Saturation Technology for Corrugated Containers, 1992 Corrugated Containers Conference Proceedings

R. N. Jopson--Demands for high strength in corrugated containers can be met by boosting basis weight but at the expense of grater conversion and transport costs, uneconomic wood use and a greater mass of waste for disposal. Saturation offers an attractive alternative. The objective of the work described here was to discover and optimise effective chemistries for strength improvement in corrugating materials.

High compressive strength at normal and high humidities were demonstrated with virgin and recycled base sheets. Effective polymers included both styrene acrylics and polyvinyl alcohol, but economics dictated the incorporation of a cheap extender, such as colloidal lignin into the formulation. Lignin-acrylic systems showed particular benefit as strength enhancers and would be a valuable end use for surplus lignin.

Changes in sheet physical properties on saturant addition indicated that the additives act as ’reinforcing networks’ increasing strength without crosslinking the cellulose so preserving the recyclability of the sheet. Saturation can be off-line or on the paper machine, pilot trials emphasised the benefits of a hydrodynamic saturator. The development of saturants based on lignins will provide an economic means of extending fibre use and producing high strength materials.