JP4742840B2 - Multilayer substrate, preform, and preform manufacturing method - Google Patents

Description

  The present invention relates to a multilayer base material having excellent formability used when molding a preform, a preform using the same, and a method for producing the preform. More specifically, a multilayer base material excellent in moldability and handleability, and a preform and a preform manufacturing method using the same, which are suitably used for manufacturing a fiber reinforced resin (hereinafter referred to as FRP) with high productivity. It is about.

  FRP is widely used in various fields such as aircraft use, general industrial use, and sports use because of its high specific strength and high specific modulus.

  As a typical manufacturing method of FRP, a prepreg in which a reinforcing fiber base is impregnated with a matrix resin in advance is used, and this prepreg is laminated so that the arrangement direction of the reinforcing fibers is shifted every lamination (for example, pseudo isotropic lamination). There is an autoclave molding method for curing a matrix resin. On the other hand, in order to reduce the molding cost of FRP, a matrix resin (mainly thermosetting resin is used) selected according to the purpose and application is applied to the laminate of the reinforcing fiber base material in a dry state under reduced pressure. Then, there is a vacuum injection molding method for curing. Such a dry intermediate substrate is more easily shaped than the molding material (for example, prepreg) integrated with the matrix resin, although the arrangement of the reinforcing fibers is somewhat disturbed, and the matrix resin is appropriately selected. Since injection is performed later, there is an advantage that a complex-shaped FRP can be easily obtained. Due to this difference, the molding material and the dry intermediate substrate are applied separately by a desired member.

  A dry intermediate base material mainly used in such a vacuum injection molding method is a so-called multiaxial stitch base in which sheets in which reinforcing fibers are arranged in parallel are cross-laminated and integrated with stitch yarns. The material is attracting attention. Since this multi-axis stitch base material can obtain a material having a desired configuration and characteristics with one sheet, a fiber that is cut into a predetermined size in the FRP manufacturing process like a conventional dry intermediate base material (for example, woven fabric) There is no need to stack a plurality of sheets so as to be arranged in a predetermined direction, and there is an advantage that stacking work is greatly saved and inexpensive FRP can be obtained. However, since the multi-axis stitch base material is a material form that restrains the reinforcing fiber by the stitch yarn, it is difficult to mold into a complicated shape even with a dry intermediate base material depending on the stitch yarn knitting structure In some cases, the shape of the FRP is limited to a simple shape such as a flat plate.

  In order to solve this problem, Patent Document 1 discloses that a low-melting polymer yarn is melt-cured and surface smoothened by impregnating a resin into a multiaxial stitch base material integrated with a low-melting polymer yarn and heating it. There is a proposal of a technique for forming an excellent FRP. However, since such a proposal does not describe a technique for tying up reinforcing fibers other than stitches, when deep drawing is performed using such a multiaxial stitch base material, moldability is obtained by melting the stitch yarn. However, there has been a problem in that there is no technique for connecting the reinforcing fibers in parallel after the stitch yarn is melted, and there is a gap between the reinforcing fibers or the arrangement of the reinforcing fibers is disturbed.

  Patent Document 2 describes the content that the formability can be improved by manipulating the configuration of the knitting structure that stitches the multiaxial stitch base material. According to such a proposal, although it is possible to improve the formability to some extent, there are problems such as a decrease in handleability and difficulty in maintaining the form of the reinforcing fibers.

In other words, conventional techniques such as Patent Documents 1 and 2 do not provide a multi-axis stitch base material that is a dry intermediate base material that achieves both formability and handleability. Has been.
JP 2002-227066 A JP 2002-317371 A

  An object of the present invention is to solve the above-mentioned problems. That is, the present invention is a dry intermediate base material that can reduce the molding cost of FRP, and can select a matrix resin according to the purpose and application, and has both moldability and handleability, and the productivity of FRP. It is an object of the present invention to provide a multilayer substrate excellent in the above, a preform using the same and a method for producing the same.

In order to achieve the above object, the present invention is characterized by the following configurations (1) to ( 9 ) .
( 1 ) A multi-layer base material in which at least two pairs of biaxial stitch base materials are laminated and integrated with a plurality of types of engaging materials, and the biaxial stitch base material has a large number of reinforcing fiber yarns. A plurality of sheets arranged in parallel are laminated so that the reinforcing fiber yarns are oriented in two directions, and stitched with stitch yarn A. The melting points Tmc of the plurality of types of engaging materials are all 80 to 200 ° C. And the melting point Tma of the stitch yarn A is within the range of (Tmd + 10) to (Tmd + 120) ° C., where Tmd is the highest melting point among the melting points Tmc of the plurality of engagement materials. Wood.
( 2 ) The multilayer base material according to (1 ), wherein the plurality of sheets in the biaxial stitch base material are laminated so that the intersecting angles of the reinforcing fiber yarns are substantially orthogonal.
( 3 ) The biaxial stitch base material has a forming limit shear deformation angle (A) in the ± 45 ° direction when one direction of the arranged reinforcing fiber yarns is defined as 0 °, and the arranged reinforcing fiber yarns. The multilayer base material according to the above ( 2 ), wherein the forming limit shear deformation angle (B) in the ± 45 ° direction when the other direction is 0 ° is in the range of 45 to 80 °.
( 4 ) The stitch length S and the gauge length G of the stitch yarn A in the biaxial stitch base material are substantially the same, and the stitch length of the stitch yarn A is in the range of 3 to 50 mm (1) The multilayer substrate according to any one of ( 3 ) to ( 3 ).
( 5 ) The number of sheets in the biaxial stitch base is in the range of 2 to 4, the total number of sheets in the multilayer base is in the range of 4 to 24, and at least two pairs of biaxial stitch bases are reinforced. The multilayer substrate according to any one of the above (1) to ( 4 ), wherein the fiber yarns are laminated so that the orientation direction of the fiber yarns is mirror-symmetrical.
( 6 ) Particles, cut fibers, in which the engagement material is arranged and fixed between stitch yarns B for sewing at least two sets of biaxial stitch bases and / or at least two sets of biaxial stitch bases The multilayer substrate according to any one of (1) to ( 5 ), which is at least one selected from the group consisting of woven fabrics, knitted fabrics, nonwoven fabrics, and meshes.
( 7 ) A preform in which the multilayer base material according to any one of (1) to ( 6 ) is shaped into a shape having a quadric surface while maintaining the continuity of the stitch yarn A.
( 8 ) A method for producing a preform, wherein the multilayer substrate according to any one of (1) to ( 6 ) is shaped into a predetermined shape in the following steps (a) and (b).
(B) Insulation step of keeping the multilayer substrate in a temperature atmosphere of Tmd to (Tma-10) ° C. (b) Next, the multilayer substrate is pressed at a temperature of 0 to (Tmd-10) ° C. ( 9 ) In the heat-retaining step (a), the engagement material is softened or melted while maintaining the continuity of the stitch yarn A. ( 8) Preform manufacturing method.

  According to the multilayer base material of the present invention, it is excellent in handling even though sheets in which a large number of reinforcing fiber yarns are arranged in parallel are laminated in a multilayer, and further, the reinforcing fibers in the biaxial stitch base material The constraint between the biaxial stitch base materials can be at least partially released while maintaining the constraint of the yarn, and each can be deformed independently of each other. It is possible to shape while preventing the occurrence. Therefore, when producing a preform and FRP using such a multilayer substrate, the number of sheets of reinforcing fiber yarns can be increased in advance, and the productivity is excellent. Further, since the reinforcing fiber yarns are arranged so as to be oriented straight in the sheet, not only the obtained FRP can exhibit excellent mechanical properties such as strength and elastic modulus, but also excellent in appearance quality. .

