JP2017056737A - Reinforcing fiber sheet for vartm - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reinforcing fiber sheet for VaRTM (Vacuum Assisted Resin Transfer Molding) and an FRP structure molding method, capable of maintaining good resin impregnation property without losing fluidity of injection resin, in molding of an FRP structure by a VaRTM method, and thereby capable of improving productivity of molding.SOLUTION: A reinforcing fiber sheet 10 for use in a VaRTM method is characterized by: forming reinforcing fiber bundles 11 by bundling up fabric strands 14 formed by aligning and converging a large number of reinforcing fibers f in one direction with covering yarns 15 along a longitudinal direction of the strands 14; forming a reinforcing fiber bundle layer 12 by aligning a large number of reinforcing fiber bundles 11 in parallel and very closely each other along the longitudinal direction; and making the reinforcing fiber bundle layer 12 into an integrated sheet-like form by fusion-bonding the covering yarns 15 to the fabric strands 14 adjacent to each other by heating and pressing the reinforcing fiber bundle layer.SELECTED DRAWING: Figure 1

Description

  The present invention is a large fiber reinforced plastic (FRP) structure in which, for example, carbon fiber is used as a reinforcing fiber used in, for example, wind turbine blades, vehicles, ships, etc. The present invention relates to a reinforcing fiber sheet for VaRTM for producing a product. The present invention also relates to an FRP structure molding method using such a VaRTM reinforcing fiber sheet and an FRP structure molded by such a molding method.

  The VaRTM method is characterized by the use of dry (non-impregnated) reinforcing fiber sheets that do not contain resin, and are laminated in advance according to the shape of the product, sewed, or fused in the necessary direction. The product is shaped so that it has the necessary strength (preform). For example, it is put into a mold, or sealed with a film, vacuumed to inject and cure the resin, and then removed from the mold. This is the construction method.

Currently, a large FRP structure (molded body) used for, for example, a windmill blade, a vehicle, a ship, and the like is manufactured by the VaRTM method, but a large FRP structure is manufactured by the VaRTM method. In some cases, the following is required: That means
(1) The bending strength of the molded FRP is 1000 N / mm ² or more.
(2) The reinforcing fiber cross-sectional area ratio in the final molded product, that is, the reinforcing fiber content (Vf) is 50% or more.
(3) The flow of the injected resin is good at the time of VaRTM molding.
Is needed.

  As shown in FIG. 7 attached to the present application, the present patent applicant, as shown in FIG. 7 attached to the present application, forms a fiber strand 14 formed by aligning a plurality of reinforcing fibers such as carbon fibers f in one direction in the longitudinal direction. A reinforcing fiber sheet 10A in which a number of reinforcing fiber bundles 11 formed by bundling with a bundling member (covering yarn) 15 are aligned along the longitudinal direction and held by a resin-permeable support 13 is proposed. did.

  The reinforcing fiber sheet 10A described in Patent Document 1 is particularly useful for reinforcing civil engineering structures and as an intermediate base material for fiber-reinforced plastic molded products.

Japanese Patent No. 4236478

  That is, in the reinforcing fiber sheet 10A described in Patent Document 1 shown in FIG. 7, the fiber strands 14 aligned along the longitudinal direction are bundled by the bundling member 15, and the porosity (Sr) is set to 30 to 90. %, And a gap (g) of 0.1 to 5.0 mm is provided between the reinforcing fiber bundles 11 and 11. Each reinforcing fiber bundle 11 is integrally held by a resin permeable support 13 and is formed into a sheet shape.

  Note that the porosity (Sr) refers to the cross-sectional area of the reinforcing fiber bundle 11 surrounded by the inner peripheral portion of the bundle member 15 as Sb and the fiber strand 14 surrounded by the bundle member 15 with reference to FIG. When the sum of the cross-sectional areas fs of the reinforcing fibers f forming S is Ss, the porosity is Sr = (Sb−Ss) / Sb.

  The reinforcing fiber sheet 10A described in Patent Document 1 can improve the fluidity of the resin when the reinforcing fiber sheet 10A is used for reinforcing a structure of a civil engineering building, for example, by using the above configuration, and is useful. It is.

  The present inventors have demonstrated that the reinforcing fiber sheet 10A described in Patent Document 1 satisfies the requirements described in the above items (1) to (3) and exhibits sufficient performance as a reinforcing fiber sheet for VaRTM. A research experiment was conducted on whether to obtain it.

  As a result of our research experiments, when producing a large FRP structure such as a spar portion of a blade for a windmill, for example, when the molding method or molding resin is greatly different from that at the time of structural reinforcement of a civil engineering building, It was found that the following configuration is important. That is, the condition of the covering when the fiber strands are bundled by the bundling member is optimized, and the gap (g) formed between the fiber strands is substantially 0 (zero). By holding each fiber strand integrally using a ring thread, that is, by not using a resin-permeable support that has been used to hold each fiber strand in the past (1) It has been found that a reinforcing fiber sheet for VaRTM that satisfies the necessary conditions described in (3) can be produced.

