Recycled Contaminant
Tacky contaminants originating from adhesives, hot-melts, and coating binders pose a major operational challenge during the recycling of recovered paper and board. These substances, collectively termed stickies, are insoluble in water and tend to agglomerate during the repulping process. They exist in both macro and micro forms, depending on their particle size and their ability to pass through fine slotted screens.
Their presence in the pulp slurry degrades the quality of the recycled board and can lead to structural defects in the finished sheet.
Operational Disturbance
Deposition of these tacky particles onto the moving parts of the paper machine causes frequent production delays. When stickies adhere to forming fabrics, press felts, or drying cylinders, they create holes in the paper web and lead to frequent sheet breaks. These interruptions require manual cleaning of the machine surfaces with specialized solvents, reducing overall mill efficiency.
In addition, the contaminants can remain dormant in the finished board, causing sheets to stick together during converting.
Removal Method
Mills utilize a combination of mechanical screening and chemical dispersion to control these residues. Fine slotted screens are deployed early in the stock preparation line to remove the larger particles. Chemical additives are then introduced to pacify the surfaces of the remaining micro-particles.
