PP-FRP member and method for manufacturing the same

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

Technical Field

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

Background Art

[0002] Conventionally, as a resin decoration molding technique, a method of infiltrating a resin into fibers to produce a member is known (for example, Patent Documents 1 and 2). In this case, for example, PVB (polyvinyl butyral) or the like is used as the resin to be infiltrated. A member in which the resin and the fiber layer are integrated has sufficient strength. In such a member, the base resin layer to be injection-molded is also fixed while infiltrating into the gaps between the fibers of the non-woven fabric layer.

[0003] In the housing described in Patent Document 1, the non-woven fabric layer is adhered to the decorative layer via an adhesive resin layer. For the adhesive resin layer, PVB (polyvinyl butyral) having a viscosity such that air bubbles in the adhesive resin layer can escape by softening, for example, is used. Patent Document 1 also discloses that polypropylene is used as an example of the material of the base resin layer constituting the housing, and that the adhesive resin layer incorporates a conducting wire.

[0004] Patent Document 2 discloses a veneer sheet and its application products in which a non-woven fabric mainly composed of fibers capable of maintaining its shape at a temperature higher than the melting point of the resin film is interposed between the back surface of the veneer and the resin film, and the resin film is configured like FRP. Examples of the non-woven fabric include PET fibers, and examples of the resin film include a propylene film. In the veneer sheet described in Patent Document 2, the non-woven fabric and the base resin are firmly joined by exerting an anchor effect between them.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[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 this invention have been working on creating integrated laminates using only polypropylene as the resin impregnated into the fibers of nonwoven fabric. However, it is common knowledge in the molding field that even when multiple sheets made of polypropylene are stacked and heat-pressed together, the sheet-derived layers peel off from the product, making it impossible to firmly integrate the entire material as a polypropylene-only component.

[0007] Patent document 2 cites propylene film as an example of a resin film. However, impregnating nonwoven fabric with resin is done to fix the veneer sheet to the veneer, and only a single layer for fixing is formed. Therefore, such veneer sheets are difficult to use as FRP members that require shape stability and strength in relation to the design, such as in automobile bodies.

[0008] This invention has been made in view of these 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. [Means for solving the problem]

[0009] (1) In order to achieve the above objective, the present invention employs the following means. Specifically, the PP-FRP member of the present invention comprises a plurality of composite layers having a sheet-like textile and polypropylene impregnated and fixed into the mesh of the textile, wherein the plurality of composite layers are laminated, adjacent textiles are in contact with each other, and the polypropylene is filled into the mesh of the textile and integrated. As a result, the laminated composite layers are integrated with each other, and a high-strength PP-FRP member with excellent shape stability is obtained.

[0010] (2) Furthermore, the PP-FRP member described in (1) above is characterized in that the textile constituting any of the multiple composite layers is a nonwoven fabric. This makes it possible to easily form the member by layering a prepreg, which is a nonwoven fabric impregnated with polypropylene, and pressing it.

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

[0012] (4) Furthermore, the PP-FRP member described in any of (1) to (3) above is characterized by further comprising a conductive material provided between the adjacent composite layers of textiles. This allows for various functions to be obtained through the conductive material.

[0013] (5) Furthermore, in the PP-FRP member described in any of (1) to (4) above, the melting point of the polypropylene is 160°C or lower. This makes it possible to process at low temperatures, and the PP-FRP member can be used, for example, for surface decoration.

[0014] (6) Furthermore, in the PP-FRP member described in any of (1) to (5) above, the polypropylene is characterized in that it contains 5 wt% to 30 wt% of tackifier. This allows the prepreg to be easily prepared by hot melt.

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

[0016] (8) Furthermore, the present invention provides a method for manufacturing a PP-FRP member, comprising the steps of: stacking a plurality of prepreg sheets having a nonwoven fabric and polypropylene impregnated in the nonwoven fabric to form a first superimposed body; and hot-pressing the first superimposed body at a predetermined temperature and a predetermined pressure. This makes it possible to manufacture a plastic member that is low cost, has excellent chemical resistance, is dense and has high strength.

[0017] (9) Furthermore, the present invention provides a method for manufacturing a PP-FRP member, characterized by including the steps of: alternately layering a plurality of prepreg sheets having a woven fabric and polypropylene impregnated in the woven fabric with a sheet-like textile to form a second superimposed body; and hot-pressing the second superimposed body at a predetermined temperature and a predetermined pressure. This makes it possible to manufacture a plastic member that is low cost, has excellent chemical resistance, is dense and has high strength. Furthermore, shape stability can also be improved.

