Patented. Nov.v 19, 1946 , 2,411,150 UNITED STATES PATENT OFFlCE 2,411,150 011. BLEND » t Hector 0. Evans, Cranford, and David W. Young, Roselle, N. 1., assignors to Standard Oil De velopment Company, a corporation of Delaware I No Drawing. Application September 20, 1941, Serial No. 411,652 _ 12 Claims. 1 (CL 252-56) 2 This invention relates to hydrocarbon oil blends ‘ with a combination of additives for more effec ,Notable examples of satisfactory V. I. improv ing thickeners are the highly saturated aliphatic hydrocarbon polymers typi?ed by the polybu tively improving viscosity-temperature relation‘ shlps of the blends with restricted thickening. A major requirement of motor lubricating oils and other industrial petroleum oil products is a tenes, which are derived by low temperature cat alytic polymerization of pure isobutene or isobu 0 ' tene in mixtures with other ole?ns. ‘Methods for - satisfactory viscosity-temperature characteristic, i. e., as little variation of viscosity over a wide the preparation of these polymers are described in the prior art. Other analogous aliphatic hy drocarbon V. I. improvers include hydrogenated temperature range as possible. Petroleum lubri eating oils with high viscosities at low tempera ’ 10 tures have poor ?ow characteristics in a cold engine, while with proper low viscosities at low temperatures, many of them lack su?icient vis cosity at operating temperatures for proper lubri cation. Although, certain thickening agents are capable of giving these oils more satisfactory vis 'diolefin polymers and copolymers of ole?ns with diole?ns. . In addition to the aliphatic hydrocarbon poly mer V. I. improvers, there have been developed aliphatic-aromatic types of polymers, represented by condensation polymers of alkyl halides with aromatic hydrocarbons, e. g. chlorinated wax with ' cosity-temperature characteristics, in serving this purpose, they thicken the oils to unduly high naphthalene, also, various oxygen-containing condensation polymers represented‘by polymer viscosities, which increase power consumption ized acrylates, e. g., polymerized laurylmethac and make the oils un?t for low temperature use. 20 rylate, polymerized vinyl esters, and the like. Accordingly, it is desirable to improve many pe In accordance with the present invention, the troleum oil products by lowering the rate of change of viscosity with temperature With pref erably, a reduction in viscosity, or at least, only a small change in viscosity, at low temperatures. In evaluating lubricating oils on their ability to maintain a more uniform viscosity with change in temperature, the well known viscosity index V. I. improving e?’ectiveness of the thickening polymers is greatly improved with ,a bene?cial restriction ins-thickening of the oil blend by an added blending agent which is substantially im- , miscible with the thickening additive at tempera tures below about 100° F., but whch, nevertheless, in ' suitable proportions forms a homogeneous classi?cation of Dean and Davis is widely used blend with the thickened oil and substantially by the oil industry. This classi?cation compara 30 lowers the viscosity of the blend at these tem tively rates the oils by their relative variations peratures. The agents which act in this ca inviscosities accurately determined at the tem pacity will‘be referred to as non~solvent modi perature limits of 100° F. and 210° F. in Saybolt ?ers of the thickening V. I. improvers. . Universal seconds (S. S. U.). Using this method Another desirable property of the modifying of classifying and rating lubricating oils, the best agents used for controlling the thickening action petroleum lubricating oils economically obtain of the thickening V. I. improvers in a lubricating able by re?ning of crude petroleum oils have a oil is asuitably high ?ash point and low vola viscosity index (V. I.) of the order of 100. . But, tility to avoid impairment in the ?ash point value at the same time, the lubricating oils must meet of the petroleum on base and avoid, loss by va grade requirements with respect to viscosity 40 ranges determined, for example, by S. A. E. num From a study of a large number of compounds bers which indicate whether the oil is too heavy, for their e?