Barrier Paperboard Substrate Selection and Wet End Disintegration Yield Testing
Aqueous dispersion barrier boards outperform extruded polyolefins by delivering over 95 percent wet end fiber yield and avoiding heavy EPR penalties.
Wet End Disintegration
Mechanical Defibration
Hydro-mechanical shear breaks down dry pulp bales, broke, and recovered paper into discrete individual fibres suspended in water at the start of the papermaking process. Standard wet end disintegration separates entangled cellulose structures through spinning rotor blades within continuous or batch hydrapulpers without cutting or shortening primary fiber walls. The processing stage converts incoming furnish into pumpable stock suspensions carrying solid consistencies between three and eighteen percent.
Mechanical operations conclude once flakes dissolve entirely, passing through extraction grid plates to cleaning and refining loops.
Slurry Processing
Water temperature, chemical dosing, and mechanical dwell time control the breakdown rate inside the pulper tub. Virgin chemical wood pulps defiber rapidly under low shear forces, whereas wet-strength liquid packaging boards require extended processing times at temperatures reaching 60 degrees Celsius alongside acid or persulphate repulping aids. Rotor speed and tub baffle orientation generate a deep vortex that repeatedly pulls floating pulp sheets downward across rotor flighting bars.
Deflaking machines situated directly behind the main pulper tub introduce secondary high-shear rotor-stator gaps to disintegrate stubborn fiber bundles without degrading sheet freeness. Low-consistency pulpers permit continuous extraction through perforation holes measuring four to twelve millimetres, separating plastics, staples, and unpulped adhesives through secondary junk traps.
Fibre Fractionation
Incomplete breakdown leaves unseparated fibre flakes that trigger pinholes, low opacity spots, and tear breaks during high-speed paper machine runs. Screening efficiency depends heavily on thorough upstream defibration, because oversize bundles plug pressure screen baskets and increase reject mass flows unnecessarily. Recycled linerboard mills adjust pulping cycles to avoid over-disintegration of non-fibrous contaminants, keeping plastic films and hot-melt adhesives intact for easy removal by coarse screening equipment.
Retaining unbroken adhesive fragments prevents microscopic sticky particles from entering the paper machine white water loop. Fibre length preservation during this phase protects ultimate tensile and bursting properties across finished packaging grades.