Two-step Ether Amino Resin Synthesis, Characterization And Properties Of The Coating

Methyl etherified amino resin as cross-linking agent to prepared water-based paint in the paint industry has wide application, but the domestic etherified amino resin products are mostly dependent on imports, the own brand market share is low, and its products can’t achieve the performance of similar foreign products.Based on the above background, this topic focuses on the two step method of etherified amino resin synthesis, the concrete content includes: the synthesis and characterization of etherified amino resin and Amino acrylic paint coating performance study. Etherified amino resin synthesis process consists of the following two steps, step 1: melamine formaldehyde as raw materials by hydroxymethyl-hydroxymethyl melamine process; Step 2: A methylol melamine by etherification Preparation of a modified amino resin ether. Synthesis of optimum conditions been explored in experiments and Methylated amino resin further NMR, IR and GPC of synthesized according to different conditions. And amino resin cross-linked with acrylic resin film and do performance testing focuses on the proportion of cross-linked amino resin and acrylic resin, curing temperature and curing time of the film properties. Analysis of experimental data obtained the following results:(1)Methyl ether amino resin optimized synthetic conditions: melamine and formaldehyde molar ratio of 1:5.5, methylol melamine and methanol molar ratio of 1:6.5, catalyst and etherification stage hydroxymethyl stage acidic modifier respectively saturated sodium carbonate solution and hydrochloric acid solution, pH optimum of 8.5and 4.0. In this two-step reaction, hydroxymethyl stage reaction temperature is 45℃,reaction time after clarify the timing 25min; ether reaction temperature is 50 ℃,etherification endpoint by titration to determine tolerance.Under the optimized conditions, the synthesis of melamine formaldehyde resin having these properties include the free formaldehyde content ≤0.5%(wt), solids content of≥ 85%(wt), a viscosity range of 2600 mpa.s~5000mPa.s, storage time> 180 d, integrated performance.Products by 1H NMR and IR spectrum analysis indicates resin containing functional groups include hydroxymethyl groups, amino groups, methoxy groups, and GPC analysis results show resin has a moderate molecular weight and molecular weight distribution curve good. The average molecular weight of the resin is about 370, mainly composed of monomeric and dimeric composition.(2)Coating performance testing; Methyl etherified amino resin and water-basedacrylic resin solids mass ratio was 1:3, samples of coating curing temperature is 130 ℃the curing time of 30 min. Coating on hardness, adhesion, flexibility, impact resistance,corrosion resistance test, the experimental results show that under conditions of this experiment to optimize the preparation of methyl ether amino resin, and can effectively improve the crosslinked curing of coating and improve the coating brittleness. In addition, p-toluene sulfuric acid catalyst can improve the hardness and resistance to impact of coating, coating is in a good performance, especially with excellent adhesion,hardness and corrosion resistance.Compared with one-step method, raw materials can choose ordinary formaldehyde instead of paraformaldehyde, Meanwhile, the remaining waste formaldehyde and methanol may continue to be recycled; Methylol melamine and melamine etherified amino resin as the downstream product market, according to market demand for different products can be adjusted both production conversion. Compared to the one-step, two-step method is more suitable for the development requirements of domestic etherified amino resin production enterprises.