US3501413A - Phosphosulfurized partial ester-partial metal salts of unsaturated dicarboxylic aliphatic acids and lubricating oils containing the partial ester-partial salts - Google Patents

Description

United States Patent PHOSPHOSULFURIZED PARTIAL ESTER-PARTIAL METAL SALTS 0F UNSATURATED DICARBOX- YLIC ALIPHATIC ACIDS AND LUBRICATING OILS CONTAINING THE PARTIAL ESTER-PAR- TIAL SALTS Howard J. Matson, Harvey, Ill., assignor to Sinclair Research, Inc., New York, N.Y., a corporation of Delaware N0 Drawing. Original application May 27, 1966, Ser. No. 553,316. Divided and this application Mar. 6, 1968, Ser. No. 730,968

Int. Cl. Cm 1/48, 3/42 US. Cl. 25232.7 7 Claims ABSTRACT OF THE DISCLOSURE Extreme pressure additives, especially for use in a lubricant composition, are provided comprising the class of materials produced by reacting an unsaturated dibasic aliphatic acid and an alcohol such as an alkanol of 4 to 24 carbon atoms, to obtain a partial ester, followed by subsequent neutralization with a metal oxide, e.g., lead oxide, and then treating with phosphorus and sulfur.

This application is a division of application Ser. No. 553,316, filed May 27, 1966, was abandoned.

The present invention relates to extreme pressure additives and a method for their preparation, and more particularly, is concerned with certain phosphosulfurized materials and metal derivatives thereof useful as additives in lubricants which are required to operate under extreme load conditions.

The need for extreme pressure lubricants and additives for the production of such lubricants is well known. When a lubricating film that separates two moving surfaces is subjected to increased pressure as a result of high load conditions, the lubricant tends to besqueezed out. The compression action of the high loads also tends to cause an increase in the internal heat of the lubricating film, resulting in a thinning out of the film due to its decreased viscosity. This combined squeezing and thin ning of lubricant film permits the metal surfaces to make point contacts and generate friction which augments the heat effect on'the film. Continued movement of the surfaces under these conditions results in high wear and ultimately in seizure and destruction of the surfaces under severe conditions.

It has been repeatedly observed that lubricating oil fractions alone do not have the required film strength to prevent wear and destruction of metal parts which are under high loads. A number of such agents have been found suitable for this purpose in the past, but there is a continuing search for new additives which are more effective or equally elfective at lower cost, since such additives are usually more expensive than the equivalent amount of lubricant base that they replace.

This invention is concerned with certain compounds which, when added in small amounts to base lubricating oils, provide a lubricant composition with improved anti-wear and extreme pressure characteristics. In' general, the compounds of this invention form three classes of extreme pressure agents which can be generally described as follows: Firstly, the class of materials produced by reacting a hydroxy dibasic acid and an ethoxy amine, which is then treated with phosphorus and sul- 3,501,413 Patented Mar. 17, 1970 (CHOHL; 2)y (COOH)2 where x is about 1 to 4 and y is about 0 to 6. Preferred dibasic acids include, among other, tartaric, mucic and malic acids. Monobasic hydroxy acids such as glycolic and tribasic hydroxy acids such as citric, may also be employed. However, dibasic hydroxy acids are preferred. Suitable ethoxy amines include those of the general formula RN [(CH CH O),,H] R' where R is an alkyl of from about 1 to 30 carbon atoms, preferably an alkyl from about 8 to 24 carbon atoms; R is hydrogen or an alkyl of about 1 to 30 carbon atoms, preferably from about 8 to 24 carbon atoms; x is an integer from about 1 to 10, preferably less than about 5; y is l or 2 and z is 0 or 1, with the proviso that if y is 2, z is 0.

The reaction of the acid and amine can be conveniently carried out by heating a fluid mixture of the components containing about 1 to 1.5, preferably about 1.1 to 1.2 mols of amine per mol of acid at a temperature and for a time sufficient to completely react the acid and amine, e.g., until the theoretical amount of water is recovered from the reaction mixture. Suitable temperatures are from about 60 to 200 0, preferably about 100 to 150 C. The time required for complete reaction will vary depending upon the temperature and particular reactants but usually falls in the range of about 1 to 20 hours. A preferred process is to reflux the acid and a small molecular excess of amine in a suitable solvent, e.g., toluene, until the theoretical amount of water is recovered.

