JP2011255619A - Method of manufacturing fiber-reinforced plastic molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing a fiber-reinforced plastic with which a molding can be easily manufactured where a thermoplastic resin can be evenly impregnated in a continuously reinforced fiber of the formed molding.SOLUTION: A reinforced fiber plastic molding 10A is manufactured by: a step of knitting a braid 4A from a prepreg 3 including a thermoplastic resin and the continuously reinforced fiber; and a subsequent heat-molding step of molding the braid 4A into a predetermined shape while heating at least the braid 4A so that the thermoplastic resin of the braid 4A is fused.

Description

  The present invention relates to a method for producing a fiber-reinforced plastic molded body that can suitably produce a molded article of fiber-reinforced plastic in which a continuous reinforcing fiber is impregnated with a thermoplastic resin.

  Conventionally, fiber reinforced plastic obtained by impregnating a resin with carbon, glass or other reinforcing fibers is lighter than metal materials and has higher mechanical strength than mere resin materials. It is also widely applied to vehicle parts such as automobiles.

  For example, when continuous reinforcing fibers are used as the reinforcing fibers of the fiber reinforced plastic and the continuous reinforcing fibers are aligned in one direction, the strength in the vertical direction relative to the strength in the fiber length direction decreases. End up. Therefore, considering such points, the continuous reinforcing fibers are laminated in a multiaxial manner, the continuous reinforcing fibers are made into a woven shape, or the continuous reinforcing fibers are knitted into a braided body before molding. Therefore, the mechanical strength of the fiber reinforced plastic is made isotropic.

  For example, as a method of manufacturing a fiber-reinforced plastic molded body by braiding, a reinforcing fiber is made into a multi-axis by tilting in a cylindrical mandrel 80 in the axial direction L by braiding as shown in FIG. Of continuous reinforcing fibers 91, 91... (See FIG. 4 (a)) to form a reinforcing fiber braid 93 knitted into a cylindrical shape (see FIG. 4 (b)). Press-molded (shaped) the shaped shaped body 95 (see FIG. 4 (c)), put the shaped body 95 into the molding die 97, and injects resin from the injection device 98 by an injection molding method to continuously reinforce. A method for manufacturing a fiber-reinforced plastic molded body in which a resin is impregnated into the fiber 91 (see FIG. 4D) has been proposed (see, for example, Patent Document 1).

  Another embodiment is a fiber reinforced plastic in which a continuous reinforced fiber is impregnated with an uncured thermosetting resin, wound around a mandrel, and the wound prepreg is heated to cure the thermosetting resin. A method for manufacturing a cylindrical body has been proposed (see, for example, Patent Document 2).

JP 2009-107408 A JP 2009-090514 A

  However, when a fiber-reinforced plastic molded body is manufactured by the manufacturing method shown in Patent Document 1, there are cases where continuous reinforcing fibers cannot be sufficiently impregnated with resin in the impregnation step after shaping. In particular, such a tendency was remarkable with the increase in the thickness of the shaped body and the use of the thermoplastic resin.

  In view of this point, as shown in Patent Document 2, when using a prepreg in which continuous reinforcing fibers are impregnated with an uncured thermosetting resin whose viscosity is generally lower than that of a thermoplastic resin, Such a point is considered to be eliminated.

  However, when a prepreg of a thermosetting resin is used, it is easy to produce a cylindrical molded body. However, when the required shape of the molded body is a complicated shape, The tubular braided body in the state of the curable resin is shaped into a desired shape of the molded body, and then the thermosetting resin is cured. In this case, it is not easy to take out the braid from the mandrel while maintaining the shape of the uncured thermosetting resin braid, and the braid with an unstable shape is further shaped into the desired shape of the molded body. It is extremely difficult to do.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to easily produce a molded body capable of uniformly impregnating a continuous reinforcing fiber of a molded molded body with a thermoplastic resin. Another object of the present invention is to provide a method for producing a fiber-reinforced plastic molded product.

