JP2023059650A - FRP structural member and its manufacturing method - Google Patents

Abstract

To provide a plate-like FRP structural member that can be bent while simplifying the manufacturing process and its manufacturing method.SOLUTION: FRP structural member 1 has a base sheet 2 of fiber-reinforced resin composed of stretchable reinforcing fibers and stretchable matrix resin, and two plates 3 laminated to the base sheet 2 at a distance from each other. The portion where the two plates 3 are stacked on the base sheet 2 constitutes a highly rigid portion G, which is more rigid than the portion where the two plates are not stacked. The portion where the two plates 3 are not stacked is thinner than the portion where the two plates 3 are stacked and constitutes the hinge portion H, which is bendable.SELECTED DRAWING: Figure 1

Description

The present invention relates to a structural member containing fiber reinforced resin (FRP) and a manufacturing method thereof.

Japanese Patent Application Laid-Open Nos. 2019-214914 (Patent Document 1) and 2019-214915 (Patent Document 2) disclose two hard composite material portions made of reinforcing fibers and a first matrix resin, and in contact with these Disclosed is a board comprising a flexible composite material portion arranged in a vertical direction and comprising reinforcing fibers and a second matrix resin. In this plate material, the soft composite material portion is a bendable portion. This plate material can be folded.

JP 2019-214914 A JP 2019-214915 A

In the conventional technology described above, it is necessary to impregnate part of the reinforcing fibers with the first matrix resin and other parts with the second matrix resin in the manufacturing process. In this way, when the reinforcing fibers are impregnated with a plurality of types of matrix resins, the manufacturing process becomes complicated.

The present application discloses a plate-shaped FRP structural member that can be bent while simplifying the manufacturing process, and a manufacturing method thereof.

The FRP structural member (fiber reinforced resin structural member) in the embodiment of the present invention includes a fiber reinforced resin base sheet composed of stretchable reinforcing fibers and stretchable matrix resin, and laminated on the base sheet spaced apart from each other. and two plate members. A portion where the two plate members are laminated on the base sheet constitutes a high-rigidity portion having higher rigidity than a portion where the two plate members are not laminated. The portion where the two plate members are not laminated is thinner than the portion where the two plate members are laminated and forms a foldable hinge portion.

According to the present disclosure, a bendable plate-like FRP structural member and a method for manufacturing the same are provided while simplifying the manufacturing process.

FIG. 1 is a side view showing a configuration example of an FRP structural member in this embodiment. FIG. 2 is a side view showing a state in which the FRP structural member shown in FIG. 1 is folded. FIG. 3 is a side view showing a state in which the FRP structural member shown in FIG. 1 is folded. 4 is a top view of the FRP structural member shown in FIG. 1. FIG. FIG. 5 is a side view showing a modification of the FRP structural member in this embodiment. FIG. 6 is a side view showing a modification of the FRP structural member in this embodiment. FIG. 7 is a side view showing a modification of the FRP structural member in this embodiment. FIG. 8 is a side view showing a state in which the FRP structural member shown in FIG. 7 is folded. FIG. 9 is a diagram showing an example of the manufacturing process of the FRP structural member 1 shown in FIG.

The FRP structural member in the embodiment of the present invention comprises a fiber-reinforced resin base sheet composed of stretchable reinforcing fibers and a stretchable matrix resin, two plate members laminated on the base sheet with a space therebetween, Prepare. A portion where the two plate members are laminated on the base sheet constitutes a high-rigidity portion having higher rigidity than a portion where the two plate members are not laminated. The portion where the two plate members are not laminated is thinner than the portion where the two plate members are laminated and forms a foldable hinge portion.

