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Publication numberUS3259579 A
Publication typeGrant
Publication dateJul 5, 1966
Filing dateNov 29, 1954
Priority dateNov 29, 1954
Publication numberUS 3259579 A, US 3259579A, US-A-3259579, US3259579 A, US3259579A
InventorsWilliam W Rice, Dilworth T Rogers
Original AssigneeExxon Research Engineering Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Esters of dithiophosphoric acids and lubricating oil compositions containing same
US 3259579 A
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Description  (OCR text may contain errors)

United States Patent 3,259,579 ESTERS 0F DITHIOPHOSPHORIC ACIDS AND LUBRICATING OIL COMPOSITIONS CON- TAINING SAME Dilworth T. Rogers, Summit, and William W. Rice, Elizabeth, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware N0 Drawing. Filed Nov. 29, 1954, Ser. No. 471,885 20 Claims. (Cl. 252-423) This invention relates to new compositions of matter and more particularly to a new class of chemical compounds which are useful in lubricating oil compositions, to lubricating oil compositions containing such compounds, and to methods for preparing such compounds. The lower molecular weight compounds are useful as multi-purpose lubricating oil additives and the higher molecular weight compounds are useful as synthetic lubricating oils.

The utilization of additives in lubricating oil compositions is well known. These additives are used to improve one or more characteristics of the lubricating oil compositions such as viscosity index, pour point, oxidation resistance, corrosion resistance, detergency, and the like, and are employed extensively in lubricating oil compositions for internal combusion engines such as automotive and aviation engines. Due to the increasing severity of engine operation, there is a continuing and critical need for new and improved additives which are capable of imparting improved characteristics to the lubricating oil compositions. Preferably, such new additives will improve more than one characteristic or property of the oil. In addition to the search for new and improved additives, considerable effort has been expended in the search for new and improved types of synthetic oils which may be used in such lubricating oil compositions. This has been necessary because it has been found that the quality of mineral oils, such as those derived from petroleum oils, is limited by the processing methods, such -as solvent extraction, acid treatment, and the like, which are available.

A new class of chemical compounds has now been found which are useful in lubricating oil compositions, the lower molecular weight compounds being useful as multi-purpose lubricating oil additives and the higher molecular weight compounds being useful as synthetic lubricating oils. The lower molecular Weight compounds are the products obtained by treating a compound selected from the group consisting of alkylene oxides and glycols and containing 2 to 18 carbon atoms with a dithiophosphate having the formula where R is a hydrocarbon radical containing 3 to 20 carbon atoms; Y is selected from the group consisting of hydrogen and metals of Groups I and II of the periodic table, and x is the valence of Y. The R radicals in the formula may be different radicals. In the preferred embodiment of this portion of the invention, the alkylene oxides and glycols contain 3 to 6 carbon atoms and R is an alkyl radical containing 6 to 10 carbon atoms. Preferably 1 to 3 moles of the alkylene oxide or glycol are reacted with one mole of the dithiophosphate and the reaction is carried out at a temperature in the range of about 100 to 300 F. Preferably Y is an alkali metal, an alkaline earth metal or zinc. The above-mentioned compounds are useful as lubricating oil additives and may be used in synthetic lubricating oils as well as mineral oils in concentrations of about 0.1 to 10% and preferably 0.5 to by weight based on the total composition. These relatively low molecular weight reaction products have been found to improve a number of properties of lubricating oil compositions. More specifically, it has been found that they are excellent sludge dispersants and sludge inhibitors; they stabilize other phosphorous sulfide-treated additives with respect to H 8 evolution; they function as emulsifying agents and are, therefore, useful in cutting oils; they have excellent extreme pressure properties and antiwear properties; they inhibit copper corrosion and reduce corrosion resulting from hydrogen halides and they are compatible wtih other conventional additives such as sulfonates, alkyl phenol sulfides, metal salts of alkyl phenol sulfides, phosphosulfurized metal salts of alkyl phenol sulfides and the like.

It has also been found that the above-described low molecular weight compounds may be treated with phosphorus pentasulfide (P 8 and additional alkylene oxides or glycols to form higher molecular weight compounds which are useful as synthetic lubricating oils. Preferably, the low molecular weight compound, that is the reaction product of the dithiophosphate and the alkylene oxide or glycol, which is further reacted is a compound wherein Y is hydrogen. More specifically, it has been found that, by reacting one mole of the reaction product of the dithiophosphate and the alkylene oxide or glycol separately and in a sequence with at least the first member in a series consisting of (1) 0.25 mole of P 8 (2) about 0.5 to 1.5 moles of an alkylene oxide or glycol, (3) about 0.125 mole of P 8 and (4) about 0.25 to 0.75 mole of an alkylene oxide or glycol, a higher molecular weight compound is formed which is useful as a synthetic lubricating oil. These high molecular weight compounds have high viscosity indices, excellent extreme pressure properties and other properties which are advantageous for lubricating oils.

