JPS60239212A - Manufacturing method of fibre reinforced plastic structure - Google Patents

Abstract

PURPOSE:To eliminate air bubble in impregnated resin by repeating decompression and pressurization of resin impregnated lobing after winding and laminating on a mold and heating thereof. CONSTITUTION:An epoxy resin is impregnated in a lobing of a carbon fibre, then, it is wound and laminated on a mold, and after a softening of the impregnated resin 4 by heating it to 60-80 deg.C, the air bubble 5 in the resin is flowed out on a surface by being decompressed lower than 10Torr and then expanded, further, a volume of a residual air bubble is reduced by the pressurization, the decompression and the pressurization are repeated again, after a completion of the elimination of the air bubble, the epoxy resin is cured under heating to 120 deg.C, and an air- bubble-less FRP product with a high strength is manufactured.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for producing a fiber-reinforced resin structure and a method for defoaming a resin-impregnated reinforcing material during the production process.

[Prior art]

Fiber-reinforced resin composites are used in automobiles because they are lightweight, have great strength, and are easy to mold, but recently they have also been used as guards (aggregate) for steering wheels, axles, etc. A fiber-reinforced resin structure is made by impregnating a resin liquid in advance, then wrapping a long thread-like fiber reinforcement material such as roving around a rolling jig to a predetermined thickness and hardening it. After.

By demolding, one-dimensional or three-dimensional structures can be obtained with various degrees of design freedom, and development as large-scale structures is also progressing. However, in the manufacturing process of such a structure, for example, as shown in the perspective view of the girder (aggregate) 1 in FIG. If the tension in the direction is insufficient, air is trapped between the resin-impregnated fibers 2 and cannot escape because it is blocked by the viscous resin.

As a result, air bubbles remain in the resin, lowering the interlayer shearing force of the structure and making it impossible to obtain sufficient strength.

One way to avoid such entrainment of air bubbles is to wind the resin-impregnated fibers at a low speed, but such a method has the disadvantage of reducing productivity.

[Purpose of the invention]

An object of the present invention is to solve the above-mentioned problems and provide a method for manufacturing a fiber-reinforced resin structure that does not contain bubbles and has sufficient strength.

[Structure of the invention]

In other words, the method for producing a fiber-reinforced resin structure of the present invention is to wrap filamentous fiber-reinforced material impregnated with a resin liquid around a winding form of a desired shape and laminate them, and then to repeatedly apply pressure to length or normal pressure under heating conditions. The method is characterized in that air bubbles in the resin are removed, and then the temperature is raised to cure the resin under normal pressure or pressurization.

Carbon fibers, glass fibers, etc. can be used as the filament fiber reinforcement used in the present invention. For example, carbon fibers with a thickness of about 7
μm, glass fiber thickness 13 to 25 μm
A thread (roving) consisting of 2,000 to 3o or ooo m threads, or a string (roving or yarn) made by twisting or pulling all of these threads together is used.

Further, as the resin impregnated into the continuous fibers, thermosetting resins such as epoxy resins, unsaturated polyester resins, and phenol resins are used. The composition of these resin liquids is such that when impregnated into fibers, the viscosity is such that it spreads over the fiber surface sufficiently but does not run off, and special catalysts or accelerators are added to improve the viscosity after impregnation. It is preferable to use a material that does not harden during initial heating but can be hardened by increasing the temperature after defoaming.

〔Example〕

Hereinafter, an embodiment for manufacturing a rectangular pipe will be described with reference to all the drawings.

Two more threads made of carbon fibers 1s, ooo with a thickness of 7μm were pulled together, and then the strings with a thickness of about 4 fins were immersed in an epoxy resin liquid (trade name: Araldite) with a viscosity of 150C, p, and then 300mm It was laminated by winding it 400 degrees around a 2 m long jig having a square cross section of 500 gH. The amount of resin liquid attached to the fibers was determined to be 1.4 times the volume ratio. After impregnation, the wood M4 contains air bubbles 5 as shown in Figure 1-P), and in order to facilitate the movement of the air bubbles 5, the laminate was placed in a vacuum chamber together with all the jigs to cause curing. The resin 4 is softened by heating to a temperature of 60 to 80°C.

Next, the pressure inside the vacuum chamber is reduced to below 1c10 Torr (-750 mHg) and kept for 3 minutes. As shown in Figure 1-(b), the bubbles 5 remaining in the resin expand, reach the surface, and flow out, and at the same time the bubbles 5 After that (indicated by the dotted line), the resin 4 flows in due to gravity.

Although most of the bubbles disappear in this way, some bubbles still remain, so in Figure 1-(c), the pressure is returned to normal and left for 10 minutes to allow the bubbles to shrink by 51. When the pressure is reduced again, the bubbles 5 expand and become easier to flow out from the surface.

After completing degassing by repeating this process three times, the mixture was heated to 120°C under normal pressure or 3 to 5 atmospheres of pressure, and then heated to 120°C.
Cure for 20 minutes. At this time, the relatively small bubbles 5 that have not completely flowed out to the surface are crushed by the surrounding resin 4 and harden in a microscopic state. After curing, the jig is removed to obtain a rectangular pipe with a length of 2rn and a wall thickness of 4.

On the other hand, the strength and elastic modulus of the flat plates cut from these two types are shown below by the method of the present invention and the conventional method. Bending strength (MPa) 1300 700 Flexural modulus (GPa) ao 6゜As described above, the product produced by the method of the present invention has increased strength and rigidity compared to conventional techniques, and is a structural material without bubbles. Recognize.

[Effects of the Invention] As is clear from the above description, in the method of the present invention, the mobility of the bubbles is increased by repeating heating and pressurization under reduced pressure in the subsequent process after lamination, so complete desorption is possible. You can make bubbles. Therefore, the reinforcing material impregnated with resin can be wound around a mold or jig at high speed, which has the effect of obtaining a structure with higher strength than before and increasing productivity.

[Brief explanation of drawings]

Figure 1 shows a cross-sectional view of the structure in which the present invention is being implemented. ).In the figure, 1...Girder 2...Resin-impregnated fiber 3...Hook 4...Straight section 5...Resin 6...Bubble patent applicant Toyota Motor Corporation Toyota Boshoku Co., Ltd. Figure 1, Figure 2゜

Claims (1)

[Claims] After the filamentous fiber reinforced material impregnated with the resin liquid is wrapped around a winding form of the desired shape and laminated, heating under reduced pressure and pressurization are repeated to remove air bubbles in the resin, and then the temperature is raised to form the resin. A method for producing a fiber-reinforced resin structure, characterized by curing the structure.