JP4940644B2 - Biaxial stitch substrate and preform - Google Patents

Description

  The present invention relates to a biaxial stitch base material in which 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 orthogonal to each other and integrated with stitch yarns, and the same is used. Related to the preform. More specifically, a biaxial stitch base material that is suitably used for producing a fiber reinforced resin (hereinafter referred to as FRP) with high productivity, and that is particularly excellent in formability and handleability, and a preform using the same. 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 method for producing FRP, a prepreg obtained by impregnating a matrix resin into a reinforcing fiber base in advance is used, and the prepreg is laminated so that the arrangement direction of the reinforcing fibers is shifted for each lamination (for example, pseudo isotropic lamination). There is an autoclave molding method in which a matrix resin is cured. In addition to this, in order to reduce the molding cost of FRP, there is a resin injection molding method in which a non-resin impregnated reinforcing fiber base material is laminated, a matrix resin is injected into the laminate, and cured.

  As an intermediate base material that has not been impregnated with a matrix resin, which is mainly used for resin injection molding, a woven base material has been used. However, in recent years, sheets with reinforcing fiber yarns oriented in parallel have been cross-laminated. So-called multi-axis stitch base materials integrated with stitch yarns have come to attract attention (for example, Patent Documents 1 and 2). Such multi-axis stitch base materials have high productivity of base materials because there is no need to weave reinforcing fiber yarns compared to conventional textile base materials, and the mechanical properties and surface quality are high because the reinforcing fiber yarns are non-crimped. Improvement can be expected. In addition, the fiber basis weight per sheet can be increased, and by laminating and integrating in multiple directions in advance, a unit with the desired configuration and characteristics can be obtained. There is also an advantage that an inexpensive FRP can be obtained.

However, such a multi-axis stitch base material, on the other hand, has a problem that it is inferior in formability such that wrinkles occur when it is placed along a complicated (for example, quadric surface) shaped mold, There was a problem that could not be deployed in a wide range of applications.
International Publication No. 01/63033 Pamphlet JP 2002-317371 A

  As described above, the multi-axis stitch base material is high in base material productivity and greatly saves the laminating work. However, there is a problem that it is difficult to form a complicated shape and the application is limited. Accordingly, an object of the present invention is to provide a biaxial stitch base material and a preform excellent in formability and handleability.

In order to solve this problem, the following means are adopted. That is, the present invention is characterized by the following (1) to ( 6 ).
(1) A biaxial stitch base material in which multiple sheets of reinforcing fiber yarns are arranged in parallel, laminated so that the reinforcing fiber yarns are substantially orthogonal, and integrated with stitch yarn A The stitch length Sa of the stitch yarn A and the gauge length Ga are substantially the same, and the stitch length Sa is in the range of 3 to 50 mm, and one direction of the arranged reinforcing fiber yarns is 0 °. The forming limit shear deformation angle (A) in the direction of ± 45 ° in the case of and the forming limit shear deformation angle in the direction of ± 45 ° (B) where the other direction of the arranged reinforcing fiber yarns is 0 ° ) Are both in the range of 45-80 °.
(2) knitting stitch yarn A is Ru anomalous 1/1 tricot knitting der biaxial stitched substrate according to (1).
(3) The biaxial stitch base material according to (1) above, wherein the knitting structure of the stitch yarn A is a chain knitting, and the stitch yarn is a spandex yarn .
(4) The sheet according to any one of (1) to (3), wherein the sheets are laminated so that the reinforcing fiber yarns are oriented at 0 ° or 90 ° with respect to the longitudinal direction of the biaxial stitch base material. Axial stitch base material.
( 5 ) A preform in which the biaxial stitch base material according to any one of (1) to (4) is shaped into a shape having a secondary curved surface.
( 6 ) A plurality of sets of biaxial stitch base materials, and the plurality of sets of biaxial stitch base materials are stitch yarns B for stitching the plurality of sets of biaxial stitch base materials, and / or the plurality of sets. to be positioned between the two axes stitch base material sticking, particles, cut fibers, woven, knitted, are engaged in at least one material selected from the group consisting of a nonwoven fabric and mesh, according to the above (5) Preforms.

