Method for producing preformed fiber-reinforced sheet, preformed fiber-reinforced sheet, and semi-cured fiber-reinforced sheet

Abstract

To provide a method for producing a preformed fiber-reinforced sheet for use in reinforcing a structure by bonding it to a bent portion such as a corner of the structure with an adhesive, which can be economically produced in small quantities and in a wide variety of types in a shape having a curvature that fits the bent portion such as the corner of the structure, by using a manufacturing device with good workability and simple configuration, and with a small capital investment, the preformed fiber-reinforced sheet, and semi-curd fiber-reinforced sheet.SOLUTION: In a method for producing a preformed fiber-reinforced sheet for use in reinforcing a structure by bonding it to a bent portion such as a corner of the structure with an adhesive, semi-cured fiber reinforced plastic strands 2a in which matrix resin R is in a B-stage state are aligned in a longitudinal direction in a curtain-like shape to form a sheet, and the semi-cured fiber reinforced sheet 1a in a B-stage state is clamped by heating and shaping means 201 and bent to a predetermined curvature while being heated, and then the preformed semi-cured fiber reinforced sheet is further heated to be completely cured.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a fiber-reinforced sheet (hereinafter referred to as a "shaped fiber-reinforced sheet") that has been pre-bent for use in repairing and reinforcing (hereinafter simply referred to as "reinforcing") civil engineering and construction structures such as concrete structures or steel structures, as well as wooden structures, plastic structures, or composite structures of these (in this specification, concrete structures, steel structures, wooden structures, plastic structures, and composite structures of these are collectively referred to as "structures"), in particular when reinforcing structures by adhering the sheet to bent parts such as corners of the structures with an adhesive, a manufacturing method for the shaped fiber-reinforced sheet, and a semi-hardened fiber-reinforced sheet. [Background technology]

[0002] In recent years, methods for reinforcing existing or newly constructed structures include continuous fiber sheet bonding methods such as a carbon fiber sheet bonding method and an aramid fiber sheet bonding method, in which a reinforcing fiber sheet such as a carbon fiber sheet or an aramid fiber sheet is attached to or wrapped around the surface of the structure, and a method in which a sheet in which a continuous fiber bundle is impregnated with an uncured matrix resin is bonded and then cured.

[0003] Furthermore, in order to eliminate the need for on-site resin impregnation, an FRP plate adhesive reinforcement method has been developed in which factory-produced FRP plates approximately 1 to 2 mm thick and 5 cm wide are adhered to the concrete surface using a putty-like adhesive resin.

[0004] However, the above-mentioned continuous fiber sheet bonding method has the disadvantage that it is time-consuming to impregnate the reinforcing fiber bundles with the matrix resin, as the continuous fiber sheet is impregnated with the matrix resin (impregnating adhesive) at the construction site and then bonded to the reinforcing structure, and that it is prone to quality defects during on-site construction, such as poor impregnation of the matrix resin, swelling of the continuous fiber sheet, and floating.

[0005] Furthermore, the method of adhering and curing a sheet in which uncured matrix resin is impregnated into a continuous fiber bundle has the disadvantage that the resin-impregnated continuous fiber sheet is not breathable, making it difficult for air to escape between the sheets at the adhesive surface, and therefore prone to quality defects during on-site construction such as swelling and floating of the continuous fiber sheet.

[0006] Furthermore, the FRP plate adhesive reinforcement method, in which an FRP plate with a thickness of 1 to 2 mm and a width of approximately 5 cm is adhered to the surface of concrete using a putty-like adhesive resin, has the disadvantage that the FRP plate, which is thicker than the continuous fiber sheet with a thickness of approximately 0.1 mm to 0.5 mm, is partially adhered in a strip-like shape, resulting in an extremely small adhesive area compared to the continuous fiber sheet adhesive method, and peeling is likely to occur at the edges due to the concentration of bond shear stress acting on the adhesive interface.In addition, the plate width is small, making it difficult to cover and adhere the entire surface of a structure, making it difficult to apply to surface components such as deck slabs.

[0007] Therefore, Patent Document 1 proposes a fiber-reinforced sheet, so-called strand sheet, in which multiple continuous fiber-reinforced plastic wires, so-called bamboo-like strands, which are made by impregnating reinforcing fibers with a matrix resin and hardening them, are aligned in a curtain-like shape in the longitudinal direction and fixed to each other with a wire fixing material, and reinforcement of structures is performed using such a strand sheet. Since a strand sheet with such a configuration does not require resin to be impregnated into the fiber bundles at the reinforcement site, it greatly contributes to shortening the reinforcement work time and improving work defects caused by insufficient impregnation.

[0008] On the other hand, because such strand sheets are composed of hardened fiber-reinforced plastic wires, while they are suitable for reinforcing straight sections, they are not suitable for reinforcing curved areas such as the haunch portions of decks or the corners of bridge piers.

[0009] Therefore, the reinforcement method described in Patent Document 1 discloses a method of using an adhesive to bond fiber-reinforced sheets made from fiber-reinforced plastic wires that have been bent in advance to fit the curvature of the structure to corners of structures such as the concave undersides of decks and bridge piers, and the haunch protruding and recessed corners of box culverts. However, it does not disclose a method of forming the bent fiber-reinforced plastic wires into sheets.

[0010] On the other hand, Patent Document 2 describes a method of reinforcing a structure in which, for example, in a concave curved portion of a structure such as the underside of a deck slab, a strand sheet is pressed against the surface of the concave portion of the structure to which an adhesive has been applied against the elastic force of the strand sheet, causing elastic deformation, and this state is temporarily fixed using a fixing device such as an L-angle, and the fixing device is removed after the adhesive has hardened. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] Patent No. 5214864 [Patent Document 2] Patent No. 5409259 Summary of the Invention [Problem to be solved by the invention]

[0012] The method of reinforcing a structure described in Patent Document 2 does not require the use of a fiber-reinforced sheet made by forming bent fiber-reinforced plastic wires into a sheet. However, the method of reinforcing a structure described in Patent Document 2 requires, in addition to applying an adhesive such as resin and attaching it, additional work such as attaching anchors to the concrete body, which involves other tasks besides resin application and attachment, and bolting. It also has problems such as the time-consuming task of removing the L-angles and cutting the anchor bolts after the resin has hardened.

[0013] Therefore, in order to solve the above problems, there is a need to economically produce various and small quantities of shaped fiber-reinforced sheets that have been bent to match the curvature of a structure prior to on-site construction, using manufacturing equipment that is easy to work with and has a simple configuration, with little capital investment.

[0014] The present inventors have found that a fiber-reinforced sheet in a B-stage state, i.e., a semi-cured state, made by stretching a fiber-reinforced plastic strand (hereinafter referred to as a "semi-cured fiber-reinforced plastic strand") in which the matrix resin is in a B-stage state (i.e., in a semi-cured state) in the longitudinal direction into a sheet shape (hereinafter referred to as a "semi-cured fiber-reinforced sheet") is clamped by a heating and shaping means and bent (shaped) at a predetermined curvature, and then the shaped semi-cured fiber-reinforced sheet is further heated to completely harden it, thereby making it possible to produce a shaped fiber-reinforced sheet with good workability and high efficiency. Moreover, it was found that the series of manufacturing equipment at this time can be made to have a simple configuration, and that a small number of various types of shaped fiber-reinforced sheets can be economically manufactured with a small capital investment. It was also found that the manufactured shaped fiber-reinforced sheet is not affected by the temperature of the environment and can exhibit stable tensile strength.

[0015] The present invention is based on the above-mentioned novel findings of the present inventors.

[0016] In other words, the main object of the present invention is to provide a method for producing a shaped fiber-reinforced sheet, a shaped fiber-reinforced sheet, and a semi-hardened fiber-reinforced sheet, which can economically produce a small number of different types of shaped fiber-reinforced sheets in shapes with a curvature that fits the corners and other curved parts of a structure using manufacturing equipment that is easy to work with and requires little capital investment, and which can be used to reinforce a structure by adhering it to the corners and other curved parts of the structure with an adhesive.

