US3001942A

US3001942A - Lubricant composition

Info

Publication number: US3001942A
Application number: US780216A
Authority: US
Inventors: Paul K Mulvany; William W West
Original assignee: California Research LLC
Current assignee: California Research LLC
Priority date: 1958-12-15
Filing date: 1958-12-15
Publication date: 1961-09-26
Anticipated expiration: 1978-09-26

Description

United States Patent:

3,001,942 LUBRICANT COMIKSITION Paul K. Mnlvany, Richmond, and William W. West, El

Cerrlto, Calif aedgnors to California Research Cor- This invention relates to a novel lubricant composition. More particularly, the invention is directed to a novel lubricant composition having improved properties for the lubrication of internal combustion engines.

The advancements made in the design of internal combustion engines during recent years have emphasized the need for improved lubricating oil compositions. It is not enough that a lubricant composition act as a coolant and a friction reducer for moving parts 'of the internal combustion engine. It must also help to prevent the formation of solid deposits on the inner surfaces of the engine which tend to accelerate wear of moving parts and also impede uniform flow of the lubricant.

It has been pointed out that the solid deposits in engines of the internal combustion type are due, not only to the formation of decomposition products from the lubricating oil and fuel, but also to a metal ash formed by the decomposition of the several metal-containing additives which are usually present in internal combustion engine lubricants as detergents and wear reducing agents. As the combined solid deposits accumulate during operation of the engine, additional metal-containing detergents and wear inhibitors are. required and they, in turn, decompose and contribute still further to the deposits within the engine. lIIl their US. patent applications Ser. No. 340,378, filed March 4, 1953; Ser. No. 400,757, filed December 28, 1953; and Ser. No. 400,758, filed December 28, 1953, all now abandoned and replaced by ap plications Ser. Nos. 574,635, now abandoned, and 574,636, now US. Patent No. 2,892,820, both filed March 29, 1956, Messrs. Frank A. Stuart, William T.- Stewart, Warren Lowe, and Frank W. Kavanagh have described a novel class of unusually effective metal-free detergents and wear inhibitors for internal combustion engine lubricant compositions. These metal-free additives are polymeric derivatives of an olefinic oil-solubilizing compound, an optional unsaturated monocarboxylic acid and an ester of a polyglycol and an unsaturated monocarboxylic acid. Lubricant compositions containing these metalfree polymeric additives are capable of maintaining large amounts of internal combustion engine decomposition products in solution and greatly reduce the wear of rubbing surfaces.

In order for the lubricant composition to function properly in the internal combustion engine, it must be capable of flowing freely through oil lines and between moving engine parts at the lower ranges of temperatures ordinarily encountered when an engine is started up. The temperature at which a lubricant composition ceases to flow or pour is called its"pour point." If a lubricant composition does not have a suitably low pour point, the fact that it is avery effective detergent and wear inhibitor will make no difference since it will be unable to flow and penetrate between rubbing surfaces during the starting up period of the engine operations, at which time surface deposits and wear are extremely critical.

Practically all of the common base oils of lubricating viscosity which are employed in lubricant compositions have undesirably high pour points and are incapable of providing proper lubrication during low temperature operation of an engine such as is encountered during the starting up period. In such cases, it is necessary to modify the flowing properties of the base oil so as to lower its Patented Sept. 26, 1961.

pour point. This is commonly done by the addition of agents which are termed pour depressants since they act in combination with the base oil to depress its pour point.

From the above description it can be readily seen that proper lubrication of the present day internal combustion engine presents many problems. Because of these problems there is a constant demand for the continued improvement of lubricant compositions. So far there has been no single solution for the problem. One agent may be added to the lubricant composition to prevent deposition of solid products. Another may be employed simultaneously to reduce wear of rubbing metal parts. Still another additive is needed to render the composition soluble at lower temperatures of operation. Even though the polymeric additive of Stuart, Stewart, Lowe and Kavanagh, referred to above, is very efiective in preventing solid deposits of combustion products and reducing wear of rubbing parts while at the same time avoiding the formation of metal ash, it is generally still necessary to add a pour depressant in order that the lubricant composition may function properly in the internal combustion engine during its critical starting up period.

It is therefore an object of this invention to provide novel lubricant composition.

