JP2011246827A - Unidirectional fiber-reinforced woven or knitted fabric for fiber-reinforced plastic and fiber base material of the same, method of manufacturing the fiber base material, and method of molding fiber-reinforced plastic using the fiber base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fiber-reinforced woven or knitted material excellent in resin impregnation and mechanical characteristics which can be manufactured at low cost, a fiber base material using the fiber-reinforced woven or knitted material, and method of manufacturing a fiber-reinforced plastic using the base material.SOLUTION: The fiber base material is made of a unidirectional fiber-reinforced woven or knitted fabric 13 which locally has clearances and in which a reinforced fiber yarn having an uneven twist part in at leaset one layer of the fiber base material is arranged as warp 11. The filament number is 50000 to 100000, and/or the yarn fineness is 32670 to 65340 dtex, and basis weight is 600 to 1000 g/m. In a method of molding, at least one or more layers of the fiber-reinforced woven or knitted material are laminated in a mold 9, and after placing a medium 17 for diffusing a resin in the surface direction, the fiber base material and the medium are entirely covered with a bag film 18. Then a vacuum is produced in the part covered with the bag film, and a heat curable resin is diffused onto one surface of the laminated fiber base material and cured after impregnation to the fiber base material.

Description

  TECHNICAL FIELD The present invention relates to a unidirectional reinforced fiber knitted fabric for fiber reinforced plastic and its fiber base material, a method for producing the fiber base material, and a method for molding fiber reinforced plastic using the fiber base material. Unidirectional reinforced fiber knitted fabrics for fiber reinforced plastics using thick reinforcing fiber yarns having irregularly arranged twisted parts, fiber reinforced plastic fiber base materials including these reinforced fiber woven knitted fabrics, and production thereof The present invention relates to a method and a method for molding a fiber reinforced plastic using the fiber substrate.

Carbon fiber reinforced plastic (CFRP), which represents a conventional fiber reinforced plastic, is disclosed in, for example, Japanese Patent Application Laid-Open No. 10-317247 (Patent Document 1) and Japanese Patent No. 3019004 (Patent Document 2). Specifically, a thin bi-directional woven fabric in which carbon fiber woven fabrics having a basis weight of 200 to 400 g / m ² in which fine carbon fiber yarns of 3000 to 12000 filaments are arranged in a warp and weft are impregnated with a resin in advance. It is manufactured by laminating a large number of the obtained prepregs and performing autoclave molding. These molded products are superior in performance, but the number of warp yarns is high and the manufacturing cost is high, and their use is limited to specific fields such as aircraft-related structural materials and sports equipment, and they are deployed in various industrial fields. Made it difficult.

  The main reason for this is that, as mentioned above, thin carbon fiber yarns are used, resulting in high manufacturing costs, and the mainstream of the fabric is a relatively thin fabric, so that a predetermined amount of carbon fiber is laminated in the CFRP manufacturing process. Therefore, the number of stacked layers increases, and the labor for stacking increases. Moreover, since the manufacturing process of a prepreg also increases, the processing cost of a prepreg is also added. Furthermore, autoclave molding is required, and large capital investment and labor costs are required.

In view of these circumstances, in order to reduce the cost, it is conceivable to form a carbon fiber woven fabric having a carbon fiber basis weight of 600 to 1000 g / m ² using a relatively thick carbon fiber yarn as a base material. . As the molding method, the carbon fiber woven fabric is laminated in a molding die, and RTM molding in which a thermosetting resin is injected while pressing, or the carbon fiber woven fabric is laminated on the die and covered with a bag film. There is a vacuum bag molding method in which a vacuum state is formed and a thermosetting resin is injected. If these molding methods are adopted, the cost is considerably reduced.

However, even when using relatively thick carbon fiber yarns and reducing the number of warp yarns to develop a woven fabric having a carbon fiber basis weight of 600 to 1000 g / m ² similar to the conventional ones to various industrial uses, The physical properties of CFRP are regarded as important as in the above specific field. By the way, if a relatively thick carbon fiber yarn is arranged in a warp and a weft to obtain a two-way woven fabric, a woven fabric having a large carbon fiber basis weight can be obtained. Bending (crimping) occurs, and the strength and elastic modulus decrease due to the stress concentration at the intersection.

