JP7384029B2 - Fiber fabrics and carbon fiber reinforced composite materials - Google Patents

Description

The present invention relates to a fiber fabric that exhibits excellent properties as a fiber-reinforced composite material and is suitable for a wide range of uses such as reinforcement for civil engineering and construction and general industrial use, and a carbon fiber-reinforced composite material using the same.

Fiber-reinforced composite materials, which are made by combining various reinforcing fibers and various matrix resins, are lightweight and have excellent mechanical properties, so they are suitable for construction applications (reinforcing materials for buildings, etc.), general industrial applications, and automotive applications (automotive parts). ), sports applications (sports equipment, bicycle parts, etc.), aerospace applications (aircraft parts, etc.), etc.

As a manufacturing method for fiber-reinforced composite materials, for example, reinforcing fiber base materials not impregnated with the matrix resin composition are piled up on a mold, which is then impregnated with the matrix resin composition and cured (hand-laying). methods such as up method, resin transfer molding (RTM) method, vacuum assisted resin transfer molding (VaRTM) method, etc. are known.

As the reinforcing fiber base material used for impregnation, reinforcing fiber fabrics are often used in which reinforcing fiber threads are used in both or one of the warp and weft to form a woven structure. Reinforced fiber fabrics have excellent shape retention of the base material because the fiber threads bind each other, and can be produced using simple equipment.
In particular, when surface smoothness or unidirectional mechanical properties are important, unidirectional reinforcing fibers are used in which the warp is a reinforcing fiber yarn and the weft is an auxiliary fiber yarn with a yarn fineness smaller than that of the reinforcing fiber yarn. Textiles are used.

The unidirectional reinforcing fiber fabric described in Patent Document 1 has warp yarns made of carbon fiber multifilament yarns, with a large number of warp yarns lined up horizontally, and thin glass fibers with a low weaving density. By interweaving these auxiliary fiber yarns in a flat weave, a sheet-like woven fabric suitable for forming fiber-reinforced molded products is obtained. Compared to reinforcing fiber fabrics in which reinforcing fiber threads are woven together, unidirectional fabrics have a smaller crimp amount of reinforcing fiber threads at the intersections of warp and weft threads, so molded products made by integrating them with resin compositions. Superior in surface smoothness and mechanical strength.

However, when inserting a weft auxiliary fiber yarn into an array of warp carbon fiber multifilament yarns in a unidirectional reinforced fiber fabric, each warp carbon fiber multifilament yarn is squeezed into a weft auxiliary fiber yarn, resulting in It has a substantially elliptical cross-sectional shape. Since the warp carbon fiber multifilament yarn is restrained by the weft auxiliary fiber yarn when pressed against a flat surface such as a mold during molding, the end portions in the cross-sectional direction of the warp carbon fiber multifilament yarn are thinner than the center portion. In a molded product, the amount of resin is excessive in the area between the warp carbon fiber multifilament yarns, and the surface smoothness decreases due to the occurrence of sink marks.

Other unidirectional reinforcing fiber base materials used for impregnation include a sheet in which carbon fiber multifilament threads are arranged in parallel and a mesh made of inorganic or organic fiber threads is integrated, as described in Patent Document 2. There is a unidirectional knitted fabric base material which is knitted as shown in FIG. Even in a unidirectional knitted fabric base material, there is a problem in that the amount of resin is excessive in the region near the stitch thread penetration part, and the surface smoothness is reduced due to the occurrence of sink marks.
Further, the unidirectional knitted fabric base material requires a complicated and large-scale multi-axis loom for production, which may be disadvantageous in terms of cost. In addition, since a continuous mesh-like body must be used, it is not possible to increase the proportion of reinforcing fibers in the molded product, and furthermore, the amount of resin between the layers of the molded product is excessive, resulting in poor interlaminar shear strength and impact strength. There is a point.

Other unidirectional reinforcing fiber base materials used for impregnation include the unidirectional reinforcing fiber base material described in Patent Document 3, in which a sheet-like material in which carbon fiber multifilament threads are arranged in parallel is adhesively fixed on one side to a mesh-like material. There is a reinforced fiber composite base material. However, manufacturing such a unidirectional reinforced fiber composite base material requires special equipment different from a commonly used loom. In addition, since a continuous mesh-like body must be used, it is not possible to increase the proportion of reinforcing fibers in the molded product, and furthermore, the amount of resin between the layers of the molded product is excessive, resulting in poor interlaminar shear strength and impact strength. There is a point.

