CA1127171A

CA1127171A - Molybdenum compounds (iii)

Info

Publication number: CA1127171A
Application number: CA351,481A
Authority: CA
Inventors: John M. King; Louis Devries
Original assignee: Chevron Research and Technology Co
Current assignee: Chevron USA Inc
Priority date: 1979-06-28
Filing date: 1980-05-08
Publication date: 1982-07-06
Also published as: AU5871580A; FR2460321A1; FR2460321B1; IT1174677B; DE3021651A1; SE8004421L; IT8023091A0; GB2053268B; NL8003283A; BR8003988A; GB2053268A

Abstract

ABSTRACT OF THE DISCLOSURE
Antioxidant additives for lubricating oil are prepared by combining an acidic molybdenum compound and certain basic nitrogen compounds to form a molybdenum-containing com-position preferably in the presence of a polar promoter.

Description

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003 This invention relates to new lubricating oil 004 compositions. More specifically, it relates to new lubricating 005 oil compositions containing antioxidant molybdenum compounds.
006 BACKGROUND O~ THE INVENTION
007 Molybdenum disulfide has long been known as a 008 desirable additive for use in lubricating oil compositions.
009 However, one of its major detriments is its lack of oil 010 solubility. ~olybdenum disulfide is ordinarily finely ground 011 and then dispersed in the lubricating oil composition to impart 012 friction modifying and antiwear properties. Finely ground 013 molybdenum disulfide is not an effective oxidation inhibitor in 01~ lubricating oils.
015 As an alternative to finely grinding the molybdenum 016 disulfide, a number of different approaches involving preparing 017 salts of molybdenum compounds have been tried. One type of 018 compound which has been prepared molybdenum dithiocarbamates.
019 R~e~/resentative compositions are described in U.S. patent 020 3,~12,539, which teaches molybdenum (VI) dioxide dialkyldithio-021 carbamates; U.S. 3,509,051, which teaches sulfurized oxymolyb-022 denum dithiocarbamates; and U.S. 4,098,705, which teaches 023 sulfur containing molybdenum dihydrocarbyl dithiocarbamate 024 compositions.
025 An alternative approach is to form dithiophospbates 026 instead of dithiocarbamates. Representative of this type of 027 molybdenum compound are the compositions described in U.S.
028 3,494,866, such as oxymolybdenum diisopropylphosphorodithioate.
029 U.S. 3,184,410 describes certain dithiomolybdenyl 030 acetylacetonates for use in lubricating oils.
031 Braithwaite and Greene in Wear, 46 tl978) 405-432 032 describe various molybdenum-containing compositions for use in 033 motor oils.
034 U.S. Patent 3,349,108 teaches a molybdenum trioxide 035 complex with diethylenetriamine for use as an additive for 036 molten ~teel.
037 ~ussian patent 533,625 teaches lube oil additives llZ'7171 prepared from ammonium molybdate and alkenylated polyamines.
Another way to incorporate molybdenum compounds in oil is to prepare a colloidal complex of molybdenum disulfide or oxysulfides dispersed using known dispersants. United States patent 3,223,625 describes a procedure in which an acidic aqueous solution of certain molybdenum compounds is prepared and then extracted with a hydrocarbon ether dispersed with an oil soluble dispersant and then freed of the ether. United States 3,281,355 teaches the preparation of a dispersion of molybdenum disulfide by preparing a mixture of lubricating oil, dispersant, and a molybdenum compound in water or Cl 4 aliphatic alcohol, contacting this with a sulfide ion generator and then removing the solvent. Dispersants noted to be effective in this procedure are petroleum sulfonates, phenates, alkylphenate sulfides, phosphosulfurized olefins and combinations thereof.
It has now been found that a lubricating oil additive can be prepared by combining an acidic molybdenum compound and certain basic nitrogen-containing compositions.
; According to the invention, there is provided a process for preparing a molybdenum-containing composition which comprises combining an acidic molybdenum compound and a basic nitrogen compound selected from the group consisting of a carboxylic acid amide, Mannich base, phosphonamide, thiophosphonamide, phosphoramide, and dispersant viscosity index improvers to form a molybdenum containing complex. The process if preferably carried out in the presence of a polar promoter.
Lubricating oil compositions containing the additive disclosed herein are effective as either fluid and grease compositions (depending upon the specific additive or additives employed) for inhibiting oxidation, imparting antiwear and extreme pressure properties t and modifying the friction proper-ties of the oil which may, when used as a crankcase lubricant, llZ7171 lead to improved mileage for the vehicle being lubricated with a lubricating oil of this invention.
The precise molecular formula of the molybdenum com-positions prepared in the process of this invention is not known with certainty; however, they are believed to be compounds in which molybdenum, whose valences are satisfied with atoms of oxygen or sulfur is either complexed by or the salt of one or more nitrogen atoms of the basic nitrogen containing composition used in the preparation of these additives.