[0018] (10) Furthermore, in the method for manufacturing the PP-FRP member described in (8) or (9) above, the predetermined temperature is 100°C or more and 150°C or less, and the predetermined pressure is 1.5 MPa or more and 2.5 MPa or less. This allows the laminated composite layers to be integrated, resulting in a high-strength PP-FRP member with excellent shape stability. [Brief explanation of the drawing]

[0019] [Figure 1] It is a cross-sectional view showing a PP-FRP member. [Figure 2] (a) to (c) are cross-sectional views showing the steps of prepreg production respectively. [Figure 3] It is a perspective view showing the step of laminating prepregs and thermocompression bonding them. [Figure 4] (a) to (d) 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 a PP-FRP member in which a conducting wire and an element are embedded respectively. [Figure 7] It is a micrograph of a cut surface.

Mode for Carrying Out the Invention

[0020] The inventors of the present invention repeated trials and errors, and produced a PP-FRP member by laminating prepregs obtained by infiltrating and fixing polypropylene to a sheet-like non-woven fabric and joining them by thermocompression bonding, thus arriving at the present invention. By making the polypropylene infiltrated and fixed in the mesh of the non-woven fabric continuous in a plurality of 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 form shown in FIG. 1 is an example, and the PP-FRP member 100 is composed of composite layers 111 to 114. The composite layers 111 to 114 are laminated, and each of the composite layers 111 to 114 is formed of a textile and polypropylene infiltrated and fixed in the mesh of the textile.

[0022] In composite layers 111-114, polypropylene is continuously present across layers and permeates into the mesh of the textile. Due to the anchoring effect of the permeated polypropylene, 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.

[0023] The polypropylene preferably contains 5 wt% to 30 wt% of a tackifier. The tackifier is a tackifying resin, and for example, a petroleum-based one is used. This facilitates the preparation of the prepreg by hot melting.

[0024] High-melting-point polypropylene can be used. Such high-melting-point polypropylene is a high-shrinkage type material and can be used as a component for products requiring a high modulus of elasticity. For example, high-melting-point polypropylene with a melting point of 150°C or higher is preferred. Such high-melting-point polypropylene is preferably composed of 85 wt% to 95 wt% of polypropylene and 5 wt% to 15 wt% of tackifier.

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

[0026] The melting point of polypropylene is preferably at least 160°C or lower. This allows for processing at lower temperatures and enables joining with materials having different melting points. For example, a material with a surface decoration made of polypropylene with a high melting point can be formed, and this material can be joined to a PP-FRP material.

[0027] The textiles contained in each of the composite layers 111 to 114 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 containing polyester or felt. The textile has a basis weight of 20 g / m². 2 More than 300g / m 2 The following can be used.

[0028] Polypropylene nonwoven fabric can also be used as the nonwoven material. Polypropylene nonwoven fabric has a high bulkiness. For example, 20 g / m² 2 More than 70g / m 2 When using the following polypropylene nonwoven fabrics, the high porosity makes it easy for the softened polypropylene to impregnate the fabric during the hot-melt process. In this case, there is also a cost advantage in that a composite layer of the same thickness can be formed with fewer nonwoven fabrics. Furthermore, the composite layer formed by impregnating polypropylene nonwoven fabric with polypropylene does not require separation of the materials during recycling.

[0029] Polyethylene-reinforced fiber woven fabric can also be used for the woven material. When using polyester nonwoven fabric, the weight is 30 g / m². 2 More than 250g / m 2 The following is preferable. 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 are also acceptable. A four-layer or more structure improves the strength and stability of the PP-FRP member 100. On the other hand, a structure with fewer than four layers makes molding easier.

[0031] [Manufacturing method for PP-FRP members] A method for manufacturing the PP-FRP member 100 configured as described above will now be explained. The PP-FRP member 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.

[0032] 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 polypropylene 20, which has been heated to a temperature above its softening point and softened, is applied on top of it, impregnated, and fixed 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.

[0033] 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 polypropylene 20 can be applied to the nonwoven fabric 10 by fixing the nonwoven fabric 10 and moving the spray-type nozzle M1 over the entire nonwoven fabric 10 to produce a prepreg 30.

[0034] 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, polypropylene 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.

[0035] The example 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 the position between rolls R3 and R4. The nonwoven fabric 10, which is fed out sandwiched between rolls R3 and R4, is impregnated with polypropylene 20. The production efficiency of prepreg 30 can be improved by using such a continuous impregnation apparatus.

