Resin-molded component and method for manufacturing thereof as well as diaphragm for loudspeaker

Abstract

A resin-molded component such as a loudspeaker diaphragm, in which rigidity is enhanced while light weight and high specific modulus of elasticity are maintained, is formed by applying carbon dioxide gas with a predetermined pressure to a thermoplastic resin in which crystallization is facilitated in the resin flowing direction to fill a mold. After the resin is filled, injection molding is performed by somewhat moving the mold to form five layers of: oriented minute-foaming layers, having approximately cylindrical foams, the length of which is twice the diameter thereof in the resin flowing direction in the mold, an unfoamed core layer positioned between both the foaming layers, and unfoamed skin layers formed on the front and rear surfaces.

1 . A method for manufacturing a resin-molded component, comprising the steps of: 
 applying carbon dioxide gas with a predetermined pressure continuously to a thermoplastic resin, in which crystallization is facilitated in a resin flowing direction, to fill a mold, and    performing injection molding by moving the mold after said filling to form a five-layer structure of: a first foaming layer and a second foaming layer having substantially cylindrical foams, a length of said foams being twice or more a diameter thereof in the resin flowing direction in the mold, an unfoamed core layer positioned between the first foaming layer and the second foaming layer, and unfoamed skin layers formed as front and rear surfaces of the component.    
     
     
         2 . The method for manufacturing a resin-molded component according to  claim 1 , wherein 
 said thermoplastic resin in which crystallization is facilitated in the resin flowing direction is a resin material substantially composed of polyolefin composition containing ultra-high molecular polyolefin.