CA1169044A

CA1169044A - Lubricating oil composition containing sediment- reducing additive

Info

Publication number: CA1169044A
Application number: CA000375185A
Authority: CA
Inventors: Max J. Wisotsky
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1980-05-08
Filing date: 1981-04-10
Publication date: 1984-06-12
Also published as: EP0039998A1; DE3163160D1; EP0039998B1; JPS573893A

Abstract

ABSTRACT OF THE DISCLOSURE
Lubricating oil compositions which contain polycarboxylic acid-glycol esters as friction modifiers in combination with hydrocarbon soluble alkenyl suc-cinimide dispersants with reduced tendency toward forma-tion of sediment upon storage through addition of small proportions of polyol or. polyol anhydride partial ester of a fatty acid or an ethoxylated fatty acid, amine or amide stabilizer. Glycerol oleates are preferred stabi-lizer additive.

Description

0 4 ~

This invention relates to storage stable lubri-~A~ cating oil compositions containing an additive package which provides both dispersant and friction modification 6 properties. More particularly, this invention relates 7 to a formulated lubricating oil composition containing a 8 polycarboxylic acid-glycol ester friction modifier and g an alkenyl succinimide dispersant having a reduced ten-dency to form sediment upon storage.
11 Lubricating oil compositions which contain 12 polycarboxylic acid-glycol esters as friction reducing 13 components are known in the art and are disclosed, for ex- -14 ample, in U.S. Patent 4,105,571 issued August 8, 1978 to Shaub et al. The oil-soluble alkenyl succinimide disper-16 sants, particularly polyisobutenyl succinimide disper-17 sants, are well known and are disclosed in U.S. Patent 18 3,172,892, issued March 9, 1965 to Le Suer et al., and 19 U.S. Patent 3,933,659, issued January 20, 1976 to Lyle et al.
21 It is known that lubricating oil compositions 22 containing the aforesaid alkenyl succinimide dispersants 23 and polycarboxylic acid-glycol ester friction modifiers 24 offer a ~umber of advantageous properties, however, a problem frequently encountered is the tendency of appre-26 ciable quantities of sediment to form upon storage of 27 formulated compositions containing these additives and 28 other conventionally employed additives, especially metal ~9 containing additives. The present invention deals with this problem by providing additives found effective in 31 stabilizing such compositions against sediment formation, 32 the stabilizer additives being certain polyol-fatty acid 33 esters or ethoxylated fatty acids, amines or amides.
34 Shaub et al in U.S. Patent 4,105,571 disclose 35 that incompatibility problems of zinc dihydrocarbyl di-36 thiophosphate and glycol ester friction-reducing compon-37 ents can be resolved by pre-dispersing ei*her component 38 in an ashless dispersant prior to combining them in the . : , ~7 ~6~t~

