Method for manufacturing a laminate and laminate

Abstract

This invention provides a method for manufacturing a laminate and a laminate that can produce a hard laminate at a low processing temperature by thermocompression bonding at a temperature lower than the softening temperature, thereby shortening the process time and reducing manufacturing costs. [Solution] The method includes the steps of forming a first superimposed body 40a by stacking bonding sheets 31, 33 and sheets to be bonded 32, 34, which mainly consist of a PP hot melt material, and hot pressing the first superimposed body 40a at a temperature of 50°C to 125°C and a pressure of 1 MPa to 5 MPa, wherein the PP hot melt material contains polypropylene as its main component, and the softening point of the PP hot melt material is 135°C or higher.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a laminate using a PP hot melt material and to the laminate.

Background Art

[0002] Conventionally, a method is known in which a prepreg sheet impregnated with a polypropylene (PP)-based hot melt material is pressure-bonded by hot pressing to produce a composite laminate (see Patent Document 1). In the method described in Patent Document 1, a plurality of prepreg sheets formed of non-woven fabric impregnated with polypropylene and non-woven fabric are stacked, and hot pressed at a temperature of 100°C or higher and 150°C or lower and a pressure of 1.5 MPa or higher and 2.5 MPa or lower to form a composite laminate.

[0003] On the other hand, a method for manufacturing a composite using a polypropylene-based hot melt film is known (see Patent Document 2). In the method described in Patent Document 2, a joined body is arranged so as to contact a hot melt film arranged so as to contact a coated metal blank having an organic resin layer, and heating is performed using equipment capable of raising the temperature to the softening temperature or melting point or higher, thereby welding the hot melt film to the organic resin layer and the joined body.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] As described above, in principle, the fluidity of a hot melt adhesive increases and bonding to the target film or prepreg becomes possible only after it has been softened at a temperature higher than its softening point. This is the conventional technical common sense in this field. Therefore, when embedding functional components such as electronic circuits, hot melt adhesives with high softening points and hardness at room temperature cannot be used. Also, hot melt adhesives that can bond at low temperatures are soft, and their applications are limited when dimensional accuracy of the molded product is required.

[0006] This invention has been made in view of these circumstances, and aims to provide a method for manufacturing a laminate and a laminate that can produce a hard laminate at a low processing temperature by thermocompression bonding at a temperature lower than the softening temperature, thereby shortening the process time and reducing manufacturing costs by lowering the processing temperature. [Means for solving the problem]

[0007] (1) In order to achieve the above objective, the present invention provides a method for manufacturing a laminate, comprising the steps of: stacking a bonding sheet and a sheet to be bonded, mainly having a PP hot melt material, to form a first laminate; and hot pressing the first laminate at a temperature of 50°C to 125°C and a pressure of 1 MPa to 5 MPa, wherein the PP hot melt material contains polypropylene as its main component, and the softening point of the PP hot melt material is 135°C or higher.

[0008] (2) Furthermore, in the method for manufacturing the laminate described in (1) above, the step of hot pressing is characterized in that the first laminate is hot pressed at a temperature of 55°C to 100°C and a pressure of 1.5 MPa to 2.5 MPa.

[0009] (3) Furthermore, in the method for manufacturing the laminate described in (1) above, the PP hot melt material is characterized by having a tensile strength of 2.0 MPa or less at room temperature, an elongation of 300% or less at room temperature, and a melt viscosity of 6000 mPa·s or more at 160°C.

[0010] (4) Furthermore, in the method for manufacturing a laminate described in any of (1) to (3) above, the bonding sheet is characterized in that it is a composite sheet having a sheet-like textile and the PP hot melt material that has permeated into and fixed within the mesh of the textile.

[0011] (5) Furthermore, in the method for manufacturing the laminate described in (4) above, the sheet to be bonded is also characterized in that it is the composite sheet.

[0012] (6) Furthermore, the method for manufacturing the laminate described in (5) above is characterized in that a functional member is sandwiched between the bonding sheet and the sheet to be bonded to form the first superimposed body.

[0013] (7) In addition, in the method for manufacturing a laminate described in any of (1) to (6) above, the sheet to be bonded is characterized in that it is a polypropylene film.

[0014] (8) In addition, in the method for manufacturing a laminate described in any of (1) to (6) above, the sheet to be bonded is characterized in that it is a sheet-like textile.

[0015] (9) The method for manufacturing a laminate described in any of (1) to (8) above is further characterized by including a step of heating the first laminate, which has been cooled after being heat-pressed, at a temperature of 140°C to 160°C.

[0016] (10) In addition, in the method for manufacturing the laminate described in (9) above, the heating step is characterized in that the first laminate is heated by injecting resin into the bonding sheet side of the first laminate.

[0017] (11) In addition, in the method for manufacturing the laminate described in (9) above, the heating step is characterized by hot pressing the first laminate at a pressure of 1 MPa to 5 MPa.

[0018] (12) Further, in the method for manufacturing a laminate according to any one of (1) to (8) above, a sheet-like heating material is embedded in the bonding sheet.

[0019] (13) Further, in the method for manufacturing a laminate according to (12) above, the heating material is exposed at least at the edges of the bonding sheet in at least two directions.

[0020] (14) Further, the laminate of the present invention includes a first layer mainly having a PP hot melt material and a second layer joined to the first layer, the PP hot melt material contains polypropylene as a main component, and the softening point of the PP hot melt material is 135°C or higher.

[0021] (15) Further, in the laminate according to (14) above, the PP hot melt material has a tensile strength at room temperature of 2.0 MPa or less, an elongation rate at room temperature of 300% or less, and a melt viscosity at 160°C of 6000 mPa·s or more.

[0022] (16) Further, in the laminate according to (14) or (15) above, the first layer is a composite layer having a sheet-like textile and the PP hot melt material infiltrated and fixed within the mesh of the textile.

[0023] (17) Further, in the laminate according to any one of (14) to (16) above, the second layer is formed of polypropylene.

[0024] (18) Further, in the laminate according to (14) above, the first layer has an embedded sheet-like heating material.

[0025] (19) Further, in the laminate according to (18) above, the heating material is exposed at least at the edges of the first layer in at least two directions.