In the above FRP structural member, the base sheet and two plate members laminated on the base sheet constitute a highly rigid portion, and the intermediate portion of the base sheet between the two plate members constitutes a foldable hinge portion. The FRP structural member can be bent at the hinge portion while maintaining its shape in the highly rigid portion. A base sheet is placed over both the rigid portion and the hinge portion. The base sheet is composed of stretchable reinforcing fibers and stretchable matrix resin. Furthermore, the hinge portion has a smaller thickness than the highly rigid portion. Therefore, the hinge portion can be bent, and the repulsive force when the hinge portion is bent is reduced. The FRP structural member having this configuration can be integrally formed by laminating at least two plate materials on the base sheet. Therefore, the manufacturing process can be simplified. In this way, it is possible to provide a bendable plate-like FRP structural member while simplifying the manufacturing process.

A stretchable reinforcing fiber means a reinforcing fiber that has an elongation to break of 5% or more in the tensile direction with respect to a tensile load due to the weaving or knitting method of the fiber or the stretchability of the fiber itself. The elongation of reinforcing fibers is measured according to the elongation measuring method defined by JIS for each fiber material. The elongation rate of general spun yarn is JIS L1095: 2010 9.5.1, the elongation rate of glass fiber is JIS R3420: 2013, the elongation rate of chemical fiber filament is JIS L1013: 2021 8.5, textiles and The elongation of the knitted fabric is measured according to the measurement method of JIS L1096:2010 8.14.1 A method or B method (A method is preferred).

A stretchable matrix resin is a matrix resin that is stretchable against tensile and compressive forces. The stretchable matrix resin means a matrix resin whose elongation to breakage of a cured product of the resin is equal to or higher than the elongation to breakage of the reinforcing fiber used.

The stretchable reinforcing fibers and stretchable matrix resin can bend against bending loads. Therefore, the hinge portion of the base sheet can be folded. The FRP structural member may be configured to be foldable so that the two high-rigidity portions are in contact with each other by bending at the hinge portion. The hinge portion may be foldable, for example along a fold line. The bending line of the hinge portion may be a line extending between two plate members in a direction not intersecting with any of the two plate members.

The reinforcing fibers of the base sheet may be formed, for example, of omnidirectional reinforcing fibers (eg mat), one or more layers of unidirectional reinforcing fibers, woven fabric (eg roving cloth), knitted fabric or net.

The tensile modulus of the hinge portion of the base sheet, on which no plate material is laminated, is preferably, for example, 1 GPa or less, more preferably 0.5 GPa or less, from the viewpoint of facilitating bending of the hinge portion. Moreover, from the viewpoint of suppressing breakage of reinforcing fibers due to bending, the elongation rate of the base sheet is preferably 3% or more, more preferably 5% or more, and even more preferably 7% or more. The tensile modulus and elongation of the hinge portion shall be measured in accordance with JIS K7164:2005. For the measurement of the tensile modulus and elongation of the hinge portion, a portion of the base sheet including the hinge portion is taken out and used as a test piece. When the base sheet is made of unidirectional fiber reinforced resin, the tensile modulus and elongation of the hinge portion shall be measured according to JIS K7165:2008.

From the viewpoint of ease of bending, the hinge portion of the base sheet, for example, the value of F in the following formula is preferably F ≤ 1.0 (N / mm) when θ is π (rad). It is more preferably ≦0.5 (N/mm), still more preferably F≦0.12 (N/mm), and still more preferably F≦0.06 (N/mm).
F=(E× ^t3 ×θ)/(12×w×D) (N/mm)
E: elastic modulus t: thickness of hinge portion w: width of hinge portion (circumferential length of bent portion)
θ: Bending angle of the plate D: Distance from the point of force to the bent portion is required, and the hinge width at that time is w. However, the portion of the hinge width w is based on the premise that all the corresponding portions of the hinge portion are ideally bent in an arc. Also, the hysteresis characteristics of the material are not considered. The inventor found that the bending properties of the FRP structural member in this embodiment are expressed by the above formula.

The matrix resin of the base sheet may include one type of matrix resin continuous with the high-rigidity portion and the hinge portion. This can further simplify the manufacturing process. In other words, the matrix resin of the base sheet may be formed of a matrix resin that is continuous with the high-rigidity portion and the hinge portion. In this case, the manufacturing process can be simplified as compared with a configuration in which different types of matrix resin are formed for the high-rigidity portion and the hinge portion.

