GB816669A - Bitumen composition - Google Patents

Abstract

An alkaline aqueous bitumen emulsion comprises a bitumen composition made by adding wax acids derived from oxidizing a petroleum wax to the residue obtained when a crude petroleum oil is distilled at atmospheric pressure, the mixture of wax acids and residue being then distilled under reduced pressure to remove lighter materials, i.e. light acids containing less than 30 carbon atoms/molecule and light oil, so as to leave a residue of bitumen containing wax acids, this residue having an acid number of 0.8 to 3. A preferred wax acid is that obtained by the catalytic air oxidation of slack wax in accordance with Specification 816,670, [Group IV (b)]. Of the wax acids remaining in the bitumen after lighter materials have been removed less than 15 per cent by weight contain less than 30 carbon atoms/molecule, the acids containing more than 30 carbon atoms/molecule assisting the emulsifiability of the bitumen in aqueous alkali. A specified emulsion contains, in parts by weight, the following: a residue of bitumen 15-65 and heavy slack wax acids 2-6, water 35-85, sodium hydroxide 0.03-0.15, and 0.01-1 of a bitumen emulsion stabilizer, e.g. tall oil or neutralized Swedish liquid rosin.ALSO:A bitumen composition suitable for the preparation of aqueous alkaline bitumen emulsions is made by adding wax acids to the residue obtained when a crude petroleum oil is distilled at atmospheric pressure and then subjecting the mixture of wax acids and residue to distillation under reduced pressure so as to remove lighter materials and leave a bitumen containing wax acids, as a residue, the residue having an acid number of 0,8 to 3. Wax acids are obtained by oxidising a petroleum wax such as a slack wax, microcrystalline wax, crude or purified paraffin wax, by means of an oxygen-containing gas, e.g. air, in the presence of a catalyst, e.g. carboxylic acids, metal salts such as manganous and cobalt salts, vanadates, permanganates. The wax acids may have an acid number of from 40 to 100, a preferred wax accordance with Specification 816,670 [Group IV(b)]. Lighter materials are defined as light acids containing less than 30 carbon atoms/molecule, and light oil. Wax acids containing more than 30 carbon atoms/molecule are said to assist the emulsifiability of bitumen in aqueous alkali and these acids remain with the bitumen as residue after lighter materials have been distilled off. Of the wax acids remaining with the bitumen less than 15 per cent. by weight contain less than 30 carbon atoms per molecule. A specified emulsion contains, in parts by weight the following: a residue of bitumen 15-65 and heavy slack wax acids 2-6, water 35-85, sodium hydroxide 0,03-0,15, and 0,01-1 of a bitumen emulsion stabilizer, e.g. tall oil or neutralized Swedish liquid rosin.