JPH1015970A - Production of fiber reinforced plastic product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the number of processes for producing an FRP molded product by arranging a shell produced from a resin of which the adhesiveness with a matrix resin of fiber reinforced plastic is low in a mold to inject a matrix resin in the shell, and taking out the shell from the mold to take out a molded product from the shell. SOLUTION: A reinforcing material preform 1 is set within upper and lower shells 2, 3 made of polypropylene, two upper and lower shells 2, 3 are assembled by a clamp, and the shells 2, 3 to which the preform 1 is set are arranged in upper and lower molds 4, 5. Thereafter, the upper and lower molds 4, 5 are clamped and a polyester resin mixed with a curing agent is sent into the molds from a resin injection port 7 under pressure while a pressure reducing hole 6 is reduced in pressure by a vacuum pump. After the gelling of the resin is confirmed, the shells 2, 3 are taken out of the molds 4, 5 to be held in a high temp. tank and gradually cooled to room temp. and, when temp. falls, FRP is taken out of the shells 2, 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for molding and manufacturing a fiber-reinforced plastic, and more particularly, to a method for easily removing a fiber-reinforced plastic molded product, setting a preform, and facilitating post-curing. And a method for efficiently forming and manufacturing FRP.

[0002]

[Prior Art] Fiber Reinforc
For molding and production of ed Plastic (hereinafter simply referred to as FRP), a hand lay-up method using only one of male and female molds, a spray-up method similar thereto, a cold press using a pair of male / female dies or Using a press method called hot pressing, using only a pair of male / female or female molds,
After setting the reinforcing material preform in the mold, the resin is injected by RTM (Resin Transfer Molding) method, and the FW (Fila) that winds the reinforcing material impregnated with resin around the mandrel
ment Winding) method is used. Of these, the cold press method, hot press method, and RTM method use FR.
Resin mold, concrete mold, FRP mold,
A heavy mold such as an electroforming mold or a metal mold is used.

[0003] As a matrix resin of FRP, polyester, vinyl ester, epoxy resin and the like are generally used. However, such a matrix resin is required to have a high bonding force with a reinforcing material. The adhesion between the material and the mold surface material is also extremely high. For this reason, a sufficient mold release treatment is required in the molding of FRP. Conventionally, FRP cured in a mold is released by applying a release wax or various release agents to the surface of a mold.

[0004]

[0005] Depending on the type of FRP base resin, the mold, and the type of molding method, it is necessary to release the mold every time. Even in a state well controlled by the RTM method, it is necessary to perform a release treatment every 50 to 70 times of molding. This release process relies exclusively on manual labor, and careful release process requires a long time and a lot of labor, which is one of the major factors hindering efficient molding and production of FRP. . If the release treatment is insufficient, F
It becomes difficult to remove the RP and it takes time,
It often damages the mold. In particular, a mold having sharp edges and thin ribs is often damaged by insufficient release treatment.

As the size of the FRP molded product increases, the size of the mold increases in proportion to the square to the cube of the dimension of the molded product.
When the FRP molded product is large, it takes time to set the reinforcing material preform in the mold. For operations other than direct molding operations such as resin injection and curing, expensive molds are occupied for a long time. The same applies to the case where a gel coat is applied to the mold surface.

In any of the cold pressing, hot pressing and RTM forming methods, it is necessary to sufficiently cure the FRP in a mold until the shape of the formed FRP becomes stable. For this reason, the time for occupying the mold becomes longer than when the reinforcing material preform is set, and it is not possible to prepare for the next molding until the FRP molded product is completely removed from the mold. In the RTM method, the mold can be placed in a high-temperature bath for the purpose of accelerating the curing of the resin in the mold. At this time, after the FRP molded product is removed from the mold, the next operation may not be performed until the temperature of the mold is lowered. Even in this case, there is a problem that effective use of the mold and efficient production of FRP are hindered.

An object of the present invention is to provide an FRP molding by cold press method, hot press method, and RTM method.
An object of the present invention is to reduce the number of steps in the manufacturing process of a P molded product. Another object of the present invention is to extend the life of a mold. Still another object of the present invention is to provide an efficient method for producing an FRP molded product.

