US 3239463 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
United States Patent 3,239,463 LUBRICATING OIL COMPOSITION Edwin C. Knowles, Poughkeepsie, N.Y., and Edward L. Kay, Akron, Ohio, assignors'to Texaco Inc, New York, N.Y., a corporation of Delaware No Drawing. Filed Mar. 24, 1965, Ser. No. 442,472 6 Claims. (Cl. 252-331?) This application is a continuation-in-part of now abandoned application S.N. 83,182.
This invention relates to a lubricating oil composition characterized by having outstanding load-carrying properties. More specifically, the invention relates to a lubricating oil containing a tertiary alkyl primary amine salt of a tetra-covalent boron acid.
Lubricating oil compositions containing certain 'organoboron compounds have been formulated heretofore. Amine salts of acid compounds of boric acid and of borodiol complexes have been employed in lubricating oils to improve resistance to sludge-formation and to improve anti-corrosion properties, see US. Patent Nos. 2,497,521 and 2,568,472. Bora'te esters have also been employed in lubricating oils but their use has been seriously hindered by their hydrolytic instability.
The present invention is concerned with lubricating oil compositions containing tertriary alkyl primary amine salts of tetra-covalent boron acids known as chelate type salts which are represented by the following general formulae:
wherein R is a monovalent tertiary aliphatic hydrocarbyl radical having from to -24 carbon atoms, R is a divalent aryl or alkaryl radical having 6 to 24 carbon atoms and R is a divalent aryl or alkaryl radical having 6 to 24 carbon atoms or an aliphatic hydrocarbyl radical having 2 to 4 carbon atoms. The acid-amine salt is present in the lubricating oil in a concentration range from above 0.5 to 5.0 weight percent an amount effective to impart load-carrying properties.
The amine salts for the present invention are prepared by the reaction of boric acid with a polyhydroxy compound or hydroxy carboxylic acid to form the tetra-covalent boron compound which is thereafter reacted with a tertiary aliphatic primary amine. The reaction mixture is diluted with a solvent such as toluene and heated to reflux temperature at normal atmospheric pressure. The solvents are then removed preferably by azeotropic distillation and the amine'salt recovered.
The amines employed in the formation of the salts of the chelated tetra-covalent boron acid" are represented by the formula:
wherein R is a monovalent tertiary aliphatic hydrocarbyl radical having 5 to 24 carbon atoms. Preferably R represents a tertiary aliphatic hydrocarbyl radical having from 11 to 22 carbon atoms. Examples of effective tertiary aliphatic primary amines include t-octylamine, tdodecylamine, and mixtures of primary aliphatic amines such as commercially available mixtures of t-alkyl primary amines. A commercial mixture of monovalent tertiary aliphatic hydrocarbyl amines having 11 to 14 carbon "ice pounds and as such do not exist in the isolated state.
They do, however, form stable salts. The acids are formed by reacting 'boric acid with a polyhydroxy compound or hydroxy carboxylic acid which may be illustrated by the following general equation:
wherein R is 'a divalent aryl or alkaryl radical having from 6 to 24 carbon atoms.
The chelated tetra-covalent boron acids employed in the formation of the amine salts of the present invention can be represented by the following formulae:
wherein R is a divalent aryl or alkaryl radical having 6 to 24 carbon atoms, preferably 6 to 12 carbon atoms, and R is a divalent aryl or alkaryl radical having 6 to 24 carbon atoms or an aliphatic hydrocarbyl radical having 2 to 24 carbon atoms, preferably 4 to 18 carbon atoms. Examples of effective acids are boro catecholate acid, alkyl derivatives of boro resorcinate acid, boro salicylate acid, boro alpha hydroxy decanoate acid, boro beta hydroxy decanoate acid, boro glycolate acid, boro propylene glycolate acid, boro tetramethyl ethylene glycolate acid and boro oxalate acid.
Upon the formation of the transistory acids, described above the amine is reacted therewith to obtain the desired amine salt, the reaction for which may be illustrated by the following general equation:
wherein R is a monovalent tertiary alphatic hydrocarbyl radical having 5 to 24 carbon atoms and R is a divalent aryl or alkaryl radical having 6 to 24 carbon atoms.
