GB675001A - Improved sisal wax and method of producing the same - Google Patents

Abstract

Sisal wax is separated from the sisal leaf by contacting the leaf with a solvent for sisal wax whilst the leaf retains its original fibre structure and its aqueous pulp in uncrushed form. The fibre may then be separated from the leaf in the usual decorticating drum, the leaf being preferably sufficiently hot to be limp during this treatment, which condition may be brought about by using a solvent heated to at least 50 DEG C. in the wax extraction. The solvent is preferably anhydrous and immiscible with water. Chlorinated hydrocarbons are preferred and the following are specified: trichlorethylene, perchlorethylene, and carbon tetrachloride. The solvent may be used heated and preferably in the vapour form, at or above its boiling point. An open or closed tank may be used for the extraction, in the latter case with reduced or increased pressure. An open, vapour-degreasing tank is preferred, equipped with a heater for the solvent in its lower part and with a cooling coil at its rim, thus forming a vapour zone between the solvent and the top of the tank wherein the leaf is suspended vertically or inclined to allow the condensed solvent thereon with its dissolved wax to drip into the tank. The solvent is preferably of boiling point below 100 DEG C. so that its vapour does not vapourize the water of the sisal leaf. The wax is then recovered from the solution, after filtering, in a conventional vaporizing and solvent recovery apparatus. A wax of lighter colour and containing less impurities is obtained than in the usual extraction from the dried sisal pulp freed from the fibres. The wax may then be refined to remove the remaining colour, fatty oils, and resins. The decolorizing may be effected with adsorbents by treating the molten wax either with a mixture of activated clay and activated carbon or with lignin whilst heating, followed by filtration. Chemical decolorizing agents may be used in addition or alternatively, such as sodium hypochlorite, bleaching powder, organic peroxides such as benzoyl peroxide, inorganic peroxides, and sulphuric acid. The fatty oils may be removed from the crude wax by means of acetone, higher boiling ketones, diethylether, or higher boiling ethers at room temperatures, which dissolve the fatty oils leaving the wax with its resin impurities. After filtration the wax is treated to remove the latter by means of hot alcohols, such as methanol, ethanol and isopropanol, in which the resin impurities are insoluble. The solution of wax in the solvent is then separated and cooled to room temperature or lower to precipitate the purified wax.