On the other hand, a unidirectional carbon fiber fabric in which carbon fiber yarns are arranged in the warp direction and auxiliary yarns that are thinner than the warp direction yarn are used, as shown in FIG. Since non-twisted multifilaments are used and auxiliary yarns thinner than the warp yarn 11 'are generally used for the weft yarn 12', there is little reduction in strength due to crimping, but the carbon fiber yarn is unidirectional. Therefore, the higher the basis weight, the greater the fiber density, and the fiber gap between adjacent fiber yarns disappears. Thereby, in the molding method such as RTM molding and vacuum bag molding, the flow of the resin is deteriorated, it takes time when impregnating the resin, and the impregnation property of the resin into the carbon fiber fabric 13 ′ is deteriorated.

Japanese Patent Laid-Open No. 10-317247 Japanese Patent No. 3019004

  The object of the present invention is to pay attention to the above-mentioned problems, and is excellent in resin impregnation even in a high-weight woven or knitted fabric using a thick reinforcing fiber yarn as a fiber base material of fiber reinforced plastic. , Unidirectional reinforced fiber knitted fabrics for fiber reinforced plastics that have excellent mechanical properties when molded and can be manufactured at low cost, and fiber base materials including those woven or knitted fabrics. It is to provide a method for producing a reinforced fiber plastic.

A first basic configuration of the present invention is a unidirectional reinforcing fiber woven or knitted fabric for fiber-reinforced plastic, comprising at least a part of a reinforcing fiber yarn having a non-uniform twisted portion. The basic configuration is a fiber base material, which is a constituent material of fiber reinforced plastic, formed by laminating a plurality of reinforced fiber knitted fabrics, and at least one of the reinforced fiber woven fabrics is reinforced with a non-uniform twisted portion. It consists of a unidirectional reinforced fiber woven or knitted fabric including a fiber yarn, and the reinforcing fiber yarn has a number of filaments of 50,000 to 100,000, or the fineness of the reinforced fiber yarn is 32670. It is 65340 dtex, and the basis weight of the unidirectional reinforcing fiber woven or knitted fabric is 600 to 1000 g / m ² .

  According to a preferred embodiment, the carbon fiber yarn having a non-uniform twist portion has a twist portion of 1 turn / m or more along the longitudinal direction, and the unidirectional reinforcing fiber woven fabric is A unidirectional reinforcing fiber woven or knitted fabric in which the reinforcing fiber yarn is used for the warp or the weft and the auxiliary yarn is used for the weft or the warp, and the intersection of the warp and the weft is bonded through a low melting point polymer. It is preferable that

  A third basic configuration is a method for producing the fiber base material, wherein a substantially untwisted reinforcing fiber yarn wound around a plurality of bobbins is hung on a warp yarn creel and vertically pulled in a bobbin axial direction and woven. It is in.

  Further, a fourth basic configuration is composed of a unidirectional reinforcing fiber woven or knitted fabric, and the number of filaments of each reinforcing fiber yarn is 50,000 to 100,000, or the reinforcing fiber yarn has a fineness of 32670 to 65340 dtex. A fiber base material comprising at least one layer of fiber woven or knitted fabric is placed in a mold, and after placing a medium for diffusing the resin in the surface direction on the upper surface, the whole of the fiber base material and the medium is a bag film. Covering and then vacuuming the interior covered with the bag film, diffusing a thermosetting resin on one side of the fiber base material through the medium, impregnating the fiber base material, and curing the fiber base The plastic molding method.

  Preferably, the unidirectional reinforcing fiber woven or knitted fabric uses reinforcing fiber yarns in which the number of filaments of the warp yarn or weft yarn is 50000 to 100,000, or the fineness of the reinforcing fiber yarn is 32670 to 65340 dtex, and the weft yarn or It is preferable to use an auxiliary yarn for the warp and to give a non-uniform twisted portion to the reinforcing fiber yarn.

