Patent Application
20220379523
This disclosure relates to a reinforcing fiber tape material, a reinforcing fiber laminate, and a molded body produced by placing and laminating the reinforcing fiber tape material.
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 light weight and high strength. Examples of a 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.
To solve such a problem, a method of fiber placement has been attracting attention. In that method, a reinforced fiber bundle is placed only at a necessary portion 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, Japanese Patent Laid-open Publication No. 2012-510385 proposes a carbon fiber tape material with a polymer adhesive bonded to both surfaces thereof, and a method of producing the material. That 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, Japanese Patent Laid-open Publication No. 2017-521291 proposes a carbon fiber tape material with a non-woven veil bonded to at least one surface thereof, a preform, and a method of 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, when a thermoplastic fiber material is used for the non-woven veil, the resulting composite material can be toughened.
Furthermore, Japanese Patent Laid-open Publication No. 2015-116806 proposes a reinforcing sheet material including a reinforcing fiber material with a basis weight of 80 g/m2 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.
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 JP '385. When, 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 JP '291, 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 JP '385.
According to JP '806, 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 to obtain a desired product thickness, thereby leading to complicated work and decreasing the productivity. In addition, JP '806 relates to a reinforcing sheet material, and fails to suggest the application of the reinforcing sheet material to the method of fiber placement.
It could therefore be helpful to provide a carbon fiber tape material favorable in followability to molds and impregnation with matrix resins, and capable of enhancing the productivity in 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, it could be helpful to provide a reinforcing fiber laminate and molded body obtained from the carbon fiber tape material.
We thus provide:
(1) A carbon fiber tape material where a carbon fiber bundle group comprising a plurality of carbon fiber bundles arranged in parallel with the fiber orientation direction and a fabric are integrated, the carbon fiber tape material satisfying (a) to (c):
(a) the fabric includes one or more thermoplastic resins;
(b) the carbon fiber tape material excluding the fabric is between 120 g/m2 and 400 g/m2 in basis weight; and
(c) the fabric elongation rate Ep (%) with a load of 80 mN/50 mm applied to the fabric is 5% to 100% in at least one direction of the fabric:
E
p={(L1−L0)/L0}×100
(2) The carbon fiber tape material according to item (1), wherein the fabric has regularity.
(3) The carbon fiber tape material according to item (1) or (2), wherein a gap of 0.1 mm to 1 mm is provided between the carbon fiber bundles.
(4) The carbon fiber tape material according to any of items (1) to (3), wherein the carbon fiber tape material is 2 mm to 2000 mm in tape width.
(5) The carbon fiber tape material according to any of items (1) to (4), wherein the carbon fiber bundle group and the fabric are integrated by bonding, with a resin binder attached to at least one surface of the carbon fiber bundle group interposed therebetween.
(6) The carbon fiber tape material according to item (5), wherein an adhesive region where the fabric and the carbon fiber bundle group are bonded with the resin binder interposed therebetween is discretely formed in the fiber orientation direction of the carbon fiber bundles in at least a part of the carbon fiber tape material.
(7) The carbon fiber tape material according to item (6), wherein an adhesive region where the fabric and the carbon fiber bundle group are bonded with the resin binder interposed therebetween is discretely formed in the fiber orientation direction of the carbon fiber bundles in the entire area of the carbon fiber tape material.
(8) The carbon fiber tape material according to item (6), wherein, of the carbon fiber bundle group, two carbon fiber bundles located at both ends in a direction orthogonal to the fiber orientation direction of the carbon fiber bundles are continuously bonded to the fabric in the fiber orientation direction of the carbon fiber bundles, and the other carbon fiber bundles located between the two carbon fiber bundles are intermittently bonded to the fabric in the fiber orientation direction of the carbon fiber bundles.
(9) The carbon fiber tape material according to any of items (6) to (8), wherein, of the adhesive region where the fabric and the carbon fiber bundle group are bonded with the resin binder interposed therebetween, the adhesive region is shifted in the fiber orientation direction of the carbon fiber in the adjacent carbon fiber bundles.
