Pp-FRP member and production method therefor

Abstract

The present invention provides: a PP-FRP member with high strength and excellent shape stability due to integration between laminated composite layers; and a production method therefor. A PP-FRP member 100 comprises a plurality of composite layers 111-114 that each have a sheet-like textile and polypropylene which is impregnated and fixed in the mesh of the textile, wherein the plurality of composite layers 111-114 are laminated, adjacent textiles contact each other, and the polypropylene is filled in the mesh of the textile and integrated. Thus, it is possible to obtain a PP-FRP member with high strength and excellent shape stability due integration between the laminated composite layers 111-114.

Description

PP-FRP member and its manufacturing method

[0001] The present invention relates to a PP-FRP (Fiber Reinforced Plastics) member and a method for manufacturing the same.

[0002] Conventionally, a resin decorative molding technique has been known in which a component is produced by infiltrating a resin into fibers (see, for example, Patent Documents 1 and 2). The resin used for infiltration is, for example, PVB (polyvinyl butyral). A component in which the resin and the fiber layer are integrated has sufficient strength. In such a component, the injection-molded base resin layer is also fixed while infiltrating into the gaps between the fibers of the nonwoven fabric layer.

[0003] In the housing described in Patent Document 1, a nonwoven fabric layer is bonded to a decorative layer via an adhesive resin layer. The adhesive resin layer is made of, for example, polyvinyl butyral (PVB), which has a viscosity that allows air bubbles to escape when softened. Patent Document 1 also discloses that polypropylene is used as an example of a material for the base resin layer that constitutes the housing, and that the adhesive resin layer has a built-in conductor.

[0004] Patent Document 2 discloses a veneer sheet and its application products in which a nonwoven fabric mainly made of fibers capable of maintaining its shape at temperatures higher than the melting point of the resin film is interposed between the back surface of the veneer and the resin film, making the resin film resemble FRP. PET fiber is cited as an example of the nonwoven fabric, and a propylene film is cited as an example of the resin film. The veneer sheet described in Patent Document 2 firmly bonds the nonwoven fabric and the base resin by exerting an anchor effect between them.

[0005] JP 2020-175641 A Republished 2013-190839 A

[0006] Polypropylene is not only inexpensive to procure but also has excellent chemical resistance, making it suitable for a variety of applications. The inventors of the present invention have been working on fabricating an integrated laminate using only polypropylene as the resin to be infiltrated into the fibers of a nonwoven fabric. However, it is common knowledge in the molding field that even if multiple sheets made of polypropylene are stacked and thermocompression bonded, the layers derived from the sheets peel off from the resulting product, making it impossible to firmly integrate the entire product into a polypropylene-only component.

[0007] Patent Document 2 cites a propylene film as an example of a resin film. However, the purpose of impregnating the nonwoven fabric with resin is to bond the sliced ​​veneer sheet to the sliced ​​veneer, and only a single layer is formed for bonding. Therefore, it is difficult to use such sliced ​​veneer sheets as FRP components that require shape stability and strength according to the design, such as automobile bodies.

[0008] The present invention has been made in view of the above circumstances, and aims to provide a high-strength PP-FRP member with excellent shape stability due to the integration of laminated composite layers, and a method for manufacturing the same.

[0009] (1) In order to achieve the above object, the present invention employs the following means. Specifically, the PP-FRP member of the present invention comprises a sheet-like textile and multiple composite layers having polypropylene infiltrated into and fixed to the mesh of the textile, the multiple composite layers being stacked, with adjacent textiles in contact with each other, and the polypropylene filling the mesh of the textile and integrating them. As a result, the stacked composite layers are integrated together, resulting in a high-strength PP-FRP member with excellent shape stability.

[0010] (2) In the PP-FRP member described in (1) above, the textile constituting each of the plurality of composite layers is a nonwoven fabric, which allows for easy formation by layering and pressing prepregs in which polypropylene is impregnated onto nonwoven fabric.

[0011] (3) In the PP-FRP member described in (1) above, one of the textiles constituting adjacent composite layers of the plurality of composite layers is a nonwoven fabric, and the other is a woven fabric. This structure is formed by sandwiching the woven fabric between the prepregs, which improves shape stability.

[0012] (4) The PP-FRP member according to any one of (1) to (3) above is characterized by further comprising a conductive material provided between the textiles of the adjacent composite layers, thereby providing various functions by the conductive material.

