Patent Description:
Fiber reinforced plastic (FRP) including a reinforcing fiber and a resin is used for aviation, space, automobiles, and the like because FRP has the properties such as the light weight and the high strength. Examples of the method of molding that achieves both the high productivity and the high strength of FRP include a method of resin transfer molding (RTM) and a method of vacuum-assisted resin transfer molding (VaRTM) in which a resin is later impregnated into a reinforcing fiber laminate and cured. The method of RTM is a method of molding FRP by later impregnating and curing a matrix resin, in which a reinforcing fiber laminate including a reinforcing fiber substrate including a dry reinforcing fiber bundle group that is not preimpregnated with a matrix resin is placed in a mold, and a liquid matrix resin having a low viscosity is injected. When a particularly high productivity is required, for example, a technique of shortening the time for molding fiber reinforced plastic is used in which during the injection of a resin, the size of a cavity in a mold is set larger than the thickness of a final molded product, and by closing the mold, a reinforced fiber laminate is impregnated at a high speed. In recent years, a method of wet press molding has also been used in which a liquid resin is applied to a reinforcing fiber laminate, and then a mold is clamped to impregnate the resin into the reinforced fiber laminate.

A reinforcing fiber laminate being impregnated with and cured of a resin is traditionally formed by cutting out a desired shape from a reinforcing fiber substrate such as a textile or a non crimp fabric (NCF) that includes a dry reinforcing fiber bundle group impregnated with no resin and has a fabric form having a certain width (that is, a substantially rectangular shape), and draping and sticking the cut-out product into a three-dimensional shape. However, after the desired shape is cut out from the fabric having a certain width, a large amount of remaining end material is generated. More specifically, the quantity of the reinforcing fibers discarded is large, and thus in the conventional method in which a reinforcing fiber substrate that has a fabric form having a certain width is manufactured in advance, there is a problem that the manufacturing cost is high.

For solving such a problem, a method of fiber placement has been attracting attention. In the method, a reinforced fiber bundle is placed only at a necessary portion so as to obtain a desired shape that matches a product shape. In accordance with the method of fiber placement, a required quantity of reinforcing fibers are placed at a necessary portion, and thus, the quantity of the reinforcing fibers discarded can be significantly reduced by making the reinforcing fibers into a tape-like form and placing the tape material only at required sites. Furthermore, the reinforcing fiber substrate manufactured by the method of fiber placement has less crimps in the reinforced fiber bundle and better straightness than conventional textiles and NCFs, so that the FRP obtained by injecting and curing a resin in the substrate has a high mechanical strength.

As a conventional technique that relates to a carbon fiber tape material for use in the method of fiber placement, for example, Patent Document <NUM> proposes a carbon fiber tape material with a polymer adhesive bonded to both surfaces thereof, and a method for producing the material. Thus method allows a carbon fiber tape with a desired width to be produced with high accuracy by melting the polymer adhesive and then attaching the melted polymer adhesive to a reinforcing fiber bundle group.

In addition, Patent Document <NUM> proposes a carbon fiber tape material with a non-woven veil bonded to at least one surface thereof, a preform, and a method for producing the preform. This method achieves, with the use of the carbon fiber tape material with the non-woven veil bonded thereto, the effect of increasing the resin permeability in the in-plane direction at the time of resin injection in RTM molding or VaRTM molding. In addition, in the case where a thermoplastic fiber material is used for the non-woven veil, the resulting composite material can be toughened.

Furthermore, Patent Document <NUM> proposes a reinforcing sheet material including a reinforcing fiber material with a basis weight of <NUM>/m<NUM> or less and a knitted fabric of a thermoplastic resin material. According to such a configuration, the use of the knitted fabric with flexibility achieves a sheet material that maintains straightness in a thin and wide form without deformations such as curls. In addition, the thin knitted fabric with many voids is used, thus allowing the air inside to be released, and allowing a molded body with few voids (voids) to be obtained.

Patent Document <NUM> teaches a textile semi-finished product, which comprises a textile structure and a fixing structure, where the textile structure has a first large number of reinforcing fiber bundles of high-performance fibers, where displacement areas are formed between adjacent reinforcing fiber bundles that are against each other, where the fixing structure fixes the reinforcing fiber bundles depending on the textile structure with a fixing pattern in such a manner that the reinforcing fiber bundles are fixed at least partially and the displacement areas remain at least partially free. Independent claims are also included for: (<NUM>) an apparatus for producing the textile semi-finished product for producing a fiber composite component, comprising a device for supplying the above mention textile semi-finished product and a device for applying the fixing pattern for fixing the reinforcing fiber bundle; and (<NUM>) a method for producing a textile semi-finished product comprising (a) assembling the textile structure of the first large number of reinforcing fiber bundles of high-performance fibers, where displacement areas are formed between adjacent reinforcing fiber bundles and are mutually displaceable, (b) arranging the fixing structure on the textile structure, and (c) fixing the reinforcing fiber bundle with the fixing structure by applying the fixing pattern relative to the textile structure.

In the method of fiber placement, however, a carbon fiber tape needs to follow the shape of a mold in attaching the carbon fiber tape directly to the mold. Thus, the carbon fiber tape is required to have higher deformability as the width of the carbon fiber tape is increases and as the mold shape is more complicated. In addition, having high productivity is required in laminating the carbon fiber tape and in resin injection in RTM molding and VaRTM molding.

In this regard, the deformability of the polymer adhesive is not mentioned in the invention in Patent Document <NUM>. In the case where, for example, a non-woven veil is used as the polymer adhesive, then the non-woven veil typically has insufficient deformability in the planar direction, because the non-woven veil is formed by randomly orienting short fibers. Furthermore, when the polymer adhesive is melted, the form of the non-woven veil is lost, and the original deformability of the fabric material will be thus deteriorated.