It is a schematic block diagram of the unidirectional carbon fiber fabric representing this invention. It is a schematic block diagram of the conventional unidirectional carbon fiber fabric. It is a side view which shows roughly the carbon fiber yarn used for this invention. It is process explanatory drawing which shows the manufacturing process of the unidirectional carbon fiber fabric of this invention. It is sectional drawing which shows the outline | summary of the shaping | molding method of this invention.

Hereinafter, representative embodiments of the present invention will be described in detail with reference to the drawings.
In the following description, a unidirectional carbon fiber woven fabric is described as the base material. However, the present invention is not limited to the unidirectional carbon fiber woven fabric, but also includes a unidirectional warp knitted fabric. The unidirectional carbon fiber fabric in the present invention refers to a fabric using a thick carbon fiber yarn for the warp or weft and using an auxiliary yarn including a thin carbon fiber yarn for the weft or warp. As the auxiliary yarn, a multifilament that is thinner than the carbon fiber yarn made of high-strength, high-elasticity fiber such as glass fiber, aramid fiber, graphite fiber, or silica fiber is used. Further, in the following description, carbon fibers will be described as an example of the reinforcing fibers, but other materials used for the auxiliary yarn can be used as the reinforcing fibers, for example.

  Generally, when weaving a woven fabric using carbon fiber yarns, when supplying carbon fiber yarns directly, or by partially warping a plurality of carbon fiber yarns, the necessary number of yarns are used as a yarn supply beam. Two supply methods are used in the case of rewinding and supplying, and most of them use a method of supplying carbon fiber yarn directly from a bobbin. The main reasons for this are that the partial warping process is not necessary and the length of the fabric can be increased. Further, as a method of directly supplying carbon fiber yarns from a bobbin, a horizontal cutting method is generally used in which the yarn is pulled out in a direction perpendicular to the bobbin axial direction from the bobbin around which the carbon fiber yarn is wound. This is because in the method of unwinding by vertical take-up, every time one winding is pulled out from the bobbin, the warp yarn is twisted once, so the twisted portion is twisted and partially converges. There is a problem that a woven fabric having a uniform yarn width cannot be obtained.

  This phenomenon appears more conspicuously as the carbon fiber yarn used is thicker. Therefore, in order to solve the above-mentioned problem, pre-feeding is often used. However, when a unidirectional woven fabric or knitted fabric having a high basis weight is obtained using a thick yarn having a filament number of 50000 or more as in the present invention, it is almost untwisted when an attempt is made to supply the warp yarn drawing method by a normal side cut. It is supplied in a state, and when passing through the supply process, the yarn is opened by rubbing with guides and the like. For this reason, when trying to obtain a fabric with a high basis weight, there is almost no gap between adjacent yarns of the warp yarn, and there is a problem that it takes a long time to impregnate when trying to impregnate the resin by RTM molding or the like.

  Therefore, as a result of intensive investigations, the present inventors have adopted vertical take-up instead of conventional horizontal take-off as a method for drawing out warp yarn, draw out the yarn while intentionally unwinding and twisting, and twist it in the longitudinal direction of the yarn. It was discovered that even when a woven fabric is formed by forming a portion, a woven fabric having gaps locally between yarns can be obtained. If the fabric is molded by RTM molding or the like, the resin can easily flow through the gap, and the impregnation time is greatly shortened.

In addition, the fabric weight of about 200 to 400 g / cm ² is the mainstream in the thin carbon fiber yarn having a high cost of about 3000 or 12,000 filaments. There is a gap. If the warp yarn is already supplied in the longitudinal direction in a woven fabric that already has a gap, the yarn will be converged by unwinding and twisting, so that the gap between the yarns will become larger and the appearance quality of the woven fabric will deteriorate. Absent. On the other hand, when a fabric having a high basis weight is produced using a thick fiber yarn having 50,000 filaments or more and a yarn fineness of 32670 to 65340 dtex, the longitudinal feeding method of the present invention is very effective and economical. Turned out to be a good tool.

