WO2013133437A1

WO2013133437A1 - High-basis-weight carbon fiber sheet for rtm process, and rtm process

Info

Publication number: WO2013133437A1
Application number: PCT/JP2013/056553
Authority: WO
Inventors: 宮尾　巻治; 小林　朗; 正棋荒添
Original assignee: 新日鉄住金マテリアルズ株式会社
Priority date: 2012-03-06
Filing date: 2013-03-05
Publication date: 2013-09-12
Also published as: JP6138045B2; JPWO2013133437A1

Abstract

A high-basis-weight carbon fiber sheet for an RTM process and an RTM process are provided. This high-basis weight carbon fiber sheet is produced using thick carbon fiber strands, so that the fiber sheet can attain a higher carbon fiber content Vf (the sectional area of carbon fiber per unit sectional area) than that attained by molding a stack of multiple sheets made of thin carbon fiber and thus can improve the performance of an FRP material. In a high-basis-weight carbon fiber sheet (10) for an RTM process, multiple singly twisted fiber bundles (11) or multiple unitedly twisted fiber bundles (12) are arranged in one direction in such a state that the fiber bundles (11) or (12) do not overlap each other, while the fiber bundles (11) or (12) are fixed to each other with a fixing fibrous material. The singly twisted fiber bundles (11) are each produced by: bundling 50000 to 60000 carbon fiber monofilaments (f) to form a carbon fiber strand (F); and twisting the carbon fiber strand (F) by 5 to 50 turns per meter. The unitedly twisted fiber bundles (12) are each produced by: assembling multiple carbon fiber strands (F) which are each obtained by bundling 50000 to 60000 carbon fiber monofilaments (f); and twisting the resulting assembly by 5 to 50 turns per meter. The high-basis-weight carbon fiber sheet (10) has a fiber basis weight of more than 800 to 6000g/m².

Description

High-weight carbon fiber sheet for RTM method and RTM method

In the present invention, for example, a large FRP material (fiber reinforced plastic material) used for wind turbine blades, vehicles, ships, etc. is an RTM method or a VaRTM method (hereinafter referred to as an RTM method) It is related to the high-weight carbon fiber sheet used in the production of the “RTM method” including the VaRTM method, and also relates to the RTM method using such a high-weight carbon fiber sheet. is there.

The RTM method is characterized by the use of dry (non-impregnated) reinforcing fiber sheets that do not contain resin, and the direction required by laminating, sewing, or fusing in accordance with the shape of the product. This is a method of making a product (preform) so that the required strength is obtained, placing it in a mold, injecting resin, and curing (heating if necessary) to make a product. Vacuuming is also performed at the time of resin injection, and it is particularly called the VaRTM method.
Currently, a large FRP material (fiber reinforced plastic material) used for, for example, a windmill blade, a vehicle, a ship, and the like is produced by the RTM method. However, such a large molded product often uses a glass mat or a non-woven fabric as the reinforcing fiber sheet.
In other words, when a large FRP material is produced by the RTM method, if a carbon fiber sheet produced by simply aligning carbon fibers in one direction is used, the orientation of carbon fibers tends to be disturbed during resin injection. Woven or knitted carbon fiber sheets, or unidirectional carbon fiber sheets that are stitched into a sheet shape are used, and carbon fiber sheets that have carbon fibers arranged in only one direction are completely not being used. That is, the carbon fiber sheet currently used is only used by laminating a plurality of woven fabrics having a basis weight of the sheet of 200 to 400 g / m ^{2 so} as to obtain a predetermined fiber basis weight.
However, the use of a woven or knitted carbon fiber sheet or a stitched carbon fiber sheet, etc., makes the production rate of the unidirectional carbon fiber sheet about 10 m / min, whereas the production rate of the sheet itself. Is about 1 m / min or less, the productivity is poor, and the cost is increased.
In particular, when a large-sized FRP material (fiber reinforced plastic material) used for a molded article having a large cross-sectional area, for example, a blade for a windmill, a vehicle, a ship, or the like, is produced, the number of laminated layers is increased, resulting in poor working efficiency. Further, when the number of laminated layers is large, a large amount of knitting yarns and knitting yarns enter, resulting in a decrease in strength, and the content of carbon fibers (Vf: the cross-sectional area ratio of carbon fibers per unit cross-sectional area) ).
Accordingly, the present inventors twisted each carbon fiber bundle (carbon fiber strand) constituted by converging tens of thousands of carbon fibers (filaments), and arranged the carbon fiber strands in one direction to form a carbon fiber sheet. As described in Patent Document 1, it was confirmed that the strength did not decrease by specifying the number of twists applied to the carbon fiber bundle (carbon fiber strand), and a predetermined number of twists were applied. A carbon fiber sheet made of a fiber bundle composed of a large number of carbon fiber filaments was proposed.

