| Intumescent fire retardant coatings have broad application prospects due to the advantages of convenient construction,light weight,low cost,and high efficiency of fireproofing,etc.However,there are problems such as poor water resistance,poor resistance to aging,moisture sensitivity and so on in the application process,thus greatly reducing the fire resistance and service life.Based on the above situation,the modified core-shell emulsions and microencapsulated flame retardants were synthesized in this paper,and their applications in decorated and steel structure fire retardant coatings were studied respectively.The main research work of this paper is as follows:Changing the addition mode and amount of organic montmorillonite,a series of soft-core/hard-shell polyacrylate emulsions modified by montmorillonite were prepared using the monomers’ pre-emulsification and seeded emulsion polymerization.When 1wt.% of organic montmorillonite were added in the core layer of core-shell emulsion,the emulsion had good stability,small particle size,and the parallel-arranged montmorillonite in emulsion formed a barrier effect,which enhanced the water resistance of the emulsion and fire retardant coating.Due to the core-shell structure of the emulsion,the emulsion had two relatively small glass transition temperatures,which could be naturally formed film at room temperature.The surface of the film containing montmorillonite showed less wrinkles and it was suitable as a film-forming of fire retardant coating.When the modified core-shell emulsion was applied in a decorative fire retardant coating,the parallel-arranged montmorillonite enhanced the fire resistance,thermal stability and the density of the carbon layer.With the increase of montmorillonite,the fire resistance of the fire retardant coating firstly increased and then decreased,and the best was at 1.5wt%.The melamine formaldehyde resin microencapsulated APP was prepared by situ polymerization and characterized by Fourier transform infrared spectra,particle size test and scanning electron microscopy.According to GB 12441-2005,the effect of amount of MFAPP,emulsion,PER and MEL on the fire performance were investigated by simulating the big panel method.And the optimal formula was selected by three-factor three-level orthogonal experiment.Because of the synergistic effect between core and shell of microencapsulated APP,the fire resistance and thermal stability of APP and fire retardant coatings have been improved.In addition,due to the presence of the capsule,the solubility of APP was reduced,and the contact angle of APP and the coating were increased.The coating containing microencapsulated APP completely did not foam at all and the morphology remained throughout the accelerated water aging test.After the fire protection and thermal stability test,they showed that the microcapsulation of APP enhanced the durability of the coating. |
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