EXPANDED BEAD AND METHOD FOR PRODUCING THE SAME

    公开(公告)号:US20220267552A1

    公开(公告)日:2022-08-25

    申请号:US17591725

    申请日:2022-02-03

    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.

    METHOD FOR PRODUCING POLYPROPYLENE-BASED RESIN EXPANDED BEADS AND MOLDED ARTICLE OF POLYPROPYLENE-BASED RESIN EXPANDED BEADS

    公开(公告)号:US20240400782A1

    公开(公告)日:2024-12-05

    申请号:US18699674

    申请日:2022-09-28

    Abstract: A method for producing polypropylene-based resin expanded beads each having a through-hole by performing a first expanding step and a second expanding step is provided. In the first expanding step, tubular resin particles containing carbon black and having through-holes are dispersed in a dispersion medium and released to an environment under a low pressure, thereby obtaining first-step expanded beads having a bulk ratio of M1 times. In the second expanding step, the first-step expanded beads are further expanded to obtain polypropylene-based resin expanded beads having a bulk ratio of M2 times. The bulk ratio M1 is 5 times or more and 25 times or less. A ratio M2/M1 of the bulk ratio M2 to the bulk ratio M1 is 1.2 or more and 3.0 or less.

    MOLDED ARTICLE OF POLYPROPYLENE-BASED RESIN EXPANDED BEADS AND METHOD FOR PRODUCING SAME

    公开(公告)号:US20240124674A1

    公开(公告)日:2024-04-18

    申请号:US18392071

    申请日:2023-12-21

    CPC classification number: C08J9/228 C08J2205/052 C08J2323/16 C08J2423/20

    Abstract: A method for producing a molded article of expanded beads includes filling tubular polypropylene-based resin expanded beads each having a through-hole in a mold, and supplying a heating medium to fusion-bond the expanded beads to each other. The expanded beads have a foamed layer constituted by polypropylene-based resin. A closed cell of the expanded beads is 90% or more. An average hole diameter (d) of through-holes of the expanded beads is less than 1 mm. A ratio [d/D] of the average hole diameter (d) to an average outer diameter (D) of the expanded beads is 0.4 or less. An open cell content of the molded article of expanded beads is 2.5% or more and 12% or less.

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