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The molybdenum compounds used to prepare the additives for com-positions of this invention are acidic molybdenum compounds. By acidic is meant that the molybdenum compounds will react with a basic nitrogen compound as measured by ASTM test D-664 or D-2896 titration procedure. Typically these molybdenum compounds are hexavalent and are represented by the following compositions: lybdic acid, ammonium molybdate, sodium molybdate, potassium molybdate and other alkali metal molybdates and other molybdenum salts such as MoOC14, MoO2Br2, Mo203C16, molybdenum trioxide or similar acidic molybdenum compounds. Preferred acidic molybdenum compounds are molybdic acid, ammonium lybdate, and alkali metal molybdates. Particularly preferred are molybdic acid and ammonium molybdate.
The polar promoter which is preferably used in the process of this invention is one which facilitates the interaction between the acidic moly-bdenum compound and the basic nitrogen compound. A wide variety of such promoters may be used. Typical promoters are 1,3-propanediol, 1,4-butanediol, diethylene glycol, butyl cellosolve, propylene glycol, 1,4-butyleneglycol, methyl carbitol, ethanolamine, diethanolamine, N-methyl-diethanol-amine, dimethyl formamide, N-methyl acetamide, dimethyl acetamide, methanol, ethylene glycol, dimethyl sulfoxide, hexamethyl phosphoramide, tetrahydrofuran and water. Preferred are water and ethylene glycol. Particularly preferred is water.
While ordinarily the polar promoter is separately added to the reaction mixture, it may also be present, particularly in the case of water, as a component of non-anhydrous starting materials or as waters of hydration in the acidic molybdenum compound, such as (NH4)6Mo7O24.4 H2O. Water may also be added as ammonium hydroxide.
The basic nitrogen compounds are selected from those having a basic B nitrogen content as measured by ASTM D-664 or D-2896. It is preferred that they be oil-soluble. These compositions are selected from -WWiA~
carboxylic acid amides, Mannich bases, phosphonamides, thiophosphonamides, phosphoramides, dispersant 1~27171 viscosity index improvers, and mixtures thereof. These basic nitrogen containing compounds are described below (keeping in mind the reservation that each must have at least one basic nitrogen). Any of the nitrogen-containing compositions may be after-treated with e.g., boron, using procedures well known in the art so long as the after-treated product continues to contain basic nitrogen. These after- treatments are particularly applicable to succinimides and Mannich base compositions.
Carboxylic amide compositions that are suitable starting materials for preparing the products of this invention, are known in the art. Typical of such compounds are those disclosed in United States patent 3,405,064. These compositions are ordinarily prepared by reacting a carboxylic acid or anhydride ester thereof, having at least 12 to about 350 aliphatic carbon atoms in the principal aliphatic chain and, if desired, having pendant aliphatic groups to render the molecule oil soluble which is with an amine or a hydrocarbyl polyamine, such as an ethylene amine, to give a mono or polycarboxylic acid amide. Preferred are those amides prepared from (1) a carboxylic acid of the formula R2COOH, where R2 is C12 20 alkyl or a mixture of this acid with a polyisobutenyl carboxylic ac~d in which the polyisobutenyl group contains from 72 to 128 carbon atoms and (2) an ethylene amine, especially triethylene tetraamine or tetraethylene pentaamine or mixtures thereof.

