Foam injection moulding of a TPO/TPC-blend and the effect of different nucleating agents on the resulting foam structure

Abstract

The manufacturing of car interior parts with a soft touch surface is possible in a one-step injection moulding process, in which an injection moulded carrier is overmoulded with a compatible foamed thermoplastic elastomer (TPE). In contrast to the complex conventional process the structural foaming of the TPE component allows a saving of one material component as it combines a compact skin and a foamed core. Furthermore the manufacturing process can be achieved on a two component injection moulding machine which offers a much higher economic efficiency. One approach to reach an adhesion between a reinforced PP carrier and the foamed TPE component including good surface resistance is the use of an olefinic-/polyester-based TPE blend (TPO/TPC-blend). This paper is going to show the possibility to process a TPO/TPC-blend system by foam injection moulding with MuCell® and how the resulting foam structure can be influenced by various nucleating agents. For this purpose particles which differ in type, form and size were added in various concentrations to the TPE-blend. Before the structure elucidation of the foamed samples the particle dispersion and their effects on the polymers rheological properties were investigated. Finally abrasion tests were performed to investigate the influence of the particles on the performance characteristics of the foamed blend system. The results showed that the foam structure as well as the surface quality of the foamed TPO/TPC-blend can be improved with the use of suitable nucleating agents. Furthermore the abrasion properties can be advanced with appropriate additives in the right dosage. © 2014 American Institute of Physics.