According to the invention in Patent Document <NUM>, the carbon fiber tape material with the non-woven veil bonded to at least one surface thereof is used. Thus, the non-woven veil has insufficient deformability, because the non-woven veil is formed by randomly orienting short fibers as in Reference <NUM>.

According to the invention in Patent Document <NUM>, the fabric with deformability is used. Since reinforcing fiber materials have low basis weight, it is necessary to laminate a large number of sheet materials in order to obtain a desired product thickness, thereby leading to complicated work and decreasing the productivity. In addition, the invention described in Patent Document <NUM> relates to a reinforcing sheet material, and fails to suggest the application of the reinforcing sheet material to the method of fiber placement.

The present invention is intended to solve the problems of the prior art, and specifically, provide a carbon fiber tape material that is favorable in followability to molds and impregnation with matrix resins, and capable of enhancing the productivity in the case of producing a reinforcing fiber laminate by a method of fiber placement and capable of providing a molded body with high mechanical strength when the material is impregnated with a resin and molded. In addition, the invention is intended to provide a reinforcing fiber laminate and molded body that are obtained from the carbon fiber tape material.

The present invention has been made to solve at least a part of the problems described above, and is defined in the appended claims.

The carbon fiber tape material according to the present invention is favorable in followability to molds and impregnation with resins, and capable of enhancing the productivity in the case of producing a reinforcing fiber laminate by a method of fiber placement and capable of providing a molded body with high mechanical strength when the material is impregnated with a resin and molded.

<FIG> shows a schematic view of a carbon fiber tape material not in accordance with the present invention.

The carbon fiber tape material <NUM> shown in <FIG> has a plurality of carbon fiber bundles <NUM> integrated with each other by a fabric <NUM>, and the respective carbon fiber bundles are arranged parallel to (in parallel with) each other in a width direction to form a carbon fiber bundle group <NUM>.

As the carbon fiber bundle for use in the present invention, for example, a carbon fiber bundle subjected to sizing treatment in advance can also be used. The sizing treatment is performed, thereby allowing the convergency of the carbon fiber bundle to be improved, and allowing the generation of fuzz to be suppressed. In addition, the carbon fiber bundle for use in the present invention may have an organic fiber mixed with a carbon fiber.

The number of filaments N (unit: K = <NUM>,<NUM>) in the carbon fiber bundle is, in a preferred aspect, <NUM> (<NUM>,<NUM>) or more and <NUM> (<NUM>,<NUM>) or less. When the number of single fibers in the carbon fiber bundle <NUM> is less than <NUM>, the yarn width of the carbon fiber bundle <NUM> is narrow, and defects such as twisting are likely to occur. When the number of the single fibers in the carbon fiber bundle <NUM> is more than <NUM>, the carbon fiber basis weight of the carbon fiber bundle <NUM> is high, and when the carbon fiber bundles <NUM> are aligned by the method of fiber placement to obtain a substrate, the carbon fiber basis weight per layer is excessively high, and there is thus a possibility that the allowable range of the design of the fiber orientation will be narrowed.

The carbon fiber tape material <NUM> includes a plurality of carbon fiber bundles <NUM> mutually integrated with the fabric <NUM>, thereby allowing the number and weight of carbon fiber filaments per unit length of the carbon fiber tape material to be increased. In addition, in placing and laminating the carbon fiber tape material by the method of fiber placement to produce a fiber-reinforced plastic, the time of placing and laminating the carbon fiber tape material, required to achieve a desired fiber volume content, can be shortened to improve the productivity.

The fabric <NUM> is made of one or more thermoplastic resins. The thermoplastic resin refers to a thermoplastic resin such as a polyamide resin, a polyester resin, a polyethylene terephthalate resin, a polyvinyl formal resin, a polyether sulfone resin, a phenoxy resin, or a polycarbonate resin, furthermore, a thermoplastic elastomer (a polystyrene-based resin, a polyolefin-based resin, a polyurethane-based resin, a polyester-based resin, a polyamide-based resin, a polybutadiene-based resin, a polyisoprene-based resin, a fluorine-based resin, an acrylonitrile-based thermoplastic elastomer, or the like), a copolymer or a modified product thereof, a resin produced by blending two or more of these resins, or the like. These resins can be formed into a fiber to have the form of a woven fabric (textile, knitted fabric) or a non-woven fabric, or can be formed into a film as the fabric <NUM>. This fabric <NUM> is partially melted to be integrated with the carbon fiber bundle group <NUM>.

In the present invention, it is important for the fabric <NUM> to have deformability. More specifically, it is important for the fabric elongation rate with a load of <NUM> mN/<NUM> applied to the fabric in at least one direction of the fabric to be <NUM>% to <NUM>%, and further preferably <NUM>% to <NUM>%. The use of a deformable fabric allows the deformability of the tape to be improved, and allows the carbon fiber tape to follow the shape of a mold in the case of directly attaching the tape to the mold by the method of fiber placement. When the fabric elongation rate is less than <NUM>%, the fabric has insufficient deformability and the carbon fiber tape fails to follow the mold shape. When the fabric elongation rate is more than <NUM>%, the fabric is deformed by a slight external force, thereby making it difficult to accurately attach and integrate the fabric to and with the carbon fiber. The fabric elongation rate herein is determined from the following formula in accordance with JIS L <NUM><NUM>.

