JP2023050344A - Reinforcing fiber base material for resin injection molding - Google Patents

Abstract

To provide a reinforcing fiber base material which has good impregnation property of a matrix resin, can obtain a fiber-reinforced resin excellent in dynamic characteristics such as impact resistance, and dynamic characteristics at high temperature with good productivity, and is excellent in handleability (especially, morphological stability when a reinforcing fiber base material for resin injection molding is produced and in an FRP molding process), and a reinforcing fiber base material excellent in a reinforcing fiber volume percentage content (Vf) of an FRP molded product, a reinforcing fiber laminated body, and a method for producing a reinforcing fiber base material for resin injection molding.SOLUTION: There is provided a reinforcing fiber base material for resin injection molding in which a resin material is arranged on at least one side surface of a reinforcing fiber assembly selected from any one of [1]: reinforcing fiber yarns, [2]: a reinforcing fiber yarn group obtained by paralleling reinforcing fiber yarns, and [3]: a reinforcing fiber fabric composed of reinforcing fiber yarns, wherein the resin material is a porous resin material having a dry heat dimension change rate at 130°C of 5% or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to a reinforcing fiber base material for resin injection molding.

Fiber reinforced resin (FRP), in which reinforcing fibers are impregnated with matrix resin, has been mainly used for aviation, space, and sports applications because it satisfies required properties such as excellent mechanical properties and weight reduction. An autoclave molding method is known as a typical manufacturing method for these. In such a molding method, a prepreg obtained by pre-impregnating a group of reinforcing fiber bundles with a matrix resin is laminated on a molding die and heated and pressurized in an autoclave to mold an FRP. The use of prepreg has the advantage of obtaining FRP with extremely high reliability, but has the problem of high production costs.

On the other hand, as a molding method excellent in FRP productivity, for example, resin injection molding such as resin transfer molding (RTM) can be mentioned. In the RTM molding method, a reinforcing fiber base material composed of a group of dry reinforcing fiber bundles that are not pre-impregnated with a matrix resin is laminated in a mold, and a liquid low-viscosity matrix resin is injected. This is a molding method in which a matrix resin is impregnated and solidified to form an FRP.

Although the resin injection molding method is excellent in FRP productivity, it requires the matrix resin to have a low viscosity. There were times when I couldn't perform.

As a solution to the above, for example, as disclosed in Patent Document 1 and Patent Document 2, an intermediate layer in which a carbon fiber unidirectional layer having a specified basis weight and a thermoplastic fiber web (nonwoven fabric) having a specified thickness are combined materials are suggested. However, when these thermoplastic fiber webs are used, it is disclosed that certain mechanical properties can be exhibited. Dimensional changes may occur during the production of the base material or during the heat treatment process during FRP molding.

Japanese Patent Publication No. 2012-506499 Japanese Patent Publication No. 2008-517812

The present invention solves the problems of the prior art. Specifically, the present invention provides a fiber-reinforced resin that has good impregnability with a matrix resin, excellent mechanical properties such as impact resistance, and high-temperature mechanical properties. Not only can it be obtained well, it is also excellent in handleability (especially when manufacturing a reinforcing fiber base material for resin injection molding and morphological stability in the FRP molding process) and in the reinforcing fiber volume content (Vf) of FRP molded products. The purpose of the present invention is to provide a reinforcing fiber base material.

The present invention employs the following means in order to solve such problems. i.e.
(1) [1]: Reinforcing fiber yarn, [2]: Reinforcing fiber yarn group formed by arranging reinforcing fiber yarns in parallel, [3]: Reinforcing fiber fabric made of reinforcing fiber yarns A reinforcing fiber base material for resin injection molding in which a resin material is arranged on at least one surface of a reinforcing fiber aggregate selected from A reinforcing fiber base material for resin injection molding, characterized by being a porous resin material.
(2) The resin material is polyamide resin, polyester resin, polyphenylene sulfide resin, polyetherimide resin, polyether sulfone resin, polyvinyl formal resin, polyether ether ketone resin, polycarbonate resin, polysulfone resin, polyphenylene ether resin, polyimide resin. , polyamideimide resin and phenoxy resin, or a mixture thereof.
(3) The reinforcing fiber base material for resin injection molding according to (1) or (2), wherein the porous resin material is heat-treated at a Vicat softening temperature or higher of the resin material. .
(4) The reinforcing fiber base material for resin injection molding according to (3), wherein the Vicat softening temperature of the resin material is 70°C or higher and 200°C or lower.
(5) The reinforcing fiber base material for resin injection molding according to any one of (1) to (4), wherein the porous resin material is a long-fiber nonwoven fabric.
is.

According to the present invention, as described in detail below, it is possible to obtain a reinforcing fiber base material and a reinforcing fiber laminate that not only have excellent shape stability but also excellent resin impregnation properties during RTM molding. FRP with excellent impact resistance and high temperature mechanical properties can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing explaining one aspect|mode of the reinforcing fiber base material in this invention. 1 is a schematic side view showing one mode of a manufacturing apparatus for a reinforcing fiber base material according to the present invention; FIG. 1 is a schematic perspective view showing one aspect of a group of reinforcing fiber yarns in the present invention. FIG. 1 is a schematic perspective view showing one aspect of a unidirectional woven fabric as a reinforcing fiber aggregate in the present invention. FIG. 1 is a schematic perspective view showing one aspect of a bidirectional woven fabric as a reinforcing fiber aggregate in the present invention. FIG. 1 is a schematic perspective view showing one aspect of a stitched fabric as a reinforcing fiber aggregate in the present invention. FIG.