The matrix resin of the base sheet may be a thermosetting resin. As a result, an FRP structural member with high strength can be obtained.

The matrix resin of the base sheet may be a thermosetting resin, and the two plate members may be laminated in contact with the matrix resin of the base sheet without an adhesive interposed therebetween.

As the thermosetting resin, for example, unsaturated polyester, vinyl ester (epoxy acrylate) resin, epoxy resin, phenol resin, diallyl phthalate resin, melamine resin, urea resin, thermosetting polyimide or polyurethane resin can be used. can.

The matrix resin of the base sheet may be a thermoplastic resin. Thermoplastic resins include polyphenylene sulfide, polysulfone, polyethersulfone, polyetheretherketone, thermoplastic polyimide, polyamideimide, amorphous polyarylate, polyamide, polyacetal, polycarbonate, polyester, polyolefin, ABS resin, or acrylic resin. can be exemplified.

The two plate members may be composed of a reinforcing material and a matrix resin, and the matrix resin of the two plate members may be formed continuously with the matrix resin of the base sheet. Thereby, the two plate materials and the base sheet can be laminated without using an adhesive. Since the matrix resin of the two plate materials and the matrix resin of the base sheet are integrally formed, the process can be shortened compared to the construction method using two or more kinds of matrix resins.

The same kind of resin may be used for the matrix resin of the plate material and the matrix resin of the base sheet. This can further simplify the manufacturing process. Note that the matrix resin of the plate material and the matrix resin of the base sheet do not necessarily have to be of the same type. For example, the tensile modulus of the matrix resin of the plate may be higher than the tensile modulus of the matrix resin of the base sheet.

Both the matrix resin of the plate material and the matrix resin of the base sheet may be thermosetting resins. As a result, an FRP structural member with high strength can be obtained.

In addition, the reinforcing material of the plate material may be a fiber or a plate-like core material. The plate material can be, for example, a metal plate such as punching metal, a wood plate such as a balsa plate, or a composite material of a plate of other materials and a matrix resin, in addition to the fiber-reinforced resin. Alternatively, the plate may not be a composite material.

The base sheet may be composed of at least two layers, and the two plate members may be arranged between the two layers of the base sheet. This makes it difficult for the plate material to separate from the base sheet and fall off. Furthermore, the plate material can be protected from the external environment. For example, even if wood that is relatively susceptible to decay is used as the plate material, the life of the material can be extended.

For example, the base sheet includes laminated first and second layers, wherein the plate material is laminated on the first layer of the base sheet, and the second layer is on the first layer. You may provide so that a board|plate material may be covered.

The reinforcing fibers of the base sheet may be organic fibers. Organic fibers often have a higher elongation rate than inorganic fibers, making it easier to bend the hinge portion. In addition, the fatigue strength of the reinforcing fiber increases against repeated bending of the hinge portion. Organic fibers are, for example, cellulose fibers, hemp fibers, aramid fibers, or nylon fibers. The organic fibers are fibers containing carbon (C) and oxygen (O) as constituent atoms.

By using, for example, 66 nylon fiber (polyamide 66) as the reinforcing fiber of the base sheet, fiber breakage due to bending is less likely to occur compared to glass fiber, and separation of the matrix resin and reinforcing fiber is less likely to occur than cellulose fiber. less likely to occur.

It is preferable that the reinforcing fibers of the base sheet are surface-treated to enhance adhesion with the matrix resin used. This makes it difficult for the reinforcing fibers and the matrix resin to separate from each other when the hinge portion is bent. Alternatively, a similar effect can be obtained by using a material having high adhesion to the matrix resin of the base sheet as the material of the reinforcing fibers of the base sheet.

For example, cellulose fibers that have not undergone surface treatment have high hydrophilicity, and therefore have low affinity with resins. Therefore, the cellulose fibers tend to be easily peeled off from the resin. On the other hand, like fiberglass, when a suitable sizing agent is applied to the surface, adhesion with the resin is improved. In the case of glass, the sizing agent often contains a silane coupling agent. If the fiber has improved adhesiveness to the resin by surface treatment, it is difficult for the fiber to separate from the resin.