<FIG> shows a method for measuring the fabric elongation rate. <FIG> shows the condition of the fabric <NUM> before applying a certain load. The fabric is cut into a specified size, specified marks <NUM> are put on the fabric, an inter-mark distance L<NUM> is measured, and then the fabric is chucked by a clamp <NUM> as shown in <FIG>. Thereafter, a load is applied. <FIG> shows the condition of the fabric <NUM> after applying the certain load. As shown in <FIG>, the inter-mark distance L<NUM> after the application of the certain load is measured, thereby allowing the elongation rate to be calculated from the designated formula. It is to be noted that in the case of measuring the elongation rate of the fabric from the tape material that has the carbon fiber bundle and fabric integrated, the fabric is peeled off from the tape material, and the elongation rate is then measured in accordance with the above-mentioned procedure.

It is important for the carbon fiber tape material according to the present invention to have a basis weight excluding fabric between <NUM>/m<NUM> and <NUM>/m<NUM>. When the basis weight of the carbon fiber tape material excluding the fabric is less than <NUM>/m<NUM>, the number of sheets of the carbon fiber tape material laminated for obtaining a laminate with a desired basis weight is increased in placing the carbon fiber tape material by the method of fiber placement, thereby increasing the time required for the lamination, which results in a limitation in further improvement in productivity. In contrast, when the basis weight of the carbon fiber tape material excluding the fabric is more than <NUM>/m<NUM>, the number of sheets of the carbon fiber tape material laminated for obtaining a laminate with a desired basis weight is excessively small, and there is a possibility that the degree of freedom in designing the fiber orientation may be reduced. The basis weight is preferably <NUM>/m<NUM> to <NUM>/m<NUM>.

In addition, the fabric <NUM> desirably has regularity. In the present invention, the wording of "having regularity" means that a certain structural form is continuously repeated in the longitudinal direction of the fabric (i.e., the longitudinal direction of the carbon fiber tape material). Examples of the fabric with regularity include knitted fabrics and textiles. The knitted fabrics and the textiles have structural forms continuously repeated in the longitudinal direction, and the positions where the fibers are located is determined by the structure, and thus, the knitted fabrics and the textiles can be considered as materials that are less likely to vary or deviate in fiber basis weight as a fabric. In contrast, examples of fabrics without regularity include non-woven fabrics (non-woven veil). Examples of the features of the non-woven fabric include: having a configuration obtained by randomly dispersing short fibers and then bonding the fibers to each other, and thus having difficulty in showing the above-mentioned fabric elongation rate; and having no structural form continuously repeated in the longitudinal direction, and thus easily varying or deviating in fiber orientation and basis weight.

As the structure form of the fabric with regularity, a woven structure such as plain weave, twill weave, and satin weave, a warp knit structure or a weft knit structure such as denbigh, code, atlas, chain, inlay, satin, half, and tulle, or a combination thereof can be used.

These fabrics with regularity have forms kept by interknitting or interweaving fibers with each other. More specifically, as compared with a non-woven fabric that has fibers bonded to each other and fixed in relative position, the positions of the interknitted or interwoven fibers are not completely fixed with a high degree of freedom, thus resulting in excellent deformability in the case of a force applied in the plane (planar direction) of the fabric.

The basis weight of the fabric <NUM> is preferably more than <NUM>/m<NUM> and <NUM>/m<NUM> or less, further preferably more than <NUM>/m<NUM> and <NUM>/m<NUM> or less. When the basis weight of the fabric <NUM> is <NUM>/m<NUM> or less, the material of the fabric is easily broken, thereby making desired deformability less likely to be obtained. In addition, the thickness of the fabric is reduced, thereby making it difficult to sufficiently secure the matrix resin flow path in impregnation. Furthermore, because of the thin fabric, the thickness of the interlayer reinforcing material in the molded body is reduced, thereby making it difficult to reinforce the interlayers between laminated fiber bundles. In contrast, when the basis weight of the fabric <NUM> is more than <NUM>/m<NUM>, because of the increased thickness of the fabric, the carbon fiber tape material undergoes an increase in thickness, thereby making the thickness of the reinforcing fiber laminate with the carbon fiber tape material used likely be larger than a desired product thickness, that is, making it difficult to make the reinforcing fiber laminate with the carbon fiber tape material used into the near net shape of a desired molded body. In addition, the interlayer reinforcement material of a molded body molded with the use of the reinforcing fiber laminate is likely to undergo an increase in thickness, thereby making it difficult to increase the fiber content (Vf: %) in the molded body.

The fabric <NUM> can be used not only for the purpose of improving the deformability of the tape, but also for the purpose of ensuring a flow path for a matrix resin in resin impregnation, and for the purpose of strengthening the interval between the layers by using a resin including a material exhibiting high toughness.

A gap <NUM> is preferably provided between the plurality of carbon fiber bundles <NUM> constituting the carbon fiber tape material <NUM>. The presence of the gap <NUM> between the plurality of carbon fiber bundles <NUM> constituting the carbon fiber tape material <NUM> makes it easy to ensure a flow path for to matrix resin in the case of the material being used as a substrate by arrangement in one direction in the method of fiber placement. Also in the case of the material being used as a substrate by arranging a plurality of carbon fiber tape materials <NUM> in one direction without any gap in the method of fiber placement, the fluidity of a matrix resin in molding is more easily ensured when a gap provided between the plurality of carbon fiber bundles <NUM> fixed in one carbon fiber tape materials <NUM>.

The gap <NUM> between the carbon fiber bundles is preferably <NUM> to <NUM>. When the gap <NUM> is smaller than <NUM>, the flow path of the matrix resin is reduced, thus increasing the time required for molding, and there is a possibility of leading to a decrease in productivity. When the gap <NUM> is larger than <NUM>, there is a possibility, in molding the reinforcing fiber laminate obtained by laminating the carbon fiber tape material in the method of fiber placement, that the tape in the upper layer partially may fall into the gap between the carbon fiber bundles in the lower layer, thereby decreasing the straightness of the carbon fiber bundles. As a result, the compression characteristics of the molded body obtained may be deteriorated.