‘ects on the thickening of oil blends, porization. too light, or suitable for a certain use. _ , ’ . - it ‘was noted‘ that modi?ers oi’ the thickeners ’ A variety of thickening V. I. improvers have which behave satisfactorily in desired low con been developed. These have been characterized 45 centrations for the present purposes, in general, , largely by linear chain or two dimensional poly are polar organic compounds having dielectric meric compounds having molecular weights above constants substantially higher than those of the 800, derived mainly by simple polymerization, thickeners and hydrocarbon oils, e. g., substan condensation, or copolymerization of low molecu tially above 4 at 20° C. Although, such polar _ lar weight monomeric reactants. In order to be 50 . useful as V. Limprovers, .these synthetic poly meric compounds must meet with certain re quirements of oil solubility, e?ectiveness-in low concentrations, and stability under operating conditions to which the oil blends are subjected. compounds are non-solvents forthe, thickening polymers at 0° F. to 100° F., they tend to have solvency for the polymers at above 100° F. in a hydrocarbon oil. . A test procedure which may be used to pre determine whether a polar organic compound 2,411,1oo (1 I ' 3 ‘has adequate non-solvent action on the polymer polymer in a clear, colorless,‘ light hydrocarbon 4 . and for the sake of economy,;_-in as small a pro solvent, such as naphtha, or kerosene, e. g., 10% * portion ‘as possible, e. g., about 4:to 20%. The by weight of the polymer in~25 cc. of the liquid ’ I effects of various thickening and modifying blend ing agents in the'oil blends will be apparent from . to the resulting solution, the ‘polar organic com- v pound to be tested. If the polar organic com ‘ solvent modi?er is preferably used in a propor tion less than 50% by weight of the total blend, . consists simply in dissolving a quantityv of the solvent, then adding slowly, with slight agitation, I- ‘type as the V. I. improving thickener, the non ' the twt results reproduced hereinafter. One procedure used in formulating blendsv of the thickeners with petroleum oils and the added non-solvent modi?er to control the action of the polymer wasto blend the non-solvent modi?er pound added in an-amount of about 5 to 75 cc. causes precipitation of the polymer from the solution, observed by the formation of turbidity, or separation of the polymer, then the polar . with-a petroleum base oil together with a small» ‘ proportion of more viscous voil until-the viscosity polar compounds having lowest miscibility with 15 of this blend corresponds closely to the original viscosity of the base oil at 210° ,F.-for reference _ the polymer prove to be the most effective modi organic compound is indicated to have the de sired non-solvent property.» However, while the purposes, after which the thickening V. I. im ?ers, it is also important that effective amounts of'such polar compounds be capable of being blended with or homogeneously dispersed in the thickened oils ‘containing the polymer. . prover was added to the oil blend, slightly warmed‘ - and with agitation. The viscosities of the result 20 ing blends were then determined accurately at 100° F. and 210° F. in order to observe the effects ' Among polar organic compounds tested va’nd found to give favorable results in restricting the of the, non-solvent modi?er. - . thickening .action'of polybutene and increasing _ the V. I. improving effectiveness of v this polymer The amount of the thickening v. I.