JP2001064406A - Preform for fiber-reinforced preform and fiber- reinforced composite material using the same and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a preform that permits efficient lamination operation by allowing woven fabrics to adhere to each other effectively and steadily with a reduced amount of an adhesive and provide a fiber-reinforced composite material using the same. SOLUTION: In the preform 1 for fiber-reinforced composite material comprising a plurality of reinforcing woven fabrics (2a-2c) laminated, at least one of the reinforcing woven fabrics is made of a flat carbon fiber yarn in which a thermoplastic polymer 5 is attached to almost the center of the carbon fiber fabric and additionally is integrally adhered to (B) other adjacent reinforcing woven fabrics through the thermoplastic polymer. The preform is set in the mold, held in vacuum, then an epoxy resin is cast in the mold and cured to give a molded product.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a preform used as a so-called reinforcing material when forming a fiber-reinforced composite material, a fiber-reinforced composite material using the preform, and a method for producing the same. .

[0002]

2. Description of the Related Art Carbon fiber has a low specific gravity and a high strength and a high elastic modulus, and a carbon fiber reinforced composite material obtained by solidifying it with a resin has a high specific strength and a specific elastic modulus. -Established in leisure products and recently started to be used for general industrial purposes.

There are various methods for molding a carbon fiber reinforced composite material. In general, an appropriate molding method is selected in view of required characteristics of a molded product, production cost, and the like. In other words, in aircraft components that require high performance,
Usually, a method is employed in which the prepreg is pre-impregnated with a resin, the prepregs are laminated along a mold, and molded in an autoclave.

[0004] In autoclave molding, however, a high-performance and reliable material can be obtained, but the disadvantage is that the production cost is high. It was still accepted when the price of crude oil rose, but it is unacceptable in the current situation of falling crude oil prices and the economic downturn, and low cost of materials is being actively called for.

Under such circumstances, attention has recently been paid to a resin transfer molding method (so-called RTM molding method).

[0006] The RTM molding method is a method in which a predetermined preform is set in a molding die, the inside of the die is evacuated, and a resin is injected into the die to perform molding. This is a molding method with the potential of obtaining a composite material at low cost.

However, in order to obtain a composite material for aircraft, which requires high performance by the RTM molding method, at a low cost, it is necessary to use a preform manufacturing technique having high productivity and a low viscosity at ordinary temperature. The biggest challenge is to develop a resin that exhibits high compressive strength under high temperature atmosphere.

For example, as a method for efficiently producing a preform, Japanese Patent Application Laid-Open No. Sho 63-152637 discloses a preform in which a thermoplastic polymer is adhered to a woven yarn and adjacent fabrics are adhered to each other with the thermoplastic polymer. Proposed.

In the preform, since the intersection of the warp and the weft is blinded by the thermoplastic polymer, the preform can be manufactured efficiently without misalignment.

However, the thermoplastic polymer to be attached to the woven fabric constituting the preform is prepared by aligning and weaving carbon fiber yarns and thermoplastic polymer yarns at the time of manufacturing the woven fabric, and heating and melting the polymer yarns. Even if the thermoplastic polymer yarn is to be arranged on the carbon fiber yarn, the cross-sectional shape of each woven yarn is elliptical, and the woven yarn is crimped, so that the thermoplastic polymer yarn is kept on the woven yarn. This is an extremely difficult technique, and in fact it is displaced to the side of the yarn or hidden in the intersecting part of the yarn, so it is not located on the surface that becomes the bonding surface between the fabrics, and the fabrics are bonded together. Is not enough.

Therefore, a large amount of the thermoplastic polymer is used to adhere the fabrics to each other, so that the cost is high and, at the same time, the thermoplastic polymer enters between the carbon fibers constituting the carbon fiber yarn, and the resin is reduced. There is a problem that the impregnation impairs the mechanical properties of the composite.

Further, in the conventional carbon fiber woven fabric, since the woven yarns are bundled and the woven structure has a gap between the woven yarns, carbon fiber-rich portions and resin-rich portions are unevenly distributed when a composite material is formed. In addition, a molded product having a high fiber volume ratio (high Vf) cannot be obtained. In addition, since the warp yarn and the weft yarn have a large crimp and are interlaced in a state where the weft yarn interval is small, there is a problem that the high specific strength and specific elastic modulus characteristics of the carbon fiber are not sufficiently exhibited.

On the other hand, the resin for RTM molding needs to have a low viscosity at room temperature and exhibit high mechanical properties as a composite material in consideration of the resin impregnating property of the preform. The members are required to exhibit high performance especially in a high-temperature atmosphere.

However, there is no low-viscosity resin that satisfies the performance required for such aircraft, and the present situation is that future development is expected.