Brief Description of the Drawings

[0026] [Figure 1] It is a cross-sectional view showing the laminate of the first embodiment. [Figure 2] (a) to (c) are cross-sectional views showing the steps of producing prepregs, respectively. [Figure 3] It is a perspective view showing the step of thermocompression bonding by laminating prepregs. <000,0106> [Figure 4] They are cross-sectional views showing the steps of molding and trimming, respectively. [Figure 5] It is a perspective view showing the step of thermocompression bonding a prepreg and a textile. [Figure 6] (a) and (b) are cross-sectional views showing laminates in which a heating element and an element are embedded, respectively. [Figure 7] It is a cross-sectional view showing the laminate of the second embodiment. [Figure 8] (a) to (d) are cross-sectional views showing the steps of forming and trimming a molded body, respectively. [Figure 9] (a) and (b) are cross-sectional views showing the step of forming a base resin layer by injection molding. [Figure 10] It is a cross-sectional view showing the step of joining a decorative layer. [Figure 11] (a) and (b) are a perspective view and a cross-sectional view showing the bonding sheet of the sixth embodiment, respectively. [Figure 12] It is a cross-sectional view showing the laminate of the sixth embodiment. [Mode for Carrying Out the Invention]

[0027] [Basic Configuration] (Configuration of the Laminate) The laminate comprises a first layer mainly consisting of PP hot melt material and a second layer bonded to the first layer. The PP hot melt material contains polypropylene as its main component, and its softening point is 135°C or higher. "Main component" refers to a content of 50% by mass or more. Examples of additives include elastomers and tackifiers. The first layer originates from the bonding sheet in the manufacturing process, and the second layer originates from the sheet to be bonded in the manufacturing process.

[0028] Elastomers are polymeric materials with elasticity similar to rubber. Examples include thermosetting elastomers such as silicone rubber and thermoplastic elastomers such as polyvinyl chloride. Specifically, olefin-based (polyolefin-based) elastomers, such as ethylene propylene rubber, are used. Tackifiers are tackifying resins, and petroleum-based tackifiers are used, for example.

[0029] As the PP hot melt material, one with a softening point of 135°C or higher is used, preferably one with a softening point of 145°C or higher. The PP hot melt material preferably has a tensile strength of 2.0 MPa or less at room temperature, an elongation of 300% or less at room temperature, and a melt viscosity of 6000 mPa·s or higher at 160°C. By using a PP hot melt material that is hard at room temperature but shows a tendency to soften rapidly when the temperature is raised to around 100°C, laminates can be produced at low processing temperatures.

[0030] The first layer may be a composite layer having a sheet-like textile and a PP hot-melt material that has permeated and fixed into the mesh of the textile. The second layer may be made of polypropylene.

[0031] (Method of manufacturing a laminate) A method for manufacturing the laminate configured as described above will be explained. First, a bonding sheet and a sheet to be bonded, mainly containing PP hot melt material, are stacked to form a first laminate.

[0032] Next, the first superimposed material is hot-pressed at a temperature of 55°C to 100°C and a pressure of 1.5 MPa to 2.5 MPa. This allows for the creation of a laminate formed at a low processing temperature, which shortens the process time and reduces manufacturing costs. Preferably, the temperature for hot pressing is 85°C or higher.

[0033] The sheet to be bonded may be a sheet-like textile. This allows for the formation of a surface layer by layering a composite layer or PP film impregnated with PVB onto the textile. A decorative layer can also be added on top of the surface layer. Details of the bonding sheet and the sheet to be bonded will be described later with specific examples.

[0034] [First Embodiment (Lamination of Prepreg)] The bonding sheet may be a composite sheet comprising textile and PP hot melt material. The textile is in sheet form, and the PP hot melt material is impregnated and fixed within the mesh of the textile. This suppresses the flow of the PP hot melt material during processing, making it possible to create a laminate with excellent shape stability. Alternatively, the sheet to be bonded may also be a composite sheet. In that case, a laminate can be created by bonding two composite sheets, and a functional member can be embedded between the sheets.

[0035] (Structure of the laminate) Figure 1 is a cross-sectional view showing the laminate 100. The configuration shown in Figure 1 is an example, and the laminate 100 is composed of composite layers 111 to 114. The composite layers 111 to 114 are laminated together, and each of the composite layers 111 to 114 is formed of a textile and a PP hot-melt material that has permeated and fixed into the mesh of the textile.

[0036] In composite layers 111-114, the PP hot melt material is continuously present across layers and permeates into the mesh of the textile. Due to the anchoring effect of the permeated PP hot melt material, each of the composite layers 111-114 is firmly bonded to the adjacent layer. In this way, a firmly integrated plate-like member is formed. The PP hot melt material may also contain an elastomer and a tackifier.

[0037] PP hot melt material has a softening point of 135°C or higher. Preferably, the softening point of the PP hot melt material is 145°C or higher. However, the PP hot melt material used is one that can be bonded to the sheet to be bonded by hot pressing at a temperature of 55°C to 100°C.

[0038] The textiles contained in each of the composite layers 111 to 114 are preferably all nonwoven fabrics or alternating layers of nonwoven and woven fabrics. The nonwoven fabric is preferably a spunbond nonwoven fabric, and particularly preferably a spunbond nonwoven fabric containing polyester. The nonwoven fabric may also be a papermaking nonwoven fabric or felt containing polyester. A polyethylene-reinforced fiber woven fabric can also be used as the woven fabric.

[0039] When using polyester nonwoven fabric, the tsubo (square meter) is 30 g / m². 2 More than 250g / m 2 The following is preferable. This makes it easier for the softened PP hot melt material to impregnate the material. Using a textile containing polyester improves the shape stability of the laminate and maintains dimensional accuracy of the shape.

[0040] In the laminate 100, the composite layers 111 to 114 have a four-layer structure, but other numbers of layers are also possible. Having four or more layers improves the strength of the laminate 100 and stabilizes its shape. On the other hand, having fewer than four layers makes molding easier.

[0041] (Method of manufacturing a laminate) A method for manufacturing the laminate 100 configured as described above will now be explained. The laminate 100 is manufactured through the processes of prepreg preparation, thermocompression bonding, preform molding, and trimming. Figures 2(a) to (c) are cross-sectional views showing the prepreg preparation process, respectively.

[0042] First, a prepreg is prepared. For example, as shown in Figure 2(a), a sheet of nonwoven fabric 10 is placed with its surface horizontal, and a PP hot melt material 20, which has been heated to a temperature above its softening point and softened, is applied on top of it, allowing it to permeate and solidify to produce a prepreg 30. It is preferable to use a nonwoven fabric 10 with a thickness of 50 μm or more and 500 μm or less.

[0043] For coating, a device called a melter can be used as a hot melt coating machine. The example device shown in Figure 2(a) is a sheet-fed coating machine, in which the nonwoven fabric 10 is fixed and the PP hot melt material 20 is applied to the nonwoven fabric 10 by moving the spray-type nozzle M1 over the entire nonwoven fabric 10 to produce a prepreg 30. Note that coating does not necessarily have to be done by spraying; it may also be done by extrusion coating such as die coating.

