Preparation Of SiO₂ Aerogel/St-BA Emulsion By In-situ Polymerization And Its Application In Insulation Coating

The waterborne heat-insulating coatings can reduce internal surrounding excessive temperature rise of materials,and protection the materials.Therefore,research and develop a new insulation coating is an important topic. SiO2 aerogel is a dispersion medium with gas gel material, the porosity reaches as high as 80%～99.8%. Because of its unique structure, the SiO2 aerogel showed a lot of unique properties. The most typical is the thermal conductivity rate is very low, the thermal conductivity is only 0.013W/(m·K) under atmospheric, is the world's smallest thermal conductivity of solid materials.Therefore,join the SiO2 aerogel in coating will has good application value.The paper firstly modified the surface of SiO2 aerogel by KH-570,and SiO2 aerogel/styrene-acrylate emulsion was synthesized by the processing of seed emulsion polymerization,the ratio of raw material and technology were determined by theorical research as well as a lot of experiments.Finally,preparation the insulation coating by SiO2 aerogel/styrene-acrylate emulsion.And test the insulation effect by homemade insulation test device.The results of surface modification SiO2 aerogel:The particle size analysis shows that SiO2 aerogel have the best surface modification effect when KH570 content 5%. Through the infrared spectrum diagram analysis can be found, KH570 has been grafted to the surfaces of SiO2 aerogel. TEM analysis shows that granule dispersion were improved obviously when the surface of SiO2 aerogel was modified by KH570.The results of SiO2 aerogel/styrene-acrylate emulsion:emulsion has good comprehensive performance when SiO2 aerogel content 4%, soft hard monomer ratio for 50/50, functional monomer emulsifier acrylic as 4%, SDS/OP-10 content is 3% and SDS/best proportion of OP-10 for 2/1, initiator ammonium persulfate dosage 0.5%; DSC analysis results that glass transition temperature (Tg) of pure emulsion only 24.79℃, and SiO2 aerogel/styrene-acrylate emulsion glass transition temperature rise to 29.32℃. The analysis of ir spectrum diagram shows that SiO2 aerogel surface has grafted by polymer.TEM shows emulsion is spherical shape compared rules,and the modified SiO2 aerogel/styrene-acrylate emulsion have very good dispersibility.The results of heat insulation coating test:When SiO2 aerogel content 4% the coating hardness reach 4H and ultraviolet aging performance had obvious improvement. Through comparing the different SiO2 aerogel temperature curve, of coating had the best insulation effect when SiO2 aerogel content is 4%, but content was 1% insulation effect is the worst. Through the actual insulation effect, and the results show the insulating coating has obvious insulation effect, the temperature with blank glass floor was 10℃higher than heat insulation coating. SEM shows that the surface of coating was density and the inside do coating have many flake hole. Thermogravimetric analysis results show that the thermal of the coating was stability, thermal loss is only 4% before 331℃.Compared the heat insulationcoating of this paper with conventional coating,the paper insulation coating was better than conventional heat insulation coating both in gloss,colour and lustre. By the above conclusions we can see, the heat insulation coating with good mechanical properties and significant heat insulation effect will have the high potential application value.