US2836563A - Lubricating grease thickened with sodium myristate and a phthalocyanine - Google Patents

Description

LUBRICATING GPEASE THICKENED WITH S DIUM P/iYRISTATE AND A PHTHALOCYANINE No Drawing. Application May 7, 1954 Serial No. 428,366

9 Claims. (Cl. 252-421) This invention relates to lubricating greases wherein phthalocyanine compounds and sodium myristate are employed in combination as thickening agents.

The use of phthalocyanine compounds as thickening agents in lubricating greases has been disclosed by Merker et al., U. S. Patent No. 2,597,018, who prepared greases by thickening lubricating oils of various types with phthalocyanine compounds in finely divided form. The greases thus obtained were found to be superior. to the conventional soap thickened greases in several respects, particularly in their improved stability and resistance to oxidation at elevated temperatures.

We have now found that by employing phthalocyanine compounds in conjunction with sodium myristate as thickening agents, greases are obtained having very superior lubricating properties, particularly at elevated temperatures, not obtainable by the use of either phthalocyanine compounds or sodium myristate separately as thickening agents. This result is very unexpected in View of the Wellknown efiect of soaps generally in degrading the lubricating properties of greases at elevated temperatures, as discussed for example by Merker et al.

The lubricating greases of our invention comprise an oleaginous liquid lubricating base thickened to a grease consistency with at least a substantial proportion of sodium myristate and at least a substantial proportion of a phthalocyanine in finely divided form, suitably in the form of particles not more than about 15 microns in diameter. The composition may suitably comprise about to 20 percent by weight based on the weight of the composition of sodium myristate and about 5 to 20 percent by weight based on the Weight of the composition of a phthalocyanine in finely divided form, the two materials being present in amounts sufficient to thicken the composition to a grease consistency by their combined effect. The sodium myristate and phthalocyanine are preferably employed in a proportion of from about 2 to 1 to about 1 to 2 by weight. The lubricating oil base may be any suitable oil of mineral, vegetable, animal or synthetic origin, such as have been employed heretofore in lubricating greases. With particular advantage, where a wide temperature range grease is desired, the oil base may comprise at least a substantial proportion'of a high molecular weight polyester of lubricating characteristics.

Additives of the usual types may be employed, such as oxidation inhibitors, corrosion inhibitors, tackiness agents, extreme pressure agents, and so forth. An oxidation inhibitor is preferably employed, which may suitably be an inhibitor of the amine type, such as diphenylamine, a-naphthylamine, b-naphthylamine, p-phenylene diamine and N,N' diphenyl p-phenylene diamine. A compound of this type may be present in amounts of from about 0.05 percent to about 5 percent by weight based on the weight of the composition. Also, additional thickening agents may be present in minor amounts, such as other soaps and other finely divided solids.

1 The preparation of these greases may be carried out rates Patent 0 by any convenient method, such as by adding the sodium myristate soap and the phthalocyanine either separately or together during the grease making process, or by forming a sodium myristate thickened grease and a phthalocyanine thickened grease separately and then mixing the two. The sodium myristate soap is preferably prepared by saponifying a mixture of low molecular weight fatty acids comprising at least 70 percent, and preferably at least percent of myristic acid and/ or the glycerides of such acids with an aqueous solution of sodium hydroxide in the presence of a small amount of mineral lubricating oil. A small excess of sodium hydroxide may be employed in this saponification; advantageously, the finished grease may contain about 0.02-0.2 percent of free alkali (calculated as sodium hydroxide). However, this is not an essential condition, and the grease may be neutral or even slightly acid if desired.

As a preferred embodiment of this invention, lubricating greases of outstandingly superior properties over a wide temperature range are obtained by employing both sodium myristate and a phthalocyanine in finely divided form as thickening agents in a high molecular weight polyester of the type disclosed by R. T. Sanderson in U. S. 2,628,974, obtained by reacting a dibasic aliphatic acid with a glycol and end blocking the reaction product with a monohydric aliphatic alcohol or a monocarboxylic aliphatic acid. Particularly suitable polyesters of this character are products obtained by reacting a mono-' or poly-alkylene glycol with a dicarboxylic acid and a mono hydric alcohol, represented by the formula wherein R is an aliphatic group or an aliphatic ether group containing from 4 to 12 carbon atoms, R is an aliphatic group containing from 1 to 12 carbon atoms, R is an aliphatic group containing from 1 to 12 carbon atoms and x is an integer from 1 to 5. Preferably, R is an aliphatic group or an aliphatic ether group containing from 6 to 12 carbon atoms in branched chain arrangement, R is an alkylene group containing 7 to 8 carbon atoms, R is an alkyl group containing from 4 to 9 carbon atoms in branched chain arrangement and x is 1 or 2. An ester of this type comprises from about 20 percent up to percent of the oil component of the grease, the remainder being a mineral oil or other oil of a different type. The composition preferably contains also about 0.1-8 percent by weight of N,N' diphenyl para-phenylene diamine and about 0.545 percent by weight of tricresyl phosphate.

