Process for manufacturing paper or cardboard
AssigneeSnf Group
InventorsCyril Barriere, Bastien Martel
Life of this patent
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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.
Claims15
A method for producing a sheet of paper or cardboard from a fibrous suspension, comprising:
- a) injecting a polymer P3 into a cellulose fiber suspension,
- b) forming a sheet of paper or cardboard,
- c) drying the sheet of paper or cardboard,
- wherein the polymer P3 is prepared, prior to said a), from a water-soluble polymer P1 of at least one nonionic monomer selected from the group consisting of acrylamide, methacrylamide, N,N-dimethylacrylamide, and acrylonitrile,
- wherein 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;
- wherein the Re1 reaction consists of 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 hypohalide and/or an alkaline-earth hypohalide and (iii) the polymer P1,
- wherein the Re2 reaction consists of preparing a P3 polymer by reaction between (iv) a compound which is capable of generating at least one aldehyde function to the P2 polymer, and (v) the P2 polymer comprising isocyanate functions,
- wherein the method is free of any decarboxylation step after said Re1 and Re2 reactions.
Dependencies are inferred from the claim text.