Method of producing high dry strength paper and cardboard and paper and cardboard thus obtained
US7972478B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Jan 11, 2006 |
| Grant date | Jul 5, 2011 |
| Priority date | — |
| Expiry date | Nov 14, 2027 |
Classification
- Technology area (CPC D)Textiles; Paper
- CPC primaryD21H21/18
- WIPO fieldMacromolecular chemistry, polymers
- WIPO sectorChemistry
Abstract
In a method of producing a sheet of paper and/or cardboard and similar products, prior to the formation of the sheet from a fibrous suspension, at least two dry strength agents are added to the suspension either separately in any order or mixed together and at one or more injection points, namely: a first agent corresponding to a product for Hofmann degradation in solution on a base (co)polymer comprising at least one non-ionic monomer which is selected from the group containing acrylamide and/or methacrylamide, N,N dimethylacrlamide and/or acrylonitrile; and a second agent corresponding to a (co)polymer having an anionic charge density greater than 0.1 meq/g. The Hofmann degradation product comprises an organic polymer produced at a concentration greater than 3.5% by weight, and preferably greater than 4.5% and the first and second agents are each introduced into the pulp suspension at a concentration of between 0.01 and 2% by weight of active polymer material in relation to the dry weight of the pulp suspension.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.