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PAPERMAKING CHEMISTRY ASPECTS OF ENVIRONMENTALLY FRIENDLY ECF AND TCF PULPS

Objective



Chemical additives are more and more important for an effective manufacture of
high quality paper products. The background of this project is the importance of
chemical additives (paper chemicals) in paper manufacture and the rapidly
increasing use of new types of non-chlorine bleached pulps, i.e. elementary
chlorine-free (ECF) and totally chlorine-free (TCF) pulps.

Paper chemicals are used in the paper production as process chemicals or as
functional chemicals. A process chemical is e.g. a charged polymer used to
flocculate fine material. A functional chemical is e.g. added to increase the
strength of the paper. The new pulps can influence the use of paper chemicals in
at least two ways. The interaction between the fibres and the paper chemicals can
be influenced which will influence the effect of the paper chemicals in the produced
sheet. This will create a new, more difficult, situation for the use of paper
chemicals. The project will give guidelines how to optimize the application of
chemical additive in papermaking from ECF and TCF pulps and thereby reduce the
papermaking costs.

The type and the amount of substances that is dissolved from the pulps will
depend on e.g. the chemical environment and whether the pulp has been dried or
not. It is therefore important to investigate the extent of carry-over of substances
from the pulp mill to the paper mill. We will perform pulp mill measurements to
investigate the carry-over. The effect on wet end additives of new ECF and TCF
pulps and of dissolved and colloidal substances carried by these pulps will be
clarified.

Another aspect is that when paper chemicals, such as retention aids and sizing
agents, are used, paper chemicals transfer between components in the furnish and
in the white water system. This can influence the performance of paper chemicals.
It is known that the amount of transfer of paper chemicals depends on the
chemical environment, i.e. the ionic strength. It is not known to what degree the
transfer is influenced by dissolved and colloidal substances originating from pulps.

The papermaking system is highly dynamic and computer simulations of the
process circuits in a paper mill have gained increased attention. An increased
knowledge in the process dynamics of both the transfer of paper chemicals and the
dissolved and colloidal substances is highly needed. Pilot paper machine
experiments will make it possible to make controlled experiments of the influence
of dissolved and colloidal substances on the effect of paper chemicals.

A deeper knowledge of the fundamental paper chemistry aspects of using ECF and
TCF pulps combined with pilot and mill trials will give great possibilities to control
the papermaking process better in order to improve the paper quality. The
environmental relevance is naturally high because a better process knowledge leads
to reduced effluents.

Coordinator

SWEDISH PULP AND PAPER RESEARCH INSTITUTE
Address
Drottning Kristinas Väg, 61 - P.o. Box 5604
114 86 Stockholm
Sweden

Participants (3)

CENTRE TECHNIQUE DE L'INDUSTRIE DES PAPIERS, CARTONS ET CELLULOSES
France
Address
Domaine Universitaire - B.p. 251
38044 Grenoble Cedex 9
OY KESKUSLABORATORIO
Finland
Address
P.o. Box 70
02151 Espoo
PAPIERTECHNISCHE STIFTUNG
Germany
Address
Pirnaer Straße, 37
01809 Heidenau