Water-based polyurethane is a stable system that uses water as a solvent to disperse high-molecular-weight polyurethane into water at a high speed. Because of the presence of water, it is very different from solvent-based polyurethane during use.
Polyurethane film formation is through the evaporation of water, and the polyurethane micelles slowly gather to form a continuous film. The quality of the film directly affects the performance of the polyurethane product. Many applications need to add fillers to polyurethane. Too much filler will reduce the tensile strength, elongation and elasticity of polyurethane film.

The surface tension of most substances is 20-40 dyne / cm, while the surface tension of water is 72 dyne / cm, and the surface tension of polyurethane is 37-42 dyne / cm. The surface is difficult to wet, so many problems can occur during use. Therefore, we often add wetting agents, leveling agents, etc. to water-based polyurethane to improve the wetting ability of the substrate. The glue has good adhesion to the substrate. First of all, the substrate must be well wetted. Ensuring the wettability of the water-based polyurethane to the substrate is the key to ensuring its application performance.

As mentioned above, adding powder filler to waterborne polyurethane also involves wetting of powder materials. If the powder filler is not wetted well, the powder cannot be dispersed uniformly, so coarse particles are easy to be produced. , Layering, agglomeration, water separation and other phenomena. To disperse the powder well and stably exist, we not only need to use wetting agents, but also dispersants that anchor inorganic powders.

The world is ever changing, there are many kinds of materials, and the materials are constantly updated with the progress of the times. Different materials are selective for adhesives as well as selective for auxiliaries. Therefore, we need to combine formulas with actual substrates. Different substrates or application environments require targeted formulas. For example, polyurethane can be divided into polyester type and polyether type. Generally, polyester is more commonly used as an adhesive. From the isocyanate classification, it can be divided into aromatic and aliphatic. Aromatic high temperature or ultraviolet light is easy to yellow, and fat The clan is much better and does not even turn yellow. From the analysis of polyester structure, there are many choices. Polyester with good regularity has good crystallinity, can be quickly shaped, and has high bonding strength. The branched polyester does not crystallize and has good adhesion to many substrates. Speaking of wetting agents, there are many different types, such as silicones, fluorine-containing, acetylene glycols, ethylene oxide adducts, succinates and so on.