Greases of the above type wherein both sodium myristate and a phthalocyanine are employed as thickening agents in a high molecular weight polyester base have very exceptional high temperature properties, required for the long-time lubrication of bearings at temperatures as high as 400 F., in addition to very excellent low temperature properties down to -60 F.

As an example of the greases of this preferred'embodiment of our invention, a grease was prepared by mixing together a copper phthalocyanine thickened grease and a sodium myristate thickened grease having the following compositions by weight:

I a 3 The synthetic "ester of the abovecompositions was a synthetic oil obtained by reacting together sebacic acid, 2-ethylhexane-1,3-diol and 2-ethylhexanol in about a 2:112 ratio, respectively, and consisting predominantly of the compound- (isoeCgI-l OOO(CH COO-iso-C H j v V I' V The mineral oil was a refined paraflinic distillate oil having an SUS viscosity at 100 F. of 330. a

The copper phthalocyanine was the pure compound in finely divided form obtained from the E. I. du vPont de Nemours Company. It had an average particle size of about 0.1 micron diameter, and a measured surface area 7 of 83 square meters per gram.

The sodium myristate thickened grease was obtained saponification number of 234 anda titer, C. of- 45.7, with sodiumhydroxide in the and then adding the synthetic ester gradually while the temperature was allowedto fall. The copper phthalocyanine thickened grease was prepared by forming a slurry of 'the'copper phthaiocyanine in the synthetic ester and then milling in a colloid mill until a smooth grease was obtained' This ordinarily requires 1 or 2 passes at 0.003 inch to 0.001 inch clearance. The greases obtained as described above were mixed in approximately equal proportions by weight and an additional amount otsynthetic ester added, amounting to about one fifth of the weight of the mixture, to give a grease containing percent of thickening agent. The grease was finished hy passing it twice through a Manton Gaulin homogenizer, with the second stage valve closed until the gauge read 4000 pounds pressure and the first stage valve closed until the gauge read 5000 pounds pressure. A smooth blue shoft fiber grease was obtained. The following table shows the physical properties of this grease (Grease No, 2) at both high and low temperatures as compared with a grease of equivalent grade thickened with copper phthalocyanine alone.

TABLE I Grease No Q 1 2 Grease Composition:

Copper phthalocyaulne Sodium myristate r s;

' Diphenyl-p-phenylen Tricresyl phosphate. Synthetic ester base- Mineral oil Inspection Tests:

Dropping point, F tttt Umvorked penatmtmn, r. r 265 270 Wmkedpenetratlon Low Temperature Torque: Seconds] revolution at- 2OS'.F

amete at WUIWNH WWWHH 'The low temperature torque test. of the foregoing table is essentially a measure of the resistance of a grease to congealing and of its ability to afford proper lubrication under'extremely low temperature conditions, such as are encountered in aircraft at very high altitudes. paratus employed for the test consists essentially of a vertically-mounted hollow spindle. with a No. 204KCon rad type 8-ball bearing mounted on the bottom, and a: drum on which is wrappeda coiled line for applyingtorquei mounted on the top. :The bearing, packed WithaGQ persaponifying a commercial myristic acid, having a presence of the mineral l'ubricating oil, and about an equal amount of'water at 170-190 F. dehydrating for two hours at 295-320 F.

