DE1055730B - Process for removing staining contaminants from waxes - Google Patents

Description

Method of removing staining impurities from waxing the The invention relates to a method for removing staining impurities from ester waxes or hydrocarbon waxing, a process that is often referred to in practice as "cleaning" or "bleaching" of waxes.

The previously known methods for removing staining impurities have various disadvantages: The adsorption process using bleaching earth, carbon, various silicates and the like are lossy or not sufficiently effective; the Oxidation methods that require pre-cleaning and using hydrogen peroxide, Chromic acid, peracids etc. change the wax chemically, so that the bleached wax has different properties than the starting wax; the Reduction methods, e.g. B. with nascent hydrogen are of limited use and have no lasting bleaching effect. According to U.S. Patent 2,168,330 it is known to clean wax with nitrobenzene.

To remove staining impurities from waxes are in the Dutch patent specification 44 737 Imine and in German patent specification 580 874 alkanolamines have been described. These procedures have been difficult because of the Way of separating the wax impurities and because of the cumbersome removal the unpleasant smelling and sometimes poisonous solvents are of no practical importance attained.

From the German Auslegeschrift 1019 784 it is known to cut the waxes to be cleaned with paraffin or Polväthv len and then bleached at 90 to 130 ° C with chromosulfuric acid. However, this two-step process is laborious and not without risk and always leads to a waste of wax. The original wax alone cannot be recovered in purified form using this process.

Dissolve aliphatic, aromatic or halogenated hydrocarbons the waxes completely on, so that at higher temperatures also the impurities are dissolved and as a result no stratification occurs, or it forms At low temperatures, homogeneous creams or pastes, such as those with nitrobenzene can be obtained. The bleaching of carnauba wax through partial saponification with Caustic soda is required for the purpose of better separation from the soap, which then causes the coloring Contains ingredients, a paraffin additive. The carnauba wax bleached in this way is therefore paraffin-containing and freed from saponifiable components, i.e. no longer to be addressed as pure carnauba wax.

It has now been shown that natural ester waxes such as carnauba, Ouricury, sugar cane, fiber, flax, esparto and other waxes as well as synthetic ones Ester waxes and hydrocarbon waxes, e.g. B. Ceresine, micro waxes and the like easy way to get rid of staining impurities that you can Waxes in the liquid state preferably at 70 to 90 ° C with one or more Nitroparaffins are added, which separates the two layers that form and the cleaned one Wax-containing layer in a known manner, for. B. by distillation, worked up. The impurities and coloring components collect in the Usually in the top layer. From the lower layer, which is the wax solution represents can, in addition to distillation, also by other known methods, e.g. B. by freezing and pressing or by centrifugation, the purified and discolored wax can be obtained. Substances can be used as nitroparaffins that are liquid at temperatures of at least about 70 ° C, in particular Nitroparaffins with 1 to 3 carbon atoms in the molecule, e.g. B. nitromethane, nitroethane or Nitropropane.

The nitro paraffins are weak and not unpleasant-smelling, thin ones Solvents that boil between about 100 and 180 ° C, a flash point of 40 up to 50 ° C, are not very soluble in water (0.5 to 2.0 'IM) and are relatively non-toxic.

A modification of the method according to the invention is that solvent mixtures are used in place of the nitroparaffins, which consist of polar, aliphatic and / or heterocyclic compounds with at least one oxygen and or Sulfur atom in the 'molecule and with dipole moments greater than 1.6 and the nitroparaffins in their solution properties and specific weights are similar or correspond to them. -The inventive method can also combine with other adsorption, bleaching or decolorization methods. So can one z. B. the waxy layer, if necessary, before working up to the pure Treat the wax with adsorbents or decolorizing agents.

The waxes obtained are light in color and chemical not changed in any way. The infrared spectra and the key figures of the bleached Waxes and the original waxes are unchanged. The separated residues are also chemically unchanged and can be used like originally bleached waxes, e.g. B. at the Manufacture of black shoe polish, etc., can be used.

