JPH08183104A - Manufacturing method of fiber reinforced resin products - Google Patents

Abstract

(57) [Summary] [Purpose] The objective is to obtain a fiber-reinforced resin molded product that allows the resin phase to be sufficiently cured to exhibit the original physical properties. [Structure] A filament winding step of winding long fibers containing a curable resin and a curing agent around a core metal of an appropriate shape, and curing the curable resin contained in the fiber reinforcement with the curing agent to form a resin layer. In the method for producing a fiber-reinforced resin product, which comprises a curing step of molding, the filament winding step includes a ratio of a curing agent to a curable resin contained in the long fibers at any stage of winding the long fibers around a core metal. Or a method for producing a fiber-reinforced resin product, which comprises coating the outer periphery of a filament winding molding with a tape having voids impregnated with a curing agent after the filament winding step. By this method, a cured resin phase can be formed without scattering of the curing agent, and the physical properties of the molded product are improved.

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber reinforced resin product, and more particularly to a method for producing a filament winding molding.

2. Description of the Related Art Conventionally, a reinforcing long fiber such as carbon fiber or glass fiber is impregnated with a resin, and then the reinforcing long fiber is wound around a core die having a desired shape to remove the resin attached to the reinforcing long fiber. There is a filament winding molding method in which a resin molded article is cured. As the resin used in this molding method, an epoxy resin having a good balance of adhesiveness with fibers, material strength, cost, etc. is often used. This epoxy resin is a material that cures to become a resin when a liquid base material and a curing agent are mixed and heated. In this molding method by filament winding, usually, a reinforcing long fiber containing a resin is wound around a core mold and molded, and then the molded body is placed in a curing furnace and heat-cured to form an epoxy resin layer.
At the time of this heat curing, the curing agent having a high vapor pressure in the epoxy resin liquid contained in the reinforcing long fibers does not participate in the curing reaction and easily evaporates at the curing temperature and escapes from the resin system. Therefore, curing of the resin layer does not proceed sufficiently and desired resin properties are often not expressed. In particular, there is a problem that sufficient hot strength cannot be obtained because the crosslinking reaction between resin molecules becomes insufficient. In this filament winding molding method, the reinforcing long fibers are continuously dipped in the epoxy resin liquid and wound around the core, so that the resin liquid is a liquid with a low viscosity at room temperature in order to uniformly adhere to the reinforcing long fibers. Is required. Therefore, the curing agent used is preferably one having a low boiling point. For example, anhydrous methyl nadic acid, which is often used as an acid anhydride-based curing agent, has a low boiling point of 127 ° C, which is considerably lower than the curing start temperature (125 to 130 ° C) (90 ° C).
Evaporation starts from ~). As a method of solving the problem of volatilization of the curing agent, it is possible to wrap a film-shaped tape around the molded product before the curing treatment to prevent the curing agent from evaporating. Since the surface of the molded product becomes uneven due to the resin liquid squeezed on the surface of the molded product during winding, post-processing (for example, a tape peeling process) is required, and the productivity deteriorates. Further, when the reinforcing long fibers are wound around the core die, air entrapped therein cannot be dispersed and remains as air bubbles inside the molded product, which easily causes an internal defect of the molded product.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a fiber-reinforced resin product capable of sufficiently curing the resin layer and exhibiting the original physical properties of the fiber-reinforced resin molded product. The purpose is to

The method for producing a fiber-reinforced resin product of the first invention of the present application is a filament winding method in which reinforcing long fibers containing a curable resin and a curing agent are wound around a cored bar of an appropriate shape. In the method for producing a fiber-reinforced resin product, which comprises a step of curing a curable resin contained in the fiber reinforcement with a curing agent to form a resin layer, the filament winding step comprises reinforcing long fibers as cores. It is characterized in that the ratio of the curing agent to the curable resin contained in the reinforcing long fibers is increased at any stage of winding around gold. The method for producing a fiber-reinforced resin product of the second invention of the present application includes a filament winding step of winding reinforcing long fibers containing a curable resin and a curing agent around a core metal of an appropriate shape, and a fiber winding step. In a method for producing a fiber-reinforced resin product, which comprises a curing step of curing a curable resin with a curing agent to form a resin layer, the filament winding step is performed after the filament winding step using a tape having voids impregnated with the curing agent. It is characterized by covering the outer periphery of the molded body.

