JPH0767751B2 - Manufacturing method of fiber reinforced plastics - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing fiber reinforced plastics (hereinafter simply referred to as FRP) in which a fiber cloth is impregnated with a resin.

[0002]

FRP is manufactured by impregnating a fiber cloth such as glass fiber with a synthetic resin such as epoxy resin. Then, generally, the fiber cloth is set in a mold to make the mold substantially vacuum,
A method in which a fiber cloth is impregnated with the synthetic resin is used. In this case, voids (air bubbles) may be mixed in the synthetic resin or between the fibers even if the impregnation is performed in a substantially vacuum mold. Naturally, the inclusion of voids causes the deterioration of the electrical characteristics of the FRP.

[0003]

For this reason, conventionally, measures have been taken to increase the degree of vacuum in the mold as much as possible, and the impregnation of the synthetic resin takes time. Therefore, in the conventional FRP manufacturing method, there are problems that the manufacturing equipment becomes complicated and the manufacturing takes time.

In order to achieve the above object, in the invention of claim 1, a fiber cloth or the like is set in a molding die,
The capillary action of the resin liquid to the fiber cloth or the like of this
In the method of impregnation using the resin liquid level in the molding die, the resin liquid level in the molding die is 0.5 to 2.5 times as high as the initial rate of the liquid level of the resin rising on the fiber cloth by the capillary phenomenon. I tried to raise.

[0005]

Therefore, in the present invention, the fineness of the fiber cloth is
The liquid level of the resin in the gap rises uniformly due to the capillary action of the gap , and voids do not occur in the cloth . this
Therefore, even the degree of vacuum in the mold is not very high, or even without over time, can be performed impregnation of void-free resin.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will now be described with reference to FIGS.
This will be described in detail with reference to FIG. Generally, a fiber cloth bundles 50 to 800 single fibers of 5 to 20 μ to form a yarn. Then, this yarn is woven on a loom to be processed into a cloth. These fiber cloths used for impregnation are generally subjected to surface treatment in consideration of adhesiveness with resin and impregnation property.

Therefore, the impregnating ability of the resin to the fiber cloth changes depending on the type of surface treatment agent, the type of resin to be impregnated, the viscosity, and the like. For this reason, the inventor conducted a resin impregnation test based on the capillary phenomenon, and obtained the test results of FIGS. Therefore, this test and its results will be described. 3 (a) to 3 (c), each sample 4 made of fiber cloth is erected and held in a petri dish (not shown) under atmospheric pressure, and an epoxy resin liquid 5 (viscosity: 20 cpoise) is poured to a predetermined depth, and the test result of observing the capillary phenomenon is shown.
3A is a plain weave cloth made of polyester fiber, FIG. 3B is a plain weave cloth made of glass fiber, and FIG. 3C is a plain weave cloth made of glass fiber. Is.

According to this, each sample 4 is
Voids 6 are not formed in the cloth up to about 5 mm above the resin surface. The reason for this is that the file by capillary action
Speed of resin to increase the inter-Iba of cross information, click
Although the difference between the yarn forming the loss and the yarn is different, the speed difference is small near the liquid surface of the resin in the petri dish, so the rate of resin rise is relatively uniform, and the resin rises only by the action of capillary action. Therefore, it is considered that the air on the cloth is only pushed up and does not stay on the cloth.

On the other hand, 5 mm from the liquid surface of the resin in the petri dish
At the above parts, fiber voids are formed with voids formed .
Ross is impregnated with resin. As this rises, the difference between the ascending speed in the yarn and the ascending speed between the yarns increases, and along with this, it is considered that the resin that has risen earlier surrounds the unimpregnated part and the air bubbles are trapped there. . The voids of the samples of FIGS. 3A and 3B are small, and the voids of the sample of FIG. 3C are large. this is,
Since Menuki plain weave has a large space between the yarns than in the plain weave, the <br/> rising speed is slow, especially due to capillary action of the resin in the large space, large bubbles believed to be due to easily confined.

From the results of this test, the resin was not affected by the kind of cloth, and the resin was fiber- crossed by the capillary phenomenon.
When impregnated into the scan confirmed that no void is generated within the upper 5mm from resin liquid surface in the Petri dish. In addition, FIGS. 4 and 5 show the relationship between the rising height of the liquid surface of the epoxy resin which rises due to the capillary phenomenon and the time when the same test as the test condition shown in FIG. 3 was conducted. FIG. 4 and FIG. 5 show the rising height of the capillary resin liquid surface that is impregnated with the epoxy resin liquid until 10 minutes have elapsed since the fiber cloth made of polyester and the fiber cloth made of glass were impregnated with the epoxy resin liquid. The initial rising speed of the capillary resin liquid level in each sample is obtained.

Further, the inventor holds each sample having a length of 10 cm in an upright position in a glass cylinder under atmospheric pressure, and raises the epoxy resin liquid level which rises by capillary action and the poured epoxy resin liquid in the cylinder. A test was conducted in which the epoxy resin was poured so that there was no difference from the resin surface. As a result, no resin can also occur the voids in any of the samples of length 10cm was sure that impregnated.

[0012] From the above test, in the case of impregnation by A capillary action alone, petri dishes or syrups are used.
5 mm above the liquid surface of the resin inside the fiber
It names can lead to voids in the cross. B Capillary resin impregnation (capillary resin liquid level
Increased) to match the speed, registration of the dish or cylinder
When the liquid level is raised, no void is generated in the fiber cloth .

