CA1090320A

CA1090320A - Lubricating oil composition containing a dispersing- varnish inhibiting combination of nitrogen-containing additives

Info

Publication number: CA1090320A
Application number: CA288,018A
Authority: CA
Inventors: Thorkild F. Lonstrup; Darrell W. Brownawell; Edward Goletz, Jr.; Solomon J. Numair
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1976-11-11
Filing date: 1977-10-03
Publication date: 1980-11-25
Also published as: AU509261B2; DE2745909A1; GB1588361A; SU686630A3; BR7707555A; BE860322A; JPS6323238B2; JPS5360905A; AR219723A1; NL7711808A; US4113639A; AU3033377A; IT1087920B; DE2745909C2; FR2370787B1; FR2370787A1

Abstract

ABSTRACT OF THE DISCLOSURE
The combination of (a) an oil-soluble oxazoline reaction product having a (?n) of from about 1,000 to 3,300, e.g., the reaction product of polybutenyl succinic anhydride with tris(hydroxymethylj aminomethane and (b) an oil-soluble acylated nitrogen material having a (?n) of from about 1,300 to 8,000, e.g. polybutenyl succinic anhydride reacted with a poly-ethylene polyamine, which nitrogen material can be borated, if desired, are surprisingly useful as combined additives for lubricating oils to increase the dispersancy and varnish inhibition properties of said oil when one part per weight of said oxazoline reaction product is combined with from 0.2 to 4, preferably 1 to 3, parts by weight of said acylated nitrogen material.

Description

1 This ~nvention relates to a combination of an oxaz-

2 oline oil additive and an acylated nitrogen-containing oil

3 additive which markedly improves the sludge dispersanc7-

4 varnish inh~biting properties of lubricating oils.
During the past decade, ashless sludge dispersants 6 have become ~ncreaslngly important for improving the per-7 ~ormance of lubricants in keeping the engine clean of de-8 posits and permitting extended crankcase oil drain periods.
9 In one category of ashless dispersants, a polyamine i8 attached to a long chain hydrocarbon polymer, usually polyisob.utylene~ through an acld group, such as ~ dicarboxyl-12 ic acid material by formlng.smide or imide linkages such as 13 described in U.S. Patents 3,172,892 and 3,272~746.
:;
;; 14 German Speci~ication (DOS) 2,512,201 teaches that the reaction of a hydrocarbyl-dicarboxylic acid material,i~e~
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6 acid or anhydride, or ester, with certain classes of amino 17 alcohols, will result in products containing one or two oxaz-, 18 oline rings, and that products containing at least one oxazo- .
19 line ring can be tailored for various functiqns, such as anti-~f~, 20 rust agents or dispersants for oleaginous compositions includ-. 21 ing lubricating oils, gasoline, turbine oils and oils for ii.- 22 drilling applications. DOS 2,534,921 and 2,534,922 disGlose 23 similar monooxazoline products which can also be modified by 24 reaction with phosphorous, boron or oxygen compounds to en-2s hance lubricating oil properties, including sludge dispers-26 ancy~ The above-mentioned DOS 2,512,201 has a general state-27 ment that the oxazoline can be used with other conventional 28 additives including, among other additives, other ashless ~ ~ diæpersants but does not d~sclose any specific dispersants to .~ ~ be used with such oxazolines. This German Specification ~ - 2 -' .

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-l also contains comparison data showing that the oxazoli~e pro-2 ducts are more effective as dispersants in lubricating oils : 3 than the commercial dispersant referred to as "PIBSA/TEPA".
4 The term "PIBSA/TEPA" refers to a product prepared by react-ing polyisobutenyl succinic anhydride with tetraethylene 6 polyamine; such a product is of the class of mater~als here-7 inafter described as acyl nitrogen-containing materials, 8 which form the one component of the composition of the .. 9 present invention.
Thus, the prior art teacheæ that oil-soluble addi-tives of the acylated nitrogen type and the oxazoline type 12 are each useful for lubricating oils but does not teach the l3 combination of these two types of materials.
14 Surprisingly, it has now been found that the com-bination of an oil-soluble polyalkenyl oxazoline product hav-6 ing a number average molecular weight ~Rn) Of about 1000 to 17 3300, preferably from about 1200 to 3100, optimally from 18 about 1600 to 2800, preferably polybutenyl succinic-bis-9 oxazoline (obtained from the reac~ion of polybutenyl succin-ic anhydride and tris(hydroxymethyl) aminomethane) and an 21 oil-soluble acyl nitrogen material having a number average 22 molecular weight of about 1300 to 8,000, preferably poly- ~.
23 butenyl succinimide (obtained from the reaction of poly-24 butenyl succinic anhydride and one molar equivalent of eGg.
2s tetraethylene pentamine), exh~bits synergisti¢ behavior in 26 dispersancy and/or varnish inhibit~on when employed in a 27 ratio of one part per weight of the oxazoline product to 28 from 0~2 to 4, preferably 1 to 3 parts by weight of the acyl 29 nitrogen material when said combination is present in at 3Q least a dispersing amount in a lubricatlng oil.

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1 Thus in its broadest concept, the sub~ect matter 2 of the invention is a lubricatlng oil compositlon comprlsing 3 a ma~or amount of lubricating oil and a minor but dispersing 4 amount of a dispersing/varnish-inhibiting combination of:
(a) one part by weight of an oll-soluble oxazoline reaction 6 product hav~ng a number average molecular weight of from 7 about 1000 to about 3300 obtained from the reaction of one 8 molar proportion of a hydrocarbyl-substituted C4-C10 mono-9 unsaturated dicarboxylic acid material and from about 1.5 to about 2 molar proportions of a 2,2-disubstituted-2-amino-11 l-alkanol having 2 to 3 hydroxy groups and containing a 12 total of 4 to 8 carbons and represented by the formula:

16 wherein X is an alkyl, or hydroxy alkyl group~ with at least 17 one of the X substltuents being a hydroxy alkyl group of the 18 structure -(CH2)nOHs wherein n is 1 to 3; and, (b) from 0.25 19 to 4 parts by weight of an oil-soluble acyl nitrogen materi-ial having a ~Mn) of from about 1300 to 8000 characterized 21 by the presence within ~ts structure of a substantially 22. satur~ted hydrocarbon-substituted polar group selected from 23 the cl~ss consisting of acyl7 acylimidoyl~ and acyloxy radi-24 cals wherein the subst~ntlally saturated hydrocarbon subst~t-~ent contains at least about 50 aliphatic carbon atoms and 26 a nitrogen-containing group characterized by a nitrogen atom 27 attached directly to sald polar radical.
28 In a preferred form~ said oxazoline product and 29 said acyl nitrogen material are both derived from hydro- -carbyl-substituted dicarboxylic acid materials wherein said 31 hydrocarbyl substituent has a (~) ranging from about 900 ' 1 to 2800, optimally about 1200 to 2500.
2 The hydrocarbyl-substituted dicarboxylic acid ma-3 terial, i.e~, acid or anhydride, or ester which is used to 4 produce both classe~ of dispersants includes alpha-beta unsaturated C4 to C10 dicarboxylic acid, or anhydrides or 6 esters thereof, such as fumaric acid, itaconic acid, maleic 7 acid, maleic anhydride, chloromaleic acid, dimethyl fumar-8 ate, etc., which are substituted with a hydrocarbyl or sub-9 stituted hydrocarbyl group having from 50 to about 400 and 0 more carbons9 and preferably from 65 to about 200 carbons.
The anhydrides can be obtained by well-known methods, such 2 as the Ene reaction between an olef~n and maleic anhydride 13 or halo-succinic anhydride~
14 Preferred olefin pslymers for reaction with the un-saturated dicarboxylic acids are polymers comprising a ma~or 16 molar amount of C2 to C5 monoolefin, e.g., ethylene, propyl-17 ene, butylene, isobutylene and penteneO The polymers can 18 be hopolymers such as polyisobutylene, as well as co-9 polymers of two or re of such olefins such as copolymers of: ethylene and propylene; butylene and isobutylene; pro-21 pylene and isobutylene; etc~ Other copolymers include those ~
22 in which a minor amount of the copolymer monomers, e.g., 1 -23 to 20 mole % is a C4 to Cl~ non-con~ugated diolefin, e.g., 24 a terpolymer of ethylene, propylene and 1,4-hexadiene.
2s The olefin polymsrs will usually have (~)s within 26 the range of about 700 and about 3,000, more usually be-27 tween about 900 and abou~ 2800. Particularly useful olefin 28 polymers have (~)s of about 1200 to 2500 with approximately 29 one terminal doubie bond per polymer chain~ An especially ~ valuable starting material for a highly potent dispersant .

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1 additive are polyalkenes, e.g~, polyisobutylene, having 2 about 80 carbons~
3 The oil-soluble oxazoline reaction products and 4 their methods of preparation are described in German Patent Application DOS 2,512,201~ This oxazoline dispersa~t can 6 be characterized in its preferred form as an oil-soluble 7 product obtained from heating together a molar equivalent 8 of a hydrocarbon substituted C4-ClO mono-unsaturated di-9 carboxylic acid material having re than about 50 carbon atoms per dicarboxylic acyl group and from 1.5 to about 2 ll lar equivalents of a 272-disubstituted-2-amlno-l-alkanol 12 `having 2 to 3 hydroxy groups and containing a total of 4 to 8 carbons at a temperature of from about 140C. to 240C.
14 until cessation of water evolution indicating completion of the oxazoline reaction~ The amino-alkan~ can be repre-l6 sented by the formula wherein X is an alkyl or hydroxy alkyl group with at least 2l one of the X substituents being a hydroxy alkyl group of 22 the structure -(CH2)nOH~ wherein n i~ 1 to 3~
23 Examplês of such 2,2-disubstituted amino-alkanols, 24 include 2-amino-2-methyl-1,3-propanediol? 2-amino-2-(hydroxy-methyl)-1,3-propanediol (also known as tris(hydroxymethyl) 26 amino methane or THAM~, 2-amino-2-ethyl-1,3-propanediol, 27 etc. Because of its effectiveness~ availability, and cost, 28 THAM is particularly preferredO
29 The formation of the preferred oxazoline disper-sants in high yield, can be effected by adding about 1.5 to lW03'~0 1 2 ~ole equivalent of the aforesaid 2,2-disubstituted-2-amino-2 l-alkanol per le equivalent of the dicarboxylic acid mater-3 ial, wi~h or without an inert diluent, and heating the mix-4 ture at 140-240C., optimally 170-220C~ and pre~erably 180-205C. for 1/2 to 24, re usually 2 to 8 hours, until 6 the react~on is complete.
7 Completion oftheoxazoline reaction can be readily 8 ascertained by using periodic infrared spectral analysis 9 for following oxazoline formation (oxazoline peak forms at o 6.0 microns), or by the cessation of water evolution of about 2.3 to 3.0 moles of water~
12 Although not necessary~ the presence of 8mal1 13 amounts, such as 0.01 to 2 wt. %, preferably 0.1 to 1 wt.%
lA based on the weight of the reactants, of a metal salt can be used in the reaction mixture as a catalyst. The metal - ~
6 catalyst can be later removed by filtration or by washing ~ ~ -17 a hydrocarbon solution of the product with a lower alcohol.
8 Alternatively, ~he metal salt can be left in the 19 reaction mixture, as it appears to become stably dispersed, or d~ssolved, in the reaction product and depending on the 21 meta~ it can contribute perfonmance benefits to the lubri-22 cating oil.
23 Inert solvents which may be used in the oxazoline 24 reaction include hydrocarbon oils, e.g., mineral lubricating oil, kerosene, xylene~ halogenated hydrocarbons, e.g., car-26 bon tetrachloride, dichlorobenzene, tetrahydrofuran, etc.
27 Metal salts that may be used as promoters or cata-28 lysts include carboxylic acid salts of Zn, Co, Mn, Ni ~nd Fe.
29 The carboxylic acids used to prepare the desired promoters 30 include Cl to Clg, e.g., Cl to Cg acids, such as the satur-'. . ~ .

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; l ated or unsaturated mono- and dicarboxylic aliphatic hydro-2 carbon acids, particularly fatty acids~ Specific examples ~j 3 of such desired car-boxylic acid salts include zinc acetate, 4 zinc formate, zinc yropionate, zinc stearate~ manganese(ous) acetate, iron tartarate, cobalt(ous) acetate, nickel acetate 6 etc~ Zinc salts, such as zinc acetate and zinc oxide, are 7 preferred.
- 8 It is preferred ~hat the metal salt promoter be 9 present at or near the onset of the reaction for greatest ef-fect. The zinc salt promoter gradually dissolves by form-ing, inter alia, z~nc complexes with the oxazoline product.
~;~ 12 The presence of zinc in the oxazoline product apparently l3 contributes performance benefits to the lubricating oil.
14 The acyl nitrogen material is of that class of oil-soluble dispersants broadly described in U.S. 3,272,746 16 as an oil-soluble acylated nitrogen material characterized l7 by the presence within its structure of a substantially 8 saturated hydrocarbon-substituted polar group selected from 9 the class co~sisting of acyl~ acylimldoyl, and acyloxy radi-cals wherein the substantially saturated hydrocarbon substit-21 uent contains at least about 50 aliphatic carbon atoms and 22 a nitrogen-containing group characterized by a nitrogen 23 atom attached directly to said polar radical. For the pur-- 24 poses of this invention, these acyl nitrogen materials have a (~) ranging from about 1300 to 8000, preferably from ?6 about 2000 to 6000 and optimally from about 3000 to 5000.
27 All ~Rn) values have been determined by Vapor Pressure 28 Osmometry (VP0).
~ 29 The relative polar groups of the acyl nitrogen r. ~ material are represented by the structural configurations , 1 as follows:
2 0 NRl 3 acyl R - C - ; acylimido~l R - C - , and, acyloxyR - C - O -6 where R is the subs~antially saturated hydrocarbon substit-7 uent preferred to as the hydrocarbyl (including the pre-8 ferred alkenyl) substituent of the dicarboxylic acid mater-9 ial and Rl represents hydrogen or a hydrocarbyl group (in-0 cluding polar-substituted hydrocarbyls, e.g. Cl-substituted)O
The nitrogen-containing group of the acylated ni-2 trogen ma~erials is derived from compounds characterized by 3 a radical having the structural configuration 14 - N - H and 6 wherein the two remaining valences of the nitrogen atom of 7 the above radical are preferably satisfied by hydrogen, or 18 organic radicals bonded to said nitrogen atom through direct 19 carbon-to-nitrogen linkagesO Thus, the compounds from which 20 the nitrogen-containing group may be derived include ali- ~
21 phatic amines~, aromatic amines, heterocyclic amines or car- -22 bocyclic amines. The amines may be primary or secondary 23 amines and preferably are polyamines such as alkylene amines, 24 arylene amines, cyclic polyamines~ and the hydroxy-substi-tuted derivatives of such polyamines.
26 The preferred acyl nitrogen materials are essen-27 tially described as the ~des and diimides, preferably di-2~ imides, resulting from the reaction of 1 to 2.5, preferably 29 about 2.0 to 2.2 molar proporti~ns of the dicarboxylic acid ~ material with one molar proportion of a nitrogen compound ;' _ 9 _ 1 having one or more amino groups.
2 Useful nitrogen compounds include mono- and poly-3 amines of about 2 to 60, e.g. 3 to 20 total carbon atoms and 4 about 1 to 12, e.g. 2 to 6 nitrogen atoms in the molecule.
S The amine compounds may be hydrocarbyl amines or may include 6 hydroxy groups, alkoxy groups, amide groups or may be cyclic 7 in structure such as imidazolines and the like. Preferred 8 amines both as noted above generally and for preparation of 9 said imides and diimides are aliphatic, saturated amines in-o cluding those of the general f~rmulae~
11 R-N-R' and R-N-(CH2~X ~-N-(CH2)~ N-R
12 R" R' L H ~ t R' 13 wherein R; R~ and R" are independently selected from the 14 group consisting of hydrogen, Cl to C12 straight or branched chain alkyl radicalsa Cl to C12 alkoxy C2 to C6 alkylene 16 radicals, C2 to C12 hydroxy or amino alkylene radicals~ and 17 Cl to C12 alkylamino C2 to C6 alkylene radicals; 8 iS a nun~
18 ber of from 2 to 6, preferably 2 to 4; and t i8 a number of 19 from O to 10, preferably 2 to 6.
Examples of suitable amine compounds include mono-21 and di-tallow amines9 1,2-diaminoe~hane~ 1,6-diaminohexane, 22 diethylene triamine, ~riethylene tetramine, tetraethylene 23 pentamine, 1,2-propylene diamine9 di-(1,2-propylene) tri-24 amine, N,N-dimethyl~1,3~diaminopropane, N,N-di-(2-amino-ethyl) ethylene diamine, N,N-di~(2~hydroxyethyl)-1,3-propyl-26 ene diamine, 3-dodeeyloxypropylamine, N-dodecyl-1,3-propane 27 diamine, tris-hydroxymethyl methylamine, and diethanol amine.
28 Other useful amine compounds include alicyclic 29 diamines such as 1,4-bis-(aminomethyl) cyc~ hexane, and ~ heterocyclic nitrogen compounds such as imidazolines and N-,., ', , ~ 10 ~

~9Q 3Z~u 1 aminoalkyl piperazines, such as N-(2- d noethyl) piperazine;
2 N-(3-aminopropyl) piperazine; and N~N'-di-(2-aminoethyl) 3 piperazine.
4 Commercial mixtures of amine compounds may advan-tageously be used. For example, one process for preparing 6 alkylene d nes involves the reaction of an alkylene di-7 halide (such as ethylene dichloride or propylene dichlor-8 ide) with ammonia, which results in a complex mixture of 9 alkylene amines wherein pairs of nitrogens are joined by alkylene groups, forming such compounds as diethylene tri-1 amine, triethylenetetramine, tetraethylene pent d ne and 2 isomeric piperazines. Low cost poly(ethyleneamines) (used 13 for the preparation of the acyl nitrogen materials of the 14 Examples herein) are available commerc~ally~ -Amination of the dicarboxylic acid material is 16 usefully carried in a solution reaction with the dicarboxyl-17 ic acid material dissolved in a solvent such as mineral oil. ~-18 The formation of the imide dispersants in high yield can be 9 effected by adding from about 0~4 to l, preferably about 0.45 to 0.5, lar proportions of alkylene polyamine per 21 molar proportion of dicarboxylic acid material of the nltro-22 gen compound to said solution and heating the mixture at - -23 140C~ to 165C~ until the appropriate amount of water of 24 reaction is evolved~
2s In some applications, it is useful to modify the 26 acyl nitrogen dispersant by subsequent boration as generally 27 taught in U.S. Patents 3,087,936 and 3,254,025. This is 28 readily accomplished by treating said acyl nitrogen disper-29 sant with a boron compound selected from the class consist-ing of boron oxide, boron halides, boron acids and esters , - 11 -':

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l of boron acids in an amount to provide from about 0.1 atomic 2 proportion of boron for each mole of said acylated nitrogen 3 material to about 10 atomic proportions of boron for each 4 atomic proportion of nitrogen of said acylated nitrogen material. Usefully, the dispersants of the invention com-6 bination contain from about 0.3 to 0.9 wt. % boron based 7 on the total weight of said borated acyl nitrogen material.
8 The boron, which appears to be in ~he product as dehydrated 9 boric acid polymers (primarily (HBO2)3), attaches chemically to the dispersant imides and diimides as amine salts, e.g.
ll the metaborate salt of said di~mide.
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~L~ 12 Treating is readily carried~by adding from about 3 1 to 3 wto % (based on the weight of said acyl nitrogen 4 material) of said boron compound, prefera~ly boric acid which is most usually added as a slurry of said acyl nitro-6 gen material and heating with stirring and at from about 7 135C. to 165C. for from 1 to 5 hours followed by nitrogen 18 stripping at said temperature ranges.
19 The c~mbination of oil-soluble dispersants accord-ing to the invention can be incorporated in a wide variety 21 Of lubricants~ They can be used in lubricating oil composi-22 tions, such as automotive crankcase lubricating oils, auto-23 matic transmission fluid, etc., in concentrations generally 24 within the range of about 0.05 to 10 wt. %, for example, 0.5 to 5 wt. %~ preferably 1~5 to 3 wto %, of the total 26 composition. As noted in general, the additive combination 27 Of the invention will comprise one part by weight of the 28 oxazoline reaction product per about 0.2 to 4, preferably 1 to 3, optimally 2 to 3 parts by weight of said acyl nitro-gen material~ The lubrica~ing oil to which the synergistic -1 combination can be added includes not only hydrocarbon oils 2 derived from petroleum but also includes synthetic lubricat-3 ing oils such as esters of dicarboxylic acid, polyglycol 4 and alcohol; alkyl esters of carbonic or phosphoric acids;
polysilicones; fluorohydrocarbon oils; and, mixtures of 6 lubricating oils and synthetic oils in any proportion, etc.
7 The useful combination may be conveniently dispensed as a 8 concentrate of lO to 80 wt. % of said synergistic combina-9 tion in 20 to 90 wt. % of mineral oil, for example, kero-sene, with or without other addi~ives being present. In 11 the above compositions or concentrates, other conventional 12 additives may also be present includ~ng dyes, pour point 13 depressants,antiwear agents such as zinc dialkyl dithio-. .. .
14 phosphates of 3 to 8 carbon atoms in the alkyl groups, an-tioxLdants such as n-phenyl-alpha naphthylamine, tertiary-6 octyl phenol sulfide, and 4,4~-methylene bis(2,6-di-tert, 17 butyl phenol)) viscosity index improvers such as ethylene-18 propylene copolymers, polymethacrylates, polyisobutylene, 19 alkyl fumarate~vinyl acetate copolymers and the like.
It has been noted that in those combinations of 21 the oxazoline reaction produ~t and acyl nitrogen material 22 according to this invention that when the (Mn) ~f said oxa-23 zoline is about 30% to 60% of the ~Mh) of the acyl nitrogen 24 material exceptionally potent dispersant-varnish inhibition 2~ is imparted to the lubricating oil, e.g. (Mn) of about 1700 26 for the oxazoline and about 3400 for the acyl nitrogen.

28 A mixture of 500 gm. (0~4 moles) of polyisobutenyl 29 succinic anhydride having a Saponification No. of 89 and a ~ (Mb) of 980, 500 ml. of mineral lubricating oil (Solvent 150 .'.' . . .

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1 Neutral), 4 gm. of zinc acetate dihydrate as a promoter and 2 96.8 gm. (0.8 le) of THAM was charged into a glass reactor 3 fitted with thermometer, stirrer and a Deane-Starke moisture 4 trapt Heating at about 180C~ for four hours gave the ex-pected quantity of water, i.e., about 1.1 moles of water in 6 the trap. After filtration and rotoevaporation, the concen-7 trate (50 wt. % of the reaction product) analyzed for 1.00 8 wt. % nitrogen, and 0~06 wt. % zinc. The product had a (~) 9 of about 1400.
0 The polyisobutenylsuccinic anhydride used herein 11 (also used in Example 2) was prepared by ~he reaction of 2 chlorinated polyisobutylene having a chlorine content of 3 about 3.5 wt. %, based on the weight of chlorinated polyiso-butylene, and a~ average of 70 carbon atoms in the polyiso-butylene group, with maleic anhydride at about 200C.

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17 A borated derlvative of the reaction product of 18 polyisobutenyl succinic anhydride and an alkylene polyamine 9 was prepared by first condensing 2.1 moles of polyisobutenyl succinic anhydride, havingaSaponification Number of 89 and 21 a ~n) of 980, dissolved in Solvent Neutral 150 mineral oil 22 to provide a 50 wt. % solution with 1 mole of tetraethylene 23 pentamine (TEPA). The polyisobutenyl succinic anhydride 24 solution was heated to about 150C. with stirring and the polyamine was charged into the reaction vessel over a 4-hour 26 period wh~ch was thereafter followed by a 3-hour nitrogen 27 strip. The temperature was maintai~ed from abou~ 140C. to 28 165C. during both the reaction with the TEPA and the sub-29 sequent stripping. While the resulting imidated product was maintained at a temperature of from about 135 to about 165C.
'''' ,:
' 1 a slurry o 1.4 moles of boric acid in mineral oil was added 2 over a 3-hour period which was thereafter followed by a final 3 4-hour nitrogen strip~ After filtration and rotoevaporation, 4 the concentrate (50 wt. % of the reaction product) contained about 1.5 wt~ % nitrogen and 0.3 wt. % boron. The product 6 had a (~n) of about 2420.
7 EXAMPT~ 3 , 8 In the same manner as Example 2, 2.1 moles of 9 polyisobutenyl succinic anhydride (Sap. No. of 103 and an lo ~n of about 1300) was utilized i~ place of the polyisobutenyl 11 succinic anhydride of Example 2~ The resulting concentrate ro~ . -2 (50 wt. 7O active ingredient) analyzed for 1.46Z~and 0.3270 13 boron.

The general process of Example 1 was used however 6 in this instance, one mole of polyisobutenyl succinic anhy-17 dride (having a Saponification Number of 103 and a ~n) of 8 1300) dissolved to 50 wt. % in S150 Neutral mineral oil was 19 heated with 0.036 moles of zinc acetate dihydrate and 1.9 moles of THAM at a temperature of from 168 to 174C. At the 21 end of the THAM addition, the reaction mixture is sparged 22 with nitro~en at 177C. for 10 hours. After rotoevaporati~n, 23 the concentrate (50 wt~ % active ingredient) analyzed for 24 1.0 wt. % nitrogen and Ool wt. % zinc~ The product had a ~ ) of about 1700.

27 The general process of Exa~ple 2 was used, how-28 ever 1.3 moles of polyisobutenylsuccinic anhydride was used 29 and boration was not undertaken. The ~ ) of the product was about 1520;

1 In the evaluation of the combinations in the ; 2 Varnish Inhibition Test, each sample consisted of 10 grams ` 3 of lubricating oil containing 0~07 of a gram of the additive 4 concentrate (50% active) which results in a total of 0.35 wt.
% addi~ive present in the test sample. The test oil to B 6 which the additive is admixed with 9 93 grams of a commercial ` !
7 lubricating oil obtained from a taxi after 2,000 miles of ~ 8 driving with said lubricating oil~ Each ten gram sample ; 9 was heat soaked overnight at about 140C~ and thereafter centrifuged to remove the sludge. The supernatant fluid of ll each sample was sub~ected to heat cycling from about 150C.
`~ l2 to room temperature over a period of 3.5 hours at a fre-l3 quency of about 2 cycles per minute~ During the heating 14 phase, the gas containing a mixture of about 0.7 volume per-cent S02, 1.4 volume percent N0 and balance air was bubbled 16 through the test samples and during the cooling phase water 17 vapor was bubbled through the test samples~ At the end of l8 the test period, which testing cycle can be repeated as l9 necessary to determine the inhibiting effect of any additive, the wall surfaces of the test flasks in which the samples 21 were contained are visually evaluated as to the varnish in-22 hibition. The amount of varnish imposed on the walls is 23 rated at values of from 1 to 7 with the higher number being 24 the greater amount of varnish. It has been found that this test correlates with the varnish results obtained as a con-26 sequence of carrying out an MSVC engine test. The results 27 which are recorded in Table I indicate that combinations of 28 the oxazoline reaction product and the acyl nitrogen material exhibit enhanced behavior when their weight ratios range from about one part by weight of the acyl nitrogen material ' ,' ~: .

1 to from 0~2 to 3 parts by weight of the oxazoline product, 2 with a synergistic result when the polyalkenyl substituent 3 of each has a (~) of about 1300 and about 3 parts by weight --4 of the acyl nitrogen material is combined with 1 part by weight of the oxazoline product~

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2 Three fully fonmulated lubricating oil blends were 3 prepared by blending five volume percent of the concentrate i 4 of Example 1, five volume percent of the concentrate of Example 2 and five volume percent of a 50/50 mixture of the 6 concentrates of Example 1 and Example 2, respectively, with 7 a SAE 30 lubricating oil of Solvent 450 N base stock con-8 ~aining about 0.6 wt, % zinc dialkyl dithiophosphate (here-9 after noted as ZDDP) and 0.6 wt. % calcium phenate sulfide. -' Each of the blends prepared as described above 11 was sub~ected to the MS Sequence VC Engine Test which is a 12 test well known in t~e automotiye industry. The test is 13 run in a Ford engine of 302 cubic inch displacement follow-' 14 ing the procedure described in the publication entitled "Multi-Cylinder Test Sequences for Evaluating Automotive 16 Engine Oil" (AS~M Special Publication 315-E). At the end 17 of each test, various parts of the engine are rated on a ' 18 merit basis wherein 10 represents a'perfectly clean part, 19 and lesser n~mbers represent increasing degrees of deposit formation. The various ratings are then totaled and aver-21 aged on the basis of 10 as a perfect (completely clean) 22 rating. The results obtained with the three blends des-23 cribed nbove are gi-en in Tnble II.

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3 MERIT RATINGS (BASIS 10) 4 Additive of the Concent~ate of Example _ !
6 1 2 1:2 7 Sludge Merit 8.899.43 9.14 8 Varnish Merit 7.767O97 7.70 9 Piston Skirt Varnish Merit 7.688.04 8.42 The results set forth above show that synergism does exist 11 for a 50/50 mixture of an oxazoline reaction product and an 12 acyl nitrogen dispersant material in the merit ratings of 13 the piston skirt varnish. The sludge and varnish ratings 14 are statistically equivalent. These results when vi~wed in concert with the data of Tables III and IV indicates~
16 that the optimum range of this combination is from about 1 17 to 3 parts by weight of acyl nitrogen dispersant to l part 18 by weight of oxazoline reaction product.

Three fully formulated lubricating oil blends com-~1 parable to those set forth in Example 6 except that the 22 two combined dispersa~ts were both prepared from polyiso-23 butylene succinic anhydride in which the (Rn) of the ~ydro-24 carbyl substituent is about 1300 rather than 980, i.e. the additives of Examples 3 and 4 are combined. These three 26 blends were prepared by blending 5 wt. % of the concentrate 27 o$ Example 3, 5 wt. % of ~he concentrate of Example 4 and 5 28 wt. % of a mixture of the combination of the concentrates of 29 Example 3 and 4 (2 wt. parts o$ Ex. 3 to 1 wt. part o~ ~x.
4), respectively, with a lubricating oll blend of two neu-- ~ .
- : :

1 tral base oils and formulated with about 0.79 ~t~ % of .~ 2 metal detergent tcalcium sulfonate overbased to a 400 TBN), 3 0.66 wt. % æinc dialkyl dithiophosphate and 0~12 wt. % iso-4 prene-styrene polymer viscosity index improver to provide a fully formulated SAE lOW-40 lubricating oil~
6 The results of the MS Sequence VC Engine Test on 7 the several formulations are set forth in Table III. TBN
8 represents total base number and reers to the milligrams 9 of KOH required to neutralize a one gram sample according to ASTM Method D-2896.

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~ 10903Z0 1 The data of Table III shows that the combination of disper-2 sants has synergistic activity ~n the MS VC Engine Test both 3 as to sludge merit and piston skirt varnish merit ratings~

~- 5 The merit ratings realized from a MS Sequence VC
6 Engine Test on the optimum combination of the invention . 7 shows that the combination includes a ratio ranging between 8 1 part of the oxazoline reaction product to 2 to 3 parts by 9 weight of the acyl nitrogen material (dispersants are de- -rived from a polyisobutenylsuccinic anhydride having a hy-11 drocarbyl substituent of ~ ) of about 1300). The additives 12 were incorporated into a SAE 30 lubricating oil of blended 13 neutral distillate and bright stock mndified with about 0.4 14 wt~ % magnesium sulfonate, Ool wt. % calcium phenate sulfide - 15 and 0.6 wt. % zinc dialkyl dithiophosphate~ The respective - 16 merit ratings are shown in Table IV.

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` 10903Z0 1 A highly useful concentrate according to this in-2 vention contains about 50 wt. % diluent (e.g. a neutral 3 mineral oil), and 50 wt. ~/O of the additive combination, 4 e.g. the products of Examples 3 and 4 in a weight ratio of .. :
one part of said oxazoline reaction product to one to three 6 parts of said acyl nitrogen material~ Such a concentrate 7 can be represented thus by about 50 wt. % of mineral oil 8 diluents, about 17% of the bis-oxazoline of polyisobutenyl 9 succinic anhydride wherein said polyisobutenyl group has a ( ~ of about 1300 and about 33 wt. % of borated tetra-11 ethylene pentamino-diimide of polyisobutenyl succinic an-12 hydride wherein said polyisobutenyl group has a (Rn) of ~3 about 1300 and said concentrate contains about 1.3 wt. ~L
14- nitrogen and about 0.2 wt. % boron~ The oxazoline dis-persant can be generally termed a bis-oxazoline since at 16 ` least about 60% of the O groups of the dicarboxylic l? -C-18 acid material have been incorporated into the oxazoline `
19 ~tructure.
It is possible to provide some or all of the .. ~
21 boron, i.e. u~ to about 0.03 wt. % in lubricating oils is 22 useful for varnish inhibition, by means of a borated oxazo-23 line reaction compound produced accord~ng to the general 24 teachlngs of German DOS 2,534S921 and 2,534,922. The oxazo-line produc~ can contain from about 0.3 to 0.9 wt. % boron.
26 The inventive combination also provides rust in-27 hibition properties to formulated lubricating oils generally 28 superior to comparable amounts of known acyl nitrogen dis-29 persants.

