Global paper and paperboard production is about 390 million tons annually. The consumption is still growing especially in Asia and China, which accounts for 40% of the global consumption, whereas Europe and North America accounts for about one quarter each. The paper products have several applications for example as graphic paper, tissue product and packaging material. In addition, many novel application possibilities are under research and development, such as bioactive paper, printed electronics and utilization of nanocellulose. Paper is a recyclable and renewable material, which favors its use in many fields. Surface and interface science play a significant role in many papermaking and converting processes. Therefore, tensiometers
have been widely utilized in this industrial sector.
Application examples include:
• Adhesion properties are crucial especially in printing, coating and packaging applications, where adhesion for example between paper and ink needs to be optimized. Adhesion and wettability properties between solid substrate and liquid can be estimated by determining surface free energy of solid and surface tension of liquid with optical and force tensiometers.
• Wettability, absorption and spreading of various fluids, such as inks and coatings, into porous paper are important phenomena in paper and packaging industry. These properties can be controlled by different coatings and surface treatments. For example influence of internal and surface sizing on paper absorption properties can be evaluated by contact angle measurements with optical tensiometer. High speed camera allows studying very fast absorption phenomena, if needed.
• Absorption properties of coating and ink pigments can be studied by using the powder wettability method of force tensiometers.
• Inkjet printing technology is expanding printing method used in home and office printing, but it has also become common in the industrial printing, packaging industry and functional printing applications. Optical tensiometer combined with picoliter dispenser can be utilized to demonstrate the inkjet printability, especially the ink-paper interactions.
• Wood-fibers are typically modified either mechanically or chemically before the final use in paper products. Novel fiber modifications, such as utilizing nanotechnology for fiber functionalization, are also topic of interest in research. Single fiber properties can be studied by force tensiometer or by using optical tensiometer combined with picoliter dispenser.
• Bubble tensiometer can be used to define dynamic surface tension, which provides essential information for many paper industry processes that are dynamic, such as deinking, coating and printing.