The tape width of the carbon fiber tape material <NUM> is preferably <NUM> to <NUM>, further preferably <NUM> to <NUM>. When the tape width of the carbon fiber tape material <NUM> is smaller than <NUM>, there is a need to place more carbon fiber tape materials in the fiber placement step, thereby making the productivity likely to be decreased. When the tape width of the carbon fiber tape material <NUM> is more than <NUM>, a large-size apparatus for manufacturing the tape easily leads to an increase in tape cost, which is not preferred.

A carbon fiber tape material <NUM> shown in <FIG> is a schematic perspective view of another carbon fiber tape material not in accordance with the present invention. The carbon fiber tape material <NUM> has, as with the carbon fiber tape material shown in <FIG>, a fabric <NUM> with regularity located on at least one surface of a carbon fiber bundle group <NUM>, and the fabric <NUM> is integrated with the carbon fiber bundle group <NUM> with a resin binder <NUM> attached to at least one surface of the carbon fiber bundle group <NUM> for the purpose of keeping the form of each carbon fiber bundle <NUM>. The other configuration is the same as the carbon fiber tape material <NUM> shown in <FIG>.

The resin binder <NUM> may have the form of a particle or the form of a non-woven fabric. The resin binder <NUM> is not to be considered limited to these forms, and may be a film, a mesh, an emulsion, a coating, or an auxiliary yarn wound around the carbon fiber bundle.

As the material of the resin binder, a thermoplastic resin such as a polyamide resin, a polyester resin, a polyethylene terephthalate resin, a polyvinyl formal resin, a polyether sulfone resin, a phenoxy resin, or a polycarbonate resin, a phenol-based resin, a phenoxy resin, an epoxy resin, a polystyrene-based resin, a polyolefin-based resin, a polyurethane-based resin, a polyester-based resin, a polyamide-based resin, a polybutadiene-based resin, a polyisoprene-based resin, a fluorine-based resin, a thermoplastic elastomer such as an acrylonitrile-based thermoplastic elastomer, or the like, a copolymer or a modified product thereof, a resin produced by blending two or more of these resins, or the like can be used.

These resin binders can be used to obtain the adhesive function of sticking the layers to one another when the reinforcing fiber laminate is formed. Furthermore, the resin binders can be used for the purpose of ensuring a flow path for a matrix resin in resin impregnation, and for the purpose of strengthening the interval between the layers by using a resin including a material exhibiting high toughness.

As a form of fixing the carbon fiber bundles <NUM> with the resin binder <NUM>, the resin binder <NUM> kept visible may be attached to and subjected to partial impregnation on the surfaces of the carbon fiber bundles <NUM>, thereby binding the plurality of filaments included in the carbon fiber bundle, or the resin binder <NUM> may be subjected to impregnation in the carbon fiber bundles <NUM> so as to be invisible from the surface, thereby binding the plurality of filaments included in the carbon fiber bundle to each other. In addition, the resin binder may be wound around the carbon fiber bundles <NUM>, or the carbon fiber bundle <NUM> may be coated with the resin binder.

The amount of the resin binder required for fixing the carbon fiber bundles <NUM> is preferably <NUM>% by weight or less, more preferably <NUM>% by weight or less, further preferably <NUM>% by weight or less, based on the weight of the carbon fiber bundles <NUM>. When the amount of the resin binder is more than <NUM>% by weight, the improved viscosity of the matrix resin makes the fluidity likely to be decreased in molding a reinforcing fiber laminate obtained by arranging and laminating the tape material by the method of fiber placement, and thus, the productivity is likely to be decreased. In addition, because a long period of time is required for the flow of the matrix resin, the viscosity of the matrix resin is further increased, and a site that is impregnated with no resin is likely to be generated in the molded body, which also leads to deteriorated mechanical property of the molded body.

The softening point Ts (°C) of the fabric <NUM> is preferably higher than the softening point of the resin binder <NUM>. When multiple types of thermoplastic resins constitute the fabric <NUM> herein, the softening point of the thermoplastic resin with the lowest softening point among the multiple types of thermoplastic resins is regarded as the softening point Ts (°C) of the fabric <NUM>. In this regard, heating and pressurizing at a temperature that is higher than the softening point of the resin binder <NUM> and lower than the softening point of the fabric <NUM> can integrate the fabric <NUM> and the carbon fiber bundle group <NUM> with the melted resin binder <NUM> as an adhesive. In this case, the fabric <NUM> keeps the form of structure without melting, and the carbon fiber tape material <NUM> with excellent deformability can be obtained without impairing the deformability of the fabric <NUM>.

In addition, the softening point (°C) of the resin binder <NUM> is preferably a temperature that is higher than <NUM> and lower than the softening point Ts (°C) of the fabric <NUM>. The use of such a resin binder can, at the temperature returned to room temperature by cooling or the like after the viscosity is reduced by heating, fix the plurality of filaments constituting the carbon fiber bundle to each other, and more reliably keep a certain form as a carbon fiber bundle. Then, when the form of the carbon fiber bundle is kept constant, the form of the carbon fiber bundle can be kept from collapsing in the case of the placement of the carbon fiber tape material <NUM> on a mold, and the application of a pressure or a tension to the carbon fiber tape material <NUM> by the method of fiber placement. As a result, the gaps <NUM> provided between the carbon fiber bundles <NUM> can be kept without being crushed, and the flow path of the matrix resin at the time of molding can be more reliably secured.

It is to be noted that in this specification, the "softening point" refers to a temperature at which a resin material such as a fabric or a resin binder softens/melts when the resin material reaches a temperature equal to or higher than the temperature. Specifically, when the resin material is a crystalline polymer, the melting point is referred to as the softening point; when the resin material is an amorphous polymer, the glass transition point is referred to as the softening point.

