JPH09272158A - Preparation of frp pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an FRP pipe being uniform and with high physical properties by a method wherein after a resin with an amt. being larger than the amt. being necessary for a final molded article is fed in a cavity, the cavity is closed and after impregnation of the resin into a reinforcing fiber is accelerated, excess resin is squeezed out and the resin is cured. SOLUTION: When a resin is fed in a resin cavity, an uncured body 5 with a shape of a racket frame is formed with a fed resin and a preset preform 7. As the resin with an amt. being larger than the amt. being required for a final molded article is fed, the resin or the resin-impregnated preform 7 is expanded inside against the first inner pressure. After impregnation of the resin is accelerated, the cavity 6 is opened. Namely, an outlet for the resin is opened. As the first inner pressure is loaded in the preform, excess resin is squeezed out by opening, and air bubbles are discharged therewith.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an FRP pipe suitable for being applied to a pipe having a complicated shape such as a bent pipe such as a racket frame.

[0002]

2. Description of the Related Art FRP tubes are used for various purposes such as sports and leisure because of their light weight and high strength. Usually, the FRP pipe is made by winding a reinforcing fiber thread impregnated with resin on a core material and curing it directly, or
It is molded by once forming a preform, setting the preform in a mold and curing the resin. The latter method is often used for a pipe having a relatively complicated shape such as a bent pipe.

In this latter method, for example, a layer of reinforcing fibers is provided on a flexible tube to form a dry preform not impregnated with resin, and the preform is set in a mold. A method of molding a FRP pipe by injecting a resin into a rear mold and curing the resin while applying an internal pressure to the tube is known.

JP-A-6-286005 and JP-A-7-280005
JP-A-2232271 describes that in the above-mentioned internal pressure molding method, the internal pressure is increased after the resin is injected to squeeze out the excess resin, but the squeeze out of the excess resin will cause the resin to spread sufficiently. Not yet,
That is, the resin may be cured in a state where there is an unimpregnated portion of the resin or a void in the reinforcing fiber.

Further, Japanese Patent Publication No. 6-49300 discloses that
Although a method of obtaining a voidless molded product by degassing from the cavity of the mold is described, it cannot be applied to a molding method using a mold because the mold is made of a flexible material.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to make it possible to produce a uniform and high physical property FRP pipe having no resin-impregnated portion or voids by allowing the injected resin to spread sufficiently into the reinforcing fibers of the preform during molding. To provide a method.

[0007]

In order to solve the above-mentioned problems, in the method for producing an FRP pipe of the present invention, a preform containing dry reinforcing fibers not impregnated with a resin is set in a cavity of a mold. The mold is clamped, the resin is injected into the cavity in an amount larger than that required for the final molded product, then the cavity is closed, and the closed state is maintained to promote the impregnation of the resin into the reinforcing fiber. After that, open the cavity and squeeze out the excess resin, and then solidify the resin and FR
The method comprises molding a P-tube. That is, this is a method in which the closed state of the cavity is continued for a certain period of time, the resin injected during that period is sufficiently spread, and then the excess resin is squeezed out.

In this method, it is preferable that the mold is clamped, internal pressure is applied to the preform, and the resin is injected into the cavity under the internal pressure load condition. Further, in order to more smoothly squeeze out the excess resin after promoting the impregnation of the reinforcing fiber with the resin, it is preferable to load the preform with an internal pressure higher than the above internal pressure, that is, to increase the internal pressure in two stages. .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings. In the present invention,
A tubular preform containing a reinforcing fiber in a dry state not impregnated with a resin is used for molding an FRP pipe. Such a preform can be formed, for example, by covering a mandrel with a flexible tube and winding a reinforcing fiber yarn around the flexible tube. The winding of the reinforcing fiber yarn is performed by, for example, a filament winding method. Alternatively, a braid of reinforcing fibers may be used to form the preform.

The type of reinforcing fiber is not particularly limited, and for example, glass fiber, carbon fiber, and organic high elastic modulus fiber such as polyaramid fiber can be used.

Using the dry preform thus prepared, the method for producing an FRP pipe according to the present invention is carried out as follows. An embodiment in the case of manufacturing a racket frame as an FRP pipe will be described below.

