JP6876516B2 - Fiber-reinforced resin member and method for manufacturing the fiber-reinforced resin member - Google Patents

Description

The present invention relates to a fiber-reinforced resin member, and more particularly, relates to a fiber-reinforced resin member having high mechanical strength and capable of being formed into a desired shape, and a method for producing the fiber-reinforced resin member.

In order to increase the mechanical strength of the fiber reinforced resin member, continuous long reinforcing fibers are used. However, molding by the injection molding method requires kneading using a screw, and since the fibers are sheared short during kneading, the reinforcing fibers cannot be lengthened, and there is a limit in improving the mechanical strength. ..

In Japanese Patent Application Laid-Open No. 2012-71595 of Patent Document 1, a preformed body made of a reinforcing fiber and a thermoplastic resin is arranged in a cavity of a mold, and a discontinuous reinforcing fiber is contained in the remaining space of the cavity. A molding method for injecting a molten thermoplastic resin and further compressing the cavity to a predetermined volume is disclosed.

Then, according to the molding method, it is described that fibers longer than the discontinuous reinforcing fibers can be used in the preformed body.

Japanese Unexamined Patent Publication No. 2012-71595

However, in the case described in Patent Document 1, since a single preformed body is used, the shape that can be molded is limited to a simple shape such as a hat shape, and a molded product having a complicated shape is formed. It's difficult to do.

The present invention has been made in view of the problems of the prior art, and an object of the present invention is to reinforce a fiber having high mechanical strength that can be formed into a desired shape even if it has a complicated shape. The purpose is to provide a resin member.

As a result of diligent studies to achieve the above object, the present inventor has a plurality of preformed bodies having different fiber lengths depending on the complexity of the shape of the molded product (hereinafter, may be referred to as prepreg). We have found that the above object can be achieved by using the above, and have completed the present invention.

That is, the fiber reinforced member of the present invention has a complicated shape portion and a simple shape portion.
The fiber-reinforced resin member has a backing layer and a fiber-reinforced layer in this order in the thickness direction, and the average fiber length of the fiber-reinforced layer is shorter in the complicated shape portion than in the simple shape portion.

Further, the method for manufacturing a fiber reinforced resin member of the present invention is a method for manufacturing a fiber reinforced resin member having a complicated shape portion and a simple shape portion.
An arrangement process in which a prepreg containing reinforcing fibers and a resin is placed in a mold, and a molding process in which the prepreg is pressed against the inner surface of the mold and the resin is injected into the mold to be lined. Has.
The arrangement step is a process of arranging a plurality of prepregs having different average fiber lengths. The prepregs having a long average fiber length are arranged in the simple shape portion, and the prepregs having a short average fiber length are arranged in the complex shape portion. It is characterized by.

According to the present invention, since the fiber length of the complex shape portion is made shorter than the fiber length of the simple shape portion, it is possible to provide a fiber reinforced resin member having high mechanical strength that can be formed into a desired shape. ..
Further, since the prepreg having a long average fiber length is arranged in the simple shape portion and the prepreg having a short average fiber length is arranged in the complicated shape portion, the high-strength fiber-reinforced resin member can be formed into a desired shape.

It is a perspective view which shows an example of the fiber reinforced resin member of this invention. FIG. 1 is a cross-sectional view taken along the line AA'in FIG. It is a figure explaining the arrangement process. It is a figure explaining the molding process.

The fiber reinforced resin member of the present invention will be described in detail. FIG. 1 shows a perspective view of the fiber reinforced resin member of the present invention.

As shown in FIG. 1, the fiber reinforced resin member 1 has a complicated shape portion 12 and a simple shape portion 11, and the cross section thereof is in the thickness direction of the fiber reinforced resin member as shown in FIG. The lining layer 3 and the fiber reinforced layer 2 are provided in this order, and the fiber reinforced layer is reinforced with a lining layer containing a resin.