‘ improver added to. the oil in the blends was completely in hydrocarbon oil blends are high boiling- oiry-' 2.5‘ ‘soluble in the. hydrocarbon oil and was com estersQsuch' as dibutoxy‘ ethyl phthalate, 'butyir aeetyl ricinoleate,' and triethylene glycol di-2 ethyl butyrate. The potency of these compounds pletely ‘soluble in' the blends with the non-solvent ' modi?ers usedin proper proportions, so that the heating and agitation of the blend is simply to for controlling the thickening effect of the poly- ' ~ facilitate solution. The procedure of the blend ing may’. be varied as desired. The non-solvent mer with added V. I. improvement depends upon modi?er for the thickening V. I. improver may _ a number of factors, hence allgpolar organic .com-. pounds, including those represented by high boil v“be added subsequent to the'thickening of the ing oxygen-containing compounds; do not give? Y‘ hydrocarbon oil, simultaneously with the thick-' ' ' exactly the same effects. For example, altho'uglr' - ener, and in practice be used without the added castor oil is a non-solvent for the hydrocarbon 85. small proportion of more viscous hydrocarbon polymer at ordinary temperatures, it was found _ oil. _ _ . Ekauru: ineffective by itself, ‘because it. could not be homogeneously blended with-the thickened oil. However, castor oilcould be used together with a _'In a speci?c scienti?c investigation of- howa more oil-solublemodi?er. ‘e. 8-. dibutoxy ethyl 40 satisfactory non-solvent for the thickener acts, phthalate. Lower alkyl phthalate esters, such as usewas made of the Staudinger method for de methyl and ethyl phthalates, behave somewhat. like castor oil. Thus, it is important to use a non-solvent modi?er which blends homogeneously . termining viscosity characteristics of thethicken ing polymer, as explained in Staudinger's articles, > Trans. Faraday, Soc. 29, 30, (1933). It was ob with the thickened oil despite its non-solvency 45 served that a non-solvent modi?er for the thick ' for'the thickener at ordinary temperatures. ening polymer tends to reduce the specific vis The hydrocarbon oils to be used in the oil " cosity of the polymer at lower temperatures, beblends may be of any preferred type, such-as low about 100° F., with less reduction or even those ‘derived from the" ordinary paraf?nic, ‘ some increase at higher temperatures, thereby de ' naphthenic', asphalticp or mixedv base crude 50 creases the di?'erential of the speci?c viscositiesv petroleum stocks by suitable re?ning practices, with respectgto increase in temperature, and thus or by synthesis. The hydrocarbon oil component makes the desired modi?cation in the thickening is. not limited to any speci?c viscosity or boiling action of the polymers. ,This effect is illustrated range, other than by the. speci?cations for the by the following data, in which ‘Nap denotes the 'purpose they are to be employed. ‘Inmaking 55 speci?c viscosity (ratio of viscosity coemcient of improved industrial oils, the hydrocarbon oil may thickened‘oil to that of the oil minus 1) and C. have to- meet certain high flash‘ point and denotes the concentration of the polymers hav volatility requirements; in making lubricating ing varying molecular weights which were tested oils, the hydrocarbon oil component should be in samples of thesame petroleum lubricating oil. substantially non-volatile and meet minimum 00 ' ?ash point requirements. The particular type of thickening V. I. improver to be used ‘may vary with the type of hydro carbon oil and the purpose of the blend. 'This TABLE 1. Viscosity characteristics of p'olybu'tenes in hydro- ‘ carbon oil blends ' component may amount to- about 1% to 15%. or higher, by weight of the ?nished blend,'but is 65, generally used in motor oils in a proportion of about 1% to 5% by weight. The nature and quantity of the thickener modifying agent also depends upon the particular 70 hydrocarbon oils, the particular V.‘ I. improving Differential , Approx. M. W. - of polybutene of speci?c 20° C 415"v C. 05° C. _ viscosities NIP/C Nm/C N,,/G unit change ~ ' - 1n N.,/C 20° ' to 65°C. thickening agent, and the proportions of these " components in the finished blend. '" With ‘common types of petroleum lubricating oils and preferred 1 aliphatic hydrocarbon polymers of the polybutene 75 20,000 .............. -- 0. 