  An object of the present invention is to provide a VaRTM reinforcing fiber sheet that can maintain good resin impregnation and improve molding productivity without impairing the fluidity of the injected resin in molding of an FRP structure by the VaRTM method. And an FRP structure molding method.

  Another object of the present invention is to provide a good VaRTM reinforcement capable of increasing the fiber content Vf of reinforcing fibers (cross-sectional area ratio of reinforcing fibers per unit cross-sectional area) and increasing bending strength. It is providing a fiber sheet, an FRP structure molding method, and an FRP structure.

The above object is achieved by the VaRTM reinforcing fiber sheet, the FRP structure molding method, and the FRP structure according to the present invention. In summary, according to the first aspect of the present invention, the reinforcing fiber sheet is arranged in a predetermined shape, sealed with an upper mold frame or a film, and a resin is injected into the reinforcing fiber sheet under vacuum to be cured. The reinforcing fiber sheet used in the VaRTM method for molding a reinforced plastic structure,
A number of reinforcing fibers are aligned in one direction and bundled fiber strands are bundled by covering yarn along the longitudinal direction to form a reinforcing fiber bundle.
A plurality of the reinforcing fiber bundles are arranged in parallel along the longitudinal direction and in close contact with each other to form a reinforcing fiber bundle layer,
VaRTM reinforcement, wherein the reinforcing fiber bundle layer is heated and pressed to fuse the covering yarn to the adjacent fiber strands so that the reinforcing fiber bundle layer is formed into an integral sheet. A fiber sheet is provided.

  According to an embodiment of the present invention, the fiber strand is formed by converging 1000 to 100,000 reinforcing fibers.

  According to another embodiment of the present invention, the covering yarn is a yarn formed by converging a plurality of organic fibers, and the covering yarn is 15-40 per 10 cm in the longitudinal direction of the fiber strand. Wound by the number of windings.

  According to another embodiment of the present invention, the covering yarn is wound around the fiber strand by braiding, flat winding, S winding and Z winding, or either S winding or Z winding. .

According to another embodiment of the present invention, when winding the covering yarn around the fiber strand,
The covering yarn is given a tension of 50 to 200 g per one yarn, and the fiber strand is given a tension of 100 to 500 g per one fiber strand.

According to another embodiment of the present invention, the fiber basis weight of the reinforcing fiber bundle layer is 300 to 2000 g / m ² .

  According to another embodiment of the present invention, the covering yarn is a yarn formed of resin fibers having a low melting point of 60 to 150 ° C. Alternatively, the covering yarn is a yarn whose surface is coated with a low melting point resin having a temperature of 60 to 150 ° C.

  According to another embodiment of the present invention, the reinforcing fiber is an inorganic fiber such as carbon fiber or glass fiber, or an organic fiber such as aramid fiber, PBO fiber, basalt fiber, polyamide fiber, polyester fiber, or polyarylate fiber. One or more of these are mixed and used.

According to the second aspect of the present invention, the reinforcing fiber sheet is arranged in a predetermined shape, hermetically sealed with an upper mold or a film, and evacuated to inject the resin into the reinforcing fiber sheet and harden the fiber-reinforced plastic structure. In the fiber reinforced plastic structure molding method by the VaRTM method of molding
The reinforcing fiber sheet is any one of the above-described VaRTM reinforcing fiber sheets. A method for molding a fiber-reinforced plastic structure is provided.

  According to one embodiment of the present invention, the injected resin has a viscosity at the time of resin injection of 30 to 300 mPa · s.

  According to another embodiment of the present invention, the injection resin is an epoxy resin, a polyester resin, a vinyl ester resin, an MMA resin, an unsaturated polyester resin, or a phenol resin.

  According to the third aspect of the present invention, there is provided a fiber reinforced plastic structure characterized by being molded by any one of the fiber reinforced plastic structure molding methods described above.

According to one embodiment of the present invention, the fiber reinforced plastic structure has a bending strength of 1000 N / mm ² or more.

  According to another embodiment of the present invention, the fiber reinforced plastic structure has a reinforcing fiber cross-sectional area ratio (Vf) of 50% or more.

  According to the present invention, in molding of an FRP structure by the VaRTM method, the fluidity of the injected resin can be increased to improve the resin impregnation property, and the molding productivity can be improved. In addition, according to the present invention, the reinforcing fiber content Vf (cross-sectional area ratio of reinforcing fibers per unit cross-sectional area) can be increased as compared with the conventional molding of FRP structures, and the tension, bending, The compression strength can be increased.

