US 12,441,860 B2
Polypropylene-based resin expanded bead, method for producing same, and molded article of polypropylene-based resin expanded beads
Takumi Sakamura, Tochigi (JP); and Hajime Ohta, Tochigi (JP)
Assigned to JSP CORPORATION, Tokyo (JP)
Appl. No. 18/569,292
Filed by JSP CORPORATION, Tokyo (JP)
PCT Filed Jun. 17, 2022, PCT No. PCT/JP2022/024274
§ 371(c)(1), (2) Date Dec. 12, 2023,
PCT Pub. No. WO2022/270426, PCT Pub. Date Dec. 29, 2022.
Claims priority of application No. 2021-105922 (JP), filed on Jun. 25, 2021.
Prior Publication US 2024/0279421 A1, Aug. 22, 2024
Int. Cl. C08J 9/18 (2006.01); B29B 9/12 (2006.01); C08J 9/228 (2006.01); B29K 23/00 (2006.01); B29K 105/04 (2006.01)
CPC C08J 9/228 (2013.01) [B29B 9/12 (2013.01); C08J 9/18 (2013.01); B29K 2023/12 (2013.01); B29K 2105/046 (2013.01); B29K 2105/048 (2013.01); B29K 2995/0082 (2013.01); C08J 2205/052 (2013.01); C08J 2323/14 (2013.01)] 10 Claims
OG exemplary drawing
 
1. A polypropylene-based resin expanded bead having a tubular shape with a through-hole, comprising:
a foamed core layer constituted by a polypropylene-based resin; and
a fusion-bondable layer covering the foamed core layer,
wherein
an average hole diameter d of the through-hole in 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,
a mass ratio of the foamed core layer and the fusion-bondable layer is foamed core layer:fusion-bondable layer=99.5:0.5 to 85:15, and
the polypropylene-based resin constituting the foamed core layer has a flexural modulus of 800 MPa or more and less than 1200 MPa and a melting point Tmc of 150° C. or lower.