To form a pipe inexpensively without deteriorating its strength characteristic by controlling the thickness of a thermoplastic film existing inside a fiber-reinforced plastic layer constituting the pipe within a specified range.
Although a thin FRP layer side thermoplastic film 2 reduces the total weight of a pipe, it may be broken when a base material such as a prepreg, which forms a fiber-reinforced plastic layer 1, is wound or during molding. Therefore the thickness is desirably at least 5 μm. When the film 2 is broken, a matrix resin, which forms the fiber-reinforced plastic 1 between the film 2 and a fluid side thermoplastic film, flows to make the extraction of the fluid side thermoplastic film after molding difficult. On the contrary, when the film 2 is too thick, the weight of the pipe is increased so that the thickness is preferably not exceeding 30 μm.
NISHI YASUHIRO
HARIGUCHI YOSHINORI
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