JP6229881B2 - Manufacturing method of fiber reinforced composite molded product - Google Patents

Description

The present invention relates to a method for producing a fiber-reinforced composite molded article .

For example, these parts, which were previously made of metal, are made of fiber-reinforced composite materials, aiming to reduce the weight, rigidity, and functionality of various machine parts such as automotive parts such as rack housings and machine tool parts. Replacement with a fiber-reinforced composite molded article is under consideration.
For example, as a carbon fiber reinforced composite material using carbon fiber among fiber reinforced composite materials, press working at a high temperature or welding with the same or different thermoplastic resin is possible recently. CFRTP material (Carbon Fiber Reinforced Thermo Plastics) using a thermoplastic resin, which is superior in workability and economy compared to the so-called CFRP material (Carbon Fiber Reinforced Plastics) used, is becoming widespread. The CFRTP material is produced by impregnating a carbon fiber sheet (woven fabric, non-woven fabric, strand, etc.) with a thermoplastic resin heated and melted.

  Taking advantage of the fact that welding with a thermoplastic resin, which is one of the advantages of a fiber-reinforced composite material using a thermoplastic resin such as a CFRTP material, is possible, for example, Patent Document 1 discloses a single-layer or multi-layer flat plate. A fiber-reinforced composite material is placed in a mold and a thermoplastic resin is injection-molded to combine and integrate the fiber-reinforced composite material and the thermoplastic resin. It is described that they are coupled and integrated.

  Further, Patent Document 2 describes that one side of a flat fiber reinforced composite material is formed in an uneven shape, and a thermoplastic resin is injection-molded on the side of the surface to increase the strength of the integration between the two. .

JP-A-6-15687 JP 2010-274508 A

In order to replace a part having various three-dimensional shapes with a fiber reinforced composite molded product, the fiber reinforced composite material used as the base includes a bent portion such as a curved surface, an arc shape, a square shape, a U shape, etc. It is necessary to form into a three-dimensional shape.
For that purpose, for example, a plurality of fiber reinforced composite materials corresponding to the thickness of the fiber reinforced composite molded article to be manufactured are stacked, and heated to near the melting point of the thermoplastic resin under pressure using a hot press, and each fiber reinforced composite material After the thermoplastic resin inside is melted and integrated, the laminated fiber reinforced composite material is integrated with the thermoplastic resin to produce a flat plate-shaped prepreg, and then the prepreg is heated again to the vicinity of the melting point for thermoplasticity. It is conceivable to press-mold the resin-reinforced composite molded article into a three-dimensional shape using a mold while the resin is softened or melted.

Further, the prepreg may be produced using the injection molding method described in Patent Documents 1 and 2.
However, with such a method, particularly during press molding, the integrated fiber reinforced composite material is easy to peel off between the layers, and if peeled off, the strength, impact resistance, heat shock resistance, etc. of the fiber reinforced composite molded product deteriorate. Produce.
The main cause of peeling is that the flat fiber-reinforced composite material has a small amount of expansion and contraction in the surface direction, and the thermoplastic resin softens or melts due to heating during press molding, resulting in a decrease in bonding strength between layers. is there.

That is, when the prepreg is bent by press molding, the outer fiber reinforced composite material in the bending direction is subjected to stress in the direction of extending in the plane direction, and the inner fiber reinforced composite material is compressed in the surface direction. Stress is applied.
However, since individual fiber reinforced composite materials cannot sufficiently expand and contract in the surface direction according to these stresses, stress accumulates inside, and when the thermoplastic resin softens or melts due to heating, the bond strength between the layers decreases In addition, deformation is caused by the accumulated stress, and the layers are easily separated.

In particular, separation between layers tends to occur in a portion where stress is easily accumulated during press molding, such as a portion where a fiber reinforced composite material is bent with a very small radius.
In particular, when a thermoplastic resin is added using an injection molding method, there is a problem that the strength of the fiber-reinforced composite molded product is lowered because the proportion of reinforcing fibers is relatively reduced.
An object of the present invention is to produce a fiber reinforced composite molded article comprising at least two fiber reinforced composite layers, having a three-dimensional shape including a bent portion, and having no risk of peeling between layers and various problems associated therewith. It is to provide a method.