[0013] (5) In addition, in the PP-FRP member according to any one of (1) to (4) above, the melting point of the polypropylene is 160°C or less. This allows processing at low temperatures, and the PP-FRP member can be used for, for example, surface decoration.

[0014] (6) In the PP-FRP member according to any one of (1) to (5) above, the polypropylene contains 5 wt % to 30 wt % of a tackifier, which allows for easy preparation of prepregs by hot melting.

[0015] (7) The PP-FRP member according to any one of (1) to (6) above is characterized in that when the PP-FRP member is heat-pressed at a temperature of 100°C to 150°C and a pressure of 2.5 MPa or less, the change in length between before and after the heat-pressing is 1% or less. This excellent shape stability of the PP-FRP member makes it easy to apply.

[0016] (8) The method for producing a PP-FRP member of the present invention includes the steps of stacking a plurality of prepreg sheets each having a nonwoven fabric and polypropylene impregnated into the nonwoven fabric to form a first laminate, and hot pressing the first laminate at a predetermined temperature or higher and a predetermined pressure or higher, thereby enabling the production of a dense, high-strength plastic member with excellent chemical resistance at low cost.

[0017] (9) The method for manufacturing a PP-FRP member of the present invention is characterized by including the steps of alternately stacking a plurality of prepreg sheets and sheet-like textiles, each having a woven fabric and polypropylene impregnated therein, to form a second laminate, and hot pressing the second laminate at a predetermined temperature or higher and a predetermined pressure or higher. This allows for the production of a dense, high-strength plastic member with excellent chemical resistance at low cost. Furthermore, shape stability can also be improved.

[0018] (10) In the method for producing a PP-FRP member according to (8) or (9) above, the predetermined temperature is 100°C or higher and 150°C or lower, and the predetermined pressure is 1.5 MPa or higher and 2.5 MPa or lower. This allows the stacked composite layers to be integrated together, resulting in a high-strength PP-FRP member with excellent shape stability.

[0019] (a) to (c) are cross-sectional views showing the steps of producing a prepreg; (a) to (c) are cross-sectional views showing the steps of stacking prepregs and thermocompression bonding; (b) are cross-sectional views showing the steps of thermocompression bonding prepregs and textiles; (a) to (d) are cross-sectional views showing the steps of molding and trimming; (a) and (b) are cross-sectional views showing a PP-FRP member with embedded wires and elements; and (c) are micrographs of the cut surface.

[0020] Through trial and error, the inventors of the present invention produced a PP-FRP component by stacking prepregs in which polypropylene was infiltrated and fixed to sheet-like nonwoven fabric, and then bonding them by thermocompression, leading to the present invention. By making the polypropylene infiltrated and fixed into the mesh of the nonwoven fabric continuous in multiple layers, the laminate can be firmly integrated while maintaining shape stability. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0021] [First embodiment] [Configuration of PP-FRP member] Fig. 1 is a cross-sectional view showing a PP-FRP member 100. The configuration shown in Fig. 1 is one example, and the PP-FRP member 100 is made up of composite layers 111 to 114. The composite layers 111 to 114 are laminated, and each of the composite layers 111 to 114 is made up of textile and polypropylene that has infiltrated into and fixed to the mesh of the textile.

[0022] In the composite layers 111-114, polypropylene exists continuously across the layers and permeates the mesh of the textile. The anchoring effect of the permeated polypropylene firmly bonds each of the composite layers 111-114 to the adjacent layer. In this way, a strongly integrated plate-like member is formed.

[0023] The polypropylene preferably contains 5 wt % to 30 wt % of a tackifier, which is a tackifying resin, such as a petroleum-based tackifier, which facilitates the preparation of prepregs by hot melt.

[0024] The polypropylene may have a high melting point. Such a high-melting-point polypropylene is a high-shrinkage material and can be used for components for products requiring a high elastic modulus. A preferred high-melting-point polypropylene has a melting point of 150°C or higher. Such a high-melting-point polypropylene is preferably composed of 85 wt% to 95 wt% polypropylene and 5 wt% to 15 wt% tackifier.

[0025] Furthermore, polypropylene with a low melting point can also be used. Such low-melting polypropylene is a low-shrinkage type and slightly softer than high-melting polypropylene. It can be used to impregnate synthetic fiber fabrics with low heat resistance, such as polyethylene reinforced fiber. A low-melting polypropylene with a melting point of 100°C or less is preferred. Such low-melting polypropylene is preferably composed of 70 wt% to 85 wt% polypropylene and 15 wt% to 30 wt% tackifier.