In the multilayer base material of the present invention, at least two sets of biaxial stitch base materials are laminated and integrated by the engaging material. In each biaxial stitch base material, a plurality of sheets in which a large number of reinforcing fiber yarns are arranged in parallel are laminated so that the reinforcing fiber yarns are oriented in two directions, and stitched with stitch yarns A. Furthermore, the melting point Tmc of the engaging material is in the range of 80 to 200 ° C., and the stitch yarn A melting point Tma is in the range of (Tmc + 10) to (Tmc + 120) ° C. Here, in the multilayer base material of the present invention, a plurality of sets of biaxial stitch base materials are integrated with a plurality of types of engagement materials, and the melting points Tmc of the plurality of types of engagement materials are all 80 to 200 ° C. The melting point Tma of the stitch yarn A is in the range of (Tmd + 10) to (Tmd + 120) ° C., where Tmd is the highest melting point among the melting points Tmc of the plurality of types of engagement materials.

Thus, the multilayer substrate according to the present invention is roughly composed of two components. One is a sheet made of a reinforcing fiber yarn, a biaxial stitched base material integrally stacked so that reinforcing fiber yarns is Oriented in two directions. Such a biaxial stitch base is integrated by the stitch yarn A. The other is a multilayer substrate obtained by further laminating two or more pairs of the biaxial stitch substrates. Such a multilayer base material is integrated by an engaging material such as a fixing material and stitch yarn B.

  In the present invention, the type of reinforcing fiber yarn is not particularly limited as long as it becomes a reinforcing material for FRP. For example, carbon fiber, graphite fiber, glass fiber, and aramid, paraphenylenebenzobisoxazole, Examples thereof include organic fibers such as polyvinyl alcohol, polyethylene, and polyarylate, and one or a combination of two or more of these can be used. Among these, carbon fibers are excellent in specific strength and specific elastic modulus and are preferably used.

  In the present invention, the arrangement direction of the reinforcing fiber yarns in the biaxial stitch base material is not particularly limited, such as 0 °, 90 °, + 45 °, and −45 °, and the reinforcing fiber yarns have a desired orientation angle. Arranged in In addition, the state where the arrangement direction of the reinforcing fiber yarns is 0 ° indicates a direction parallel to the longitudinal direction of the biaxial stitch base material.

  What is important here is that the reinforcing fiber yarns are oriented only in two directions in the biaxial stitch base material, and the biaxial stitch base material takes a form that can cause a large shear deformation. That is, examples of other base materials that can cause a large shear deformation include bi-directional woven fabrics, and these woven fabrics change the crossing angle between the warp yarn and the weft yarn by the bi-directional force acting in the plane direction. Although shear deformation occurs, the biaxial stitch base material can similarly generate shear deformation in the present invention. However, in the present invention, the biaxial stitch base material is not subjected to shear deformation by the same mechanism as that of the two-way fabric because the warp and the weft are not interlaced. Each sheet laminated in two directions and constrained by the stitch yarn A undergoes shear deformation under appropriate restraint conditions.

  In the case of a multiaxial stitch base material (for example, a four-axis stitch base material) in which the reinforcing fibers are oriented in three or more axes, the reinforcing fibers are stretched depending on the deformation direction to significantly inhibit shear deformation, or the reinforcing fibers are This causes bending in the out-of-plane direction (generates wrinkles) and cannot exhibit sufficient moldability. On the other hand, since the multilayer base material of the present invention is formed by laminating and integrating two or more biaxial stitch base materials capable of large shear deformation as described above, it has both moldability and handleability. It can be done.

  In order to further improve the formability, the reinforcing fiber yarns constituting the biaxial stitch base are substantially orthogonal, that is, the crossing angle of the reinforcing fiber yarns is within a range of 90 ± 10 °. It is preferable to arrange so that. In that case, it becomes possible to make both the shaping limit shear deformation angle (A) and the shaping limit shear deformation angle (B), which will be described later, within the range of 45 to 80 °, and a further excellent loading. The formality can be achieved.

  In the present invention, the engagement material for integrating at least two sets of biaxial stitch base materials is not particularly limited, but stitch yarn B for sewing at least two sets of biaxial stitch base materials, or at least 2 It is preferably at least one selected from the group consisting of particles, cut fibers, woven fabrics, knitted fabrics, non-woven fabrics and meshes, which are disposed between and fixed to the sets of biaxial stitch substrates. One of them may be selected, or a plurality of types may be used. Further, the shape may be continuous or discontinuous.

  In the multilayer base material of the present invention, since at least two sets of biaxial stitch base materials are integrated by such an engaging material, the multi-layer base material is arranged in a predetermined direction by cutting like a conventional intermediate base material. Thus, a material having a desired configuration and characteristics can be obtained with one sheet. As a result, the laminating operation is greatly labor-saving, the molding cost can be reduced, and the problem that the orientation angle of the reinforcing fibers is shifted during transportation and the laminating process can be solved.

  In the present invention, a material having a melting point Tmc in the range of 80 to 200 ° C. is used as the engagement material. By using an engagement material having such a melting point and using stitch yarn A having a melting point Tma in the range of (Tmc + 10) to (Tmc + 120) ° C. The moldability can be further improved. That is, when the preform is formed, each of the biaxial stitch bases is heated and kept warm in the temperature range of Tmc to (Tma-10) ° C. The engagement material can be softened or melted while maintaining the continuity of the stitch yarn A in the material, and the plurality of integrated biaxial stitch base materials can be separated at least partially. As a result, the above-described formability of the biaxial stitch base material can be maximized while maintaining the handleability.

Then, the multilayer substrate of the present invention, since the integral multiple sets of two-axis stitch base in a plurality of kinds of engagement material, the melting point Tmc of any engagement material in the range of 80 to 200 ° C., The melting point Tma of the stitch yarn A is set within the range of (Tmd + 10) to (Tmd + 120) ° C., where Tmd is the highest melting point among these melting points Tmc. By carrying out like this, when shape | molding a preform, the engagement material which integrated two or more sets of biaxial stitch base materials is heated and heat-retained in the temperature range of Tmd- (Tma-10) degree C, and each 2 The engagement material can be softened or melted while maintaining the continuity of the stitch yarn A on the axial stitch base material, and the plural sets of integrated biaxial stitch base materials can be separated at least partially. As a result, the above-described formability of the biaxial stitch base material can be maximized while maintaining the handleability.

  Here, if Tmc is less than 80 ° C., the type of engagement material to be used is limited, and there is a possibility of losing the integration effect as described above especially in storage and use in summer, and there is a limitation in handling. I will receive it. On the other hand, when Tmc exceeds 200 ° C., it is necessary to increase the temperature when the engaging material is melted, the time required for temperature increase and decrease becomes longer, the molding efficiency of the preform decreases, and the molding cost also increases. Become. Further, in molding a large molded body, it is difficult to control the temperature uniformly, and it is difficult to secure the molding space itself. Tmc is preferably in the range of 100 to 180 ° C, more preferably 120 to 160 ° C.

