Polymer Barrier Coatings and Pulpability Test Standards
Polymer barrier paperboard compliance requires passing 0.15mm laboratory slot screening with under 15 percent reject mass to prevent EPR fee penalties.
Slot Width 0.15mm
Screen Aperture
Precision physical aperture size utilized in laboratory slotted screens isolates fine contaminants and unpulped fiber bundles from pulp suspensions. Selecting a slot width 0.15mm sets a strict mechanical barrier that captures micro-stickies and small plastic flakes while letting single cellulose fibers pass. Testing laboratories utilize pressurized or vibrating screening devices equipped with this plate geometry to evaluate pulp cleanliness.
Standardized slot dimensions ensure consistent contaminant separation across different laboratory screening units.
Particle Separation
Mechanical screening relies on precise hydraulic flow dynamics to draw individualized fibers through narrow apertures while rejecting rigid or tacky particles. Operating with a slot width 0.15mm provides the high sensitivity required for fine repulpability and stickies testing on recycled packaging stocks. Screen plate blinding occurs when flexible film fragments or tacky adhesives plug screen slots, reducing flow capacity and altering separation efficiency.
Constant pressure differential and mechanical pulse cleaning maintain consistent flow rates during testing. Collected screen reject fractions serve as key quality indicators for secondary pulp stock.
Filtration Limit
Aperture dimensions establish the boundary between acceptable fiber stock and rejected debris. Larger slot sizes fail to capture small sticky contaminants, while smaller apertures cause excessive fiber loss and screen blinding. Testing terminates when slot plugging prevents fluid passage or skews mass balance calculations.
Precise slot dimensions guarantee reproducible pulp purity measurements.