US2500164A - Synthetic lubricant - Google Patents

Description

Patented Mar. 14, 1950 SYNTHETIC LUBRICANT William E. Garwood, Haddonfield, Francis M. Segcr, Pitman, and Alexander N. Sachanen, Woodbury, N. J., assignors to Socony-Vacuum Oil Company, Incorporated, a corporation of New York No Drawing. Application December 2, 1948, Serial No. 63,204

13 Claims. (Cl. 252-45) This invention has to do with synthetic lubricants and, more particularly, has to do with a process for preparing a new and novel class of synthetic lubricants from certain normal, alpha mono-olefins and sulfur.

As is well known to those familiar with the art, hydrocarbons have been sulfurized by various means to develop products useful as lubricants or suitable for use as adjuvants. Considerable attention has been directed to sulfurization of olefins, in view of the known ease of reaction between sulfur and unsaturated materials. Generally, the products prepared by sulfurizing olefins contain relatively large amounts of sulfur, are dark in color and are characterized by a relatively low viscosity index and/or high pour point, all of which properties limit their utility. For example, such products are effective for use in. cutting oils or even as cutting oils per se, but are not suitable for use as lubricants for internal combustion engines.

In all of the prior art, however, there has been no reported success in the preparation of stable synthetic lubricants of low sulfur content, high viscosity index and low pour point. It has now been discovered that certain mono-olefins can be polymerized with sulfur under well-defined con.- diticns to form successfully synthetic lubricants having the aforesaid desirable properties. In the process of this invention normal, alpha monoolefins having from about 6 carbon atoms to about 14 carbon atoms are reacted with sulfur at temperatures within the range of about 550 to 750 F., the quantity of sulfur so reacted being from about 0.01 mol (atomic weight) to about 0.15 mol and, preferably less than 0.05 mol, per mol of olefin.

REACTANTS As indicated above, the mono-olefins of this invention are normal or straight-chain alpha, mono-olefins and contain from about 6 to about 14 carbon atoms. Such mono-olefins are normally liquid at temperatures of the order of 20-25 C. Illustrative of such olefins are: hexene-l, octene-l, decene-l, dodecene-l, tetradecene-l, and the like. Preferred of such olefins, however, are those having from 8 to 12 carbon atoms, with decene-l forming particularly outstanding synthetic lubricants. It will be clear from the foregoing examples that an alpha olefin may also be referred to as a l-olefln.

Not only may the mono-olefins of the aforesaid character be used individually in this invention, but they may also be used in admixture with each other. In addition, olefin mixtures con- 2 taining a substantial proportion of such monoolefins may be used. Preferred of such mixtures are those containing a major proportion of a lolefin or of l-olefins. Representative of such mixtures are those obtained by the cracking of paraflin waxes and other; paraffin products, and those obtained from the Fischer-Tropsch and related processes. These hydrocarbon mixtures may contain, in addition to the l-olefin or l-olel fins, such materials as: other olefins, 'parafilns.

fected with elemental sulfur. Also contemplated herein, however, are the related materials: selenium and tellurium, which provide excellent synthetic lubricants in the process of this invention. Selenium and tellurium may replace sulfur in part or in entirety, and mixtures of two or all three of said substances may be used. It will be noted that each of these substances is in class VIB of Mendelejeffs Periodic Table, with atomic weights ranging from 32 to 128.

In view of the availability and low cost of sulfur, and particularly in view of the outstanding character of the oils obtained therewith, sulfur is particularly preferred herein. It is on this basis that the following discussion and illustrative examples are directed to polymerization-s involving sulfur.

REACTION CONDITIONS Polymerization of the aforesaid l-olefins is effected under critical conditions. Temperature must be maintained within the range of about 550 F. to about 750 F'., and preferably between about 600 F. and about 700 F. Critical also is the proportion of sulfur used with the l-olefin, from about 0.01 mol to about 0.15 mol of sulfur being used for each mol of l-olefin. As shown hereinafter, the interrelation of l-olefin, temperature and proportion of reactants provides the particularly outstanding synthetic lubricants. When either of these factors falls without the limits defined above. substantially inferior lubricants are formed or lubricants are obtained in but small yield.

