US2637698A - Mineral oil lubricating composition containing a copolymer of an alkyl ester of itaconic acid and an alkyl acrylate or methacrylate - Google Patents

Description

Patented May 5, 1953 Mm ngln pin QNI N ESTER or 1 W iB T NG i MiQ S T Qfi A QOPOLYMER OF AN ALKYL TACONIC ACID AND AN ALKYL ACRYLATE on METHACRYLATE Thomas Stanford Tiltwilei; Elizabeth, J, as= Signor to Standard Oil Development Gmrlpan y; a corporation of Delaware No Drawing. Application December at,- 1948, Serial No. 68,378

(on sea-56) A 4 Claims: 1

The present ii lviitiolirelates to. ccpelymers of unsaturated clibasic acid esters and their derivatives with acrylic esters and related compounds. The present invention further relates to the use of polymeric materials of this general type as ascitives; for lubricating oils and} analogous compositions, and to the formulation of oil compositions, and the like containing said additives as new products of manufactiire. The invention further relates tothe processes for producing the products of the character referred to above.

It has been fennel, anti is the subject matter of the invention, that alpha-methylene dicarboxylic acid esters readily copolymerize with. alpha,v beta unsaturated mono'carboii-jilic compounds to yield shear stable and thermally stable on soluble products which are particularl valuable as lubricating oil acci'tives as viscosi ty: index im rcv'ers our sepressants, anti the like.

It is wellknown in theprior art that ifiini a l base lubricating oils and, particularly, lubricatin'g' oils such as; those used in" the crank of automotive engines, have: serious limitations with respect to pour point and v ontymemperature relationships unless they are pi pared froiu lly s'elected materials or are iiitiiiifieri to iiii' prove-their viscosity and/or'their pour characteristics-. The present invention has; as a er object; the production of animproved ad matreial for oils whiclr is suitable both for irh proving the viscosity inde x' anal for icweniig the ponr'point.

While reference is made above to lubricants for automotive crank cases, i/fvil-i be understoda that the iriirentron" has application to other type lubricants and is applicable generally to were carbon oil fractions such as hydraulic oils and in some instances to synthetic oils which are employed similarly to naturally occurring miera-l oil's.

An important object of this invention is to produce polymeric materials which are stable at high rates of shear and are stable when em: ployed in. internal combustion engines as a c'bnst-ituent of the lubricating oil; A further'obj ect of this invention-is to produc apolymeric material which is useful for improving'the'visco'si'tytemperature characteristics of oils Without excessi vel'y" increasing the viscosity membrane which may be; used in various hydrocarbon base stock's derived from variousemceoils; s'uc'll as: parar finic; naphthe'nicy asphaltic" or mixed base: A still. further object is" to repare a material-which points or ens u on repeated cycles as temperature change above and below the normal pour points. Many materials which are eiiective pour point depressers in lubricating oils, for example, become unsatisfactory after being subjected to a large number of temperatur changes. This property which is commonly referred to as pour instability is highly objectionable under many conditions where low temperatures are encountered and an object of this invention is to prepare materials and lubricating oils containing suchmaterials which are free from pour instability.

As an important aspect of the present infven' tion, it has been discovered that excellent shear stable and thermally stable polymeric lubricating oil additives may be produced by opolyiiieiizihg alpha-methylene unsaturated dicarboxylic acid esters, wherein the esterifying group contains 6 or less carbon atoms, with compounds having the formula R! Riff mint-t cs" wherein it is hydrogen or ai ialkyl group; R is hydrogen or a halogeir, R is hydrogen; a halogen or an alkyl gran an it? is 1' alkyl; al-i'c'yclic aranryi or alpl yl grasp semia- 'irig abreast 8 carbon atoms; In general, when R anti R" are alkyl, it is prefer that they be relatively small, for exam le; methyl, ethyl; iopyi isopropyl; etc. Among the cont-petites of ty are esters of acrylic acid; methac'rylic acre, alpha-chief" acrylic acid, crotonic' acid, alpha clilor crotonic' acid, beta chlor' crotch-id acre and mixtures thereof. The alpha-methylene dicarboxylic acid esters which are copolymerized with the alpha, betaunsaitura terl compounds have the following general folniuli 2 cl n c-o o o R tooR' aralkyl' or alphyl' group I usuallycontaining no e 131 6 carbon ate" Examples fthese es 1 's pi es'e -at 1east=one- 1011s chain hydrocarbon radical tailfiiiigfrom about 8 to" about 2'4" carbon atoms! Tliese long chains are supplied by the alpha-beta unsaturated compound. The presence of these relatively long chains is of value in providing oil solubility and also for imparting desirable propertie to the copolymer. For the production of pour depressants, it is essential that there be side chains containing 10 or more carbon atoms. These long chains may be supplied by the alcohols which are used to prepare the esters of the alpha-beta unsaturated compounds.