  In order to solve the above problems, a method for producing a fiber-reinforced plastic molded body according to the present invention includes a step of knitting a braided body from a prepreg containing a thermoplastic resin and continuous reinforcing fibers, and the thermoplastic resin of the braided body is melted. And at least a heating forming step of forming the braided body into a predetermined shape while heating the braided body.

  According to the present invention, it is possible to uniformly impregnate a continuous reinforcing fiber of a formed molded body with a thermoplastic resin by thermoforming a braided body knitted from a prepreg containing the thermoplastic resin and the continuous reinforcing fiber. it can.

  The braided body is preferably knitted so that the thermoplastic resin and the continuous reinforcing fibers are uniformly dispersed. Here, in the process of knitting the braided body, the braided body is knitted from the prepreg containing the thermoplastic resin and the continuous reinforcing fiber without using the core material, and in the heat forming process, the braided body is pressure-formed between the heating rolls. A flat fiber-reinforced plastic molded body may be used. In the heat forming step, the braided body may be press-molded to form a fiber-reinforced plastic molded body having a desired shape.

  Moreover, when using a core material, it is more preferable that the prepreg is wound around the surface of the core material by a braiding method and the braided body is knitted on the surface of the core material in the step of knitting the braided body.

  According to the present invention, since the prepreg is wound around the surface of the core material by the braiding method, a braided body in which continuous reinforcing fibers intersect so as to cover the surface of the core material can be obtained. In the thermoforming process, the braided body is heated to melt the thermoplastic resin contained in the braided body, thereby integrating the thermoplastic resin contained in the prepreg, so that the thermoplastic resin is uniformly formed on the continuous reinforcing fibers. An impregnated shaped body can be obtained.

  In addition, since the braided body is knitted by the braiding method, the mechanical strength of the obtained molded body can be made isotropic, and the shape according to the shape of the core material more easily and without waste of material A fiber-reinforced plastic molded article can be obtained. Furthermore, by appropriately adjusting the number of prepregs and the assembly angle at the time of braiding, a fiber-reinforced plastic molded product having different mechanical characteristics can be easily obtained.

  Such a fiber-reinforced plastic molded body may leave the core material, and may be heat-molded with the core material by hot pressing, or may be heat-molded with the core material between a pair of heating rolls. Only the braided body from which the core material has been removed may be formed by heating. When performing thermoforming while leaving the core material, in the thermoforming step, the core material is integrated with the braided body while heating so that the thermoplastic resin of the braided body is welded to the surface of the core material. It is preferable to heat mold.

  According to the present invention, in the thermoforming process, the core material can be molded together with the braided body while welding the thermoplastic resin of the braided body to the surface of the core material, so that the core material and the braided body are joined. Can do.

  Here, if the core material is made of a foam material, the obtained fiber-reinforced plastic molded body can be further reduced in weight, and furthermore, the pores of the foam material are impregnated with resin. The bondability of the body can be improved. In addition, since the fiber reinforced plastic obtained from the braided body is disposed on the surface layer of the molded body where a large stress is more likely to act than other parts when using the molded body, a core material made of a foam material is used. Even if it is used, the mechanical strength of the obtained molded article can be sufficiently ensured.

  As such a core material, for example, a metal core material, a resin core material and the like can be mentioned, and if the moldability and mechanical strength of the fiber-reinforced plastic molded body can be ensured, In particular, the material is not limited.

  However, more preferably, in the method for manufacturing a fiber-reinforced plastic molded body, the same thermoplastic resin as the thermoplastic resin of the prepreg is used for the core material, and in the thermoforming process, together with the thermoplastic resin of the braided body. The core material and the braided body are heated so that the thermoplastic resin in at least the surface layer of the core material melts.

  According to the present invention, by using the same thermoplastic resin as the prepreg thermoplastic resin for the core material, the resin of the core material and the braided body can be easily adapted. In the thermoforming process, the surface of the core material covered with the braided body is also melted, so that the bondability between them can be further improved.

  Here, the “same thermoplastic resin” referred to in the present invention includes not only a resin whose composition is completely the same, but also a thermoplastic resin as a main material containing the same resin. For example, when the thermoplastic resin contained in the prepreg is a nylon resin, it means that the same kind of nylon resin is used for the thermoplastic resin constituting the core material.