1 lubricating o~l formulation; however, 5haub et al do note

2 that formulations containing dispersants based on a re-

3 action product of polyisobutenyl succinic anhydride and

4 polyamine exhibited evidence of storage instability and suggested that an increased amount of dispersant may be 6 necessary to maintain compatibility. The present inven-7 tion deals with this problem by providing a stabilizer 8 additive found effective in compatibilizing the composi-g tions disclosed herein or enhancing ~he compatibility of said components.
11 In accordance with the present invention, there 12 are provided storage stable lubricating oil compositions 13 having a reduced tendency to form sediment comprising:
14 (a) a polycarboxylic acid-glycol ester fric-tion reducing component, 16 (b) an oil-soluble alkenyl succinimide or bor-17 ated alkenyl succinimide dispersant, and 18 (c) an oil-soluble stabilizer additive being 19 a polyol or polyol anhydride partial ester of a C8-C22 fatty acid or an ethoxylated 21 fatty acid, fatty amine or fatty amide, in 22 an amount effective to reduce the tendency 23 of said lubricating oil formulation to 24 form sediment.
Tha term lubricating oil composition as used 26 herein is meant to refer to fully formulated compositions 27 intended for use, for example as crankcase motor oils~
28 which contain a number of conventionally used additives 29 in the usual amounts especially oxidation inhibitors, rust inhibitors, viscosity index improvers, such as ole-1 fin copolymers, pour depressants, oil-soluble detergent 32 additives such as the neutral and basic metal phenates, 33 sulfurized phenates and sulfonates, such as the calcium and magnesium sulfurized phenates and sulfonates,as well as the zinc ~lkyl dithiophosph tes which are useful anti-oxidant 36 and anti-w~ additives. It is ~ ieve~ that the metal con-' ' -690~L'1 1 taining additi~es such as the normal and basic metal sul-fonates, phenates and sulfurized phenates and metal di-3 thiophosphates contribute to the tendency o~ lubricating 4 oil compositions to orm sediment when in the presence of the ester friction reducing components and alkenyl suc-6 cinimide dispersant. The metal phenates and sulfonates 7 noted above are typically employed in amounts of from 8 about 2 to 5 weight percent and metal dithiophosphates 9 are usually found in fully formulated lubricating oil com-positions in amounts from about l to 3 weight percent.
ll The friction reducing esters are generally de-12 rived from the esterification of a polycarboxylic acid 13 with a glycol and may be partial esters or diesters of 14 the ~ormulas:
lS HO-R'-OOC-R-COOH and HO-R ' -OOC-R-COOR" -OH
16 wherein R is the hydrocarbon radical of the acid and R' 17 and R" is either the hydrocarbon radical of an alkane 18 diol or the oxy-alkylene radical from an oxa-alkane diol 19 as defined hereinbelow. The polycarboxylic acid may be an aliphatic saturated or unsaturated acid and will gen~
21 eralIy have a total of about 24 to 90, preferably about 22 24 to 60, carbon atoms and about 2 to 3, preferably about 23 2, carboxylic acid groups with at least about 9 carbon 24 atoms, preferably about 12 to 42, especially 16 to 22 car-bon atoms between the carboxylic acid groups. Generally 26 about 1-3 moles of glycol, preferably 1-2 moles of glycol, 27 are used per mole of acid to pro~ide either a complete or 28 partial ester.
: ~ :
29 Also, esters can be obtained by esteri~ying a ~30 dicarboxylic acid or mixture of such acids with a diol 1 or mixture of diols, in which case R would then be the 32 hydrocarbon radical of the dicarboxylic acid and R' and R" would be the hydrocarbon radicals associated with the diol or diols.
The friction reducing esters are typically used 6 in amounts ranging ~rom about 0.01 percent to 2 percent : ~ :
: ~:

:
. . , ~ .

~ 3 ~0~'1 1 by weight, more preferably 0.05 to 0.5 percent by weight 2 based upon the overall weight of the lubricating oil com-3 position, more preferably, formulations containing 0.1 4 to 0.3 weight percent are highly effective.
Especially preferred are the dimer acid ester 6 friction reducing esters. The term dimer acid used here-7 in is meant to refer to those substituted cyclohexene di-8 carboxylic acids formed by a Diels-Alder-type reaction 9 which is a thermal condensation of C18-C22 unsaturated fatty acids, such as tall oil fatty acids, which ~ypical 11 ly contain about 85 to 90 percent oleic or linoleic acids.
12 Such dimer acids typically contain about 36 carbon atoms.
13 The dimer acid structure can be generalized as follows-IRl 6 ~ ~ 2 18 iR ~ 3 with two of the R groups being carboxyl groups and two be-21 ing hydrocarbon groups depending upon how the condensation 22 of the carboxylic acid has occurred. The car~oxyl grouE6 23 can be -(CH2)gCOOH;-CH=CH(CH2)8COOH;-(CH2)7COOX;
24 -CH2-CH=CH(CH217COOX;~CH=CH(CH2~7COOH and t~e h~drocarbon 25 terminating group can ~e represented b~: C~3(CH2)4-~;
26 (CH3(cH2)5-;cH3 ~CH2 ) 7-jCH3 (CH.2 ~ 4CH- CH - ; CH:3 ~CH2)4CH-CH-CH
27 and the like. The dimer o~ linoleic acid which is the 28 preerred embodiment can be exoressed in the ~ollowinq 2 9 formula:

31 (CH2)7COOH
32 [hfCH=CH (CH2) 7COOH
`f \ ( CH 2 ) 5CH 3 3 5 (CH2 ) 5CH3 _4_ .. . . . .
. : :'. - . ' : -.

0 ~ '1 1 Also the term dimer acid as used herein neces-2 sarily includes products containing up to about 24 per-3 cent by weight trimer, but more typically about 10 per-4 cent by weight trimer since, as is well known in the art,

5 the dimerization reaction provides a product containing

6 a trimer acid having molecular weight of about three times

7 the molecular weight to the starting fatty acid.

8 The polycarboxylic acids or dimer acids noted

9 above are esterified with a glycol, the glycol being an

10 alkane diol or oxa-alkane diol represented by the formula ~ O(~CHCH2O~xH wherein R i5 H or CH3 and x is about 2 to 12 100, preferably 2 to 25 with ethylene glycol and diethy-13 lene glycol particularly preferred. A preferred embodi-14 ment is formation of the ester with about 1 to 2 moles of 15 glycol per mole of dimer acid or polycarboxylic acid, 16 such as the ester of diethylene glycol with dimerized lin-17 oleic acid.
18 The oil-soluble alkenyl succinimide ashless dis-19 persants are those formed by reacting a polyalkenyl suc-cinic acid or anhydride with a polyalkyleneamine. Pre-21 ferably the alkenyl group-is derived from a polymer of a 22 C2 to C5 mono-olefin, especially a polyisobutylene where 23 the polyisobutenyl group has a number average molecular 24 weight of about 70Q to about 5,000, more preferably about 900 to 1,500. The polyamines may be represented by the 26 formula NH2(CH2)n-~NH(CH2)n)m-NH2 wherein n is 2 to 3 and 27 m is 0 to 10. Illustrative are ethylene diamine, diethy-2~ lene triamine, triethylene tetramine, tetraethylene pent-29 amine, which is preferred, pentaethylene hexamine and the like, as well as mixtures of such polyamines. Theseamines 31 are reacted with the alkenyl succinic acid or anhydride in 32 ratios of about 1:1 to 10:1 moles of alkenyl succinic 33 acid or anhydride to polyamine.
34 The borated alkenyl succinimide dispersants are also well known in the art as disclosed in U.S. Patent 36 3,254,025. These borated derivatives are provided by 37 treating the alkenyl succ~nimide with a boron compound '' 0 ~ '1 1 selected from the class consisting of boron oxides, boron 2 halides, boron acids and esters thereof in an amount to 3 provide from about 0.1 atomic proportion of boron to about 4 10 atomic proportions of boron for each atomic proportion of nitrogen in the dispersant. The borated product will 6 generally contain about 0.1 to 2.0, preferably 0.2 to 0O8 7 weight percent boron based upon ~he total weight of the 8 borated dispersant. The boron is considered to be present 9 as dehydrated boric acid polymers attaching as the metabor-ate salt of the imide. The boration reaction is readily

