Vinyl acetate is polymerized to form polyvinyl acetate. The polymer can be saponified to give various grades of flocculent, flake, granular, and powdery polyvinyl alcohol with 99.9% and 88% alcohol solvency under different amounts of alkali. The polyvinyl alcohol solution has good film-forming properties. Emulsification. Polyvinyl alcohol is mainly used for the production of synthetic fibers, plastics, adhesives, coatings, new building materials, etc., and is widely used in the chemical industry, textile, printing and papermaking, tanning industry, construction and so on.
During the production process, the final polyvinyl alcohol precipitate produced by saponification must be pressed and dried to obtain the final product. Polyvinyl alcohol is more viscous and gel-like. The evaporation rate of surface water during drying is much faster than the migration of moisture inside the material to the surface of the particles. The migration of moisture is the limiting part of the drying speed. The heat required for this type of material is not large, and the drying speed is very slow. In general, direct drying with hot air is not suitable for the drying of such materials.
At present, most manufacturers use a vacuum rake dryer to dry polyvinyl alcohol. Vacuum rake dryer only jacket is the heat transfer surface, plus the material can not fill the entire cylinder, so the jacket area is only 60% can be effectively used, which led to a very large volume of vacuum rake dryer, occupying space Large, increasing the investment in civil engineering; the movement of materials in a vacuum rake dryer cannot maintain a strict first-in, first-ou