Continuous on-line determination of particle size distribution in polymer dispersions involves simultaneous optical counting and crossflow fractionation using surfactant solution as carrier and flushing liquids in the fractionator

摘要

Continuous determination of particle size distribution in polymer dispersions involves simultaneous optical counting and crossflow fractionation of sample streams diluted with water and surfactant solution, using surfactant solution as carrier in the fractionator and flushing the analyzer section with surfactant solution after every 100 samples at the latest. A method for the continuous determination of particle size distribution (PSD) in polymer dispersions by simultaneous characterization by means of optical counting of single particles and flow-fieldflow fractionation (crossflow fractionation) or hydrodynamic fractionation involves (i) continuously taking a sample stream from a product line, (ii) diluting the sample stream with high-purity water and aqueous surfactant solution to a solid content of 0.3-20 g/l and a surfactant content of 0.1-5 g/l, (iii) taking off a part stream (continuously or discontinuously) and determining the PSD in at least one partial size range between 0.5 and 1000 microns with the aid of single particle analyzer(s) and (iv) taking repeated discontinuous samples from the diluted stream and determining the PSD in at least one size range which includes the range 0.005-2 microns, with the aid of a cross-flow fractionator with UV detector. The carrier liquid used in the fractionator is a surfactant solution with a concentration of 0.1-5 g/l and the analyzer section of the fractionator is washed with a flushing solution containing 2-30 g/l surfactant, at the latest after every 100 repeats of step (iv).