It is a more particular-object of the invention to provide a novel lubricant composition having improved properties for the lubrication of internal combustion engines.

Another and still more particular object of the invention is the provision of a lubricant composition having improved detergent properties.

It is another particular object of the invention to provide a lubricant composition having enhanced wear reducing ability.

A further object of the invention is the provision of a lubricant composition of improved detergency and wear reducing properties which does not give objectionable metal ash deposits upon decomposition.

I the use of but a single additive.

It is a still further object of the invention to improve the pour point of oils of lubricating viscosity.

Another particular and very important object of theinvention is the provision of a lubricant composition possessing all of the above desirable properties through Still other objects of the invention will be the disclosure which follows hereinafter.

The multi-functional additives of the, lubricant compositions of this invention are polymers of at least the (A), (B) and (D) monomers of the following: (A) an alkyl ester of a lower aliphatic il-unsaturated monocarboxylic acid in which the alkyl group contains from 4 to 30 carbon atoms, (B) an alkyl ester of the same or another lower aliphatic o e-unsaturated monocarboxylic acid in which the alkyl group contains a different number in the range of 4 to 30'carbon atoms, which is 4 to 16 carbon atoms more than the alkyl group of said (A) alkyl ester, (C) a lower aliphatic timnsaturated monocarboxylic acid, and (D) an ester of a polyoxy-1,2-alkylene glycol and a lower aliphatic il-unsaturated monocarboxylic acid. These polymeric additives are employed with a major portion of an oil of lubricating viscosity in minor amounts sufficient to enhance the detergent characteristics of the lubricant composition and depress the p'our point thereof.

The lubricant compositions of the invention are capable of maintaining largeamounts of combustion products in solution thus preventing the formation of solid deposits on surfaces in internal combustion engines. The wearing of rubbing parts of engines is also effectively reduced. No objectionable metal ash deposits are formed as decomposition products of the lubricant compositions. Compared to the base oil employed, the lubricant compositions of the invention are characterized by remarkapparent from such as those encountered in starting up operations of in tcrnal combustion engines. It is indeed surprising that all of these improved properties are obtained in the lubricant compositions of the invention with the use of but a single additive.

The alkyl esters of a lower aliphatic t p-unsaturated monocarboxylic acid having from 4 to 30 carbon atoms in the alkyl group constitute a definite class of materials. They include such esters as butyl acrylate, dodccyl methacrylate or lauryl methacrylate, hexadecyl methacrylate, isooctyl a-chloroacrylate, hexadecyl a-methylcrotonate, octacosyl methacrylate, tricosyl a-ethylcrotonate, tricontyl tiglate, pentadecyl angelate, etc. A preferred group of esters are the alkyl esters of acrylic and methacrylic acid in which the alkyl group contains from 4 to 20 carbon atoms.

The optional (C) monomer component of the present copolymeric additives is an u,p-unsaturated monocarboxylic acid, preferably one of the type having the general formula where R R and R;,, which can be the same 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. Representative acids of this type, any one or more of which can be employed in forming the copolymers hereof, are acrylic, methacrylic, crotonic, tiglic, angelic, a-ethylacrylic, a-methylcrotonic, u-ethylcrotonic, fl-ethylcrotonic, a-butylcrotonic, and the like. A more preferred group of acids for use in the present invention comprises those of the type indicated by the above structural formula which contain a total of from about 3 to 8 carbon atoms in the molecule, as represented by the acids listed above. A still more preferred group of acids is made up of acrylic and methacrylic acids.

The (D) component of the present polymeric additives is an ester of a lower aliphatic tarp-unsaturated monocarboxylic acid (of the type defined in the preceding paragraph) and a polyoxy-1,2-alkylene glycol. The polyglycols which can be used in forming said esters have molecular weights between 106 and 10,000, or higher, preferably between about 134 and 30,000. These polyglycols are of the type obtained by polymerizing one or more 1,2-alkylene oxides in the presence of a catalyst and suitable reaction initiator, e.g., water, a monohydric alcohol, a glycol, an acid, amine, mercaptan, or the like. The resulting polymer materials are polyoxyalkylene glycols, or polyoxyalkylene glycols wherein one or both of the terminal OH groups are replaced (either during the polymerization reaction or subsequently thereto) by alkoxy, acyloxy, or other end groups. Methods for synthesizing said polyglycol compounds are well known in the art and need not further be described here, reference being made to US. Patents Nos. 2,448,664 and 2,457,139, for example, for a description of such methods.

