| In recent years, the glass fiber reinforced polymer has been widely used in theconstruction sector. Because of its easy construction, high strength and light weightetc., it has been widespread concern in the field of engineering. However, manydomestic and foreign research reports indicate that alkali resistance of GFRP is notideal, it is easy to be corroded by base, which would to affect their mechanicalproperties. Waterborne epoxy resin is a water-based paint which has excellentperformance. It has a lot of ether bond in the system, this makes it possible to stablyexist in the base. However, due to different raw materials and production methods,there are many types of water-based epoxy resin. In addition, it is difficult forwater-based epoxy resin to cure without curing agent. We know that etherifiedmelamine resin can be used as water-based epoxy resin cross-linking agent fromrelevant literatures.We synthesize waterborne epoxy resin and methanol-butanol etherifiedmelamine resins.And both of them have better performance.This paper study onseveral factors which would effect the properties of methanol-butanol etherifiedmelamine resin,the factors include reactant ratio, reaction temperature, reaction timeand pH. The paper also studies cross-linking of the two resins. The results are asfollows:In the role of potassium persulfate catalyst, emulsifier is synthesized bypolymerization between polyethylene glycol4000and epoxy E-44.Then waterborneepoxy resin is synthesized by inversion method. The results show that, when themolar ratio of polyethylene glycol4000and the epoxy resin is1:1, the catalyst ispotassium persulfate, the reaction temperature is180℃, reaction time is3.5h, theemulsifier has better performance. Then, when the stirring speed is800r/min, waterbath temperature is50℃, the composite waterborne epoxy resin has good stability.The methanol-butanol etherified melamine-formaldehyde resin is synthesized intwo steps and used as a curing agent of water borne paint. The best reaction condition is investigsted in ferms of the influence of temperature, time and pH. The resultsshow that, in the reaction stage of hydroxyl methylation, when the temperature is70℃, time is20min and pH is8.5, the methylol content is high and the content of freeformaldehyde is low in the system. In the etherification stage, when the temperatureis50℃,time is60min and pH is4.5, the resin have excellent storage performance.Formaldehyde content of the synthetic resin is low,and the resin has high storagestability.The paper studies cross-linking of the two resins. Several factors which wouldeffect the coating performance have been studied,such as reactant ratio, reactiontemperature, reaction time. The results show that, if curing agent usesmethanol-butanol etherified melamine-formaldehyde resin that molar ratio ofmethanol, butanol is8:2in the preparation, the mass ratio of crosslinking agent andWaterborne epoxy resin is1:2, curing temperature is200℃,and curing time is10min,the coating performance is better, its hardness is6H, adhesion is0, simultaneously ithas better uniformity and alkali.GFRP is processed under the best condition.Then the paper does quick alkaliexperiment. The results show that, flexural strength decreased rate of treated GFRP isless than the untreated GFRP. After a long period of lye corrosion, flexural strength oftreated GFRP is better than the untreated GFRP. This indicates that cured coating onthe reinforcement surface playes the role of better alkali.So, the methanol-butanoletherified melamine-formaldehyde resin synthesized in this paper can be used as acrosslinking agent of waterborne epoxy resin. The solidified membrane has somegood performance,such as hardness, adhesion, uniformity and alkali resistance,and itcan be used on the surface of GFRP to increase its corrosion resistance. It is helpfulto increase the life of the building structure. |
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