In order to solve the above-mentioned problems, the present invention is a fiber reinforcement in which a fiber sheet is impregnated with a thermoplastic resin, and at least two layers having a three-dimensional shape including a bent portion are laminated and integrated through a thermoplastic resin. A method for producing a fiber reinforced composite molded article (1) comprising a composite material layer (2) and a filler (3) that penetrates at least two laminated fiber reinforced composite material layers and reinforces bonding between the layers. ,
Process wherein a fiber-reinforced composite material layer at least 2-layered fiber reinforced composite material comprising the original stacked and press-forming a flat prepreg which is formed by integrating, in the three-dimensional shape including a bent portion, and the press molding Is a method for producing a fiber-reinforced composite molded article comprising a step of injection molding a thermoplastic resin having a higher melt flow rate than a thermoplastic resin impregnated in a fiber sheet, including a filler in a prepreg at any stage before and after (Claim 1 ).

In the process of up press forming, it is also possible to combine at least two prepregs (claim 2).
Further in the case of injection molding after press molding is a process of the injection molding, structural part made of a thermoplastic resin (8) to (10) (12) may be molded integrally (claim 3).

  In this section, numbers in parentheses represent reference numerals of corresponding components in the embodiments described later, but the scope of the claims is not limited by these reference numerals.

According to the first aspect of the present invention, at least two laminated fiber reinforced composite material layers are integrated by the thermoplastic resin, and the bonding of the at least two layers is made by the filler penetrating both layers. Since it is reinforced, separation between layers can be prevented, and a fiber-reinforced composite molded product can be produced without deteriorating strength, impact resistance, heat shock resistance, etc. due to separation .

In addition, at least two layers of fiber reinforced composite material, which are the basis of the fiber reinforced composite material layer, are included in each fiber reinforced composite material by passing through two steps of a press molding process and an injection molding process. In addition to thermoplastic resin, it is bonded firmly by injection molding between the fiber reinforced composite material and between the fiber reinforced composite material and the filler that penetrates the laminated fiber reinforced composite material. to, without causing peeling or the like, can be produced fiber reinforced composite molded product.

In particular, when injection molding is performed after press molding, a mold for injection molding is used in the press molding process, press molding is performed using the clamping force of the mold, and a thermoplastic resin containing a filler is then used. because be injection molded, the fiber-reinforced composite molded article can be produced easily and efficiently with fewer steps.
Furthermore, since the filler is added together with the thermoplastic resin, the proportion of the reinforcing fiber is reduced, but the reinforcing effect of the filler can also prevent the strength of the fiber-reinforced composite molded product from being reduced.

Moreover, by injection molding a thermoplastic resin and a filler having a higher melt flow rate than the thermoplastic resin impregnated into the fiber sheet, the thermoplastic resin and the filler are made into the interlayer of the fiber-reinforced composite material and the fiber reinforcement. Penetration into the composite material can be further improved, and separation between layers can be further prevented.
According to the invention described in claim 2 , it is possible to manufacture a fiber-reinforced composite molded article having a more complicated three-dimensional shape, which cannot be formed only by press-molding one prepreg.

Also, in the injection molding process, the filler can be penetrated between the prepregs that are heat-welded to each other to reinforce the bond.
According to the invention described in claim 3, a complex fiber-reinforced composite molded product in which the fiber-reinforced composite material layer and the structural portion are integrally formed can be easily and efficiently manufactured with fewer steps.
Further, the fiber reinforced composite material layer and the structural portion can be integrated with a thermoplastic resin.