[0044] The example apparatus shown in Figure 2(b) is a roll-to-roll continuous impregnation apparatus. By fixing the spray nozzle section M2 and moving the nonwoven fabric 10 from roll R1 to roll R2, the PP hot melt material 20 can be applied to the entire nonwoven fabric 10 to produce a prepreg 30. In such a coating machine, it is preferable to move either the coating machine side or the nonwoven fabric side at a constant speed relative to the other during coating.

[0045] The apparatus shown in Figure 2(c) is also a continuous impregnation apparatus using rolls. A discharge nozzle section M3 is fixed, and PP hot melt material 20 is supplied to the position between rolls R3 and R4. The nonwoven fabric 10, which is fed out sandwiched between rolls R3 and R4, is impregnated with the PP hot melt material 20. The production efficiency of prepreg 30 can be improved by using such a continuous impregnation apparatus.

[0046] As described above, the PP hot melt material 20 may be impregnated into the textile by application alone, but it may also be possible to impregnate the textile with a heat press at 130°C or higher after applying the hot melt material, or to place a sheet of hot melt material on the textile and impregnate it with a heat press at 130°C or higher.

[0047] Alternatively, heated and softened PP hot melt material may be collected in a container, and sheet-like textile material may be immersed in the container (so-called "dip immersion"). The PP hot melt material that has permeated the textile in this way is then cooled and hardened to form a prepreg. In this case, it is preferable to move the textile continuously at a constant speed using a rotating roller or the like to pass it through the PP hot melt material. In addition to the above, a method of permeating the textile with PP hot melt material by heat pressing can also be employed.

[0048] The sheet-like prepreg obtained in this manner is preferably 100 μm to 1500 μm thick, and more preferably 100 μm to 500 μm thick.

[0049] The obtained sheet-like prepregs 30 are stacked and arranged according to a predetermined design to form a superimposed layer (first superimposed layer). The arranged superimposed layer is then heated and pressed to heat-seal it. Figure 3 is a perspective view showing the process of stacking and heat-sealing the prepregs. In the example shown in Figure 3, a superimposed layer 40a made of four stacked prepregs 31-34 is heated and pressed from above and below. As a result, a sheet-like laminate is formed.

[0050] For heat bonding, it is preferable to use a hydraulic heat press or a multi-stage press to apply heat at a temperature between 55°C and 100°C and a pressure between 1.5 MPa and 2.5 MPa. Although the softening point of PP hot melt material is 135°C or higher, the temperature of the mold during heat pressing is lower, between 55°C and 100°C. This allows the PP hot melt material to bond to the target prepreg, firmly integrating the components.

[0051] In this way, when the prepregs are heat-pressed together, the PP hot-melt material that has permeated into the mesh becomes continuously integrated and firmly fixed to the mesh by the anchoring effect. As a result, the laminate 100 is formed as a laminated sheet in which multiple nonwoven fabrics are firmly bonded together by the PP hot-melt material that has permeated throughout.

[0052] The laminated body 100 can be stabilized in shape by natural cooling after lamination by thermocompression bonding. Therefore, it is possible to mass-produce them simultaneously using a multi-stage press. A multi-stage press is a hot press machine that has a heating plate in the middle in addition to the upper and lower heating plates, and has multiple openings to serve as stages for sandwiching the material. Multiple laminated bodies can be formed simultaneously by sandwiching the material between multiple stages and applying pressure with a press while heating.

[0053] The laminate 100 has a composite layer structure in which PP hot-melt material is infiltrated and fixed into the textile, thus possessing high strength. This makes it suitable for use in lightweight yet high-strength components such as automobile bodies.

[0054] The laminate 100 sheets obtained in the above process are molded and trimmed. Figures 4(a) to 4(d) are cross-sectional views showing the molding and trimming process. First, the laminate 41 is softened by heating. Then, as shown in Figure 4(a), the laminate 41 is placed between the male mold D1 and the female mold D2.

[0055] Next, as shown in Figure 4(b), the male mold D1 and the female mold D2 are clamped together. As a result, the laminate 41 is formed. After clamping, as shown in Figure 4(c), the male mold D1 and the female mold D2 are opened and the resulting molded body 42 is demolded. Then, as shown in Figure 4(d), unnecessary parts are removed by trimming to obtain the molded body 43. Even after such molding processes, the change in length from the laminate 41 to the molded body 43 is within 1%, indicating that the laminate 100 has excellent shape stability. The resulting laminate 100 can be further machined as appropriate depending on the application.

[0056] (Manufacturing method involving inserting textiles) In the above embodiment, only prepregs are stacked and heat-pressed, but prepregs and textiles may be stacked alternately and then heat-pressed. Figure 5 is a perspective view showing the process of heat-pressing prepregs and textiles. The textiles stacked alternately with the prepregs are woven or nonwoven fabrics. In the example shown in Figure 5, a laminated body 40b (second laminated body) is formed by alternately stacking two prepregs 35-36 and two textiles 51-52, and this laminated body 40b is heat-pressed. As a result, a sheet-like laminate is formed. This heat-pressing can also be performed using the same equipment and temperature conditions as in the first embodiment.

[0057] In this case as well, the prepreg and textile are heat-pressed together at a temperature of 55°C to 100°C, causing the PP hot-melt material within the prepreg to adhere to the prepreg. As a result, the PP hot-melt material, which has spread continuously through penetration, joins the prepreg and textile, creating a laminated sheet of laminate 100.

[0058] (Embedded functional component type) A first superimposed structure can also be formed by sandwiching a functional component between a bonding sheet and a sheet to be bonded. This allows for the manufacture of laminates containing, for example, heaters, wire harnesses, or electronic circuits. A functional component refers to a component that performs a function according to a specific purpose or application, such as a component that performs some function through electric current. Specifically, this includes conductive components such as conductors, heater wires, heating materials, and electronic circuits.

[0059] A heat-generating material 231 can be embedded in the main body layer of the laminate 100 described above as a functional component. Figures 6(a) and 6(b) are cross-sectional views showing laminates 200 and 300, respectively, in which the heat-generating material 231 and element 331 are embedded in the main body layer. Laminate 200 is basically constructed in the same way as laminate 100, but has the embedded heat-generating material 231 and related features.

[0060] In the laminate 200, a heat-generating material 231 is provided between the composite layer 211 and the composite layer 212. In this way, a laminate 200 can be constructed that is firmly integrated with PP hot melt material and has added functionality due to the heat-generating material 231 provided inside. In the example shown in Figure 6(a), the heat-generating material 231 is provided between the composite layer 211 and the composite layer 212, for example, by heat-generating fibers formed in a sheet shape.

