process for preparing a stable dispersion of barium carbonate, which can be used as an additive for lubricating oils

摘要

A lubricating oil composition may contain 1 to 20% of a dispersion of a barium carbonate material, 0.65 to 7% of oil-compatible oxidation inhibitors and antifoaming agents and sufficient oil base to make 100%, all percentages being by weight. The lubricating oil base is preferably a blend of high viscosity, highly refined mineral lubricating oils. The finished oil composition should have a base number of at least about 2.0 and preferably not less than about 3. A four point depressant and viscosity index improver may be added. The specified oxidation inhibitor is zinc dithiophosphate, and the foam inhibitor is silicone oil.ALSO:A barium-carbonate-containing dispersion is produced by forming a mixture containing an oil-soluble dispersing agent, a non-volatile, oil-soluble, diluent liquid, a glycol ether solution of barium oxide and/or hydroxide-said solution having a base number of at least 110 and the ether having the formula R.O.CH2.CH2.OH, or R1.O.CH2.CH2.O.CH2.CH2.OH where R is a hydrocarbon group containing 1-6 carbon atoms and R1 is a hydrocarbon group containing 1 to 4 carbon atoms-and passing CO2 through the mixture to produce the desired dispersed material and removing undesired volatile material either before or after the carbonation step by steam treatment or boiling to produce the desired dispersion. Preferred dispersing agents are oil-soluble sulphonic acids, carboxylic acids or phosphorus sulphide treated olefines and metal salts thereof. The oil soluble diluent liquid is preferably a mineral or synthetic lubricating oil. 1 to 5 moles of CO2 may be passed through the mixture for each mole of a neutralized barium containing base present therein. A preferred composition of the reaction mixture is given, and the preferred ether is 2-methoxy-ethanol. The mixing may be carried out at atmospheric pressure at a temperature of 25-120 DEG C. and the CO2 may be bubbled through the mixture at a temperature of 21-63 DEG C. until it is acidic to p-naphthol benzein indicator.ALSO:A solution comprises a glycol ether having the formula R.O.CH2OH or R1O.CH2.CH2. O.CH2.CH2.OH, where R is a hydrocarbon group containing 1 to 6 carbon atoms and R1 is a hydrocarbon group containing from 1-4 carbon atoms which ether has in solution at least 18.5% by weight of Ba calculated as carbonate. The solution may be prepared by adding Ba oxide and/or hydroxide to the glycol ether preferably in small increments so as to avoid excessive heating of the mixture as a result of the exothermic reaction which occurs. The addition is also preferably made under a blanket of inert gas e.g. N2 in the presence of small amount of oxidation inhibiting compoun e.g. ditertiary butyl cresol in amount of 0.025 to 0.1% by weight. If it is desired to add the whole of the barium base at once, the mixture must be cooled to keep the temperature below the b.pt. of the glycol, e.g. at a temperature from 80-90 DEG C. After the reacation has subsided, the mixture is heated to a temperature between 80 DEG C. and the b.pt. of the glycol for a period of 10-30 minutes and then cooled. In the examples the ether used is 2-methoxy ethanol.