[0036] The heated and softened polypropylene may be collected in a container, and sheet-like textiles may be immersed in the container (a method known as "dip immersion"). The polypropylene 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, passing it through the polypropylene.

[0037] 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.

[0038] 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.

[0039] Heat pressing is preferably performed using a hydraulic heat press or a multi-stage press at a predetermined temperature and pressure. The predetermined temperature is between the melting point and the softening point of polypropylene. For example, heating to 140°C to 160°C is preferable. The predetermined pressure is preferably between 1.5 MPa and 2.5 MPa. This allows the polypropylene to penetrate and adhere to the mesh within the textile, creating an anchoring effect and firmly integrating the components.

[0040] In this way, by heat-pressing the prepreg at a temperature higher than the softening point of polypropylene but lower than its melting point, the polypropylene that has permeated into the mesh becomes continuously integrated and firmly fixed to the mesh by the anchoring effect. As a result, a sheet of PP-FRP member 100 is produced as a laminated sheet in which multiple nonwoven fabrics are firmly bonded together by the polypropylene that has permeated throughout.

[0041] The PP-FRP member 100 exhibits excellent shape stability; when hot-pressed at a temperature between 100°C and 150°C and a pressure of 2.5 MPa or less, the absolute value of the change in length before and after pressing is 1% or less. Thus, the PP-FRP member is less prone to dimensional changes before and after pressing. Therefore, the PP-FRP member can be formed according to the design, and its application becomes easier.

[0042] The PP-FRP member 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 heat press 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 PP-FRP members can be formed simultaneously by sandwiching the material between multiple stages and applying pressure with a press while heating.

[0043] PP-FRP components have high strength because they have a composite layer structure in which polypropylene is impregnated and fixed within the textile. This makes them suitable for use in lightweight yet strong components such as automobile bodies.

[0044] The PP-FRP member 100 sheet obtained in the above process is 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.

[0045] 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 PP-FRP member 100 has excellent shape stability. The obtained PP-FRP member 100 can be further machined as appropriate depending on the application. The PP-FRP member 100 can be applied to various products using polypropylene as the surface material.

[0046] [Second Embodiment] 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.

[0047] In this case as well, the prepreg and textile are heat-pressed together at a temperature higher than the softening point but lower than the melting point of polypropylene. This allows the polypropylene in the prepreg to penetrate into the mesh of the textile, and the anchoring effect firmly fixes it to the mesh. As a result, the PP-FRP member 100 sheet is produced as a laminated sheet in which the prepreg and textile are joined by the polypropylene that has continuously permeated through penetration.

[0048] [Third Embodiment] [Configuration of PP-FRP components for embedded circuit components] A conductive material can be embedded in the main body layer of the PP-FRP member 100 described above. Figures 6(a) and 6(b) are cross-sectional views showing PP-FRP members 200 and 300, respectively, with a conductor and an element embedded in the main body layer. The PP-FRP member 200 is basically constructed in the same way as the PP-FRP member 100, but has the embedding of a conductor 231 and related features.

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

[0050] In the example shown in Figure 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 power supply or control of each device. Since the PP-FRP member 200 is formed by heat-pressing with the conductor 231 in between, a semicircular depression corresponding to the cross-sectional shape of the conductor is created in the composite layer 212 that is pressed by the conductor 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 conductive material of the conductor 231 is exposed without an insulating coating.

[0051] In the example above, the conductor 231 is provided between the nonwoven fabrics within the composite layer, but if the nonwoven and woven fabrics are arranged alternately, it may be provided between the nonwoven and woven fabrics. In other words, the conductor 231 only needs to be embedded within the multiple layer structures that make up the PP-FRP member 200, and in that case, it may be embedded between any of the layers.

[0052] On the other hand, the PP-FRP member 300 is basically constructed in the same way as the PP-FRP member 200, but the element 331 embedded in the PP-FRP member 300 and related characteristics are different. In the example shown in Figure 6(b), a flat cross-section element 331 is provided as the element 331 between the composite layer 311 and the composite layer 312. During the manufacturing process, the composite layer 312, which is pressed by the element 331, has a flat recess corresponding to the cross-sectional shape of the element.

[0053] The manufacturing process for PP-FRP members 200 and 300 is the same as that for PP-FRP member 100. The only difference is that when arranging the prepreg and textile, a conductive wire 231 or element 331 is placed between them.

