Abstract: This invention relates to a method for manufacturing a sheet of paper or cardboard, according to which, before forming said sheet, at least one N-vinylformamide polymer that is partially hydrolyzed in the form of an inverse emulsion is added, at one or more injection points, to a fibrous suspension in the presence of an anti-gelling agent, and having a cationic regain between 30 and 150%, the inverse emulsion having a weight ratio of partially hydrolyzed N-vinylformamide polymer to anti-gelling agent in the range between 1,000,000/5000 and 1,000,000/50,000.

Abstract: A method for producing a sheet of paper or cardboard from a fibrous suspension, includes injection of a polymer P2 into a fibrous suspension, forming of a sheet of paper or cardboard, and drying the sheet of paper or cardboard. The polymer P2 is prepared, before injection of the polymer P2, from a water-soluble polymer P1 in the form of solid particles. Polymer P1 consists of at least one nonionic monomer selected from acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile. Polymer P1 is subjected to a reaction Re to yield polymer P2. The reaction Re includes the addition and the dissolution of solid particles of polymer P1 in an aqueous solution M1 of an alkali hydroxide and/or an alkaline earth hydroxide, and an alkali hypohalide and/or an alkaline earth hypohalide, prior to a reaction time of 10 seconds to 5 hours.

Abstract: This invention relates to a process for making a paper or cardboard sheet from a fibrous suspension, comprising the following steps: a) injecting a P3 polymer into a suspension of cellulosic fibers, b) forming a paper or cardboard sheet, c) drying the paper or cardboard sheet, the P3 polymer being prepared, prior to step a), from a water-soluble P1 polymer of at least one nonionic monomer selected from acrylamide, methacrylamide, N,N-dimethylacrylamide and acrylonitrile, the P1 polymer being subjected to an Re1 reaction to give a P2 polymer, which is then subjected to an Re2 reaction to give the P3 polymer, which is injected into the fibrous suspension within 24 hours of the start of the Re1 reaction, the Re1 reaction comprises preparing a P2 polymer comprising isocyanate functions by reaction for 10 seconds to 60 minutes between (i) an alkali hydroxide and/or an alkaline earth hydroxide, (ii) an alkali hypohalite and/or an alkaline earth hypohalite and (iii) the P1 polymer, the Re2 reaction comprises pre

Abstract: This invention relates to a process for making a paper or cardboard sheet from a fibrous suspension, comprising the following steps: a) injecting a P3 polymer into a suspension of cellulosic fibers, b) forming a paper or cardboard sheet, c) drying the paper or cardboard sheet, the P3 polymer being prepared, prior to step a), from a water-soluble P1 polymer of at least one nonionic monomer selected from acrylamide, methacrylamide, N,N-dimethylacrylamide and acrylonitrile, the P1 polymer being subjected to an Rel reaction to give a P2 polymer, which is then subjected to an Re2 reaction to give the P3 polymer, which is injected into the fibrous suspension within 24 hours of the start of the Re1 reaction, the Re1 reaction comprises preparing a P2 polymer comprising isocyanate functions by reaction for 10 seconds to 60 minutes between (i) an alkali hydroxide and/or an alkaline earth hydroxide, (ii) an alkali hypohalite and/or an alkaline earth hypohalite and (iii) the P1 polymer, the Re2 reaction comprises pre

Abstract: The invention relates to a method for producing anionic polymers that are hydrosoluble in an aqueous solution, comprising at least the following successive steps: b) polymerisation, in an aqueous solution, of anionic monomers containing at least 5 mol % of 2-acrylamido-2-methylpropane sulfonic acid and/or one of the salts thereof and optionally non-ionic monomers up to a mass concentration of polymer A of between 5 and 40%, b) addition of at least one aldehyde into the solution produced in step a), and c) acidification to a pH of between 3 and 4 of the solution produced in step b). The invention also relates to the use thereof in a paper-making method.

Abstract: A method for producing a sheet of paper or cardboard from a fibrous suspension includes injection of a polymer P2 into a suspension of cellulosic fibers, forming of a sheet of paper or cardboard, and drying of the sheet of paper or cardboard. The polymer P2 is prepared, before the injection, from a water-soluble polymer P1 in inverse emulsion form. P1 consists of at least one nonionic monomer selected from acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile. The polymer P1 is subjected to a reaction Re to yield a polymer P2. The reaction Re includes adding the polymer P1 in inverse emulsion form to an aqueous solution M1 of an alkali hydroxide and/or an alkaline earth hydroxide, and an alkali hypohalide and/or an alkaline earth hypohalide, prior to a reaction time of 10 seconds to 5 hours.

