Recycled Containerboard Compression Loss under Constant Atmospheric Humidity
Recycled containerboard loses up to 45% compression strength under constant 85% RH; specify ISO 2233 derated SCT metrics to prevent static stack collapse.
Starch Sizing
Hydrophilic Coating
Aqueous solutions of natural or modified polymers improve surface characteristics of cellulosic webs during papermaking or converting operations. Starch sizing penetrates the voids between fibres to modify the porosity and surface energy of the substrate. This process prevents excessive ink absorption during printing while increasing the internal bond strength of the sheet.
Such application prepares the surface to accept coatings or laminates that require a uniform base to maintain adhesion. Controlled deposition limits the migration of liquids into the body of the paper to ensure consistent visual results.
Surface Reinforcement
Increased mechanical strength follows the interaction between the starch molecules and the fibre network. Starch sizing creates a dense film that protects the paper structure from friction and mechanical stress during secondary processing like folding or gluing. Consistent moisture management during the drying phase prevents brittle fractures in the finished stock.
Proper loading levels remain essential for maintaining the balance between stiffness and flexibility. High concentrations result in excessive curl while insufficient pickup leads to poor pick resistance.
Conversion Performance
Print fidelity and adhesive uptake depend upon the uniformity of the modified surface layer across the entire web width. Converters adjust the starch sizing concentration to match the absorbency requirements of specific ink systems or gluing equipment. Consistent surface chemistry allows high speed lines to function without frequent pauses for equipment cleaning or substrate failure.
Uniformity across the surface remains the primary factor for achieving predictable runnability in commercial operations. Surface characteristics govern the final quality of the printed product under standard production conditions.