| Cathodic electrophoretic paint is a new kind of environmental protection electrophoresis paint,a modern cathodic electrophoretic paint after a short period of time in the inner car coating replaced the anodic electrophoretic paint,this is because the cathode electrophoresis paint excellent anti-corrosion performance.In modern times,cathodic electrophoretic coating technology has become one of the most important coating methods in the world,which is widely used and popularized in various countries.At present,domestic electrophoretic paint mainly comes from abroad,relying on independent research and development.So the research and development of a new type of cathode electrophoretic paint has a milestone significance.Cathodic electrodeposition paint process design technology at the core of the design is developed for cathodic electrophoretic coating of resin technology,this paper using polyethylene glycol(200)of modified epoxy resin as the main body of the resin,closed isocyanate as curing agent for the preparation of cathode electrophoresis paint.The research contents are:1.In this paper,we used bisphenol A and polyethylene glycol(200)to carry out the amines modification of epoxy resin and analyzed and studied the expansion chain and modification process.The effects of the molar ratio and reaction time of bisphenol A and peg on the stability and film performance of resin emulsion were discussed and modification of epoxy resin.The results show that: when the adjustment of bisphenol A and polyethylene glycol(peg)mole ratio was 2.5:1,reaction time is 6h,the reaction temperature 160?,through test to the cathode electrophoresis paint film hardness for 3 h,flexibility to 2 mm,the impact strength of 50 kg.cm,adhesion level 0,paint film acid-proof alkaline are better.2.Isooctanol and ethylene glycol butyl ether blocked 4,4'methylene diisocyanate(MDI)together,and the curing agent was prepared.The effects of the closing reaction time and the type of sealant on the curing temperature and film properties were studied and a series of characterization of the curing agent and lacquer film were carried out.The results showed that the controlled reaction time was 4h,the curing temperature was 150?,and the curing time was 20 min.3.The emulsification reaction of the modified epoxy resin and the curing agent under the action of the emulsifier was performed to obtain the emulsion with stable performance.The effects of emulsifier type,lactic acid and solvent addition on the properties of resin emulsion were studied.As follows: selection of lactic acid(80%)as the emulsifier,8% lactic acid(the percentage of resin),ethylene glycol butyl ether solvent(help)under the condition of12% of the mechanical stability of the emulsion is better.4.The color filler used in the cathode electrophoretic paint with good performance wasprepared by using pigment dispersible resin and filler according to certain ratio.Dispersion resin was studied and the ratio of filler,the thickening agent of fillers for the amount of solid content and stable performance and to the FT-IR and TGA analysis means such as the preparation of fillers for cathodic electrophoretic paints were characterized analysis.The results showed that the dispersibility of the pigments was better in the condition that the dispersion resin was 23%,the packing was 37%,the carbon black was 0.9%,the epoxy equivalent to 1090,and the grinding time was 50 min.5.It is said that a certain amount of the above emulsion,facial filler and auxiliary agent can be mixed in a certain proportion and then the required cathode electrophoretic paint can be prepared.The influence of bath temperature,liquid solid content,electrophoresis voltage and pH value of paint on the film thickness and performance was studied.Results show that the control of bath temperature 30?,liquid solid content 22%,electrophoresis voltage is 120 v,electrophoresis time of 3min,lacquer liquid pH = 6.2 the lacquer liquid performance is better. |
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