It is a perspective view which shows one Example of the reinforced fiber sheet which concerns on this invention. It is sectional drawing of one Example of the reinforced fiber sheet which concerns on this invention, and is a figure explaining the preparation process of a reinforced fiber sheet. It is a perspective view which shows one Example of a reinforced fiber bundle. It is sectional drawing of one Example of a reinforced fiber bundle. It is a schematic block diagram of one Example of the shaping | molding apparatus for implementing a VaRTM construction method. It is a schematic block diagram of the other Example of the shaping | molding apparatus for implementing a VaRTM construction method. It is a perspective view explaining the conventional reinforcing fiber sheet.

  Hereinafter, the VaRTM reinforcing fiber sheet, FRP structure molding method, and FRP structure according to the present invention will be described in more detail with reference to the drawings.

Example 1
First, the method for molding the VaRTM reinforcing fiber sheet and the FRP structure according to the present invention will be described.

  The feature of the present invention is that, when a large FRP (fiber reinforced plastic) structure such as a windmill blade, a vehicle, a ship or the like is manufactured by the VaRTM method, the reinforcing fiber content Vf is high and the flow of the injected resin is high. It is to use a reinforcing fiber sheet having good properties.

As will be described in detail later, the present inventors have described the above-described reinforcing fiber sheet 10 according to the present invention as shown in FIGS. 1 and 2, which is required when a large FRP structure is produced by the VaRTM method. Requirements described in items (1) to (3), that is,
(1) The bending strength of the molded FRP is 1000 N / mm ² or more.
(2) The reinforcing fiber cross-sectional area ratio (Vf) in the final molded product is 50% or more.
(3) The flow of the injected resin is good at the time of VaRTM molding.
It was found that it satisfied.

(Reinforcement fiber sheet for VaRTM)
1 and 2 show an embodiment of a reinforcing fiber sheet according to the present invention. According to the present embodiment, the reinforcing fiber sheet 10 is a reinforcing fiber formed by bundling a plurality of reinforcing fibers f in one direction and bundling the fiber strands 14 that are converged by the covering yarns 15 along the longitudinal direction. It has a bundle 11. In the reinforcing fiber sheet 10, a large number of reinforcing fiber bundles 11 are drawn in parallel along the longitudinal direction and in close contact with each other to form a reinforcing fiber bundle layer 12. In the description of the present specification and claims, “closely” does not necessarily mean that the adjacent reinforcing fiber bundles 11 are in complete contact with each other. By pressing the reinforcing fiber bundle layer 12, the reinforcing fiber bundles 11 are crushed, and the adjacent reinforcing fiber bundles 11 are in contact with each other and are also arranged in close proximity.

  The reinforcing fiber bundle layer 12 is heated and pressurized from one or both sides by a heating and pressurizing means (not shown), whereby a bundle member that bundles the fiber strands 14, that is, a covering yarn 15 is formed. The adjacent reinforcing fiber bundles 11, that is, the fiber strands 14 are fused, and the adjacent covering yarns are fused, and the reinforcing fiber bundles 11 are joined together to form an integral sheet. Is done.

  Specifically, as shown in FIGS. 2 (a) and 2 (b), the reinforcing fiber bundle layer 12 is heated by a heating means such as a heating furnace so that the reinforcing fiber bundle 11 is melted by the covering yarn 15. Heat to above. Thereafter, the reinforcing fiber bundle layer 12 is preferably pressed from both sides by a pressing means such as a cooling roller, so that the reinforcing fiber bundles 11 are crushed, and the adjacent reinforcing fiber bundles 11 and 11 are mutually connected. It will be in close contact. At the same time, the covering yarn 15 heated to the melting point or more of each reinforcing fiber bundle 11 is fused to the adjacent reinforcing fiber bundle 11 (that is, fiber strand 14). Of course, the adjacent covering yarns 15 may also be fused. Since the cooling roller has a temperature equal to or lower than the melting point of the covering yarn 15, the covering yarn 15 is not fused.

  1 and 2A, the cross-sectional shape of the reinforcing fiber bundle 11 (that is, the fiber strand 14) is circular, but as understood in the above description, the reinforcing fiber bundle By pressing the layer 12 with a cooling roller, it is formed into a flat shape as shown in FIG. Of course, the reinforcing fiber bundle 11 may be formed in a flat shape in the step before heating and pressing, as desired.

  The reinforcing fiber sheet 10 will be described in more detail.

  As will be better understood with reference also to FIGS. 3 and 4, according to the present invention, the reinforcing fiber bundle 11 has a large number, for example, 1000 to 100,000, generally 3000 to 60000. Reinforced fibers (monofilaments) f are aligned in one direction, preferably arranged in parallel so that the fibers do not overlap, or loosely twisted as necessary to converge fiber strands 14 and fiber strands 14 And the covering yarn 15 that bundles the outer peripheries.

  As the reinforcing fiber, carbon fiber can be most preferably used, but is not limited to this, and is not limited thereto. Carbon fiber, inorganic fiber such as glass fiber, or aramid fiber, PBO fiber, basalt fiber, polyamide fiber, polyester One or more organic fibers such as fibers and polyarylate fibers can be mixed and used.

