JPH04281037A - Reinforcing woven carbon fiber fabric and its production - Google Patents

Abstract

PURPOSE:To provide a reinforcing woven carbon fiber fabric free from the trouble of stress concentration caused by the shift of carbon fiber or the bending of woven yarn, having excellent drapeability and capable of forming a CFRP having excellent physical properties and reliability, and to provide a process for the production of the woven fabric. CONSTITUTION:A woven carbon fiber fabric traveling in the direction of warp is subjected to a water jet ejected from a nozzle having a nozzle diameter of 0.05-0.5mm and a nozzle pitch corresponding to <=1/3 of the warp pitch, and the jet is made to collide with the woven fabric at a striking force of 0.1-3gf per single yarn. The woven yarns are opened, expanded and flattened by this process. The width W and the fineness D of the woven yarn of the obtained reinforcing woven carbon fiber fabric satisfy the formula W=k.(D/rho)<5/9> (k is a coefficient; rho is specific gravity of the carbon fiber).

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a woven fabric used as a reinforcing material for resin when molding carbon fiber reinforced plastic (CFRP), and a method for producing the same.

0002

BACKGROUND OF THE INVENTION When molding CFRP, carbon fibers are often used in the form of woven fabrics woven from multifilament yarns. Various types of textiles are also available.

By the way, as is well known, carbon fiber yarns are produced by firing precursor fiber yarns (multifilament yarns) such as polyacrylonitrile fibers in an inert atmosphere and carbonizing them. and,
Most of the manufacturing cost of carbon fiber yarn is accounted for by this firing process, and the quality of productivity in the firing process has a large impact on the cost of carbon fiber yarn and, ultimately, the fabric.

[0004] The productivity in the firing process improves as thicker precursor fiber yarns are used. This is because the fabric can be fired all at once, and the thinner the fabric, the lower the productivity and the higher the cost of the fabric. However, as the cost of textiles increases, CF
As the proportion of material costs in RP increases, cost performance declines, and applications become more restricted, the number of single yarns for precursor fiber yarns is usually several thousand or more.
Sometimes they use thick ones with over 10,000 pieces. Therefore, the carbon fiber yarn obtained from such a thick precursor fiber yarn is naturally also thick, which brings various disadvantages to the fabrics woven from it.

[0005] In other words, the thicker the threads of a woven fabric, the greater the bending of the threads due to interlacing. However, as is obvious from a mechanical point of view, if there is bending, stress will be concentrated in that part, making it impossible to fully utilize the inherent properties of carbon fiber. This is because the fabric begins to break at the bent portion before the characteristics of the carbon fiber are developed.

[0006] Furthermore, as the bending of the weaving yarn becomes larger, the weave becomes larger and the surface irregularities also become larger. The texture and unevenness become larger due to the high rigidity of carbon fibers and the convergence force exerted on the weaving yarns due to interlacing. However, if the weave becomes larger or the unevenness becomes larger, CFRP
When this happens, it is difficult to obtain CFRP with excellent physical properties and reliability, as the uneven distribution of carbon fibers results in areas with no carbon fibers or areas with too much resin.

By the way, when molding CFRP,
The fabric is often made into prepreg in advance. In other words, the fabric is impregnated with a B-stage thermosetting resin under pressure and heat to form a prepreg. In the impregnation process, the fabric is heated and pressurized while the viscosity of the thermosetting resin is lowered. Therefore, the weaving threads are widened, the weave is almost closed, and the surface unevenness is almost eliminated. This may seem like a good thing at first glance, but this is the result of the highly rigid carbon fiber single yarn being forced to move under pressure, and when the pressure is released, it returns to its original state. Although it may not be the case, it will recover to a state close to it. For example, a plurality of such prepregs are laminated on each side of a honeycomb core, heated and pressurized to harden the thermosetting resin to form a skin, and then bonded to the honeycomb core to form a honeycomb sandwich panel. When used in manufacturing, the fabric is pressurized in the cell wall area and the single yarns move, but the cell pore area is not pressurized, so the recovery state described above is maintained almost as it is. , carbon fibers are unevenly distributed, creating areas where there are no carbon fibers at all, or areas where there is too much resin.
Voids may appear between the layers. However, when such honeycomb sandwich panels are used to construct, for example, an aircraft spoiler, moisture accumulates in the voids, which freezes during high-altitude flight, inducing cracks in the skin, and this cycle repeats. Moisture soon begins to enter the honeycomb core, degrading the physical properties of the panel and jeopardizing the safe operation of the aircraft.

