Deinkability Score Impact on EPR Eco Modulation Fees in Recycled Stock
Deinkability scores under INGEDE Method 11 directly determine EPR eco-modulation fee surcharges or discounts on printed recycled paperboard packaging.
Alkali Repulping
Fiber Dissociation
Hydromechanical fibre liberation processes rely on elevated pH levels to swell cellulose cell walls and weaken intermolecular bonds in recovered paper stock. Standard alkali repulping introduces sodium hydroxide or sodium carbonate into the hydrapulper at temperatures ranging between forty and sixty degrees Celsius. This chemical action relaxes hydrogen bonding within the fibre matrix, allowing mechanical rotors to defibre recovered paperboards without excessive mechanical refining energy.
Process Chemistry
Solubilization of alkaline-soluble resins occurs rapidly when alkaline chemicals saponify vegetable oils and crosslinked binders found in printing inks. Chemical additives in alkali repulping raise the liquor pH to roughly nine to eleven, causing fatty acid binders to form soluble soaps that disperse ink particles away from the cellulose fibres. Sodium silicate is frequently added alongside caustic soda to buffer pH fluctuations and prevent detached ink particles from redepositing onto cleaned fibre surfaces.
Peroxide bleaching agents are sometimes introduced in the same pulping stage to mitigate alkali darkening on mechanical pulps.
Yield Boundary
Chemical consumption increases exponentially when processing unbleached kraft or heavily sized paper grades that consume hydroxyl ions during wet processing. Excessive alkalinity degrades hemicellulose chains, reducing overall yield and increasing chemical oxygen demand in effluent streams.