  Further, the shape of the core material is not particularly limited as long as the prepreg can be uniformly wound by the braiding method. However, more preferably, in the method for producing a fiber-reinforced plastic molded body according to the present invention, the core material is a long core material, and the cross-section in the longitudinal direction of the core material is an irregular cross-section having a different shape. It is more preferable to use the core material.

  Until now, when manufacturing a fiber-reinforced plastic molded body having such a shape, the braided body cannot be taken out from the mandrel by the above-described methods of Patent Documents 1 and 2, so that continuous reinforcing fibers are laminated in multiple axes. The molded body was manufactured using the prepreg obtained by laminating woven prepregs or woven continuous reinforcing fibers. However, according to this invention, the molded object which has a deformed cross section can be easily manufactured by manufacturing by the method mentioned above using the core material which has a deformed cross section in a longitudinal direction.

  In addition, when using a prepreg laminated with multi-axial continuous reinforcing fibers or a prepreg laminated with woven continuous reinforcing fibers, prepare the reinforced prepreg according to the molded body. This is difficult, and unnecessary parts of the heat-formed molded body are cut out to obtain a molded product. However, in the case of the present invention, it is not necessary to prepare a core material matched to the molded body and the braided body is covered with the core material, so that unnecessary portions need not be cut off. As a result, a fiber-reinforced plastic molded body can be manufactured at a lower cost than before without generating extra waste material.

  Further, in the above-described method, the molded body is manufactured while leaving the core material during molding, but the core material may be removed. In this case, a more preferable aspect is that after the step of knitting the braided body and before the heat forming step, the core material is removed from the braided body, and in the heat forming step, the braided body is heat formed.

  According to the present invention, since the core material is removed from the braided body and only the braided body is heat-molded, the density of the continuous reinforcing fibers of the obtained fiber-reinforced plastic molded body is higher than that of the conventional one. A high-strength fiber-reinforced plastic molded body can be obtained. In addition, as for the core material used by this manufacturing method, it is more preferable that the cross section of a longitudinal direction is a core material of the same shape. Thereby, a core material can be easily extracted from a braided body along a longitudinal direction.

  In addition, it is preferable that the above-described continuous reinforcing fiber of the prepreg is included in such a degree that at least strength can be secured as a fiber reinforced plastic, and the thermoplastic resin is included in such an extent that it acts as a matrix resin of the continuous reinforcing fiber.

  Alternatively, the prepreg can include a strip-like, string-like, or thread-like prepreg containing a thermoplastic resin and continuous reinforcing fibers, and the continuous reinforcing fibers of the prepreg are aligned along the longitudinal direction of the prepreg. These prepregs are not particularly limited as long as they are flexible enough to be wound around the core by a braiding method.

  However, more preferably, the prepreg is a prepreg obtained by impregnating a continuous reinforcing fiber obtained by opening a continuous reinforcing fiber bundle with a thermoplastic resin, or a bundle of continuous resin fibers made of continuous reinforcing fiber and a thermoplastic resin. It is.

  Since the prepreg configured in this manner has superior flexibility as compared to the conventional pultruded prepreg and the like, the prepreg can be suitably wound around the core material by, for example, a braiding method.

  According to the present invention, it is possible to uniformly impregnate a continuous reinforcing fiber of a molded article with a thermoplastic resin.

