Preparation And Properties Of Waterborne Intumescent Fire-retardant Coatings For Wood

The waterborne intumescent coatings have many advantages such as easy to use, low cost and environmental friendliness. It can reduce the heat transfer in fire, protecting the wood substrate and decrease the fire hazard by the foamed char. In this paper, waterborne intumescent fire-retardant coatings for wood were prepared by using the blend of melamine urea-formaldehyde (MUF) and PVAc resin, and epoxy/acrylic resin as film-forming resin, respectively. The physical and chemical and fire-retardant properties of the coatings were evaluated. The structure and quality of the coat and char was studied, and the relationship between the char structure and the film fire-retardancy was discussed. In order to decrease or eliminate the loss and recrystallization of fire retardants from the film in service, an exploratory research on the preparation of fire retardant microencapsule was performed.After repeated tests, an optimized ratio of film-forming resin was obtained. In order to optimize the formulation of the intumescent fire-retardant system, ammonium polyphosphate(APP) and guanyl-urea phosphate(GUP) was used as the dehydration-carring catalyst, melamine(MEL) as the blister, and pentaerythritol(PER) as the spumific agent. Through the Uniform design and the subsequent evaluation, the optimized intumescent fire-retardant coatings formula D2for MUF-PVAC blend, U5and U7for epoxy/acrylic resin were obtained.The results of cone calorimeter (CONE) analysis showed that wood samples painted with D2, U5and U7respectively had much lower heat release and smoke release compared with unpainted wood sample controll.Through the method of TG analysis, FTIR analysis, it studied about the structure and the qualities of coat and char. The results showed that the mass loss rate of the synthesized coating was reduced obviously. The composite dehydration catalysts interacted at the different range of temperature, and intumescent fire-retardant system was approved to be synergistic with the film-builder. The majority of organic groups obviously reduced, or even disappeared in the foamed char. The overall fire-retardant and smoke suppressant performance of the intumescent waterborne modified-amino-resin fire-retardant coating were much better than the commercial intumescent waterborne fire-retardant coating.Spray drying and phase separation of the fire-retardant system was used to prepare fire-retardant microencapsules. The morphological difference between the two microcapsules was distinct. In the preparation of fire-retardant microcapsules by spray drying, it is important to keep the optimized import and export temperature and spray pressure, while for phase separation method it is critical to have a relatively higher ratio of the wall material to the core material.