[0017] Another object of the present invention is to provide a method for producing a shaped fiber-reinforced sheet that can exhibit stable tensile strength without being affected by environmental temperature, and a shaped fiber-reinforced sheet, as well as a semi-hardened fiber-reinforced sheet, for use in reinforcing a structure by adhering it with an adhesive to bends such as corners of the structure. [Means for solving the problem]

[0018] The above objects can be achieved by the method for producing a shaped fiber-reinforced sheet, the shaped fiber-reinforced sheet, and the semi-hardened fiber-reinforced sheet according to the present invention. In summary, according to the first invention, there is provided a method for producing a shaped fiber-reinforced sheet for use in reinforcing a structure by bonding the sheet to a bent portion such as a corner of the structure with an adhesive, comprising: Semi-cured fiber reinforced plastic strands in which the matrix resin is in a B-stage state are aligned in a longitudinal direction in a sheet shape, and the semi-cured fiber reinforced sheet in the B-stage state is clamped by a heating and shaping means and bent at a predetermined curvature, and then the shaped semi-cured fiber reinforced sheet is further heated to completely cure. The present invention provides a method for producing a shaped fiber-reinforced sheet, comprising the steps of:

[0019] According to the second aspect of the present invention, there is provided a method for producing a shaped fiber-reinforced sheet in which a plurality of fiber-reinforced plastic strands are aligned in a curtain shape in the longitudinal direction and fixed to each other with a strand fixing material, the fiber-reinforced sheet having a bent portion that has been previously bent in order to be bonded to the corners of a structure with an adhesive to reinforce the structure, comprising: (a) a process for producing a semi-cured fiber-reinforced plastic strand in which a thermosetting resin is impregnated as a matrix resin into a reinforcing fiber bundle in which a large number of continuous reinforcing fibers are bundled, and then the matrix resin is heated by a heating means to be in a B-stage state in which the glass transition temperature (Tg value) of the matrix resin is 50 to 90°C; (b) A step of preparing a semi-cured fiber-reinforced sheet in which the matrix resin is in a B-stage state by drawing a plurality of the semi-cured fiber-reinforced plastic strands in a longitudinal direction and fixing the strands to each other with a strand fixing material; (c) clamping the semi-cured fiber reinforced sheet with a flexible heater and heating the entire semi-cured fiber reinforced sheet at a predetermined temperature in the range of 70 to 165°C; (d) bending the heated semi-cured fiber reinforced sheet at a predetermined curvature to give it a shape; (e) holding the semi-cured fiber reinforced sheet that has been bent at the predetermined curvature between the flexible heaters at a temperature of 100° C. or more and 165° C. or less to completely cure the matrix resin; (f) cooling the completely cured fiber reinforced sheet while being clamped by the flexible heater, and then removing the fiber reinforced sheet; A method for producing a shaped fiber-reinforced sheet is provided, comprising the steps of:

[0020] According to the third aspect of the present invention, there is provided a method for producing a shaped fiber-reinforced sheet, which is a fiber-reinforced sheet having a plurality of fiber-reinforced plastic strands arranged in a curtain shape in the longitudinal direction and fixed to each other with a strand fixing material, the fiber-reinforced sheet having a bent portion that has been previously bent in order to be bonded to the corners of a structure with an adhesive to reinforce the structure, comprising: (a) a process for producing a semi-cured fiber-reinforced plastic strand in which a thermosetting resin is impregnated as a matrix resin into a reinforcing fiber bundle in which a large number of continuous reinforcing fibers are bundled, and then the matrix resin is heated by a heating means to be in a B-stage state in which the glass transition temperature (Tg value) of the matrix resin is 50 to 90°C; (b) A step of preparing a semi-cured fiber-reinforced sheet in which the matrix resin is in a B-stage state by drawing a plurality of the semi-cured fiber-reinforced plastic strands in a longitudinal direction and fixing the strands to each other with a strand fixing material; (c) heating the entire semi-cured fiber-reinforced sheet at a predetermined temperature in the range of 55 to 165°C; (d) The heated semi-cured fiber reinforced sheet is pressed between an upper mold formed in a convex shape with a predetermined curvature and a lower mold formed in a concave shape with a complementary shape to the upper mold. A process of clamping and bending to give a shape; (e) a step of holding the semi-cured fiber-reinforced sheet, which has been bent to a predetermined curvature, between the upper and lower molds at a temperature of 100° C. or more and 165° C. or less to completely cure the matrix resin; (f) cooling the completely cured fiber reinforced sheet while being sandwiched between the upper mold and the lower mold, and then separating the upper mold and the lower mold to remove the fiber reinforced sheet; A method for producing a shaped fiber-reinforced sheet is provided, comprising the steps of:

[0021] According to the fourth aspect of the present invention, there is provided a sheet-like semi-cured fiber-reinforced sheet, characterized in that it is formed by aligning semi-cured fiber-reinforced plastic strands, in which the matrix resin is in a B-stage state, in a longitudinal direction in a curtain-like shape and fixing the strands together with a strand fixing material.

[0022] According to the fifth aspect of the present invention, there is provided a fiber-reinforced sheet in which a matrix resin is impregnated into a reinforcing fiber bundle in which a large number of continuous reinforcing fibers are bundled, and a plurality of hardened continuous fiber-reinforced plastic strands are aligned in a longitudinal direction in a curtain-like shape and fixed to each other with a strand fixing material, the fiber-reinforced sheet being a shaped sheet having a bent portion that has been previously bent in order to be bonded to the corners of a structure with an adhesive to reinforce the structure, The matrix resin has a glass transition temperature (Tg value) of 100°C or higher, and a shaped fiber-reinforced sheet is provided which is characterized in that it cannot be bent again even if it is heated to a temperature equal to or higher than the Tg value.

[0023] In one embodiment of the present invention, the reinforcing fiber bundle is twisted 5 to 100 times per meter, and the fiber-reinforced plastic strand has a substantially circular cross-sectional shape with a diameter of 0.5 to 5 mm.

[0024] In another embodiment of the present invention, the shaped fiber-reinforced sheet has an overall shape of a "L" or "U" shape, the radius of curvature (Ra) of the bent portion subjected to bending processing is 10 mm or more, and the tensile strength is 3500 N / mm2 or more.

[0025] In another embodiment of the present invention, the reinforcing fibers of the fiber-reinforced plastic strand are inorganic fibers such as carbon fibers, glass fibers, and basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; and organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester, and high-strength polyester; used alone or in a hybrid form by mixing two or more types.

[0026] In another embodiment of the present invention, the matrix resin of the fiber-reinforced plastic strand is a thermosetting resin such as a heat-curing epoxy resin, a vinyl ester resin, an MMA resin, an unsaturated polyester resin, or a phenol resin. Effect of the Invention

[0027] According to the present invention, a small amount of a wide variety of shaped fiber-reinforced sheets having a shape with a curvature that fits a bent portion such as a corner of a structure can be economically produced with a simple manufacturing device having good workability and a small capital investment. Furthermore, the shaped fiber-reinforced sheets produced according to the present invention can exhibit a stable tensile strength without being affected by the environmental temperature. [Brief description of the drawings]

[0028] [Figure 1] Figure 1(a) is an oblique view showing one embodiment of a shaped fiber-reinforced sheet produced by the shaped fiber-reinforced sheet manufacturing method of the present invention, Figure 1(b) is a side view, and Figures 1(c) and (d) are side views showing other embodiments of the shaped fiber-reinforced sheet. [Diagram 2] FIG. 2 is a schematic diagram of a manufacturing apparatus for explaining one embodiment of a method for producing a semi-cured fiber-reinforced plastic strand in the shaped fiber-reinforced sheet manufacturing method of the present invention. [Diagram 3] FIG. 3(a) is a perspective view showing an example of a semi-cured fiber reinforced sheet, and FIG. 3(b) is a cross-sectional view of a semi-cured fiber reinforced plastic strand. [Figure 4]4(a) and (b) are perspective views showing other examples of the semi-cured fiber reinforced sheet. [Diagram 5] 5(a), (b) and (c) are perspective views showing examples of reinforcing fiber bundles constituting a fiber-reinforced plastic strand. [Figure 6] 6(a) to (d) are diagrams illustrating an example of a procedure for bending a semi-cured fiber-reinforced sheet in the shaped fiber-reinforced sheet manufacturing method of the present invention. [Figure 7] 7(a) to (d) are diagrams illustrating another embodiment of the procedure for bending a semi-cured fiber-reinforced sheet in the shaped fiber-reinforced sheet manufacturing method of the present invention. [Figure 8] Figures 8(a), (b), and (c) are figures for explaining a tensile test of a fiber-reinforced plastic wire of the fiber-reinforced sheet of the present invention, where Fig. 8(a) is a test piece of a straight fiber-reinforced plastic wire, Fig. 8(b) is a test piece of a fiber-reinforced plastic wire that has been bent at 90°, and Fig. 8(c) is a figure explaining the aspect of a 90° bending tensile test on the test piece of the fiber-reinforced plastic wire that has been bent at 90° shown in Fig. 8(b). [Figure 9] 9(a) to (c) are diagrams illustrating a manner in which a corner portion of a structure is reinforced by using a shaped fiber-reinforced sheet that has been bent according to the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] According to the method for manufacturing a shaped fiber-reinforced sheet of the present invention, fiber-reinforced plastic strands (semi-cured fiber-reinforced plastic strands) in which the matrix resin is in a B-stage state (i.e., semi-cured state) are aligned in a curtain-like shape in the longitudinal direction to form a sheet, and the fiber-reinforced sheet in the B-stage state, i.e., in a semi-cured state, is clamped by a heating and shaping means and bent to a predetermined curvature, and then this shaped semi-cured fiber-reinforced sheet is further heated to completely harden it, thereby producing a shaped fiber-reinforced sheet for use in reinforcing a structure by adhering it with an adhesive to bends such as corners of a structure.

