US3808134A

US3808134A - Synthetic hydrocarbon lubricant compositions

Info

Publication number: US3808134A
Application number: US00280059A
Authority: US
Inventors: H Romine
Original assignee: Continental Oil Co
Current assignee: ConocoPhillips Co
Priority date: 1972-08-09
Filing date: 1972-08-09
Publication date: 1974-04-30
Anticipated expiration: 1991-04-30
Also published as: CA1006152A; SU644393A3

Abstract

COMPOSITIONS COMPRISING MIXTURES OF DI-N-ALKARYLS (E.G., DI-N-AKYLBENZENES) AND LINEAR MONO-OLEFIN OLIGOMERS HAVE CERTAIN IMPROVED PROPERTIES OVER THAT OF EITHER ALONE FOR EXAMPLE, MIXTURES OF THE TWO MATERIALS HAVE A LOWER --40*F. VISCOSITY, AS COMPARED TO THE INTERPOLATED VISCOSITY, THAN EITHER MATERIAL ALONE. ALSO MIXTURES OF THE TWO MATERIALS ARE MORE COMPATIBLE TO ADDITIVE COMBINATIONS THAN THE LINEAR MONO-OLEFIN OLIGOMER ALONE. STILL FURTHER, COMPOSITIONS COMPRISING THE MIXTURES AND VARIOUS ADDITIVE COMBINATIONS HAVE IMPROVED VISCOSITY INDEXES AS COMPARED TO EITHER MATERIAL CONTAINING THE ADDITIVE PACKAGE.

Description

United States Patent O 3,808,134 SYNTHETIC HYDROCARBON LUBRICANT COMPOSITIONS Hugh Ernest Romine, Ponca City, Okla., assignor to Continental Oil Company, Ponca City, Okla. No Drawing. Filed Aug. 9, 1972, Ser. No. 280,059 Int. Cl. Cm 1/28 US. Cl. 252-59 11 Claims ABSTRACT OF THE DISCLOSURE Compositions comprising mixtures of di-n-alkaryls (e.g., di-n-alkylbenzenes) and linear mono-olefin oligomers have certain improved properties over that of either alone. For example, mixtures of the two materials have a lower -40 F. viscosity, as compared to the interpolated viscosity, than either material alone. Also, mixtures of the two materials are more compatible to additive combinations than the linear mono-olefin oligomer alone. Still further, compositions comprising the mixtures and various additive combinations have improved viscosity indexes as compared to either material containing the additive package.

BACKGROUND OF THE INVENTION Field of the invention This invention is directed to lubricating fluids suitable for use under extremely low temperature (i.e., 40 to 75 F.) conditions. The invention is directed specifically to synthetic hydrocarbon compositions, and to mixtures of such compositions, having the requisite physical properties for such use.

GENERAL BACKGROUND It is known that certain dialkylbenzenes (e.g., those having C -C alkyl groups) have physical properties which render them useful as low temperature lubricants. For example, US. Pat. No. 3,173,965 contains such teachings. It is also known that synthetic hydrocarbon lubricants which contain a major amount of di-n-alkylbenzenes, or di-n-long-chain alkaryls, and a minor amount of other hydrocarbon (e.g., diphenylalkanes or trialkyl substituted tetrahydronaphthalenes) have properties which render them useful as low temperature lubricants. US. Pat. Nos. 3,288,716; 3,588,739; and 3,662,012 contain such teachings.

The use of linear mono-olefin oligomers as lubricants is also well known. While these materials have outstanding physical properties (e.g., viscosity index and pour point) they are deficient in oxidation stability and compatibility with various conventional lubricating oil additives.

I have discovered that mixtures of di-n-long-chain alkaryls (or synthetic hydrocarbon compositions containing a major amount of di-n-long-chain alkaryls) and linear mono-olefin oligomers have certain unexpectedly improved properties over either alone.

More specifically, the mixtures of dialkaryls and linear mono-olefin oligomers provide the following improvements:

(a) The 40 F. viscosity, as compared to the interpolated viscosity, is lower than that of either material alone;

(b) The mixture is more compatible to additive combinations than the linear mono-olefin oligomers alone;

(c) Compositions comprising the mixture and various additive combinations have improved viscosity indexes as compared to either the dialkaryls or linear mono-olefin oligomers containing the additive package.

