Production method and technological proces of alginate fiber

　　As a natural polymer, alginic acid has a high relative molecular weight. The polymerization degree of high viscosity alginic acid extracted from brown algae is 600~1000, and the corresponding relative molecular weight is 120000~190000. Because the sodium salt of alginic acid can be dissolved in water, it is easy to prepare alginate fibers by wet spinning after dissolving sodium alginate in water to prepare spinning solution.

The salt formed by alginic acid and most divalent or multivalent metal ions is insoluble in water, so the aqueous solution of divalent metal ions can be used as the coagulation liquid. Because calcium chloride is cheap and has no toxicity to human b ody, it is the most commonly used production method in industry to produce calcium alginate fibers with calcium chloride as the coagulation liquid.


From a chemical point of view, the forming process of alginate fiber is a process in which water-soluble sodium alginate is transformed into water-insoluble calcium alginate. After divalent calcium ions are bound to carboxylic acid groups on adjacent alginate molecular chains through ionic bonds, calcium ions are surrounded between adjacent molecular chains, forming an egg box-like structure.

　

　　Technological process of wet spinning of seaweed fiber

　　The formation of this structure makes alginic acid lose its solubility, and at the same time, a large amount of water is surrounded between macromolecules, so that the nascent calcium alginate fiber forms a fibrous colloid with extremely high water content. Thomas et al. found in the process of studying t he formation of calcium alginate fiber that when sodium alginate solution is squeezed into calcium chloride aqueous solution through the spinneret, calcium alginate is quickly formed on the surface of the filament. After calcium chloride enters the cylindrical sodium alginate solution through preci pitated calcium alginate, it reacts with sodium alginate to form calcium alginate. Because the reaction speed between sodium alginate and calcium chloride is very fast, the gelation speed depends on the seepage velocity of calcium chloride.