Paper360 - January/February 2018 - 28
* The extremely high surface area due to over
20 trillion particles per gram of Cartaspers
PLH liquid enables a significant passivation
effect with only 1/8th to 1/10th of the volume
of dry talc.
* The hydrophilic molecule is uniquely engineered with a high Tg hydrophobic polymer
that has an extremely strong attraction and
affinity for pitch.
* Cartaspers PLH liquid is much smaller than
pitch and covers the particle like a shell,
eliminating the tackiness of the pitch. It also
creates a protective layer on existing pitch
deposits in the system and prevents further
agglomeration of new particles to the deposit.
It will not cause existing organic and pitch
deposits to break loose.
* The product is non-abrasive, and will not
decrease the life of paper machine fabrics.
* The low addition rate of Cartaspers PLH
liquid is cost effective, with it being applied
at 1/8th to 1/10th (as received) that of talc
on a dry basis. The proper dosage can be
determined with laboratory work in the mill.
* Cartaspers PLH liquid complies with BfR recommendations XIV and XXXVI and is compliant with the Code of Federal Regulations
(FDA) Chapter 21. Part 176.170 and 176.180.
In conclusion, Cartaspers PLH liquid presents several advantages over other passivation
methods, improving pulp mill efficiency, contributing to product quality, and providing a
safer work environment for employees. As usage
levels are low, it can provide an application cost
benefit as well.
Marcelo Ribeiro is global head of product management for process chemicals, Archroma. He
can be reached at marcelo.ribeiro@archroma.
com. To learn more, contact your Archroma
representative, or visit www.archroma.com.
How it Works
Cartaspers PLH liquid controls pitch by acting as a liquid
synthetic adsorbent, which is
differentiated with many advantages over conventional talc and
dispersant treatments. Cartaspers
PLH liquid is delivered as a waterbased emulsion, requiring no
makedown or dry handling. Fig. 4: Component parts of Cartaspers PLH liquid.
When dried, Cartaspers PLH is
non-film forming and has no tack due to its extremely high Tg. The active mechanism of the product occurs when the Cartaspers PLH particles associate with
hydrophobic pitch particles and raise the Tg of the pitch, reducing or eliminating its tackiness. The pitch is passivated, thus preventing the formation of pitch
deposits. Because Cartaspers PLH liquid can be added at the brown stock washers,
the passivated compound is removed from the process.
Figure 4 illustrates the main components of Cartaspers PLH liquid:
* Hydrophobic chain polymer is attracted to pitch particles. The high Tg of
polymer shell increases the point at which the pitch particles soften, thus reducing coalescence.
* Hydrophilic groups maintain the bound pitch and polymer in a colloidal
particle that is stable in the liquid phase, preventing agglomeration.
Cartaspers PLH liquid has strong affinity for nonpolar (hydrophobic) surfaces,
i.e. pitch or stickies particles. Once adsorbed, the particles become hydrophilic in
nature, and slightly anionic, promoting dispersion and preventing agglomeration.
The high Tg of the polymer shell increases the softening point of the particles,
This principle of passivation with a Cartaspers PLH liquid is similar to the use
of talc, but with critical differences. Cartaspers PLH liquid particles are much
smaller than talc, with more than 20 trillion particles per gram of dry product,
delivering an extremely high surface area for the typical addition level of 1/8th
to 1/10th the dose of talc. The extremely small particle size and huge surface
area per kilogram of Cartaspers PLH liquid versus talc means greater efficiency.
Colloidal pitch particles are completely covered by Cartaspers PLH liquid, preventing any agglomeration.
Fig. 2: Graph of colloidal pitch counts-Digester and 1st DD Washer.
Fig. 3: Graph of colloidal pitch counts-Post O2, Ep and D stages.