An embodiment based on this knowledge will be described below with reference to FIG.
This will be described with reference to FIG. FIG. 1 shows a molding die 11 and a core material 12.
And F formed by the molding die 11 and the core material 12.
RP13 is shown. The molding die 11 includes a cylindrical portion 14, and a lower cap 15 and an upper cap 16 screwed to a lower portion and an upper portion thereof. The molding die 11 is erected in a heating device (not shown). An injection pipe 17 for injecting a resin is connected to the lower cap 15, and an exhaust pipe 18 for exhausting air is connected to the upper cap 16. Recesses 19 and 20 for accommodating the ends of the core material 18 are formed in the inner centers of both caps 15 and 16, respectively.

A resin tank 21 for sending out resin is connected to the injection pipe 17, and a suction side of a vacuum pump 22 is connected to the exhaust pipe 18. Resin tank 21
A resin made of a liquid thermosetting epoxy resin is stored inside. Further, the resin tank 21 is provided with a vacuum pump 23 for discharging the air mixed in the resin and a resin stirring device 24. A tube pump 25 is arranged in the middle of the injection pipe 17 so that a fixed amount of resin can be supplied into the molding die 11. Further, a reservoir 26 for collecting the resin overflowing from the molding die 11 is arranged in the middle of the exhaust pipe 18. 32-36
Is a valve.

Next, a method for manufacturing an FRP by using the apparatus configured as described above will be described. First, a long cross 31 having a narrower width than the outer circumference of the cylindrical core 12 is formed.
Wrap a specified number of times. As the cloth 31, polyester fiber cloth or glass fiber cloth is used. The cloth 31 is a plain woven glass fiber having a thickness of 0.21 mm and a mass of 206 g square centimeter, and the surface treatment is a silane coupling treatment.

Next, the core 41 thus formed is
As shown in FIG. 1, the recesses 1 of the upper and lower caps 15 and 16
The upper and lower ends of the core material 12 are fitted into the core members 9 and 20, respectively, whereby the core member 12 is set upright in the molding die 11. With the above configuration, the vacuum pump 22 is driven with the valve 35 closed, the air in the molding die is discharged, and the molding die 11 is heated by the heating device (not shown).
Is heated. Further, in a state where the liquid resin is stored in the resin tank 21, the stirring device 24 and the vacuum pump 23
Is driven, and the resin is degassed under vacuum stirring. After the completion of the vacuum stirring and degassing, the valve 32 is closed, the stirring device 24 and the vacuum pump 23 are stopped, and the valves 34 and 36 are opened.

Next, the tube pump 25 is driven to supply a predetermined amount of liquid resin into the molding die 11. After the liquid resin is filled in the molding die 11, the tube pump 25 is stopped and the valves 34 and 36 are closed. Then, the vacuum pump 22 is stopped, the valve 35 is opened, and the liquid resin is cured in this state. After being sufficiently cured by heat, the upper cap 16 was removed, the core 41 was taken out from the molding die 11, and the presence or absence of voids was examined.

The impregnation tests of Samples 1 to 3 were carried out by the method described above. The respective samples are as shown in FIG. Here, as the resin to be supplied, a diglycidyl ether type resin having a different molecular weight of an epoxy resin was mixed to adjust the viscosity, and an acid anhydride curing agent was added to this resin to obtain an impregnated resin. Further, the initial capillary ascending speed was determined from the relationship between the capillary ascending height and the elapsed time of each sample in the same manner as when the data in FIG. 5 was obtained.

Further, observing each of the impregnated samples 1 to 3,
I investigated the existence of voids. As a result, the cash register in the molding die
In Samples 1 and 9 in which the ratio B / A of the liquid surface rising speed (B) and the initial capillary resin liquid surface rising speed (A) was 3.0, tubular voids were generated. Further, in Samples 5 and 13 in which the ratio B / A was less than 0.5, spherical voids were generated. On the other hand, sample 2 having a ratio B / A in the range of 0.5 to less than 3.0
-4, 6-8, 10-12, no void was observed.

Samples 2 to 4 in which the resin liquid level was raised at an ascending velocity within the range of 0.5 to 3.0 of the ascending velocity of the capillary liquid surface in the cloth due to capillarity
It was found that 6-8 and 10-12 can be impregnated without generating voids. In this embodiment, an example in which the inside of the molding die 11 is evacuated when the resin is impregnated is shown, but it is not always necessary to evacuate and the upper cap 14 may be provided with an air vent.

[0021]

As is apparent from the above description, according to the present invention, the synthetic resin is voided in the fiber cloth without providing a means having a complicated structure for making the inside of the molding die as vacuum as possible. The effect of being able to be impregnated in a short time without causing the phenomenon is exhibited.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a molding die with a cloth attached.

FIG. 2 is a pipeline diagram of a manufacturing apparatus.

FIG. 3 is an explanatory view showing a resin impregnation state.

FIG. 4 is a table showing a relationship between a resin liquid surface rising due to a capillary phenomenon and time.

FIG. 5 is a graph showing a relationship between a resin liquid surface rising due to a capillary phenomenon and time.

FIG. 6 is a table showing an impregnation test of a sample.

[Explanation of symbols]

 11 Mold 13 FRP 31 Cloth

Claims (1)

[Claims] 1. A fiber sets cross into the molding die, resin capillary action of liquid to this fiber cloth
A method of impregnating utilizing, formed with a 0.5 to 2.5-fold increase rate of the initial rate of rise of the resin capillary liquid level to increase the slit of the fiber cloth by the capillary phenomenon
A method for producing fiber reinforced plastics, which comprises raising the liquid surface of a resin in a mold .