[0026] It is preferable that the melting point of polypropylene is at least 160°C or lower. This allows processing at low temperatures and enables joining of components with different melting points. For example, a component with a surface decorated with polypropylene, which has a high melting point, can be formed and joined to a PP-FRP component.

[0027] The textiles contained in each of the composite layers 111 to 114 are preferably all nonwoven fabrics or nonwoven fabrics and woven fabrics are alternately layered. The nonwoven fabric is preferably a spunbond nonwoven fabric, and particularly preferably a spunbond nonwoven fabric containing polyester. The nonwoven fabric may be a paper-based nonwoven fabric containing polyester or a felt. The textile has a basis weight of 20 g / m. 2 More than 300g / m 2 The following can be used:

[0028] As the nonwoven fabric, a polypropylene nonwoven fabric can also be used. The polypropylene nonwoven fabric has a high bulkiness. For example, the nonwoven fabric has a basis weight of 20 g / m. 2 70g / m or more 2 When using the polypropylene nonwoven fabric shown below, the high porosity makes it easy for the softened polypropylene to penetrate during the hot melt process. This also has the cost advantage of allowing a composite layer of the same thickness to be formed using fewer sheets of nonwoven fabric. Furthermore, composite layers made by impregnating polypropylene into polypropylene nonwoven fabric do not need to be separated into individual materials when recycled.

[0029] The woven fabric may be a polyethylene reinforced fiber woven fabric. When a polyester nonwoven fabric is used, the basis weight is 30 g / m. 2 More than 250g / m 2 This makes it easier for the softened polypropylene to be impregnated.

[0030] In the PP-FRP member 100, the composite layers 111 to 114 have a four-layer structure, but other numbers of layers may be used. A four-layer structure or more can improve the strength of the PP-FRP member 100 and stabilize its shape. On the other hand, a structure of fewer than four layers makes it easier to mold.

[0031] [Manufacturing Method of PP-FRP Member] A method for manufacturing the PP-FRP member 100 configured as described above will now be described. The PP-FRP member 100 is manufactured through the steps of prepreg production, thermocompression bonding, preform molding, and trimming. Figures 2(a) to 2(c) are cross-sectional views showing the prepreg production steps.

[0032] First, a prepreg is prepared. For example, as shown in Fig. 2(a), a sheet-like nonwoven fabric 10 is placed with its surface horizontal, and then polypropylene 20, which has been heated to a temperature above its softening point and softened, is applied to the nonwoven fabric 10, allowing it to infiltrate and bond, thereby producing a prepreg 30. The nonwoven fabric 10 preferably has a thickness of 50 µm to 500 µm.

[0033] For coating, a hot melt coating machine called a melter can be used. The example of the machine shown in Figure 2(a) is a sheet-fed coating machine, in which the nonwoven fabric 10 is fixed and a spray nozzle M1 is moved over the entire nonwoven fabric 10 to coat the polypropylene 20 onto the nonwoven fabric 10 and produce the prepreg 30.

[0034] The example of the apparatus shown in Figure 2(b) is a roll-to-roll continuous impregnation apparatus. By fixing the spray nozzle M2 and moving the nonwoven fabric 10 from roll R1 to roll R2, polypropylene 20 can be applied to the entire nonwoven fabric 10 to produce prepreg 30. In the above-described applicator, it is preferable to move either the applicator side or the nonwoven fabric side at a constant speed relative to the other during application.

[0035] The example of the apparatus shown in Figure 2(c) is also a continuous impregnation apparatus using rolls. A discharge nozzle M3 is fixed, and polypropylene 20 is supplied to a position between rolls R3 and R4. The polypropylene 20 is infiltrated into the nonwoven fabric 10 that is sandwiched between the rolls R3 and R4 and fed out. Using such a continuous impregnation apparatus can improve the production efficiency of the prepreg 30.

[0036] The heated and softened polypropylene may be collected in a container, and the sheet-shaped textile may be immersed in the container (so-called "dipping"). The polypropylene that has soaked into the textile in this way is cooled and hardened to form a prepreg. In this case, it is preferable to pass the textile through the polypropylene by continuously moving it at a constant speed using a roller or the like.

