WO2014034606A1

WO2014034606A1 - Three-dimensional fiber structure, prepreg using same and process for manufacturing three-dimensional fiber structure

Info

Publication number: WO2014034606A1
Application number: PCT/JP2013/072736
Authority: WO
Inventors: 原田　亮
Original assignee: 株式会社豊田自動織機
Priority date: 2012-08-30
Filing date: 2013-08-26
Publication date: 2014-03-06
Also published as: JP2014047432A

Abstract

This three-dimensional fiber structure (11) comprises: a laminated fiber layer (12) in which first and second fiber layers (12a, 12b) that are each composed of filaments are stacked and which exhibits at least biaxial orientation; and a binding yarn (13) which has portions that are arranged in a direction crossing the first and second fiber layers (12a, 12b) and by which the laminated fiber layer (12) is bound. A spiral yarn is used as the binding yarn (13).

Description

Three-dimensional fiber structure, prepreg using the same, and method for producing three-dimensional fiber structure

The present invention relates to a three-dimensional fiber structure, a prepreg using the same, and a method for manufacturing the three-dimensional fiber structure.

Fiber reinforced composite materials (hereinafter simply referred to as composite materials) are widely used as lightweight structural materials. There is a three-dimensional fiber structure such as a three-dimensional fabric as a reinforcing base material for a composite material. In order to be able to use the three-dimensional fiber structure as a reinforced base material for a composite material in a wide range of applications, it is necessary to provide a bent portion instead of a simple flat plate shape.

As a method for producing a three-dimensional fiber structure having a bent portion, there is a method of producing a flat three-dimensional fiber structure and shaping the bent portion in the three-dimensional fiber structure.

Further, in order to form a three-dimensional fiber structure having a shape in which a plurality of plate-like portions are bent in the connection portion, a frame corresponding to the shape of the three-dimensional fiber structure is provided, and a plurality of frames are provided on the frame. There is known a method of using a device in which the regulating members are arranged at a predetermined pitch (see Patent Document 1). In this method, a plurality of yarn layers are laminated by arranging yarns (continuous fibers) in a folded manner between the regulating members on the frame body, and after forming the laminated yarn group, the laminated yarn group is held on the frame body. In the state, the thickness direction thread is inserted.

Japanese Patent Laid-Open No. 9-137336

The elongation of constraining yarns such as thickness direction yarns and stitch yarns constituting the conventional three-dimensional fiber structure is very small. Therefore, when a bent part is formed on a flat plate-like three-dimensional fiber structure, wrinkles and distortion occur in the bent part during bending. As a result, the dimensional accuracy of the manufactured three-dimensional fiber structure having a bent portion is deteriorated, and the strength of the composite material using the three-dimensional fiber structure as a reinforcing substrate is reduced.

On the other hand, in the method of Patent Document 1, after forming a laminated yarn group using a special frame, the thickness direction yarn is inserted into the laminated yarn group, so that the lamination step and the thickness direction yarn insertion step are performed. Very cumbersome and time consuming.

The present invention has been made in view of the above-mentioned conventional problems, and its purpose is to use a flat plate-like three-dimensional fiber structure as a reinforcing substrate of a three-dimensional fiber-reinforced resin having a bent portion. However, it is providing the three-dimensional fiber structure which can manufacture a fiber reinforced resin in the state in which generation | occurrence | production of the wrinkles and distortion in a bending part was suppressed, and its manufacturing method.

In order to achieve the above object, according to the first aspect of the present invention, a fiber layer composed of continuous fibers is laminated, and a laminated fiber layer having at least biaxial orientation and a direction intersecting the fiber layer A three-dimensional fiber structure in which the laminated fiber layers are bonded by the bonding yarn, and a helical thread is used as the bonding yarn. A three-dimensional fiber structure is provided.

Here, the continuous fiber is not limited to a single fiber (monofilament) but includes a fiber bundle in which a plurality of single fibers are bundled. The spiral yarn used as the binding yarn is a core-sheath yarn in which a spiral yarn is wound so as to form a sheath covering the periphery of the core yarn, as in a so-called covering yarn. Including. The binding yarn may be configured so that the core yarn does not perform the binding function as a yarn in a state in which a fiber reinforced resin using a three-dimensional fiber structure as a reinforcing material is manufactured. For example, an example in which the core yarn is dissolved in the matrix resin constituting the fiber reinforced resin can be given.