[0030] In the present invention, "shaped" means that the shape is maintained without the use of auxiliary or restraining materials, such as a form or a clamp, to maintain the shape.

[0031] The shaped fiber-reinforced sheet manufactured by the manufacturing method of the shaped fiber-reinforced sheet of the present invention is a fiber-reinforced sheet in which a plurality of fiber-reinforced plastic wires 2 are aligned in a longitudinal direction in a curtain-like shape and fixed to each other by a wire fixing material 3, as shown in Fig. 1 (a) and (b), and is bonded to the corners of a structure by an adhesive and is previously bent to reinforce the structure, resulting in a shaped fiber-reinforced sheet 1 having a bent portion 1R with a curvature radius Ra. The shaped fiber-reinforced sheet 1 can be any size as desired, but when used to reinforce the corners of a structure, the length L of the wires 2 in the longitudinal direction is usually 250 mm to 5 m, and the length La of the straight portion other than the bent portion 1R is 100 mm or more to express the joint strength with another fiber-reinforced sheet 1C (see Fig. 9 described later), and the width W is 250 mm to 500 mm.

[0032] In more detail, as will be understood later, the shaped fiber-reinforced sheet 1 produced by the present invention has a matrix resin with a glass transition temperature (Tg value) of 100°C or higher, and is in a state in which it cannot be bent again even if it is heated to a temperature above the Tg value.

[0033] Here, "re-bending is impossible" means, in the present invention, (i) bending the bent portion 1R to reduce the radius of curvature Ra of the bent portion 1R so that the radius of curvature Ra of the bent portion 1R is smaller than 0.5×Ra; and (ii) bending the bent portion 1R to increase the radius of curvature Ra of the bent portion 1R so that the radius of curvature Ra of the bent portion 1R is greater than 2×Ra; This means that it is not possible to

[0034] Hereinafter, the method for producing a shaped fiber-reinforced sheet and the shaped fiber-reinforced sheet according to the present invention will be described in more detail with reference to the drawings.

[0035] Example 1 According to a first embodiment of the present invention, a shaped fiber-reinforced sheet 1 is manufactured by a manufacturing method including the following steps (a) to (e), in which a plurality of fiber-reinforced plastic wires 2 are aligned in a longitudinal direction in a swirl shape and the wires 2 are fixed to each other with a wire fixing material 3, as shown in Fig. 1(a) and (b), and the shaped fiber-reinforced sheet 1 has a bent portion 1R with a curvature radius Ra that is previously bent in order to reinforce a structure by bonding the wires to the corners of the structure with an adhesive. Note that the shaped fiber-reinforced sheet 1 shown in Fig. 1(a) and (b) has an overall shape that is roughly "L" shaped, but as shown in Fig. 1(c) and (d), the shaped fiber-reinforced sheet 1 may also be bent into an overall shape that is roughly "U" shaped and has a curvature radius Ra in order to be applied to, for example, tunnels, sewer pipes, bridge piers, etc.

[0036] That is, according to the first embodiment of the present invention, as will be described in detail with reference to Figs. 2 to 6, the method for producing the shaped fiber-reinforced sheet 1 of the present invention is as follows: (a) a step of impregnating a reinforcing fiber bundle formed by bundling a large number of continuous reinforcing fibers with a thermosetting resin as a matrix resin, and then heating the impregnated fiber bundle with a heating means to produce a semi-cured fiber-reinforced plastic strand 2a in a B-stage state in which the glass transition temperature (Tg value) of the matrix resin is 50 to 90° C.; (b) A step of aligning a plurality of the semi-cured fiber-reinforced plastic strands 2a in the B-stage state in a longitudinal direction in a curtain shape and fixing the strands to each other with a strand fixing material to produce a semi-cured fiber-reinforced sheet 1a in which the matrix resin is in the B-stage state; (c) clamping the semi-cured fiber reinforced sheet 1a with a flexible heater 201 and heating the entire semi-cured fiber reinforced sheet at a predetermined temperature in the range of 70 to 165°C; (d) bending the heated semi-cured fiber-reinforced sheet 1a at a predetermined curvature to give it a shape; (e) a step of holding the semi-cured fiber-reinforced sheet, which has been bent to a predetermined curvature, between the flexible heaters at a temperature of 100° C. or more and 165° C. or less to completely cure the matrix resin; (f) cooling the completely cured fiber reinforced sheet 1 while it is sandwiched between the flexible heaters, and then removing the fiber reinforced sheet 1; It has.

[0037] The method for producing the shaped fiber-reinforced sheet of the present invention will now be described in more detail.

[0038] (1) Preparation of semi-hardened fiber-reinforced plastic wire The semi-cured fiber-reinforced plastic strand 2a can be produced by any method known to those skilled in the art. In this embodiment, a method for producing the semi-cured fiber-reinforced plastic strand 2a according to a conventional pultrusion method will be described with reference to FIG.

[0039] In Fig. 2, as shown in Fig. 5(a), a reinforcing fiber bundle F, which is a bundle of many continuous reinforcing fibers f oriented in one direction, moves from left to right, and during this process, the processes of resin impregnation, round shape forming, primary heat curing (semi-curing), and winding are performed. The process will be explained in more detail below.

[0040] According to a manufacturing apparatus 10 for carrying out the pultrusion method shown in FIG. 2, a reinforcing fiber bundle F consisting of a plurality of reinforcing fibers f that are not impregnated with resin and wound around a winding bobbin 11 is unwound from the winding bobbin 11 and fed to a resin impregnation process equipped with a resin impregnation tank 12.

[0041] The reinforcing fiber bundle F fed to the resin impregnation step is introduced to the impregnation roller 14 by the inlet guide roller 13, and is impregnated with the resin R.

[0042] Here, as understood above, the reinforcing fiber bundle F is composed of a large number of continuous reinforcing fibers f oriented in one direction bundled together, and the reinforcing fibers f may be inorganic fibers such as carbon fibers, glass fibers, and basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; or organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester, and high-strength polyester; either alone or in a hybrid form by mixing multiple types.

[0043] The matrix resin R impregnated into the reinforcing fiber bundle F is preferably a thermosetting resin, particularly a heat-curable epoxy resin, and may further be a vinyl ester resin, an MMA resin, an unsaturated polyester resin, or a phenol resin, etc. The amount of resin impregnation is 30 to 70% by weight, preferably 40 to 60% by weight.

[0044] In this embodiment, the temperature of the resin R in the resin impregnation tank 12 is set to 60°C, and the viscosity of the resin at that time is 250 mPa·s. The viscosity of the resin during impregnation is adjusted to within the range of 50 mPa·s to 10000 mPa·s. If the resin viscosity is less than 100 mPa·s, particularly 50 mPa·s, the impregnated resin will seep out, and when the resin is cured in the next step, the cross-sectional shape will become indefinite, resulting in poor appearance, and it will be difficult to maintain the fiber volume content at a constant level, resulting in quality problems. If the resin viscosity exceeds 10000 mPa·s, it will be difficult for the resin to be impregnated into the reinforcing fiber bundle F, and this will result in problems such as failure to obtain the required mechanical properties, including tensile strength.

[0045] The impregnation roller 14 impregnates the reinforcing fiber bundle F with the resin R, and an outlet guide roller 15 provided at the outlet of the resin impregnation tank 12 feeds the resin-impregnated reinforcing fiber bundle F to the next process.

[0046] The resin-impregnated reinforcing fiber bundle F is first fed to a mold 16, and then fed to a primary heat-curing furnace (semi-curing furnace) 18 serving as heating means.

[0047] That is, the mold 16 has a circular groove 17 with a predetermined diameter formed in the moving direction of the reinforcing fiber bundle F, and when the resin-impregnated reinforcing fiber bundle F passes through the circular groove 17, it is molded into a circular shape, and then heated in a semi-curing furnace 18 at a predetermined temperature for a predetermined time to perform primary curing (semi-curing) of the resin, thereby obtaining a circular semi-cured fiber-reinforced plastic strand 2a in a so-called B-stage state. Usually, the B-stage condition is that the temperature inside the semi-curing furnace 18 is 70 to 100°C, and the heating time is 10 to 240 minutes. In this embodiment, the resin-impregnated reinforcing fiber bundle F was heated for 120 minutes in a primary heating furnace (semi-curing furnace) with an internal temperature of 80°C.