[0061] Heat-generating fibers can be formed by mixing organic fibers and carbon fibers. Organic fibers are, for example, cellulose or a mixture of cellulose and polyester. Carbon fibers with a typical length of 3 mm to 6 mm can be used. The carbon fibers may be present in an amount of 10% to 20% by weight relative to the organic fibers. For example, a mixture of cut carbon fibers into papermaking or a mixture of cut PET into papermaking can be used. Alternatively, natural cellulose fibers may be mixed with carbon fibers and then made into paper. Heat-generating fibers may also be composed solely of carbon fibers. Furthermore, heat-generating fibers may be woven fabrics as well as nonwoven fabrics. For example, a heat-generating fiber may be a woven fabric made of heater wires, and the heater wires may be conductive wires themselves, or they may be composite wires consisting of an insulated wire and one or more conductive wires wound around the insulated wire.

[0062] Since the laminate 200 is formed by heat-pressing with the heat-generating material 231 sandwiched in between, the composite layer 212 pressed by the heat-generating material 231 has depressions corresponding to the cross-sectional shape of the heat-generating material. Depending on the heat-pressing temperature, the PP hot melt material may permeate the heat-generating fibers of the heat-generating material 231. Because the composite layers 211 and 212 deform flexibly in this way, the surface on the composite layer 211 can be made smooth. Since it is embedded between the composite layers, it is not a problem if the heat-generating material 231 is exposed as a conductive material without an insulating coating.

[0063] In the above example, the heat-generating material 231 is provided between the nonwoven fabrics in the composite layer, but if the nonwoven fabrics and woven fabrics are arranged alternately, it may be provided between the nonwoven fabrics and woven fabrics. In other words, the heat-generating material 231 only needs to be embedded inside the multiple layer structures that make up the laminate 200, and in that case, it may be embedded between any of the layers.

[0064] On the other hand, the laminate 300 is basically constructed in the same way as the laminate 200, but the element 331 embedded in the laminate 300 and its related characteristics are different. In the example shown in Figure 6(b), a flat cross-section element 331 is provided between the composite layer 311 and the composite layer 312. During the manufacturing process, the composite layer 312, which was pressed by the element 331, has a flat recess corresponding to the cross-sectional shape of the element.

[0065] The manufacturing process for laminates 200 and 300 is the same as that for laminate 100. The only difference is that the heat-generating material 231 or element 331 is placed between the prepreg and textile during the arrangement of the materials.

[0066] [Second Embodiment (Applications of Laminated Prepregs)] (Structure of the laminate) The laminate of the prepreg used in the above embodiment may be provided with a backer sheet containing a composite layer in which PVB is impregnated into a nonwoven fabric. Furthermore, as the base resin, ABS resin, PP, PC, PMMA, or other resins may be injection molded onto the backer sheet side. In this way, it can be applied to various uses as a lightweight intermediate processing material with a low processing temperature.

[0067] The backer sheet functions as an adhesive layer that bonds the laminate and the base resin, but depending on the conditions, the base resin may be directly injection molded onto the laminate without providing an adhesive layer. The adhesive layer may be a composite layer as described above, but it may also be composed solely of nonwoven fabric.

[0068] Figure 7 is a cross-sectional view showing the laminate 400. In the example shown in Figure 7, the laminate 400 has a laminate 400 made of composite layers using PP hot melt material, a backer sheet 420, and a base resin layer 430. The laminate 400 is composed of composite layers 411 to 414 in which PP hot melt material is impregnated into the textile. The backer sheet 420 has PVB composite layers 421, 423 and a PVB film layer 422. The PVB composite layers 421 and 423 have a sheet-like textile and PVB (polyvinyl butyral) that is impregnated and fixed into the mesh of the textile. PVB has the property of melting instantly at temperatures above its melting temperature and solidifying instantly at temperatures below its solidification temperature, making it very effective as an adhesive.

[0069] The textile for PVB impregnation may be a woven fabric, but a nonwoven fabric is preferred. Nonwoven fabrics are readily available and allow for the low-cost production of the laminate 100. Spunbond nonwoven fabrics are preferred, and spunbond nonwoven fabrics containing polyester are particularly preferred. The nonwoven fabric may also be a papermaking nonwoven fabric or felt containing polyester. Polyethylene-reinforced fiber woven fabric can also be used as the woven fabric.

[0070] The PVB film layer 422 is derived from the PVB film and is a thin layer composed of PVB. The PVB exists continuously across layers, and the PVB constituting the PVB film layer 422 is continuous with the PVB that has permeated into the mesh of the textile. Due to the adhesive strength of the PVB and the anchoring effect of the permeated PVB, the PVB composite layers 421 and 423 are firmly bonded to the adjacent layers. When all the PVB in the PVB film has permeated and adjacent textiles are in contact, the PVB film layer 422 is absent and the PVB composite layers 421 and 423 are in contact with each other. The laminate 400 can be formed by injection molding a base resin layer 430 onto a 3D molded product made from a laminate 400 and backer sheet 420 using a composite layer made of PP hot melt material. Examples of thermoplastic resins used in injection molding include ABS resin, PP, PC, and PMMA.

[0071] (Method of manufacturing a laminate) A method for manufacturing the laminate 400 configured as described above will now be explained. A backer sheet is formed on the prepreg layer sheet obtained in the process of the above embodiment, and then molded and trimmed. Figures 8(a) to 8(d) are cross-sectional views showing the process of forming and trimming the backer sheet, respectively. First, as shown in Figure 8(a), a textile 451, a PVB film 452, and a textile 453 are placed in order from the surface of the prepreg laminate 441 between the male mold D1 and the female mold D2. Then, they are heated and pressurized at a temperature of 120°C to 130°C. At this time, the PVB softens and permeates into the mesh of the textiles 451 and 453.

[0072] Next, as shown in Figure 8(b), the male mold D1 and the female mold D2 are clamped together. As a result, the laminate 441 based on the prepreg, the textiles 451 and 453, and the PVB film 452 are formed. After clamping, as shown in Figure 8(c), the male mold D1 and the female mold D2 are opened and the resulting molded body 442 is demolded. Then, as shown in Figure 8(d), the unnecessary parts are removed by trimming to obtain the preformed molded body 443.

[0073] (injection molding) A base resin layer can be formed on the preformed molded body 443 (intermediate member) formed as described above by injection molding a thermoplastic resin. Figures 9(a) and (b) are cross-sectional views showing the process of forming the base resin layer 430 by injection molding. As the thermoplastic resin, ABS resin, PP, PC, PMMA, etc., can be used at their respective melting temperatures. For example, when using ABS resin, the ABS resin is melted before use.

