Working up hydrophobic solvents from suspension polymerisation - by ultrafiltration, pref. using membranes with specified cut=off to remove dispersants and give pure solvent as permeate

摘要

A process is claimed for working up hydrophobic solvents (I) contg. dispersants (II) which are obtd. in reversed-phase suspension polymerisation after sepn. of the polymer. The process involves ultrafiltration to give (I) as the permeate. (I) are hydrocarbons, esp. cyclohexane. Ultrafiltration is carried out at 20-60 (pref. 20-40) deg. C and 0.2-1 (pref. 0.2-0.5) MPa, and (I) is pref. mixed with 0.5-5 (pref. 1-3) wt.% water before ultrafiltration; the membranes have cut-off point of 3000-40,000, pref. 6000-35,000 (mol. wt.), and (I) is pref. stirred before ultrafiltration. (I) are obtd. from reversed-phase suspension polymerisation of starch-acrylate graft copolymers (III) after sepn. of the polymer, and contain non-ionic dispersants. USE/ADVANTAGE - The invention provides an economical alternative to distn. for recovery of (I); energy consumption is below 1 kWh/t cyclohexane (no heating required), and the amt. of dispersant is reduced to 1/5-1/10 of the original amt., so that purified (I) can be re-used directly. (0/1)