[0015]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the above-mentioned conventional preform and the production method by RTM molding. Provided is a preform capable of efficiently performing lamination work by firmly and securely bonding, a fiber-reinforced composite material using the preform, and RTM.
An object of the present invention is to provide a method for producing a carbon fiber reinforced composite material exhibiting excellent performance by molding at low cost.

[0016]

In order to solve the above-mentioned problems, the present invention provides a preform for a fiber-reinforced composite material, in which a plurality of reinforcing fabrics are laminated, and (A) a preform for the reinforcing fabric. At least one of the fibers is made of a flat carbon fiber yarn having a fineness D (denier) of 3,500 denier or more, and the relationship between the yarn width W (mm) of the warp and weft yarns and the fineness of the carbon fiber yarn is W = 0.05 × D ^1/2 〜0.12 × D
A carbon fiber woven fabric having a cover factor of 95% or more within a range of ^{1/2 and} a thermoplastic polymer adhered to a substantially central portion of the warp or weft yarn width, and (B) another adjacent reinforcing material A preform for a fiber-reinforced composite material, wherein the preform is bonded to a woven fabric by the thermoplastic polymer to be integrated.

Further, the present invention is a fiber-reinforced composite material using the preform for a fiber-reinforced composite material.

Further, the present invention sets the preform for a fiber-reinforced composite material in a mold, and
After holding in a vacuum state of 1 MPa or less, an epoxy resin having a resin viscosity at 25 ° C. of 1.5 to 15 poise and a glass transition point of 120 ° C. or more after curing as a composite material is injected, and the resin is cured and molded. A method for producing a fiber-reinforced composite material, and a fiber-reinforced composite material obtained by the production method.

The warp and weft of the reinforcing fabric constituting the preform of the present invention are bundles of single fibers having a fineness in the range of 0.4 to 0.6 denier, and have a flat cross section ( It is composed of a carbon fiber thread having a thread width of Wmm).

The yarn width W is related to the fineness of the carbon fiber yarn used, and the relationship with the fineness D of the carbon fiber yarn is W = 0.
It is in the range of 05 × D ^{1/2 to} 0.12 × D ^1/2 . Then, a thermoplastic polymer is attached on the wide carbon fiber yarn.

The method for adhering the thermoplastic polymer is as follows: the warp is controlled by a guide so that the thermoplastic low-melting polymer yarn is positioned on the center of the warp or weft supplied with a wide yarn width when weaving a woven fabric. Alternatively, it is supplied in parallel with the weft yarn and formed into a woven fabric form, and then attached on a loom or in a separate step by heating at a temperature higher than the melting point of the thermoplastic polymer. In this way, it is possible to simultaneously determine the intersection of the warp and the weft.

At this time, since the warp and the weft of the woven fabric are interlaced with each other in a flat state, the respective floating portions are flat. Therefore, the thermoplastic polymer yarn and the weft are combined with the woven yarn as in the above-mentioned prior art. It is possible to reliably and stably adhere to the center of the width of the yarn without falling between the yarns.

The thermoplastic polymer serving as an adhesive is stably adhered to the central portion of the flat warp or weft yarn, that is, the outer surface of the fabric, so that when another fabric is laminated thereon, the thermoplastic polymer is used. Can reliably contact other fabric surfaces, and the fabrics can be firmly and reliably bonded to each other.

Here, in the relationship between the fineness D of the carbon fiber yarn and the yarn width W, when the yarn width W is reduced to less than 0.05 × D ^{1/2, the} cross-sectional shape of the woven yarn becomes elliptical. There is a problem that the thermoplastic polymer yarn easily falls between the woven yarn and the adjacent woven yarn, and it is difficult to reliably arrange the woven yarn on the woven yarn.

On the other hand, when the yarn width W is wider than 0.12 × D ^1/2 , there is no fear that the thermoplastic polymer yarn falls between the yarns, but the space between the yarns is large. The binding force between the warp and the weft becomes too weak, and the morphological stability of the woven fabric is reduced, resulting in a woven fabric that is difficult to handle.

Therefore, in consideration of both the stabilization of the arrangement of the thermoplastic polymer and the handleability of the woven fabric itself, the yarn width W is W = 0.05 × D ^1/2に お い て in relation to the used yarn fineness D.
It must be in the range of 0.12 × D ^1/2 .

The carbon fiber thread forming the warp and the weft is preferably non-twisted. When the twist is present, the flat carbon fiber yarns are bundled at the twisted portion, and the yarn width cannot be secured, and at the same time, the portion is thickened and a composite material having a smooth surface cannot be obtained. Further, when a stress is applied, there is a problem that the stress concentrates on the twisted portion and the destruction proceeds from that portion.

The fineness of the carbon fiber yarn of the present invention is 3,
500 denier or more.

Since the production of carbon fiber yarns is carried out at substantially the same firing speed regardless of the thickness, the production cost of a thicker yarn is lower. Weaving the yarn at a coarse density naturally leads to higher productivity and lower processing cost. Therefore, the above-mentioned woven fabric can be reduced in cost in terms of both yarn production cost and woven fabric processing cost.

