Influence of Deinked Pulp on Paper Colour and its Susceptibility to Ageing
Research and development
Author:
- Drzewińska Ewa
Institute of Papermaking and Printing, Technical University of Lodz, Łódź, Poland
 Full text | Abstract: The dyeability of chemical pulp and deinked pulp (DIP) as well as a mixture of these grades with cationic direct dyes were investigated. It was found that the paper obtained contains significant quantities of fluorescent whitening agents (FWA), which were added to white printings to increase their brightness. When using FWA, there are problems obtaining the colour of dyed paper required. The fluorescence of a whitening agent fades away after exposure to light. The faster fading of paper containing recycled fibres reflects lower penetration of a dye into fibres in comparison to primary fibres. The use of deinked pulp in the manufacture of colourfull papers is expected to grow. For this reason paper mills will be forced to use expensive bleaching technologies to remove FWA from deinked pulp. This indicates that the need to obtain a very high level of brightness in printing papers with FWA is ungrounded. |
Tags: chemical pulp, deinked pulp, DIP, colour, dyeing, direct dyes.