Hermann Berstorff Maschinenbau Gmbh

Gefinex Polymerschaeume Gmbh

Otto Deseke

Joachim Meyke

Armin Pfeiffer

Juergen Bruning

A method for producing a foamed granulate, wherein a thermoplastic synthetic material is placed in an extruder, the synthetic material is melted, a pressurized expanding agent is fed through one or several injection nozzles, the molten material enriched with the expanding medium is foamed as it exits through a perforated plate arranged at the outlet of the extruder and is granulated by a cutting device arranged behind the perforated plate. Also disclosed is a device for implementing the method and the foamed granulate. The invention is characterized in that the molten material is cooled in a controlled manner as it comes out of the perforated plate and exits directly into a flowing cooling medium, in that the temperature of the molten material and the temperature and pressure of the cooling medium are regulated in such a way that once the molten material exits the perforated plate, the surface of the molten material is directly hardened into a closed film with a smooth surface having a thickness that ranges from 10 to 500 &mgr;m, preferably 20 to 200 &mgr;m, whereupon the molten material is foamed and a granulate with a rounded surface and a bulk density of 10 to 600 g/l is formed. A semi-spherical granulate with a smooth surface is thus obtained.

Method of producing a foamed granulate

In a process and apparatus for producing TPE foam profiles, material is heated up in a conveying zone at a temperature of 180.degree.-210.degree. C. and a pressure of 100-200 bar. The melt then passes through a two-stage shear process consisting of two spaced shearing sections separated by a homogenizing section in which the melt and water are intimately mixed, with the melt being exposed to a further homogenizing section in which the melt is intensively mixed and homogenized prior to being extruded through a profile die.

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Lehrte, Germany

Otto Deseke