[0037] The sheet-like prepreg thus obtained preferably has a thickness of 100 μm or more and 1500 μm or less, and more preferably has a thickness of 100 μm or more and 500 μm or less.

[0038] The obtained plurality of sheet-like prepregs 30 are stacked and arranged according to a predetermined design to form a stack (first stack). The arranged stack is then heated and pressed to thermocompression bond it. Figure 3 is a perspective view showing the process of stacking and thermocompression bonding prepregs. In the example shown in Figure 3, a stack 40a in which four prepregs 31 to 34 are stacked is heated and pressed from above and below. As a result, a sheet-like laminate is formed.

[0039] The thermocompression bonding is preferably performed using a hydraulic hot press or a multi-stage press at a predetermined temperature or higher and a predetermined pressure or higher. The predetermined temperature is a temperature equal to or lower than the melting point and softening point of polypropylene. For example, heating to a temperature of 140°C or higher and 160°C or lower is preferable. The predetermined pressure is preferably 1.5 MPa or higher and 2.5 MPa or lower. This allows the polypropylene to infiltrate and bond into the mesh of the textile, creating an anchor effect and firmly integrating the components.

[0040] In this way, by thermocompressing the prepreg at a temperature higher than the softening point and lower than the melting point of polypropylene, the polypropylene that has infiltrated into the mesh continuously integrates and firmly bonds to the mesh through an anchor effect. As a result, a sheet of PP-FRP component 100 is produced as a laminated sheet in which multiple nonwoven fabrics are firmly bonded by the infiltrated polypropylene.

[0041] The PP-FRP member 100 has excellent shape stability, and when hot-pressed at a temperature of 100°C to 150°C and a pressure of 2.5 MPa or less, the absolute value of the rate of change in length before and after pressing is 1% or less. In this way, the PP-FRP member is less likely to change in dimension before and after pressing. This allows the PP-FRP member to be formed as designed, making it easy to apply.

[0042] After lamination by thermocompression, the PP-FRP member 100 can be naturally cooled to stabilize its shape. Therefore, it is possible to mass-produce them simultaneously using a multi-stage press. A multi-stage press is a heat press machine that has an intermediate heat plate in addition to upper and lower heat plates, and is provided with multiple openings as stages to sandwich the material. By sandwiching the material between multiple stages and applying pressure with a press while heating, multiple PP-FRP members can be formed simultaneously.

[0043] PP-FRP components have a composite layer structure in which polypropylene is infiltrated and fixed into the textile, giving them high strength, making them suitable for use in components that require light weight and strength, such as automobile bodies.

[0044] The sheet of PP-FRP member 100 obtained through the above process is then 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 a male mold D1 and a female mold D2.

[0045] Next, the male mold D1 and female mold D2 are clamped together as shown in FIG. 4(b). As a result, a laminate 41 is formed. After clamping, the male mold D1 and female mold D2 are opened as shown in FIG. 4(c), and the resulting molded body 42 is released. Then, as shown in FIG. 4(d), unnecessary portions are trimmed away to obtain a molded body 43. Even after this molding process, the change in length from the laminate 41 to the molded body 43 is within 1%, and the PP-FRP member 100 has excellent shape stability. The resulting PP-FRP member 100 is further machined as appropriate depending on the application. The PP-FRP member 100 can be used in a variety of products using polypropylene as a surface layer.

[0046] Second Embodiment In the above embodiment, only prepregs are stacked and thermocompression bonded. However, prepregs and textiles may be alternately stacked and thermocompression bonded. FIG. 5 is a perspective view showing the process of thermocompression bonding prepregs and textiles. The textiles alternately stacked with the prepregs are woven fabrics or nonwoven fabrics. In the example shown in FIG. 5, two prepregs 35-36 and two textiles 51-52 are alternately stacked to form a stack 40b (second stack), which is then thermocompression bonded. As a result, a sheet-like laminate is formed. Thermocompression bonding in this case can also be performed using the same equipment and under the same temperature conditions as in the first embodiment.

[0047] In this case, too, the prepreg and textile are thermocompression bonded at a temperature higher than the softening point and lower than the melting point of polypropylene, so that the polypropylene in the prepreg also infiltrates into the mesh of the textile, firmly adhering to the mesh through an anchoring effect. As a result, a sheet of PP-FRP component 100 is produced as a laminated sheet in which the prepreg and textile are bonded together by the polypropylene that has continuously spread through the infiltration.