By subjecting the surface of the cellulose fiber to an appropriate surface treatment, the affinity of the cellulose fiber with the resin can be improved. By using surface-treated cellulose fibers as the reinforcing fibers of the base sheet, the reinforcing fibers are less likely to separate from the matrix resin due to bending of the hinge portion.

In this way, by using a surface-treated fiber that enhances affinity with the matrix resin as the reinforcing fiber of the base sheet, or by using a fiber that has a high affinity with the matrix resin, the hinge portion is reinforced by bending. Peeling of fibers from the matrix resin can be suppressed. Surface treatments include, for example, surface treatments that impart hydrophobicity to the surface.

The base sheet may have a groove extending along the folding line on the surface of the hinge portion. Thereby, the curvature of the hinge portion can be restricted to be small. As a result, the reinforcing fibers are less likely to separate from the matrix resin due to excessive bending of the hinge portion.

At least one of the bend inner and outer surfaces of the hinge portion of the base sheet may be provided with grooves extending along the bend line. Further, a groove extending in a direction crossing the groove extending along the folding line may be further provided on the surface of the hinge portion of the base sheet.

A method for manufacturing an FRP structural member according to an embodiment of the present invention includes the steps of placing reinforcing fibers for a base sheet on a mold; The method includes a step of arranging materials at intervals, a step of impregnating the reinforcing fibers for the base sheet with a matrix resin material, and a step of curing the matrix resin material with which the reinforcing fibers for the base sheet are impregnated.

According to the manufacturing method described above, it is possible to provide a bendable plate-like FRP structural member while simplifying the manufacturing process. The step of impregnating the reinforcing fibers for the base sheet with the matrix resin material may be performed before or after the step of arranging the plate material on a partial region of the reinforcing fibers for the base sheet.

The manufacturing method further includes the step of further arranging a base sheet reinforcing fiber so as to cover the plate material with respect to the base sheet reinforcing fiber on which the two or more plate materials are arranged. You may As a result, it is possible to manufacture an FRP structural member in which a plate material is arranged between two layers of base sheets.

Hereinafter, FRP structural members according to embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and the description of those members will not be repeated. Also, the dimensions of the constituent members in each drawing do not faithfully represent the actual dimensions of the constituent members, the dimensional ratios of the respective constituent members, and the like.

FIG. 1 is a side view showing a configuration example of an FRP structural member in this embodiment. 2 and 3 are side views showing a state in which the FRP structural member shown in FIG. 1 is folded at the hinge portion. 4 is a top view of the FRP structural member shown in FIG. 1. FIG.

An FRP structural member 1 shown in FIG. 1 includes a base sheet 2 and two plate members 3 . The base sheet 2 is fiber reinforced resin (FRP). A portion where the plate material 3 is laminated on the base sheet 2 constitutes a high-rigidity portion G. As shown in FIG. A portion of the base sheet 2 where the plate material is not laminated constitutes a hinge portion H. As shown in FIG. The high-rigidity portion G has higher rigidity than the hinge portion H. The thickness t of the hinge portion H is smaller than the thickness tg of the high-rigidity portion G (t<tg). The hinge portion H is bendable.

The two plate members 3 are arranged apart from each other. A hinge portion H is provided between the two plate members 3 . That is, as shown in FIG. 4, the hinge portion H is arranged between two high-rigidity portions G separated from each other. The hinge portion H can be folded along the folding line C1. The bending line C1 of the hinge portion H extends between the two high-rigidity portions G (plate members 3) in a direction that does not intersect with these two high-rigidity portions G (plate members 3), that is, in the direction of the high-rigidity portions G. It is a line that extends in a non-tangent direction.

The base sheet 2 is formed continuously over both the high-rigidity portion G and the hinge portion H. The matrix resin of the base sheet 2 is formed of one type of matrix resin that is continuous with the high-rigidity portion G and the hinge portion H. As shown in FIG. The FRP of the base sheet 2 is composed of stretchable reinforcing fibers and stretchable matrix resin. This allows the hinge portion H to be bent. For example, as shown in FIG. 3, the hinge portion H is configured to be bendable up to a bending angle θ of 180 degrees (θ=π). In the FRP of the base sheet 2, the stretchability of the matrix resin is higher than that of the reinforcing fibers.

