The fire resistant coating is based on HefCel technology (High-Consistency Enzymatic Fibrillation of Cellulose) developed and patented by VTT. The use of enzymes in production of  wood-derived nanocellulosic materials is cost efficient. The technology enables the production of cellulose nanofibril dispersions with a solids content ten times higher compared to the solids content achieved with traditional manufacturing methods. This makes HefCel an ideal material choice in applications where high-water content may cause problems eg. paints and coatings, packaging and composites.

HefCel material, photo by Eveliina Juuri

Bio-based fire-resistant coatings

The concept of a bio-based fire-resistant coating draw inspiration from nature and the bark of the Canary pine. The bark protects the tree from wildfires by its unique layered structure, which enhances charring upon burning. The char layer in turn, decreases the flow of gasses, oxygen going into the bark and volatiles coming from the bark. The FireCellCoat project aims at creating new fire-resistant coating, using phosphate-modified high consistency microfibrillated cellulose (HefCel) in two different approaches to create new wood coatings both for interior and exterior use. The use of MFC will bring many advantages, apart from being bio-based, as the new coatings should be non-toxic and leaching free. The key to achieve this is chemical bonding of the widely used fire retardant, phosphate, to HefCel, rather than using it as an additive.  

Interior wood coatings will consist of a layered structure by hybridizing phosphate modified MFC with plate like clay particles. In this one-step concept all materials play an important role in improving the fire resistance. Phosphorous groups bound to HefCel act as fire retardants, the clay gives a layered structure and the synergistic effects of modified MFC-clay structure promotes favorable charring of the HefCel, which prevents ignition. 

For wood coatings intended for exterior use, a more complex system must be developed, as they need to withstand harsh outdoor conditions. These wood coatings will be based on polymeric binders, both commercial ones and in-project produced copolymers containing MFC. Fire retardant properties will be enhanced by the addition of phosphate modified MFC.

Potential applications

FireCellCoat provides a novel approach for durable, high-performance fire-retardant materials based on sustainable resources. It could be applicable to numerous wood-based construction materials such as paints and decorative coatings.

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