The preferred polyglycol materials for employment in the present invention are those which are formed from ethylene oxide, from 1,2-propylene oxide, or from mixtures of said oxides, and which have molecular weights between about 200 and 2,000, or higher, preferably between about 400 and 10,000.

The polymeric glycols employed in forming the ester component (D) of the copolymeric additive can be a single compound of relatively pure nature such as triethylene glycol, pentaethylene glycol, nonaethylene glycol, tetra-1,2-propylene glycol, monobutyl ether of heptaethylene glycol, or the like, though as a general rule the polyglycol material employed (and hence the (D) monomer component itself) will be a mixture of polymeric molecules of varying chain length, structure, and molecular weight. Accordingly, in referring herein to the molecular weight of the polyglycol material, reference is had to either a relatively pure compound or to the average molecular weight of a mixture of such compounds.

The ester, or (D) component of the polymer can be described as one of the type (or a mixture of compounds, each of the type) having the general structural formula where R R, and R,, as indicated above in connection with the definition of the (C) component, are preferably hydrogen atoms or C -C alkyl radicals, the R s are 1,2- alkylene radicals, n is an integer greater than 1, and R is a hydrogen atom or a substituted or unsubstituted hydrocarbon group, the substituent groups here contemplated being the polar groups where the R 's and the Rfs are hydrogen atoms or hydrocarbon groups. Preferably, however, a still more preferred group of (D) monomer components is made up of those compounds wherein, in the above structural formula, R and R, represent hydrogen atoms, R, represents hydrogen or a methyl group, the R s are ethylene or propylene groups, and R. is hydrogen or an alkyl group of from 1 to 18 carbon atoms. Representative (D) monomer component esters coming within this more preferred grouping are esters of acrylic or methacrylic acid with the following glycol polymers:

l-lO-(CH CH,-O),H HO-(CH,CH --0),--H Ho cH, cH,0)-,--H HO(CH CH- O) H HO--(C H,O),-H HO(C;H O)-,H HO(CH -CH,OC,H;O) H HO(CH,CH -0),--CH; HO(CH,CH,-O) C,H rz rrn zs 2 z l8"" 1l 8'I Polyethylene glycol mixtures having average molecular weights of 200, 400, 1000, 1540 or 2000. Poly-1,2-propylene glycol mixtures having average molecular weights of 425 or 1025.

In addition to the above exemplary (D) monomer components, it should also be noted that good results can be obtained with acrylates and methacrylates of polyglycols such as the following wherein the terminal, or R group is a polar-substituted radical:

. O HO-(CHrCHh-Oh-ii-CH In preparing the copolymers of this invention, it is important that the ratio of the (A), (B), (C) and (D) components to one another be such as to ensure that the finished polymeric material will be soluble in the petroleum or other lubricating oil employed to the extent of at least 0.5% by weight and preferably 2% or more, in addition to imparting the desired antiwear, detergent and pour depressant characteristics to the oil. Since the various (A) and (B) components differ somewhat in their oil-solubilizing characteristics, and since the (D) component (and to a lesser extent the (C) component) tends to exert an oil-insolubilin'ng effect of greater or lesser magnitude on the polymer, the optimum monomer component ratios in a copolymer will depend on the particular components. Accordingly, as a general rule, preliminary tests are preferably made with the contemplated polymeric additive to determine whether the ratio of (A) and (B) to (C) and .(D) components is high enough togive the desired degree of oil solubility. In general, however, satisfactory oil-solubility, antiwear and detergeney properties are obtained with polymers wherein the (A) and (B), or oil-solubilizing components, constitute from about 75 to 97 mole percent, or more, for example, 99.9 mole percent of the over-all polymer composition, with the (C) and (D), or polar monomer components representing a total of from 25 to 3 mole percent, or less, for example, 0.1 mole percent of the polymer composition, there being in all cases at least one and usually several monomer units of each of said (D) polyglycol ester monomer component in the copolymer. Expressed percentagewise, of the total polar monomer content of the copolymer, the (C), or acid component constitutes from 0 to 97 mole percent, while the (D), or polyglycol ester component from 100 to 3 mole percent. Preferred ranges can be established within the aforesaid ranges for particular polymers and classes of polymers coming within the scope of this invention. Thus, with copolymers of (A) and (B), a higher alkyl methacrylate (e.g., l-auryl methacrylate), (C) acrylic or methacrylic acids, and (D) an acrylate or methacrylate of a polyethylene glycol or a polypropylene glycol, or a monoalkyl ether of said glycols, or mixture of said glycols or glycol others, or a polyglycol monoether, there preferably is employed from 80 to 92 mole percent of the oil-solubilizing, (A) and (B) components, while the balance of the polymer is made up of from 65 to 90 mole percent of the (C) component and 35 to mole percent of the (D) component.