[0048] The semi-cured fiber reinforced plastic strand 2a manufactured by the manufacturing method of this embodiment has a circular cross section, i.e., a round shape, and has a thin and elongated shape (thin diameter) like a bamboo stick with a substantially circular cross section with a diameter (d) of 0.5 to 5 mm, and has elasticity. The resin R is in a semi-cured state with a Tg value of 50 to 90°C. In order to avoid problems such as the sheet shape being disturbed due to shrinkage of the weft 3 and melting of the heat fusion material when manufacturing the semi-cured fiber reinforced sheet 1a using the semi-cured fiber reinforced plastic strand 2a, and to eliminate operational problems during bending processing when bending the semi-cured fiber reinforced sheet, the impregnated resin R in the semi-cured fiber reinforced plastic strand 2a needs to have a Tg value of 50 to 90°C. In other words, if the Tg value is less than 50°C, the resin has not been sufficiently polymerized and therefore has high fluidity, which causes the resin to flow out during processing, making the shape of the semi-cured fiber reinforced plastic strand 2a unstable, as well as causing problems such as the strands fusing together and the sheet shape being distorted.If the Tg value exceeds 90°C, the resin has progressed in polymerization and therefore has high fluidity, making it necessary to heat the semi-cured fiber reinforced sheet 1a to a higher temperature in the bending process, which causes the shrinkage of the weft threads 3 and the melting of the heat-sealing material, significantly distorting the sheet shape and making it impossible to maintain quality, as well as generating smoke due to the combustion of volatile components such as residual monomers in the impregnated resin, which is undesirable from a safety standpoint.

[0049] The melt viscosity of the impregnating resin R in the semi-cured fiber reinforced plastic strand 2a is set to a range of 0.1 Pa·s to 1000 Pa·s because it is necessary to soften the resin by heating appropriately so that the semi-cured fiber reinforced sheet 1a can conform to the curved surface of the mold. If the melt viscosity is less than 0.1 Pa·s, the matrix resin will flow out during bending, causing burrs and resulting in a poor appearance, and the fiber volume content of the semi-cured fiber reinforced plastic strand 2a will not be constant. If the resin viscosity exceeds 1000 Pa·s, the semi-cured fiber reinforced plastic strand 2a will not be sufficiently softened, causing problems such as buckling or bending fracture of the semi-cured fiber reinforced plastic strand 2a during bending.

[0050] The wire 2a semi-hardened in the primary heating furnace 27A is fed to the bobbin 19 of the winding device, and is wound around the bobbin 19 via release paper, release film, or the like, if necessary.

[0051] Further, in the case of the semi-cured fiber-reinforced plastic strand 2a, for example, when carbon fiber is used as the reinforcing fiber f, a resin-unimpregnated reinforcing fiber bundle F can be obtained by bundling 6,000 to 24,000 single fibers (carbon fiber monofilaments) f having an average diameter of 7 μm, which are aligned parallel to one direction, and impregnated with a matrix resin R, followed by semi-curing.

[0052] Here, as shown in FIG. 5(b), the semi-hardened fiber-reinforced plastic strand 2a can be configured by twisting a reinforcing fiber bundle F, which is made up of a large number of continuous reinforcing fibers f oriented in one direction, 5 to 100 times per meter (i.e., 5 to 100 turns / m).

[0053] According to the experiments of the present inventors, it was found that the bending tensile strength is lower than the linear tensile strength, especially when the twisting number is less than 5 turns / m (the bending tensile strength and linear tensile strength will be described later with reference to Figs. 8(a) to (c)). On the other hand, when the twisting number exceeds 100 turns / m, the strength of the strand itself is reduced due to the excessive number of twists, and as a result, it was found that the linear tensile strength and the bending tensile strength are about the same. In the present invention, since the semi-cured fiber reinforced plastic wire 2a is subjected to bending processing, the above-mentioned problem rarely occurs. However, it can be said that it is preferable to twist within the range of 5 to 100 turns / m in that it is possible to prevent the fibers in the reinforcing fiber bundle F from being disturbed when the reinforcing fiber bundle F is impregnated with the resin R to prepare the resin-impregnated reinforcing fiber bundle F and when the resin-impregnated reinforcing fiber bundle F is fed to the mold 16 and then fed to the primary heat curing furnace 27B.

[0054] The reinforcing fiber bundle F can also be formed by twisting a number of, for example, three continuous reinforcing fiber bundles Fa having a small diameter, as shown in FIG. 5(c).

[0055] The semi-cured fiber reinforced plastic strand 2a can be produced by twisting a non-resin-impregnated reinforcing fiber bundle F made of a bundle of many continuous reinforcing fibers f, impregnating it with resin, and then semi-curing it, but if desired, it can also be produced by twisting the resin-impregnated reinforcing fiber bundle F by a predetermined number of twists, i.e., by semi-curing the matrix resin. Also, in the reinforcing fiber bundle F shown in Fig. 5(c), the semi-cured fiber reinforced plastic strand 2a can be produced by twisting three small-diameter reinforcing fiber bundles Fa that have been resin-impregnated, and then semi-curing the resin.

[0056] (2) Preparation of semi-hardened fiber-reinforced sheet Next, the semi-cured fiber reinforced sheet 1a is produced using the semi-cured fiber reinforced plastic strand 2a. An example of the production of the semi-cured fiber reinforced sheet 1a is shown in Figures 3(a) and (b).

[0057] The semi-cured fiber reinforced sheet 1a is produced by arranging a plurality of continuous semi-cured fiber reinforced plastic wires (ie, semi-cured strands) 2a in a longitudinal direction in a curtain shape and fixing each wire 2a to each other with a wire fixing material 3.

[0058] As a method for fixing each wire 2a with a wire fixing material 3, as shown in FIG. 3(a), for example, a method may be adopted in which a weft is used as the wire fixing material 3, and a wire in the form of a sheet consisting of a plurality of wires 2a arranged in one direction in a curtain-like manner, i.e., a continuous wire sheet, is driven at a constant interval (P) in a direction perpendicular to the longitudinal direction of the wires 2a, and woven. The driving interval (P) of the weft 3 is not particularly limited, but is usually selected in the range of 10 to 100 mm intervals in consideration of the handleability of the produced semi-hardened fiber reinforced sheet 1a. The semi-hardened fiber reinforced sheet 1a may have any dimensions depending on the dimensions of the shaped fiber reinforced sheet 1 to be produced, but when used to reinforce corners of a structure, the length L of the wire 2 in the longitudinal direction is usually 250 mm to 5 m and the width W is usually 250 to 500 mm depending on the dimensions of the shaped fiber reinforced sheet 1.

[0059] In this case, the weft thread 3 is, for example, a yarn formed by bundling a plurality of glass fibers or organic fibers having a diameter of 2 to 50 μm. As the organic fiber, nylon, vinylon, polyester, etc. are preferably used.

[0060] As another method for fixing the wires 2 in a blind shape, a mesh-like support sheet can be used as the wire fixing material 3 as shown in FIG. 4(a).

[0061] In other words, one or both sides of a plurality of wires 2a aligned in a blind-like shape forming a sheet, i.e., a wire sheet, can be supported by a mesh-like support sheet 3 made of glass fiber or organic fiber having a diameter of, for example, 2 to 50 μm.

[0062] In this case, for example, the surfaces of the warp threads 4 and weft threads 5 constituting the mesh-like support sheet 3 having a biaxial structure are pre-impregnated with a low-melting point type thermoplastic resin, and the mesh-like support sheet 3 is laminated on both sides of the blind-like wire sheet and heated and pressed to weld the warp threads 4 and weft threads 5 of the mesh-like support sheet 3 to the blind-like wire sheet.

[0063] In addition to the biaxial configuration, the mesh-like support sheet 3 can be formed by orienting the glass fibers triaxially, or by arranging the glass fibers in a so-called uniaxial orientation in which only the weft threads 5 are arranged perpendicular to the wire 2, and then bonded to the multiple wires 2a that have been aligned in the form of a sheet.

[0064] As the thread of the wire fixing material 3, for example, a double-structure composite fiber having a glass fiber core and a low-melting point heat-fusible polyester or polyamide surrounding the core is also preferably used.

[0065] As another method for fixing the wires 2a in a curtain shape, as shown in Fig. 4(b), a flexible strip such as an adhesive tape or a bonding tape can be used as the wire fixing material 3. The flexible strip 3 is attached to one or both sides of the multiple semi-cured fiber-reinforced plastic wires 2a in a direction perpendicular to the longitudinal direction of each semi-cured fiber-reinforced plastic wire 2 that has been aligned in a curtain shape forming a sheet.