(10) The carbon fiber tape material according to item (5), wherein an adhesive region where the fabric and the carbon fiber bundle group are bonded with the resin binder interposed therebetween is discretely formed in a direction orthogonal to the fiber orientation of the carbon fiber bundles in at least a part of the carbon fiber tape material.
(11) The carbon fiber tape material according to any of items (1) to (10), wherein the tensile load F [N] measured at a shear angle θ [° ] in the range from 0° to 45° by using 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 0° and 1.0°, the maximum value of the tensile load F [N] measured at the shear angle θ [° ] of 0° to 45° is higher than 0.5 [N], and ΔF/Δθ is larger than 0.1 and smaller than 1.0 at the shear angle θ [° ] between 0.1° and 1.0°.
(12) The carbon fiber tape material according to items (1) to (11), wherein the fabric has a form of a tubular body or a bag-like body.
(13) A reinforcing fiber laminate including the carbon fiber tape material according to any of items (1) to (12).
(14) A molded body including the reinforcing fiber laminate according to item (13).
Our carbon fiber tape material is favorable in followability to molds and impregnation with resins, and capable of enhancing the productivity in 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.
The carbon fiber tape material 100 shown in
As the carbon fiber bundle, 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 may have an organic fiber mixed with a carbon fiber.
The number of filaments N (unit: K=1,000) in the carbon fiber bundle is, in a preferred aspect, 1 K (1,000) or more and 60 K (60,000) or less. When the number of single fibers in the carbon fiber bundle 101 is less than 1 K, the yarn width of the carbon fiber bundle 101 is narrow, and defects such as twisting are likely to occur. When the number of the single fibers in the carbon fiber bundle 101 is more than 60 K, the carbon fiber basis weight of the carbon fiber bundle 101 is high, and when the carbon fiber bundles 101 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 100 includes a plurality of carbon fiber bundles 101 mutually integrated with the fabric 103, 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 103 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 103. This fabric 103 is partially melted to be integrated with the carbon fiber bundle group 102.
It is important for the fabric 103 to have deformability. More specifically, it is important for the fabric elongation rate with a load of 80 mN/50 mm applied to the fabric in at least one direction of the fabric to be 5% to 100%, and further preferably 15% to 100%. 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 directly attaching the tape to the mold by the method of fiber placement. When the fabric elongation rate is less than 5%, the fabric has insufficient deformability and the carbon fiber tape fails to follow the mold shape. When the fabric elongation rate is more than 100%, 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 formula in accordance with JIS L 1096 8.16.1:
E
p={(L1−L0)/L0}×100
It is important for the carbon fiber tape material to have a basis weight excluding fabric between 120 g/m2 and 400 g/m2. When the basis weight of the carbon fiber tape material excluding the fabric is less than 120 g/m2, 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 400 g/m2, 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 160 g/m2 to 300 g/m2.
In addition, the fabric 103 desirably has regularity. The wording “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, compared to 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 a force applied in the plane (planar direction) of the fabric.
The basis weight of the fabric 103 is preferably more than 2 g/m2 and 40 g/m2 or less, further preferably more than 4 g/m2 and 20 g/m2 or less. When the basis weight of the fabric 103 is 2 g/m2 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 103 is more than 40 g/m2, 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 103 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 106 is preferably provided between the plurality of carbon fiber bundles 101 constituting the carbon fiber tape material 100. The presence of the gap 106 between the plurality of carbon fiber bundles 101 constituting the carbon fiber tape material 100 makes it easy to ensure a flow path for to matrix resin in the material being used as a substrate by arrangement in one direction in the method of fiber placement. Also, in the material being used as a substrate by arranging a plurality of carbon fiber tape materials 100 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 101 fixed in one carbon fiber tape materials 100.
