US 2497521 A
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eteni Feb. l4, l9
on. ooosrrrons comma a SALTS 0F BORO-DIOL COMPLEXE Charles E. Trautman, Cheswick, Pa, assignor to Gulf Research & Development Company, Pittsburgh, Pa, a corporation of Delaware No Drawing. Application December 3, 1947, Serial No. 789,569
12 Claims. 3
This invention relates to oil compositions, and n particular concerns new hydrocarbon oil com- Jositions having improved stability characterisics. including improved resistance to sludge- :ormation and improved anti-corrosion properdes.
It is well known that hydrocarbon oils, par- ;icularly those of mineral origin, have a tendency ao deteriorate and form sludge-like deposits when tllOWEd to stand over long periods of time at moderately elevated temperatures, or in a relaively short time under service conditions such is those encountered in modern intern-a1 comillStlOD. engines. This type of deterioration is atributed to the oxidation of certain of the hydro- :arbons present in such oils. It is also known hat such oils tend to promote corrosion of metal \urfaces, particularly alloy bearing surfaces, with which they come in contact during service. This ype of corrosion is in many cases believed to be we to the presence of oxidation products formed ry deterioration of theoil rather than to comonents of the oil itself.
It is an object of the present invention to pro- -ide oil compositions having improved resistance 0 deterioration and sludge-formation.
Another object is to provide oil compositions laving improved anti-corrosive properties, paricularly with respect to alloy bearings.
A further object is to provide oil compositions I raving improved service characteristics.
A still further object is to provide means for mproving the general stability characteristics of lydrocarbon oils without detracting from their cad-carrying and lubrication qualities.
Other objects will be apparent from the fol- )wing detailed description of the invention, and arious advantages not specifically referred to ierein will occur to those skilled in the art upon mployment of the invention in practice.
In accordance with the above and related obects, I have found that the amine salts of boroiol complexes are excellent stabilizing agents or hydrocarbon oils, and that compositions comrising hydrocarbon oils normally subject to dearioration through oxidation or other means and relatively small amounts of such amine salts have greatly improved resistance to sludge-formation and other manifestations of deterioration, including a tendency to promote corrosion of bearing alloys and the like. This improvement is secured with no loss of load-carryingqualities, and in fact in certain instances the general lubrication characteristics are improved. The variousamine salts differ among themselves as to their" degree of effectiveness in imparting one or more desirable properties to the compositions. For example, certain of such salts may be particularly efl'ective in reducing sludge-formation, whereas others may be more efiective in inhibiting hearing-corrosion. Others may secure one or both of these benefits and in addition improve lubrication properties. In general, however, all of such salts act as stabilizing agents to improve the resistance of hydrocarbon oils to deterioration during storage or service. Accordingly, the oil compositions provided by the invention are particularly suited to use as lubricants in internal comdrastic deterioration conditions. They are also useful as heat-transfer media and the like, e. g.,
transformer oils, where it is desired to maintain a high degree of resistance to sludging over long periods of time. I
The amine salts which are employed as stabilizing agents in the oil composition provided by the invention are obtained by the direct addition of an organic amine to a boro-diol complex. The latter complexes are formed by reaction between boric acid and an organic compound containing at least two hydroxyl groups, e. g., ethylene glycol. The nature of the reaction and the configuration of these complexes are not known with certainty, although in some instances structural formulae have been proposed. In general they are believed to be chelate-type compounds containing the wherein R represents the residue oi the dihydroxy compound. The present invention, however, is in no way limited by any theory concerning the structure of the boro-diol complexes whose amine salts are employed as stabilizing agents in the new compositions.
The formation of the boro-diol complexes may be carried out simply lay-heating boric acid with an organic compound containing at least two hydroxyl groups until the theoretical amount of water is evolved from the mixture. The polyhydroxy compounds which may be reacted with boric acid in such manner include both aliphatic and aromatic compounds, 1. e., polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, trimethylene glycol, erythritol, glycerol, triethylene glycol, tetramethylene glycol, etc., and pclyhydric phenols such as catechol, resorcinol, orcinol,
beta naphthohydroquinone, dihydroxytoluene, phenylcatechol, ethylcatechol, etc. They may also be compounds in which one of the hydroxyl groups is part of a carboxyl group, e. g., salicylic acid, glycollic acid, melilotic acid, coumaric acid, and similar hydroxycarboxylic acids, or cyclic compounds such as dihydroxycyclohexane, dihydroxyfuran, etc. I
As previously mentioned, the amine salts which are employed as stabilizing agents in the oil compositions provided by the invention are formed by the direct addition of organic amines to the above-described boro-diol complexes. This reaction may be carried out simply by heating a mixture of the complex and the amine to a suitable reaction temperature until reaction is complete. Usually the optimum reaction temperature will be between about 50 C. and about 200 0., although this range is not critical and temperatures outside this range may be em ployed. If desired, the reaction may be carried out in the presence or" an inert solvent such as water, benzene, toluene, naphtha, etc. Also, if desired, the amine salts may be prepared directly from boric acid and the desired organic amine and polyhydroxy compound without isoiation of the intermediate boro-diol complex by heating a mixture of the three reactants, either under anhydrous conditions as proposed in U. S. Patent 1,975,890 or in the presence of water as disclosed by Boesken et al., Rec. Trav. Chim., 37, 18a (1918).