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

FIG. 1 is a schematic cross-sectional view explaining one aspect of the reinforcing fiber base material 11 in the present invention. The reinforcing fiber base material 11 shown in this figure is formed by bonding and integrating the porous resin material 13 on one side of the reinforcing fiber assembly 12 .

The reinforcing fiber base material 11 is a reinforcing fiber assembly 12 selected from any one of reinforcing fiber yarns, reinforcing fiber yarn groups, and reinforcing fiber fabrics composed of reinforcing fiber yarns or reinforcing fiber yarn groups. , it is important to have a porous resin material 13 on at least one side surface. By having such a porous resin material 13 present on at least one side surface, morphological stability such as the width and fiber orientation of the reinforcing fiber base material 11 is improved, and when the sheet-like reinforcing fiber base material 11 made of reinforcing fiber yarn groups is conveyed, etc. can be improved. In addition, in a laminate (preform) obtained by laminating the reinforcing fiber base material 11 or the reinforcing fiber aggregate 12 described later, the adhesion between the reinforcing fiber aggregates 12 is improved, the preform is given appropriate rigidity, and the preform is improved. It is possible to improve the handleability of the preform by improving the shape stability due to the prevention of misalignment of the reinforcing fibers during remodeling.

In addition, the porous resin material 13 arranged between the layers of the reinforcing fiber assembly 12 secures a space for flowing and diffusing the matrix resin described later to shorten the impregnation time, or is manufactured using the reinforcing fiber base material 11. It is possible to prevent cracks from occurring between the layers of the FRP molded body to be molded, and to impart excellent impact resistance (particularly, compressive strength after impact: CAI).

Such a porous resin material 13 adheres to the reinforcing fiber assembly 12 and exists at least on one side surface of the reinforcing fiber assembly 12, and exists inside the reinforcing fiber assembly 12 (permeates the reinforcing fiber threads ). Preferably, 50% by weight or more, and more preferably 70% by weight or more, is unevenly distributed on the surface of the reinforcing fiber assembly 12 for the reason described above. Further, a binder component may be included for the purpose of bonding the porous resin material 13 and the reinforcing fiber bundle assembly 12, for example, a thermoplastic resin having a softening point (melting point or glass transition temperature Tg) lower than that of the porous resin material 13. Alternatively, a thermosetting resin can be used.

The term "porous" as used herein refers to a shape in which holes are formed at least in the thickness direction on a plane. In addition, unlike the case of dispersing particles, there is connection in the plane direction, so the width stability is improved when reinforcing fiber threads are used, and the sheet-like reinforcing fiber base material 11 made of reinforcing fiber threads is conveyed. It is possible to improve the handleability in time and the morphological stability of the base material when using a group of reinforcing fiber threads or a fabric. Examples of the porous resin material 13 include nonwoven fabric, mat, net, mesh, woven fabric, knitted fabric, perforated film, and porous film. Among them, non-woven fabrics, mats, nets, meshes, woven fabrics, or knitted fabrics are preferable because they are available at low cost and have flow paths for the matrix resin and air in the planar direction, so that the above effects are highly exhibited. When the porous resin material 13 is a non-woven fabric, the form of the constituent fibers includes long fibers and short fibers, and is manufactured by a method such as meltblowing, spunbonding, airlaid, carding, papermaking, etc., but is not particularly limited. not. Although a binder component for binding fibers together may be included as a secondary component, excessive use of the binder component may adversely affect properties such as heat resistance of the FRP. In addition, the staple fiber nonwoven fabric may be applied with an oil during the spinning process, which may adversely affect the adhesion to the matrix resin. Therefore, it is preferable to use a long-fiber nonwoven fabric such as meltblown or spunbond that does not contain a binder component or oil.

The fiber diameter of the fibers constituting the nonwoven fabric is preferably 1 µm or more and less than 100 µm, more preferably 5 µm or more and less than 80 µm, and even more preferably 10 µm or more and less than 60 µm. If the fiber diameter is less than 1 μm, the resin material has a large surface area, which may hinder the flow of the resin in the resin impregnation step described later. Further, when the fiber diameter is 100 μm or more, the thickness between the reinforcing fiber base layers becomes large when the FRP is formed, and the fiber volume fraction (Vf) may decrease.

The porous resin material 13 used in the present invention preferably accounts for 1 to 20% by weight of the reinforcing fiber base material 11 . It is preferably 2 to 18% by weight, more preferably 3 to 16% by weight. By arranging the porous resin material 13 within the above range, the reinforcing fiber base material 11 is provided with dimensional stability, making it possible to obtain the reinforcing fiber base material 11 with excellent handleability. If it is less than 1% by weight, not only is the handleability of the reinforcing fiber base material 11 lowered, but also the effect of improving the mechanical properties (especially CAI) may be reduced. On the other hand, if it exceeds 20% by weight, the volume fraction of reinforcing fibers in FRP may become too low, and the heat resistance, chemical resistance and compressive strength of FRP may deteriorate.