The ap-t cpnt capacity charge of the grease, to be tested, is clamped at the inner'race to the spindle,' while the outer race clamped immovably'to a stationary cup within which the bearing is inserted. The assembly is inserted with the low er bearing end in a low temperature bath containing iso- V propyl alcohol, and the desired temperature of the bathand bearing is attained by dropping'Dry Ice in the, bath. The drum and drum extension carried at the uppergend of the hollow spindle and protruding from the bath are held in vertical position by a tapered roller bearing. The line coiled around the drum extends over a pulley to a container into which the desired weights are added to apply the torque load to the hollowspindle to thereby cause rotation of the spindle and inner race of the bearing with Atime of not less than two hours is utilized to cool the bearing to the test temt respect to the fixed outersrace.

perature, and an additional soaking period at the test temperature is permitted such that the test 'is not" run until three hours from the start of cooling; When the desired bearing temperature and soaking period are attained, a 2000 gram-'centimeter'torque load is applied in both clockwise and counter-clockwise directions, and the number of seconds for one rotationin each direction is observed. The values obtained with rotation in clockwise and counter-clockwise directions are given-sepa-.

rately in the tableunder the headings CW and CCW, respectively; r s

As shown by'the foregoing table, the grease of our invention, containing bothsodium myristateand copper phthaloc'yanine, had a high dropping point above 500 F; combined with very low torque at temperatures down to -60 F. It wasconsiderably superior in these respects to the grease thickened with sodium myristate alone and fully equivalent to the grease thickened with copper phthalocyanine alone, and in addition-it showed less change upon Working than did either of these other I greases; As compared with the copper phthalocyanine thickened grease it had a-rvery considerable advantage fromtheystandpoint of cost,-since it required only 7.5 percent of sodium myristate and 7.5 percent of'co'pper phthalocyanine, whereas 25 percent of the very expensive copper phthalocyanine was required to produce a grease of the same grade, whenitwas employed as, the soles thickening, agent.

- The following table shows the high temperature pertormance properties of the greases of Table I, as well as those of other greases of this invention containing larger proportions of sodium myristate and copper phthalocyamine and also of greases wherein carbon'black is employed as a thickening: agent. The latter are included as representative'of the other solids thickened greases of the prior'art. All of the: greases of this table contained thesame' esterbase-and inhibitors as the greases of Table L'greases No. 3, 4: and 6 also containing 5.9 percent, 6.7 percent and 4.0 percent, respectively, of the mineral lubricating oil employed in the greases of Table I in admixture with the ester base, and grease No. 5 containing the ester as the sole oleaginous component. Greases No. l and 2 of this table correspond to the like numbered greases of Table I. Y

The high temperature performance test of the foregoing table is a test for determining the performance characteristics of greases in'anti-friction bearings at elevated temperatures and high rotative speeds. The test unit consists essentially of a steel spindle supported on ball bearings in an electrically heated housing and driven by an electric motor connected into an electric circuit containing a low amperage fuse 0.1 ampere below that required for full load running. The bearings are Norma- Hoffman ABEC No. 3 grade, and are mounted on the spindle approximately 5% inches apart. A thrust load of 17.5 pounds is applied to the bearings. One bearing is used for test purposes and the second hearing, which is not heated, is used as a guide hearing. The test consists of operating the test bearing for twenty-four hours at 10,000 R. P. M. and at a temperature of 325 F. or 400 F. followed by a shut down and cooling period of two hours, and repeating this cycle until the lubricant fails, which is indicated by rupture of the low amperage fuse in the motor circuit. In carrying out the test at 400 F., Marlin Rockwell special heat treated high speed tool steel bearings with silver plated bronze retainers are used. In starting up the test, three grams of the test grease are charged to the test bearing and worked into and around the races and balls. The bearing is next rotated both clockwise and counter clockwise for one minute each at 200 R. P. M. and assembled into the test unit. The heaters and the motor are then started and the test bearing brought up to the test temperature as rapidly as possible, which requires 1.0 to 1.25 hours, while the spindle is rotated at a speed of 10,000 R. P. M. After 24 hours of operation the heaters and motors are shut off for 2 hours, during which the temperature of the test bearing drops to a minimum of 120-130 F. The total hours of operation, excluding the two hour shutdown periods, to the failure point is recorded as the hours to failure.

As shown by Table 11, the greases containing both sodium myristate and copper phthalocyanine as thickening agents ran for over twice as long in the high temperature performance test at 325 F. as did the grease thickened with copper phthalocyanine alone, showing that a pronounced synergistic effect results from the combination of these two types of materials in a grease. The unpredictable nature of this synergistic efiect is shown by the fact that the use of sodium myristate as a partial thickening agent in a carbon black thickened grease had only the expected elfect of degrading the high temperature properties of the grease.