24 45,000 .............. __ ,000_._............ -- 0- 28 0.42 ' 0. 20 0. 15 0. 09' 0.24 0. 35 . 0.18 a 0.26 0.10 0. 16 2,411,150 Tan: 2 I Turin 5 Viscosity character-mites o! polybutenes in hydro- carbon oil blends ‘with 10% non-solvent (di s. s. U. Wis. at bntomy ethyl phthalote) i i v. I_ 100° F. 210° F. Di?erential Approx. M. W. of polybutene , 20° C. 45° C. N.,/C N-p/C 65° C. of specific Hydrocarbon reference 011 __________________ __ unit change Blends with thickener and modi?er med visoosities Nip/C in Nw/C 20 to 65°C. 10 . ' . . "parade 93. 8 37.‘. 32: . dibutoxy ethyl hthalate '27 ‘as s s U . it 210° F. 01])-..5 ______ __ (+ _.° 0. 19 0. 23‘ 0- 40 0. 18 0. 22 0. 36 0. 16 0. 20 0. 33 0.03 0. 03 0. 07 140- 9 Blend with thickener and modi?er used 15' To illustrate how the non-solvent modi?er acts ’ as 5% thickener _____________ -_ ’ ‘ together 5% thickener +995 dibutoxy ethyl phtha late (+270 65 s. s. U. at 210° F. oil) ______ __ 211.1 to bene?cially decrease thickening and at the same time improve viscosity-temperature char ‘8. 9 “' 52.90 143.0 - Effects of dibutoxy ethyl phthalatewith a poly acteristics of the polymer‘ thickened oil on the acrylate thickener is shown in the‘ following V. I. scale,_the following data are presented: 20 data: 7 , ' . T2311: 6‘ TABLE 3 s. s. U. vis. at“ S. S. U. vis. v. I. at 25 V. I ‘ 100° F. 210“ F. 100° F. 210° F. Hydrocarbon reference oil __________________ __ 92. 40 Hydrocarbon reference 011 (S. A. E. 10W)____ 93.8 37. 32 8. 9 . Blend with polyacrylote thickener alone v ‘Blends with thickener and modi?er used 30 separately 36% dibutoxy ethyl phthslate (+21% oil of I ' 37. 22 3% polyacrylnte unmodi?ed, _______________ __ 140.5 44.69 Blend with thickener and polymer used‘toyether 65 S. S. U. at 210° F. ____________________ __ 89. 64 36.74 9.7 ‘2% polybntene 13,000 M. W ................ ._ 227. 7 51.63 1.28. 0 9. 8 __ 137.5 ' 3% polymer+40% dibutoxy ethyl phthalate__ 136. l 44. 56 ‘141.4 Triethylene glycol d1-2-ethyl butyrate is a .35 non-solvent modi?er having somewhat greater 2% polybutene +36% dibutoxy ethyl phtha potency than the dibutoxy' ethyl phthalate, as late (+4% oil of 05 S. S. U. at 210° F.) .... __ 121. 5 46.04 171.7 shown in the following data on its use with poly butene type and polyacrylate type‘ thickeners. The data in Table 3 illustrate how the modi TABLE '7 Blends with thickener and modi?er used together ?er itself has little effect on the V. I. of a base 40 oil, but when used in conjunction with the thick- . ening V. I. improver,v considerably increases in V. I. and bene?cially lowers the thickening at the E?‘ect of triethylene glycol di-Z-ethyl butyrate as non-solvent modi?er on polybutene thick ened‘oil lower temperature level (100° F.), so that the re sulting blend ‘is more useful as a lighter grade, S. S. U. vis. at— ’ ' I V. I lower power-consuming lubricating oil of highly improved V. I. value. Pronounced bene?cial ef 100° F. 210° F. fects were obtained with a high V. I. petroleum lubricating oil base, as shown in the following data: Hydrocarbon reference oil (S. A. E. l‘0W),__. i078 50 . 38. 2 25 Blend with polybutene thickener unmodi?ed I TABLE 4 2% polybutene ...... ____ ____ ._- ________ .. 222.2 50.63 2‘7 polybutene+6.4% modi?er ______________ _. 194.2 2 a polybutene+12.8% modi?en. _,._ 184.4 2% polybutene+32% modi?er ______________ ._ 147.1 48. 56 48.27 ‘46.49 . 1,24 Blenda with polybutene thickener and modi?er 5. 5.11m. at v.1 127 132 147 100° F. 210° F. ’ TABLE 8 Hydrocarbon reference oil __________________ _. 239.2 49.20 102.1 lends with thickener and modi?er used 60 separately 187 dibntoxy ethyl phthalate (+27 65 s‘.’ s. U. 8t210°F. oil) _________ -v ____ E?ect of methylene glycol di-Z-ethyl butyrate as non-solvent modi?er‘on polyacrylate thick ened oil 92.32 38.10 0.6% polybutene ____________________________ _- 316.5 54.76 ‘ 65.8 _ . l 107.4 S. S. U. vis. at V. I. Blend with thickener and modi?er used together 65 100° F. 210° F. 0.07 polybutene +187 dibutoxy ethyl phtha late (+27. 