Alkaline Treatment
Industrial cleaning process that uses a high-pH solution to remove contaminants from recycled material streams. During the reprocessing of post-consumer plastic and paper packaging, a caustic wash dissolves adhesives, inks, and organic residues. This treatment prepares the recovered material for pelletizing or repulping by isolating the clean polymer or fibre from surface coatings.
Chemical Dissolution
Sodium hydroxide solutions, typically maintained at elevated temperatures, break down the acrylic and vinyl-based binders that hold inks to the surface of the substrate. This chemical action hydrolyzes the polymer chains, which renders them soluble in water and allows them to be rinsed away. In addition to ink removal, the caustic wash neutralizes acidic compounds and sanitizes the material, which reduces both odour and microbial load in the recycled pulp.
The concentration of the alkaline agent must be carefully regulated to prevent chemical degradation of the underlying cellulose fibres.
Systemic Resistance
Certain polymer coatings and specialty barrier layers resist the action of hot alkaline solutions, which requires the addition of specialized wetting agents. Inadequate washing leads to adhesive carryover, which causes blockages in downstream extrusion screens and filter assemblies. Efficient washing guarantees that the recovered raw materials meet purity standards for reuse.