However, when a thick carbon fiber yarn is used, the crimp of the woven yarn becomes large, and when a stress is applied, there is a problem that the stress is concentrated at the intersection of the warp yarn and the weft yarn and is broken at an early stage.

In the woven fabric constituting the preform of the present invention, thick carbon fiber yarns having a fineness of 3.500 denier or more are arranged at a large pitch in relation to the yarn width W, and are interlaced in a flat shape. As a result, a large crimp as described above does not result, and high mechanical properties can be exhibited. It is most preferable that the arrangement pitch of the carbon fiber yarns is the same as the yarn width. However, in practice, it is difficult to make the arrangement pitch and the yarn width the same because the warp and the weft intersect each other. If the arrangement pitch is too large with respect to the yarn width, that is, if there is a large gap between the yarns, the gap becomes rich in resin, so that there is a problem that a composite material having a high fiber volume ratio (Vf) cannot be obtained. Therefore, the weave yarn arrangement pitch is preferably 1.2 times or less the yarn width. In order to make the crimp of the carbon fiber thread as small as possible, the carbon fiber thread preferably has a flat shape with a yarn width / thickness ratio of 25 or more.

The crimp of the woven yarn is related to (thickness of the woven yarn at the intersecting portion) / (interval of the woven yarn). In the woven fabric used in the present invention, the carbon fiber yarn is interlaced at a flat shape with a large pitch. Since the thickness of the yarn at the intersecting portion is small and the interval between the yarns is large, the crimp is very small and high mechanical properties can be exhibited.

The woven fabric has a cover factor of 95% or more. The reason is that there is a gap between the yarns, and in a woven fabric with a small cover factor, as described above, a composite material having a high fiber content cannot be obtained, and the high specific strength and high specific elastic modulus of carbon fibers cannot be exhibited. Because it will be.

If there is a large gap in the woven fabric, the resin portion becomes rich in that portion. When a stress is applied, the stress concentrates on the resin-rich portion, which causes a problem of breaking at a low load as a starting point of destruction. Yes, the conclusion is that the cover factor as a woven fabric must be 95% or more.

The cover factor is a ratio of the carbon fiber covering when the woven fabric is viewed in a plane, and the yarn spacing (mm) and the yarn width (m) of the woven fabric.
This is a value obtained from m) by the following formula. Next, the type of the carbon fiber yarn used in the present invention is not particularly limited, and may be a PAN-based carbon fiber or a pitch-based carbon fiber. In particular, when the application is for aircraft, the strength is required to be 3,500 MPa because of the required impact resistance.
PA with high strength and high elongation at break of 1.5% or more
N-based carbon fiber yarns are preferred.

The thermoplastic polymer deposited on the warp or weft is not particularly limited, either.
A thermoplastic low melting point polymer having a low melting point of 130 ° C. is preferred because it can be melted during fabric production and easily arranged on a woven yarn.

As the low melting point polymer, copolymerized nylon, copolymerized polyester, polypropylene, polyethylene, phenol and the like can be used. As a method of arranging the thermoplastic polymer on the woven yarn, as described above, the thermoplastic polymer yarn is arranged on the woven yarn by supplying the thermoplastic polymer yarn together with the warp yarn or the weft yarn during the production of the woven fabric, for example, on a loom. And can be easily attached by heating and melting with a far infrared heater.

As the form of the thermoplastic polymer after melting, the thermoplastic polymer may be continuously adhered at the center of the warp or weft yarn width. It may be heated at a high temperature of 20 ° C. or higher to cut the thermoplastic polymer yarn by utilizing the heat shrinkage, and to adhere the particles in the vicinity of the intersecting yarn ends.

When the fibers are attached linearly on the warp or weft yarn, the amount of the thermoplastic polymer serving as an adhesive is buried in the fiber and comes out to the surface of the woven fabric because it is parallel to the fiber direction of the warp or weft yarn. Although the adhesion between the woven fabrics is likely to be insufficient, the presence in the form of particles can be surely made to exist on the surface of the woven fabric, which is preferable.

When the thermoplastic polymer is attached to the flat surface of the warp or weft, it may be attached only to the surface side of the woven fabric or to both sides. Alternatively, one warp or one weft may be alternately attached to both the front and back surfaces.

The amount of the attached thermoplastic polymer is preferably 1 to 5% by weight. If it is less than 1%, it is sufficient to observe the intersection between the warp and the weft, but there is a problem in that the woven fabrics are not easily adhered to each other, and there is a problem that the woven fabrics are easily peeled off even if they are adhered. On the other hand, if it exceeds 5%, the adhesion between the fabrics can be strengthened, but a large amount of the thermoplastic polymer adheres between the carbon fibers at the time of molding, impairing the impregnation of the resin, and the adhesion portion tends to be an unimpregnated portion. There is.

