Dispersion Barrier Performance under Crease Compression in Folding Boxboard
Wide matrix channels and shallow penetration depth prevent polymer micro-fractures in dispersion-coated folding boxboard during creasing.
ISO 535 Standard
Water Absorption
Standardized test procedures specify the liquid absorption characteristics of sized paper or paperboard under controlled time intervals. Designated as the Cobb method, compliance with the iso 535 standard measures the mass of water absorbed per square metre of sheet surface during specified contact durations. This liquid absorption value indicates hydrophobic sizing effectiveness for packaging materials exposed to condensed moisture or liquid spillages.
Scope limits exclude non-absorbent plastic-coated boards or porous tissue papers.
Apparatus Specification
Metal cylinders with a hundred square centimetre cross-sectional area clamp tightly onto sheet samples. Neoprene gaskets prevent edge leakage during liquid contact.
Testing Procedure
Distilled water placed inside the test cylinder contacts the conditioned paperboard sample for precisely determined exposure times, such as sixty or one hundred and twenty seconds. Following liquid exposure, operators roll a standardized heavy metal roller over blotting paper placed on the wetted sample to remove excess surface water before weighing. Deviations from timing or rolling pressure specified by the iso 535 standard produce inaccurate Cobb values that misrepresent sheet water resistance.
Internal sizing additives like alkyl ketene dimer reduce water absorption rates in corrugated linerboard grades. Controlled liquid exposure testing ensures packaging compliance with maritime transport moisture specifications.