According to the first method of the present invention, the ratio of the curing agent to the curing resin in the curable resin liquid contained in the reinforcing long fibers at any stage of the filament winding step of winding the reinforcing long fibers around the core metal. Increase. as a result,
The amount of the curing agent in the resin liquid contained in the outer portion of the fiber reinforced molded product increases, and the curing reaction of the resin in the outer portion of the molded product becomes faster. Therefore, the contained curing agent is volatile, and even if a part of it scatters, the relative amount of the curing agent involved in the curing reaction of the cured resin increases, and the curing reaction progresses rapidly to improve the strength of the resin layer. Can be increased. In order to increase the amount of the curing agent impregnated into the reinforcing long fibers, any step after the usual resin liquid is added, for example, the fibers of the portion forming the surface portion of the molded product are re-immersed in the curing agent liquid. Or let
Alternatively, the ratio of the curing agent in the resin contained in the reinforcing fiber can be increased by changing the resin impregnating liquid to a separately prepared resin liquid having a different concentration ratio. By this method, it is possible to secure a sufficient concentration of the curing agent for crosslinking the resin even with the volatile curing agent during the heating for curing. as a result,
A molded article of the fiber-reinforced resin after curing can exhibit desired physical properties. In the second method of the present invention, after completion of the filament winding step, a tape having pores preliminarily impregnated with a curing agent (e.g. nylon, polyester, etc., which can withstand epoxy curing temperature and has chemical resistance, such as synthetic fiber Woven cloth heat-resistant tape, etc.) is wrapped around the surface of the molded product to cover it, thereby increasing the concentration of the curing agent on the surface of the molded product, and the resin due to insufficient amount of curing agent in the resin liquid contained in the laminated fiber. It is possible to prevent the layer from being insufficiently cured. As a result, the cured fiber-reinforced resin molded article can exhibit desired physical properties. Here, as the tape having voids, for example, a tape having voids such as a cloth woven with synthetic fibers is preferable, and when the tape is wound around the molded product, excess resin inside the molded product is uniformly deposited on the surface. At the same time, when the resin liquid passes through the pores of the tape, it has the effect of uniformly mixing with the curing agent contained in the tape. Further, air bubbles remaining inside during molding can be pushed out to the surface by winding the tape, pass through the void holes of the tape, and be scattered to the outside. Also,
In some cases, the tape coated with the molded product can be directly incorporated into a molded product without peeling and used. Therefore, in this method, since the hardener liquid is impregnated in the tape and held, the amount of the hardener at the surface portion can be easily controlled, and a molded product having higher strength can be obtained. In addition, when impregnating a tape having voids with a curing agent, a flame retardant such as aluminum hydroxide powder is dispersed at the same time so that the flame retardant is adhered only to the surface of the molded article to make the molded article flame-retardant. It is also possible to plan. When this flame retardant is dispersed in the entire molded product, the strength of the molded product is reduced, but if it is only the surface portion, the strength of the molded product can be prevented from being reduced and flame retardation can be achieved.