Japanese Patent No. 4667069

The carbon fiber sheet described in Patent Document 1 has excellent resin impregnation properties, but the fiber basis weight of the carbon fiber sheet is 50 to 800 g / m ² . Further, as described in Patent Document 1, the carbon fiber sheet having such a structure is attached with an adhesive impregnated for reinforcing a structure such as a bridge or an elevated road, When a fiber reinforced plastic product is produced by applying and impregnating a resin by up-up or the like, if the fiber basis weight exceeds 800 g / m ² , particularly if it exceeds 1000 g / m ² , the resin impregnation property deteriorates and becomes impractical. .
The inventor conducted further research and experiments based on the technique described in the above-mentioned Patent Document 1, and a fiber bundle in which the twisted resin is not impregnated, for example, 50K (the number of carbon fiber filaments is 50,000). ) And a high-weight carbon fiber sheet having a fiber basis weight exceeding 800 g / m ² , and using this carbon fiber sheet, a large molded product, for example, An attempt was made to produce a large FRP material (fiber reinforced plastic material) for use in windmill blades, vehicles, ships, and the like. As a result, even if the high-weight carbon fiber sheet using such large-diameter carbon fiber strands has a high basis weight exceeding 800 g / m ² , even if it is a high-weight carbon fiber sheet exceeding 1000 g / m ² , RTM It has been found that a large molded product can be produced very efficiently by the construction method.
The reason is,
(1) An extremely low viscosity resin (RTM resin) can be used in the RTM method.
That is, conventionally, the viscosity of a construction resin for civil engineering and construction using a unidirectional carbon fiber sheet is about 3000 to 10000 mPa · s / 23 ° C. Accordingly, it is extremely difficult to impregnate such a construction resin for civil engineering and construction into a carbon fiber sheet having a high basis weight exceeding 800 g / m ² , particularly exceeding 1000 g / m ² . On the other hand, the viscosity of the resin for RTM is about 30 to 300 mPa · s at the time of resin injection (temperature 25 ° C. as an example), and the fiber basis weight using a large-diameter carbon fiber strand is 800 g / m. ^2, greater even at high basis weight carbon fiber sheet exceeding even 1000 g / m ² is impregnated very efficiently. On the other hand, such a low viscosity RTM resin cannot be used as a construction resin for civil engineering and construction because the resin flows or droops when applied to a ceiling surface or a wall surface.
(2) Since the fiber is twisted, it is difficult for the fiber to flow when the resin is injected by the RTM method.
(3) Since there are many moldings with a thick molding thickness in the RTM method, a high-weight carbon fiber sheet can reduce the number of laminated sheets.
Because.
The present invention is based on the novel knowledge of the present inventors.
The object of the present invention is to use a carbon fiber sheet using thick carbon fiber strands, so that the carbon fiber Vf (carbon fiber per unit cross-sectional area) is compared with molding by stacking a plurality of thin carbon fiber strand sheets. An object of the present invention is to provide a high-weight carbon fiber sheet for an RTM method and an RTM method that can increase the cross-sectional area ratio) and improve the performance of the FRP material.
Another object of the present invention is a twist that can be used when a large FRP material having a fiber basis weight exceeding 800 g / m ² , for example, used for a windmill blade, a vehicle, a ship, etc., is produced by the RTM method. It is to provide a high-weight carbon fiber sheet for an RTM method and an RTM method using a carbon fiber strand having a large diameter of, for example, 50K, which is impregnated with resin.