<FIG> shows a schematic perspective view of still another carbon fiber tape material <NUM> not in accordance with the present invention. In this carbon fiber tape material <NUM>, as with the aspect of <FIG>, a fabric <NUM> with regularity is placed on at least one surface (both surfaces in <FIG>) of a carbon fiber bundle group <NUM> that has a plurality of carbon fiber bundles <NUM> arranged in parallel. The fabric <NUM> is integrated with the carbon fiber bundle group <NUM> with a resin binder <NUM> attached to the surface of the carbon fiber bundle group <NUM> for the purpose of keeping the form of each carbon fiber bundle <NUM>. In the aspect shown in <FIG>, of the resin binder <NUM> provided on the surface of the carbon fiber bundle group <NUM>, only the resin binder <NUM> in the region surrounded by adhesive regions <NUM> is melted to contribute to bonding between the fabric <NUM> and the carbon fiber bundle group <NUM>. The adhesive regions <NUM> are formed not continuously but discretely (intermittently) in the fiber orientation direction of the carbon fiber bundles <NUM> in at least a part of the carbon fiber tape material <NUM>. The "adhesive region" herein refers to a region where the fabric <NUM> and the carbon fiber bundle group <NUM> are bonded to each other with the resin binder <NUM> interposed therebetween. The fabric <NUM> and the carbon fiber bundle group <NUM> are bonded to each other in at least some of the adhesive regions to be integrated with each other, thereby allowing the form of the carbon fiber tape material to be kept. The carbon fiber tape material <NUM> shown in <FIG> has the same configuration as the carbon fiber tape material <NUM> shown in <FIG> except for the foregoing respects.

The adhesive regions <NUM> are preferably formed discretely in the fiber orientation direction of the carbon fiber bundles <NUM> as described above. When the adhesive regions <NUM> extends over the entire tape to bond the carbon fiber bundle group <NUM> and the fabric <NUM> over the entire surface of the tape, the positions of the thermoplastic fibers constituting the fabric will be completely fixed by bonding to the carbon fiber bundles, thereby deteriorating the inherent deformability of the fabric. In <FIG>, because the adhesive regions <NUM> are discretely dispersed in the fiber orientation direction, there is room for the fabric to be free to move locally, thus making it possible to suppress deterioration in fabric deformability due to bonding.

Furthermore, an aspect in which adhesive regions are discretely formed in the fiber orientation direction of the carbon fiber bundles will be described in detail below. A carbon fiber tape material <NUM> shown in <FIG> is a plan view of a carbon fiber tape material according to the present invention. According to the embodiment of <FIG>, adhesive regions <NUM> where a fabric and a carbon fiber bundle group are bonded with a resin binder interposed therebetween are discretely formed in the fiber orientation direction of carbon fiber bundles <NUM> in the entire area of the carbon fiber tape material <NUM>. According to the present embodiment, the adhesive regions <NUM> are discretely formed over the entire area of the carbon fiber tape material <NUM>, and there is thus much room for the fabric to be free to move locally, thereby allowing excellent tape deformability to be exhibited. According to the embodiment of <FIG>, of a carbon fiber bundle group <NUM>, two carbon fiber bundles <NUM>(a) and <NUM>(b) located at both ends in a direction orthogonal to the fiber orientation direction of the carbon fiber bundles <NUM> are continuously bonded to a fabric <NUM> in the fiber orientation direction of the carbon fiber bundles, and carbon fiber bundles <NUM>(c), <NUM>(d), and <NUM>(e) located between the two carbon fiber bundles <NUM>(a) and <NUM>(b) are intermittently bonded to the fabric <NUM> in the fiber orientation direction of the carbon fiber bundles. According to the present embodiment, the two carbon fiber bundles <NUM>(a) and <NUM>(b) located at both ends in the direction orthogonal to the fiber orientation direction of the carbon fiber bundles are continuously bonded to the fabric <NUM>, thus allowing the fabric <NUM> to be kept from peeling off from the tape end, and allowing a balance to be achieved between the tape stability and the tape deformability. It is to be noted that in the carbon fiber tape material <NUM> shown in <FIG>, each adhesive region <NUM> is preferably provided so as not to extend over a plurality of carbon fiber bundles.

A carbon fiber tape material <NUM> shown in <FIG> is a plan view of another carbon fiber tape material not in accordance with the present invention. <FIG> respectively show a b-b cross section and a c-c cross section of the carbon fiber tape material <NUM>. Also according to the embodiment, adhesive regions <NUM> where a fabric and a carbon fiber bundle group are bonded with a resin binder interposed therebetween are discretely formed in the fiber orientation direction of carbon fiber bundles <NUM> in the entire area of the carbon fiber tape material <NUM>. Each adhesive region <NUM> is provided so as not to extend over a plurality of carbon fiber bundles. Further, for adjacent carbon fiber bundles (for example, <NUM>(a) and <NUM>(b)), the adhesive regions (for example, <NUM>(a) and <NUM>(b)) are shifted in the fiber orientation direction of the carbon fibers. According to the present embodiment, the adhesive regions provided respectively in the adjacent carbon fiber bundles are shifted in the fiber orientation direction of the carbon fibers, thereby allowing the relative positions of the adjacent carbon fiber bundles to vary independently without being fixed. Thus, when the fabric is deformed, the carbon fiber bundles are each allowed to move independently following the movements of parts of the fabric with the bundles bonded thereto.