Abstract: A process for making a sheet of paper or cardboard from a fiber suspension, includes injection of a polymer P3 into a cellulosic fiber suspension, formation of a sheet of paper or cardboard, and drying of the sheet of paper or cardboard. The P3 polymer is prepared, prior to the injection, from a water-soluble P1 polymer of at least one nonionic monomer, such as acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile. The P1 polymer is subjected to a Re1 reaction to give a P2 polymer, which is then subjected to a Re2 reaction to give the P3 polymer, which is injected into the fibrous suspension within 24 hours of the start of the Re1 reaction.

Abstract: Equipment for preparing a polymer solution of a non-ionic, cationic, anionic or amphoteric polymer by reaction between a compound including at least one aldehyde function and at least one base polymer aqueous solution having at least one non-ionic monomer includes a reactor provided with a stirring system, as well as a recirculation loop including between the outlet of the reactor and the inlet of the reactor, a recirculation pump, a pH measuring probe, and a pressure differential in-line measuring device in the form of a calibrated tube configured to measure the pressure difference of the polymer solution between the inlet and the outlet of the calibrated tube, the calibrated tube being branched on the recirculation loop.

Abstract: This invention relates to a method for manufacturing a sheet of paper or cardboard, according to which, before forming said sheet, at least one N-vinylformamide polymer that is partially hydrolyzed in the form of an inverse emulsion is added, at one or more injection points, to a fibrous suspension in the presence of an anti-gelling agent, and having a cationic regain between 30 and 150%, the inverse emulsion having a weight ratio of partially hydrolyzed N-vinylformamide polymer to anti-gelling agent in the range between 1,000,000/5000 and 1,000,000/50,000.

Abstract: The invention relates to a method for producing anionic polymers that are hydrosoluble in an aqueous solution, comprising at least the following successive steps: b) polymerisation, in an aqueous solution, of anionic monomers containing at least 5 mol % of 2-acrylamido-2-methylpropane sulfonic acid and/or one of the salts thereof and optionally non-ionic monomers up to a mass concentration of polymer A of between 5 and 40%, b) addition of at least one aldehyde into the solution produced in step a), and c) acidification to a pH of between 3 and 4 of the solution produced in step b). The invention also relates to the use thereof in a paper-making method.

Abstract: Process for manufacturing a sheet of paper and/or of paperboard and the like, according to which, the cellulosic material is brought into contact with at least one dry strength aid, characterized in that said dry strength aid is a cationic or amphoteric (co)polymer derived from the reaction between at least one aldehyde and at least one base (co)polymer comprising at least one nonionic monomer, said base copolymer being modified with at least one polyfunctional compound comprising at least three heteroatoms chosen from N, S, O and P, in which at least three of these heteroatoms each have at least one mobile hydrogen.

Abstract: Process for manufacturing a sheet of paper and/or of paperboard and the like, according to which, the cellulosic material is brought into contact with at least one dry strength aid, characterized in that said dry strength aid is a cationic or amphoteric (co)polymer derived from the reaction between at least one aldehyde and at least one base (co)polymer comprising at least one nonionic monomer, said base copolymer being modified with at least one polyfunctional compound comprising at least three heteroatoms chosen from N, S, O and P, in which at least three of these heteroatoms each have at least one mobile hydrogen.

Abstract: Process for manufacturing a sheet of paper and/or of paperboard and the like, according to which, the cellulosic material is brought into contact with at least one dry strength aid, characterized in that said dry strength aid is a cationic or amphoteric (co)polymer derived from the reaction between at least one aldehyde and at least one base (co)polymer comprising at least one nonionic monomer, said base copolymer being modified with at least one polyfunctional compound comprising at least three heteroatoms chosen from N, S, O and P, in which at least three of these heteroatoms each have at least one mobile hydrogen.

Abstract: Process for manufacturing a sheet of paper and/or of paperboard and the like, according to which, the cellulosic material is brought into contact with at least one dry strength aid, characterized in that said dry strength aid is a cationic or amphoteric (co)polymer derived from the reaction between at least one aldehyde and at least one base (co)polymer comprising at least one nonionic monomer, said base copolymer being modified with at least one polyfunctional compound comprising at least three heteroatoms chosen from N, S, O and P, in which at least three of these heteroatoms each have at least one mobile hydrogen.