JP2001254255A - Fiber sheet for carbon-carbon composite material and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber sheet of a carbon fiber precursor to be used for a carbonaceous material reinforced with carbon fiber, that is, carbon-carbon composite material. SOLUTION: The fiber sheet for carbon-carbon composite material has a sheet-shaped fiber aggregate having the following features: in the sheet-shaped fiber aggregate, plural fiber bundles consisting of continuous fibers of a carbon fiber precursor are arranged parallelly in one direction; the fiber bundle has a total fineness of 3,000-60,000 TEX, and has fiber entanglements of 1.5-60 cm in a hook-drop value; and further, the sheet-shaped fiber aggregate is formed at an average density by fiber number in the cross direction of the sheet-shaped fiber aggregate of 10,000-35,000 threads/cm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a carbonaceous material reinforced with carbon fibers, that is, a carbon fiber precursor fiber sheet used for a carbon-carbon composite material.

[0002]

2. Description of the Related Art Carbon-carbon composite materials are lightweight and have excellent heat resistance, and are therefore used for brake shoes of high-speed vehicles and aircraft, and injection nozzles of flying objects.

[0003] This carbon / carbon composite material is a composite material comprising carbon fibers and matrix carbon, and its production method differs depending on the matrix precursor.

[0004] When the matrix precursor is a thermoplastic resin or a thermoplastic pitch, a carbon fiber substrate is impregnated with the resin or the pitch, and then a prepreg laminate is carbonized.
Graphitization is performed.

At this time, a gas is generated by thermal decomposition of the matrix precursor to form a cavity, so that impregnation, heat treatment and graphitization are repeated several times until a predetermined specific gravity is obtained.

There is also a method in which a hydrocarbon gas is used as a matrix precursor to impregnate a carbon fiber sheet laminated base material by a chemical vapor deposition method (CVD method), and a gas phase carbonization and graphitization treatment is repeated several times to obtain the same.

As the carbon fiber sheet material in the above-described method for producing a carbon / carbon composite material, a laminated material of a sheet fiber aggregate of a mat or a woven material made of carbon fiber is usually used. Since there is no fiber orientation in the thickness direction, there is a problem that it is easy to peel off between layers.

As a method of reinforcing the interlayer, a means for orienting a part of the fibers in the thickness direction of the base material by needle punching on the base material on which the sheet-like fiber aggregate is laminated is often used. Since it has little elongation, it is cut with a needle and it is difficult to orient the fiber in the thickness direction, and the fluff is scattered so much that the working environment is deteriorated.

According to a method of forming a sheet-like fiber aggregate in the state of oxidized acrylonitrile fiber, which is a precursor of carbon fiber, into a sheet-like fiber aggregate, and applying a hydrocarbon to the laminated base material by a CVD method, carbonization of the fiber is performed. Since the breaking elongation is large, the fibers are not cut by the needle punch, and sufficient fibers can be oriented in the thickness direction of the laminated base material.

[0010] However, the sheet-like fiber aggregates aligned in one direction have fibers aligned in parallel. Therefore, when the sheet-like fiber assembly is pierced with the needle, the fiber easily escapes, so that the fiber is hardly caught on the hook of the needle, and it is difficult to orient a sufficient fiber in the thickness direction of the laminated material. Therefore, it is necessary to repeat the needle punch many times.

On the other hand, in the case of a mat-like material, since the fibers are randomly oriented, the fibers are easily caught on the hooks of the needles and can be efficiently oriented in the thickness direction of the laminated base material. And the cost increases.

[0012]

SUMMARY OF THE INVENTION The object of the present invention is to pay attention to such a current situation, and it is possible to easily orient the fibers in the thickness direction of the sheet laminated base material by a needle punch or the like without breaking the fibers, and to handle the fibers at low cost. An object of the present invention is to provide a fiber sheet for a carbon / carbon composite material having good properties.

[0013]

In order to achieve the above object, the present invention basically has the following arrangement.

That is, a sheet-like fiber aggregate in which a plurality of fiber bundles composed of continuous fibers of a carbon fiber precursor are arranged in parallel in one direction, wherein the fiber bundle has a total fineness of 3,000 to 60, 2,000 TEX, a fiber entanglement with a hook drop value of 1.5 to 60 cm, and an average fiber number density in the width direction of the sheet-like fiber assembly of 10,000.
A fiber sheet for a carbon-carbon composite material, comprising a sheet-like fiber aggregate integrated at a rate of up to 35,000 fibers / cm.

