THE INFLUENCE OF WASTE PAPER ON THE LUMINANCE (Y-VALUE) OF PRINTING PAPER

The waste paper recycling quota of Germany climbed to 54% in 1993. This is a very high level when compared with other countries worldwide. The government of Germany is interested to increase this figure further substantially within the next years. The increase of the waste paper consumption in Germany is bound to an increase in the usage of recycled fibre in the manufacturing of higher quality graphical paper. The only waste paper quality available in necessary quantities is mixed white household waste, of which 50-60% is newsprint. The usage of this waste paper quality requires upcycling of the deinked pulp. INGEDE, the international deinking research organization has sponsored a research project in which the quality of deinked pulps was studied in a laboratory. The pulps were prepared by combining industrially used waste paper pulping techniques in different sequences. The results presented in this paper show that the efforts will be successful provided the quality of white waste paper can be improved. Practical results from existing industrial deinking plants equipped with the most modern techniques support the laboratory results.