Further, the melting point Tma of the stitch yarn A is in (Tmd + 10) ° C. less than, excessively close to the melting point Tmd engagement material, even stitch yarn A when attempting to melt only engagement material softens May be cut off. When the stitch yarn A is cut, it becomes difficult to maintain the form as the biaxial stitch base material, and a gap is likely to be generated between the reinforcing fiber yarns in the obtained preform. On the other hand, when the melting point Tma of the stitch yarn A exceeds ( Tmd + 120) ° C., the time required for raising and lowering the temperature of the engagement material becomes longer, and the preform molding efficiency is lowered. In addition to this, the molding cost is increased, and particularly in the molding of a large molded body, it is difficult to control the temperature atmosphere, and it is difficult to secure a molding space. That is, the melting point Tma of the stitch yarn A is no problem in use as long as the temperature difference against the Tmd + 10 ° C., even beyond the opposite (Tmd + 120) ℃ only works against from the above description.

  In addition, the said melting | fusing point refers to the value measured by the temperature increase rate of 20 degrees C / min in the absolutely dry state according to JISK7121 (1987) using DSC (differential scanning calorimeter). In addition, about what does not show melting | fusing point (for example, amorphous polymer), glass transition temperature +100 degreeC obtained by measuring similarly is considered as melting | fusing point.

  The stitch yarn A used in the present invention is not particularly limited as long as the melting point Tma is within the above temperature range. Examples of the type thereof include polyester, polyamide, polyethylene, vinyl alcohol, polyphenylene sulfide, polyaramid, and compositions thereof. You can choose from etc. Of these, polyester and polyamide are preferred.

  The engagement material is not particularly limited as long as the melting point Tmc is within the above temperature range, but the stitch yarn B needs to be in the form of a fiber, and as a type thereof, for example, copolymer polyester, copolymer polyamide, copolymer Polyolefins, their compositions, etc. can be used. On the other hand, as the fixing material disposed between the biaxial stitch base materials, since there is no limitation on the form, a wider composition than the stitch yarn B can be selected. In addition to those described for the stitch yarn B, for example, thermosetting resins such as epoxy, phenol, vinyl ester, unsaturated polyester, thermosetting resins and polyvinyl formal, polycarbonate, polyphenylene ether, polyether sulfone, polyether imide, etc. A composition such as a thermoplastic resin can be used.

  The form of the stitch yarn A and stitch yarn B may be either a filament or a spun yarn, but is preferably a multifilament yarn in order to obtain the smoothness of the substrate surface. This is because, in the case of multifilament yarn, by pressing the preform at the time of shaping or forming, the arrangement position of the filaments moves, and the thickness of the multifilament yarn can be reduced.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic perspective view for explaining an embodiment of the multilayer substrate of the present invention.

  FIG. 2 is a schematic cross-sectional view illustrating an embodiment of the multilayer base material of the present invention.

  The multilayer base material 1 shown in FIGS. 1 and 2 includes a first sheet 2 and a second sheet 4 in which a large number of reinforcing fiber yarns 3 and 5 are arrayed and stitched together with stitch yarn A6 (chain stitch). The third sheet 8 and the fourth sheet 10 in which a large number of reinforcing fiber yarns 9 and 11 are similarly arranged on the biaxial stitch base material 7) are stitched together with another stitch yarn A6. The biaxial stitch base material 12 integrated (an irregular tricot knitting) is laminated | stacked and comprised.

  The first sheet 2 has a plurality of reinforcing fiber yarns 3 arranged in parallel, and is arranged so that the reinforcing fiber yarns 3 are oriented in the −45 ° direction with respect to the longitudinal direction 13 of the substrate. ing. Similarly, the second sheet 4 has a large number of reinforcing fiber yarns 5 arranged in parallel, and is arranged so that the reinforcing fiber yarns 5 are oriented in the + 45 ° direction with respect to the longitudinal direction 13 of the substrate. Has been. The third sheet 8 has a large number of reinforcing fiber yarns 9 arranged in parallel, and is arranged so that the reinforcing fiber yarns 9 are oriented in the + 90 ° direction with respect to the longitudinal direction 13 of the substrate. Yes. The fourth sheet 10 has a large number of reinforcing fiber yarns 11 arranged in parallel, and is arranged so that the reinforcing fiber yarns 11 are oriented in the 0 ° direction with respect to the longitudinal direction 13 of the substrate. Yes.

  The multi-layer base material according to the present invention may be such that two sets of biaxial stitch base materials are integrated with an engaging material (not shown), and such two sets of biaxial stitch base materials. Units made of base materials may be further laminated and integrated with an engaging material (not shown). Further, the number of reinforcing fiber yarns constituting each biaxial stitch base material may be two or more as long as the reinforcing fiber yarns are arranged in two directions.

  Integration of the biaxial stitch base material using the engagement material is performed, for example, by heating a laminated body in which the engagement material is disposed between the biaxial stitch base materials in a temperature atmosphere of the melting point Tmc of the engagement material. There is a method of fusing. As a method of arranging the engaging material between the biaxial stitch base materials, a biaxial stitch base material in which the engaging material is arranged on at least one surface in advance is used, or the biaxial stitch base material is laminated at the time of lamination. For example, a method of applying an engaging material between them.

  The engagement material is not particularly limited as long as it has a function of integrating the biaxial stitch base materials, and may be particles, cut fibers, woven fabrics, knitted fabrics, nonwoven fabrics, meshes, etc. as described above. That's fine. In some cases, since these engagement materials perform a function of improving impact resistance, it is also preferable to dispose a high-toughness engagement material between the biaxial stitch substrates. It can contribute to energy absorption and crack prevention. That is, when the engagement material adheres to at least one surface of the base material, the above functions can be exhibited and impact resistance can be improved. Furthermore, the engagement material of the above form also functions to form a flow path for the later-described matrix resin to flow, and can improve the impregnation property.

  Moreover, you may integrate with the stitch thread | yarn B which sews a biaxial stitch base material other than the fixed material arrange | positioned between the above biaxial stitch base materials. Specifically, the stitch yarn B is used and the biaxial stitch base materials are stitched together with a knitting machine, a sewing machine, or a sewing needle. Examples of the knitting structure of the stitch yarn B include a chain knitting, a 1/1 tricot knitting, or an irregular 1/1 tricot knitting in which a chain knitting and a 1/1 tricot knitting are combined. There is a feature that the strength of restraint of each unit can be freely operated by optimizing the knitting structure.

  The biaxial stitch base material constituting the multilayer base material of the present invention will be described in more detail with reference to the drawings.

  FIG. 3 is a schematic plan view illustrating an embodiment of the biaxial stitch base material of the present invention. As shown in FIG. 3, the biaxial stitch base 12 is arranged so that the first sheet has a large number of reinforcing fiber yarns 9 arranged in parallel with the longitudinal direction 13 in the 90 ° direction on the lower surface side. Next, the second sheet is stitched and integrated with each other by stitch yarn A6 in a state where a plurality of reinforcing fiber yarns 11 are laminated and arranged so as to be arranged in the 0 ° direction. In FIG. 3, the stitch yarn A6 is knitted with an irregular 1/1 tricot knitting.

  Here, it is preferable that the reinforcing fiber yarn 9 and the reinforcing fiber yarn 11 are substantially orthogonal, that is, the crossing angle 14 is within a range of 90 ± 10 °. If the crossing angle 14 is outside the range of 90 ± 10 °, the anisotropy is large, and the formability varies greatly depending on the direction of deformation. In the case of sizing and local deep squeezing, it is not preferable because the amount of reinforcing fibers is remarkably biased. More preferably, the crossing angle 14 between the reinforcing fiber yarns 9 and 11 is 90 °.