As shown in FIG. 1, first, the above-mentioned preform is shaped into a racket frame-shaped preform 1 as shown in FIG. 1, and the preform 1 is molded into a molding die 2.
The mold 2 set in the cavity is clamped, and a larger amount of resin than the amount required for the final molded product, that is, the target molded racket frame is injected into the cavity. The resin is injected in the state of a resin composition in which the main agent 3 (matrix resin) and its curing agent 14 are mixed.

The type of the matrix resin is not particularly limited, and any of thermosetting resin, thermoplastic resin, and mixed resin thereof can be used. In general, F
Thermosetting resins are most often used for RP products, and epoxy resins are most widely used.

Examples of the epoxy resin include bisphenol A type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, glycidyl amine type epoxy resin, alicyclic epoxy resin,
Urethane-modified epoxy resin, brominated bisphenol A
Various epoxy resins such as type epoxy resin can be used. These epoxy resins can be used alone or in combination of two or more kinds, and can be used in liquid form to solid form. Usually, a one-component curing type epoxy resin to which a curing agent is added is often used. The curing agent is not particularly limited, but a latent type curing agent is preferable in terms of storability. As an example of the latent curing agent, a guanidine-based curing agent such as dicyandiamide is preferably used.

At the step of injecting the resin, as shown in FIGS. 2 and 3, it is preferable to apply an internal pressure to the preform 1, for example, to a flexible tube forming the inner surface side of the preform 1. (Hereinafter, this is called a first internal pressure).

When the resin is poured into the cavity until it is filled, the unfilled body in the shape of a racket frame is formed in the cavity by the injected resin and the preform 1 set in advance as shown in FIG. 5 is formed.

At the time of this resin injection, it is preferable that the resin is extracted from the side opposite to the injection end in order to fill the cavity with the resin. At this time, it is preferable that the inside of the cavity is decompressed at the same time so that the resin is filled more easily and uniformly.

At this stage, as shown in FIG. 3, a larger amount of resin than that required for the final molded product shown in FIG. 4 is injected into the cavity 6, so that the resin or resin-impregnated preform is injected. 7 bulges inwardly against the first internal pressure. In addition, 8 in FIG. 3 shows a core for forming the gut groove.

Further, when the resin is injected, the injected resin may not yet be sufficiently impregnated into the reinforcing fiber of the preform 1, and unimpregnated portions and bubbles 9 (voids) may be present.

Therefore, after the resin is injected, the cavity 6 is closed, and the closed state is maintained and continued for a certain period of time. As a result, the resin appropriately flows in the cavity 6 to sufficiently impregnate the reinforcing fiber, the unimpregnated portion disappears, and the bubbles 9 are also driven to a position where they are easily extruded in the next step. That is, the resin impregnation is promoted by maintaining the closed state of the cavity.

After promoting the resin impregnation, the cavity 6
Is released. That is, the resin outlet is opened.
Since the first internal pressure is applied to the inside of the preform 1, the excess resin is squeezed out by the opening, and the air bubbles are also extracted together therewith. At this time, as shown in FIG. 4, a second internal pressure higher than the first internal pressure may be applied to more positively and quickly squeeze out the surplus resin. That is, the first internal pressure is increased to the second internal pressure,
Apply 2-stage internal pressure.

After squeezing out the excess resin, it is heated at a predetermined temperature to solidify the resin, and a desired FRP racket frame is molded.

The steps from the resin injection to the solidification of the resin are shown, for example, in FIG. 5 when the time is plotted along the horizontal axis. That is, the resin impregnation is promoted for a certain period of time after the resin injection (A), and the excess resin is squeezed out (B),
The resin is solidified (C).

In the above molding, in order to more surely close the cavity after resin injection, as shown in FIGS. 6 and 7, for example, as shown in FIGS. O-ring 10 to surround cavity 6
Is preferably provided. Also, this O-ring 10
Is preferably arranged so as to also surround the resin injection port 11 and the decompression / resin extraction port 12.

In the FRP racket frame molded as described above, the resin is sufficiently and uniformly impregnated,
There are no voids on the surface, and molded products with good physical properties and surface characteristics can be obtained. Further, since there are no voids on the surface, it is possible to omit the putty filling / polishing step after molding.