For the production of unusually effective V. I. improvers, it is necessary to have short side chains such as methyl, ethyl, butyl, etc. present in the copolymer in addition to the long side chains necessary to give oil solubility. These short side chains are supplied by the alphamethylene dicarboxylic esters. It has been found that copolymers containing methyl side chains are usually more effective V. I. improvers than similar copolymers containing ethyl, butyl or longer side chains, and that, in general, the V. I. improving potency of similar copolymers decreases as side chain length, as supplied by the alpha-methylene dicarboxylic ester, is increased.

This is illustrated as follows:

3.6 Wt. Percent Copolymer in Oil B l C 1 er ODD ym Viscosity, S. U. S./210 V. 1.

Dimethyl Itaconate, 2% 147 Cs x0 Acrylate, 98% 64 0 Diethyl itaconate, 4% 62' 7 146 62.8 145 Cs 0x0 Acrylatc 63. 4 143 1 Oil B=lubricating oil having 45 S. U. S. viscosity at 210 F. and 115 V. I.

One commercially available alcohol mixture suitable for the preparation of the esters may be obtained from the hydrogenation of coconut oil. Such a product is sold under the trade name Lorol and is a mixture of saturated straight chain alcohols ranging from 10 to 18 carbon atoms and having a major proportion of lauryl alcohol which has 12 carbon atoms. Other related products are made by separating this material, which may be considered as a crude mixture, into several difierent fractions having a relatively higher proportion of the higher, lower, or medium constituent thereof. The composition of Lorol per se and related products, Lorol B and Lorol R, is approximately as follows:

Compositions of Mixtures of Commercial Alcohols Lorol Lorol B Lorol R ercent. 4 3 1 .d0 55. 46 85 "110--.- 22. 5 24 13 .do.- 14 1 d0 4 17 Atoms. 12. 8 13. 5 12. 2

the synthesis of hydrocarbons from carbon monoxide and hydrogen may also be used. Primary aliphatic alcohols are preferred, although secondary alcohols may be employed.

Also, alicyclic alcohols such as cyclohexanol. methylcyclohexanol and hydrogenated alkyl phenols, aralkyl alcohols such as phenylethanol, and alphyl alcohols such as alkylated phenols, cresols, etc., can be employed. The above-mentioned alcohols may contain functional groups such as halogen, NHz, CN, NOz, OR, -O(CH2)n-OR, etc., provided they do not interfere with copolymerization or render the copolymer insoluble. Whereas straight chain and slightly branched aliphatic primary alcohols give excellent results and are therefore preferred, the other types of alcohols and their derivatives mentioned above can be employed for preparing the ester monomers which are copolymerized according to the invention. It will be understood that mixtures of alcohols of the same type or of different types can be employed. In the case of esters prepared from the alpha-methylene dicarboxylic acid, mixed esters such as methyl decyl itaconate can be copolymerized with the alpha, beta-unsaturated monocarboxylic compound with good results.

Half esters of alpha-methylene dicarboxylic acids may also be used in the preparation of copolymers. The resulting products contain free carboxyl groups which may be used as such or which may be neutralized by reacting with an alcohol, a primary or secondary amine or with ammonia or with a metal-containing compound to obtain an esterified, amidized or imidized product or an ammonium or a metallic salt.

Various conditions of copolymerization may be used in this invention involving either bulk or emulsion techniques. In bulk polymerization diluents may or may not be used. Temperatures may vary from 25 C. to 150 C. for periods ranging from 5 minutes to hours and in the presence of various types of catalysts such as benzoyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, and other peroxides, aluminum chloride, boron fluoride, activated clays, ultraviolet light, and the like.

The oil solubility of the finished copolymeric material is governed to a considerable extent by the ratio of the alpha methylene dicarboxylic esters, which supply short side chains to the copolymer, to the alpha, beta unsaturated monocarboxy esters, which supply long side chains to the copolymer, employed in the copolymerization reaction. Examples of approximate maximum ratios giving copolymeric materials soluble in a lubricating oil consisting of 94% solvent extracted Mid-Continent stock and 6% solvent extracted bright stock are as follows:

I II

Acrylate Copolymers of higher ratios of short chain esters to long chain esters may be soluble in other types of lubricating oil stocks.