Patent No. 3991440 Japanese Patent Application Publication No. 2004-209667 Patent No. 03099730

The purpose of the present invention is to focus on the above-mentioned current situation, and to provide a fiber that uses carbon fiber multifilament yarn as a reinforcing fiber, has excellent surface smoothness when molded integrally with a resin, and is easy to manufacture. An object of the present invention is to provide a woven fabric and a carbon fiber reinforced composite material using the same.

The present invention was made against the above background, and includes the following aspects [1] to [9].
[1] A fiber fabric including a sheet in which a plurality of carbon fiber multifilament threads are arranged in parallel, and a plurality of auxiliary fiber threads,
The fiber fabric is woven with the carbon fiber multifilament yarn as the warp yarn and the auxiliary fiber yarn as the weft yarn,
When the number of the carbon fiber multifilament yarns in the fiber fabric is N, and the insertion density of the auxiliary fiber yarns is D yarns/m, at least one of the carbon fiber multifilament yarns is the auxiliary fiber yarn. A fiber fabric having a surface where the density Y at the intersection with D/N pieces/m or less.
[2] The fibrous fabric according to claim 1, wherein both sides include carbon fiber multifilament yarns having surfaces in which the density Y of the intersection points exceeds D/N pieces/m.
[3] The fiber fabric according to [1] or [2], wherein carbon fiber multifilament yarns that do not have a surface where the density Y of the intersection points is D/N pieces/m or less are not arranged next to each other. .
[4] The fibrous fabric according to any one of [1] to [3], wherein the auxiliary fiber yarn has a smaller yarn fineness than the warp carbon fiber multifilament yarn.
[5] The fiber fabric according to any one of [1] to [4], wherein the carbon fiber multifilament yarn and the auxiliary fiber yarn are bonded to each other by a thermoplastic polymer at the intersection point.
[6] The fibrous fabric according to any one of [1] to [5], wherein the auxiliary fiber yarn is glass fiber to which a thermoplastic polymer is attached.
[7] The fiber fabric according to any one of [1] to [6], wherein the warp carbon fiber multifilament yarn has a number of filaments of 24,000 to 100,000.
[8] A carbon fiber reinforced composite material comprising a thermosetting resin composition and the fibrous fabric according to any one of [1] to [7].
[9] A carbon fiber reinforced composite material comprising a thermoplastic resin composition and the fibrous fabric according to any one of [1] to [7].

According to the present invention, an easy-to-manufacture fiber fabric that uses carbon fiber multifilament threads as reinforcing fibers and has excellent surface smoothness when molded integrally with a resin, and carbon fibers using the same. Reinforced composite material can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a top view which shows an example of the fiber fabric based on one embodiment of this invention. FIG. 1 is a cross-sectional view showing an example of a fiber fabric according to an embodiment of the present invention. This is an example of a loom that is a means for manufacturing the fabric of the present invention.