The dithiophosphates employed in the present invention have the general formula [(ROhli-SLY where R is a hydrocarbon radical containing 3 to 20 carbon atoms; Y is selected from the group consisting of hydrogen and metals of Groups I and II of the periodic table, and x is the valence of Y. R may be an alkyl, aryl, alkaryl or ara-lkyl radical. Preferably R is an alkyl radical and preferably the alkyl radical contains 6 to 10 carbon atoms. When Y is a metal, it is preferably an alkali metal such as sodium or potassium; an alkaline earth metal such as calcium, barium or magnesium; or zinc. These metal dithiophosphates may be represented by the following formula where M is a metal of Groups I and II of the periodic table and x is the valence of M.

The dithiophosphates are prepared by methods well known to the art. More specifically, these dithiophosphates may be conveniently prepared in accordance with the following reaction:

where R has the aforedescribed definition. The diester is the principal product. Small amounts of the monoand tri-esters may also be formed. Mixtures of alcohols may be employed if desired. The above reaction may be carried out at a temperature in the range of about to 300 F. for about 2 to 10 hours. To form dithiophosphates where Y is a metal, the dithiophosphate shown in Equation 1, which may also be termed a dithio' 3 phosphoric acid, is reacted with a basic reacting compound, such as the oxide or hydroxide, of a metal of Groups I and II of the periodic table. For example, the metal dithiophosphate may be prepared in accordance with the following reaction:

2(RO)Z}|.])'SH M(H)x [(Ro)1i s]XM 2) where M is a metal of Groups I and II of the periodic table. Specific compounds of the formula ROH which may be employed in these reactions include Cyclohexanol Isopropanol 2-ethylhexanol Capryl alcohol N-butanol Oleyl alcohol Stearyl alcohol Methyl isobutyl carbinol Especially preferred compounds of the formula ROH are Oxo alcohols which are derived from the well-known Oxo process. In the Oxo process, Oxo alcohols are synthesized from olefinic organic compounds and mixtures of CO and H in the presence of a Group VIII metal catalyst, usually cobalt. The primary reaction product consists essentially of organic carbonyl compounds, mainly aldehydes having one more carbon atom per molecule than the olefinic feed material. This oxygenated product is then hydrogenated in a second catalytic stage to convert the aldehydes to the corresponding alcohols. Practically all types of organic compounds having an olefinic double bond, such as aliphatic olefins and diolefins, cycloolefins, aromatics with olefinic side chains, oxygenated organic compounds with olefinic double bonds, and the like, may be employed as starting materials. The metal catalyst may be present as a solid or in the form of a compound soluble in the olefinic feed stock. Suitable reaction conditions in the primary reaction include temperatures of about 150450 'F., presures of 100 to 300 and higher atmospheres, H to CO ratios of about 0.5-221, liquid feed rates of about 0.1 to 5.0 v./v./hr., and gas feed rates of about 1000 to 45,000 standard cubic feet of gas mixture per barrel of liquid olefin feed. Similar or higher temperatures and pressures, and hydrogenation catalysts such as nickel, copper, tungsten, oxides or sulfides of Group VI and Group VIII metals, etc., may be employed in the second stage for hydrogenation of the carbonyl compounds to alcohols. Specific Oxo alcohols prepared by the 0x0 process include C Oxo alcohol from butylene-propylene copolymer, C Oxo alcohol from tripropylene and C Oxo alcohol from tetrapropylene.

Specific examples of the dithiophosphates which may be employed in this invention include zinc dihexyl dithiophosphate, z-inc hexyl octyl dithiophosphate, barium isopropyl octyl dithiophosphate, sodium butyl tetradecyl dithiophosphate, dioctyl dithiophosphoric acid, calcium didodecyl dithiophosphate, potassium nonadecyl pentadecyl dithiophosphate, hexyl decyl dithiophosphoric acid, zinc isopropyl methylisobutylcarbinyl dithiophosphate, and magnesium cyclohexyl amyl dithiophosphate.

The alkylene oxides and glycols which are employed in the present invention are those containing 2 to 18 carbon atoms and preferably those containing 3 to 6 carbon atoms. The alkylene oxides may be represented by the general formula c n o and the glycols may be represented by the general formula where m is an integer of 2 to 18. Specific examples of the alkylene oxides which may be employed include 1,2

propylene oxide; 1,3 propylene oxide; 1,2-butylene oxide; ethylene oxide; 1,2-hexylene oxide; 2,3 amylene oxide; 1,2 decylene oxide; 2,3 octodecylene oxide and 2,3- octylene oxide. Specific examples of the glycols which may be employed include 1,2-propylene glycol; 1,3- propylene glycol; ethylene glycol; 1,2-butylene glycol; 2,3-butylene glycol; tetradecylene glycol; 1,2-amy1ene glycol; 3,4-hexylene glycol; 1,2 dodecylene glycol; 1,2 octylene glycol and 1,2 octodecylene glycol. Alkylene sulfides and thioglycols may be employed in the present invention in place of their oxygen derivatives, although the thio derivatives are less preferred due to their relatively strong and disagreeable odor.