The hook drop value is 1.5 to 60 cm.
After supplying a plurality of fiber bundles composed of continuous fibers of the carbon fiber precursor in a sheet shape at a constant arrangement pitch, and after expanding each fiber bundle width to the same or more than the arrangement pitch by widening means, And a method for producing a fiber sheet for a carbon / carbon composite material, wherein the sheet is integrated as a sheet by an integrating means.

[0016]

Preferred examples of the carbon fiber precursor fiber of the present invention include polyacrylonitrile fiber, rayon fiber, and pitch-based fiber. Particularly, these flame-resistant fibers, especially the polyacrylonitrile fiber, If it is a fiber, it is not necessary to perform a flameproofing treatment after processing it into a sheet, and the elongation at break is as high as 15 to 30%. In addition, especially in the case of a carbon fiber precursor, a fiber (polyacrylonitrile fiber, rayon fiber, pitch type, etc.)
Refers to fibers that have been made flame resistant by heat treatment.

A continuous fiber is one in which single fibers are connected without being cut substantially in the middle of a long span.

When a single fiber is composed of a large number of single fibers, there is a possibility that a single fiber cut in the middle may exist. If the properties such as strength are not substantially affected by the single fiber, continuous fibers may be used. Considered as fiber. For example, if the number of single fibers cut in the middle is about 1% or less of the total number, the fibers often function as continuous fibers.

The fineness of the single fiber is preferably from 0.03 to 0.3.
It is 3 TEX (more preferably 0.05 to 0.2 TEX, further preferably 0.1 to 0.2 TEX). If the value is below the lower limit of the numerical range, breakage of single yarns tends to occur. If the value exceeds the upper limit of the numerical range, it becomes difficult to uniformly heat-treat the inside of the fiber during the flame-proofing step, which may be undesirable.

A plurality of the above fibers form a fiber bundle. The number of fibers per fiber bundle is 20,000.
~ 420,000 are preferred.

A sheet-like fiber aggregate in which a plurality of fiber bundles are arranged in parallel in one direction is defined as:
This is a state in which the fiber bundle is oriented parallel to one direction. Therefore, it can be said that the fiber bundles are oriented in parallel in one direction even when the entire plane of the sheet is curved, for example, when the sheet-like fiber aggregate is arranged along the non-planar shape.
Further, in the fiber bundle, as described later, entanglement of single fibers or the like exists. That is, the orientation of the single fiber fluctuates within the fiber bundle. Furthermore, as described later, the fiber bundle is slightly bent in the vertical direction of the sheet plane due to a combination with the auxiliary yarn or needle punch or stitch,
Some single fibers may be disturbed in the direction perpendicular to the plane of the sheet-like fiber assembly.

The sheet-shaped fiber aggregate of the present invention is formed of a plurality of fiber bundles, and the number thereof is not particularly limited, but is usually about 10 to 100.

A single fiber bundle composed of the above fibers is a thick fiber bundle having a total fineness of 3,000 to 60,000 TEX, and is entangled with fibers (preferably 5,000 fibers).
0 to 40,000 TEX, more preferably 5,000 to
20,000 TEX). It is necessary to consider the thickness of the fiber bundle from the viewpoint of fiber entanglement. Although the fiber bundles constituting the fiber sheet of the present invention have fiber entanglement, the fiber bundles do not have fiber entanglement. Therefore, in the case of a thin fiber bundle, the portion without fiber entanglement increases, the fiber orientation in the thickness direction of the laminate becomes insufficient by needle punch, and the fineness is 3,000T.
It is preferably a thick fiber bundle on EX. On the other hand, if the fiber bundle is too thick, it is difficult to obtain a thin and uniform fiber sheet, so the fineness is preferably 60,000 TEX or less.

In general, a fiber product is preferable because the thicker the fiber bundle is, the lower the manufacturing cost becomes, but it is difficult to obtain a thin and uniform sheet-like fiber aggregate with a thick fiber bundle. However, in the present invention, a thin and uniform sheet can be obtained even with a thick fiber bundle by the method for manufacturing a fiber sheet of the present invention described later, and a low-cost fiber sheet material can be obtained without deteriorating quality.