The above object is achieved by the high-weight carbon fiber sheet for RTM method and the RTM method according to the present invention. In summary, the first aspect of the present invention is a single twisted fiber bundle produced by twisting 5 to 50 times per meter to a carbon fiber strand in which 50,000 to 60000 carbon fiber monofilaments are converged, or A plurality of carbon fiber strands in which 50,000 to 60,000 carbon fiber monofilaments are converged are combined and a twisted fiber bundle produced by twisting 5 to 50 times per meter is arranged in one direction so as not to overlap. Each of the single twisted fiber bundles or each of the twisted fiber bundles is fixed to each other with a fixing fiber material, and has a fiber basis weight of more than 800 g / m ² and 6000 g / m ² or less. This is a high-weight carbon fiber sheet for construction methods.
According to one embodiment of the present invention, a gap (g) of 0 to 2 mm is formed between each single twisted fiber bundle or each twisted fiber bundle.
According to another embodiment of the present invention, the twisted fiber bundle is formed by twisting 2 to 5 single fiber bundles.
According to another embodiment of the present invention, the fixing fiber material includes the single twisted fiber bundle or the single twisted fiber bundle in the direction perpendicular to the longitudinal direction of the single twisted fiber bundle or the twisted fiber bundle. A weft for knitting a twisted fiber bundle.
According to another embodiment of the present invention, the weft is a yarn made of glass fiber or organic fiber.
According to another embodiment of the present invention, the fixing fiber material is disposed on one side or both sides of each single twisted fiber bundle or each twisted fiber bundle arranged in one direction, and is bonded or melted. This is a worn mesh-like support sheet.
According to another embodiment of the present invention, the mesh-like support sheet is formed by orienting yarns made of glass fibers uniaxially, biaxially, or triaxially and coated on the surface of the yarn. Is bonded or fused to each single twisted fiber bundle or each single twisted fiber bundle.
In the RTM method of inserting the carbon fiber sheet into the mold, injecting and curing the resin, and molding the fiber reinforced plastic material,
The carbon fiber sheet is a high-weight carbon fiber sheet for any RTM construction method configured as described above,
The resin is an RTM method characterized by a viscosity at the time of resin injection of 30 to 300 mPa · s.
In the second aspect of the present invention, the 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 present invention, by using a carbon fiber sheet using thick carbon fiber strands, the carbon fiber Vf (carbon fiber per unit cross-sectional area) can be compared with molding by stacking a plurality of thin carbon fiber strand sheets. The cross-sectional area ratio) can be increased, and the performance of the FRP material can be improved. Therefore, according to the present invention, the fiber basis weight exceeds 800 g / m ² , for example, a large FRP material used for wind turbine blades, vehicles, ships, etc., by the RTM method, the resin impregnation time is shortened, and Good products such as tensile and bending strength can be produced.

FIG. 1 is a perspective view showing an embodiment of a carbon fiber sheet according to the present invention.
Fig.2 (a) is the perspective view which expanded a part of carbon fiber sheet according to this invention, FIG.2 (b) is a perspective view which shows a part of twisted fiber bundle.
FIG. 3 is a perspective view showing another embodiment of the carbon fiber sheet according to the present invention.
FIG. 4 is a schematic configuration diagram of an experimental apparatus for carrying out the RTM method.
FIG. 5 is a graph showing the relationship between the number of twists of carbon fiber strands and strength.

Hereinafter, the carbon fiber sheet and the RTM method according to the present invention will be described in more detail with reference to the drawings.