The low molecular weight compounds of this invention which are useful as lubricating oil additives are the products obtained by reacting a dithiophosphate having the formula with an alkylene oxide or a glycol. Preferably 1 to 3 moles of the alkylene oxide or glycol are reacted with the dithiophosphate. The reaction may be carried out at a temperature ranging from room temperature F.) to about 400 F. and preferably is carried out at a temperature in the range of about to 300 F. The reaction proceeds slowly at temperatures below about 100 F., and at temperatures above about 400 F. the dithiophosphate may decompose. Atmospheric pressures may be employed, although elevated pressures such as up to 10 atmospheres may also be employed if desired. Elevated pressures are especially useful when employing ethylene oxide since at atmospheric conditions ethylene oxide is a gas. The reaction proceeds rapidly and will be substantially completed in about 0.5 to 5 hours. Generally a reaction time of 1 to 2 hours will be sufiicient to assure completion of the reaction. The end of the reaction will be indicated when evolution of heat from the reaction mixture ceases. In carrying out the reaction, it is convenient to add the alkylene oxide or glycol to the dithiophosphate which has been preheated. Intimate mixing of the reactants by mechanical or other means will facilitate the reaction. It is often convenient to initially dissolve the dithiophosphate in an inert solvent such as a mineral lubricating oil and to carry out the reaction in this solvent medium.

Although the reaction products of this invention have not been positively identified at this time, it is believed that they have the following formulae and are formed in accordance with the following equations. For example, when the dithiophosphoric acid is reacted with n moles of propylene oxide, it is believed that the following product is produced:

wherein n is prefer-ably an integer of 1 to 3. In case glycols are employed, it is believed that the dithiophosphoric acid reacts with n moles of 1,2-propylene glycol, for example, as follows:

(RO)zP-S CHCHIO 11H H20 Thus it is believed that 1,2-propylene glycol is dehydrated in the reaction and forms a compound similar to that formed with propylene oxide. In the case where a metal dithiophosphate, for example such as zinc dithiophos phate, is reacted with n moles of propylene oxide, it is believed that the following reaction takes place:

1! E [(RO)2PS]:Z11 nOH-CH:

fi (CIHa 0)=Ps]1 CH-CHzO nZn When a dithiophosphate of a monovalent metal, such as sodium, is reacted, for example, with propylene oxide, it is believed that the following reaction takes place:

H (IJHa fi (CH: (RO):P-S-N3+I1C]\17CH1 (R0)2PS- CHCHEO Na 0 I The reaction product of a dithiophosphoric acid and an alkylene oxide or glycol may be reacted with a basic reacting compound of a metal to form the metal salt thereof. For example, where the reaction product of a dithiophosphoric acid and propylene oxide is reacted with zinc hydroxide, it is believed that the following reaction takes place:

CHI

The reaction product of the dithiophosphates and the alkylene oxides or glycols may be further reacted with P 8 and additional alkylene oxides or glycols to form high molecular Weight compounds which are useful as synthetic lubricating oils. Preferably the dithiophosphate compounds employed to form lubricating oils are dithiophosphoric acids, that is where Y in the formula is hydrogen. If the low molecular weight reaction product of the dithiophosphate and the alkylene oxide or glycol is designated as Compound I, and P 8 is designated as Compound II and the alkylene oxide or glycol is designated as Compound III, the reactions may be described as being carried out as follows: 1 mole of Compound I is reacted separately and in a sequence with at least the first member of a series consisting of (1) about 0.25 mole of Compound II, (2) about 0.5 to 1.5 moles of Compound III, (3) about 0.125 mole of Compound II, and (4) about 0.25 to 0.75 mole of Compound III. Thus four different compounds may be obtained by reacting the various compounds in accordance with the above-described procedure. More specifically, a first reaction is prepared by reacting l mole of the dithiophosphate-alkylene oxide or glycol reaction product with about 0.25 mole of P 8 a second reaction product is obtained by reacting one mole of the first reaction product with about 1 to 3 moles of additional alkylene oxide or glycol; a third reaction product is obtained by reacting 1 mole of the second reaction product with about 0.25 mole of P 8 and a fourth reaction product is obtained by reacting 1 mole of the third reaction product with aboutl to 3 moles of additional alkylene oxide or glycol. All of the four above-described products are useful as synthetic lubricating oils. The

(IJHa The reaction product of Equation 8 may then be further reacted with, for example, additional propylene oxide in accordance with the following postulated equation:

Then the reaction product of Equation 9 may be further reacted with additional P 8 in accordance with the following postulated equation:

Then the reaction product of Equation 10 may be further reacted with additional propylene oxide in accordance with the following postulated equation:

The following examples are intended to set forth the invention in greater detail but it will be understood that it is not intended that the invention be limited in any way to these examples.