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Another class of compounds useful for supplying basic nitrogen are the Mannich base compositions. The Mannich base compositions are prepared from a phenol or Cg 200 alkylphenol, an aldehyde, such as formaldehyde or formaldehyde precursor such a para-formaldehyde, and an amine compound.
The amine may be a mono or polyamine and typical compositions are prepared from an alkylamine, such as methylamine, or an ethylene amine, such as diethylene triamine, or tetraethylene pentaamine and the like. The phenolic material may be sulfurized and preferably in dodecylphenol or a C80 100 alkylphenol. Typical Mannich bases which can be used in this invention are disclosed in United States patents 3,649,229, 3,368,972, 3,539,663 and 4,157,309. The last specification discloses Mannich bases prepared by reacting an alkylphenol having at least 50 carbon atoms, preferably 50 to 200 carbon atoms with formaldehyde and an alkylene polyamine HN(ANH)nH
where A is a saturated divalent alkyl hydrocarbon of 2 to 6 carbon atoms and n is 1-10 and where the condensation product of said alkylene polyamine may be further reacted with urea or thiourea. The utility of these Mannich bases as starting materials for preparing lubricating oil additives can often be significantly improved by treating the Mannich base using conventional techniques to introduce boron into the composition.

B

The phosphoramides and phosphonamides, such as those disclosed in United States patents 3,909,430 and 3,968,157, may be prepared by forming oil soluble phosphorus compound having at least one P-N bond~ They can be prepared, for example, by reacting phosphorus oxychloride with a hydrocarbyl diol in the presence of a monoamine or by reacting phosphorus oxychloride with a difunctional secondary amine and a mono-functional amine. Thiophosphoramides can be prepared by reacting an unsaturated hydrocarbon compound containing from

2 to 450 or more carbon atoms, such as polyethylene, poly-isobutylene, polypropylene, ethylene, l-hexene, 1,3-hexadiene, isobutylene, 4-methyl-1-pentene, and the like, with phosphorus pentasulfide and nitrogen-containing compound as defined above, particularly an alkylamine, alkyldiamine, alkylpolyamine, or an alkyleneamine, such as ethylene diamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentaamine, and the like.
Another class of nitrogen-containing compositions useful in preparing the molybdenum compositions of this invention includes the so-called dispersant viscosity index improvers (VI improvers). These VI improvers are commonly prepared by functionalizing a hydrocarbon polymer, especially a polymer derived from ethylene and/or propylene, optionally containing additional units derived from one or more co-monomers such as ~2'7171 oo 1 -7 -002 alicyclic or aliphatic olefins or diolefins. The functionaliza-003 tion may be carried out by a variety of processes which ù04 introduce a reactive site or sites which usually has at least 005 one oxygen atom on the polymer. The polymer is then contacted 006 with a nitrogen-containing source to introduce nitrogen-007 containing functional groups on the polymer backbone. Commonly 008 used nitrogen sources include any basic nitrogen compound, 009 especially those nitrogen-containing compounds and compositions 010 described herein. Preferred nitrogen sources are alkylene 011 amines, such as ethylene amines, alkyl amines, and Mannich 012 bases.
013 Preferred basic nitrogen compounds for use in this 014 invention are succinimides, carboxylic acid amides, and ~annich 015 bases.
016 The process of this invention may be carried out by 017 combining the acidic molybdenum precursor as described above, 018 with a basic nitrogen-containing composition as described above 019 preferably in the presence of a polar promoter. The reaction 020 is ordinarily carried out at atmospheric pressure; however, 021 higher or lower pressures may be used, if desired, using 022 methods that are well-known to those skilled in the art. A
023 diluent may be used to enable the reaction mixture to be 024 eficiently stirred. Typical diluents are lubricating oil and 025 liquid compounds containing only carbon and hydrogen. If the 026 mixture is sufficiently fluid to permit stirring, no diluent is 027 necessary. A diluent which does not react with the molybdenum 028 containing compound is desirable.
029 In the reaction mixture, the ratio of molybdenum 030 compound to basic nitrogen compound is not critical; however, 031 as the amount of molybdenum with respect to basic nitrogen, 032 increases, the filtration of the product becomes more diffi-033 cult. Since the molybdenum component probably oligomerizes, it 034 is ad~7antageous to add as much molybdenum as can easily be 035 maintained in the composition. Usually the reaction mixture 036 will have charged to it from 0.01 to 2.00 atoms of molybdenum 037 per basic nitrogen atom. Preferably from 0.4 to 1.0, and most 7~

