US2583200A

US2583200A - Nonspreading lubricant

Info

Publication number: US2583200A
Application number: US653124A
Authority: US
Inventors: George E Barker
Original assignee: Elgin National Watch Co
Current assignee: Elgin National Watch Co
Priority date: 1946-03-08
Filing date: 1946-03-08
Publication date: 1952-01-22
Anticipated expiration: 1969-01-22

Description

Patented Jan. 22, 1952 George Barker, Newport Del assignor to Elgin Y i National Watch Company, Elgin lll a corpo ration of Illinois No Drawing. Application March 8', 1946,: I Serial No. 6535124 cant and the parts determine the maintenance of the lubrication film againstthe action of the forces which are tending to bring the parts together. An example of such behavior occurs in "fine instruments su ch as watches, meters, etc., where pivotstaffs turn injewel bearings atlow rates of speed, and in which for accuracy of movement of indication, the frictional resistance must be kept low and substantially uniform.

In my granted Patent 2,355,616 I have described the employment of organic substances as lubricants which are effective under boundary lubrication conditions, and which demonstrate a high contact ang'le'to normal bearing surfaces of fine instruments, that is, while such lubricants are in contact: with brass, steel, ruby, etc. In the said patent'reference has been made to the desirability of employing mixtures of homolog's' in order to keep the solidifying point low, so that the lubricant will be effective down to low temperatures; these homologs'being substances of related properties and each having a'hi'gh contact angle efiect.

It has now been found thatunder' certain restricted conditions it is'feasible to' employ mixtures of such non-spreading lubricants with or- 'ganic compounds which individually are 'of spreading type or which have extremely low contact angles relative to brass, steel, ruby, etc., such contact angles being of the order of degrees or less under ,the conditions of determination and measurements set out in my aforesaid patent. An example of this has been set out in the Barker application Serial No. 547,979 filed August -3, 1944, now U. S. Patent No 2,4 1'2,956, granted December 24,1946; of which'the-present application is a continuation-in-part.

' The effect of such mixtures-of non-spreading and spreading lubricants'is to produce a lubrication medium which hassuperior properties as compared with the individual components, and having in many instances superiority over the corresponding individual values 'fore'ach'of the components.

h i ta onon... emplo ment .0: such spreading diluents for. a non-spreading iubricant is that the'diluentshouldcohsist .0: Organic comi- 10 C aims. 25.2457) .1 1

' poundsor mixtures oi-homologous organic compounds, in which each-compound has two groups of which one is an ester group and the other may be either an esteror an aryl group. The mixture must be substantially free of theflnormal mineral oils} of which a maximum of. up to 5 percent may be tolerated by some such mixed lubricants:

this content or mineral oil must take into account not only the presence of impurities in the lubricant as prepared for use, but also the presence of such mineral" oils by'reason of their employment informing or machining the parts to be lubricated and the possible presence from prior employment as lubricant therebetween. As set out in mygaforesaid patent, it is therefore at least advisable to perform thorough cleaning operations upon the parts before bringing them together in the presence of the nonespreading lubricant. medium. As a corollary, the instant lubricants are clearly and definitely to be distinguished from any employment of additives for modifying or improving the behavior of a mineral oil lubricant.

As a specific. example. of practice, alubricant prepared from partsby weight of benzyl phenylundecanoate, 40 parts of diethylene glycol dicaproate, 05' part -dodecylpiperidine stearate and 0.1 part oftertiary-butyl catechol, has a viscosityicentistokes) of 10.2 at degrees F., and 53.6 at 32 degrees F.;;-a pour point of minus '70 degrees F.; no corrosion on brass or steel; a surface tension-bf 36.0 dynes per centimeter; contact angles of 25 degrees on brass, 21 degrees onrsteel and '23 degrees on ruby; and having an evaporation factor of .Sl percent. (This evaporation factoris the percentage of a 1.0000 gram sample remaining after .100 hours at'lO degrees C., or the. equivalent l58 degrees F., while passing dry nitrogen gasthrough the oil at the rate of cubic foot per hour in a cell which assures essential saturationofthe gas with oil vapor.)

