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24. March 2010

Material challenge for the "Dragon Castle"

For the latest highlight of Playmobil, the Great Dragon Castle, developers had to meet multiple challenges. One of them was the dragon itself, with a total of eight injection moulding tools, of which four had to be designed for multi-component injection moulding.

To meet current safety regulations, parts of the dragon's body that could potentially cause injuries, had to be "defused" by the use of TPEs. But the selection of the materials was not that simple. Since the dragon body is made of ABS, the soft materials for the spiky back and the claws of the toy beast had to be adhesion-modified.

For this task German compounding specialist PTS, based in in Adelshofen-Tauberzell, delivered special adhesion-modified grades coming from its-Thermoflex-A1/B family. Due to the high polarity of these materials, the adhesion to ABS is very good, but in case of the dragon wing, the large area in contact with the mould led to severe demoulding problems. On top of this, the soft component had to be highly transparent to implement the colour effects, required by the Playmobil design department. After checking all technical properties, Robert Banker, technical director at Playmobil gave the green light to try out a new hard/soft material combination from PTS. The company developed an ABS blend for the rigid elements of the wings (PTS-Creablend-F) with adhesion to all standard TPS-grades (SEBS) and TPV-grades (EPDM/PP). For the soft parts, a highly transparent TPS-grade (PTS-Thermoflex) with a hardness of approx. 85 Shore A was selected. The choice of a non-polar material that is easy to process, was crucial to allow an automated production.

PTS-Creablend-F is said to show low warpage, high dimensional stability and chemical resistance. The company points out that this material combines the dimensional stability of ABS with the chemical resistance of polypropylene and this should as well be interesting for the automotive industry and the electric appliances industry. Furthermore, the material complies with all relevant provisions for food contact.

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