Staedtler uses TPE compound in Wopex pencil

ERJ staff report (DS)

Waldkraiburg, Germany -- it looks like a pencil; it writes like a pencil, but instead of wood, it is made from a thermoplastic elastomer-wood mix. Staedtler, the Munich-based manufacturer of writing instruments has developed an environmentally-friendly alternative to the conventional pencil called Wopex.

The TPE is a highly transparent compound developed by Kraiburg TPE, which allows Staedtler to create Wopex pencils in a range of bright, vibrant colours. It ponds well with the graphite at the core of the pencil and can, of course, be extruded, leading to a cost-efficient manufacturing process.

The basic material for Wopex is a natural fiber laminate (or wood polymer material) containing seventy percent wood; the remainder comprises varying parts of plastics and additives. This make it possible to use the efficient co-extrusion process, offering lower energy costs and less waste than was the case in conventional pencil manufacture. The wood is used in its entirety. That is one of the reasons why this innovative pencil was recently also designated “Bio-Material of the Year 2009”.

The natural fiber laminate, joining the thermoplastic elastomers, makes for efficient manufacture in the co-extrusion process, entirely without solvents. The materials are plasticised at temperatures of from 130 to 180 degrees Celsius and are then fed to a specially engineered co-extrusion head. There the individual streams of resin are metered in the right quantities and delivered at the required relative positions. The advantages: Energy needs are trimmed and the number of steps in the process chain is reduced considerably when compared with conventional pencils. The wood used as the feedstock material is employed far more efficiently. In addition, that material consists exclusively of PEFC-certified wood (Program for the Endorsement of Forest Certification Schemes) originating in German forests managed for sustainability. This reduces scrap, which can be as much as eighty percent when manufacturing conventional wooden pencils.

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Press release from Kraiburg TPE