Further, adhesive regions may be provided as in <FIG>. In a carbon fiber tape material <NUM> shown in <FIG>, however, for adjacent carbon fiber bundles (for example, <NUM>(a) and <NUM>(b)), adhesive regions (for example, adhesive regions <NUM>(a) and <NUM>(b)) are not shifted in the fiber orientation direction of the carbon fibers. Thus, the positions of the adjacent carbon fiber bundles are fixed, thereby making it difficult for each carbon fiber bundle to move independently following the movements of parts of the fabric with the bundles bonded thereto. Accordingly, as compared with the case where the adhesive regions are not shifted in the fiber orientation direction of the carbon fibers in the adjacent carbon fiber bundles, the case where the adhesive regions are shifted is preferred because a tape with high deformability can be obtained. Further, <FIG> is a plan view of the carbon fiber tape material <NUM>, and <FIG> is a b-b sectional view of the carbon fiber tape material <NUM>.

As shown in <FIG>, even when the adhesive regions <NUM> are provided to be substantially shifted in the fiber orientation direction of the carbon fibers, the following is more preferred. More specifically, in an arbitrary cross section in a direction orthogonal to the fiber orientation direction of the carbon fibers, the adhesive regions (for example, <NUM>(a) and <NUM>(b)) are kept from co-existing on the adjacent carbon fiber bundles (for example, <NUM>(a) and <NUM>(b)). In other words, in the adjacent carbon fiber bundles (for example, <NUM>(a) and <NUM>(b)), the adhesive regions (for example, <NUM>(a) and <NUM>(b)) are preferably provided so as to be shifted (as shown in <FIG>), rather than partially overlapped (as shown in <FIG>), in the fiber orientation direction of the carbon fibers. Such a configuration allows the carbon fiber tape material to exhibit more favorable deformability. To that end, in the carbon fiber tape material <NUM>, the part with such a cross section as shown in <FIG> preferably falls within the range of <NUM>% or less of all cross sections collected at regular intervals in the fiber orientation direction of the carbon fibers.

Furthermore, <FIG> show plan views of another carbon fiber tape material <NUM> not in accordance with the present invention. While <FIG> mentioned above show aspects in which the adhesive regions are discretely formed in the fiber orientation direction of the carbon fiber bundles, adhesive regions <NUM> in which a fabric and a carbon fiber bundle group are bonded with a resin binder interposed therebetween are discretely formed in a direction orthogonal to the fiber orientation direction of the carbon fiber bundles in the carbon fiber tape material <NUM> shown in <FIG>. Even such a configuration allows adjacent carbon fiber bundles to move independently without fixing the relative positions of the carbon fiber bundles, thus allowing the carbon fiber tape material to demonstrate favorable deformations.

The carbon fiber tape material according to the present invention, configured as described above allows the following shear deformation performance to be delivered. More specifically, the tensile load F [N] measured at a shear angle θ [°] in the range from <NUM>° to <NUM>° with the use of a picture frame method by a two sides gripping method has no maximum value for the tensile load F [N] at the shear angle θ [°] between <NUM>° and <NUM>°, the maximum value of the tensile load F [N] measured at the shear angle θ [°] in the range from <NUM>° to <NUM>° is higher than <NUM> [N], and ΔF/Δθ is larger than <NUM> and smaller than <NUM> at the shear angle θ [°] between <NUM>° and <NUM>°.

The picture frame method by the two sides gripping method, which is a method for evaluating shear deformation performance, will be described. <FIG> shows a schematic view of a picture frame method by a two sides gripping method. One or more carbon fiber tape materials <NUM> of <NUM> in length are arranged in parallel without any gap, and prepared such that the sum of the overall widths is <NUM>. After a gripping sections <NUM> are marked such that the gripping interval is <NUM>, the carbon fiber tape materials <NUM> are attached to a picture frame jig <NUM> so as to grip the two sides at both ends of the carbon fiber tape such that the gripping section <NUM> is <NUM>, the measurement angle α [°] is <NUM>°, and the longitudinal direction of the carbon fiber tape is parallel to two sides <NUM> of the picture frame gripping no carbon fiber tape material. The picture frame jig is attached to a universal testing machine, not shown, such that the measurement angle α [°] is <NUM>°, and then the picture frame jig is pulled in the vertical direction at a speed of <NUM>/min, and the tensile force F [N] and the measurement angle α at the time are measured. Thereafter, the shear angle θ [°] calculated from the following formula and ΔF/Δθ at θ [°] between <NUM>° and <NUM>° are calculated.

<FIG> shows an example of a shear angle-tensile load graph in the case of applying the picture frame method by the two sides gripping method to the carbon fiber tape material according to the present invention. <FIG> is a shear angle-tensile load graph in the case of testing at the shear angle θ [°] from <NUM> to <NUM>, and <FIG> is an enlargement of the same graph around the shear angle θ [°] from <NUM> to <NUM>.

In the carbon fiber tape material according to the present invention, the tensile load F preferably has no maximum value at the shear angle θ [°] between <NUM>° and <NUM>° in the case of testing at the shear angle θ [°] from <NUM>° to <NUM>°. Having the maximum value of the tensile load F [N] at the shear angle θ [°] between <NUM>° and <NUM>° means that the carbon fiber tape material fails to keep the form until the shear angle θ [°] reaches <NUM>°, thereby collapsing. In this case, the value of ΔF/Δθ fails to be evaluated as the shear deformation performance of the carbon fiber tape material.

For the carbon fiber tape material according to the present invention, when the tensile load F has no maximum value at the shear angle θ [°] between <NUM>° and <NUM>°, ΔF/Δθ at the shear angle θ [°] between <NUM>° and <NUM>° is preferably smaller than <NUM>, more preferably smaller than <NUM>, and still more preferably less than <NUM>. When ΔF/Δθ is <NUM> or more, a large force is required for the shear deformation of the carbon fiber tape material, and favorable followability to a mold fails be achieved in the alignment and placement in the mold by the method of fiber placement. In contrast, ΔF/Δθ is preferably larger than <NUM>. When ΔF/Δθ is <NUM> or less, the application of a slight force causes the carbon fiber tape material to undergo a significant shear deformation, thereby impairing the stability of the carbon fiber tape material.