The rigidity of the high-rigidity portion G can be adjusted by the rigidity of the plate material 3 . For example, the material and thickness of the plate member 3 may be selected according to the rigidity required for the high rigidity portion G. In the FRP structural member 1, it is often preferable that the high-rigidity portion G has a high rigidity. For example, the high-rigidity portion G may have such rigidity that it cannot be bent by human force. The plate material 3 can be, for example, a composite material composed of a reinforcing material (core material) and a matrix resin. The elongation of the reinforcement of the plate 3 may be lower than the elongation of the reinforcement of the base sheet 2 .

It is preferable that the rigidity of the hinge portion H is low from the viewpoint of ease of bending. The rigidity of the hinge portion H can be adjusted by the thickness t of the hinge portion H (base sheet 2) and the width w of the hinge portion H in addition to the materials of the reinforcing fibers and the matrix resin.

Moreover, in order to realize 180-degree bending of the hinge portion H, the width w of the hinge portion H is preferably twice or more the thickness tg of the high-rigidity portion G (w≧2tg). Further, when the hinge portion H is bent, the hinge portion H bends in an arc, so it is preferable that W≧3.14tg.

In the example shown in FIG. 1, the base sheet 2 is composed of two layers of a first base sheet 2a and a second base sheet 2b. The plate material 3 is arranged between the layers of the first base sheet 2a and the second base sheet 2b. The first base sheet 2a includes a first fiber layer that is a layer of one or more reinforcing fibers. The second base sheet 2b includes a second fiber layer which is a layer of one or more reinforcing fibers. The plate material 3 is arranged between the first fiber layer and the second fiber layer. The matrix resin of the first base sheet 2a and the second base sheet 2b may be the same matrix resin. In this case, at the hinge portion H, the matrix resin of the first base sheet 2a and the matrix resin of the second base sheet 2b are continuously formed.

The matrix resin of the first base sheet 2a, the second base sheet 2b, and the plate member 3 may be integrated. That is, the reinforcing fibers of the base sheet 2 (the first fiber layer and the second fiber layer in the example of FIG. 1) and the reinforcing material of the plate material 3 may be bonded together by one type of continuous matrix resin. As a result, the entire FRP structural member 1 is integrated with one kind of matrix resin.

FIG. 5 is a side view showing a modification of the FRP structural member. In the example of FIG. 5, the base sheet 2 is one layer. Two plate members 3 are laminated on one layer of the base sheet 2 while being spaced apart from each other. No base sheet is laminated on the plate material 3 . Also in this case, a bendable plate-like FRP structural member can be obtained while simplifying the manufacturing process.

FIG. 6 is a side view showing another modification of the FRP structural member. In the example of FIG. 6, plate materials 3 are laminated on one side and the opposite side of the front and back surfaces of one-layer base sheet 2 . In the configuration of FIG. 5 , a base sheet may be further laminated so as to cover each plate material 3 laminated on the base sheet 2 . That is, the plate member 3 may be arranged between two layers of base sheets.

FIG. 7 is a side view showing another modification of the FRP structural member. FIG. 8 is a side view showing a state in which the hinge portion H of the FRP structural member shown in FIG. 7 is bent. In the example shown in FIG. 7, the base sheet 2 has grooves 2v on the surface of the hinge portion H. In the example shown in FIG. The groove 2v extends along the fold line of the hinge portion H. That is, unevenness is provided on the surface of the hinge portion H in a cross section perpendicular to the bending line. As a result, the curvature of the hinge portion H during bending becomes smaller than when there is no groove 2v. That is, the degree of bending of the hinge portion H at the time of bending is moderated by the groove 2v. As a result, the load on the hinge portion H due to bending is alleviated. In addition to the groove 2v on the surface of the hinge portion H, another groove extending in a direction intersecting (for example, a direction orthogonal to) the groove 2v may be further provided. Further, in the example shown in FIGS. 7 and 8, grooves 2v are provided on both the inner surface and the outer surface of the hinge portion H when bent. Alternatively, the groove 2v may be provided on one of the inner and outer surfaces of the hinge portion H, and the other surface may not be provided with the groove.

