GB785890A - Improvements in manufacture of alkali cellulose by cellulose slurry-steeping - Google Patents

Abstract

Chemical cellulose pulp containing up to 0.35 per cent by weight of natural matter extractable with ethyl ether is slurry-steeped in an aqueous solution of caustic alkali in the presence of a small proportion of a surface-active agent having the formula <FORM:0785890/IV (a)/1> , in which x is 3.3-106 and y is 19-31, particularly an agent of the above formula in which x has an average value of 15.5 and y has an average value of 28. The agent may be added to the cellulose pulp, the caustic alkali solution or the slurry, and its proportion may be about 0.02-0.25 per cent, based on the dry pulp. In an example, pulp sheet of 96 per cent alphacellulose content and containing 0.12 per cent ether-extractable matter is slurried at 2.2 per cent concentration in a steeping liquor containing 18.6 per cent of sodium hydroxide and 1.5 per cent of hemicellulose to which is added 0.1 per cent (based on the dry pulp) of a surface active agent having the above formula in which x is 15.5 and y is 28. The pulp may be Jordanned or otherwise mechanically treated before being slurried to straighten the fibres and reduce the proportion of surface-active agent required. The presence of the agent during slurry-steeping reduces foaming of the steeping liquor and floating and clumping of the fibres. Specifications 573,775, 575,138, 590,064, [all in Group IV], 601,783, 623,566, 685,842, and 685,843 are referred to.