It is important that the porous resin material 13 in the present invention has a dry heat dimensional change rate of 5% or less at 130°C. If the dry heat dimensional change rate of the porous resin material 13 at 130° C. exceeds 5%, for example, when manufacturing a reinforcing fiber base material for resin injection molding, in the bonding step between the reinforcing fiber assembly 12 and the porous resin material 13 When the heating means is selected, the heat shrinkage of the porous resin material 13 not only changes the basis weight and dimensions of the porous resin material itself, but also changes the width and thickness of the reinforcing fiber assembly 12, fiber alignment, and the like. , resulting in dimensional defects in the reinforcing fiber base material for resin injection molding. Also, when using an automated fiber placement (AFP) or automated tape layup (ATL) device during FRP molding, dimensional defects may be similarly induced. Therefore, the dry heat dimensional change rate of the porous resin material 13 at 130° C. is preferably 3% or less, more preferably 1% or less. In addition, the dry heat dimensional change rate in the present invention is measured according to JIS L1913 (2010) 6.10.3.

The porous resin material 13 in the present invention includes polyamide resin, polyester resin, polyphenylene sulfide resin, polyetherimide resin, polyether sulfone resin, polyvinyl formal resin, polyether ether ketone resin, polycarbonate resin, polysulfone resin, and polyphenylene ether resin. , a polyimide resin, a polyamideimide resin and a phenoxy resin, or a thermoplastic resin material consisting of a mixture thereof. Moreover, the porous resin material 13 in the present invention may be composed of a mixture of the thermoplastic resin material described above and a thermosetting resin material selected from unsaturated polyesters, vinyl esters, epoxies and phenols. By arranging the porous resin material 13 between the layers of the reinforcing fiber assembly 12, excellent mechanical properties of the FRP molded article manufactured using the reinforcing fiber base material 11 can be achieved. Such an FRP molded article is particularly excellent in CAI, which is compressive strength after impact is applied.

The porous resin material 13 in the present invention is preferably heat-treated at a Vicat softening temperature (hereinafter sometimes referred to as VST) or higher of the resin material. If the porous resin material 13 is not heat-treated at VST or higher, the dry heat dimensional change rate of the porous resin material 13 at 130° C. often exceeds 5%. It may induce dimensional defects in the base material and dimensional defects when using an AFP or ATL device.

Heat treatment is also called so-called heat setting processing, and specific processing methods include, for example, embossing, calendering, and the like, but are not limited to the use of a heat set tenter or hot press. As for the heating method, there are dry heat, wet heat, and the like, but any method may be selected according to the characteristics of the porous resin material 13 .

By performing such heat treatment, not only can the dimensional stability of the porous resin material 13 and the reinforcing fiber assembly 12 as described above be obtained, but also the thickness of the porous resin material 13 can be made uniform and the bulk can be suppressed. effect is also obtained. Reducing the bulk of the porous resin material 13 makes it possible to reduce the bulk of the preform in the FRP molding process, making it easier to load the preform into the mold and reducing the volume content of reinforcing fibers ( Vf) is improved.

The Vicat softening temperature (VST) of the resin material that becomes the porous resin material 13 is preferably in the range of 70° C. or more and 200° C. or less. If the VST is less than 70° C., the high-temperature mechanical properties of the FRP deteriorate, which is not preferable. Also, if the VST exceeds 200° C., the adhesiveness between the thermoplastic resin material and the thermosetting resin material is lowered, and the mechanical properties (especially CAI and ILSS) of the FRP may be lowered. Therefore, it is more preferable that the thermoplastic resin material has a Vicat softening temperature in the range of 100° C. or higher and 180° C. or lower. Here, the Vicat softening temperature (VST) in the present invention refers to the value measured by the A-50 method according to JIS K7206 (2016).

In addition, if the porous resin material 13 has a low affinity with the FRP matrix resin, separation occurs at the interface between the porous resin material 13 and the matrix resin, and the effect of improving mechanical properties cannot be obtained satisfactorily. There is Therefore, the absolute value of the solubility parameter difference between the porous resin material 13 and the matrix resin is preferably 5 or less, preferably 3 or less. The solubility parameter of the porous resin material 13 is obtained by the following formula (1). The method is described in "Osamu Fukumoto (1988) "Polyamide Resin Handbook" Nikkan Kogyo Shimbun, Ltd.".

here,
M: molecular weight ρ: density ΔH: interaction between amide groups T: temperature.

Also, the solubility parameter of the matrix resin is obtained from the value of the repeating unit of the polymer at a temperature of 25° C. determined by the method of Fedors. The method is described in F. Fedors, Polym. Eng. Sci. , 14(2), 147 (1974).

The reinforcing fiber yarns in the present invention are multifilament yarns such as glass fiber yarns, organic (aramid, PBO, PVA, PE, etc.) fiber yarns, carbon fiber (PAN-based, pitch-based, etc.) yarns. Carbon fibers are excellent in specific strength and specific modulus and hardly absorb water, so they are preferably used as reinforcing fibers for aircraft structural materials and automobiles.

The reinforcing fiber yarn used in the present invention preferably has 3,000 to 50,000 filaments, and particularly preferably 12,000 to 24,000 filaments from the viewpoint of handleability. Although the form of the reinforcing fiber yarn is not particularly limited, it is preferably a non-twisted yarn that is excellent in the stability of the width and thickness of the yarn, and more preferably a spread yarn that is excellent in fiber orientation.

Here, the reinforcing fiber base material in the present invention is [1]: reinforcing fiber yarn, [2]: reinforcing fiber yarn group formed by arranging reinforcing fiber yarns in parallel, or [3] reinforcing fiber yarn or It is important to consist of a reinforcing fiber assembly selected from any one of reinforcing fiber fabrics composed of reinforcing fiber thread groups.