[0048] [Third Embodiment] [Configuration of PP-FRP Member with Embedded Circuit Component] Conductors can be embedded in the main body layer of the above-described PP-FRP member 100. Figures 6(a) and 6(b) are cross-sectional views showing PP-FRP members 200 and 300, respectively, in which conductors and elements are embedded in the main body layer. The PP-FRP member 200 is basically configured similarly to the PP-FRP member 100, but has embedded conductors 231 and related features.

[0049] In the PP-FRP member 200, a conductor 231 is provided between the composite layer 211 and the composite layer 212. In this way, the PP-FRP member 200 can be configured, which is firmly integrated by polypropylene and has added functionality due to the conductor 231 provided inside.

[0050] In the example shown in FIG. 6( a), a conductor 231 with a circular cross section is provided between the composite layer 211 and the composite layer 212. The conductor 231 is, for example, a conductor for supplying power or controlling each device. Because the PP-FRP member 200 is formed by sandwiching the conductor 231 and thermocompression bonding it, a semicircular depression corresponding to the cross-sectional shape of the conductor is formed in the composite layer 212 pressed against the conductor 231. Because the composite layers 211 and 212 flexibly deform in this way, the surface of the composite layer 211 can be smoothed. Because the conductor 231 is embedded between the composite layers, it is not a problem if the conductive material of the conductor 231 is exposed without an insulating coating.

[0051] In the above example, the conductive wire 231 is provided between the nonwoven fabrics in the composite layer, but when nonwoven fabrics and woven fabrics are provided alternately, the conductive wire 231 may be provided between the nonwoven fabrics and the woven fabrics. In other words, the conductive wire 231 only needs to be embedded inside the multiple layer structure that constitutes the PP-FRP member 200, and in that case, the conductive wire 231 may be embedded between any of the layers.

[0052] On the other hand, the PP-FRP member 300 is also basically configured in the same manner as the PP-FRP member 200, but differs in the element 331 embedded in the PP-FRP member 300 and the related features. In the example shown in Figure 6(b), an element with a flat cross section is provided as element 331 between composite layer 311 and composite layer 312. In the manufacturing process, composite layer 312 is pressed against element 331, and a flat depression corresponding to the cross section of the element is generated.

[0053] The manufacturing process of the PP-FRP members 200 and 300 is similar to that of the PP-FRP member 100. However, the difference is that when the prepreg and the textile are arranged, the conducting wire 231 or the element 331 is arranged between them.

[0054] [Large Components and Housings] PP-FRP components can be used as large components and housings that require strength, such as automobile bodies, bumpers, and housing equipment. PP-FRP components have excellent shape stability and do not change dimensions due to shrinkage after the thermocompression bonding process, making them suitable for manufacturing large components as designed as a replacement for steel products. By decorating the surface of a PP-FRP component with a polyester nonwoven or woven fabric as a coating base and then coating the surface with PET resin, painting becomes possible. In this way, they can be applied to components where painting is essential, such as automobile exteriors. Furthermore, by using polyester conductive woven fabric for the surface decoration, the entire component can be made electrically non-static.

[0055] [Wiring Harness] PP-FRP members with embedded conductors for supplying power to devices and transmitting electrical signals for controlling devices can be used in wiring harnesses. Because the conductors are embedded between composite layers, wiring harnesses that are less susceptible to problems such as short circuits can be realized. It is also possible to incorporate touch panels and antennas into PP-FRP members.

[0056] [Toilet Seat] A PP-FRP member with a heater wire embedded as a conductor can also be used for a toilet seat. The toilet seat is a so-called heated toilet seat, and the surface temperature can be maintained at around 40°C by passing an electric current through the heater wire. There are no particular restrictions on the material of the heater wire. A heated toilet seat can be realized with a surface formed from polypropylene, which has excellent hydrochloric acid resistance. Placing a heater wire directly under the composite layer on the surface facilitates heat conduction to the surface, improving thermal efficiency. PP-FRP members can also be used for toilet seats without embedding the heater wire. In this case, it is preferable to use a surface material that has been treated to be pleasant to the touch, such as with a raised nap.

[0057] [Backer] PP-FRP members can be used as backers for composite laminates of PP film and nonwoven fabric. They can also be used as backers for composite laminates of resin films such as PMMA, PET, and PC with nonwoven fabric. In such cases, PVB resin is used as an adhesive to bond the resin film to the nonwoven fabric. Furthermore, ABS resin, PP, PC, PMMA, or other resins may be injection molded onto the backside as the base resin. In this way, they can be used in a variety of applications as lightweight intermediate processing materials with low processing temperatures, for example, around 120 to 150°C.