001 ~-002 preferably from 0.4 to 0.7, atoms of molybdenum per atom of 003 basic nitrogen is added to the reaction mixture.
004 The polar promoter, which is preferably used, is 005 ordinarily present in the ratio of 0.1 to S0 mols of water per 006 mol of molybdenum. Preferably from 0.5 to 25 and most 007 preferably 1.0 to 15 mols of the promoter is present per mol of 008 molybdenum.
009 The lubricating oil compositions of this invention 010 can be prepared by admixing, by conventional techniques, the 011 appropriate amount of the molybdenum-containing composition 012 with a lubricating oil. The selection of the particular base 013 oil depends on the contemplated application of the lubricant 014 and the presence of other additives. Generally, the amount of 015 the molybdenum containing additive will vary from 0.l05 to 15%
016 by weight and preferably from 0.2 to 10~ by weight.
017 The lubricating oil which may be used in this 018 invention includes a wide variety of hydrocarbon oils, such as 019 naphthenic bases, paraffin bases and mixed base oils as well as 020 synthetic oils such as esters and the like. The lubricating 021 oils may be used individually or in combination and generally 022 have a viscosity which ranges from 50 to 5,000 SUS and usually 023 from 100 to 15,000 SUS at 38C.
024 In many instances, it may be advantageous to form 025 concentrates of the molybdenum containing additive within a 026 carrier liquid. These concentrates provide a convenient method 027 of handling and transporting the additives before their subse-028 quent dilution and use. The concentration of the molybdenum-029 containing additive within the concentrate may vary from 0.25 030 to 90% by weight although it is preferred to maintain a con-031 centration between 1 and 50% by weight. The final application 032 of the lubricating oil compositions of this invention may be in 033 marine cylinder lubricants as in crosshead diesel engines, 034 crankcase lubricants as in automobiles and railroads, lubri-035 cants for heavy machinery such as steel mills and the like, or 036 as greases or bearings and the like. Whether the lubricant is 037 fluid or a solid will ordinarily depend on whether a thickening 11~717~

