The polyurethane filter foam is opened and the film is opened to form a mesh structure of the main skeleton. The mesh cotton has a void ratio higher than 97%, an open porosity of 99%, good gas permeability and high mechanical strength. As a filter material, it has a small flow resistance and a high filtration efficiency. It can be washed repeatedly, showing the advantages of durability, economy and environmental protection. It is mainly used in filters in aquariums, filter layers in air conditioners, and carriers in ceramic foam filters. Valet processing can be cut into various shapes!