EXAMPLE I.PREPARATION OF REACTION PRODUCTS A. Preparation of zinc di-C C alkyl dithi0ph0sphate Propylene oxide reaction productPr0duct A A commercially available additive concentrate consisting of about 57.5% by weight of a zinc di-C C alkyl dithiophosphate in a diluent mineral oil was reacted with propylene oxide to form an additive in accordance with this invention. The untreated commercial additive concentrate will be referred to hereinafter as Product A-U, the U referring to the fact that it was untreated. The additive of the present invention, Product A, was prepared as follows:

386.0 grams of Product A-U were placed into a threeneck, round bottom flask to which were attached a water cooled condenser, an air driven stirrer, a dropping funnel, and a thermometer. The flask and contents were heated to a temperature of 190 F. 100 cc. (82 g.) of previously chilled propylene oxide was added in 5 cc. portions by means of the dropping funnel. Heat was given off during the addition of the propylene oxide. The temperature of the reaction mixture was maintained at 180 F. by means of an ice bath. After all of the propylene oxide was added, the reaction mixture was heated at 250 F. and nitrogen blown for 2 hours. Prior to the propylene oxide treatment, Product A-U had a phosphorus content of 4.70%, sulfur content of 10.33%, neutralization number of 82.6 and saponification number of 89.4; after propylene oxide treatment, the product had a phosphorus content of 4.15%, sulfur content of 8.67%, neutralization number of 50.7 and saponification number of 65.3.

B. Preparation of barium di-C C alkyl ditlziophosphate-Prpylene oxide reaction product-Product B A commercially available additive concentrate, hereinafter termed Product BU, consisting of (1) about 85% by weight of an oil solution containing as the active ingredient about 46% by weight of barium dl-C cg alkyl dithiophosphate and (2) about 15% by weight of an oil solution containing as the active ingredient about 40% by weightof barium sulfonate was treated with propylene oxide in accordance with the present invention as follows to form a Product B:

351.0 grams of Product BU weretreated with 100 cc. of propylene oxide in a similar manner as described in the procedure for the propylene oxide treatment of Product A-U.

Anaylsis of Product BU:

Ba, percent 6.79 P, percent 2.61 Neut. No. 0.41 Sap. No 10.36

Analysis of Product B:

Ba, percent 6.57 P, percent 2.71 Neut. No. 0.10 Sap. No. 13.26

C. Preparation of di C 0x0 dithiophosphoric acid Propylene oxide reaction product-Product C Initially a C Oxo alcohol was treated with P 8 to form a di C 0x0 dithiophosphoric acid (Product C-U) as follows:

A mixture of 1500 grams of C Oxo alcohol and 700 grams of powdered P 5 was placed in a glass reaction vessel and agitated at 180:10 P. for a period of 6 hours. The reaction mixture was cooled and filtered through a sintered glass funnel to remove unreacted P 8 The P 'S -treated C Oxo alcohol was a liquid having the following analysis:

Neut. No. 158

Sap. No. 169.5 S, percent 18.3 P, percent 8.96

Product CU was then treated with propylene oxide to form Product C as follows:

1200 grams of Product C-U were treated with 300 cc. of propylene oxide in a similar manner as described in the procedure for the preparation of Product A. Reaction Product C-U had a neutralization number of 13.9, a saponification number of 174.6, phosphorus content of 8.28% and sulfur content of 15.8%.

D. Preparation of zinc di C 0x0 dithiophosphate- Propylene oxide reaction pr0duct--Product D Initially a zinc di C Oxo dithiophosphate (Product D-U) was prepared as follows:

145 grams of Product C-U and 20 grams of powdered zinc oxide were charged to a reaction vessel and stirred for 2 hours at 250 F. The reaction product was filtered hot through a sintered glass funnel.

Product D-U was then treated with propylene oxide to form Product D as follows:

160 grams of Product D-U were treated with 100 cc. of propylene oxide in a similar manner as described in the procedure for the propylene oxide treatment of Product A-U.

E. Preparation of di C 0x0, dithiophosphoric acid- Propylene oxide reaction pr0duct-Product E A reaction product of di C Oxo dithiophosphoric acid and propylene oxide, Product E, was prepared as follows:

1815 grams of Product C-U were treated with 400 cc. of propylene oxide as directed in the procedure for the preparation of Product A. Product E had a neutralization number of 14, a saponification number of 175, and analyzed 15.8% sulfur and 8.28% phosphorus. Product E, which was a liquid, had an SSU viscosity at 210 F. of 45.5 and a viscosity index of 66.

F. Preparation of di C 0x0 dithiophosphoric acid Propylene oxideP S reaction prodact.-Pr0duct F Product E was then treated with phosphoruspentasulride, P 8 as follows to form a Product F:

465 grams of Product E and 100 grams of powdered P 8 were charged to a reaction vessel and agitated at 250 F. for 6 hours. The reaction mixture was filtered hot through a sintered glass funnel.

G. Preparation of di C Oxxo dithiophosphoric acid- Propylene oxideP S,Pr0pylene oxide reaction product-Product G H. Preparation of di-isopropyl dithiophosphoric acid- Propylene oxide reaction product-Product H 275 grams of isopropyl alcohol and grams of pow dered P S were charged to a flask and stirred for 2 hours at 180 F. To the reaction product cc. of propylene oxide were added. Procedure for the propylene oxide addition is described in the preparation of Product A. The reaction Product H was filtered hot.

Analysis of P S -treated isopropyl alcohol:

Neut.No 251 Sap. No. 284.6

Analysis of Product H:

Neut. No. 35.9

Sap. No. 221.5

I. Preparation of zinc di-C -C alkyl dithi0ph0sphate 1,2-pr0pylene glycol reaction pr0ductProduct I 354 grams of Product A-U were placed into a threeneck, round bottoms flask to which were attached an airdriven stirrer, a dropping funnel and a thermometer. The flask and contents were heated to a temperature of 225 F. 40 cc. of chilled 1,2-propylene glycol were added in 5 cc. portions. some heat was given off during the course of the addition. The reaction mixture was heated for 2 hours at 250 F.

