Update:Water-based polyurethane uses water as the main medium and contains no or only a small amount of organic solvents. Accor...
uses water as the main medium and contains no or only a small amount of organic solvents. According to the different formulations and additives, it can be adjusted into coatings, adhesives and other treatment agents. Compared with solvent-based polyurethanes, it has the following characteristics:
1. Most water-based polyurethanes are solvent-free, odorless, pollution-free, non-flammable, and low cost.
2. Most one-component waterborne polyurethane products do not contain NCO groups, mainly relying on the intramolecular polar groups to generate cohesion and adhesion, and solidify after the water volatilizes. Waterborne polyurethane contains carboxyl, hydroxyl and other groups, and other reactive groups can also be introduced, which can participate in the reaction under suitable conditions to cause the resin to produce cross-linking. Add crosslinking agent (curing agent) to form a two-component system.
3. The main factors affecting the viscosity of waterborne polyurethane are emulsion particle size, ionic charge properties and quantity. When the solid content is the same, the viscosity of water-based polyurethane is lower than that of solvent-based polyurethane.
4.Because the volatility of water is worse than that of organic solvents, the water-based polyurethane adhesive dries slowly, and due to the large surface tension of water, the wetting ability of the surface hydrophobic substrate is poor.
5. Water-based polyurethane can be mixed with a variety of water-based resins to improve performance or reduce costs. Due to the compatibility of polymers or the solubility in some solvents, solvent-based polyurethanes can only be combined with a limited number of other Resin blending.
6. Water-based polyurethane products have little taste, can be diluted with water, are convenient to operate, and are easy to clean; while solvent-based polyurethanes sometimes need to consume a lot of solvents in use, especially the two-component materials and glues are not as clean as water-based glues. convenient.