„Green“ writing with Wopex
Wopex is the latest innovation in the portfolio of Staedler, Europe’s largest manufacturer of felt-tip pens, erasers, wooden pencils, fineline leads for mechanical pencils, modeling clay and industrial plastiline.
One of the challenges faced by the Wopex project team was to identify a compound that would bond with the wood polymer material while ensuring a comfortable, non-slip grip. TPEs supplied by Kraiburg TPE delivered the solution.
The basic material for Wopex is a WPC (Wood Plastic Composite) containing 70% wood in a polymer matrix. The WPC, joining the TPE, makes for efficient manufacture in the co-extrusion process, entirely without solvents.
The materials are plasticised at temperatures from 130 - 180°C and are then fed to a specially engineered co-extrusion head. There the individual streams of resin are metered in the correct quantities and delivered at the required relative positions. Greiner Tool.Tec from Upper Austria developed the innovative co-extrusion tooling for the production of the pencil.
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, the material consists exclusively of PEFC-certified wood (Program for the Endorsement of Forest Certification Schemes) originating in German forests managed for sustainability. This increases the amount of wood utilised in each tree and reduces scrap, which can be as much as 80% when manufacturing conventional wooden pencils.
The transparency of the Kraiburg TPE compounds makes it possible to add colour in numerous variations, turning the TPEs used in Wopex into an optical highlight – a real design advantage.