PRIOR ART A search of the prior art did not produce any reference 3,808,134 Patented Apr. 30, 1974 showing any advantages of mixtures of di-n-long-chain alkaryls and linear mono-olefin oligomers compared to either material alone. The search did produce thirteen US. patents concerned with the general state of the art of the individual materials. In order to make my disclosure complete these patents were the following: 2,190,918; 2,534,095; 3,173,965; 3,518,321; 2,327,705; 2,746,925; 3,436,349; 2,500,165; 3,057,801; 3,449,249; 2,500,244; 3,163,705; and 3,848,857.

BRIEF SUMMARY OF THE INVENTION Broadly stated, the present invention is directed to lubricant compositions comprising mixtures of di-n-longchain alkaryls and linear mono-olefin oligomers.

In one aspect, the invention is directed to lubricant compositions comprising mixtures of linear mono-olefin oligomers and a synthetic hydrocarbon composition containing a major amount of di-n-long-chain alkaryls.

In another aspect, the invention is directed to lubricant compositions comprising a major amount of a mixture of linear mono-olefin oligomers and di-n-long-chain alkaryls and a minor amount of conventional lubricating oil additives.

The relative amounts and nature of the various materials will be described in the detailed description.

DETAILED DESCRIPTION One component of the composition of my invention is a di-n-long-chain alkaryl or a synthetic hydrocarbon composition containing a major amount of di-n-long-chain alkaryls.

The term di-n-long-chain alkaryl refers to materials represented by the formula wherein R and R are alkyl groups containing from 6 to 18 carbon atoms, more suitably from about 9 to about 15 carbon atoms, and'preferably from about 10 to about 14 carbon atoms, with the sum of R and R being from about 20 to about 28 carbon atoms and wherein A and A are hydrogen or a C or C alkyl group, but preferably are hydrogen.

Thus the preferred di-n-long-chain alkaryl is a di-nalkylbenzene wherein the alkyl group contains from about 10 to about 14 carbon atoms.

The alkyl groups are substantially straight-chain (thus the term n-alkaryls) wherein, preferably, at least 95 percent of the alkyl substituents are bonded to the benzene nucleus through a secondary carbon atom of the respective alkyl groups. While we prefer the term nalkaryls other terms such as linear alkaryls or straight chain alkaryls are equally descriptive.

The first component of my invention also includes synthetic hydrocarbon compositions containing a major amount (i.e., 60 to weight percent) of the di-n-alkaryls, as defined in the foregoing, and a minor amount of other hydrocarbons, such as diphenylalkanes and trialkybsubstituted tetrahydronaphthalenes, having molecular weights corresponding to the di-n-long-chain alkaryls.

A particularly suitable material for the first component is a synthetic hydrocarbon composition having the fol lowing composition.

Component: Percent by weight Di-n-long-chain alkaryls 61-92 Trialkyl-substituted tetrahydronaphthalenes 5-30 Miscellaneous alkyl aromatics:

Less than 15 Preferably less than 10 The composition is also characterized as having the following properties:

Viscosity index 80-116 Pour point, F. -40-80 Molecular weight range 350-526 Preferably 375-480 The di-n-long-chain alkaryls meet the description provided in the foregoing.

The trialkyl-substituted tetrahydronaphthalenes can be represented by the formula wherein R and R contain from 1 to about 13 carbon atoms each, with the sum of R and R being from about 6 to about 14 and R and R contain from 1 to about 16 carbon atoms with the sum of R and R being from about 9 to about 17. The alkyl groups, R R R and R are straight-chain.

The trialkyl-substituted tetrahydronaphthalenes have the same boiling range as the di-n-alkylbenzenes. In addition, they have approximately the same molecular weight.

This particular synthetic hydrocarbon alkaryl lubricant can be prepared by any of several methods. It can be prepared by alkylating benzene and tetrahydronaphthalene and blending the resulting product. Also, it can be prepared by alkylating a mixture of mono-n-alkylbenzenes and dialkyl-substituted tetrahydronaphthalenes with a suitable alkylating agent. A particularly suitable method of preparing the synthetic hydrocarbon alkaryl lubricant is by the disproportionation of a monon-alkyl-benzene-rich feedstock using HF-BF aluminum bromide or aluminum chloride as the catalyst.

