US2768139A - Lubricating greases from oxo glycols - Google Patents

Description

United States Patent LUBRICATING GREASES FROM oxo GLYCOLS No Drawing. Application October 20, 1952, Serial No. 315,843

12 Claims. (Cl. 252-42) The present invention relates to new lubricating greases. More specifically, the invention pertains to new and. improved lubricating greases having excellent lubrieating properties over a wide temperature range, particularly at extremely low temperatures, and to methods for making such greases.

In brief compass, the invention provides for the manufacture of lubricating greases on the basis of certain glycols. These glycols are the oxonation products of cyclic diolefins, particularly non-conjugated cyclic diolefins, such as butadiene dimers. They are used as such or in the form of their esters with certain dibasic acids as a lubricating oil base for the greases of the present invention.

Prior to the present invention, low temperature greases have been prepared by compounding low boiling mineral oil fractions having low viscosities with metal soaps in grease-making proportions. However, such greases are frequently subjected to relatively high temperatures in normal use. The mineral oil used in making the grease should, therefore, combine low viscosity with low volatility in order to provide efiicient low temperature lubrication and at the same time prevent oil losses at relatively high temperatures. Since most low boiling mineral oils of sufiiciently low viscosity have high volatilitie's, the number of mineral oils suitable for the production of low temperature greases is very limited.

More recently, it has been suggested to use certain synthetic oils, particularly certain esters of dibasic aliphatic acids as an oil constituent for low temperature greases. While greases containing these esters have highly desirable lubricating qualities as well as excellent high and low temperature characteristics, many of these esters are easily hydrolyzed. The soap and the grease, therefore, must be made in separate stages. In addition, the available raw materials are rather limited. In view of the rapidly increasing demand for greases having utility over a wide range of temperatures, a broadening of the raw material basis is highly desirable.

It has now been found that certain glycols and some of their esters may be substituted for low boiling mineral oil fractions and synthetic oils of the type described above in the production of low temperature greases. In accordance with the preferred embodiment of the invention, the glycols used have substituted alicyclic hydrocarbon radicals with at least two non-conjugated olefinic linkages, one of. which is in a ring, and containing 5-30, and preferably 10-20 carbon atoms. These glycols have excellent lubricating qualities and combine relatively high boiling points with desirably low pour points, high flash points, low viscosity-temperature coefficients and high chemical stability.

The preferred glycols of the invention may be obtained by subjecting cyclic diolefins, particularly non conjugated cyclic diolefins to oxonation i. e. to a reaction with CO and H2 in the presence of carbonylation catalysts, followed by hydrogenation of the product so obtained. In particular, cyclic compounds having one olefinic linkage in the ring and one olefinic linkage either in a side chain or in another ring, are adaptable to the process. Thus, it has been found, for example, that l-vinyl cyclohexene-3 or l-vinyl cyclohexene-4 reacts in the presence of a solvent, with carbon monoxide and hydrogen to give a product which, by hydrogenation, is converted into high yields of glycol containing 10 carbon atoms suitable as such or in the form of certain of its esters, as a lubricating oil constituent of the greases of the present invention. This reaction is accompanied to a certain extent by formation of nonyl alcohols, but is substantially unaccompanied by polymerization and resinification by-products hitherto reported as accompanying and as being the main product in the oxonation of diolefins. Similarly, dicyclopentadiene may be converted by the oxonation or 0x0 process in good yields into a glycol suitable for the purposes of the present invention, with the simultaneous formation of Cii-alcohols.

This process involves the catalytic reaction of the diolefins dissolved in a hydrocarbon solvent, such as hexane or heptane, with carbon monoxide and hydrogen at elevated temperatures of about 225 -400 F. and pressures of about 2000-4000 p. s. i. g., particularly in the presence of cobalt catalysts, to form aldehydes having 2 carbonyl groups added to the diolefin originally used. The aldehyde is catalytically hydrogenated to the corresponding glycol. Minor proportions of lower boiling monohydric alcohols are formed as by-products. The total hydrogenation product is subjected to distillation to remove the monohydric alcohols and to recover the glycol as overhead product. The distillation residue, i. e., the so-called Oxo-bottorns, is rich in by-product alcohols of higher molecular weight.