[0008]

A method of manufacturing a fiber reinforced plastic product according to the first aspect includes the following steps. -Molding using at least one shell having the same shape as the outer shape or inner shape of the fiber reinforced plastic product at least on the surface of which is covered with a resin having low adhesiveness to the base resin of the fiber reinforced plastic product, for manufacturing the fiber reinforced plastic product Shell placement process to place in the mold.

A molding step including a step of injecting a base resin and a step of clamping. ○ Release process for removing the shell from the mold. ○ Demolding process to remove the molded product from the shell. The method for producing a fiber-reinforced plastic product according to claim 2 is the method for producing a fiber-reinforced plastic product according to claim 1, wherein before the shell disposing step,
Disposing a reinforcement preform of a fiber reinforced plastic product in the shell.

In a third aspect of the present invention, there is provided a method of manufacturing a fiber reinforced plastic according to the first or second aspect, wherein the base resin of the fiber reinforced plastic product to be molded is completely cured before the demolding step. Removing the shell from the mold and post-curing outside the mold. ******** Here, the shell may be entirely formed of a resin having low adhesion to a matrix resin of a fiber-reinforced plastic, A structure in which the resin is covered with a surface formed of a metal material may be used. The resin forming the shell is not particularly limited as long as it is a resin having extremely low adhesiveness to polyester, vinyl ester, and epoxy resins, which are base resins of fiber reinforced plastic, and examples thereof include polyolefin resins. For example, the polypropylene shell has extremely poor adhesion to the base resin of the FRP, and the FRP molded product in the shell can be easily removed from the shell without performing a special release treatment on the surface of the shell. The shell can be any thickness. The molding pressure is supported by the mold. Therefore, the shell only needs to have such a strength that the shell is not broken by the molding pressure in the state of being placed in the mold. The shell is made by injection molding, or vacuum or air pressure molding. It may be manufactured by other methods.

[0011] When a shell that is sufficiently thicker than the shell shape and has high rigidity is used, the shape can be maintained even outside the mold, and the preform can be placed inside the shell without disposing the shell inside the mold. Can be set first. When used in the RTM method, a resin injection hole or opening is provided in the shell. Also, a groove for soft pinch and a resin reservoir can be provided. Regardless of the molding method, the shell is removed from the mold and post-cured outside the mold before the resin inside the shell is completely cured, at the stage of gelation, or at the stage where the shape of the FRP molded product has been cured enough to maintain the shape. Can be.

It is sufficient that all the molds can hold the shell accurately. The surface of the mold holding the shell does not require special treatment. It is sufficient that the molding die has sufficient strength to withstand molding pressure and rigidity to maintain accuracy. In the molding process, the F is pressed in the shell by cold pressing, hot pressing or RTM.
Form the RP.

The surface of the shell in contact with the FRP molded product is FR
To make it smooth corresponding to the surface roughness of the P molded product.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 An example in which the present invention is applied to a manufacturing method for forming an FRP by an RTM method will be described. 1 to 3 show a diameter 2 to which the present invention is applied.
RTM of thin FRP cylindrical container with 5cm and 10cm depth
3 shows a molding process. The thickness of the FRP is 3 mm, the width of the flange is 2 cm, and the thickness is 1 mm. The reinforcing material was a plain weave glass cloth with a thickness of 3 mm and 12 sheets were used, and a binder was applied to perform the preform. Unsaturated polyester was used as the base resin. The shell was produced by injection molding using polypropylene as a material. The thickness is 2 mm. The molding die was made of epoxy resin concrete, and a polypropylene shell was used as a mold on the side where the shell was placed in order to accurately hold the shell made of polypropylene. Since there is no need for special surface finishing, the cost of the mold was less than 1/3 of the cost of the conventional mold.

First, as shown in FIG. 1, the reinforcing material preform 1 is set in upper and lower shells 2 and 3 made of polypropylene, and the upper and lower shells 2 and 3 are assembled by a clamp.
Next, as shown in FIG. 2, the shells 2 and 3 on which the preforms are set are placed in upper and lower molds 4 and 5, respectively. Thereafter, the upper and lower molding dies 4 and 5 are clamped with a shank and the like, and the polyester resin already mixed with the curing agent is pressure-fed from the resin injection hole 7 while the pressure reducing hole 6 is connected to a vacuum pump (not shown) to reduce the pressure. After confirming that the resin comes out from the decompression hole 6, the pressure feeding of the resin is stopped. After 20 minutes, it was confirmed that the resin had gelled, and the shells 2 and 3 were removed from the molds 4 and 5 and heated at 80 ° C.
For 1 hour. Then, slowly cool at room temperature,
When the temperature has dropped, the FRP is removed from the shells 2 and 3. At this time, the mold could be easily removed by sending compressed air from the resin injection hole 7.

