Study On Water-borne Polyurethanes For Coil Coating

With the rapid development of economy, the application of coated-coil gets more widely, quantity demand also gets bigger and bigger, the requirement of the coil coatings is rising. In view of the worldwide deep attention on energy conservation and environmental protection, coil coatings industry has been walking toward a high performance, economy and green path day by day. At present the coil coatings new topic mainly include:(1) environmental friendly. Development of the thick film without halide high solid content coating system, powder coating, coating, etc.; (2) energy-efficient. Development temperature curing coatings, UV cure coatings, etc.; (3) developing new functional coatings. Including from clean sex coating and anti-static coating etc; (4) improve polyester coating endure-climate property. This article is about preparation of new base resin through the synthesis methods of polyester polyurethane, combined with the application of coating production techniques of the pigments and fillers and additives, developed a new type of waterborne polyurethane coil coatings.1.First synthesize a new polyester polyurethane resin, its synthesis method is to copolymerize diisocyanate compounds and hydroxyl groups polyester with hydroxyl polyester over-dose to isocyanate, generating the water-borne polyurethane resin which containing hydroxyl groups. This method not only introduces a lot of ammonia ester keys, making resin improve many properties such as hydrolyzing stability, corrosion resistance, etc. Ensure that each macromolecule contain hydroxyl groups, making resin mix with crosslinking resin much easier. In addition, polyurethane resin has adjustability, through the adjustment of different proportion of composition content and different molecular of hydroxyl groups polyester, we can get a wide range of various performance.Choose appropriate polyisocyanates and polyols to synthesize the excellent properties of polyurethane resin material, and test the materials with solid content, size, infrared, thermal and mechanical properties, analyze it for seeing if each performance meets the actual requirements. Results show that:(1) The particle test shows the average particle of the resin emulsion are smaller than 100nm, and the particle size distribution is relatively concentrated, the emulsion has transparent appearance and long storage stability.(2) Infrared test shows, NCO reacted completely, and there are a large number of esters carbamate and a certain amount of hydroxyl existing in synthetic resin, according with the requirements of the coil coating base resin.(3) Through the DSC and TG we can see, resin has good thermal properties, high temperature resistant roasted, and adapt to the use conditions of low temperature.(4) Through the tensile test show that the breaking elongation data of synthetic resin is higher than common polyurethane resin and epoxy resin, so that it would have good flexibility and processing properties.2.Use homemade polyester polyurethane resin as base resin, crosslinking with amino resins, through the addition of the pigments and fillers, additives improvements, and adjust action of high molecular weight epoxy resin, we can make a series of waterborne polyurethane coil coatings. According to HG/T 3830 "the coil coatings "industry standard, do the sample preparation and performance detection, obtain the best coil coating formula through the analysis.3. We discussed the influence factors of the industrialized production of the water-borne polyurethane resin, mainly from the emulsifying process neutralization, water addition, mixing, to do the research of the synthesis technology resin operating standards.This subject will combine the good physical and mechanical properties and processing properties of polyurethane and the excellent properties of epoxy resin and polyester resin with various functional additives, for preparation the resin which has excellent adhesion and flexibility, better performance in wiping with the MEK and resistance of substrate with finish paint adaptability and supporting performance; Then by choosing appropriate anticorrosion pigment for paints, we can make excellent anti-corrosion primer; Through the appropriate use of fertilizer, solvents, make primer has excellent machining, construction performance. Excellent coil coatings not only has very good theoretical value, but also have a good application value.