Effect of Virgin Fiber Content on Strength and Stiffness Characteristics of a Three-layer Testliner

Abstract

Research results on the improvement of the strength properties of a testliner produced from recovered paper and kraft pulp are presented in this work. The effects of kraft pulp content and the fractionation of secondary fiber on testliner strength properties were determined. Primary and recovered paper pulp was produced using standard procedures. The testliner consisted of three layers, totaling a grammage of 150 g/m2, when the center layer was made solely from the short fiber fraction of recovered paper. The weight of the surface layers each comprised 30% of the total handsheet weight, and the center layer weight was 40%. The virgin fiber content of the upper and lower layers was varied from 0% to 30% of the corresponding handsheet layer weight. The breaking length, tensile strength, modulus of elasticity, longitudinal and bending rigidity, and bursting and plybond strength, along with the effects of virgin fiber dosage on the strength properties were experimentally determined. As a result, a composition was proposed that showed the rational arrangement of virgin fibers as well as short- and long-fiber fractions of recovered paper in the layers. A comparison of the strength properties of the testliner using standard parameters demonstrated the advantages of the testliner producing technology.

Keywords

• Refining
• Cardboard
• Recovered paper
• Mechanical properties
• Fractionation