It is sectional drawing which expanded a part of example of embodiment of the fiber reinforced composite molded product manufactured by the manufacturing method of this invention. FIGS. (A) and (b) are each a schematic diagram illustrating an example of a process for producing the fiber-reinforced composite molded article of FIG. Fig. (A) is a cross-sectional view showing another example of the embodiment of the fiber-reinforced composite molded article produced by the production method of the present invention, and Fig. (B) is an enlarged view of part of Fig. (A). It is sectional drawing. FIG. 4 is a perspective view of the fiber-reinforced composite molded product of FIGS. 3 (a) and 3 (b). FIGS. (A) and (b) are cross-sectional views illustrating an example of a process for manufacturing the fiber-reinforced composite molded article of FIGS. 3 (a) and 3 (b).

FIG. 1 is an enlarged cross-sectional view of a part of an example of an embodiment of a fiber-reinforced composite molded product manufactured by the manufacturing method of the present invention. 2 (a) and 2 (b) are schematic views for explaining an example of a process for producing the fiber-reinforced composite molded product of FIG.
Referring to FIG. 1, a fiber reinforced composite molded article 1 of this example is formed by impregnating a fiber sheet with a thermoplastic resin, and a plurality of layers having a curved shape are laminated and integrated through a thermoplastic resin. It consists of a fiber reinforced composite material layer 2.

In addition, the laminated fiber reinforced composite material layer 2 of the laminated layers is reinforced by the filler 3 that randomly penetrates at least two of the fiber reinforced composite material layers 2 among them, peeling between the layers, This prevents the strength, impact resistance, heat shock resistance, and the like from being lowered.
A fiber reinforced composite molded article 1 in the example of FIG. 1 is formed by laminating and integrating a plurality of layers of fiber reinforced composite materials as a basis of the fiber reinforced composite material layer 2 with reference to FIG. The formed flat prepreg 4 can be manufactured by first press-molding it into a predetermined three-dimensional shape and then injection-molding a thermoplastic resin containing the filler 3 as indicated by white arrows.

Alternatively, referring to FIG. 2 (b), a white arrow is first applied to a flat prepreg 4 formed by laminating and integrating a plurality of layers of fiber reinforced composite material that is the basis of the fiber reinforced composite material layer 2. As shown in Fig. 1, the fiber reinforced composite molded article 1 shown in Fig. 1 can be manufactured by injection molding a thermoplastic resin containing the filler 3 and then press molding it into a predetermined three-dimensional shape.
In any case, a plurality of layers of fiber reinforced composite material that is the basis of the fiber reinforced composite material layer 2 is added to the thermoplastic resin contained in each fiber reinforced composite material, and the fiber reinforced composite material is injected by injection molding. , And a thermoplastic resin permeated into the fiber reinforced composite material, and a filler 3 penetrating the laminated at least two layers of the fiber reinforced composite material, so that there is no separation during the production. The fiber reinforced composite molded article 1 of the example of FIG. 1 can be manufactured.

In the press molding process, the flat prepreg 4 is heated to the vicinity of the melting point of the thermoplastic resin using, for example, an oven or an infrared heater and softened or melted, and then pressed into a predetermined three-dimensional shape using a mold. What is necessary is just to shape | mold.
When injection molding is performed after press molding, a mold for injection molding is used in the press molding process, the prepreg 4 is press-molded using the clamping force of the mold, and the thermoplastic containing the filler 3 is then used. By injection molding the resin, the fiber reinforced composite molded product 1 can be easily and efficiently manufactured with fewer steps.

Examples of the fiber sheet on which the fiber reinforced composite material layer 2 is based include woven fabrics, nonwoven fabrics, strands, and the like made of various fibers such as carbon fibers, glass fibers, and aramid fibers. The type of the fiber sheet can be appropriately changed according to the three-dimensional shape and structure of the fiber reinforced composite molded article 1.
Examples of the thermoplastic resin impregnated into the fiber sheet include general thermoplastic resins such as polyamide 66, polyphenylene sulfide (PPS), thermoplastic polyurethane (TPU), and polyetheretherketone (PEEK). The kind of thermoplastic resin can be appropriately changed according to the strength, heat resistance, and the like required for the fiber-reinforced composite molded article 1.