First, [1]: The reinforcing fiber base material 21 made of reinforcing fiber threads is produced using the apparatus illustrated in FIG. 2, for example. Specifically, the reinforcing fiber thread 22 pulled out from the bobbin 20 is spread by the spreading unit 201, adjusted to a desired width by the width regulating roller 202, and then slit to a desired width in advance. is laminated with a porous resin material), heated by a heater 203, and pressed by a press roll 204. FIG. The fiber spreading unit 201 is composed of a vibrating roller or the like, and has a mechanism for applying vibration in the vertical and horizontal directions perpendicular to the advancing direction of the reinforcing fiber thread 22 . Further, the fiber spreading unit 201 may be provided with a heater (not shown) for softening the sizing agent adhering to the surface of the reinforcing fiber threads 22 . At this time, if the thread width of the reinforcing fiber thread 22 pulled out from the bobbin 20 is w0, the width of the reinforcing fiber thread 22 after opening is expanded to w1 (w0<w1), and then the width regulating roller 202 The width is adjusted to w2 (w1>w2). It is preferable to adjust w2 according to the basis weight required for the reinforcing fiber base material 21 . In order to improve the width accuracy of the reinforcing fiber base material 21, the press roll 204 preferably has a grooved structure.

The reinforcing fiber base material 21 produced by such an apparatus has good stability in width and basis weight, and is excellent in fiber orientation, so that it can contribute to the improvement of the mechanical properties (especially compressive strength) of FRP. Moreover, it is preferable to arrange the resin material 23 on both sides of the reinforcing fiber yarn group, because the shape stability of the reinforcing fiber substrate 21 is further improved.

Next, [2]: The reinforcing fiber base material 21 made of the group of reinforcing fiber yarns is prepared by inserting a plurality of bobbins into the apparatus illustrated in FIG. 20 and pulling out a plurality of reinforcing fiber yarns 22 while arranging them in parallel. Here, to align in parallel means to align adjacent reinforcing fiber threads 22 so as not to substantially cross or intersect each other. Preferably, two adjacent reinforcing fiber threads are separated by 100 mm. When a straight line is approximated within the range of length, the angle formed by the approximated straight line is 5° or less, preferably 2° or less. Here, approximating the reinforcing fiber thread 22 to a straight line means forming a straight line by connecting the starting point and the ending point of 100 mm. Adjacent reinforcing fiber yarns 22 may be spaced apart by a certain distance according to the basis weight of the reinforcing fiber base material 21 required, or may overlap each other. When they are spaced at a constant interval, the interval is preferably 200% or less of the width of the reinforcing fiber threads 22, and when they overlap, they may overlap 100% of the width of the reinforcing fiber threads 22. It is preferable that the group of reinforcing fiber threads pulled out while being aligned in parallel pass through a fiber opening unit so that the basis weight in the width direction is uniformly distributed. Further, the reinforcing fiber base material 21 made from such a reinforcing fiber yarn group can be slit if necessary to control the width to an arbitrary value.

[3] The reinforcing fiber fabric composed of reinforcing fiber threads or groups of reinforcing fiber threads will be described later.

For the reinforcing fiber base material 21 using the reinforcing fiber yarn 22 and the group of reinforcing fiber yarns, an automated fiber placement (AFP) or an automated tape layup (ATL) device is preferably used. Such a device is used for the purpose of reducing the waste rate of the reinforcing fiber base material 21 and automating the lamination process, but since the width and fiber orientation after placement are strictly required, the morphological stability of the reinforcing fiber base material 21 is important. Become. Here, since the porous resin material 23 used in the present invention has a porous shape, it is excellent in width stability and shape stability due to connection in the plane direction, so it can be suitably used for AFP and ATL.

Further, another aspect of the reinforcing fiber yarn group in the present invention includes a sheet-like one arranged in parallel by AFP or ATL. FIG. 3 shows one aspect of the group of reinforcing fiber yarns used in the present invention. The reinforcing fiber yarns 32 are supplied by the AFP head 300 and aligned in parallel. A reinforcing fiber base material can be obtained by placing a porous resin material (not shown) on the reinforcing fiber thread group 31 so as to be superimposed and heat-bonding them with a far-infrared heater or the like. Since the sheet-like reinforcing fiber thread group 31 aligned by AFP or ATL is not constrained in the direction crossing the fiber direction, there is a problem that the reinforcing fiber thread group 31 loses its shape during transportation. By arranging and adhering the porous resin material to such a problem, a restraining force is generated in the direction intersecting the fiber direction, and the transport problem can be solved. Further, the interval between the reinforcing fiber threads 32 when the reinforcing fiber threads 32 are aligned by AFP or ATL is preferably 0.5 to 2 mm. If the gap is less than 0.5 mm, the resin impregnation may not be sufficient during RTM molding. Further, if the interval exceeds 2 mm, when a plurality of reinforcing fiber substrates are laminated, the reinforcing fibers of the upper layer fall between the reinforcing fiber threads 32 of the lower layer, undulation in the thickness direction occurs, and mechanical properties (especially compression strength) may decrease.

