A simple model to examine the impact of changes in wood traits on the costs of thermomechanical pulping and high-brightness newsprint production with radiata pine

A number of functions were investigated that related the costs of thermomechanical pulp (TMP) and high-brightness newsprint production, using Pinus radiata D. Don, to important pulp and paper quality (breeding objective) variables, including specific energy consumption and pulp handsheet tear and tensile strength, brightness, and opacity. Pulp handsheet quality traits were considered to be reasonable two-dimensional predictors of paper quality traits in this context. A specific production process that requires the use of a reinforcement kraft pulp and an artificial clay filler to improve the quality of paper produced from the bleached TMP fibres was investigated, similar to the production process used by Australian Newspaper Mills' Boyer Mill in Tasmania, Australia. Pulp and pulp handsheet quality variables could be explained by significant (P > 0.05) wood traits using multiple linear regression equations. This provided a method to predict the economic importance of each wood trait in relation to the thermomechanical production process investigated. The results showed that tracheid length, wood density, wood brightness, and tracheid coarseness were the best predictors of costs. Increases in tracheid length, wood density, and wood brightness and decreases in tracheid coarseness resulted in decreasing the total costs of TMP and high-brightness newsprint production.