EXAMPLE II.CARBON BLACK DISPERSANCY TEST Product A, Product A-U, Product B, and Product BU were each dissolved in a mineral lubricating oil 9 which consisted of a solvent-extracted mineral oil (a blend of Mid-Continent neutral and bright stock) of SAE 10 grade to form the following compositions:

Composition I consisted of 3.0 wt. percent of Proi suspended almost 50% more sludge than did the untreated additive product, Product A-U. This test is another indication of .the excellent sludge dispersancy properties of the products of this invention.

2x1 lalilijdicgziggzoflby weight of the aforementioned 5 EXAMPLE IV 4LUDGE FORMATION Composition II consisted of 3.0 wt. percent of Product INHIBITOR TEST A-U and 97.0% of the mineral lubricating oil. In this-example, Product A and Pl'edllet Were Composition III consisted of 2.5% by weight of Proevaluated as Sludge formation inhibitors. These addiduct B and 75% by weight of the mineral lubricat- 1O tives were dissolved in a filtered used drain oil obtained i n from a laboratory engine test in which a high-deposit- Composition IV consisted of 2.5% by weight of Profel'mlng f11e1 and an SAE10 gTade lubfieatihg Oil Were duct 13.11 and 975% by weight f the mineral lubricat. used. Since filtered used drain O11 continues to form i 1 sludge upon standing, this test is an indication of the Th se cgmpositigns were h evaluated i a C b 15 eifectiveness of an additive to inhibit sludge formation. Black Dispersancy Test which was carried out by adding P blends Were P P cehtaihlhg 30% y 6 grams of carbon black with thorough mixing to 294 Welght f Pfedllct A and 979% by gh e the filtered grams of h il composition Th resultant blgnds used dram 011 and the other blend consistlngof 3.0 wt. were maintained at 200 F. for 48 hours in a 500 cc. Pereent 0f Prodllct A43 and 970% y Welght 0f the graduate, Th ft 150 gram portions f h il filtered used drain oil. The blends were stored for one blends were decanted from the graduates and filtered WEEK at 2 00 F., after each blend was filtered and through weighed sintered glass funnels and the weight of e qh 0f p e 011 each filter s d t mined by carbon black determined. This test is an indication of welghlhg- The followmg results Were Obtamed 111 1 the ability of an additive to disperse materials such as Particular test! engine sludge in lubricating oil compositions. The 1501- TABLE III.RESULTS or SLUDGE FORMATION INHIBI- lowing results were obtained in this test: TOR TEST TABLE I.RESULTS OF CARBON BLACK DISPERSANCY TEST Grams Sludge Additive Product Formed per 330 Grams of Grams oi Sus- Used Oil Additive pended Carbon Composition Product Black per 150 Grams oi None Blend .AU 0: s4

gidinerai Lubricating Oil Alone None 0:25 This test shows that Product A is a sludge inhibitor g gs and is superior to the untreated compound, Product AU. The superior load-carrying properties of the products It will be noted that Product A dispersed more than four times as much carbon black as the untreated prog mventlon Shown by Examples and duct, Product A-U. Also, it will be noted that Product B dispersed nearly twice as much carbon black as the EXAMPLE V' SAE TEST untreated parent product, Product B-U. Thus the low Product A, Product AU, Product C, and Product molecular weight reaction products of this invention are C-U were evaluated in this particular test. Separate shown to be excellent dispersants for such materials as blends were prepared, each containing 0.7% by weight of carbon black in lubricating oil compositions. the particular additive in a lubricating oil base stock EXAMPLE III ACETONE INSOLUBLE SLUDGE composition which consisted of 95% by weight of an 'DISPERSANCY TEST SAE-10 grade mineral oil and 5.0% by weight of a commercial detergent-inhibitor additive. The following four COITIPOSIUOB I Fontamlng y welght of Product separate compositions were prepared: Composition V A and cempesiheh II eenlalhlhg 3.0% y welght 0f contained 0.7% by weight of Product A; Composition Product AU were evaluated in an Acetone-Insoluble VI t i d 0.7% b i h of P d A U; c Sludge Dispersancy Test- In this test, 6 grams of aceposition VII contained 0.7% by weight of Product C, tone-insoluble sludge obtained from automotive engines a d Composition VIII contained 0.7% by weight of Prowere added to 294 grams of each of the two composi- 5o d t C U, liens With thOTOugh IhiXihg and the resultant blends were The SA E Test is carried out as described in J.I.P. vol. stored at 200 F. for 48 hours in a 500 cc. graduate. 32 (1936). The following results were obtained in this Then 150 grams of each 011 blend were decanted and t filtered through a sintered glass funnel and the amount of acetone-insoluble sludge collected on each filter was TABLE RESULTS OF SAE TEST determined. The following results were obtained in this Additive Scale test: Composition Product Reading, TABLE II.RESULTS OF ACETONEJNSOLUBLE SLUDGE Pmnds DISPERSANCY TEST A VI A-U so Grams of Sus- VII G 95 Additive pended Carbon C U 90 Composition Product Black per Grams of Blend 70 It will be noted that the additive of this invention 1mem1Lubflatmg oilAlQne 120119 3%? Product C is superior to the untreated additive Product 11 A-U 0134 C-U in the SAE Test. Also it will be noted that the other additive of this invention, Product A, which was It ill b noted fr th resuus f th tests h t evaluated in this test, [was substantially superior to the Product A prepared in accordance with this invention 75 untreated Product A-U.