Next, [3] reinforcing fiber fabrics composed of reinforcing fiber yarns or reinforcing fiber yarn groups include woven fabrics (unidirectional, bidirectional, multiaxial), knitted fabrics, braided fabrics, and unidirectionally aligned A sheet (unidirectional sheet), a multiaxial sheet obtained by stacking two or more unidirectional sheets, and the like. Such a reinforcing fiber aggregate may be formed by integrating a plurality of fibers by means of various joining means such as stitch yarn, knotted yarn, coarse cloth, resin such as binder, or the like. Unidirectional sheets, unidirectional woven fabrics, or multiaxial sheets (especially stitch-bonded sheets) are preferred, particularly when used as structural (particularly primary structural) members of transportation equipment (especially aircraft).

FIG. 4 shows a schematic perspective view showing one aspect of the unidirectional fabric 41 as the reinforcing fiber fabric used in the present invention. The reinforcing fiber yarns 42 and the warp auxiliary yarns 43 are arranged in the length direction of the unidirectional fabric 41, that is, in the warp direction, and the weft auxiliary yarns 44 thinner than the reinforcing fiber yarns 42 are arranged in the weft direction, and the warp auxiliary yarns are arranged. The yarn 43 and the auxiliary weft yarn 44 are crossed to form a unidirectional fabric having the weave structure shown in FIG. The auxiliary yarn 43 preferably has low shrinkage, and examples thereof include glass fiber yarn, aramid fiber yarn, carbon fiber yarn, etc. The fineness (weight per unit length) of the auxiliary yarn is the same as that of the reinforcing fiber. It is preferably 1/5 or less of the thread. If it exceeds 1/5, the auxiliary yarns become thick, and the reinforcing fiber yarns are crimped by the auxiliary yarns, resulting in a slight decrease in the strength of the reinforcing fibers when made into FRP. On the other hand, from the viewpoint of the shape stability and production stability of the reinforcing fiber assembly, the fineness of the auxiliary yarn is preferably 0.05% or more of the reinforcing fiber yarn. When the fineness is within the above range, the reduction in strength is minimized, and the gaps between the reinforcing fiber yarns 42 formed by the warp auxiliary yarns during molding serve as resin flow paths, which facilitates the impregnation of the matrix resin, which is preferable.

FIG. 5 shows a schematic perspective view showing one aspect of the bidirectional fabric 51 as the reinforcing fiber fabric used in the present invention. The reinforcing fiber yarns 52 are arranged in the length direction of the bidirectional fabric 51, that is, in the warp direction, the reinforcing fiber yarns 53 are arranged in the weft direction, and the warp yarns 52 and the weft yarns 53 intersect to form the weave shown in FIG. It is a bidirectional fabric with a texture.

Furthermore, FIG. 6 shows a schematic perspective view showing one aspect of a stitched fabric 61 as a reinforcing fiber fabric used in the present invention. From the lower surface of the stitch fabric 61, first, a large number of reinforcing fiber threads are arranged in parallel in a direction diagonal to the length direction a to form the +α° layer 62, and then a large number of reinforcing fibers are arranged in the width direction of the reinforcing fabric. The fiber yarns are arranged in parallel to form a 90° layer 63, then a large number of reinforcing fiber yarns are arranged in parallel in an oblique direction to form a −α° layer 64, and then in the longitudinal direction of the reinforcing fabric. A large number of reinforcing fiber threads are arranged in parallel to form a 0° layer 65, and in a state in which four layers with different arrangement directions are laminated, these four layers are sewn and integrated with a stitch thread 66. there is The stitching structure formed by the stitch thread 66 for stitching and integration includes, for example, a single chain stitch and a 1/1 tricot stitch. Materials for stitch threads can be selected from polyester resins, polyamide resins, polyethylene resins, vinyl alcohol resins, polyphenylene sulfide resins, polyaramid resins, compositions thereof, and the like. Among them, polyester resins and polyamide resins are preferable. From the viewpoint of shaping of the fabric, it is preferably spandex (polyurethane elastic fiber), polyamide resin or polyester resin textured yarn. The fineness of the stitch yarn is preferably ⅕ or less that of the reinforcing fiber yarn in order to suppress crimping of the reinforcing fiber yarn. From the viewpoint of the shape stability and manufacturing stability of the reinforcing fiber assembly, it is preferably 10 dtex or more, more preferably 30 dtex or more. Furthermore, from the viewpoint of shapeability in the preforming step, which will be described later, the stitch yarn preferably has stretchability. In FIG. 6, it seems that the assembly of the reinforcing fibers whose cross-sectional shape is elliptical is one thread, and the stitch threads 66 are arranged between the reinforcing fiber threads. The reinforcing fiber yarns are randomly inserted into the reinforcing fiber yarns, and the elliptical reinforcing fiber assembly is formed by the binding of the stitch yarns 66 .

Here, the configuration of the reinforcing fibers of the multiaxial stitched fabric 61 shown in FIG. 6 was described as a four-layer configuration of +α° layer/90° layer/−α° layer/0° layer, but it is not limited to this. do not have. For example, two layers such as 0° layer/90° layer, +α° layer/−α° layer, 0° layer/+α° layer, +α° layer/0° layer/−α° layer, +α° layer/−α Three layers consisting of ° layer / 0 ° layer, etc., and 0 ° layer / + α ° layer / 0 ° layer / - α ° layer / 90 ° layer / - α ° layer / 0 ° layer / + α ° layer / 0 ° Like a layer, it may include four directions of 0°, +α°, -α°, and 90° such that many 0° layers are included. It may also include any one of 0°, +α°, -α°, and 90°. The bias angle α° is preferably 45° from the viewpoint of laminating the stitched fabric in the longitudinal direction of the FRP and effectively performing shear reinforcement by the reinforcing fibers.