  Further, as the covering yarn 15 used as a bundling member, various materials can be used, but a low melting point type resin fiber, for example, a yarn formed by converging a plurality of organic fibers such as polyester fiber, can do. In addition, a yarn coated with a low melting point resin may be used.

  The melting point of the covering yarn, that is, the low melting point resin fiber or the low melting point resin covering the yarn is preferably about 60 to 150 ° C, particularly preferably 80 to 120 ° C.

  In this embodiment, as the covering yarn 15, for example, a yarn made of 20 to 100 denier polyester fiber or a yarn produced by converging a plurality of such polyester fibers is used. Could get. At this time, the covering pitch P of the covering yarn 15 is suitably 15 to 40 windings per 10 cm in the longitudinal direction of the fiber strand 14. More preferably, it is 25 to 33 times (in FIG. 1, P = 3 to 4 mm).

  In this embodiment, two covering yarns 15 (yarns 15a and 15b) are used, and each yarn 15a and 15b is wound around the fiber strand 14 by 2P. The yarns 15a and 15b are preferably wound so as to cross each other. In particular, the covering yarns 15a and 15b are preferably a system in which the S winding and Z winding covering yarns 15a and 15b are moved up and down by braiding. However, flat winding is also possible without being limited to braided knitting. Moreover, it is also possible to use any one winding mode of S winding and Z winding. However, in the case of flat winding, since the covering yarn 15 is easily displaced, care must be taken in handling the covered reinforcing fiber bundle 11.

  In the present embodiment shown in FIG. 1 to FIG. 4, an embodiment in which two yarns 15 (15a, 15b) are used as the covering yarn 15 and the fiber strands 14 are bundled by overwinding is shown. Of course, the number of yarns may be one, or three or more yarns may be used.

  In the present invention, the outer periphery of the fiber strand 14 needs to be tightly squeezed by the covering yarn 15 (15a, 15b). Accordingly, the covering yarn 15 (15a, 15b) needs a tension of 50 to 200 g per yarn 15a, 15b during covering. When the tension is less than 50 g / strand, particularly 20 g / strand or less, the thread 15 is not fastened to the fiber strand 14. Conversely, when the tension exceeds 200 g / strand, particularly when the tension is 300 g / strand or greater, the yarn 15 is bent. It becomes easy.

  Further, in order to make the fiber strands difficult to bend at the time of covering, the fiber strands themselves are more than 200 g per fiber strand, that is, for example, one fiber strand 14 having 50K (50000) reinforcing fibers. It is necessary to apply tension. If it is less than 100 g / piece, it becomes easy to bend by the tension of the yarn 15 at the time of covering. In general, the fiber strand 14 having several thousand to 100,000 reinforced fibers (f) is usually 100 to 500 g / piece (100 g / piece or more, 500 g / piece or less).

  According to the present invention, as described above, the reinforcing fiber bundle 11 having the configuration according to the present invention needs to increase the Vf of the structure (molded body) by VaRTM molding. No. 15 tightly bundles the outer periphery of the fiber strand 14. Further, the resin permeable support 13 (see FIG. 7) that has been conventionally used is not used.

In the present invention, the reinforcing fiber sheet not using the resin permeable support has the following features. That means
(1) Since the thickness of the resin permeable support is eliminated, the fiber content (Vf) of the reinforcing fibers can be increased. Unlike the civil engineering and construction field, in the VaRTM molding method, it is particularly important to increase Vf in terms of FRP performance, and it becomes a factor that Vf decreases even with the thickness of the resin-permeable support, and such factors must be eliminated as much as possible. There is.
(2) From the above, the physical properties of the reinforcing fiber sheet are improved and the handleability is also improved.
(3) Since the resin-permeable support is not used, the cost of the reinforcing fiber sheet itself can be reduced. In addition, when manufacturing the reinforcing fiber sheet, the resin permeable support supply equipment that is conventionally required is not required, and the manufacturing equipment can be simplified.
It has the features such as.

  According to the present invention, the reinforcing fiber bundle layer 12 is formed by aligning a number of reinforcing fiber bundles 11 along the longitudinal direction. The reinforcing fiber bundle layer 12 is formed as shown in FIGS. The reinforcing fiber bundle 11 can be formed by one layer, but is not limited to this, and the reinforcing fiber bundle 11 can be formed by laminating a plurality of layers, for example, two to three layers.

With the above-described configuration, the reinforcing fiber bundle layer 12 can have a fiber basis weight of 300 g / m ² or more and 2000 g / m ² or less, can remarkably improve physical properties (such as bending strength), and VaRTM molding. Good resin impregnation property (that is, resin fluidity) in the method can be maintained. When the reinforcing fiber bundle layer 12 exceeds 2000 g / m ² , the fluidity is deteriorated even in the VaRTM molding method.