Examples of the thermoplastic resin to be injection-molded include the same type or different types of thermoplastic resins having good compatibility with the thermoplastic resin impregnated in the fiber sheet. The same kind of thermoplastic resin is particularly preferable.
However, as the thermoplastic resin to be injection molded, it is necessary to select and use a resin having a higher melt flow rate than the thermoplastic resin impregnated into the fiber sheet.

By injection-molding a thermoplastic resin having a large melt flow rate and excellent fluidity, the thermoplastic resin and the filler 3 are satisfactorily permeated into the interlayer of the fiber reinforced composite material and the fiber reinforced composite material, Peeling between layers can be prevented even better.
In view of this effect, it is preferable to use a thermoplastic resin to be injection-molded having a melt flow rate of 30 g / 10 min or more, particularly 50 g / 10 min or more. If the melt flow rate is less than this range, the thermoplastic resin and the filler 3 can be satisfactorily permeated into the fiber-reinforced composite material and between the fiber-reinforced composite material, and the effect of preventing separation between layers cannot be obtained. There is a fear.

Examples of the filler 3 include various fillers in the form of fibers or plates that can penetrate at least two laminated fiber reinforced composite material layers 2 and reinforce the bonding between the two layers.
In particular, long-fiber carbon fibers are preferred. Since carbon fiber itself has high strength and can be penetrated through two or more laminated fiber-reinforced composite material layers 2 by making it into a long fiber, it has an excellent bonding reinforcing effect.

In order to obtain the above effect, the fiber length of the long fiber such as carbon fiber is preferably not less than the thickness of the fiber reinforced composite material layer 2 and not more than 2 mm. The fiber length is preferably 2 mm or less in order to disperse the fibers in the fiber-reinforced composite material layer 2 as smoothly and uniformly as possible by injection molding.
The plate-shaped prepreg 4 has a melting point of the thermoplastic resin under pressure using a hot press in a state where a plurality of fiber reinforced composite materials obtained by impregnating a fiber sheet with a thermoplastic resin, for example, are overlapped as in the past. By heating up to the vicinity and melt-integrating the thermoplastic resin in each fiber-reinforced composite material, the overlapped fiber-reinforced composite material can be integrated and formed with the thermoplastic resin.

FIG. 3 (a) is a cross-sectional view of another example of the embodiment of the fiber reinforced composite molded article manufactured by the manufacturing method of the present invention, and FIG. 3 (b) is a part of FIG. 3 (a). It is expanded sectional drawing. FIG. 4 is a perspective view of the fiber-reinforced composite molded product of FIGS. 3 (a) and 3 (b).
With reference to FIGS. 3A and 3B and FIG. 4, the fiber-reinforced composite molded article 1 of this example includes a cylindrical body 5. The cylindrical body 5 has an arc-shaped cross-sectional shape corresponding to a half circumference, and both ends of the circular arc are bent radially outward over the entire axial length of the cylindrical body 5 to form a flat plate-like connecting portion. The two half cylinders 7, which are 6, are formed by joining the side surfaces of the connection portion 6.

The entire semi-cylindrical body 7 including the connection portion 6 includes a fiber reinforced composite material layer 2 in which a plurality of layers obtained by impregnating a fiber sheet with a thermoplastic resin are laminated and integrated through the thermoplastic resin.
In addition, the laminated fiber reinforced composite material layer 2 of the laminated layers is reinforced by the filler 3 that randomly penetrates at least two of the fiber reinforced composite material layers 2 among them, peeling between the layers, This prevents the strength, impact resistance, heat shock resistance, and the like from being lowered.

Further, the two fiber reinforced composite material layers 2 constituting the side surface of the connecting portion 6 and laminated to bond the connecting portions 6 to each other are also integrated with each other through the thermoplastic resin. Bonds are reinforced by fillers 3 that are randomly penetrated through the fiber-reinforced composite material layer 2 that is included, thereby preventing the half cylinders 7 from being separated from each other.
The connecting portion 6 that protrudes radially outward of the cylindrical body 5 in the coupled state is covered with a rib 8. The rib 8 is provided over the entire axial length of the cylindrical body 5. Thereby, the coupling | bonding of the connection parts 6 is further reinforced and peeling can be prevented still more reliably.

