GB903610A - Production of regenerated cellulose from wood pulp - Google Patents

Abstract

In the manufacture of regenerated cellulose filaments from prehydrolysed sulphate chemical wood pulp by the viscose process, there is incorporated in the viscose a modifying agent consisting essentially of an ethylene oxide-1.2 propylene oxide ester of disproportionated rosin in amount from 0,5% to 3,5% by weight of the bone dry pulp, the oxides being present in the esters in amount from 1,5 to 9 times the weight of rosin, and the ethylene oxide constituting from 40% to 85% of the total oxide weight of the esters. The modifying agents are esters of a mixture consisting substantially of dehydroabietic acid with minor proportions of dihydroabietic and tetrahydroabietic acid. This agent may be added at any stage prior to spinning, but is preferably added prior to the completion of steeping in the slurry viscose process and prior to the completion of shredding in the sheet steeping viscose process, and especially is added to sheeted prehydrolysed sulphate pulp. The amount of agent added may be 0,5% by weight of the bone dry pulp. The agent modifies the skin to core ratio of the filaments spun from the viscose, and their cross-sectional shape. The skin to core ratio obtained increases as the percentage of ethylene oxide in the agent is increased and vice versa. In viscose spinning, the skin to core ratio and cross-sectional shape of the filaments may be changed without interrupting the process by changing the modifying agent added to the viscose to one having a different proportion of ethylene oxide. The viscose may be spun in an acid bath, containing zinc sulphate and the filaments so made may be stretched in a second bath.