Polyurethane (PU) has been used as sole and other materials since 1970s.
The main advantage of PU is that it is hard, flexible, durable and elastic in a large density range.
PU, also known as polyurethane, originated in Germany during World War II. PU is an environmentally friendly material, easy to hydrolyze, but its physical properties are very good in normal dry environment. First, it is light, easy to foam, can be sprayed with various colors, wear-resistant and fold-resistant, and more suitable for sandal soles, beach soles and leisure soles, photographic bags, etc.