I Byway of comparison, the employed benzyl phenylundecanoateitself has a viscosity of 17.6 ,centistokes at 100 degrees F. and 142.5 at 32 degrees F.; a pour point of minus 40 degrees F.; no corrosion on brass; .a surface. tension of 39.5 dynes per. centimeter; and a contact angle of 19 degrees on steel. 'This'ingredient .is a composition including homologs with a boiling range of to 210 degrees C. at one mm. pressure, wherewith the viscosity may varyfor various specimen butthevalues of.l 'l.0 11017.7 atlOO de rees F. essentially covers the range. Thus, this substance of itself.is a nonspread'ing compound employment of which can be used for boundary lubrication, but has the difllculty of a large change in viscosity and a high minimum pour point (minus 40 degrees F.) which unfit it for employments where a low viscosity-temperature factor and operativeness at minus fio degrees F. or belpw are requisit Dieth'ylen glycol ,dicaproa't. used in the form of ho ni ol'ogs having a bo'iliiig range or 149 to 162 degreesiC. at one mm. Of itself it is a spreading lubricant: the viscosity is around 53 centistokes at 100 degrees-F. and 18.6.9.1; 32.degrees F. Its cloud and pour points are at n inus 2 degrees F. (crystallizationl. eminence it freezes under conditions of airplane service 01- fine instruments. It exhibits no corrosion against brass, and has a surface tension of around 32.9 dynes' per centimeter. 7

It is striking that this mixture exhibited a centact angle efiect against steel, for example, which is .sr a er th nthst any cme qeep r he a th o ems? be ,ii hr ii qeie b' w say, 5 percent or mineral oil lubricantspreads essentially. with'the ss ess'e ast 'e mineral oil itself. It i nsewis'e' strikingthat the; poor point or this" mistin is well pe ow tli pour point of eith o t e n were l bh i e the viscosity shift between 100 degre lli' and 32 der s F. bf ,theor r; 5.: ,wh re e e yl pneny uhdecsn ate m ens has e; factor of around 1:? and. W d h v I p ne t hast mor mu s .2 Thedodecylpiperidirie $tfiaratefisihtroduced to improve a the coeihcient otj='fricti on during service as'. set. at in .nay e a some, sppncan n; Serial q r ed .usnstgfiil lsaawh c e alliyl p'iperidinesalts for such purpose 1se1 a1med.,,,

The tertiary butyl ste m ifrnzzludedv as a stabilizing oranti oxi'dizingage t to ofisetminor tendencies tow v I .taxi'dation35y the re nce of the. ester. groupings in the major ingredients.

Example II p 70 parts by weight of t 'ame benzyl phenylundec'an'oat 30 parts of meth ene glycol divmerate; 9.2 part of tri'is'obutyl phenol and 0.2 part Of st a iri c semi with the 'majsringreaients in the forth o'f 'niixti res of sch mes. provides a non-spreading lubricant Having viscosity of 10.4 centi'stokes at 100 degrees F. and 57,7 ce ritistbkes at 32 degrees F.; a pom-po nt or ini'n'us fiidegrees Fl; no corrosion on biassp'r steel; a su'rface tension 0135.8 dynes "pegce tnneter'; contact'angles of 29 degrees as brass; 9 degrees on steel and 25 degrees on iuby asd an evaporation factor of 69 percent. This material is therefore useful within a lesser min mum a id-maximum temperatui'e 'rauset'han th material or Exempl r, and with a slightly lower sm r ce ,teri sion vsme, a

With respect tothe properties of the' diethyl'ene glycol divalerate cornponent, this ingredient has bdfl s j e or12 -inqesm s t 0- a viscosity of 3.8 centistok'e's at 'l llodegrees Ff, and meat '32 degree n; a; h ur pointer minu 99 degrees 'F.; no corrosion onbilifisi and asurtace a tension o f 31.7 dynes per centimeter. It is n w worthy that the pou pointof this. diester is below that oi the corresponding dicapro ate ester of Exaxn'ple 1, but the mixture oi ingredients does not reveal a corresponding depression of pouripoint.

. mam m eb as a friheflyfteammate... so. i a. or.whn-shenymneec, s

'no'ate, dimes part or 6131c acid; with the "xhajor glycol dicaproate ingredients composed of homologs as before, pro vides a mixture having a viscosity of 12.3 centistokes at 100 degrees F. and 78.5 at 32 degrees F.; and contact angles of 23 degrees on brass, 12 degrees on steel, and 28 degrees on ruby. This composition is illustrative that the benzyl ester is norispreading whilefethe corresponding methyl ester spreads; This methyl ester had a boiling range of 150 degrees to 175 degrees C. at one mm., a viscosity of 9.1 centistokes at 100 degrees F. and. 4.8.5.9215 32 degrees F.; a pour point of minus 70,degrees; .no corrosion on brass or steel; and a surface .teiis'iofi 61,. 35.8 dynes per centimeter. Thisrhethyl este satisfies the specification above in that it two groups including the ester grouping between the methyl alcohol and the phenylundecanoic acid, and the second group is provided by the phenyl radical which is an aryl group.