The sulfurization and phosphorization of the resulting reaction product can be accomplished by any of the various methods employed in the art but in each case should be conducted in a manner that provides the mixture with about 5 to 15% by weight of combined sulfur, preferably about 8 to 12%, and about 2 to 8%, Preferably about 4 to 6% by weight of combined phosphorus. A part cularly preferred method of conducting the sulfurization-phosphorization is phosphosulfurization which can conveniently be performed by adding a suitable amount, usually about 30 to mol percent based on the acid component, of phosphorus sesquisulfide or phosphorus penta sulfide to the reaction product and heating the resulting mixture at a temperature and for a time sufiicient to provide the aforementioned amounts of sulfur and phosphorus. Suitable temperatures are between about and 200 C., preferably about to C. Again the reaction time will vary with the reaction temperature selected but will usually fall in the range of mixture. The time required for complete reaction of the sulfur will vary depending upon the reaction temperature selected but usually falls in the range of about 3 to 15 hours. About to hours at 170 C. is a preferred sulfu-r-izing condition. After sulfurizat-ion of the reaction product, the sulfurized product can then be phosphorized employing a suitable phosphorizing agent such as a phosp'hosul-furizing agent. Phosphosulfurizing agents are the phosphorus sulfides such as P 8 P 5 etc., phosphorus sesquisulfide (P 8 being particularly preferred. Since, when employing the phosphorus sulfides, the treatment is a phosphosulfurization, it may act to provide the reaction product with sulfur as well as phosphorus.

The phosphosulfurized reaction product of the hydroxy dibasic acid and ethoxylated amine is then treated with an alcohol to improve oil solubility. Suitable alcohols in clude alkanols having from about 5 to 24 carbon atoms. Fatty alcohols e.g., lauryl alcohol, oleyl alcohol, etc., having from 10 to 24 carbon atoms are preferred. The treatment with alcohol is preferably carried out by heating, e.g., refluxing a fluid mixture of the phosphosulfurized reaction product and alcohol at a temperature of from about 80 to 170 C., preferably about 110 to 150 C., for a time sufficient to improve the solubility of the reaction product which time will vary depending upon the temperature and reactants but is usually within the range of about 5 to hours. Conveniently, the reaction is terminated when no further water is evolved. A preferable method of carrying out this reaction is to reflux the reactants in a solvent such as toluene. In general, the alcohol is used in a slight excess, about 101 to 105 percent, referred to the acidic reaction component.

The phosphosulfurized reaction product, as treated with an alcohol, can be further neutralized or partially neutralized by methods employed in the art using, for example, metal oxides. Neutralization can be accomplished by heating a fluid mixture of the reaction product with a metal oxide such as lead or zinc oxide at a temperature of from about 100 to 200 C., preferably about 130 to 170 C., for a time suflicient to neutralize the alcoholtreated, phosphosulfurized reaction product the desired degree. The final product will generally have an acid number of less than about 100, preferably, 60, and contain about 2 to 5 weight percent metal. The time for this neutralization required will vary depending upon the reactants and temperature, but usually is within the range of about 5 to 15 hours.

The second class of additives referred to above are the reaction products of unsaturated dibasic acids and an alcohol, followed by subsequent neutralization with a metal oxide, and then treated with phosphorus and sulfur. In general, the reaction is accomplished by heating a fluid mixture of the unsaturated dibasic acid and alcohol in about a 1:1 mol ratio so that the desired partial ester, e.g., the half ester, reaction product predominates. Conveniently, the acid and alcohol can be refluxed in a suitable solvent, e.g., toluene, with removal of water until no further water is evolved. However, the means by which this esterification is carried out in no Way limits the scope of this invention, since the partial ester product is desired only as in intermediate reaction material and can be prepared in a variety of ways well known to the art. Suitable acids are maleic, fumaric, citraconic, mesaconic as well as high molecular weight material such as 'linoleic dimer acids. Suitable alcohols are alkanols having about 4 to 24 carbon atoms and preferably about 6 to 18 carbon atoms. The ester, e.g., half ester, of the acid is nontralized with a metal oxide such as lead oxide. The neutralized ester, e.g., the lead salt or soap is then phosphorized and sulfurized, more accurately phosphosulfurized, for example, according to the procedure described above to produce a final product containing about 0.5 to 2% by weight, preferably about 0.75 to 1%, sulfur and about 0.5 to 5% by weight, preferably about 1 to 3%,