FIG. 9 is a diagram showing an example of the manufacturing process of the FRP structural member 1 shown in FIG. As shown in FIG. 9( a ), first, reinforcing fibers 20 a for the first base sheet 2 a are arranged in the mold 11 . As shown in FIG. 9(b), two or more reinforcing members 30 for the plate member 3 are spaced apart on the reinforcing fibers 20a. As shown in FIG. 9(c), reinforcing fibers 20b for the second base sheet 2b are arranged so as to cover the reinforcing material 30 arranged on the reinforcing fibers 20a. The reinforcing fibers 20b are arranged so as to cover the entire reinforcing fibers 20a. 9(a) to 9(c) show an example of the process of setting materials.

The reinforcing fibers 20a and the reinforcing fibers 20b can be, for example, one or more fiber layers. The fibrous layer may be, for example, a strand mat or a roving cloth. The reinforcing material 30 for the plate 3 is an example of the plate material. The reinforcement 30 can be, for example, a fiber layer or a board. Preferably, the reinforcing material 30 is less bendable than the reinforcing fibers 20a, 20b. Further, it is preferable that the reinforcing fibers 20a and 20b have higher stretchability than the reinforcing material 30, that is, have a higher elongation rate.

As shown in FIG. 9(d), the reinforcing fibers 20a and 20b and the reinforcing material 30 on the mold 11 are covered with the film 5 and sealed. A mold (upper mold) may be used instead of the film 5 . Thereby, the reinforcing fibers 20a and 20b and the reinforcing material 30 are housed in a closed space. A flow medium (resin flow medium) 4 may be inserted between the reinforcing fibers 20b and the film 5. FIG. For the flow medium 4, for example, a knit or mesh fabric is used. In addition to the flow medium 4, a breather, a peel ply (separating material), and other auxiliary materials may be inserted.

Also, in the space surrounded by the film 5 and the mold 11, a resin pipeline 6 for introducing resin and a vacuum pipeline 7 for vacuuming and decompressing the sealed space may be arranged. The resin pipeline 6 is connected to a resin tank (not shown). Resin is supplied to the resin pipeline 6 from a resin tank. The vacuum pipeline 7 is connected to a vacuum pump (not shown). The positions of the resin pipeline 6 and the vacuum pipeline 7 are not limited to the example shown in FIG.

The space surrounded by the mold 11 and the film 5 is evacuated while the reinforcing fibers 20a and 20b and the reinforcing material 30 are sealed. When this space reaches a predetermined vacuum pressure, the matrix resin material mixed with the curing agent is sucked into the space. As a result, the air around the reinforcing fibers 20a, 20b and the reinforcing material 30 is replaced with the matrix resin material (FIG. 9(e)). Thereby, the matrix resin material is shaped by suction (injection molding). The reinforcing fibers 20a, 20b and the reinforcing material 30 are impregnated with the matrix resin material.

The cast matrix resin material is allowed to cure. Curing may include heating the molded matrix resin material. In addition to curing by heat, curing by ultraviolet rays, visible rays, high frequencies, electromagnetic waves, radiation, or the like is also possible. By curing the molded matrix resin material, an FRP structural member including the base sheet 2 and the plate member 3 is formed. As a result, the base sheet 2 and the plate member 3 are integrated by the matrix resin. Therefore, the base sheet 2 and the plate member 3 can be joined together without using an adhesive or the like. As shown in FIG. 9(f), the film 5 and the like are removed, and the FRP structural member 1 is released.