(fiber fabric)
The present invention is a fiber fabric including a sheet in which a plurality of carbon fiber multifilament threads are arranged in parallel, and a plurality of auxiliary fiber threads (hereinafter sometimes referred to as a unidirectional reinforcing fiber fabric). A carbon fiber multifilament yarn is a yarn in which a large number of carbon fiber single filaments are aligned in substantially the same direction and unified by a sizing agent or the like. Auxiliary fiber threads are threads made of any material that are introduced into the base material not for the purpose of bearing the load, but for the purpose of restraining the reinforcing fibers that bear the load and integrating the base material. It is. The unidirectional reinforcing fiber fabric is woven with carbon fiber multifilament yarns as warp yarns and auxiliary fiber yarns as weft yarns. The term woven means that a plurality of warp threads and a plurality of weft threads running perpendicular to each other switch their positions in the thickness direction and are combined vertically to form a plane and are integrated. It is preferable that the carbon fiber multifilament yarn and the auxiliary fiber yarn are bonded to each other at their intersections. The intersection is a portion where the carbon fiber multifilament yarn and the auxiliary fiber yarn are in contact, and may be a plane or a line. When the number of carbon fiber multifilament threads in the unidirectional reinforcing fiber fabric is N, and the insertion density of the auxiliary fiber threads is D threads/m, at least one of the carbon fiber multifilament threads is the auxiliary fiber thread. It has a surface where the density Y of the intersection points with is equal to or less than D/N pieces/m. The insertion density D of the auxiliary fiber threads is preferably 20 to 500 threads/m. Carbon fiber multifilament yarn has two surfaces parallel to the fiber direction, and the density Y of the intersection with the auxiliary fiber yarn on one of the surfaces is D/N pieces/m or less, so that it is smooth. Excellent in sex. From the viewpoints of strength and appearance, the directional reinforcing fiber fabric preferably includes carbon fiber multifilament yarns on both sides of which the density Y of the intersection points exceeds D/N pieces/m. The density Y of the intersection points is calculated by counting the portion where one surface of the carbon fiber multifilament yarn and the auxiliary fiber yarn are in contact with each other per unit length. Y is preferably D/(10×N) pieces/m or less, and more preferably 0 pieces/m. That is, it is preferable that the unidirectional reinforcing fiber fabric includes carbon fiber multifilament yarns having no intersections with the auxiliary fiber yarns on one surface. For example, if the mutual spacing between the auxiliary fiber yarns 2 is 10 mm, then in the carbon fiber multifilament yarn 1b in FIG. In the multifilament yarn, the density of intersection points is 100 pieces/m on the 10 plane, and 0 pieces/m on the 11 plane.

(Carbon fiber multifilament yarn)
The carbon fiber multifilament yarn used as the reinforcing fiber in the present invention is not narrowed down to the weft auxiliary fiber yarn except for the areas where it intersects with the weft auxiliary fiber yarn on both sides of a narrow range in the longitudinal direction. Can take any cross-sectional shape. Therefore, when a surface where the density number Y of intersection points is D/N pieces/m or less comes into contact with a smooth surface such as a mold, the carbon fiber single filaments constituting the carbon fiber multifilament yarn will move along the smooth surface. It has a widening approximately trapezoidal cross-sectional shape. At this time, since voids are created between adjacent carbon fiber multifilament threads, sink marks are suppressed and excellent surface smoothness is exhibited when integrated with resin to form a molded product. The higher the yarn fineness, the more likely the cross-sectional shape of the warp carbon fiber multifilament yarn, where the surface where the density number Y of intersection points is D/N pieces/m or less is in contact with the smooth surface, becomes approximately trapezoidal, resulting in higher surface smoothness. Molded products can be obtained. The number of yarn filaments is preferably 24,000 or more, more preferably 40,000 or more from the viewpoint of smoothness of the molded product. On the other hand, from the viewpoint of productivity, the number is preferably 100,000 or less, and more preferably 60,000 or less. The yarn fineness is preferably 1600 mg/m or more, more preferably 3000 mg/m from the viewpoint of the smoothness of the molded product. On the other hand, from the viewpoint of productivity, it is preferably 7500 mg/m or less, more preferably 4500 mg/m or less.
In order to improve productivity, the diameter of the filaments constituting the carbon fiber multifilament yarn is preferably 4 μm or more, more preferably 6 μm or more. The thickness is preferably 16 μm or less, more preferably 14 μm or less in order to exhibit high physical properties with homogeneity in the inner and outer peripheral portions. Further, the tensile strength of carbon fiber is preferably 3000 MPa or more, more preferably 4000 MPa or more, since the load that can be borne is important for building material reinforcement and industrial use members. Furthermore, since high-strength carbon fibers are expensive, the tensile strength is preferably 8,000 MPa or less, more preferably 7,000 MPa or less from the viewpoint of cost effectiveness. . In the present invention, the tensile strength of carbon fiber refers to strand strength measured in accordance with JIS R 7601.

The convergence of the carbon fiber multifilament yarn is achieved by appropriately deforming the cross-sectional shape of the warp carbon fiber multifilament yarn, where the surface where the density number Y of the intersection points is D/N pieces/m or less is in contact with the smooth surface, and forming a molded product. The hook drop value is preferably 100 mm or more, more preferably 500 mm or more, since high surface smoothness can be obtained and the weavability and strength are improved due to the generation of fuzz. On the other hand, the hook drop value is preferably 1000 mm or less, more preferably 900 mm or less, since it becomes easier to handle as a yarn and improves weaving properties. Here, the hook drop value is a factor related to the cohesiveness of carbon fiber multifilament yarn, and a hook (radius 5 mm, metal wire diameter 1 mm) with a total weight of 30 g and a weight are inserted into the yarn arranged vertically. It is measured as the falling distance when the object is dropped.

