Richard Gagnon of DuPont Soy Polymers, Joel
Kendrick and Jan Walter of Western Michigan
University, and Rajan Iyer, Leslie McLain and Roger
Wygant of IMERYS, has developed a new approach
using pigmented sizing to improve sheet stiffness.
They have found that, when used as part of the
pigmenting system, platy (high aspect ratio) kaolin
can provide significant improvements in sheet
stiffness, when compared to the more traditional
blocky (low aspect ratio) GCC pigments. They also
found improvements in sizing holdout and Optical
Brightening Aid (OBA) efficiency.
to obtain the very bright shades of paper we, the
consumer, prefer to buy. They are extensively used
in free sheet papers typically added at the start of
the papermaking process and as part of the surface
size. Adding pigment to the sizing solution will
improve OBA efficiency by keeping the sizing
solution near the surface of the paper. This is
critical to achieving today's highest brightness
targets with high optical brightener dosages.
carbonates, they still enhance this effect. This is
demonstrated in figure 1.
of platy kaolin in figure 2. where stiffness is
assessed by measuring bending resistance
paper producer should be able to reduce total fibre
weight by between 1% and 8%, thereby reducing
the energy demands in the dryer section. This
would likely result in either an increase in
productivity, or a reduction in steam usage.
and possibly additional filler, to achieve the
same weight of paper, papermakers can achieve
a significant degree of cost saving.
overall fibre demand, combined with improved
size press chemical efficiency, reduced energy
requirement for drying and possibly increased
production rate.
uncoated free sheet would increase the amount
of pulp available to the market, thus gaining
extra revenue.