  In the biaxial stitch base material of the present invention, a plurality of sheets in which reinforcing fiber yarns are arranged in parallel are laminated so that the reinforcing fiber yarns are substantially perpendicular to each other and integrated with stitch yarns. Furthermore, 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 is 0 °. Since the forming limit shear deformation angle (B) in the ± 45 ° direction is 45 to 80 °, it is excellent in handling, and for example, wrinkles are generated or strengthened on a shape having a quadric surface. The effect of shaping without generating a gap between the fiber yarns can be exhibited. When such a biaxial stitch base material excellent in formability is used, not only a complicated shape that could not be formed so far can be realized, but also a laminating operation can be greatly saved and an inexpensive FRP can be obtained. In such FRP, since the reinforcing fibers are oriented substantially straight (non-crimped), the FRP can exhibit not only excellent mechanical properties such as strength and elastic modulus but also excellent appearance quality.

  The biaxial stitch 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, laminated so that the reinforcing fiber yarns are orthogonal, and integrated by stitch yarn A Then, the 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 is 0 °. In each case, the shaping limit shear deformation angle (B) in the ± 45 ° direction is in the range of 45 to 80 °. In the present invention, the biaxial stitch base material only needs to be a base material on which reinforcing fiber yarns are arranged substantially only in two directions. For example, the biaxial stitch base material has two layers in two directions such as 0 ° and 90 °. In addition to the laminate, any number of laminates may be used as long as the directions of the reinforcing fiber yarns are two directions such as 0 °, 90 °, and 0 °.

  Details of the present invention will be described below.

  The present inventors examined the cause of the difficulty in shaping a multi-axis stitch base material having more than two axes into a complex shape, and it was found that the reinforcing fiber yarns stretched and prevented the deformation of the multi-axis stitch base material. all right. For example, in a multiaxial stitch base material in which reinforcing fiber yarns are oriented in 45 °, 0 °, −45 °, and 90 ° directions, the base material is placed in any direction of 45 °, 0 °, −45 °, and 90 °. Even when pulled, the reinforcing fibers are stretched and cannot be greatly deformed. In addition, the angle region (for example, the range of −45 to 0 °, the range of 0 to 45 °) where the reinforcing fiber yarns that prevent the deformation do not exist is extremely narrow, and shear deformation is difficult in the substrate surface. That is, in a base material having three or more axes, a region in which reinforcing fiber yarns are present at 60 ° or less is necessarily formed. Therefore, even if the base material is subjected to shear deformation, shear deformation is prevented and the formability is poor. The area is large.

  On the other hand, in the case of a biaxial base material in which reinforcing fiber yarns are oriented in two directions of 0 ° and 90 °, which can be applied even in a relatively complicated shape and has high formability, the direction is + 45 ° or −45 °. Since there is no reinforcing fiber that stretches when it is pulled, and the angular region (range of 0 to 90 °) where there is no reinforcing fiber yarn that prevents deformation, the substrate can be greatly deformed. That is, in the case of a biaxial base material, the reinforcing fiber yarns that inhibit shear deformation can be arranged substantially 90 ° at a time, so that the formability can be improved.

  Further discussion made it clear that shapeability was developed mainly by shear deformation in the substrate surface, and it was found that a biaxial substrate has the potential to improve the shapeability most. That is, when trying to shape the above-mentioned biaxial base material into a complex shape, the base material absorbs deformation in the base material surface so that the base material is not wrinkled, and the base material undergoes shear deformation. This is because, in a biaxial substrate, it is much easier to shear and deform than to stretch the reinforcing fiber yarn.

  As described above, a biaxial base material in which reinforcing fiber yarns are arranged so as to be substantially perpendicular to each other, and further, by grasping shear deformation within the base material surface, a clue for improving the formability can be grasped. This is one of the major features of the present invention.

  In the case of a uniaxial base material, it depends on the engagement material (for example, resin in the case of auxiliary yarn or prepreg) that connects the reinforcing fiber yarns arranged in parallel, but the engagement material is used rather than shear deformation. It is often easier to cut or stretch or wrinkle the reinforcing fiber yarn. That is, when it is shaped into a complex shape, the engaging material cannot connect the reinforcing fiber yarns, the reinforcing fiber yarns vary, and the portions where the reinforcing fiber yarns are present and the portions where they are not present Or wrinkles are generated in the reinforcing fiber yarn, and the quality of the obtained FRP may be lowered.

  Moreover, the biaxial base material arranged in two directions so that the reinforcing fiber yarns are not orthogonal to each other has anisotropy in shear deformability and is very difficult to handle.

