US2551931A

US2551931A - Polysiloxane grease and method of preparation

Info

Publication number: US2551931A
Application number: US51861A
Authority: US
Inventors: Chester C Currie
Original assignee: Dow Corning Corp
Current assignee: Dow Silicones Corp
Priority date: 1948-09-29
Filing date: 1948-09-29
Publication date: 1951-05-08
Anticipated expiration: 1968-05-08
Also published as: DE850048C; GB666360A

Description

Patented May 8, 19 51 UNITED STATES PATENT OFFICE POLYSILOXANE GREASE AND METHOD OF PREPARATION Chester 0. Currie, lvllidland, Mich, assignor to Dom-Corning Gorporation Midland, Mi cl 1.,,a--.

corporation of; Michigan No Drawing; Application September-29; 1948';- Serial No 51,861

8 Clahns.

from polysiloxanes and; salts ofalicyelic: sub: stituted fatty acids.

2'. the siliconatoms may be. variously substituted. with .the; indicated; organic. radicals. Preferably each silicon. atomhas-fromone. to three of. the herein definectorganic radicals. attached thereto.

The lubrication ofimovingparts whichgoperate The. proportions: of the; variously. substituted a-t-high or low; temperatures has always presented silicon atoms. shouldlbe; such that therev is. an. difiicult or-insoluble problems, With,- conyenaverage of from 1.9 to 2.5 organic radicalsperz tionalhydroearbonoilszandgreases the tempera: silicon. The viscosity; of, the. siloxanev polymer ture at which effective lubrication; may be used to..prep are thecgreaseeis;innozway critical. obtained is limited. by the inherent thermal W The above siloxanes;mayrbeprepared by any. instability of those compounds. Greases preappropriate method: Methods-known'to;therart pared from polysiloxanes and lithium stearate include hydrolysis or corhydrolysis. of the: correpresent an improvement over the organic responding hydrolyzable-silanes, catalytic 001-1 es r high temperatu v lubriation, t polymerization ofthe desiredsiloxanes and. the they too have several undesirable proper reaction ofsilicon-halides with alkali, metal salts.

It is an object of this invention to produce. a of organo silanols. h at sta n nrr siv r a which Will The additivesused tothickenthepolysiloxane serve as a Supe lubricant for Operating 3 fluids. to. produce theereasesoflthisinvention y h or low temperatures. Other objec are. salts of alicyclic, substituted,= fatty acids. and. advantages Will appeal from following wherein-the fatty acidlchain is=from 2:to.6 carbonv c p atoms in length. Such acids. include for ex- This invention r to e v lg ample, cycloparafiin derivatives of straightchain a liquid Organo' polysuoxane m h t fatty acids; sue-h a-s cyclohexylacetio, cyclol-iexyl 9 are p phenyl"or q butyricandcyclopentylyalerie; allgyl substituted sald slloxane havmg gt ff g cycloparafiim derivates-of fatty acids, such as 4 alicyclic substituted fatty acid, which fatty acid butylcycllhexylbllinci P f ghasa chain lengthofirom 2.110. Scarbonatoms. fatty fields, w ms-' ql e e s a w, an 7 The metals of the salts. are alkali metals or y ycllc Substituted. fatty acids such as alkaline earth metals. These greaseshave desirp a1a acet1c-- able lubricating. properties. In order thatthis invention maybe better The 'siloxanesfrom, which the greases oithis' understood, the formulae of some of. the acids invention are. prepared, are polymers composed which may be. employed therein are. given. in of alternate silicon and oxygenatoms. wherein 36 Table I.

TABLET H-"J 32. H c Alpha 4 diterbutylcyclohexyl- L bummomomcrro 0 OH Alpha- 4 disecbutylcyclohexyl- H 0 1 omongt'no Q Q11 1 TABLE IContinued by any appropriate method. For example, the

salt may be dispersed in the siloxane by dissolving both in a common solvent and then evaporating the latter, or the salt may be introduced directly into the siloxane and dissolved by heating and agitating the mixture, or the salt may be formed in situ by adding an aqueous solution of the metal hydroxide to a solution of the acid in the siloxane.

A preferred method of preparing the greases is to add an aqueous solution of the metal hydroxide to a solution of the acid in an equal weight of siloxane. The addition is preferably carried out at a temperature of about 80 C. The water is evaporated by heating at 100 C. and more siloxane is added to the residue. The

- product is then heated at a temperature up to 200 C., cooled and milled.