[0074] As shown in Figure 9(a), the preformed molded body 443 is placed in the female mold M12 for injection molding with the prepreg layer side facing outwards, and then the female mold M12 is moved toward the male mold M13 for injection molding. At the same time, the injection hole M15 of the injection machine is pressed against the injection molding hole M16 of the male mold M13, and the injection screw M11 is rotated clockwise to inject the raw material P1 of the base resin layer in the tank T1 into the space defined by the preformed molded body 443 and the male mold M13 for injection molding. In other words, thermoplastic resin is injection molded onto the main surface on the back side of the intermediate member.

[0075] The molten thermoplastic resin, which is the raw material P1 for the base resin layer, is heated and melted in the injection molding machine M10 and injected into the female mold M12 into which the preformed molded body 443 is mounted, and permeates and solidifies into the gaps between each fiber of the textile layer. At this time, the thermoplastic resin permeates into the gaps between each fiber of the textile, and the shrinkage during the cooling and solidification of the raw material P1 strengthens the bond between the preformed molded body 443 and the base resin layer.

[0076] Then, as shown in Figure 9(b), after the injection-molded base resin layer has cooled and solidified, the injection machine and the male mold M13 for injection molding are separated from the female mold M12, and the laminate 400, comprising the prepreg layer 410, backer sheet 420, and base resin layer 430, is removed. The obtained laminate 400 is then machined as appropriate according to the application. The obtained laminate 400 can be applied to various products using thermoplastic resin as the surface material.

[0077] (Decorative layer) A decorative layer can also be added to the laminate. In this case, a laminate containing a composite layer impregnated with PP hot melt material can be used, and a decorative layer made of wood, suede, or metal mesh can be bonded to the laminate. This allows the use of a prepreg layer with excellent shape stability in the laminate to which the decorative layer is bonded.

[0078] Figure 10 is a cross-sectional view showing the bonding process of the decorative layer. In the example shown in Figure 10, the decorative layer 470 is placed on top of the preformed molded body 443 (intermediate member), which has a prepreg layer and a PVB composite layer bonded together, and then heat-pressed onto it. This allows the decorative layer 470 to be bonded to the prepreg layer.

[0079] [Third Embodiment (Bonding of Prepreg and PP Film)] When a prepreg is used as the bonding sheet, the sheet to be bonded may be a polypropylene film. This makes it possible to create a laminate in which polypropylene is bonded to a bonding sheet that mainly contains a PP hot melt material.

[0080] In this case, the laminate consists of a polypropylene composite layer and a PP film. The polypropylene composite layer may be a laminate of multiple prepreg-based composite layers. In this case, the PP hot melt material is present continuously across the layers, and each layer is firmly bonded to the adjacent layer. The composite layer is formed of textile and PP hot melt material that has permeated and fixed into the mesh of the textile.

[0081] The textiles contained in the PP composite layer are preferably all nonwoven fabrics or a combination of nonwoven and woven fabrics layered alternately. The nonwoven fabric is preferably a spunbond nonwoven fabric, and particularly preferably a spunbond nonwoven fabric containing polyester. The nonwoven fabric may also be a papermaking nonwoven fabric or felt containing polyester. Polyethylene-reinforced fiber woven fabric can also be used as the woven fabric.

[0082] (Method of manufacturing a laminate) The manufacturing method for the laminate configured as described above will now be explained. The laminate is manufactured by heat-pressing the prepared prepreg with a PP film.

[0083] The resulting sheet-like prepreg is placed on top of a PP film to form a superimposed layer (first superimposed layer). The superimposed layer is then heated and pressed to heat-bond it. The superimposed layer of prepreg and PP film is heated and pressed from above and below. As a result, a sheet-like laminate is formed.

[0084] The heat-pressing is performed using a hydraulic heat press or a multi-stage press at a temperature between 55°C and 100°C and a pressure between 1.5 MPa and 2.5 MPa. A heat-pressing temperature of 85°C or higher is preferred.

[0085] In this way, when the prepreg and PP film are heat-pressed together, the polypropylene that has permeated into the mesh and the polypropylene in the PP film become continuously integrated and firmly fixed to the mesh by the anchoring effect. As a result, a laminated sheet is produced in which multiple nonwoven fabrics are firmly bonded together by the PP hot melt material that has spread throughout through permeation.

[0086] [Fourth Embodiment (Bonding of Hot Melt Material Sheet and PP Film)] The bonding sheet may be formed from the PP hot melt material itself, and the sheet to be bonded may be a polypropylene film. This allows for the creation of a laminate bonded between the PP hot melt bonding sheet and the polypropylene film. The laminate consists of a PP hot melt layer and a PP film layer. Each layer of PP hot melt material is firmly bonded to the adjacent layer.

[0087] (Method of manufacturing a laminate) The manufacturing method for the laminate configured as described above will now be explained. The laminate is manufactured by heat-pressing a PP hot-melt sheet and a PP film. Specifically, the PP hot-melt sheet is placed on top of the PP film to form a superimposed layer (first superimposed layer). Then, the placed superimposed layer is heated and pressed to heat-press it. The superimposed layer of the PP hot-melt sheet and PP film is heated and pressed from above and below. As a result, a sheet-like laminate is formed.

[0088] The heat-pressing is performed using a hydraulic heat press or a multi-stage press at a temperature above a specified temperature, between 55°C and 100°C, and at a pressure between 1.5 MPa and 2.5 MPa. A heat-pressing temperature of 85°C or higher is preferred. In this way, the PP hot-melt sheet and the PP film are heat-pressed together, resulting in a continuous, integrated, and firmly bonded polypropylene structure. As a result, a laminated sheet is produced in which the layers are firmly joined together by the PP hot-melt material.

[0089] [Fifth Embodiment (Two-Stage Bonding)] In the above embodiment, the bonding of the bonding sheet and the sheet to be bonded is performed in one step, but it may also be performed in two steps. Similar to the above embodiment, the bonding sheet is a sheet mainly having PP hot melt material, and is a prepreg or a hot melt material sheet. The PP hot melt material contains not only polypropylene as the main component, but also a tackifier and an elastomer.

[0090] (First stage of joining) The sheets to be joined are placed on top of the joining sheet, and the resulting superimposed material is joined by applying a hot press. In this case, the hot press is applied at a temperature of 50°C to 125°C and a pressure of 1 MPa to 5 MPa. The temperature above 50°C creates tackiness in the joining sheet, promoting the joining process, while the temperature below 125°C prevents joining by melting. The hot press time is preferably 10 seconds or more, and from a practical standpoint, it is preferably 5 minutes or less. In the first stage of joining, it is even more preferable to apply a hot press at a temperature of 55°C to 100°C and a pressure of 1.5 MPa to 2.5 MPa.