The solvent mixtures that can also be used for cleaning waxes must be bad solvents for the waxes at room temperature and one have a sufficiently large difference in specific weight compared to the wax, thus a sharp separation of the impurities at temperatures between 70 and 90 ° C he follows. While the cleaned and discolored light wax components in these Temperatures in one layer must be clearly resolved, the other layer can contain small amounts of undissolved wax with the impurities. The solvent mixtures consist advantageously of polar aliphatic or heterocyclic compounds with at least one oxygen and / or sulfur atom in the 'molecule and possess Dipole moments above 1.6. Examples are lower alcohols, acetic anhydride, Dimethyl sulfoxide, dioxolanes and their substitution products.

It was also found that there are types of wax, which are based on the known or the process according to the invention not or only with difficulty of impurities let free by centrifugation or additional washing with hot water can be made suitable for this procedure. It is preferable to combine these two Process steps by washing with hot water while centrifuging.

Example 1 10 parts by weight of carnauba wax, light fat gray, are melted, 100 parts by weight of Nitroäthati are added and the mixture is brought to 80 ° C. with stirring. After standing for a short time, the impurities and coloring agents collect on the surface Components; the upper layer is separated and the wax-solvent mixture below freed from nitroethane by distillation. The resulting wax is very light in color and has a pale greenish color.

Example 2 Ouricury, sugar cane, fiber. Flax wax and others The waxes mentioned above are bleached according to Example 1 and also give light-colored waxes Waxes.

Example 3 10 parts by weight of carnauba wax, fat gray, are used as in Example 1 treated with 100 parts by weight of nitroethane. After separating the Dark constituents are mixed with full earth, activated charcoal or similar in the wax solution Adsorbent introduced. After filtering off the solid components and When the solvent is distilled off, a light, pale beige colored wax becomes obtain.

Example 4 8 parts by weight of carnauba wax, light fat gray, are like treated in example 1. The wax solution is cooled, the precipitated wax pressed off and freed from adhering solvent. The carnauba wax obtained is completely free of resin-like components. The squeezed-out nitroethane resin solution can be decolorized with activated charcoal cold or warm and the resin, if desired, be added again to the bleached carnauba wax.

Example 5 A very dark variety of carnauba which cannot be bleached with bleaching earth is centrifuged in the molten state and washed with hot water. That The wax obtained is treated further according to Example 1 or 3. It will be a light brown Preserved wax.

Example 6 10 parts by weight of carnauba wax are combined with 100 parts by weight a nitroparaffin mixture, consisting of 2-nitropropane and nitromethane in a ratio 3: 2, as indicated under Example 1, treated. The resulting wax is from light color. Example 7 8 parts by weight of carnauba wax, light fat gray, are melted, with 100 parts by weight of 2-dimethyl-4-oxymethyl-1,3-dioxolane, chemically pure, and mixed with 20 parts of ethanol and brought to 80 ° C. The impurities separate on the surface and are separated according to Example 1.

The wax obtained is light with a faint beige color.

Instead of ethanol, for. B. also methanol, propanol or a other similar oxygen and,! or sulfur-containing compound can be used.

Claims (5)

PATENT CLAIMS: 1. Method for removing staining contaminants from ester waxes or hydrocarbon waxes, characterized in that one the waxes in the liquid state, preferably at 70 to 90 ° C, with one or more Nitroparaffins are added, which separates the two layers that form and the waxy one Layer worked up in a manner known per se. 2. Modification of the procedure according to Claim 1, characterized in that solvent mixtures are used in place of the nitroparaffins used consisting of polar aliphatic and / or heterocyclic compounds with at least one oxygen and / or sulfur atom in the molecule and with dipole moments over 1.6 and their solution properties and specific weights den Correspond to nitroparaffins. 3. The method according to claim 1 or 2, characterized in that that the waxes before the addition of the nitro paraffins or solvent mixtures centrifuged and, if necessary, with hot water, preferably during centrifugation, washes. 4. The method according to claim 1 to 3, characterized in that the waxy layer before you work up with adsorption treated or decolorizing agents. 5. The method according to claim 1 to 4, characterized in that one uses nitroparaffins with 1 to 3 carbon atoms in the molecule. Documents considered: German Patent No. 580 874; German Auslegeschrift No. 1019 784; U.S. Patent No. 2,168,330; Dutch patent specification No. 44 737.