11 carried out by adding from about 1 to 3 weight percent,

12 based on the weight of dispersant, of said boron compound,

13 preferably boric acid, to the dispersant as a slurry in

14 mineral oil and heating with stirring as from about 135C
to 165C for from 1 to 5 hours followed by ~itrogen strip-16 ping and filtration of the product.
17 These alkenyl succinimide ashless dispersants and 18 borated derivatives thereof are used customarily in lubri-19 cating oil compositions in amounts ranging from 0.7 to 10 percent, preferably 0.5 to 5 percent, by weight based upon 21 the total weight of the finished composition.
22 One category of the stabilizer additives of the 23 present invention may generally be defined as the polyol 24 ester of a C8-C22 fatty acid, partial ester meaning at least one hydroxy group remains unreacted. Preferably 1 26 to 3 free OH groups are present such as an average of 1.5 27 to 2.5 free hydroxy groups. Such compounds are, per se, 28 known in the art and it is only their use as a stabilizing 29 agent in a formulated composition containing both the ester friction modifier and alkenyl succinimide dispersant or 31 borated dispersant derivative thereof which is the basis 32 Of the present invention.
33 Suitable polyols for preparing the ester stabili-34 zer of the present invention are those polyhydric alcohols such as glycerol, diglycerol, and the sugar alcohols, 36 which may be represented in the formula CH2oH(cHoHlmcH2oH
37 where m is one t~ five as well as the polyol anhydrides ' .

I ~ 0 ~ '1 1 thereof. Preferred are the esters of glycerol itself, 2 C3H5(O~)3, sorbitol and sorbitol anhydride (sorbitan).
3 Esters based upon relatively higher, i.e~, C12-C22, fatty 4 acids or mixtures of fatty acids are more preferable, such 5 as, the tall oil fatty acids. The fatty acids may be satu-6 rated or unsaturated. Especially preferred are glycerol 7 and sorbitan parti~l esters of liquid C18-C22 unsaturated 8 fatty acids such as oleic, linoleic, and palmitoleic fat-9 ty acids and mixtures of such acids.
Ethoxylated oil-soluble fatty acids, fatty acid 11 amines, and amides have also been found suitable for use 12 as sediment-reducing stabilizer additives in the composi-]3 tions of the present invention. Useful products are those 14 oil-soluble ethoxylated additives of about C8 to C22 satu-

15 rated or unsaturated fatty acids, amines or amides. The

16 de~ree of ethoxylation of such products is about 2 to 30

17 moles, preferably 1 to 5 moles of ethylene oxide per mole

18 of fatty acid, amine or amide, so that the products retain

19 oil solubility. Derivatives of liquid unsaturated C12-C22 fatty acids are preferred, such as oleic, linoleic, pal-21 mitoleic and mixtures thereof, such as the tall oil fatty 22 acids and vegetable oil fatty acids, for example, those 23 derived from cottonseed and soybean oils which contain 24 major amounts of unsaturated C18 fatty acids and which are generally liquid at room temperature.
26 Of this category, the oil-soluble ethoxylated 27 fatty acid amines are a preferred embodiment including 28 both fatty acid monoamines and diamines, such as, oil-sol-29 uble polyethoxylated (1-3 moles of ethylene oxide) coco-amine derived from mixed coconut oil fatty acids (C12-C15) 31 and tallow diamine ethoxylates ~1-3 moles of ethylene 32 oxide) derived from mixtures of predominantly C16-C18 fatty 33 acids.
34 The quantity of sediment-reducing amount of ad-ditive stabilizer of the present invention which is used 36 in a lubricating oil formulation is best expressed rela-37 tive to the amount of the ester friction-reducing additive '3 0 ~ '1 l which is present. The broad ratio is about 2 to 20 parts 2 bv weight of additive stabilizer per part by weight of 3 ester friction-reducing additive with the preferred ratio 4 being about 2 to 12 parts by weight of stabilizer additive 5 per part by weight of friction reducing ester.
6 While the method of addition of the stabilizer 7 additive is largely a function of the exact composition of 8 the total finished formulation, it is generally preferable 9 to provide a blend of stabilizer additive, friction-reduc-ing ester and dispersant by admixing same at moderately ll elevated temperatures, not greater than 150F, and incor-12 porating this blend into the lubricating oil formulation 13 either prior to or subse~uent to the addition of other ad-14 ditives in accordance with blending techniques known in 15 the art.
16 The lubricating oil base stock employed herein 17 are those customarily used: The term lubricating oil in-18 cludes not only the petroleum hydrocarbon paraffinic, l9 naphthenic, and aromatic oils of lubricating viscosity,but