Any mixtures of the alkyl radicals containing from 4 to 30 carbon atoms and preferably from 4 to 20 carbon atoms will effect a desirable reduction in the pour point of lubricant compositions containing the polymeric additives in accordance with this invention. The alkyl radicals may vary widely in chain length, as in the case when n-butyl methacrylate and stearyl methacrylate are employed. Preferably the alkyl radicals will not differ by more than 16 carbon atoms and not less than 4 carbon atoms. In these cases, it is preferred to employ from 50 to 80 mole percent of the shorter alkyl ester with 20 to 50 mole percent of the longer to obtain the greatest reduction'in pour point.

The copolymers employed in a practice of this invention can be prepared by any one of several methods, as known in the art. Thus, one may polymerize a mixture of (A), (B), (C) optionally, and (D) monomer components to form the desired copolymer. It is also possible to form the desired copolymer by first preparing a'suitable polymer intermediate and then subjecting the latter material to an appropriate treatment to form the finished polymer. Thus, one may copolymerize given oil-solubilizing (A) and (B) compounds such as the alkyl methacrylates with a suitable (C) component acid such as acrylic or methacrylic acid; the resulting polymer is then reacted with a polyglycol whereby a portion or all of the free -COOH groups in the polymer intermediate becomes ester-linked to the polyglycol. Instead of forming an intermediate copolymer by thus reacting the (A), (B) and (C) components, one may start with a homopolymer such, for example, as poly(dodecyl methacrylate), this homopolymer being first partially hydrolyzed to free the desired portion of its --COOH groups, after which the correct portion or all of the latter is then esterified with a suitable different alkylalcohol and a suitable polyglycol material. Other possible variations in the nature of the reactants andin the selection of a suitable reaction path would also suggest themselves to those-skilled in the art.

. When.the polymeric additive of this invention, or a suitable polymeric intermediate, is to be prepared by reicate types.

prepared by conventional bulk, solution or emulsion methods in the presence of an addition polymerization initiator such as benzoyl peroxide, acetyl peroxide, tert. butyl hydroperoxide, di-tert. butyl peroxide, or di-tert. amyl peroxide, or an azo initiator such as 1,l'-azodicyclohexanecarbonitrile or ,a-azodiisobutyronitrile. The catalyst, or polymerization initiator, can be employed in an amount of from about 0.1 to 10%, with a preferred range being from about 0.25 to 2%. If desired, the catalyst can be added in increments as the reaction proceeds. An inert .solvent can be employed, if desired, and, as is the case with the catalyst, 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 to 300 F., with the optimum temperature for any given preparation depending on the nature of the solvent, .the concentration of monomers present in the solvent, the

catalyst, and the time of the reaction. The copolymers formed by such methods which are useful in a practice of the present invention have an apparent molecular weight of at least 2,000 and preferably of at least 8,000. In the main, however, they have apparent molecular weights of 20,000 or more. For practical purposes, molecular weights of from 100,000 to 1,000,000 are most suitable from the standpoint of viscosity and other physical characteristics of the polymeric additives.