phosphorus, and about 15 to 25% by weight metal, e.g., lead depending on the degree of esterification in making the partial ester and the molecular weight of the alcohol portion of the partial ester. Using a preferred alcohol of about 116 to 158 molecular weight for example, lead con-tent will be about 18 to 22% The third class of additives encompassed by this invention are the reaction products of an overbased lead naphthenate with a dialkyl dithio phosphoric acid or a partially neutralized dialkyl dithio phosphoric acid. Overbased lead naphthenate is produced by reacting naphthenic acids with an excess of lea-d oxide over the amount required for neutralizing the naphthenic acids. Generally, the lead naphthenate will contain about 35 to 50% by weight lead and preferably about twice the amount of lead calculated for theoretical neutralization of the naphthenic acids. For the usual naphthenic acids having an acid number in the range of about 190220 the lead content preferably will be about 39 to 46%. The lead oxide is generally used in an excess of from about 50 to preferably about 75 to 125%. Suitable naphthenic acids are those having an acid number of about to 250, preferably about to 220 and an average molecular weight of about 220 to 320, preferably about 250 to 290 as calculated from the acid number. The basic lead naphthenate is reacted with a dialkyl dithiophosphoric acid in an amount sutficient to neutralize the excess ba-sicity of the lead naphthenate. The basic lead naphthenate may be similarly reacted with a partially zinc-neutralized dialkyl dithio phosphoric acid, again in an amount calculated to neutralize the excess bas-icity of the lead naphthenate. The alkyl group of the dialkyl dithiophosphoric acid may have from about 4 to 24 carbon atoms, preferably about 6 to 18 carbon atoms.

The lubricating oil base stock used in the present invention is of lubricating viscosity and can be, for instance, a solvent extracted or solvent refined oil obtained in accordance with conventional methods of solvent refining lubricating oils. Often, lubricating oils have viscosities from about 20 to 250 SUS at 210 F. The base can be derived from paraffinic, naphthenic, asphaltic or mixed base crudes, and if desired, a blend of solvent-treated Mid-Continent neutrals and Mid-Continent bright stocks may be employed. The oils can be thickened to grease consistency.

The base oil of the fluid lubricant or grease can also be a synthetic oil of lubricating viscosity. One type of synthetic oleaginous base which can be used in-an ester synthetic oil of lubricating visocosity which consists essentially of carbon, hydrogen and oxygen, e.g., di-2- ethylhexyl sebacate. Various of these lubricating materials have been described in the literature and generally their viscosity ranges from the light to heavy oils, e.g., about 50 SUS at 100 F. to 250 SUS at 210 F. and preferably 30 to 150 SUS at 210 F. These esters are of improved thermal stability, low acid number and high flash and fire points. The complex esters, diesters, monoesters and polyesters can be used alone, or, to achieve the most desirable viscosity characteristics, complex esters, diesters and polyesters can be blended with each other or with naturallyoccurring esters like castor oil to produce lubricating compositions of wide viscosity ranges which can be tailor-made to meet various specifications. This blending is performed, for example, by stirring together a quantity of diester and complex ester at an elevated temperature, altering the proportions of each component until the desired viscosity is reached.

The compositions of this invention incorporate into the base oil a small, minor amount of one of the above described additives sufficient to provide the base oil of lubricating viscosity (which is the. major portion of the composition) with improved antiwear and extreme pressure properties. This amount is generally about 0.01 to 15 or 20 or more percent by weight of the lubricant de- 6 pending on the particular base oil used and its applica- 200 grams of a 50 vis. 95 VI mineral oil were added to tion. The preferred concentration should be the minimum reduce viscosity, and the product filtered to remove unamount to give the desired properties for the particular reacted zinc oxide and insoluble reaction products. The application and usually will be about 0.2 to 20 percent by 600-gram yield of product analyzed: sulfur, 3.24%; weight of the lubricant. In some cases where oil solubility phosphorus, 1.84%; zinc, 2.82%; acid No. 50.6.

