Patent GB-740558-A (GB)
Title: A process for the extraction of mineral oil contaminants from synthetic lubricants
Inventor: HOARE MICHAEL FREDERICK
IPC: C10G17/02
Filed: 1953-01-21
Abstract: Synthetic lubricant is removed from a mixture of a synthetic lubricant and a mineral oil, for example a used synthetic lubricant which has become contaminated with mineral oil, by solvent extraction using an aliphatic carboxylic acid containing 1-6 carbon atoms per molecule as the solvent, and the synthetic lubricant is separated from the extract phase.  The solvent employed may be acetic acid, either glacial or containing minor proportions of water, and the solvent may be removed from the extract phase by water-washing.  The synthetic lubricant may be a complex ester and the general formul  of suitable classes of complex esters are given, the complex esters mentioned in Specifications 659,103, 662,650, 664,992, 666,697 and 668,663 lying within the scope of these formul .  Specifications 687,346, [Group IV (a)], and 743,571, [Group III], are referred to in the Provisional Specification.ALSO:Synthetic lubricant is removed from a mixture of a synthetic lubricant and a mineral oil, for example a used synthetic lubricant which has become contaminated with mineral oil, by solvent extraction using an aliphatic carboxylic acid containing 1-6 carbon atoms per molecule as the solvent, and the synthetic lubricant is separated from the extract phase.  The solvent employed may be acetic acid, either glacial or containing minor proportions of water, and the slvent may be removed from the extract phase by water-washing.  The synthetic lubricant may be a complex ester and the various classes of complex esters are discussed in detail.  Alternatively, the synthetic lubricant may be a blend of a complex ester with an oleoginous liquid containing either oxygen or thioether sulphur linkages in its molecule (e.g. glycol ether or polyglycol ether, or an ester, particularly a glycol diester, in which either the acid or the alcohol or both contain the desired linkages) or with a diester of an aliphatic dicarboxylic acid.  The synthetic lubricant blends disclosed in Specifications 687,346 and 743,571 are mentioned in the Provisional Specification.  The synthetic lubricant may contain antioxidants and these are discussed under the following headings:-(1) phenolic compounds, (2) aromatic nitro compounds, (3) aromatic amines and aliphatic primary amines, (4) organic sulphur compounds, and (5) organic compounds containing both phosphorus and sulphur.  The waterwashing of the extract phase may be repeated a second stage and an emulsion breaker such as methyl alcohol may be employed.  The water-washed synthetic lubricant may be washed with sodium carbonate to reduce acidity and then given a final water-wash.  The synthetic lubricant may then be stripped to remove emulsion breaker and water.  In the examples, a lubricant consisting of a complex ester derived from sebacic acid 2-ethyl hexanol and a polyglycol of molecular weight 200, together with dinovyl sebacate and small amounts of mineral oil, is freed of mineral oil by extraction with acetic acid. Specifications 659,103, 662,650, 666,697 and 668,663 also are referred to.