  In the present invention, in order to provide a substrate excellent in formability and handleability, a plurality of sheets in which a large number of reinforcing fiber yarns are arranged in parallel and the reinforcing fiber yarns are substantially orthogonal to each other. The reinforcing fiber yarns are substantially perpendicular to each other, but the crossing angle of the reinforcing fiber yarns constituting a plurality of sheets is within a range of 90 ± 10 °. It means that Hereinafter, such a base material is simply referred to as a biaxial stitch base material.

  And the biaxial stitch base material of the present invention comprises the shape forming 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. The shaping limit shear deformation angle (B) in the ± 45 ° direction when the other direction of the yarn is 0 ° is in the range of 45 to 80 °. As will be described later, the shaping limit shear deformation angle is a forming limit point of the base material that cannot be swallowed in-plane when it is further deformed, and is wrinkled under no tension. The maximum shear deformation angle at which no occurs. Conventionally, a picture frame method or a bias extension method has been used as a method for quantifying the shear deformability of a biaxial substrate. However, these measure the resistance when the base material undergoes shear deformation, that is, the shear rigidity of the base material, and are parameters that indicate whether or not the fabric base material is simply placed on the mold and conforms to the mold. Although it can be said that the shaping is actually performed by pushing by hand or applying a very large force to the base material with a press machine or the like, it is difficult to say that it is appropriate as a parameter representing moldability. Therefore, 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 ± 45 ° direction is 45 to 80 ° when the other direction of the arranged reinforcing fiber yarns is 0 °. If so, the formability is far superior to that of general multi-axis stitch base materials. For example, when forming into a shape with a quadric surface, wrinkles or gaps between reinforcing fiber yarns are generated. I found it difficult to do.

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 θ .

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

  First, as shown in the enlarged view of FIG. 1, the rectangular test piece 1 is adjusted so that the reinforcing fibers are arranged in the 45 ° direction 28 and the −45 ° direction 29 when the long side direction 27 is 0 °. Cut out. At this time, the long side length 21 (L) is set to 300 mm, and the short piece length 23 (W) is set to 100 mm. The long side length L does not include the grip portion length, and the grip portion 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, in the present invention, when preparing the test piece, a test piece having a long side in the 0 ° direction with respect to the base material in which the reinforcing fiber yarns are oriented at 45 ° and −45 °, and 90 ° Both test pieces having a long side in the direction 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. 1, 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 33 is performed at n = 5, and the average is defined as the maximum tensile load at that level.

  A tensile load 34 of 20% of the maximum tensile load 33 obtained in this way is added to a test piece of the same level prepared separately. The test conditions are the same as when the maximum tensile load 33 was 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. 8, the reinforcing fiber yarn 13 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, and the intermediate line 39 of the most protruding portion 37 and the recessed portion 38 of the reinforcing fiber yarn 13 was recognized as the long side end portion of the test piece. The length W ′ of the line connecting the midpoints of both 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 9 loaded with 20% of the maximum tensile load is placed on a flat table 11 as shown in FIG. From above, a transparent and smooth plate 12 such as a glass plate is placed, and W ′ is measured. 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. The test piece loaded with at least 20% of the maximum tensile load is measured by N5, and the shaping limit shear deformation angle is obtained from the average value thereof.

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

  When the forming limit shear deformation angle in the ± 45 ° direction is less than 45 °, wrinkles and the like are likely to occur when the mold is placed in a complicated shape, and as a result, it cannot be developed for a wide 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 When the forming limit shear deformation angle (B) in the ± 45 ° direction when the angle is set to 0 ° must be 45 ° or more, either of the forming limit shear deformation angles is less than 45 ° The shape of the biaxially stitched base material is governed by the smaller shaping limit shear deformation angle. As a result, wrinkles and the like are likely to occur when the mold is placed in a complicated shape, making it suitable for a wide range of applications. Becomes a biaxial stitch base material that cannot be developed. On the other hand, when one of the two-direction same-shaped limit shear deformation angles (A) and (B) exceeds 80 °, it is difficult to maintain the form of the biaxial stitch base material and the handling property is inferior. End up. As will be described later, the controlling factor of the shear deformability in the biaxial stitch base material is the stitch yarn A, and the two-direction shaping limit shear deformation angles (A) and (B) are both greater than 80 °. This shows that the restraint by the stitch yarn A is in a very loose state. Therefore, the biaxial stitch base material of the present invention includes the shape forming 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 ° must be 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 of the present invention includes, for example, a plurality of sheets in which a large number of reinforcing fiber yarns are arranged in parallel, and are laminated so that the reinforcing fiber yarns are substantially orthogonal to each other. When integrating at A, the stitch length Sa and the gauge length Ga of the stitch yarn A are made substantially the same, and the stitch length Sa is obtained within a range of 3 to 50 mm.