might limit the amount of additive employed, dispersants 5 EXAMPLE Iv may be used to increase the concentration. In these cases,

it has been found that increased solubility is best obtained Th5 half ester of maleic acid was P p y refluxin highly refined oils by dissolving the dispersant in the Q 0f maleic acid With 4 111018 of {nixed 7 oil before dissolving the additive. 10 alcohols 1n the presence of toluene solvent until 73 mol Materials normally incorporated in lubricating oils and of water were recovered and no further water was evolved.

greases to impart special characteristics can be added to The Product was filtered to remove traces of Solid the. composition of this invention. These include corrosion tarninants and the toluene solvent Was removed y vacuum inhibitors, additional extreme pressure agents, antiwear PP agents, etc. The amount of additives included in the EXAMPLE V composition usually ranges from about 0.01 weight per- 406 grams (1'9 mols est) f the Example 1v h lf cent up to about or more weight percent Of th lubrl' ester reaction product were treated with 210 grams (0.95

In general they can bgemnloyed 111 y amount mol) of lead oxide at 120 C. for one hour. The product dFslred as 10118 as the composltlol'l not unduly delete was then diluted with approximately two volumes of bennously f 20 zene and filtered to remove unreacted lead oxide and The following examples are meluded to Illustrate F insoluble lead salt of unreacted maleic acid. The fluid edvanteges of the eerflpounds of the Present composltlon filtrate was treated with 77 grams (0.35 mol) of phoslubneant eomposltlonsphorus sesquisulfide at 110 C. for one hour, filtered, and

EXAM LE I the solvent removed by vacuum stripping. The resultant .4 d Ethomeen 18/12 (0.67 mol) and Ethomeen T/12 fizi gfig y sulfuros4%phosphoms 1 6% an (0.73 mol) were reacted with tartaric acid (1.3 mols) by reflecting in toluene until the theoretical 2.6 mols of water EXAMPLE VI were recovered from reaeilen e e' Ethomeen A solution of basic lead naphthenate was prepared by 18/12 and T/12 are tertiary amines containing one fatty reacting 260 grams of napthenic acids (acid 212 avg. alkyl group and two dioxyethylene groups, having the MW 260) ith 223 grams (1 mol or 2 equiv.) of lead formula RN[(CH2CH2O)XH]2' The Ethemeens are oxide in 1600 grams of 100 vis. napthentic neutral oil. The

merelal matenalsfivalleble from chemleal resultant 22% lead naphthenate solution in oil analyzed Ethemeen T/ 12 denved f a,mlxture of ammes 9.70% lead, equivalent to approximately 44% lead conhavmg an :aYerage carbon mngmg from C14 tent in the lead naphthenate, or approximately twice the e predemment alkyl group m 18/12 15 lead content required for neutralization of the naphthenic Thls reaetlon Product was tohen treated wlth mol f acid. 300 grams of the basic lead naphthenate solution P285 for four hours at 110 and for at 130 were diluted with 200 grams of toluene, and to this mix- After removal of toluene Solvent the Selle amber e ture were added 48 grams of dioctyl dithiophosphoric acid uet analyzed} Sulfur 10'1%; phosphorus 520%; aeld 40 (acid No. 181), and the reaction mixture refluxed for six Thls 3 i Y found to be Soluble P P hours with water of reaction being removed via a Dean- W'P lubneetlpg 011 base Stocks but to have hmlted Stark trap. After removal of solvent by vacuum stripping, solublhty m Parafiime'type base stocks the resultant product analyzed: sulfur 2.94%; phos- EXAMPLE II PhOIOIJS, 1.53%; and lead, 7.57%. 640 grams of the product of Example I (1.94 acid No. EXAMPLE VII equivalents) were reacted with 400 grams (2 mols) lauryl 300 grams of basic lead naphthenate Solution alcohol by refluxing in toluene for 12 hours, recovering prepared as in Example VI were treated with 262 grams 11 ml. water of reaction. 200 grams of maleic acid (1.5 of a artiall y zinc-neutralized d1oct l d1th1o hos hOIlC t were .then added and the reeetlen Wes eontmued acid Facid No. 32.6), this amount being cal eulat ed to approxlmately 68 of T f Z collected e neutralize the excess basicity of the lead naphthenate. no further water was emg eve tee remove 0 After removal of solvent, the reaction product analyzed: toluene solvent, the dark amber fluid product analyzed: Sulfur 9.18% phosphorous 4.22% lead 482% and sulfur, 4.34%; phosphorus, 2.72%; acid No. 139. Zinc 400%.