In the present invention, the complicated shape portion is a portion where it is difficult to bend the fibers in the prepreg to follow the mold, and although it depends on the thickness of the fiber reinforced layer and the like, for example, at a steep angle of 60 ° or more. It refers to a portion where the outer shape of the fiber reinforced resin member is formed by the mountain fold line Y and the valley fold line V of the folded fiber reinforced layer and the intersection X of these fold lines. Further, the simple shape portion is a portion where the fibers in the prepreg can be easily bent to follow the mold, and the portion where the mountain fold line Y and the valley fold line V do not intersect.

<Fiber reinforced layer>
The fiber-reinforced layers 2a and 2b are on the surface side of the fiber-reinforced resin member 1, and the surface thereof forms the appearance of the fiber-reinforced resin member, and is a layer containing reinforcing fibers in the resin.

The reinforcing fibers of the fiber reinforcing layer have a shorter average fiber length of the complex shape portion 12 than that of the simple shape portion 11. Since the reinforcing fibers of the simple shape portion are long, the mechanical strength of the fiber reinforced resin member can be improved.
Since the reinforcing fibers of the complicated shape portion 12 are shorter than the reinforcing fibers of the simple shape portion 11, the reinforcing fibers can be displaced from each other even if they are bent by a mold at the time of molding. Therefore, even if the shape is complicated, the stress due to bending does not concentrate at one point following the shape of the mold, so that gaps are unlikely to occur between the reinforcing fibers, and the resin of the lining layer passes through the fiber reinforcing layer and reaches the surface. It is prevented from being exposed.

The fiber reinforcing layer 2a of the simple shape portion preferably contains reinforcing fibers such as a woven fabric or a unidirectional material. When the reinforcing fibers are continuous long fibers that are regularly oriented, the load can be distributed within the long reinforcing fibers, so that the mechanical strength is improved.

Further, the fiber reinforcing layer 2b of the complicated shape portion preferably contains the reinforcing fibers contained in the prepreg produced by the LFT-D method and the reinforcing fibers having a random orientation such as a non-woven fabric.
Reinforcing fibers in complex shapes need to follow the complex shape of the mold, and the random orientation of the reinforcing fibers makes them more likely to shift against bending in all angular directions, compared to regularly oriented reinforcing fibers. It is possible to form a complicated shape.

Here, in the LFT-D (Long Fiber Thermoplastics-Direct) method, continuous fibers and a thermoplastic resin are introduced into an extruder, and the screw of the extruder is rotated to cut the continuous fibers into a thermoplastic resin. A method of extruding a kneaded kneaded material and then press-molding it.

The fiber length of the reinforcing fiber in the complicated shape portion is preferably more than 3 mm and 30 mm or less, although it depends on the complexity of the shape and the thickness of the fiber reinforcing layer. When the length is in the above range, it is possible to achieve both mold followability and mechanical strength.

Further, it is preferable that the fiber reinforcing layer 2b of the complicated shape portion has a fiber content lower than that of the fiber reinforcing layer 2a of the simple shape portion. The sparseness of the reinforcing fibers improves the followability to the mold.

Further, it is preferable that the fiber reinforcing layer 2b of the complicated shape portion is thicker than the fiber reinforcing layer 2a of the simple shape portion. The thick fiber reinforced layer can prevent the resin in the lining layer from passing through.

In the fiber reinforcing layer 2, it is preferable that the fibers of the complex shape portion and the fibers of the simple shape portion overlap at the boundary between the complex shape portion 12 and the simple shape portion 11. By overlapping the fibers of the complicated shape portion and the fibers of the simple shape portion, the continuity of the fibers is not interrupted, and the decrease in strength can be prevented.
The overlapping width of the fibers is preferably 30 mm to 100 mm, although it depends on the purpose of use of the fiber reinforced resin member and its shape.

As the reinforcing fiber, carbon fiber or glass fiber can be used. The carbon fibers are not particularly limited, and any of PAN-based carbon fibers made from PAN precursor (polyacrylonitrile fiber), pitch-based carbon fibers made from coal tar, and rayon-based carbon fibers may be used. , If necessary, different types of carbon fibers may be used in combination.