[0091] During the first stage of bonding, the hot melt material is heated to a temperature between 50°C and 125°C. At this time, the tackifier and elastomer contained in the hot melt material exert adhesive force, and the bonding sheet and the sheet to be bonded are bonded together. However, with this adhesive bonding, delamination may occur when the material is reheated to above 100°C (reheating delamination).

[0092] (Second stage of joining) To further strengthen the first-stage bonding and eliminate the problem of delamination upon reheating, the superimposed material, after being hot-pressed and cooled, is heated to a temperature of 140°C to 160°C. The heating time is preferably 30 seconds or more, and preferably 5 minutes or less from a practical standpoint. Simultaneously with heating, it is preferable that the superimposed material is pressed against a mold or the like. The pressure during pressing is preferably 1 MPa to 5 MPa, and more preferably 1.5 MPa to 2.5 MPa.

[0093] During the second stage of joining, the main component, polypropylene (with a softening point of 135°C or higher), melts, and the joining sheet and the sheet to be joined are fused together. This results in a strong bond and prevents delamination upon reheating. Pressing is preferable during the second stage of joining. Pressing may be performed by hot pressing, or by injecting a resin such as polypropylene from the joining sheet side to press the sheet to be joined against the mold.

[0094] When injecting polypropylene, it is preferable to raise the polypropylene resin temperature to 170°C to 180°C to compensate for heat loss due to conduction and to maintain the bonded sheet at the specified temperature. Furthermore, during injection molding, if the PP resin is poured in from the side gate, it will flow too much due to its fluidity, so it is preferable to pour the PP resin from the multi-gate.

[0095] (Application of two-stage joining) Two-stage bonding is particularly well-suited for applications involving large components such as automobile bumpers. For example, when manufacturing large components using injection molding, the following process can be employed: A superimposed structure is prepared using a PP prepreg sheet as the bonding sheet and a PP film as the sheet to be bonded, and the first stage of bonding is performed. The resulting sheet is used as an intermediate component, and the intermediate component is positioned opposite the mold. By injecting PP resin towards the intermediate component and pressing it, a large component with high dimensional stability can be manufactured.

[0096] Traditionally, automobile bumpers are manufactured by injection molding PP resin into large molds and then painting the surface. However, the painting process lengthens and complicates the process due to pre- and post-processing and quality control, leading to increased costs. Therefore, there is a challenge to eliminate the painting process from the manufacturing of automobile bumpers. The two-stage bonding described above makes it possible to produce bumpers with a surface covered with colored PP film. Furthermore, this two-stage bonding method for large components can be applied not only to automobile components but also to toilet seats and other items.

[0097] [Sixth Embodiment (Bonding Sheet for Embedded Heat-Generating Material)] In the above embodiment, bonding is performed by heating the bonding sheet from the outside, but bonding may also be performed by embedding a heating material within the bonding sheet and heating the heating material by passing an electric current through it. Figures 11(a) and (b) are a perspective view and a cross-sectional view, respectively, of the bonding sheet 610. The bonding sheet 610 is formed by embedding a planar heater 612 in a PP prepreg sheet 611.

[0098] The planar heater 612 is a type of sheet-shaped heating material, for example, made by forming carbon fiber into a paper-like structure. For example, a planar heater 612 can be obtained by slicing discarded carbon fiber into small pieces and forming it into a paper-like structure, and with such a configuration, waste materials can be effectively utilized and the environmental burden can be reduced. In the bonding sheet 610, the material of the layer sandwiching the sheet-shaped heating material can be any resin that softens at a temperature of 140°C to 160°C, for example, it may be a PP film, or a combination of a PP film and a PP prepreg sheet.

[0099] The planar heater 612 is exposed from the PP prepreg sheet 611 at the four edges of the bonding sheet 610. This allows for the attachment of terminals, and by applying voltage, heating can be performed to promote fusion bonding. Preferably, the planar heater 612 is exposed from the PP prepreg sheet 611 at at least two edges of the bonding sheet 610. In some cases, the planar heater 612 may not be exposed from the PP prepreg sheet 611 at the edges of the bonding sheet 610. In that case, the planar heater 612 is connected to terminals inside the bonding sheet 610, and only the terminals are exposed from the edges of the bonding sheet 610 in two directions. Voltage can be applied to the exposed terminals.

[0100] The bonded sheet 610 can be formed by hot-pressing two PP prepreg sheets 611 with a planar heater 612 sandwiched between them. For example, the sheets can be hot-pressed at a temperature of 50°C to 125°C and a pressure of 1 MPa to 5 MPa for 10 seconds to 5 minutes. Alternatively, the sheets can be hot-pressed at a temperature of 140°C to 160°C and a pressure of 1 MPa to 5 MPa for 30 seconds to 5 minutes. In this case, heating may be performed using the planar heater 612.

[0101] For example, a laminate may be manufactured by joining a bonding sheet 610 to a sheet to be bonded 620. Figure 12 is a cross-sectional view showing the laminate 600. As shown in Figure 12, the bonding sheet 610 is formed by embedding a planar heater 612 in a PP prepreg sheet 611. The sheet to be bonded 620 is, for example, a PP film. In this embodiment, since the structure of each layer of the laminate 600 corresponds to the structure of the material sheet, the same reference numerals are used in the figure to represent them.

[0102] During joining, a voltage is applied to the planar heater 612, and the joining sheet 610 is heated from the inside, causing melt bonding to proceed. After joining, the planar heater 612 remains in place. For example, it is preferable to heat the joining sheet 610 to 150°C. When joining by hot press, the laminate 600 can be efficiently formed by instantaneously heating the laminate 600 with the joining sheet 610 without heating the mold, and then lowering the applied voltage to reduce the temperature.

[0103] Such laminates 600 can be used as interior materials for automobiles. Conventionally, interior materials in automobiles, such as the center console and armrest, which have cushioning material on the surface side, have the cushioning material covered with a sheet-like surface material or decorative material, and then sealed with fasteners by workers. By using a laminate with a surface heater embedded in the position of the fasteners as the surface material, and sealing the surface material by melt bonding through heating, manual work by workers becomes unnecessary, and efficiency can be improved. Similarly, in areas where sheets are currently joined by hand, it becomes possible to join them by melt bonding through heating using the joining sheet 610.

[0104] In the examples described above, a flexible mold, such as a silicone mold, can be used instead of a metal mold. While metal molds can be heated, flexible molds made of resin or the like are not suitable for heating. In such cases, heating from the inside using the bonding sheet 610 is particularly effective, rather than heating the flexible mold itself. In the manufacturing process of interior materials containing cushioning material, a silicone mold can be used when sealing the surface material using the bonding sheet 610.