The example shown in FIG. 9 is an example using a resin transfer molding method (RTM method). The manufacturing process of the FRP structural member is not limited to this. For example, a prepreg obtained by impregnating the reinforcing fibers 20 a and 20 b or the reinforcing material 30 with a resin may be laminated on the mold 11 . Further, for example, hand lay-up method, spray-up molding method, bag molding method, autoclave molding method, sheet molding compound (SMC) molding method, bulk molding compound (BMC) molding method, and other manufacturing methods are used to produce FRP structural members. can be manufactured.

(Experimental Example 1) (Measurement of required bending force)
The force (F×L) required to bend the hinge portion H of the FRP structural member having the configuration shown in FIGS. 1 to 4 was measured. where L is the depth or dimension (mm) of the FRP structural member in the direction of the folding line C1. F is the force per mm of depth. As shown in FIG. 3, the curvature radius r was measured when θ=π[rad]=180°, and the width w of the hinge portion H was set to w=rθ. The distance in the direction perpendicular to the bending line C1 from the end K of the hinge portion H to the force measurement point was defined as D (mm). That is, the load was measured with a force gauge at the position of the distance D (mm) from the K point. Measurements were taken for each of the base sheets 2a and 2b with one fiber layer (1PLY) and two fiber layers (2PLY). The measurement was performed by changing the matrix resin in a two-layer configuration of the fiber layer. Table 1 below shows the measurement results. The fiber layers of the base sheets 2a and 2b were 66 nylon roving cloth. The composition of the matrix resin A is 100% flexible resin. The composition of the matrix resin B is 75% soft resin and 25% hard resin. The physical properties of the matrix resin A are a tensile strength of 6.6 MPa, a tensile modulus of 14 MPa, an elongation of 170% according to JISK7113, a hardness of 52 according to JISK7215, and a water absorption of 1.02% by weight according to JISK6919. is. The matrix resin B casting board is harder than the matrix resin A casting board. The tensile modulus E was measured by a tensile test (based on JISL7164:2005) of FRP having the same configuration as the base sheets 2a and 2b used in the experiment.

The theoretical value of F×L in Table 1 above was calculated by the following formula.
F×L={(E×t ³ ×θ)/(12×w×D)}×L

From the results in Table 1 above, it was found that the above formula is generally close to the measured values. The reason why the measured values are smaller than the theoretical values is considered to be that the force that presses the force gauge is reduced by the weight of the FRP structural member. It was found that when the F-number is around 0.05, the hinge portion is easily bent, and when it is less than that, it is easily bent by a person. Also, it is easy to bend at F=0.12, but a certain amount of force is required. Further, it was found that by configuring the base sheet to have a tensile modulus of 1.0 GPa or less, preferably 0.5 GPa or less, a foldable FRP structural member of a practical size can be easily realized. .

(Experimental Example 2) (Characteristic evaluation when using various reinforcing fibers)
By changing the reinforcing fiber of the base sheet, an FRP structural member having the structure shown in FIG. 1 was produced, and its properties were evaluated. Properties were evaluated when cellulose, glass, cloth (commercially available cloth), and 66 nylon were used as reinforcing fibers for the base sheet. Cellulose was evaluated both when grooves (unevennesses) were not provided on the surface of the base sheet (configuration in FIG. 1) and when grooves were provided (configuration in FIG. 5). For glass, both cloth woven with a stretchable weave (knitted weave) and non-stretchable glass fibers were evaluated. Evaluation items were ease of bending, separation of fibers and resin due to bending, fiber breakage due to bending, and resin cracking due to bending. Ease of bending was qualitatively evaluated when bent so that θ was 180°. With respect to fiber peeling, fiber determination, and resin cracking, it was examined whether or not these occurred after bending at θ=180° was repeated several tens of times. Table 2 below shows the evaluation results. In Table 2, plate thickness indicates the thickness of the hinge portion H.

From the results shown in Table 2, when non-stretchable glass fiber is used as the reinforcing fiber of the base sheet, it is difficult to bend at the hinge part even when compared with the case of using cloth reinforcing fiber with the same thickness. It was found that Fiber breakage and resin cracking occurred when stretchable woven glass fibers were used.