  That is, the stitch length Sa and the gauge length Ga 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 in the biaxial stitch base material at equidistant intervals, a structure having a small shear deformation anisotropy is obtained. be able to. 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 Sa represents a stitch interval in the longitudinal direction of the biaxial stitch base material, that is, corresponds to a distance per one loop. The gauge length Ga 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 material of the present invention 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.

  In the present invention, the ratio between the shaping limit shear deformation angles (A) and (B) is preferably 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 the biaxial stitch base material of the present invention, 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 the knitting structure of the stitch yarn A, 1 An anomalous 1/1 tricot knitting as shown in FIG. 3 in which a 1/1 tricot knitting or a chain knitting and a 1/1 tricot knitting are combined.

  Further, in the case of a + 45 ° / −45 ° base material integrated with the most common chain knitting as shown in FIG. 2, the 0 ° direction test piece and the stitch yarn in which the stitch yarn A is pulled in the chain-continuous direction. With the 90 ° direction test piece that is pulled in the direction not containing A, 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, when the reinforcing fiber yarns are arranged at 0 ° and 90 ° with respect to the longitudinal direction of the base material indicated by the arrow 40 in FIG. 3 and then integrated by an irregular 1/1 tricot, the effect of the present invention is fully exhibited. Therefore, it can be said to be a preferable embodiment in the present invention.

  Such a biaxial stitch base material of the present invention can cope with many laminated patterns as in the case of a general woven base material, and is much easier to handle than a general multiaxial stitch base material. Therefore, it is an industrial base material with a wide range of applications.

  The type of reinforcing fiber yarn used in the present invention 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 more of these can be used in combination. Among these, carbon fibers are excellent in specific strength and specific elastic modulus and are preferably used.

  The type of stitch yarn A used in the present invention can be selected from, for example, polyester, polyamide, polyethylene, vinyl alcohol, polyphenylene sulfide, polyaramid, polyurethane, and compositions thereof. In order to maximize the shapeability, which is the greatest problem in the present invention, it is preferable that the stitch yarn A itself has a large stretchability. From this point of view, spandex (polyurethane elastic fiber), polyamide or polyester processing Yarn is preferred. The stitch yarn A may be any of monofilament yarn, multifilament yarn, processed yarn (crimped yarn, synthetic yarn, covering yarn, etc.), spun yarn, etc. In order to obtain smoothness, a multifilament yarn is preferred. In the case of a multifilament yarn, by applying pressure at the time of shaping or forming, the arrangement position of the multifilament moves, and the thickness of the multifilament yarn can be reduced. More preferred are multifilament yarn processed yarns (crimped yarn, synthetic yarn, covering yarn, etc.). By using such a processed yarn, the stitch yarn A itself has great stretchability as described above. Specifically, a processed yarn in which a low melting point fiber is covered with spandex can be used.

  As an insertion thread, copolyester, copolyamide, copolyolefin, polyester, polyamide, polyethylene, vinyl alcohol, polyphenylene sulfide, polyaramid, organic fiber made of those compositions, or carbon fiber, glass fiber, ceramic fiber, Although it can be selected from inorganic fibers such as metal fibers and mixed yarns thereof, glass fibers are preferable from the viewpoint of cost.

  The biaxial stitch base material of the present invention described above exhibits its effect when it is molded into a preform having a shape having a quadric surface as well as a flat surface and a primary surface. The quadratic curved surface refers to a shape such as a hemisphere, for example, and refers to a complex shape that is not a shape obtained by simply extruding a curve in one direction, such as a primary curved surface. When a conventional multi-axis stitch base material is used, for example, when forming into a shape of a quadratic curved surface having a curvature of 300 mm or less, wrinkles and gaps are generated, and forming is difficult. However, when forming a preform using one or a plurality of biaxial stitch base materials of the present invention, since the biaxial stitch base material has the above-mentioned characteristics, the shape of the secondary curved surface has a small curvature. However, it can be molded without wrinkles or gaps, and a preform with good quality can be obtained.

