METHOD FOR THE HYDROLYSIS OF A POLYMER

The invention relates to a method for producing final polymer A containing the steps (A) providing a starting polymer V， the starting polymer V being obtainable by radical polymerization of the monomers (i) 25 to 90 mol% of a monomer of the formula (I) in which R 1 denotes H or C1-C6 alkyl， (ii) 3 to 65 mol% of a C1-C4 alkyl ester of acrylic acid or of a C1-C4 alkyl ester of methacrylic acid， (iii) 1 to 45 mol% of a monoethylenically unsaturated carboxylic acid， a monoethylenically unsaturated sulfonic acid or a monoethylenically unsaturated phosphonic acid， or salt forms thereof， (iv) 0 to 35 mol% of one or more ethylenically unsaturated monomers which are different from a monomer (i)， (ii) and (iii)， wherein the total amount of all monomers (i)， (ii)， (iii) and (iv) is 100 mol%， and (B) hydrolyzing the provided starting polymer V under alkaline conditions to obtain the final polymer A， wherein the N-C(=O)R1 groups of formula (I) at least partially hydrolyze the monomers (i) polymerized into the starting polymer V to form primary amino groups. Certain final polymers A obtained are useful for a method for producing paper or cardboard comprising adding certain final polymers A to a first aqueous pulp suspension， dewatering the obtained second aqueous pulp suspension containing certain final polymers A on a water-permeable substrate to a wet paper structure， and further dewatering of the wet paper structure into a paper or cardboard. The resulting paper or cardboard has good dry strength.