In the three-dimensional fiber structure according to the first aspect of the present invention, since a helical thread is used as a binding thread for joining the laminated fiber layers having biaxial orientation, a flat three-dimensional fiber structure is used. When it is shaped into a three-dimensional shape having a bent portion, a three-dimensional fiber structure is formed in which the generation of wrinkles and distortion in the bent portion is prevented or suppressed. This is because the laminated fiber layer tends to shift in the direction along the interface of the fiber layer when bending the flat three-dimensional fiber structure. At that time, since the binding yarn is not linear but spiral, the binding yarn is stretched to allow the misalignment of the laminated fiber layer, and the three-dimensional structure having the bending portion in a state where generation of wrinkles and distortion in the bending portion is suppressed. A fiber structure is formed.

A configuration in which only a spiral thread is present as a binding thread is obtained by, for example, combining a laminated fiber layer with a composite thread having a core-sheath structure in which a spiral thread is wound so as to form a sheath around the core thread. Thereafter, it is formed by pulling out only the core yarn. Further, the core yarn of the core-sheath composite yarn is made of a material that can be dissolved in the matrix resin of the fiber reinforced resin, and in the fiber reinforced resin manufacturing process, the spiral yarn remains in the core-sheath composite yarn. The core yarn may be dissolved in the matrix resin.

In the first aspect of the present invention, it is desirable that the spiral thread has a spiral pitch of 100 to 1000 revolutions / m. If the pitch of the spiral is too large, even if it can be bent into a three-dimensional fiber structure having a bent portion in a state where generation of wrinkles and distortion in the bent portion is suppressed, the three-dimensional fiber structure is In a state where it is used as a reinforced base material for fiber reinforced resin, the function of the helical thread as a reinforced fiber is lowered. When the helical pitch is 100 to 1000 revolutions / m, the helical thread can reliably retain the function of the reinforcing fiber in a state where the three-dimensional fiber structure is used as a reinforcing substrate of the fiber reinforced resin. Can do.

It is desirable to further have a retaining thread for retaining the binding thread from the laminated fiber layer.

The binding yarn is preferably a yarn constituting a sheath portion of a composite yarn having a core-sheath structure including a core yarn and a sheath covering the periphery of the core yarn.

It is desirable to form a prepreg in which the three-dimensional fiber structure is impregnated with a thermosetting resin or a thermoplastic resin.

According to the second aspect of the present invention, a bonded yarn having a laminated fiber layer in which fiber layers made of continuous fibers are laminated and having at least a biaxial orientation, and a portion arranged in a direction intersecting the fiber layer. In the method of manufacturing a three-dimensional fiber structure in which the laminated fiber layer is bonded by the binding yarn, the binding yarn includes a core sheath and a sheath that covers the periphery of the core yarn. A spiral thread constituting the sheath of the composite yarn, wherein the core thread is composed of fibers that can be dissolved in a thermosetting resin, and the thread that constitutes the sheath is insoluble in the thermosetting resin. The thermosetting while being formed by a mold in a state in which the three-dimensional fiber structure is used as a reinforcing substrate and the three-dimensional fiber structure is impregnated with the uncured thermosetting resin. A method for manufacturing fiber-reinforced composites that cures functional resins is proposed. It is.

In this case, it is possible to manufacture the fiber reinforced resin in a state where generation of wrinkles and distortion in the bent portion is suppressed.

According to the present invention, even when a flat three-dimensional fiber structure is used as a reinforcing substrate of a three-dimensional fiber reinforced resin having a bent portion, generation of wrinkles and distortion in the bent portion is suppressed. Thus, a three-dimensional fiber structure capable of producing a fiber reinforced resin can be provided.

(A) is a schematic perspective view of a flat plate-like three-dimensional fiber structure, (b) is a schematic cross-sectional view showing the relationship between the laminated fiber layer and the binding yarn, (c) is a spiral binding yarn and a retaining yarn The partial schematic diagram of the state which has engaged. The schematic diagram of the three-dimensional fiber structure formed in the three-dimensional shape and having a curved surface portion. (A), (b) is a schematic diagram of the three-dimensional fiber structure of another embodiment.

Hereinafter, an embodiment embodying the present invention will be described with reference to FIGS. 1 and 2.

As shown in FIGS. 1A and 1B, a flat plate-like three-dimensional fiber structure 11 includes a laminated fiber layer 12 and a laminated fiber layer 12 arranged so that continuous fibers have at least biaxial orientation. The first and

second fiber layers

12a and 12b constituting the binding yarn 13 have a portion arranged in a direction intersecting with the first and

second fiber layers

12a and 12b. The laminated fiber layers 12 are bonded by a binding yarn 13. As the continuous fiber, for example, carbon fiber is used. The number of filaments of carbon fibers is about several hundred to several tens of thousands, and the number of fiber bundles suitable for the required performance is selected.

