JP2006001074A - Manufacturing method of hollow molded product made of fiber reinforced resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a hollow molded product made of a fiber reinforced resin without causing a flaw from an aspect of appearance. <P>SOLUTION: A plurality of prepregs each of which is obtained by impregnating reinforcing fibers with a thermosetting resin and precured so that the curing depth of the thermosetting resin becomes 5-10%, are wound around a flexible hollow core material in a laminated state and cooled to form a preform. This preform is heated to be put in a mold in a softened state and heated while introducing air into the core material to cure the prepregs before the core material is removed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for producing a fiber-reinforced resin hollow molded body.

  Fiber reinforced resin (FRP) is used in various structures. For example, a hollow molded body made of fiber reinforced resin is used for sports equipment such as golf club shafts and tennis racket frames, and automobile parts such as seat frames. It has been.

  Such a hollow molded body made of fiber reinforced resin has been conventionally laminated around a core material called a mandrel and laminated with a reinforcing fiber sheet impregnated with an uncured thermosetting resin called a prepreg, It is manufactured by curing a thermosetting resin of a prepreg and extracting a mandrel.

  Although a linear hollow molded body can be manufactured by the above method, a molded body having a shape that is curved in an arc shape cannot be manufactured. Therefore, the prepreg is wound around the flexible hollow member, the prepreg is preheated to reduce the viscosity of the thermosetting resin, the prepreg is set in a mold, and pressurized air is fed into the hollow member. A method has been proposed in which a thermosetting resin is cured while the hollow member is finally extracted (for example, see Patent Document 1).

JP 63-193811 A

  When manufacturing a molded body by such a method, the prepreg is uncured when it is set in the mold. Reinforcing fiber pinching, that is, fiber biting, occurs at the split surface between the molds. Then, a streak-like burr | flash arises in the center surface corresponded to a parting surface in the obtained molded object. In order to prevent pinching of such reinforcing fibers, it is conceivable that reinforcing fibers are arranged in each of the upper mold and the lower mold of the mold, and the flexible hollow member is arranged and cured. In this case, although the pinching of the reinforcing fiber can be prevented, the fiber joint can be visually observed on the dividing surface.

  Such burrs or seams are not preferable in appearance, and an object of the present invention is to provide a method capable of producing a fiber-reinforced resin hollow molded body without causing such appearance defects.

  In order to solve the above-mentioned problem, according to the first invention, a prepreg obtained by impregnating a reinforcing fiber with a thermosetting resin, wherein the thermosetting resin is pre-cured to a curing depth of 5 to 10%. Are wound in a laminated state around a flexible hollow core material, cooled to form a preform, and then the preform is heated and softened and placed in a mold, and the core material is There is provided a method for producing a fiber-reinforced resin hollow molded body, characterized in that the prepreg is cured by heating while pressing air into the core, and finally the core material is removed.

  In order to solve the above problem, according to a second invention, a flexible sheet and a prepreg obtained by impregnating a reinforcing fiber with a thermosetting resin, the curing temperature of the thermosetting resin is 5 to 10%. A plurality of pre-cured prepregs are wound around the core in a laminated state, cooled to form a hollow tube and preform of a flexible sheet, the core is removed, and the preform is heated The fiber-reinforced resin hollow molded article is characterized by being placed in a mold in a softened state, heated while pressing air into the hollow tube to cure the prepreg, and finally removing the hollow tube. A manufacturing method is provided.

  According to the present invention, by performing molding using a prepreg that has been pre-cured to a predetermined curing depth in advance, it is possible to prevent the cross-section of the reinforcing fiber from being collapsed when the mold is clamped. Can be prevented. Moreover, the joint of a fiber can be made only at one place, and can be set at an arbitrary part of the molded body from which this joint can be obtained. Furthermore, by simultaneously forming the hollow tube of the flexible sheet at the time of forming the preform, it is possible to eliminate the labor and cost of manufacturing and installing the hollow member in advance.

  The present invention will be described below with reference to the drawings. First, as shown in FIG. 1, a plurality of prepregs 2 are wound around the core material 1 in a laminated state so as to have a predetermined thickness, and cooled to form a preform. This prepreg is obtained by impregnating a reinforcing fiber with a thermosetting resin, and those generally used in fiber-reinforced resins can be used.

  As the reinforcing fibers, fibers generally used as high-performance reinforcing fibers can be used, and examples thereof include carbon fibers, aramid fibers, silicon carbide fibers, aluminum fibers, boron fibers, and glass fibers. These reinforcing fibers may be either long fibers or short fibers, and two or more of these may be mixed. The shape and arrangement of the reinforcing fibers are not limited, and may be any shape and arrangement such as a single direction, a random direction, a sheet shape, a mat shape, a cloth shape, and a braid shape.

  Examples of the thermosetting resin include those generally used in fiber reinforced resins, such as epoxy resins, vinyl ester resins, unsaturated polyester resins, and the like, and among these, epoxy resins are particularly preferable. Moreover, you may include the hardening | curing agent for epoxy resins in an epoxy resin. As the curing agent, any compound having an active group capable of reacting with an epoxy group may be used. For example, amines, acid anhydrides, imidazoles and the like are known.