[0008] As described above, CFRP is not originally an isotropic material like metal materials, but an anisotropic material, which makes the design itself difficult, and there are various delicate problems with the reinforcing material. This makes design even more difficult, and that difficulty makes reliability even less certain. Although CFRP is used in aircraft as an advanced material with excellent properties such as specific strength and specific modulus, its use is limited to secondary structural materials, and its use as a primary structural material whose destruction affects flight safety. This is also the reason why there is hesitation. For this reason, various improvements have been made to carbon fiber fabrics as reinforcing materials.

For example, the invention of Japanese Patent Publication No. 2-32383 discloses that while a reinforced carbon fiber fabric is continuously running, a high-pressure water jet of 30 to 1,000 kg/cm2 is applied to the surface of the fabric to spread the woven yarn. It is proposed to widen and flatten the weave to reduce the bending of the weaving yarns at the intersection, reduce surface irregularities, and completely close the weave. Although there is no mention of reinforced carbon fiber fabrics, the same thing is also described in JP-A-50-126979. In the fabric treated in this way, the bending of the yarn at the intersection is small, and the above-mentioned problem of stress concentration is alleviated. Furthermore, since the surface unevenness is small and the weave is completely closed, problems caused by uneven distribution of carbon fibers when molding CFRP can be prevented. However, on the other hand, when a carbon fiber fabric is exposed to a high pressure water jet of 30 to 1,000 kg/cm 2 , there is a problem in that the single yarns constituting the weaving yarns are severely broken. Carbon fiber is
This is because it is fragile. However, when a single filament breaks, the reinforcing effect of the resin in CFRP naturally decreases. In addition, the water jet is directed from multiple nozzle holes arranged in rows in the weft direction of the fabric, but if the pitch of the nozzle holes is not appropriate, the water jet may not be directed to some yarns, or some yarns may be Forces in complicated directions act on the weaving yarns, resulting in differences in the degree of opening, widening, and flattening between yarns, and single yarns meandering. In this case, the reinforcing effect is also reduced. Furthermore, if the weave is completely occluded, the degree of freedom of movement of the weaving threads will be reduced, and the drapeability (the ability to follow the shape), which is an important characteristic for reinforcing materials in CFRP, will rapidly decrease. , it becomes unsuitable for molding CFRP of a complicated shape such as a curved surface, regardless of a simple shape such as a flat plate.

[0010] In this way, when directing a water jet to a carbon fiber fabric to spread the yarn and widen and flatten it, the nozzle hole diameter and the water jet on the fabric surface, which are related to the momentum of the water jet, are The striking force and the pitch of the nozzle holes are extremely important, and if these are not selected within the appropriate range, CFRP with excellent physical properties and reliability will not work.
It is not possible to obtain such a fabric that can be molded.

[0011]

OBJECTS OF THE INVENTION An object of the present invention is to solve the above-mentioned problems in conventional reinforced carbon fiber fabrics and methods for producing the same, and to provide excellent uniformity in opening, widening and flattening of woven yarns. The bending of the weaving yarns at the intersection is small, so there is almost no need to worry about breakage due to stress concentration, and the surface smoothness is excellent, which almost avoids the inconveniences caused by uneven distribution of carbon fibers when forming CFRP. It is an object of the present invention to provide a reinforced carbon fiber fabric that can be molded into CFRP that has excellent drape properties, high physical properties, and excellent reliability, and a method for manufacturing the same.

0012

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention has a carbon fiber multifilament yarn having a twist count of 5 times/m or less, which is organized as warp and weft, and at least the warp is a single yarn. The number of threads is 3,000 or more, and the relationship between the width and fineness of the warp and weft is as follows: W=k・(D/ρ)5/9 Where, W: Width of warp or weft (mm) ) k: Coefficient, 3.5 x 10-2 to 10.0 x 10-2 (
mm・D-5/9) D: Fineness (denier) of warp or weft ρ: Satisfies the specific gravity of carbon fiber and has a cover factor of 90 to 99
．． Provided is a reinforced carbon fiber fabric characterized in that the carbon fiber content is in the range of 8%. The value of k in the above formula is 4.5×1 at least when the number of single warp yarns is less than 3,000.
0-2 to 10.0×10-2 mm・D-5/9.

[0013] Furthermore, the present invention uses carbon fiber multifilament yarns with a twist count of 5 times/m or less as the warp and weft, and the size of the weave is at least 1 of the width of the warp.
/5 while running the fabric in the warp direction, the water jet is directed at the fabric from a plurality of nozzle holes arranged in rows in the weft direction of the fabric to spread the warp and weft yarns to widen the fabric.・When flattening, a. The nozzle hole diameter is in the range of 0.05 to 0.5 mm, b. The nozzle hole pitch is 1/3 or less of the warp pitch, c. Provided is a method for producing a reinforced carbon fiber fabric, characterized in that the impact force per water jet on the surface of the fabric is in the range of 0.1 to 3 gf.

[0014] In the present invention, a woven fabric using carbon fiber multifilament yarns as the weaving yarns, that is, warp and weft yarns, is obtained by a normal weaving operation.

