Method for producing paper, paperboard and cardboard

Abstract From the Canadian patent

The inventive method for producing paper paperboard and cardboard by removing , interfering substance-containing water from a paper pulp in the presence of polymers containing vinylamine units whose mean molecular mass Mw is equal or greater than one million. Said method consists in preparing at first a high-, density pulp, introducing a doses quantity at least of one type polymer which contains vinylamine units and whose mean molecular mass Mw is equal or greater than one million and a degree of hydrolysis ranges from 1 to 20 mol % in the high-density pulp, in diluting said high-density pulp by adding water until a low-density pulp is obtained and in dewatering said low-density pulp. …