The fiber bundle constituting the fiber sheet of the present invention is fiber entangled, and the degree of entanglement is 1.5 to 60 cm in hook drop value (preferably 2 to 40 cm).
cm, more preferably 2 to 20 cm). The fiber sheet of the present invention is laminated such that the sheet becomes pseudo-isotropic in the intermediate step of forming the carbon / carbon composite material of the final product, and the fibers are oriented in the thickness direction of the laminate by a needle punch or the like to strengthen the interlayer. It is suitable for doing. Therefore, if the fiber constituting the sheet material has a hook drop value of more than 60 cm and is less entangled and close to parallel, the fiber easily escapes even if the needle pierces the laminate, so that the fiber does not catch on the hook of the needle, Fiber cannot be oriented in the thickness direction.

On the other hand, if the degree of entanglement is large and the hook drop value is less than 1.5 cm, it becomes difficult to increase the width of the fiber bundle, and there is a problem that a thin and uniform sheet material cannot be obtained. Needs to be not less than 1.5 cm in hook drop value.

The hook drop value referred to in the present invention indicates the degree of intermingling of the fiber bundles constituting the fiber sheet, and is expressed by the weight drop distance of the metal hook.

It is preferable that 0.2 to 1.0% of an oil agent for imparting smoothness and preventing static electricity is adhered to the fiber bundle.

The fiber bundle of the present invention is spread flat, and is uniformly distributed as 10,000 to 35,000 fibers / cm in the number of fibers in the width direction of the fiber sheet as a sheet-like fiber assembly ( The number is preferably 15,000 to 30,000 lines / cm, more preferably 15,000 to 25,000 lines / cm.) The fiber count density of the sheet-like fiber aggregate is 1
If it is less than 000 fibers / cm, the number of laminations when forming into a carbon / carbon composite material increases, and the work becomes complicated, so that there is a problem that the molding cost rises. This makes it difficult for the needle punch to orient the fiber in the thickness direction on the laminate. On the other hand, if the fiber number density exceeds 35,000 fibers / cm, the thickness of each layer increases when molded into a carbon-carbon composite material, and there is a problem that a highly accurate isotropic material cannot be obtained.

FIG. 1 is a perspective view showing the concept of a sheet-like fiber assembly 1 as a fiber sheet for a carbon / carbon composite material of the present invention.

In the sheet-like fiber assembly 1, it is preferable that the fiber bundles 2 are arranged in parallel in one direction, and that adjacent fiber bundles are in contact with each other without any gap and are uniformly dispersed. It is permissible that a slight gap is partially generated due to a variation in the degree of fiber entanglement in the direction.

FIG. 2 shows an example of a sheet-like fiber assembly 3 in which the ends of a plurality of fiber bundles 2 are arranged in such a manner that the ends of adjacent fiber bundles overlap each other. In FIG. 2,
This is an example in which each fiber bundle is alternately arranged vertically.
Even if the width of the fiber bundle fluctuates somewhat, no gap is formed between the fiber bundles, so this is the most preferable arrangement example, but is not limited to this. For example, the arrangement may be such that pieces of shogi that have been beaten down are stacked much higher (lower).

In order to avoid the above-mentioned gap, the end of each fiber bundle 2 is overlapped with the end of the adjacent fiber bundle in the sheet-like fiber assembly 3, so that the width of the fiber bundle due to the variation of the fiber entanglement is reduced. This is a preferable mode because no gap is formed even when a portion having a small spread is formed.

The degree of superposition of both ends of the fiber bundle is not particularly limited, but it is sufficient that 5% or more of the fiber bundle width overlap at one end of one fiber bundle 2. On the other hand, if the overlap is large, the thickness of that portion increases, so 2
0% or less is preferable. More preferably, it is 5 to 15%, and still more preferably 5 to 10%. Alternatively, it is sufficient that one end of one fiber bundle 2 overlaps at least 2 mm. On the other hand, since the thickness increases, the thickness is preferably 10 mm or less, more preferably 2 to 5 mm, and still more preferably 2 to 4 mm.
mm. When there are a plurality of overlapping portions, the degree of overlapping can be calculated by the average as follows. That is, when there are n fiber bundles, there are n-1 overlapping portions, and the total width of each fiber bundle is Wf, the total width of the overlapping portions is Wp, Assuming that the width of the sheet-like fiber aggregate in a state where there is an overlapping portion is Wr, the average Dp of the overlapping is Dp = nWp / ((n-1) Wf) or Dp = n. ( Wf−Wr) / ((n−1) · Wf).

Next, an embodiment integrated as a fiber sheet for a carbon / carbon composite material of the present invention will be described with reference to FIGS.

