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Author:Saranpää, Emmi-Kaisa
Title:The effect of dry strength additive characteristics and wet-end conditions on paper and board strength properties
Kuivalujuuskemikaalien ominaisuuksien ja märänpään olosuhteiden vaikutus paperin ja kartongin lujuuteen
Publication type:Master's thesis
Publication year:2012
Pages:108 + [24]      Language:   eng
Department/School:Puunjalostustekniikan laitos
Main subject:Paperi- ja painatustekniikka   (Puu-21)
Supervisor:Paltakari, Jouni
Instructor:Hietaniemi, Matti ; Virtanen, Mikko
OEVS:
Electronic archive copy is available via Aalto Thesis Database.
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Location:P1 Ark Aalto  2191   | Archive
Keywords:dry strength additive
paper strength
board stiffness
PAM
kuivalujuuskemikaali
paperin lujuus
kartongin jäykkyys
Abstract (eng): The objective of this thesis was to study how characteristics of dry strength additives and wet-end conditions effect on paper and board strength properties.
Different furnishes and dry strength additives were employed within the study to increase filler content in paper and to enhance board stiffness.
Sequential addition of cationic chemical and APAM was employed within some of the test points.
Most of the tests were carried out with laboratory hand sheets, but samples from Moving Belt Fonner (MBF) were also used.
In addition to dry strength and stiffness measurements, the effect of dry strength additives on wet web tensile strength was examined with the case of fine paper hand sheets.
The adsorption of the polymers was followed by zeta potential measurements.
However, the change in the zeta potential did not predict the performance of the chemicals.

Molecular weight of the dry strength additive was found to have a biggest impact on tensile strength and SCT of test liner board hand sheets.
Branched chemical structure seemed to be optimal for board stiffness.
Both molecular weight and charge of the chemical had significant effect on strength properties of fine paper.
Chemicals with high molecular weight and low charge, e.g. starch, performed better when ash content of paper increased.
G-PAM increased the initial wet web strength of fine paper, as expected.

Molecular weight of the chemical had the biggest influence on tensile strength and internal bond of the SC paper sheets.
Amphoteric polymer with net anionic charge obtained the best internal bond results.
Chemicals with low molecular weight and low charge generate the best strength results for SC paper.
On the other hand, chemical with high molecular weight and low charge also benefit the strength.

Wet-end conditions have a major effect on the adsorption of polymers to fibres.
However, high conductivity did not have an impact on the performance of the cationic chemical.
Nevertheless, it disturbed the performance of APAM.
High conductivity with high charge of the furnish disturbed also the performance of the cationic additive.
However, the effect was negligible with cationic starch.
Abstract (fin): Tässä työssä tutkittiin miten erilaiset kuivalujuuskemikaalien ominaisuudet ja märänpään olosuhteet, kuten varaus ja johtokyky, vaikuttavat paperin ja kartongin lujuusominaisuuksiin.
Tutkimuksessa käytettiin erilaisia massoja ja kuivalujuuskemikaaleja nostamaan paperin täyteainepitoisuutta ja kartongin jäykkyyttä.
Joissakin koepisteissä käytettiin kationisen kemikaalin ja APAMin peräkkäistä lisäämistä.
Suurin osa testeistä tehtiin laboratoriokäsiarkeista, mutta testattavia arkkeja tehtiin myös Moving Belt Formerilla (MBF).
Kuivalujuus- ja jäykkyysmittausten lisäksi tutkittiin hienopaperimassalla märän rainan lujuutta.
Polymeerien adsorptiota seurattiin zeta-potentiaalimittauksin.
Zeta-potentiaalimuutos ei kuitenkaan kertonut kemikaalin toimintakyvystä.

Kuivalujuuskemikaalin molekyylipaino vaikutti eniten kartongin vetolujuuteen ja SCT:iin.
Haaroittunut kemikaalin rakenne näyttäisi olevan optimaalinen lisäämään kartongin jäykkyyttä.
Kemikaalin molekyylipaino ja varaus vaikuttivat merkittävästi hienopaperin lujuuteen.
Kemikaalit, joilla on suuri molekyylipaino ja matala varaus, kuten tärkkelys, tuottivat paremman lujuuden kun arkkien tuhkapitoisuus nousi.
Kuten oletettiin, G-PAM paransi hienopaperin märän rainan lujuutta.

Molekyylipaino vaikutti eniten veto- ja z-suuntaiseen lujuuteen.
Nettoanioninen amfoteerinen polymeeri tuotti parhaat Scott Bond-tulokset.
Parhaat lujuustulokset tuottivat kemikaalit, joilla on pieni molekyylipaino ja pieni varaus.
Toisaalta kemikaali, jolla on suuri molekyylipaino ja pieni varaus, paransi lujuutta.

Märänpään olosuhteet vaikuttavat merkittävästi polymeerien adsorboitumiseen kuituihin.
Massan korkea johtokyky ei kuitenkaan vaikuttanut kationisen kemikaalin suorituskykyyn, mutta häiritsi APAMin toimintaa merkittävästi.
Massan korkea varaus yhdessä korkean johtokyvyn kanssa vaikutti myös kationisen kemikaalin toimintaa.
Tärkkelyksen toimintakyky ei kuitenkaan häiriintynyt.
ED:2012-10-03
INSSI record number: 45330
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