At an intermediate position in the circumferential direction of the two ribs 8 on the outer periphery of the cylindrical body 5, a rib 9 is provided in parallel with the rib 8 over the entire axial length of the cylindrical body 5. In addition, annular ribs 10 are provided over the entire circumference of the cylindrical body 5 so as to be orthogonal to the ribs 8 and 9 at both ends in the axial direction of the outer periphery of the cylindrical body 5 and at intermediate positions thereof.
Each of the ribs 8 to 10 is formed of a thermoplastic resin integral with the thermoplastic resin forming the cylindrical body 5 as a structural portion.

The inner periphery of the cylindrical body 5 is covered with a coating 12 so as to fill the concave portion 11 including the concave portion 11 generated by bending the connecting portion 6 radially outward. Thereby, the inner periphery of the cylindrical body 5 can be smoothed, and for example, sliding characteristics with other members can be improved.
The coating 12 is formed of a thermoplastic resin integral with the thermoplastic resin forming the cylindrical body 5 as a structural portion.

Such a fiber-reinforced composite molded product can be used as various housings such as a rack housing of an automobile.
5 (a) and 5 (b), respectively, two flat prepregs 4 that form the base of the semi-cylindrical body 7 are press-molded and bonded to the shape of the semi-cylindrical body 7, and further a thermoplastic containing a filler. It is sectional drawing explaining an example of the process which forms the cylinder 5 by injection-molding resin, and manufactures the fiber reinforced composite molded product of Fig.3 (a) (b).

Referring to FIG. 5 (a), in this example, an injection mold 13 is used to perform the press molding and injection molding processes.
The mold 13 includes a columnar inner mold 14 having an outer diameter corresponding to the inner diameter of the cylindrical body 5 and two sets of outer molds 15.
Further, the outer mold 15 is provided with a mating surface 16 to be brought into contact with each other at the time of clamping, and is recessed from the mating surface 16 so as to have an inner diameter corresponding to the outer diameter of the cylindrical body 5 and a cylinder. A semicircular arc-shaped concave portion 17 having a length corresponding to the entire axial length of the body 5 is formed.

The outer mold 15 is also formed with concave grooves 18 to 20 corresponding to the ribs 8 to 10 so as to communicate with the concave portion 17. That is, in the opening of the concave portion 17 at the mating surface 16, a concave groove 18 having a depth corresponding to half the thickness of the rib 8 and extending over the entire length of the concave portion 17 is formed.
In addition, a concave groove 19 corresponding to the rib 9 and extending over the entire length of the concave portion 17 is formed in the innermost portion of the concave portion 17. Further, arc-shaped concave grooves 20 corresponding to the ribs 10 are formed at a plurality of locations in the concave portion 17 in the axial direction of the cylindrical body 5.

Further, in the drawing, the right outer mold 15 is connected to the tip of a nozzle of an injection molding machine (not shown) and is provided with a gate 21 for injecting a thermoplastic resin containing a filler into the mold 13. .
In order to manufacture the fiber-reinforced composite molded article shown in FIGS. 3A and 3B using such a mold 13, first, two flat prepregs 4 that are the basis of the half cylinder 7 are prepared.

The plate-shaped prepreg 4 has a melting point of the thermoplastic resin under pressure using a hot press in a state where a plurality of fiber reinforced composite materials obtained by impregnating a fiber sheet with a thermoplastic resin, for example, are overlapped as in the past. By heating up to the vicinity and melt-integrating the thermoplastic resin in each fiber-reinforced composite material, the overlapped fiber-reinforced composite material can be integrated and formed with the thermoplastic resin.
Next, the prepared two flat prepregs 4 are heated to the vicinity of the melting point of the thermoplastic resin using, for example, an oven or an infrared heater, and softened or melted. Insert between.

