| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for producing a foamed propeller fan which has a thin wall and is high in rigidity, light in weight, good in blade shape, and excellent in low noise properties. SOLUTION: The foamed propeller fan having foamed structure at least in its blade part is obtained through a process (a) in which an expandable thermoplastic resin composition is plasticated, a process (b) in which the plasticated couxposition is injected into a mold cavity closed to be smaller than the volume of an aimed molding, a process in which the composition is cooled after the completion of injection to a state in which a solidified layer contacting a mold surface and an internal molten layer are mixed, a process (d) in which the volume of the cavity is expanded to the volume of the aimed molding by opening a mold, and a process (e) in which the molding is demolded after additional cooling. As the mold, with respect to the blade part, a mold in a shape in which the thickness of a minimum wall-thickness part is at least 1 mm, the thickness of a maximum wall-thickness part is 15 mm or below, and the periphery is substantially an arc-shaped terminal is used, the time of the process (b) is 5 sec or blow, and the time of the process (c) is within a range of Tmin-Tmax.
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