The gap 106 between the carbon fiber bundles is preferably 0.1 mm to 1 mm. When the gap 106 is smaller than 0.1 mm, 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 106 is larger than 1 mm, 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 100 is preferably 2 mm to 2000 mm, further preferably 5 mm to 100 mm. When the tape width of the carbon fiber tape material 100 is smaller than 2 mm, 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 100 is more than 2000 mm, 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 200 shown in
The resin binder 204 may have the form of a particle or the form of a non-woven fabric. The resin binder 204 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 201 with the resin binder 204, the resin binder 204 kept visible may be attached to and subjected to partial impregnation on the surfaces of the carbon fiber bundles 201, thereby binding the plurality of filaments included in the carbon fiber bundle, or the resin binder 204 may be subjected to impregnation in the carbon fiber bundles 201 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 201, or the carbon fiber bundle 201 may be coated with the resin binder.
The amount of the resin binder required to fix the carbon fiber bundles 201 is preferably 25% by weight or less, more preferably 20% by weight or less, further preferably 15% by weight or less, based on the weight of the carbon fiber bundles 201. When the amount of the resin binder is more than 25% 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 203 is preferably higher than the softening point of the resin binder 204. When multiple types of thermoplastic resins constitute the fabric 203 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 203. In this regard, heating and pressurizing at a temperature that is higher than the softening point of the resin binder 204 and lower than the softening point of the fabric 203 can integrate the fabric 203 and the carbon fiber bundle group 202 with the melted resin binder 204 as an adhesive. In this example, the fabric 203 keeps the form of structure without melting, and the carbon fiber tape material 200 with excellent deformability can be obtained without impairing the deformability of the fabric 203.
In addition, the softening point (° C.) of the resin binder 204 is preferably a temperature higher than 40° C. and lower than the softening point Ts (° C.) of the fabric 203. 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 placement of the carbon fiber tape material 200 on a mold, and the application of a pressure or a tension to the carbon fiber tape material 200 by the method of fiber placement. As a result, the gaps 206 provided between the carbon fiber bundles 201 can be kept without being crushed, and the flow path of the matrix resin at the time of molding can be more reliably secured.
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.
The adhesive regions 305 are preferably formed discretely in the fiber orientation direction of the carbon fiber bundles 301 as described above. When the adhesive regions 305 extends over the entire tape to bond the carbon fiber bundle group 302 and the fabric 303 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
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 400 shown in
A carbon fiber tape material 500 shown in
Further, adhesive regions may be provided as in
As shown in
Furthermore,
The carbon fiber tape material 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 [° ] of 0° to 45° 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 0° and 1.0°, the maximum value of the tensile load F [N] measured at the shear angle θ [°] of 0° to 45° is higher than 0.5 [N], and ΔF/Δθ is larger than 0.1 and smaller than 1.0 at the shear angle θ [°] between 0.1° and 1.0°.
The picture frame method by the two sides gripping method, which is a method of evaluating shear deformation performance, will be described.
θ[°]=90°−α[°].
In the carbon fiber tape material, the tensile load F preferably has no maximum value at the shear angle θ [° ] between 0° and 1.0° in testing at the shear angle θ [°] from 0° to 45°. Having the maximum value of the tensile load F [N] at the shear angle θ [°] between 0° and 1.0° means that the carbon fiber tape material fails to keep the form until the shear angle θ [°] reaches 1.0°, thereby collapsing. In this example, 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, when the tensile load F has no maximum value at the shear angle θ [°] between 0° and 1.0°, ΔF/Δθ at the shear angle θ [°] between 0.1° and 1.0° is preferably smaller than 1.0, more preferably smaller than 0.4, and still more preferably less than 0.2. When ΔF/Δθ is 1.0 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 0.1. When ΔF/Δθ is 0.1 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, the maximum value of the tensile load F is preferably more than 0.5 N, further preferably more than 1.0 N in testing with the shear angle θ [°] from 0° to 45°. In testing with the shear angle θ [°] from to 0° to 45°, the carbon fiber tape material fails to keep the tape form, due to peeling off between the carbon fiber bundle and the fabric material, when the maximum value of the tensile load F is 0.5 N or less.