  When a preform is formed using a plurality of sets of biaxial stitch base materials, the biaxial stitch base materials are laminated, and an engaging material is arranged and integrated between the laminated biaxial stitch base materials. Is preferred. As the engaging material, it is preferable to use a fixing material as will be described later, because the biaxial stitch base material is not further damaged by the needle or the like. In addition, depending on the type of fixing material to be selected, it functions to improve impact resistance, and functions as a stopper for cracks that occur between biaxial stitch base materials (interlayers). Furthermore, it also functions to form a flow path for the matrix resin to flow, and the impregnation property can be improved.

  The form of the fixing material is preferably at least one selected from particles, cut fibers, woven fabrics, knitted fabrics, nonwoven fabrics and meshes. Among them, particles or cut fibers are excellent in formability to a preform because the fixing material is discontinuous, and the effects of the present invention can be exhibited to the maximum. Examples of the types include thermosetting resins such as epoxy, phenol, vinyl ester, unsaturated polyester, and compositions thereof, polyvinyl formal, polycarbonate, polyphenylene ether, polyether sulfone, polyether imide, and copolyester. Further, thermoplastic resins such as copolymerized polyamides, copolymerized polyolefins, and compositions thereof, compositions of thermosetting resins and thermoplastic resins, and the like can be used.

  From another viewpoint, it is also preferable to integrate a plurality of sets of biaxial stitch base materials with the stitch yarn B. When multiple sets of biaxial stitch base materials are integrated with stitch yarn, the biaxial stitch base material may be slightly damaged by the needle, but not only the handling property as a preform is greatly improved but also the matrix The flow path for the resin to flow can be reliably formed in the thickness direction, and the impregnation property can be particularly improved.

(Substrate used)
The following five types of substrates were prepared as the base material in which the reinforcing fiber yarns were arranged in two directions and were orthogonal to each other to measure the forming limit shear deformation angle.
A. Plain weave base material CO6343B (manufactured by Toray Industries, Inc.): A plain weave fabric in which 3000 yarns of carbon fiber filaments are orthogonal to two axes.
B. Plain weave base material BT70-30 (manufactured by Toray Industries, Inc.): A woven fabric in which 12,000 carbon fiber filaments are bundled in a plain weave structure perpendicular to two axes.
C. Biaxial stitch base material C: 24000 pieces of carbon fiber filaments bundled are aligned in two layers of + 45 ° / −45 °, gauge length Ga is 5 mm, stitch length Sa is 2.3 mm, and chain knitting Integrated + 45 ° / -45 ° stitch substrate. Polyester multifilament yarn was used as stitch yarn A.
D. Biaxial stitch base D: 24000 pieces of carbon fiber filaments bundled together are aligned in two layers of 0 ° / 90 °, gauge length Ga is 5 mm, stitch length Sa is 2.3 mm, irregular 1/1 0 ° / 90 ° stitch base material integrated with tricot. Polyester multifilament yarn was used as stitch yarn A.
E. Biaxial Stitch Substrate E: 24000 carbon fiber filaments bundled together are aligned in two layers of 0 ° / 90 °, gauge length Ga is 2.3 mm, stitch length Sa is 2.3 mm, irregular 1 / 0 ° / 90 ° stitch base material integrated in 1 tricot knitting. Polyester multifilament yarn was used as stitch yarn A.
F. Biaxial stitch base material F: 24000 pieces of carbon fiber filaments bundled are aligned in two layers of 0 ° / 90 °, gauge length Ga is 55 mm, stitch length Sa is 55 mm, irregular 1/1 tricot Integrated at 0 ° / 90 ° stitch substrate. Polyester multifilament yarn was used as stitch yarn A.
G. Biaxial stitch base material G: 24,000 carbon fiber filaments bundled together are aligned in two layers of 0 ° / 90 °, gauge length Ga is 3 mm, stitch length Sa is 3 mm, irregular 1/1 tricot Integrated at 0 ° / 90 ° stitch substrate. Polyester multifilament yarn was used as stitch yarn A.
H. Biaxial stitch base material H: 24,000 carbon fiber filaments bundled with two layers of 0 ° / 90 °, gauge length Ga is 5 mm, stitch length Sa is 5 mm, irregular 1/1 tricot Integrated at 0 ° / 90 ° stitch substrate. Polyester multifilament yarn was used as stitch yarn A.
I. Biaxial stitch base material I: 24000 pieces of carbon fiber filaments bundled are aligned in two layers of 0 ° / 90 °, gauge length Ga is 10 mm, stitch length Sa is 10 mm, irregular 1/1 tricot Integrated at 0 ° / 90 ° stitch substrate. Polyester multifilament yarn was used as stitch yarn A.
J. et al. Biaxial Stitch Base J: 24,000 carbon fiber filaments bundled in two layers of 0 ° / 90 °, gauge length Ga is 50 mm, stitch length Sa is 50 mm, irregular 1/1 tricot Integrated at 0 ° / 90 ° stitch substrate. Polyester multifilament yarn was used as stitch yarn A.
K. Biaxial stitch base material K: Threads with 24,000 carbon fiber filaments bundled together are arranged in two layers of + 45 ° / -45 °, integrated with chain knitting with gauge length Ga of 5 mm and stitch length Sa of 5 mm + 45 ° / −45 ° stitched substrate. Spandex was used as the stitch yarn A, and the reinforcing fibers were integrated in a substantially tension-free state, while an insertion yarn made of 45 tex (ECE225 1/2) glass fiber was arranged in the direction perpendicular to the stitch direction of the stitch yarn A. L. Biaxial stitch base material L: 24000 pieces of carbon fiber filaments bundled together are arranged in two layers of 0 ° / 45 °, gauge length Ga is 5 mm, stitch length Sa is 5 mm, irregular 1/1 tricot Integrated at 0 ° / 45 ° stitched substrate. Polyester multifilament yarn was used as stitch yarn A.
M.M. Multiaxial stitch base material M: Threads in which 24,000 carbon fiber filaments are bundled are aligned in four layers of 45 ° / 0 ° / −45 ° / 90 °, the gauge length Ga is 5 mm, and the stitch length Sa is 2. .45 ° / 0 ° / −45 ° / 90 ° stitch substrate integrated with chain stitch at 3 mm. Polyester multifilament yarn was used as stitch yarn A.
N. Unconstrained sheet N: Unconstrained sheet in which 24000 pieces of carbon fiber filaments are bundled into two layers of 0 ° / 90 ° to form a sheet (Examples 1 to 5)
The measuring method Z was applied to the G to K substrates, 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 with a grip portion provided in the longitudinal direction at 20 mm. As shown in FIG. 1, the long side length L, that is, the chuck interval 21 is 300 mm, and the short side length W, The test piece width 23 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. FIG. 6 shows a load-displacement curve of a 0 ° direction test piece of the biaxial stitch base material H.

