公开(公告)号：US12240956B2

公开(公告)日：2025-03-04

申请号：US17591725

申请日：2022-02-03

Applicant: JSP CORPORATION

Inventor： Takumi Sakamura ,  Hajime Ohta

IPC: C08J9/18 ,  B29C44/34 ,  C08J9/00 ,  C08J9/12 ,  B29K23/00

Abstract: An expanded bead having a tubular shape with a through hole and a method for producing the same are provided. The expanded bead includes a foamed core layer and a covering layer. A polyolefin-based resin included in the covering layer has a melting point lower than a melting point of a polypropylene-based resin included in the foamed core layer. An average hole diameter d of the through hole of the expanded bead is less than 1 mm, and a ratio d/D of the average hole diameter d to an average outer diameter D of the expanded bead is 0.4 or less. The polypropylene-based resin for the foamed core layer has a flexural modulus of 1,200 MPa or more and a melting point of 158° C. or lower.