FIG. 3 shows a fiber sheet 4 in which non-woven fabrics 5a and 5b are bonded to both surfaces of the above-mentioned sheet-like fiber assembly 1 and integrated, and the fibers constituting the non-woven fabric are nylon 6, nylon 66. , Vinylon, polyester, polyethylene, acrylic, polyaramid, PPS,
Organic fibers such as phenol, regenerated fibers such as rayon, and inorganic fibers such as carbon fiber and glass fiber may be used.

Nonwoven fabrics 5a and 5b and sheet-like fiber aggregate 1
The method of bonding may be such that a tacky adhesive or a thermoplastic binder is attached to the bonding surface and bonded, or a non-woven fabric containing a low melting point thermoplastic polymer is used to heat and press-bond (thermal bonding). good.

Among them, a method using a nonwoven fabric containing a low-melting-point thermoplastic polymer is a simple and preferable method.

Since the purpose of the nonwoven fabric is simply to integrate it as a sheet, it is preferably 15 g / m ² or less.

FIG. 4 shows an adhesive net 7 provided with an adhesive material on both sides of the sheet-like fiber assembly 1 as a net.
This shows a fiber sheet 6 integrated by affixing a and 7b, and as a net, a bidirectional net in which yarns having a fineness of 2 to 50 TEX are oriented in a vertical direction and a horizontal direction at an interval of 5 to 30 mm, or It may be a three-way net oriented vertically and obliquely.

A tacky adhesive is adhered to the net, and the net and the sheet-like fiber assembly 1 may be adhered and integrated by the adhesive, or the net may be formed by a composite yarn having a core / sheath structure. The low-melting polymer formed as the sheath component may be adhered to the sheet-like fiber assembly 1 as an adhesive to be integrated. Alternatively, a fiber or a single yarn made of a low-melting polymer may be entangled in the net, or a woven or non-woven fabric made of the low-melting polymer may be interposed between the sheet-like fiber aggregate and the net, and the net may be bonded.

Although FIGS. 3 and 4 show a sheet-like fiber assembly 1 in which a nonwoven fabric or a net is attached to both sides, the sheet-like fiber assembly 1 may be on one side. Further, one surface may be made of a nonwoven fabric as shown in FIG. 3 and the other surface may be made of an adhesive net as shown in FIG.

FIG. 5 shows the warp-direction assisting yarns 10a and 9b arranged on both sides of the sheet-like fiber assembly 1 and the warp-direction assisting yarns 10a and 9b.
Are crosswise integrated with the weft direction auxiliary yarn group while repeatedly penetrating in the thickness direction of the fiber assembly 1. That is,
FIG. 5 shows a fiber sheet 8 integrated by a woven structure using auxiliary yarns. 9a and 9b are weft direction auxiliary yarn groups orthogonal to the fiber bundle, and 10 is arranged in the same direction as the fiber bundle. In the warp direction auxiliary yarns, the weft direction auxiliary yarns 9a are arranged at substantially equal intervals on the surface of the sheet-like fiber assembly 1, and the weft direction auxiliary yarns 9b are arranged at substantially equal intervals on the back surface of the sheet-like fiber aggregate 1. The weft direction auxiliary yarns 9a are arranged in such a relationship that they are located between two adjacent weft direction auxiliary yarns 9b on the back surface of the fiber assembly. And the warp direction assisting yarn 10
Are intersected and integrated with the weft direction auxiliary yarns 9a and 9b while repeating penetration in the thickness direction of the sheet-like fiber assembly. Warp direction auxiliary yarn 10 and weft direction auxiliary yarn 9
It is preferable that a and 9b be polyacrylonitrile fibers, rayon fibers, or the like, which are carbon fiber precursor fibers, because they are carbonized by the final carbonization treatment.

The auxiliary yarn is preferably a thin fiber yarn of 3 to 50 TEX. In the case of a fiber yarn having a thickness of more than 50 TEX, there is a problem that the portion swells and the surface of the molded product becomes uneven. On the other hand, too thin fiber yarns have a problem that yarn breakage is apt to occur during weaving. Therefore, the fineness in the range of 3 to 50 TEX is preferable.

Further, the auxiliary yarn can be bonded to the sheet-like fiber aggregate with a slight low-melting-point thermoplastic polymer, whereby the fiber sheet has excellent form stability and is easy to handle. It is preferred.

Examples of the low melting point thermoplastic polymer include copolymerized nylon having a melting point of 60 to 160 ° C., modified polyester, and polyethylene.

If the arrangement density of the auxiliary yarns is secured as much as possible, the use amount can be reduced as much as possible if the form stability is ensured. In addition, in the weft direction auxiliary yarns, the weaving speed is increased and the productivity is improved. The preferred auxiliary yarn arrangement density is 0.
It is 25 to 2 wires / cm.