  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 9 is placed on the smooth base 11 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 39 of the most protruding portion 37 and the retracted portion 38 of the reinforcing fiber yarn end portion 13 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 results are shown in Table 1. The biaxial stitch base G has a knitted structure in which the gauge length Ga and the stitch length Sa are equal to 3 mm, and the shaping limit shear deformation angle is 45 ° for both the 0 ° direction test piece and the 90 ° direction test piece, Isotropic shear deformation occurred. In addition, the biaxial stitch base H has the same gauge length Ga and stitch length Sa of 5 mm, and the shaping limit shear deformation angle is as large as 55 ° for both the 0 ° direction test piece and the 90 ° direction test piece. A shapeability equal to or higher than that of a plain woven fabric, which was said to be excellent in shapeability, was obtained. The biaxial stitch bases I and J have a knitted structure in which the gauge length Ga and the stitch length Sa are increased to 10 mm and 50 mm, respectively, compared with the biaxial stitch bases G and H, respectively. The shape limitability shear deformation angle was 65 ° and 79 ° for both of the 90 ° direction test pieces and the shapeability was greatly improved. However, as the gauge length Ga and the stitch length Sa are increased, the handleability tends to be slightly lowered. The biaxial stitch base material K is integrated by chain knitting, and although the base materials G to J are different in knitting structure, the 0 ° direction test piece and the 90 ° direction test piece have respective shaping limit shear deformation angles of 46. The ratio of °, 49 ° and the shaping limit shear deformation angle was 1.07, indicating a sufficiently isotropic shear deformability. In addition, each of the shaping limit shear deformation angles was 45 ° or more, and it had sufficient shaping properties, and the handleability was high due to the insertion of the insertion yarn.

(Examples 6 to 10)
As shown in FIG. 9, the biaxial stitch base materials G to K are formed on the hemispherical mold 17, and in Examples 1 to 5, the forming limit shear deformation angle is 45 ° in both the 0 ° direction and the 90 ° direction. It was confirmed that the biaxial stitch base materials G to K which were more than the above and a plain woven fabric have high shapeability.

