Abstract: The invention relates to a process of synthesis at low temperature of polymers of the PVA (polyvinylamine) type on the basis the monomer vinylformamide. The polymerization claimed for the invention begins at around 0° C., is initiated by an original combination of redox and azoic catalysts, and is conducted under more or less normal pressure. The polymerization is conducted in water and is followed by direct hydrolysis. A powdered cationic PVA of high molecular weight is thereby obtained. The process may also be conducted in an emulsion at an initiation temperature of around 15° C. Application of PVAs as flocculants and coagulants in the paper, water treatment, petroleum and parapetroleum, and, similar industries.

Abstract: The invention relates to an improved paper production process, according to which a branched polymer prepared in reverse phase emulsion is used as the main retention aid, and then bentonite is used as the secondary retention aid (a dual type system). The two additions are separated by a stage for shearing the fibrous suspension (or mass).

Abstract: The invention relates to an improved paper production process, according to which a branched polymer prepared in reverse phase emulsion is used as the main retention aid, and then bentonite is used as the secondary retention aid (a dual type system). The two additions are separated by a stage for shearing the fibrous suspension (or mass).

Abstract: According to the present invention, a cross-linked polymer or copolymer formed by reverse phase emulsion polymerization from suitable water-soluble monomers or from mixtures of such monomers is used as a retention agent. The process according to the invention is characterized in that the cross-linked polymer is sheared before its introduction or injection into the suspension to be flocculated. This results in a distinct improvement in the retention, formation, drainage and other properties of the paper or paperboard sheet thus obtained, as a function of the shearing.

Abstract: Process for improving retention during the manufacture of paper, board or the like, which consists:first of all in adding to the fibrous suspension a first retaining agent formed by a cationic polymer of high molecular weight,then, optionally in shearing the flocs obtained,and finally, in adding to the suspension a second retaining agent of inorganic nature, characterized in that the second retaining agent is a kaolin pigment.