Surface characterization of paper products by profilometry with a fractal dimension analysis

Abstract

A surface profilometry technique was used to characterize the surfaces of paper products. A stylus-contact type profilometer capable of simultaneously generating both surface roughness- and friction-profiles was used. As a stylus for the profilometer, a conical shape whose tip was rounded to have a 0.5 mm curvature radius was designed and successfully employed in both printing & writing (P&W) papers and hygiene papers such as bathroom tissues and kitchen towel. From the profiles, the mean absolute deviation (MAD) from the averages, i.e., R-MAD from the roughness average and F-MAD from the average coefficient of friction, were suggested as the new surface characterization parameters. To elucidate the surface roughness profiles by fractal dimension analysis, the variogram method was applied to get the fractal dimensions of the paper products. Generally, the value of the fractal dimension increased as the surface roughness increased. The surface profilometry technique with the fractal dimension analysis with the variogram method looks promising to gain additional insight on the surface characteristics of paper products.

Towards Expanding the Use of Paper Made from Recycled and Non-Woody Plants: Enhancing the Print Quality through the Application of Nano-Modified Offset Inks

“…Two different roughness parameters were measured: the parameter R a , which expresses the arithmetic mean deviation of the surface profile, and R z , which defines the vertical distance between the highest peak and deepest valley within the measuring length, according to ISO 21920-2:2021 [39]. Surface profilometry is widely used in the paper industry today as it enables the comparison of the results obtained with the various properties of the paper surface structures, which are important for the interactions within the papermaking and printing processes [40,41]. The size of the stylus was 2 µm and measuring force was 0.00075 N. Ten repetitions were made for each sample and the average values of the results were obtained.…”

“…Alternatively, additional fillers can be used in the papermaking process to improve the mechanical and surface properties of the paper [56]. It has also been shown that a low value of smoothness and a high value of roughness parameters affect the optical density of prints, the gloss, and the general paper properties [40].…”

“…Alternatively, additional fillers can be used in the papermaking process to improve the mechanical and surface properties of the paper [56]. It has also been shown that a low value of smoothness and a high value of roughness parameters affect the optical density of prints, the gloss, and the general paper properties [40]. However, when putting these results in the context of the print properties and quality (which is shown in the results presented in the continuation; results of the ink transfer, variation in ∆E, and print mottle), it can be concluded that the roughness/smoothness alone do not relate to the increased or decreased quality of the print.…”

Developing physical softness models for facial tissue products

“…A stylus-contact type surface tester has been used to determine both surface roughness and friction of bathroom tissue products (Spendel 1990;Ampulski et al 1991;Dwiggins et al 2003;Harper et al 2002;Yokura et al 2004;Beuther et al 2012;Park 2017;Ko et al 2018;Moon 2021;Lee et al 2023). ISO 12625-18 (2022) presents the determination of the friction of bathroom tissue products.…”

“…Among commercially available surface testers, only the Kawabata surface tester (Model: KES-SESRU, Kato Tech, Kyoto, Japan) can simultaneously measure both the surface roughness and friction from the same scan lines (Kato Tech 2018a,b). Recently, this tester has been successfully used for bathroom tissue products (Ko et al 2017a,b;2018;Lee et al 2017b;Park 2017;Moon 2021;Lee et al 2023). As such, the Kawabata surface tester was used to determine both the surface roughness and friction of facial tissue samples in this study.…”