Development of a process for flame retardant coating of textiles with bio-hybrid anchor peptides

The fire protection of materials has an important role in our everyday life and covers a highly diverse spectrum of substances, materials, and fields of application. Important fields of application for fire protection, especially in public areas, are construction and transport, electronic devices, furnishings, and textiles (e.g., applications for occupational safety, carpets, curtains, upholstery, insulation, and technical applications in outdoor areas). The efficient and durable finishing of materials with flame retardant additives is crucial to ensure effective fire protection. Many of the flame retardant additives currently used are based on bromides, chlorides, phosphates, or antimony. However, these flame retardants are harmful to the environment and/or health (not phosphates). Therefore, the use of these flame retardants is already being restricted by EU directives (e.g., REACH regulation), and it is foreseeable that they will be further restricted in the future. To keep up with this development, innovative and sustainable solutions must be developed in the short term. The amount of flame retardant additives that are harmful to the environment and health must be reduced. In the medium term, these harmful additives must be completely replaced by sustainable flame retardant additives that are not harmful to the environment and health. This paper describes research results to reduce the amount of additives in the short term. In order to reduce the amount of additives used, an innovative refinement process is being developed. In a first step, the flame retardant additives are combined with bio-based adhesion promoters (anchor peptides). Anchor peptides bind with high selectivity, binding strength, and occupancy density to a broad portfolio of materials (e.g., synthetic polymers, metals, ceramics, and natural materials) and enable the finishing of the materials with a broad spectrum of functional units (e.g., flame retardant additives). Material functionalization by anchor peptides is energy-efficient and resource-saving at room temperature in aqueous solution and is scalable in its production. Based on these developments, in this paper, a finishing process is presented with which flame retardant textiles can be equipped with bio-based anchor peptides. A requirements' outline for the new finishing process is described. Established processes (e.g., foulard, coating machine, and roller application) are compared with each other and evaluated with regard to the requirements and their suitability. The most suitable process is then designed, and a laboratory scale as well as an industry scale concept are presented.