DISSOLUTION OF POLYMERS

摘要

1379820 Dissolving butyl rubber gel EXXON RESEARCH & ENG CO 18 April 1972 17827/72 Heading C3P A method of removing butyl rubber gel from process equipment comprises (a) contacting the gel with a hydrocarbon or hydrocarbon halide solution of a Lewis acid catalyst of Formula (I) R a MX b where M is a Group IIIA or Group IVA metal, R is hydrocarbyl and X is halogen, (2) M1Y b where M1 is a Group IVA or Group IVB metal and Y is halogen or (3) AX c where A is boron or phosphorus and X is halogen; and a Lewis salt cocatalyst selected from hydrocarbon halides, hydrogen halides and organic acids; thereby solubilizing a portion of the gel and forming a sludge; (b) separating the solution of the solubilized gel from the sludge; (c) contacting the sludge with a polar solvent to dissolve the sludge; and (d) withdrawing the resulting polar solvent solution. The solvent may be an alkane, cycloalkane or aromatic hydrocarbon, methyl chloride or chlorobenzene. Preferred Lewis acids are ethyl aluminium dichloride, diethyl aluminium chloride, tin tetrachloride, titanium tetrachloride, zirconium tetrachloride, tin tetrabromide and titanium tetrabromide and boron trichloride, phosphorus trichloride and phosphorus tribromide. Preferred Lewis salt cocatalysts are benzyl chloride, t.-butyl chloride, allyl bromide, chlorobenzene, hydrogen chloride, hydrogen bromide, acetic acid, chloracetic acids and benzoic acid. The polar solvent may be an alcohol, ketone, aldehyde or solution of hydrochloric or acetic acid in water, ethers or hydrocarbons. Examples describe the treatment of butyl rubber gels with hexane solutions of (I) ethyl aluminium dichloride and benzyl chloride, (II) diethyl aluminium chloride and benzyl chloride, (III) aluminium trichloride and isopropyl fluoride, (IV) boron trifluoride and trichloracetic acid, (V) titanium tetrachloride and trichloracetic acid, (VI) aluminium bromide and hydrogen bromide, (VII) stannic chloride and hydrogen chloride and (VIII) isobutyl aluminium dichloride and t.-butyl chloride; using as polar solvents (I, II and VII) ethanol, (III) methyl ethyl ketone, (IV) methylene chloride, (V) isopropanol, (VI) methanol and (VIII) amyl alcohol.