TABLE V.RESULTS OF ALMEN TEST Additive Weights Composition Product Carried VIL C 7 VIII C-U It will be noted that the additive of this invention Product C was superior in this test to the untreated additive Product C-U.

EXAMPLE VII.TvIMKEiN TEST Composition V and Composition VI were evaluated in the Timken Test as described in J.I. P. vol. 32 (1936). The results of the T imken Test were as follows:

TABLE VI.RESULTS OF TIMKEN TEST Additive Load Composition Product Carried, Pounds V A VI A-U 8 It will be noted that the additive of this invention Product A was superior in this test to the untreated additive Product A-U.

Other testswere conducted to evaluate further the low molecular weight reaction products of this invention. In these tests it was shown that the alkylene oxideor glycoltreated dithiophosphates showed several advantages over the untreated additive products for use as motor oil additives. These advantages were: (1) less corrosive to copper; (2) improved color; (3) improved water sensitivity characteristics in oil blends containing conventional additives; (4) increased resistance to hydrogen bromide corrosion. All of the products tested met the conventional motor oil inspection requirements for flash, rfire, compatibility, and hydrogen sulfide odor.

When the additives of the present invention, that is the low molecular weight reaction products of dithiophosphates and alkylene oxides or glycols, are employed as lubricating oil additives, they are preferably added to the lubricating oil compositions in proportions of about 0.1% to about 10.0% and preferably 0.5 to about 5.0%, based on the total composition. The proportions giving the best results will vary somewhat according to the nature of the additive and the specific purpose which the lubricant is to serve in a given case. For commercial purposes, it is convenient to prepare concentrated oil solutions in which the amount of additive in the composition ranges from 25% to 50% by weight, and to transport and store them in such form. 'In preparing a lubricating oil composition for use as a crankcase lubricant, the additive concentrate is merely blended with the base oil in the required amount.

The low molecular weight products of the present invention may be employed not only in ordinary hydrocarbon lubricating oils but also in the heavy duty type of lubricating oils which have been compounded with such detergent type additives as metal soaps, metal petroleum sulfonates, metal phenates, metal alcoholates, metal alkyl phenol sulfides, metal organo phosphates, phosphites, thiophosphates, and thiophosphites, metal xanthates and thioxanthates, metal thioc-arbamates, and the like. Other types of additives, such as alkyl phenols and phenol sultfides, may also be present. 1

The lubricating oil base stocks used in the compositions of this invention may be straight mineral lubricating oils or distillates derived from paraflinic, naphthenic, asphaltic or mixed base crudes, or, if desired, various blended oils may be employed as Well as residuals, particularly those from 'which asphaltic constituents have been carefully removed. The oils may be refined by conventional methods using acid, alkali and/or clay or other agents such as aluminum chloride, or they may be extracted oils produced by solvent extraction with solvents such as phenol, sulfur dioxide, etc. Hydrogenated oils or white oils may be employed as well as synthetic oils prepared, for example, by the polymerization of olefins or by the reaction of oxides of carbon with hydrogen or by the hydrogenation of coal or its products. In certain instances cracking coal tar fractions and coal tar or shale oil distillates may also be used.

Other lubricating oil base stocks which may be used include synthetic lubricating oils having a viscosity of at least 30 SSU at P. such as esters of monobasic acids (e.g. ester of C Oxo alcohol with C Oxo acid, ester of C Oxo alcohol with octanoic acid, etc.), esters of dibasic acids (e.g. di-2-ethyl hexyl sebacate, di-nonyl adipate, etc.), esters of glycols (e.g. C Oxo acid diester of tetraethylene glycol, etc.), complex esters (e.g. the complex ester formed by reacting one mode of sebacic acid with two moles of tetraethylene glycol and two moles of Z-ethyl-hexanoic acid, complex ester formed by reacting one mole of tetraethylene glycol with two moles of sebacic acid and two moles of 2-ethyl hexanol, complex ester formed by reacting together one mole of azelaic acid, one mole of tetraethylene glycol, one mole of C Oxo alcohol, and one mole of C Oxo acid), esters of phosphoric acid (e.g. the ester formed by contacting three moles of the mono methyl ether of ethylene glycol with one mole of phosphorus oxychloride, etc.), halocarbon oils (e.g. the polymer of chlorotrifluoroethylene containing twelve recurring units of chlorotrifiuoroethylene), alkyl silicates (e.g. methyl polysiloxanes, ethyl polysiloxanes, methylphenyl polysiloxanes, ethyl-phenyl polysiloxanes, etc.), sulfite esters (e.g. ester formed by reacting one mole of sulfur oxychloride with two moles of the methyl ether of ethylene glycol, etc.), carbonates (e.g. the carbonate formed by reacting C Oxo alcohol with ethyl carbonate to form a half ester and reacting this half ester with tetraethylene glycol), mercaptals (e.g. the mercaptal formed by reacting 2-ethyl hexyl mercaptan with formaldehyde), formals (e.g. the formal formed by reacting C Oxo alcohol with formaldehyde), polyglycol type synthetic oils (e.g. the compound formed by condensing butyl alcohol with fourteen units of propylene oxide, etc.), or mixtures of any of the above in any proportions. Also, for special applications, animal, vegetable or fish oils or their hydrogenated or volatilized products may be employed in admixtures with mineral oils. Also mixtures of any of the above-mentioned oils in any proportions may be used.