The preferred weight per layer of the reinforcing fiber base material in the present invention is in the range of 50 to 800 g/m ² . More preferably from 100 to 500 g/m ² , still more preferably from 120 to 300 g/m ² . If it is less than 50 g/m ² , the number of layers to be laminated to obtain the desired thickness of FRP increases, and molding workability may deteriorate. In addition, if the basis weight per layer is small, gaps are formed between the reinforcing fiber yarns in the layer, and the reinforcing fiber volume content Vf becomes partially uneven. Where Vf is large, the FRP becomes thick, and where the reinforcing fiber volume fraction Vf is small, the FRP becomes thin, resulting in an FRP with an uneven surface. In such a case, if the reinforcing fiber yarn is thinly spread with a vibrating roller or an air jet jet just before weaving, before integration processing with stitch yarn, and/or after processing the reinforcing fabric, the reinforcing fiber can be spread over the entire surface of the reinforcing fabric. is uniform, and FRP with a smooth surface can be obtained. On the other hand, if it exceeds 800 g/m ² , the impregnating property of the matrix resin may deteriorate.

Next, the reinforcing fiber laminate in the present invention will be explained. Prior to FRP molding, the reinforcing fiber base material in the present invention is laminated with a plurality of layers until a desired thickness is achieved to form a reinforcing fiber laminate. In the present invention, it is preferable that the reinforcing fiber laminate is integrated by heat-sealing or stitching in order to impart handleability and shape stability to the reinforcing fiber laminate.

In addition, the reinforcing fiber laminate in the present invention is obtained by imparting a three-dimensional shape to the carbon fiber laminated base material using a shaping mold, a jig, etc., according to the desired shape of the carbon fiber reinforced resin molded product. It can also be a form-locked preform. In particular, when the molding die has a three-dimensional shape, by doing so, it is possible to easily suppress the occurrence of fiber disturbance and wrinkles during mold clamping or resin injection/impregnation.

Next, the FRP of the present invention will be explained. The FRP of the present invention is obtained by impregnating the above reinforcing fiber laminate with a matrix resin. Such matrix resins are solidified (cured or polymerized) as necessary. Preferable examples of such matrix resins include thermosetting resins and thermoplastic resins for RIM (Reaction Injection Molding). It is preferably at least one selected from unsaturated polyester resins, cyanate ester resins, bismaleimide resins and benzoxazine resins.

In addition, since the FRP of the present invention has excellent mechanical properties and is lightweight, it is used as a primary structural member, secondary structural member, exterior member or interior member in any of transportation equipment such as aircraft, automobiles and ships. is preferably

Next, the FRP molding method using the reinforcing fiber base material in the present invention will be described.

Of the reinforcing fiber substrates in the present invention, reinforcing fiber substrates composed of reinforcing fiber yarns and reinforcing fiber yarn groups are arranged in a desired shape by an AFP or ATL device.

Such an arrangement step may be performed in a two-dimensional planar shape, or may be performed in a three-dimensional shape. In the case of a two-dimensional planar shape, after arranging the reinforcing fiber base material for each layer, by arranging and bonding the porous resin material, a sheet-like reinforcing fiber base material that can be easily transported for each layer is formed. It can be created and can be transported to a separately prepared shaping mold without breaking the shape in a state where it is aligned and arranged. At this time, it is preferable that the porous resin material arranged at this time has at least partial cuts, because the formability in the preforming step described later will be better. Moreover, as a conveying means, a conveying means using a method such as static electricity, suction, needle sticking, or the like can be used.

Further, the sheet-like reinforcing fiber base material prepared for each layer may be made into a reinforcing fiber laminate by stacking a plurality of layers and integrating them by heat-sealing or stitching in order to further improve handleability. At this time, by making the arrangement direction of the n-th layer of the reinforcing fiber base material after the second layer different from the arrangement direction of the (n-1)-th layer, it can be treated in the same way as a fabric. It can be a fiber laminate. Such a step of integrating the reinforcing fiber base materials may be performed on the entire surface where the reinforcing fiber base materials are overlapped, or may be performed partially. When the entire surface is integrated, the reinforcing fiber base material has excellent shape stability. On the other hand, if it is partially integrated, it is easily deformed when it is formed into a molded product shape in the preforming step described later (that is, the shapeability is good). Therefore, it is preferable to arbitrarily use these according to the complexity of the shape of the molded product.

Here, the reinforcing fiber base material in the present invention is a group of reinforcing fiber yarns (to which no resin material is attached) arranged in a desired shape by an AFP or ATL device, and a porous resin is added to the group of reinforcing fiber yarns. It can also include those in which materials are arranged and adhered. As a result, properties such as impact resistance can be imparted to carbon fiber yarns that do not have properties such as impact resistance.

Furthermore, after placing the first layer of the reinforcing fiber base material, the placement of the second and subsequent layers may be repeated on the same plane. In this placement step, a heater is provided in the head portion of the AFP or ATL device, and the reinforcing fiber base material is placed in the second and subsequent layers while melting the resin material on the surface of the reinforcing fiber base material, thereby performing the placement step of the reinforcing fiber base material. It is possible to unify the integration process. At this time, by making the arrangement direction of the n-th layer of the reinforcing fiber base material after the second layer different from the arrangement direction of the (n-1)-th layer, it can be treated in the same way as a fabric. It can be a fiber laminate.