[0066] That is, a pressure-sensitive adhesive tape such as polyvinyl chloride tape, paper tape, cloth tape, or nonwoven fabric tape with a width (w1) of about 2 to 30 mm is used as the flexible strip 3. These tapes 3 are usually attached at intervals (P) of 10 to 100 mm in a direction perpendicular to the longitudinal direction of each semi-cured fiber-reinforced plastic strand 2a.

[0067] Furthermore, the flexible strip 3 can also be achieved by thermally fusing a thermoplastic resin such as nylon or EVA resin in a strip shape to one or both sides of the wire 2 in a direction perpendicular to the longitudinal direction.

[0068] In the present invention, since the matrix resin of the semi-cured fiber-reinforced plastic strand 2a is in a semi-cured state, the strand fixing material 3 is temporarily fixed by fusion of the matrix resin, and is then completely fixed by shaping and final curing. Note that the strand can also be fixed with the strand fixing material 3 at the same time as bending the strand, which will be described later.

[0069] (3) Bending of semi-hardened fiber-reinforced sheet In the present invention, as described above, bending is performed on the semi-cured fiber reinforced sheet 1a having the above-mentioned configuration, which is produced using the semi-cured fiber reinforced plastic strand 2a. Of course, it is not impossible to perform bending on a fiber reinforced sheet using fiber reinforced plastic strands in a state immediately after impregnation with the matrix resin (i.e., A-stage state), but the resin is very sticky, workability is poor, and there are burrs and adhesion between strands due to a large resin flow, and a deterioration of the cross-sectional shape. Therefore, in the present invention, bending is performed on the semi-cured fiber reinforced sheet 1a produced using the semi-cured fiber reinforced plastic strand 2a, as described above.

[0070] Next, an embodiment of a bending method for a semi-cured fiber-reinforced sheet 1a and a processing device therefor will be described with reference to Figures 6(a) to 6(d). In this embodiment, a shaped fiber-reinforced sheet 1 having a roughly V-shape as shown in Figures 1(a) and 1(b) will be produced.

[0071] According to this embodiment, the bending device 200 is provided with a flexible sheet heating element such as a rubber heater, i.e., a flexible heater 201, as a heating shaping means, and as can be understood by referring to FIG. 6(a), the flexible heater 201 has an upper flexible heater 201a and a lower flexible heater 201b. For example, a commercially available heater manufactured by Sakaguchi Electric Heating Co., Ltd. (product name "Samicon 230") or Nippon Heater Co., Ltd. (silicone rubber heater RSP type) can be suitably used as the flexible heater 201. Depending on the size of the fiber reinforced sheet 1, it is also possible to use a plurality of heaters, or to attach a heater to a flexible heat conductive material such as a metal foil as a heat spreader.

[0072] 6(a) and (b), the flexible heater 201 sandwiches the semi-cured fiber reinforced sheet 1a between the upper flexible heater 201a and the lower flexible heater 201b, and heats the entire semi-cured fiber reinforced sheet 1a to a predetermined temperature in the range of 70 to 165°C. If the heating temperature is less than 70°C, the semi-cured fiber reinforced sheet cannot be sufficiently softened, resulting in problems such as buckling and breakage during bending. If the heating temperature exceeds 165°C, problems such as adhesion between wires and burrs due to the outflow of resin, shrinkage of the weft 3 and melting of the heat-sealing material significantly disturbing the sheet shape, making it impossible to maintain quality, and smoke is generated due to combustion of volatile components such as residual monomers of the impregnated resin, which is undesirable from a safety standpoint. In this embodiment, the semi-cured fiber reinforced sheet 1a is sandwiched between the upper flexible heater 201a and the lower flexible heater 201b, and the semi-cured fiber reinforced sheet 1a is heated to 150°C.

[0073] Next, as shown in FIG. 6(c), the upper flexible heater 201a and the lower flexible heater 201b are bent at a predetermined angle with respect to the longitudinal direction of the wire 2a, and the semi-cured fiber reinforced sheet 1a is bent at a desired predetermined angle (shaping angle) θ with respect to the longitudinal direction of the wire 2a. If the straight state of the wire 2a is 0°, the wire 2a can be bent by 10° or more. That is, the shaping angle θ can be changed from a state in which the wire 2a is bent by 10°, i.e., the shaping angle θ is 170°, to a state in which the wire 2a is bent to a state in which the wire 2a is folded in half, i.e., the shaping angle θ is 0°. That is, the shaping angle θ can be set to 0° to 170°. In addition, the shaped fiber reinforced sheet 1 is often fitted to the corners of a structure. For example, when preparing the "L"-shaped sheet shown in Fig. 1(a) and (b), the shaping angle θ of the wire is set to 90° to 120°, and is usually set to about 90°. In the case of the "U"-shaped sheet shown in Fig. 1(c), it is bent at about 180° (i.e., θ≒0°), and in the case of the wide "U"-shaped sheet shown in Fig. 1(d), both ends of the bent portion 1R are bent at about 90° (i.e., θ≒90°). The curvature radius Ra of the bent portion 1R of the semi-hardened fiber reinforced sheet 1a is set to 10 mm or more with respect to the longitudinal direction of the wire 2a, and is usually set to 1000 mm or less. In this embodiment, as described later, the overall shape shown in Figs. 1(a) and (b) is "L" shaped, the shaping angle θ ≈ 90°, and the curvature radius Ra ≈ 100 mm.

[0074] The shaped semi-cured fiber reinforced sheet 1a spreads due to the repulsive force (springback) of the wire 2a, making it difficult to bend it to the desired angle θ. Therefore, the flexible heater 201 holds the semi-cured fiber reinforced sheet 1a having the shaped bent portion 1R between the upper flexible heater 201a and the lower flexible heater 201b in this state (as shown in FIG. 6(c)) at a temperature of 100°C or higher for a predetermined time, typically at a predetermined temperature in the range of 100°C to 165°C for 5 minutes to 8 hours, to completely cure the semi-cured fiber reinforced sheet 1a. In this embodiment, the semi-cured fiber reinforced sheet 1a was completely cured by holding it at 150°C for 1 hour.

[0075] The fiber reinforced sheet 1a heated to a completely cured state in the above-mentioned manner is cooled while being sandwiched between the upper flexible heater 201a and the lower flexible heater 201b (as shown in FIG. 6(c)). After cooling, the upper flexible heater 201a and the lower flexible heater 201b are separated and the sheet is removed from the flexible heater 201. The completely cured fiber reinforced sheet 1 thus produced and cooled has a Tg value of 100° C. or more, and typically has a Tg value of 100 to 250° C. If the Tg value is less than 100° C., the resin softens due to direct sunlight in the hot summer sun or heat generated by materials used at a construction site such as asphalt, causing springback, which may cause the shape of the fiber reinforced sheet to become unstable.

[0076] In the present invention, the impregnating resin R in the fiber-reinforced sheet 1 has already been cured and is in an insoluble and infusible state, and therefore the melt viscosity thereof is not measured.

[0077] The bending processing apparatus 200 having the above-described configuration is a manufacturing apparatus having a simple configuration, and can economically produce, with a small capital investment, shaped fiber-reinforced sheets 1 to be used for reinforcing structures by bonding them with an adhesive to bends such as corners of the structures.

[0078] Example 2 Next, a second embodiment of the present invention will be described. In this embodiment 2, as in the above-mentioned embodiment 1, a fiber-reinforced sheet 1 is manufactured in which a plurality of fiber-reinforced plastic strands 2 are aligned in a curtain-like shape in the longitudinal direction and the strands 2 are fixed to each other with a strand fixing material 3, as shown in Fig. 1(a), (b), and further Fig. 1(c) and (d), and the shaped fiber-reinforced sheet 1 has bent parts that are bonded to the corners with an adhesive and are previously bent to reinforce a structure.

