Preparation And Study On Performance Of Water-borne Intumescent Fire Retardant Coatings

Water-borne intumescent fire retardant coatings are widely used because of its advantages such as environmental protection,high flame retardant efficiency,fast drying and convenient construction.However,water-borne intumescent fire retardant coatings still have some deficiencies,such as the strength of the expanded carbon layer formed by the coating is low,resulting in poor fire resistance of the coating;the large amount of smoke generated by the coating causes the coating to be harmful when exposed to fire;poor water resistance of the coatings,resulting in coating short service life,small effect when in contact with water,and soon on.So for the above situation,layered double hydroxide(S-LDH,C-LDH and N-LDH)intercalated with spirocyclic phosphate ion,carbonate ion and nitrate ion,and ammonium polyphosphate microcapsule(MFAPP),zinc borate microcapsule(MFBZ)and aluminum hypophosphite microcapsule(PUFAHP)are prepared respectively in this paper,applying them to intumescent fire retardant coatings,and the effects of different kinds of layered double hydroxide and layered double hydroxide content on the fire resistance of fire retardant coatings and the effects of microencapsulated flame retardants on the fire resistance,smoke suppression and water resistance of fire retardant coatings are also studied.The main work of this paper is as follows:1.The aqueous acrylate core-shell emulsion is prepared by semi-continuous seed emulsion method,the coagulation rate and solid content of the emulsion are 2.96% and 47.72% respectively,the mechanical stability and calcium ion stability of the emulsion are excellent,the storage stability is more than 7 months;Three kinds of layered double hydroxide,C-LDH,N-LDH and S-LDH,are prepared by hydrothermal method using carbonate ion,nitrate ion and phosphorus-containing spirocyclic phosphate ion as anion intercalation agents,their layer spacing is 0.76 nm,0.88 nm and 1.44 nm,respectively,of which S-LDH has the largest layer spacing and the best thermal stability;When three kinds of layered double hydroxide are applied to the intumescent fire retardant coatings,they can enhance the strength and thermal stability of the expanded carbon layer,and make the carbon layer structure more uniform and compact.The thermal insulation ability of the expanded carbon layer was enhanced,among which,the coating with S-LDH has the best fire resistance,and the optimum addition of S-LDH was 4?5%.2.Ammonium polyphosphate microcapsule(MFAPP),zinc borate microcapsule(MFBZ)and aluminum hypophosphite microcapsule(PUFAHP)are synthesized by in-situ polymerization using melamine formaldehyde resin,polyurea formaldehyde as wall material and ammonium polyphosphate,zinc borate and aluminum hypophosphite as core materials,characterized by infrared spectroscopy,scanning electron microscopy,particle size analysis,etc.,proved that ammonium polyphosphate microcapsule(MFAPP),zinc borate microcapsule(MFBZ)and aluminum hypophosphite microcapsule(PUFAHP)have been successfully prepared;The water solubility and water contact angle test analysis show that after microencapsulation of BZ and AHP,the water solubility of the particles decrease,the hydrophobicity of the particles increase,and the water resistance of the particles is improved;Thermogravimetric analysis shows that the prepared MFBZ and PUFAHP have excellent thermal stability.The fire test analysis shows that the addition of MFBZ in fire retardant coating is about 6%,and the coating with 6% MFBZ has excellent fire resistance,when the fire test is 100 min,the back temperature is only 212 ?;Through thermal weight loss analysis and cone calorimeter test analysis show that the thermal stability of the coating with MFBZ can be effectively improved,and the amount of smoke is greatly reduced;The carbon layer analysis shows that after addition of the MFBZ,the expansion rate of the expanded carbon layer of the coating is smaller,more difficult to crack,more complete,and the carbon layer structure is more compact and density;The water contact angle test analysis shows that the water contact angle of the coating increases from 31.5°to 90.1° with the microencapsulation of APP and BZ,and the surface of the coating changes from hydrophilicity to hydrophobicity;Static immersion test analysis shows that after microencapsulation of APP and BZ,the coating is immersed in water for 72 h,the surface is not foamed and wrinkled,the appearance dose not change significantly,and the water resistance is obviously improved;The analysis of fire test before and after the water immersion of the coatings show that the microencapsulation of APP and BZ do not damage the fire resistance of the coatings,but improve the fire resistance of the coatings to a certain extent,and the fire resistance of microencapsulated coatings is much better than that of non-microencapsulated coatings.