For the best results the base stock chosen should normally be an oil which with the new additive present gives the optimum performance in the service contemplated. However, since one advantage of the additives is that their use also makes feasible the employment of less satisfactory mineral oils, no strict rule can be laid down for the choice of the base stock. The additives are normally sufiiciently soluble in the base stock, but in some cases auxiliary solvent agents may be used. The lubricating oils will usually range from about 40 to seconds (Saybolt) viscosity at 210 F. The viscosity index may range from 0 to 100 or even higher.

Other agents than those which have been mentioned may be present in the'oil composition, such as dyes, pour point depressants, heat thickened fatty oils, sulfurized fatty oils, sludge dispersers, antioxidants, thickeners, viscosity index improvers, oiliness agents, resins, olefin polymers, and the like. Assisting agents which are particularly desirable as plasticizers and defoamers and which may be included in the composition are the higher alcohols having 13 preferably 8 to 20 carbon atoms, e.g. octyl alcohol, lauryl alcohol, stearyl alcohol, and the like.

In addition to being employed in lubricants, the additives of the present invention may also be used in other mineral oil products such as motor fuels, hydraulic fluids, torque converter fluids, cutting oils, flushing oils, turbine oils, transformer oils, industrial oils, process oils and the like, and generally as useful additives in mineral and synthetic oil products. They may also be used in gear lubricants, greases and other products containing mineral or synthetic oils as ingredients.

The higher molecular weight reaction products, that is the reaction products of dithiophosphates and alkylene oxides or glycols which are further treated with P 8 and additional alkylene oxides or glycols, may be employed as lubricating oils in lubricating oil compositions. Generally, when they are used as the sOle lubricating oil base stock in lubricating oil compositions, they will be ememployed in major proportions, such as in the range of about 55 to 95% by weight based on the total composition. However, if desired, the higher molecular weight reaction products of this invention may be employed together with mineral oils and/or other synthetic lubricating oils of the type previously described, in which event the high molecular weight products of this invention may be present in minor proportions such as in the range of about 5 to 45% by weight based on the total composition. In general, therefore, the higher molecular weight reaction products of this invention which are useful as synthetic lubricating oils may be employed in the lubricating oil compositions from concentrations as little as about 1% or less to concentrations of about 99% or more by weight based on the total composition.

The high molecular weight reaction products of this invention may be employed in lubricating oil compositions which contain the low molecular reaction products of this invention and conventional additives such as those previously disclosed. In addition to being used in lubricants, the high molecular weight reaction products of the present invention may be used in other mineral and synthetic oil products such as hydraulic fluids, industrial oils, greases, and the like. The high and low molecular weight products of this invention are also usefulas flotation agents for ores, soil-conditioning agents and insecticides.

What is claimed is:

1. The product obtained by reacting one mole of a compound having the formula (ROhi SH where R is a hydrocarbon radical containing 3 to 20 carbon atoms with 1 to 3 moles of a compound selected from the group consisting of alkylene oxides and glycols and containing 2 to 18 carbon atoms, and reacting four moles of the resultant compound with about one mole of P 8 the reactions being carried out at a temperature in the range of about 100 to 300 F.

2. The product obtained by reacting one mole of the product of claim 1 with 1 to 3 moles of a compound selected from the group consisting of alkylene oxides and glycols and containing 2 to 18 carbon atoms, the reaction being carried out at a temperature in the range of about 100 to 300 F.

3. The product obtained by reacting 4 moles of the product of claim 2 with about one mole of P 8 the reaction being carried out at a temperature in the range of about 100 to 300 F.

4. The product obtained by reacting one mole of the product of claim 3 with 1 to 3 moles of a compound selected from the group consisting of alkylene oxides and glycols and containing 2 to 18 carbon atoms, the reaction being carried out at a temperature in the range of about 100 to 300 F.

5. A lubricating oil composition comprising a major proportion of the product of claim 1.

6. A method for preparing compounds useful as lubricating oil components which comprises reacting separately and in a sequence one mole of a Compound I with at least the first member of a series consisting of (1) about 0.25 mole of a Compound II, (2) about 0.5 to 1.5 moles of a Compound III, (3) about 0.125 mole of Compound II and (4) about 0.25 to 0.75 mole of Compound III at a temperature in the range of about to 300 F.; wherein Compound I is the reaction product of a dithiophosphoric acid of the formula II (RO)2PSH with 1 to 3 moles of Compound III,where R is -a hydrocarbon radical containing 3 to 20 carbon atoms; Compound II is P 8 and Compound III is selected from the group consisting of alkylene oxides and glycols and contains 2 to 18 carbon atoms.

