Development status of water-soluble membrane

u003cpu003eDevelopment status of domestic and foreign water-soluble film production technologyu003cbr /u003eu003cpu003e At present, the process methods for manufacturing PVA film at home and abroad mainly include solution salivation method (wet method) and extrusion blown film method (dry method). Both of these processes are 'born' from traditional plastic film production. Because PVA is a water-soluble substance, the film-making process conditions are different from those of thermoplastics, so the above two processes are directly applied to the production of PVA film, there are still many technical problems, and some economic problems, such as difficult quality control and efficiency Low energy consumption, large area, high equipment investment, etc. Therefore, research and improvement of these two types of process technology and equipment to make them more suitable for PVA film production is the focus of research and development in the domestic and foreign industries. u003c/pu003eu003cpu003eWater-soluble PVA film is a new type of plastic product that has emerged internationally in recent years and belongs to the plastic film manufacturing industry. As a novel green packaging material whose main raw materials are polyvinyl alcohol and starch, it has both water and biological degradation characteristics, and can be completely degraded into CO2 and H2O. It is a veritable high-tech and environmentally friendly product. It is recognized by the national environmental protection department in Europe, America, Japan and other countries. The water-soluble PVA film has excellent transparency and gloss, non-charged properties, large tensile strength and tear strength, good oil resistance, excellent gas barrier properties, heat sealability and adhesion, and high moisture permeability. It has the advantages of good mold release and metal plating, and has water solubility and biodegradability under certain conditions. Therefore, as a new packaging material, it has an extremely wide and unique use in flexible packaging. u003c/pu003eu003cpu003e The basic production process of the solution casting method includes: water-dissolved PVA → casting coating → drying (heat treatment) → peeling → coiling → finished product.　　　The process flow of the casting method is relatively simple, but the product quality is not easy to control, the film yield is low, the energy consumption is high, and the equipment investment is large. u003cbr /u003eu003c/pu003eu003c/pu003e