[0054] [Large components and enclosures] PP-FRP components can be used as large, high-strength components and enclosures, such as in automobile bodies, bumpers, and housing equipment. PP-FRP components offer excellent shape stability; their dimensions do not change due to shrinkage after the heat-sealing process, making them a viable alternative to steel products for manufacturing large components according to design specifications. By decorating the surface of the PP-FRP component with polyester nonwoven or woven fabric as a base coat, and then converting the surface to PET resin, painting becomes possible. This allows for application 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.

[0055] [Wire harness] PP-FRP components with embedded wires for supplying power to equipment and for transmitting 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 PP-FRP components.

[0056] [toilet seat] A PP-FRP material with embedded heater wires as a conductor can also be used for the toilet seat. This toilet seat is a so-called heated toilet seat, and by passing an electric current through the heater wires, the surface temperature can be maintained at around 40°C. The material of the heater wires is not particularly limited. A heated toilet seat can be realized with a surface formed of polypropylene, which has excellent resistance to hydrochloric acid. Placing the heater wires directly beneath the composite layer of the surface makes it easier to conduct heat to the surface, improving thermal efficiency. Alternatively, a PP-FRP material can be used for the toilet seat without embedding heater wires. In that case, it is preferable to use a surface material that has been processed to have a pleasant texture, such as a napped surface.

[0057] [Backer] PP-FRP components 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 and nonwoven fabric. In this case, PVB resin is used as an adhesive to bond the resin film and nonwoven fabric. Furthermore, ABS resin, PP, PC, PMMA, or other resins may be injection molded onto the back surface as the base resin. Thus, as a lightweight intermediate processing material with a low processing temperature of, for example, around 120-150°C, it can be applied to a variety of uses.

[0058] [Experiment 1] A prepreg was prepared by heating and softening hot-melt polypropylene (HMPP) with added tackifier, and then applying the softened polypropylene to a nonwoven fabric made of spunbond polyester. Toray Industries, Inc.'s nonwoven fabric N2070-6S was used. A prepreg using low-melting-point (95°C) hot-melt polypropylene (PP 80 wt%, tackifier 20 wt%) was conveniently referred to as "Prepreg 2". The materials were layered using the obtained prepregs in the following combinations.

[0059] [Table 1]

[0060] Black nonwoven fabric is denser and harder than regular nonwoven fabric. Toray Industries, Inc.'s nonwoven fabric G2200-BKO was used as the black nonwoven fabric. Coarse white nonwoven fabric is less dense than regular nonwoven fabric. Toray Industries, Inc.'s nonwoven fabric D5100 was used as the coarse white nonwoven fabric.

[0061] On the surface of the layered material sample, a square with sides of approximately 100 mm was drawn using a 0.5 mm tip felt-tip pen. The length of each side was measured twice, and the results were averaged. The lengths were measured to the nearest 0.01 mm using a digital caliper (the same procedure was followed for subsequent measurements). The samples were heat-pressed using a hydraulic heat press for 1 minute. During the heat-pressing of laminated sample 3, a 15 mm spacer was inserted to prevent the sample from becoming too flat and crushed, deviating from the purpose of the press.

[0062] After heat-sealing, the length of each side of the square was measured twice and averaged. All of the laminated samples 1-3 obtained as PP-FRP members showed a change in square length of less than 1%. The measurement results are shown in the table below.

[0063] [Table 2]

[0064] Next, a prepreg made of high-melting-point (155°C) hot-melt polypropylene (PP 90 wt%, tackifier 10 wt%) and a prepreg made of low-melting-point (95°C) hot-melt polypropylene were laminated, and the sample, with both ends sandwiched in nonwoven fabric, was heat-pressed. For convenience, the prepreg made of high-melting-point (155°C) hot-melt polypropylene will be referred to as "Prepreg 1". The materials were layered in the following combinations.

[0065] [Table 3]

[0066] A square with sides of approximately 100 mm was drawn on the surface of the layered material sample using a marker pen, and the length of each side was measured twice and averaged. The samples were then heat-pressed using a hydraulic heat press for 1 minute. After heat-pressing, the length of each side of the square was measured twice and averaged. The resulting laminated samples 4 and 5, obtained as PP-FRP members, both showed a change in the square length of less than 1%. The measurement results are shown in the table below.

[0067] [Table 4]

[0068] Next, samples made by laminating a prepreg using high-melting-point (155°C) hot-melt polypropylene with a nonwoven fabric were heat-pressed together. The materials were layered in the following combinations.