In the preparation of the grease, the amount of alkali added may be less than enough to. neutralize the acid or it may be in amount equivalent to the acid or it may be in amount in excess of that required to react with the acid. Thus, the grease may be either acidic, neutral, or alkaline in character. It is preferred however, that the grease be alkaline with an alkaline number of at least 5. The alkaline number is determined by titrating a one gram sample of the material with standard acid and calculating the milligrams of KOH which are equivalent to the acid necessary to neutralize the sample. The number is always expressed in milligrams of potassium hydroxide regardless of the type of alkali present in the grease.

The greases of this invention are extremely stable at both high and low temperatures. They possess melting points in excess of 600 F. and exhibit a bleed of less than 1% when heated in a standard A. N. G.5 test apparatus at 150 C. for 24 hours. Bearings lubricated with the products have been operated in excess of 2,000 hours erratic in their behavior in use. By contrast the present greases give reproducible results.

Consisting essentially of as used in the claims means that the composition is made up almost entirely of the ingredients recited and these ingredients are the main and characterizing ones, but this expression does not exclude the presence of minor amounts of other ingredients which are commonly employed in lubricating compositions or which are merely inert. Such added ingredients would not change the essential character of the composition.

In order that those skilled in the art may better understand this invention, recourse may be had to the following examples which should be considered only asillustrative thereof.

this run was composed of phenylmethylsiloxane' units, dimethylsiloxane units and trimethylsiloxane units. was such that the degree of substitution of the copolymer was between 2 and 2.1 organic radicals per silicon atom. A solution of 5 g. of LiOH.H2O in 20 g. of water was added with agitation to a solution of cyclohexylcaproic acid in 20 g. of a 100 c. s. phenylmethylpolysiloxane of the above composition. The addition of the hydroxide solution was carried out at a temperature of 80 C. After all the hydroxide had been added the temperature was raised to 100 C.

to evaporate the water. g. more of the phenylmethylsiloxane was added with stirring to the residue Which was being maintained at a temperature between 100 and 120 C. The material was then heated at a temperature of about 200 C. for one hour, cooled and then milled on a three-roll mill. The grease so obtained melted above 315 C. and had an alkaline number of 8.96. This grease underwent no change after at a speed of 1750 revolutionsper minute and a temperature of 175 C. without showing any signs of failure. Samples of the material have been heated at 200 C. for'24 hours without showing any change.

The stability of the products herein defined are vastly superior as high-temperature lubricants to organic greases. They are also markedly superior to greases prepared from 1101 1 110 anes thickened with lithium stearate. The latter carbonize at substantially lower temperatures and break down more readily, as shown by change in consistency when workedat elevated temperatures, than do the present greases. Eurthermore, lithium stearate siloxane greases are 24 hours heating at 200 C.

Example 2 A solution of 100 g. of cyclohexylcaproic acid and 100 g. of the 100 c. s. phenylmethylpolysiloxane fluid of Example 1 was heated to C. The solution was agitated during the addition of 25.4 g. of LiOH.H2O in 120 g. of water. When the addition of the hydroxide solution was complete the temperature was raised to C. to evaporate the water. The residue was maintained at 100 to C. and agitated during the'slow addition of 300 g. more of the phenylmethylpolysiloxane. After addition of the siloxane was complete, the mixture was heated to about 200 C. for one hour and allowed to cool.

. The resulting product was milled on a three-roll mill and the grease so obtained had a melting point greater than 600 F. with an alkaline num- The amount of trimethylsiloxane.

assnes i her of "13.95. The grease wasipla'eed :in a standand apparatus described in A. N. G.5 and heated at1150 C. for 24 hours. The results were as follows: A bleed of 0.68 percent and-a volatility of 1i60 percent. A bearing lubricated with this grease and operated at 1750 R. P. M. with no "load at a temperature at 175 C, was still functioning after 1,666 hours.

Example 3 The procedure of Example 1 was employed tov prepare greases -using the Li salts of the acids shown in Table II.

Example 4 TA suspension of 121 g. of Ba(OI-I) 28H20' in 200 g. of water was added with stirring to 100 g. of cyclohexylcaproic acid. The salt solution thus formed was heated to partially evaporate the water. A thick mass resulted to which 200 g, of the.phenylmethylpolysiloxane of Example 1 was added'slowly with stirring at about 100 C. When the addition was complete the temperature was raised-gradually to 230 C. The resulting material was then cooled to room temperature and milled on a three roll mill. The milled product was a grease having a melting point 600 F. and an alkaline number of 44. This grease did not bleed after 16 hours at 150 C. and its volatility loss was 1.09 percent. The grease was essentially unchanged after heating 175 hours at 175 C.

