Production of New Cellulosic Filament Spun from Cellulose/aqueous NaOH Solution. (part 3). Spinning of Alkali Soluble Cellulose-Caustic Soda Solution System Using Sulfuric Acid as Coagulant.

Novel cellulose filaments from aqueous caustic soda solution were spun by sulfuric acid coagulation method on bench scale.In this spinning, the concentration of sulfuric acid was found to seriously affect on the structure and tensile properties of the yarn obtained.When draft ratio is constant, both degree of orientation and packing density which are measured as the degree of swelling of never dried yarn increase with an increase of the sulfuric acid concentration and the time of coagulation.It was inferred that dehydration effect of the sulfuric acid markedly increases with an increase of its concentration.The dehydration of the sulfuric acid gives rise to high shrinking stress in the coagulating yarn, leading to high orientation and packing density.Consequently, the yarn obtained showed high tensile strength and high initial Young's modulus.The shrinking stress due to the dehydration effect was calculated and it was found that the stress drastically increases when sulfuric acid concentration was 40-50wt%-Based on these facts, cellulose filament with tensile strength in dry state higher than that of regular viscose rayon was successfully obtained using sulfuric acid with concentration of 50-65wt%.