5, 6, or 12 under the following conditions. In Example 4, the MD direction of the raw material film was defined as the x direction. • Equipment used: AUTOGRAPH AG-X plus (manufactured by Shimadzu Corporation) • Test specimen: The dumbbell-shaped test specimen (Dumbbell Type 1) shown in Figure 7(a) • Chuck spacing: 100mm • Test speed: 1 mm / min • Stroke: 1mm • Method for calculating elastic modulus: Inclination of two points at strokes of 0.05 mm and 0.25 mm. • Plot sampling start point: 3N

[0104] <Bending Test> <Bending Test> In accordance with JIS K7171, the tensile modulus of elasticity was measured in the TD direction (x direction) and MD direction (y direction) at the positions indicated by (1), (2), and (3) in Figure 5 under the following conditions. In Example 4, the MD direction of the raw material film was defined as the x direction. • Equipment used: AUTOGRAPH AG-X plus (manufactured by Shimadzu Corporation) • Test specimen: 150 × 25 mm rectangular test specimen as shown in Figure 7(b) • Distance between lower supports: 47mm • Test speed: 1.26 mm / min • Stroke: 1mm • Method for calculating elastic modulus: Inclination of two points at strokes of 0.05 mm and 0.25 mm. • Plot sampling start point: 3N

[0105] <Evaluation of surface condition> Test specimens for surface condition evaluation were cut out at the positions indicated by α, β, and γ in Figures 8, 9, or 13 below. The size of the test specimens is shown in Figure 10. The method for determining the positions of α, β, and γ, and the method for collecting each test specimen, are the same as those described above in (Laminated Sheet). In accordance with JIS2001, the arithmetic surface roughness (Ra) was measured under the following conditions. • Equipment used: Surftest SJ-400 (manufactured by Mitutoyo) • Test speed: 1 mm / min • Filter: GAUSS • λc (wave cutoff parameter): 8mm • λs (noise cutoff parameter): 25 μm ·Measurement speed: 1mm / s • Evaluation length: 16.0mm ·Stylus tip radius: 2μm • Stylus tip angle: 60° The specimen size and measurement location are shown in Figure 10.

[0106] (Example 1) As a preparation step, 48 sheets of the BAB co-extruded film 1 were stacked, and BAA film 1 was placed on both surfaces so that layer A was on the surface to obtain a precursor (pMS1). Next, it was inserted into a pressurizing device having a continuous pressure molding mechanism as shown in Figure 1, and pressing, pressure release, and laminated sheet feeding were repeated continuously.

[0107] The temperature settings for the upper and lower molds in the pressurizing device were as shown in Figure 4, the pressure was set to 30 MPa for all four cylinders, the pressing time was 5 seconds, and the sheet feed length at the time of pressure release was 25 mm. In this way, a transparent laminated sheet (MLS) measuring 595 × 1500 mm and 2.5 mm thick was obtained, as shown in Figure 5. From the obtained transparent laminated sheet, dumbbell-shaped test specimens for tensile testing and strip-shaped test specimens for bending testing were cut from the position shown in Figure 5, and the mechanical properties were evaluated using the measurement methods described above for <Tensile Test> and <Bending Test>. The results are shown in Table 1. Furthermore, test specimens for surface condition evaluation were cut from the obtained laminated sheet at the positions shown in Figure 8 below, and the surface condition was evaluated using the measurement method described in <Surface Condition Evaluation> above. The results are shown in Table 2.

[0108] (Example 2) A precursor (pMS2) was obtained in the same manner as in Example 1, except that BAB film 1 and BAA film 1 were made with a width of 700 mm. Next, the bonding was carried out in the same manner as in Example 1, except that the temperature settings of the upper and lower molds in the pressurizing device were as shown in Figure 11. In this way, a transparent laminated sheet measuring 700 x 1500 mm and 2.5 mm thick was obtained, as shown in Figure 12. From the obtained transparent laminated sheet (MLS), dumbbell-shaped test specimens for tensile testing and strip-shaped test specimens for bending testing were cut from the position shown in Figure 12, and the mechanical properties were evaluated using the measurement methods described in <Tensile Test> and <Bending Test> above. The results are shown in Table 1. Furthermore, test specimens for surface condition evaluation were cut from the obtained laminated sheet at the positions shown in Figure 13 below, and the surface condition was evaluated using the measurement method described in <Surface Condition Evaluation> above. The results are shown in Table 2.

[0109] (Example 3) As a preparation step, fifteen BAB co-extruded films 2 were stacked, and AAB films 2 (thickness 200 μm) were placed on both surfaces so that the A layer was on the surface. Otherwise, the procedure was the same as in Example 1 to obtain a precursor (pMS3). Next, the layers were bonded in the same manner as in Example 1, except that the temperature settings of the upper and lower molds in the pressurizing device were set to the conditions shown in Figure 16, to obtain a transparent laminated sheet measuring 700 x 1500 mm and 3 mm thick. From the obtained transparent laminated sheet, dumbbell-shaped test pieces for tensile testing and strip-shaped test pieces for bending testing were cut from the position shown in Figure 12, and the mechanical properties were evaluated using the measurement methods described in <Tensile Test> and <Bending Test> above. The results are shown in Table 1.

