Liquid flame retardants for PU foams on the basis of s-heptazine-, s-triazine- and dicyanamide derivatives

• Applicant: Professor Dr. Edwin Kroke
• Subject Area: Preparatory and Physical Chemistry of Polymers ; Inorganic Molecular Chemistry - Synthesis and Characterisation ; Plastics Engineering ; Polymer Materials
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 426342087

Polyurethane and polyisocyanurate foams (PU-S, PIR-S) without flame retardants (FRs) are not suitable for thermal insulation in the construction sector as insulation panels and for other applications because they do not meet the required fire protection regulations. Therefore, predominantly chlorinated phosphate esters are used as effective FRs for PU-S and PIR-S. Due to their PBT potential (persistence, bioaccumulation and toxicity), these halogenated substances are included in the European Union's risk assessment and are expected to become significantly less available in the future. Alternative FRs are preferably nitrogen and phosphorus rich compounds, which should be liquid for a good processability and a uniform distribution in PU-S or PIR-S. The present project is therefore based on promising s-triazine, s-heptazine and dicyanamide derivatives, which have been successfully investigated by the project partners in joint previous studies. Corresponding liquid substances will be produced on a laboratory scale at the TU Bergakademie Freiberg (TUBAF) and examined structurally as well as with regard to their thermal properties. Particularly suitable compounds will be produced in larger quantities at the Fraunhofer Institute for Chemical Technology ICT, incorporated into PU foams and analyzed thermally and with regard to their FR properties. At the industrial partner, BASF Polyurethanes GmbH, the new halogen-free FR candidates based on s-triazine, s-heptazine and dicyanamide are being formulated (including PU catalysis) in various PU-S and PIR-S and tested on a laboratory scale. Subsequently, the specimens obtained are characterized in terms of their flame retardancy and other properties (thermal conductivity, mechanics, pore structure, etc.). In addition, the project includes a cost-effectiveness and environmental impact assessment of the substances. Since BASF manufactures melamine-based FRs, commercialization options are to be evaluated during the three-year project period, possibly involving other companies and / or research institutions and the project partners TUBAF and ICT. When exploiting the project results, it is important to point out the role of BASF as a PU manufacturer. BASF secures a leading position in the market through worldscale plants in all regions of the world and independently produces products such as polyols, diisocyanates, catalysts and additives for the entire range of PU applications. Novel flame retardant additives can therefore be successfully launched on the basis of the existing product portfolio. In addition to foams, the product range covers many other areas, which may result in novel fields of application for the s-triazine, s-heptazine and dicyanamide derivatives.

• DFG Programme: Research Grants (Transfer Project)
• Application Partner: BASF Polyurethanes GmbH
• Cooperation Partners: Professor Dr.-Ing. Peter Elsner (†); Dr. Carl-Christoph Höhne