Abstract
Deresination effects of surfactants containing hydrotropic agent was evaluated during hot alkali refining in a conventional multi-stage refining process of sulfite pulp. When mixtures of sodium xylene sulfonate (I) with polyoxyethylene nonylphenyl ether (n=9) (II) were employed in the refining of sulfite pulp from fresh softwood, synergistic deresination effect was observed in the mixing ratio of 1:1 to 1:2 (i.e. (I) 50 to 33%, (II) 50 of 67%.) The deresination effect was also improved when (I) was mixed as a third component with surfactant mixtures comprising sodium dodecylbenzene sulfonate (III) and (II). Though ternary surfactant mixture comprising (I) (or sodium tetralin sulfonate) 1 part, (III) 1 part and (II) 2 parts cannot reduce the resin content of refined pulp below the maximum allowable for the pulp obtained from such wood as several days after felling, it is an excellent deresination agent for the pulp from wood seasoned for five to six months, and the amount to be added may be one twentieth of commercially available anionics.
When mixtures of (I) (or sodium methylnaphthalene sulfonate) with polyoxyethylene nonylphenyl ether (n=11) were applied in the refining of hardwood sulfite pulp, no synergistic effect was observed, but deresination effects of the mixtures were practically the same as with nonionic surfactant alone if the mixing ratio of hydrotropic agent is less than 50%.
