447 WOOD RESEARCH 65 (3): 2020 447-458 BLENDING IMPACT OF HARDWOOD PULPS WITH SOFTWOOD PULP ON TISSUE PAPER PROPERTIES Monika Stankovská, Mária Fišerová, Juraj Gigac, Elena Opálená Pulp and Paper Research Institute Bratislava, Slovak Republic (Received November 2019) ABSTRACT The influence of proportions of bleached birch, eucalyptus, beech kraft pulps as well as the bleached aspen chemi-thermomechanical pulp (BCTMP) in the mixture with bleached pine kraft pulp on tissue paper properties was compared. Increase of bleached beech kraft pulp and aspen BCTMP proportion in a mixture with bleached pine kraft pulp leads to significant rise of porosity ε as well as bulk. The water absorption after immersion increased significantly with increase of aspen BCTMP content in the mixture while other hardwood pulps in the mixture had only moderate impact. Increasing of bleached beech and eucalyptus kraft pulps content in the mixture continually increased initial water absorption. As a result of blending of bleached birch kraft pulp with bleached pine kraft pulp, bulk softness improved and the tensile index increased slightly. The increased content of bleached birch and beech kraft pulp in the mixture increased the brightness while the addition of aspen BCTMP and bleached eucalyptus kraft pulp increased of coordinate b* value. Mixed pulps with properties suitable for different types of hygienic products were selected. KEYWORDS: Hardwood kraft pulp, softwood kraft pulp, chemi-thermomechanical pulp, water absorption, tensile index, bulk softness, optical properties, tissue paper. INTRODUCTION The expenses of fibre typically accounts for more than 50% of the total cost of hygienic papers production, depending on their properties such as softness, bulk density, strength and absorption capacity. The highest quality tissue paper products are mainly made of pulp, usually a mixture of long-fibre pulp of softwood wood with short-fibre pulp of hardwood wood. Hygienic products made of 100% hardwood pulp can be very soft, but are less rigid than from softwood pulp. Their disadvantage is also the degradation of strength during embossing. Additives may be used to increase the strength, but they affect the cost and the resulting properties of tissue paper. doi.org/10.37763/wr.1336-4561/65.3.447458