As the resin, a thermoplastic resin can be used, for example, a polyamide resin such as nylon 6 and nylon 66, a polyolefin resin such as polyethylene and polypropylene, a polyester resin such as polyethylene terephthalate and polybutylene terephthalate, and poly. Examples thereof include ether ketone, polyether sulphon, aromatic polyamide, and the like. Among them, nylon 6 has excellent moldability and can be preferably used.

The fiber reinforcing layer can be formed by using a prepreg containing reinforcing fibers in a matrix resin of a thermoplastic resin.

<Backing layer>
The lining layer 3 is a layer for improving the mechanical strength of the fiber reinforced resin member by joining the fiber reinforced layers with a resin from the back surface side of the fiber reinforced resin member 1.

As the resin constituting the backing layer 3, the same thermoplastic resin as the fiber reinforced layer 2 can be used, but it is preferable to use the same resin type as the resin type used for the fiber reinforced layer 2.

Further, the resin constituting the backing layer 3 may contain reinforcing fibers. The length of the reinforcing fibers in the lining layer is preferably 0.1 mm or more and 3 mm or less. If the length of the reinforcing fiber exceeds 3 mm, it becomes difficult to inject, and molding defects such as voids are likely to occur, which may cause a decrease in strength and a poor appearance.

The lining layer 3 may have a reinforcing shape such as a rib 31 if necessary. The position where the reinforcing shape is provided is not particularly limited, but it is preferable to have the reinforcing shape at the boundary where the fibers of the complex shape portion of the fiber reinforcing layer and the fibers of the simple shape portion overlap.

At the boundary portion, the fiber reinforcing layer may become thick and it may be difficult for the resin to flow when forming the lining layer. However, by having the reinforcing shape at the boundary portion, the portion where the reinforcing shape of the mold is formed is formed. The entire mold can be filled with resin through the mold.

<Fiber reinforced plastic member>
The fiber-reinforced resin member of the present invention has both moldability and mechanical strength, and can be used in the same manner as the conventional fiber-reinforced resin member in which the reinforcing fibers are only long fibers, and is a screw pin. It is also possible to join with other members by stopping, fusing, etc.

When used in combination with another member, it is preferable to provide the joint portion 4 with the simple shape portion 11, that is, the portion having a long average fiber length. High mechanical strength can be obtained by joining at the simple shape portion 11.

<Manufacturing method of fiber reinforced resin member>
The fiber-reinforced resin member includes a press molding method in which a prepreg containing reinforcing fibers and a thermoplastic resin is pressed with a mold to form a prepreg, and an injection molding method in which a molten thermoplastic resin is injected into a mold to form the prepreg. It can be manufactured by a hybrid injection press molding method that combines the above.

Specifically, it has an arranging step of arranging the prepreg 5 in the die 7 and a molding step of pressing the prepreg 5 with the die 7 and further injecting and lining the injection material 6 containing resin.

As shown in FIG. 3, the above arranging step is a step of arranging the preheated prepreg 5 in the mold 7 near the melting point of the impregnated resin in the prepreg. A prepreg containing reinforcing fibers having a long average fiber length is arranged, and a prepreg containing reinforcing fibers having a short average fiber length is arranged at a portion forming a complex shape portion.

As the prepreg containing the reinforcing fibers having a short average fiber length, those having notches and corner cuts can be used. By arranging the notch of the prepreg at the corner of the mold, the followability to the mold can be improved.

In the molding step, as shown in FIG. 4, the mold 7 on which the prepreg 5 is arranged is closed and pressed, the prepreg 5 is made to follow the shape of the mold 7, and the injection material 6 ( The backing material) is injected in the direction indicated by the arrow in FIG. 4, and the gap in the mold is filled with the injection material to line the product, and the molding process is performed.

At this time, the prepreg 5 in the mold is pressed against the mold by the injection material 6, and the dimensional accuracy of the molded product is improved. After that, when the mold cools and the resin solidifies, the mold is opened and the molded product is taken out.

Hereinafter, the present invention will be described in detail with reference to Examples, but the present invention is not limited to the following Examples.

[Example 1]
A prepreg A in which a woven fabric of carbon fibers was impregnated with nylon 6 and a prepreg B prepared by the LFT-D method containing carbon fibers in nylon 6 were preheated to 260 ° C.