  Further, the biaxial stitch base material constituting the multilayer base material of the present invention has a forming limit shear deformation angle (A) in the ± 45 ° direction when one direction of the arranged reinforcing fiber yarns is 0 °, and The shaping limit shear deformation angle (B) in the ± 45 ° direction when the other direction of the arranged reinforcing fiber yarns is 0 ° is preferably in the range of 45 to 80 °. The shaping limit shear deformation angle is the base point of shaping of the base material that cannot be swallowed in-plane if it is further deformed, and is the maximum at which no wrinkles occur under no tension. If the biaxial stitch base material in which both of the shaping limit shear deformation angles (A) and (B) are in the range of 45 to 80 ° is used, it is more than a general multiaxial stitch base material. For example, when forming into a shape having a quadratic curved surface, it is difficult to generate wrinkles or to generate a gap between reinforcing fiber yarns.

  Conventionally, a picture frame method or a bias extension method is used as a method for quantifying the shear deformability of the biaxial base material. However, these measure the resistance when the base material undergoes shear deformation, that is, the shear rigidity of the base material, and indicate whether or not the fabric base material is simply placed on the mold and fits the mold. Although it can be said that it is a parameter, the shaping is actually carried out by pushing by hand or applying a very large force to the base material with a press or the like, so it is difficult to say that it is appropriate as a parameter representing the formability. On the other hand, in the present invention, the shaping limit shear deformation angle as described above is used. That is, the present invention finds an index of the shaping limit shear deformation angle, and further, the shaping limit shear deformation angle (A) in the ± 45 ° direction when one direction of the reinforcing fiber yarn is 0 °, A biaxial stitch base material in which the forming limit shear deformation angle (B) in the direction of ± 45 ° when the other direction of the arranged reinforcing fiber yarns is 0 ° is within a range of 45 to 80 °. If so, the formability is much better than general multi-axis stitch base material, for example, when forming into a shape having a quadratic curved surface, wrinkles are generated or gaps are formed between the reinforcing fiber yarns. It was found that it is difficult to occur.

  The shaping limit shear deformation angle is obtained as follows. First, the reinforcing fiber yarns are arranged in the 45 ° direction and the −45 ° direction with respect to the long side direction, and the ratio L / W of the short side length W to the long side length L is 3. Cut out a rectangular specimen. Next, the short side of the test piece is fixed and a tensile test of the test piece is performed in the long side direction to obtain the maximum tensile load. Furthermore, after applying a tensile load equivalent to 20% of the maximum tensile load to a test piece of the same level under the same test conditions, the load is released and the length W of the line connecting the midpoints of the two opposing long sides is connected. 'Is measured, and the shear deformation angle obtained according to Equation 1 is obtained as the shaping limit shear deformation angle φ.

  The measurement method is defined as measurement method Z, and the procedure of measurement method Z will be described in more detail.

  First, as shown in the enlarged view of FIG. 4, the reinforcing fibers are arranged in the 45 ° direction (21) and the −45 ° direction (22) when the long side direction 20 of the rectangular test piece 19 is 0 °. Adjust and cut out. At this time, the long side length L (23) is set to 300 mm, and the short piece length W (24) is set to 100 mm. The long side length L does not include the length of the grip portion, and the grip portion 40 for applying a tensile load must be appropriately added according to the size of the clamp portion.

  In addition, depending on the type of base material, it may have two-way shear deformability, in which case two shaping limit shear deformation angles are defined for the same base material. Therefore, when preparing the test piece, the test piece having the long side in the 0 ° direction and the long side in the 90 ° direction with respect to the base material in which the reinforcing fiber yarns are oriented at 45 ° and −45 °. Both of the test pieces to be prepared must be prepared (hereinafter simply referred to as a 0 ° direction test piece and a 90 ° direction test piece). That is, a test piece in which one direction of the arranged reinforcing fiber yarns is 0 ° and a test piece in which the other direction of the arranged reinforcing fiber yarns is 0 ° are prepared. From these two types of test pieces, The respective shaping limit shear deformation angles to be measured are defined as the two-direction shaping limit shear deformation angles (A) and (B) of the base material.

  When a specimen that satisfies the conditions is prepared, the maximum tensile load is measured. As shown in FIG. 4, a tensile load is applied with both short sides completely fixed. For example, a jig that clamps the grip portion of the test piece is attached to a universal testing machine, and a tensile load is applied to the test piece until the test piece breaks. The tensile speed is 10 mm / min at a constant speed for a static test. When a tensile load is applied, the shape of the test piece is deformed as shown in FIG.

  FIG. 5 shows an example of a load-displacement curve of a tensile test with respect to a 0 ° direction test piece of a biaxial stitch base material in which the reinforcing fiber yarn is carbon fiber and is integrated by an irregular tricot knitting as will be described later. A tensile test for obtaining the maximum tensile load 26 is performed at n = 5, and the average is defined as the maximum tensile load at that level.

  A tensile load 27 which is 20% of the maximum tensile load 26 thus obtained is added to a test piece of the same level prepared separately. The test conditions are the same as when the maximum tensile load 26 is acquired. When the tensile load reaches 20%, the test piece is unclamped to be in a no-tension state. For example, in the case of a base material on which the reinforcing fiber yarns are fixed in a spot manner with resin or the like, there is a fabric base material in which the fixing is released and the load is reduced after the load is greatly increased in the initial stage. The load is stopped when the load exceeds 20%. Care must be taken not to apply compressive loads when unloading tensile loads.

  After unloading, using the fact that the shear deformation angle can be calculated geometrically from the width of the test piece, the center width W ′ of the test piece, which is the length of the line connecting the midpoints of the two opposing long sides, is measured. . As shown in FIG. 7, the reinforcing fiber yarn 28 may move in units of yarn during shear deformation and the end portion of the yarn may not be continuous, and the end portion of the test piece may be jagged. Since the strip end portion was originally on the same line, the moving average was taken, the middle line 31 of the most protruding portion 29 and the recessed portion 30 of the reinforcing fiber yarn 28 was recognized as the long side end portion of the test piece, The length W ′ of the line connecting the midpoints of the long sides is measured. When measuring, since it is a condition that there is no warping or wrinkles in the measurement part, a test piece 33 loaded with 20% of the maximum tensile load is placed on a flat table 32 as shown in FIG. W'42 is measured by placing a transparent and smooth plate 34 such as a glass plate from above. Since some fabric base materials tend to recover the deformation of the reinforcing fiber yarn after a long time after the tensile test and the width W ′ becomes large, one minute after applying a tensile load of 20% of the maximum tensile load. W 'is measured. A test piece loaded with at least 20% of the maximum tensile load is measured with N number = 5, and a shaping limit shear deformation angle is obtained from an average value thereof.

  All measurement procedures are performed at room temperature (25 ° C.).

  By setting the forming limit shear deformation angle in the ± 45 ° direction to 45 ° or more, it is possible to more reliably prevent wrinkles and the like from occurring even when the mold is placed in a complicated shape. As a result, it is possible to develop a wider range of applications. In the present invention, the shaping limit shear deformation angle (A) in the ± 45 ° direction when one direction of the arranged reinforcing fiber yarns is 0 ° and the other direction of the arranged reinforcing fiber yarns. It is preferable that the forming limit shear deformation angle (B) in the ± 45 ° direction when the angle is 0 ° is 45 ° or more. When one of the shaping limit shear deformation angles is less than 45 °, the formability of the biaxial stitch base material is governed by the smaller shaping limit shear deformation angle, and the above-described effect is obtained. It may not be obtained after all. On the other hand, by setting both the same-shaped limit shear deformation angles (A) and (B) to 80 ° or less, it is easier to maintain the form of the biaxial stitch base material, and the handling property is excellent. be able to. As will be described later, the controlling factor of the shear deformation property in the biaxial stitch base material is the stitch yarn A, and the two-direction shaping limit shear deformation angles (A) and (B) are larger than 80 °. It shows that the restraint by the thread A is in a very loose state. Therefore, the biaxial stitch base material of the present invention comprises the shaping limit shear deformation angle (A) in the ± 45 ° direction when one direction of the arranged reinforcing fiber yarns is 0 °, and the arranged reinforcing fibers. Both the shaping limit shear deformation angle (B) in the ± 45 ° direction when the other direction of the yarn is 0 ° are preferably in the range of 45 to 80 °. More preferably, it is in the range of 50 to 70 °, more preferably 55 to 65 °.