While the exactcomposition of all these glycols and alcohols is not known, it is well established that they are mixtures of primary alcohols. At least a substantial proportion of the monohydric alcohols is of the branchedchain type. The overhead glycol product consists of a mixture of glycols averaging 2 carbon atoms more than the olefin originally fed to the Oxo synthesis. It has been found that these glycols, particularly those containing at least 5, and preferably 10-20, carbon atoms have greatest utility for manufacturing greases in accordance with the present invention.

For example, the oxonation product of butadiene-l,4 dimer has the composition and properties listed below which give it excellent utility as a grease base.

Composition: Percent C 70.1 H 11.9 0 18.0 Properties:

Boiling Range, C.:

at 3.1-3.3 mm. Hg 153.5-l56.9 at 760 mm. Hg 305-317 Density, g./cc. at 25 C. 1.0 Refractive Index N 1.4890

The product also has a desirably high flash point and low pour point as well as satisfactory viscosity characteristics.

Oxo-glycols of this type and the process of producing the same are described in greater detail and claimed in the copending Staib and Stewart application, Serial No. 236,234, filed July 11, 1951, now U. S. Patent No. 2,738,- 370, and assigned to the assignee of the present application. Said copending application is here referred to for specific details of the process of producing the x0- glycols.

As indicated above, certain esters may be derived from these Oxo-glycols which have likewise excellent lubricating oil characteristics which render the same suitable for the preparation of greases in accordance with the invention. These esters include the products obtained by esterifying C-C3u Oxo-glycols with 2 mols of a mono-basic fatty acid having 2-10 carbon atoms per molecule, such as acetic acid, propionic acid, the butyric acids, various C5 acids, caproic acid, etc. Quite generally, it may be stated that acids suitable for the production of 0x0- glycol esters having desirable lubricating oil characteristics and particularly flash points of at least 350 F. are preferred.

Lubricating greases in accordance with the invention may be prepared by incorporating into these glycols or glycol esters grease-making proportions, say about 540 wt. percent, of suitable metal soaps, preferably alkali metal soaps, such as a sodium or lithium soap or alkaline earth metal soaps particularly calcium soaps of high molecular weight, preferably saturated fatty acids having -30 carbon atoms per molecule, such as stearic acid, hydrogenated fish oil acids, etc., or of a soap-salt complex consisting of the soaps of higher molecular weight fatty acids and the salts of low molecular weight carboxylic acids, such as acetic, furoic, acrylic or similar acids. The metal soap or soap-salt complex is preferably added as such by slurrying the preformed dry soap or complex into the glycol base oil and heating the mixture to 300500 F. while stirring until a homogenous mass is obtained which is cooled to form the finished grease.

When Oxo-glycol esters are used, the grease thickening soap or soap-salt complex may be formed in situ. For this purpose, suitable fatty acids may be mixed with the glycol ester in grease-making proportions and heated to about 100-200 F. A metal hydroxide, preferably caustic alkali, is then added in aqueous solution and in amounts at least sufiicient to neutralize the acids. The mixture is heated to about 300-400 F. until neutralization is completed and the mixture is completely dehydrated. Upon cooling, the grease is finished. For the production of low temperature greases lithium soaps or lithium soap-salt complexes are preferred.

The greases may be further modified by the addition of other lubricating oils, particularly synthetic oils, such as the more readily hydrolyzable esters of dibasic acids, complex esters and others. Other conventional modifying agents may be added to the greases of the invention in a manner known to the art. These include thickeners, such as N-stearyl-p-amino phenol, anti-oxidants, such as phenyl alpha-naphthylamine and phenothiazine, corrosion inhibitors, such as zinc naphthenate or petroleum sulfonate soaps, tackiness agents, such as polybutenes, poly acrylate and poly methacrylate esters, load-carrying compounds, such as sulfochlorinated hydrocarbons or lead oleate or naphthenate, viscosity index improvers, such as polybutenes or poly acrylate esters, etc.

The preferred thickeners for low temperature greases in accordance with the present invention are lithium soaps of hydrogenated fish oil acids or complexes of such soaps with lithium salts of low molecular weight carboxylic acids of the type described above. It may also be desirable to add small amounts, say, about 0.5-5 wt. percent of a stabilizer to these greases to improve their texture and consistency. The oxides, carbonates, or soaps of metals forming amphoteric oxides, such as the soaps of zinc, tin and aluminum, are useful for this purpose.