65 s. s. ii. at 210° F. oil) ______ -_ 273.3 53.25 116.4 Hydrocarbon reference oil .................. __ 54. 3 33. 80 ‘70 Blends with polyocrylote thickener and modi?er The following data illustrate how the non-sol vent modi?er, dibutoxy ethyl‘ phthalate, acts in 70 ‘used separately 10% modi?er .... _________________ _- 54. as as. n 70 3% polyacrylate thickener __________ _- 69. 9 37. 25 144. 8 66. 97 37. 09 152.8 smaller concentrations on hydrocarbon oils thick Blend with thickener and modi?er used together ened by aliphatic-aromatic hydrocarbon V. I. im proving polymers formed by condensation of 3% polyacrylate+l0% modi?er _____________ __ highly chlorinated wax with naphthalene. 75 _ . 7 2,411,150 > - ‘Tara: 9. Additional speci?c types of compounds found to actas eifectively non-solvent modi?ers ior ob taining blends of improved V. I. with lower vis cosity at temperatures below about 100° F. in 5 clear, thickened hydrocarbon oil blends are rep resented by: \ v- Compositionolblsuda' ' 317- ' _ , v.1. 100' r. no‘, r. r_. Y . 011+5' dibutoxy ethyl phthalate ........... -_ 1. cs5 - 50.1 91s‘ 0il+4 ,, polybutene (13,000 M. W.) ......... __ 2,061 ' Butyl-acctyl ricinoleate on+4% polybutene (13,000 M. woe-5% di- 10 ' Diethylene glycol '(mono) laurate Glyceryl oleate s. an. via butoxy ethyl phthalats ___________________ __ 1 500 99.03 The modi?ed thickenedpil blends, prepared in ' accordance with this invention, may contain two Diglycol oieate Butoxy ethyl stearate > or more di?erent types of thickeners and two or ' ' .15 more different types of modi?ers. They may also contain small amounts of other kinds of oil ad ditives used for stabilizing, dyeing, inhibiting oxidation, imparting oiliness, lowering the pour Methoxy ethyl oleate Buty-l stearate Tributyl ‘acoanitate point, etc. ’ r The present invention has been illustrated by numerous~examples but is not intended to be 20 The number and‘ variety of effective modi?ers ‘limited thereby, nor is it intended to be limited ' is much larger than shown by the illustrative by any theory ‘on the mechanism by which the improvement is obtained, nor to any particular kind of hydrocarbon oil, polymer, modi?er, or blend. Any modi?cation which comes within the speci?c examples, and can be further extended by the use of the guiding explanations given. _ Some of the modi?ers are more effective than others on account of their greater non-solvent spirit of the invention is ‘intended to'be‘ included ’ action on the thickeners.' It. is apparent that a. within the scope thereof number of the preferred modi?ers for use in in: claims. , as de?ned inthe follow ' lubricating oils'are high boiling oxy-esters, i. e. 30 We claim: ' > ' 1. A lubricating oil comprising a hydrocarbon hydroxy or alkoxy esters. Some of the modi?ers lubricating oil blended withv about 1% to 5% by are more eiiective with one kind of thickener than another. For example; methoxy eth'ylole weight of a polybutene viscosity index‘improving atev appears to be more eifective than triethylene thickener and homogeneously blended with about ' glycol vdi-2-ethy1 butyrate with a polyacrylate 35 4 to 50% by weight of a substantially non-vola-_ tile oxy-ester which is a non-solvent for said poly The non-solvent modi?ers may be only par butene at temperatures below 100° F. as shown by tially miscible with the hydrocarbon’ oils, which its ability'to precipitate polybutene from a 10% occurs often in the case of highly potent modi solution thereof in alight hydrocarbon solvent ?ers. Those having too low solubility in'the hy 40 when added at room temperature in amounts of thickener. ' i > drocarbon oil for making a homogeneous blend may be used bene?cially together with a more from about 20 to 300% based on said solution, said oxy-ester being homogeneously dissolved in the thickened blend to substantially reduce the oil-soluble modi?er. The use of castor oil as a non-solvent modi?er illustrates the