  The core material 1 is a flexible hollow body. For example, a tube made of polyamide resin, polyester resin, silicon rubber, or the like can be used. However, such a core material needs to be manufactured in advance. Therefore, as shown in FIG. 2, a flexible sheet 3 is arranged between the core material 1 and the prepreg 2, and the flexible sheet 3 and the prepreg 2 are wound around the core material 1, thereby performing a preform. It is preferable to form the hollow tube at the same time as forming. At this time, the core material 1 may be, for example, a metal mandrel conventionally used. As the flexible sheet, Teflon rubber, silicon rubber, nylon resin, Teflon resin, or the like can be used.

  In the present invention, the thermosetting resin in the prepreg is previously subjected to heat treatment at a predetermined temperature and a curing depth of 5 to 10%. The heat treatment temperature varies depending on the resin used, the curing agent, the heating time, and the like, but is generally 80 to 120 ° C. The curing depth is a value measured from a change in the dielectric characteristics of the resin when the uncured prepreg state is 0% depth.

  The preform thus formed is shown in FIG. In this preform 4, nozzles 5 for inserting air pressure are embedded at both ends of a hollow tube formed of a flexible core material or flexible sheet 3.

  The preform 4 is heated and bent in a softened state, and is placed in a lower mold 6 having a predetermined cross-sectional shape as shown in FIG. The heating temperature for softening is a temperature at which the thermosetting resin softens but does not harden, and is generally 60 to 100 ° C. although it varies depending on the resin.

  Next, as shown in FIG. 5, the upper mold 7 is set on the lower mold 6, and heating is performed while air is being injected through the nozzle 5 to cure the thermosetting resin, thereby obtaining a molded body. This heating temperature is a temperature at which the thermosetting resin is sufficiently cured, and is generally 130 to 180 ° C. Finally, a hollow molded body is obtained by removing the flexible hollow core material 1 or the hollow tube 3.

  A carbon / epoxy prepreg (Toho Tenax Co., Ltd., W3101 / Q-112J) is used as a raw material, and a dielectric property sensor (NETZSCH-Geratebau Co., Ltd., IDEX-Midcon) is affixed to a part and placed in a heating furnace at 80 ° C. Preheating was performed. During this preheating, the dielectric properties of the prepreg were measured using a Microdielectrometer (manufactured by NETZSCH-Geratebau, Eumetric system III), and the resin viscosity and the cure depth (Cure Index) were measured. In measuring the curing depth, measurement parameters are extracted from data obtained in a 100% curing experiment by rapid heating and slow cooling using the same measurement system and the same material in advance and corrected on the same apparatus.

  In the above treatment, when the curing depth reached 10%, the heating was stopped and rapidly cooled to stop the curing reaction. 80 minutes after the start of the heat treatment, the resin arrival temperature was 84 ° C.

  The prepreg thus precured was appropriately cut, and after eight layers were laminated, a PTFE film (TOOLTEC CS5, manufactured by AIRTEC) having a thickness of 152 μm was stuck on one side. Wrap the prepreg around the core material with a predetermined cross-sectional shape so that the PTFE film is in contact with the core material, heat it to about 60 ° C, cool it to room temperature, leave it for 24 hours, and remove the core material. Then, both ends of the PTFE film were squeezed and an aluminum pipe having a diameter of 10 mm was inserted and sealed to obtain a preform.

  The preform was put into a lower mold having a predetermined shape while being deformed along the cavity while being heated to about 60 ° C. Next, when the upper mold was set and left at room temperature for 25 days through an aluminum pipe and heated again to 130 ° C., the resin viscosity increased and the fluidity decreased. This tendency was more remarkable as the curing depth was higher. As a result, it was difficult to set the lower mold.

It is a figure which shows the process of this invention. It is a figure which shows the process of this invention. It is a figure which shows the process of this invention. It is a perspective view which shows a preform. It is a figure which shows the process of this invention.

Explanation of symbols

1 Core Material 2 Prepreg 3 Flexible Sheet 4 Preform 5 Nozzle 6 Lower Mold 7 Upper Mold

Claims (2)

  A prepreg obtained by impregnating a reinforcing fiber with a thermosetting resin, wherein a plurality of prepregs obtained by pre-curing the thermosetting resin at a curing depth of 5 to 10% are laminated around a flexible hollow core material After winding and cooling to form a preform, the preform is heated and softened and placed in a mold, heated while pressing air into the core material to cure the prepreg, Finally, the core material is removed, and a method for producing a fiber-reinforced resin hollow molded body.   A prepreg formed by impregnating a flexible sheet and a reinforced fiber with a thermosetting resin, and a plurality of prepregs obtained by pre-curing the thermosetting resin at a curing depth of 5 to 10%. Wrapped in a laminated state, cooled to form a hollow tube and preform of a flexible sheet, the core material is removed, the preform is heated and softened and placed in a mold, and the hollow A method for producing a fiber-reinforced resin hollow molded article, wherein the prepreg is cured by heating while pressing air into the tube, and finally the hollow tube is removed.

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