To obtain a fly wheel hard to generate a crack even if rotated at a high speed and excellent in durability by winding an epoxy resin prepreg containing reinforcing fibers arranged in one direction so that reinforcing fibers are oriented in a peripheral direction to constitute fiber reinforced plastic and setting the voids thereof to a specific value or less.
In a wet method, an expoxy resin compsn. is uniformly mixed with a solvent having epoxy resin dissolving capacity such as methyl ethyl ketone and, thereafter, reinforcing fibers arranged in one direction are immersed in the resulting soln. so that fiber content becomes a desired value to be allowed to run and the solvent is volatilized from the resin impregnated reinforcing fibers in a hot air dryer. In a hot-melt method, the uniformly kneaded resin compsn. is applied to a releasable film coated with silicone or the like to form a resin film which is, in turn, held between at least one surface of reinforcing fibers arranged in one direction to be heated and pressed to impregnate the fibers with the resin. Voids are made hard to generate in fiber reinforced plastic and void vol. can be reduced to 3% or less.
YAMANE SHOJI
MATSUKISONO KASUMI
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