  In general, it is well known that in the longitudinal take-up, one unwinding and twisting is performed every time one yarn is pulled out from the bobbin. In this unwinding twist, the thicker the fiber yarn, the more noticeably the twisted portion appears along the longitudinal direction. However, the twisted portion is formed almost uniformly in the longitudinal direction of the fiber yarn by passing through a combustion process that actively imparts a twist of several tens of turns / m or more. Then, it is rare that a twist is formed uniformly in the longitudinal direction of the fiber yarn. When the weaving speed and knitting speed are relatively slow as in the production of woven fabrics and knitted fabrics, and are easily affected by rubbing or tension by guides, the formation state of the twisted portion is as shown in FIGS. Rather, not only the part with the twisted part 14 and the part with no twist (non-twisted part) 15 are likely to occur randomly in the longitudinal direction of the yarn, but also the length of the twisted part 14 and the untwisted part 15 and the twisted part. The convergence state of 14 is also non-uniform. Since the woven fabric is formed in such a fiber yarn form, the fiber yarn width of the twisted portion 14 is narrower than that of the non-twisted portion 15, and, as shown in FIG. 1, between the adjacent yarns in the woven fabric. A gap is formed.

  Note that the direction in which the warp yarn 11 is pulled out may be either clockwise or counterclockwise, but if it is pulled out clockwise, Z twist is applied, and if it is pulled counterclockwise, S twist is applied. Therefore, in order to avoid trouble when pulling out, it is preferable to pull it out in either one. Conventionally, it is widely known that the presence or absence of such a twisted part affects the resin impregnation property at the time of forming a woven fabric. In particular, in the hot melt method in which a resin film coated with a resin is applied to a woven fabric and impregnated with the resin, the impregnation property is greatly affected by the presence or absence of the twisted portion, but the viscosity is relatively high as in the wet method or RTM molding. In a molding method using a low-resin resin, the impregnation property of the resin depends on the presence or absence of gaps between yarns in the woven fabric rather than the presence or absence of twisted portions.

  Next, a method for producing a unidirectional reinforcing fiber fabric will be briefly described with reference to FIG. The bobbin 1 wound with the carbon fiber yarn is hung on the creel 2 so that the necessary number of warp yarns 11 of the fabric 13 can be pulled out in the same direction. The creel 2 is fixed so that the bobbin 1 does not rotate so that the fiber yarn can be pulled out vertically. The fiber yarns drawn out in the bobbin axial direction are supplied to a nip roll device 5 that feeds the warp yarn 11 after being arranged in a sheet shape through guides 3 and combs 4. When the warp yarn 11 is pulled out from the bobbin 1, the warp yarn is twisted once each time one bobbin 1 is pulled out.

  Subsequently, the warp yarn 11 is sequentially drawn into the heald 6 that opens up and down and the heel 7 that regulates the basis weight. Next, an auxiliary yarn that becomes the weft yarn 12 is inserted into the opening 8 of the warp yarn 11, and the warp yarn 11 and the auxiliary yarn that is the weft yarn 12 are interlaced to form the woven fabric 13, and then the heating device 10. And is bonded via a low-melting polymer at the intersection of the auxiliary yarn as the weft yarn 12 and the warp yarn 11 and wound around a take-up roll. In addition, the auxiliary yarn which is the weft yarn 12 is not particularly limited as described above, such as a glass fiber and an aramid fiber, which are thinner than the warp yarn.