[0015] The number of single yarns of the multifilament yarn is determined by the ease of weaving operation, and the higher the number of single yarns, the more uniform the distribution of single yarns within the weaving yarn during the subsequent opening, widening, and flattening treatments. Considering the improvement, 1,000 to 30,000
The denier is preferably about 400 to 40,000 deniers. The single yarn diameter is about 5 to 10 μm.

[0016] The above-mentioned multifilament yarn has a twist count of 5 times/m or less in order to facilitate the subsequent opening, widening and flattening treatment and to achieve excellent uniformity. In terms of opening, widening, and flattening, it is most preferable to have no twist, but if there is no twist at all, it is difficult to perform the weaving operation.

[0017] Such a multifilament yarn is prepared by attaching a sizing agent in a range of 0.2 to 1.8% by weight to a twisted multifilament yarn of carbon fiber, drying it, winding it around a bobbin, and twisting the yarn to a number of twists of 5. It is preferable to obtain it by untwisting it so that it is less than twisting times/m. That is, after firing the twisted multifilament yarn of the precursor fiber and carbonizing it, a sizing agent is attached, dried and wound onto a bobbin, and the bobbin is rotated and unraveled so that the number of twists is 5 turns/m or less. When twisted, the multifilament yarns experience air resistance and form a balloon. At this time, if the amount of the sizing agent attached is in the range of 0.2 to 1.8% by weight, the sizing agent will be peeled off due to friction with the air, and the restraint between the single yarns will be released, resulting in an open state. In a woven fabric using such multifilament yarn as a weaving yarn, even if the striking force of the water jet is low, the yarn can be sufficiently and uniformly opened, widened, and flattened. That is, it becomes possible to perform fiber opening, widening, and flattening treatments under gentle conditions. In addition, if an epoxy-based sizing agent is used, there is no need for desizing, and the fabric that has been opened, widened, and flattened using a water jet can be directly used in the prepreg process or CFRP forming process. It becomes like this. At this time,
If the epoxy sizing agent contains water-soluble components, surfactants, etc., it is best to wet it with water or warm water before treatment.

[0018] When weaving a fabric using the above-mentioned carbon fiber multifilament yarn as a weaving yarn, it is necessary to make the cover factor within a specific range so that the subsequent fiber opening, widening, and flattening treatments can be performed easily and uniformly. The gaps formed between the warp and weft, that is, the weave, are widened so that the The extent to which it is spread depends on the thickness of the threads, but it should be at least 1/5 of the width of the warp threads. For example, when the width of the warp is 1.5 mm, it is set to around 0.5 mm, and when it is 4 to 5 mm, it is set to about 10 to 20 mm. A woven fabric with a weave size of 10 to 20 mm is called a mesh woven fabric.

Most preferably, the texture of the fabric is a plain texture. Usually, yarns with the same number of single yarns and the same fineness are used for the warp and weft, and the weaving density is made equal in the warp direction and the weft direction. However, it is also possible to have a unidirectional structure in the warp direction, which is called a unidirectional fabric.

On the other hand, the basis weight can be arbitrarily selected, but when the number of single yarns is small, the ease and uniformity of opening, widening and flattening, the shape retention of the resulting fabric, and the cover factor are important. Considering the above, preferably 120 to 200g/
m2, preferably in the range of 140 to 195 g/m2. This area weight range is for a single yarn count of 3,000
This is particularly preferred when the book is a book. Note that the basis weight does not change even after opening, widening, and flattening treatments.

[0021] In the present invention, the above-mentioned carbon fiber multifilament yarn having a twist number of 5 times/m or less is used as the warp and weft, and the size of the weave is at least 1/5 of the width of the warp. A certain woven fabric is subjected to fiber opening, widening, and flattening treatment using a water jet while running continuously in the warp direction.

To explain this process with reference to the drawings, as shown in FIG. 5a is guided onto a conveyor belt 5, and further guided to a winding core 9 via a dewatering roller 6 consisting of a pair of rollers, a dryer 7, and a nip roller 8. Then, while the fabric 2 is continuously running, the conveyor belt 5
Above, a water jet is directed onto the fabric 2 from a direction of 90±20° with respect to the fabric surface from a nozzle device 10 placed about 5 to 30 cm above the conveyor belt 5,
The striking force is used to open, widen, and flatten the weaving yarn. After the treatment, the woven fabric is squeezed out of moisture with a dewatering roller 6, further dried with a drier 7, and then passed through a nip roller 8 and wound onto a core 9. The running speed of the fabric 2, that is, the processing speed, depends on the striking force of the water jet, but is between 0.5 and 2.
Preferably, the speed is within the range of 20 m/min. When the striking force is small, it can be processed at low speed, and when it is large, it can be processed at high speed. A more preferable range is 0.5 to 15 m/min. In addition, in terms of weaving operations, it is natural that the warp direction of the woven fabric is the length direction. Therefore, the running direction of the fabric in FIG. 1 is the warp direction.