[0026]

【Example】

Example 1 A folding diameter of 24 mm on a steel mandrel having an outer diameter of 14 mm
Of nylon fiber, covered with a three-layer carbon fiber braid "Torayca Blade" T6383 manufactured by Toray Industries, Inc., and then the mandrel was removed to prepare a preform.
The preform was set in a mold (70 ° C) with a U-shaped cavity, and while the pressure inside the mold was reduced, an air pressure of 392 KPa was applied to the inside of the mold, and a resin with a viscosity of 10 vise or less (epoxy A resin CER AER260 and a curing agent Ciba HY2962 are mixed at a ratio of 100: 25), and when the resin comes out from the resin outlet, the cocks of the inlet and the outlet are closed to close the mold.
Here, the amount of resin to be injected must be determined by the set Vf (volume fiber content rate), the resin path inside and outside the mold, the distance, etc.
0% more was injected.

Although the resin viscosity temporarily decreases and then increases again, the cock of the injection / extraction port is opened and the excess resin is extracted at the timing when the viscosity does not become too high. The resulting U-shaped tube is completely voidless and has a Vf of 58.
It was as high as%.

Example 2 A mandrel made of steel having an outer diameter of 15 mm and a folding diameter of 24 mm
Carbon fiber “Torayca” manufactured by Toray Industries, Inc. by the filament winding method
T700SC-12K (± 30 ° / ± 10 ° / ± 30
After winding up with a winding angle of (°) and a winding layer structure, the mandrel was removed to prepare a preform. The preform was shaped into a racket frame shape, charged into a racket mold preheated to 100 ° C., and then clamped. Molding was performed by the following procedure. a. The inside of the cavity is decompressed from the resin outlet side installed in the grip part, and the inside of the tube is 392 KPa with air pressure.
Pressurize. b. Resin (epoxy resin similar to that in Example 1) is injected at a pressure of 980 KPa from an injection port provided on the top side. When the injection is finished, close the cock of the injection port. c. When the injected resin bleeds from the outlet,
The cock of the outlet is also closed to close the inside of the mold, and resin impregnation (penetration) time is provided. d. At a timing when the resin viscosity does not become too high, the inlet and the outlet are opened, the internal pressure is increased to 785 KPa, and the excess resin is squeezed out. The finished frame has no void and Vf is 62
% And high Vf. When the reproducibility was examined at n = 10, the results were as shown in Table 1.

[0029]

[Table 1]

In Table 1 above, the CV value (%) is represented by (standard deviation / average value) × 100, and represents the degree of data variation as a percentage.

[0031]

As described above, according to the present invention,
FRP with uniform and high physical properties without resin-impregnated parts and voids
A tube is obtained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a method for molding an FRP racket frame according to an embodiment of the present invention.

FIG. 2 is a plan view showing a state of molding in the method of FIG.

FIG. 3 is an enlarged partial sectional view showing a state immediately after resin injection in the method of FIG.

FIG. 4 is a cross-sectional view showing a state when a surplus resin is extracted from the portion of FIG.

FIG. 5 shows an example of each step in the method of the present invention,
It is a characteristic view of internal pressure and time.

FIG. 6 is a schematic enlarged plan view of the mold of FIG.

7 is a cross-sectional view taken along the line VII-VII of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Preform 2 Mold 3 Main agent (matrix resin) 4 Curing agent 5 Uncured body 6 Cavity 7 Resin (impregnated preform) 8 Core 9 Bubble 10 O-ring 11 Resin injection port 12 Pressure reduction / resin extraction port

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location B29K 105: 08 B29L 23:00 31:52 (72) Inventor Tetsuyuki Kyono Matsumae, Iyo-gun, Ehime Prefecture 1515 Tsutsui Toray Co., Ltd. Ehime factory

Claims (4)

[Claims] 1. A preform containing dry reinforcing fibers not impregnated with resin is set in a cavity of a mold and the mold is clamped, so that a larger amount of resin than that required for a final molded product is obtained. After injecting into the cavity, the cavity is closed, and after maintaining the closed state to promote the impregnation of the reinforcing fiber with the resin, the cavity is opened to squeeze out the excess resin,
Then, the resin is solidified to form an FRP pipe, which is characterized by a method for producing the FRP pipe. 2. The method for manufacturing an FRP pipe according to claim 1, wherein after the mold is clamped, an internal pressure is applied to the preform, and the resin is injected into the cavity under the internal pressure load condition. 3. After promoting the impregnation of the reinforcing fibers with the resin,
The method for manufacturing an FRP pipe according to claim 2, wherein the preform is subjected to an internal pressure higher than the internal pressure to squeeze out excess resin. 4. The method for manufacturing an FRP pipe according to claim 1, wherein the molded FRP pipe is a racket frame.