Inter-Ply Bond Measurement Standards in Recycled Paperboard Production
Inter-ply bond standards mandate TAPPI T 541 or ISO 16260 testing under strict ISO 187 conditioning to prevent converting delamination on recycled paperboard.
TAPPI T 833
Standard Method
Standardized testing procedures measure the bending resistance of paperboard and paper using a multi-point bending method. The protocol known as tappi t 833 defines the method for determining the stiffness of the board by measuring the force required to deflect a specimen by a set angle. This standard is used by quality control laboratories to ensure that board shipments meet the requirements for high-speed packaging lines.
Measurement Apparatus
The test specimen is clamped at one end, and a force is applied to the free end by a moving pointer or a digital load cell. The resistance of the paperboard to this deflection is recorded in stiffness units, which are used to calculate the bending stiffness of the sheet. Tests must be performed in both the machine direction and the cross direction, as the orientation of the fibers makes the board much stiffer along the machine direction.
The laboratory must be maintained at a constant temperature and humidity, as moisture content has a major impact on the stiffness of paperboard.
Quality Application
Lower stiffness values than specified can lead to carton collapse during filling or stacking on pallets. The test is limited to materials within a specific thickness range to prevent shearing effects.