As shown in FIG. 2, the nozzle device 10 is divided into upper and lower chambers by a high-pressure water introduction hole 10b provided in a main body 10a, an upper passage 10c communicating with the high-pressure water introduction hole 10b, and a perforated plate 10d. Divided lower flow path 10
e, a rectifying plate 10m having a communication hole 10f connecting the upper flow path 10c and the lower flow path 10e, and a nozzle plate 10h having a large number of nozzle holes 10g arranged in a row at a constant pitch P. There is. The nozzle plate 10h is connected to the main body 10a by a pressure plate 10j having an opening 10i.
is attached to. 10k is an O-ring for sealing. Note that although only half of the nozzle device is shown in FIG. 2, the remaining half is also constructed symmetrically. Further, although the nozzle holes are arranged in a line in the case shown in FIG. 2, they may be arranged in a staggered manner.

In use, such a nozzle device 10 is arranged so that the rows of nozzle holes 10g are in the weft direction (width direction) of the fabric 2. Then, the pressurized high-pressure water is guided from the high-pressure water introduction hole 10b into the upper flow path 10c, and is rectified through the communication hole 10f while being rectified into the lower flow path 10c.
After the flow is further rectified by a perforated plate 10d to equalize the pressure, it is discharged from a nozzle hole 10g of a nozzle plate 10h to form a water jet. Preferably, the fabric is oscillated in the weft direction during processing. The pitch and period of the oscillation are preferably in the range of 1 to 5 times the warp pitch and about 0.03 to 1 second, respectively.

The nozzle hole diameter (diameter of the nozzle hole) of the above-mentioned nozzle device is in the range of 0.05 to 0.5 mm. 0
．． If it is less than 0.05, the amount of water is small, and even if the striking force on the surface of the woven fabric is high, sufficient energy cannot be obtained to open the woven yarn and make it wide and flat. In addition, the nozzle hole becomes easily clogged, making stable processing difficult. on the other hand,
If it exceeds 0.5 mm, the amount of water will be too large, and although it depends on the striking force, adjacent water jets will interfere with each other on the surface of the fabric, and the single yarns that make up the weaving yarns will become unstable. The yarns become irregularly bent, and the uniformity of opening, widening, and flattening of the yarns is greatly reduced.

Furthermore, the pitch of the nozzle holes is set to 1/3 or less of the warp pitch of the fabric. If the pitch is larger than 1/3, the energy distribution of the water jet on the surface of the fabric becomes too uneven, and in extreme cases, the water jet may not be directed at some yarns, causing the yarns to open. , the uniformity of widening and flattening is greatly reduced.

[0027] Furthermore, the water jet is such that the impact force per jet on the surface of the fabric is in the range of 0.1 to 3 gf. If it is less than 0.1 gf, the striking force is too small and sufficient energy necessary for opening, widening, and flattening the yarn cannot be obtained. Moreover, if it exceeds 3gf, the striking force will be too large, resulting in frequent single yarn breakage, broken single yarns becoming fluffy, and the uniformity of opening, widening, and flattening of the weaving yarns being significantly reduced. become. Preferably 0.1-1.5gf
, more preferably in the range of 0.3 to 1 gf. Here, the hitting force is determined as follows.

[0028] That is, the thickness of the strain gauge is 0.
．． One end of a stainless steel plate measuring 96 mm and width 40 mm is fixedly supported, and a portion 150 mm from the support and 10 mm from the other end is aligned with the surface position of the fabric to which the water jet is directed, and the water jet is applied. Then, the stainless steel plate is distorted by the striking force of the water jet, so the amount of distortion is taken out with a strain gauge and the force acting on the stainless steel plate is determined.
Divide the force value by the number of directed water jets. This value is the striking force per water jet.

In the above, for the sake of convenience, the reasons for specifying the ranges for each of the nozzle hole diameter, nozzle hole pitch, and striking force of the water jet on the surface of the fabric have been explained.
However, these are interconnected and are organic and inseparable in achieving the above-mentioned purpose of the present invention.

Now, according to the method described above, the relationship between the width and fineness of the warp and weft, respectively, is expressed by the formula, W
=k・(D/ρ)5/9 Where, W: Width of warp or weft (mm) k: Coefficient, when the number of single threads in the warp is 3,000 or more, 3.5 x 10-2 ~ 10.0×10-2 (mm・D
-5/9), 4.5 x 1 if less than 3,000
0-2~10.0×10-2 (mm・D-5/9)D:
Fineness (denier) ρ of warp or weft: A fabric satisfying the specific gravity of carbon fiber can be obtained. A woven fabric that satisfies this condition has yarns that are extremely uniformly opened, widened, and flattened, has very little bending due to interlacing, and has excellent surface smoothness. Here, k is related to the degree and uniformity of opening, widening, and flattening of the weaving yarn, and when k is below the lower limit value in the above equation, widening and flattening have not progressed sufficiently. . Therefore, the bending due to interlacing of the weaving threads is large, and the surface unevenness is also large. Moreover, when the value exceeds the upper limit, the unevenness of the opening state of the single yarn is large.