FIG. 6 shows a fiber sheet 11 in which a sheet-like fiber assembly is entangled with a fiber by a needle punch and integrated. Although the sheet-like fiber aggregate to be needle-punched may be the fiber aggregate 1 shown in FIG. 1,
If a sheet-like fiber aggregate 3 in which the ends of adjacent fiber bundles are overlapped with each other as shown in FIG. 2 is used instead, the fiber entangled fiber bundles are overlapped with each other, so that a strong integration is achieved. This is a more preferable embodiment.

The needle punch density is preferably from ¹ to 1,000 punches / cm ² , and more preferably from ² to 500 punches / cm ^2.
m ² is more preferred.

FIG. 7 shows a fibrous sheet 12 integrated by stitches. The fibrous sheet 12 is integrated by a stitch thread 13 in a state where a nonwoven fabric 14 is arranged on one side of a sheet-like fiber assembly 3.

FIG. 7 shows an example in which one sheet-shaped fiber assembly 3 in which the ends of adjacent fiber bundles are overlapped with each other is arranged. (Preferably 20 to 90 degrees, more preferably 30 to 90 degrees) includes those that are stitched in a stacked state, and the plurality of layers (preferably 2 to 20, more preferably 2). In the case of (10 to 10), the nonwoven fabric 14 may not be provided if a sheet-like fiber aggregate having a different fiber orientation angle from the loop forming direction is arranged on the side surface of the loop of the stitch.

The stitch yarn 13 is made of acrylonitrile fiber,
Rayon fibers are preferred, but ordinary organic fibers such as nylon fibers and polyester fibers may be used.
It is preferably a thin fiber yarn of ~ 50 TEX.

As in the case of FIG. 6, the cases of FIGS. 3 to 5 and 7 have been described using the example using the sheet-like fiber aggregate 1 shown in FIG. 1, but instead of the sheet-like fiber aggregate 1 shown in FIG. Fiber aggregate 2
May also be used.

FIGS. 8 and 9 are conceptual diagrams for explaining a method for producing a fiber sheet for a carbon / carbon composite material according to the present invention.
Hereinafter, the manufacturing method of the present invention will be described with reference to the drawings, but the present invention is not limited to this embodiment. FIG. 8 is a perspective view showing a method of manufacturing the fiber sheet 4 shown in FIG.
FIG. 9 is a side view showing a method for manufacturing a fiber sheet in which a nonwoven fabric is attached to both surfaces of a sheet-like fiber assembly 3 in which ends of adjacent fiber bundles are overlapped.

In FIG. 8, the fiber bundle 23 is made of continuous fiber of a carbon fiber precursor having a hook drop value of 1.5 to 60 m, and is wound around the bobbin 15 without twist. Is pulled out so that the unwinding twist does not enter, and after being adjusted to a constant pitch by the comb 16,
It passes through the guide roller 18 from under the widening vibration roller 17 and is guided to the hot roller. In addition, as a general rule, the constant pitch indicates that the ratio (Pu / Pd) of the largest pitch (Pu) to the smallest pitch (Pd) is 1.1 or less. However, if there are a plurality of Pu or Pd having the same value, any one of Pu and Pd may be selected.

The pitch of the comb 16 is determined by the thickness of the fiber bundle 23 to be used and the basis weight of the fiber sheet, and is selected as necessary.
1.5 to 10 times (more preferably 2 to 6 times, even more preferably 2 to 5 times) the width of the fiber sheet. In some cases, the fiber sheet becomes uneven and uneven, resulting in an uneven fiber sheet.

The widening vibration roller 17 vibrates in the axial direction of the roller 17 by the rotation of the motor 22 to widen the width of the fiber bundle 23 supplied.
The amplitude is preferably 1 to 20 mm in 100 cycles.

By the action of the widening vibration roller 17, the width of the fiber bundle 23 is expanded to the arrangement pitch of the fiber bundle on the guide roller 18, and is supplied to the hot roller 19 as a sheet having no gap between the fiber bundles. You.

A non-woven fabric containing a thermoplastic polymer fiber having a low melting point is simultaneously supplied from above and below the sheet supplied to the hot roller 19, and the non-woven fabrics 20a and 20b are
And the sheet are adhered and integrated as a fiber sheet.

As for the hot roller 19, it is sufficient that two rollers form a pair, and at least one of the rollers has a built-in heater.