It is a typical perspective view for demonstrating the fiber reinforced plastic molding method which concerns on 1st embodiment, (a) is the figure which showed the state which knitted the braided body from a prepreg, (b) is used for a knitting process The figure of a prepreg, (c) is the figure which showed the relationship between the braided body after a braiding process, and a core material, (d) is the figure which showed the fiber reinforced plastic of a thermoforming process. It is a typical perspective view for demonstrating the fiber reinforced plastic molding method which concerns on 2nd embodiment, (a) is the figure which showed the state which knitted the braided body from a prepreg, (b) is the state after a knitting process The figure which showed the relationship between a braided body and a core material, (c) is the figure which showed the fiber reinforced plastic molding after heat molding. It is a typical perspective view for demonstrating the fiber reinforced plastic molding method which concerns on 3rd embodiment, (a) is a figure for demonstrating the state which braids a braid from a prepreg, (b) is a braiding process The figure which showed the state which removed the core material from the back braided body, (c) is the figure which showed the fiber reinforced plastic molding after heat forming. It is a figure for demonstrating the conventional fiber reinforced plastic molding method, (a) is a typical perspective view which showed the state which knitted the braid body which consists of continuous reinforcement fibers, (b) is the braid which consists of continuous reinforcement fibers The schematic perspective view which showed the body, (c) The typical perspective view which showed the shaping state of the braided body, (d) is the process of impregnating the braided body with resin and injection-molding it into the fiber reinforced plastic molded body The figure for demonstrating.

  Below, based on drawing, three embodiment which concerns on this invention is described. FIG. 1 is a schematic perspective view for explaining a fiber-reinforced plastic molding method according to the first embodiment, (a) is a diagram showing a state in which a braided body is knitted from a prepreg, and (b) is The figure of the prepreg used for a knitting process, (c) is the figure which showed the relationship between the braided body and core material after a knitting process, (d) is the figure which showed the fiber reinforced plastic of a heat forming process.

  First, a braided body 4A is formed on the surface 2a of the flat core 2A using a braider such as a three-dimensional braider (rotor carrier type three-dimensional weaving loom). Specifically, a plurality of string-like prepregs 3, 3... Containing thermoplastic resin and continuous reinforcing fibers are wound around the surface 2a of the core 2A at a predetermined angle with respect to the axial direction L by a braiding method. The braided body 4A is knitted on the surface 2a of the long core 2A.

  FIG. 1 (a) is an example of this, and a plurality of prepregs 3, 3... Are moved in the axial direction of the core 2A with respect to the core 2A while moving the core 2A mounted on the machine in the axial direction L. From around the surface 2a along L, the prepreg 3 is woven into the surface 2A of the core material 2A by being alternately wound in a mesh shape.

  Here, the string-like prepreg 3 is a continuous mixed spinning in which the continuous reinforcing fiber 3a and the continuous resin fiber 3b made of a thermoplastic resin are homogeneously mixed as shown in FIG. 1 (b). . However, the structure of these prepregs is not particularly limited as long as the prepreg is flexible enough to be wound around the core 2A by the braiding method. ). Further, it may be a string-like body obtained by impregnating a matrix resin made of a thermoplastic resin into a plurality of continuous reinforcing fibers aligned (oriented) along the longitudinal direction (in one direction). It may be a narrow tape obtained by impregnating a continuous reinforcing fiber having a bundle opened with a thermoplastic resin.

  The continuous reinforcing fiber 3a is a continuous fiber for resin reinforcement for reinforcing the mechanical strength of the fiber reinforced plastic. For example, glass fiber, carbon fiber, aramid fiber, alumina fiber, boron fiber, steel fiber, PBO fiber , Organic fibers, or fibers such as high-strength polyethylene fibers, natural fibers, metal fibers, and the like. As long as they are continuous in the longitudinal direction, they may be cloth-like fibers instead of thread-like fibers. However, in order to obtain stable material properties, it is more preferably a continuous reinforcing fiber in which continuous fibers are aligned (oriented) in one direction.

  The thermoplastic resin constituting the prepreg is not particularly limited as long as it can be impregnated into the continuous reinforcing fibers 3a and functions as a matrix resin for the fibers. For example, nylon resin, polycarbonate resin, polyamide resin, polyolefin resin, or Examples thereof include acrylic resins and ABS resins.

  Furthermore, the core material 2 </ b> A is made of the same thermoplastic resin as the thermoplastic resin of the prepreg 3. Further, the core material 2A has a shape corresponding to a molded body to be obtained (in the case of the present embodiment, an L-shaped molded body). In the case of the present embodiment, the axial cross-sectional shape is the same. A rectangular long material is used.