, ` - 25 -

Claims

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

1. A lubricating oil composition comprising a major amount of lubricating-oil and a minor but dispersing amount of a dispersing and varnish-inhibiting combination of: (a) one part by weight of an oil-soluble oxazoline reaction product having a number average molecular weight of from about 1,000 to about 3,300 obtained from the reaction of one molar proportion of a hydrocarbyl substituted C4-C10 dicarboxylic acid material wherein said hydro-carbyl substituent contains at least about 50 aliphatic carbon atoms and from about 1.5 to about 2 molar proportions of a 2,2-disubstituted-2-amino-1-alkanol having 2 to 3 hydroxy groups and containing a total of 4 to 8 carbons and represented by the formula:

wherein X is an alkyl, or hydroxy alkyl group, with at least one of the X substituents being a hydroxy alkyl group of the structure -(CH2)nOH, wherein n is 1 to 3; and, (b) from 0.25 to 4 parts by weight of oil-soluble acylated nitrogen material having a number average molecular weight ranging from about 1,300 to 8,000 characterized by the presence within its structure of a sub-stantially saturated hydrocarbon substituted polar group selected from the class consisting of acyl, acylimidoyl, and acyloxy radicals wherein the substantially saturated hydrocarbon substituent contains at least about 50 aliphatic carbon atoms and a nitrogen-containing group characterized by a nitrogen atom attached directly to said polar radical.

2. A composition according to claim 1 wherein said combination is present in from about 0.05 to 10 wt. %, based on the total weight of said composition.

3. A composition according to claim 1 wherein both said hydrocarbyl substituted dicarboxylic acid material and said substantially saturated hydrocarbon-substituted polar group are poly(alkenyl) succinic anhydride with said poly(alkenyl) substit-uent having a number average molecular weight of from about 900 to about 2800.

4. A composition according to claims 1-3 wherein both said hydrocarbyl substituted dicarboxylic acid material and said substantially saturated hydrocarbon-substituted polar group are poly(alkenyl) succinic anhydride with said poly(alkenyl) substituent having a number average molecular weight of from about 1100 to about 2000.

5. A composition according to claims 1-3 wherein said oxazoline reaction product has a (?n) ranging from 1200 to 3100, said acyl nitrogen material has a (?n) ranging from 2000 to 6000, and said combination consists of one part by weight of (a) to from about 1 to 3 parts by weight of (b).

6. A composition according to claims 1-3 wherein said amino-1-alkanol is tris-(hydroxymethyl) aminomethane and said nitrogen-containing group is an alkylene polyamino substituent having from 2 to 60 carbon atoms and from 2 to 6 nitrogen atoms.

7. A composition according to claims 1-3 wherein said oxazoline reaction product contains from 0.1 to 2 weight percent of zinc.

8. A composition according to claims 1-3 wherein said acylated nitrogen material contains from 0.3 to 0.9 weight percent boron.

9. A composition according to claim 1 wherein said oxazoline reaction product is obtained by the reaction of one molar proportion of a poly(butenyl) C4-C10 dicarboxylic acid material with said poly(butenyl) substituent having a (?n) of about 1300 and about two molar proportions of said tris(hydroxy-methyl) aminomethane at a temperature of from about 160°C to about 220°C until cessation of water evolution and said acyl nitrogen material is obtained from the reaction of about two molar proportions of a poly(butenyl) substituted succinic anhydride material with said poly(butenyl) substituent having a (?n) of about 1300 with about one molar proportion of a polyethylene polyamine at a temperature of from about 140°C to about 165°C until about 2 molar proportions of water has evolved followed by condensation with boric acid at a temperature of from about 135°C to about 165°C.

10. A concentrate comprising from about 20% to about 90% by weight of mineral oil and from about 10% to about 80%
by weight of the dispersant combination of: (a) a bis-oxazoline of poly(isobutenyl) succinic anhydride having a (?n) of 1000 to 3300 and (b) a borated alkylene polyamino-diimide of poly(iso-butenyl) succinic anhydride having a (?n) of about 1300 to 8000, the weight ratio of (a) to (b) ranging from about 1 to 3.