As shown in FIG. 1B, the laminated fiber layer 12 includes a first fiber layer 12a composed of first continuous fibers 14a having an arrangement angle of 0 ° and a second fiber comprising second continuous fibers 14b having an arrangement angle of 90 °. And the layer 12b. The first continuous fibers 14a having an arrangement angle of 0 ° extend so as to be orthogonal to the paper surface shown in FIG. 1B, and the second continuous fibers 14b having an orientation angle of 90 ° are orthogonal to the first continuous fibers 14b. The plurality of first fiber layers 12a and the plurality of second fiber layers 12b are alternately laminated to form a biaxially oriented laminated fiber layer 12.

The binding yarn 13 is inserted in a loop shape from the other outer surface (upper surface in FIG. 1) so as to be folded back at one outer surface (lower surface in FIG. 1) of the laminated fiber layer 12. Retaining yarns (ear yarns) 15 arranged in a direction orthogonal to the arrangement direction of the binding yarns 13 are inserted into the loop portion protruding from the lower surface of the laminated fiber layer 12, and the connecting yarns 13 are formed by the retaining yarns 15. Has been secured. Therefore, the first and second fiber layers 12 a and 12 b of the laminated fiber layer 12 are bonded together by the joint yarn 13 and the retaining yarn 15.

As shown in FIG. 1 (c), a spiral thread is used as the binding thread 13. When the laminated fiber layers 12 are bonded by the spiral bonding yarn 13, for example, a covering yarn (composite yarn) having a core-sheath structure is used. In that case, after the laminated fiber layer 12 is bonded with the covering yarn and the retaining yarn 15, only the core yarn of the covering yarn is pulled out, and the sheath yarn remains as the bonded yarn 13. As the covering yarn, for example, the core yarn is a general synthetic yarn, the sheath portion is made of glass fiber, the core yarn is a general synthetic yarn, the sheath portion is a high-strength and high-modulus fiber (for example, And aramid fibers).

The spiral pitch of the spiral yarns constituting the binding yarn 13 has an appropriate value range depending on the thickness of the three-dimensional fiber structure 11, the fiber volume content (Vf), the radius of curvature of the bent portion, the bending angle, and the like. Since they are different, a preliminary test is performed in advance to set an appropriate value. The helical pitch of the binding yarn 13 is moved along the adjacent fiber layers when the bending portion is formed in the flat three-dimensional fiber structure 11 along with the bending process. It is set to a value that is allowed to do. The helical pitch of the helical yarn constituting the binding yarn 13 is preferably 100 to 1000 revolutions / m, and more preferably 100 to 600 revolutions / m. Except for FIG. 1C, the illustration of the binding yarn 13 in a spiral shape is omitted.

The flat plate-like three-dimensional fiber structure 11 configured as described above is processed into a three-dimensional three-dimensional fiber structure 11 having a curved surface portion by bending, and then used as a reinforced base material for fiber reinforced resin. Is done. The bending of the flat three-dimensional fiber structure 11 is performed, for example, by gripping the three-dimensional fiber structure 11 in at least two places by a clamping device having a mold surface of a predetermined shape, and then holding the three-dimensional fiber structure 11. Is pressed with a presser having a pressing surface of a predetermined shape between the gripped portions. At this time, at least one clamping device is moved so as to reduce the interval between the gripping portions of the three-dimensional fiber structure 11 so that unnecessary force is not applied to the three-dimensional fiber structure 11. Then, the three-dimensional fiber structure is deformed so as to follow the pressing surface of the presser, and is pressed by the pressing surface of the presser and the mold surface of the clamping device, and shaping is performed. This bending method is basically the same as the method disclosed in, for example, Japanese Patent Application Laid-Open No. 2007-1046.

When the three-dimensional fiber structure 11 is pressed by the presser, the first and second fiber layers 12a and 12b constituting the three-dimensional fiber structure 11 are arranged on the boundary surfaces of the first and second fiber layers 12a and 12b. A force is applied to move them along each other. However, since the binding yarn 13 that joins the laminated fiber layers 12 is formed in a spiral shape, the binding yarn 13 follows the mutual movement of the first and second fiber layers 12a and 12b, unlike the case where the binding yarn 13 is linear. As the binding yarn 13 extends, the first and second fiber layers 12a and 12b move smoothly, and the generation of wrinkles and distortion at the bent portion is prevented or suppressed. As a result, a three-dimensional three-dimensional fiber structure 11 in which wrinkles and distortions in the bent portion are suppressed is obtained. FIG. 2 shows a three-dimensional fiber structure 11 having a substantially inverted U-shaped cross section. The three-dimensional fiber structure 11 has four bent portions 16, but these bent portions 16 are free from wrinkles and distortion.