The surface of the FRP thus formed was as smooth as the surface of the shell. In the mold,
The FRP base resin did not adhere. When the shell is removed from the mold, the next molding step can be prepared. Since the shell was very light, it was easy to set the preform. The shell survived more than 20 repetitions. The following preforms can be prepared during post-curing, no release processing is required, the FRP molded product is easily released from the mold, and the post-curing does not occupy the molded product.
The productivity in one mold has tripled from the conventional one. In addition, the division of the molding work was achieved, and the production efficiency was more than doubled. No repair of the mold was necessary.

Example 2 An example in which the present invention is applied to a manufacturing method for forming an FRP by a cold press method will be described. 4 to 6 show a cold press forming process of a thin FRP cylindrical container to which the present invention is applied. The molded article has the same dimensions as in Example 1. The same shell as in Example 1 was used. However, unlike RTM molding,
Since no resin is injected, the resin injection hole and the reduced pressure hole are closed. The same molding die as in Example 1 was used.

First, as shown in FIG. 4, the upper shell 2 made of polypropylene is attached to the upper mold 4 by a clamp. The reinforcing material preform 1 was set in the lower shell 3, and then placed in the lower mold 5. Since the lower mold 5 is a female mold, the lower shell 3 is simply fitted into the mold 5. Next, as shown in FIG. 5, a polyester resin mixed with a curing agent is sprayed on the preform 1. After spraying the required amount of resin, the upper mold 4 is
T with a hydraulic press. Excess resin accumulates in the resin reservoir for soft pinch. After 20 minutes, it was confirmed that the resin had gelled, and the upper and lower shells 2 and 3 were taken out of the molds 4 and 5, clamped, and left in the high-temperature bath 8 at 80 ° C for 1 hour. Thereafter, the mixture is gradually cooled at room temperature, and the FRP is taken out of the shells 2 and 3 when the temperature has dropped. Hereinafter, it is the same as the first embodiment. The effect of the present invention on improving the production efficiency was the same as that of Example 2.

[0019]

As described above, according to the present invention, there is no need to release the FRP mold in the FRP molding by the cold press method, the hot press method, or the RTM method, and the life of the mold is improved. Further, it is possible to reduce the mold occupation time due to the curing of the FRP molded product. Furthermore, it is possible to reduce the mold occupation time associated with the application of the gel coat and the setting of the reinforcing material preform, and it is possible to efficiently produce the FRP.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a manufacturing method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a manufacturing method according to the first embodiment of the present invention.

FIG. 3 is a diagram showing a manufacturing method according to the first embodiment of the present invention.

FIG. 4 is a diagram showing a manufacturing method according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a manufacturing method according to a second embodiment of the present invention.

FIG. 6 is a diagram showing a manufacturing method according to a second embodiment of the present invention.

[Explanation of symbols]

 1 Reinforcement preform 2,3 Shell 4,5 Mold

Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location // B29K 101: 10 105: 06

Claims (3)

[Claims] At least one shell made of a resin having low adhesion to a matrix resin of the fiber reinforced plastic and having the same shape as the outer shape or inner shape of the fiber reinforced plastic product is manufactured by manufacturing the fiber reinforced plastic product. A shell disposing step of disposing in a molding die used for forming, a molding step including a step of injecting a base material resin and a step of clamping, a mold releasing step of removing the shell from the molding die, And a method for producing a fiber-reinforced plastic product comprising: 2. The method of claim 1, further comprising the step of placing a reinforcing material preform of the fiber reinforced plastic product in the shell prior to the step of placing the shell. 3. The method according to claim 3, further comprising, before the demolding step, removing a shell from the mold before the matrix resin of the fiber-reinforced plastic product to be molded is completely cured, and post-curing the shell outside the mold. A method for producing the fiber-reinforced plastic according to claim 1.