First, with reference to FIG. 1, the carbon fiber sheet 10 which uses carbon fiber as a reinforced fiber of this invention is demonstrated.
In FIG. 1, one Example of the carbon fiber sheet 10 of this invention is shown. In the present embodiment, the carbon fiber sheet 10 is formed by aligning twisted carbon fiber strands (in this specification, twisted carbon fiber strands are referred to as “single twist fiber bundles”) 11 in one direction. The single twist fiber bundles 11 are fixed to each other by a fixing fiber material 13 and formed into a sheet shape. The carbon fiber strand F is formed by converging a large number of carbon fiber filaments f. A gap g is formed between the single twisted fiber bundles 11.
More specifically, according to the present embodiment, as shown in FIGS. 1 and 2A, the carbon fiber of the carbon fiber sheet 10 is a twisted carbon fiber strand F, that is, a single twisted fiber bundle 11. Is used. Moreover, the sizing agent of the carbon fiber strand F was 0.2% in the present Example. However, in the present invention, the amount of the sizing agent of the carbon fiber strand F is not limited to this.
In other words, according to this example, carbon fiber strands F in which 50000 to 60000 carbon fiber monofilaments f having an average diameter of 7 μm are converged as carbon fibers are used, and the carbon fiber strands F are 5 to 50 times per meter. Twist times are applied to form a single twist fiber bundle 11. If the number of twists is less than 5, the force for converging the carbon fiber strands F is weak, and the strands F are not easily thinned. Moreover, if it exceeds 50 times, the carbon fiber strand F will become hard by winding, and the impregnation property of resin will worsen. Further, the linearity of the fiber is deteriorated, and the performance of FRP is lowered.
The inventors of the present invention have no problem in terms of physical properties such as twist workability and strength even when a thick carbon fiber strand F in which 50,000 to 60000 carbon fiber monofilaments f converge is twisted, and such carbon fibers An experiment was conducted to confirm that the fiber sheet produced with the strand can be suitably used in an RTM method using a low-viscosity RTM resin. That means
(1) Even if a predetermined number of twists are added to the large-diameter carbon fiber strand F, the strength does not decrease.
(2) Extremely low viscosity used in the RTM method, that is, excellent in impregnation with RTM resin having a viscosity of about 30 to 300 mPa · s when the resin is poured into the mold (for example, temperature 25 ° C.) Being.
Conventionally, as described above, the viscosity of a construction resin for civil engineering and construction using a unidirectional carbon fiber sheet is about 3000 to 10,000 mPa · s / 23 ° C.
(3) By twisting the fiber, it is difficult for the fiber to flow when the RTM resin is injected.
(3) Since there are many moldings with a thick molding thickness in the RTM method, the number of laminated sheets can be reduced in the high-weight carbon fiber sheet.
An experiment was conducted to confirm the above.
In this experiment, carbon fiber strand F (size agent 0.2%) in which 50000 high-strength carbon fiber monofilaments f having an average diameter of 7 μm were converged as carbon fibers was used, and the number of twists was set to no twist, 5, 10, It was confirmed at 20, 30, 40, 45, 50, 55, 60 times / m.
As a result, as shown in the following Table 1 and FIG. 5, the tensile strength of the carbon fiber strand F was not observed when the twist was not twisted to 50 times / m, and the strength was decreased at 55 times / m or more. .

On the other hand, the width (w) of the carbon fiber strand F (see FIG. 2 (a)) is not twisted and is less than 5 times / m, the fiber convergence force is weak, and it cannot be made as thin as expected. When it was 5 times or more, particularly 15 times / m or more, the convergence was sufficient and the carbon fiber strands were in a thin and tight state.
From the above, the carbon fiber strand has a suitable fiber twist frequency in the range of 5 to 50 times / m, and 10 to 20 times / m is the best.
Thereby, when the single twist fiber bundle 11 is aligned in one direction, the fiber bundle does not spread or spreads very little, and the single twist fiber bundle 11 has a width (w) of 1.7 to ~. A substantially circular or elliptical cross-sectional shape of 2.0 mm and a thickness (t) of 1.7 to 2.0 mm can be maintained. Thereby, it can prevent that each carbon fiber strand overlaps.
Therefore, according to the present example, when the fiber basis weight of the carbon fiber sheet 10 formed by the single twisted fiber bundles 11 arranged in one direction exceeds 800 g / m ² , for example, 1000 g / m ^2. Even in the case of exceeding, the gap (g) = 0 to 2 mm, preferably 0.2 to 1 mm is formed between the single

twisted fiber bundles

11 and 11 as shown in FIG. 1 and FIG. be able to.
Therefore, in particular, when impregnating the RTM resin having a low viscosity (that is, a temperature at the time of injection, for example, a viscosity of 30 to 300 mPa · s at 25 ° C.) used in the RTM method, the matrix resin is a single