  At this time, a heat-bonding fiber (not shown) made of a low-melting polymer is aligned with the auxiliary yarn, or a composite yarn is formed by resin bonding, combusting, covering, or the like. There are no particular restrictions on how the composite yarns are combined. Further, the heating method by the heating device 10 is not limited to a pressure bonding with a heat roll or a non-contact far infrared heater. In the woven fabric 13 woven as described above, the carbon fiber yarn used for the warp yarn 11 is formed with a non-uniform pitch between the twisted portion 14 and the non-twisted portion 15 along the longitudinal direction. At this time, the twisted portion 14 is converged more than the non-twisted portion 15 as shown in FIG. 3, and the yarn width is narrow, so that a woven fabric having a gap between adjacent yarns as shown in FIG. 1 is obtained. . Here, examples of the low-melting-point polymer constituting the heat-sealing fiber include thermoplastic resins such as polyamide (nylon), polyethylene, and polyurethane, but are not limited thereto.

  Next, a method for molding CFRP (carbon fiber reinforced plastic) of the present invention will be described. FIG. 5 is a cross-sectional view for explaining the CFRP molding method of the present invention. In the figure, a mold release agent is applied to the mold 9, and a predetermined number of carbon fiber fabrics 13 according to this embodiment serving as a fiber base material are laminated on the mold 9 in a predetermined direction. A sheet 17 that is peeled off after the resin is cured, that is, a so-called peel ply 16, is laminated, and a medium 17 for diffusing the resin is placed on the entire surface of the carbon fiber fabric 13 that is a fiber base material. Moreover, the spiral tube 21 which deposits resin on a fiber base material is arrange | positioned at the both ends of the carbon fiber axial direction of the carbon fiber fabric 13, and the suction port 23 of a vacuum pump is attached to the end of the spiral tube 21, and those whole are bag films 18, and the periphery of the bag film 18 is bonded to the mold 9 with a sealing material 20 so that air does not leak. The resin inlet 25 injected from the resin tank is connected to the other end of the spiral tube 21.

  In the resin tank, a low-viscosity resin suitable for RTM molding (for example, a thermosetting resin in a syrup-like thermosetting type with a predetermined amount of a curing agent added) is placed. After operating the vacuum pump to bring the carbon fiber fabric 13 constituting the fiber base material covered with the bag film 18 into a vacuum state with a vacuum pressure of about 70 to 76 cmHg, the valve 26 is opened to inject the resin. . Since the inside covered with the bag film 18 is in a vacuum state, and the flow resistance of the resin in the surface direction of the medium 17 is smaller than the fiber axis direction of the carbon fiber fabric 13, the resin is first diffused over the entire surface of the medium, and then Impregnation proceeds in the thickness direction of the carbon fiber fabric 13 as a fiber base material. However, the degree of impregnation is considerably influenced by the form of the carbon fiber fabric 13 used as the fiber base material. Of course, the impregnation of the resin in the thickness direction is completed faster as the woven fabric has gaps between the yarns.

  Here, as the medium 17, a mesh-like sheet using a monofilament such as polyethylene or polypropylene having a fiber diameter of about 0.2 to 0.5 mm, a sheet formed by Russell knitting, or the like is used. Absent. The vacuum pump is preferably operated until at least the impregnation of the resin is completed, and the bag film 18 is preferably kept in a vacuum state. After the resin impregnation is completed, the peel ply 16 is peeled off, the medium 17 and the bag film 18 are removed, and the mold is removed from the mold 9 to obtain a CFRP molded product.

  Note that the peel ply 16 used in the present invention needs to allow the resin to pass therethrough, and a nylon fiber fabric, a polyester fiber fabric, a glass fiber fabric, or the like can be used. The smaller the weaving density of the woven fabric, the larger the gap, so that the resin can pass easily. On the other hand, when the resin is cured and finally peeled, irregularities are generated on the surface of the fiber substrate. Therefore, it is preferable to select a resin that can pass through the resin as much as possible and is less likely to have unevenness on the surface. The bag film 18 needs to be airtight, and a nylon film, a polyester film, or the like can be used.