importance of homogeneously blending the modi?er with the thickened oil to as a viscosity thereof at 100° F. and increase the vis : cosity indexpf the thickened oil blend. l secure a further improvement in V. I. and at the 2. A lubricating oil composition in accordance with claim 1, in which said ester, is a high boiling same time restrict thickening. Castoroil is found aliphatic alkoxy ester. ‘ ~ to restrict thickening‘ to some extent in low con . ' ~_ 3. _A lubricating. oil composition in accordance centrations with a polybutene thickened 102 V. I. 50 with claim 1, in-which ‘said ester is a high boiling oil, but it also lowered the V. I. and made the solu tion cloudy. When the castor oil was jointly used in small concentrations with a more oil-soluble modifier, dibutoxy ethyl phthalate, in the poly aliphatic hydroxy ester. - - ‘ 4. A hydrocarbon oil blend containing a minor proportion of an oil-soluble acrylate polymer thickener lowering the rate of change of viscosity butene'thickened oil, the blend was clear, the 55 with the temperature of the oil and a su?lcient . thickening was reduced, and the V. VI. of the amount of a substantially now-volatile oxy-ester ' thickened oil was increased considerably, from which is a non-solvent at ordinary temperatures 124.4 to 157.0. ' ' . . for said polymer as shown by its ability to pre Hydrogenated castor oil, _ considered . to have cipitate said polymers from a 10% solution there more oil solubility than castor oil, also increased the thickening action of the polymer and adverse ‘ ly a?ected the viscosity index of the oil when‘ of in a light hydrocarbon solvent when added at Y room temperatures in amounts of from about 20 to 300% based on said solution, said oxy-ester used alone as a modi?er, and further demon being homogeneously dissolved in the blend to‘ strated the need of having the modi?er homo substantially reduce thickening by the polymer 65 at a temperature below about 100° F. and ‘give the geneously blended with the'thickened oil. Another extension in the utilization of the oil alower rate or change of viscosity with tem present invention is illustratedby the effects of perature. ‘ the vmodi?ers on thickeners in hydrocarbon oils .5. A hydrocarbon oil blend containing a minor‘ having extremely low V. I. values. ~For example, proportion oi’ a synthetic aliphatic-aromatic con using a low‘ V. I. phenol extract or a naphthenic 70 densation polymer which lowers the rate of lubricating oil, a study was 'made or how a non solvent modi?er ailfected the oil and its thickened blends. The following data illustrate how- a mod? ‘ i?er Jointly with the thickener tremendously im proved the VV. 1. with restricted thickening. change of viscosity with the temperature 0! the oil and a suf?cient amount of a substantially non- - _' volatile oily-ester which is a nongsolvent at or- ‘ dinary temperatures for said polymer as shown 75 by its ability to precipitate said polymers from 2,411,150 9 10. a 10% solution thereof in a light hydrocarbon solvent when added at room temperatures in amounts of from about 20 to 300% based. on said ' sisting of polybutenes, hydrogenated diol‘e?n polymers, condensation polymers of alkyl halides with aromatic hydrocarbons and polymerized solution, said oxy-ester. being homogeneously dis vinyl esters and with a substantially non-volatile ' oxy-ester which is a non-solvent for said thick solved in the blend to substantially reduce thick ening by said polymer at temperatures below ening polymeric compounds at ordinary tem peratures as shown by its ability to precipitate of change of viscosity with temperature. said polymers from a 10% solution of the poly 6. A lubricating oil blend comprising a hydro; mer in a light hydrocarbon solvent when added carbon lubricating oil blended with about 1% to‘ 10 at about room temperature in amounts of from 5% by weight of a viscosity index improving ‘ about 20 to 300% based on said solution, said thickener and a su?icient amount of triethylene oxy-ester