The reinforcing fiber sheet 10 according to the present invention produced as described above has the following features when summarized. That means
(1) Since a large number of reinforcing fibers f converge, the resin impregnation property (resin fluidity) into the reinforcing fiber bundle 11 is improved by capillary action.
(2) Since the reinforcing fiber bundle is tightly converged, the thickness does not increase even if the resin is impregnated, and the Vf of the reinforcing fiber is increased. Vf is 50% or more, usually 65% or less, that is, 50 to 65%. On the other hand, conventionally, in the case of structural reinforcement, Vf is about 20 to 40%.
(3) Since the reinforcing fibers f are tightly converged by the covering yarn 15 so that the reinforcing fibers f are not scattered and the generation of fluff can be reduced, the physical properties and handling properties are improved.
(4) By firmly converging the reinforcing fibers f, the resin fluidity is good at the time of VaRTM molding, and the productivity is improved.

  Next, the VaRTM method using the reinforcing fiber sheet 10 having the above configuration will be described.

(VaRTM method)
When the reinforcing fiber sheet 10 having the above-described configuration is used for molding an FRP structure by the VaRTM method, it can improve the resin impregnation property by increasing the fluidity of the injected resin and improve the molding productivity. . Moreover, the physical properties of the FRP structure (molded product) can be improved.

  As described above, the FRP structure using the reinforcing fiber sheet 10 having the configuration according to the present invention increases the reinforcing fiber content Vf as compared with the FRP structure manufactured using the conventional reinforcing fiber sheet 10A. Can do. Moreover, as will be understood from the results of experiments conducted by the inventors, which will be described later, the reinforcing fiber sheet 10 having such a configuration has good resin flowability compared to the conventional reinforcing fiber sheet 10A. It was found that The reason is that, particularly in the VaRTM method, the viscosity of the injected resin to be used is low (viscosity at the time of injection is 30 to 300 mPa), so that the injected resin enters the reinforcing fiber bundles 11 to form the reinforcing fibers. This seems to be due to the capillary phenomenon caused by f flowing between the reinforcing fibers f.

  FIG. 5 shows a schematic configuration of an example of a molding apparatus 100 used in the VaRTM method. In this example, the molding apparatus 100 puts the reinforcing fiber sheet 10 into a mold (mold) 101, and a resin distribution medium 102 and a vacuum bag (film) 103 are set thereon. Resin R is injected between the resin distribution medium 102 and the mold 101 from the resin injection device 104 disposed adjacent to the mold 101. Further, the vacuum bag 103 is evacuated, whereby the reinforcing fiber sheet 10 is impregnated with the resin R. The reinforcing fiber sheet 10 impregnated with the resin R is heated together with the molding die 101 in a heating device such as a heating plate or an oven, and the resin R is cured. Thereafter, the resin-impregnated and cured reinforcing fiber sheet 10 is removed from the mold 101 to obtain a product (molded product of fiber-reinforced plastic structure). Of course, when a room-temperature curable resin R is used, a heating device or the like is unnecessary.

  FIG. 6 shows a schematic configuration of another example of the molding apparatus 100. In this example, the molding apparatus 100 is different in that an upper mold 101b is disposed instead of the film 103 in the molding apparatus 100 shown in FIG. That is, in the molding apparatus 100 of this example, the molding die 101 is configured by the lower mold frame 101a and the upper mold frame 101b, but the other configurations and functions are the same. Components having the same configuration and function are denoted by the same reference numerals, and the above description related to FIG. Of course, also in this example, when the room temperature curable resin R is used, a heating device or the like is unnecessary.

  As described above, according to the present invention, the reinforcing fiber sheet 10 is arranged in a predetermined shape, sealed with the upper mold frame 101b or the film 103, and evacuated to inject the resin into the reinforcing fiber sheet 10 to be cured, thereby reinforcing the fiber. A fiber reinforced plastic structure molding method by the VaRTM method for molding a plastic structure is provided.

Here, the reinforcing fiber sheet 10 is as described above.
(A) The reinforcing fiber bundle 11 is formed by bundling the fiber strands 14 converged by aligning a large number of reinforcing fibers f in one direction with the covering yarns 15 along the longitudinal direction;
(B) A large number of reinforcing fiber bundles 11 are aligned in parallel along the longitudinal direction and in close contact with each other to form a reinforcing fiber bundle layer 12;
(C) By heating and pressurizing the reinforcing fiber bundle layer 12, the covering yarns 15 are fused to the adjacent fiber strands 14, and the reinforcing fiber bundle layer 12 is formed into an integral sheet.
It is supposed to be configured.

  Further, as the injection resin, VaRTM resin having a viscosity of 30 to 300 mPa · s at the time of resin injection is used.