twist fiber bundle

11, 11 Easy to pass between. Further, by increasing the contact area between the reinforcing fiber and the matrix resin, and further converging the fibers, the capillarity between the carbon fiber filaments f in each fiber bundle 11 causes the inside of the fiber bundle 11 to enter. The resin impregnation property can be improved.
According to the present invention, the fiber basis weight of the carbon fiber sheet 10, as described above, a value exceeding at least 800 g / ^{m 2,} especially is a value greater than 1000 g / ^{m 2,} fiber weight per unit area of 6000 g / ^{m 2} If it exceeds, the sheet thickness (t) (FIG. 2 (a)) becomes too large, and even in the RTM method, that is, even if a low-viscosity RTM resin is used, the resin impregnation property is poor and impractical. Preferably, the fiber basis weight is greater than 800 g / ^{m 2,} in particular exceed ^{^{1000g / m 2, 6000g / m}} 2 or less, preferably, is a 2400 g / ^{m 2} or less.
As described above, in the carbon fiber sheet 10 in which the single twisted fiber bundles 11 are aligned in one direction, each single twisted fiber bundle 11 has a gap (g) = 0 to 2 mm, preferably 0.2 to 1 mm. The fibers are fixed by the fixing fiber material 13 so as to be separated from each other.
The length (L) and width (W) of the carbon fiber sheet 10 formed in this manner are determined as appropriate according to the size and shape of the structure to be reinforced, but generally, due to handling problems, The total width (W) is 100 to 500 mm. Moreover, although length (L) can manufacture a thing of 100 m or more, in use, it cuts suitably and is used.
Moreover, as a method of fixing each single twisted fiber bundle 11 with the fixing fiber material 13, as shown in FIG. 1, for example, wefts are used as the fixing fiber material 13, and a plurality of fibers arranged in one direction are used. The single twisted fiber bundle 11 may be driven at a constant interval (P) perpendicular to the single twisted fiber bundle 11 and knitted. The driving interval (P) of the weft yarn 13 is not particularly limited, but is usually selected in the range of 1 to 15 mm in consideration of the handleability of the produced fiber reinforced sheet 10.
At this time, the weft 13 is a yarn obtained by bundling a plurality of glass fibers or organic fibers having a diameter of 2 to 50 μm, for example. As the organic fiber, polyester, nylon, vinylon, or the like is preferably used.
As another method of aligning the single twisted fiber bundles 11 in one direction and fixing them in a sheet shape, a mesh-like support sheet can be used as the fixing fiber material 13 as shown in FIG.
That is, a mesh-like support made of, for example, glass fiber or organic fiber having a diameter of 2 to 50 μm on one side or both sides of a plurality of single twisted fiber bundles 11 in the form of a sheet aligned in one direction. A configuration supported by the sheet 13 may also be adopted.
In this case, for example, the surface of the warp yarn 14 and the weft yarn 15 constituting the mesh-like support sheet 13 having a biaxial configuration is impregnated with a low melting point type thermoplastic resin in advance, and the mesh-like support sheet 13 Are laminated on one or both sides of each single twisted fiber bundle 11 and heated and pressurized, and the warp yarn 14 and weft yarn 15 portions of the mesh-like support sheet 13 are fused to a plurality of single twist fiber bundles 11 in sheet form. To do.
In addition to the biaxial configuration, the mesh-shaped support sheet 13 is formed by orienting glass fibers in three axes, or only the wefts 15 that are orthogonal to the single twist fiber bundle 11 are disposed. It can also be bonded to a plurality of single twisted fiber bundles 11 formed so as to be oriented in one axis and aligned in the form of a sheet.
Further, as the yarn of the fixing fiber material 13, for example, a double-structured composite fiber having a glass fiber in the core and a low melting point heat-fusible resin arranged around it is also preferably used. It is done.
The carbon fiber sheet 10 is made by twisting the carbon fiber strands F, that is, the single twisted fiber bundles 11 in one direction, but in another method, as shown in FIG. A plurality of carbon fiber strands (single fiber bundles) F that are not twisted, for example, 2 to 5 are combined, and in FIG. In the present specification, the “twisted fiber bundle”) 12) can be used in place of the single twisted fiber bundle 11.
That is, in this case as well, as described above, carbon fiber strands in which 50000 to 60000 carbon fiber monofilaments having an average diameter of 7 μm are converged, that is, a single fiber bundle F, are used. Combine 5 pieces and apply 5 to 50 twists per meter. If the number of twists is less than 5, the force for converging the carbon fiber strands F is weak, and the strands F are not easily thinned. Moreover, if it exceeds 50 times, the carbon fiber strand F will become hard by winding and it will become difficult to do the impregnation property of resin. Further, the linearity of the fiber is deteriorated, and the FRP performance is lowered. Preferably, the number of twists is 10 to 20 times / m.
Thus, the twisted fiber bundle 12 has a substantially circular or elliptical cross-sectional shape with a width (w) of 2.0 to 2.3 mm.
Also in this embodiment, the carbon fiber sheet 10 replaces the single twisted fiber bundle 11 shown in FIG. 1 with the above twisted fiber bundle 12 aligned in one direction, and the respective twisted fiber bundles 12 are fixed to each other. 3 is fixed in a sheet shape. Also in this case, as described above, in the carbon fiber sheet 10 in which the twisted and twisted fiber bundles 12 are aligned in one direction, the gap (g) = 0 to ~ 2 mm, preferably 0.2 to 1 mm, was formed, and there was no fiber overlap.
Accordingly, when the resin for RTM is impregnated, it is easy for the matrix resin to pass between the

