Investigation of paper dryer picking, web transfer and quality issues using a new web adhesion and drying simulator

Abstract

-Paper dryer surface contamination can influence the severity of fiber picking, result in increased adhesion of the paper web to the surface, and impact the severity of cockle (out-of-plane deformation), a paper quality issue. The Web Adhesion and Drying Simulator (WADS) is a unique apparatus designed for investigation of paper sticking and fiber picking. Using the WADS, it has been found that the work of separation and amount of picking depend on roll surface material, contamination and temperature, and on the composition, moisture content and temperature of the web, and contact time. The WADS was also found to be convenient for studying the effect of drying conditions on severity of cockle. Cockle was found to depend on ingoing sheet solids content, surface temperature and degree of heat transfer non-uniformity.

Influence of Particle Size, Applied Compression, and Substratum Material on Particle−Surface Adhesion Force Using the Centrifuge Technique

“…Generally, the adhesion force between contiguous bodies is due to van der Waals, electrostatic, and capillary forces, but the predominance of one or more of these forces depends on the local experimental conditions and the physical−chemical properties of the materials that are in contact. In theory, all these forces are affected by the format of the particle, surface roughness, particle size, relative air humidity, and contact pressure applied . Thus, total adhesion force is considered to be composed of the sum of these three forces…”

“…Adhesion force between contiguous bodies is influenced by the particle shape, the surface roughness, the particle size, the relative air humidity, and the application of contact pressure, as well as the physical−chemical properties of the material involved, such as density …”

“…In theory, all these forces are affected by the format of the particle, surface roughness, particle size, relative air humidity, and contact pressure applied. 8 Thus, total adhesion force is considered to be composed of the sum of these three forces. 9 The majority of particles 0.1 µm or larger carry some electrostatic charge, known as q, which induces an equal charge in the opposite direction on the substrate surface and results in an attractive electrostatic force.…”

“…23 The adhesion force between two surfaces also depends on both the material properties and the geometry of the surfaces. 8 Analytical models have been developed to predict the mechanical behavior of ideal sphere-sphere or sphere-plane contacts, notably the Johnson, Kendall, and Roberts (JKR) 24 and Derjaguin, Muller, and Toporov (DMT) 25 models. Both of these models consider elastically deformable solids in contact with either sphere-sphere or sphere-plane geometries.…”

Influence of removal time and particle size on the particle substrate adhesion force

“…All these forces are affected by the material, its shape, surface roughness, particle size, relative air humidity, duration of contact and initial speed of contact (Ahrens et al, 2005). Therefore, the total adhesion force (F adhesion ) is known as the sum of various forces (Stewart, 1986), as illustrated in Equation (1):…”