The average molecular weight of the finished polymeric material should not be less than 1,000 or more than 50,000. The preferred range is 7,000 to 17,000 being especially preferred.

The copolymers which are produced according to this invention not only are-suitable pour depressants and viscosity index improvers but also are rust inhibitors, detergents, and generally improve the condition of the engines in which they are used. These copolymers may also be used in compounding greases, waxes, and the like, and may-also be used in conjunction with other additive materials such as pour de pressants, viscosity index improyers, rust inhibitors, detergents, extreme pressure agents, dyes, and the like.

The invention will better be understood from the specific examples described hereinafter which are illustrative only and are not to be construed as limiting the scope of the applicants invention.

EXAMlE-LE I To g. of dimethyl itaconate were added 180 g. of octyl, decyl methacrylate (a mixture of octyl and decyl methacrylates) and 164 g. of a white oil having a S. U. S. viscosity at 210 F. in a 3-liter stirring flask contained in an oil bath. The mixture was then heated for 48 hours at 70 C. in a nitrogen atmosphere adding 1 gram of benzoyl peroxide at the start and 1 gram of benzoyl peroxide after heating the mixture for 1 hour. A clear homogeneous copolynier was obtained which was blended to 20% com centration in a lubricating oil having a viscosity of 43-44 S. U. S. at 210 F. and this oil concen tration was employed directly as a V. 1. improver.

EXAMPLE II To 100 g. of climethyl itaconate were added 900 g. of octyl, decyl methaerylate and 755 g. of a .1

white oil having 43 S. U. S. viscosity a 210 15k, in a 3-liter stirring flask contained in an oil bath. The mixture was then heated for 27 hours at 70 C. in a nitrogen atmosphere, adding 5 grams of benzoyl peroxide at the start and 5 grams of benzoyl peroxide after heating the mixture for 1 hour. A clear, homogeneous copolymer was obtained which was blended to 4.0% concentration in a mineral lubricating oil having 43 .4 S. U. S. viscosity at 210 F. and this oil concentrate was employed directly as a V. I. improver.

EXAMPLE III To 0.2 grams of dimethyl itaconate were added 9.0 grams of octyl 0x0 acrylate, 10.0. grams of a white oil having a 43 S. U. S. viscosity at 210" F. and 0.10 gram of 100 mesh benzoyl peroxide in a cc. test tube. The tube was flushed with nitrogen, stoppered, agitated to effect complete solution, then heated for 30 hours at 70 C. in an oil bath, A clear, homogeneous copolymer was obtained which was blended to 20% com centration in a lubricating oil. having a viscosity of l3a44 S. U. S. at 210 F. and this oil com centration was employed directly as a viscosity index improver. The octyl alcohol from which the acrylate was prepared was made by the 0x0 reaction in the presence of a cobalt catalyst of CO, hydrogen and a C7 olefin fraction, obtained from the polymerization of C3-C4 refinery gases in the presence of phosphoric acid catalyst, forming octyl aldehyde which was then hydrogenated to the alcohol.

EXAMPLE W copolymer of 1.7 g. of dimethyl itaconate with 9.3 g. of decyl. acrylate was prepared in a similar manner to Example III, employing 9.0 g. of white oil diluent and 0.11 g. of mesh benzoyl peroxide.

EXAMPLE V A copolymer of 2.0 g. of dimethyl itaconate with 8.0 g. of lauryl acrylate was prepared, in' a similar manner to Example III, employing 7.0 g. of white oil diluentand 0.10 got 100 mesh benzoyl peroxide.

EXAMPLE VI A copolymer of 3.2 g. of dirnethyl itaconate with 12.8 g. of Lord R aeryl-ate was prepared in a similar manner to Example III, employing 11.1 g. of white oil diluent and 0.16 g. of 100 mesh benzoyl peroxide. This copolymer was also useful as a pour depressant.

EXAMPLE VII A copolymer of 0.4 g. of diethyl itaconate with 9.6 g. of octyl 0 x0 acrylate was prepared in a similar manner to Example III, employing 10.0 g. of white oil diluent and 0.10 g. of 100 mesh benzoyl peroxide.

EXAMPLE VIII S. U. S. 3.6 Wt. Percent Via/210 F., Copolymer in Oil B C 20 Wt.

opolym'er Percent Copolymer S. U. S. V I

in Oil A Via/210 F.

