3.2 Sticky Removal
The appearance of so-called stickies is described for instance by Hubbe [53]. These
are most often the result of synthetic polymers used in pressure-sensitive label
adhesives. The full characterization of stickies is not easy to assess since there are
many different types of stickies that have to be considered [54].
The existence of primary stickies (from raw materials) and secondary stickies,
which were built by the interaction in such systems, has been described, together
with many different characterization methods(including mechanical methods) for
quantifying the efficiency of different fixing agents [55, 56]. In addition, physicochemical methods such as measuring the cationic demand, the zeta-potential, or the
turbidity of wastewater have been applied.
Unfortunately, none of the sticky test methods investigated was found to be
universally applicable, i.e., suitable for all types of stickies. Therefore, the most
suitable method must be chosen for each particular case and problem area [56].
Previous articles or reviews (such as [53, 57]) have considered the origin, the
nature, as well as the removal of DCS.
Among the organic polymers used in the paper industry to combat deposit
problems are polymers with a huge ranges of molecular mass, charge, and hydrophilic versus sparingly soluble character. The effects of these polymers are greatly
dependent on how these materials interact with the suspension or with surfaces [53].
Important classes of polymers are cationic polymers with very high mass, e.g.,
acrylamide polymers (well known as retention aids) or high charge cationic
polymers [58, 59]. Hydrophilic polymers of intermediate mass are applied as well
as PEL with partially hydrophobic character or surfactants. The adsorption tendency
of PEL onto tacky materials can be increased by derivatization with hydrophobic
substituent groups. Various copolymers of cationic, hydrophilic monomers, and
hydrophobic monomers have shown promise as detackifying agents for resinous
material [60, 61].
According to Meixner et al. [62], tailor-made cationic polymers are very effective
for fixing interfering substances because they reduce the tendency of adhesive,
hydrophobic substances to agglomerate and slow down the rate at which secondary
stickies are formed. Using different types of models (hydrophilic or hydrophobic)
and fixing agents, Meixner et al. were able to demonstrate that, for efficient sticky
removal, not only is the cationic charge necessary but also the hydrophobicity.
Whether (or not) a certain polymer is effective depends on the type of detrimental
substances.
3.3 Natural Polymers for Sticky Removal
A few articles describe the application of starch, modified starch, or other carbohydrate polymers as flocculant for sticky removal [63–66]. The role of charge on the
destabilization of microstickies was investigated by Huo by comparing the strong PC
42
G. Petzold and S. Schwarz
The appearance of so-called stickies is described for instance by Hubbe [53]. These
are most often the result of synthetic polymers used in pressure-sensitive label
adhesives. The full characterization of stickies is not easy to assess since there are
many different types of stickies that have to be considered [54].
The existence of primary stickies (from raw materials) and secondary stickies,
which were built by the interaction in such systems, has been described, together
with many different characterization methods(including mechanical methods) for
quantifying the efficiency of different fixing agents [55, 56]. In addition, physicochemical methods such as measuring the cationic demand, the zeta-potential, or the
turbidity of wastewater have been applied.
Unfortunately, none of the sticky test methods investigated was found to be
universally applicable, i.e., suitable for all types of stickies. Therefore, the most
suitable method must be chosen for each particular case and problem area [56].
Previous articles or reviews (such as [53, 57]) have considered the origin, the
nature, as well as the removal of DCS.
Among the organic polymers used in the paper industry to combat deposit
problems are polymers with a huge ranges of molecular mass, charge, and hydrophilic versus sparingly soluble character. The effects of these polymers are greatly
dependent on how these materials interact with the suspension or with surfaces [53].
Important classes of polymers are cationic polymers with very high mass, e.g.,
acrylamide polymers (well known as retention aids) or high charge cationic
polymers [58, 59]. Hydrophilic polymers of intermediate mass are applied as well
as PEL with partially hydrophobic character or surfactants. The adsorption tendency
of PEL onto tacky materials can be increased by derivatization with hydrophobic
substituent groups. Various copolymers of cationic, hydrophilic monomers, and
hydrophobic monomers have shown promise as detackifying agents for resinous
material [60, 61].
According to Meixner et al. [62], tailor-made cationic polymers are very effective
for fixing interfering substances because they reduce the tendency of adhesive,
hydrophobic substances to agglomerate and slow down the rate at which secondary
stickies are formed. Using different types of models (hydrophilic or hydrophobic)
and fixing agents, Meixner et al. were able to demonstrate that, for efficient sticky
removal, not only is the cationic charge necessary but also the hydrophobicity.
Whether (or not) a certain polymer is effective depends on the type of detrimental
substances.
3.3 Natural Polymers for Sticky Removal
A few articles describe the application of starch, modified starch, or other carbohydrate polymers as flocculant for sticky removal [63–66]. The role of charge on the
destabilization of microstickies was investigated by Huo by comparing the strong PC
42
G. Petzold and S. Schwarz