Example IV 90 partsby weight ofthe saine benz$d phenylundecanoate; parts of benz'yl undecarioate', 0.1 part of tri-isobutyl phenol, and 0.1 part of s'tearic acid, provides'e? mixture in which the major is;- gredients are composed of homologs as before, and has a viscosity of s centistokes at 100 defgrees' F. and 93.5 at 32 degrees F.'; -a pour point or minus degrees F.: no corrosion onbrass or steel: asurface tension oi 38.2 dynesper centimeter: contact angies r 17 degrees on brass, 19 degrees on st'eel and 24 degrees on ruby; and an evaporation factor of 89 percent. 7, V t

In this mixture", the benzyl undecanoate has the ester grouping and also has the aryl group provided by the ben'iiyl radical which n this in stance is on t'lialcoholrather than on the acid side or the ester co'nhection. By comparison, this benzyl ndec'anoate itself is, a spreading lubricant. However, the behavior in the presence of even less than spa e-s a normal miner'alpil lubricant is entirely displaceth'e contact angle behavior so that thesubstituted mixture becomes tr ssi e the pre ence 6 t larg eentage 0f bh'iyl pnenymnaecanoate;

, Example. v 57 pa'rts py weightoi. bienjzyl 'plienylundecano ate, 43 parts oib'enzylthioethyl caproate. 0.5 part of dodeeylpiperidih'e stearate, and 0.1 pa rtof tertiary butyl catechol. provide anon-spreading lubricant aving viscosity. 01.10.; centistokesat 100 degreesE; and 56,4 centist'okes' at 32 degrees F., pompoint minus 60 degrees F., and surface tension ors4.4 dynes/ cm, It causes a slight corrosion onbrass, but is useful for inany emp oy,- mentsavh re lowviscosity, low pour point and low surface tension are desired.

amble v1 v .50 partsby weight of benzylphenylundecancate, 50 parts of thioglycol dicaproate. 05 part f dodecylpiperidine stearate and, 0.1 part, of.v tertiary butyl catecholprovidea non-spreading lubricanthavingviscosityof 10.2 and 51.2 centis'tokes at and 32 degrees. F resp,ectively, ,a cloud point of plus. 40 de'grees F. and a pour point of plus20degreesR,withno corrosion on brass. This productis useful where the exposure temperature is high.

Example VII p6 par s. by wei ht. 10,: ntnz l; uhe yl n cano- We; 3. 2 hl idl'sl cblldi, 2 thii h tyrat l 0:55 p-sr tsr aeieet1nptnaise senate, imam part of tertiary butyl catechol provide a non spreading lubricant having viscosity of 12.9 and 81.0 centistokes respectively at 100 and 32 degrees F., non-corrosive to brass, and having a surface tension of 36.6 dynes/cm.

Ewample VII] 50 parts by weight of benzyl phenylundecanoate, 50 parts of thiodiglycol dihexoate, 0.3 part of dodecylpiperidine stearate, and 0.1 part of tertiary butyl catechol provide a non-spreading lubricant having viscosity of 10.4 and 57.7 centistokes respectively at 100 and 32 degrees F., a pour point of minus 70 degrees F., slight corrosion on brass and steel, and with contact angle of .26 degrees on brass, 16 degrees on steel, and 3 degrees on ruby. In the above examples, the feasibility of employing spreadingtype compounds as diluents and composition-modifiers for non-spreadingtype lubricants has been set out by employing Example IX 50 parts by weight of benzyl phenylvalerat e, 50 parts of benzyl thioethyl undecanoate, 0.2 part of triisobutyl phenol, and 0.1 part of stearic acid provide a lubricant having viscosity of 9.1 and 51.8 centistokes respectively at 100 and 32 degrees F., a pour point of minus 50 degrees F., low cor- .rosion on brass (the actual corrosion being probably due to impurity in specific sample tested),

surface tension'38.4 dynes/cm., and which was non-spreading V on brass (contact angle 31 degrees) and ruby (contact angle 21 degrees), and exhibiting for the samples tested a contact angle of 9 degrees on steel.