The carbon fiber used in the present invention contains 0.01 to 5 mass of a substance having one or more functional groups selected from epoxy groups, hydroxyl groups, amino groups, carboxyl groups, carboxylic acid anhydride groups, acrylate groups, and methacrylate groups. % and can be used as a sizing agent to improve the convergence of fiber bundles and the adhesion between carbon fibers and matrix resin when made into a carbon fiber reinforced composite material.

(Weft auxiliary fiber yarn)
As the weft auxiliary fiber yarn used in the present invention, inorganic fibers such as glass fiber, carbon fiber, and basalt fiber, and organic fibers such as polyaramid fiber, vinylon fiber, and polyester fiber can be used, and the type thereof is not particularly limited.
Since the crimp of the weft auxiliary fiber yarn is reduced and the strength is improved, the yarn fineness is preferably 2 mg/m or more, more preferably 5 mg/m or more, and even more preferably 10 mg/m or more. In addition, since it is difficult to cut during weaving or handling, it is preferably 2000 mg/m or less, more preferably 200 mg/m or less, and even more preferably 50 mg/m or less.
In addition, from the viewpoint of convergence, the yarn fineness of the weft auxiliary fiber yarn is preferably 0.01% or more, more preferably 0.05% or more, with respect to the yarn fineness of the warp carbon fiber multifilament yarn. .1% or more is more preferable. On the other hand, from the viewpoint of smoothness, it is preferably 100% or less, more preferably 10% or less, and even more preferably 1% or less.

In order to bond the warp carbon fiber multifilament yarn and the weft auxiliary fiber yarn, it is possible to use a weft auxiliary fiber yarn to which a thermoplastic polymer is continuously attached. Thermoplastic polymers used include nylon, copolymerized nylon, polyester, vinylidene chloride, vinyl chloride, polyurethane, and the like. Among these, copolymerized nylons, such as copolymerized nylons of nylon 6, 66, and 610, and copolymerized nylons of nylons 6, 12, 66, and 610, are preferred because they have good adhesion to thermosetting resins. From the viewpoint of ease of handling, shape retention of the base material, and environmental resistance, glass fibers to which a thermoplastic polymer is attached are preferable. The method of attaching the thermoplastic polymer to the weft auxiliary fiber yarn is not limited in any way, such as plying, covering, and pulling.

(Aspects of fiber fabric)
The fiber fabric of the present invention consists of a large number of carbon fiber multifilament yarns as warp yarns and weft auxiliary fiber yarns. A thermoplastic polymer may be used as a means for adhering the warp carbon fiber multifilament yarn and the weft auxiliary fiber yarn at their intersections, but other means may be used.
As the means for supplying the thermoplastic polymer, it is preferable to use a weft auxiliary fiber yarn to which the thermoplastic polymer is continuously attached, but carbon fiber multifilament yarn to which the thermoplastic polymer is continuously attached, carbon fiber multifilament The method is not limited to applying the thermoplastic polymer by spraying onto the yarn sheet.

As shown in FIG. 1, some of the warp carbon fiber multifilament yarns 1a have a density Y of intersection points on one surface 11 of D/N pieces/m or less. In this embodiment, the warp carbon fiber multifilament yarn 1a is in contact with the weft auxiliary fiber yarn 2 only on one side (surface 10). The warp carbon fiber multifilament yarn 1a is not squeezed from the weft auxiliary fiber yarn 2 except for the portions having intersections with the weft auxiliary fiber yarn on both sides of a narrow range in the longitudinal direction of the weft auxiliary fiber yarn. It is possible to take a cross-sectional shape in which the surface not in contact with 2 is widened. In addition, the warp carbon fiber multifilament yarn 1a is not held in shape by being restrained by the weft auxiliary fiber yarn 2 from both sides, but since it is adhered to the weft auxiliary fiber yarn 2 at the surface 10, it is integrated into one piece. It is held as a base material.

