A POLYMER PRODUCT FOR IMPROVING RETENTION OF HYDROPHOBIC INTERNAL SIZING AGENTS IN MANUFACTURE OF PAPER OR BOARD

The invention relates a method for a manufacturing paper or board and to an internal sizing system for providing improved retention of hydrophobic internal sizing agents. An internal sizing system comprises a hydrophobic internal sizing agent as a first component selected from the group consisting of alkenyl succinic anhydride (ASA)， alkyl ketene dimer (AKD)， rosin sizes and any combination thereof， and a water-soluble polymer product comprising amphoteric polyacrylamide as a second component， which amphoteric polyacrylamide has neutral or cationic net charge at pH 7， a weight-average molecular weight of 700 000 – 18 000 000 g/mol and a total ionicity of 4 – 28 mol-%， wherein the first component and the second component are provided as separate components or as a combination of the first component and the second component. The invention relates a method for a manufacturing paper or board and to an internal sizing system for providing improved retention of hydrophobic internal sizing agents. An internal sizing system comprises a hydrophobic internal sizing agent as a first component selected from the group consisting of alkenyl5 succinic anhydride (ASA)， alkyl ketene dimer (AKD)， rosin sizes and any combination thereof， and a water-soluble polymer product comprising amphoteric polyacrylamide as a second component， which amphoteric polyacrylamide has neutral or cationic net charge at pH 7， a weight-average molecular weight10 of 700 000 – 18 000 000 g/mol and a total ionicity of 4 – 28 mol- %， wherein the first component and the second component are provided as separate components or as a combination of the first component and the second component.