  Such a biaxial stitch base material is made of, for example, a plurality of sheets in which a large number of reinforcing fiber yarns are arranged in parallel, and laminated so that the reinforcing fiber yarns are substantially perpendicular to each other. When integrating, the stitch length Sa and the gauge length Ga of the stitch yarn A can be made substantially the same, and the stitch length Sa can be obtained within a range of 3 to 50 mm.

  That is, the stitch length Sa (15) and the gauge length Ga (16) shown in FIG. 3 are important parameters that affect the formability and handleability of the biaxial stitch base material. In the case of a biaxial fabric, the shear deformation characteristic of the material is governed by the spacing between the reinforcing fiber yarns, but the shear deformation characteristic of the biaxial stitch base is governed by the pitch of the stitch yarn A. If it is substantially the same in the longitudinal direction and the width direction of the material, by arranging the knitting points 17 in the biaxial stitch base material at equidistant intervals, a structure with small anisotropy of shear deformability can be obtained. can do. Note that “substantially the same” refers to a range in which the above-described effects are not hindered, and specifically, stitch length / gauge length = 0.9 to 1.1.

  The stitch length Sa15 represents a stitch interval in the longitudinal direction 13 of the biaxial stitch base material, that is, corresponds to a distance per one loop. The gauge length Ga16 represents a stitch interval in the width direction of the biaxial stitch base, that is, a distance obtained by dividing the knitting width by the number of wells.

  As described above, the stitch length Sa is preferably about 3 to 50 mm. When the stitch length Sa is less than 3 mm, the reinforcement of the reinforcing fiber yarn by the stitch yarn A becomes strong, and the formability may be impaired. If the stitch length Sa exceeds 50 mm, the moldability is improved, but the handling force is poor because the binding force is reduced, and the reinforcing fiber yarns meander or bend in the stitch during molding. Problems may occur. More preferably, the width is preferably about 1 to 5 times the original width of the reinforcing fiber yarns aligned when the biaxial stitch base material is manufactured, and in terms of the stitch length Sa, the range is 4 to 20 mm. More preferably, it is in the range of 5 to 15 mm, particularly preferably 6 to 10 mm.

  Conventionally, when the base material used for FRP production is a biaxial stitch base material, the stitch length Sa of the stitch yarn A and the gauge length Ga are substantially different, and the stitch length Sa is generally different. The shape limit shear deformation angle was about 30 to 45 ° even in the case of a small woven fabric whose shape limit shear deformation angle was much less than 45 ° and was said to have the highest shapeability. .

  The biaxial stitch base as described above can also be obtained by increasing the length of the stitch yarn A per loop and loosening the tension of the stitch yarn A. By giving an appropriate loop length, the formability can be improved without deteriorating the handleability. At this time, for example, by applying the stitch yarn A made of a material having a large stretchability, the formability can be further improved. From this viewpoint, the stitch yarn A is preferably spandex (polyurethane elastic fiber), polyamide or polyester processed yarn.

  Furthermore, in the present invention, it is more preferable that the ratio of the shaping limit shear deformation angles (A) and (B) is in the range of 1 to 1.2. Here, the ratio obtained by dividing the larger shaping limit shear deformation angle by the smaller shaping limit shear deformation angle is used as the ratio. When the ratio between the two types of shaping limit shear deformation angles exceeds 1.2, the shear deformability anisotropy becomes strong and uniform deformation may be difficult. The range of 1 to 1.1 is particularly preferable because the anisotropy of shear deformability is minimized.

  In order to set the ratio of the shaping limit shear deformation angles (A) and (B) within the range of 1 to 1.2, for example, as a knitting structure of the stitch yarn A, 1/1 tricot knitting or chain knitting and 1 / An anomalous 1/1 tricot knitting as shown in FIG. 3 combined with one tricot knitting may be selected.

  Also, in the + 45 ° / -45 ° base material integrated with the most common chain knitting, the 0 ° direction test piece in which the stitch yarn A is pulled in the chain-continuous direction and the direction in which the stitch yarn A is not contained With the 90 ° direction test piece that is pulled to the right, the former shows a very small shaping limit shear deformation angle, whereas the latter shows a very large shaping limit shear deformation angle. Therefore, the ratio of the shaping limit shear deformation angle becomes larger than 1.2. However, for example, the stitch yarn A per loop is lengthened, the stitch yarn A per loop is preferably lengthened, and the stitch yarn A made of a material having a large elasticity is applied. By inserting the insertion yarn in a direction orthogonal to the stitch direction, the ratio of the shaping limit shear deformation angles (A) and (B) can be set within a range of 1 to 1.2. That is, in the 0 ° direction test piece, when the stitch yarn A hinders the tensile deformation, the stitch yarn A length per one loop is lengthened, and preferably the stitch yarn A length per one loop is lengthened and large. By applying the stitch yarn A made of a stretchable material, the base material is more easily deformed, and the shaping limit shear deformation angle can be improved. On the other hand, in the 90 ° direction test piece, when it was deformed loosely without the hindering stitch yarn, it was inhibited by inserting the insertion yarn, and was about the same as the shaping limit shear deformation angle of the 0 ° direction test piece. Can be adjusted. Such an insertion yarn can also improve the form stability and handleability of the biaxial stitch base material. Such an insertion yarn does not need to bear substantial strength in the FRP, and the fineness of the insertion yarn is preferably 10 to 200 tex. If it is smaller than this range, the effect of improving the form stability and handling properties may not be sufficient. On the other hand, if it is larger than this range, the weight of the FRP may become too heavy.

  Furthermore, in the present invention, a configuration in which the reinforcing fiber yarns are oriented in the 0 ° direction and the 90 ° direction with respect to the longitudinal direction of the base material is preferable. In the case of such a configuration, the stitch yarn A cannot be continuously present in the direction in which shear deformation occurs (± 45 ° direction) due to the nature of the stitching device, so that the shapeability can be improved without difficulty. . For example, as shown in FIG. 3, when reinforcing fiber yarns are arranged at 0 ° and 90 ° with respect to the longitudinal direction 13 of the substrate and then integrated by an irregular 1/1 tricot, the effect of the present invention is maximized. Since it can express, it can be said that it is a preferable aspect in this invention.

  Sheets made of reinforcing fiber yarns are laminated so that the reinforcing fiber yarns are arranged in different directions on different sheets. Specifically, for example, [−45 ° / 0 ° / + 45 ° / 90 ° /...] (Where 0 ° indicates the longitudinal direction of the multilayer base material) so as to show pseudo-isotropic properties. It is preferable to stack in four or more directions.

