PURPOSE: To obtain a water-soluble metal-chelating agent capable of efficiently chelating a metal contained in water, excellent in biodegradability and free of a problem of eutrophication, and hence useful in the fields of a scaling- proofing agent, a builder for detergents, etc., of which a metal-chelating effect is required.
CONSTITUTION: A metal-chelating agent is constituted of a carboxyalkylated lignin deriv. [e.g. a lignin deriv. obtd. by digesting wood chips prepd. from coniferous and/or broadleaf trees as the pulpwood with acetic acid and hydrochloric acid, immersing the resulting lignin prepd. through digestion with acetic acid in an aq. soln. of an alkali to effect a treatment thereof, dispersing the treated lignin in an org. solvent (e.g. 1,4-dioxane), and adding a monohalogenoalkylcarboxylic acid (e.g. monochloroacetic acid) to the dispersion to effect a reaction therebetween].
NODA NAOKO
TAKIZAWA MASAHIRO
