Patent GB-773820-A (GB)
Title: Improvements in and relating to molybdenum lubricants and their manufacture
IPC: C10M141/02
Filed: 1955-01-06
Abstract: A stable solution of molybdenum blue in a water-immiscible, hydrocarbon-miscible, solvent is employed as an additive for lubricating oils.  Suitable solvents are aliphatic alcohols containing 6 to 12 carbon atoms and water insoluble, hydrocarbon soluble, organic phosphorus compounds of the general formula <FORM:0773820/III/1> where X is an oxygen or sulphur atom, Y is -OR, -NR2 or -NHR1, and R and R1 are aliphatic radicals containing 2 to 12 carbon atoms and also alkyl phosphonates of the general formul <FORM:0773820/III/2> wherein R and R1 are aliphatic radicals containing 2 to 12 carbon atoms.  The molybdenum blue solution may be prepared by acidifying an aqueous solution of molybdenum blue with sulphuric or hydrochloric acid, extracting the aqueous solution with isobutyl alcohol, adding an organic liquid, preferably an aliphatic alcohol containing 6 to 12 carbon atoms which is soluble both in isobutyl alcohol and hydrocarbons, and removing the isobutyl alcohol and part of the added organic liquid by distillation under reduced pressure to obtain a 20 to 40 per cent solution of molybdenum blue in the organic liquid.  The isobutyl alcohol extract may be dried over magnesium sulphate and filtered prior to the addition of the organic solvent.  If an organic phosphorus compound is employed as a solvent the acidified aqueous solution of molybdenum blue may be directly contacted with such a phorphorus compound to obtain the desired molybdenum blue solution therein.  Alternatively, when employing an organic phosphorus compound as solvent an acidified aqueous solution of an alkali metal or ammonium molybdate may be reduced with aluminium in the presence of the organic phosphorus compound, whereby the molybdenum blue is formed in the oily organic phosphorus compound layer which may then be decanted and dried. According to examples (1) a sodium molybdate solution acidified with sulphuric acid and containing also diammonium phosphate was heated to boiling point and aluminium foil added whilst continuing heating under reflux.  The mixture was rapidly cooled to room temperature and was extracted with isobutyl alcohol.  The isobutyl alcohol solution was then mixed with a C12 alcohol and the mixture dried over anhydrous magnesium sulphate and filtered, after which the isobutyl alcohol was driven off under reduced pressure whilst raising the temperature.  A 33 per cent solution of molybdenum blue in the C12 alcohol resulted.  (2) Powdered molybdenum was added to a suspension of molybdenum oxide in water and the mixture heated to boiling point in a nitrogen atmosphere and subsequently filtered to obtain a molybdenum blue solution.  The solution was extracted with diethylamide - di - decylphosphate.  The mixture was diluted with n-hexane to facilitate decantation and the hydrocarbon layer containing the molybdenum blue and the phosphate compound was dried over magnesium sulphate and the hexane driven off.  (3) An aqueous solution of acidified sodium molybdate was treated with normal bisdecyl diethylamido - thiophosphate and aluminium foil at boiling point after which the reactants were cooled to room temperature and the oily layer containig the molybdenum blue separated and dried.  Further examples relate to the extraction of the molybdenum blue with triethyl phosphate ester, octylamidodioctyl phosphate, monodecylamidodidecyl phosphate and monoduodecylamide diduodecyl phosphate.  The molybdenum blue solutions obtained may be employed as high pressure dopes for mineral oil lubricants and they may be employed in conjunction with a sulphur compound capable of decomposing under the temperatures obtained by friction thus causing the precipitation of molybdenum sulphide.  Suitable sulphur compounds are benzyl sulphide, benzyl disulphide, and xanthates of diols or glycols. The lubricants may also contain tertiary polychlorinated butyl benzines.  An extreme pressure lubricant consisting of a mineral oil having a viscosity of 54 centipoises at 50 DEG C. and containing 1 per cent of molybdenum blue solution together with 2 per cent of glycol dibenzyl-xanthate is described.