Any of the well-known types of oils of lubricating viscosity are suitable base oils for the compositions of the invention. They include hydrocarbon or mineral lubricating oils of naphthenic, parafiinic, and mixed naphthenic and paraflinic types. They may be refined by any of the conventional methods such as solvent refining and acid refining. Synthetic hydrocarbon oils of the alkylene polymer type or those derived from coal and shale may also be employed. Alkylene oxide polymers and their derivatives such as the propylene oxide polymers and their ethyl esters and acetyl derivatives in which theterminal hydroxyl groups have been modified are also suitable. Synthetic oils of the dicarboxylic acid ester type including dibutyl adipate, di-Z-ethylhexyl sebacate, di-n-hexyl fumaric polymer, dilauryl azelate, and the like may be used. Alkyl benzene types of synthetic oils such as tetradecyl benzene, etc. are also included. Liquid esters of acids of phosphorus including tricresyl phosphate, diethyl esters of decane phosphonic acid, and the like may also be employed. Also suitable are the polysiloxane oils of the type of polyalkyl, polyaryl, polyalkoxy andpolyaryloxy siloxane such as polymethyl siloxane, polymethylphenyl siloxane, and polymethoxyphenoxy siloxane and silicate ester oils such as tetraalkyl and tetraaryl silicates of the tetra-Z-ethylhexyl silicate and tetra-p-tert.-butylphenyl sil- The following examples of the preparation of the novel copolymeric detergents, wear inhibitors and pour depressants in accordance with the invention are submitted as additional illustrations. Unless otherwise specified, the proportions given are on a weight basis.

EXAMPLE 1 The following reactants were charged to a 3-liter resin jar equipped with a thermometer, a reflux condenser and a stirrer: 150 grams of oxotridecyl methacrylate, 124 grams of tallow methacrylate, 8.05 grams of 91% active methacrylic acid, 27.4 grams of decaethylene glycol tridecyl ether methacrylate, 1.99 grams of benzoyl peroxide, and 309 milliliters mixed hexanes.

The resin jar was partially immersed in an oil bath maintained at F. and the reactants stirred at the reflux temperature for 8 hours. At the end of this reaction period, 383 grams of a low viscosity mineral lubricating oil were added as a diluent. The mixed hexanes were stripped from the resulting oil solution to provide a finaction of monomeric components, said polymers can be 75 ished concentrate containing 40% of polymeric additives.

7 EXAMPLE 2 To a 3-liter resin jar of the type described in Example 1 were charged 75 grams of oxotridecyl methacrylate, 62 grams of tallow methacrylate, 4.03 grams of 91% active methacrylic acid, 13.7 grams of decaethylene glycol tridecyl ether methacrylate, 1.0 gram of benzoyl peroxide and 155 milliliters of mixed hexanes. The materials were reacted for 8 hours at a temperature of 190 F. under refluxing conditions as described in the above example. 383 grams of 140 neutral mineral lubricating oil were added as a diluent and the mixed hexanes stripped from the resulting oil solution to give a concentrate containing approximately 20% of the polymeric additive.

The remarkable ability of the improved lubricating oil compositions of this invention to flow at low temperatures is effectively illustrated by evaluating them in the Pour Point Test. In these tests there is employed a variety of polymeric additives containing different proportions of mixed alkyl methacrylates (A) and (B). For the purpose of comparison a synthetic mixture of polymeric additives obtained by simply mixing the polymer of (A) oxotridecyl methacrylate, (C) methacrylic acid, and (D) decaethylene glycol tridecyl ether methacrylate with the polymer of (B) tallow methacrylate, (C) methacrylic acid, and (D) decaethylene glycol tridecyl ether methacrylate in ditferent proportions is also tested. In both cases, the molar ratio of alkyl methacrylate, methacrylic acid and decaethylene glycol tridecyl ether methacrylate was maintained at 8.3/ 0.8/0.2.

The oxotridecyl group referred to above and hereinafter is one obtained from a primary branched-chain alcohol of l3icarbon atoms produced by the x0 process. The tallow group is one obtained from a predominantly straight-chain alcohol of 18 carbon atoms produced by hydrogenation and hydrolysis of tallow, also referred to as a "stearyP group.

The pour point tests are performed in accordance with ASTM method D-97. In this test the sample is maintained at a temperature of 115 F. or lower for at least 24 hoursprior to the test. The sample is then cooled systematically under quiescent conditions and observed at intervals of F. The pour point is the lowest temperature at which the oil flows when the container is tilted. Illustrative test results are given in the following table:

Table 1 Pour Point, F.

