Foamed polypropylene resin beads and preparation method thereof

Patent abstract

A method for preparing an expanded bead, comprising: a base resin containing a polypropylene resin and having a tensile modulus of at least 1,200 MPa and a colorant and a thermoplastic polymer having a lower tensile modulus than the base resin The mixture is kneaded to form a kneaded mixture, a matrix including a base resin in the kneaded mixture, and a plurality of domains distributed in the matrix and each containing a thermoplastic polymer and a colorant. The kneading mixture is shaped into resin pellets, and then the resin pellets are surface-modified with organic peroxides to modify the resin pellets. The foamed and expanded surface-modified resin beads give expanded beads having an inner zone surrounded by a skin zone. The heat of fusion at the high temperature peak in the surface zone is lower than that in the inner zone.



Patent sovereignty

A process for preparing an expanded bead, comprising the steps of: (a) kneading a base resin containing a polypropylene resin and having a tensile modulus of at least 1,200 MPa and a mixture of a colorant and a thermoplastic polymer to form a kneading In the mixture, the thermoplastic polymer has a lower tensile modulus than the base resin, the matrix comprising the base resin in the kneaded mixture, and the matrix distributed in the mixture, each containing the thermoplastic polymer and the colorant (b) forming the kneaded mixture into resin pellets; (c) treating the resin pellets with an organic peroxide for surface modification; and (d) foaming and swelling the surface modification Sex resin particles are obtained to obtain expanded beads.