Further, among the reinforcing fiber base materials in the present invention, the reinforcing fiber base material composed of the reinforcing fiber aggregate and the reinforcing fiber laminate containing the resin material between the layers of the reinforcing fiber yarn group are formed into a desired shape according to the shape of the molded product. It is cut into pieces and used.

The reinforcing fiber base material or the reinforcing fiber laminate prepared in this way can be laminated one by one or a plurality of layers in a desired angular configuration, and then subjected to a preforming step to prepare a preform.

Molding of the FRP of the present invention is performed by so-called resin injection molding, and RTM (Resin Transfer Molding) molding and VaRTM (Vacuum assisted Resin Transfer Molding) molding are preferably applied. The porous resin material arranged on at least one side of the reinforcing fiber base material in the present invention functions as a flow path (air path) for discharging the air inside the reinforcing fiber base material and as a resin diffusion medium. Demonstrate. Therefore, it is possible to improve the internal quality of the molded product and speed up the resin injection process. In addition, since the porous resin material arranged on at least one side of the reinforcing fiber base material of the present invention has connections in the planar direction, deformation of the reinforcing fiber base material when the resin is injected at high pressure can be prevented.

The FRP of the present invention has a reinforcing fiber volume content (Vf) in the range of 53 to 65%, and the room temperature compressive strength after impact described in SACMA-SRM-2R-94 is 240 MPa or more. preferable. Note that Vf (in units of vol%) refers to the volume ratio of reinforcing fibers in a fiber-reinforced resin, and is specifically defined by the following formula, and the symbols used here are as shown below.
Vf=(W×100)/(ρ×T)
W: Weight of reinforcing fiber per 1 cm ² of reinforcing fiber substrate (g/cm ² )
ρ: Density of reinforcing fiber (g/cm ³ )
T: Thickness of fiber reinforced resin (cm)

When the Vf of the fiber reinforced resin is in the range of 53 to 65%, the excellent mechanical properties of the fiber reinforced resin can be maximized. If the Vf is less than 53%, the weight reduction effect is poor, and if it exceeds 65%, molding by resin injection molding described above becomes difficult, and mechanical properties (especially impact resistance) may deteriorate. That is, in such a Vf range, if the room temperature compressive strength after impact application described in SACMA-SRM-2R-94 of the fiber reinforced resin is 240 MPa or more, it is a material that satisfies both the weight reduction effect and the mechanical properties. can do. Fiber-reinforced resins that meet these requirements are used in a wide variety of applications due to their excellent mechanical properties and weight reduction effects. Although it is not particularly limited, it is used for primary structural members, secondary structural members, exterior members, interior members, or parts thereof in transportation equipment such as aircraft, automobiles, and ships to maximize its effects.

Incidentally, SACMA is an abbreviation of Suppliers of Advanced Composite Materials Association, and SACMA-SRM-2R-94 is a test method standard defined by this. Cold compressive strength after impact is measured in accordance with SACMA-SRM-2R-94 under dry conditions at an impact energy of 270 inch pounds.

The present invention will be further described below using examples. Raw materials and molding methods used in Examples and Comparative Examples are as follows. It should be noted that the present invention is not limited to these Examples and Comparative Examples.

[Example 1]
<Reinforcing fiber thread>
As the carbon fiber thread, PAN-based carbon fiber, 24,000 filaments, tensile strength: 6.0 GPa, tensile modulus: 294 GPa was used.

<Porous resin material>
Polyamide 12 resin (“Grilamid” (registered trademark) L16, manufactured by Em Chemie Japan Co., Ltd.) was melt-blown to obtain a porous resin material in the form of a non-woven fabric. The Vicat softening temperature was 160°C. The resulting porous resin material was hot-pressed at a temperature of 160° C. and a pressure of 0.1 MPa for 10 seconds. The dry heat dimensional change rate at 130° C. of the porous resin material after hot pressing was 0.5%.

<Matrix resin>
To 100 parts by weight of the main liquid, 39 parts by weight of the curing liquid was added, and the mixture was uniformly stirred at 80° C. to prepare an epoxy resin composition.
Main liquid: Tetraglycidyldiaminodiphenylmethane type epoxy ("Araldite" (registered trademark) MY-721, Huntsman Japan Co., Ltd.) 40 parts by weight, liquid bisphenol A type epoxy resin ("EPON" (registered trademark) 825, manufactured by Mitsubishi Chemical Corporation) 35 parts by weight, diglycidylaniline (GAN, manufactured by Nippon Kayaku Co., Ltd.) 15 parts by weight, and triglycidyl aminophenol type epoxy resin (“jER” (registered trademark) 630, Mitsubishi Chemical Co., Ltd.) was weighed out and stirred for 1 hour at 70° C. for uniform dissolution.

Curing liquid: modified aromatic polyamine (“jER Cure” (registered trademark) W, manufactured by Mitsubishi Chemical Corporation) 70 parts by weight, 3,3′-diaminodiphenylsulfone (manufactured by Mitsui Chemicals Fine Co., Ltd.) 20 parts by weight, and 10 parts by weight of 4,4′-diaminodiphenylsulfone (“Seika Cure” S, manufactured by Seika Co., Ltd.), each weighed, stirred at 100° C. for 1 hour to homogenize, cooled to 70° C., and cured. As an accelerator, 2 parts by weight of t-butyl catechol (DIC-TBC, manufactured by DIC Corporation) was weighed and further stirred at 70°C for 30 minutes to dissolve uniformly.