[0058] [Experiment 1] Hot-melt polypropylene (HMPP) containing tackifier was heated and softened, and the softened polypropylene was applied to a nonwoven fabric made of spunbond polyester to prepare a prepreg. The nonwoven fabric used was nonwoven fabric N2070-6S manufactured by Toray Industries, Inc. For convenience, a prepreg using low-melting-point (95°C) hot-melt polypropylene (PP 80 wt%, tackifier 20 wt%) was referred to as "Prepreg 2." The resulting prepreg was used to stack materials in the following combinations:

[0059]

[0060] The black nonwoven fabric is denser and harder than regular nonwoven fabric. Nonwoven fabric G2200-BKO manufactured by Toray Industries, Inc. was used as the black nonwoven fabric. The coarse white nonwoven fabric is lower in density than regular nonwoven fabric. Nonwoven fabric D5100 manufactured by Toray Industries, Inc. was used as the coarse white nonwoven fabric.

[0061] A square with approximately 100 mm sides was drawn on the surface of the laminated sample using a 0.5 mm felt-tip pen, and the length of each side was measured twice and averaged. The length was measured to the nearest 0.01 mm using a digital caliper (same below). Each sample was thermocompressed for 1 minute using a hydraulic hot press. During thermocompression bonding of laminate sample 3, a 15 mm spacer was inserted to prevent the sample from becoming too flat and crushed, which would deviate from the purpose of the bonding.

[0062] After thermocompression bonding, the length of each side of the square was measured twice and the results were averaged. The change in the length of the square for all of the laminate samples 1 to 3 obtained as PP-FRP members was within 1%. The measurement results are shown in the table below.

[0063]

[0064] Next, a prepreg using a hot-melt polypropylene (PP 90 wt%, tackifier 10 wt%) with a high melting point (155°C) and a prepreg using a hot-melt polypropylene with a low melting point (95°C) were laminated, and the sample was sandwiched between nonwoven fabrics at both ends and thermocompression bonded. For convenience, the prepreg using the hot-melt polypropylene with a high melting point (155°C) is referred to as "prepreg 1." The materials were layered in the following combinations:

[0065]

[0066] A square with approximately 100 mm sides was drawn with a felt-tip pen on the surface of the sample where the materials were stacked, and the length of each side was measured twice and averaged. Each sample was thermocompression bonded by pressing it for 1 minute using a hydraulic heat press. After thermocompression bonding, the length of each side of the square was measured twice and averaged. For both laminate samples 4 and 5 obtained as PP-FRP members, the change in square length was within 1%. The measurement results are shown in the table below.

[0067]

[0068] Next, a sample was prepared by laminating a prepreg made of hot-melt polypropylene with a high melting point (155°C) and a nonwoven fabric, and then thermocompression bonding was performed. The materials were laminated in the following combinations.

[0069]

[0070] A square with a side length of approximately 100 mm was drawn with a felt-tip pen on the surface of the sample where the materials were stacked, and the length of each side was measured twice and averaged. Each sample was thermocompression bonded by pressing it for 1 minute using a hydraulic heat press. After thermocompression bonding, the length of each side of the square was measured twice and averaged. For both laminate samples 6 and 7 obtained as PP-FRP members, the change in the length of the square was within 1%. The measurement results are shown in the table below.

[0071]

[0072] As described above, the change in length before and after thermocompression bonding was 1% or less for all laminate samples, demonstrating extremely excellent shape stability. In particular, when prepregs using low-melting-point hot-melt polypropylene were laminated and thermocompression bonding was performed at a relatively low temperature of 120°C or less, the change was 0.4% or less. These results demonstrate that the PP-FRP components not only have excellent shape stability during manufacture, but also that the manufactured PP-FRP components have excellent shape stability, with a change in length of 1% or less even when hot-pressed at a temperature of 100°C to 150°C and a pressure of 2.5 MPa or less.

[0073] [Experiment 2] For comparison, a 0.5 mm thick 100% polypropylene (PP) film was heat-treated for 1 minute. The heat treatment was performed under the following temperature, pressure, and measurement conditions. Before the heat treatment, a square approximately 100 mm on each side was drawn on the surface of the sample with a felt-tip pen, and the length of each side was measured twice and averaged. After the heat treatment, the length of each side of the square was measured twice and averaged to calculate the rate of change.