[0031] Furthermore, the woven fabric produced by the above method has a cover factor in the range of 90 to 99.8%. here,
Cover factor is the degree of tightness of the weave, in other words,
Related to the size of the weave. The larger the cover factor, the more the weaving yarns are opened, widened and flattened, and the weave becomes smaller. When molding CFRP, the cover factor is 100 to avoid creating areas where there is no carbon fiber or areas with too much resin.
%, ie the weave is completely occluded, seems preferable. However, in such a woven fabric, the binding force between the woven yarns is too strong and the degree of freedom of movement of the woven yarns is too small, resulting in extremely poor drapability and the tendency to wrinkle during molding. Although it is extremely small, creating a gap between the woven threads and allowing freedom of deformation is the key to CFRP.
This is extremely important as a reinforcing material. In this invention, the above-mentioned opening, widening, and
Considering the balance between the degree of flattening and drapability, the upper limit of the cover factor is set at 99.8%. On the other hand, 90%
If it is less than that, although the drapability is excellent, the weave is too large. However, as described above, this texture is temporarily eliminated by pressurization when forming a prepreg. However, when the pressure is removed, it recovers. Here, the cover factor is determined as follows.

That is, first, using a stereomicroscope, for example, a stereomicroscope SMZ-10-1 manufactured by Nikon Corporation, the surface of the fabric is photographed while shining light from the back side of the fabric. As a result, a transmitted light pattern of the fabric is photographed, with the weaving yarn portion being black and the weave portion being white. The amount of light is set within a range that does not cause halation. In this invention, the light of a double arm fiber manufactured by Nikon Corporation was reflected by an acrylic plate. The photographing magnification is set within 10 times so that 2 to 20 warps and wefts are each included in the analysis range in later image analysis. Next, the obtained photograph is placed on a CCD (charge coupled
(device) camera, converts the photographed image into digital data representing black and white brightness, stores it in memory, analyzes it with an image processing device, and calculates the total area S1, the sum of the areas of the white parts S2, and From, cover factor C
f by the formula, Cf = [(S1 - S2)/S1]
Calculate from x100. The same process was carried out at 10 locations on the same fabric, and the simple average value was taken as the cover factor referred to in this invention. In this invention, CC
A personal image analysis system LA-525 manufactured by Pierce Co., Ltd. was used as the D camera and image processing device. The analysis range of the image is from the left end of the leftmost warp to the left end of the rightmost warp in the horizontal direction.
The longitudinal direction was from the upper end of the weft shown at the top to the upper end of the weft shown at the bottom, and 2 to 20 warps and wefts were each included in this range. Note that the digital data includes an intermediate portion between black and white at the boundary between the thread portion (black portion) and the texture portion (white portion). In order to distinguish this middle part into a thread part and a weave part, a black tape of 6 mm width was attached to a transparent paper in a grid pattern vertically and horizontally at 6 mm intervals as a model, and the cover factor was 75.
Standardized to be %. That is, the aperture of the CCD camera was set to 2.8, and the image analysis system LA-525 was used.
The portion with a memory value of 128 or less was standardized as a yarn portion (in this system, black and white brightness and darkness are stored as memory values in stages of 0 to 255).

As described above, the woven fabric of the present invention has a constant relationship between the width of the yarn and the fineness, and has a cover factor within a specific range. In other words, the conditions described in the manufacturing method, such as the nozzle hole diameter, nozzle hole pitch, and impact force of the water jet on the surface of the fabric, are necessary conditions for obtaining such a fabric.

Among the fabrics of the present invention, carbon fiber multifilament yarns with a twist count of 5 turns/m or less, a single yarn count of 3,000, and an equal fineness are used as warp and weft yarns in a flat structure. The relationship between the width and fineness of the warp and weft is as follows: W=k・(D/ρ)5/9 Where, W: Width of warp or weft (mm) k: Coefficient, 3.5× 10-2 to 10.0×10-2 (
mm・D-5/9) D: Fineness (denier) of warp or weft ρ: Satisfies the specific gravity of carbon fiber, the weaving density is equal in the warp direction and the weft direction,
The basis weight is in the range of 120 to 200 g/m2, and
Those having a cover factor in the range of 90 to 99.8% are particularly suitable as reinforcing materials in CFRP.

