Synthetic leather slurry – Types of polyurethanes

Polyester-based polyurethanes take advantage of the excellent physical properties of polymers; they also have a higher viscosity (compared to polyether-based ones). They can be used to create rigid foams, but they are not resistant to hydrolysis. This type of polyester-based polyurethane is often used in shoe adhesives. Polyesters have good tensile strength and hardness ； Polyether-based polyurethanes have good hydrolysis resistance; however, polyethers are not resistant to ultraviolet radiation. They also possess other favorable physicochemical properties, and their softness can be adjusted. To enhance water resistance, PO-terminated versions should be used instead of EO-terminated ones, allowing for the creation of soft foams. Every product has its drawbacks; polyethers, for example, are not weather-resistant. However, aliphatic compounds are weather-resistant, so it’s not possible to generalize. It depends mainly on how the various raw materials are combined together. There are also poly**furan ethers, but the cost is high as well; however, they have good weather resistance. Nothing is absolute; moreover, some polyesters tend to crystallize, resulting in higher viscosity. If materials other than polyester are used, the viscosity will be lower. If these double bonds are not treated later on, it will still affect the weather resistance.