[0110] (Example 4) Forty sheets of BAB co-extruded film 1 were stacked, and BAA film 1 was placed on both surface layers with the A layer facing outwards. The film was then cut to a size of 700 x 700 mm. Here, the B / A / B co-extruded films and the B / A co-extruded films were laminated so that the MD direction and TD direction were aligned. The lamination was performed using the chamber of the single-wafer vacuum lamination apparatus shown in Figure 14 and the cooling device shown in Figure 15. The lamination conditions were as follows: Upper hot plate temperature 150℃ Lower hot plate temperature 145℃ Vacuuming time: 120 seconds Pressurization time: 300 seconds Hold time 300 seconds Hot plate pressing time: 300 seconds Hot plate pressing pressure: 0.3 MPa Configuration during lamination pressing From top to bottom: Polytetrafluoroethylene sheet / SUS plate / Laminated sheet / Material on top of SUS plate / Polytetrafluoroethylene sheet From the obtained transparent laminated sheet, dumbbell-shaped test pieces for tensile testing and strip-shaped test pieces for bending testing were cut from the position shown in Figure 6, and the mechanical properties were evaluated using the measurement methods described above for <Tensile Test> and <Bending Test>. Here, the MD direction of each raw material film was set as the x-direction and the TD direction as the y-direction for various evaluations. The results are shown in Table 1. Furthermore, test specimens for surface condition evaluation were cut from the obtained laminated sheet at the positions shown in Figure 9 below, and the surface condition was evaluated using the measurement method described in <Surface Condition Evaluation> above. The results are shown in Table 2.

[0111] (Comparative Example 1) Using the same configuration as in Example 1, a precursor (pMS1) cut to 400 x 400 mm was attempted to be bonded using a roll forming machine (dielectric heating jacket roller manufactured by Tokuden Co., Ltd., model "JR-D0-W", roll diameter 200 mmφ x 2, roll surface length 400 mm). Heating roll temperature: 165℃ Heated roll forming take-up speed: 0.8 m / min Preheating roll: 130~155℃ However, the resulting laminated sheets had areas where air was trapped and failed to bond evenly distributed throughout, and also exhibited warping and undulation. Furthermore, when the take-up speed of the heated roll molding was reduced and bonding was attempted again, the radiant heat from the heated roll caused wrinkles on the surface, and a smooth laminated sheet could not be obtained.

[0112] [Table 1]

[0113] [Table 2] [Explanation of Symbols]

[0114] 2: Mold 4: Heating plate / cooling plate module 6: Hydraulic Cylinder 8: Lifting Unit 10: Lifting guide 12: Drawer Unit 20:Product direction 60: Laminated sheet precursor (pMS) 62: Multilayer biaxially oriented film (X) 64a: Multilayer biaxially oriented film (X) 64b: Multilayer biaxially oriented film (X) 100: Continuous pressurization device 200: Single wafer vacuum laminating equipment 201: Main unit of the device 202: Chamber 203: Hydraulic cylinder 204: Hot plate 205: Hot plate 300: Cooling device 301: Cooling metal plate 302: Cooling metal plate d: diaphragm s: Stainless steel plate sl: Silicone sheet pt: Polytetrafluoroethylene sheet MLS, 70: Laminated Sheet PV: Flexible solar cell module 400: Solar sheet 500: Solar-powered carport

Claims

1. A laminated sheet having a structure in which a layer made of biaxially oriented polypropylene film and a b layer made of olefin resin with a melting point of 110 to 160°C are alternately laminated, The melting point of the olefin resin constituting the b layer is lower than the melting point of the biaxially oriented polypropylene film constituting the a layer. The laminated sheet is a BAB-type film in which a biaxially oriented polypropylene film (A) constituting the a layer and a biaxially oriented olefin resin film (B) constituting the b layer are laminated on both surfaces thereof, and it is made by laminating two or more BAB-type films in which the thickness ratio of B / A / B in the BAB-type film is B / A / B = 2 to 20 / 96 to 60 / 2 to 20. A laminated sheet characterized in that, when the direction of one side of the laminated sheet is defined as the x-direction and the direction perpendicular thereto as the y-direction, the tensile modulus of elasticity in the x-direction and the y-direction at three positions including the center position in the y-direction and two positions passing through this center position and located 200 mm away from the center position in the y-direction are all within the range of 2000 to 5000 MPa.

2. In a plan view of the laminated sheet, when a 595 mm x 595 mm square is drawn such that the diagonal intersection is at the center in the TD direction, let the diagonal intersection be α, the midpoint between the diagonal intersection and the corner be β, and the corner be γ. When the surface roughness at positions α, β, and γ are denoted as Ra(α), Ra(β), and Ra(γ), The laminated sheet according to claim 1, wherein Ra(α), Ra(β), and Ra(γ) satisfy the following formulas (1) to (2). Ra(α)-Ra(β)<0.3 (1) Ra(α)-Ra(γ)<0.3 (2) The above-mentioned Ra(α), Ra(β), and Ra(γ) are the average values ​​(average roughness) obtained when the surface roughness of each test piece was measured at two locations on each test piece, which was cut out in the shape of a strip with the x-direction as its longer side from the positions of α, β, and γ, respectively.