The invention will be further illustrated by the following specific examples.

EXAMPLE I A Cm-Oxo-glycol was produced by oxonation of butadiene-l,4 dimer as described above. The glycol product is believed to be a mixture of isomers having the standard formulae given below.

where is the hexahydrobenzene ring. This glycol mixture was heated with a dry complex soap to 500 F. while stirring. The product set up to a smooth uniform soft grease upon cooling.

Wt. Percent Ingredients:

Complex soap, Li-hydroiolate Li-acetate, Mole rat 1 5 Hydrocarbon solubil Insoluble. Water solubility Not 5 -ln)lc in colrl or hot water.

Hydrofol acids are hydrogenated fish oil acids having a degree of saturation corresponding to stearic acid.

This lubricant did not attack rubber.

EXAMPLE 11 The Cm-Oxo-glycol of Example i was esterified with 2 mols of caproic acid by heating the mixture of the reactants in the presence of xylene as a diluent and small amounts of sodium bisulfate as the catalyst to 305 62 F. for 10 hours. After stripping to a still temperature of 392 F. at a vacuum of 4 mm. Hg the weight of the residue was 250 g.

For purposes of comparison, glycol-centered complex esters of the same Cm-Oxo-glycol with 2 mols of adlpic acid and 2 mols of Cs-Oxo-alcohol, on the one hand, and 2 mols of adipic acid and 2 mols of Cs-Oxo-alcohol, on the other hand, were prepared in a similar manner. The Ca-Oxo-alcohol was prepared by oxonation of C1 monoolefin polymers in the conventional manner. The C9- Oxo-alcohol was the byproduct alcohol obtained in the production of the Cm-Oxo-glycol used.

The composition and properties of these esters are listed below in Table I. The esters were all made by heating the charge listed below under Composition with g. of xylene as water entrainer.

Table I A B C 172 g. C:G' 1Y(50l 172 g. Clo-Glycol. 172 g. (ho-Glycol. 292 g. Adlpio Ac1d 292 g. Adipic Acid 232 g. Oaproic Acid. I 260 g. Os 0x0 Alcohol. 288 g. Co 0x0 Alcohol 100 g. Xylene. Composition (by-product from 010 glycol Manufacur g. llgllafisglrn ou 3.62 g. NlaHS04 2.0 g. NaHSOr. tigg SE? g. eno 1az1ne 3.62 g. P enothrazme. 2.0 g. Phenothiazmc.

or eating to 392 F. Still 389.2 533 2 Temperature Under 4 mm. 50 Hg. Vac., g. Prorartietsz O s. a 100 F 66.00 106.20-. US. at 210 F 10.31- 12. 05. at 40 F 60,1760 Sol 4,190. Flash, F. 43% 475 395. Pour Point, F 65 -35 70.

The above data show a superiority of the caproic acid ester over the complex ester with respect to low temperature viscosity characteristics.

Ester C prepared as described was converted into a grease by mixing it with a dry complex soap and heating the mixture to a maximum temperature of 510 F. over a period of 3 hours. The molten grease was cooled to 450 F. and poured into pans for further cooling. The cold cakes may be returned to the kettle and worked to a smooth uniform product, filtered and packaged. Cooling may also be finished in the grease kettle while stirring. The composition and properties of the grease were as follows:

The invention is not limited to the specific figures of the foregoing examples. The relative proportions of the materials used may be varied within the limits indicated in the specification to obtain products of varying characteristics.

What is claimed is:

1. The process of making lubricating greases which comprises catalytically oxonating a cyclic butadiene dimer with Hz and CO at elevated temperatures and pressures conducive to the formation of an aldehyde having two carbonyl groups added to said dimer, catalytically hydrogenating said aldehyde to form the corresponding mono-glycol, compounding said glycol with grease-making proportions of a soap-base grease thickener at temperatures of about 300-500 F. while stirring and cooling the grease so formed.

2. The process of claim 1 in which said glycol is esterified with two mols of a monobasic acid having 2-10 carbon atoms per molecule and the ester so formed is compounded with said thickener.