The obtained three-dimensional fiber structure 11 having a three-dimensional shape is impregnated with a matrix resin to form a prepreg. Thereafter, the matrix resin is cured to form FRP (fiber reinforced resin) as a composite material. For the treatment of impregnating the three-dimensional fiber structure 11 with resin, for example, a resin transfer molding (RTM) method or a vacuum RTM method (VaRTM method) is employed. In the RTM method, a three-dimensional fiber structure 11 is placed in a mold, and a thermosetting resin before curing constituting the matrix resin is injected into the mold, and the thermosetting resin is used as a three-dimensional fiber. After the structure 11 is impregnated, it is cured by heating.

According to this embodiment, the following effects can be obtained.

(1) In the three-dimensional fiber structure 11, the laminated fiber layer 12 having at least biaxial orientation in which the first and second fiber layers 12a and 12b made of continuous fibers are laminated is the first and second fiber layers 12a, They are bound by a binding thread 13 having portions arranged in a direction crossing 12b. A spiral thread is used as the binding thread 13. Therefore, when the flat three-dimensional fiber structure 11 is shaped into a three-dimensional shape having the bent portion 16, the three-dimensional fiber structure 11 in which generation of wrinkles and distortion in the bent portion 16 is prevented or suppressed is obtained. It is done.

(2) The spiral pitch of the spiral thread constituting the binding thread 13 is 100 to 1000 revolutions / m. If the pitch of the spiral is too large, even if the three-dimensional fiber structure can be bent, in the state where the three-dimensional fiber structure is used as a reinforcing substrate for the fiber reinforced resin, The function as a reinforcing fiber is lowered. In this invention, since the helical pitch is 100 to 1000 revolutions / m, the helical thread ensures the function of the reinforcing fiber in a state where the three-dimensional fiber structure is used as the reinforcing substrate of the fiber reinforced resin. Can be held in.

The embodiment is not limited to the above-described embodiment, and may be embodied as follows, for example.

In the three-dimensional fiber structure 11, at least a biaxially oriented laminated fiber layer 12 in which the first and second fiber layers 12a and 12b made of continuous fibers are laminated intersects the first and second fiber layers 12a and 12b. It is only necessary that the yarns are coupled by the coupling yarns 13 having the portions arranged in the direction, and the spiral yarns are used as the coupling yarns 13. For example, in a composite yarn having a core-sheath structure in which a spiral thread is wound around a core yarn like a covering yarn, the core yarn is a bent portion of at least a flat plate-like three-dimensional fiber structure 11. What is necessary is just to be in a state where the core yarn loses its binding function as a yarn when it is shaped into a three-dimensional shape having 16 or before it is shaped into a three-dimensional shape. In this case, the sheath portion of the composite yarn functions as a spiral yarn, that is, the binding yarn 13.

The core yarn of the composite yarn having the core-sheath structure may be made of a material that can be dissolved in the matrix resin of the fiber reinforced resin. For example, when the matrix resin is a thermoplastic resin, the core yarn is constituted by a yarn made of a thermoplastic resin, and the plate-like three-dimensional fiber structure 11 is impregnated with the matrix resin in the production process of the fiber reinforced resin. After the fiber reinforced resin intermediate is configured, the fiber reinforced resin intermediate is processed into a three-dimensional fiber reinforced resin having a bent portion 16 by press molding. In this case, at the stage of the flat fiber reinforced resin intermediate, the core yarn is dissolved in the matrix resin, and when the fiber reinforced resin intermediate is press-molded, it does not function as a yarn, and the sheath of the composite yarn Since the portion functions as the binding yarn 13, generation of wrinkles and distortion in the bent portion 16 is prevented or suppressed during press molding of the fiber reinforced resin intermediate.

The core yarn of the core-sheath structure yarn may be formed of a material that can be dissolved in the thermosetting resin. In this case, since it is necessary to impregnate the flat three-dimensional fiber structure 11 with an uncured thermosetting resin, unlike the case of a thermoplastic resin, heating cannot be freely performed during the impregnation. Phenoxy resin may be used as the material for the core yarn. When the phenoxy resin is used, in the obtained fiber reinforced resin, a phase in which the phenoxy resin is mixed with the matrix resin exists around the binding yarn 13. In the fiber reinforced resin, a resin rich portion tends to exist in the vicinity of the binding yarn 13, and microcracks are easily generated in the resin rich portion. However, when phenoxy resin is mixed, phenoxy resin is flexible because it has a long molecular chain, and has excellent flexibility, and also has good adhesion because it has a hydroxyl group as a hydrophilic group and a hydrocarbon group as a hydrophobic group. In addition, the toughness of the resin-rich portion is improved and the generation of microcracks is suppressed.

