Paperboard Middle Ply Furnish Compression Mechanics under Static Bench Conditions
Middle ply CTMP bulk provides structural moment of inertia, while short-span compression bench testing quantifies network collapse risks under load.
Wet End Starch Addition
Chemical Treatment
Introduction of cationic or amphoteric polysaccharides to the dilute pulp suspension before the forming wire enhances the internal bonding of the finished sheet. By strengthening the fibre network, wet end starch addition improves the burst strength, tensile strength, stiffness, and surface pick resistance of the paper. The starch molecules bind to the negatively charged cellulose fibres and fines, creating a bridge that strengthens the web.
This process is more efficient when the starch is properly cooked and dispersed to ensure maximum contact with the solids in the furnish.
Retention Mechanism
The success of the treatment depends on the ionic balance within the headbox. Within the headbox, wet end starch addition requires careful monitoring of the charge density to prevent the buildup of dissolved and colloidal substances that can interfere with the drainage. If the dosage is too high, the excess starch remains in the process water, increasing the biological oxygen demand of the effluent and potentially causing foam or slime.
Proper retention ensures that the polymer stays with the fibres rather than washing away through the wire.
Physical Property
Increased internal strength allows for the use of more filler or recycled fibre without compromising the performance of the packaging. The presence of the polymer also helps to anchor surface treatments applied later in the production line.