Let’s take a very simplified and quick look around the Pulp World. Cellulosic pulps are comprised of basically the same materials, cellulose (polysaccharides), hemicellulose, lignin, and extractives. The pulp characteristics and differences are:
Fiber Wall Thickness
Fiber Length
Fiber Diameter
Chemical Composition
And the separation process of the fibers from the chip matrix. This includes Kraft Cooking, Sulfite, NSSC, BCTMP, and other High –Yield processes. Also to be included is the Bleaching process for the bleached pulps.
These fiber properties can be a guideline as they explain the interaction with other fiber properties important to the papermaker and to the ultimate product.
Paper fiber properties that are critical include:
Drainage- related to WRV, porosity, strength development, and population
Wet Sheet Strength- coarseness, fiber-fiber bonding
Formation- coarseness, porosity, fiber population
Water Retention Value- fiber dimensions, fiber wall thickness, and coarseness
Porosity- coarseness, fiber population, fiber-fiber bonding
Bulk- fiber diameter, coarseness, fiber wall thickness
Fiber Stiffness- fiber length, fiber wall thickness
Opacity Ability- fiber length, fiber population, coarseness, fiber-fiber bonding
Tensile- fiber length, fiber-fiber bonding, fiber population
Tear – fiber length, fiber-fiber bonding
The correct blend of these properties will lead to optimized machine runnability, reduction in off-spec paper produced, optimized steam consumption, optimized chemical consumption, optimized fiber recipe cost, and potentially lead to superior end-product quality.