  In this example, an epoxy resin was used as the VaRTM resin. In addition to the epoxy resin, a polyester resin having a viscosity of 30 to 300 mPa · s at the time of resin injection (temperature 25 ° C. as an example), Vinyl ester resin, MMA resin, unsaturated polyester resin, phenol resin, and the like can be used.

The reinforcing fiber sheet 10 of the present invention can increase the reinforcing fiber content Vf as compared with the conventional reinforcing fiber sheet 10A shown in FIG. As described above, according to the present invention, the Vf of the reinforcing fiber (the cross-sectional area ratio of the reinforcing fiber per unit cross-sectional area) is set to 50% or more as compared with the molding of the FRP structure using the reinforcing fiber sheet 10A. Thus, the fiber basis weight of the reinforcing fiber bundle layer 12, that is, the reinforcing fiber sheet 10, can be about 300 to 2000 g / m ^2, and the bending strength and the like of the molded FRP structure can be increased. .

  Moreover, as described above, the reinforcing fiber sheet 10 having such a configuration, when used for molding an FRP structure by the VaRTM method, has a good resin impregnation property without reducing the fluidity of the injected resin. Molding productivity can be improved.

  As described above, the reinforcing fiber sheet 10 of the present invention has the feature that the fiber strands 14 are tightly converged by the covering yarns 15 so that the fibers are not easily bent. Is good.

Experimental Example In order to verify the working effect of the FRP structure molding method and VaRTM reinforcing fiber sheet of the present invention, in Experimental Example 1, a reinforcing fiber sheet using carbon fibers as reinforcing fibers, that is, impregnation of a carbon fiber sheet An experiment was conducted to evaluate the sex. In Experimental Example 2, it was confirmed by the bending performance of CFRP (carbon fiber reinforced plastic) whether the carbon fiber sheet of the present invention having a high Vf had a difference in physical properties compared to other sheets. Experimental examples 1 and 2 will be described below.

Experimental example 1
The carbon fiber sheet 10 of this example (FIG. 1) and the carbon fiber sheet 10A of the comparative example (FIG. 7) used in Experimental Example 1 were produced as follows.

  As the carbon fiber strands 14 in the carbon fiber sheets 10 and 10A, PAN-based carbon fiber strands having an average diameter of 7 μm and a convergence number of 50000 were used as the reinforcing fibers f. This carbon fiber strand 14 uses two yarns made of 50 denier polyester fiber as the covering yarn 15, and the covering yarns 15a and 15b are moved up and down by braided knitting S winding and Z winding. The carbon fiber strand 14 was wound around the outer periphery. The covering pitch P was set to 33 times (P = 3 mm) per 10 cm in the longitudinal direction of the carbon fiber strand 14.

  At this time, the covering yarn 15 was given a tension in the range of 50 to 80 g / piece, and the carbon fiber strand 14 was given a tension of 200 g / piece to cover the carbon fiber strand 14. . In this way, a carbon fiber bundle 11 having a shape as shown in FIG. 3 was obtained. The carbon fiber bundle 11 did not bend along the longitudinal direction, and showed very good linearity.

In the carbon fiber sheet 10 of this example, the carbon fiber bundles 11 produced as described above are arranged in parallel and in close contact, heated to 140 ° C. in a heating furnace, and then the carbon fiber bundles are cooled using a cooling roller. 11 was pressurized. Thereby, in the carbon fiber sheet 10 of the present embodiment, as shown in FIG. 2B, the covering yarns 15 are fused to the adjacent carbon fiber bundles 11, and the carbon fibers lined up in parallel. There was no gap between the bundles 11 and 11, and the gap (g) was substantially 0 (zero). The fiber basis weight of the carbon fiber bundle layer 12, that is, the carbon fiber sheet 10 was 1800 g / m ² .

Further, the carbon fiber sheet 10A of the comparative example was prepared by arranging the carbon fiber bundles 11 prepared as described above in parallel on a resin-permeable (that is, mesh-like) support sheet 13 and applying heat and pressure. However, as shown in FIG. 7, a gap (g) of 2 mm was provided between the carbon fiber bundles 11 and 11. The fiber basis weight of the comparative carbon fiber sheet 10A was 600 g / m ² .

  The mesh-like support sheet 13 was a biaxial mesh-like support sheet using glass fibers (number 300d, number of driven-in pieces / 10 mm) as the warp 16 and the weft 17. The distance between the warp yarn 16 and the weft yarn 17 of the biaxial mesh support sheet 13 was 10 mm.

  The carbon fiber sheets 10 and 10A thus produced had a width (W) of 500 mm and an axial length of 100 m.

  Using the carbon fiber sheet 10 of this example having the above-described configuration and the carbon fiber sheet 10A of the comparative example, CFRP plates were respectively produced by the VaRTM method.