Example 5 The solution of 20 g. of cyclohexylcaproic acid and 20 g. of the phenylmethylpolysiloxane of Example 1, a solution of 4.2 ga of NaOH and 20 g. of water was added slowly with stirring. During the addition of the hydroxide solutionthe mixture was maintained at atemperature of 80 C. After all the hydroxide had been added the temperature was raised to 100 C. to evaporatethe water. The resulting residue was heated at 100 to. 120 C. as 40 g. more of the phenylmethylpolysiloxane was gradually added. The material was then heated at about 200 C. for one hour. After cooling the resulting material was milled on'a three-roll mill to produce a grease.

Example 6 cool. The resulting material was milled to pro ,duce agrease.

Example 7 A20 g. :sampleof cyclohexylcaproic acid was neutralized with aqueous KOH. The resulting solution was maintained at a temperature of 100 C. and ag'itated as 20 g. of the phenylmethyl- -polysiloxanefluid of Example 1 was slowly added. Thetemperature was kept at 100 C. until the water evaporated. To the residue 60 g. of the p'henylmethylpolysiloxane was added slowly with stirring at a temperature ofabout 120 C. The mixture was further heated to give a clear product which was then cooled and milled to produce a grease.

Example 8 A solution of 4.4 g. of LiOH.H2O and 20 g. of water was added slowly with stirring at a temperature of C. to a solution of 20 g. of cyclohexylcaproic acid and 20 g. of 100 c. s. dimethylpolysiloxane fluid. The temperature wa then raised to 100 C. to remove the water. The resulting mass was heated to 120 C. and 40 g. of the dimethylpolysiloxane fluid was slowly added. The product was heated at 200 C. for one hour, cooled, and milled on a three-roll mill to produce a grease.

Ezrample'9 A solution of 10g. of cyclohexylcaproic acid and 10 g. of tolylmethylpolysiloxane of 7,000 c. s. viscosity was heated to 60 C. and agitated during addition of a solution of 2.1 g. of LiOH.H2O and 15 g. of water. The temperature was raised to 100 C. to remove the water. The residue was maintained .at a temperature of 120 C. during addition of 20 g. of the tolylmethylpolysiloxane. The resulting mixture was heated at 100 C. for one hour, cooled, and milled to produce a semiclear grease.

Example 10 A solution comprising 100 g. of eyclohexylcaproic acid and 100 g. of a 500 c. s. polysiloxane having'the composition of mol percent phenylmethylsiloxane and 10 mol percent trimethylsiloxane, was prepared. To this solution 25.4 g. of LiOH.HzO in 120 g. of water was added slowly withstirring at a temperature of 180 C. The mixture was then heated at C. to evaporate the water. The residue was maintained at about C. as 300 g. of the copolymeric siloxane was slowly added. The resulting material was heated at 200 C. for one hour, cooled, and milled on a three-roll mill to produce a grease having an alkaline number of 12.15. This grease showed a weight loss of 0.67 percent after 24 hours at C.

Example 11 Asolution of 2.5 g. of LiOH.H2O in 20 g. of water was-added to a solution of 10 g. of cyclohexylcaproicaacid and 10 g. of the phenylmethylpolysiloxane fluid of'Example 1,with agitation. During the addition of the hydroxide solution the temperature was maintained at 80 C. After all the lithium hydroxide was added the water was evaporated at 100 C. The residue was then heated to 120 C. as 70 g. of the phenylmethylsiloxane was slowly added with stirring. The material was then heated at C. for one hour and allowed to cool. The resulting product was milled on a three-roll mill to produce a thin grease. This grease contained 10 percent by weight of the lithium salt of cyclohexylcaproic acid based on the weight of the grease.

Example 12 evaporated at a temperature of 100 C. The residue was heated at 120 C. and agitated as 46 g. of the phenylmethylpolysiloxane fluid was slowly added. The resulting product was heated at 200 C. for one hour and then cooled. Upon milling on a three-roll mill a thick grease resulted. This material contained 35 percent by weight of the lithium salt of cyclohexylcaproic acid based on .the weight of the grease.

The greases described in the above examples performed satisfactorily in the lubrication of bearings.

