Dissertation > Industrial Technology > General industrial technology > Materials science and engineering > Special structural materials

Preparation and Characerization of Modified Nano Sized Coating for Hydrophilic Fins

Author ZhaoHui
Tutor ChenZhiMing
School Southeast University
Course Chemical processes
Keywords Nano hydrophilic aluminum foil coated material A latent epoxy curing agent Waterborne Polyurethane Acrylic Modified
CLC TB383.1
Type Master's thesis
Year 2005
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Hydrophilic aluminum foil air conditioner evaporator and condenser heat exchanger fin material, it avoids the surface of the heat exchanger fins light foil corrosive, easy barricaded water bridge, resulting in white powder, and reduce the efficiency of heat transfer defects so that the noise of the air conditioner to reduce to reduce energy consumption and promote the development of air conditioning direction toward energy conservation and environmental protection, and miniaturization. The the modified nano hydrophilic aluminum foil coating material primer and topcoat part primer taken waterborne epoxy resin has excellent corrosion resistance, its principle is to use waterborne epoxy emulsion and latent curing agent at elevated temperatures the reaction film. The latent epoxy resin curing agent prepared by the acrylate-modified imidazole curing agent, potassium persulfate as the initiator first with acrylic acid, methyl methacrylate, butyl acrylate, etc. The reaction temperature is 75 ℃ , the occurrence of a radical initiator prepared by copolymerization reaction of the acrylic resin has a certain hydrophilic and prepared, and modified imidazole compounds. When the latent epoxy curing agents with epoxy emulsion ratio of 1.5:1 or 2:1 complex with waterborne epoxy emulsion, the applicable period of up to two weeks or more, with some latent performance. Under high temperature conditions can be smooth and dense film corrosion resistance. The alkali resistance is greater than 5min, to meet the the alkali resistance requirements (lye in a concentration of 20% NaOH). Hydrophilic modified nano aluminum foil coating material topcoat taken prepolymer and methyl acrylate, vinyl pyrrolidone, acrylamide and other monomers in the use of the polyurethane resin used ammonium sulfate under the conditions of the water as a main solvent, as an initiator in the The copolymerization was carried out under the conditions of 70 ° C to 80 ° C, thereby forming a polymer interpenetrating network system polymer. Then, the dynamics of the research to verify the reaction time and the amount of the initiator of the reaction temperature and the influence on the reaction results. Obtained by the comparative experiment the following reaction conditions: The reaction temperature is from 70 ° C to 80 ° C, the dropwise feed was added dropwise for 3 hours, the holding time is 1 hour, the initiator is added in two the ratio is 6:4. Evaluation of the initial hydrophilic hydrophilic coating, continuous hydrophilic, water moisten adhesion performance using the reflection infrared, and scanning electron microscopy were used to characterize the surface of the film. Experimental data show that the initial hydrophilicity of the coating angle less than 5 °; continuous hydrophilic angle less than 30 °; water moisten good performance, water and dried five cycles not shrink; adhesion qualified. Found different primer emulsion and a pigment directly affects the performance of the topcoat, organic pigment containing topcoat in the active group may be a group reactive direct impact to the surface by a coating on the different primer coated with primer binding force, but also due to the consumption of the hydrophilic group, sustained hydrophilic of the topcoat will be affected. .

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