The effective amine salts are illustrated by the following: t-C C alkyl primary amine boro catecholate, -t-C -C alkyl primary amine boro alkylcatecholate, LC -C alkyl primary amine boro resorcinolate, t-C C alkyl primary amine boro alkylresorcinolate, t-C C alkyl primary amino boro salicylate, t-C C alkyl primary amine boro alkylsalicylate, ec -c alkyl primary amine boro alpha hydroxy decanoate, t-C C alkyl primary amine boro alpha hydroxy alkyldecanoate, ec -c alkyl primary amine boro glycolate, t-'C C alkyl primary amine boro propylene glycolate, t-C -C alkyl primary amine boro tetramethyl ethylene glycolate, ec -c alkyl primary amine boro oxalate, PC -C alkyl primary amine boro catecholate, FO -C alkyl primary amine boro alkylcatecholate, t-C -C alkyl primary amine boro resorcinolate, t-C C alkyl primary amine boro alkylresorcinolate, t-C -C alkyl primary a amine boro salicylate, t-C C alkyl primary amine boro alkylsalicylate,t-C C alkyl primary amine boro alpha hydroxy decauoate, t-C C alkyl primary amine boro alpha hydroxy alkyldeconoate, t-Cm-C alkylprimary amine boro glycolate, PC alkyl primary amineboro propylene glycolate, vo -cs alkyl primary amine boro tetramethyl ethylene glycolate, tC C alkyl primary amine boro oxalate, t-octyl amine boro catecholate, t-octyl amine boro alkylcatecholate, t-octyl amine boro resorcinolate, t-octyl amine boro alkylresorcinolate, t-octyl amine amine boro alpha hydroxy decanoate, t-octyl amine boro alpha hydroxy alkyl decanoate, t-octylamineboro gly'-.. colate, t-octyl amine boro propylene glycolate, t-octyl;
amine boro tetramethyl ethylene glycolate, and t-octyl amine boro oxalate.
The concentration of the tertiary alkyl primary amine salt of a tetra-covalent boron acid of the invention in a lubricating oil composition is. critical. Generally,.a concentration ranging from above 0.5 percent by weight to i from hydrocarbonsynthetic ilubricating oilbases. The.
- hydrocarbon oils found, to be useful for this invention include oils. having a viscosity in the .rangerequired for lubricating fluids and in particular hydrocarbon mineral oils which include parafiinzbase, naphthene base, mixed 1 paraflinnaphthenebase and mineraloilsiof the residual or distillate type The hydrocarbon lubricating base gener- '10 boro salicylate, t-octyl amine boro alkylsalicylate, t-octyl 5.0 percent by weight is essential to impart load carrying EXAMPLE I.-PREPARATION OF CHELATE AMINE BORO SALT OF SALICYLIC ACID 123.6 grams, 2.0 mols of boric acid, 552 grams 4.0
mols, sali cylic acid and 500 mls. of benzene were refluxed and the Water of the reaction removed by azeotropic distillation. Thereafter 400 grams, 2.0 mols of a mixture oft-alkyl primary'amine wherein the t-alkyl radical contains 11 to 14 carbon atoms .was added to the reaction mixture. The pot temperature rose from 75 C. to 85 C.
Q has been found eifective and are generally incorporated After-stripping solvents to a pot temperature of 150 .C., 944 grams of clear viscous t-C -C primary amine boro salicylate liquid were isolated and at ambient tempera-- ture the reaction product solidified.
EXAMPLE II.PREPARATION OF 'CHELATE AMINE BORO SALT OF 'ALPHA-HYDROXY DECANOIC ACID 61.8 grams, 1.0 mol of boric acid, 200 mls..of toluene and 376 grams, 2.0 mols, of alpha hydroxy decanoic acid were refluxed and 46 mls. of water were removed by azeotropic distillation. The toluene was stripped 'at "a pot temperature of 195 C. Uponthe addition of..195 grams, 1.0 mols of amixture of t-alkyl primary amines 'wherein the t-alkyl groups contained 11 'to 14 carbon atoms mixture, the pot temperature rose from 50 C. to 92 C. 350 mls. of pentane were added to the reaction mixture and the solution was filtered. Pentane was re-' moved by heating the product and 558 grams of-clear amber t-C -C primary amine boro alpha hydroxw decanoate liquid were isolated.
EXAMPLE III.-PREPARATION OF CHELATE: AMINE BORO SALT OF CATECHOL" 61.8 grams, 1.0 mol of boric acid, 220 grams, 2.0 mols of catechol and 200 mls. of toluene were refluxed and 51 mols of water were isolated by azeotropic distillation. Solvents were strippedto a pot temperature of 170 0.
Upon cooling to room temperature a solid separated.-
195 grams, 0.1 mol of a mixtureof t-alkyl primary amine wherein the t-alkyl groups contained 11 to, 14 carbon atoms mixture were added and the pot temperature roseally has-been subjected to solvent refiningto improve its oxidation and thermal stability and viscosity-temperature properties asswell as solv'ent dewaxingto remove vwaxy components and .to improve the-pour. properties: of :the
oil. Broadly speaking,ihydrocarbon lubricating oils having an SUSviscosity at;l00 Fiof between-5010 :2500 are vus'edini'thei formulation'of the improved lubricants:
of this invention; V
The minerallubricating oils to designed to impart-desirableg: properties thereto. For example, viscosity, index improvers, such as the 'polymeth-f acrylates having .a molecular weight ranging from 500 to 25,000 are usually included .therein'.: The improver having the following normally used is a polymethacrylate recurring structural unit: I
wherein R is an aliphaticradical ranging from'butyl to stearyl andxn is an integer of morethan -l.
