Process for the preparation of polymeric acetal carboxylates

Abstract

The alkali metal, ammonium and alkanol ammonium salts of polymeric acetal carboxylates are stable detergent builders under laundry use conditions but depolymerize in acid media, making the polymer fragments more readily biodegradable in waste streams. Such polymeric acetal carboxylates can now be made by the process of the present invention which comprises: bringing together an ester of glyoxylic acid and a polymerization initiator under polymerization conditions; adding to the resulting polymer a sufficient amount of trichloroacetic acid or trifluoroacetic acid, preferably trifluoroacetic acid, to provide temporary stability to the polymer during subsequent operations; optionally contacting the temporarily stabilized polymer with an immiscible solvent to obtain a polymer of greater purity; providing to the polymer in the presence of a miscible solvent, preferably acetonitrile, a sufficient amount of trichloroacetic acid or trifluoroacetic acid, preferably trifluoroacetic acid, to act as an endcapping catalyst; and adding an alkyl vinyl ether having up to about 20 carbon atoms in the alkyl group, preferably ethyl vinyl ether, to provide a chemically stable end group at the polymer termini to stabilize the polymer against rapid depolymerization in alkaline solution.

Dependencies are inferred from the claim text.