That which is claimed is: 1. A grease consisting essentially of a liquid organo polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals per silicon atom, said radicals being selected from the group consisting of methyl, phenyl, and tolyl radicals and a minor amount of a metallic salt of an alicyclic substituted fatty acid in which fatty acid the chain length is from 2 to 6 carbon atoms, the metal of said salt being selected from the group consisting of alkali metals and alkaline earth metals, said salt being present in amount suflicient to form a grease.

2. A grease having an alkaline number of at least 5, said grease consisting essentially of a liquid organo polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals per silicon atom, said radicals being selected from the group consisting of methyl, phenyl, and tolyl radicals and a minor amount of a metallic salt of an alicyclic substituted fatty acid in which fatty acid the chain length is from 2 to 6 carbon atoms, the metal of said salt being selected from the group consisting of alkali metals and alkaline earth metals, said salt being present in amount sufficient to form a grease.

3. A grease consisting essentially of a liquid organo polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals .per silicon atom, said radicals being selected from the group consisting of methyl, phenyl, and tolyl radicals and a minor amount of a barium salt of an alicyclic substituted fatty acid in which fatty acid the chain length is from 2 to 6 carbon atoms, said salt being present in amount sufiicient to form a grease.

4. A grease having an alkaline number of at least 5, said grease consisting essentially of a liquid organo polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals per silicon atom, said radicals being selected from the group consisting of methyl, phenyl, and tolyl radicals and a minor amount of a barium salt of an alicyclic substituted fatty acid in which fat= ty acid the chain length is from 2 to 6 carbon atoms, said salt being present in amount sufficient to form a grease.

5. A grease consisting essentially of a liquid organo polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals per silicon atom, said radicals being selected from the group consisting of methyl, phenyl, and tolyl radicals and a minor amount of a lithium salt of an alicyclic substituted fatty acid in which fatty acid the chain length is from 2 to 6 carbon atoms, said salt being present in amount suflicient to form a grease.

6. A grease having an alkaline number of at least 5, said grease consisting essentially of a liquid organo polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals per silicon atom, said radicals being selected from the group consisting of methyl, phenyl, and tolyl radicals and a minor amount of a lithium salt of an alicyclic substituted fatty acid in which fatty acid the chain length is from 2 to 6 carbon atoms, said salt being present in amount suflicient to form a grease.

7. A grease having an alkaline number of at least 5, said grease consisting essentially of a liquid polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals per silicon atom in which siloxane the organic radicals are phenyl and methyl radicals and a minor amount of a lithium salt of an alicyclic substituted fatty acid in which fatty acid the chain length is from 2 to 6 carbon atoms, salt being present in amount suliicient to form a grease.

8. A grease having an alkaline number of at least 5, said grease consisting essentially of a liquid polysiloxane having a degree of substitution of from 1.9 to 2.5 organic radicals per silicon atom in which polysiloxane the organic radicals are tolyl and methyl radicals and a minor amount of a lithium salt of an alicyclic substituted fatty acid in which fatty acid the chain length is from 2 to 6 carbon atoms, salt being present in amount sufficient to form a grease.

CHESTER C. CURRIE.

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

UNITED STATES PATENTS Number Name Date 2,055,795 Kaufman Sept. 29, 1936 2,379,245 Morway June 26, 1945 2,409,950 Meyer Oct. 22, 1946 2,446,177 Hain Aug. 3, 1948 2,456,642 Merker Dec. 21, 1948 OTHER REFERENCES Chemical Constituents of Petroleum, by Sachanen, Reinhold Pub. Co., 1945, pages 323 and 324.

Claims

1. A GREASE CONSISTING ESSENTIALLY OF A LIQUID ORGANO POLYSILOXANE HAVING A DEGREE OF SUBSTITUTION OF FROM 1.9 TO 2.5 ORGANIC RADICALS PER SILICON ATOM, SAID RADICALS BEING SELECTED FROM THE GROUP CONSISTING OF METHYL, PHENYL, AND TOLYL RADICALS AND A MINOR AMOUNT OF A METALLIC SALT OF AN ALICYCLIC SUBSTITUTED FATTY ACID IN WHICH FATTY ACID THE CHAIN LENGHT IS FROM 2 TO 6 CARBON ATOMS, THE METAL OF SAID SALT BEING SELECTED FROM THE GROUP CONSISTING OF ALKALI METALS AND ALKALINE EARTH METALS, SAID SALT BEING PRESENT IN AMOUNT SUFFICIENT TO FORM A GREASE.