A SPRAY-DRYING PROCESS.

摘要

The present invention relates to a process for preparing a spray-dried powder comprising (i) anionic detersive surfactant; (ii) from 0 wt% to 10 wt% zeolite builder; (iii) from 0 wt% to 10 wt% phosphate builder; and (iv) optionally from 0 wt% to 15 wt% silicate salt; wherein the process comprises the steps of : (a) forming an alkaline slurry in a mixer, the slurry having a viscosity of from 0.5 to 50.0 Pas at a temperature of 70 °C and at a shear rate of 50 s-1, wherein the alkaline slurry is shear thinning; and (b) transferring the alkaline slurry from the mixer through at least one pump to a spray pressure nozzle; (c) contacting a viscosity increasing agent to the alkaline slurry after the mixer and before the spray pressure nozzle so as to increase the viscosity of the alkaline slurry to form a viscous alkaline slurry, step (c) being carried out at an average shear rate of from 10 s-1 to 150 s-1; (d) spraying the viscous alkaline slurry through the spray pressure nozzle into a spray-drying tower; (e) spray-drying the viscous alkaline slurry to form a spray-dried powder; and (f) optionally, contacting an alkalinity source with the alkaline slurry and/or the viscosity increasing agent, and/or the viscous alkaline slurry.