That is, in a woven fabric, except for those with a special structure, the yarns extend in two directions perpendicular to each other and are highly anisotropic, but the warp and weft have the same number of single yarns and fineness, and Fabrics with equal weaving density in the warp and weft directions have the same properties in the directions perpendicular to each other, so by stacking and using the warp or weft so that they are shifted by a specific angle, for example 45 degrees, Pseudo-isotropy can be easily obtained. Also, from a manufacturing method point of view, if the warp and weft have the same number of single yarns and fineness, and the weave density is the same in the warp and weft directions, the size of the weave will be the same in the warp and weft directions. By spreading the weaving threads to the same extent in both directions, it can be easily widened and flattened.

[0036]Furthermore, the flat weave provides a thinner woven fabric with less deviation of the weave and a stable weave.

[0037]Furthermore, in a fabric in which the yarn fineness and weaving density are the same and the basis weight is in the range of 120 to 200 g/m2, the bending of the yarn at the intersection is smaller, and the problem of breakage due to stress concentration is more reliably avoided. It can be avoided. In addition, surface irregularities are also reduced. When the number of single yarns is 3,000, if the basis weight is less than 120 g/m2, the cover factor becomes too small, and if it exceeds 200 g/m2, the bending of the yarn becomes too large. In terms of the manufacturing method, a woven fabric with a basis weight in this range has 3,000 single yarns, so even though it is flat-woven, the binding force between the woven yarns due to interlacing is small. In addition, the size of the weave is small, and it can be easily opened, widened, and flattened using a water jet. A more preferable range of area weight is 140 to 195 g/m2
It is.

The fabric of the present invention can be made into a prepreg by impregnating it with a B-stage thermosetting resin such as epoxy resin, unsaturated polyester resin, phenol resin, polyimide resin, or bismaleimide resin using a conventional method. can do. The proportion of thermosetting resin in the prepreg is preferably 30 to 50% by weight, more preferably 35 to 45% by weight.

[0039] CFRP can be molded by the autoclave method using the above-mentioned prepreg or the mold molding method. Alternatively, the well-known injection molding method can be used. When using the injection molding method, in addition to the above-mentioned thermosetting resin, polyamide resin, P
Thermoplastic resins such as BT resin and polyetheretherketone resin can also be used.

[0040]

[Examples and Comparative Examples] Example 1: 0% in twisted carbon fiber yarn
．． Carbon fiber “Torayca” T300 yarn manufactured by Toray Industries, Inc. (average single yarn diameter : 7μm, number of single threads: 3,000, fineness: 1,800
denier, specific gravity: 1.76) as the warp and weft, and the warp and weft widths are 1.47mm and 1.49m, respectively.
m, the size of the weave in the warp direction and the weft direction is 0.
57mm, 0.59mm, weaving density in the warp and weft directions are both 4.85 threads/cm (warp pitch: approximately 2.06 m
m), a flat-woven fabric having a basis weight of 194 g/m2 and a thickness of 0.31 mm was obtained.

Next, as shown in FIG. 1, the fabric was opened, widened and flattened while traveling in the warp direction at a speed of 1.5 m/min. At this time, as a nozzle device,
Nozzle hole diameter is 0.13mm, nozzle hole pitch is 0.6m
m, and the striking force per water jet was 0.6 gf.

In the fabric thus obtained, the single yarns were well opened, and the warp and weft widths were 1.71 mm and 1.71 mm, respectively.
．． It was widened and flattened to 91mm. Also, the thickness is 0
．． It was 28 mm, had a cover factor of about 99%, was thin, and had extremely small surface irregularities. Furthermore, no single thread breakage or fuzz was observed.

Comparative Example 1: In Example 1, the striking force of the water jet was increased to 4.5 gf. When the obtained fabric was observed, it was found that significant single yarn breakage occurred, and the fabric resembled a nonwoven fabric made of short fibers.

Example 2: Using the carbon fiber yarn used in Example 1 as the warp and weft, the warp and weft widths were 1.60 mm and 1.49 mm, respectively, and the weave sizes in the warp and weft directions were respectively 1.37mm, 1.26mm,
The weave density in the warp and weft directions is both 3.5 threads/cm (
Warp pitch: approx. 2.86mm), basis weight 140g/m2
A flat-woven fabric having a thickness of 0.29 mm was obtained.

Next, the fabric was opened, widened and flattened in the same manner as in Example 1. The resulting woven fabric had the warp and weft widths widened and flattened to 2.17 mm and 2.09 mm, respectively. Further, the thickness was 0.23 mm, the cover factor was about 96%, and the surface was thin and had extremely small irregularities. Furthermore, no single thread breakage or fuzz was observed.

Example 3: B was added to the fabric obtained in Example 2.
A prepreg was obtained by impregnating the stage with a phenolic resin of 44% by weight.