While copper phthalocyanine has been employed in the specific examples of greases of our invention described above, it is to be understood that other phthalocyanine compounds, having closely similar properties as thickening agents in greases may also be employed. Compounds of this class, which are disclosed in the above cited patent of Merker et al., include metal phthalocyanines generally, such as for example zinc, nickel and aluminum phthalocyanines, metal-free phthalocyanine, chlorinated phthalocyanine and chlorinated metal phthalocyanines. Also, as discussed hereinabove, other lubricating oils, such as mineral lubricating oils or synthetic oils of different types, may be employed as the oil component in place of the complex polyester employed in the described examples. In addition, various other additives of the usual types employed in lubricating greases may be employed in place of the diphenyl-p-phenylenediamine and the tricresyl phosphate, and minor amounts of other thickening agents, such as other soaps and other finely divided solids, may be employed in these compositions.

This is a continuation-in-part of our application Serial No. 307,154, filed August 29, 1952, now abandoned.

Obviously many modifications and variations of the invention; as hereinbefore set forth, may be made with out departingfrom the spirit and scope thereof, and therefore only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. A lubricating grease consisting essentially of an ole'aginous liquid lubricating base thickened to a grease consistency with about 5 to 20 percent by weight based on the weight of the composition of sodium myristate and about 5 to 20 percent by weight based on the weight of the composition of copper phthalocyanine.

2. The lubricating grease of claim 1 wherein the proportion of sodium myristate to copper phthalocyanine is from about 1:2 to about 2:1 by weight.

3. The lubricating grease of claim 1 wherein the oleaginous liquid, lubricating base consists essentially of a high molecular weight polyester of lubricating characteristics.

4. The lubricating grease of claim 3 wherein the polyester is a product obtained by reacting a dibasic aliphatic acid with a glycol and a compound selected from the group consisting of monohydric aliphatic alcohols and mono-carboxylic aliphatic acids.

5. The lubricating grease of claim 3 wherein the polyester is represented by the general formula wherein R is selected from the group consisting of aliphatic groups and aliphatic ether groups containing from 4 to 12 carbon atoms, R is an aliphatic group containing from 1 to 12 carbon atoms, R is an aliphatic group containing from 1 to 12 carbon atoms and x is an integer from 1 to 5.

6. The lubricating grease of claim 3 wherein the polyester is represented by the general formula wherein R is an aliphatic group containing from 6 to 12 carbon atoms in branched chain arrangement, R is an aliphatic group containing from 7 to 8 carbon atoms, R is an aliphatic group containing from 4 to 9 carbon atoms in branched chain arrangement and x is an integer from 1 to 2.

7. A lubricating grease consisting essentially of an oleaginous liquid lubricating base containing about 5-15 percent by weight of sodium myristate, about 5-15 percent by weight of copper phthalocyanine, about 0.1-8 percent by weight of N,Ndiphenyl para-phenylene diamine and about 0.3-15 percent by weight of tricresyl phosphate, said oleaginous liquid lubricating base consisting essentially of a polyester represented by the general formula:

wherein R is an alkylene group containing from 4 to 12 carbon atoms in branched chain arrangement, R is an alkylene group containing from 1 to 12 carbon atoms, R is an alkyl group containing from 1 to 12 carbon atoms in branched chain arrangement and x is an integer from 1 to 5.

8. The lubricating grease of claim 7 wherein the polyester is a compound having the formula 9. A lubricating grease consisting essentially of an oleaginous liquid lubricating base containing about 5-15 gr m b weight of sodiummypistzityabiozit 54-1 5, ar k ferenc sfimd in he fi Q hi E said oleaginous liquid lubricating base comprising in 5 25 9.

nl by weight: of Copper phthalocyanineg abput..0.5 2 percenf by weight =dfiN,N'diphnyl p phenylenediamine i v[.INI'IED E- t w and about 15 percent by? wcightiof,trictesYlv Phosphate," 2 t Puryeaneji -1 r'-- 195-1 minim prp ztion aniineral oil of lubricating charater- 2 2 Feb: mi 1953 isticsaand in major'proportion'a polyeste'r oilicomprising ,53 5 :Dllwofth 6t 1- --V-' M 1 essentially a compoundof the fbrmula: V 7 OTHER REFERENCES '7 V .LMa 20,;1952]

Claims (1)

1. A LUBRICATING GREASE CONSISTING ESSENTIALLY OF AN OLEAGINOUS LIQUID LUBRICATING BASE THICKENED TO A GREASE CONSISTENCY WITH ABOUT 5 TO 20 PERCENT BY WEIGHT BASED ON THE WEIGHT OF THE COMPOSITION OF SODIUM MYRISTATE AND ABOUT 5 TO 20 PERCENT BY WEIGHT BASED ON THE WEIGHT OF THE COMPOSITION OF COPPER PHTHALOCYANINE.