Abstract
The strength, particularly their knot-strength, of polyvinyl alcohol fibers is known generally to be reduced by acetalization reaction. Acetalization is carried out in acidic aqueous solution, in which an antiswelling agent such as sodium sulfate is added in order to prevent swelling and shrinkage of the fibers during the acetalization reaction.
As a result of investigations on various formalization conditions such as reaction temperature, concentration of each component in reaction bath and pre-treatment with adequate swelling agents, it is found that the decreasing of the concentration of formaldehyde and sulfuric acid in reaction. bath is most effective to prevent lowering of their knot strength.