Next, six sheets of the above prepreg were laminated with the warp directions of the fabrics aligned, heated at 170° C. and 7 kg/cm2 for 1 hour, and pressure molded to form a CFRP with a thickness of 1.03 mm.
Got the board. The volume content of carbon fiber in this CFRP board was 46.5%.

Next, when the above CFRP board was observed,
The carbon fiber single yarns were well dispersed, and no resin-excessive areas or voids were observed.

[0049] Also, from the above CFRP board, a width of 25 mm,
Cut out a test piece with a length of 230 mm, JIS K707
A tensile test was conducted in accordance with 3. The test results are shown below.

[0050] Tensile strength: 48.5 kg/mm2 Tensile modulus: 5480 kg/mm2 Tensile strain at break: 0.9
4% Tensile proportional strain limit: 0.94% Comparative example 2: Using the fabric before opening, widening and flattening in Example 2, prepreg was made in the same manner as in Example 3, and a CFRP board was further molded. did. This CFRP
The plate had a thickness of 1.06 mm and a carbon fiber volume content of 45.1%.

Next, when the above CFRP board was observed,
Large resin-excess areas were observed in the weave, and
A visible void had occurred in that part.

Next, regarding the above CFRP board, Example 3
A tensile test was conducted in the same manner. The test results are shown below.

[0053] Tensile strength: 47.5 kg/mm2 Tensile modulus: 5460 kg/mm2 Tensile strain at break: 0.9
5% Tensile proportional strain limit: 0.60% Comparing this CFRP plate with the one according to Example 3, it is found that although the content of phenolic resin in the prepreg is the same, the thickness is thicker, and the carbon The fiber volume content is low. Furthermore, although there are no major differences in tensile strength, tensile modulus, and tensile strain at break, the tensile proportional limit strain is 0.60%, and the linearity of the stress-strain diagram disappears before reaching final break. . In this respect, in the former case according to Example 3, the tensile proportional limit strain was 0.94%, and the linearity of the stress-strain diagram was maintained until just before the final breakage.

Example 4: B was added to the fabric obtained in Example 2.
A prepreg was obtained by impregnating the stage with an epoxy resin of 38% by weight.

Next, the prepreg is placed along a mold having a cup-shaped cavity with the warp direction of the fabric aligned.
Laminated, 120℃ in autoclave, 7kg/c
Heated and pressure molded at m2 for 2 hours, wall thickness is 0.87mm.
got a cup of The volume content of carbon fiber in this cup was 55%.

Next, when the above-mentioned cup was observed, it was found that the carbon fiber single yarns were well dispersed, and no disorder of arrangement due to wrinkles was observed, nor were there any resin-excessive areas or voids. Moreover, the surface was extremely smooth.

Comparative Example 3: Opening, widening and
Using the woven fabric before flattening treatment, a prepreg was made in the same manner as in Example 4, and a cup was further molded. This cup had a wall thickness of 0.89 mm and a carbon fiber volume content of 54%.

[0058] Next, when the cup was observed, it was found that the weaving threads had not spread sufficiently, so the surface had large irregularities, and areas with too much resin were formed in the weave, and voids were also generated in those areas. Was.

Comparative Example 4: Example 1 except that carbon fiber yarn with a twist count of 15 turns/m was used as the warp and weft.
A similar fabric was obtained in the same manner.

Next, the above fabric was treated in the same manner as in Example 1, but the warp and weft widths were both 1.50 mm.
It had hardly been widened or flattened.

[0061]

Effects of the Invention The method of the present invention uses carbon fiber multifilament yarns with a twist count of 5 turns/m or less as the warp and weft, and the size of the weave is at least 1/5 of the width of the warp. While running a certain fabric in the warp direction, a water jet is directed at the fabric from a plurality of nozzle holes arranged in rows in the weft direction to spread the warp and weft, thereby widening and flattening the fabric. , a. The nozzle hole diameter is in the range of 0.05 to 0.5 mm, b. The nozzle hole pitch is 1/3 or less of the warp pitch, c. The impact force per water jet on the surface of the fabric is in the range of 0.1 to 3 gf, and in particular, the nozzle hole diameter, nozzle hole pitch, and pressure of the water jet on the surface of the fabric are as specified above. By setting the weaving yarn within this range, the weaving yarn can be opened, widened, and flattened with high uniformity while preventing breakage of the single yarns constituting the weaving yarn.

