Wet strength paper
Li, Qiuyue; Liu, Ke (2014)
Tampereen ammattikorkeakoulu
2014
All rights reserved
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:amk-2014060712127
https://urn.fi/URN:NBN:fi:amk-2014060712127
Tiivistelmä
In this final thesis, the subject is to study the wet strength of paper.
According to the topic, it was started by analyzing the dry strength of fiber networks, and contributes to paper web. Fiber held together mainly by two kinds of forces-van der Waals forces and hydrogen bonds, which give paper strength properties. But when paper gets re-wetted, the strength will lose a lot. In order to get wet strength, wet strength resins are needed to be added to pulp.
The wet strength resins which are most likely used are PAE, UF, MF, DAS and PEI. But if the wet strength of the paper grade is too high, there will be a big problem during re-pulping process. So, it is also essential to study how to degradate the paper with high wet strength.
After the study of theory work, experiment was also made to examine the wet strength of certain paper samples. Four types of paper are used in the laboratory works, they are kraft paper, label base paper, tape base paper and wall paper. Basic properties of paper were measured at first, then followed by dry tensile strength and wet tensile strength measurement. The whole experiment was based on ISO Standard.
As the results shows, the wet strength retention of label base paper is the highest. Tape base paper also has a high paper tensile strength and wet strength retention. Although the paper basis weight has a low value in both paper types, the protection and strong connection produced by wet strength resins are rather obvious high.
According to the topic, it was started by analyzing the dry strength of fiber networks, and contributes to paper web. Fiber held together mainly by two kinds of forces-van der Waals forces and hydrogen bonds, which give paper strength properties. But when paper gets re-wetted, the strength will lose a lot. In order to get wet strength, wet strength resins are needed to be added to pulp.
The wet strength resins which are most likely used are PAE, UF, MF, DAS and PEI. But if the wet strength of the paper grade is too high, there will be a big problem during re-pulping process. So, it is also essential to study how to degradate the paper with high wet strength.
After the study of theory work, experiment was also made to examine the wet strength of certain paper samples. Four types of paper are used in the laboratory works, they are kraft paper, label base paper, tape base paper and wall paper. Basic properties of paper were measured at first, then followed by dry tensile strength and wet tensile strength measurement. The whole experiment was based on ISO Standard.
As the results shows, the wet strength retention of label base paper is the highest. Tape base paper also has a high paper tensile strength and wet strength retention. Although the paper basis weight has a low value in both paper types, the protection and strong connection produced by wet strength resins are rather obvious high.