Suitable mono-n-alkylbenzenes are those containing from about 6 to about 18 carbon atoms in the alkyl groups. Preferably, the alkyl groups of the mono-n-alkylbenzenes contain from about 10 to about 15 carbon atoms. The term n-alkylbenzenes has been defined in the foregoing.

A particularly suitable method of preparing this latterdescribed synthetic hydrocarbon lubricant composition is described in US. Pat. No. 3,662,012.

The second component of my invention is a linear mono-olefin oligomer or mixture thereof. These materials are usually prepared from m-olefins using a suitable catalyst and are usually referred to as a-olefin oligomers. For preparing the a-olefin oligomers, there is used one or more a-olefins containing from 6 to 16 carbon atoms, more suitably from 8 to 12 carbon atoms and preferably 10 carbon atoms. The linear mono-olefin oligomer is characterized as containing at least 50 weight percent, more usually at least 60 weight percent, of materials containing 24 to 60 carbon atoms. When the linear monoolefin oligomer is prepared by oligomerization of a-olefins containing 8 to 12 carbon atoms preferably the maximum amount of dimer present is 10 weight percent. The linear mono-olefin oligomers can obtain very small amounts \(usually less than weight percent) of branched-chainolefins or di-olefins.

If desired, in order to improve the oxidation stability thereof, the linear mono-olefin oligomers can be treated by any of several known methods, such as hydrogenation or heat treatment. Whether or not the linear monoolefin oligomers have been treated to improve their oxidation stability does not affect the improvements due to mixtures of linear mono-olefin oligomers and di-n-alkylbenzenes as described herein.

The mixtures forming the composition of my invention can contain from about to about 90 weight percent, more suitably from about 30 to about 85 weight percent,

and preferably from about 50 to about weight percent linear mono-olefin oligomers.

USES FOR IMPROVED LUBRICANT COM- POSITIONS OF MY INVENTION As is readily apparent to those skilled in the art, there are many uses for the lubricant compositions of my invention. They can be used as crankcase lubricants, turbojet aircraft lubricants, turbine lubricants, hydraulic fluids, transmission fluids, combination crankcase and transmission fluids, steering fluids, and instrument lubricants.

While the lubricants of my invention have many uses per se, usually they are used in compounded formulations containing various additives. Examples of additives which can be used include dispersants and detergents, oxidation inhibitors, corrosion inhibitors, viscosity index improvers, antirust agents, and antifoam agents.

In order to disclose the nature of the present invention still more clearly, the following examples, both illustrative and comparative, will be given. It is to be understood that the invention is not to be limited to the specific conditions or details .set forth in these examples except insofar as such limitaitons are specified in the appended claims.

In the examples the test methods were ASTM or other standard tests. The viscosity index was based on measured and 210 F. viscosities.

The percent deviation from interpolated --40 F. viscosity can be explained as follows:

It is common practice in the petroleum industry to use what is known as ASTM viscosity blending paper to interpolate blend viscosities from component viscosities. It is generally observed that at a given temperature lubricant blends obey the relationship ln ln (K +A) ==X ln ln (K +A)-|-(1-X) ln ln (K -l-A) where K is the kinematic viscosity of the blend in centistokes, K and K are the blend component viscosities, A is approximately 0.6, and X is the weight fraction of component one in the blend. This expression is derived from the Walther equation which describes the viscosity-temperature relationship of lubricant blends. ASTM viscosity blending .paper as cited above linearly relates blend composition (X) to ln ln (K -l-A). This relationship was used to arrive at an interpolated blend viscosity. The difference between the interpolated and measured blend viscosities divided by the interpolated value is the percent deviation as used herein.

EXAMPLE 1 Oligomer The synthetic hydrocarbon lubricant was prepared by disproportionation of a predominantly Cm-Cm mono-nalkylbenzene using AlCl as the catalyst. It had the following composition by mass spectrometer:

Vol. percent Di-n-alkylbenzenes 2 68 Trialkyl-substituted tetrahydronaphthalenes 3 22.8

1 Substantially same as weight percent.

Predominantly (Biz-C14 alkyl groups.

a Substantially the same molecular Weight as the dl-ualkylbenzenes.