[0062] Furthermore, the woven fabric of the present invention has a twist number of 5 times/
The warp and weft are carbon fiber multifilament yarns with a diameter of less than m, and the warp has at least 3,000 single threads, and the relationship between the width and fineness of the warp and weft is expressed by the formula, W=k・(D/ρ)1/1.8 However, W: Width of warp or weft (mm) k: Coefficient, 3.5 x 10-2 to 10.0 x 10-2 (
mm・D-5/9) D: Fineness (denier) of warp or weft ρ: Satisfies the specific gravity of carbon fiber and has a cover factor of 90 to 99
．． 8%, or at least the number of warp yarns is less than 3,000 single yarns in the above, and the value of k in the formula is 4.
．． 5 x 10-2 ~ 10.0 x 10-2 mm・D-5/9
Since it is within the range of C
When molding FRP, it is possible to almost avoid inconveniences such as the uneven distribution of carbon fibers, the formation of areas with no carbon fibers at all, the formation of areas with too much resin, and the generation of voids. The bending of the weaving yarns is small in the parts, so there is almost no need to worry about stress concentration problems, and it also has excellent drape properties, making it possible to mold CFRP with high physical properties and excellent reliability. become.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing the implementation of the method of the present invention.

FIG. 2 is a schematic vertical sectional view of a nozzle device used in the method of the present invention.

[Explanation of symbols]

1: Winding core 2: Textile 3: Rotating guide 4: Dancer roller 5: Conveyor belt 5a: Wire mesh 6: Dehydration roller 7: Dryer 8: Nip roller 9: Winding core 10: Nozzle device 10a: Main body 10b: High pressure water introduction hole 10c: Upper channel 10d: Perforated plate 10e: Lower flow path 10f: Communication hole 10g: Nozzle hole 10h: Nozzle plate 10i: Open hole 10j: Pressure plate 10k: O-ring 10m: Current plate

Claims (7)

[Claims] Claim 1: A carbon fiber multifilament yarn with a twist count of 5 times/m or less is organized as warp and weft yarns,
At least the warp has a single thread count of 3,000 or more, and the relationship between the width and fineness of the warp and weft is determined by the formula:
W=k・(D/ρ)5/9 Where, W: Width of warp or weft (mm) k: Coefficient, 3.5×10-2 to 10.0×10-2 (
mm・D-5/9) D: Fineness (denier) of warp or weft ρ: Satisfies the specific gravity of carbon fiber and has a cover factor of 90 to 99
．． A reinforced carbon fiber fabric characterized by having a carbon fiber content in the range of 8%. 2. A carbon fiber multifilament yarn with a twist count of 5 turns/m or less is used as warp and weft yarns,
At least the number of single threads in the warp is less than 3,000, and the relationship between the width and fineness of the warp and weft is expressed by the formula:
W=k・(D/ρ)5/9 Where, W: Width of warp or weft (mm) k: Coefficient, 4.5×10-2 to 10.0×10-2 (
mm・D-5/9) D: Fineness (denier) of warp or weft ρ: Satisfies the specific gravity of carbon fiber and has a cover factor of 90 to 99
．． A reinforced carbon fiber fabric characterized by having a carbon fiber content in the range of 8%. Claim 3: The number of twists is 5 times/m or less, and the number of single yarns is 3.0
00 carbon fiber multifilament yarns with the same fineness are used as warp and weft yarns, and the relationship between the width and fineness of the warp yarns and wefts is expressed by the formula: W=k・(D/ρ)5/ 9 However, W: Width of warp or weft (mm) k: Coefficient, 3.5 x 10-2 to 10.0 x 10-2 (
mm・D-5/9) D: Fineness (denier) of warp or weft ρ: Satisfies the specific gravity of carbon fiber, the weaving density is equal in the warp direction and the weft direction,
The basis weight is in the range of 120 to 200 g/m2, and
A reinforced carbon fiber fabric having a cover factor in the range of 90 to 99.8%. 4. A prepreg comprising the fabric according to claim 1, 2 or 3. 5. A carbon fiber reinforced plastic comprising the fabric according to claim 1, 2 or 3. 6. A woven fabric whose warp and weft are carbon fiber multifilament yarns with a twist count of 5 turns/m or less, and whose weave size is at least 1/5 of the width of the warp,
While traveling in the warp direction, a water jet is directed at the fabric from a plurality of nozzle holes arranged in rows in the weft direction of the fabric to spread the warp and weft yarns, thereby widening and widening the fabric.
When flattening, a. The nozzle hole diameter is in the range of 0.05 to 0.5 mm, b. The nozzle hole pitch is 1/3 or less of the warp pitch, c. A method for producing a reinforced carbon fiber fabric, characterized in that the impact force per water jet on the surface of the fabric is in the range of 0.1 to 3 gf. [Claim 7] A sizing agent is applied in a range of 0.2 to 1.8% by weight to carbon fiber twisted multifilament yarns as warp and weft yarns, and the yarn is dried so that the number of twists becomes 5 turns/m or less. 7. The method for producing a reinforced carbon fiber fabric according to claim 6, which uses multifilament yarns which are untwisted as follows.