PRODUCTION OF COMPOSITION OF DYE AND/OR BRIGHTENER

摘要

PROBLEM TO BE SOLVED: To obtain the subject composition capable of developing through-flow rate and operation reliability even under low operation pressure by desalting an aqueous suspension containing a specific dye and/or a brightener and an inorganic synthetic salt by using a specific microfiltration membrane. SOLUTION: An aqueous suspension containing (A) a dye and/or a brightener containing at least one free SO3H and/or COOH group [preferably a compound of the formula (M is +N(CH3)4 or the like) and (B) an inorganic synthetic salt is desalted by using a microfiltration membrane having 0.05-40μm pore diameter to give the objective composition of the component A from which the component B is removed. After the desalting, the suspended component A is dissolved by adding hydroxide, carbonate and/or hydrogencarbonate of an alkali or ammonium and/or an amine. Preferably, a colloidal and/or insoluble component is removed from the solution directly or after addition of another additive by using the microfiltration membrane having 0.05-40μm pore diameter.