In the preform of the present invention, the woven fabric includes at least one sheet to form a laminated structure, and the surface to which the thermoplastic polymer is attached and the adjacent woven fabric are bonded and integrated with the thermoplastic polymer. . Adhesion of the fabrics, the other fabric on the fabric surface with the thermoplastic polymer attached,
It can be easily carried out by heating above the melting point of the thermoplastic polymer.

Further, by applying a slight pressure during heating, stronger adhesion can be obtained. On the practical side, it is also possible to bond while shaping into a predetermined shape after heating using a press machine. In the case of a long preform, shaping and bonding can be continuously performed using a hot roller or the like.

The shape of the preform material is determined by the shape of the final product. For example, there are various shapes such as a flat plate shape, a cross-sectional shape such as a beam material extending in the form of I, T, C, or a convex or concave surface. Is included.

In particular, since it becomes difficult to simultaneously form a complicated shape, the woven fabrics may be adhered while being formed one by one.

The laminating direction between a plurality of fabrics constituting the preform may be appropriately determined according to the strength characteristics required for the final product. For example, the warp or weft constituting each fabric is placed in the same direction. Or a laminated structure including reinforcing fibers crossed in the 0/90 ° direction or the + 45 / -45 ° direction.

When the laminating direction is different, the molded product may be warped depending on the laminating structure. Therefore, it is preferable to form the laminated product symmetrically with respect to the central axis in the thickness direction.

The preform of the present invention is laminated on the above-described two-way fabric, including a unidirectional fabric in which carbon fiber threads are oriented in the warp direction and the weft is woven with thin fiber yarns. Things are also included.

By laminating such a unidirectional woven fabric, it is effective as a preform of a molded article requiring strength and elasticity in the longitudinal direction of the molded article.

As the thin fiber yarn used as the weft of the unidirectional woven fabric, a glass fiber yarn, a polyaramid fiber yarn, a vinylon fiber yarn, or the like can be used. The fineness of the yarn is preferably a thin yarn of 100 to 500 denier from the viewpoint of reducing the crimp of the warp yarn.

Further, a thermoplastic polymer yarn is aligned with the weft yarn or covered with the thermoplastic polymer yarn and woven into a woven fabric, and then heated to the melting point of the thermoplastic polymer or higher to find the intersection of the warp yarn and the weft yarn. It is preferable that the carbon fiber yarns are not broken when cut into a predetermined size and the handleability is excellent, so that the handleability is excellent.

Next, a method for producing the fiber-reinforced composite material of the present invention using the above-described preform will be described.

First, the above-described preform of the present invention is set in a cavity formed between the upper mold and the lower mold, and the inside of the cavity is evacuated to 0.01 MPa or less to reduce the pressure. Is injected to impregnate the resin into the preform, and when the resin injection is completed, the resin is cured.

The resin used in the method for producing a composite material of the present invention is a thermosetting epoxy resin which is liquid at room temperature, and the resin viscosity at room temperature must be 1.5 to 15 poise.
The lower the viscosity of the resin, the easier it is for the resin to enter the preform and the shorter the resin injection time, which is a favorable tendency.However, if the resin viscosity at room temperature is lowered, the glass transition point of the resin decreases, and the composite material In this case, there is a problem that high mechanical properties cannot be obtained in a high-temperature atmosphere. Therefore, the resin viscosity needs to be 1.5 poise or more.

On the other hand, if the resin viscosity is greater than 15 poise, the fluidity of the resin is reduced, impregnation of the preform with the resin is deteriorated, and unimpregnated portions are formed, and the resin injection time is prolonged. In particular, the woven material constituting the preform used in the present invention has a very tight woven structure with a flat warp yarn and a weft yarn interlaced and a cover factor of 95% or more. It is preferable that the viscosity is as low as possible.

The resin viscosity specified here is JIS K7
This is a value measured 5 minutes after mixing the resin at room temperature of 25 ° C. in accordance with the viscosity test method using a rotational viscometer of the liquid resin described in 117.

The glass transition point of the epoxy resin needs to be 120 ° C. or higher. When the glass transition point is lower than 120 ° C., as described above, high mechanical properties of the molded article in a high-temperature atmosphere cannot be obtained. In particular, there is a problem that it cannot be used for aircraft members and the like that require such characteristics. There is no particular upper limit for the glass transition point, but if the glass transition point is to be made too high, the resin viscosity tends to increase, which is limited by the relationship with the resin viscosity.
The glass transition point defined in the present invention is a value obtained by measuring a completely cured composite material by a DSC method in accordance with JIS K7121 plastic transition temperature measurement method.