As shown in FIG. 2, the warp carbon fiber multifilament yarn 1b, which does not have a surface where the density Y of the intersection point is D/N pieces/m or less, is squeezed from the weft auxiliary fiber yarn 2 and has a substantially elliptical cross section. Because of its shape, when it comes into contact with a smooth surface such as a mold, a gap is created with respect to the smooth surface. In this embodiment, the warp carbon fiber multifilament yarn 1b is in contact with the weft auxiliary fiber yarn 2 on both sides.
On the other hand, when the surface where the density Y of the intersection points is D/N pieces/m or less comes into contact with a smooth surface such as a mold, the carbon fiber filaments forming the warp carbon fiber multifilament yarn move along the smooth surface. .
When the warp carbon fiber multifilament yarn 1a, which contacts the weft auxiliary fiber yarn on only one side, is arranged adjacent to the warp carbon fiber multifilament yarn 1b, which contacts the weft auxiliary fiber yarn 2 on both sides, the latter is smooth. The carbon fiber filaments constituting the former fit into the gaps between the surfaces and take on an approximately trapezoidal shape.
If the warp carbon fiber multifilament yarns 1b that do not have a surface where the density number Y of intersection points is D/N pieces/m or less are not arranged next to each other, there is a gap between the warp carbon fiber multifilament yarns. Since there is no sink mark caused by an excessive amount of resin when the resin composition is integrated with the resin composition, a molded product with excellent surface smoothness can be obtained.

Some of the warp carbon fiber multifilament yarns have a surface where the density Y at the intersection point is D/N pieces/m or less, and does not have a surface where the density Y at the intersection point is D/N pieces/m or less. As an example of a woven structure in which carbon fiber multifilament yarns are not arranged next to each other, for example, when counting a certain weft as the first weft, then the second and third wefts inserted, the odd-numbered weft becomes the warp. In some cases, the even-numbered weft threads repeat "float, float, float, sink" against the warp threads. The first and third weft yarns in the four warp cycles are always in contact with each other on the floating side, and the second and fourth warp yarns, which are in contact with the weft yarns on both sides, are not adjacent to each other, so the above structure is satisfied.
A similar structure is that in a weave structure applied to ordinary textiles such as Mihara-ori, the pre-existing warp is made into a warp carbon fiber multifilament yarn that does not have a surface where the density Y of the intersection point is less than D/N, It is also possible to obtain a woven structure in which warp carbon fiber multifilament yarns each having a plane in which the density Y of one or more intersection points is D/N yarns/m or less are inserted in the intervals. The texture is not limited to these.

(Method for manufacturing fiber fabric)
A method for manufacturing a unidirectional reinforcing fiber fabric will be explained using FIG. 3. The fiber fabric of the present invention can be manufactured using a conventional textile manufacturing apparatus 100. A plurality of carbon fiber multifilament yarns 1 are supplied as warp yarns by wefting from a warp yarn supply creel 104 and arranged in parallel to form a warp carbon fiber multifilament yarn sheet 3. Each carbon fiber multifilament thread is passed through a mail provided in the heald 114 of the weaving section 129 according to the desired weaving structure, and the sheet is opened by moving the heddle 114 up and down in a predetermined pattern, and the weft thread is inserted. The weft auxiliary fiber yarn 2 is inserted by means 128. The weft thread insertion means 128 includes various means such as a rapier, a shuttle, an air jet, and a water jet, but is not limited to these.

If the insertion density of the weft auxiliary fiber threads is too low, the shape retention as a base material will be poor, but if it is too high, the surface smoothness will decrease due to the weft on the outermost surface. For this reason, it is preferable that the weft auxiliary fiber threads are inserted at a pitch of 2 to 50 mm.

The sheet-like material, which has become a unidirectional reinforcing fiber fabric by inserting weft auxiliary fiber yarns, is heated and the thermoplastic polymer continuously attached to the weft auxiliary fiber yarns melts. The warp carbon fiber multifilament yarn and the weft auxiliary fiber yarn are bonded together at their intersections.
The heating means includes contact means such as a heating roll and non-contact means such as an infrared heater, but is not limited to these.