[0079] According to a second embodiment of the present invention, as will be described in detail with reference to Figs. 2 to 5 and 7, a method for producing a shaped fiber-reinforced sheet 1 of the present invention includes the following steps: (a) a step of impregnating a reinforcing fiber bundle formed by bundling a large number of continuous reinforcing fibers with a thermosetting epoxy resin as a matrix resin, and then heating the impregnated fiber bundle with a heating means to produce a semi-cured fiber-reinforced plastic strand 2a in a B-stage state in which the glass transition temperature (Tg value) of the matrix resin is 50 to 90°C; (b) A step of aligning a plurality of the semi-cured fiber-reinforced plastic strands 2a in the B-stage state in a longitudinal direction in a curtain shape and fixing the strands to each other with a strand fixing material to produce a semi-cured fiber-reinforced sheet 1a in which the matrix resin is in the B-stage state; (c) heating the entire semi-cured fiber-reinforced sheet at a predetermined temperature in the range of 55 to 165°C; (d) a step of sandwiching and bending the heated semi-cured fiber reinforced sheet 1a between an upper mold formed in a convex shape with a predetermined curvature and a lower mold formed in a concave shape complementary to the upper mold; (e) a step of holding the semi-cured fiber-reinforced sheet, which has been bent to a predetermined curvature, between the upper and lower molds at a temperature of 100° C. or more and 165° C. or less to completely cure the matrix resin; (f) cooling the completely cured fiber reinforced sheet while being sandwiched between the upper mold and the lower mold, and then removing the fiber reinforced sheet; It has.

[0080] The method for producing the shaped fiber-reinforced sheet 1 of Example 2 will be described in more detail.

[0081] In the manufacturing method of the shaped fiber-reinforced sheet of this Example 2, the explanation of "(1) Preparation of semi-hardened fiber-reinforced plastic strand" and "(2) Preparation of semi-hardened fiber-reinforced sheet" carried out in the above steps (a) and (b) is the same as the above "(1) Preparation of semi-hardened fiber-reinforced plastic strand" and "(2) Preparation of semi-hardened fiber-reinforced sheet" described in Example 1 above, so detailed explanation will not be repeated.

[0082] The manufacturing method of the shaped fiber-reinforced sheet of Example 2 differs from Example 1 in “(3) Bending of the semi-hardened fiber-reinforced sheet” carried out in the above steps (c) to (f) of this Example 2. Next, we will explain in more detail “(3) Bending of the semi-hardened fiber-reinforced sheet” in this Example 2.

[0083] (1) Preparation of semi-hardened fiber-reinforced plastic wire In the manufacturing method of the shaped fiber-reinforced sheet 2a of this Example 2, the semi-cured fiber-reinforced plastic strand 2a is also manufactured by using the materials, method, and apparatus described in “(1) Manufacturing of semi-cured fiber-reinforced plastic strand” in Example 1 above.

[0084] (2) Preparation of semi-hardened fiber-reinforced sheet In the manufacturing method of the shaped fiber-reinforced sheet of this Example 2, the semi-hardened fiber-reinforced sheet 1a is also produced by using the materials, method, and apparatus described in “(2) Production of semi-hardened fiber-reinforced sheet” in Example 1 above.

[0085] (3) Bending of semi-hardened fiber-reinforced sheet Bending is performed on the semi-hardened fiber reinforced sheet 1a having the same configuration as the semi-hardened fiber reinforced sheet 1a described in Example 1. An embodiment of a bending method for the semi-hardened fiber reinforced sheet 1a according to this Example 2 and a processing device therefor will be described with reference to Figures 7(a) to (c).

[0086] According to this embodiment, the bending apparatus 300 for the semi-cured fiber reinforced sheet 1a includes a bending mold 301, as can be seen from FIG. 7(b). The bending mold 301 includes an upper mold (male mold) 301a and a lower mold (female mold) 301b. The upper mold 301a and the lower mold 301b each have complementary pressing surfaces, i.e., a convex surface 302a and a concave surface 302b, so that the semi-cured fiber reinforced sheet 1a can be sandwiched between the upper mold 301a and the lower mold 301b and a predetermined bending process can be performed on the semi-cured fiber reinforced sheet 1a. The curved surface forming angle of the pressing surfaces 302a and 302b, i.e., the shaping angle (θ) and the curvature radius Ra, are appropriately set according to the desired bending shape of the bent portion 1R of the semi-cured fiber reinforced sheet 1a.

[0087] The shaping angle (θ) and the curvature radius Ra are the same as those described in Example 1. That is, the shaping angle θ is 0° to 170°, and the curvature radius Ra is 10 mm or more, and usually 1000 mm or less, relative to the longitudinal direction of the wire 2a. However, in this example, as in Example 1, a shaped fiber-reinforced sheet 1 having an overall shape of a "L" shape as shown in Figs. 1(a) and (b) is produced, and the shaping angle θ of the pressing surfaces 302a and 302b is approximately 90°, and the curvature radius Ra is approximately 100 mm.

[0088] Next, a method for bending the semi-cured fiber reinforced sheet 1a will be described. As shown in FIG. 7(b), before the semi-cured fiber reinforced sheet 1a is sandwiched between the upper mold 301a and the lower mold 301b, the entire semi-cured fiber reinforced sheet 1a is uniformly heated at a temperature in the range of 55 to 165°C as shown in FIG. 7(a). There is no particular limitation on the method for uniformly heating the semi-cured fiber reinforced sheet 1a, and any method may be used as long as the semi-cured fiber reinforced sheet 1a can be uniformly heated. For example, a method of heating by sandwiching the semi-cured fiber reinforced sheet 1a between a flexible planar heating element such as the rubber heater described in Example 1, or a method of heating by blowing hot air onto the sheet can be applied.

[0089] In the manufacturing method described in the previous Example 1, the semi-cured fiber reinforced sheet 1a sandwiched between the upper flexible heater 201a and the lower flexible heater 201b is heated to a predetermined temperature in the range of 70 to 165 ° C., but in this Example, the semi-cured fiber reinforced sheet 1a is uniformly preheated to a temperature in the range of 55 to 165 ° C., and then sandwiched between the upper mold 301a and the lower mold 301b. Thus, in this Example, a low heating temperature range with a lower limit of 55 ° C., such as a range of 55 to 165 ° C., is adopted as the heating temperature in the preheating step of the semi-cured fiber reinforced sheet 1a. This is because when a mold is used during shaping, the processing speed is faster than in Example 1, and if the semi-cured fiber reinforced sheet is not preheated, the softening of the resin is delayed, which may cause buckling or breakage during processing.

[0090] Next, as shown in FIG. 7(b), before the uniformly preheated semi-cured fiber reinforced sheet 1a is air-cooled, the sheet 1a is placed on the lower mold 301b, and the semi-cured fiber reinforced sheet 1a is pressed into the lower mold 301b using the upper mold 301a to sandwich the semi-cured fiber reinforced sheet 1a between the upper mold 301a and the lower mold 301b for shaping. After this, the semi-cured fiber reinforced sheet 1a having the shaped bent portion 1c is held between the upper mold 301a and the lower mold 301b at a temperature of 100°C or higher for a predetermined time, typically at a temperature in the range of 100°C to 165°C for 1 to 8 hours, to completely cure the semi-cured fiber reinforced sheet 1a. In this embodiment, the semi-cured fiber reinforced sheet 1a is completely cured by holding it at 150°C for 1 hour.

[0091] The above-mentioned completely cured fiber reinforced sheet 1 is cooled while still sandwiched between the upper mold 301a and the lower mold 301b, and after cooling, the upper mold 301a and the lower mold 301b are separated and the sheet is removed from the upper mold 301a and the lower mold 301b. The completely cured fiber reinforced sheet 1 thus produced has a Tg value of 100°C or more, typically 100°C to 250°C, for the same reasons as explained in Example 1. In addition, since the impregnated resin R in the fiber reinforced sheet 1 is completely cured, its melt viscosity is in an insoluble and unmeltable state due to the completion of curing, and therefore cannot be measured.

[0092] The bending processing apparatus 300 having the above-described configuration described in this Example 2 is also a manufacturing apparatus having a simple configuration, and can economically produce, with a small capital investment, shaped fiber-reinforced sheets to be used for reinforcing structures by bonding them with an adhesive to bends such as corners of the structures.

[0093] (About matrix resin) As understood from the above, according to the manufacturing method of the shaped fiber reinforced sheet of the present invention, a fiber reinforced sheet (semi-cured fiber reinforced sheet) 1a in a B-stage state (i.e., semi-cured state) is produced using a fiber reinforced plastic strand (semi-cured fiber reinforced plastic strand) 2a in which the impregnated matrix resin R is in a B-stage state (i.e., semi-cured state), and this semi-cured fiber reinforced sheet 1a is bent at a predetermined curvature while being heated to be shaped, and then this shaped semi-cured fiber reinforced sheet 1a is further heated to be completely cured, thereby producing a shaped fiber reinforced sheet 1. The matrix resin R has a glass transition temperature Tg value of 50 to 90°C in the semi-cured fiber reinforced sheet 1a, and a Tg value of 100°C or more, usually 100°C to 250°C, in the completely cured shaped fiber reinforced sheet 1. The melt viscosity of the impregnated resin R in the shaped fiber reinforced sheet 1 is unmeasurable because the curing is completed and the impregnated resin R is in an insoluble and unmeltable state. Thus, in the present invention, the impregnated matrix resin R constitutes an important element. Therefore, the matrix resin R will be described below.

