MODELING OF MECHANICAL-PROPERTIES OF PAPE R AFFECTED BY ITS FURNISH COMPONENTS

When modifying the furnish of a paper, optimizing or developing new pa per grades the question arises, which blends of different pulps meet t he requirements of optical and mechanical properties as well as of pri ntability of the paper at minimized costs. In order to find the optima l sheet composition by means of a computer, models of paper are needed . Mechanical properties of stock blends can be calculated by a linear mass-proportion additivity of the properties of the single components of a mixture (mechanical pulp, chemical pulp and deinked pulp) concern ing bulk, tensile strength, stretch at rupture, tear strength, modulus of elasticity, zero span tensile strength and bond strength. The effe ct of fillers (china clay) can be calculated by empirical equations ba sed on experimental data on handsheets. Furthermore, it is shown how t o determine the properties of a commercial paper based on experimental data of handsheets. The effect of calendering on apparent density, te nsile strength and tear strength cannot be modeled but trends are show n.