20 also synthetic oils, such as, polyethylene oils, esters of

21 dicarboxylic acids, complex ester oils, polyglycol, and

22 alcohol alkyl esters of carbonic or phosphoric acids, poly-

23 silicones, fl ~ ohydrocar~on oils and the like. Preferred

24 base stocks are mineral hydrocarbon oils of a paraffinic

25 nature, especially those having a viscosity of about 20 to

26 100 cS min. (100F) and blends of such mineral paraffinic

27 oils.

28 The stabilizer additives of the present invention

29 are generally effective in substantially eliminating all

30 but traces of sediment when the lubricating oil formulation

31 contains the usually preferred amounts of friction reduc-2 ing ester component, that is, about 0.05 to 0.3 weight per-33 cent and ~herefore, formulations prepared in accordance 34 with the present invention which contain these amounts of friction-reducing ester component are particularly pre-36 ferred. For formulations containing more than about 0.3 37 weight percent of ester component, there will be in most 1 cases a substantial reduction in the amount of sediment 2 observed after centrifuging as opposed to a complete eli-3 mination to trace levels.
4 Examples 1-4 Lubricating oil formulations were prepared con-6 taining the dimer acid ester friction modifier and the 7 alkenyl succinimide dispersant to which were added the 8 sediment-reducing additives of the present invention. ~he 9 formulation was a standard lOW~SAE quality automotive lub-ricating oil composition con~aining a zinc dialkyl dithio-11 phosphate, overbased metal sulfonate, rust inhibitor, and 12 VI improver in typical proportions. At this point the 13 formulation was storage stable with no evidence of sed~ent 14 formation. To this was added 0.1 percent by weight of a 15 friction modifier being the ester of a dimerized linoleic 16 acid and diethylene glycol and 5 weight percent of the re-17 action product of 2.1 moles polyisobutenyl (Mn=1300) suc-18 cinic anhydride (Sap. No. 103) and 1 mole of alkylene poly-19 amine to provide the 3ase Formulation. The polyamine had r~ 20 a composition approximating tetraethylene pentamine and 21 is available under the trade ~ "DOW E-100" from Dow 22 Chemical Company, Midland, Michigan. Samples (100 ml.,cali-23 brated test tube) of this base formulation were centrifuged 24 for 8, 16 and 24 hours at 1900 r.p.m. at room temperature 25 and thereafter, samples containing the sediment reducing 26 additives of this invention were also tested for compat-27 ibility by centrifuging under the same conditions. me volume 28 p~æ~ s~ment~asmeasured on the basis of the se~;ment obs~ved Ln 29 a calibrated test tube which contained the 100 ml. samples 30 and the results are set forth in the following Table I.

:

:
.. ~. , -:

6 t.~ 0 ~ '1 2 V_l. % After Centrifu~ing 3 hrs. 16 hrsO 24 hrs.
5 Base .20 .50 3.00 6 Base + Glyceride Trace Trace Trace 7 (Example 1 and lA) 8 Base ~ Sor~itan Ester Trace Trace Trace 9 (Example 2) 10 sase + Ethoxylated - - Trace 11 Cocoamine (Example 3) 13 Base + Ethoxylated - - Trace Tallow Diamine 14 (Example 4) Example 1: 0.26 weight percent liquid mixture 16 of mono- and diglyceride of oleic acid, 55 percent mono-17 ester, 130 cps. viscosity at 25C, sold as ATMOS ~ 300 18 by ICI America, Inc.
19 Example lA: Example 1 was repeated using 0.56 weight percent of the same glyceride with the same results 21 after centrifuging.
22 Example 2: 1.25 weight perc nt Sorbitan Mono-23 oleate li~uid having 1900 cps. at 25C viscosity sold as 24 Arlacel~ 80 by ICI America, Inc.
Example 3: 1.25 weight percent ethoxylated coco-26 amine sold as Ethomeen~ C-12 by Armak, Inc., 2 moles ethyl-27 ene oxide per mole amine, a~erage mol. weight = 285.
28 Example 4: 1.25 weight percent ethoxylated tal-29 low diamine sold as Ethoduomeen~ TD-13 by Armak, Inc., 3 moles~ethylene oxideper mole amine, average mol. weight = 530.
31 Exam~le 5