<Reinforcing fiber base material>
Using the apparatus shown in FIG. 2, a tape-shaped reinforcing fiber substrate having a width of 1/4 inch was produced. The basis weight of the reinforcing fiber base material was 162 g/m ² .

<Reinforcing fiber laminate>
Such a reinforcing fiber base material is pseudo-isotropically laminated [45/0/-45/90] _3S (24 layers: here, "3S" is symmetrically laminated in the order of the orientation angles shown in [ ] with an AFP device. [Symmetry] A mode in which three sets (8 layers x 3 = 24 layers) of three sets (8 layers x 3 = 24 layers) of which one set (4 layers x 2 = 8 layers) is combined with the layers stacked in the same arrangement is shown below. ) was laminated on a planar preform mold in the configuration of ), and then heated in an oven at 120° C. for 1 hour while being sealed with a bag film and a sealant and reduced in vacuum. Thereafter, the preform was taken out of the oven, cooled to room temperature, and then depressurized to obtain a reinforcing fiber laminate.

<Fiber reinforced resin>
A resin diffusion medium (aluminum wire mesh) is laminated on the obtained reinforcing fiber laminate, and a cavity is formed by sealing with a flat molding die and bag material using a sealant, and placed in an oven at 100 ° C. I put it in. After the temperature of the reinforcing fiber laminate reached 100°C, the closed cavity was evacuated to a vacuum, and the matrix resin was injected only under the pressure difference from the atmospheric pressure while maintaining the temperature at 100°C. After being impregnated with the matrix resin, the temperature was raised to 180° C. while the pressure was reduced, and the FRP flat plate 1 was obtained by leaving it to stand for 2 hours for curing and demolding. Vf was 58% and CAI was 260 MPa.

[Example 2]
Polyamide 6 resin (“Amilan” (registered trademark) CM1007, manufactured by Toray Industries, Inc.) was used as the porous resin material, and the FRP flat plate 2 was fabricated in the same manner as in Example 1, except that the hot press temperature was set to 210°C. Created. The Vicat softening temperature of the porous resin material was 205° C., and the dry heat dimensional change at 130° C. of the porous resin material after hot pressing was 0.3%. The FRP flat plate 2 had a Vf of 54% and a CAI of 230 MPa.

[Comparative Example 1]
A reinforcing fiber base material was produced in the same manner as in Example 1, except that the hot press temperature when producing the porous resin material was 130 ° C., but the porous resin material was thermally shrunk between the heater and the press roll. However, the width of the porous resin material became shorter than the width of the reinforcing fiber threads, and it was not possible to obtain a tape-shaped reinforcing fiber base material of satisfactory quality. At this time, the dry heat dimensional change rate of the porous resin material was 5.8%.

Since the FRP of the present invention has excellent mechanical properties and is lightweight, its use is limited to primary structural members, secondary structural members, exterior members or interior members in transportation equipment such as aircraft, automobiles, and ships. It is also suitable for members for general industrial applications such as medical equipment such as windmill blades, robot arms and X-ray tabletops.

11: Reinforcing fiber substrate 12: Reinforcing fiber assembly 13: Porous resin material 20: Bobbin 21: Reinforcing fiber substrate 22: Reinforcing fiber thread 23: Resin material 201: Spreading unit 202: Width regulation roller 203: Heater 204: Press roll 31: Reinforcing fiber thread group 32: Reinforcing fiber thread 300: AFP head 41: Unidirectional fabric 42: Reinforcing fiber thread (warp)
43: Auxiliary thread (warp)
44: Auxiliary thread (weft)
51: Bidirectional fabric 52: Reinforcing fiber thread (warp)
53: Reinforcing fiber thread (weft)
61: Stitched fabric 62: +α° reinforcing fiber layer forming reinforcing fabric 63: 90° reinforcing fiber layer forming reinforcing fabric 64: −α° reinforcing fiber layer forming reinforcing fabric 65: forming reinforcing fabric 0° reinforcing fiber layer 66: stitch yarn

Claims (5)

[1]: Reinforcing fiber yarn, [2]: Reinforcing fiber yarn group formed by arranging reinforcing fiber yarns in parallel, [3]: Reinforcing fiber fabric made of reinforcing fiber yarns. A reinforcing fiber base material for resin injection molding in which a resin material is disposed on at least one surface of a reinforcing fiber assembly in which the resin material is a porous resin having a dry heat dimensional change rate of 5% or less at 130 ° C. A reinforcing fiber base material for resin injection molding, characterized by being a material. The resin material is polyamide resin, polyester resin, polyphenylene sulfide resin, polyetherimide resin, polyethersulfone resin, polyvinyl formal resin, polyetheretherketone resin, polycarbonate resin, polysulfone resin, polyphenylene ether resin, polyimide resin, polyamideimide. 2. The reinforcing fiber base material for resin injection molding according to claim 1, comprising at least one selected from a resin and a phenoxy resin, or a mixture thereof. 3. The reinforcing fiber base material for resin injection molding according to claim 1, wherein said porous resin material is heat-treated at a Vicat softening temperature or higher of said resin material. The reinforcing fiber base material for resin injection molding according to claim 3, wherein the Vicat softening temperature of the resin material is 70°C or higher and 200°C or lower. The reinforcing fiber substrate for resin injection molding according to any one of claims 1 to 4, wherein the porous resin material is a long-fiber nonwoven fabric.

Images