For the carbon fiber tape material according to the present invention, the maximum value of the tensile load F is preferably more than <NUM> N, further preferably more than <NUM> N in the case of testing with the shear angle θ [°] from <NUM>° to <NUM>°. In the case of testing with the shear angle θ [°] from to <NUM>° to <NUM>°, the carbon fiber tape material fails to keep the tape form, due to peeling off between the carbon fiber bundle and the fabric material, and etc., when the maximum value of the tensile load F is <NUM> N or less.

Further, for the carbon fiber tape material according to the present invention, for example, as shown in <FIG>, a fabric <NUM> is preferably placed on both surfaces of a carbon fiber bundle group <NUM> to provide a tubular body (<FIG>) or a bag-like body (<FIG>) as a whole. More specifically, as shown in <FIG>, two carbon fiber bundles <NUM>(a) and <NUM>(b) located at both ends in the direction orthogonal to the fiber orientation direction of the carbon fiber bundles <NUM> are preferably, on both surfaces thereof, bonded to the fabric <NUM>, such that the carbon fiber bundles <NUM>(a) and <NUM>(b) at the both ends and the fabric <NUM> at the both surfaces form a tubular closed system. This makes it possible to prevent the three inner carbon fiber bundles <NUM>(c), <NUM>(d), and <NUM>(e) from falling off. In addition, for the same reason, it is also preferable to place the fabric <NUM> so as to enclose all of the carbon fiber bundles <NUM> as in <FIG>. The placement of the fabric on the both surfaces of the carbon fiber bundle group as described above makes it possible to keep the carbon fiber bundles from being detached during handling of the carbon fiber tape material, and makes it possible to improve the production stability of the carbon fiber tape material.

The carbon fiber tape material according to the present invention is used for a reinforcing fiber laminate. The reinforcing fiber laminate has a shape kept by arranging and laminating the carbon fiber tape material according to the present invention and at least partially sticking the interlayers. Such a configuration makes it possible to set the gap between the carbon fiber bundles constituting the reinforcing fiber laminate at any distance and then place the carbon fiber bundles. As a result, the productivity can be improved, such as that fact that the fluidity of the matrix resin during molding can be secured, and the fact that the types of resins injected and the variety of process window can be expanded.

Furthermore, the reinforcing fiber laminate with the carbon fiber tape material used is preferably impregnated with a matrix resin to obtain a fiber reinforced resin composite. The above-described configuration allows an obtained fiber reinforced resin composite to be completely impregnated to the inside thereof with the resin, thereby providing a high mechanical property.

The carbon fiber tape material according to the present invention will be described based on examples. Table <NUM> shows the conditions and results of examples and a comparative example.

As a reinforcing fiber bundle, a previously sized carbon fiber "TORAYCA" (registered trademark) T800SC manufactured by Toray Industries, Inc. and having <NUM>,<NUM> carbon fiber filaments (N = <NUM>) was used.

As a fabric, a knitted fabric (material: polyamide, basis weight: <NUM>/m<NUM>) with regularity was used, which was obtained by warp knitting into a tulle structure with the use of a tricot machine.

The fabric elongation rate was measured as follows with reference to JIS L <NUM><NUM>. More specifically, the fabric was cut into a width of <NUM> and a length of <NUM> such that the wale direction of the fabric was the longitudinal direction, and the gripping section was marked such that the gripping interval was <NUM>. After one end of the test piece was fixed with a clamp, a load of <NUM> mN/<NUM> was gently applied, and the length between the marks after holding for <NUM> minute was then measured. As a result of calculating the fabric elongation rate from the following formula, the elongation rate was <NUM>%.

With the use of a carbon fiber bundle manufacturing apparatus (not shown), one carbon fiber bundle was drawn out from a bobbin, the width was reduced without slitting while adjusting the thickness, and thereafter, heat-meltable binder particles (average particle size: <NUM>) with a softening point temperature of <NUM> were sprayed onto the surface of the carbon fiber bundle. The binder particles were sprayed so as to have a proportion of <NUM>% by weight (the weight of the obtained carbon fiber bundle was considered as <NUM>%), and then melted and cooled to obtain a carbon fiber bundle of <NUM> in yarn width with a form fixed.

Ten carbon fiber bundles were aligned in parallel in the longitudinal direction, a knitted fabric (fabric) with a softening point temperature of <NUM> was then placed on one surface of the carbon fiber bundles, and these were heated at <NUM> to melt the binder particles so as to partially bond (the binder particles were arranged in a staggered manner as spherical bodies of <NUM> in diameter on the carbon fiber bundles other than those at both ends, and the binder particles were arranged over the entire surface on the two carbon fiber bundles at the both ends) and then integrate the knitted fabric and the carbon fiber bundles with the binder particles interposed therebetween as shown in <FIG>. This integration provided a carbon fiber tape material with a width of <NUM>, a tape basis weight of <NUM>/m<NUM> excluding the fabric, and each gap of <NUM> between the carbon fiber bundles.

As an evaluation for the deformability of the carbon fiber tape material, the picture frame method by the two sides grip method was performed. Three carbon fiber tape materials with a length of <NUM> and a width of <NUM> were arranged in parallel, and marks were put on the gripping section such that the gripping interval was <NUM>. Then, the three carbon fiber tape materials arranged in parallel were attached to the picture frame jig shown in <FIG> so as to grip two sides such that the gripping section was <NUM> and that the measurement angle α [°] was <NUM>°, and subjected to a measurement. As a result, the maximum value of the tensile load F [N] at the shear angle θ [°] in the range from <NUM>° to <NUM>° was larger than <NUM> [N], without the maximum value at the shear angle θ [°] in the range from <NUM>° to <NUM>°. Further, with ΔF/Δθ = <NUM>, it has been confirmed that the carbon fiber tape material exhibits favorable deformability against the in-plane shear force.