The use of various metal? baseforganic type additives in the lubricating oils of this invention, particularly those:
oils used in high speed, spark ignition and diesel engines to reduce ring. sticking, minimize carbon deposits.
lacquer. formation and- The hydrocarbon lubricating oils of this invention may:
also contain other additives such as metal ,sulfonatesto afiord additional detergent-dispersant properties, metal,
dialkyl dithiophosphates to afford additional. corrosion and oxidation resistance, and anti-foam agents such as silicone polymers in the amount of'about 5 to. 200 parts per million, etc.
from 60 C. to 'C. A water bath was then used-to cool the mixture. Some solids were still presentin the reaction mixture and thereafter 500 mls. of pentane were added. The mixture was filtered and stripped of pentane. 391 grams of dark amber t-alkyl C C amine boro catecholate liquid were isolated.
The lubricating oils of this invention are prepared,
The esters which constituted the synthetic lubricant composition of this invention are broadly described as;
They are. high esters "of hydrocarbyl carboxylic acids. molecular weight'materials of lubricating oil characteristics derived from alcohols which are ;usually aliphatic; alcohols containing 1 or more, hydroxyl radicals and monocarboxylic acids which are usually aliphatic-canboxylic 'acids containing 1 or; more carboxylic acid radicals.
Widely used synthetic ester lubricants arealiphatic diesters of aliphatic dicarboxylic acids containing 6 to 12 L carbonatoms. From the standpoint of cost and availability, the preferred dibasic acidsrare adipic acid, sebacic acid and azelaic acid. The aliphatic-alcohols used to form the diesters usually contain at :least 4 carbon atoms and up to 20m more carbon atoms. C to C alcohols are most commonly used. Ether alcohols such as Cellosolve and Carbitol may also beused inthe formation of the aliphatic diesters of organic dicarboxylic acids used as the lubricating base in-the compositions ofthis invention. Alcohols containing 2 for more hydroxyl radicals and no hydrogen substituted: on ;the beta carbon atom such as trimethylol. propane. and .pentaerythritolhave .proven particularly elfective in formulating stable high temperature .ester lubricants.
Examples of alkyl esters-of aliphatic carboxylic. acids are the following; difisooctyl .azelate, di-2-ethylhexyl.v sebacate, di-2-ethylhexy1 azelate, di-Z-ethylhexyl adipate,
dilauryl azelate, di-sec-amyl sebacate, di-2-ethylhexyl alkenyl-succinate, di-Z-ethoxyethyl sebacate, di-2-(2,--
methoxy-ethoxy) ethyl Tsabacate, di-2- (2-ethylb;utoxy) ethyl sebacate, di-Z-butoxyethyl azelate, di-2-(2'-ibutoxywhich the amine salts of this invention are added usually contain other additives 7 ethoxy) ethyl alkenyl-succinate, pentaerythritol tetracaproate and trimethylol propane tri-isooctanoate.
In addition to such esters, polyester lubricants formed by a reaction of an aliphatic dicarboxylic acid, a dihydroxy compound and a monofunctional compound, which is either an aliphatic monohydroxy alcohol or an aliphatic monocarboxylic acid, in specified mol ratios are also employed as the synthetic lubricating base in the compositions of this invention; polyesters of this type are described in U.S. 2,628,974 on Polyester Synthetic Lubricants, which issued to R. T. Sanderson on February 17, 1953. Polyesters formed by reaction of a mixture containing specified amounts of 2-ethyl-1,3-hexanediol, sebacic acid, and 2-ethylhexanol and by reaction of a mixture containing adipic acid, diethylene glycol and 2- ethylhexanoic acid illustrate this class of synthetic polyester lubricating bases.
The sulfur analogs of the above-described esters are also used in the formulation of the lubricating compositions of this invention. Dithioesters are exemplified by di-Z-ethylhexyl thiosebacate, di-n-octyl thioadipate and the dilaurate of 1,5-pentanedithiol; sulfur analogs of polyesters are exemplified by the reaction product of adipic acid, thio glycol and 2-ethylhexyl mercaptan.
Alkyl-substituted phenols are usually incorporated in the lubricants of the invention as anti-oxidants. The preferred and most commonly used alkyl phenol antioxidants is 2,6-di-tertiary octylphenol; 2,6-di-tertiary amyl-4-methylphenol; and 2,6-di-isopropyl-4-methylphenol. Hindered phenols of this type are employed in concentrations between 0.1 and 1.0 weight percent.