  In this way, as shown in FIG. 1C, a multiaxial three-dimensional braided body (a braided body of a multiaxial structure) 4A in which a large number of prepregs 3, 3... Are knitted can be obtained. Here, the multiaxial three-dimensional braided body (a braided body of a multiaxial structure) is a braided body in which prepregs arranged in a plurality of (multiple) directions cross each other and are joined together.

  It should be noted that the braided body 4A having a desired strength can be obtained by appropriately selecting a multiaxial structure, a biaxial structure, a triaxial structure, or an angle of the assembly angle ± θ. Obtainable. Also, a braided body having a multilayer structure can be obtained by performing reciprocal weaving in the axial direction.

  The braided body 4A thus obtained is placed in a hot press apparatus, and the thermoplastic resin of at least the surface layer of the core material 2A is melted together with the thermoplastic resin of the braided body 4A, and these are welded to each other. Thus, the core material 2A is heated together with the braided body 4A. Then, in this heated state, the core material 2A and the braided body 4A can be formed into a U-shaped cross section by pressing to obtain a fiber-reinforced plastic molded body 10A.

  Thus, by using the same thermoplastic resin as the thermoplastic resin of the prepreg 3 for the core material 2A, the resin of the core material 2A and the braided body 4A can be easily adapted. And in a thermoforming process, since the surface of 2 A of core materials covered with 4 A of braids is also fuse | melted, both bondability can be improved further. In this way, the core material 2A and the braided body 4A are integrated, and as shown in FIG. 1D, a molded body 10A in which the continuous reinforcing fibers are impregnated with the thermoplastic resin can be obtained.

  In addition, since the braided body 4A is knitted by the braiding method, it is possible to ensure the isotropy of the mechanical strength of the obtained molded body 10A, and the shape of the core material more easily and without waste of materials. A molded body 10A according to the above can be obtained.

  FIG. 2 is a schematic perspective view for explaining a fiber-reinforced plastic molding method according to the second embodiment, (a) is a diagram showing a state in which a braided body is knitted from a prepreg, and (b) is The figure which showed the relationship between the braided body after a knitting process, and a core material, (c) is the figure which showed the fiber reinforced plastic molding after heat forming.

  The second embodiment is different from the first embodiment only in the shape of the core material. Accordingly, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

  As shown in FIG. 2A, the core material 2B according to the present embodiment is a long core material made of a thermoplastic resin, and the cross section in the axial direction of the core material 2B is an irregular cross section having a different shape. It has become. More specifically, the core material 2B is formed with a protruding portion 2b protruding in a trapezoidal shape in the width direction at the center in the axial direction (longitudinal direction) L, and this protruding portion 2b is formed of a molded body at the time of molding. A rib is formed.

  Using such a core material 2B, as shown in FIG. 2A, the prepreg 3 is wound around the surface 2a of the core material 2B by a braiding method, and as shown in FIG. A braided body 4B is knitted on the surface 2a of 2B. Next, while heating the core material 2B and the braided body 4B so that the thermoplastic resin at least in the surface layer of the braided body 4B and the core material 2B is melted, these are hot pressed into the shape shown in FIG. The fiber-reinforced plastic molded body 10B can be obtained by integral molding.

  Until now, when manufacturing a fiber-reinforced plastic molded body 10B having such a shape, it is molded by hot pressing using a prepreg in which continuous reinforcing fibers are laminated in multiple axes or a prepreg in which woven continuous reinforcing fibers are laminated. It was manufactured by doing. However, if it shape | molds like this embodiment, the molded object which has a deformed cross section in an axial direction can be manufactured easily.

  In addition, when using a prepreg laminated with conventional continuous reinforcing fibers in multiple axes or a prepreg laminated with woven continuous reinforcing fibers, prepare the continuous reinforcing fibers according to the shape of the molded body. It is difficult to manufacture, and positional displacement may occur at the time of lamination. Furthermore, an unnecessary portion of the molded body formed by hot pressing is cut out to obtain a molded product.

