Dissolving pulps from enzyme treated kraft pulps for viscose application

The purpose of this study was to
illuminate enzymatic treatments as
process steps for the efficient conversion
of paper-grade pulps to dissolving pulps
in terms of process economics. The
challenge of pulp refinement comprises
the selective removal of hemicelluloses
and the precise adjustment of the pulp
viscosity, while maintaining the
reactivity of the pulp as required for
viscose application.
A commercial oxygen-delignified
E. globulus paper-grade kraft pulp was
subjected to xylanase (X) pre-treatment
combined with cold caustic extraction
(CCE) at reduced alkali concentration
and to endoglucanase (EG) posttreatment
after TCF-bleaching. The
xylanase pre-treated pulp showed
increased reactivity towards xanthation
and high viscose dope quality in terms
of particle content in comparison to the
pulp after cold caustic extraction at
elevated alkali concentration.
The dependence of cellulose chain
scission upon endoglucanase treatment
on certain pulp qualities was analyzed
in detail, and this allowed precise
viscosity reduction as well as reactivity
increase. The qualities of the spun fibers
from the differently treated pulps were
very similar to those viscose fibers from
commercial dissolving pulps.