Any organic amine may be employed in preparing the boro-diol complex salts as just described. As examples of such amines, there may be mentioned aliphatic and cycloaliphatic amines, including alkylolamines, such as methylamine, ethylamine, diethylamine, amylamine, tributylamine, ethanolamine, diethanolamine, triethanolamine, isopropanolamine, trimethylamine, laurylamine, hexadecylamine, ethylenediamine, diethylenetriamine, triethylenetetramine, cyclohexylamine, dicyclohexylamine, tristearylamine, guanidine, etc.; aromatic amines, such as aniline, naphthylamine, methylaniline, diethylaniline, toluidine, phenetidine, diphenylamine, triphenylamine, diaminodiphenylmethane, aminocresol, aminophenol, phenylenediamine, benzidine, amino-diphenyl, aminodiphenyloxide, diphenylguanidine, benzylamine, diphenylethylamine, etc.; and heterocyclic amines, such as pyridine, piperidine, aminobenzothiazole, morpholine,. etc.
The amine salts of the present class are ef- Iective as stabilizing agents for hydrocarbon oils in relatively small. amounts, e. g. from as little as 0.001 per cent by weight up to the limit of their solubility in the oil, which is usually somewhat less than about 0.5 per cent'by weight.
Since it is usually desirable to provide compositions of maximum stability, 1. e., compositions 5 containing a maximum effective amount 01' the stabilizing agent, the new compositions are usuallyprepared by adding the stabilizing agent to the oil in an amount in excess of that soluble .in the quantity of oil taken. After promoting as complete solution as possible through the use 01' agitation and/or heat, the composition is filtered to recover the undissolved stabilizing agent and to insure a homogeneous product. If desired, however, the stabilizing agent may be added to the oil in predetermined amounts lust sufficient to eflect the desired degree of improvement in stability.
In testing and demonstrating the improved stability of the new oil compositions provided by the invention, use may be made of several standard testing procedures. A convenient test of stability ingeneral is the so-called sludge accumulation test, designated as ASTM D670-42T, Method A. Bearing-corrosion tendencies may be determined by the Lauson engine test, and loadcarrying and general lubrication qualities may be determined by the Falex and static coeiiicient of friction tests, respectively. These various tests are described more fully hereinafter.
The following examples will illustrate several ways in which the principle of the invention hasbeen applied, but are not to be construed as limiting the same. All proportions are specified as parts by weight.
nxmmr Preparation of amine salts of bor'o-diol complexes The complex oi. boric acid and ethylene glycol was prepared by heating a mixture of 248. parts (4 mols) of ethylene glycol and 123.6 parts (2 mols) of boric acid in a flask fitted with a mechanical stirrer, thermometer, and reflux water as trap. The flask and contents were initially heated at a temperature of about 100 C. for 1 hour, after which time 100 parts of toluene were added and the heating, was continued at reflux temperature while collecting water in the trap. Approximately 114 parts of water were collected n this manner. When the temperature of the contents of the flask reached about 121 C., the water trap was disconnected and the toluene was distilled off until the temperature reached about 200 C. Upon cooling and standing overnight, the boroethylene glycol complex was obtained as a white powdery solid'having a melting point of about A mixture of 17.1 parts (0.1 mol+30% excess) of the boro-ethylene glycol complex so prepared and 24.1 parts (0.1 mol) of hexadecylamine was placed in a flask and heated at a temperature or about 150 C. for 20 minutes. It was then allowed to cool to about 50 C., and approximately 200 parts of benzene were added. The mixture was then heated at reflux temperature for 1 hour, after which it was cooled and flltered to remove a small quantity'of unreacted complex. The benzene was then distilled off, and the product was dried in a vacuum oven. The hexadecylamine salt of the boro-ethylene glycol complex so obtained was a yellow waxy solid having a. melting point of about 60-69 C.