[0105] The method using the heat-generating bonding sheet 610 can also be performed by placing cut pieces of the bonding sheet 610 in areas where partial bonding reinforcement is desired. Since electric current flows along the shortest path, even if planar heaters 612 are embedded throughout, only the areas where electric current flows through the planar heaters 612 will be heated. This allows heating to be performed only where needed. When molding large components, conventional methods for heating the entire component from the outside lead to larger and more complex equipment. However, by using the bonding sheet 610, equipment can be simplified and processes can be shortened.

[0106] The method using a bonding sheet with embedded heat-generating material can also be used for the two-stage bonding described above. In the first stage of bonding, heat pressing is performed by heating from an external source, and in the second stage of bonding, voltage is applied to the heat-generating material. This allows for efficient two-stage bonding. It also makes it possible to shorten the molding time and increase the bonding strength in localized areas.

[0107] [Large components and enclosures] Laminates can be used as large, high-strength components and enclosures, such as in automobile bodies, bumpers, and housing equipment. Laminates using prepregs, in particular, exhibit excellent shape stability; their dimensions do not change due to shrinkage after the heat-sealing process, making it possible to manufacture large components according to design specifications as a substitute for steel products. By decorating the surface of the laminate with polyester nonwoven or woven fabric as a coating base, and then converting the surface to PET resin, painting becomes possible. In this way, it can be applied to components where painting is essential, such as automobile exteriors. Furthermore, by using polyester conductive woven fabric for surface decoration, the entire component can be made non-static.

[0108] [Wire harness] A laminated structure with embedded functional components, containing wires that supply power to equipment and wires that transmit electrical signals to control equipment, can be used in wire harnesses. Because the wires are embedded between the composite layers, a wire harness less prone to short circuits and other malfunctions can be realized. Touch panels and antennas can also be integrated into the laminated structure.

[0109] [toilet seat] A laminate with an embedded heating element can also be used as a toilet seat. This toilet seat is a so-called heated toilet seat, and by passing an electric current through the heating element, the surface temperature can be maintained at around 40°C. A heated toilet seat can be realized with a surface made of polypropylene, which has excellent resistance to hydrochloric acid. Placing the heating element directly beneath the composite layer on the surface makes it easier to conduct heat to the surface, improving thermal efficiency. Alternatively, a laminate can be used as a toilet seat without embedding the heating element. In that case, it is preferable to use a surface material that has been processed to have a pleasant texture, such as brushed fabric.

[0110] [Experiment 1 (Comparison of PP hot melt materials)] PP prepreg sheets were prepared using three types of PP hot melt materials with different softening points, and various tests were conducted.

[0111] (Prepreg fabrication) 100g / m² of 0.11mm thick polyester nonwoven fabric sheet (Toray Akstar N2070-6S) 2 A PP hot melt material was applied and impregnated by hot pressing at 135°C to produce a prepreg. The PP hot melt materials used were HM-A (low temperature), HM-B (medium temperature), and HM-C (high temperature) as shown in the table below (Asahi Chemical Synthesis Asahitack TD0-3399, TD0-3448, TD0-3447). All were successfully impregnated, and three types of PP prepreg sheets (prepreg A, B, and C) were produced.

[0112] [Table 1]

[0113] (Crimping test) Two sheets of each type of PP prepreg were stacked and pressed together using a hot press at 100°C and 2.5 MPa. In each case, a laminate was created in which the PP prepreg sheets were joined, and it was confirmed that they were integrated.

[0114] (PP film bonding test) Bonding tests were conducted on the three types of laminates prepared in the above-described compression test using polypropylene film (hereinafter referred to as PP film). Specifically, sheets of prepreg A to C were sandwiched between two PP films, and heat-pressed at a predetermined mold temperature and a pressure of 2.5 MPa. Afterwards, the bonding was confirmed by sensory testing (that the bond was strong enough that it could not be separated by human force; the same applies below), as shown in the table below. In the table, "×" indicates that the bond was not formed, and "○" indicates that the bond was formed.

[0115] [Table 2]

[0116] Furthermore, when heat-pressing two prepreg C sheets and prepreg C to a PP sheet was performed at 55°C, both bonding was successful. However, it was found that heat-pressing was difficult at temperatures below 55°C. In addition, while all of the above bonding is possible by heat pressing at 125°C, it was found that the fluidity of the PP hot melt material increases, making it difficult to handle.

[0117] (Bonding test of PVB composite material) The laminate of prepreg C prepared in the above compression test was bonded to the surface of a PVB composite material, which was constructed by impregnating a nonwoven fabric sheet with PVB, using a hot press at 100°C and 1.5 MPa. It was confirmed that the resulting laminate was integrated.

[0118] (3D press test) 3D molding was performed on laminates formed by joining PVB composite material and prepreg C, and the moldability and the occurrence of delamination were confirmed. For 3D molding, a shallow-drawn mold with a case shape of 100 × 150 × 2 mm and a deep-drawn mold with a case shape of 100 × 150 × 12 mm were used. Hot pressing was performed with the shallow-drawn mold at a press temperature (upper plate 60°C / lower plate 60°C) and a press pressure of 6 MPa, and hot pressing was performed with the deep-drawn mold at a press temperature (upper plate 30°C / lower plate 50°C) and a press pressure of 8 MPa. In the press tests of both the shallow-drawn and deep-drawn molds, both types of laminates were molded without any problems.

[0119] (summary) The test results are summarized in the table below. In the table, "×" indicates failure to achieve crimping or bonding, and "○" indicates success. "-" indicates that the test was not performed.

[0120] [Table 3]

[0121] [Experiment 2 (Confirmation of prepreg C bonding)] (Bonding tests of various sheets) Using the laminate fabricated with the above-mentioned prepreg C, various sheets were further joined by hot pressing at 100°C and 2.5 MPa. The combinations are as follows. Note that " / " indicates joining by hot pressing. 3M DiNOC was used for the PVC decorative sheet. All combinations were successfully integrated. (1) PVC decorative sheet / nonwoven fabric / prepreg C laminate / PVB composite material (2) Wood veneer / PVB / Nonwoven fabric / Prepreg C laminate / PVB composite material (3) Stone / PVB / Nonwoven fabric / Prepreg C laminate / PVB composite material

[0122] (Insert molding test) The resulting sheets were punched out into the shape of injection-molded parts, press-molded using a mold, trimmed of excess material, and then hot-pressed at 60°C for the upper plate and 60°C for the lower plate, with a press pressure of 6 MPa to produce preformed molded parts for insert molding. Then, insert molding was performed into the preformed molded parts using GF-reinforced PP resin at a resin temperature of 180°C and a mold temperature of 60°C. As a result, molding was successful in all cases without any problems.