  The diameter of the hemisphere was 200 mm, and the biaxial stitch base material 14 cut out to 500 × 500 mm was sandwiched between plates 15 and 16 with holes having a diameter of 210 mm and pressed against the hemispherical mold 17.

  As a result, any biaxial stitch substrate was shaped into the mold 17 while sliding between the plates 15 and 16. In addition, as shown in Table 2, for the biaxial stitch base materials G, H, I, and K, wrinkles and waviness in the thickness direction did not occur on the base material even after shaping, and a clean appearance could be obtained. . For the biaxial stitch base J, some fiber meandering was observed. Table 2 shows the appearance of each substrate after shaping.

(Comparative Examples 1-6)
In the same manner as in Examples 1 to 5, the forming limit shear deformation angle was measured by applying measurement method Z to the substrates A to F. The measured shaping limit shear deformation angles are summarized in Table 3. 4A) and FIG. 4B, the respective loads of the 0 ° direction test piece and the 90 ° direction test piece of the biaxial stitch base material C, and FIG. -A displacement curve is shown.

  Conventionally, the base materials A and B, which were considered to have high formability, had a shaping limit shear deformation angle of less than 45 ° in both the 0 ° direction test piece and the 90 ° direction test piece. On the other hand, as for biaxial stitch base material C, the result that the shaping limit shear deformation angle differs greatly in the 0 ° direction and the 90 ° direction was obtained. In the case of 0 ° direction, as shown in FIG. 2a), a chain stitch is applied in the tensile direction, and the stitch yarn itself is stretched to become resistance and prevent deformation, resulting in a low shaping limit shear deformation angle. It was. On the other hand, in the case of the 90 ° direction, as shown in FIG. 2 b), the chain knitting is performed perpendicular to the tensile direction, and there is nothing that hinders the deformation, so that the deformation is loose. The biaxial stitch base D has the same shaping limit shear deformation angle in the 0 ° direction and 90 ° direction, and depending on the knitting structure of the stitch yarn A, isotropic shear deformation is possible like the plain fabric. However, all had a forming limit shear deformation angle of less than 45 °. The biaxial stitch base E had the same shaping limit shear deformation angle in the 0 ° direction and the 90 ° direction, but both the stitch length and the gauge length were as small as 2.3 mm. The forming limit shear deformation angle was not so high as 33 °. Furthermore, the biaxial stitch base material F has both a stitch length and a gauge length as large as 55 mm, a large shape limit shear deformation angle of 81 ° in the 0 ° direction and 90 ° direction, and it seems that the formability is high. The handleability was very poor because the constraint by the thread was too small.

(Comparative Examples 7-15)
In the same manner as in Examples 6 to 10, the base materials A to F and the base materials L to N were formed into the hemispherical mold 17 shown in FIG. 9 to verify the formability. Table 4 summarizes the appearance of each substrate after shaping. The base fabrics A and B and the biaxial stitch bases D and E, which are plain weave base materials, were all nicely shaped in most areas, but there were some wrinkles and waviness in the thickness direction around the edge of the hemisphere. It has occurred. About biaxial stitch base material C, wrinkles generate | occur | produced on the whole surface and it was not able to shape at all. When the shape limit shear deformation angles in the two directions are different, it is assumed that the shapeability is determined at a low shape limit shear deformation angle. The biaxial stitch base material F could be shaped on the entire surface, but the fiber meandering was large and some gaps occurred. The biaxially stitched base material L was shaped nicely in almost all areas, but some wrinkles and waviness in the thickness direction occurred around the edge of the hemisphere. In addition, there was anisotropy in shear deformability and large deformation occurred only in one direction, resulting in gaps. About the multi-axis stitch base material M, wrinkles generate | occur | produced on the whole surface and it was not able to shape at all. The reason is thought to be that the reinforcing fibers are oriented in the direction that prevents shear deformation. With respect to the unconstrained sheet N, no shear deformation occurred, and there was no connection between the reinforcing fibers.

  The biaxial stitch substrate and preform according to the present invention are FRP type, FRP used in other general industries including repair and reinforcement of transportation equipment (automobile, ship, aircraft, bicycle, etc.), sports equipment and structures. It is suitably used as a reinforcing material, and particularly suitable for structural members such as transportation equipment.

