The paper industry
continually has to
minimize its costs,
especially in today's
market with increasing energy and fibre prices. There is also
an ongoing need to improve product quality to satisfy market demands.
As a result, Roquette has recently developed a new range of products
in order to satisfy several demands. All sectors of the paper
industry are looking for 'green' products which enable them to
meet their own end-use requirements; ideally with a negative or
zero on-cost, lower chemical consumption and reduced rejects.
One of the objectives of this range development is to offer new
opportunities to achieve strength at the wet-end. We will describe
hereafter some advantages of these new biopolymers in tissue paper.
Rheology: All investigations were carried out with the AR 2000
rheometer from TA Instruments using concentric cylinders (14/15
mm). For viscoelastic determination, sinusoidal stress is variable
and the frequency is constant. For flow determination, shear rate
is variable.
| Samples |
Viscosity (mPa.s) |
Delta
20 °C (°) |
| Cook-up cationic starch |
- |
42 |
| Bio-polymer |
2000 |
83 |
Figure 1
Delta is the phase
displacement
angle. Figures between 45 and 90° give a viscous
behaviour (liquid
one) and figures under 45 an elastic behaviour (solid one). By
elastic, it is meant that there is a degree of structure, with
some hydrogen bonding. The lower the result, the greater the degree
of structure
When results are
high, there is a lower tendency to retrogradation. Pumping is
easier and molecules are more available to bind cellulose fibres.
The characteristics of this product are:
• 27% dry solid,
• 0.35-0.40 % nitrogen content (DS about 0,045).
• Neutral pH
• FDA & BfR compliant. |
Where And How To Apply Bio-Polymer?
On this simplified flow diagram (Figure 2) the possible addition
points are shown.
The product should
be diluted sufficiently before addition to allow a homogeneous
distribution onto the fibres.
The normal addition point for strength is into the thick-stock;
but improved first pass retention levels can be achieved if the
bio-polymer is added to the thin stock. If wet-strength resin
is being used, it needs to be added first.
INDUSTRIAL EXAMPLES:
You will see here after several industrial cases showing benefits
achieved with biopolymers. This new product primarily increases
the bond-strength of the sheet (Figure 3). This improved ability
to bind can be used in a number of ways to improve the final quality
and/or reduce manufacturing costs.
Example 1 (figure 4): Production of toilet tissue (16,5 g/m2),
machine speed: 1720 m/mn.
Figure 4 shows that with the introduction of bio-polymer, strength
increase more than
25%. After a while, even with the refining reduced from 47 kWh/t
to 25 kWh/t, the tensile strength was stable.
This decrease of the refining level gave a better drainage, and
so it was possible to speed up the machine to 1800 m/min, a productivity
improvement of 4.5%. The tensile strength remained 18% higher
than the reference.
Example 3 (figure 5): Kitchen towelling with 90% of cellulose
(long fibre) and 10% broke. Speed of the machine was 1450 m/min.
The WSR is introduced in thick stock, prior the level box. The
bio-polymer is introduced in the machine chest at 8.3 and 12.5
l/t.
The Zeta potential increased as we introduced our biopolymer,
meaning that the fixation is correct. Following the increase of
the dosage, the dry strengths are increased as well.
In that case, the wet strength increased after the second amount,
by 7%. The first amount (8 l/t) does not show an improvement,
but nor is there a negative effect.
Conclusion
These few examples show that it is possible to improve the strength
and runnability of a tissue machine, by the use of this new biopolymer.
Every machine is a unique process. Detailed investigation is required
to achieve the best balance between the possible advantages including:
speed improvement, paper specification, energy consumption and
others.
For further information, contact Régis Houze, Technologist
Market Development:
: Regis.houze@roquette.com