3. The laminated sheet is formed by stacking and heat-sealing multiple layers of multilayer biaxially oriented films (X), each of which a biaxially oriented polypropylene film (A) constituting the a layer and a biaxially oriented olefin resin film (B) constituting the b layer are laminated on at least one surface thereof, and The laminated sheet according to claim 1 or 2, wherein the multilayer biaxially oriented film (X) has a stretching ratio of 2.8 to 8 times in the MD direction and a stretching ratio of 2.8 to 12 times in the TD direction.

4. The multilayer biaxially oriented film (X) is a BAB type film and has a thickness of 30 to 80 μm. The laminated sheet according to claim 3, wherein the laminated sheet is obtained by laminating 30 to 60 BAB type films and laminating BA type films or BAA type films on both surfaces such that A is on the surface.

5. The multilayer biaxially oriented film (X) is the BAB type film, and its thickness is 100 to 400 μm. The laminated sheet according to claim 4, wherein the laminated sheet is obtained by laminating 2 to 20 BAB type films and laminating BA type films or BAA type films on both surfaces such that A is on the surface.

6. A molded article of a laminated sheet according to claim 1 or 2.

7. A method for manufacturing the laminated sheet described in Claim 1, A preparatory step of stacking two or more of the aforementioned BAB-type films to form a laminated sheet precursor (pMS), A method for manufacturing a laminated sheet, comprising a pressing step of heating and pressing the laminated sheet precursor (pMS) on its surface.

8. A method for manufacturing the laminated sheet described in Claim 1, A preparatory step of stacking two or more of the aforementioned BAB-type films to form a laminated sheet precursor (pMS), The process includes a continuous press step in which the laminated sheet precursor (pMS) is continuously heated and pressed using a continuous press device, and then cooled. A method for manufacturing a laminated sheet, characterized in that the continuous pressing device has multiple heating zones and cooling zones, and the laminated sheet precursor (pMS) is heated and pressed in the heating zone using upper and lower planar molds, and then continuously pressed in the cooling zone using upper and lower planar molds.

9. The laminated sheet precursor (pMS) is inserted between the upper and lower planar molds that constitute the heating zone in the continuous pressurizing device. A method for manufacturing a laminated sheet according to claim 8, comprising: pressing at a temperature of 110 to 170°C and a pressure of 1 to 40 MPa; then, after releasing the press, feeding the sheet a predetermined length in the direction of travel (MD direction); heating and pressing again; and repeating this process to continuously transfer the sheet from the heating zone to the cooling zone; and subsequently, pressing in the cooling zone at a temperature of 25 to 125°C and a pressure of 1 to 40 MPa; then, after releasing the press, feeding the sheet in a predetermined direction of travel to continuously remove the heat-fused laminated sheet.

10. The heating zone is divided into 2 to 10 stages in the MD direction, and is composed of a mold with a flat contact surface that sandwiches the sheet from above and below, The method for manufacturing a laminated sheet according to claim 9, wherein the cooling zone is divided into one or two to five stages in the MD direction and has a structure composed of a mold with a flat contact surface that sandwiches the sheet from above and below.

11. A method for manufacturing a laminated sheet according to claim 9 or claim 10, wherein the temperature conditions of the heating zones, which are divided into 2 to 10 stages in the MD direction, are such that the temperature of the first heating zone closest to the sheet entrance is 110 to 160°C, the temperature of the second heating zone following it is 10 to 40°C above the set temperature of the first heating zone, and the maximum temperature of the heating zones is 170°C.

12. The method for manufacturing a laminated sheet according to claim 7 or 8, wherein the BAB-type film has a stretching ratio of 2.8 to 8 times in the MD direction and a stretching ratio of 2.5 to 12 times in the TD direction.

13. The method for manufacturing a laminated sheet according to claim 12, wherein the thickness of the biaxially oriented polypropylene film (A) in the BAB type film is 30 to 80 μm, and the laminated sheet precursor (pMS) is obtained by laminating 30 to 60 BAB type films, with a BA type film or a BAA type film laminated on both surfaces such that A is on the surface.

14. A method for manufacturing a laminated sheet according to claim 7, comprising using a single-wafer vacuum laminating apparatus having planar metal plates on the upper and lower sides of a chamber, placing the laminated sheet precursor (pMS) on the lower metal plate in the chamber, heating and pressing while maintaining a vacuum of 170 Pa or less in the chamber, and after releasing the press, sandwiching the laminated sheet with a cooling metal plate.

15. The method for manufacturing a laminated sheet according to claim 14, wherein the heating press is performed under the conditions that the metal plate temperature is 140 to 160°C and the cylinder pressure is 0.1 to 1 MPa.

16. A solar cell sheet comprising a flexible solar cell module bonded to a laminated sheet as described in claim 1 or 2.

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