[0074]

[0075] It was found that the shape of polypropylene film samples 4 and 6 changed when a pressure of 2 MPa was applied at a temperature above the softening point. The rate of change exceeded 1%, indicating that sufficient shape stability could not be obtained even when a laminate was produced by compressing polypropylene films.

[0076] [Experiment 3] The PP-FRP member obtained in Experiment 1 was cut, and the cut surface was observed under a microscope. Figure 7 is a micrograph of the cut surface. As shown in Figure 7, it can be seen that a PP-FRP member 400 was formed in which a prepreg-derived composite layer 411 and a nonwoven fabric-derived composite layer 412 were laminated. It can be seen that polypropylene 411b that had infiltrated into nonwoven fabric 411a was continuously integrated.

[0077] [Experiment 4] A PP-FRP component was fabricated by embedding a 0.1 mm diameter heater wire between the first and second layers of a four-layer structure. Observation of the surface of the resulting PP-FRP component revealed a smooth surface with no irregularities due to the heater wire. A current of 3 V and 4.5 A was passed through the conductor of the resulting PP-FRP component, and electrical conduction was observed without any problems.

[0078] This international application claims priority based on Japanese Patent Application No. 2022-165725, filed on October 14, 2022, and the entire contents of Japanese Patent Application No. 2022-165725 are incorporated by reference into this international application.

[0079] REFERENCE SIGNS LIST 10 Nonwoven fabric 20 Polypropylene 30 Prepreg 31 to 36 Prepreg 40a, 40b Laminate 41 Laminate 42 to 43 Molded body 51 to 52 Textile 100 PP-FRP member 111 to 114 Composite layer 200 PP-FRP member 211 to 212 Composite layer 231 Conductive wire 300 PP-FRP member 311 to 312 Composite layer 331 Element D1 Male mold D2 Female mold M1, M2 Nozzle portion R1 to R4 Roller

Claims

1. It comprises a plurality of composite layers having a sheet-like textile and polypropylene infiltrated and fixed within the mesh of the textile, The plurality of composite layers are laminated, and the polypropylene is filled and integrated within the mesh of the textile, The polypropylene contains 5 wt% or more and 30 wt% or less of a tackifier, and the melting point of the polypropylene is 155°C or less, and it is a PP-FRP member characterized by this.

2. The PP-FRP member according to Claim 1, characterized in that the textile constituting any of the plurality of composite layers is also a non-woven fabric.

3. The PP-FRP member according to Claim 1, characterized in that one of the textiles constituting adjacent composite layers among the plurality of composite layers is a non-woven fabric and the other is a woven fabric.

4. The PP-FRP member according to any one of Claims 1 to 3, further comprising a conductive material provided between the textiles of the adjacent plurality of composite layers.

5. (Deleted)

6. (Deleted)

7. When heat-pressed at a temperature of 100°C or more and 150°C or less and a pressure of 2.5 MPa or less, which is equal to or higher than the softening point and equal to or lower than the melting point of the polypropylene, the rate of change in length before and after the heat pressing is 1% or less. The PP-FRP member according to any one of Claims 1 to 3, characterized by this.

8. A step of stacking a plurality of prepreg sheets having a non-woven fabric and polypropylene impregnated in the non-woven fabric to form a first laminate; A step of heat-pressing the first laminate at a temperature of 100°C or more and 150°C or less and a pressure of 1.5 MPa or more and 2.5 MPa or less, which is equal to or higher than the softening point and equal to or lower than the melting point of the polypropylene, and including this. The manufacturing method of the PP-FRP member is characterized in that the polypropylene contains 5 wt% or more and 30 wt% or less of a tackifier, and the melting point of the polypropylene is 155°C or less.

9. A step of alternately stacking a plurality of prepreg sheets having a woven fabric and polypropylene impregnated in the woven fabric and a sheet-like textile to form a second laminate; A step of thermally pressing the second laminate at a temperature of 100°C or more and 150°C or less and a pressure of 1.5 MPa or more and 2.5 MPa or less, which is equal to or higher than the softening point and equal to or lower than the melting point of the polypropylene; The manufacturing method of the PP-FRP member is characterized in that the polypropylene contains 5 wt% or more and 30 wt% or less of a tackifier, and the melting point of the polypropylene is 155°C or less.