The binding yarn 13 that bonds the laminated fiber layer 12 is not limited to the configuration in which the laminated fiber layer 12 is inserted into the laminated fiber layer 12 in a folded state from one surface and is prevented from being detached by the retaining yarn 15. Instead, a stitch thread is used, and a single binding thread 13 is inserted into the laminated fiber layer 12 from one side using a needle, and the needle is inserted in the other side so that the needle insertion position is changed. The laminated fiber layer 12 may be bonded by repetition.

The insertion interval or density of the binding yarn 13 may be set according to the strength required for the target composite material.

The laminated fiber layer 12 in which the first and second fiber layers 12a and 12b composed of the first and second continuous fibers 14a and 14b are laminated may be at least biaxially oriented, and the arrangement angle of the continuous fibers is 0 degree. And the combination of 90 degrees. For example, in addition to a fiber layer with an arrangement angle of 0 degrees and 90 degrees, a fiber layer composed of continuous fibers with an arrangement angle of +45 degrees and −45 degrees is provided, and a configuration with a four-axis orientation is adopted, or the arrangement angle is 0 Alternatively, a triaxially oriented configuration may be adopted, which is a combination of a continuous fiber having a degree or 90 degrees and a bias fiber bundle arranged obliquely with respect to the continuous fiber.

The laminated fiber layer 12 is not limited to a configuration in which a plurality of fiber layers configured such that continuous fibers having the same arrangement angle are positioned on a single plane, but a configuration in which a woven fabric is laminated as a fiber layer. It may be. As the woven fabric, for example, a plain woven fabric is used, but a multilayer woven fabric such as a double woven fabric, a triple woven fabric, or an air woven fabric may be laminated. In this case, the laminated fiber layer 12 can be formed in a shorter time than the laminated fiber layer 12 is formed by laminating fiber layers in which continuous fibers are arranged.

The shape of the three-dimensional fiber structure 11 having the bent portion 16 constituted by the flat plate-like three-dimensional fiber structure 11 is not limited to the configuration having the four bent portions 16 as shown in FIG. For example, as shown in FIG. 3A, a cross-sectional L-shaped configuration having one bent portion 16 or a cross-sectional crank-shaped configuration having two bent portions 16 as shown in FIG. May be.

DESCRIPTION OF SYMBOLS 11 ... Three-dimensional fiber structure, 12 ... Laminated fiber layer, 12a, 12b ... 1st and 2nd fiber layer, 13 ... Binding yarn, 14a, 14b ... 1st and 2nd continuous fiber.

Claims

A fiber layer composed of continuous fibers is laminated, and has a laminated fiber layer having at least biaxial orientation, and a binding yarn having a portion arranged in a direction intersecting the fiber layer, and the laminated fiber layer is A three-dimensional fiber structure bonded by a binding yarn, wherein a helical thread is used as the binding yarn.
The three-dimensional fiber structure according to claim 1, wherein the helical thread has a helical pitch of 100 to 1000 revolutions / m.
The three-dimensional fiber structure according to claim 1, further comprising a retaining thread for retaining the binding thread from the laminated fiber layer.
The three-dimensional fiber structure according to claim 1 or 2, wherein the binding yarn is a yarn constituting a sheath portion of a yarn having a core-sheath structure including a core yarn and a sheath covering the periphery of the core yarn. body.
A prepreg obtained by impregnating the three-dimensional fiber structure according to any one of claims 1 to 4 with a thermosetting resin or a thermoplastic resin.
A fiber layer composed of continuous fibers is laminated, and has a laminated fiber layer having at least biaxial orientation, and a binding yarn having a portion arranged in a direction intersecting the fiber layer, and the laminated fiber layer is In the method for producing a three-dimensional fiber structure bonded by a binding yarn,
The binding yarn is a helical thread that constitutes the sheath in a core-sheath yarn comprising a core yarn and a sheath covering the periphery of the core yarn,
The core yarn is composed of a fiber that can be dissolved in a thermosetting resin, and the yarn constituting the sheath portion is composed of a fiber that is insoluble in the thermosetting resin,
The three-dimensional fiber structure is used as a reinforcing substrate, and the thermosetting resin is cured while being shaped by a mold in a state where the three-dimensional fiber structure is impregnated with the uncured thermosetting resin. Manufacturing method of fiber reinforced composite material.
The method for producing a fiber-reinforced composite material according to claim 6, wherein a phenoxy resin fiber is used as the core yarn.