Further, for the carbon fiber tape material, for example, as shown in
The carbon fiber tape material is used for a reinforcing fiber laminate. The reinforcing fiber laminate has a shape kept by arranging and laminating the carbon fiber tape material 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.
Our carbon fiber tape material will be described based on examples. Table 1 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 24,000 carbon fiber filaments (N=24 K) was used.
As a fabric, a knitted fabric (material: polyamide, basis weight: 8 g/m2) 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 1096 8.16.1. More specifically, the fabric was cut into a width of 50 mm and a length of 300 mm such that the wale direction of the fabric was the longitudinal direction, and the gripping section was marked such that the gripping interval was 200 mm. After one end of the test piece was fixed with a clamp, a load of 80 mN/50 mm was gently applied, and the length between the marks after holding for 1 minute was then measured. As a result of calculating the fabric elongation rate from the formula, the elongation rate was 52%:
E
p={(L1−L0)/L0}×100
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: 0.2 mm) with a softening point temperature of 80° C. were sprayed onto the surface of the carbon fiber bundle. The binder particles were sprayed to have a proportion of 5% by weight (the weight of the obtained carbon fiber bundle was considered as 100%), and then melted and cooled to obtain a carbon fiber bundle of 4.8 mm 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 200° C. was then placed on one surface of the carbon fiber bundles, and these were heated at 120° C. to melt the binder particles to partially bond (the binder particles were arranged in a staggered manner as spherical bodies of 4.5 mm 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
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 220 mm and a width of 50 mm were arranged in parallel, and marks were put on the gripping section such that the gripping interval was 200 mm. Then, the three carbon fiber tape materials arranged in parallel were attached to the picture frame jig shown in
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 to provide a gap of 0.7 mm between the respective carbon fiber tape materials; the carbon fiber tape materials were repeatedly cut and placed into a square shape of 300 mm×300 mm to prepare a sheet substrate. The adjacent carbon fiber tape materials were bonded and integrated by lapping adjacent knitted fabrics by 1 mm and heating the lapped part at 200° C. to prepare a sheet substrate.
The obtained sheet substrate was placed in a pyramid (tetrahedral) shaped mold (bottom surface: equilateral triangle of 14 cm on a side, height: 7 cm), 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 120° C. for 10 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 120° C. for 10 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 100° C. Thereafter, a matrix resin (epoxy resin) was injected and cured in an atmosphere at 180° C. 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 1 except for the following point:
As a fabric, a knitted fabric (material: polyamide, basis weight: 10 g/m2) with regularity was used, which was obtained by warp knitting into a chain+half structure with the use of a tricot machine.
As a result of measuring the elongation rate in the same manner as in Example 1, the elongation rate in the wale direction was 35%.
As a result of performing the picture frame method by the two sides grip method in the same manner as in Example 1, the maximum value of the tensile load F [N] at the shear angle [° ] of 0° to 45° was larger than 0.5 [N], without the maximum value at the shear angle θ [° ] of 0° to 1.0°. Further, with ΔF/Δθ=0.37, we 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 1, 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 1, a favorable molded body without any resin-unimpregnated site was obtained.
A carbon fiber tape was obtained in the same manner as in Example 1 except for the following point:
After carbon fiber bundles of 3.5 mm in yarn width with a form fixed were obtained in the same manner as in Example 1, ten carbon fiber bundles were aligned in parallel in the longitudinal direction, and each gap between the carbon fiber bundles was adjusted to about 0.3 mm such that the finally obtained carbon fiber tape material was 38 mm in width and 271 g/m2 in tape basis weight excluding the fabric.
The knitted fabric and the carbon fiber bundles were, as shown in
As a result of performing the picture frame method by the two sides grip method in the same manner as in Example 1, the maximum value of the tensile load F [N] at the shear angle [° ] of 0° to 45° was larger than 0.5 [N], without the maximum value at the shear angle θ [°] of 0° to 1.0°. Further, with ΔF/Δθ=0.17, we 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 1, 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 1, a favorable molded body without any resin-unimpregnated site was obtained.