Next, examples relating to the fiber-reinforced plastic of the present invention will be described below.
(Example 1, "invention fabric")
A multifilament carbon fiber yarn with 50000 filaments and a yarn fineness of 32670 dtex is used as the warp, and a bobbin is hung on the creel so that the unwinding direction can be taken counterclockwise and pulled out, and the glass fiber of 222 dtex is applied to Toray. Auxiliary yarn made by combining heat-bonded fibers (nylon) manufactured by Co., Ltd. is used as a weft yarn, and the warp density is 5.5 yarns / 2.54 cm, the weft yarn density is 5 yarns / 2.54 cm, and is woven so as to form a plain structure. Subsequently, the mixture was heated with a heating device to prepare a unidirectional carbon fiber woven fabric having a carbon fiber woven fabric basis weight of 720 g / m ² . In addition, heating inserts the weft yarn combined with the fusion fiber, melts the fusion fiber of the weft yarn with a heating roll attached on the loom, and the carbon fiber yarn and the glass fiber are passed through the heat fusion fiber. It was carried out by the method of bonding. The obtained woven fabric has twisted portions and non-twisted portions formed at arbitrary positions in the longitudinal direction of the carbon fiber yarns by unwinding and twisting, and the yarns having these forms are arranged so that adjacent yarns are arranged. In addition, a gap as shown in FIG. 1 was formed.

(Comparative Example 1, “Comparative Fabric”)
Similarly to the present invention, a multifilament carbon fiber yarn having 50000 filaments and a yarn fineness of 32670 dtex is used as a warp yarn, and is applied to a creel so that the warp yarn can be pulled out by picking so as not to be untwisted. An auxiliary yarn made by combining glass fiber with a heat-bonding fiber (nylon) manufactured by Toray Industries, Ltd. is used as a weft yarn, and the warp density is 5.5 yarns / 2.54 cm, and the weft yarn density is 5 yarns / 2.54 cm. Then, it was heated with a heating device to produce a unidirectional carbon fiber fabric having a carbon fiber fabric basis weight of 720 g / m ² . In addition, after inserting the weft yarn combined with the heat fusion fiber, the heat fusion fiber of the weft yarn is melted with a 120 ° C. heating roll attached on the loom, and the carbon fiber yarn and the glass fiber are heat fusion. It carried out by the method of adhere | attaching through a fiber. The obtained woven fabric was a woven fabric having almost no gap between the twisted portions of the carbon fiber yarn and the yarn as shown in FIG.

(Example 2 and Comparative Example 2, “Molding Method”)
Three unidirectional carbon fiber fabrics of the present invention having a width and a length of 50 cm each obtained in Example 1 were prepared, and the carbon fiber fabric was fiber-coated on a mold coated with a release agent. Three substrates were laminated in the same direction. A nylon woven fabric made by Airtech is placed on the fiber base material as a peel ply, and a mesh sheet of 0.8 mm thickness and 2.5 mm × 2.2 mm opening size made of polyethylene is used as the medium on the entire surface of the fiber base material. Was placed to cover. A spiral tube is arranged at both ends of the fiber base in the fiber axis direction, a suction port of a vacuum pump is attached to one end of the spiral tube, a resin inlet is attached to the other end, and the whole is a bag film made of nylon film. The bag film, the mold, the resin inlet, and the suction port attachment port were bonded with a sealing agent so as to cover and maintain a vacuum state. Next, the inside of the bag film covered with a vacuum pump is brought to a vacuum state of 76 cmHg, and then the valve is opened to inject a thermosetting epoxy resin having a resin viscosity of 260 mPa · s and heated in an oven at 40 ° C. for 24 hours. After being held, it was further heated at 80 ° C. for 2 hours. After the resin was sufficiently cured, it was cooled to room temperature, and the bag film, mesh sheet and peel ply were peeled off to obtain a molded plate. Further, as Comparative Example 2, the woven fabric of the present invention was changed to a comparative woven fabric, and the molding method was performed by using the comparative woven fabric as a base material in the same procedure as in Example 2.

  The evaluation results of the forming are shown in Table 1. However, in the forming using the woven fabric of the present invention, a twisted portion and a non-twisted portion are mixed in the yarn, so that a gap is formed between the yarns in the longitudinal direction. It took only 14 minutes to completely impregnate the resin flow path. On the other hand, in the molding using the comparative woven fabric in the same manner, there are almost no gaps between the yarns in the longitudinal direction, and the resin diffusion at the surface layer portion was not different from that of the woven fabric of the present invention. The flow of the resin was very slow, and it took about 24 minutes for the comparative fabric to be completely impregnated with the resin.

