HI-CAT®
Starch in the paper industry
For more than twenty years, Roquette has been supplying wet
end, size press and coating starches for the paper industry.
Roquette's particular speciality is the production and application
of wet end cationic starches.
Cellulose fibres and filler particles normally have a negative
polarity when in a water suspension, giving them a natural
affinity for cationic starch. By the process of etherification,
starch molecules can be given a positive charge, i.e by cationiazed.
Roquette sells a very wide range of cationic starches under
its trade mark of HI-CAT®.
Use of HI-CAT® enables better fibre retention
to be obtained as well as improving paper strength properties.
The large number of HI-CAT®grades which are readily
available means that the best product can be selected for
each specific application.
Improvement of fibre and filler retention
All papermaking materials suspended in water possess some
degree of surface charge. For cellulose fibres this charge
(zeta potential) varies between-20mV and-30mV depending on
the type of fibre, its chemical treatment and degree of refining.
The zeta potential of a furnish is also influenced by the
filler used, for example a suspension of china clay particles
in water as a zeta potential of between - 25mV and - 30mV
( the exact value depending on the particle size distribution).
Because like charges repel each other , the zeta potential
has a strong influence on the flocculation and settling characteristics
of a furnish. This repulsive force can be neutralized if positively
charged groups are attached to the surface of the particles.
HI-CAT® cationic starch operates essentially in
this manner.
HI-CAT® molecules attract negatively charged particles
to themselves to the long cellulose fibres. In the laboratory
it is possible to fix up to 4% HI-CAT® onto papermaking
fibres. At the lower addition levels which are normally used,
100% HI-CAT® retention is obtained.
Paper strength improvement
HI-CAT®, being completely retained in the sheet,
substantially improves the mechanical properties of the finished
paper. The high retention of HI-CAT® cationic starch
improves both fibre/fibre and fibre/filler bonding. The fines
distribution in the sheet is far more uniform because the
fines are fixed to the fibres during sheet formation. The
resulting paper is less two sided ,stronger and the printing
properties are significantly improved. By using HI-CAT®,
a paper with superior strength properties can be produced
in particular HI-CAT® :
- Increases breaking length
- Increases bursting strength
- Increases internal bond strength (Scott Bond)
- Improves printability (I.G.T., Dennison)
Preparing HI-CAT® solution
in the mill
HI-CAT® cationic starches are available
in either pregelatinised cold water soluble form (HI-CAT®
C.W.S) or as a cook-up product. HI-CAT® C.W.S can
be added directly to the pulper or it can be pre-dissolved
for addition closer to the paper machine. A tank equipped
with a good agitator is required for the preparation of solutions
of HI-CAT® C.W.S .Normally, a 5% solution is prepared
and, to ensure a complete solubilisation, 20-30 minutes must
be allowed before sending this solution to the paper
machine . Cook-up cationic starches are supplied in the form
of a white powder which is insoluble in cold water. This type
of cationic starch must be cooked in hot water before it can
be used. The cooking operation is extremely important because
the beneficial effects of the cationic starch are not attainable
in less it is completely dissolved.
The use of HI-CAT® permits either the quality of
the final product to be improved or a product of the same
standard to be produced at a lower cost to the mill.
By increasing the filler content of a paper it is also possible
to improve the drying efficiency of the paper machine , leading
to increasing productivity.
HI-CAT cationic starches are used to manufacture a wide variety
of papers. The choice of which particular grade of HI-CAT®
should be used is determined by the physicochemical conditions
encountered in the paper machine in question.
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ROQUETTE
is the world’s largest producer of polyols, sorbitol, maltitol, mannitol,
xylitol.
ROQUETTE
is the world’s largest producer of polyols, sorbitol, maltitol, mannitol,
xylitol.
ROQUETTE
: world’s leader of polyols - an extensive range of high-quality starch
derivatives for the whole industry
ROQUETTE
, leader mondial des polyols - une gamme étendue de dérivés d’amidon de
haute qualité pour toute l’industrie
ROQUETTE
is the world’s largest producer of polyols, sorbitol, maltitol, mannitol,
xylitol. One of Europe’s most advanced suppliers of native and modified
starches, sweeteners including maltodextrins for the food, pharmaceuticals
cosmetics, biochemistry, paper, corrugated board and animal nutrition industries.
Polyols,
maltitol, sorbitol, xylitol, mannitol, hydrogenated glucose syrups,sugar
free sweeteners