Further, before entering the hot roller, a radiating heater may be provided to soften or melt the thermoplastic polymer fibers contained in the nonwoven fabric, and then, the fibers may be adhered by pressing with a simple nip roller.

The method of bonding the nonwoven fabric and the sheet-like fiber assembly is not limited to the thermoplastic polymer fibers contained in the nonwoven fabric, but may be applied to the nonwoven fabric or the sheet-like fiber assembly in advance using a liquid or solid adhesive. It may be adhered.

Although the method of bonding the nonwoven fabric has been described with reference to FIG. 8, the same method can be used for the bonding of the nets. After the bundle 23 is widened by the widening vibration roller 17 to form a uniform sheet, the bundle 23 is integrated by the respective integrating means (needle punch, stitch).

In the integration by weaving as shown in FIG. 5, after the fiber bundle 23 is widened by the widening vibrating roller 17, the heald mail is used to pass the fiber bundle through the heald for opening the warp yarn. Since the fiber bundle narrows, the heald's mail width is the same as the arrangement pitch of the fiber bundle. After weaving, weaving, and further passing through a widening vibration roller in the woven state, there is no fiber sheet between fiber bundles. Is a preferable method.

Next, a method of manufacturing a fiber sheet in which ends of adjacent fiber bundles are overlapped with each other will be described with reference to FIG.

Basically, it is the same as the manufacturing method described with reference to FIG. 8, except that the fiber bundles supplied at a constant pitch are separated into at least two groups and the width of each fiber bundle is supplied. This is a method for producing a sheet for carbon / carbon composite material, in which each group is overlapped after being widened to a width equal to or greater than the arrangement pitch at the time, and integrated as a sheet by an integrating means. That is, in the case of the example shown in FIG. 9, two sets of widening vibration rollers for the fiber bundle are provided (17a, 17b), and the comb 1
6, the fiber bundles 23 arranged at the same pitch are alternately separated into upper and lower two stages for each fiber bundle.
The third row is the lower row, the third row is the upper row), and the fiber bundle group divided into the upper row is the widening vibration roller 17a and the guide roller 18a.
And the fiber bundle group divided at the lower stage is
7b, the width of each of the fiber bundles 23 is increased by individually widening the fiber bundles through the guide rollers 18b.
The pitch is greatly expanded to preferably 2 to 10 times (preferably 2 to 5 times) the pitch regulated in 6.

By superposing the two sheet-like fiber aggregates thus greatly expanded before entering the hot roller 19, at least the ends of the adjacent fiber bundles overlap each other, and a gap is generated between the fiber bundles. A uniform fiber sheet can be obtained without the need.

If there is a variation in the width of the fiber bundle, the guide rollers 18a and 18b have grooves (pitch 10).
６０60 mm, a height difference between the valley and the valley is preferably 1 to 5 m).

The method of measuring the hook drop value according to the present invention is as follows. That is, the hook drop value is represented by the weight drop distance of the metal hook measured by the measuring device shown in FIGS.

The hook drop value (FD ₍₁₅₎ ) of the fiber bundle constituting the fiber sheet is such that three fiber sheets having a length of 1,000 mm are extracted and each fiber sheet is made so that no fluff is generated. Then, a fiber bundle having a length of 1,000 mm is collected, and the upper end thereof is fixed to the apparatus by the upper clamp 26. Since the width of the fiber bundle to be fixed, that is, the thickness of the fiber bundle affects the hook drop value, the relationship between the width B (mm) of the fiber bundle to be fixed and the fineness T (TEX) of the fiber bundle is calculated according to the following equation. Like
The fiber bundle is fixed to the upper clamp 26 so as to have a uniform thickness.

Next, with a load of 36 mg / TEX applied to the lower end, the width B of the fiber bundle B = 36 × 10 ⁻⁴ × T
It is fixed vertically by the lower clamp 28 so that the gripping interval becomes 950 mm so that no twist is applied.

Next, a metal hook 24 (wire diameter: 1 mm,
Weight (radius 5 mm) attached with weight 25 with cotton thread 29 (distance from upper end of hook 24 to upper end of weight 25: 3)
0 mm) of the metal hook 24 so that the distance from the lower end of the upper clamp to the upper end of the metal hook 24 becomes 50 mm, and release the hand to allow the metal hook 24 to fall freely (from the above 50 mm position to the fall position). The distance to the upper end of the metal hook 24 is measured. Metal hook 2
4 and the cotton thread 29 are made as light as possible.
4, the total weight of the cotton yarn 29 and the weight 25, that is, the weight of the weight is 15 g. The hook drop value (FD ₍₁₅₎ ) was measured ten times for a fiber bundle from one fiber sheet, and expressed as an average of n = 30.