[Examples] Hereinafter, specific examples will be described. (Example) (Filament winding step) A roving, which is a bundle of reinforcing long fibers (glass fiber or carbon fiber), is drawn out and a resin liquid (uncured epoxy resin (e.g., Epicoat 827, epicron, etc.)) and a curing agent (e.g., MH
AC, Epiclon 13570, etc.) to a curing agent (eg, Epicoat 827; 100: MHAC; 88).
The weight ratio of the above))) and then wound around a core die such as a cylindrical shape while controlling the amount of adhesion to the fiber (20 to 50 wt% relative to the fiber weight) with a guide roller to form a cylindrical laminated molded article. . Next, a nylon woven tape having voids is dipped in the above-mentioned curing agent liquid (adhesion amount: 10 to 100% by weight based on the weight of the tape) to impregnate the tape with the curing agent, and the surface of the above fiber-laminated resin molded product is uniformly coated. Wrap around. At the time of winding the tape, the air bubbles attached to the fibers can be scattered from the gap of the tape by the pressure applied to wind the tape. Further, when the uncured resin liquid oozing from the inside of the molded product to the surface of the molded product comes into contact with the curing agent, the concentration of the curing agent can be increased and the curing speed can be increased. Further, in order to make the curing rate uniform, the ends of the tape may be overlapped with each other and wound around the molded body so that the thickness of the tape becomes constant. (Curing step) The fiber-laminated resin molded product wound with the tape was put in a heating and curing oven and heated at 130 ° C for 20 minutes to cure the resin. As a comparative example, the tape was not wrapped around the molded product, but the fiber-laminated resin molded product was used as it was in a heating and curing furnace.
The resin was cured by heating at 0 ° C for 120 minutes. The molded product obtained in the example had a hot strength 1.5 times that of the molded product of the comparative example. In addition, the curing speed is uniform by winding the tape so that the thickness of the tape (impregnated curing agent amount) is constant so that the surface curing agent becomes uniform when the tape having voids is wound around the molded product. You can also Therefore, by winding the tape having the voids around the molded product, a high-strength fiber-reinforced resin molded product having no hot air inside and having excellent hot strength was obtained. (Example 2) The roving of the reinforcing long fiber was passed through the same resin liquid bath as in Example 1 to form a core type such as a cylindrical shape while controlling the amount of adhesion to the fiber (20 to 50 wt% relative to the fiber weight) with a guide roller. It is wound to form a cylindrical laminated molded product. At the stage where the roving of the reinforcing long fibers forms the outermost surface layer of the molded article, the curing agent liquid bath (Example 1
The tape is impregnated with the curing agent liquid), the reinforcing long fibers are impregnated with the curing agent, and the tape is wrapped around the molded body to form a surface layer. This additional step of the curing agent liquid bath increases the concentration of the curing agent in the surface layer of the molded body. When the molded body having the high surface concentration of the curing agent was cured in the curing step under the same conditions as in Example 1, a fiber-reinforced resin molded product having the same hot strength as in Example 1 was obtained. (Example 3) The roving of long fibers for reinforcement was passed through the same resin liquid bath as in Example 1 to form a core type such as a cylindrical shape while controlling the amount of adhesion to the fibers (20 to 50 wt% relative to the fiber weight) with a guide roller. It is wound to form a cylindrical laminated molded product. After forming a molded product unlike Example 2, the curing agent concentration was increased by spray coating or brush coating on the surface of the molded product. In this way, after molding, the curing agent liquid can be applied to the surface of the molded article by spraying or the like to increase the concentration of the curing agent at the surface site. When this molded product was cured under the same conditions as in Example 1, a fiber-reinforced resin molded product having similarly excellent hot strength was obtained.

According to the first method of the present invention, the proportion of the curing agent in the resin is increased while the reinforcing fiber is being wound around the core while being immersed in the resin liquid in the filament winding step. As a result, the ratio of the curing agent in the resin layer near the surface of the fiber laminated molded article is increased, and the curing agent is sufficient to cure the resin even if a part of the volatile curing agent flies out of the system at the heating temperature. It is possible to hold the quantity. Therefore, the resin curing normally proceeds and desired resin physical properties can be obtained. According to the second method of the present invention, a tape having voids impregnated with a curing agent is wound around the surface of the fiber laminated molded product molded in the filament winding step. At this time, the resin that has exuded from the inner side to the surface side during molding exudes to the outside of the tape through the voids. At this time, the curing agent immersed in the tape is taken into the resin, and the ratio of the curing agent in the resin near the surface increases.
Therefore, even if a part of the curing agent is scattered, the amount of the curing agent necessary for curing the resin can be maintained and the curing speed can be increased. Further, the air bubbles remaining inside the molded product during molding can be extruded to the surface when the tape is wound and removed through the pores of the tape on the surface, and a fiber-reinforced resin molded product having excellent strength can be obtained. .

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Shimoda 1 Toyota-cho, Toyota-shi, Aichi Toyota Motor Co., Ltd.

Claims (2)

[Claims] 1. A filament winding process in which long fibers containing a curable resin and a curing agent are wound around a cored bar of an appropriate shape, and the curable resin contained in the fiber reinforcement is cured with the curing agent to form a resin layer. In the method for producing a fiber-reinforced resin product, which comprises a curing step for molding, the filament winding step includes a ratio of a curing agent to a curable resin contained in the long fibers at any stage of winding the long fibers around a core metal. A method for producing a fiber-reinforced resin product, which comprises increasing 2. A filament winding process in which long fibers containing a curable resin and a curing agent are wound around a cored bar of an appropriate shape, and the curable resin contained in the fiber reinforcement is cured with the curing agent to form a resin layer. In the method for producing a fiber-reinforced resin product, which comprises a curing step of molding, a filament winding molded body is covered with a tape having voids impregnated with a curing agent after the filament winding step. Manufacturing method of fiber-reinforced resin product.