Effect of hydrophilic substances in spruce TMP resin on its physico-chemical characterization and deposition tendency

The viscosity, wettability and deposition tendency of spruce thermomechanical pulp resin extracted with hexane, acetone and hexane–acetone (9:1, v/v) were studied in this paper. Some hydrophilic substances such as sugars and lignans could be extracted by some hydrophilic solvents, and the effect of the hydrophilic substances on physico-chemical properties is still not well known. The results showed that hydrophilic substances such as lignans and sugars present in spruce thermomechanical pulp resin had a great effect on resin physico-chemical properties. About 19% sugars and 14% lignans were identified in the acetone extracts, which could increase resin viscosity greatly. Only a little of lignans and sugars could be extracted by hexane–acetone, but these sugars and lignans could increase resin hydrophilicity evidently, leading to the decrease in contact angles with water and the increase in the acid–base component of work of adhesion. During preparation of resin dispersions, however, these sugars and lignans dissolved in dispersions could pass through the pores of the dialysis tube into water system which would cause an unexpected deposition result of the acetone-extracted resin dispersion. Resin extracted with hexane can be regarded as a relative ideal resin model in evaluating resin deposition tendency.