Polymerization is generally complete in from charged. The contents of the bomb were vacuum topped to remove unreacted hydrocarbons and products of low molecular weight. It should be noted that the reaction times, recited as time,

1 to 20 hours, with the higher reaction temperahours" in Table I, represent the time intervals ture being used for the shorter reaction periods, during which the bomb was maintained at the and with the lower reaction temperatures being desired temperature, and do not include the time used for the longer reaction periods. Ten hours intervals necessary to heat the bomb and its has been found to be an eilective time interval contents to the desired temperature, and do not with temperatures of the order of 650 F. include the time intervals necessary to cool the Pressures ranging from atmospheric to 4000 bomb after heat to the bomb has been disconpounds per square inch, most frequently about 500 tinued. Normally, about 1 hours are required pounds, characterize the polymerization. It is to raise the temperature of the bomb to about desirable to use sufilcient pressure to maintain 650 F.; similarly, several (about 8) hours are rethe reactants in liquid state. quired for the bomb to cool to room temperature It will be understood, of course, that the polyafter being maintained at 650 F. for ten hours. merization is aided by providing mixing of the The reaction or polymerization products disreactants. This may be provided by using various charged from the bomb, or other reaction vessel, agitating means which are well known in the were topped and filtered as in the runs shown in art. At the reaction conditions, the reactants are Table I. To distinguish the polymerization prod mutually soluble and homogeneity is readily atucts from the distillate fractions thereof, the retained. fined oils are identified as residual oils. The

latter term identifies the oils from which unre- EXAMPLES acted materials and products of intermediate In order to illustrate the principles of this inboiling range have been separated. vention, the results of a series of typical, and All of the tests and analyses to which the renon-limiting, polymerizations are set forth in sidual oils in Table I were subjected are well tabular form in Table I below. These polymeriknown standard tests. In this connection, it zations were carried out in a rocking-type bomb will be noted that the designation "N. N." refers (American Instrument 00.). The reactants were t0 t neutralization number, which s a easu e charged to the bomb, the free space was swept of the acidity of the oil. The abbreviation "K. V. with nitrogen, and the bomb was heated to the at 210 F., Cs. is used to identify the kinematic desired temperature for the desired length of viscosity (of the residual oils) at 210 F., measured time. Thereafter, the bomb was cooled and disin centistokes.

Table I Influence oi Olefin Structure Influence oi Reaction Temperature Run No.

Olefin Octane-1.- Octane-2.- 2-Ethyl Hexene-l- Decene-L. Decene-L. Decene-l Decene-l,

Parts by Weight. see 336 33a 2ao x2.e)...... 280. Molar Proportion 2(X2.6) 2. Sulfur:

Parts by Weight-- 2(x2.5) 2. Molar Proportion 006250 0.0625. Temperature, F 652 Time, Hrs Max. Pressure, p, s. i. g...- Residual Oil:

Yield, Percent l K. v. @210F., Cs V. I Pour Point, F s m a vit as. areas). Sulfur. Per Cent.--

Influence oi Sulfur Concentration Run No.

Olefin Tri isobutylene.

Partsb Weilzht 332. Molar roportinn 2. ur: Parts by Weight 2 l6. Molar Proportion" 0.5. 12---- 600.

Cop r Gasket Corro ed During Rene tion Black 'Iar Left Pour Point, "F in Bomb.

c rav y..- 083m (Lovibond) Sulfur, Per Cent 1 Based upon original charge materials; reaction product distilled to a maximum temperature 0! 200 0. at mm. to remove intermediate products.

From the data in Table I above, it will be seen, in runs 1, 2 and 3, that a substantially larger yield of synthetic oil is obtained from octene-l (a normal, alpha mono olefin) than from either octene-2 or 2-ethylhexene-1. Further, the viscosity index (V. I.) of the synthetic oil from octene-l is appreciably higher than the viscosity indices for the oils prepared from octene-2 or 2-ethylhexene-l.

Runs 4 through 7, inclusive, demonstrate the critical nature of the reaction temperature. At a temperature of 502 F. (run No. 4) a synthetic oil is obtained in relatively small yield and has a high sulfur content. When the temperature is maintained within the range of GOO-702 F. (runs 5-7), synthetic oils are obtained in substantially larger yields than in run 4 at 510 F. and the sulfur content of the synthetic oils is at a desirable level.

Runs 8 and 9 indicate the influence of the proportion of sulfur, for when a larger proportion than contemplated herein is used the viscosity index falls and the yield decreases somewhat.

Runs 10 and 11 represent two additional synthetic oils, illustrative of the invention.