It is a schematic diagram of the measuring method Z of a shaping limit shear deformation angle. It is a schematic diagram which shows the mode at the time of the shaping limit shear deformation angle measurement of the +45 degree / -45 degree base material integrated by the general chain stitch. It is a schematic diagram which shows one embodiment of the biaxial stitch base material of this invention. It is an example of the load-displacement curve in the measuring method Z of the biaxial stitch base material C used by the comparative example. It is an example of the load-displacement curve in the measuring method Z of the biaxial stitch base material D used by the comparative example. It is an example of the load-displacement curve in the measuring method Z of the biaxial stitch base material H used in the Example. 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 test of the various base materials in an Example and a comparative example.

Explanation of symbols

1 Specimen shape before test of measurement method Z 2 Specimen shape during test of measurement method Z 3 Shear deformation part (shaded part)
4 Chain stitch biaxial stitch base material 5 Chain stitch stitch yarn A
6 0 ° direction reinforced fiber yarn 7 90 ° direction reinforced fiber yarn 8 Anomalous 1/1 Tricot stitch yarn A
9 Test piece after 20% of the maximum tensile load is applied by measuring method Z 10 Test piece gripping part 11 of measuring method Z Flat base 12 Transparent and smooth plate 13 Reinforced fiber yarn 14 Base material 15 Holding jig Upper plate 16 Holding jig lower plate 17 Hemispherical shaping mold 21 Test piece long side length L of measurement method Z
22 Displacement amount of test piece of measuring method Z 23 Short side length W of test piece of measuring method Z
24 Length of the line connecting the midpoints of two opposing long sides during the test of measurement method Z 25 Reinforcement fiber direction 26 before the tensile test of measurement method Z Measurement 27 of reinforcing fiber direction during the tensile test of measurement method Z Method Z test piece long side direction (0 ° direction)
28 Reinforcing fiber direction (45 ° direction) of test specimen before measurement method Z
29 Reinforcing fiber direction (−45 ° direction) of test piece before measurement method Z
30 Angle formed by reinforcing fibers in two directions of test specimen before measurement method Z (90 °)
31 Gauge length Ga
32 Stitch length Sa
33 Maximum tensile load measured by measurement method Z 34 20% of maximum tensile load measured by measurement method Z
35 A line connecting the middle points of the two opposing long sides of the test piece in Measurement Method Z 36 A width W after the test of a line connecting the middle points of the two opposing long sides of the test piece in Measuring Method Z '
37 The most protruding line 38 of the reinforcing fiber yarn 39 The most protruding line 39 of the reinforcing fiber yarn 39 The intermediate line between the most protruding line 37 of the reinforcing fiber yarn and the most protruding line 38 of the reinforcing fiber yarn 40 Base material longitudinal direction

Claims (6)

A biaxial stitch base material obtained by laminating a plurality of sheets in which a plurality of reinforcing fiber yarns are arranged in parallel, laminated so that the reinforcing fiber yarns are substantially orthogonal, and integrated by stitch yarn A, When the stitch length Sa and the gauge length Ga of the stitch yarn A are substantially the same, the stitch length Sa is in the range of 3 to 50 mm, and one direction of the arranged reinforcing fiber yarns is 0 ° The forming limit shear deformation angle (A) in the ± 45 ° direction and the forming limit shear deformation angle (B) in the ± 45 ° direction when the other direction of the arranged reinforcing fiber yarns is 0 °. Both are biaxial stitch base materials within the range of 45-80 °. Knitting stitch yarn A is Ru irregular 1/1 tricot knitting der biaxial stitched substrate of claim 1. The biaxial stitch base material according to claim 1, wherein the knitting structure of the stitch yarn A is a chain knitting, and the stitch yarn is a spandex yarn . The biaxial stitch base material according to any one of claims 1 to 3 , wherein the sheet is laminated so that the reinforcing fiber yarns are oriented at 0 ° or 90 ° with respect to the longitudinal direction of the biaxial stitch base material. The preform by which the biaxial stitch base material in any one of Claims 1-4 was shape | molded by the shape which has a secondary curved surface. A plurality of sets of biaxial stitch substrates, and the plurality of sets of biaxial stitch substrates are stitch yarns B for sewing the plurality of sets of biaxial stitch substrates, and / or the plurality of sets of biaxial stitches. The preform according to claim 5, wherein the preform is engaged with at least one material selected from the group consisting of particles, cut fibers, woven fabrics, knitted fabrics, nonwoven fabrics and meshes, which are arranged and fixed between the stitch substrates.

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