  The multilayer base material of the present invention is a minimum unit in which a sheet composed of reinforcing fiber yarns constitutes the base material, and is formed by further laminating a biaxial stitch base material in which at least two of them are laminated and integrated. Therefore, the minimum number of laminated sheets of reinforced fiber yarns is inevitably four. And as above-mentioned, it is preferable to laminate | stack the sheet | seat which consists of a reinforced fiber thread | yarn in four or more directions so that pseudo-isotropic property may be shown, Therefore, it is preferable to laminate | stack four or more sheets. On the other hand, if the number of stacked layers exceeds 24, in addition to manufacturing problems such as deformation or breakage of needles during stitching, the time required for heating and cooling when fixing materials are melted increases. There arises a problem that the production efficiency is lowered. Furthermore, the frictional resistance between the sheets increases, and the influence on moldability such as wrinkles and meandering of reinforcing fiber yarns can be considered. Therefore, in the multilayer base material of the present invention, the number of sheets composed of reinforcing fiber yarns is more preferably in the range of 4 to 24, and still more preferably in the range of 8 to 16 layers.

  Furthermore, it is preferable that the sheet | seat which consists of a reinforced fiber thread is laminated | stacked so that the orientation direction of a reinforced fiber thread may become mirror surface symmetry in the multilayer base material of this invention. With such a configuration, it is possible to prevent the occurrence of warpage due to the interlayer stress generated when the FRP is molded.

  The multilayer base material of the present invention as described above exhibits its effect particularly when forming a preform. That is, not only the shape of the flat surface and the primary curved surface, but also the effect is exhibited particularly when molding into a preform having a shape having a secondary curved surface. A quadric surface indicates a shape such as a hemisphere, for example. Conventional multi-layered base materials using multi-axis stitch base materials have had wrinkles and gaps when forming into a shape of a quadratic curved surface having a radius of curvature of 300 mm or less, for example, and forming was difficult. However, since the multilayer base material of the present invention has the above-described configuration, it can be shaped even with a secondary curved surface having a small radius of curvature while preventing generation of wrinkles and gaps, and a good quality preform can be obtained. Can do.

  In preform manufacture, when the engagement material which unites biaxial stitch base materials is cut at least partially, maintaining the continuous state of the stitch thread | yarn A in a biaxial stitch base material, multiple sets of 2 The shaft stitch base materials can be shear-deformed independently of each other, can reliably follow the curved shape of the multi-layer base material, and can obtain a good quality preform. .

The preform manufacturing method described above is performed through the steps described below .
(B) Insulation step for keeping the multilayer substrate in a temperature atmosphere of Tmd to (Tma-10) ° C. (b) Next, the multilayer substrate is pressed at a temperature of 0 to (Tmd-10) ° C. Forming step of forming into a shape having a next curved surface In the above step, one or more multilayer base materials are arranged in advance. There is no limitation on the temperature atmosphere in the arrangement of the multilayer base material, and it is generally carried out within a range of 25 ± 15 ° C. particularly when the arrangement is performed manually. In order to further increase the productivity of the preform, the preform is performed in the same temperature atmosphere as in the heat-retaining step (a). That is, it is preferable to continuously perform the arrangement of the multilayer base material and the heat-retaining step (A), and the preform manufacturing time can be further shortened by continuously performing the arrangement.

Next, regarding the heat-retaining step (A), in this step, the multilayer base material is kept warm in a temperature atmosphere of T md to (Tma-10). That is, the engagement material is softened or melted while maintaining the continuity of the stitch yarn A by keeping the engagement material at a temperature equal to or higher than T md and lower than Tma. As a result, the shear deformability of the biaxial stitch base material can be maximized in the subsequent forming step, and a preform having a shape having a quadric surface can be manufactured. If the temperature in this step (I) is too high, the stitch yarn A is melted and the integrity as a biaxial stitch base material cannot be maintained. The temperature in this step (A) is more preferably in the range of ( Tmd + 10) to (Tma-20) ° C.

And about the shaping process of (b), in this process, the multilayer base material in which the engaging material is melted or softened is pressed at a temperature of 0 to (Tmd-10) ° C. to form a quadratic curved surface. Mold to the shape you have. By performing the molding under such temperature conditions, it is possible to promote the solidifying action of the engaging material and to suppress the preform from springing back to the original shape. More preferably, in the range of 2 0~ (Tmd-30) ℃ .

(Example 1 [Reference Example] )
A biaxial stitch base material in which the reinforcing fiber yarns were arranged so as to be −45 ° / 0 ° in order from the upper layer with respect to the longitudinal direction of the base material and stitched together with the stitch yarn A was produced. Similarly, biaxial stitch base materials in which reinforcing fiber yarns were arranged so as to be + 45 ° / 90 °, 90 ° / + 45 °, and 0 ° / −45 ° were prepared. As the reinforcing fiber yarn, a PAN-based carbon fiber yarn (total fineness: 800 tex) having a tensile strength of 4,900 MPa, a tensile elastic modulus of 230 GPa, and a filament number of 12,000 is used as the stitch yarn A. Used a 56 dtex polyester yarn composed of 24 filaments having a melting point Tma of 260 ° C. The knitting structure was a 1 × 1 irregular tricot knitting having a stitch length of 2.3 mm and a gauge length of 5 mm. Moreover, the fabric weight of each sheet | seat of the reinforced fiber yarn which comprises a biaxial stitch base material was 150 g / m < ² >.

Next, these two types of biaxial stitch base materials are (−45 ° / 0 °) / (+ 45 ° / 90 °) / (90 ° / + 45 °) / (0 ° / -45 °), and then stitched together with stitch yarn B to produce a multilayer substrate. As the stitch yarn B, a 56 dtex copolymer nylon yarn composed of five filaments having a melting point Tmb of 135 ° C. was used, and stitching was performed with a 1 × 1 irregular tricot knitting having a stitch length of 5 mm and a gauge length of 5 mm.
(Example 2)
A biaxial stitch base material in which the reinforcing fiber yarns were arranged so as to be −45 ° / 0 ° in order from the upper layer with respect to the longitudinal direction of the base material and stitched together with the stitch yarn A was produced. Similarly, biaxial stitch base materials in which reinforcing fiber yarns were arranged so as to be + 45 ° / 90 °, 90 ° / + 45 °, and 0 ° / −45 ° were prepared. As the reinforcing fiber yarn, a PAN-based carbon fiber yarn (total fineness: 800 tex) having a tensile strength of 4,900 MPa, a tensile elastic modulus of 230 GPa, and a filament number of 12,000 is used as the stitch yarn A. Used a 56 dtex polyester yarn composed of 24 filaments having a melting point Tma of 260 ° C., and the knitting structure was a 1 × 1 irregular tricot knitting having a stitch length of 2.3 mm and a gauge length of 5 mm. Moreover, the fabric weight of each sheet | seat of the reinforced fiber yarn which comprises a biaxial stitch base material was 150 g / m < ² >.