Dimethyl Itaconate, 10% Octyl, dccyl Methacrylate, 90%.-. 323 61. 4 14 7 Example I Dimethyl Itaconate, 10%., Octyl, decyl Methacrylate, 90%." 352 62. 3 149 Example II Dimethyl Itaconate, 2% Octyl 0x0 Acrylate, 98% 433 64. 0' 147 Example 111 Dimethyl itaconate, 15% Deeyl Acrylate, 85% 660 74.1 154 Example IV Dimethyl Itaconate, 20% Lauryl Acrylate, 80% 601 68.1 152 Exam e V Dimethyl Itaeonate, 20%.., Loro'l R acrylate, 80% 401 63. 8 150 Example VI Diethyl Itaconate, 4%. Octyl 0x0 Aerylate, 96% 373 62. 7 146 Example VII Dibutyl Itaconate, 5%

362 63.4. 1.43 566 '71. 7 1&7 335 66.1 141 6 72- .14

Oil Aso1vent extracted lubricating oil having 43-44 S. U. S. vis. at 210 F., 112 V. I.

Oil B-solvent extracted lubricating oil having 45 S. U. S. vis. at 210 F., 115 V. I.

The following table illustrates the pour depressing properties of copolymers prepared according to this invention.

Oil C-conventinally refined Pennsylvania 180 Neutral.

Oil Dso1vcnt extracted Mid-Continent +Bright Stock-S. A. E. 10 grade.

The following tables illustrate the superior polymer stability characteristics of copolymers prepared according to the present invention as compared to the stability characteristics of other type methacrylate-itaconate ester copolymers and 'sentially of a major proportion of a mineral oil base stock and a small but viscosity index improving amount of a copolymer of dimethyl itaconate and a compound having the formula wherein R is selected from the class consisting of hydrogen and a methyl group and R is selected 10 from the class consisting of the alkyl group containing from 8 to 24 carbon atoms.

3. A lubricating oil composition consisting essentially of a major proportion of a mineral oil base stock and a small but viscosity index improving amount of a copolymer of dimethyl itaconate and mixtures of octyl and decyl methacrylate.

4. A lubricating oil composition consisting essentially of a major proportion of a mineral oil a current commercial V. I. improver in both base stock and a small but viscosity index imlaboratory tests and automotive enging tests.

proving amount of a copolymer of 1 mol of di- Polymer breakdown characteristics [McIntype pump testJ] Used Oil 4 Hr. New 011 Sample Vis. 20% Copolymer 3 5 2 Wt LPercent perass, is. 011 A cent Visi, 210 V. I. L asslin F" Copol. Based on Polymer Dimethyl Itaeonate, 10% Octyl, decyl Methacrylate, 90%. 323 2. 75 75. 8 122 2. 0 16 D 17? t 8 7 ecy acona e, 0 Methyl Methacrymtg 20% h 356 3.40 76.1 134 7.0 39 Commercial V. I. Improver X 651 2. 05 77.0 123 4.8 31

1 Oopolymer oil blend circulated through McIntyre gear pump at 200 F. and 1000 p. s. i. g.

Polymer breakdown characteristics [32 hr. Chevrolet engine test] What is claimed is: 1. A lubricating oil composition consisting essentially of a. major proportion of a mineral oil base stock and a small but viscosity index improving amount of a copolymer of an alkyl ester of itaconio acid wherein the esterifying group .contains from 1 to 4 carbon atoms and a compound having the formula wherein R is selected from the class consisting of hydrogen and a methyl group and R is selected from the class consisting of the alkyl group containing from 8 to 24 carbon atoms.

2. A lubricating oil composition consisting csmethyl itaconate and 0.1 to 2.0 mols of mixtures of octyl and decyl methacrylate.

THOMAS STANFORD TUTWILER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,020,714 Wulff Nov. 12, 1935 2,091,627 Bruson Aug. 31, 1937 2,220,855 Slagh Nov. 5, 1940 2,279,881 DAlelio Apr. 14, 1942 2,279,883 DAlelio Apr. 14, 1942 2,366,517 Gleason Jan. 2, 1945 2,375,516 Blair May 8, 1945 2,422,881 Blair June 24, 1947

Claims (1)

1. A LUBRICATING OIL COMPOSITION CONSISTING ESSENTIALLY OF A MAJOR PROPORTION OF A MINERAL OIL BASE STOCK AND A SMALL BUT VISCOSITY INDEX IMPROVING AMOUNT OF A COPOLYMER OF AN ALKYL ESTER OF ITACONIC ACID WHEREIN THE ESTERIFYING GROUP CONTAINS FROM 1 TO 4 CARBON ATOMS AND A COMPOUND HAVING THE FORMULA