Basf Aktiengesellschaft

Basf Se Corporation

Isidor De Grave

Klaus Hahn

Christian Maletzko

Frank Braun

Franz-Josef Dietzen

Gerd Ehrmann

Uwe Keppeler

The invention relates to expandable polyolefin beads which comprise blowing agent and have been coated with from 0.01 to 3% by weight of a salt and/or ester of a long-chain fatty acid, preferably with calcium stearate, to prevent caking during foaming.

Expandable polyolefin particles

A process prepares expandable propylene polymer beads by mixing propylene polymer melt with a volatile organic blowing agent and with a nucleating agent in an extruder, whereupon the extrusion and pelletization of the extruded takes place in a water bath under conditions of temperature and pressure at which practically no foaming of the pellets takes place.

Preparation of expandable propylene polymer beads

The invention relates to expandable olefin bead polymers which comprise a blowing agent with a boiling point of from &minus;5 to 150&deg; C., selected from the group consisting of alkanes, alkanols, ketones, ethers and esters. The particles are unfoamed and have a bulk density above 500 g/l, and can be foamed to a bulk density below 200 g/l after storage for one hour at room temperature in free contact with the atmosphere. They are prepared by impregnating polyolefin pellets in suspension in a pressure vessel with the blowing agent, cooling the batch below 100&deg; C., reducing the pressure and isolating the particles.

Expandable olefin bead polymers

Growing community of inventors

Wachenheim, Germany

Isidor De Grave