A carbon fiber tape was obtained in the same manner as in Example 1 except for the following point:
After carbon fiber bundles of 7.0 mm in yarn width with a form fixed were obtained in the same manner as in Example 1, five carbon fiber bundles were aligned in parallel in the longitudinal direction, and each gap between the carbon fiber bundles was adjusted to about 0.7 mm such that the finally obtained carbon fiber tape material was 38 mm in width and 135 g/m2 in tape basis weight excluding the fabric.
The knitted fabric and the carbon fiber bundles were, as shown in
As a result of performing the picture frame method by the two sides grip method in the same manner as in Example 1, the maximum value of the tensile load F [N] at the shear angle θ [° ] of 0° to 45° was larger than 0.5 [N], without the maximum value at the shear angle θ [°] of 0° to 1.0°. Further, with ΔF/Δθ=0.33, we 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 1, 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 1, a favorable molded body without any resin-unimpregnated site was obtained.
A carbon fiber tape was obtained in the same manner as in Example 1 except for the following point:
As a fabric, a non-woven fabric (material: polyamide, basis weight: 6 g/m2) from Spunfab Ltd. was used.
After carbon fiber bundles of 3.5 mm in yarn width with a form fixed were obtained in the same manner as in Example 1, ten carbon fiber bundles were aligned in parallel in the longitudinal direction, and each gap between the carbon fiber bundles was adjusted to 0.3 mm such that the finally obtained carbon fiber tape material was 38 mm in width and 271 g/m2 in tape basis weight excluding the fabric.
The non-woven fabric and the carbon fiber bundles were, as shown in
As a result of measuring the elongation rate in the same manner as in Example 1, the elongation rate in the wale direction was 10%, thus providing favorable formability.
As a result of performing the picture frame method by the two sides grip method in the same manner as in Example 1, the maximum value of the tensile load F [N] at the shear angle [° ] of 0° to 45° was larger than 0.5 [N], without the maximum value at the shear angle θ [°] of 0° to 1.0°. Further, with ΔF/Δθ=0.23, we 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 1, 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 1, a favorable molded body without any resin-unimpregnated site was obtained.
A carbon fiber tape was obtained in the same manner as in Example 1 except for the following point:
As a fabric, a non-woven fabric (material: polyamide, softening point: 130° C., basis weight: 10 g/m2) from Spunfab Ltd. was used.
Ten carbon fiber bundles without any binder particle attached thereto were aligned in parallel in the longitudinal direction, a non-woven fabric with a softening point temperature of 130° C. was then placed on one surface of the carbon fiber bundles, and these were heated at 130° C. to melt the nonwoven fabric to entirely bond and then integrate the non-woven fabric and the carbon fiber bundles. This integration provided a carbon fiber tape material with a width of 50 mm, a tape basis weight of 206 g/m2 excluding the fabric, and each gap of 0.2 mm between the carbon fiber bundles.
As a result of measuring the elongation rate in the same manner as in Example 1, the elongation rate in the wale direction was 3%, 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 1, the maximum value of the tensile load F [N] at the shear angle [° ] of 0° to 45° was larger than 0.5 [N], without the maximum value at the shear angle θ [° ] of 0° to 1.0°. Further, with ΔF/Δθ=1.2, we 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 1, 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 1, a molded body with a resin-unimpregnated site at the wrinkled site was obtained.
Our carbon fiber tape material and the reinforcing fiber laminate with the material used are excellent in the impregnation property with a matrix resin, and the molded body obtained with the use of the reinforcing fiber laminate is also suitably used, in particular, for large members for aircraft, automobiles, ships and the like and members for general industrial applications such as windmill blades.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-203907 | Nov 2019 | JP | national |
| 2019-203908 | Nov 2019 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2020/041312 | 11/5/2020 | WO |
