Multi-ply Composition
Recycled fibre multi-ply folding boxboard consists of three or more distinct layers formed from recovered paper stock. The gd board relies on a grey waste paper core sandwiched between thinner top and back liners made of stronger white pulp or bleached mechanical fibre. This configuration provides the necessary stiffness for structural packaging while maintaining a printable surface on the outer side and a clean appearance on the reverse side.
Manufacturers produce the material on a multi-vat cylinder machine or a multi-ply fourdrinier machine where specific furnish recipes govern the properties of each individual layer.
Fiber Stratification
Mechanical integration of these layers ensures high bending resistance without requiring the expensive virgin chemical pulp density found in solid bleached boards. Different qualities of recycled furnish go into the middle ply to optimize bulk and cost effectiveness. A secondary layer of finer material or a white coating applied to the top surface improves ink receptivity and surface smoothness for graphic reproduction.
Production controls monitor the moisture content and basis weight distribution across the deckle to prevent delamination of the layers during the converting process.
Conversion Tolerance
Finished sheets or reels must maintain specific caliper consistency to function on high-speed die-cutting and folding equipment. Variations in density between the grey interior and the outer surface demand precise settings for creasing depth to avoid cracking the top liner during package assembly. Machines that process this stock require adjustments for the higher thickness typically associated with this grade compared to single-ply alternatives.
Optimal performance relies on the dimensional stability provided by the secondary treatment of the surface plies.
