Paper Technology International 2020 - Journal - Page 33

PAPERTECHNOLOGYINTERNATIONAL
New approaches to stickies control in tissue-making systems
Mark Christopher, Global Market Manager, Tissue - Buckman
INTRODUCTION:
Tissue makers using both virgin and recycled content to make their final products can suffer from highly sticky contaminants which
can adhere to the machine fabrics. The provenance of the contamination can be from glues used in converting and the cores of rolled
products which inadvertently make their way back into the broke system of the tissue mill or from the use of recycled furnish which contains
pressure sensitive adhesives, binding glues, packing tapes, etc. These stickies result in a final product that has visible holes, and when
these holes are large enough or numerous enough, production breaks on both the tissue machine and in converting begin to occur. At this
point the machine must be stopped and the forming fabrics cleaned via a solvent washing step that contributes significant downtime, as well
as environmental and operator health and safety impacts.
Over the years, chemical advances have provided several
different approaches to reducing or eliminating the negative impact
of stickies. Retention mechanisms, passivating chemistries,
retention chemistries and fabric coatings have all been used with
varying levels of success.
The most common application on tissue machines has been
the application of passivating coatings onto the forming fabrics.
These reduced the tendency for stickies to adhere to the forming
fabric and also greatly increased the ease with which they could be
washed off once it became necessary. One large drawback was that
large stickies still resulted in holes in the sheet, and the passivation
chemistry itself would build up over time, necessitating a shut to
strip it off.
More recently, two new technologies have been developed
and accepted by tissue makers that have greatly reduced the
negative impact of stickies.
The first is based on the patented use of enzymes and
passivating agents in a single product that can be applied into the
wet end. This approach mates the two most successful approaches
to reducing both the size and tack of sticky contaminants in the wet
end. The enzyme reacts with a large part of the most problematic
sticky materials which are butyl based, changing the surface
characteristics of the contaminants to a non-sticky and more
hydrophilic form. This allows the contaminants to go out with the
tissue sheet instead of building up on the machine.
The second is a wire passivation approach that is not
based on the cationic chemistries previously used. The passivating
chemistries are non-ionic and create a single molecular barrier
between the forming fabric and the incoming contaminant. These
non-ionic chemistries are not susceptible to building up over time
requiring their stripping on a shut down like previous generation
chemistries.
Hydrophobic Cationic Passivation.
Examples of tissue machine
wires treated in lab with the
differing approaches.
Hydrophilic Non-Ionic
Passivation.
Optimyze® Plus 727 Treated vs. Untreated Rejects
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