The low-viscosity epoxy resin composition having a glass transition point of 120 ° C. or higher and a resin viscosity of 1.5 to 15 poise is a trifunctional or more aromatic epoxy resin having a viscosity of 0.1 to 30 poise. And a curing agent of an aromatic amine compound and / or an alicyclic amine compound having a viscosity of 0.01 to 5 poise. Here, the epoxy resin may be of one kind, but for example, a bifunctional aromatic epoxy resin may be mixed with a trifunctional or higher aromatic epoxy resin. However, it is particularly preferable that the trifunctional or higher aromatic epoxy resin is contained in an amount of 50% by weight or more based on the total epoxy resin weight% from the viewpoint of improving heat resistance.

As a curing method after resin injection, for example, 1
The temperature may be raised to 30 to 180 ° C. and maintained for 1 to 4 hours to completely cure the resin.
After pre-curing for 4 hours, remove from the mold
You may hold | maintain at about 30-180 degreeC for 1-4 hours, and may fully cure.

Further, the flexural modulus of the epoxy resin used in the method for producing a composite material of the present invention is preferably 3.2 GPa or more. Here, the elastic modulus of the resin specified in the present invention is a value obtained by measuring a resin cured under the same curing conditions as a composite material in accordance with JIS K7203 cured plastic bending test method. The elastic modulus of the resin is 3.2G
When it is less than Pa, high compressive strength cannot be obtained as a composite material, the weight increases in order to obtain the necessary strength as a structural material, and as a result, the merit of weight reduction as a carbon fiber reinforced composite material is not exhibited. The resin elongation after curing is 3.5.
% Is preferable. If the resin elongation is small, when stress acts on the composite material, cracks occur in the resin, and the cracks serve as starting points of destruction, so that there is a problem that the composite material is broken with low stress.

Although the above-described molding method uses an upper mold and a lower mold, a plurality of split molds may be combined depending on the shape of the molded product, or may be appropriately selected according to the shape of the molded product. . Since the thickness of the molded product is determined by the gap between the upper and lower molds, a molded product with good dimensional accuracy can be obtained.However, depending on the molded product, place a preform on the lower mold, cover it with a film from above and cover the inside Vacuum bag molding in which a resin is injected in a vacuum state may be used.

When the resin is cured by vacuum bag molding, if the temperature is raised to a high temperature as it is, there is a problem that the bag film and the sealing material are broken. Therefore, the resin is first preliminarily cured at a low temperature of about 60 ° C. It is preferable to completely cure.

As a method of injecting the resin, the pressure in the cavity is reduced, and the resin has an extremely low viscosity of 1.5 to 15 poise, so that the resin can be injected at atmospheric pressure.

When a molded article having a complicated shape, a large molded article, or a molded article having a high carbon fiber content is to be obtained, it takes time to inject the resin.
Injecting at a pressure of 7 MPa is a preferable method because the molding time can be shortened.

Further, the resin to be injected may be heated beforehand to lower the viscosity of the resin before the injection.

[0066]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the preform according to the present invention, in which three warp yarns and weft yarns of woven fabrics 2a, 2b and 2c are laminated in the same direction, respectively. A thermoplastic polymer 5 is adhered on the weft yarn 3 of 2b and 2c, and the preform 1 in which the woven materials 2a and 2b and the woven materials 2b and 2c are firmly bonded and integrated with the thermoplastic polymer is used. Has formed.

The woven material 2a may be a woven fabric to which the thermoplastic polymer is not attached, but may be laminated so that the surface to which the thermoplastic polymer is attached is in contact with the lower woven fabric 2b.

FIG. 2 shows an example in which the laminated structure of the woven materials is different. The fiber axes of the woven fabrics constituting the woven fabrics 7a and 7b are oriented in the order of 0 ° / 90 °, ± 45 °, 0 ° / 90 °. In the laminated preform 6, the respective fabrics 7a, 7b, 7c are bonded by a thermoplastic polymer 5 attached on the yarn. By including ± 45 ° in this manner, an excellent molded product having isotropy in the plane direction can be obtained.

FIG. 3 shows an example of a preform 8 including a unidirectional woven fabric in which carbon fiber yarns are oriented in one direction together. The fiber axes of the constituent fibers of the woven fabrics 9a and 9b are 0 ° / 90 °, 0 °.
The layers are laminated in the order of {, 0} / 90 °, and are bonded with the thermoplastic polymer 5 in the same manner as described above.

Although not shown, a thermoplastic polymer is attached to the surface of the woven material 9a that overlaps with the unidirectional woven fabric, and is bonded to the unidirectional woven fabric 9b.

By including the unidirectional woven material, the amount of carbon fibers in the 0 ° direction can be increased, and the strength and elastic modulus in the 0 ° direction can be increased.

The laminating direction of the woven material of the present invention may be appropriately selected so as to satisfy the mechanical properties required for the molded product.