The physical properties of the a-olefin oligomers (a-O-O), the synthetic hydrocarbon lubricant (S.H.L.)

and various mixtures of the two materials are shown in Table I below.

TABLE I Composition No.

A B C D S.H.L., percent wt 100 0 90 80 a-O-O, percent wt 0 100 20 Viscosity cs. at-

F 9,587 6,769 8, 823 8,079 100 F-.- 29.77 31. 95 28. 97 28.45 210 F 5. 07 5. 84 5.09 5. 12 Percent deviation from interpolated 40 4.3 9. 0 Viscosity index 116 118 Pour point, F 70 60 1 Below 75.

EXAMPLE 2 This example illustrates the improvement in 40" F. viscosity of mixtures of a di-C -alkylbenzenes and two hydrogenated a-olefin ollgomers prepared from decene-l.

Vol. percent 1 Di-n-alkylbenzenes 69.3 Trialkyl-substituted tetrahydronaphthalenes 3 22.3

1 Substantially same as weight percent. Predominantly C12-Cu alkyl groups.

Substantially the same molecular weight as the di-nalkylbenzenes.

The viscosity properties of the a-olefin oligomer (a-O-O), the synthetic hydrocarbon lubricant (S.H.L.) and various mixtures of the two materials are shown in the table below.

TABLE III Percent devia- Viscosity Weight percent 210 100 0 tion index 5. 92-5. 89 35. 90-35. 06 882-884 8, 2128365 119-121 4. 97-4. 98 29. 03-28. 60 866-858 8, 793-8, 941 105-109 5. 15 29. 04 856 8, 559 1. 8 117 5. 39 30. 40 853 8, 3. 3 123 5. 63-565 31 8131.48 886-854 8, 217-8,254 2.3 128-132 5. 67 31. 92 856 8, 2 --1. 8 130 5.74 32.44 861 8,254 1.4 131 a (1 0 5.82 32.54 872 8,260 1.1 135 a-O-O, (95%); S.H.L., (5%) 5.89 33.11 868 8,322 0 315 1 From Interpolated 40 viscosity.

a-olefin oligomer B contained 37.5% decene-ltrimer 2% decene-l tetramer. a-Olefin oligomer B contained 37.5% decene-l trimmer and 62.5% decene-l tetramer.

The following examples illustrate the advantage of using mixtures of a-olefin oligomers and a synthetic hydrocarbon lubricant as the base oil in various compounded lubricants.

EXAMPLE 4 This example illustrates the advantage of using mix- The physical properties of the dialkylbenze (DAB-C 35 tures as a base oil in a hypoid gear oil. The gear oil cona-olefin oligomer A (a-O-O-A), and a-olefin oligomer B tained 6.5% of a commercial extreme pressure additive and 93.5 weight percent of the base oil. The synthetic hydrocarbon lubricant (S.H.L.) and oz-OlCfill oligomer TABLE IV Hypoid gear 011 Ratio: Percent S.H.L.: a-O-O 100:0 75:25 :50 25:75 0:100

Kinematic viscosity, cs. at-

40" F 10,328 9, 623 9, 331 9,060 9,809. Viscosity inde 111 113 123 126 118. Pour point 65 65 -70. Storage stability tw 150 Pass Pass Pass Pass Fail, precipitated.

................... Pass Pass Pass Pass Fail, cloudy precipitated.

*Sample cloudy when value determined,

(a-O-O-B) and mixtures of the dialkylbenzene and each of the oligomers are shown in Table H below.

TABLE II A B C D DAB-C11, percent wt 0 70. 2 70. 2 e-O-O-A, percent wt- 0 100 29. 8 0 d.-O-O'B, percent wt 0 0 0 29. 8 Viscosity indeq. 123 113 111 Viscosity cs. at-

20. 65 14. 57 18. 39 23. 26 210 F 4.06 3. 43 3. 86 4.44 Percent deviation from interpolated -40 vis 7. 5 5. 0 Pour point, F 75 75 EXAMPLE 3 This example illustrates the improvement in -40 F.

viscosity of mixtures of linear mono-olefin oligomers (a-O-O) were the same as in Example 3. The results are shown in Table IV.