Next, these two types of biaxial stitch base materials are (−45 ° / 0 °) / (+ 45 ° / 90 °) / (90 ° / + 45 °) / (0 ° / -45 °). At this time, the non-woven fabric was placed between the layers of (+ 45 ° / 90 °) / (90 ° / + 45 °), (−45 ° / 0 °) / (+ 45 ° / 90 °), (90 ° / + 45 °) / ( (0 ° / −45 °) between the resin particles as engaging materials, and the laminate was melt bonded at 200 ° C. with a far infrared heater to obtain a multilayer substrate. A copolymer nylon nonwoven fabric having a melting point of 135 ° C. and a basis weight of 10 g / m ² is used as the nonwoven fabric, and a crystalline polyester having a melting point of 143 ° C. and an average particle diameter D _{50 of} 98 μm is used as the resin particles at a basis weight of 14 g / m ^2. It sprayed so that it might become.
(Example 3 [Reference Example] )
Four biaxial stitch base materials in which the reinforcing fiber yarns were arranged so as to be 0 ° / 90 ° in order from the upper layer with respect to the longitudinal direction of the base material and stitched together with the stitch yarn A were produced. As the reinforcing fiber yarn, a PAN-based carbon fiber yarn (total fineness: 800 tex) having a tensile strength of 4,900 MPa, a tensile elastic modulus of 230 GPa, and a filament number of 12,000 is used as the stitch yarn A. Used a 56 dtex polyester yarn composed of 24 filaments having a melting point Tma of 260 ° C. The knitting structure was a 1 × 1 irregular tricot knitting having a stitch length of 2.3 mm and a gauge length of 5 mm. Moreover, the fabric weight of each sheet | seat of the reinforced fiber yarn which comprises a biaxial stitch base material was 150 g / m < ² >.

Next, these two biaxial stitch base materials are (−45 ° / + 45 °) / (0 ° / 90 °) / (90 ° / 0 °) / (+ 45 ° / −45 °) in order from the upper layer. Then, a multilayer base material was produced by stacking and integrating with stitch yarn B. The stitch yarn B was a 56 dtex copolymer nylon yarn composed of 5 filaments having a melting point Tmb of 135 ° C., and a 1 × 1 irregular tricot knitting with a stitch length of 5 mm and a gauge length of 5 mm.
(Comparative Example 1)
The reinforcing fiber yarns are −45 ° / 0 ° / + 45 ° / 90 ° / 90 ° / + 45 ° / 0 ° / −45 ° (in order from the upper layer) in order from the upper layer with respect to the longitudinal direction of the base material. A multi-axis stitch base material that was aligned and stitched together with stitch yarn A was produced. As the reinforcing fiber yarn, a PAN-based carbon fiber yarn (total fineness: 800 tex) having a tensile strength of 4,900 MPa, a tensile elastic modulus of 230 GPa, and a filament number of 12,000 is used as the stitch yarn A. Used a 56 dtex polyester yarn composed of 24 filaments having a melting point Tma of 260 ° C. The knitting structure was a 1 × 1 irregular tricot knitting having a stitch length of 2.3 mm and a gauge length of 5 mm. Moreover, the fabric weight of each sheet | seat of the reinforced fiber yarn which comprises a multiaxial stitch base material was 150 g / m < ² >.
(Comparative Example 2)
The reinforcing fiber yarns are −45 ° / 0 ° / + 45 ° / 90 ° / 90 ° / + 45 ° / 0 ° / −45 ° (in order from the upper layer) in order from the upper layer with respect to the longitudinal direction of the base material. A multi-axis stitch base material arranged and stitched together with stitch yarn B was produced. As the reinforcing fiber yarn, a PAN-based carbon fiber yarn (total fineness: 800 tex) having a tensile strength of 4,900 MPa, a tensile elastic modulus of 230 GPa, and a filament number of 12,000 is used as the stitch yarn B. Used was a 56 dtex copolymer nylon yarn consisting of 5 filaments with a melting point Tmb of 135 ° C. The knitting structure was a 1 × 1 irregular tricot knitting having a stitch length of 5 mm and a gauge length of 5 mm. Moreover, the fabric weight of each sheet | seat of the reinforced fiber yarn which comprises a multiaxial stitch base material was 150 g / m < ² >.

<Evaluation of moldability>
The moldability was evaluated for the obtained multilayer base materials (Examples 1, 2, 3) and multiaxial stitch base materials (Comparative Examples 1, 2). That is, as shown in FIG. 6, the multilayer base material obtained in the example and the multiaxial stitch base material obtained in the comparative example were each cut into a size of 500 mm × 500 mm to prepare a test body 44, and 500 mm A sandwich between a holding jig (upper) 45 and a holding jig (lower) 46 having a hole with a radius of 120 mm in the center of a × 500 mm plate, preheated in an oven heated to 180 ° C. for 1 hour, and then curved. The specimen 33 was shaped along a hemispherical mold 47 having a radius of 120 mm, and the moldability was evaluated from the appearance quality of the obtained preform.
<Evaluation of forming limit shear deformation angle>
About the biaxial stitch base material which comprises the multilayer base material obtained in Example 3, the measuring method Z was applied and the shaping limit shear deformation angle was measured. All test procedures were performed at room temperature (25 ° C.) and details were as follows.

  Two types of rectangular test pieces having a size of 100 mm × 340 mm (inside, gripping portions at both ends of 100 mm × 20 mm) were cut out from a fabric base material in which reinforcing fiber yarns were oriented in two directions. One type is a test piece (0 ° direction test piece) having a long side in the 0 ° direction and a short side in the 90 ° direction, with the reinforcing fiber direction being 45 ° and −45 °, and the other type is the reinforcing fiber direction. Were cut out by 10 pieces each with a test piece having a long side in the 90 ° direction and a short side in the 0 ° direction (90 ° direction test piece).

  In order to measure the maximum tensile load, the test piece was set in a universal testing machine INSTRON 5566. Both of the short sides of the rectangular test piece are completely fixed to the chuck by a grip portion provided in the longitudinal direction at 20 mm. As shown in FIG. 4, the long side length L, that is, the distance between chucks 23 is 300 mm, and the short side length W, The specimen width 24 was 100 mm. The test piece was pulled at a constant speed so that the tensile speed was 10 mm / min. The maximum tensile load was measured while comparing the relationship between the displacement output from the universal testing machine and the load. Subsequently, the same test was performed, and the 0 ° direction test piece and the 90 ° direction test piece of each base material were measured at n = 5, and the maximum tensile load was measured from the average.

  Next, 20% of the maximum tensile load was applied to the remaining five test pieces at each level by the same test. When the load reaches 20%, the grip portion of the test piece is released in the order of the lower chuck and the upper chuck, and the test piece 33 is placed on a smooth base 32 as shown in FIG. Between. In this way, the length W ′ of the line connecting the midpoints of the two opposing long sides was measured when 1 minute had elapsed after unloading. At that time, the jagged edge of the long side end recognizes the middle line 31 of the most protruding portion 29 and the retracted portion 30 of the reinforcing fiber yarn end portion 28 as the long side end portion according to the standard of FIG. Measurements were made.

  From the maximum tensile load W ′ thus measured, the shaping limit shear deformation angle θ in each direction was determined from Equation 1.

  The evaluation results are shown in Table 1.

  In Example 1, since the shear deformability of the biaxial stitch base material is anisotropic, large deformation occurred only in one direction, and some wrinkles and waviness in the thickness direction occurred around the edge of the hemisphere. However, it was able to be shaped nicely in most areas. In addition, about the shaping | molding limit shear deformation angle of a biaxial stitch base material, since the arrangement direction of the reinforced fiber yarn was not orthogonal, measurement was impossible.

  In Example 2, since the limit shear deformation angle of the biaxial stitch base material has anisotropy, a large deformation occurred only in one direction and a slight gap was generated, but there was no wrinkle or waviness in the thickness direction. I was able to mold it neatly. In addition, about the shaping | molding limit shear deformation angle of a biaxial stitch base material, since the arrangement direction of the reinforced fiber yarn was not orthogonal, measurement was impossible.

  In Example 3, there was no wrinkle or undulation in the thickness direction, and it was able to be shaped beautifully. Moreover, since there was no anisotropy in the shear deformability of the biaxial stitch base material, there was no gap. Regarding the forming limit shear deformation angle of the biaxial stitch base material, the results were 55 ° for the 0 ° direction test piece and 55 ° for the 90 ° direction test piece.