FIG. 4 is a cross-sectional view of an I-shaped preform 10 for molding a beam material having an I-shaped cross section. The flange portion has an outer surface of 0 ° / 90 ° (11 °).
a), 0 ゜ (11b), 0 ゜ (11b)
Also, the web part is 0 ° / 90 ° (11 °) from the outer surface.
a), ± 45 ° (11c), and ± 45 ° (11c), and the surfaces where the fabrics are in contact with each other are firmly bonded with a thermoplastic polymer to form the preform 10.

With the above laminated structure, when a bending load is applied to the beam material, a large amount of carbon fibers are arranged in the 0 ° direction on the flange portion where the highest tensile or compressive stress is applied, so that bending is suppressed. It is effective for

Although a large shear stress acts on the web for bending, a large amount of ± 45 ° carbon fibers are oriented in the web, so that shear fracture can be prevented.

As described above, the preform that maintains the shape of the molded article with effective fiber orientation can be set in a molding die as it is, and molding can be performed efficiently.

When forming the flat plate as shown in FIGS. 1 to 3, it is possible to stack the sheets one by one on a forming die at the time of forming. Even if you try to laminate materials of complex shapes during molding, they will quickly fall apart and cannot be laminated accurately, and you will have to spend a lot of time laminating on the molding die. And the productivity is poor.

In the case of the preform of the present invention, even if the preform is of a complicated shape, it can be easily produced one by one, or can be easily laminated and bonded together so that a high-precision preform can be easily produced. Even if there is no molding die, the molding can be performed in advance, and the molding can be efficiently performed because only the time required to set the molding die when it is empty is sufficient.

FIG. 5 shows an example of a method for producing a beam material having a cross section of an I-shape in a composite material using the preform of the present invention, and shows that the preform is set in a mold. It is the perspective view showing the fracture surface of the center part of the metal mold | die for easy understanding.

In the drawing, the woven materials are laminated in a predetermined configuration, and the I-shaped beam material preform 10 of FIG. 4 bonded to each other by the thermoplastic polymer arranged on the yarn is divided into divided molds 12a, 12b, 13a, 13b, 17a, 17b
And the mating surfaces of the respective molds are sealed with a sealing material in order to completely seal the inside of the cavity.

Then, after vacuuming was performed through the suction hole 16 in the direction of the arrow, the resin injection valve 14 was opened to open the resin tank 1.
The resin in 5 is injected into the cavity, and the preform 10 is impregnated with the resin. When injecting the resin, the inside of the tank 15 is sealed, and the injection time can be reduced by pressurizing the inside of the tank.

By heating the entire mold in which the obtained impregnated preform 10 is set and curing the resin, a composite material having excellent mechanical properties can be obtained.

[0084]

EXAMPLES Example 1 Warp and weft have a tensile strength of 4,900 MPa and a tensile modulus of 230 G.
Pa, a breaking elongation of 2.1%, a yarn fineness of 7,200 denier, a yarn width of 6.5 mm, and a flat, non-twisted carbon fiber yarn. The fiber yarn is supplied while keeping the flat shape, and the basis weight is 193 g /
It was weaving the fabric of m ^2.

During weaving, 100 denier low-melting copolymer nylon was fed together approximately at the center of all the warp yarns.

After forming into a woven fabric, the fabric was heated with a far-infrared heater provided on a loom to melt the low-melting copolymer nylon,
The intersection between the warp and the weft was observed, and at the same time, a low-melting copolymer nylon, which was a thermoplastic polymer, was adhered onto the warp.

Further, regarding the weft yarn, the width of the flat carbon fiber was slightly narrowed by beating, so that the weft was made into a woven fabric, and the yarn width was widened by air injection on a loom.

Table 1 shows the yarn width and the cover factor of the obtained carbon fiber fabric.

A preform 10 having a laminated structure as shown in FIG. 4 was manufactured in order to form a beam material having the I-shaped cross section from the above woven fabric.

Regarding the method of manufacturing the preform, first, six woven fabrics for forming the web portion were laminated and bonded to the web portion as much as possible. At this time, in order to prevent adhesion of a portion extending to the flange portion, a release film was sandwiched between layers of the portion extending to the flange portion.

Next, in order to bend both ends of the part where only the part to be the web part was adhered and to include it in the flange part, three of the six woven fabrics laminated using the shaping mold were bent to one side at a right angle. Glue the parts together and the remaining 3
The sheets were adhered while bending to the opposite side. From the portion extending to the flange portion, three pieces of fabric for the flange portion were laminated while being bonded to each other, thereby producing a preform having an I-shaped cross section.

[0092] For the unidirectional woven fabric included in the flange portion, the same carbon fiber yarn as that of the bidirectional woven fabric is used for the warp yarn.
As the weft, a 203 denier glass fiber thread covered with 50 denier low melting point copolymerized nylon at a twist number of 250 turns / m was used, and the warp yarn density was 4.75.
The book and the weft were woven at a density of 3 / cm under ordinary weaving conditions. At this time, the basis weight of the carbon fiber alone is 380 g / m ² .