Mole Per- Mole Percent A cent B Synthetic Mixed Mixture Alkyl copolymer 0 100 +18 +18 10 90 +16 +12 25 75 +10 0 35 66 +5 -10 60 50 +3 -Ill 65 35 +3 ---40 100 0 +3 +3 in the following table.

tridecyl ether methacrylate in which the polyethylene glycol group has an average molecular weight of about 1800. In each test 0.3% of the copolymer is employed in SAE 10W solvent refined paraffinic type mineral lubricating oil. The ASTM method pour point, as described above, is then obtained. Illustrative test results are given Table II Mole Percent A Mole Percent B Pour Polnt, Dodecyl Trldecyl Oetadecyl F.

Meth- Meth- Methacrylate ncrylate acrylate The above test results show that the neutral type copolymers of the invention in lubricating oils possess the same sort of improved lower pour points already shown as characteristic of the free acid-containing copolymers of the invention. When the aforedescribed percentages of mixed alkyl esters, including the higher octadecyl methacrylate, are used, pour point improvements amounting to decreases of as much as 35 F. are obtained. This is surprising since the octadecyl methacrylate copolymers themselves have higher pour points and would be expected to increase rather than decrease the pour point of the dodecyl and tridecyl methacrylate copolymers when incorporated therein.

As shown by the test results of the above tables, the lubricating oil compositions according to this invention possess improved pour points compared to similar compositions containing polymeric additives characterized by a single type alkyl ester. It is further evident from the above data that this improvement is a particular effect of the mixed alkyl ester polymeric additives since lubricat- ,ing oil compositions containing comparable amounts of simple mixtures of polymers of varying alkyl groups do not provide the same degree of enhancement.

The efiectiveness of the lubricating'oil compositions of the invention as detergents and wear inhibitors is evaluated in a series of engine tests. The method employed in these tests is that described for the FL-2 Engine Test in the June 21, 1948, Report of the Coordinating Research Council. In accordance with this method, the compounded oil is employed as the crankcase lubricant in a 6-cylinder Chevrolet engine operated with a low grade gasoline especially prone to cause engine deposits. A jacket temperature of 95 F. and a crankcase oil temperature of F. are maintained. The engine is operated at 2500 r.p.m. under a load of 45 brake horsepower for 40 hours. Cold engine conditions normally experienced in city driving are thus closely simulated. At the end of each test the engine is dismantled and the amount of engine deposits on the piston determined and expressed as the average piston varnish rating. This value is obtained by visually rating the amount of deposit on each piston and averaging the individual ratings so obtained for the various pistons on a scale of 0 to 10 with 10 representing the absence of any deposits.

The lubricant compositions taken for the purpose of illustration in the test comprise a solvent refined SAE 30 mineral lubricating oil as the base oil, to which is added 2% by weight of an alpha-pinene-P S oxidation inhibitor. The polymeric additive in these illustrative example: is

present in the amount of "1.6% by weight polymer based on the total composition.

Table III Molar Pro rtions Average Piston of A, B, and D Piston Ring Polymeric Additive Components in Varnish Wear Polymeric Additive Rating (rugs! hour) None (base oil alone) 3. 5 5. Oxotrldecyl methacrylate/tab low methacrylate/methacryllc acid/decaethylene glycol tridecyl ether methacrylate 3. 7/2. 4/0. 70/0. 30 6. 5 2. 7 Oxotridecyl methacrylate/tallow methacrylate/methacrylic aeid/decaethylene glycol tridecyl ether methacrylate 4. 31/2. 88/0. 70/0. 30 6. 6 2. 9 Octadecyl methacrylate] stearyl methacrylate methacrylic acld/decaet ylene glycol propyl ether methacrylate 4. 20/2. 80/0. 70/0. 30 7. 1 3. 1 Butyl methacrylate/stearyl acrylate/acryllc acid/methacrylate of lauryl monoether of polyethylene glycol (Average Molecular Weight- 440) 2. 30/4. 31/0. 70/0. 30 6. 7 2. 8

The efiectiveness of the lubricant compositions of the invention as detergents and wear inhibitors is readily apparent from the illustrative test data of the above table. The base oil containing only the conventional oxidation inhibitor gives an average piston varnish rating and piston ring wear of 3.5 and 5.0, respectively, whereas the improved compositions of the invention containing the illustrative polymeric additives give results in the order of 7 and 3, respectively. 1

Although the compositions of the invention have bee primarily described as crankcase lubricants for internal combustion engines, they are also useful as turbine oils, hydraulic fluids, instrument oils, constituent oils in grease manufacture, ice-machine oils, and the like.