(molding)
A carbon fiber reinforced composite material can be obtained by impregnating the fiber fabric of the present invention with a resin. There is no particular restriction on the resin to be impregnated, but it may be a thermosetting resin composition or a thermoplastic resin composition, and there is no particular restriction on the thermosetting resin, such as those conventionally used in RTM molding or VaRTM molding. Examples include epoxy resin, phenol resin, vinyl ester resin, unsaturated polyester resin, cyanate ester resin, bismaleimide resin, benzoxazine resin, and the like. The thermoplastic resin is not particularly limited, and includes polyolefins such as polyethylene and polypropylene, polyesters such as polyethylene terephthalate and polybutylene terephthalate, polystyrene, ABS resin, acrylic resin, vinyl chloride, polyamides such as polyamide 6, polycarbonate, and polyphenylene. Ethers, polyethersulfones, polysulfones, polyetherimides, polyketones, polyetherketones, polyetheretherketones, etc. can be used. Further, modified versions of each of these resins may be used, or a blend of multiple types of resins may be used. Furthermore, the thermoplastic resin may contain various additives, fillers, colorants, and the like.

The method for producing a carbon fiber reinforced composite material using the fiber fabric of the present invention includes arranging the unidirectional reinforcing fiber fabric in a mold, covering the unidirectional reinforcing fiber fabric with a bagging film, and then placing the unidirectional reinforcing fiber fabric in a mold. A VaRTM method can be used in which a cavity is formed by sealing between the bagging film and the bagging film, the pressure inside the cavity is reduced, and the liquid resin composition is sucked and injected. There are no particular limitations on the bagging film and sealing material used in the VaRTM method, and heat-resistant materials can be selected depending on the type of matrix resin used. Furthermore, a flow media that promotes resin diffusion can be used as necessary. Resin injection methods include a multi-point injection method in which the resin is diffused and impregnated concentrically from any point on the molded product, and a side injection method in which the resin is diffused and impregnated in parallel from any side of the molded product in one direction. You can use any method that suits your needs.

Another method for producing a carbon fiber reinforced composite material using the fiber fabric of the present invention includes placing the unidirectional reinforcing fiber fabric in a split mold, closing the split mold to form a cavity, and An RTM method in which a liquid resin composition is injected into a cavity, a high cycle RTM method, or a high pressure RTM method can be used.

Examples will be described below.
(Example 1)
A 50K (number of filaments: 50,000) multifilament yarn made of carbon fiber multifilament yarn (manufactured by Mitsubishi Chemical Corporation, Pyrofil (product name)) is used for the warp, and a 22.5tex glass fiber (Unitika glass fiber) is used for the warp. Using an auxiliary fiber with heat-fused fibers (manufactured by Toray Industries, Inc.) attached to the yarn as the weft auxiliary fiber yarn, the weft alternately "floats, sinks, floats, floats" for the four warp threads. Weaving is performed using a weaving structure that repeats "floating, floating, floating, sinking," and the warp carbon fiber multifilament yarn and weft auxiliary fiber yarn are bonded at their intersections by contacting them with a heated roll at 90°C. A unidirectional reinforced fiber fabric was produced.

Four rectangular cut sheets with a length of 400 mm and a width of 160 mm were cut out from the above-mentioned unidirectional reinforcing fiber fabric so that the longitudinal direction coincided with the orientation direction of the carbon fiber multifilament yarn. Arrange the first sheet so that the side where some of the warp carbon fiber multifilament yarns are not in contact with the weft auxiliary fiber yarns is facing down, and then stack the second sheet on top of it in the same direction, so that the top and bottom directions are A third sheet was laminated on top of it in the opposite direction, and a fourth sheet was laminated on top of it in the same direction as the third sheet, to obtain a laminate consisting of a total of four sheets. The obtained laminate was placed on a mold coated with a release agent, and the upper surface was covered with a bagging film (manufactured by AIRTECH, product name: Rytron WL8400) with sealant tape (manufactured by RICHMOND, product name: RS200). ) was sealed. A polyurethane tube with an inner diameter of 4 mm was placed at the center of each of the two opposing sides perpendicular to the fiber orientation as a resin injection port and a vacuum pump connection port.

A vacuum was drawn from the vacuum pump connection port, and a resin composition (100:27 mixture of epoxy resin VaRTM molding was carried out under environmental conditions. Thereafter, impregnation curing was performed under curing conditions of 24° C. for 24 hours and post-cure at 80° C. for 2 hours.
As a result, a carbon fiber-reinforced composite material was obtained on both surfaces in which a portion of the warp carbon fiber multifilament yarns did not come into contact with the weft auxiliary fiber yarns.