Next, referring to FIG. 5 (b), the two sets of outer molds 15 are clamped together with the mating surfaces 16 sandwiching the inner mold 14 therebetween, so that each prepreg 4 is a semi-cylindrical body. 7 and press-molded into the shape of 7 and joined to each other at the connecting portion 6.
Then, as indicated by white arrows in the figure, a thermoplastic resin containing the filler 3 is injected into the mold 13 through the gate 21.

  Then, in addition to the thermoplastic resin contained in each fiber reinforced composite material, a plurality of layers of fiber reinforced composite materials that are the basis of the fiber reinforced composite material layer 2 are injected between the fiber reinforced composite materials and fibers. The thermoplastic resin infiltrated into the reinforced composite material and the filler 3 penetrating the laminated at least two layers of fiber reinforced composite material are more firmly bonded to each other without causing separation during the production. The half cylinder 7 which becomes the basis of the body 5 can be formed.

Along with that, the two-layer fiber reinforced composite material that forms the side surface of the connection portion 6 and is laminated to bond the connection portions 6 to each other is bonded through a thermoplastic resin, and the fiber reinforcement including the two layers is also provided. The bonding is reinforced by the filler 3 penetrating the composite material, so that the half cylinders 7 can be integrated without causing separation or the like.
Therefore, it is possible to form a cylindrical body 5 that cannot be formed only by pressing one prepreg 4.

In addition, for example, conventionally, three steps of press molding, insert molding, and welding are required, and the formation of the cylindrical body 5 that requires separate apparatuses is performed using a single mold 13 as described above. Can improve productivity.
In addition, it is possible to reliably prevent the separation at the base portion of the connection portion 6 and the like by the bonding by the thermoplastic resin and the reinforcement by the filler 3, which are easy to cause separation between layers in the conventional method.

In addition, since the thermoplastic resin is also filled in the concave grooves 18 to 20 and the concave portion 11, the ribs 8 to 10 and the coating 12 as the structural portion are simultaneously formed with the cylindrical body 5 made of the fiber reinforced composite material layer 2. And can be formed integrally.
As the fiber sheet that becomes the basis of the fiber reinforced composite material layer 2, the thermoplastic resin impregnated in the fiber sheet, the thermoplastic resin that is injection-molded, and the filler 3, those described above can be used.

The configuration of the present invention is not limited to the examples in the drawings described above, and is composed of a fiber reinforced composite material using a thermoplastic resin, and is applied to the manufacture of fiber reinforced composite molded products having various three-dimensional shapes and structures. can do. In addition, according to the present invention, it is also possible to manufacture a fiber-reinforced composite molded product having a three-dimensional shape and structure that could not be formed conventionally.

  1: Fiber reinforced composite molded product, 2: Fiber reinforced composite material layer, 3: Filler, 4: Pre-preg, 5: Cylindrical body, 6: Connection part, 7: Half-cylindrical body, 8-10: Rib, 11: Recessed part, 12: coating, 13: mold, 14: inner mold, 15: outer mold, 16: mating surface, 17: recessed portion, 18-20: recessed groove, 21: gate

Claims (3)

A fiber-reinforced composite material layer obtained by impregnating a fiber sheet with a thermoplastic resin, laminated with at least two layers having a three-dimensional shape including a bent portion, and integrated through the thermoplastic resin, and at least two layers laminated A method for producing a fiber-reinforced composite molded article comprising a filler that penetrates the fiber-reinforced composite material layer and reinforces the bonding between the layers,
A step of press-molding a flat prepreg formed by laminating and integrating at least two layers of fiber-reinforced composite material that is the basis of the fiber-reinforced composite material layer into a three-dimensional shape including a bent portion; and
A process of injection-molding a thermoplastic resin containing a filler and having a higher melt flow rate than a thermoplastic resin impregnated in a fiber sheet into a prepreg at any stage before or after press molding
Fiber-reinforced method for producing a composite molded article comprising a. In the press molding process, the manufacturing method of the fiber-reinforced composite molded article according to claim 1 for coupling at least two prepregs. The method for producing a fiber-reinforced composite molded article according to claim 1 or 2 , wherein the injection molding is performed after the press molding, and the structural portion made of the thermoplastic resin is integrally molded in the injection molding process.

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