EXAMPLE 5 TABLE V Gas turbine oil Ratio: Percent S.H.L.: Percent a-O-O Kinematic viscosity, cs. at-

5.33 100 F 30. 34 F 949 40 F 10, 452 Viscosity index 120 P0111 point a F '765 Storage stability; two weeks at- 150 F Pass cipitated. 0 F Pass Pass Fail, cloudy... Fail, cloudy. precipitated Fail. cloudy precipitated.

Not run, sample precipitated. 2 Sample cloudy when value determined.

EXAMPLE 6 This example is both illustrative and comparative in showing the eifect of using mixtures as a base oil in an SE. engine oil. Use of the mixtures gave an improvement in viscosity index but no improvement in compatibility to the additive package. The engine oil contained 7.95 weight percent of an additive combination which comprised an ashless dispersant, an overbased magnesium sulfonate, a zinc dithiophosphate inhibitor, an overbased calcium phenate', and an ashless antioxidant and 92.05 weight percent of the base oil. The synthetic" Hydrocarbon lubricant (S.H.L.) and a-oleiin oligomer '(m-O-O) were the same as in Examples 3, 4 and 5. The results are shown in Table VI.

TABLE VI S.E. engine oil Ratio: percent S.H.L.: percent a-O-O 100:0 75:25 50:50 25:75 0:100

Kinematic viscosity, cs. at-

210 F 6.02 6.25 6.46 6. 72 7. 07 100 F 30. B9 37. 47 38. 69 40. 11 45. 29 0 F 1,209 1, 194 1, 191 1, 204 1, 229 30 F--- 6, 719 6,546 6. 405 6, 340 6,447 Viscosity index- 119 127 130 135 126 Four point, F -65 60 65 65 65 Storage stability; two weeks at- 150 Pass Pass Pass Pass Pass 0 F Pass Pass Pass Pass 1 Sample cloudy when value determined.

EXAMPLE 7 ,decene;1 and contained at leas1; 5 0 weightprcent of oligomers containing 24-60 carbon atoms.

The di-n-C -alkylbenzene had the following composition, as determined by mass spectrometer:

Percent Didecylbenhenes 96.4 Tridecylbenzenes 2.9 Miscellaneous alkyl aromatics 0.6

The viscosity properties of the a-olefin oligomer (m-O-O) and the di-n-C -alkylbenzene (DAB-C and The data in Table VII shows that the measured 40 F. viscosity is lower (which is an improvement) than the interpolated viscosity for all of the mixtures and particularly is better for the blends containing 60, 40, and 20% of the oligomers. For example, on the blend containing 40% oligomers, the measured --40 F. viscosity was 4058 cs., while the interpolated viscosity was 4900 cs. Thus the measured viscosity showed a 17.1% deviation (an improvement) over the measured viscosity.

While we have defined previously what is meant by interpolated viscosity, the following amplification of the definition is provided. Referring to the table, it will be observed that ---4() F. viscosities for the pure materials were as follows: olefin oligomer-7949; di-C -alkylbenzone-2867.

The interpolated -40 F. viscosity for various mixtures of the two materials was determined by interpolation of these values using ordinary graph paper, whereas logarithmic graph paper was used in the other examples herein. This diiference in type of graph paper does not make a substantial difierence for the values described herein.

Thus, having described the invention in detail, it will be understood by those skilled in the art that certain variations and modifications may be made without departing from the spirit and scope of the invention as defined herein and in the appended claim.

I claim:

1. A lubricant composition comprising a mixture of about 30 to about 85 weight percent of a first component which is a linear mono-olefin oligomer, or mixtures thereof, and about 15 to about weight percent of a second component which is a di-n-C -C alkylbenzene, a mixture of di-n-C -C alkylbenzenes or a synthetic hydrocarbon composition containing a major amount of di-n- C -C alkylbenzenes, said linear mono-olefin oligomer, or mixtures thereof, containing at least 60 weight percent oligomers which contain 24 to 60 carbon atoms.

2. The lubricant-composition of claim 1 wherein said linear mono-olefin oligomers is prepared from a-olefins containing 8 to 12 carbon atoms.

