Forest product- A component in the underbody coating and seam sealer of cars

Purpose and goal

Volvo Cars, together with most other manufacturers, uses PVC as a sealant and damping compound in the body construction. The use of PVC has been debated for a long time as it is softened with fossil-based phthalates, which are suspected to adversely affect both humans and the environment. The purpose of the project was to phase out these hazardous chemical substances and replace them with bio-based health and environmentally compatible substances, such as lignin. The produced sealant would have similar mechanical and physical properties and have a lower cost.

Expected results and effects

The final lignin-based seal formulation has been found to meet a number of set requirements in the project such as compatibility, temperature stability, flexibility and cost neutrality compared to PVC. However, the adhesion requirement between paint and sealant was not fulfilled. This means that the seal is not coatable, which is a basic requirement for being able to implement the material. There are still possibilities to use the jointing compound where coating with color pigment is not a requirement.

Planned approach and implementation

In Stage 1, a matrix was made over raw material and various lignin fractions. In addition, a cost estimate was made. Oversight was kept on the cost all the way. In Stage 2, quality improvements were made to the jointing compound: Blisters were eliminated in the jointing compound and adhesion became strong. In Stage 3, the composition of the jointing compound was refined it changed from being brittle to soft. In the overpainting experiment in Stage 4, it was found that the jointing compound and Volvo Cars´ paint systems is not compatible. The price level went against acceptable.