The metal hook 24 is connected to the lower clamp 28
In some cases, the free fall distance is assumed to be 900 mm. For this purpose, the metal hook 24 hits the lower clamp 28, but it is necessary to prevent the cotton thread 29 and the weight 25 from being caught.

The measurement was performed after the fiber sheet was left in an environment of a temperature of 25 ° C. and a relative humidity of 60% for 24 hours.
The test is performed in an environment of 60 ° C. and a relative humidity of 60%.

[0075]

As described above, the fiber sheet for carbon / carbon composite material of the present invention is composed of a fiber bundle composed of continuous fibers of a carbon fiber precursor having a high elongation at break.
The fibers can be oriented in the thickness direction of the sheet without cutting the fibers when the sheet is needle-punched.

Further, the fineness of the fiber bundle is so large that
60,000 tex hook drop value is 1.5-60cm
Since the fiber bundle with the fiber entanglement is spread flat and integrated in one direction, it is easy to handle,
In addition, the orientation of fibers in the thickness direction of the sheet laminate is facilitated by needle punching, and needle punching can be performed efficiently.

Further, since the fiber bundle has a large fineness, the fiber bundle itself is inexpensive, so that a low-cost sheet can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing the concept of a fiber sheet for a carbon / carbon composite material according to the present invention.

FIG. 2 is a perspective view showing the concept of a fiber sheet for a carbon / carbon composite material in which an end portion in a width direction and an end portion of an adjacent fiber bundle overlap with each other according to the present invention.

FIG. 3 is a perspective view of a fiber sheet for a carbon / carbon composite material according to the present invention, which is a fiber sheet in which a nonwoven fabric is bonded and integrated.

FIG. 4 is a perspective view of a fiber sheet for a carbon / carbon composite material according to the present invention, which is integrated by bonding nets together.

FIG. 5 is a fiber sheet for a carbon / carbon composite material according to the present invention, which is integrated by weaving an auxiliary yarn.

FIG. 6 is a perspective view of a fiber sheet for a carbon / carbon composite material according to the present invention, which is integrated by a needle punch.

FIG. 7 is a perspective view of a fiber sheet for a carbon / carbon composite material according to the present invention, which is integrated with a stitch.

FIG. 8 is a perspective view showing a method of manufacturing a fiber sheet for a carbon / carbon composite material according to the present invention, in which a nonwoven fabric is laminated and integrated to manufacture a fiber sheet.

FIG. 9 shows a method for producing a fiber sheet for a carbon / carbon composite material according to the present invention, in which an end of a fiber bundle is overlapped with an end of an adjacent fiber bundle, and a nonwoven fabric is stuck and integrated. It is a side view which shows manufacture.

FIG. 10 is a perspective view of a hook drop measuring device.

FIG. 11 is an enlarged view of a weight portion of the hook drop measuring device.

[Explanation of symbols]

1: sheet-like fiber assembly 2: fiber bundle 3: sheet-like fiber assembly in which the end of a fiber bundle is overlapped with the end of an adjacent fiber bundle 4: fiber sheet 5a, 5b: non-woven fabric 6: Fiber sheet 7a, 7b: net 8: fiber sheet 9a, 9b: weft direction auxiliary yarn 10: warp direction auxiliary yarn 11: fiber sheet by needle punch 12: fiber sheet by stitch 13: stitch yarn 14: non-woven fabric 15: bobbin of carbon fiber precursor fiber 16: comb 17: widening vibration roller 18: guide roller 19: hot roller 20a, 20b: non-woven fabric 21: fiber sheet winding roll 22: motor 23: fiber bundle 24: metal Hook 25: Weight 26: Upper clamp 27: Lower clamp 28: Cotton thread

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) D04H 3/10 D04H 3/10 3/12 3/12 F term (Reference) 4F100 AD11 AG00 AJ05D AK01D AK04 AK21 AK27A AK27D AK33 AK42 AK47 AK48 AK57 AL01 AL06 BA05 BA06 BA10D BA10E BA14A DC11D DC11E DG04A DG04D DG07D DG15B DG15C EC03B EC03D EC032 EC08A EC08C EC082 EC09A EC092 EJ19 EJ42 EJ901 GB90 JA04B JA04C JA04D JA13A JB16D JJ03 JJ07A JL01 JL02 YY00A 4L047 AA03 AB03 AB07 BA03 BA06 BA08 CA03 CB01 4L048 AA07 AA16 AA44 AC18 DA41