In order to measure the surface roughness of the obtained carbon fiber reinforced composite material panel, the amount of resin between the tows of the carbon fiber multifilament yarn sheet was measured using a surface roughness measuring device Surfcom (manufactured by Tokyo Seimitsu Co., Ltd.). The sink depth was measured in the excess area. With the direction perpendicular to the fiber orientation as the evaluation axis, the maximum valley depth Rv was measured within a measurement distance of 30 mm, and was defined as the sink depth in the excessive resin content region between the tows of the carbon fiber multifilament yarn sheet. The average value of the sink depths at five points arbitrarily selected under the condition that the measuring element did not come into contact with the weft auxiliary fiber yarn was 0.93 μm.

(Comparative example 1)
A unidirectional reinforcing fiber fabric was obtained in the same manner as in Example 1, except that the weaving structure was plain weave. Using the obtained unidirectional reinforced fiber fabric, a carbon fiber reinforced composite material panel was obtained in the same manner as in Example 1. The average value of the sink mark depth of the obtained carbon fiber reinforced composite material panel was 1.44 μm.

From the above, the warp carbon fiber multifilament yarns and the weft auxiliary fiber yarns obtained in the present invention are bonded to each other at their intersection points, and the number of carbon fiber multifilament yarns in the unidirectional reinforcing fiber fabric is N. Unidirectional reinforcement in which at least one of the carbon fiber multifilament yarns has a surface where the density Y of the intersection point is D/N yarns/m or less, when the insertion density of the auxiliary fiber yarns is D yarns/m. By using a fiber fabric, a molded product with excellent surface smoothness can be obtained. Suitable for a wide range of uses such as civil engineering and construction reinforcement and general industrial use, the present invention is extremely useful industrially.

1... Carbon fiber multifilament yarn 2... Auxiliary fiber yarn 3... Warp carbon fiber multifilament yarn sheet 4... Fiber fabric 10... Fiber fabric (top view)
11...Fiber fabric (bottom view)
DESCRIPTION OF SYMBOLS 100...Textile manufacturing apparatus 104...Warp supply creel 114...Heald 116...Reed 118...Heating roll 126...Take-up roll 128...Weft thread insertion means 129...Weaving section

Claims (9)

A fiber fabric comprising a sheet in which a plurality of carbon fiber multifilament yarns are arranged in parallel, and a plurality of auxiliary fiber yarns,
The fiber fabric is woven with the carbon fiber multifilament yarn as the warp yarn and the auxiliary fiber yarn as the weft yarn,
When the number of the carbon fiber multifilament yarns in the fiber fabric is N, and the insertion density of the auxiliary fiber yarns is D yarns/m, at least one of the carbon fiber multifilament yarns is the auxiliary fiber yarn. A fibrous fabric having a surface in which the density Y of intersection points with the stripes is D/(10×N) pieces/m or less. The fibrous fabric according to claim 1 , wherein both sides include carbon fiber multifilament yarns having surfaces in which the density Y of the intersection points exceeds D/N pieces/m. The fibrous fabric according to claim 1 or 2, wherein carbon fiber multifilament yarns that do not have a surface where the density Y of the intersection points is D/N pieces/m or less are not arranged next to each other. The fibrous fabric according to any one of claims 1 to 3, wherein the auxiliary fiber yarn has a smaller yarn fineness than the warp carbon fiber multifilament yarn. The fibrous fabric according to any one of claims 1 to 4, wherein the carbon fiber multifilament yarn and the auxiliary fiber yarn are bonded to each other by a thermoplastic polymer at the intersection. The fibrous fabric according to any one of claims 1 to 5, wherein the auxiliary fiber yarn is glass fiber to which a thermoplastic polymer is attached. The fiber fabric according to any one of claims 1 to 6, wherein the warp carbon fiber multifilament yarn has a number of filaments of 24,000 to 100,000. A carbon fiber reinforced composite material comprising a thermosetting resin composition and the fibrous fabric according to any one of claims 1 to 7. A carbon fiber reinforced composite material comprising a thermoplastic resin composition and the fibrous fabric according to any one of claims 1 to 7.