Runs '12 and 13 further illustrate the interrelation of olefin structure, reaction temperature and concentration of sulfur. For example, in run 12, the olefin used is butene-l and the reaction temperature is only 500 F.; the product was a black tar. In run 13, the olefin was triisobutylene and the temperature of reaction only 500 F.; again a black tar was formed.

That the residual oils illustrated above in Table I are characterized by a high degree of stability is revealed by the results of a catalytic oxidation test for the oil of run 6. In this test 6.5 feet of No. 14 (Brown and Sharpe gauge) iron wire (15.6 square inch), 6.2 inches of No. 18 (B. & S.) copper wire (0.78 square inch), 3.33 inches of No. 12 (B. & S.) aluminum wire (0.87 square inch), a A; inch square of 1% inch lead sheet (/18 square inch), and cos. of the test oil were placed in a glass test tube, heated to 260 F. and air blown therethrough at the rate of 10 liters per hour for hours.

Changes in the characteristics of the oil and effect of the oil upon the lead sheet were reported. The results of this test with the residual oil of run 6, and with a SAE-10 solvent-refined Pennsylvania motor oil, are shown in Table II below.

Table II N N K. V. at Percent Pb Loss, 210 F.,Cs. Vls.lncr. mgms.

Reference Oil 16 12. 91 125 236 Oil 01' Run 6 0.9 3.77 5.0 40.1

The test data set forth in Table II clearly indicate the high degree of stability which characterizes the oils contemplated herein.

As will be evident from the data presented above in Tables I and II, the polymerization products of this invention are highly desirable lubricants per se. They are also of considerable value as blending agents for other lubricating oils. In view of the inherent stabilit of the synthetic oils, they impart stability to the oils with which they are blended. So also, they impart desirable viscosity index (V. I.) and pour point characteristics to the oils in combination therewith, for, as indicated above, they have advantageous viscosity index and pour point properties. In short, the synthetic oils find utility in upgrading other lubricants. Typical oils with which the synthetic oils may be blended are mineral oils such as are normally used in internal combustion and turbine engines. When so blended, the synthetic oils may comprise the major proportion of the final blended oil, or may even comprise a minor proportion thereof. For example, although used only in the amounts of the order of 1 to 10 per cent, the synthetic oils improve the stability of mineral oils, such as SAE 10 and 20 Pennsylvania type oils.

One or more of the individual properties of the synthetic lubricants of this invention may be further improved by incorporating therewith a small, but effective amount, of an addition agent such as an antioxidant, a detergent, an extreme pressure agent, a foam suppressor, a viscosity index (V. I.) improver, etc. Antioxidants which may be used are well-known in the art; and are generally characterized by phosphorus, sulfur, nitrogen, etc. content; representative of such materials is a phosphorusand sulfur-containing reaction product of pinene and P285. Typical detergents which may be so used are metal salts of alkyl-substituted aromatic sulfonic or carboxylic acids, as illustrated by diwax benzene barium sulfonate and barium phenate, barium carboxylate of a wax-substituted phenol carboxylic acid. Extreme pressure agents are well known; illustrating such materials are numerous chlorine and/or sulfur containing compositions, one such material being a chlornaphtha xanthate. Silicones, such as dimethyl silicone, may be used to illustrate foam suppressing compositions. Viscosity index improving agents which may be used are typified by polypropylenes, polyisobutylenes, polyacrylate esters, and the like.

Contemplated also as within the scope of this invention is a method of lubricating relatively moving surfaces by maintaining therebetween a film consisting of any of the aforesaid oils.

It is to be understood that the foregoing description and representative examples are nonlimiting and serve to illustrate the invention, which is to be broadly construed in the light of the language of the appended claims.

We claim:

1. The method of preparation of a viscous oil, which comprises: polymerizing, at a temperature between about 550 F. and about 750 F., for a period of time from about twenty hours to about one hour, respectively, a normal, alpha mono-' olefin having from about 6 to about 14 carbon atoms, in the presence of an elemental substance selected from the group consisting of sulfur, selenium and tellurium,- the molar ratio of said substance to said olefin being from about 0.01 to about 0.15.

2. The method of preparation of a viscous oil, which comprises: polymerizing, at a temperature between about 550 F. and about 750 F., for a period of time from about twenty hours to about one hour, respectively, a normal, alpha monoolefin having from about 6 to about 14 carbon atoms, in the presence of sulfur, the molar ratio of sulfur to said olefin being from about 0.01 to about 0.15.