The prepreg A was placed in the center of the mold, and the prepreg B was placed at both ends of the mold so that the overlap with the prepreg A was 50 mm.

The mold was closed and the prepreg was pressed to allow the prepreg to follow the shape of the mold. Further, an injection material (lining material) obtained by melting nylon 6 pellets containing carbon fibers was injected into the gaps of the mold, and the prepreg was pressed against the mold for lining.

After cooling the mold, the mold was released to obtain a fiber reinforced resin member having the shape shown in FIG.
In this fiber-reinforced resin member, the average fiber length of the reinforcing fibers in the simple shape portion was 1200 mm, the average fiber length of the reinforcing fibers in the complex shape portion was 10 mm, and the average fiber length of the reinforcing fibers in the lining layer was 0.2 mm. In addition, there was no place where the backing material passed through the fiber reinforced layer and was exposed on the front side.

[Comparative Example 1]
A fiber-reinforced resin member was obtained in the same manner as in Example 1 except that molding was performed using only prepreg A without using prepreg B.
In the fiber-reinforced resin member of Comparative Example 1, the backing material was exposed on the surface at 50% of the front side.

In Comparative Example 1, when the prepreg was pressed, the ability to follow the square shape of the die was poor, and the reinforcing fibers were torn to form a gap, and the backed injection material passed through the gap and was exposed to the surface. it is conceivable that.

1 Fiber reinforced resin member 11 Simple shape part 12 Complex shape part 2a Fiber reinforced layer 2b Fiber reinforced layer 3 Backing layer 31 Rib 4 Joint with other parts 5 Prepreg 6 Injection material (lining material)
7 Mold Y Mountain fold line V Valley fold line X Intersection

Claims (8)

A fiber reinforced resin member having a complicated shape portion and a simple shape portion.
It has a lining layer and a fiber reinforced layer in order in the thickness direction of the fiber reinforced resin member.
A fiber-reinforced resin member characterized in that the average fiber length of the reinforcing fibers of the fiber-reinforced layer is shorter in a complicated shape portion than in a simple shape portion. The fiber reinforcing layer of the simple shape portion contains the reinforcing fiber of the woven fabric and / or the unidirectional material.
The fiber-reinforced resin member according to claim 1, wherein the fiber-reinforced layer of the complicated shape portion contains reinforcing fibers having a random orientation. The fiber-reinforced resin member according to claim 1 or 2, wherein the fiber content of the complicated shape portion is lower than the fiber content of the simple shape portion. The fiber-reinforced resin member according to any one of claims 1 to 3, wherein the fiber-reinforced layer of the complicated shape portion is thicker than the fiber-reinforced layer of the simple shape portion. At the boundary between the complicated shape portion and the simple shape portion, the reinforcing fibers of the complex shape portion and the reinforcing fibers of the simple shape portion overlap each other.
The fiber-reinforced resin member according to any one of claims 1 to 4, wherein the lining layer has ribs at a boundary portion where reinforcing fibers overlap. The fiber-reinforced resin member according to any one of claims 1 to 5, wherein the simple shape portion is provided with a joint portion with another member. A method for manufacturing a fiber reinforced resin member having a complicated shape portion and a simple shape portion.
The arrangement process of arranging the prepreg containing the reinforcing fiber and the resin in the mold,
It has a molding process of pressing the prepreg and pressing it against the mold, injecting resin into the mold, and lining the mold.
The above-mentioned arrangement step is a process of arranging a plurality of prepregs having different average fiber lengths of reinforcing fibers.
A method for manufacturing a fiber-reinforced resin member, characterized in that a prepreg having a long average fiber length of reinforcing fibers is arranged in a simple shape portion and a prepreg having a short average fiber length of reinforcing fibers is arranged in a complicated shape portion. The prepreg having a short average fiber length of the reinforcing fibers has notches and / or corner cuts.
The method for manufacturing a fiber reinforced resin member according to claim 7, wherein the arranging step includes a process of arranging the cuts and / or corner cuts at the corners of the mold.

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