Ewample X 50 parts by weight of benzyl phenylvalerate, 50 partsof methyl phenylundecanoate, and 0.1 part stearic acid provide a non-spreading lubricant acceptable for service on brass, steel and ruby.

Example XI 50 parts by weight of phenoxyphenyl cetan'e, 50 parts of trimethylene glycol dioctoate, 0.1 part tertiary butyl catechol, and 0.1 part stearic acid provide a non-spreading lubricant having a pour point of minus 60 degrees F., and being non-corrosive to brass.

Example xii 70parts by weight of phenoxyphenyl cetane. 30 parts of trimethylene glycol dihexoate, 01 part tertiary butyl catechol and 0.1 part stearic acid, also provide an acceptable non-spreading lubricant. v I

In the above examples, the corrosion test was performed by submerging a carefully cleaned and bright instrument brass block 2.5 x 1 x 1 centimeters in'size and having an area of 12 square centimeterazin about cubic centimeters of the 8 oil in'a glass vessel: the temperature was maintained at 100 degrees C. for 100 hours while passing oxygen gas saturated with water vapor at 3 bubbles per. second (0.2 cubic feet per hour) at the end of test, the lubricant was examined for change of viscosity and appearance, and the surface of the brass block was examined for pitting or other evidence of corrosion and weighed after removing the. oil. The viscosity change was not over 5 percent, and the weight loss of--the brass block was not over 1 milligram for the products accepted as non-corrosive": surface staining without essential change of weight occurred in some instances. A second test for corrosion on steel is made by half-immersing a high-grade cleaned steel bearing ballina 20 cc. bcalger containing the lubricant, the beaker being thenrkept in a sealed vessel containing water to maintain a saturated atmosphere, at room'temperature, for a period of several months: satisfactory"ilubricants resist this test for 5 or 6 months. A third test for corrosion on steel is conducted by immersing such a steel ball in the lubricant at 65'; degrees C. for one hour; then adding distilled water to displace the main body of oil and leave the ball immersed in thewater; and then holding jthe ball so immersed until more than 10 percent of the surface is covered with rust: a satisfactory lubricant must resist for at least 2 days. -:(By comparison, r'nost uninhibited mineral oils of highly refined types fail in a few hours under this test: some even in a few minutes) y The illustrative mixtures of materials can be defined as being non-volatile compositions including a non-spreading or (A), lubricant ingredient consisting essentiallyoff stable polar 'aralkyl molecules, each comprisii'ifgfan alkyl chain and a nuclear'aromatic radical connected to said chain and including-a strong non-anionic negative group, the ingredient demonstrating a positive contact angle with a steelsuiface in excess of 10 degrees and having surface tension of at least dynes per centimeter; the alkyl chain comprising 5 to 21 carbon atoms when a single aromatic nucleus is present, and comprising 3 to 21" carbon atoms when there are a plurality of aromatic nuclei in the molecule. The spreading-typediluent-or (B) component employed was illustratively selected from stable organic compounds which contain at least two polar groups, of which one is the ester group, and another is either a second ester group or an aryl group; so that they may be referred to as having esterester or diester connections or ester-aryl connections, with feasibility of employing complexes of aryl-thio ether-ester or similar types. It is "preferred to have this (B) component in the form of a stable non-volatile organic compound including the said connection and having a saturated aliphatic chain of 4 to 16 carbon atoms, either without substitutions or side groups or including oxygen 01 sulfur atoms as other or ester bonds in'the chain or a side group. Thus, some of the illustrative (B) component are glycols having'di-ester connections to monovalent acids,

"and others are mono-esters which include an aryl nucleus.

Itisusual, as shown by the above examples, to employ to parts by weight of the nonspreading or (A) component, with 50 to 10 parts of the spreading component.

7 Each of thesemajor constituents or ingredients 'is preferably present, in the form of a mixture of homologsso that theboiling point 01' the mix- "'ture appears'as a range of temperature within attract which these siiniiar-compdundscome'over during distillation. 1 It is p'refe'r'redto include small-percentages (not exceeding substantially 1 percent in all) of modiiying agent to improve the 'oiliness; the co'elilcient of friction, ;'etc.-; but care must be taken to avoid the presence during the-service of the lubricant of such an amount ofmineral oil lubricant. as to modify the behavior of the mixture or in itseli to perform lubricating service: this content-must never exceed 5- percent and should be kept as low aspss1o1e,- andhence the compositions can be described as essentially free ofimineral oil". A.