001 ~9 ~

002 agent is present. Typical thickening agents include polyurea 003 acetates, lithium stearate and the like.
004 If desired, other additives may be included in the lubri-005 cating oil compositions of this invention. These additives 006 include antioxidants or oxidation inhibitors, dispersants, rust 007 inhibitors, anticorrosion agents and so forth. Also anti-foam 008 agents stabilizers, anti-stain agents, tackiness agents, anti-009 chatter agents, dropping point improvers, anti-squawk agents, 010 extreme pressure agents, odor control agents and the like may 011 be included.
012 Certain molybdenum products that can be prepared by 013 the process of invention also find utility in making brake 014 lining materials, in high-temperature structural materials, in 015 iron and steel alloys, in cladding materials, in electroplating 016 solutions, as components for electrical discharge machine 017 electrodes, as fuel additives, in making self-lubricating or 018 wear-resistant structures, as mold release agents, in composi-019 tions for phosphatizing steel, in brazing fluxes, in nutrient 020 media for microorganisms, in making electrosensitive recording 021 material, in catalysts for refining coal, oil, shale, tar 022 sands, and the like or as stabilizers or curing agents for 023 natural rubber or polymers.
024 The following examples are presented to illustrate 025 the operation of the invention and are not intended to be a 026 limitation upon the scope of the claims.
027 Example 1 028 To a 1 liter flask was added 290 grams of a solution 029 of 45% concentrate in oil of the succinimide prepared from 030 polyisobutenyl succinic anhydride and tetraethylene pentaamine 031 and having a number average molecular weight for the polyiso-032 butenyl group of about 980, 28.8 grams of molybdenum trioxide 033 as a dry powder, 9.6 ml of water and 150 ml of hydrocarbon 034 thinner. The reaction mixture, which was a murky yellow-green 035 suspension, was heated to 65C and held at this temperature for 036 3-1/2 hours. The temperature was then raised to 150C to 037 remove water and held at this temperature for one hour. Then llZ7171 002 50 ml of hot hydrocarbon thinner was added and the reaction 003 mixture was filtered through diatomaceous earth. The filter 004 cake was washed with 100 ml of hot hydrocarbon thinner and a 005 light blue residue remained on the filter cake. The reaction 006 mixture was then stripped to 160C at 20 mm Hg to yield a 007 product containing 4.16~ molybdenum, 3.4896 oxygen, and 1.97%
008 nitrogen.
009 Example 2 010 To a l-liter flask was added 290 grams of the 011 succinimide described in Example 1 and 150 ml of hydrocarbon 012 thinner. The mixture was heated to 65C and then 28.8 grams of 013 molybdenum trioxide and 50 ml of water was added. The tempera-014 ture of the mixture was maintained at 65C for 1/2 hour and 015 then increased to 155C over a period of one hour and main-016 tained at 155 to 160C for one hour. To this mixture was 017 added 50 ml hydrocarbon thinner and the product was filtered 018 through diatomaceous earth. The filtrate was stripped to 160C
019 at 20 mm Hg to yield 311 grams of product containing 6.18%
020 molybdenum, 4.17% oxygen and 1.94% nitrogen.
021 Example 3 022 To a 3-liter flask was added 1160 9 o~ the succini-023 mide described in Example 1 and 800 ml hydrocarbon thinner.
024 The temperature of the mixture was increased to 75C and 200 ml 025 water and 116 g MoO3 were added and the mixture was stirred at 026 97C for 3 hours. It was then stripped at 188C. After 027 cooling to 130C, 100 ml hydrocarbon thinner and 25 g diatoma-028 ceous earth were added and the mixture was filtered through 029 diatomaceous earth and then stripped at 180C and 20 mm Hg.
030 The product contained 5.84% molybdenum and 1.92~ nitrogen.
031 Example 4 032 To a l-liter flask containing 290 g of the succini-033 mide described in Example 1 and 200 ml hydrocarbon thinner at 034 65C was added 50 ml water and 589 MoO3. The mixture was 035 stirred at reflux for 4.5 hours and then stripped at 198-209C.
03~ The product was diluted with hydrocarbon thinner and then 037 filtered through diatomaceous earth to yield 332 9 of product llz7ln containing 10.1% molybdenum (by X-ray fluorescence), 9.71% molybdenum ~by neutron activation) and 5.97% oxygen ~by neutron activation).
Example 5 Lubricating oil compositions containing the additives prepared according to this invention have been tested in a variety of tests. Reported below are results from certain of these tests which are described as follows.
In the Oxidator B test the stability of the oil is measured by the time required for the consumption of 1 liter of oxygen by 100 grams of the test oil at 340F. In the actual test, 25 grams of oil is used and the results are corrected to 100-gram samples. The catalyst which is used at a rate of 1.38 cc per 100 cc oil contains a mixture of soluble salts pToviding 95 ppm copper, 80 ppm iron, 4.8 ppm manganese, 1100 ppm lead, and 49 ppm tin.
The results of this test are reported as hours to consumption of 1 liter of oxygen and our measure of the oxidative stability of the oil.
The anti-corrosion properties of compositions can be tested by their performance in the CRC L-38 bearing corrosion test. In this test, separate strips of copper and lead are immersed in the test lubricant and the lubricant is heated for 20 hours at a temperature of 295F. The copper strip is weighed and then washed with potassium cyanide solution to remove copper compound deposits. It is then re-weighed. The weight losses of the two strips are reported as a measure of the degree of corrosion caused by the oil.
The copper strip test is a measure of corrosivity toward non-ferrous metals and is described as ASTM Test Method D-130. Anti-wear properties are measured by the 4-ball wear and the 4-ball weld tests. The 4-ball wear test is described in ASTM D-2266 and the 4-ball weld test is ASTM D-2783. The data for some of the tests run on compositions of this in~ention is reported in the Table below.

