With the enhancement of people's awareness of environmental protection, people pay more and more attention to their living environment. Traditional solvent - based polyurethane adhesive has following disadvantages, toxic, flammable, peculiar smell, easy to cause air pollution,etc. Water-based paint has following advantages, its is non - toxic, non - flammable and non - polluting environment,etc. And waterborne polyurethane topcoat paint has following advantages, high hardness, strong adhesion, corrosion resistance, good solvent resistance, low VOC content, etc. It is a binary colloid system with water as dispersing medium, which meets the requirement of environmental protection in chemical industry. However, the general polyurethane emulsion solid content is low, the water resistance of the film is poor, the gloss is low, the comprehensive performance of the film is poor. The comprehensive properties of waterborne polyurethane topcoat paint
can be improved and the application range can be expanded by appropriate modification of waterborne polyurethane emulsion. Among the various modification methods, the most attractive one is the study of polyurethane/polyacrylic acid modified (PUA) composite emulsion. PUA modified resin integrates the best properties of the two materials to produce water-based resin with high solid content to reduce processing energy consumption and improve productivity. Its film is soft, wear - resistant, anti - wet wipe, and has excellent hydrolysis resistance. There are four kinds of emulsion polymerization methods of PUA: blend polymerization, copolymerization, core-shell emulsion polymerization and PUA interpenetrating network emulsion polymerization. Waterborne polyurethane was modified by epoxy resin E-44 and methyl methacrylate (MMA). Hydroxyethyl acrylate (HEA) copolymerizeswith MMA, producing core-shell cross-linked PUA composite emulsion with acrylate as the core, polyurethane as the shell, and HEA as the bridge between the core and shell. This composite emulsion has many advantages, such as Low temperature resistance, good softness and strong adhesion of polyurethane, water and weather resistance of acrylate, High modulus, high strength and chemical resistance of epoxy resin. The experimental results showed that: with the increase of the addition amount of e-44 and MMA of epoxy resin, the gradual improvement of hardness, tensile strength and water resistance of the film, the elongation at break and the stability of emulsion decreases. When the content of epoxy e-44 is 4% and the content of MMA is 20%~30%, the comprehensive performance is better.
The modified polyurethane has excellent comprehensive effects in the following USES: waterborne polyurethane topcoat paint
for wood ,waterborne polyurethane topcoat paint
for fabric, waterborne polyurethane topcoat paint
for building, waterborne polyurethane topcoat paint
for corrosion protection, waterborne polyurethane topcoat paint
for automotive,Waterborne polyurethane topcoat paint