Paper products have many uses, from drawing paper and toilet paper to packaging materials. Many new and multifunctional paper products are being developed, such as biologically active paper, printed electronics, and the utilization of nanocellulose. Paper is a recyclable and renewable material, which facilitates its application in many other fields.

[Surface Treatment and Coating - Paper and Packaging Paper]

In the packaging industry, adhesion and wetting play critical roles in many processes. Packaging materials typically include various layers of different materials to meet all requirements for protecting and improving the products inside the packaging.

Optimize the adhesion of coatings on paper

Due to its relatively low cost and renewability, paper is often used as a packaging material. The barrier properties of paper are usually insufficient, so different polymer coatings are used to produce laminated materials. To ensure good mechanical properties of laminated boards, it is necessary to optimize the adhesion between polymers and paper. Wettability and surface roughness play a crucial role in adhesion and can be studied by combining contact angle and surface roughness measurements.

Before the final use of paper products, wood fibers are usually mechanically or chemically modified. The improvement of new fibers, such as utilizing nanotechnology for fiber functionalization, is also a hot topic of research. The performance of a single fiber can be studied by combining a tensiometer or optical tensiometer with a skin lift distributor.

The influence of roughness on the wettability of paper

Due to its fibrous structure, the surface of paper and cardboard is almost rough. Because it amplifies the wetting effect of surface chemicals, this roughness can affect wetting properties. In addition, different types of plasma and flame treatments used to improve printing quality can affect surface chemistry and surface roughness, so evaluating the effect of roughness on contact angle is very important.

The following example shows the effect of roughness on contact angle. Measure roughness and water contact angle at three different sample locations. Especially for hydrophilic base paper, the measured contact angle shows significant changes in the contact angle reading. After removing the influence of roughness by calculating the contact angle corrected for roughness, the contact angles become closer to each other. The difference in contact angle for roughness correction is due to the surface chemical properties of the surface. Combining contact angle and surface roughness measurement makes it possible to evaluate how roughness affects contact angle.

[Surface roughness and wettability download]

Evaluating Printing Quality through Wettability Study

Another aspect of packaging is its visual appearance. The purpose of printing on packaging is to sell internal products. The printing quality is affected by the wetting and absorbing properties of ink, as well as its spreading onto porous paper. Printing on low surface energy polymer coatings may be challenging. Optical tensiometers can be used to measure the contact angle to evaluate the influence of internal and surface sizing on the paper's absorption performance. If necessary, high-speed cameras can study very fast absorption phenomena.

Inkjet printing technology is increasingly being used for home and office printing, and has also become common in industrial printing, packaging industries, and functional printing applications. The combination of optical tensiometer and skin lift distributor can be used to demonstrate inkjet printability, especially its interaction with paper.

Study the absorption properties of coatings and ink pigments using powder wetting method with mechanical tension meter.

Evaluate the plasma treatment effect on extruded coated paper using contact angle measurement.

When printing non absorbent and low surface energy plastic surfaces, the adhesion between ink and substrate is challenging. The surface free energy of the substrate should be higher than that of the ink. To ensure good printing quality, surface treatment methods such as plasma and flame treatment should be used before printing to increase the surface free energy of the coated substrate.

Application Summary: Evaluation of Surface Treatment in the Packaging Industry

Tension measurement in inkjet printing applications

Inkjet printing is a versatile technology widely used in small home and office printing, high-speed industrial printing, and more innovative functional printing applications. Due to the crucial interaction between ink and substrate in defining inkjet printing quality, tension measurement method is widely used in this field.

The adhesion between ink and substrate can be estimated by comparing the surface tension of ink and the surface energy of substrate. Using contact angle measurement to study the absorption and spreading of droplets. The leather upgrade dispenser option of Theta optical tensiometer generates droplets of the same size as those in the real inkjet process through the use of piezoelectric driving technology.

Application Summary: Tension Measurement in Inkjet Printing

Related blog articles

The Effect of Surface Roughness on the Wettability of Paper and Paperboard

6 Reasons for Wettability Measurement in Paper and Paperboard Quality Control

Wetting Analysis of Inkjet Printing