Intelligent design of Yankee Coatings - Paper Technology International 2023 - Paper Technology International 2023 - Flipbook - Page 123

Intelligent design of Yankee Coatings - Paper Technology International 2023

PAPERTECHNOLOGYINTERNATIONAL Intelligent design of Yankee Coatings - Paper Technology International 2023
Intelligent design of Yankee Coatings
Gary S. Furman, Senior Corporate Scientist, Nalco Water, an Ecolab Company
Robert Melchiors, Senior Industry Technical Consultant, Nalco Water, an Ecolab Company
Marisa A. Rocha, Lead Chemist, Nalco Water, an Ecolab Company
INTRODUCTION:
All Yankee coatings must perform three critical tasks basic to their performance. They must (1) protect the Yankee surface, (2)
provide adequate adhesion to transfer the sheet onto the Yankee and to develop enhanced sheet properties at the creping blade, and (3)
be soft enough to allow blade tip penetration into the coating and below the sheet. The tissue machine type and grade being produced
greatly influence the ability of the coating to perform these functions. Thus, the coating package and the coating properties which develop
must be designed for the machine type and grade conditions in order to run the tissue machine efficiently and produce the desired tissue
quality. Nalco Water’s Yankee coating offerings including the TULIPTM and NAVIGATORTM adhesive product lines, when coupled with the
appropriate release and modifying agents, perform these tasks over the broad range of conditions employed in the industry today. This
review will highlight the coating needs and recommendations for each major machine type – conventional wet press (CWP), (creped)
through-air dried (TAD) and hybrid.
Background
Globally, the tissue and towel industry remains in a
dynamic phase with good growth, a reaffirmation by consumers of
the importance of these products to their personal hygiene, and
steady advances in production technology. The FisherSolve®
Next database shows a current global capacity for tissue and towel
products of over 55 million MT (air dry basis) with the regional
breakdown shown in Figure 1.
technologies have the capability to produce a structured sheet (prior
to creping) like TAD but without utilizing a TAD dryer. Global market
share by technology is dominated by CWP (91% of global tons) but
the TAD and hybrid machines have steadily increased market share
in North America, as shown in Figure 2, now accounting for 41% of
the NA tons.
Figure 2a: North America tissue and towel tonnage by machine
type. (FisherSolve® Next)
Figure 2b: North America growth of advanced machines.
FMT = Finished Metric Tons
55,360,289
Figure 1: Global capacity for tissue and towel products by
region. Total capacity = 55,360,289 finished metric tons (FisherSolve® Next).
Most analysts estimate the underlying growth rate of the
industry remains in the 3-4% range per year even though the COVID
19 pandemic has caused some recent fluctuations. Hoarding by
consumers in the early days of the pandemic caused a spike in
apparent usage (followed by a lull) and emphasized the critical
nature of tissue products.
The most important properties to consumer preference
remain softness, bulk, absorbency, and cleaning ability. Base paper
or parent roll manufacturing of tissue and towel can be categorized
into three different technologies: (1) conventional wet press or CWP,
(2) through-air dried or TAD and (3) hybrid machines. The hybrid
All current machine technologies emphasize improvements
in softness, bulk and absorbency while maintaining necessary
product strength in use, however, the TAD and hybrid technologies
excel at this, thus resulting in their popularity in N. America.
The TAD and hybrid technologies can also be referred to as
“advanced” tissue machines that produce “structured” sheets.
These technologies are increasingly used by tissue manufacturers
to produce premium and ultra-premium products for well-known
national brands as well as for the private label market. Reviews of
advanced machine technologies capable of producing structured
sheets have been presented by both Janda (reference 1) and
Reisinger (reference 2).
Creping remains the key unit operation in the tissue making
process having an inordinate influence on machine efficiency, and
at least in conventional tissue making technology, largely defining
the end-product attributes of the tissue. Creping is governed by the
complex interaction between various mechanical, operational, and
chemical factors, some of which are depicted in Figure 3. (overleaf)
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