  The molding apparatus 100 used in this experiment is an apparatus that implements the VaRTM method described with reference to FIG. 5, and a carbon fiber sheet 10 (10A) is put into a mold (molding mold) 101, and a resin is placed thereon. The distribution medium 102 and the vacuum bag 103 were set. The resin R was injected between the resin distribution medium 102 and the mold 101 from the resin injection device 104 disposed adjacent to the mold 101, and the vacuum bag 103 was evacuated. As a result, the carbon fiber sheet 10 (10A) was impregnated with the resin R. The carbon fiber sheet 10 (10A) impregnated with the resin R was heated together with the mold 101 in a heating device (oven), and the resin R was cured. Thereafter, the resin-impregnated and cured carbon fiber sheet 10 (10A) was removed from the molding die 101 to obtain a product (molded body of carbon fiber reinforced plastic structure).

  The CFRP plate thus obtained had a width of 200 mm × a length of 2 m and a thickness of 2.0 mm. The resin R used in this example and comparative example is a low viscosity resin for VaRTM, and an epoxy resin for composite materials (general type “XNR / H6815” (trade name)) manufactured by Nagase ChemteX Corporation was used. . The viscosity of the resin was 260 mPa · s / 25 ° C. and 80 mPa · s / 40 ° C. The viscosity at the time of pouring into the mold, that is, the resin viscosity at a temperature of 25 ° C. was 260 mPa · s.

In this experiment, when the carbon fiber sheet 10 of this example was used and the total basis weight was 1800 g / m ² , the resin impregnation work was completed in about 0.5 hours (total molding work time 2.5 hours). And a good product could be obtained. This resin impregnation work time was comparable to the case where the carbon fiber sheet 10A of the comparative example was used. Moreover, Vf after VaRTM shaping | molding at the time of using the carbon fiber sheet 10 of a present Example was 58%. On the other hand, when the carbon fiber sheet 10A of the comparative example was used, Vf after VaRTM molding was 38%.

Experimental example 2
In order to verify the operational effects of the carbon fiber sheet 10 and the CFRP structure molding method of the present example, in Experimental Example 2, the bending strength of the CFRP structure when the carbon fiber sheet 10 of the present example was used was evaluated. An experiment was conducted to

(Test method)
Using the same carbon fiber sheet 10, 10A and resin as used in Experimental Example 1 shown in Table 1 and the experimental apparatus 100, CFRP plates of this example and a comparative example were produced. This CFRP plate was cut into a width of 12 mm and a length of 120 mm to prepare a bending test sample, and a three-point bending test by the JISK7203 method was performed. The test results are shown in Table 1.

  As a result of the experiment, as can be understood from Table 1, the present example has fewer voids and higher Vf (carbon fiber content) than the comparative example, so the bending stress of the CFRP plate is high. On the other hand, since the comparative example has a gap (g) between the carbon fiber bundles 11 and 11 and uses a resin-permeable support, as described in Experimental Example 1, the resin impregnation property is Although it is good, it can be seen that Vf is lower than others and bending stress is low.

  The carbon fiber sheet 10 of the present embodiment can increase its carbon fiber content Vf as compared to the carbon fiber sheet 10A of the comparative example. Thereby, according to this invention, compared with the shaping | molding of the CFRP structure by the conventional carbon fiber sheet | seat 10A, Vf (cross-sectional area ratio of the carbon fiber per unit cross-sectional area) of carbon fiber can be made high, and it shape | molded The bending strength of the CFRP structure can be increased.

  In addition, when the carbon fiber sheet 10 having such a configuration is used for molding a CFRP structure by the VaRTM method, the fluidity of the injected resin is not lowered, the resin impregnation property is good, and the molding production Can be improved. In the carbon fiber sheet 10 of the present invention, since the carbon fiber strands 14 are tightly bundled by the covering yarns 15, the fibers are difficult to bend, the productivity is good, and the performance is good.

  In the above experimental example, the case where carbon fibers are used as the reinforcing fibers has been described. However, similar results could be obtained even when reinforcing fibers other than carbon fibers were used.

10 Carbon fiber sheet (reinforced fiber sheet)
11 Carbon fiber bundle (reinforced fiber bundle)
12 Carbon fiber bundle layer (reinforced fiber bundle layer)
14 Carbon fiber strand (fiber strand)
15 (15a, 15b) Covering thread

The present invention is a large fiber reinforced plastic (FRP) structure in which, for example, carbon fiber is used as a reinforcing fiber used in, for example, wind turbine blades, vehicles, ships, etc. The present invention relates to a reinforcing fiber sheet for VaRTM for producing a product .

An object of the present invention is to provide a VaRTM reinforcing fiber sheet that can maintain good resin impregnation and improve molding productivity without impairing fluidity of the injected resin in molding of an FRP structure by the VaRTM method. Is to provide

Another object of the present invention is to provide a good VaRTM reinforcement capable of increasing the fiber content Vf of reinforcing fibers (cross-sectional area ratio of reinforcing fibers per unit cross-sectional area) and increasing bending strength. it is to provide a fiber sheet.