In general, excellent detergent and antiwear properties can be imparted to lubricating oils by dissolving therein a quantity of from about 0.1 to 10% by weight of the polymers of the type described above, although a preferred range is from about 1 to 5% by weight. 0n the other hand, since the polymers of this invention are compatible with mineral and other lubricating oils in substantially all proportions, as much as 75% of the present polymeric additives can be dissolved in a suitable lubricating oil for the purpose of preparing a concentrate capable of dilution with lubricating oils and the like to prepare the final lubricant composition. Such concentrates, which may also contain other additives in desired either free of mineral-containing (i.e., ash-forming) components, or contains but asmall percentage thereof, it is preferable that the additives supplied the oil composition be of the mineral-free variety.

This application is a continuation-in-part of our copending application Serial No. 436,729, filed June 14, 1954, and now abandoned.

We claim:

1. -A lubricant composition comprising a major portion of an oil of lubricating viscosity and a minor portion sufiicient to enhance the detergent characteristics of the composition and depress the pour point thereof of an oil-soluble polymer which comprises (A) an alkyl ester of a lower aliphatic cap-unsaturated monocarboxylic acid of from 3 to 8 carbon atoms, said alkyl ester being characterized by an alkyl group of from 4 to 30 carbon atoms, (B) an alkyl ester of a lower aliphatic c p-unsaturated monocarboxylic acid of from 3 to 8 carbon atoms, said alkyl ester being characterized by an alkyl group of from 4 to 30 carbon atoms, which is from 4 to 16 carbon atoms more than the alkyl group of said (A) alkyl ester, (C) a lower aliphatic a,fl-unsaturated monocarboxylic acid of from 3 to 8 carbon atoms, and (D) a monoester of a polyoxy-1,2-alkylene glycol and a lower aliphatic a, 3- unsaturated monocarboxylic acid of from 3 to 8 carbon atoms, in which the polyoxy-1,2-alkylene glycol is se lected from the group consisting of polyethylene glycols,

pollyl,2-propylene glycols and alkyl ethers thereof having a molecular weight between 106 and 10,000, said (A) and (B) components being present in the ratio of from 50 to 80 mole percent of (A) to 20 to 50 mole percent of (B) and amounting to a total of from 75 to 97 mole percent and the (C) and (D) components represent a total of from 3 to 25 mole percent of the polymer, there being at least one unit of each of said (C) and (D) components in the copolymer, said copolymer having a molecular weight of 'at least 2,000.

2. A lubricant composition comprising a major portion of an oil of lubricating viscosity and from about 1 to 5% by weight of an oil-soluble polymer which comprises (A) tridecyl methacrylate in which the tridecyl group is a primary branched-chain group of 13 carbon atoms, (B) tallow methacrylate, (C) methacrylic acid, and (D) decaethylene glycol tridecyl ether methacrylate, said (A) and (B) components being present in the ratio of from 50 to 80 mole percent of (A) to 20 to 50 mole percent of (B) and amounting to a total of from 80 to 92 mole percent of the polymer, while the (C) component represents 65 to 90 mole percent and the (D) component repreamounts, and which normally contain at least 10% of the polymer, comprise a convenient method for handling the polymer and may be used as a compounding agent for lubricants in general.

While satisfactory lubricant compositions can be obtained by adding to the base oil employed only one or more of the polymeric additives of the type described above, it also falls within the purview of this invention to provide lubricant compositions which contain not only such polymers, but also other additives such as oiliness and extreme pressure agents, antioxidants, corrosion inhibiting agents, blooming agents, thickening agents, and/or compounds for enhancing the temperature-viscosity characteristics of the oil. The present invention also contemplates the addition to the lubricant composition (particularly when the amount of polymer employed is relatively small) of auxiliary detergents and/or antiwear sents 35 to 10 mole percent of the balance of the polymer, said polymer having a molecular weight of at least 2,000.

