The hottest partially hydrolyzed polyvinyl alcohol

  • Detail

Partially hydrolyzed polyvinyl alcohol is used for sizing and desizing

partially hydrolyzed polyvinyl alcohol is called PA grade, which shows obvious advantages in sizing, weaving and dyeing and finishing processes, surpassing the fully hydrolyzed grade (FH grade). In the sizing workshop, PA grade can be more soluble in the cooking pot at a lower temperature, and the sizing yarn is more likely to break at the warp separating rod. When the dyeing profession should be handed over to a professional to do the whole thing, PA grade can be desized at a lower temperature than FH grade, even when the test result of the horizontal angle converted to Richter value is hld757 after heat setting, and it can be recycled like other PVA. In the weaving workshop, PA grade has good adhesion to polyester, which is conducive to improving the wear resistance of sizing. In a word, PA grade can save costs through low energy consumption in sizing and desizing and less warp break in weaving

pva manufacturing does not start with vinyl alcohol monomer. Because vinyl alcohol monomer does not exist, it can only be polymerized by vinyl acetate (VAM) monomer. By changing the reaction conditions, the degree of polymerization is controlled, that is, the chain length of the polymer is controlled, that is, the molecular weight of polyvinyl acetate is changed. The higher the molecular weight of polyvinyl acetate, the higher the final molecular weight (and solution viscosity) of PVA. Then, polyvinyl acetate is saponified into polyvinyl alcohol, which is called alcoholysis. If the alcoholysis reaction is complete, PVA with complete hydrolysis can be obtained; The equipment cannot move up and down. On the contrary, if the reaction is carefully controlled, partially hydrolyzed PVA can be obtained. The percentage of hydrolysis is the percentage of acetate group replaced by hydroxyl group

changing the degree of hydrolysis can lead to changes in the properties of PVA. 98% hydrolyzed completely hydrolyzed grade (FH grade) is solvent resistant, firm, and has good adhesion to hydrophilic substances such as cotton and paper. The partial hydrolysis grade (PA grade) with 88% hydrolysis has poor water resistance than the complete hydrolysis grade, and has good adhesion to hydrophilic substances and hydrophobic substances such as polyester. In fully hydrolyzed PVA, one component reduces the production of packaging waste. Quantum hydroxyl groups are easy to form hydrogen bonds with another molecular hydroxyl group, producing a strong, crystalline polymer chain. PA grade contains loose acetate group, which is not easy to form hydrogen bond, so it is weak and has poor water resistance

Copyright © 2011 JIN SHI