Although hindered phenol type anti-oxidants are the most widely used anti-oxidants in the lubricant compositions of the invention, aryl-substituted amine anti-oxidants such as phenylnaphthylamine, phenylene diamine, and diphenylamine are also used in lubricants in conjunction with the extreme pressure additive of the invention. The amine anti-oxidants are employed in the same concentrations as the hindered phenol anti-oxidant.
Organic silicones are normally incorporated in the lubricants of the invention to impart thereto anti-foam properties. The silicones are usually of the d-ialkyl or mixed alkyl-aryl silicone type. Dimethyl silicone is normally employed as the anti-foam agent. The silicone is incorporated in the lubricant by means of a kerosene concentrate containing 5 to 15 weight percent silicone. A very satisfactory anti-foam agent is a kerosene concentrate weight percent dimethyl silicone. The kerosene concentrate is employed in an amount sufiicient to provide a silicone polymer concentration of from 50 to 250 parts per million based on the total lubricant composition.
To demonstrate the excellent improvement in the loadcarrying ability of lubricating oil containing the amine salts of the present invention, high speed gear scuff test was used. This test is called the LAB. Gear Test and is intended for the evaluation of the load-carrying ability of the scuff limited load-carrying ability of those lubricants used in reduction and accessory drives of turbo-jet and turbo-prop engines. The I.A.E. Gear Test is one of the requirements of the British specification D.E.R.D. 2,487 Lubricating Oil, Aircraft Turbine Engine, Synthetic Type. The I.A.E. Gear Test is also designed to evaluate the scuti limited, load-carrying ability of aircraft gear hydrocarbon lubricants.
The results of the I.A.E. Gear Test on lubricating oil compositions of the present invention are set forth in the following tables:
Table 1.l.A.E. gear test Oil:
Base oil B consisted of a paraffin base crude which has been furfural refined, lightly acid treated, clay contacted and solvent dewaxed and has an SUS viscosity at F. of 150.
The criticality in the concentration of the additive as well as the load-carrying properties of a synthetic lubricating oil composition are demonstrated by the results given in Table II. Base oil C, which was employed in these tests, was di-Z-ethyl hexylsebacate, a synthetic oil of lubricating viscosity.
Table II.I.A.E. gear test Tooth loadpounds Blend: 2000 sl'bglg. test Base oil C 50,60 Base oil C plus 0.1% PO -C primary amine 'borosalicylate 50 Base oil C plus 0.25% ec -c primary borosalicylate 60 Base oil C plus 0.5% EC -C primary amine borosalicylate 80 Base oil C plus 2.0% tC C primary amine borosalicylate The foregoing results show that significant load-carrying properties begin when the concentration of the additive is above 0.5 percent by weight, lesser amounts of the additive producing no improvement in load-carrying properties over those of the base oil itself.
In addition to the load-carrying properties, the amine salts of the chelated tetra-covalent boron acids of the invention also impart a high degree of oxidation and corrosion resistance to lubricating oil compositions. Many organo borate compounds do not perform as satisfactory additives for lubricants because of their hydrolytic instability. In this respect, the salts of the present invention have another improtant advantage, namely that the amine salts of the chelated tetra-covalent boron acids are hydrolytical'ly stable in both water and lubricating oils.
1. A lubricating oil containing above 0.5 to 5 percent by weight of an amine salt of a tetra-covalent boron acid, said amine salt having the formula:
wherein R isa monovalent tertiary aliphatic hydrocarbyl radical having from 5 to 24 carbon atoms and R" is selected from the group consisting of divalent aryl and alkaryl radicals having from 6 to 24 carbon atoms.
2. A lubricating oil as described in claim 1 wherein R is a mixture of monovalent tertiary aliphatic hydrocarbyl radicals having from 11 to 14 carbon atoms.
3. A lubricating oil as described in claim 1 wherein R is a mixture of monovalent tertiary aliphatic hydrocarbyl radicals having from 18 to 22 carbon atoms.
4. A lubricating oil composition according to claim 1 in which said amine salt is present in a concentration of from 0.6 to 2.0 weight percent.
5. A lubricating oil as described in claim 1 containing above 0.5 to 5.0 weight percent of an amine salt having the formula:
wherein R is a mixture of tertiary alkyl groups having from 11 to 14 carbon atoms.
vwherein R is a mixture of tertiary alkyl groupsbhaving 6.: A lubricating oil as described in claim 1 containing: I References (literd by the rExaminer."v
above 0.5 to 5.0 weight percent of an amine'sa'lt having I "UNITED -1. P
from 11 to 14 carbon atoms.