REDUCING THE CLOUD POINT OF HYDRODEWAXED BASE STOCKS

摘要

The cloud point or overnight cloud point of a hydrowaxed mineral oil base stock is lowered by reacting with S, pref. at about 150-250 (180-220) deg.C for about 1-5 hrs., to give a S content of about 0.01-0.2 wt.%. About 0.01-1.0 wt.% of an oil-sol. Mg, Ca or Ba cpd., pref. Mg 10C-salicylate, may be present during sulphurisation to reduce the development of colour. An inert gas (e.g. N2) may be passed through or over the sample during treatment to remove the H2S produced. In an example, the base stock for treatment was hydrodewaxed Adelaide MLDW Bright Stock (150 SUS at 210 deg.F; VI=95; pour pt.= 20 deg.F). 200g of this stock, 0.043g S and 0.4g Mg 10C-salicylate were heated at 180 deg.C under an N2 stream. The prod. was cooled to 90 deg.C and filtered through diatomaceous earth. The filtered prod. contained 0.02% S and 0.004% Mg. A sample was submitted to the overnight cloud pt. test by heating to 212 deg.F., then maintaining at 30 deg.F overnight, and then measuring haze nephelometrically. A value of 9 was found: the untreated base stock gave a value 33. (Values of 10 and more indicate visible haze).