32 A formulation was prepared similar to the base

33 Eormulation, the preceding Examples except that 0.3 weight

34 percent of the dimer acid ester friction reducing component was used. The base formulation showed about a 3.0 vol.
36 percent sediment formation after 24 hours centrifuging.
~ 37 After addition of 1.25 weight percent of ~he same gly-;: ~: : ` :

~ :1 6 ~1~ 0 ~ Ll l ceride of Example l,the formation was stable after 24 2 hours centrifuging, 3 Example 6 4 Example 5 was repeated with the same results using the same stabilizer additive in the same amount ex-6 cept that the base formulation contained a borated alkenyl 7 s~ccinimide dispersant prepared by reacting the dispersant 8 of the base formulation with a slurry of 1.4 moles of g boric acid in mineral oil over a 3 hour period at 135 to 165C followed 4 hours of nitrogen stripping. The ll final product contained l.S weight percent nitrogen and 12 0.3 weight percent boron and had a Mn of about 3,000.

.

Claims

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

1. A storage stable lubricating oil composition having a reduced tendency to form sediment comprising a lubricating oil containing (a) .01 to 2 percent by weight of a polycar-boxylic acid-glycol ester friction reduc-ing component;
(b) 0.1 to 10 percent by weight of an oil-soluble alkenyl succinimide or borated alkenyl succinimide dispersant and (c) an oil-soluble stabilizer additive being a polyol or polyol anhydride partial ester of a C8-C22 fatty acid, an ethoxylated C8-C22 fatty acid, fatty amine or fatty amide, in an amount effective to reduce the tendency of said lubricating oil com-positions to form sediment.

2. The composition of claim 1 wherein said (a) component is a dimer acid ester of an unsaturated fatty acid having from about 16 to 22 carbon atoms between the carboxylic acid groups of said dimer acid.

3. The composition of claims 1 or 2 wherein there is present 0.05 to 0.5 percent by weight of said (a) compo-nent based on the total weight of the lubricating oil com position.

4. The composition of claim 1 or 2, wherein said (c) component is a glycerol partial mono- or di-ester of oleic, linoleic or palmitoleic acid or a mixture of said acids.

5. The composition of claim 1 or 2 wherein said (c) component is a mixture of glycerol mono- and di-esters of oleic acid.

6. The composition of claim 1 or 2 wherein said (c) component is a sorbitan partial ester of oleic acid.

7. The composition of claim 1 or 2 wherein said (c) component is an ethoxylated C12-C18 fatty monoamine or diamine containing 1 to 3 mole of ethylene oxide per mole of said monoamine or diamine.

8. The composition of claim 1 or 2 wherein the weight ratio in parts by weight of said (c) component to said (a) component is from 2 to 20 parts by weight of said (c) component per part by weight of said (a) component.

9. The composition of claim 1 wherein said (a) com-ponent is diethylene glycol ester of dimerized linoleic acid present in an amount from about 0.1 to 0.3 weight percent, based on the total weight of the composition.

10. The composition of claim 1 wherein said (b) dispersant component is a polyisobutenyl succinic anhydride-polyalkyleneamine reaction product or borated polyiso-butenyl succinimide.

11. The composition of claim 1 or 2 wherein said (c) component is an ester or a C18 to C22 unsaturated fatty acid and said composition also contains a metal-containing additive being a normal or basic metal phenate, sulfurized phenate or sulfonate in an amount of from 2-5 weight percent or a zinc dialkyldithiophosphate in an amount of from 1 to 3 weight percent.