1.ApplicationNumber: US-81439959-A
1.PublishNumber: US-3010897-A
2.Date Publish: 19611128
3.Inventor: MYERS HERBERT
OTTO FERDINAND P.

4.Inventor Harmonized: HERBERT MYERS()
OTTO FERDINAND P()

5.Country: US
6.Claims:

7.Description:
(en)COLLQEDAL BM CABONATE DISPERSION AND BAUM SOAP-BARIUM CONATE GASE CGMPOSHION Herbert Myers, Merchantville, and Ferdinand P. Otto,
Woodbury, NJ, assign'ors to Socony Mobil Oil Company, Inc, a corporation of New York No Drawing. Filed May 20, E959, Ser. No. 814,399
, 3 Claims. (Cl. 252-18) The present invention relates to the production of colloidal barium carbonate and, more particularly, provides an improved method for producing colloidal suspensions of barium carbonate embodying unique properties by which they are particularly adapted to use in the thickening or gelling of petroleum lubricating oil fractions for the production of lubricating greases. The invention also provides the novel and highly useful colloidal suspensions so produced and improved lubricating greases produced through the use of our improved suspensions.
Lubricating greases have for decades been prepared by thickening a petroleum lubricating oil fraction with a soda or lime soap of a long chain fatty acid, such as oleic acid, palmitic acid or stearic acid, or mixtures thereof, the soap being produced by saponifying the fatty acid premixed with the oil fraction. More recently, the soaps of other metals have been used in the manufacture of lubricating greases.
It has, also, more recently, frequently been found desirable' to incorporate in lubricants a substantial amount of an oil-soluble base material, sometimes designated reserve base, for the purpose of neutralizing acidic materials with which the lubricant comes in contact during use. For this purpose, it has been'proposed to incorporate in lubricating oils an excess of base material as an oilsoluble basic soap or as an oil-soluble complex of -a colloidal alkaline earth metal oxide or carbonate with '21 petroleum sulfonate.
More particularly, it has been proposed to use as the acid-neutralizing agent or detergent in petroleum lubricating oils, an oil-soluble basic soap or complex of barium carbonate and a sulfonic acid containing a substantial excess of the carbonate. In the preparation of these-oilsoluble salts or complexes, an anhydrous mixture of methanol, mineral oil, barium oxide and an oil soluble or ganic acid or acid salts, such as sulfonic acid or barium sulfonate, is blown with carbon dioxide.
As distinguished therefrom, the present invention is concerned primarily with the production of lubricating greases consisting essentially of a petroleum lubricating oil fraction thickened to grease consistency by incorporating therein a thickener or gelling agent produced by re- 1 acting a long chain fatty acid, for instance stearic acid, with a substantial excess of colloidal barium carbonate. The invention is more particularly directed to the production of a colloidal suspension of barium carbonate especially suited to that purpose.
It will be appreciated that, in order to function as a thickening agent for the mineral oil, for purposes of the present invention, the additive must be substantially insoluble in the oil. The oil-soluble materials, heretofore proposed as additives for lubricating oil, have been found a not to be effective as thickening or gelling agentsfor the oil to form a grease, especially greases which are stable toward water and are adapted to use under conditions of high temperature and high bearing loads.
It is, therefore, a primary object of the'present invention-to provide a colloidal suspension of barium carbonate through the use of which there may be produced greases which, under normal conditions of storage and under conditions of use at a wide range of temperature 1 conditions, are stable against excessive separation or 3,010,897 Patented Nov. 28, 1961 ice bleeding of the mineral oil constituent and which pro- .vide satisfactory lubrication under high temperatures andv cerned, the colloidal barium. carbonate used must possess a certain characteristics, presently not fully understood, but which may be consistently reproduced by strictadlierence to the conditions herein described and claimed.
We have found that for producing satisfactory greases of the type described, the colloidal suspension of barium carbonate used should not be formed in the presence of either the fatty acid, or the mineral oil. It further appears that the colloidal suspension so produced should be relatively stable, even in the presence of atmospheric moisture or water. The size and uniformity of size of the barium carbonate particles are also believed to be important factors infiuencingthe thickening properties of the excess carbonate and avoiding abrasive action. I
It has been proposed, forinstance, to use as a thickening agent in greases adapted to withstand widely varying temperatures, a colloidal dispersion of calcium carbonate which has been coated by chemical interaction with the calcium salt of a low molecular weight polycarboxylic acid. It has been reported that, for this purpose, a very special mode of preparation of such thickening agents is required. More particularly, it has been reported that the colloidal dispersion of the calcium carbonate must be prepared in situ in a mixture of the liquid vehicle and an appropriate solvent, and that a dispersing agent must necessarily be present during the carbonation in order to obtain: the carbonate in sufficiently small particle size. Following carbonation, the dicarboxylic 'acid is added to the dispersion to react With-the resultant calcium carbonate. Subsequent removal of the solvents is said toproduce' the thickened grease.
