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: 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.