Abstract: A method for manufacturing a sheet of paper and/or board having improved retention and drainage properties is provided, according to which, before the formation of the sheet and/or board, at least two retention aids are added to the fibrous suspension. These two retention aids are a main retention aid corresponding to a (co)polymer having a cationic charge density above 2 meq/g, obtained by the Hofmann degradation reaction, and a secondary retention aid corresponding to a water-soluble or water-swellable polymer having an anionic charge density above 0.1 meq/g. The main retention aid is introduced into the fibrous suspension in a proportion of 100 to 800 g/t of dry pulp, and the secondary retention aid is introduced into the fibrous suspension in a proportion of 50 to 800 g/t of dry pulp and has an intrinsic viscosity IV above 3 dl/g.

Abstract: Polymer complex obtained by polymerization of water-soluble monomers: in the presence of a host polymer comprising vinylamine functions and of a non-polymeric transfer agent, and in the absence of branching or crosslinking agent of ethylenic polyfunctional type.

Abstract: Cationic or amphoteric (co)polymer obtained by Hofmann degradation reaction, in aqueous solution, in the presence of an alkaline-earth and/or alkali metal hydroxide and of an alkaline-earth and/or alkali metal hypohalide, on a base (co)polymer comprising at least one nonionic monomer chosen from the group comprising acrylamide (and/or methacrylamide) and N,N-dimethylacrylamide, is characterized in that the base (co)polymer is modified beforehand with at least one polyfunctional compound containing at least 3 heteroatoms chosen from N, S, O and P and each having at least one mobile hydrogen. Use as a flocculation, retention and/or drainage aid, and dry strength aid is contemplated.

Abstract: In a process for preparing cationic or amphoteric (co)polymers derived from acrylamide by a Hofmann degradation reaction in aqueous solution in the presence of an alkali and/or alkaline-earth metal hydroxide and an alkali metal hypohalide on a base copolymer, a solution of base copolymer on which the reaction is performed contains a polyvalent cationic salt representing at least 0.5% by weight, preferably from 2 to 10% by weight of the base copolymer.

Abstract: A cationic copolymer is obtained by the Hofmann rearrangement (also referred to as the Hofmann degradation reaction) in aqueous solution in the presence of an alkaline-earth and/or alkali hydroxide and an alkaline-earth and/or alkaline hypohalide, on a base copolymer comprising at least one nonionic monomer selected from the group comprising acrylamide (and/or methacrylamide), N,N-dimethylacrylamide and/or acrylonitrile The copolymer is branched after the Hofmann rearrangement, in the presence of at least one polyfunctional branching agent, and is soluble in water.

Abstract: A method for manufacturing a sheet of paper and/or board having improved retention and drainage properties is provided, according to which, before the formation of the sheet and/or board, at least two retention aids are added to the fibrous suspension. These two retention aids are a main retention aid corresponding to a (co)polymer having a cationic charge density above 2 meq/g, obtained by the Hofmann degradation reaction, and a secondary retention aid corresponding to a water-soluble or water-swellable polymer having an anionic charge density above 0.1 meq/g. The main retention aid is introduced into the fibrous suspension in a proportion of 100 to 800 g/t of dry pulp, and the secondary retention aid is introduced into the fibrous suspension in a proportion of 50 to 800 g/t of dry pulp and has an intrinsic viscosity IV above 3 dl/g.

Abstract: A method for producing paper, cardboard or similar materials, comprising, separately or in a mixture, adding to a fibrous suspension: at least one main retention agent comprising a cationic (co)polymer, and at least one dual retention agent comprising a crosslinked cationic (co)polymer obtained in the form of a dispersion and placed in solution prior to its introduction into the fibrous suspension with gentle stirring. The crosslinked cationic (co)polymer having—a UL viscosity of between 1.3 and 2.7 cps, preferably between 1.5 and 2.4 cps, and—an apparent cationicity ratio of between 25 and 75%. Optionally, before or after the dual agent or the main retention agent are added, one or more tertiary retention agent(s) selected from the group comprising mineral particles and organic polymers carrying anionic charges, is added to the suspension.

Abstract: A cationic copolymers of acrylamide obtained by the Hofmann rearrangement, using an alkali and/or alkaline earth hydroxide and an alkali and/or alkaline earth hypohalide, are provided. The copolymers can be used as strengthening agents for paper and/or coagulants. The copolymers have a desalination coefficient (Cd) higher than 0.6, higher than 0.65, or higher than 0.7.

Abstract: Cationic or amphoteric (co)polymer obtained by Hofmann degradation reaction, in aqueous solution, in the presence of an alkaline-earth and/or alkali metal hydroxide and of an alkaline-earth and/or alkali metal hypohalide, on a base (co)polymer comprising at least one nonionic monomer chosen from the group comprising acrylamide (and/or methacrylamide) and N,N-dimethylacrylamide, is characterized in that the base (co)polymer is modified beforehand with at least one polyfunctional compound containing at least 3 heteroatoms chosen from N, S, O and P and each having at least one mobile hydrogen. Use as a flocculation, retention and/or drainage aid, and dry strength aid is contemplated.

Abstract: In a process for preparing cationic or amphoteric (co)polymers derived from acrylamide by a Hofmann degradation reaction in aqueous solution in the presence of an alkali and/or alkaline-earth metal hydroxide and an alkali metal hypohalide on a base copolymer, a solution of base copolymer on which the reaction is performed contains a polyvalent cationic salt representing at least 0.5% by weight, preferably from 2 to 10% by weight of the base copolymer.