EXAMPLE III EXAMPLE VIII 500 grams of the product of Example II were treated The efficacy of the compounds of this invention as exwith 50 grams of zinc oxide at 150 C. for 8 hours. treme pressure and antiwear additives is demonstrated by TABLE I Composition No Blank 1 2 Blank 3 4 5 Weight percent:

Base Oil A 98 93 Base Oil B 30 28. 5 27 27 Base Oil 0 .5 63

Example VI.

Example VII FalexMax. Load, lbs SAEMaohine, lbs. at 300 r.p.m Timken Machine, safe lbs 6 35 50 Four-B all Weld Point:

MHL l3. 7 40. 1 2x5. 3 19. Four Ball Wear Scar, mm.:

At 7 kg. for 2 hrs At 14 kg. for 1 hr Timken Wear at 100 lbs., mg

B ase oilsA and B are solvent refined neutral oils, having 100 F. viscosities of about 50 and 200 SUS, respectively. Base oil 0 is a solvent refined bright stock having a viscosity of SUS at 210 F.

the data of Table I, which show performance in the Falex load test, the Four-ball EP and wear tests, the 'SAE load test, and the Timken load and wear tests. The tests used in evaluating these lubricants are well known in the art and their description is not considered essential to this invention. The Timken wear test is run using the T imken machine described in CRC procedure L-18-545, modified so that the test block is continuously moved back and forth for a distance of about 0.13 inch approximately every 15 seconds.

It is claimed: 7

1. An extreme pressure additive comprising the product of the process consisting essentially of reacting an unsaturated dicarboxylic aliphatic acid selected from the group consisting of maleic, fumaric, citraconic, mesaconic, and linoleic dimer acid, and an alkanol of about 4 to 24 carbon atoms in approximately a 1 to 1 mole ratio to produce a partial ester, reacting the partial ester with lead oxide to neutralize the same, and thereafter phosphosulfurizing the neutralized partial ester to produce a product containing about 0.5 to 2 percent by weight sulfur and about 0.5 to 5 percent by weight phosphorous.

2. The additive of claim 1 wherein said phosphosulfurized reaction products contains about 1 to 3 percent by weight phosphorous, about 0.75 to 1 percent by weight sulfur and about 15 to 25 percent by weight of lead.

3. The additive of claim 2 wherein the alcohol is an alkanol having about 6 to 18 carbon atoms.

4. An oleaginous lubricant composition consisting essentially of a base oil of lubricating viscosity and an amount sufiicient to give improved extreme pressure properties to the composition of the product of claim 1.

' 5. The composition of claim 4 wherein said amount is from about 0.01 to 20 percent by weight of the lubricant composition.

6. An oleaginous lubricant composition consisting essentially of a base oil of lubricating viscosity and an amount sufficient to give improved extreme pressure properties to the composition of the product of claim 10.

7. The additive of claim 1 wherein said unsaturated dicarboxylic aliphatic acid is maleic acid.

References Cited UNITED STATES PATENTS 2,375,061 5/1945 Williams et a1 25232.7 2,419,153 4/1947 Musselman et al. 25232.7 X 2,733,235 1/1956 Cross et a1. 252-82.? X

PATRICK P. GARVIN, Primary Examiner W. CANNON, Assistant Examiner U.S. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. q 501 l;1q ifierch 17. 1970 n n Howard J. Matson It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Claim 6, line t thereof, delete "10" and insert therefor --2--.

SIGNEE AND S FM ED 35? 3 1970 Attest:

Edward M. Fletcher, Ir. Attesting Officer mm B. EWJYIM, JR.- Omissiom of Patent! FORM PO-105O (10 69) -gc 50375.pqg e u s covumnrm nmmnc ornce: nu o-ni-au