According to our present process, the colloidal suspension of the carbonate is separately prepared, in the ab- .sense of the lubricant vehicle, and no dispersingagent uniform particle size is not obtained. Further, when one attempts to use an excess of the resultant suspension for reacting with a fatty acid dispersed in mineral oil to form a grease, there is invariably obtained an unstable mixture from which the oil separated upon standing.
We cannot, at present, state with certainty the characteristic of the resultantcolloidal carbonate which is responsible for this unsatisfactory result. One may speculate thatthe particle diameter or structure or surface chemistry or. some combination of these characteristics of the resultant colloidal particles is responsible for this deficiency. It seems possible that when formed under certain conditions the individual colloidal particles are joined together, after the fashion of certain types of carbon black, to form reticulate chains or clusters which definitely influence'the behavior of the colloid.
v Whatever the cause, we have found that colloidal suspensionsof'barium carbonate especially adapted for the purpose herein described and which are surprisingly stable, even toward water, may be produced by reacting barium oxide with an excess of anhydrous methylalcohol and'thereaften-adding to the 'resultant'solution, and
uniformly mixing therewith, a minor proportion of Water prior to passing carbon dioxide gas into the solution.
We have found, more particularly, that the barium oxide must be dissolved completely in the anhydrous methyl alcohol prior to the adding of the water. Water is, of course, readily miscible with methyl alcohol in all proportions. However, when barium oxide is dissolved in the methyl alcohol, a methanol solution of the reaction product is formed with which water is much less readily miscible. Therefore, precaution should be taken to assure thorough, uniform mixing of the added water with the methanol solution prior to carbonation.
We have found that in the absence of water in the proportion hereinafter described, a waterstable grease, of the type herein described, does not result from use of the resultant colloidal carbonate. Further, unless said water is throughly mixed with the solution prior to carbonation, we have been unable to produce a colloidal barium carbonate suspension suitable for our present purpose.
Predicated upon these discoveries, the process of our present invention comprises the following steps in sequence:
(a) Barium oxide is first reacted with an excess of anhydrous methyl alcohol to give a clear solution, filtration being employed, if necessary.
(b) A minor proportion of water is then added to the solution, resulting from step (a) and is thoroughly stirred into and mixed with the solution.
Carbon dioxide is then passed into the solution and dissolved therein to convert the barium oxide-methanol reaction product to barium bicarbonates. Upon peptization, as by mildly heating, or permitting the suspension to stand at room temperature for 16 to M hours, a stable colloidal suspension of barium carbonate results.
The foregoing steps (a), (b) and (c) may, with advantage, be carried out under ambient conditions of temperature and pressure, though carbonization under-somewhat higher pressure does not appear deleteriously to affect the characteristics of the resultant suspension. Following the carbonation, the mixture is more advantageously mildly heated with refluxing, usually at about 153 F. for about 15 minutes, until a substantially clear colloidal solution or suspension is obtained.
In carrying out the process, the proportion of barium oxide reacted with the anhydrous methyl alcohol maybe varied somewhat. One may, with advantage, use proportions of barium oxide equivalent to about to about barium, based on the weight of the anhydrous alcohol; however, about 12.5% has generally been found to give most satisfactory results.
The proportion of water added to, and mixed with, the resultant solution of the methanol-barium oxide reaction product, prior to carbonation, has been found to be quite critical. The effective amount of water must be within the range of about 1 to about 4 mols of water per mol of barium present in the solution. For most satisfactory results, the proportion of water should be about 2 mols of water per mol of barium. Using portions of water less than about 1 mol or in excess of about 4 mols per mol of barium has not proven satisfactory.
In the carbonation of the methanol-barium oxide reaction product, substantial anhydrous carbon dioxide may be passed through the solution until no more carbon dioxide will dissolve therein. The molar proportion of carbon dioxide thus dissolved must at least equal the mols of barium present and, preferably, should substantially exceed that amount. We have, by our present methods, succeeded in dissolving 1.9 mols of carbon dioxide per mol of barium present, as against a theoretically possible ratio of 2:1.
Subsequent heating to a temperature of about 153 F. with refluxing, for about one-quarter hour, has been found to result in a stable, substantially clear solution. Peptization of the solution by long standing, though permissible, is not presently commercially practical.
The diameter of the resultant colloidal carbonate particles so produced has been shown by electron microscope examination to be relatively uniform and to fall within the range from about 0.02 to about 0.2 micron.