7. The product obtained by reacting separately and in a sequence one mole of a Compound I with at least the first member of a series consisting of (1) about 0.25 mole of a Compound II, (2) about 0.5 to 1.5 moles of a Compound III; (3) about 0.125 mole of Compound II and (4) about 0.25 to 0.75 mole of Compound III at a temperature in the range of about 100 to 300 R; wherein Compound I is the reaction product of a dithiophosphoric acid of the formula II (ROMPSH with 1 to 3 moles of Compound III, where R is a hydrocarbon radical containing 3 to 20 carbon atoms; Compound H is P 8 and Compound III is selected from the group consisting of alkylene oxides and glycols and contains 2 to 18 carbon atoms.

8. A lubricating composition consisting essentially of a mineral lubricating oil and from 1 to 10% by weight of a phosphorousand sulfur-containing material prepared by the process which comprises the reaction of a metal salt, wherein the metal is selected from the class consisting of alkali and alkaline earth metals and zinc, of a phosphorodithioic acid having the structure (RO PSSH wherein R is a hydrocarbon radical containing from 3 to 20 carbon atoms, with at least a substantially equivalent amount of an alkylene oxide containing from 2 to 18 carbon atoms at a temperature within the range of 100-300" F.

9. The process of preparing phosphorusand sulfurcontaining compositions which comprises the reaction of a metal salt of a phosphorothioic acid having the structure where R and R are organic radicals selected from the class consisting of alkyl, cycloalkyl, aryl, aralkyl, alkaryl, and alkenyl, and where X is sulfur, with at least a substantially equivalent amount of an organic compound selected from the class consisting of epoxy alk-anes and thioepoxy lower alkanes, the metal of said metal salt being selected from the class consisting of sodium, lithium, potassium, calcium, barium, strontium, magnesium, cadmium and zinc.

10. The process of claim 9 characterized further in that R and R of the phosphorothioic acid are saturated hydrocarbon radicals.

11. The process of claim 9 characterized further in that the phosphorothioic acid is a phosphorodithioic acid.

12. The process of claim 9 characterized further in that R and R of the phosphorothioic acid are alkyl radicals.

13. The process of claim 9 characterized further in that the second-named reactant is an epoxy alkane.

14. The process of claim 9 characterized further in that the metal salt is a salt of a polyvalent metal.

15. The process of preparing phosphorusand sulfurcontaining compositions which comprises the reaction of a metal salt of a phosphorodithioic acid having the structure PSSH where R and R are alkyl radicals with at least a substantially equivalent amount of an epoxy alkane, the metal of the said metal salt being selected from the class consisting of sodium, lithium, potassium, calcium, barium, strontium, magnesium, cadmium and zinc.

16. The process of claim 15 characterized further in that the epoxy alkane is propylene oxide.

17. The process of claim 9 characterized further in that the metal salt is a Zinc salt.

18. The product obtained by the process of claim 9.

, 19. The product obtained by the process of claim 15.

20. The process of preparing phosphorusand sulfurcontaining compositions which comprises the reaction of a metal salt of a phosphorus thioic acid in which the organic radicals are hydrocarbon radicals, said phosphorus thioic acid being a phosphorodithioic acid, with at least a substantially equivalent amount of an organic 16 compound selected from the class consisting of epoxy alkanes and thioepoxy lower alkanes, the metal of said metal salt being selected from the class consisting of sodium, li-thium, potassium, calcium, barium, strontium, magnesium, cadmium and zinc.

References Cited by the Examiner UNITED STATES PATENTS 2,063,629 12/1936 Salzberg et al 260-461 2,133,310 10/1938 Shuman 260-461 2,157,452 5/1939 Humphreys 252-466 2,178,610 11/1939 Salzberg 252-466 2,266,514 12/1941 Romieux et al. 260-461.112 2,372,244 3/1945 Adams et al. 260461.312 2,531,129 11/1950 Hook et al. 252-466 2,614,988 10/1952 Hook et al. 252-466 2,783,203 2/1957 McDermott 260-46l.ll2 2,783,204 2/1957 McDermott 260-461.112

FOREIGN PATENTS D. 18,787 3/1956 Germany.

TOBIAS E. LEVOW, Primary Examiner.

GEORGE A. GORECKI, ABRAHAM H. WINKEL- STEIN, JULIUS GREENWALD, Examiners.

G. O. ENOCKSON, W. S. BROWN, D. E. WYMAN, A.

MAZEL, I. R. PELLMAN, Assistant Examiners.

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Referenced by
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US3428662 *Jul 16, 1965Feb 18, 1969Texaco IncMethod of preparing metal dihydrocarbyl dithiophosphates
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US4882446 *Mar 3, 1988Nov 21, 1989Institut Francais Du PetroleMolybdenum complexes; extreme pressure lubricants; efficient wear resistance
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