The University of Akron

Agence Nationale De Valorisation De La Recherche (Anvar)

Alain Vidal

Joseph P Kennedy

Gerard Riess

Jean-Baptiste Donnet

Disclosed is a novel bigraft copolymer comprising a polyhydrocarbon backbone selected from the class consisting of aromatic homopolymers, saturated and unsaturated hydrocarbon homopolymers, such homopolymers having halogen functionality and copolymers and terpolymers formed therefrom, and two different branches which are selected from the group consisting of monovinyl aromatic compounds and isoolefins. The bigraft copolymer is formed by the selective sequential cationic initiation of a first charge of one monomer onto the backbone at specific functional positions thereon and in the presence of a suitable solvent and an alkylaluminum compound. The resultant monograft copolymer is subsequently subjected to a second charge of another monomer, in the presence of a suitable solvent and an alkylaluminum compound, which becomes polymerized at the remaining, different functional positions available on the backbone. Also described are steps for substituting desired functional groups on the backbone and for the separation and purification of the mono and bigraft copolymer products.

Bigraft copolymers and process for the preparation thereof

A process for grafting polymers on carbon black through a free radical mechanism comprising contacting of the black with the polymer and a thermal treatment. After formation of the carbon black mixture with at least one polymer, said mixture is degassed under vacuum at approximately room temperature, at least one substance acting as a solvent for said polymer is then introduced on said degassed mixture which is under vacuum, so as to form a solution of the latter containing the carbon black, said solution is heated with stirring at least at 50.degree. C until a carbon black bearing polymer grafts is obtained and the latter can, if desired, be separated by filtration or centrifugation of the unattached polymer solution. The carbon black products bearing polymer grafts as well as this carbon black itself are easily dispersed in solvents. They find valuable applications in paints, varnishes, printing inks, among others. The increase in dispersibility of the grafted carbon black improves its efficiency as a pigment, ultraviolet screening agent, filler, antioxidant, and the like.

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Mulhouse, France

Alain Vidal