twisted fiber bundles

12 and 12, and the contact area between the reinforcing fiber and the matrix resin is increased, so that the resin inside the reinforcing fiber bundle can be obtained. Impregnation can be improved.
Performance test example 1
According to the present invention, a carbon fiber sheet 10 shown in FIG. 3 was produced.
A PAN-based carbon fiber strand (single fiber bundle) F in which a single fiber (carbon fiber monofilament) f having an average diameter of 7 μm and a converged number of 50,000 were used was used as the carbon fiber. The strand F was twisted 15 times per meter to obtain a single-stranded fiber bundle 11. The sizing agent of the carbon fiber strand F was 0.2%.
In the carbon fiber sheet 10, the single twist fiber bundles 11 were aligned so as to have a fiber basis weight of 1200 g / m ² and arranged in a sheet shape. A mesh-like support sheet 13 was bonded to one side of the single fiber bundle 11 having a sheet shape.
The carbon fiber sheet 10 thus produced had a width (W) of 200 mm and a length (L) of 100 m. The gap (g) between the single twisted fiber bundles 11 was 0 to 0.2 mm.
As a comparative example, a carbon fiber sheet having the following configuration was produced.
Comparative Example 1
The comparative example 1 is different only in that a strand (single fiber bundle) F that does not twist the carbon fiber is used as a comparative example 1, and the carbon shown in the above specific example 1 according to the present invention is of the same material, configuration, and dimensions. A carbon fiber sheet similar to the fiber sheet 10 was produced.
Comparative Example 2
As Comparative Example 2, PAN-based carbon fiber strands (single fiber bundles) F in which single fibers (carbon fiber monofilaments) f having an average diameter of 7 μm were converged as 24,000 converging numbers were used as carbon fibers. The strand F was twisted 15 times per meter to obtain a single-stranded fiber bundle 11. The sizing agent of the carbon fiber strand F was 0.2%.
In the carbon fiber sheet 10, the single twisted fiber bundles 11 were aligned so as to have a fiber basis weight of 400 g / m ² and arranged in a sheet shape. A mesh-like support sheet 13 was bonded to one side of the single fiber bundle 11 having a sheet shape.
The carbon fiber sheet 10 thus produced had a width (W) of 200 mm and a length (L) of 100 m. The gap (g) between the single twisted fiber bundles 11 was 0 to 0.2 mm.
Next, the carbon fiber sheet 10 of the specific example 1 and the carbon fiber sheets of the comparative examples 1 and 2 are used in the specific example 1 and the comparative example 1, one sheet in the comparative example 2, and three sheets are used in the RTM method. A flat plate having a width of 200 mm, a length of 2 m, and a thickness of 1.3 mm was produced using the experimental apparatus 100 shown in FIG.
Referring to FIG. 4, the molding apparatus 100 used in this experiment is an apparatus that performs the VaRTM method. The carbon fiber sheet 10 is placed in a mold (mold) 101, and a resin distribution medium 102 and a vacuum are placed thereon. Bag 103 is set. 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. In addition, the vacuum bag 103 is evacuated, whereby the carbon fiber sheet 10 is impregnated with the resin R. The carbon fiber sheet 10 impregnated with the resin R is heated together with the mold 101 with a heating device, for example, a heating plate or an oven, and the resin R is cured. Thereafter, the resin-impregnated and cured carbon fiber sheet 10 is removed from the molding die 101 to obtain a product (carbon fiber reinforced plastic material).
Resin R used in Specific Example 1 and Comparative Examples 1 and 2 is a low-viscosity RTM resin and is an epoxy resin for composite materials manufactured by Nagase ChemteX Corporation (general-purpose type “XNR / H6809” (trade name)). It 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.
Of course, as an RTM resin, in addition to an epoxy resin, a polyester resin, a vinyl ester resin, an MMA resin, an unsaturated polyester resin having a viscosity of 30 to 300 mPa · s at the time of resin injection (temperature 25 ° C. as an example) Phenolic resins can be used.
When the carbon fiber sheet 10 of the specific example 1 was used in this experiment, the resin impregnation operation was completed in about 0.5 hours (total molding operation time 2.5 hours), and the orientation of the carbon fiber sheet 1 was disturbed. And a good product could be obtained.
A product similar to that of Example 1 was produced using the carbon fiber sheet of Comparative Example 1, but it took 1 hour for resin-containing work (total molding work time 3.5 hours). In addition, the product was disturbed in carbon fiber orientation.
A product similar to that of Example 1 was prepared using three carbon fiber sheets of Comparative Example 2, but the carbon fiber orientation disorder was not found in the product, but the resin impregnation work was performed for 1.2 hours (total Molding work time of 4 hours) was required.
As described above, the carbon fiber sheet of the present invention uses a carbon fiber sheet using thick carbon fiber strands, so that the carbon fiber Vf (unit breakage) can be compared with molding of a large number of thin carbon fiber strand sheets. The cross-sectional area ratio of the carbon fibers per area) can be increased, the molding time can be significantly reduced including preparations such as laminating work, and the disturbance of fibers at the time of laminating can be further reduced. Thereby, it is possible to improve the performance of the FRP material and avoid an increase in cost.
Therefore, according to the carbon fiber sheet of the present invention, the fiber basis weight exceeds 800 g / m ² , particularly exceeds 1000 g / m ² , for example, a large FRP material used for wind turbine blades, vehicles, ships, etc. Thus, the resin impregnation time can be shortened and a product having good tensile and bending strength can be produced.
In addition, although the fiber sheet of the present example was used, a resin impregnation work was attempted using a construction resin for civil engineering and construction (viscosity at the time of resin injection (23 ° C.) 8000 mPa · s). It took time and had a big problem in terms of work efficiency.