It is obvious that the. invention is not limited to theformsoipractice described, but that the same may be employed-in many ways within-the scope of the appende'dclaims.

" Iclaim: i

1. A non-spreading lubricant having a base consisting of 50 to QOparts'by weight of a noni spreading component and 50.150 10 parts of a spreading component, said components being compatible andintersoluble 'in one another; said non-spreading component, consisting of a liquid homologous mixture of stable non-volatile polar aralkyl compounds each having an alkyl chain and a nuclear aromatic radical connected to said chain and includingiastrong non-anionic negative group, demonstrating a positive contact angle with a steel surface in excess of 10 degrees and havinga surface tension of at least 35 dynes per centimeter, the alkyl chain having from about -to-21 carbon atoms,= said spreading component consisting of a liquid mixture of stable non-volatile organic compounds each containing "a saturated aliphatic chain of-.-4 to '16 carbon atoms and at least two polar groups, of which one is the ester group and another is selected from the radicals consisting ofthe ester group and the aryl groups; said lubricant being further character'- ized in containing less than 5 per cent of mineral .oil lubricant and for'the remainder consisting of not exceeding 1 per' cent of modifying agents to improve oiliness and coefficient of friction.

2. A non-spreading lubricant having a base consisting of-50 to 90 parts by weight'of a non"- spreading, component and 50 to parts of a spreading component, said components being compatible and intersoluble in one another; said non-spreading component consisting of a liquid i homologous mixture of stable non-volatile "polar aralkyl compounds each-having an alkyl chain and-a nuclear aromaticradica-l connected to-said chain and including a strong non-anionic negative group,said non-spreading componentdemonstrating a positive contact angle with a steel surface in excessrof 10 degrees andhaving a surface tension of at least. dynes per centimeter, the alkyl chain having from about '5 to 21 carbon atoms; said spreading component consisting of liquid homologous mixture of stablenon-volatile: organic compounds each containing saturated aliphatic chains of 4 to 16 carbon atoms and atleast, two polar groups; of which one is the ester group and another is selected from the radicals consistingor the ester group and the aryl groups; said lubricant being further characterized in containingless than 5 percent of mineral oil lubricant andfor the remainder'consisting of-not exceeding -1- per cent of modifying agents to improve oilinessand coeflicient orfriction.-. 7

'3. A non spreading; lubricant having a base consisting of to; 90 parts by weight of a non.- spre ng, complimen and 5.0-, to 1 parts of i s ll 8 spreading com onent." sajiii components be ng compatible and intersoluble in one another; said non-spreading component consisting of-a liquid homologous mixture of stable nonfvolatile polar aralkyl compounds eachbei'ng the ester of an aralkyl alcohol and an aralkyl acid and having an alkylchain and a nuclear aromatic radical connected to Said chain and including a strong non-anionic negative group, said non spreadin g component demonstrating a positive'contact angle with-"a. steel surface in excess of 10 degrees and having a surface tension of 'atleast 35 dynes per centimeter, the alkyl chain having from about to 21 carbonatoms; said spreading component consisting of a liquid homologou mixture of stable non-volatile organic compounds each fc'on taining a saturated aliphatic chain of 4 to 16 carbon atoms and at least tw'o polar groups of which twoare ester groups;'said lubricant being further characterized in containing less than 5 percent of mineral oilIubricant and for the remainder consisting of not exceeding 1 per cent of modifying 'agents to improve oilines and coefficient of friction. 7 I

4;. A non-spreading lubricant h'avinga base consisting of-56' to parts by Weight of a nonspreading component and 50 to '10 parts of a spreading component; said components being compatible and intersoluble in one another; said non-spreading component consisting of a liquid homologous-mixture of stable non-volatile polar 'aral-kyi compounds each being the ester of an aralkyl alcohol and anaralkyl acid having "an alkyl chain and a nuclear aromatic radical connected to said chain, said non-spreading component demonstrating a positive contact angle with a steel surface in excess of 10 degrees and having a surface tension of at least 35 dynes percentimeter; the alkyl chain having from about 5 to 21 carbon atoms; said spreading component consisting of a liquid homologous mixture of stable non-volatile organic compounds each containing a'sa'turated aliphatic chain of 4 to 16 carbon-atoms and at least two polar groups of which two'are ester groups; said lubricant being further characterized in containing less than 5flper centof mineral oil lubricant and for "the remainder consisting of not exceeding '1 per cent of modifying agents to improve oiliness and coeificient of friction. v