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The formulations tested contained, in neutral oil, 3.5% of a 50%
in oil solution of succinimide, 22 mmols/kg of the molybdenum product being tested, 20 mmols/kg sulfuri~ed calcium phenate, 30 mmols/kg overbased magnesium sulfonate, 5.5% viscosity index improver and, if necessary, additional succinimide to bring the total nitTogen content of the finished oil to 2.14%.

~27~71 TABLE

Product Oxidator ASTM ASTM L-38 D-130 of B, hrs. D-2266, D-2783 Cu, mg Pb, mg Example mm kg 1 7.7 .39 165 16.3 10.1 ; 2 8.0 ~ 3 8.5 lA
: 4 I Fortulation tested was 4~ ~t. = Iybdenum oo Found in neutral oil.

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Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for preparing a molybdenum-containing com-position which comprises combining an acidic molybdenum compound and a basic nitrogen compound selected from the group consisting of a carboxylic acid amide, Mannich base, phosphonamide, thio-phosphonamide, phosphoramide, and dispersant viscosity index improvers to form a molybdenum containing complex.

2. The process of Claim 1 wherein the acidic molybdenum compound is selected from molybdic acid, ammonium molybdate, and alkali metal molybdates.

3. The process of Claim 2 wherein said acidic molybdenum compound is molybdic acid or ammonium molybdate, and said basic nitrogen compound is a carboxylic acid amide, or a Mannich base prepared from a C9-200 alkylphenol, formaldehyde, and an amine.

4. The process of Claim 3 wherein said basic nitrogen compound is a carboxylic acid amide prepared from one or more carboxylic acids of the formula R2-COOH, wherein R2 is C12-350 alkyl or C12-350 alkenyl and a hydrocarbyl polyamine.

5. The process of Claim 4 wherein R2 is C12-20 alkyl or C12-20 alkenyl and the hydrocarbyl polyamine is tetraethylene pentaamine or triethylene tetraamine.

6. The process of Claim 3 wherein said basic nitrogen compound is the Mannich base prepared from dodecyl phenol, formaldehyde, and methylamine.

7. The process of Claim 3 wherein said Mannich base is prepared from a C80-100 alkylphenol, formaldehyde, and triethylene tetraamine or tetraethylene pentaamine, or mixtures thereof.

8. The process of Claim 1 wherein said reaction is carried out in the presence of a polar promoter.

9. The process of Claim 8 wherein said polar promoter is water.

10. The product prepared by the process of Claim 1.

11. The product prepared by the process of claim 8.

12. The product prepared by the process of claim 9.

13. A lubricating oil composition comprising an oil of lubricating viscosity and from 0.05 to 15% by weight of the product of Claim 10.

14. A lubricating oil concentrate composition comprising an oil of lubricating viscosity and from 15 to 90% by weight of the product of Claim 10.

15. A lubricating oil composition comprising an oil of lubricating viscosity and from 0.05 to 15% by weight of the product of Claim 11.

16. A lubricating oil composition comprising an oil of lubricating viscosity and from 0.05 to 15% by weight of the product of Claim 12.

17. A lubricating oil concentrate composition comprising an oil of lubricating viscosity and from 15 to 90% by weight of the product of Claim 11.

18. A lubricating oil concentrate composition comprising an oil of lubricating viscosity and from 15 to 90% by weight of the product of Claim 12.