[0123] (Integrated heating element) A sheet of heat-generating fiber (made of FCC) was sandwiched between two sheets of prepreg C as a heat-generating material, and this was then sandwiched between two sheets of PP film. A laminate was then fabricated by hot pressing at a temperature of 85°C and a pressure of 2.5 MPa to embed the heat-generating material. The resulting laminate was integrated, and when a voltage was applied to the heat-generating material, a rise in temperature was confirmed.

[0124] [Experiment 3 (Confirmation of HM-C bonding)] (PP film bonding test) A sheet of HM-C PP hot melt material was sandwiched between two polypropylene films and hot-pressed at a specified temperature and pressure of 2.5 MPa. The specified temperatures were 85°C, 100°C, and 125°C. The resulting laminate was confirmed to have sufficient bonding strength through sensory testing.

[0125] (Bonding test of PVB composite material) Using HM-C PP hot melt material sheets, PVB composite material was further bonded by hot pressing at 100°C and 2.5 MPa. The combination is as follows, and integration was successful. (1) PP sheet / HM-C PP hot melt material sheet / PVB composite material

[0126] (Insert molding test) The laminated sheets obtained from the bonding tests of the PVB composite material described above were punched out into the shape of injection-molded parts, press-molded using a mold, trimmed of excess material, and then hot-pressed at 60°C for the upper plate and 60°C for the lower plate, with a press pressure of 6 MPa to produce preformed molded parts for insert molding. Then, insert molding was performed into the preformed molded parts using GF-reinforced PP resin at a resin temperature of 180°C and a mold temperature of 60°C. As a result, the molding was completed without any problems.

[0127] [Experiment 4 (Two-stage bonding)] When a PP film and a sheet of prepreg C were bonded in two stages under the following conditions, the sample that had undergone the first stage of bonding exhibited reheating delamination at 100°C. On the other hand, the sample that had undergone the second stage of bonding did not exhibit reheating delamination at 100°C. [Table 4]

[0128] In the first stage of bonding, sufficient bonding was achieved in 10 seconds. In the second stage of bonding, bonding was achieved in 30 seconds. It is thought that the second stage requires time for the PP resin to melt and permeate. [Explanation of Symbols]

[0129] 10 Nonwoven fabric 20 PP hot melt material 30 prepregs 31-36 Prepreg 40a, 40b Superimposed 41 Laminate 42-43 Molded body 51-52 Textiles 100-layer structure 111~114 Composite layer 200-layer structure 211~212 Composite layer 231 Heating material 300-layer structure 311~312 Composite layer 331 elements 400-layer structure 410 Prepreg layer 420 Backer Seats 421, 423 PVB composite layer 422 PVB film layer 430 Substrate resin layer 441 Laminate 442 Molded body 443 Preformed molded body 451, 453 Textiles 452 PVB film 470 decorative layers 600-layer structure 610 Bonding Sheet 611 PP prepreg sheet 612 Planar heater 620 Bonded Sheet D1 Male mold D2 Female mold M1, M2, M3 nozzle section M10 injection molding machine M11 injection screw M12 Female Mold M13 Male Mold M15 injection hole M16 injection molding hole R1~R4 Roll P1 raw material T1 Tank

Claims

1. A process of forming a first superimposed body by stacking a bonding sheet and a sheet to be bonded, mainly having a PP hot melt material, The process includes a step of hot-pressing the first superimposed body at a temperature of 50°C to 125°C and a pressure of 1 MPa to 5 MPa, The aforementioned PP hot melt material contains polypropylene as its main component, A method for manufacturing a laminate, characterized in that the softening point of the PP hot melt material is 135°C or higher.

2. The method for manufacturing a laminate according to claim 1, characterized in that the first superimposed body is hot-pressed at a temperature of 55°C to 100°C and a pressure of 1.5 MPa to 2.5 MPa in the hot-pressing step.

3. The method for manufacturing a laminate according to claim 1, characterized in that the PP hot melt material has a tensile strength of 2.0 MPa or less at room temperature, an elongation of 300% or less at room temperature, and a melt viscosity of 6000 mPa·s or more at 160°C.

4. The method for manufacturing a laminate according to any one of claims 1 to 3, characterized in that the bonding sheet is a composite sheet having a sheet-like textile and the PP hot melt material that has permeated and fixed into the mesh of the textile.

5. The method for manufacturing a laminate according to claim 4, characterized in that the sheet to be bonded is also the composite sheet.

6. The method for manufacturing a laminate according to claim 5, characterized in that a functional member is sandwiched between the bonding sheet and the sheet to be bonded to form the first superimposed body.

7. The method for manufacturing a laminate according to any one of claims 1 to 3, characterized in that the sheet to be bonded is a polypropylene film.

8. The method for manufacturing a laminate according to any one of claims 1 to 3, characterized in that the sheet to be joined is a sheet-like textile.

9. The method for manufacturing a laminate according to any one of claims 1 to 3, further comprising the step of heating the first laminate, which has been cooled after being heat-pressed, at a temperature of 140°C to 160°C.

10. The method for manufacturing a laminate according to claim 9, characterized in that the heating step involves heating the first laminate by injection molding resin onto the bonding sheet side of the first laminate.

11. The method for manufacturing a laminate according to claim 9, characterized in that the heating step involves hot-pressing the first superimposed body at a pressure of 1 MPa to 5 MPa.

12. The method for manufacturing a laminate according to any one of claims 1 to 3, characterized in that a sheet-like heat-generating material is embedded in the bonding sheet.

13. The method for manufacturing a laminate according to claim 12, characterized in that the heat-generating material is exposed at the edges of the bonding sheet in at least two directions.

14. A first layer mainly consisting of PP hot melt material, The first layer is joined to a second layer, The aforementioned PP hot melt material contains polypropylene as its main component, The laminate is characterized in that the softening point of the PP hot melt material is 135°C or higher.

15. The laminate according to claim 14, characterized in that the PP hot melt material has a tensile strength of 2.0 MPa or less at room temperature, an elongation of 300% or less at room temperature, and a melt viscosity of 6000 mPa·s or more at 160°C.

16. The laminate according to claim 14 or 15, characterized in that the first layer is a composite layer having a sheet-like textile and the PP hot-melt material that has permeated and fixed into the mesh of the textile.

17. The laminate according to claim 14 or 15, characterized in that the second layer is made of polypropylene.

18. The laminate according to claim 14, characterized in that the first layer has an embedded sheet-like heat-generating material.

19. The laminate according to claim 18, characterized in that the first layer has the heating material exposed at at least two edges of the first layer.

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