Claims (18)

[Claims] 1. A sheet-like fiber aggregate in which a plurality of fiber bundles composed of continuous fibers of a carbon fiber precursor are arranged in parallel in one direction, wherein said fiber bundle has a total fineness of 3,000 to
Hook drop value of 1.5 to 6 at 60,000 TEX
It has a fiber entanglement of 0 cm, and the average fiber number density in the width direction of the sheet-like fiber assembly is 10,000 to 350,000.
A fiber sheet for a carbon-carbon composite material, comprising a sheet-like fiber aggregate integrated at 0 fibers / cm. 2. The fiber sheet for a carbon-carbon composite material according to claim 1, wherein an end of the fiber bundle in the width direction and an end of an adjacent fiber bundle overlap each other. 3. The fiber sheet for a carbon-carbon composite material according to claim 2, wherein 5% or more of the fiber bundle width overlaps at one end of one fiber bundle. 4. The fiber sheet for a carbon / carbon composite material according to claim 2, wherein 2 mm or more is overlapped at one end of one fiber bundle. 5. The fiber sheet for a carbon / carbon composite material according to claim 1, wherein the fiber of the carbon fiber precursor is a polyacrylonitrile fiber or a polyacrylonitrile oxidized fiber. 6. The fiber sheet for a carbon / carbon composite material according to claim 1, wherein a nonwoven fabric is disposed on at least one surface of the sheet-like fiber assembly. 7. The fiber sheet for a carbon-carbon composite material according to claim 6, wherein the nonwoven fabric contains a low-melting-point thermoplastic polymer and is bonded and integrated by thermal bonding. 8. The sheet-like fiber assembly according to claim 1, wherein a net is attached to at least one surface of the sheet-like fiber assembly.
5. The fiber sheet for a carbon / carbon composite material according to any one of 5. 9. A weft direction auxiliary yarn group orthogonal to the fiber bundle is arranged on both surfaces of the sheet-like fiber assembly, and the warp direction auxiliary yarn group arranged in the same direction as the fiber bundle is the thickness of the sheet-like fiber assembly. The fiber sheet for a carbon-carbon composite material according to any one of claims 1 to 5, wherein the sheet-like fiber aggregate is integrated by intersecting with the weft direction auxiliary yarn while repeating penetration in the direction. 10. The fiber sheet for a carbon-carbon composite material according to claim 9, wherein the auxiliary yarns in the warp direction and the weft direction are bonded to the fiber bundle by a thermoplastic polymer having a low melting point. 11. The warp direction and weft direction auxiliary yarns are made of polyacrylonitrile fiber or rayon fiber,
The fiber sheet for a carbon / carbon composite material according to claim 9 or 10, wherein the fineness is 3 to 50 TEX. 12. The fiber sheet for a carbon-carbon composite material according to claim 1, wherein said sheet-like fiber aggregate is integrated by fiber entanglement by a needle punch. 13. The fiber sheet for a carbon-carbon composite material according to claim 1, wherein said sheet-like fiber aggregate is integrated by stitching. 14. The sheet-like fiber aggregate according to claim 1, wherein
14. The fiber sheet for a carbon-carbon composite material according to claim 13, wherein the fiber sheet is laminated at an angle and integrated by stitching. 15. A carbon in which a plurality of the sheet-like fiber aggregates according to any one of claims 1 to 5 are laminated, and some of the fibers are oriented in a thickness direction of the sheet-like fiber aggregates by needle punching. -Fiber sheet laminate for carbon composite material. 16. A plurality of fiber bundles composed of continuous fibers of a carbon fiber precursor having a hook drop value of 1.5 to 60 cm are supplied in a sheet at a constant arrangement pitch, and the width of each fiber bundle is increased by widening means. A method for producing a fiber sheet for a carbon-carbon composite material, wherein the sheet is expanded to a width equal to or greater than the arrangement pitch and then integrated as a sheet by an integrating means. 17. The method according to claim 16, wherein the fiber bundles arranged and supplied at a constant pitch are separated into at least two groups, and the width of each fiber bundle is equal to or greater than the arrangement pitch at the time of supply. A method for producing a sheet for a carbon / carbon composite material, comprising a step of superposing the respective groups and then integrating them as a sheet by an integrating means. 18. The method according to claim 16, wherein said integrating means is at least one method selected from a method of bonding a nonwoven fabric or an adhesive net, needle punching, stitching, and weaving. A method for producing a sheet for a carbon composite material.