[0094] The glass transition temperature (Tg value) in the present invention is a value determined by differential scanning calorimeter (DSC) based on JIS K7121, a method for measuring transition temperature of plastics. The measuring device used was a Hitachi High-Tech Science Corporation product (product name: DSC7020). The viscosity of the resin was measured using an Anton Pear Corporation product (product name: "MCR 102").

[0095] As a result of research and experiments by the present inventors, it has been found that, although a thermosetting resin can be used as the matrix resin used in the present invention, a heat-curable epoxy resin is preferable.

[0096] Next, the relationship between the strength of the shaped fiber-reinforced sheet produced according to the present invention and the glass transition temperature (Tg value) of the matrix resin will be described in more detail based on experiments conducted by the present inventors.

[0097] (experiment) In this experiment, the reinforcing fiber bundle F was a reinforcing fiber bundle (PAN-based carbon fiber (manufactured by Toray Industries, Inc.: product name "T700SC-240000-60E") consisting of 24,000 single fibers (carbon fiber monofilament) f having an average diameter of 7 μm, and was impregnated with a heat-curable epoxy resin having compositions 1 to 3 shown below as the matrix resin. In this experiment, the uncured resin-impregnated reinforcing fiber bundle F after resin impregnation was twisted at a twist rate of 18 turns / m.

[0098] (Composition 1) (1) Epoxy base Liquid bisphenol A type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.: product name "YD-128"): 100 phr 1-6 Hexanediol diglycidyl ether (ADEKA Corporation: product name "ED-503"): 67 phr (2) Hardener Dicyandiamide: 12 phr (3) Curing accelerator Dichlorophenyl dimethyl urea: 2 phr The above (1) to (3) (total 181 phr) were blended.

[0099] (Composition 2) (1) Epoxy base Liquid bisphenol A type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.: product name "YD-128"): 10 phr Solid bisphenol A type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.: product name "YD-011"): 40 phr Reactive diluent: 1-6 hexanediol diglycidyl ether (manufactured by Yokkaichi Chemical Co., Ltd.: product name "Epogosei HD"): 50 phr (2) Hardener Dicyandiamide: 4 phr (3) Curing accelerator Dichlorophenyl dimethyl urea: 4 phr The above (1) to (3) (total 108 phr) were blended.

[0100] (Composition 3) (1) Epoxy base Liquid bisphenol A type epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.: product name "YD-128"): 90 phr Solid bisphenol A 4-functional epoxy resin (manufactured by Nippon Steel Chemical & Material Co., Ltd.: product name "YH-434"): 10 phr (2) Hardener 2-Phenyl-4-methyl-5-hydroxymethylimidazole (Shikoku Chemical Industry Co., Ltd., 2P4MHZ): 5.0 phr The above (1) and (2) (total 105 phr) were mixed.

[0101] (Consideration) Bend test Experimental Example 1 is an embodiment according to the present invention, and Experimental Examples 2 to 4 are comparative examples of the present invention.

[0102] Experimental Example 1: In Experimental Example 1, the resin-impregnated reinforcing fiber bundle F impregnated with the matrix resin of Composition 1 was heated under B-stage conditions of 80°C and 120 minutes to produce a semi-cured fiber reinforced plastic wire 2a. Next, this semi-cured fiber reinforced plastic wire 2a was heated to 150°C using a heat gun, clamped in a mold, and bent at a shaping angle θ = 90° and a curvature radius Ra = 100 mm. Furthermore, the semi-cured fiber reinforced plastic wire 2a was heated to 150°C for 60 minutes using a heat gun to produce a completely cured fiber reinforced plastic wire 2. In Experimental Example 1, the Tg values ​​were measured for the wires 2a and 2 in the B-stage state (semi-cured) and the final cured state (completely cured). The Tg value in the B-stage state (semi-cured) was 50°C or more, and the Tg value in the final cured state (completely cured) was 100°C or more.

[0103] The wire 2a in the semi-hardened state could be bent well, but when the completely hardened wire 2 was further bent, the wire 2 was broken.

[0104] As described above, the Tg value was measured based on the JIS K7121 method for measuring transition temperature of plastics by differential scanning calorimetry (DSC measurement), using a measuring device manufactured by Hitachi High-Tech Science Corporation (product name: DSC7020).

[0105] Experimental Example 2: In experimental example 2, a resin-impregnated reinforcing fiber bundle F impregnated with the matrix resin of composition 2 above was heated to 150°C using a heat gun, and this fiber-reinforced plastic strand 2 was clamped in a mold and bent to a shaping angle θ = 90° and a curvature radius Ra = 100 mm. It was then further heated at 150°C for 60 minutes to produce a completely hardened fiber-reinforced plastic strand 2.

[0106] In Experimental Example 2, the Tg value of the fully cured wire 2 was measured using the same measuring device as that used in Experimental Example 1. The Tg value was below 50° C. This fully cured fiber-reinforced plastic wire 2 could be bent, and the wire 2 could also be bent again after bending without breaking.

[0107] Experimental Example 3: In Experimental Example 3, a resin-impregnated reinforcing fiber bundle F impregnated with the matrix resin of Composition 1 above was heated to 150°C using a heat gun, and this fiber-reinforced plastic strand 2 was clamped in a mold and bent to a shaping angle θ = 90° and a curvature radius Ra = 100 mm. It was then further heated at 150°C for 60 minutes to produce a completely hardened fiber-reinforced plastic strand 2.

[0108] In Experimental Example 3, the Tg value of the fully cured wire 2 was measured using the same measuring device as that used in Experimental Example 1. The Tg value was 173° C. When the fully cured fiber-reinforced plastic wire 2 was subjected to bending processing, the wire 2 was broken.

[0109] Experimental Example 4: In experimental example 4, a resin-impregnated reinforcing fiber bundle F impregnated with the matrix resin of composition 3 above was heated to 150°C using a heat gun, and this fiber-reinforced plastic strand 2 was clamped in a mold and bent to a shaping angle θ = 90° and a curvature radius Ra = 100 mm. It was then further heated at 150°C for 60 minutes to produce a completely hardened fiber-reinforced plastic strand 2.

[0110] In Experimental Example 4, the Tg value of the fully cured wire 2 was measured using the same measuring device as that used in Experimental Example 1. The Tg value was greater than 100° C. When the fully cured fiber-reinforced plastic wire 2 was subjected to bending, the wire 2 was broken.

[0111] The viscosity of the epoxy resin at 23°C is 47,500 mPa·s, so it was heated to 40°C before use in the experiment. The viscosity at that time was 2,020 mPa·s.

[0112] Tensile strength test Tensile tests were conducted on the fiber-reinforced plastic strands 2 obtained in Experimental Examples 1 and 2. First, as shown in Figs. 8(a) and (b), a fiber-reinforced plastic strand (straight strand) 2 (Fig. 8(a)) that was not bent and had experimental tabs 230 fixed to both ends, and a fiber-reinforced plastic strand (curved strand) 2 (Fig. 8(b)) that was bent were prepared as test pieces 2T. A straight tensile test was conducted on the straight strand 2, and a bending tensile test was conducted on the curved strand 2 at a curvature radius of 50 mm and a 90° angle using a bending jig 400 with a jig curvature radius R400 as shown in Fig. 8(c). The substantial main body length L2T of the fiber-reinforced plastic strand 2 of the test piece 2T was 380 mm, and the wire diameter d2T was 2.1 mm.

[0113] In Experimental Example 1, as described above, bending of the semi-hardened wire was successfully performed, and the fully hardened wire had a Tg value of more than 100°C and a strength of 3500N / mm2 or more in an environment of 23°C and 40°C, and there was no decrease in strength due to changes in environmental temperature. It was found that the shaped fiber-reinforced sheet 1 manufactured according to the present invention can exhibit stable tensile strength without being affected by the environmental temperature. As described above, when the fully hardened wire was bent again, the wire was broken. In other words, it was found that it was impossible to bend again the wire 2 manufactured according to the present invention, which has a Tg value of 100°C or more after fully hardened.

[0114] In Experimental Example 2, the Tg value of the wire after complete hardening was less than 50°C, and the wire could be bent again, but the tensile strength at an air temperature of 40°C was significantly reduced to below 3500 N / mm2.

[0115] In Experimental Examples 3 and 4, the Tg value of the wire after complete hardening exceeded 100° C., and the wire was broken when bent.

[0116] The measurement results of Experimental Examples 1 to 4 are shown in Table 1.