Abstract: In a method of producing a sheet of paper and/or cardboard and similar products, prior to the formation of the sheet from a fibrous suspension, at least two dry strength agents are added to the suspension either separately in any order or mixed together and at one or more injection points, namely: a first agent corresponding to a product for Hofmann degradation in solution on a base (co)polymer comprising at least one non-ionic monomer which is selected from the group containing acrylamide and/or methacrylamide, N,N dimethylacrlamide and/or acrylonitrile; and a second agent corresponding to a (co)polymer having an anionic charge density greater than 0.1 meq/g. The Hofmann degradation product comprises an organic polymer produced at a concentration greater than 3.5% by weight, and preferably greater than 4.5% and the first and second agents are each introduced into the pulp suspension at a concentration of between 0.

Abstract: A method for making a sheet of paper and/or cardboard and the like, comprises, prior to forming said sheet, adding to the fibrous suspension, separately or mixed, in any sequence of introduction, into one or more injection points, at least three dry strength agents respectively: first agent corresponding to a (co)polymer having a cationic filler density higher than 1 meq/g and exhibiting primary amine functions; a second agent corresponding to a synthetic organic (co)polymer having cationic filler density higher than 0.1 meq/g; and a third agent corresponding to a (co)polymer having an anionic filler density higher than 0.1 meq/g.

Abstract: A cationic copolymers of acrylamide obtained by the Hofmann rearrangement, using an alkali and/or alkaline earth hydroxide and an alkali and/or alkaline earth hypohalide, are provided. The copolymers can be used as strengthening agents for paper and/or coagulants. The copolymers have a desalination coefficient (Cd) higher than 0.6, higher than 0.65, or higher than 0.7.

Abstract: A process for the manufacture of paper, board or similar products, comprises first of all, adding, to the paper pulp fibrous suspension, at least one main retention aid composed of a cationic (co)polymer. Then optionally the flocs obtained are sheared. Subsequently there is added to the suspension, separately or as a mixture, in any order: at least one secondary retention aid chosen from the group consisting of silica derivatives and anionic or amphoteric organic polymers, and at least one tertiary retention aid composed of a crosslinked anionic organic polymer with a size of greater than or equal to 1 micrometer and exhibiting an intrinsic viscosity of less than 3 dl/g.

Abstract: A cationic copolymer is obtained by the Hofmann rearrangement (also referred to as the Hofmann degradation reaction) in aqueous solution in the presence of an alkaline-earth and/or alkali hydroxide and an alkaline-earth and/or alkaline hypohalide, on a base copolymer comprising at least one nonionic monomer selected from the group comprising acrylamide (and/or methacrylamide), N,N-dimethylacrylamide and/or acrylonitrile The copolymer is branched after the Hofmann rearrangement, in the presence of at least one polyfunctional branching agent, and is soluble in water.

Abstract: The invention concerns an improved method for making paper, which uses a branched polymer prepared in invert emulsion as the main retention agent, and bentonite as a secondary retention agent (dual type system). The two additions are separated by a step for shearing the fibrous suspension (or mass). The invention results in highly improved retention and also highly improved dewatering. Moreover, it enables the bentonite content in white water to be reduced.

Abstract: A method for producing paper, cardboard or similar materials, comprising, separately or in a mixture, adding to a fibrous suspension: at least one main retention agent comprising a cationic (co)polymer, and at least one dual retention agent comprising a crosslinked cationic (co)polymer obtained in the form of a dispersion and placed in solution prior to its introduction into the fibrous suspension with gentle stirring. The crosslinked cationic (co)polymer having—a UL viscosity of between 1.3 and 2.7 cps, preferably between 1.5 and 2.4 cps, and—an apparent cationicity ratio of between 25 and 75%. Optionally, before or after the dual agent or the main retention agent are added, one or more tertiary retention agent(s) selected from the group comprising mineral particles and organic polymers carrying anionic charges, is added to the suspension.

Abstract: A process for the manufacture of paper, board or similar products, comprises first of all, adding, to the paper pulp fibrous suspension, at least one main retention aid composed of a cationic (co)polymer. Then optionally the flocs obtained are sheared. Subsequently there is added to the suspension, separately or as a mixture, in any order: at least one secondary retention aid chosen from the group consisting of silica derivatives and anionic or amphoteric organic polymers, and at least one tertiary retention aid composed of a crosslinked anionic organic polymer with a size of greater than or equal to 1 micrometer and exhibiting an intrinsic viscosity of less than 3 dl/g.

Abstract: In a method of producing a sheet of paper and/or cardboard and similar products, prior to the formation of the sheet from a fibrous suspension, at least two dry strength agents are added to the suspension either separately in any order or mixed together and at one or more injection points, namely: a first agent corresponding to a product for Hofmann degradation in solution on a base (co)polymer comprising at least one non-ionic monomer which is selected from the group containing acrylamide and/or methacrylamide, N,N dimethylacrlamide and/or acrylonitrile; and a second agent corresponding to a (co)polymer having an anionic charge density greater than 0.1 meq/g. The Hofmann degradation product comprises an organic polymer produced at a concentration greater than 3.5% by weight, and preferably greater than 4.5% and the first and second agents are each introduced into the pulp suspension at a concentration of between 0.

Abstract: A method for making a sheet of paper and/or cardboard and the like, comprises, prior to forming said sheet, adding to the fibrous suspension, separately or mixed, in any sequence of introduction, into one or more injection points, at least three dry strength agents respectively: first agent corresponding to a (co)polymer having a cationic filler density higher than 1 meq/g and exhibiting primary amine functions; a second agent corresponding to a synthetic organic (co)polymer having cationic filler density higher than 0.1 meq/g; and a third agent corresponding to a (co)polymer having an anionic filler density higher than 0.1 meq/g.