  In Comparative Example 1, since the stitch yarn A constrains each layer, the deformation is slight, the curved surface shape cannot be followed, the deformation is out of the plane, and wrinkles and waviness in the thickness direction occur. Occurred. Further, the forming limit shear deformation angle could not be measured because the reinforcing fiber yarns were oriented in multi.

  In Comparative Example 2, although it was possible to follow the curved surface shape, all of the stitch yarns B were melted, so that the restraint in the layer direction was lost and a large gap was generated in the preform. Further, the forming limit shear angle could not be measured because the reinforcing fiber yarns were oriented in multi.

  The multilayer base material of the present invention is formed by laminating a plurality of sheets in which a large number of reinforcing fiber yarns are arranged in parallel so that the reinforcing fiber yarns are oriented in two directions and stitching them together with stitch yarn A2. Since at least two sets of shaft stitch base materials are laminated and integrated with the engaging material, it is possible to shape the shape having a quadric surface while preventing wrinkles and gaps, Excellent handleability. Preforms obtained using such multilayer substrates are not only excellent in FRP productivity, but also have mechanical properties such as high strength and elastic modulus in FRP because the reinforcing fibers are oriented substantially straight. And an even better appearance quality can be achieved.

  Such multilayer substrates and preforms are suitable as FRP reinforcements for FRP types, transport equipment (automobiles, ships, aircraft, bicycles, etc.), sports equipment and structures, and other general industries. It is particularly suitable for structural members such as transportation equipment.

It is a schematic perspective view explaining one Embodiment of the multilayer base material of this invention. It is a schematic sectional drawing explaining one Embodiment of the multilayer base material of this invention. It is a schematic plan view explaining one Embodiment of the biaxial stitch base material which comprises the multilayer base material of this invention. It is a schematic diagram of the measuring method Z of a shaping limit shear deformation angle. It is an example of the load-displacement curve in the measuring method Z of a biaxial stitch base material. It is a schematic diagram which shows one process in the measuring method Z of a shaping limit shear deformation angle. It is a schematic diagram which shows one process in the measuring method Z of a shaping limit shear deformation angle. It is a schematic diagram which shows the mode of the shaping property evaluation in an Example and a comparative example.

Explanation of symbols

1 Multilayer substrate 2 First sheet 3 Reinforcing fiber yarn (-45 ° direction)
4 Second sheet 5 Reinforcing fiber yarn (+ 45 ° direction)
6 Stitch yarn A
7 Biaxial stitch base (+ 45 ° / -45 ° configuration)
8 Third sheet 9 Reinforcing fiber yarn (90 ° direction)
10 Fourth sheet 11 Reinforcing fiber yarn (0 ° direction)
12 Biaxial stitch base material (0 ° / 90 ° configuration)
13 Longitudinal direction 14 Crossing angle of reinforcing fiber yarn 15 Stitch length 16 Gauge length 17 Knitting point 18 Reinforcing fiber yarn width 19 Pre-test specimen 20 in measuring method Z Long-side direction of test piece in measuring method Z (0 ° direction) )
21 Reinforcing fiber direction of test specimen in test method Z (45 ° direction)
22 Reinforcing fiber direction (−45 ° direction) of test specimen before test in measurement method Z
23 Measurement sample Z test piece long side length L
24 Test piece Z side length W
25 Displacement length of test piece of measuring method Z 26 Maximum tensile load measured by measuring method Z 27 20% of maximum tensile load measured by measuring method Z
28 Reinforcing fiber yarn 29 The most protruding line 30 of the reinforcing fiber yarn The most indented line 31 of the reinforcing fiber yarn The middle of the most protruding line 29 of the reinforcing fiber yarn and the most indented line 30 of the reinforcing fiber yarn Line 32 Flat base 33 Test piece 34 after 20% of maximum tensile load is applied by measurement method Z Transparent and smooth plate 35 Test piece shape during test of measurement method Z 36 Site where shear deformation occurs (shaded) Part)
37 Length of the line connecting the midpoints of two opposing long sides during the test of measurement method Z 38 Direction of reinforcing fiber before tensile test of measurement method Z 39 Direction of reinforcing fiber during tensile test of measurement method Z 40 Grasp Part 41 Angle formed by reinforcing fibers in two directions of test piece before measurement method Z (90 °)
42 Width W ′ after the test of the line connecting the midpoints of the long sides of the two opposing sides of the test piece in measurement method Z
43 A line connecting the middle points of the two opposing long sides of the test piece in measurement method Z 44 Specimen 45 Upper holding jig 46 Lower pressing jig 47 Hemispherical type

Claims (9)

A multi-layer base material in which at least two sets of biaxial stitch base materials are laminated and integrated with a plurality of types of engagement materials. The biaxial stitch base material has a plurality of reinforcing fiber yarns arranged in parallel. A plurality of sheets are laminated so that the reinforcing fiber yarns are oriented in two directions and stitched with stitch yarn A, and the melting points Tmc of the plurality of types of engagement materials are all in the range of 80 to 200 ° C. In addition, the multi-layer substrate in which the melting point Tma of the stitch yarn A is in the range of (Tmd + 10) to (Tmd + 120) ° C., where Tmd is the highest melting point among the melting points Tmc of the plurality of types of engagement materials. The multilayer base material according to claim 1, wherein the plurality of sheets in the biaxial stitch base material are laminated so that the crossing angles of the reinforcing fiber yarns are substantially orthogonal. The biaxial stitch base material has a shaping limit shear deformation angle (A) in the direction of ± 45 ° when one direction of the arranged reinforcing fiber yarns is 0 °, and the other direction of the arranged reinforcing fiber yarns. The multilayer base material according to claim 2, wherein the forming limit shear deformation angle (B) in the direction of ± 45 ° with respect to 0 ° is within a range of 45 to 80 °. The stitch length S and the gauge length G of the stitch yarn A in the biaxial stitch base material are substantially the same, and the stitch length of the stitch yarn A is in the range of 3 to 50 mm . The multilayer base material in any one. The number of sheets in the biaxial stitch base is in the range of 2 to 4, the total number of sheets in the multilayer base is in the range of 4 to 24, and at least two sets of biaxial stitch bases are reinforced fiber yarns. The multilayer substrate according to any one of claims 1 to 4 , which is laminated so that the orientation directions of the mirrors are mirror-symmetrical. Particles, cut fibers, fabrics, wherein the engagement material is arranged and secured between stitch yarns B for sewing at least two sets of biaxial stitch substrates and / or at least two sets of biaxial stitch substrates The multilayer substrate according to any one of claims 1 to 5 , which is at least one selected from the group consisting of a knitted fabric, a nonwoven fabric and a mesh. A preform in which the multilayer substrate according to any one of claims 1 to 6 is shaped into a shape having a quadric surface while maintaining the continuity of the stitch yarn A. A method for manufacturing a preform, wherein the multilayer substrate according to any one of claims 1 to 6 is shaped into a predetermined shape in the following steps (a) and (b).
(B) Insulation step of keeping the multilayer substrate in a temperature atmosphere of Tmd to (Tma-10) ° C. (b) Next, the multilayer substrate is pressed at a temperature of 0 to (Tmd-10) ° C. Molding process to mold into a shape with a secondary curved surface The method for manufacturing a preform according to claim 8, wherein the engagement material is softened or melted while maintaining the continuity of the stitch yarn A in the heat retaining step (a).

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