Soft packaging, also known as soft cans, has been used more than hard packaging, such as plastics, glass bottles and cans, because of its unique comprehensive properties such as light weight, convenience, long shelf life, sanitation, easy storage and transportation, easy disassembly, less garbage and good shelf effect. Due to its excellent properties, polyurethane adhesive can bond different film materials together to obtain composite films for flexible packaging with various properties such as cold resistance, oil resistance, drug resistance, transparency and wear resistance.