Together with Sika AG, Switzerland, BASF developed a technology for PVC window frames that is significantly more filigree, yet stiffer. The newly developed SUR-technology using Ultradur® and a SikaFast® glue allows to create stiffness by help of the structural properties of existing glasses. Thus, the frames don’t need a steel reinforcement anymore and can be designed slimmer, thereby improving both vision and the u-value. Completely new PVC frame designs with state of the art energy ratings are possible with the new technology.