With the use of a fiber placement device (not shown), the carbon fiber tape materials obtained in the manner as mentioned above were aligned in one direction and then placed on a stand so as to provide a gap of <NUM> between the respective carbon fiber tape materials; the carbon fiber tape materials were repeatedly cut and placed into a square shape of <NUM> × <NUM> to prepare a sheet substrate. The adjacent carbon fiber tape materials were bonded and integrated by lapping adjacent knitted fabrics by <NUM> and heating the lapped part at <NUM> to prepare a sheet substrate.

The obtained sheet substrate was placed in a pyramid (tetrahedral) shaped mold (bottom surface: equilateral triangle of <NUM> on a side, height: <NUM>), and the upper mold was lowered for press draping while applying a tension to the sheet substrate, and then, the lower mold was heated at <NUM> for <NUM> minutes. As a result, the sheet substrate exhibited a favorable draping property without large wrinkles. After the sheet substrate was sequentially subjected to draping layer by layer into the pyramid-shaped mold in the same procedure, the upper mold was closed, and the lower mold was then heated at <NUM> for <NUM> minutes. As a result, a favorable reinforcing fiber laminate was obtained without large wrinkles.

The obtained reinforcing fiber laminate was placed in the lower mold in the above-described pyramid shape, vacuum bagging was performed with the use of a bagging film, and the mold was then placed in an oven at an atmospheric temperature of <NUM>. Thereafter, a matrix resin (epoxy resin) was injected and cured in an atmosphere at <NUM>. As a result, a favorable molded body without any resin-unimpregnated site was obtained.

A carbon fiber tape was obtained in the same manner as in Example <NUM> except for the following point.

As a result of measuring the elongation rate in the same manner as in Example <NUM>, the elongation rate in the wale direction was <NUM>%.

As a result of performing the picture frame method by the two sides grip method in the same manner as in Example <NUM>, the maximum value of the tensile load F [N] at the shear angle θ [°] in the range from <NUM>° to <NUM>° was larger than <NUM> [N], without the maximum value at the shear angle θ [°] in the range from <NUM>° to <NUM>°. Further, with ΔF/Δθ = <NUM>, it has been confirmed that the carbon fiber tape material exhibits favorable deformability against the in-plane shear force.

As a result of performing the same method as in Example <NUM>, a favorable reinforcing fiber laminate was obtained without twisting or wrinkling the sheet substrate.

As a result of performing the same method as in Example <NUM>, a favorable molded body without any resin-unimpregnated site was obtained.

As a result of measuring the elongation rate in the same manner as in Example <NUM>, the elongation rate in the wale direction was <NUM>%, thus providing favorable formability.

As a result of measuring the elongation rate in the same manner as in Example <NUM>, the elongation rate in the wale direction was <NUM>%, thus failing to provide favorable formability.

As a result of performing the picture frame method by the two sides grip method in the same manner as in Example <NUM>, the maximum value of the tensile load F [N] at the shear angle θ [°] in the range from <NUM>° to <NUM>° was larger than <NUM> [N], without the maximum value at the shear angle θ [°] in the range from <NUM>° to <NUM>°. Further, with ΔF/Δθ = <NUM>, it has been confirmed that the carbon fiber tape material exhibits no favorable deformability against the in-plane shear force.

As a result of performing the same method as in Example <NUM>, the sheet substrate was found to be twisted and wrinkled, and so any favorable reinforcing fiber laminate was not obtained.

As a result of performing the same method as in Example <NUM>, a molded body with a resin-unimpregnated site at the wrinkled site was obtained.

Claim 1:
A carbon fiber tape material (<NUM>) wherein a carbon fiber bundle group (<NUM>) comprising a plurality of carbon fiber bundles (<NUM>) arranged in parallel with a fiber orientation direction is integrated with a fabric (<NUM>), the carbon fiber tape material (<NUM>) satisfying the following (a) to (c):
(a) the fabric (<NUM>)comprises one or more thermoplastic resins;
(b) the carbon fiber tape material (<NUM>) excluding the fabric (<NUM>) is between <NUM>/m<NUM> and <NUM>/m<NUM> in basis weight; and
(c) a fabric elongation rate Ep (%) with a load of <NUM> mN/<NUM> applied to the fabric (<NUM>) is <NUM>% to <NUM>% in at least one direction of the fabric (<NUM>) <MAT>
Ep: fabric elongation rate (%)
L<NUM>: original fabric length between marks (mm)
L<NUM>: fabric length at load application (mm),
wherein the carbon fiber bundle group (<NUM>) and the fabric (<NUM>) are integrated by bonding, with a resin binder attached to at least one surface of the carbon fiber bundle group (<NUM>) interposed therebetween,
wherein an adhesive region (<NUM>) where the fabric (<NUM>) and the carbon fiber bundle group (<NUM>) are bonded with the resin binder interposed therebetween is discretely formed in the fiber orientation direction of the carbon fiber bundles (<NUM>) in at least a part of the carbon fiber tape material (<NUM>), characterized in that
of the carbon fiber bundle group (<NUM>), two carbon fiber bundles (<NUM>(a), <NUM>(b)) located at both ends in a direction orthogonal to the fiber orientation direction of the carbon fiber bundles (<NUM>) are continuously bonded to the fabric (<NUM>) in the fiber orientation direction of the carbon fiber bundles (<NUM>), and the other carbon fiber bundles (<NUM>(c), <NUM>(d), <NUM>(e)) located between the two carbon fiber bundles (<NUM>(a), <NUM>(b)) are intermittently bonded to the fabric (<NUM>) in the fiber orientation direction of the carbon fiber bundles (<NUM>).