5. A non-spreading lubricant as in claim 1, in which the non-spreading component mixture consists of aralkyl alcohol esters of aralkyl acids, said acids each having an alkyl chain of at least 3 carbon atoms; 'andin which'the spreading component mixture consists of diesters of a glycol with monovalent saturated organic acid groups having said saturated aliphatic chain of 4*to'16 carbonatoms. 7

6 A non-spreading lubricant as in claim '1, having a pour point below minus 50 degrees F., in which the non-spreading component mixture consists of 50 to '70 parts by weight of benzyl phenylundecanoate; and the spreading component mixture consists of 30-t0 50 parts of stable organic glycol diesters having the said saturated aliphaticcarbon-chain of 4 to 16 carbon atoms.

'7. A non-spreading lubricant as in claim -1, in which the non-spreading component mixture consists of 50 to 70 parts by weight of benzyl phenylundecanoate; and. the spreading com- :ponent mixture consists of 30 to 50 parts by weight of dieste'rs'of a glycol with an aliphatic 8. A non-spreading lubricant as in claim 1, in which the non-spreading component mixture consists of benzyl phenylundecanoate; and the spreading component mixture consists of benzyl undecanoate.

9. A non-spreading lubricant as in claim 1, in which the non-spreading component mixture consists of aralkyl alcohol esters of aralkyl acids, said acids each having an alkyl chain of at least 3 carbon atoms; and said spreading component 10 mixture consists of thioglycol diesters of saturated aliphatic acids each having at least 3 carbon atoms.

10. A non-spreading lubricant consisting essentially of 50 to 70 parts by weight of benzyl 15 10 phenylundecanoate and 30 to 50 parts of diethyl ene glycol dicaproate.

GEORGE E. BARKER.

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

UNITED STATES PATENTS Number Name Date 2,179,067 Smith Nov. '7, 1939 2,241,531 Wiezevich May 13, 1941 2,355,616 Barker Aug. 15, 1944 2,409,443 Morgan et a1 Oct. 15, 1946

Claims

1. A NON-SPREADING LUBRICANT HAVING A BASE CONSISTING OF 50 TO 90 PARTS BY WEIGHT OF A NONSPREADING COMPONENT AND 50 TO 10 PARTS OF A SPREADING COMPONENT, SAID COMPONENTS BEING COMPATIBLE AND INTERSOLUBLE IN ONE ANOTHER; SAID NON-SPREADING COMPONENT CONSISTING OF A LIQUID HOMOLOGOUS MIXTURE OF STABLE NON-VOLATILE POLAR ARALKYL COMPOUNDS EACH HAVING AN ALKYL CHAIN AND A NUCLEAR AROMATIC RADICAL CONNECTED TO SAID CHAIN AND INCLUDING A STRONG NON-ANIONIC NEGATIVE GROUP, DEMONSTRATING A POSITIVE CONTACT ANGLE WITH A STEEL SURFACE IN EXCESS OF 10 DEGREES AND HAVING A SURFACE TENSION OF AT LEAST 35 DYNES PER CENTIMETER, THE ALKYL CHAIN HAVING FROM ABOUT 5 TO 21 CARBON ATOMS, SAID SPREADING COMPONENT CONSISTING OF A LIQUID MIXTURE OF STABLE NON-VOLATILE ORGANIC COMPOUNDS EACH CONTAINING A SATURATED ALIPHATIC CHAIN OF 4 TO 16 CARBON ATOMS AND AT LEAST TWO POLAR GROUPS, OF WHICH ONE IS THE ESTER GROUP AND ANOTHER IS SELECTED FROM THE RADICALS CONSISTING OF THE ESTER GROUP AND THE ARYL GROUPS; SAID LUBRICANT BEING FURTHER CHARACTERIZED IN CONTAINING LESS THAN 5 PER CENT OF MINERAL OIL LUBRICANT AND FOR THE REMAINDER CONSISTING OF NOT EXCEEDING 1 PER CENT OF MODIFYING AGENTS TO IMPROVE OILINESS AND COEFFICIENT OF FRICTION.