Spray application of strength chemicals
Somerkallio, Manu (2012)
Somerkallio, Manu
2012
Ympäristö- ja energiatekniikan koulutusohjelma
Luonnontieteiden ja ympäristötekniikan tiedekunta - Faculty of Science and Environmental Engineering
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Hyväksymispäivämäärä
2012-03-07
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tty-201203221085
https://urn.fi/URN:NBN:fi:tty-201203221085
Tiivistelmä
Spray application can bring various benefits when applying chemicals on wet and dry paper or board such as precise adjustability of dosage and good coverage. Special advantage of spray application is in creating a uniform coverage onto irregular surfaces. This thesis is divided into two major sections. In the literary section the basic aspects of spraying are covered. Some of the current applications in paper and board industry, with ongoing research projects included, are reviewed with benefits and problems arising from using spray technology. The aim of the study was to determine the possibilities and restrictions of application of strengthening chemicals via spraying. Based on the literary section, xyloglucan, a water soluble polysaccharide, was chosen as focus.
Xyloglucan (XG) was selected as the main focus as according to previous studies the strength properties, when sprayed onto paper web, increase significantly. Viscosity measurements were carried on a variety of solutions to characterize their behaviour when sprayed. Surface tension, according to general theories, factors in to good sprayability and was therefore included in the measurements – although the results from surface tension measurements were inconsistent. The power of ultrasound was taken in use to determine the effect of deflocculation and shorter molecules on the viscosity of the xyloglucan solution.
The main objective of the experimental part was to study how the sprayed solutions which varied in viscosity and composition affect strength properties. Goal was also to determine whether it is possible to increase the dry weight fraction of sprayed xyloglucan solutions on to the level where the amount of water in the solutions would not require too much energy to be evaporated at drying sections in paper or board machines.
Amount of borax in Tamarind Kernel Powder (TKP) and XG solutions was the most significant factor increasing the strength properties of the handsheets. Borax addition lowered viscosity to a certain point at lower dosages and increased the dry weight proportion of the solutions. XG with an addition of borax had the highest percentage of strain at break by far. Addition of only TKP or XG to the handsheet did not improve the sustained strain notably thus the runnability improving properties of borax seem to be excellent with conjunction of XG.
Introducing ultrasound to higher concentrations of TKP showed a vast decline in viscosity already at short processing times. It can be assumed that sonication reduces viscosity via deflocculation to a certain point. The strength properties were significantly worse when compared to unmodified TKP. The results show that spraying of XG or TKP with borax provides best total increase in almost all strength properties. Borax can also be used effectively to increase the dry weight fraction of the sprayed solution without increasing viscosity too much.
Xyloglucan (XG) was selected as the main focus as according to previous studies the strength properties, when sprayed onto paper web, increase significantly. Viscosity measurements were carried on a variety of solutions to characterize their behaviour when sprayed. Surface tension, according to general theories, factors in to good sprayability and was therefore included in the measurements – although the results from surface tension measurements were inconsistent. The power of ultrasound was taken in use to determine the effect of deflocculation and shorter molecules on the viscosity of the xyloglucan solution.
The main objective of the experimental part was to study how the sprayed solutions which varied in viscosity and composition affect strength properties. Goal was also to determine whether it is possible to increase the dry weight fraction of sprayed xyloglucan solutions on to the level where the amount of water in the solutions would not require too much energy to be evaporated at drying sections in paper or board machines.
Amount of borax in Tamarind Kernel Powder (TKP) and XG solutions was the most significant factor increasing the strength properties of the handsheets. Borax addition lowered viscosity to a certain point at lower dosages and increased the dry weight proportion of the solutions. XG with an addition of borax had the highest percentage of strain at break by far. Addition of only TKP or XG to the handsheet did not improve the sustained strain notably thus the runnability improving properties of borax seem to be excellent with conjunction of XG.
Introducing ultrasound to higher concentrations of TKP showed a vast decline in viscosity already at short processing times. It can be assumed that sonication reduces viscosity via deflocculation to a certain point. The strength properties were significantly worse when compared to unmodified TKP. The results show that spraying of XG or TKP with borax provides best total increase in almost all strength properties. Borax can also be used effectively to increase the dry weight fraction of the sprayed solution without increasing viscosity too much.