  However, in this embodiment, since the core material 2B matched to the fiber reinforced plastic molded body 10B is prepared and the braided body 4B is covered with the core material 2B, it is not necessary to cut off unnecessary portions. As a result, the fiber-reinforced plastic molded body 10B can be manufactured at a lower cost than before without generating extra waste material.

  FIG. 3 is a schematic perspective view for explaining a fiber-reinforced plastic molding method according to the third embodiment, and (a) is a diagram for explaining a state in which a braided body is knitted from a prepreg, and (b). These are the figures which showed the state which removed the core material from the braided body after a knitting process, (c) is the figure which showed the fiber reinforced plastic molding after heat forming.

  The third embodiment is different from the first embodiment in that the core material is removed from the braided body before the heat forming. Accordingly, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof will be omitted.

  First, as in the first embodiment, as shown in FIG. 3A, the prepreg 3 is wound around the surface 2a of the core material 2A by braiding, and the braided body 4A is knitted on the surface 2a of the core material 2A. . Next, as shown in FIG. 3B, the core material 2A is moved along the axial direction L, and the core material 2A is removed from the braided body 4A. Next, while heating the braided body 4A so that the thermoplastic resin of the braided body 4A melts, it is molded by hot pressing into the shape shown in FIG. 3C, and the cross section in the axial direction is an L-shaped fiber. A reinforced plastic molded body 10C can be obtained.

  Thus, since the core material 2A is removed from the braided body 4A and only the braided body 4A is heat-molded, the density of the continuous reinforcing fibers of the obtained fiber-reinforced plastic molded body 10C is higher than that of the conventional one. Thus, a fiber-reinforced plastic molded body having higher strength can be obtained.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various designs can be made without departing from the spirit of the present invention described in the claims. It can be changed.

  For example, in the first to third embodiments, the braided body is knitted using the core material, but the braided body may be knitted from the prepreg without using the core material, and this may be heat-molded. In the case of producing a flat or sheet-like fiber reinforced plastic molded body, the molded body may be thermoformed while a braided braided body is sandwiched between a pair of heated rolls.

  Moreover, in 1st embodiment and 3rd embodiment, although the plate-shaped core material was used, the shape of a core material is not limited to this shape, For example, you may use a cylindrical core material. What is necessary is just to use the core material match | combined with the shape of the required molded object.

  In the third embodiment, the core material is removed by drawing, but the core material may be removed by shaving, and the method is not particularly limited as long as the core material can be removed. .

  1A, 1B, 1C: Fiber reinforced plastic molded body (molded body), 2A, 2B: Core material, 3: Prepreg, 3a: Continuous reinforcing fiber, 3b: Resin fiber, 4A, 4B: Braided body, L: Axial direction ( (Longitudinal direction)

Claims (6)

Knitting a braid from a prepreg containing a thermoplastic resin and continuous reinforcing fibers;
And a thermoforming step of forming the braid into a predetermined shape while heating the braid so that the thermoplastic resin of the braid is melted. Production method.   2. The fiber-reinforced plastic molded body according to claim 1, wherein in the step of knitting the braided body, the prepreg is wound around a surface of a core material by a braiding method, and the braided body is knitted on the surface of the core material. Manufacturing method.   The core material is integrally heat-molded together with the braided body while heating the thermoplastic resin of the braided body so as to be welded to the surface of the core material in the thermoforming step. The manufacturing method of the fiber reinforced plastic molding of description.   For the core material, the same thermoplastic resin as the thermoplastic resin of the prepreg is used, and in the thermoforming step, together with the thermoplastic resin of the braided body, at least the thermoplastic resin of the surface layer of the core material is melted. The said core material and the said braided body are heated, The manufacturing method of the fiber reinforced plastic molding of Claim 3 characterized by the above-mentioned.   The fiber according to any one of claims 2 to 4, wherein the core material is a long core material, and the cross-section in the longitudinal direction of the core material is an irregular cross section having a different shape. A method for producing a reinforced plastic molding.   3. The fiber-reinforced fiber according to claim 2, wherein after the step of knitting into the braided body and before the heat forming step, the core material is removed from the braided body, and the braided body is heat formed in the heat forming step. A method for producing a plastic molded body.

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