[0069] [Table 5]

[0070] A square with sides of approximately 100 mm was drawn on the surface of the layered material sample using a marker pen, and the length of each side was measured twice and averaged. The samples were then heat-pressed using a hydraulic heat press for 1 minute. After heat-pressing, the length of each side of the square was measured twice and averaged. The resulting laminated samples 6 and 7, obtained as PP-FRP members, both showed a change in the square length of less than 1%. The measurement results are shown in the table below.

[0071] [Table 6]

[0072] As described above, the length change rate before and after thermocompression bonding was 1% or less for all laminated samples, demonstrating extremely excellent dimensional stability. In particular, when prepregs using low-melting-point hot-melt polypropylene were laminated and thermocompression bonded at a relatively low temperature of 120°C or less, the change rate was 0.4% or less. These results show that not only is the dimensional stability of PP-FRP members excellent during manufacturing, but the PP-FRP members after manufacturing also exhibit extremely excellent dimensional stability, with a change rate of 1% or less even when hot-pressed at temperatures between 100°C and 150°C and pressures 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 heat treatment, a square with sides of approximately 100 mm was drawn on the surface of the sample with a marker pen, and the length of each side was measured twice and averaged. After heat treatment, the length of each side of the square was measured twice, averaged, and the rate of change was calculated.

[0074] [Table 7]

[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. In these cases, the rate of change exceeded 1%, indicating that sufficient dimensional stability cannot be obtained even when polypropylene films are compressed to create laminates.

[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 is formed by laminating a composite layer 411 derived from the prepreg and a composite layer 412 derived from the nonwoven fabric. It can be seen that the polypropylene 411b that has permeated into the nonwoven fabric 411a is continuously integrated.

[0077] [Experiment 4] A PP-FRP member 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 member revealed that it was smooth with no irregularities originating from the heater wire. When a 3V, 4.5A current was passed through the resulting PP-FRP member, it conducted without any problems.

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

[0079] 10 Nonwoven fabric 20 Polypropylene 30 prepregs 31-36 Prepreg 40a, 40b Superimposed 41 Laminate 42-43 Molded body 51-52 Textiles 100 PP-FRP components 111~114 Composite layer 200 PP-FRP components 211~212 Composite layer 231 Conductor 300 PP-FRP components 311~312 Composite layer 331 elements D1 Male mold D2 Female mold M1, M2 nozzle section R1~R4 Rollers

Claims

1. The invention comprises a sheet-like textile and a plurality of composite layers having polypropylene impregnated and fixed within the mesh of the textile, The aforementioned multiple composite layers are laminated, and the polypropylene is filled and integrated within the mesh of the textile. The PP-FRP member is characterized in that the polypropylene contains 5 wt% to 30 wt% of tackifier, and the melting point of the polypropylene is 155°C or lower.

2. The PP-FRP member according to claim 1, characterized in that the textile constituting any of the plurality of composite layers is a nonwoven 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 nonwoven 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 adjacent plurality of composite layers of the textile.

5. (delete)

6. (delete)

7. The PP-FRP member according to any one of claims 1 to 3, characterized in that when the polypropylene is hot-pressed at a temperature between its softening point and melting point, between 100°C and 150°C, and at a pressure of 2.5 MPa or less, the rate of change in length before and after the hot-pressing is 1% or less.

8. A step of stacking a plurality of prepreg sheets having a nonwoven fabric and polypropylene impregnated in the nonwoven fabric to form a first superimposed body, The process includes a step of hot-pressing the first superimposed material at a temperature of 100°C to 150°C, which is above the softening point and below the melting point of the polypropylene, and at a pressure of 1.5 MPa to 2.5 MPa. A method for producing a PP-FRP member, characterized in that the polypropylene contains 5 wt% to 30 wt% of tackifier, and the melting point of the polypropylene is 155°C or lower.

9. A step of forming a second layered body by alternately layering a plurality of prepreg sheets having a woven fabric and polypropylene impregnated in the woven fabric, and a sheet-like textile, The process includes a step of hot-pressing the second superimposed material at a temperature of 100°C to 150°C, which is above the softening point and below the melting point of the polypropylene, and at a pressure of 1.5 MPa to 2.5 MPa. A method for producing a PP-FRP member, characterized in that the polypropylene contains 5 wt% to 30 wt% of tackifier, and the melting point of the polypropylene is 155°C or lower.

Images