3. The method of preparation of a viscous oil, which comprises: polymerizing, at a temperature between about 600 F. and about 700 F., for a period of time from about twenty hours to about one hour, respectively, a normal, alpha monoolefin having from about 6 to about 14 carbon atoms, in the presence of sulfur, the molar ratio of sulfur to said olefin being from about 0.01 to about 0.15.

4. The method of preparation of a viscous oil,

which comprises: polymerizing, at a temperature between about 550 F. and about 750 F., for a period of time from about twenty hour to about one hour, respectively, a normal, alpha monoolefin having from about 8 to about 12 carbon atoms, in the presence of sulfur, the molar ratio of sulfur to said oleflne being from about 0.01 to about 0.15.

5. The method of preparation of a viscous oil, which comprises: polymerizing decene-l in the presence of sulfur, at a temperature between about 550 F. and about 750 F., for a period of time from about twenty hours to about one hour, respectively, the molar ratio of sulfur to decene-l being from about 0.01 to about 0.15.

6. A viscous oil obtained by: polymerizing, at a temperature between about 550 F. and about 750 F., for a period of time from about twenty hours to about one hour, respectivel a normal, alpha mono-olefin having from about 6 to about 14 carbon atoms, in the presence of an elemental substance selected from the group consisting of sulfur, selenium and tellurium, the molar ratio of said substance to said olefin being from about 0.01 to about 0.15.

7. A viscous oil obtained by: polymerizing, at a temperature between about 550 F. and about 750 F., for a period of time from about twenty hours to about one hour, respectively, a normal, alpha mono-olefin having from about 6 to about 14 carbon atoms, in the presence of sulfur, the molar ratio of sulfur to said olefin being from about 0.01 to about 0.15.

8. A viscous oil obtained by: polymerizing, at a temperature between about 600 F. and about 700 F., for a period of time from about twenty hours to about one hour, respectively, a normal, alpha mono-olefin having from about 6 to about 14 carbon atoms, in the presence of sulfur, the molar ratio of sulfur to said olefin being from about 0.01'to about 0.15.

9. A viscous oil obtained by: polymerizing, at a temperature between about 550 F., and about 750 F., for a period of time from about twenty hours to about one hour, respectively, a normal. alpha mono-olefin having from about 8 to about 12 carbon atoms, in the presence of sulfur, the molar ratio of sulfur to said olefin being from about 0.01 to about 0.15.

10. A viscous oil obtained by: polymerizing decene-1 in the presence of sulfur at a temperature between about 550 F. and about 750 F., for a period of time from about twenty hours to about one hour, respectively, the molar ratio of sulfur to decene-l being from about 0.01 to about 0.15.

11. A viscous oil obtained by polymerizing decene-l in the presence of sulfur at about 650 F. for about 10 hours, the molar ratio of sulfur to decene-l being about 0.03.

12. A viscous oil obtained by polymerizing' decene-i in the presence of sulfur at about 600 F. for about 10 hours, the molar ratio of sulfur to decene-l being about 0.03.

13. A viscous oil obtained by polymerizing decene-l in the presence of sulfur at about 700 F. for about 3 hOurs, the molar ratio of sulfur to decene-l being about 0.03.

WILLIAM E. GARWOOD. FRANCIS M. SEGER. ALEXANDER N. SACHANEN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,246,282 Zimmer June 17, 1941 2,312,750 Cohen Mar. 2, 1943 2,338,829 Werntz Jan. 11, 1944

Claims (1)

1. THE METHOD OF PREPARATION OF A VISCOUS OIL, WHICH COMPRISES: POLYMERIZING, AT A TEMPERATURE BETWEEN ABOUT 550*F. AND ABOUT 750*F., FOR A PERIOD OF TIME FROM ABOUT TWENTY HOURS TO ABOUT ONE HOUR, RESPECTIVELY, A NORMAL, ALPHA MONOOLEFIN HAVING FROM ABOUT 6 TO ABOUT 14 CARBON ATOMS, IN THE PRESENACE OF AN ELEMENTAL SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF SULFUR, SELENIUM AND TELLURIUM, THE MOLAR RATIO OF SAID SUBSTANCE TO SAID OLEFIN BEING FROM ABOUT 0.01 TO ABOUT 0.15.