The above objects are achieved by VaRTM reinforcing fibers sheets according to the present invention. In summary, according to the present invention , a reinforcing fiber sheet is arranged in a predetermined shape, sealed with an upper mold or a film, and a resin is injected into the reinforcing fiber sheet under vacuum to be cured. The reinforcing fiber sheet used in the VaRTM method for molding an object,
This reinforcing fiber bundle a large number of reinforcing fibers fiber strand is converged aligned in one direction are bundled by covering yarn in the longitudinal direction a large number, drawn in parallel along a longitudinal direction aligned sheet-like Having a reinforcing fiber bundle layer ,
The VaRTM reinforcing fiber sheet is provided in which the fiber strands adjacent to each other in the reinforcing fiber bundle layer are bonded by the fused covering yarn .

Hereinafter will be described in more detail with reference to VaRTM reinforcing fibers sheets according to the present invention with reference to the drawings.

Claims (15)

The reinforced fiber sheet is arranged in a predetermined shape, sealed with an upper mold or film, vacuumed, injected with resin into the reinforced fiber sheet and cured, and used in the VaRTM method of molding a fiber reinforced plastic structure. A reinforcing fiber sheet,
A number of reinforcing fibers are aligned in one direction and bundled fiber strands are bundled by covering yarn along the longitudinal direction to form a reinforcing fiber bundle.
A plurality of the reinforcing fiber bundles are arranged in parallel along the longitudinal direction and in close contact with each other to form a reinforcing fiber bundle layer,
VaRTM reinforcement, wherein the reinforcing fiber bundle layer is heated and pressed to fuse the covering yarn to the adjacent fiber strands so that the reinforcing fiber bundle layer is formed into an integral sheet. Fiber sheet.   The reinforcing fiber sheet for VaRTM according to claim 1, wherein the fiber strand is formed by converging 1000 to 100,000 reinforcing fibers.   The covering yarn is a yarn formed by converging a plurality of organic fibers, and the covering yarn is wound at a winding frequency of 15 to 40 times per 10 cm in the longitudinal direction of the fiber strand. The reinforcing fiber sheet for VaRTM according to claim 1 or 2, characterized by the above.   The covering yarn is wound around the fiber strand by braided knitting or flat winding by S winding and Z winding, or by S winding or Z winding. The reinforcing fiber sheet for VaRTM according to any one of the items. When winding the covering yarn around the fiber strand,
The covering yarn is provided with a tension of 50 to 200 g per one yarn, and the fiber strand is provided with a tension of 100 to 500 g per one fiber strand. The reinforcing fiber sheet for VaRTM according to any one of items 1 to 4. The fiber basis weight of the reinforcing fiber bundle layer, VaRTM reinforcing fiber sheet according to any one of claims 1 to 5, characterized in that a 300~2000g / m ^2.   The VaRTM reinforcing fiber sheet according to any one of claims 1 to 6, wherein the covering yarn is a yarn formed of resin fibers having a low melting point of 60 to 150 ° C.   The VaRTM reinforcing fiber according to any one of claims 1 to 7, wherein the covering yarn is a yarn whose surface is coated with a low melting point resin having a temperature of 60 to 150 ° C. Sheet.   The reinforcing fibers are used by mixing inorganic fibers such as carbon fibers and glass fibers, or organic fibers such as aramid fibers, PBO fibers, basalt fibers, polyamide fibers, polyester fibers, and polyarylate fibers. The VaRTM reinforcing fiber sheet according to any one of claims 1 to 8, wherein the reinforcing fiber sheet is for VaRTM. Fiber reinforced plastic by VaRTM method in which reinforced fiber sheets are arranged in a predetermined shape, sealed with an upper mold or film, vacuumed to inject resin into the reinforced fiber sheets and cured to form a fiber reinforced plastic structure In the structure molding method,
The fiber-reinforced plastic structure molding method, wherein the reinforcing fiber sheet is the VaRTM reinforcing fiber sheet according to any one of claims 1 to 9.   The fiber-reinforced plastic structure molding method according to claim 10, wherein the injected resin has a viscosity of 30 to 300 mPa · s at the time of resin injection.   The fiber-reinforced plastic structure molding method according to claim 11, wherein the injection resin is an epoxy resin, a polyester resin, a vinyl ester resin, an MMA resin, an unsaturated polyester resin, or a phenol resin.   A fiber-reinforced plastic structure formed by the fiber-reinforced plastic structure molding method according to any one of claims 10 to 12. The fiber reinforced plastic structure according to claim 13, wherein the fiber reinforced plastic structure has a bending strength of 1000 N / mm ² or more. The fiber-reinforced plastic structure according to claim 13 or 14, wherein the fiber-reinforced plastic structure has a reinforcing fiber cross-sectional area ratio (Vf) of 50% or more.

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