Enhanced quality - strength and cost efficiency by means of layering

The effect of adding thermomechanical pulp (TMP) in fine paper’s middle layer was studied. Bleached hardwood pulp made of birch (BHW) was studied in top and bottom layers while TMP was layered in middle layer of handsheets. Layering of TMP in the middle enhanced surface smoothness significantly compared to trialspoints where pulps were mixed and homogenous. Adding 40% of TMP pulp in the middle layer had no effect on surface properties of handsheets. Addition of TMP increased bulk of uncaledered handsheets significantly. Increase of TMP or stratifying the pulps had no effect on dry paper tensile properties. Tensile strength and residual tension i.e. tension holding capacity of wet web increased significantly with increasing of TMP in furnish. Mixing TMP in pulps instead of stratifying gave higher tensile and residual tension values for wet samples. Addition of TMP decreased brightness significantly