3. A lubricant composition comprising a major portion of an oil of lubricating viscosity and from about 1 to 5% by weight of an oil-soluble polymer which comprises (A) tridecyl methacrylate in which the tridecyl group is a primary branched-chain group of 13 carbon atoms, (B) stearyl methacrylate, (C) methacrylic acid and (D) decaethylene glycol propyl ether methacrylate, said (A) and (B) components being present in the ratio of from 50 to mole percent of (A) to 20 to 50 mole percent of (B) and amounting to a total of from 80 to 92 mole percent of the polymer, while the (C) component represents 65 to mole percent and the (D) component represents 35 to 10 mole percent of the balance of the polymer, said polymer having a molecular weight of at least 2,000.

4. A lubricant composition comprising a major portion of'an oil of lubricating viscosity and from about 1 to 5% by weight of an oil-soluble polymer which comprises (A) butyl methacrylate, (B) stearyl acrylate, (C) acrylic acid, and (D) methacrylate of lauryl monoether of polyethylene glycol, which glycol has an average molecular weight of about 440, said (A) and (B) components being present in the ratio of from 50 to 80 mole 11 percent of (A) to 20 to 50 mole percent of (B) and amounting to a total of from 80 to 92 mole percent of the polymer, while the (C) component represents 65 to 90 mole percent and the (D) component represents 35 to 10 mole percent of the balance of the polymer, said 6 polymer having a molecular weight of at least 2,000.

References Cited in the file ofthis patent UNITED STATES PATENTS Fenske et al. Sept. 17, 1946 Popkin July 22, 1952 Stuart et a1. June 30, 1959

Claims

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR PORTION OF AN OIL OF LUBRICATING VISCOSITY AND A MINOR PORTION SUFFICIENT TO ENHANCE THE DETERGENT CHARACTERISTICS OF THE COMPOSITION AND DEPRESS THE POUR POINT THEREOF AN SOIL-SOLUBLE POLYMER WHICH COMPRISES (A) AN ALKYL ESTER OF A LOWER ALIPHATIC A,B-UNSATURATED MONOCARBOXYLIC ACID OF FROM 3 TO 8 CARBON ATOMS, SAID ALKYL ESTER BEING CHARACTERIZED BY AN ALKYL GROUP OF FROM 4 TO 30 CARBON ATOMS, (B) AN ALKYL ESTER OF A LOWER ALIPHATIC A,B-UNSATURATED MONOCARBOXYLIC ACID OF FROM 3 TO 8 CARBON ATOMS, SAID ALKYL ESTER BEING CHARACTERIZED BY AN ALKYL GROUP OF FROM 4 TO 30 CARBON ATOMS, WHICH IS FROM 4 TO 16 CARBON ATOMS MORE THAN THE ALKYL GROUP OF SAID (A) ALKYL ESTER, (C) A LOWER ALIPHATIC A,B-UNSATURATED MONOCARBOXYLIC ACID OF FROM 3 TO 8 CARBON ATOMS, AND (D) A MONOESTER OF A POLYOXY-1,2-ALKYLENE GLYCOL AND A LOWER ALIPHATIC A,BUNSATURATED MONOCARBOXYLIC ACID OF FROM 3 TO 8 CARBON ATOMS, IN WHICH THE POLYOXY-1,2-ALKYLENE GLYCOL IS SELECTED FROM THE GROUP CONSISTING OF POLYETHYLENE GLYCOLS, POLY-1,2-PROPYLENE GLYCOLS AND ALKYL ETHERS THEREOF HAVING A MOLECULAR WEIGHT BETWEEN 106 AND 10,000, SAID (A) AND (B) COMPONENTS BEING PRESENT IN THE RATIO OF FROM 50 TO 80 MOLE PERCENT OF (A) TO 20 TO 50 MOLE PERCENT OF (B) AND AMOUNTING TO A TOTAL OF FROM 75 TO 97 MOLE PERCENT AND THE (C) AND (D) COMPONENTS REPRESENT A TOTAL OF FROM 3 TO 25 MOLE PERCENT OF THE POLYMER, THERE BEING AT LEAST ONE UNIT OF EACH OF SAID (C) AND (D) COMPONENTS IN THE COPOLYMER, SAID COPOLYMER HAVING A MOLECULAR WEIGHT OF AT LEAST 2,000.