Next, in order to obtain a molded product having an I-shaped cross section having a height of 100 mm, a flange width of 80 mm, a flange thickness of 1.55 mm, a web thickness of 1.15 mm and a length of 1.5 m. It was set in the mold shown in FIG.

When setting the mold, first, the preform 10 is set on the side surface 12a of the split mold, and then the mold 12b on the opposite surface is fitted, and the upper mold 13a and the lower mold 13b are attached. We were able to set efficiently in time.

Table 1 shows the preform manufacturing time including the mold setting time in order to quantitatively express the effect of the present invention. Comparative Example 1 As a comparative example, the warp and the weft have a tensile strength of 3,630 MPa and a tensile modulus of 230 GP.
a, elongation at break 1.5%, the usual carbon fiber fabric of 193 g / m ² basis weight using a carbon fiber thread of yarn fineness of 1,780 deniers, low melting copolymerized with all of the warp A preform was manufactured in the same manner as in the example, using a woven fabric prepared by aligning nylon 50 denier.

Since the warp and the weft of the woven fabric have a large crimp and are interlaced with each other, the low-melting copolymer nylon yarn woven together with the warp is located on the side of the warp, and the low-melting copolymer nylon is used. Although the content was large, it was hardly adhered to each other because it did not appear on the surface of the woven fabric, and the woven fabric was laminated while holding it one by one in a molding die.

[0097] The weaving yarn was not broken because it was stagnant, but the preform could not be formed due to incomplete adhesion. When the molds were assembled, the woven material was displaced and wrinkled, and it took much time.

The results of producing the preform are shown in Table 1.

[0099]

[Table 1]

(Example 2) The two-way woven fabric used in Example 1 was cut into a size of 30 cm width x 50 cm length, and a flat preform was produced by laminating four pieces in the same direction while adhering. Then, it is set in a mold including an upper mold and a lower mold, and the inside of the mold is depressurized to a degree of vacuum of 0.01 MPa or less. 3.5 GPa, glass transition point of cured resin is 23
An epoxy resin having a glass transition point of 215 ° C. as a composite material at 0 ° C. was injected.

The height of the space formed between the upper mold and the lower mold, that is, the thickness of the molded product was set to 0.77 mm.

When the resin starts to come out of the evacuation hole, the injection of the resin is stopped. In this state, the resin is first pre-cured at 60 ° C. for 180 minutes, then raised to 180 ° C. at a rate of 2 ° C./min and left for 120 minutes. And cured.

Table 2 summarizes the resin injection time of this example and the results of evaluating the mechanical properties of the obtained cured plate. (Comparative Example 2) With the preform used in Example 2 and the same mold, the inside of the mold was depressurized to a degree of vacuum of 0.01 MPa or less, and then the resin viscosity was 20 poise and the elastic modulus of the cured resin was 3 .4 GPa, glass transition point of cured resin is 203 ° C.,
An epoxy resin having a glass transition point of 190 ° C. as a composite material was injected and molded under the same curing conditions as in Example 2.

Since the resin viscosity is high, the resin injection time is 15
It took a very long time, and even in the molded product, the resin was not sufficiently rotated, and a resin defect was found on the surface, resulting in low mechanical properties of the cured plate.

Table 2 summarizes the results of the resin injection time and the evaluation of the mechanical properties of the cured plate in the same manner as in Example 2. (Comparative Example 3) The bidirectional woven fabric used in Comparative Example 1 was molded by the same resin and the same molding method as those used in Example 2.

Although the laminated product had an inadequate adhesion between the layers, there was no particular problem because the laminated structure was simple. Also, the resin injection time is almost the same as that of the second embodiment.
Fast resin impregnation was achieved.

However, since the woven yarn crimp of the woven material constituting the preform was large, the strength development rate of the cured plate was low. Table 2 shows the molding results.

[0108]

[Table 2]

[0109]

As described above, in the preform of the present invention, by using a warp or weft having a wide yarn width, the woven fabric having the thermoplastic polymer adhered to the surface is securely bonded to each other. Because it is molded in the state
The dimensional accuracy is increased, the dies can be easily and reliably mounted on a molding die, and the molding time can be greatly reduced.

Further, since the thermoplastic polymer is securely adhered to the surface of the woven fabric, the amount of the thermoplastic polymer used as an adhesive is small, and the thermoplastic polymer is contained in the carbon fiber thread bundle. There is no intrusion. Therefore, R
A composite material exhibiting high strength and high elastic properties of carbon fibers without hindering resin impregnation during TM molding.

Also, since at least one of the reinforcing fabrics constituting the preform is woven at a coarse density using a thick carbon fiber yarn having a low yarn production cost,
Since the preform is formed while the manufacturing cost is low and the woven material is easily bonded, a preform with low manufacturing cost can be obtained.