When organic fibers such as cellulose, cloth, and 66 nylon were used as the reinforcing fibers of the base sheet, it was easy to bend and no fiber breakage occurred. Therefore, it is considered preferable to use organic fibers for the reinforcing fibers of the base sheet. Also, even when flax was used, bending was difficult when the plate thickness was 4.5 mm. From this, it is considered preferable that the plate thickness of the hinge portion H is less than 4.5 mm from the viewpoint of ease of bending.

Further, it has been found that by providing unevenness (grooves) on the surface of the base sheet, the curvature of the hinge portion can be restricted to a small value, and separation between the fibers and the resin can be prevented. In addition, when unevenness was provided on the surface of the base sheet, the resin cracked at the recessed portion of the groove.

When glass fiber and 66 nylon were used as the reinforcing fibers of the base sheet, no peeling occurred between the reinforcing fibers and the matrix resin. Since the glass is surface-treated with a sizing agent containing a silane coupling agent, it is considered to have high adhesiveness. On the other hand, 66 nylon is a petroleum-derived material, and is presumed to have a higher affinity with resins than cellulose or the like. From this, it is considered that separation of the reinforcing fibers from the matrix resin during bending can be suppressed by surface-treating the reinforcing fibers to increase affinity with the matrix resin.

It was found that by using nylon 66 as the reinforcing fibers of the base sheet, it is possible to obtain an FRP structural member that is somewhat bendable and is resistant to peeling and breakage of the reinforcing fibers and cracking of the matrix resin due to bending.

In one FRP structural member, the number of plate members laminated on the base sheet is not limited to two, and may be three or more. That is, one FRP structural member may be provided with three or more rigid portions. Also, the base sheet may be laminated in two or more layers. The plate material may also be laminated in two or more layers.

The FRP that constitutes the base sheet or plate may contain a filler. The filler is not particularly limited, but examples thereof include calcium carbonate, aluminum hydroxide, magnesium oxide, magnesium hydroxide, alumina, talc, glass flakes, clay, and the like.

Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the scope of the invention.

1: FRP structural member, 2: base sheet, 3: plate material

Claims (9)

a fiber-reinforced resin base sheet composed of stretchable reinforcing fibers and stretchable matrix resin;
and two plate members laminated on the base sheet spaced apart from each other,
The portion where the two plate materials are laminated on the base sheet constitutes a high-rigidity portion having higher rigidity than the portion where the two plate materials are not laminated,
The FRP structural member, wherein the portion where the two plate members are not laminated is thinner than the portion where the two plate members are laminated and forms a foldable hinge portion. The FRP structural member according to claim 1,
The FRP structural member, wherein the matrix resin of the base sheet includes one type of matrix resin continuous with the high-rigidity portion and the hinge portion. 3. The FRP structural member according to claim 1, wherein the matrix resin of said base sheet is a thermosetting resin. The FRP structural member according to any one of claims 1 to 3,
The FRP structural member, wherein the two plate members are composed of a reinforcing material and a matrix resin, and the matrix resin of the two plate members is formed continuously with the matrix resin of the base sheet. The FRP structural member according to any one of claims 1 to 4,
The FRP structural member, wherein the base sheet is composed of at least two layers, and the two plate materials are arranged between the two layers of the base sheet. The FRP structural member according to any one of claims 1 to 5,
The FRP structural member, wherein the reinforcing fibers of the base sheet are organic fibers. The FRP structural member according to any one of claims 1 to 6,
The FRP structural member, wherein the reinforcing fibers of the base sheet are surface-treated to enhance adhesion of the base sheet to the matrix resin. The FRP structural member according to any one of claims 1 to 7, wherein the base sheet has grooves extending along the folding lines on the surface of the hinge portion. A method for manufacturing an FRP structural member, comprising:
placing reinforcing fibers for the base sheet on the mold;
a step of arranging two or more plate materials in a partial area of the base sheet reinforcing fibers;
a step of impregnating the reinforcing fibers for the base sheet with a matrix resin material;
and curing the matrix resin material impregnated into the reinforcing fibers for the base sheet.

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