| Epoxy resin has many excellent comprehensive properties, such as the strong coherence,adhesive force on base material and resistance to pressure, resistance to wear, corrupt, high and low temperature are outstanding, low curing shrinkage rate, at the same time, it is easy to processing molding and low cost. Currently, it is widely used in the field of casting material, molding, adhesives, paints, building materials, construction machinery, aerospace, insulation materials and advanced composite materials. Pure epoxy resin is hard and brittle, impact strength, flexibility and wet and heat resistance is poor. In order to further improve the practical value of the epoxy resin, meet the demand of more applications, usually epoxy resin would be modificated, in order to get more extensive application in the practical production.For the properties of high adhesion and excellent resistance to corrupt, epoxy coatings has widely used in the areas of housing, food storage tanks, steel corrosion and other areas. Its excellent properties not only be fully reflected in the solvent-based paints, but also the full application in aqueous paint. With requirements of environment protection and people’s health are increasingly urgent and strict, the application of conventional solvent-based epoxy resin has been greatly restricted. The structure of epoxy resin determines it does not dissolve in water, dissolved only in organic solvents. Therefore, more and more researchers focus on the research of water-borne epoxy resin. There are mainly two methods to prepare water-borne epoxy resin until now, one is applied emulsifier method which includs mechanical method and phase reversion method, another is chemical modified method which including esterification reaction type, etherification reaction type and grafting reaction.Firstly, this article studies a method of preparation of waterborne epoxy coatings. Add defoamers, leveling agents, cellulose and other additives and titanium dioxide, talc, fumed silica filler into waterborne epoxy emulsion, then mixed with epoxy curing agent and coated on tinplate sheet. Examine the coating surface phenomenon, adhesion, impact resistance, hardness, flexibility and water resistance, acid and alkali resistance, salt water resistance. Discuss the influence of different amount of epoxy emulsion, pigment volume concentration (PVC) and the various additives on the properties of the film. Finally found the optimal ratio of resin and additives as well as the critical pigment volume concentration (CPVC), thereby get the new waterborne epoxy coatings with excellent properties. The results show that when the epoxy content more than 20%, the decoration and mechanical properties of the coating would be better When the PVC content is 45%, the adhesion, water resistance and flexibility achieve the best results. In terms of pigments and fillers, titanium dioxide fully cover the substrate when content more than 5 percent. With the increasement of the amount of talc, the film’s impact resistance, adhesion, flexibility and hardness are showing a decreasing trend after the first increase. In terms of additives, defoamers, leveling agents and hydroxyethyl cellulose have little effect on the mechanical properties of the coating, when the dosage of defoamer is 0.09% and leveling agents is 0.13% accounted for the total proportion, the surface phenomenon of coating is nice. Hydroxyethyl cellulose can effectively increase the viscosity of the paint, with the increasement of amount, the viscosity of the coating has been increasing, when the amount of cellulose in the range of 1 ‰-3 ‰, viscosity suits for brushing and spraying, meanwhile other properties are the best. Then, analysed the structure of the coating by infrared spectra, laser particle test, X-ray diffraction and scanning electron microscopy, investigate the binding of epoxy resin and fillers. Finally, developed a kind of multi-functional, environmentally friendly waterborne epoxy coating which suits for building, steel structures, machinery and equipment, electrical and electronic fields.In this article, in order to increase the flexibility of the epoxy resin, broaden its application scope, used polyurethane to graft modification of epoxy resin. Fluorinated polyurethane modified epoxy resin was synthesized by polyurethane prepolymer, prepared by MDI-50 and the polyether N210,and E-44 epoxy resin, used fluoroalcohol as end-blocking agent, discuss the influence of different graft compounds, different addition ratio, different capping agents and different curing agents to the mechanical properties of the modified polyurethane resin The results show that when the graft copolymer is a polyurethane prepolymer, which NCO content is 9%, the addition ratio of epoxy resin and polyurethane prepolymer is 2:1, low molecular weight polyamide as curing agent, the mechanical properties of the cured composition is the best. The glass transition temperature of the cured epoxy resin is 102℃ after modified. Heat decomposition divided into two stages, the first stage the initial decomposition temperature is about 296℃, the initial decomposition temperature of the second stage is about 647 ℃, compared to unmodified,the temperature increased. Research the curing case by infrared spectroscopy of resin, and investigate nonstick by contact angle test, found that the contact angle of polyurethane prepolymer modified epoxy and fluorinated polyurethane prepolymer modified epoxy are 90.5° nd 93.7°, compared to pure epoxy resin cured, the contact angle has been improved. Final selection of OP-10 and cetyl trimethyl ammonium bromide to get water-borne epoxy resins by applied emulsifier method and investigate the stability. |
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