[0117] [Table 1]

[0118] (Method of reinforcing structures) Next, with reference to Figs. 9(a) to (c), reinforcement of a structure 100 using a shaped fiber-reinforced sheet 1 constructed according to the present invention will be described.

[0119] When reinforcing the structure 100, in cases where a fiber-reinforced sheet 1 with straight fiber-reinforced plastic wires 2 is arranged circumferentially around a rectangular column member, or where a shaped fiber-reinforced sheet 1 is arranged at a haunch corner, etc., bending failure of the fiber-reinforced plastic wires 2 may occur at the protruding corners and recessed corners of the structure when the fiber-reinforced sheet 1 with straight fiber-reinforced plastic wires 2 is arranged around the corners of the structure.

[0120] Therefore, for example, by placing a shaped fiber-reinforced sheet 1 bent according to the present invention as shown in Figures 1(a) and (b) in the corner portion of the reinforced structure, that is, a shaped fiber-reinforced sheet 1 (1A, 1B) bent according to the present invention as shown in Figures 9(a) to (c), and placing a straight fiber-reinforced sheet 1C in the general portion and joining the fiber-reinforced sheets 1A, 1B, 1C with a lap joint, it is possible to wrap the fiber-reinforced sheet 1 continuously in the circumferential direction of a rectangular column member or to continuously reinforce a haunch portion having an inside corner.

[0121] For example, as shown in Figure 9(a), for a rectangular cross-section prismatic structure 100, a bent, shaped fiber-reinforced sheet 1A is placed at the corner, and combined with a straight fiber-reinforced sheet 1C placed on the flat surface, and connected with a lap joint, thereby orienting the fiber-reinforced plastic wires 2 in the circumferential direction of the prismatic member 100, thereby closing and reinforcing it.

[0122] Furthermore, for example, as shown in the examples in Figures 9(b) and (c), a bent, shaped fiber-reinforced sheet 1B can be placed at the inside corner and outside corner of the haunch, and at the concave portion of the haunch of a culvert, and combined with a straight fiber-reinforced sheet 1C placed on a flat portion and connected with a lap joint, thereby reinforcing a haunch-shaped structure 100. [Explanation of symbols]

[0123] 1. Shaped fiber-reinforced sheet 1a Semi-hardened fiber reinforced sheet 2a Semi-hardened fiber-reinforced plastic wire 3 Wire fixing materials (weft, mesh support sheet, flexible strip) 100 structures 200 Fiber-reinforced sheet bending device 201 Flexible Heater 300 Fiber-reinforced sheet bending device 301 Mold

Claims

1. A method for producing a shaped fiber-reinforced sheet for use in reinforcing a structure by adhering the sheet to a bent portion such as a corner of the structure with an adhesive, comprising: A semi-cured fiber reinforced plastic wire in which the matrix resin is in a B-stage state is stretched in the longitudinal direction to form a sheet, and the semi-cured fiber reinforced sheet in the B-stage state is clamped by a heating and shaping means and bent at a predetermined curvature, and then the shaped semi-cured fiber reinforced sheet is further heated to completely harden it. A method for producing a shaped fiber-reinforced sheet, comprising the steps of:

2. A method for manufacturing a shaped fiber-reinforced sheet comprising a plurality of fiber-reinforced plastic wires arranged in a curtain shape in the longitudinal direction and fixed to each other with a wire fixing material, the fiber-reinforced sheet having a bent portion that has been previously bent in order to be bonded to the corners of a structure with an adhesive to reinforce the structure, comprising: (a) A process for producing a semi-cured fiber-reinforced plastic strand in which a thermosetting resin is impregnated as a matrix resin into a reinforcing fiber bundle formed by bundling a large number of continuous reinforcing fibers, and then the matrix resin is heated by a heating means to be in a B-stage state in which the glass transition temperature (Tg value) of the matrix resin is 50 to 90° C.; (b) A step of preparing a semi-cured fiber-reinforced sheet in which the matrix resin is in a B-stage state by drawing a plurality of the semi-cured fiber-reinforced plastic strands in a longitudinal direction in a swirl shape and fixing the strands to each other with a strand fixing material; (c) clamping the semi-cured fiber reinforced sheet with a flexible heater and heating the entire semi-cured fiber reinforced sheet at a predetermined temperature in the range of 70 to 165°C; (d) bending the heated semi-cured fiber reinforced sheet at a predetermined curvature to give it a shape; (e) holding the semi-cured fiber reinforced sheet that has been bent at the predetermined curvature between the flexible heaters at a temperature of 100° C. or more and 165° C. or less to completely cure the matrix resin; (f) cooling the completely cured fiber reinforced sheet while being clamped by the flexible heater, and then removing the fiber reinforced sheet; A method for producing a shaped fiber-reinforced sheet, comprising:

3. A method for manufacturing a shaped fiber-reinforced sheet comprising a plurality of fiber-reinforced plastic wires arranged in a curtain shape in the longitudinal direction and fixed to each other with a wire fixing material, the fiber-reinforced sheet having a bent portion that has been previously bent in order to be bonded to the corners of a structure with an adhesive to reinforce the structure, comprising: (a) A process for producing a semi-cured fiber-reinforced plastic strand in which a thermosetting resin is impregnated as a matrix resin into a reinforcing fiber bundle formed by bundling a large number of continuous reinforcing fibers, and then the matrix resin is heated by a heating means to be in a B-stage state in which the glass transition temperature (Tg value) of the matrix resin is 50 to 90° C.; (b) A step of preparing a semi-cured fiber-reinforced sheet in which the matrix resin is in a B-stage state by drawing a plurality of the semi-cured fiber-reinforced plastic strands in a longitudinal direction in a swirl shape and fixing the strands to each other with a strand fixing material; (c) heating the entire semi-cured fiber-reinforced sheet at a predetermined temperature in the range of 55 to 165°C; (d) a step of sandwiching and bending the heated semi-cured fiber reinforced sheet between an upper mold formed in a convex shape with a predetermined curvature and a lower mold formed in a concave shape complementary to the upper mold, to give it a shape; (e) a step of holding the semi-cured fiber reinforced sheet, which has been bent to a predetermined curvature, between the upper mold and the lower mold at a temperature of 100° C. or more and 165° C. or less to completely cure the matrix resin; (f) cooling the completely cured fiber reinforced sheet while being sandwiched between the upper mold and the lower mold, and then separating the upper mold and the lower mold to remove the fiber reinforced sheet; A method for producing a shaped fiber-reinforced sheet, comprising:

4. A sheet-like semi-cured fiber-reinforced sheet, which is formed by aligning semi-cured fiber-reinforced plastic strands, in which the matrix resin is in a B-stage state, in a longitudinal direction in a curtain-like shape and fixing the strands together with a strand fixing material.

5. A fiber-reinforced sheet is formed by impregnating a reinforcing fiber bundle, which is a bundle of many continuous reinforcing fibers, with a matrix resin, and then aligning a plurality of hardened continuous fiber-reinforced plastic strands in a longitudinal direction in a curtain-like shape and fixing the strands to each other with a strand fixing material. The fiber-reinforced sheet is a shaped fiber-reinforced sheet having a bent portion that has been previously bent in order to be bonded to the corners of a structure with an adhesive to reinforce the structure, The matrix resin has a glass transition temperature (Tg value) of 100°C or higher, and is characterized in that it cannot be bent again even if it is heated to a temperature equal to or higher than the Tg value.

6. The reinforcing fiber bundle is twisted 5 to 100 times per meter, and the fiber-reinforced plastic strand has a diameter of 0.5 to 5 mm and a substantially circular cross-sectional shape. The shaped fiber-reinforced sheet according to claim 5.

7. The shaped fiber-reinforced sheet according to claim 5 or 6, characterized in that the overall shape of the shaped fiber-reinforced sheet is "L"-shaped or "U"-shaped, the radius of curvature (Ra) of the bent portion subjected to bending processing is 10 mm or more, and the tensile strength is 3500 N / mm2 or more.

8. The shaped fiber-reinforced sheet according to claim 7, characterized in that the reinforcing fibers of the fiber-reinforced plastic strand are inorganic fibers such as carbon fibers, glass fibers, and basalt fibers; metal fibers such as boron fibers, titanium fibers, and steel fibers; and organic fibers such as aramid, PBO (polyparaphenylene benzbisoxazole), polyamide, polyarylate, polyester, and high-strength polyester; used alone or in a hybrid form by mixing multiple types.

9. The shaped fiber-reinforced sheet according to claim 7, characterized in that the matrix resin of the fiber-reinforced plastic strand is a thermosetting resin such as a heat-curing epoxy resin, a vinyl ester resin, an MMA resin, an unsaturated polyester resin, or a phenolic resin.

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