A number of amine salts of diflerent boro-diol 7 complexes were prepared by the procedure just co Triethalnolamine salt 01 bore-ethylene yco 'Hexadecylamine salt of boromtechol.--
'5 described. The properties of these products are tabulated below:
oi sludge formation one sample was removed and the sludge content determined in the usual man- TABLE I Solubility Product Appearance Ether Hexane Benzene Alcohol gfi Yellow waxy solld.
Hexadecylamiue salt of bore-ethylene cygigfi l rylamine salt of bore-ethylene Brown waxy solid Brown semi-liquid.
'Ian powder Brown viscous liquid Tan solid Triethanolamine salt of boro-catechol... Hexadecylamine salt or barb-salicylic acid.
Trieitianolamine salt of bore-salicylic Hexadecylamine salt of bore-propylene glycol.
Hexadecylamine salt of boro-trimethyl- Brown solid Brown waxy solid..-
Yellow waxy solid. one given Triethanolamine salt of boro-trimethyl- Brown semi-liquid.
1 Solubility: l=lnsoluble; S=Soluble; S1. S.=Slightly Soluble; V. S.==Very Soluble; S. H.==Soluble Hot.
EXAMPLE II Sludge accumulation tests Compositions were prepared comprising certain of the boro-diol complex amine salts set forth in Example I and a mineral oil base having the ner. The test was continued with samples being withdrawn and sludge determinations made at intervals of time depending upon the apparent rate of sludge formation. When all five samples had been used up in this manner, a curve was plotted of the amount of sludge formed versus following specifications: 30 time. The time required for formation of 0.1 Gravity 0 API 2&0 per cent by Weight of sludge was read from this viscosity F SUV 5 curve and taken as a convenient value for comviscosity F" s v 5 parison purposes. The rate of sludge formation Flash point a F 275 35 was determined from the slope of the curve. The Fire point, F 310 results of the tests carried out in this manner are Neut. No 0.01 tabulated below:
TABLE II Stabilizing Agent Rate of gg f Sludge Forby Identity g; Qtlf mt1n'%/Day Sludge, Days None (Base oil alone) 0.0 0.010 10 Triethanolamine salt of bow-ethylene glycol. 03 0.008 34 Hexadecylamine salt of boro-catechol 0. 3 0. 0035 34 Triethanolamine salt ofboro-catechol o.3 0.0015 60 (est.) 'Iriethanolamine salt of boro-trimethylene glycol 0.3 0.0035 38 Triethanolamiae salt of boro-trunethylene yc 0.001 0.0095 12 'Iriethanolamine salt of borosalicyiic acid." 0. 0. 001 43 Triethanolamine salt of borosalicylic acid." 0.001 0.010 14 Triethanolamine salt of boro-propylene glycol 03 0.003 38 1 Composition was prepared by dissolving the given amount of stabilizing agent in the base 0 Each of the compositions was prepared by adding 0.3 per cent by weight of the amine salt to the base oil, after which the mixture was warmed and stirred to promote solution. The composition was then filtered to remove any of the amine salt which had not dissolved in the oil. Each of the compositions so prepared was then subjected to the sludge accumulation test, ASTM D670-42T, Method A, as described in ASTM Standards on Petroleum Products and Lubricants, December 1946, modified as follows: Instead of subjecting three samples to the test and determining the amount of sludge formed at the end of the three given periods of time, five samples of each composition tested were placed in the apparatus. After starting the test, the samples were examined from time to time and at the first evidence EXAMPLE III Lauson engine tests Compositions comprising three of the amine salts set forth in Example I and a mineral lubrieating oil were prepared as described in Example II. The base oil employed was a highly parafllnic lubricating base having the following specifications:
These compositions were tested for bearing-corrosion tendencies in the crankcase of a standard 7 single-cylinder Lauson engine equipped with a copper-lead bearing and operated under the fol- -lowing conditions (L-4 prototype procedure):
Water-jacket temperature, F 2l0- '-2 Oil temperature, F 280:2 Load, H. P 1 Oil charge, ml 183 Air/fuel ratio 14.5:1.- -0.2 Speed, R. P. M 1820110 After 4 hours of operation and at the end of each alternate 8-hour period thereafter, 23 ml. of fresh oil were added to the crankcase. At the end of the first 8-hour running period and. after each accumulative 8-hour period thereafter, 10 ml. of the oil were withdrawn from the crankcase, the crankcase volumewas corrected to 160 ml. and 23 ml. of fresh oil were added. The copper-lead bearing was examined after each 8-hour period, and at the end of 40 hours was weighed to determine the loss of weight. The piston was also examined at the end of 40 hours for evidence of varnish formation and was compared with a set of prepared standards and given an arbitrary varnish rating value ranging from 10 (no varnish formed) to (very heavy varnish formation). The results of these tests are tabulated below:
Load-carrying and lubrication tests In order to determine the load-carrying and lubrication qualities of the new compositions provided by the invention, a number of the compositions were subjected to suitable tests. Loadcarrying properties were tested by the standard Falex seizure test employing steel V-blocks and steel pins. After a 3-minute break-in period at 300 1bs. jaw load, followed by a 1-minute period at 500 lbs. load, the load was increased in increments of 250 lbs. with one minute running time until failure occurred. The load at failure is a measure of the load-carrying properties of the composition under test. A measure of the lubrication properties of the new compositions was obtained by a determination of the static coefilcient of friction at room temperature on a modifled Herschel-type machine employing steel balls on a steel .race. The results of these tests are tabulated beW TABLE IV Stabilizing Agent Falex Static P t 05d at good. of er can a ure, riction Identity by Wt lbs None (Base Oil alone) 1, 000 0. 29 Triethanolamine salt of borocatechol 0. 2 1, 500 0. 22 Hexadecylamine salt of boroethylene glycol 0. l 1, 000 Hexadecylamine salt of borotrimethylene glycol 0. 2 1, 250 0. Tricthanolamine salt of borotrimethylene glycol 0. 2 1. 250 Hexadecylamine salt of bore-salicylic acid 0. 2 1, 000 0. 21 Hexadecylamine salt of boropropylene glycol 0. 2 1, 250
While the preceding examples illustrate the preparation and properties of compositions consisting only of a hydrocarbon oil base and a boro-diol complex amine salt stabilizing agent, it is to be understood that the compositions provided by the invention may contain other additive agents, e. g., pour point depressants, antifoam agents, viscosity index improvers, detergents, extreme pressure agents, etc. They may also contain corrosion inhibitors of the type which is effective against corrosion in the presence of water or water vapor. Similarly, the base oil employed may be derived from various types of stocks, e. g., parafl'lnic, naphthenic, or asphaltic stocks, or blends thereof, as well as from synthetic hydrocarbon oils, and may be of various degrees of refinement. They may vary widely in physical characteristics depending upon the use to which theyare to be put.
Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the methods or ingredients employed, provided the products defined by the following claims be obtained.
1. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent by weight of the composition of an amine salt of an acid compound of boric acid and a member selected from the group consisting of glycols and polyhydroxy benzenes.
2. A composition of matter consisting essentially of a major proportion of a. hydrocarbon oil and a minor proportion of an amine salt of an acid compound of boric acid and a member selected from the group consisting of glycols and polyhydroxy benzenes, said amine salt being present in an amount ranging from about 0.001 per cent by weight to the limit of its solubility in said oil.
3. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent by weight of the composition of an amine salt of an acid compound of boric acid and a glycol.
4. A composition of matter in accordance with claim 3 in which said glycol is ethylene glycol.
5. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent by weight of the composition of an amine salt of an acid compound of boric acid and a polyhydroxy benzene.-
6. A composition of matter in accordance with claim 5 in which said polyhydroxy benzene ls catechol.
7. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent by weight of the composition of an aliphatic amine salt of an acid compound of boric acid and a member selected from the group consisting of glycols and polyhydroxy benzenes.
8.v A composition of matter consisting of essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent by weight of the composition of an alkylolamine salt of an acid compound of boric acid and a member selected from the group consisting of glycols and polyhydroxy benzenes.
9. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent by weight of the composition of an aliphatic amine salt of an acid compound of boric acid and a glycol.
10. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent by weight of the composition of an aliphatic amine salt of an acid compound of boric acid and a dihydroxy benzene.
11. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about' '0.5 per cent by weight of the composition of the hexadecylamine salt of an acid compound of boric acid and ethylene glycol. I
12. A composition of matter consisting essentially of a major proportion of a hydrocarbon oil and between about 0.001 and about 0.5 per cent 10 by weight of the composition of the triethanolamine salt of an acid compound of boric acid and catechol.
CHARLES E. TRAUTMAN.
REFERENCES CITED The following references are of record in the file of this patent: