US2892816A - Detergent copolymers - Google Patents

Description

United States Patent DETERGENT COPOLYMERS Warren Lowe, Berkeley, William T. Stewart, El Cerrito, Frank A. Stuart, Orinda, and Frank W. Kavanagh, Berkeley, Calif., assignors to California Research Corporation, San Francisco, Calif, a corporation of Delaware No Drawing. Application March 29, 1956 Serial No. 574,634

8 Claims. (Cl. 260-78) This invention relates to a novel lubricant composition, and it is particularly directed to the provision of a lubricant composition which is adapted to be employed in internal combustion engines.

With the refinements now being made in automotive and other internal combustion engines, a great deal of attention is being directed to the provision of a lubricant which will permit the engine to be operated at a high level of efficiency over long periods of time. The primary function of the lubricant is, of course, to reduce friction and thereby not only decrease the wear on pistons, piston walls, bearings and other moving parts, but also increase the elficiency of the engine. Additionally, it is also a function of the lubricant to prevent the deposition of solid products on the piston walls and other surfaces of the engine coming in contact with the lubricant. Such deposits seriously interfere with eflicient engine operation for they accelerate piston ring and cylinder wall wear and also increase oil losses by plugging the oil ring grooves. The troublesome deposits which form on the face of the piston and on the other walls of the combustion chamber, as well as on valves and spark plugs are also partially attributable in many cases to the lubricant, and especially to various of the metal-containing additives employed therein. It is of importance to eliminate or at least minimize the formation of all such deposits, and it is the basic object of this invention to achieve such a result.

To a minor degree, certain of the deposits formed on engine surfaces have their origin in the oil itself, that is to say, in the decomposition products of the oil. A more important, though still minor, source of engine deposits lies in the additives with which oils are conventionally supplied. This is particularly the case with metal-containing additives as, for example, the organic, metal-containing salts which are incorporated in the oil to increase the detergency thereof, and the various metal-containing compounds which are added to increase the lubricity of the oil and reduce piston ring and cylinder wall wear. Whenever oil is burned in the engine (as occurs with the oil film present in the cylinder wall during the combustion stroke) any metal-containing additives present in the oil may form an ash which is partially deposited out on the various surfaces of the combustion chamber and on those of the spark plugs and valves. Accordingly, it is a particular object of this invention to provide a lubricant composition which is compounded with metalor mineral-free detergents and wear-reducing additives.

While certain of the additives heretofore employed in oils (and to a lesser degree the oil itself) are partially responsible for deposits which form on engine surfaces, it is now recognized that the major source of such deposits or their precursors lies in the various aldehydes, acids, oxy-acids and other similarly reactive, partiallyoxidized combustion products of the fuel. These prodnets are formed both under pre-ignition conditions as well.

as during the combustion step proper, particularly during the period before the engine has reached operating temperature. Accordingly, under city driving conditions where the engine is repeatedly started in the cold condition and is seldom driven for a distance sufiicient to reach the most efiicient operating temperatures, the formation of partial oxidation products is particularly severe. Many of these partial oxidation products are carried down into the crankcase of the engine along with other blow-by gases, and since most are insoluble or only sparingly soluble in lubricating oils, they tend to separate from the oil and adhere to engine surfaces or form large droplets. In either case, under the elevated temperature conditions prevailing in the engine, these reactive monomers quickly polymerize to form solid masses which readily deposit out on the engine wall surfaces.

It is the practice in the art to prevent the formation of such deposits by adding to the lubricant a material normally referred to as a detergent. Insofar as is known, all the detergent additives which have heretofore been successfully employed on a commercial scale are organic, metal-containing compounds such as calcium petroleum sulfonate, calcium cetyl phosphate, calcium octyl salicylate, calcium phenyl stearate, the barium salt of waxsubstituted benzene sulfonate, or the potassium salt of the reaction product of phosphorus pentasulfide and polybutene. Various of these detergents act by reacting chemically with deposit precursors to form harmless compounds. Others act to prevent flocculation or coagulation of solid particles in the oil and maintain the same in a state of suspension as finely divided particles. Still others not only perform this dispersant function but also effect the solubilization or emulsification of the sparingly soluble monomers inthe oil and thereby greatly reduce the rate of polymerization. In the latter case, such polymer materials as. do then form within the body of the oil are smaller in size and can be peptized or dispersed in the oil much more readily than is the case with the large polymeric particles which are formed on exposed engine surfaces or in droplets lying without the oil.

Detergents capable of acting in the latter fashion are preferably employed wherever possible, particularly in automotive engines to be operated under city driving conditions. However, even among the metal-containing additives, few are available which are capable of solubilizing any appreciable amount of all the many types of polymer precursors which are carried into the oil from the fuel. Accordingly, it is a more particular object of this invention to provide a lubricant composition incorporating a metal-free detergent which is capable of solubilizing or emulsifying in the lubricant large amounts of all the various partial oxidation products of the fuel which are carried into the oil, and which is also capable of maintaining in suspension in the oil the various solid polymeric materials which are present therein.

The problem of piston ring and cylinder wall Wear, especially the control thereof, is also one which is closely related to the composition of the crankcase lubricant. Aside from abrasive wear, which is caused by dust and dirt and can be remedied by suitable filtering and aircleaning means, a large part of the wear experienced by piston rings and cylinder wall is attributable to chemical attack by moisture and acidic products originating as byproducts of fuel combustion. In engines operated at optimum temperature levels, these combustion products the lubricating oil with additives such as the various are largely discharged through the exhaust and breather pipe. However, under the relatively cold conditions experienced in city driving, and especially at cylinder wall temperatures below about F., the moisture and acid products are condensed on the engine surfaces where they promote corrosive attack and are in a position to work past the piston and accumulate within the engine. and in the crankcase oil. This difiiculty is one which the art has heretofore met most successfully by supplying 3 metal salts of petroleum sulfonic acids and other metalorganic compounds, especially those having a basic reaction. However, this practice has a disadvantage of adding still another metal-containingingredient to the oil and therefore of increasing the deposit-forming characteristics of the lubricant composition. Accordingly, it forms still another object of this invention to provide a lubricant composition containing a metalor mineral-free additive which effectively decreases the wear experienced by piston rings and cylinder walls, particularly during periods before the engine has become thoroughly warmed to operating temperatures.

The present invention is based on the discovery that certain copolymers, which contain no metal component and therefore are substantially free of any ash-forming tendency, have the ability to impart excellent detergent and antiwear qualities to lubricating oils employed in internal combustion engines. In particular, these copolymers have the ability to solubilize in the oil large amounts of all the various partially oxidized combustion products of the fuels employed in internal combustion engines, while also having the ability of maintaining in a state of suspension any solid polymeric products present in the oil. Additionally, the copolymeric additives of the present invention effectively reduce the wear experienced by piston rings and cylinder wall surfaces even under the most unfavorable operating conditions such as are experienced during the starting and warming up of the engine. These additives have the advantage that they do not combine chemically with the various polymer precursors which are solubilized or dispersed in the oil, nor apparently do they act by a neutralization reaction in counteracting the effect of the various acidic fuel combustion by-products. Accordingly, they are capable of giving excellent protection against engine deposits and wear over extended operating periods. It should also be noted that the copolymeric additives of this invention are noncorrosive to the various bearing metals employed in engines. I

Since the additives of the present invention differ in kind from any heretofore proposed for either detergent or antiwear purposes, it would have been surprising to discover that they were eliective for either of these purposes. However, that they possessed not one but both of said qualities was altogether unexpected and could not have been predicted.

The polymeric additives of the present invention are copolymers of monomers selected from at least each of the first three classes of the classes consistingfof (A) oil-solubilizing compounds haying a polymerizable ethylenic linkage and containing a hydrocarbyl group of from 4 to 30 aliphatic carbon atoms (B) estersof acidic compounds selected from the group consisting of ufi-llnsat'urated monocarboxylic acids of from 3 to 8 carbon atoms each and cap-unsaturated, a,fi-dicarboxylic acids of from 4 to 12 carbon atoms each and anhydrides thereof wherein the carboxyl groups of said acidic compounds are monoester-linked to a member of the group consisting of polya lkylene glycols and alkyl ethers thereof having from 2 to 7 carbon atoms in each alkylene group, '(C) amides and amine salts selected from the group consisting of amides, hydrocarbyl amides, hydrocarbyl amine salts and substituted hydrocarbyl amides and amine salts of afiunsatnrated monocarboxylic acids of from 3 to 8 carbon atoms each and a,B-unsaturated, a,B-dicarboXylic acids of from 4 to 12 carbon atoms each and anhydrides thereof wherein at least one hydrogen atom of said substituted hydrocarbyl group is substituted by at least one polar group selected from the group consisting of hydroxyl and amino groups, (D) acidic compounds selected from the group consisting of ups-unsaturated monocarboxylic acids of from '3 to 8 carbon atoms each, tarp-unsaturated, ot-,5- dicarboxylic acids of from 4 to 12 carbon atoms each, anhydrides thereof and half-esters, halt-amides and monoamine salts thereof, the ester, amide and salt groups being as defined in (B) and (C).

The oil-s0lubilizing monomer portion of the polymeric additives of this invention can be any compound having at least one ethylenic linkage C=C together with at least one substituent group which contains an oilsolubilizing hydrocarbyl group of from 4 to 30 aliphatic carbon atoms, and which is characterized by the ability to copolymerize through said ethylenic linkage with the polar monomer referred to above in the presence of a suitable catalyst. Alternatively, the oil-solubilizing aliphatic radical can be introduced into the copolymer, as will hereinafter be more fully described. This aliphatic radical, whether present in the original monomer or introduced into the copolymer, imparts oil solubility to the polymer and is preferably a branched or straight-chain alkyl radical or a cycoalkyl radical such as butyl, isobutyl, n-pentyl, n-hexyl, Z-ethylhexyl, decyl, dodecyl, tetradecyl, cyclohexyl, 4-ethylcyclohexyl, or the like, or an alkenyl radical such as oleyl, ricinoleyl, or the like, wherein the ethylenic double bond has substantially no copolymerizing tendency. Oil solubilizing monomers of this general character are well known in the art and are frequently erhployed as the oil-solubilizing portion of copolymers which are added to lubricating oils to improve the viscosity index and pour point characteristics thereof. They include such materials as olefins and ethylenically unsaturated ethers, esters, ketones, aldehydes, and the like.

The oil solubilizing monomers of component (A) may also be illustrated by the following general formula:

groups and combinations thereof with not more than two alkylene groups of from 1 to 7 carbon atoms each, and n and'n are 0 or 1. When R and R are hydrocarbon radicals, they may be alkyl, cycloalkyl, alkenyl, cycloalkenyl, aryl, alkaryl or aralkyl in structure, as illustrated by radicals such as 2-ethylh exyl, cyclohexyl, hexenyl, cyclohexenyl, phenyl, na'phthyl, tertiary butylphenyl benzyl, etc., with the preferred radicals being as previously mentioned.

Representative oil-solubilizing monomer compounds which can be employed to form the copolymeric additives of the present invention include the following:

I OLEFIN'S Octndccene-l 4-octylcycloh crane-1 3-phenylhexadeceno-1 Tripropylen'e p-Oetylstyrene Dodecened Vinylcy'clohexane Hexadecene-l Z-hexadecylbutadiene-LB Oyclohexene p-Tertiarybutylstyrenc ETHERS Vinyl n-butyl ether I Proponyl Zethylh'exyl other Vmyl 2-ethylhexyl ether Orotyl n-oetyl ether Allyl n-butyl ether Isopropenyl dodecyl ether Allyl isobutylethcr -1-decenyl butyl other All'yl eyclohexyl ether 1 V H Leic'osenyl decyl ether .tll'yll1 4,4,8,8-tetra;methyl-docosyl vVinyl p-octylph'enyl other Methallyl ether I p l-decenyl p cetylphenyl other l-decenyl 2-phenylbuty1 ether et; er -tert. but 1 hen l Methallyl n-hexyl ether p y p y Methallyl nedecyl ether Methallyl 2-ethylhexyl ether Methallyl octadecyl ether ditives were demonstrated by incorporating the copoly- The lubricant compositions thus obtained were tested to determine their detergency and deposition properties. The results of these tests are In the tests the base oil, unless otherwise indicated, is :a solvent-refined, wax-free, SAE-30 grade mineral lubricating oil having a viscosity index of 85 which is. derived from California waxy crude. Various amounts of the copolymers are incorporated into the oil as indicated The piston varnish ratings of the lubricant compositions were obtained by the standard FL-2 test procedure as set out in the June 21, 1948 report of the Coordinating In this test the lubricating oil compositions were tested as crankcase lubricants in a 6-cylinder Chevrolet engine, using a low-grade gasoline espe- .1 ESTERB Vinyl caproate Cyclohexyl methacrylate mers 111w lubrlcatlng 0115- Vtnyl palmltate Cyclohexyl 2-dodecenoate Vinyl oleate Decyl vlnylacetate fi lyl 1caprylate Isgoctyl ni-clllilorofcrylated t y aura e psoamy p any 2- exa ecenoa e Allyl oleate et-p-tolylbutyl 2-octadecenoate 5 glven Table I below Allyl palmitate Undecyl cinnamate Allyl stearate Methylcyclohexyl 2-ethyl-2- Allyl-2-ethylhexanoate hexenoate Allyl rlcinoleate S-ethyldocosyl crotonate Allyl esters of babassn acids Ootadecyl isocrotonate Allyl esters of lard acids n-Butyl 2-elcosenoate fillylllnfiplhthenatte p-Tegt. t amylphenyl octade-cyl e a y caproa e ma ea c Methallyl' naphthenate p-Hexadecylphenyl 2-ethylhexyl In terms of Percent by Weight Methallyl rleinoleate malcate Methallyl p-octylbenzoate o-Tolyl 2-octadecylcyclohexyl ma- Methallyl oleate leate Mletthallyl cyclohexane carboxyonytllphepyl-lliextadecyl maleate as exa ecy maeae Methallyl palmltate Dl-methylcyclohexyl maleate Research councll' Orotyl oleate M ono-2-ethylhexyl maleate Orotyl naphthenate Di-2-ethylhexyl maleate a-Methylerotyl palmitate Dl-dodecyl maleate l-propenyl naphthenate Di-dodecyl mesaconate l-propenyl elaidate Di-dodecyl cltraconate Dodecyl acrylate o-Tolyl octadecyl itaconatc Hexadecyl methacrylate Mono-hexadecyl itaconate Isobutyl a-decylacrylate Isopropenyl palmitoleate Vinyl p-n-octyl benzoate l-decenyl laurate Allyl 3,5-diisobutyl benzoate l-hexadecenyl myristatc Although any of the oil solubilizing compounds described above will give effective copolymer compositions for lubricant compositions in accordance with the present invention, higher alkyl esters of u,fl.unsaturated monocarboxylic acids of from 3 to 6 carbon atoms having alkyl groups of from 8 to 30 carbon atoms are most preferred, both for availability and effectiveness of copolymers prepared from them.. Representative acids of this type are the acrylic, methacrylic, crotonic, tiglic, angelic, u-ethylacrylic, u-methylcrotonic, a-ethylcrotonic, fi-ethylcrotonic, fl-propylcnotonic, and hydrosorbic acids and the like. Evenmore desirable are the alkyl esters of acrylic and methacrylic acids containing from 10 to 20 carbon atoms inthe alkyl groups, since they are found to provide highly superior polymers for the lubricant compositions of the invention and are obtainable incommercial quantities.

Various copolymers employing representative oil-solubilizing monomers of the foregoing types were prepared toillustrate the oil solubilizing effect of the monomers on the-resultant copolymers. The solubility of the copolymers in oil and their suitability as lubricating oil adcially prone to cause engine deposits. At the end of each test the engine was dismantled and the detergency or deposition properties of the lubricant compositions were determined by examining the engine deposits on the piston and visually rating them as to the amount of piston varnish present. The piston varnish ratings of the compositions are given in numerical terms on a scale of 0-l0 with 10 representing the complete absence of deposits.

The deposition characteristics of the lubricant compositions containing the copolymeric additives were also determined in the lacquer deposition test. In this test typical engine fuel combustion products were passed into the lubricant compositions and the ability of the lubricant compositions to solubilize and retain the lacquerforming materials was observed by weighing the amount of lacquer deposits formed on a fresh iron catalytic surface for a standard period of time. The lacquer deposit of the lubricant composition is taken as the number of milligrams deposit on the metal surface, and may be correlated :directly to the piston varnish rating obtained in the standard FL-Z test procedure outlined in the above paragraph.

Both the FL-2 test procedure and the lacquer deposition test are more fully described in the disclosure which follows with regard to the particular lubricant composition of the present invention.

TABLE I Piston Ratio of varnish (1) monomer Piston Lacquer rating Lubricant composition to (2) varnish deposit (estirnonomer rating (millimated to grams) from monomer lacquer deposit) Base oil alone 3.0 850 2.8% (1) dodecyl methacrylate, (2) N,N-di-2-hydroxy-ethyl malearnide 20/ 450 5.0 2.8% (1) dodecyl methacrylate, (2) allyl stearatc, (3) maleic anhydride- 20/1/1 405 5 z 1.5% (1) dodecyl methacrylate, (2) N -(2-hydroxyethyl) methacrylamlde 7/ 6.3 3.0% (1) tridecyl methacrylate, (2) octadecyl methaerylate, (3) monododecyl other of hexadeoaethylene glycol l methacrylate 10/6/1 8. 4 2.5% (1) allyl stearate, (2) didodecyl maleate, (3) di-(hydroxyethyl) ethylenediamine salt of monododecyl meleate /5/2 5. 5 2.8% (1) vinyl ethylhexoate, (2) itacomc acld 15/1 500 4.5 2.8% (1) vinyl stearate. (2) maleic anhydride, (3) monododecyl ether of pentaethylone glycol b methacrylate (4) methacrylamide 30/1/2/1 325 6.0 2.5% (1) ally] stearate, (2) ethylene glycol mono-oleate monomaleate, (3) mono- N ,N'-di(2-hydroxy-ethyl) ethylenedialuine maleate (salt) 5/4/1 4. O 2.8% (1) octadecene, (2) monododecyl maleate, (3) monopentaerythrrtol maleate 2/1/1 500 4. 6 2.8% (1) hexene-l, (2) dodeoyl-methacrylate, (3) methacrylic acid, (4) monododecyl ether of eicosa-ethylene glycol methacrylate 25/25/1/4 400 5. 6 2.8% (l) di-2rethylhexy] fumarate, (2) oetadecene-l, (3) crotonrc acld, (4) monotridecyl ether of decaethylenc glycol methacrylate 25/25/8/2 570 4. 0 2.8% (l) allylethyl ether, (2) vinyl stearate, (3) itaconlc acid (4) monododecyl ether of decaethylene glycol crotonate 14/50/7/3 3.0% (1) vinyl 2-ethylhexy1 ether, (2) tetradecylphenyl maleate, (3) dodecyl maleate, 6/3/1/2 4 6 4 maleic acid 1.5 (1) dodecyl acrylate, (2) monododecyl ether of decaethylene glycol acrylate (3) acrylic acid 780/9/1 5.6 1.5% (1) heaxdecyl styrene, (2) methacryhc acid 6.8/1 5.9

In Neutral Mineral Lubrlating Oil from solvent-refined waxy California crude.

Polyethylene glycol of 704 M.

Polyethylene glycol of 220 M.W. Polyethylene glycol of 880 M.W. Polyethylene glycol of 440 M.W.

the Maripus oil-.solubilizing monomers representative of theaforementioned types were effective in the production of useful, copolymeric lubricating oil additives which are capable of preventing deposits from lubricant compositions under typical engine operating conditions. These monomers, as previously described, constitute a definite, recognized class of compounds which have been used heretofore in the art in the production of polymeric lubricating oil additives of the nonpolar type, such as VI improvers and pour point depressants. Although the re sl lts demonstrate beyond any reasonable doubt the suitability ,of the ditferent oil-solubilizing monomers within the terms of the description in the production of oil soluble copolymers, it should be understood that the efi'icacy of each individual class of copolymers as detergents is primarily dependent upon the particular polar or functional group in the so-. cal led polar monomer and its relationship to the rest of the copolymer.

Since the functionality of the individual polar groups difiers and is largely empirical in nature, no conclusion is intended to be drawn concerning equivalency of the various copolymeric lubricating oil additives employed as detergents in this illustration. The polar groups of the particular class of copolymers of the compositions of this invention and their balance or relationship to the remainder of the copolymers are more fully discussed in the disclosure which follows, along with additional examples of the invention.

As indicated, the present additives are copolymers of an oil-solubilizing (A) monomer of the type described above and an a,;8-unsaturated .carboxylic acid wherein in the copolymer a portion of the carboxyl groups of said acid is esterified with a polyalkylene glycol and another portion thereof is converted to amides and amine salts. The aforementioned portions may vary so long as there is at least one polyalkylene glycol monoester and at least one amide or amine salt present in the copolymer molecule. The ester, amide and amine salt groupings associated with the carboxyl group as formed therewith may be present in monomer reactants employed in forming the copolymer ,or they may be introduced into an intermediate ttorm of the copolymer by appropriate reaction. While the processes by which the present additives can be formed are discussed more fully below, it may be here noted that suitable copolymers can readily be formed by copolymerizing an olefinical-ly unsaturated, oil-solubilizing ingredient with an u, 3-unsaturated acid or acid anhydride and then partially .esterifying the resulting copolymer a polyalkylene glycol and thereafter reacting it with an appropriate nitrogen compound or vice versa. Alternatively, one may start with a homopolymer such as a higher alkyl polymethacrylate and then partially hydrolyie the same; the [free carboxyl groups so formed thereafter being linked with the desired polyglycol and nitrogen compound.

The afi-UIlSEltllTfliEd carboxylic acids referred to herein can be monocarboxylic in character, as represented by acrylic, methacrylic, crotonic, tiglic and angelic, ra -ethylacrylic, fi-ethylcrotonic, or the like, or they can contain more than one carboxyl group. Representative polycarboxylic acids are maleic, fumaric, itaconic, glutaconic, citraconic, mesaconic and aconitic acids. In referring herein to said acids, and particularly to those of a polybasic character, it is also intended to include a corresponding anhydride thereof where the same are available. Thus, in cases where the copolymer incorporates an ester of maleic acid it is possible to substitute the corresponding anhydride for the acid in forming the copolymer. The resulting anhydride units can be esterified or converted to amides and ami e alt in t e s a ia h s a an an sen earshot thus converted can either be hydrolyzed to carboxyl groups or left as anhydride units in the finished copolymer.

The a-p-unsaturated monocarboxylic acid components of the copolymeric additives employed in this invention have the general formula R1 R3 0 R1..-o =b-o-oH where the Rfs, R s and R s, which can be the as or different from one another, are selected from the group consisting of hydrogen atoms and alkyl groups of from 1 to 4 carbon atoms.

The M -unsa u a d nfi-dicarboxylic id ggmp nsn s o h mb it a d i e have the strustyra emale 0 R3 R 0 II I I ll R -oo=o-o-R4 wherein the R s, which may be the same as or different from one another, are hydrogen atoms or alkyl groups of from 1 to .4 carbon atoms each, and the R s represent (1) in a common (1) a ,common'o radical (in which case the compound is an acid anhydride'), or (2) both Ris represent +01 1 radicals. i

A preferred group of acids for use in the present invention is made up of those which contain not more than 8 carbon atoms, while a particularly preferred group is made up of the one-unsaturated monocarboxylic acids having 3 to 8 carbon atoms.

The polyalk-ylene glycols and alkyl ethers thereof used in the esterification of the copolymeric (l3) and .(D) components of the copolymer additives of'the invention contain from 2 to 7 carbon atoms in each alkylene group, as already mentioned. Poly-1,2-alkylene glycols and their alkyl ethers having molecular weights between 134 and 30,000 are preferred. Such glycols may be obtained by polymerizing 1,2-alkylene oxides or mixtures thereof in the presence of a catalyst and a suitable initia tor for the reaction such as water, monohydric alcohol in the case ofthe alkyl ethers, mercaptan and the like. The preparation of polyglycol compounds of this type has been fully described heretofore in US. Patents 2,448,664 and 2,457,139, for example, and, therefore, requires no detailed discussion here.

For present purposes, the most suitable poly-1,2-alkylene glycols are those derived from ethylene oxide or from 1,-2-propylene oxide or mixtures thereof and their alkyl ethers of l to 18 carbon atoms per alkyl group which have r r ecu a wei hts 9; ave molecular weights between about 200 and 1,000, or higher, preferably between about 400 and 10,000. Esterification with these polyalkylene glycols is found to provide the most effective detergent and wear inhibiting compositions.

The following polyalkylene glycols containing from 2 to 7 carbon atoms in each alkylene group are illustrative of the types described above.

Polyethylene glycol mixtures having average molecular ous compound in an amideor amine salt-linkage, The resulting portion of the copolymer (i.e., the portion made up of a carboxyl group of the acid and the associated nitrogen-containing compound) can be represented by the general formula where C represents the carbon atom of a carboxyl group of the acid component (B) and R is a nitrogen-containingradical having the structure -NR R in the case of amides, or OH-NR R R in the case of amine salts.

In said formulae, the R s (which may be the same as or different from one another) represent hydrogen atoms or organic radicals, and R represents an organic radical. These organic radicals can be either unsubstituted hydrocarbyl radicals, i.e. aliphatic or aromatic hydrocarbon radicals such as methyl, ethyl, propyl, n-butyl, isobutyl, sec.-butyl, tert.-buty1, cyclohexyl, hexyl, 2-ethylhexyl, decyl, dodecyl, heptadecyl, phenyl, tolyl, xylyl, benzyl, naphthyl, or the like, or said radicals can be substituted byv one or more hydroxyl or amino polar groups, representat-ive substituted hydrocarbon radicals being 2- hydroxyethyl, 4-hydroxycyclohexyl, 3-azapentyl, 4-aminohexyl, 3-aza-5-hydroxypentyl, 2-ethyl-6-aminohexyl, p-aminophenyl, 2-hydroxy-6-phenylhexyl, or the like.

In the case of either monoor polycarboxylic acid components, any carboxyl groups not associated with a polyglycol or a nitrogen-containing compound can be left as free carboxyl (or acid anhydride) groups. However, in the case of polymers where but a portion of the carboxyl groups in the molecule are linked to a polyglycol or a nitrogen-containing compound, the remaining carboxyl group or groups in said molecule can be esterified with a suitable monoor polyhydric alcohol. In many cases such alcohol is preferably a C or higher monohydric aliphatic alcohol in order that the over-all oil-solubility of the copolymer may be increased.

While reference has been made above to various exemplary nitrogen-containing radicals which may be amide-or amine salt-linked to the acid component of the copolymer, there is presented below a list of representative monomer components, as formed from suitable acid components and a nitrogen-containing compound, it being observed that in the case of the compounds derived from polycarboxylic acids, free carboxyl or ester-linked groups can also be present:

I. From monocarboxylic acids Methacrylamide N-ethylmethacrylamide N-dodecylmethacrylamide N,N-didodecylmethacrylamide N-( 2-ethylhexyl) -methacrylamide N- Z-hydroxyethyl) -methacrylamide N- 4-aminobutyl) -methacrylamide N,N-dimethylmethacrylamide N- 3-azapentyl) -methacrylamide N-phenylmethacrylamide N,N-ditolylmethacrylamide N-methyl-N-(2-hydroxyethyl)methacrylamide N,N-di (Z-hydroxyethyl) -methacrylamide N (2 hydroxyethyl) N (3 aza hydroxypentyl)- methacrylamide Ethylamine salt of methacrylic acid Ethanolamine salt of methacrylic acid Tetraethylenepentamine salt of methcrylic acid Dihydroxethyl ethylenediamine salt of methacrylic acid Methacrylic acid amide of pentaerythritol mono-(p-amino)benzoate Acrylamide N-methacrylamide N,N-diphenylacrylamide 10 N-methyl-N-dodecylacrylamide N-tolylacrylamide N- 2-hydroxyethyl) -acrylamide N,N-di 2-ethylhexyl) -acrylamide Ethanolamine salt of acrylic acid N- 3-azapentyl-acrylamide N-butyl-N- 2-hydroxyethyl -acrylamide Crotonamide Ethanolamine salt of crotonic acid N,N-diethylcrotonamide Tiglamide II. From polycarboxylic acids Ester of the dodecyl monoether of heptaethylene glycoland N-phenyl maleamic acid Diethanolamine salt of N-(Z-hydroxyethyl)-N-(3-aza-5- hydroxypentyD-maleamic acid Tetraethylene pentomine salt of lauryl maleate Dihydroxyethyl ethylenediamiue salt of maleic acid Pentaerythritol N-(Z-hydroxyethyl)-monomaleamate Ethylamine salt of maleic acid Ethanolamine salt of maleic acid Di(ethylamine) salt of maleic acid Dodecyl N-(p-aminophenyl)-maleamate N,N-di- (p-hydroxyphenyl) -maleamide Fumaramic acid N-dodecyl-fumaramic acid N-(Z-hydroxyethyD-fumaramic acid N,N'-di- Z-hydroxyethyl) -fum aramide Ester of poly-1,2-propylene glycol and fumaramic acid N-2,3 -dihydroxypropyl) -N-(2-aminoethyl) fumaramide Cetyl fumaramate Erythritol monofumaramate N,N-di 2-hydroxy-4-aminohexy1) -citraconarnide Dodecyl N-(Z-hydroxyethyl)-citraconamate The preferred nitrogen-containing compounds to be amideor amine-salt linked to the carboxyl group of the acid component to form (C) and (D) compounds are primary and secondary amines wherein the nitrogen atom, is linked to either one or two alkyl radicals of not more than 20 carbon atoms which are either unsubstituted, or are substituted'by one or more polar groups, and many such compounds are presented in the foregoing list.

The copolymers employed in a practice of this invention can be prepared by any one of the methods known in the art. Thus, one may polymerize a mixture of the desired monomer components to form the desired polymer, an exemplary monomer mixture being one containing (A) dodecyl methacrylate, (B) polyethylene glycol methacrylate, (C) N-dodecyl methacrylamide and, optionally, (D) methacrylic acid. However, in many cases the reaction is easier to control by starting with suitable precursor compounds, the desired monomer units of the finished copolymer then being formed by the applopriate treatment of the resulting polymeric intermediate product. Thus, one may first copolymerize a given oil-solubilizing compound such as dodecyl rnethacr'ylate 11 with a suitable acid componentsuch as-methacrylic acid of maleic anhydride; the resulting copolymen can-thereafter be partially esterified with -apolygly'col and therrreacted with a nitrogen-containing-compound such as an amine to convert part or all of the remaining carboxyl groups of the polymer intermediate-to the desired-amideor amine-salt linkagw When the polymeric additive of this invention, or a suitable polymeric intermediate, isto be'prepared by reaction of monomeric components, said polymers canbe prepared by conventional bulk, solution or emulsion methods in the presence of an addition polymerization initiator. Preferably, however, the copolymerization is effected in an inert organic solvent such as benzene, toluene, xylene or petroleum naphtha in the presence of a free radical-liberating type of initiator suchas aperoxy compound, for example, benzoyl peroxide, acetyl peroxide, tertbutyl hydroperoxide,- di-tertbutyl peroxide, dibenzoyl peroxide, or; di-tert.amyl peroxide, oran azo initiator such as 1 ,lazo-dieyclohexanecarbonitrile or a,oc'-aZ0dllSOb11t61'ODitl'il6. The catalyst, or polymerization initiator, can be employed-inan amount of from about 0.1 to with a preferred range being from 0.10 to 2%. If desired, the catalyst can be added in increments as the reaction proceeds. Likewise, additional portions of the solvent can also-be added from time to time in order to maintain the-solution in a homogeneous condition. The temperature of copolymerization varies from about" L70 to 300" F., with the optimum temperature for any given preparation depending on the nature ofi-the solvent, the concentration of monomers present in the solvent, the catalyst, and theduration of the reaction. Much the sameconditions are employed when the copolymerization iseffected in bulk rather than in the presence of an inert solvent.

In preparing the copolymers of this invention, it is important to obtain a final product which is oil soluble, i.e., which is soluble in the-petroleum or other lubricating oil employed, to the extent of at'least 0.5 and preferably 2% or more by weight. Since the various oil-solubilizing monomer components difier somewhat in. their oilsolubilizing characteristics, preliminary. tests are made with the polymeric additiveto determine whether the relative proportion of Qil solubiIiZing monomer compound in the-copolymer ishigh enoughto impart the desired degree of oil solubility. If the solubility in oil is. unduly ,low, and if there remain uncombined carboxyl groupsin the copolymer, the oil-solubility thereof can normally be remedied bytesterifying a portion of said carboxyl groups with a higher alcohol, e.g.,- a C or higher aliphatic alcohol such as n-octanol, Z-ethylhexanol, decanol, dodecanol (lauryl alcohol) or thelike, or by repeating the polymerization reaction and employing ahigher proportion of the oihsolubilizingcomponent (A) in relation to the other components of the molecule. In general, good oil solubility coupled with the ability to impart excellent antiwear' and detergent properties to oils can be obtained with copolymers incorporating from about 1 to 20 monomer units of the'oil-solubilizing component (A) for each monomer unit of the n e-unsaturated acid and its polyglycol and nitrogenous derivatives, and wherein in each polymer molecule there are present from about 1 to 10 monomer units each of the monoester-linked polyalkylene glycol and the amide or amine salt-linked nitrogenous components. Preferably, there are employed those copolymers which incorporate from 3 to 15'monomer units of the oil-solubilizing: component (A) for each monomer unit of the ext-unsaturatedacid component, and wherein thereare presentfrom 2 to hydrocarbon radicals of'the type whichcontain' a group of from 4 to 3.0 aliphatic carb'oQr'iatoms and are capable of impartin'g oil solubility to thepolymer; for ea'cli' ester linked polyglycol' unit and eacharmde' or airline sz'ilt linkt'a'dunit present: inj the co" polymer, there being present from 1" to 4=monomerunits 12 each of the lattefr componentsin the preferred copolymeric acldi-tives Although effective' copolymer'staccording to'- the inven tion are obtained with proportions of oil-solubilizing (A) T monomer units and polar (B );-(C) and (D) monomer units within the aforementioned ranges, it has been noted that in a preferred application of the copolymeric lubricating oil detergent additives of the present invention in mineral. lubricating oil, a certain optimum relationship aliphatic carbon atoms and the total number of polar groups within the molecule. This optimum relationship which isterme'd Polar Balance for convenience, is expressedby the formula Z- (N @X P PB- Na in which PB=polar; balance, N,,=number of a certain where-R is an organic radical as herein described and preferably an alkyl or substituted alkyl radical of not more-than 20- carbon atoms and R" is hydrogen or an organic radical as defined, for R) the polarity constant is 50. For alkylene oxide groups (RO-, where R- the, polarity constant is 15. The solubilizing aliphatic carbon atoms-to be considered are the following:

and excluding aromatic ring carbon atoms and the carbon atom of carbonyl groups.

The polar balance of a given copolymer according to the above formula is equal to the sum of the number 1 of each type of polar group-multiplied by itspolarity constant, said sum being the'n' divided by thenumber of solubilizing aliphatic carbon atoms. For best performance, the polar balance i's-app'roxirnately 1. However, very eifective copolymeric lubricating oil detergent additives may have polar balances in the range from 0.30 to 3.00.

The copolymer additives of the invention have apparent 122 g. (0.48 mole) of dodecyl meth'acr-ylate, 1.3 g

J (0.015 mole) of methacrylic acid, 21.3 g. (0.03 m0le)-of' appearsfltoexist betwe'enpthe' total number of solubilizingis an alkylene group, preferably ethylene or propylene) '13 tridecyl-capped decaethylene glycol methacrylate (molecular weight 708), and 2.9 g. (0.015 mole) of N-2-ethylhexyl methacrylamide were charged to a three-necked flask fitted with a stirrer, thermometer, reflux condenser,

and dropping funnel. The mixture was stirred and heated to 220-225 F. A solution of 3 g. of benzoyl peroxide in 30 cc. of benzene was added dropwise to the reaction mixture over a period of 6 hours. After about 6 cc. of the solution had been added a temperature surge was observed. The maximum temperature reached was 260 F. The mixture was cooled by external means to 225 F. and the reaction temperature was maintained at this temperature for the remainder of the catalyst addition. 'It was then kept at 194F. for an 18-hour period. 500 cc. of benzene was then added. The polymer was precipitated from the benzene solution with 4 volumes of methanol The resulting product, 133 g., was a viscous, oil-soluble polymer which was shown by analyses to contain dodecyl methacrylate, methacrylic acid, tridecylcapped decaethylene glycol methacrylate, and N-Z-ethylhexyl methacrylamide in a molar ratio of approximately EXAMPLE II 152 g. (0.6 mole) of dodecyl methacrylate, 1.8 g. (0.025 mole) of acrylic acid, 17.7 g. (0.025 mole) of tridecyl-capped decaethylene .glycol methacrylate, and 3.2 g. (0.025 mole) of ,B-hydroxyethyl methacrylamide were charged to a reaction vessel as described in the preceding example. The mixture was heated to 220-225 F. with stirring. Catalyst solution was added to the mixture as in Example I above. The mixture thickened perceptibly after the addition of 0.35 g. of benzoyl peroxide, and the temperature was maintained at 220-225 F. for 4 hours. Another 0.35 g. of catalyst was added and the mixture kept at the same temperature for another three hours. At this point about one liter of xylene was added. The solution was filtered and then concentrated to about 600 cc. The polymer was precipitated with 4 volumes of methanol and taken up in lubricating oil to give 112 g. of polymer as a 27% concentrate. dicated that the polymer contained dodecyl methacrylate, acrylic acid, tridecyl-capped decaethylene glycol methacrylate, and fi-hydroxyethyl methacrylamide in a molar ratio of approximately 24/1/1/1.

EXAMPLE III 95 g. (0.375 mole) of octadecene, 36.7 g. (0.375 mole) of maleic anhydride, 47.2 g, of dodecyl-capped polyethylene glycol methacrylate (molecular weight 954), and 1000. of butanone were charged to the reaction vessel as previously described. The mixture was heated to 220-225" F. with stirring. Catalyst was added to the reaction mixture in small installments until thickening occurred. The total reaction time was about 25 hours. The product was stripped to 400 F. at 1 mm. mercury to remove unreacted octadecene and maleic anhydride. 1145 g. of a viscous, oil-soluble product was obtained. Analyses of the material indicated that the polymer contained octadecene, maleic anhydride, and dodecyl-capped polyethylene glycol methacrylate in a molar ratio of about 8/8/ 1 100 g. of the above octadecene-maleic anhydride-dodecyl-capped polyethylene glycol methacrylate copolymer, 0.7 g. (0.0115 mole) of ethanolamine (about theory amine for the amidification of 3% of the available free acid), 0.2 g. of'p-toluene sulfonic acid monohydrate, and xylene were charged to a three-necked flask fitted with a stirrer, thermometer, reflux condenser, and water receiver. The mixture was stirred and heated at reflux, 320 F., for one hour. 98 g. (0.43 mole) of lauryl alcohol (50% excess of theory for the esterification of 94% of the available free acid) was added and enough xylene was withdrawn byjdistillation to give a reflux'temperature of 350 F. The contents were maintained at this tempera- Analyses of the viscous polymer-oil mixture in- 14 ture for 10 hours. The product was stripped of solvent and unreacted lauiyl alcohol and then taken up in benzene. The polymer was precipitated with methanol alcohol to give 134 g. of material which was shown by analyses to be a ternary copolymer of octadecene, maleic anhydride, dodecyl-capped polyethylene glycol methacrylate in which 8% of the available free acid was arnidified with ethanolamine and 75% of the acid was esterified with lauryl alcohol. The product thus obtained was a copolymer of octadecene, didodecyl maleate, dodecyl acid maleate, dodecyl 2-hydroxyethy1maleamate, dodecyl ether of hexadecaethylene glycol methacrylate in 40/ 20/ 12/8/ 5 mole ratio.

EXAMPLE IV 126 g. (0.5 mole) of dodecyl methacrylate, 1.2. g..

(0.014 mole) of methacrylic acid, 20 g. (0.028 mole) of tridecyl-capped decaethylene glycol methacrylate (molecular weight 708), and 2.4 g. (0.014 mole) of N,N-dimethylaminopropyl methacrylamide was charged to the polymerization vessel as described previously. The mixture was stirred and heated to 220-225 F. A solution of 3 g. of benzoyl peroxide in 30 cc. of benzene was added dropwise over a period of 2% hours. Little or no thickening occurred during this time. Addition of 0.75 g. of bulk catalyst in small installments during the next hour resulted in some polymerization. After stirring the mixture at 220225 F. for one hour, and adding another 0.75 g, of catalyst appreciable thickening occurred. The addition of toluene diluent in small portions was required to' control stirring. Another 0.5 g. of catalyst was added over the next hour and stirring continued for an additional 1 /2 hours. 600 cc. of benzene was then added to the mixture, and the polymer was precipitated with about 5 volumes of methanol. The product was re-precipitatedv from a benzene solution and then taken up in lubricating oil to give 129 g. of polymer as a 21% concentration.

Analyses of the concentrate indicated that the polymer contained dodecyl methacrylate, methacrylic acid, tridecyl-capped decaethylene glycol methacrylate, and N,N- dimethylaminopropyl methacrylamide in a molar ratio of 156/ 3/ 8/4.

. EXAMPLE V 50 g. (0.184 mole) of tridecyl methacrylate, 41 g. (0.124 mole) of octadecyl methacrylate, 2.64 g. (0.031 mole) of methacrylic acid, 9.6 g. (0.0135 mole) of tridecyl-capped decaethylene glycol methacrylate (molecular weight 712), g. of mixed hexanes, and 0.35 g. of benzoyl peroxide were charged to a three-necked resin flask fitted with a stirrer, thermometer, and reflux condenser. The mixture was stirred and heated at reflux temperature, F. for 5 /2 hours. At this point lubricating oil was added to the mixture and hexanes were removed by distillation to give a 40% polymer concen- ,trate. Analyses of the product indicated a quaternary copolymer composed of tridecyl methacrylate, octadecyl methacrylate, methacrylic acid, and tridecyl-capped polyethylene glycol methacrylate in a molar ratio of about 4.'08/2.72/0.7/0.3.

A mixture of 250 g. of the above copolymer concentrate and 3.1 g. (0.0305 mole) of N,N'-dirnethylaminopropylamine was stirred at 200-220 F. for two hours. Analyses of the mixture indicated approximately 50% of the acid in the polymer was converted to the N,N'-

dimethylaminopropyl ammonium salt. The product thus obtained was the copolymer of tridecyl methacrylate, octadecyl methacrylate, methacrylic acid, tridecyl ether of decaethyleneglycol methacrylate, N,N-dimethylaminopropyl amine methacrylate in 12/ 8/ 1/ 1/1 molar ratio.

EXAMPLE VI (molecular Weight 454), 1.4 g. (0.0167 mole) of methacrylarrrid'e', and; 10 cc. ofbenzene werecharged to a three-necked flask fitted with a--st-irrer, thermometer, re= flux condenser; and dropping funnel. The mixture was heatedto 220225 F. with stirring. A solution 0133.4 g; of} ben-zoyl-peroxide in 35 cc. of benzene was added overa 6-hour' period." The mixture was stirred andheated to 225 F. for another hour after all catalyst had beenadded. 1.5 liters of xylene were added,- thesolution was filtered, and then concentrated to about 800 cc. The

polymer was precipitated with 4 volumes of methanol" a'nd takenup in a lubricating oil to give 119 g. of polymer as a 43% concentrate. The polymer wasshown by analyses to contain vinyl stearate, maleic anhydride, dodecyl-capped pentaethylene glycol methacrylate, and methacrylamide in a molar ratio of 148/ 5/ 4.-

EXAMPLE VII 2g. (0.02 mole) of maleic anhydride, 203 g. (0.8 mole) of dodecyl methacrylate, 21.5 g. (0.01 mole)-of dodecyl-capped tritetracontaethylene glycol methacrylate; (molecular Weight 2154), 2.5 g. (0.02 mole) of tertiary butyl acrylamide, and 500 cc of benzene Were charged to-the polymerization vessel as described above.- The mixture was stirred and heated at reflux temperature. A solution of 5 g. of benzoyl-peroxide-in 50 cc. of ben zene-was added over a 6-hour period. Themixture was,v

methac'rylate, and tertiary butyl acrylamide in a molar' ratio of 2/74/1/3. In general, excellent detergent and antiwear properties can be imparted to lubricating oils by dissolving therein aquantity of fromabout 0.1 to 10% by'weight of the copolymers of the type described above, although a pre-. ferred range is from about 0.5 to 5% by weight. The copolymeric additives of this invention can be used with good efiect in the case of any one of a wide variety of oils of lubricating viscosity, or of blends of such oils. Tlius,- the base oil can be a refined Pennsylvania or other paraffin base oil, a refined naphthenic base oil, or a synthetic hydrocarbon or non-hydrocarbon. oil of lubricating viscosity. As synthetic oils there can be mentioned alkylated: waxes and similar alkylated hydrocarbons of relatively high molecular weight, hydrogenated polymers of hydrocarbons, and the condensation products of chlorinated alkyl hydrocarbons with aromatic compounds. Other suitable oils are those which are obtained by polymerization of lower molecular weight alkylene oxides such as propylene and/or ethylene oxide. Still other synthetic oils are obtained by etherification and/or esterification of the hydroxy groups in alkylene oxide polymers such as, for example, the acetate of the 2- ethylhexanol-initiated polymer of propylene oxide. Other important classes of synthetic oils include the various esters as, for example, di(2-ethylhexyl) sebacate, tricresyl phosphate and silicate. esters. If desired, the oil can be a mixture of mineral and synthetic oils.

While satisfactory lubricant compositions can be ob tained by adding to the base oil employed only one or more of the copolymeric additives of the type described above, it also falls within the purview of this invention to provide lubricant compositions which contain not only such copolyrners, but also other additives such as pour point depressants, oiliness and extreme pressure agents, antioxidants, corrosion inhibiting agents, blooming agents, thickening agents, and/or compounds for enhancingthe temperature-viscosity characteristics of'the oil, The present invention also contemplates the addition' to the lubricant composition, pa'rticularlywhen:

1 6 the amount of copolymer employed-is relatively small) of auxiliary detergents and/or ant-iw'ear agents;

The efficacyof" copolymeric'additives of the type de-' scribed above asdetergents'and'anti-wear agents in lubricating oils is illustrated by data from a number of tests. In the tests from which the data is obtained the base oil, unless otherwise specified, is a solvent-refined, wax-free SAE-30 grade'mineral lubricating oil having aviscosity index of 8-5 which is derived-from (Dalifornia waxy crude. Various amounts-of the copolymeric additives are incorporated into the oil as noted in terms of percent by weight.

In thelacquer deposition test the low temperature detergency of'the oils tested is'measuredby determining the ability ofthe-oilto solubilizeand retain typical engine fuel' deposits and precursors thereof] which are formed due to incomplete combustionof the fuel. Retention of these deposits in a given oil' depends upon their dispersal and upon minimizingtheir polymerization' to lacquer.

Briefly described, the Lacquer Deposition. Test involves condensing fresh cool flame oxidation products'froma standard test fuel simulatingth'e fuel combustion products of an internal combustion-engme ina: steel. vessel containing a certain amount of' the lubricating oil being: tested. The steel': surface of the vessel actsras, an lroncatalyst for polymerization ofthe fuel: oxidation products to. lacquer in the same manner. as the steel surfaces in an internal combustion engine." After the'oxidation products have. been condensed, thesteel vessel containingthe: lubricating oil is heated for 24 hours at a-temperature selected-to correspond withv actual engine condi tions; The test oil is: then decantedwhile hot from the lacquer deposits formedin the. steel vessel due-to polymerization and the lacquer deposits areide-oiled and weighed.

In the actual test' a lowgrade gasoline: is employed of the type described in connectionwith the standard FL2 test procedure" given below. The: gasoline at a rate of 133 cc; per hour is vaporized and mixed with air, the airratebeing 1.75 liters perfminute. The vapor mixture of gasoline and air is then fed into an elongated cocl flame combustionchamber of: standard design-having-a diameter of 1 /2 inches. The cool'flame combustion chamber is maintained at 695 F. The' t'est 'is continued for 1 hour during which the oxidation products issuing from the cool flame combustion chamber are condensed into the weighed steelcatalyst-vessel which contains 30 g. of the oil: being tested at about room temperature.

The'steelvessel containing test'oiland'condensed oxidation' 'products is then heated for 24 hours ati1l0 F. The

oil is decanted fromthe lacquerdeposits-in the. vessel,

following which: the deposits are. die-oiled: by washing The increase. in weight of the steel vessel due to the lacquer depositsisthendetermined with petroleum solvent;

and recorded'in-milligrams as LB or: lacquer: deposit. The lacquer deposit for any' given lubricant com.- position' obtained in accordance Withthe. procedure de-.

scribed. above is: directly correlated tothe piston varnish rating or PVR obtained'for thesa'me lubricant composition in the standard EL-2 test: procedurepreviously referred to and hereinafter more particularly described. Table II which follows: gives the correlated values for both the-lacquer deposits and piston varnish ratings.

17 The correlated values in the above table provide an accurate means for estimating from the lacquer deposits determined for a given oil the piston varnish rating to be obtained in the standard FIr-Z Chevrolet engine test.

'18 amount of deposit on each piston skirt and averaging the individual ratings so obtained for the various pistons. Under the conditions of this test, a piston varnish rating of 4.5 is indicative of satisfactory performance, though -fia z ea gge g Venus]? preferably this rating should be 5 or above. The wear g1 en cqmpoemon 1s teste experienced by the piston rings during the test is also the crankcase lubncant in a -cylmder Chevrolet engine measured 1n certain cases and expressed in mgs. of metal using a low grade gasoline especially prone to cause engine 1 h 5 h deposits, the conditions being those defined in the stan- 0st per per out Is regarded-as saflsfactory dard FL-2 test procedure as described in the June 21 thmlgh Preferably the shmild be 3 less e 1948 report of the Coordinating Research Council. This f In the of i base 011 alone wlthput the i 1- procedure requires the maintenance of a jacket temperaany adqltlves 1t found the Plstn varmsh we f 5 F. and a crankcase oil temperature of rating 1s approximately 3.0 and the piston ring weight loss F. at 2500 r.p.m. and 45 brake horsepower of 40 hours, 15 mgS/hron the other hand as lndleated by the and therefore closely simulates the relatively cold en- 5 'data Presented 111 Table III bdow, When the base Oil is gine conditions which are normally experienced in city compounded With the indicated amounts of a copolymer, driving. At the end of each test, the en ne is dismantled reatl su erior results are obtained.

gl 8 Y P TABLE III Piston Ratio of(1) Lacquer varnish V V monomer to Piston deposit rating (as- Lubricant composition (2) monomer to varnish (mlllitimated (3) monomer, rating grams) from etc. lacquer deposit) Base oil al n 3.0 850 1.5% copolymer of (1) dodecyl methacrylate, (2) methacrylic acid, (3) heptadecenyl-ZJ]ydrqxyethyl imidazoline methacrylate and (4) dodecyl ether of decaethylene glycol methacrylate in base 11 7/0. 7/0. 1/0. 4. 7 1.2% copolymer of (1) tridecyl methacrylate, (2) octadecyl methacrylate, (3) methaorylamide and (4) trldecyl ether of decaethylene glycol methacrylate in base oil 1 4/3/0. 7/0. 3 5. 6 2.8% copolymer of (1) dodecyl methacrylate, (2) methacrylic acid, (3) tridecyi ether of decaethylene glycol methacrylate and (4) N -2-ethylhexyl methacrylamideinbase oil 58/2/3/2 160 9. 4 2.8% copolymer of (1) dodecyl methacrylate, (2) acrylic acid, (3) trldecyl ether of decaethylene glycol methacrylate and (4) N-2-hydroxyethyl methacrylamide in base oil 24/1/1/1 286 6. 9 2.8% copolymerof (1) octadecene, (2) dldodecyl maleate, (3) dodeoyl acid maleate, (4) dodecyl 2- I hydroxyethyl maleamate and (5) dodecyl ether of hexadecaethylene glycol methacrylate in base oil- /20/12/8/5 705 3, 5 2.8% copolymer of (1) dodecyl methacrylate, (2) methacrylic acid, (3) tridecyl ether of decaethylene glycol methacrylate and (4) N, N'-dimethylaminopropyl methacrylamide in base oil 156/3/8/4 283 6. 9 2.8% copolymer of (1) tridecyl methacrylate, (2) octadecyl methacrylate, (3) methacrylic acid, (4)

tridecyl other of decaethylene glycol methacrylate, and (5) N, N-dimethylaminopropyl amine "methaorylate in base oil... 1 /8/1/l/1 165 9.1 2.8% copolymer of (1) vinyl stearate, (2) maleic anhydride, (3) dodecyl other of methacrylate, and (4) methacrylamide in base oil 148/5/10/4 325 6. 1 2.8% copolymer of (1) doclecyl methacrylate, (2) maleic anhydride, (3) dodecyl, ether of tritet contaethylene glycol methaorylate and (4) tert. butyl acrylamido in base oil 74/2/1/3 170 9. 0

l 140 Neutral mineral lubricating oil from solvent-refined waxy California crude containing 27 mlllimoles/kg. calcium alkyl phenate sulfurized, having an average of 13 carbon atoms per alkyl group derived from propylene polymer and 12 millimoles/kg. zinc butylhexyl dlthlophosphate.

and the amount of engine deposits on the piston determined and expressed as the piston varnish rating. This value is obtained by visually rating (on a scale of 0 to 10, with 10 representing the absence of any deposit) the The utility of still other lubricant compositions in accordance with the invention in which various representative oils of lubricating viscosity are employed is illustrated by the additional examples given in the following table:

TABLE IV Ratio of (1) monomer to Viscosity Viscosity Lubncant composition Base 011 (2) monomer at F., at 210 F., Viscosity to S.S.U. S.S.U. index monomer,

Etc.

Base all alone ,140 neutral mineral 139. 4 42. 13 A 9 lubricating oil. 2.8% copolymer of (1) dodecyl methacrylate, (2) methacrylic acid, (3) tridecyl do 58/2/3/2' 2001; 50,4 135 ether of'deoaethylene glycol methacrylate and (4) N-2cthylhexyl methacryl- 1 amide in base oil. l 2.8% copolymer of (1) dodecyl methacrylate, (2) acrylic acld, (3) tridecyi ether of do 24/1/1/1 248. 5 57. 86 1 145 degaethylene glycol methacrylate and (4) N-Z-hydroxyethyl methacrylamide in ass or 2.8% copolymer of (1) octadecene, (2) didodecyl maleatc, (3) dodecyl acid maleatc, do 40/20/12/8/5 150. 9 43. 63

(4) dodecyl 2hydroxyethyl maleamate and (5) dodecyl ether of hexadecaethylene glycol methacrylate in base oil. 2.8% copolymer of (1) dodecyl methacrylate, (2) methacryhc acid, (3) tridecyl do 166/3/8/4 295- 66.03 149 other of decaethylene glycol methacrylate and (4) N, N -d1methy1aminopropyl methacrylamide in base oil. I 2.8% copolymer of (1) tridecyl methaorylate, (2) octadecyl methacrylate, (3) do 12/8/1/1/1 280 58.1

methacrylic acid, (4) tridecyl other of decaethylene glycol methacrylate, and .(5) N ,N-dimethylamh1opropyl amine methacrylate in base oil. 2.8% copolymer of (1) vinyl stearate, (2) maleic anhydrlde, (3) dodecyl ether of do 148/5/10/4 252.1 55. 5 135' pentaethylene glycol methacrylate and (4) methacrylamrde in base oil. 2.8% copolymer of (1) dodecyl methacrylate, (2) maleic anhydnde, (3) dodecyl -do 74/2/1/3 212.1 51.6 135' gtlhgr of tritetracontaethylene glycol methaorylate and (4) tert. butyl acrylamide ass or. Base oil alon 7 Mixed hexyloctyl 45. 19 33. 62 183 orthosilioate. 2.8% copolymer of (1) dodecyl methacrylate, (2) methacrylic acid, (3) tridecyl do 58/2/3/2 63.8 .37. 1 240 etligr 101: gecaetiliylene glycol methacrylate and (4) N -2-ethyl.hexyl methacrylam e aseo 2.8% copolymer of (1) dodeoyl methaorylate, (2) acrylic acid, (3) tridecyl ether of --do 24/1/1/1 cs. 86 42. 7 232 1i ifc z aet'hyil ene glycol methacrylate and (4) N-2-hydroxyethy1 methacrylamide eseo v TABLE IV-Continued Lubricant composition Ratio of (1) monomer to Base 011 (2) monomer Viscosity Viscosity Viscosity to (3) at 100 F., at 210 F., index monomer, S.S.U. S.S.U

Etc.

2.8% copolymer of (1) dodecyl methacrylate, (2) methacrylic acid, (3) tridecyl ether of decaethylene glycol methacrylate and (4) N ,N-dimethylaminopropyl methacrylamide in base oil. 2.8% copolymer (5) N,N-dimethylaminopropyl amine methacrylate in base oil. 2.8% copolymer (1) (lodecyl methacrylate,

in base oil. Base oil lon 2.8% copolymer mide in base 011.

2.8% copolymer of (l) dodecyl methacrylate, (2) acrylic acid, (3) tridecyl ether of glycol methacrylate and (4) N -2-hydroxyethyl methacrylamide 2.8% copolymer of (1) octadecene, (2) didodecyl maleate, (3) dodecyl acid maleate, (4) dodecyl 2-hydroxyethyl maleamate and (5) dodecyl ether of hexadecaethyldeoaethylene in base oil.

ene glycol methacrylate in base oil. 2.8%

methacrylamide in base oil. 2.8% copolymer of (1) tridecyl methacrylate, (2)

(5) N,N-dimethyl-aminopropyl amine methacrylate in base oil.

2.8% copolymer of (1) dodecyl methacrylate, (2) maleic anhydride, (3) dodecyl ether of trit'etracontaethylene glycol methacrylate and (4) tert.butyl acrylamide in base oil. Base oil alone pl (1) tridecyl methacrylate, (2) octadecyl methacrylate, (3) methacrylic 801d, (4) tridecyl ether of decaethylene glycol methacrylate, and

(2) maleic anhydride, (3) dodecyl ether oftritetracontaethylene glycol methacrylate and (4) tert. butyl acrylamide of (l) dodecyl methecrylate, (2) methacrylic acid, (3) tridecyl ether of decaetliylene glycol methacrylate and (4) N-2-ethylhexyl methacrylacopolymer of (1) dodecyl methacrylate, (2) methacrylic acid, (3) tridecyl ether of deco-ethylene glycol methacrylate and (4) N,N- dlmethylaminopropyl octadecyl methacrylate, (3) mcthacrylic acid, (4) tridecyl ether of decaethylene glycol methacrylate, and

Mixed hexyloctyl orthosilicate.

Octyl oxy octapropylene glycol acetate.

2.8% copolymer of (l) ether of decaethylene amide in base oil.

in base oil 2.8% copolymer of (l) octadecene, (2) didodecyl maleate, (3) dodecyl acid maleate,

(4) dodecyl 2-hydroxyethyl maleamate and (5) dodecyl other of hexadecaethylone glycol methaerylate in base oil.

2.8% copolymer 0! (1) dodecyl methacrylate, (2) methacrylic acid, (3) tridecyl ether of decaethylcne glycol methacrylatc and (4) N,N-dimethylaminopropyl methacrylamide in base oil.

2.8% copolymer of (1) tridecyl methacrylate, (2) octadecyl mcthacrylate, (3) methacrylic acid, (4) tridecyl ether 01' decaethylene glycol methacrylate, and

(5) N,N'-dimethylaminopropyi amine methacrylate in base 0 2.8% copolymer of (1) vinyl stcarate,

ether of tritctracontaethylene glycol amide in base oil.

dodecyl methac rylate, (2) idethacrylic acid (3) tridecyl glycol methacrylate and (4) N -2-ethyll1exyl methacryl- 2.8% copolymer of (1) dodecyl methacrylate, (2) acrylic acid, (3) tridecyl ether of decaethylene glycol methacrylate and (4) N-2-hydroxyethyl methacrylamide il (2) maleic anhydride, (3) dodecyl ether of pentaethylene glycol methacrylate, and (4) methacrylamide in base oil 2.8% copolymer of (l) dodecyl methacrylate, (2) maleic anhydrrde, (3) dodecyl methacrylate and (4) tert. butyl acryl- Dioctyl phthalate. do 58/2/3/2 From the tests of the foregoing table it will be seen that each of the illustrative compositions containing the copolymeric lubricating oil additives according to the invention possess improved lubricating properties compared to the base oils alone.

In the foregoing description of the invention, the term hydrocarbyl is used with reference to the class of organic groups commonly known as hydrocarbon groups. As employed herein, this term is considered to be a more convenient and concise generic expression for describing said hydrocarbon groups.

This application is a continuation-in-part of Lowe, Stewart and Stuart, Patent Application Serial No. 360,837, filed June 10, 1953, now abandoned.

We claim:

1. An oil-soluble copolymer of the monomers including at least (A), (B) and (C) of the following: (A) polymerizable oil-solubilizing compounds selected from the group consisting of olefinic hydrocarbons, olefinic ethers containing a single oxygen atom and hydrocarbon carboxylic acids containing at most two carboxy groups fully esterified with monohydroxy hydrocarbons, said compounds having a single ethylenic linkage and containing a monovalent hydrocarbon group of from 8 to 30 aliphatic carbon atoms, (B) esters of acidic compounds selected from the group consisting of 0a,,B-fithYlenically unsaturated monocarboxylic acids of from 3 to 8 carbon atoms each and afi-ethylenicafly unsaturated, a,fl-dicarboxylic acids of from 4 to 12 carbon atoms each wherein the carboxyl groups of said acidic compounds are monoester-linked to a member of the group consisting of poly-1,2-a1kylene glycols and monoalkyl ethers thereof having from 2 to 7 carbon atoms in each alkylene group and a molecular weight between about 200 and 10,000, (C) polymerizable compounds selected from the group consisting of unsubstituted amides, N-hydrocarbon amides, N-hydrocarbon amine salts and substituted N-hydrocarbon amides and N-hydrocarbon amine salts of 00,;3-81113'1- enically unsaturated monocarboxylic acids of from 3 to 8 carbon atoms each and corresponding diamides and diamine salts of a,,8-ethylenically unsaturated, 0:,[3- dicarboxylic acids of from 4 to 12 carbon atoms each wherein the substituent on said substituted monovalent hydrocarbon group is at least one polar group selected from the group consisting of hydroxyl and amino groups, (D) acidic compounds selected from the group consisting of a,B-ethylenically unsaturated monocarboxylic acids of from 3 to 8 carbon atoms each, a,fi-ethylenically unsaturated, a,/3-dicarboxylic acids of from 4 to 12 carbon atoms each, and anhydrides, half-esters, halfamides and monoamine salts of said dicarboxylic acids, the ester, amide and salt groups being as defined in (B) and (C), said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the light scattering method and from about 1 to 20 monomer units of the oil-solubilizing component (A) for each monomer unit of the (B), (C) and (D) components.