The following specific examples are included as further detailed illustrations of the invention and should not be construed as limiting the scope thereof.
Example I Barium oxide was reacted with anhydrous methyl alcohol and the solution filtered to give a clear solution containing 11.8% barium. To 433 grams of the resultant reaction solution, there was added 13 grams of water. The mixture was then thoroughly stirred until it was entirely homogeneous. Carbon dioxide gas was then passed into the mixture at ambient temperature and pressure, while periodically weighing the flask, until the molar ratio of the carbon dioxide, thus dissolved, to the barium present in the mixture was 1:1. The resultant mixture, which was slightly hazy, was then heated .to about 153 F. with refluxing for one-quarter hour by which time the solution had become only faintly opalescent.
Example 11 Barium oxide was reacted with anhydrous methyl alco hol and the solution filtered to give a clear solution containing about 12.5% barium. To the resultant reaction solution, there was added 2 mols of water per mol of barium present therein, and the water was thoroughly stirred into the mixture until the mixture was entirely homogeneous. Carbon dioxide gas was then passed into the mixture, as described in the preceding example, until the mixture was saturated with the carbon dioxide and a copious precipitate had formed, the molar ratio of carbon dioxide, thus dissolved, to the barium present in the mixture being 1.9: 1. Upon heating the resultant mixture for approximately one-quarter hour at about 153 'F., with refluxing, a substantially clear solution was obtained.
The colloidal suspensions produced in accordance with the foregoing examples have been successfully used in the production of stable lubricating greases by mixing the carbonate suspension, a petroleum lubricating oil 'raction and a saturated, straight chain fatty acid in various proportions and heating the mixture to drive off the methanol and water and effect saponification of the fatty acid.
For example, the suspension resulting from Example I, stearic acid and a solvent refined naphthenic oil, having 9. SUV at 210 F. of 58 seconds, have been used in the following proportions:
Parts by weight Carbonate suspension 22 Petroleum oil 21 Stearic acid 3 The resultant mixture was heated with stirring over a period of about one hour to a temperature of 190 C. A gel was observed to form shortly afterthe methanol began coming off and the mixture became thicker and more crumbly as the temperature increased. Upon cooling, the resultant crumbly mass was milled to a soft pliable grease.
At ambient temperature, the resultant milled grease exhibited good mechanical stability, both. dry and in the presence of water, and was found to maintain its grease structure at temperatures as high as 250 C. The grease was found to pass the four-ball weld test at a loading of within the range of kilograms, thus showing improved ex-treme pressure properties.
Barium greases having comparable softening points and similarly prepared, except that conventional barium carbonate is used instead of the colloidal suspension of the present invention, have been found to have a four-ball weld test value not exceeding 120 kilograms and to exhibit excessive oil leakage when subjected to the A.S.T.M. wheel hearing test.
The four-ball weld tests, referred to above, were carried out in accordance with the procedure and equipment described in Method 6503 of Federal Test Method Standard No. 791.
Though the invention has been particularly described and illustrated with reference to grease manufacture, it will be understood that the utility of the invention is not restricted to the manufacture of grease but includes other uses where a stable colloidal suspension of barium carbonate is indicated.
We claim:
1. Process for producing colloidal suspensions of barium carbonate which comprises the following steps, reacting barium oxide with anhydrous methyl alcohol to form a clear solution containing from about 10% to about barium, based on the weight of the anhydrous alcohol, thereafter adding to and thoroughly mixing with the resultant solution an amount of water within the range of about 1 mol to about 4 mols of water per mol of barium, with stirring to form a homogeneous solution, then dissolving carbon dioxide in the resultant solution in a molar proportion at least equal to the mols of barium present therein and heating the resultant mixture with refluxing until a substantially clear colloidal solution is obtained.
2. Process for producing colloidal suspensions of barium carbonate which comprises the following steps,
reacting barium oxide with anhydrous methyl alcohol, to
form a clear solution containing about 12.5% barium, based on the weight of the anhydrous alcohol, thereafter adding to and thoroughly mixing with the resultant solution approximately 2 mols of Water per mol of barium present, with stirring to form a homogeneous solution, then saturating the resultant solution with carbon dioxide and heating the resultant mixture with refluxing until a substantially clear colloidal solution is obtained.
3. A lubricating grease consisting essentially of a petroleum lubricating oil fraction thickened to a grease consistency with an admixture of a barium soap of -a long chain fatty acid and colloidal barium carbonate, said grease having a four-ball weld test value of at least kilograms.
References Cited in the file of this patent UNITED STATES PATENTS 1,884,082 Miller Oct. 25, 1932 FOREIGN PATENTS 478,187 Great Britain Jan. 10, 1938 790,473 Great Britain Feb. 12, 1958