being homogeneously dissolved in said glycol di-2-ethyl butyrate blended with the thus blend in an amount su?icient to lower the rate thickened oil to substantially reduced the vis of change of viscosity with temperature of said cosity and raise the viscosity index of the thick 15 blend from the rate of change of viscosity with ened oil blend, said thickener being normally temperature of a blend consisting of the lubricat about 100° F. and give the oil blend a lower rate immiscible with triethylene " glycol di-Z-ethyl butyrate. ' ing oil and polymer. - ' ‘ ' > 11. A hydrocarbon oil blend comprising a h - 7. An oil blend comprising a hydrocarbon lu , drocarbon lubricating oil blended with about 1 bricating oil thickened by about 1 to 15% by 20 to 15% by weight of a soluble thickening poly- ' weight of a viscosity index improving thickener meric compound selected from the‘ group consist and blended with a minor proportion of dibutoxy ing of polybutenes, hydrogenated diole?n poly ethyl phthalate, said thickener being normally , vmers, condensation polymers of alkyl halides with immiscible with dibutoxy ethyl phthalate. I 8. An oil blend comprising a hydrocarbon lu bricating oil thickened by about 1 to 15% by weight of ‘a viscosity index improving ‘thickener aromatic ‘hydrocarbons and polymerized vinyl 25 esters and with about 4 to 50% by weight of a substantially non-volatile oxy-ester which is a non-solvent for'said thickening polymeric com pounds at ordinary temperatures as showngby its ability to precipitate said polymers from a, 10% solution of the polymer in a light hydrocarbon and blended with a minor proportion” of butyl acetyl ricinoleate, said thickener being normally immiscible with butyl acetyl ricinoleate. 9. A hydrocarbon oil blend comprising a hydro carbon lubricating oillblendedwith a minor pro- " portion of a soluble thickening polymeric com pound selected from the group consisting of poly“ butenes, hydrogenated diole?n polymers, conden solvent when added at about room temperature in amounts of from about 20 to 300% based on said solution, said oxy-ester being homogeneous- ' 1y dissolved in said blend and imparting to' the 35 blend 3. lower rate of change of viscosity'with , _ sation polymers of 7 alkyl halides with aromatic temperature than is possessed by a blend con hydrocarbons and polymerized vinyl esters and‘ sisting of the lubricating oil and polymer. with a substantially non-volatile oxy-ester which -is a non-solvent for said thickening polymeric 12; A hydrocarbon oil blend comprising a hy drdcarbon lubricating oil blended with about 1 ~ compounds at ordinary temperatures as shown by 40 to 15% by weight .01 a polybutene/viscosity im~ ‘ its ability‘to precipitate said polymers from ‘a proving thickener and with a. substantially non z 10% solution of the polymer in a light hydro-. volatile oxy-ester which is a non-solvent for said carbon solvent when added at about room tem ‘ polybutene at ordinary temperature'as shown by l perature in amounts of from about 20 to 300% based on said solution, said oxy-ester being homogeneously dissolved in said 'blend in an amount sufficient to lower therate of change ‘of viscosity with temperature of said blend from the rate of change of viscosity with temperature of a blend consisting of the lubricating oil and 50 polymer. ' ' 10.‘A hydrocarbon oil blend comprising a hy drocarbon lubricating oil blended with about 1 to 15% by weight of a‘soluble thickening poly meric compound selected from the group con its ability to precipitate polybutene from a 10% solution thereof in a light hydrocarbon solvent when added at about room temperature in amounts of from about 20 to 300%,based on said solution, said oxy-ester being homogeneously dis solved in said blend in an amount sumcient to lower the rate of change of viscosity with tem perature of said blend from the rate of change of viscosity with temperature of a blend consisting of the lubricating oil and apolybutene. , HECTOR C. EVANS. 55 vDAVID W. YOUNG. .