2. An oil-soluble copolymer of (A) a polymerizable oil-solubilizing compound, said compound being selected from the group consisting of olefinic hydrocarbons, olefinic ethers containing a single oxygen atom and hydrocarbon carboxylic acids containing at most two carboxy groups fully esterificd with monohydroxy hydrocarbons,

said compound having a single ethylenic linkage and containing a monovalent hydrocarbon group .of from 8 to 30 carbon atoms, (B) esters of u,/3-ethylenically unsaturated monocarboxylic acids of from 3 to 8 carbon atoms each wherein the carboxyl groups of said acids are monoesterlinked to a member of the group consisting of poly-1,2- alkylene glycols and monoalkyl ethers thereof having from 2 to 7 carbon atoms in each alkylene group and a molecular weight between about 200 and 10,000, (C) substituted N-hydrocarbon amides of a,fi-ethylenically unsaturated monocarboxylic acids of from 3 to 8 carbon atoms each wherein the substituent on said substituted N-hydrocarbon group is at least one polar group selected from the group consisting of hydroxyl and amino groups and (D) a, 3-ethylenically unsaturated monocarboxylic acids of from 3 to 8 carbon atoms each, said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the light scattering method and from about 1 to 20 monomer units of the oil-solubilizing component (A) for each monomer unit of the (B), (C) and (D) components.

3. An oil-soluble copolymer of (A) a polymerizable oil-solubilizing compound, said compound being selected from the group consisting of olefinic hydrocarbons, olefinic ethers containing a single oxygen atom and hydrocarbon carboxylic acids containing at most two carboxy groups fully esterified with monohydroxy hydrocarbons, said compound having a single ethylenic linkage and containing a monovalent hydrocarbon group of from 8 to 30 carbon atoms, (B) esters of oz, B-ethylenically unsaturated, c, p-dicarboxylic acids of from 4 to 12 carbon atoms each wherein the carboxyl groups of said acidic compounds are monoester-linked to a member of the \group consisting of poly-1, 2-alkylene glycols and monoalkyl ethers thereof having from 2 to 7 carbon atoms in each alkylene group and a molecular weight between about 200 and 10,000, (C) substituted N-hydrocarbon diamides of a, p-ethylenically unsaturated, a,,B-dicarboxylic acids of from 4 to 12 carbon atoms each whenein the substituent on said substituted N-hydrocarbon group is at least one polar group selected from the group consisting of hydroxyl and amino groups and (D) a, ,B-ethylenically unsaturated, a, B-dicarboxylic acids of from 4 to 12 carbon atoms each, said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the light scattering method and from about 1 to 20 monomer units of the oil-solubilizing component (A) for each monomer unit of the (B), (C) and (D) components.

4. An oil-soluble copolymer of (A) an alkyl methacrylate having from 8 to 30 atoms in the alkyl group and (B) an ester of an a, p-ethylenically unsaturated monocarboxylic acid of from 3 to 8 carbon atoms, in which the carboxyl group on said acid is monoester-linked to a poly-1, 2-alkylene glycol having a molecular weight between about 200 and 10,000, and (C) an amide of a monocarboxylic acid as defined in (B) in which the carboxyl group of said monocarboxylic acid is amide-linked to a primary unsubstituted N-alkyl amine of not more than 20 carbon atoms, said (A), (B) and (C) compo- 22' nents being present in the monomer ratio of from 1 to 20 of the (A) monomer units for each monomer unit of the (B) and (C) compounds and said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the standard light scattering method.

5. An oil-soluble copolymer of (A) an alkyl methacrylate having from 8 to 30 atoms in the alkyl group and (B) as ester of an a, B-ethylenically unsaturated monocarboxylic acid of from 3 to 8 carbon atoms, in which the carboxyl group on said acid is monoester-linked to a poly-l, 2-alkylene glycol having a molecular weight between about 200 and 10,000, and (C) and amide of a monocarboxylic acid as defined in (B) in which the carboxyl group of said monocarboxylic acid is amidelinked to a primary polar group substituted N-alkyl amine of not more than 20 carbon atoms in which the polar group substituent is selected from the group consisting of hydroxyl and amino groups, said (A), (B) (C) components being present in the monomer ratio of from 1 to 20 of the (A) monomer units for each monomer unit of the (B) and (C) compounds and said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the standard light scattering method.

6. An oil-soluble copolymer of (A) dodecyl methacrylate, (B) tridecyl ether of decaethylene glycol methacrylate, (C) N,N'-ethylhexy1 methacrylamide and (D) methacrylic acid, said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the light scattering method and from about 1 to 20 monomer units of the oil-solubilizing (A) component for each monomer unit of the (B), (C) and (D) components.

7. An oil-soluble copolymer of (A) a mixture of tn'decyl methacrylate and octadecyl methacrylate, (B) tridecyl ether of decaethylene glycol methacrylate, (C) N,N- dimethylaminopropyl amine methacrylate, and (D) methacrylic acid, said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the light scattering method and from about 1 to 20 monomer units of the oil-solubilizing (A) component for each monomer unit of the (B), (C) and (D) components.

8. An oil-soluble copolymer of (A) a mixture of tridecyl methacrylate and octadecyl methacrylate, (B) tridecyl ether of decaethylene glycol methacrylate and (C) methacrylamide, said oil-soluble copolymer having an apparent molecular weight of at least 2,000 as determined by the light scattering method and from about 1 to 20 monomer units of the oil-solubilizing (A) component for each monomer unit of the (B) and (C) components.

References Cited in the file of this patent UNITED STATES PATENTS 2,047,398 Voss July 14, 1936 2,666,044 Catlin Jan. 12, 1954 2,704,277 Giammaria Mar. 15, 1955 2,737,496 Catlin Mar. 6, 1956

Claims (1)

1. AN OIL-SOLUBLE COPOLYMER OF THE MONOMERS INCLUDING AT LEAST (A), (B) AND (C) OF THE FOLLOWING: (A) POLYMERIZABLE OIL-SOLUBILIZING COMPOUNDS SELECTED FROM THE GROUP CONSISTING F OLEFINIC HYDOCARBONS, OLEFINIC ETHERS CONTAINING A SINGLE OXYGEN ATOM AND HYDROCARBON CARBOXYLIC ACIDS CONTAININJG AT MOST TWO CARBOXY GROUPS FULLY ESTERIFIED WITH MONOHYDROXY HYDROCARBONS, SAID COMPONDS HAVING A SINGLE ETHYLENIC LINKAGE AND CONTAINING A MONOVALENT HYDROCARBON GROUP OF FROM 8 TO 30 ALIPHATIC CARBON ATOMS, (B) ESTERS OF ACIDIC COMPOUNDS SELECTED FROM THE GROUP CONSISTIN OF A,B-ETHYLENICALLY UNSATURATED MONOCRBOXYLIC ACIDS OF FROM 3 TO 8 CARBON ATOMS EACH AND A,B-ETHYLENICALLY UNSATURATED, A,B-DICARBOXYLIC ACIDS OF FROM 4 TO 12 CARBON ATOMS EACH WHEREIN THE CARBOXYL GROUPS OF SAID ACIDIC COMPOUNDS ARE MONOESTER-LINKED TO A MEMBER OF THE GROUP CONSISTING OF POLY-1,2-ALKYLENE GLYCOLS AND MONOALKYL ESTERS THEREOF HAVING FROM 2 TO 7 CARBON ATOMS IN EACH ALKYLENE GROUP AND A MOLECULAR WEIGHT BETWEEN ABOUT 200 AND 10,000, (C) POLYMERIZABLE COMPONDS SELECTED FROM THE GROUP CONSISTING OF UNSUBSTITUTED AMIDES, N-HYDROCARBON AMIDES, N-HYDROCARBON AMINE SALTS AND SUBSTITUTED N-HYDROCARBON AMIDES AND N-HYDROCARBON AMINE SALTS OF A.B-ETHYLENICALLY UNSATURATED MONOCARBOXYLIC ACIDS OF FROM 3 TO 8 CARBON ATOMS EACH AND CORRESPONDING DIAMIDES AND DIAMINE SALTS OF A.B-ETHYLENICALLY UNSATRUATED, A.BDICARBOXYLIC ACIDS OF FROM 4 TO 12 CARBON ATOMS EACH WHREIN THE SUBSTITUENT ON SAID SUBSTITUTED MONOVALENT HYDROCARBON GROUP IS AT LEAST ONE POLAR GROUP SELECTED FROM THE GROUP CONSISTING OH HYDROXYL AND AMINO GROUPS, (D) ACIDIC COMPOUNDS SELECTED FROM THE GROUP CONSISTING OF A.B-ETHYLENICALLY UNSATURATED MONOCARBOXYLIC ACIDS OF FROM 3 TO 8 CARBON ATOMS EACH, A,B-ETHYLENICALLY UNSATURATED, A,B-DICARBOXYLIC AICDS OF FROM 4 TO 12 CARBON ATOMS EACH, AND ANHYDRIDES, HALF-ESTERS, HALFAMIDES AND MONOAMINE SALTS GROUPS BEING AS DEFINED IN THE ESTER, AMIDE AND SALT GROUPS BEING AS DEFINED IN (B) AND (C), SAID OIL-SOLUBLE COPOLYMER HAVING AN APPARENT MOLECULAR WEIGHT OF AT LEAST 2,000 AS DETERMINED BY THE LIGHT SCATTERING METHOD OF FROM ABOUT 1 TO 20 MONOMER UNITS OF THE OIL-SOLUBILIZING COMPONENT (A) FOR EACH MONOMER UNIT OF THE (B), (C) AND (D) COMPONENTS.