Agfa Gevaert Nv

Luc E Leemans

Philippe J Teyssie

Nikolaas C De Jaeger

Herman J Uytterhoeven

Walter A Verdyck

Roger M Fayt

According to the present invention a dispersant is provided for stabilizing dispersions of metal oxides and/or carbon black in water in the presence of a hydrophilic binder. Said dispersant is a block-copolymer comprising at least one block of an ammonium group containing (meth)acrylate.

Stabilization of dispersions of metal oxides and/or carbon black in water

Process for the preparation of polymers by anionic (co)polymerization of ethylenically unsaturated organic monomers in the presence of an arylmethide initiator of the following general structure: ##STR1## wherein: X.sup.+ represents a cation;

Anionic (co)polymerization using an arylmethide initiator

A surface-active block copolymer which comprises chemically linked polymeric blocks (A) and (B), block (A) of said copolymer consisting of at least one homo- or copolymerized non-polar alpha,beta-ethylenically unsaturated monomer and block (B) of said copolymer is derived by polymerizing an alpha-beta ethylenically unsaturated monomer containing an epoxy group and transforming the epoxy group into an hydroxy-substituted ionic group, preferably an anionic group. These block copolymers are used as dispersing agents in aqueous dispersions, including polymeric latex dispersions, and as plasticizing agent in hydrophilic colloid layers, including colloid layers containing a dispersed light-sensitive silver halide emulsion or other auxiliary substances for photographic materials.

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Diepenbeek, Belgium

Luc E Leemans