3. The lubricant composition of claim 2 wherein the second component is a synthetic hydrocarbon composition various mix tures of the two are shown in Table VII. 50 having the following composition:

TABLE VII Ratio: percent a-O-O: percent DAB-Clo (by Weight) 100:0 90:10 :20 60:40 40:60 20:80 10:90 0:100

Measured kinematic viscosity at- 210 F 5. 5. 00 5. 23 4. 65 4. 10 F--- 33. 25 30. 41 27. 90 24v 00 20. 57 40 F 7,949 7,269 6,485 4,997 4, 058 Lineari y interpolated kinematic vlsocrty cs. at-

21 F 5. 65 5. 39 4. 88 4. 36 100 F 31. 5 29. 7 26. 1 22. 5 40 F 7,450 6, 940 5,910 4, 900 Percent deviation from interpolated viscosity 210 F 0.9 3. 0 4. 7 4. 0 100 F 3. 5 6. 1 8.0 8. 4 40 F 2. 4 e. 5 15. 4 l7. 1 Viscosity index 134 133 132 120 said synthetic hydrocarbon composition being characterized as having a molecular weight of about 375 to about 480, said fiialkyl-substituted tetrahydronaphthalenes being represented by the formula H t ll wherein R and R are straight-chain alkyl groups containing from 1 to about 13 carbon atoms each, with the sum of R and R being from about 6 to about 14, and wherein R and R are straight-chain alkyl groups containing from about 1 to about 16 carbon atoms, with the sum of R and R being from about 9 to about 17.

4. The lubricant composition of claim 1 wherein the amount of said first component is about 50 to about 80 weight percent and the amount of said second component is about 20 to about 50 weight percent.

5. The lubricant composition of claim 3 wherein the amount of said first component is about 50 to about 80 weight percent and the amount of said second component is about 20 to about 50 weight percent.

6. A lubricant composition comprising a mixture of about 10 to about 90 weight percent of a first component which is a linear mono-olefin oligomer, or mixtures thereof, said linear mono-olefin oligomer containing at least 50 weight percent oligomer, which contain 24 to 60 carbon atoms, and about 10 to about 90 weight percent of a second component which is a di-n-long-chain alkaryl compound, a mixture of di-n-long-chain alkaryl compounds, or a synthetic hydrocarbon composition containing a major amount of di-n-long-chain alkaryl compounds, said lubricant composition being characterized in that:

(a) said di-n-long-chain alkaryl compound is represented by the formula wherein R and R are substantially straight-chain alkyl groups containing from 6 to 18 carbon atoms, with the sum of R and R being from about 20 to about 28 carbon atoms and wherein A and A are hydrogen or a C or C alkyl group, and

(b) said synthetic hydrocarbon composition has the following composition:

10 Component: Percent by weight Di-n-long-chain alkaryls 61-92- Trialkyl-substituted tetrahydronaphthalenes 5-30 Miscellaneous alkyl aromatic compounds 15 said synthetic hydrocarbon composition being characterized as having a molecular weight range of about 350 to about 526, said di-n-long-chain alkaryls being represented by the formula wherein R and R are substantially straight-chain alkyl groups containing from 6 to 18 carbon atoms, with the sum of R and R being from about 20 to about 28 carbon atoms, and wherein A and A are hydrogen or a C or C alkyl group, said trialkyl substituted tetrahydronaphthalenes being represented by the formula wherein R and R are straight-chain alkyl groups containing from 1 to about 13 carbon atoms each, with the sum of R and R being from about 6 to about 14, and wherein R and R are straight-chain alkyl groups containing from about 1 to about 16 carbon atoms, with the sum of R and R being from about 9 to about 17.

7. The lubricant composition of claim 6 wherein said linear mono-olefin oligomer is prepared from a-olefins containing 6 to 16 carbon atoms.

8. The lubricant composition of claim 7 wherein the alkyl groups R and R contain from about 9 to about 15 carbon atoms.

9. The lubricant composition of claim 8 wherein R and R contain from about 10 to about 14 carbon atoms.

10. The lubricant composition of claim 9 wherein A and A are hydrogen.

11. A lubricant composition of claim 10 wherein said linear mono-olefin oligomer is prepared from a-olefins containing 8 to 12 carbon atoms.

References Cited UNITED STATES PATENTS 3,322,848 5/1967 Garwood et a1 252-59 X 3,598,739 8/1971 Sias 25259 X 3,642,634 2/ 1972 Olund 25259 X WARREN H. CANNON, Primary Examiner