This is a bit technical. Hopefully, the below information gives you a basic picture of the differences and similarities:
(A) “Waterborne PU” is just another word for “Water-Based PU,” where the raw material PU resin particles are dispersed in mostly water. To make synthetic leather, we coat this resin onto a substrate (e.g. release paper), and dry the resin with heat to form a soft, solid PU layer on the substrate. This is how we at Ocean Plastics (OPC) make our PU synthetic leather.
(B) “Wet-Process PU” refers to the traditional solvent-based PU, where the PU resin particles are dissolved in dimethylformamide (DMF), an organic solvent. To make synthetic leather, the manufacturer coats a layer of this solvent-based PU resin on a textile substrate and immerse the coated textile into tanks of water to coagulate the PU resin into a similar soft, solid PU layer on the substrate. Because of this water-tank process, people call this the “Wet Process,” so solvent-based PU with this process is called “Wet-Process PU.” However, during this process, more energy is consumed than the Water-Based system above, and the DMF would migrate from the PU resin to the water in the water tanks, creating chemical waste water problems. Meanwhile, DMF also vaporizes into the air as harmful VOCs for the human body and the environment. We do not use this method.
(C) Sometimes, we hear of “Wet-Process Water-Based PU.” How can water-based and solvent-based PU vocabulary be put together in the same phrase? Well, it’s the production process of synthetic leather again. Some manufacturers use water-based PU resin to make synthetic leather by coating the water-based PU resin on a textile substrate, then immersing the coated substrate into tanks of water filled with acids. Since the water-based PU resin is slightly alkaline, the acid in the water coagulates the PU resin into the soft, solid PU layer. Because water tanks are used again, but the raw material PU resin is water-based, people sometimes call this “Wet-Process Water-Based PU.” However, this process creates salt compounds left in the water, and the water becomes industrial waste water, creating a similar waste water problem like the traditional solvent-based Wet Process. The process also requires more energy consumption and water resource consumption than the Water-Based PU without wet process. We do not use this method