3. The process of claim 2 in which said thickener is formed in said ester by neutralizing soap-forming acids with a metal base in said ester at temperatures of about 300-400 F.

4. The process of claim 1 in which said thickener is formed prior to said compounding.

5. A lubricating grease comprising a minor greasemaking proportion of a grease thickener selected from the group consisting of the alkali metal and alkaline earth metal soaps of carboxylic acids having from 10 to 30 carbon atoms and complexes of said soaps with salts of said metals with lower molecular Weight carboxylic acids and a major grease-making proportion of a lubricating oil selected from the group consisting of monoglycols having 5 to 30 carbon atoms per molecule obtained by the catalytic oxonation of an alicyclic compound having two non-conjugated olefinic linkages, one of which linkages is in a ring, with carbon monoxide and hydrogen at temperatures of about 225 to 400 F. and pressures of about 2,000 to 4,000 p. s. i. g. followed by catalytic hydrogenation of the oxonation product; and diesters of said monoglycols with monobasic carboxylic acids having 2 to 10 carbon atoms per molecule.

6. A grease according to claim 5 in which said alicyclic compound is a cyclic butadiene dimer.

7. A grease according to claim 5 in which said alicyclic compound is dicyclopentadiene.

8. A grease according to claim 5 in which said alicyclic compound is 1-vinyl cyclohexene-3.

9. A grease according to claim 5 in which said alicyclic compound is l-vinyl cyclohexene-4.

10. A lubricating grease according to claim 5 in which said diesters have a flash point not lower than 350 F.

11. The lubricating grease according to claim 5 in which said monobasic carboxylic acid is caproic acid.

12. A lubricating grease according to claim 5 in Which said thickener is a soap-salt complex consisting of lithium soaps of hydrogenated fish oil acids and lithium acetate in a mol ratio of 1:1.

References Cited in the file of this patent UNITED STATES PATENTS 1,982,198 Brunstrum et al. Nov. 27, 1934 2,575,195 Smith Nov. 13, 1951 2,575,196 Smith Nov. 13, 1951 2,576,032 Morway et al. Nov. 20, 1951 2,589,973 Smith et al. Mar. 18, 1952 2,612,473 Morway et al. Sept. 30, 1952 2,628,974 Sanderson Feb. 17, 1953 2,639,266 Dilworth et a1 May 19, 1953 2,652,361 Woods et al. Sept. 15, 1953 OTHER REFERENCES Wender and Orchin: Critical Review of Chem. of 0x0- Synthesis, Bur. of Mines R. I. 4270, pp. 6 and 9, June 1948.

Claims (1)

1. 5. A LUBRICATING GREASE COMPRISING A MINOR GREASEMAKING PROPORTION OF A GREASE THICKENER SELECTED FROM THE GROUP CONSISITN OF THE ALKALI METAL AND ALKALINE EARTH METAL SOAPS OF CARBOXYLIC ACIDS HAVING FROM 10 TO 30 CARBON ATOMS AND COMPLEXES OF SAID SOAPS WITH SALTS OF SAID METALS WITH LOWER MOLECULAR WEIGHT CARBOXYLIC ACIDS AND A MAJOR GREASE-MAKING PROPORTION OF A LUBRICATIONG OIL SELECTED FROM THE GROUP CONSISTING OF MONOGLUCOLS HAVING 5 TO 30 CARBON ATOMS PER MOLECULE OBTAINED BY THE CATALYTIC OXONATION OF AN ALICYCLIC COMPOUND HAVING TWO NON-CONJUGATED OLEFINIC LINKAGES, ONE OF WHICH LINKAGES IS IN A RING, WITH CARBON MONOXIDE AND HYDROGEN AT TEMPERATURES OF ABOUT 225* TO 400* F. AND PRESSURES OF ABOUT 2,000 TO 4,000 P. S. I. G. FOLLOWED BY CATALYTIC HYDROGENATION OF THE OXONATION PRODUCT; AND DIESTERS OF SAID MONOGLYCOLS WITH MONOBASIC CARBOXYLIC ACIDS HAVING 2 TO 10 CARBON ATOMS PER MOLECULES.