  As is clear from the above explanation, in the present invention, a unidirectional reinforced fiber woven or knitted fabric using a yarn in which a twisted portion and a non-twisted portion are unevenly mixed is used as a fiber base material for fiber reinforced plastic. Even in a reinforced knitted fabric with a high basis weight using thick reinforcing fiber yarns, gaps are formed between the reinforcing fiber yarns of the woven knitted fabric to form resin flow paths during molding, and the resin impregnation speed is increased. Since it can be improved, it is economically advantageous and becomes a fiber base material for composite materials particularly suitable for RTM molding and vacuum bag molding.

1 Bobbin 2 Creel 3 Guide 4 Comb 5 Nip roll device 6 Held 7 ロ ー ル 8 Opening 9 Mold 10 Heating device 11 Warp yarn 12 Weft yarn (auxiliary yarn)
13 (Unidirectional reinforcing fiber) Woven fabric (base material)
14 Twisted portion 15 Non-twisted portion 16 Peel ply 17 Medium 18 Bag film 20 Seal material 21 Spiral tube 23 Vacuum pump suction port 25 Resin inlet port 26 Valve

Claims (7)

  A unidirectional reinforcing fiber woven or knitted fabric for fiber-reinforced plastic, comprising at least a portion of reinforcing fiber yarn having a non-uniform twisted portion. A fiber base material, which is a constituent material of fiber reinforced plastic, is formed by laminating a plurality of reinforced fiber knitted fabrics, and at least one of the reinforced fiber woven knitted fabrics has a reinforced fiber yarn having a non-uniform twisted portion. Including a unidirectional reinforcing fiber woven or knitted fabric with gaps locally, wherein the number of filaments of the reinforcing fiber yarn is 50,000 to 100,000, or the fineness of the reinforcing fiber yarn is 32670 to 65340 dtex, The fiber base material whose fabric weight of the unidirectional reinforcing fiber woven fabric is 600 to 1000 g / m ² .   The fiber substrate according to claim 2, wherein the reinforcing fiber yarn having a non-uniform twisted portion has a twisted portion of 1 times / m or more along the longitudinal direction.   The reinforcing fiber woven or knitted fabric is formed by using the reinforcing fiber yarn for the warp or the weft, and using the auxiliary yarn for the weft or the warp, and the intersection of the warp and the weft is bonded through a low melting point polymer. The fiber substrate according to claim 2 or 3.   The fiber base according to any one of claims 2 to 4, wherein a substantially untwisted reinforcing fiber yarn wound around a plurality of bobbins is hung on a warp yarn creel, vertically taken in the bobbin axial direction, and woven. A method of manufacturing the material.   At least one or more layers of the above-mentioned reinforced fiber knitted fabric, which is composed of a unidirectional reinforced fiber knitted fabric and each reinforcing fiber yarn has 50000 to 100,000 filaments, or the reinforcing fiber yarn has a fineness of 32670 to 65340 dtex The fiber base material is placed in a mold, and a medium for diffusing the resin in the surface direction is placed on the upper surface, and then the entire fiber base material and the medium are covered with a bag film, and then covered with the bag film. A method of molding fiber reinforced plastic, wherein the inside is evacuated, a thermosetting resin is diffused on one side of the fiber base material through the medium, and the fiber base material is impregnated and cured.   The unidirectional reinforcing fiber woven or knitted fabric uses a reinforcing fiber yarn in which the number of filaments of the warp yarn or weft yarn is 50,000 to 100,000, or the fineness of the reinforcing fiber yarn is 32670 to 65340 dtex, and assists the weft yarn or warp yarn. The method for molding fiber-reinforced plastic according to claim 6, wherein a yarn is used to impart a non-uniform twisted portion to the reinforcing fiber yarn.

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