DESCRIPTION OF SYMBOLS 10 Carbon fiber sheet 11 Single twist fiber bundle 12 Twisted fiber bundle 13 Fixing fiber material

Claims

A single-stranded fiber bundle prepared by applying 5 to 50 twists per meter to a carbon fiber strand in which 50000 to 60000 carbon fiber monofilaments are converged, or 50000 to 60000 carbon fiber monofilaments are converged. A plurality of carbon fiber strands are combined and a twisted fiber bundle produced by twisting 5 to 50 times per meter is arranged in one direction so as not to overlap, and each of the single twisted fiber bundles or the respective twisted fibers is arranged. fiber bundle twisted is fixed at a fixing fiber material to each other, the fiber basis weight exceeds 800g / m 2, 6000g / m 2 or less and the RTM method for the high basis weight carbon fiber sheet, characterized in that it is.
The high-weight carbon fiber sheet for an RTM method according to claim 1, wherein a gap (g) of 0 to 2 mm is formed between each single twisted fiber bundle or each twisted fiber bundle.
The high-weight carbon fiber sheet for an RTM method according to claim 1 or 2, wherein the twisted fiber bundle is formed by twisting 2 to 5 single fiber bundles.
The fixing fiber material is a weft for knitting each single twist fiber bundle or each twist fiber bundle in a direction perpendicular to the longitudinal direction of each single twist fiber bundle or each twist fiber bundle. The high-weight carbon fiber sheet for an RTM method according to claim 1, 2, or 3, characterized by the above.
The high-weight carbon fiber sheet for an RTM method according to claim 4, wherein the weft is a yarn made of glass fiber or organic fiber.
The fixing fiber material is a mesh-like support sheet that is disposed on one side or both sides of each single twisted fiber bundle or each twisted fiber bundle arranged in one direction, and is bonded or fused. The high-weight carbon fiber sheet for an RTM method according to any one of claims 1 to 5, wherein:
The mesh-like support sheet is formed by orienting uniaxial, biaxial or triaxial yarns made of glass fibers, and the single twisted fiber bundles or the synthetic fibers are made of resin coated on the yarn surface. The high-weight carbon fiber sheet for an RTM method according to claim 6, which is adhered or fused to a twisted fiber bundle.
In the RTM method of inserting a carbon fiber sheet into a mold, injecting and curing a resin, and molding a fiber reinforced plastic material,
The carbon fiber sheet is a high-weight carbon fiber sheet for an RTM method according to any one of claims 1 to 7,
The RTM method, wherein the resin has a viscosity at the time of resin injection of 30 to 300 mPa · s.
The RTM method according to claim 8, wherein the resin is an epoxy resin, a polyester resin, a vinyl ester resin, an MMA resin, an unsaturated polyester resin, or a phenol resin.