Further, the relationship between the yarn width W (mm) of the warp and weft yarns and the fineness D (denier) of the carbon fiber yarn used is W =
Since the yarn is crossed with a wide cross-sectional shape of 0.05 × D ^{1/2 to} 0.12 × D ^1/2 , the crimp of the woven yarn is not easily generated, and the cover factor is 95% or more and there is almost no void. Since the reinforced fabric is used, a composite material that maximizes the high specific strength and specific elastic modulus of the carbon fiber can be obtained.

Further, according to the method for producing a carbon fiber reinforced composite material of the present invention, a preform exhibiting the above-mentioned effects is set in a mold, evacuated, and then 1.5 to 15 at room temperature.
Injection and molding of a resin with a poise and low viscosity, and a high glass transition point after curing, ensure that the preform is impregnated with the resin, and the obtained molded product is high even in a high-temperature atmosphere. An excellent fiber reinforced composite material exhibiting mechanical properties is obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a preform of the present invention.

FIG. 2 is a perspective view showing an example of an embodiment different from the preform of FIG. 1;

FIG. 3 is a perspective view of a preform different from the preforms of FIGS. 1 and 2;

FIG. 4 is a perspective view showing one embodiment of a preform of the present invention having an I-shaped cross-sectional shape.

FIG. 5 is a perspective view of one embodiment for explaining a method for forming a carbon fiber reinforced composite material of the present invention.

[Explanation of symbols]

 1: Preform 2: Woven material 3: Weft yarn 4: Warp yarn 5: Thermoplastic polymer (adhesive) 6: Preform 7: Woven material 8: Preform 9: Woven material 10: Preform 11: Woven material 12: Gold Mold (side surface) 13: Mold (upper and lower surfaces) 14: Resin injection valve 15: Resin tank 16: Suction port 17: Mold (end surface)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B32B 27/04 B29C 67/14 G // C08L 63:00 F term (Reference) 4F072 AA04 AA07 AB09 AB10 AB15 AB33 AC02 AD23 AD51 AG02 AG16 AH36 AK03 4F100 AD11A AG00A AG00B AK01C AK48 AK53G BA03 BA07 BA10A BA10B BA22 BA31 BA32 CB02 DG01A DG12A DG12B DG18A DG18B DH00 DH01A DH01B05 J01 AJG04 A HA01 HA34 HA35 HA43 HA44 HA47 HB01 HC07 HC16 HC17 HG02 HM02 HM06

Claims (9)

[Claims] 1. A preform for a fiber-reinforced composite material comprising a plurality of reinforcing fabrics laminated, wherein (A) at least one of the reinforcing fabrics has a fineness D (denier) of 3,
It is made of a flat carbon fiber yarn of 500 denier or more, and the relationship between the yarn width W (mm) of the warp and weft yarns and the fineness of the carbon fiber yarn is W = 0.05 × D ^{1/2 to} 0.12 × D A carbon fiber woven fabric having a cover factor of 95% or more within a range of ^{1/2 and} a thermoplastic polymer adhered to a substantially central portion of the warp or weft yarn width, and (B) further reinforcing other adjacent fibers A preform for a fiber-reinforced composite material, wherein the preform is bonded to a woven fabric by the thermoplastic polymer to be integrated. 2. The preform for a fiber-reinforced composite material according to claim 1, wherein the thermoplastic polymer is attached in a granular form to the surface of the carbon fiber fabric. 3. The fiber reinforced composite material according to claim 1, wherein the carbon fiber woven fabric and the other reinforcing woven fabric are laminated so that the warp yarns or the weft yarns are laminated in the same axial direction. preform. 4. The carbon fiber woven fabric and the other reinforcing woven fabric include those in which the axial direction of each warp or weft is at least one of 0 and 90 ° direction or ± 45 ° direction. 3. The method according to claim 1, wherein
The preform for a fiber-reinforced composite material according to item 1. 5. The fiber reinforced composite material according to claim 1, wherein the warp yarn comprises a carbon fiber yarn and the weft yarn includes a carbon fiber woven fabric comprising a glass fiber yarn. preform. 6. A fiber-reinforced composite material using the preform for a fiber-reinforced composite material according to claim 1. 7. The preform for a fiber-reinforced composite material according to claim 1 is set in a mold, and the inside of the mold is kept in a vacuum state of 0.01 MPa or less, and then 25%.
A fiber characterized by injecting an epoxy resin having a glass transition point of 120 ° C. or more as a composite material and having a resin viscosity at 1.5 ° C. within a range of 1.5 to 15 poise and curing and molding. A method of manufacturing a reinforced composite. 8. The method for producing a fiber-reinforced composite material according to claim 7, wherein the cured product of the epoxy resin has a flexural modulus of 3.2 GPa or more. 9. A fiber-reinforced composite material obtained by the production method according to claim 7. Description: