US2088452A

US2088452A - High temperature lubricant and process of preparation

Info

Publication number: US2088452A
Application number: US30637A
Authority: US
Inventors: Irving R Valentine
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1935-07-10
Filing date: 1935-07-10
Publication date: 1937-07-27
Anticipated expiration: 1954-07-27
Also published as: DE700289C; FR808046A

Description

Patented July 27, 1937 UNITED STATES 2,088,452 PATENT OFFICE.

HIGH TEMPERATURE LUBRICANT AND PROCESS OF PREPARATION Irving R. Valentine, Erie, Pa., assignor to General Electric Company, a corporation of New York No Drawing. Application July 10, 1935, Serial No. 30,637

8 Claims.

The present invention relates to lubricants and process of preparing the same, and refers more both heat and pressure.

Y Heretofore lubricating greases have. been prepared by compounding mineral oil and a soap such as sodium stearate, sodium oleate and sodium palmitate at low temperatures. The soap was compounded in the presence of water, and a small percentage of water remained inthe final grease composition. In such a grease the soap holds the oil as a sponge. When subjected to heat, as is frequently encountered in service, the grease decomposes and changes from a neutral or slightly alkaline composition to one having distinctly acid characteristics. In.the decomposition process, the soap is destroyed causing an ultimate breakdown of the grease. It appears that hydrolysis due to the presence of water in the grease contributes materially to its instability.

The improved grease compositions embodying my present invention employ, inplace of water, analkyl ether of diethylene glycol, such as, the monoethyl ether of diethylene glycol. The alkyl ethers of diethylene glycol act as a vehicle ior uniting the alkali and fat, or fatty acid in the production of the soap constituent of the grease and apparently to some extent combine with these reacting ingredients. The anhydrous soap composition thus formed, which contains a minor proportion of an alkyl ether of diethylene glycol, or a derivative thereof, is compounded with a suitable mineral lubricating oil.-

While various glyceride fats or oil, or fatty acids derived therefrom, or other saponifiable hydrocarbon, may be used in the formationof the soap constituent, I prefer to employ a mixture of drying, semi-drying and non-drying oils, the semi-drying oilvpreponderating over the other oils. For example, with about one to ten parts of drying oil, and a similar proportion of non-.

drying oil, I employ ten to fifty parts of a semidrying oil, such as soya bean oil.

A preferred process of preparing the lubricating grease is-as follows: a mixture consisting of 3 parts sodium hydroxide, 10 parts monoethyl ether of diethylene glycol, and a vegetable oil mixture consisting of 2 parts castor oil, 3 parts tung oil, 2 parts raw linseed oil and 10 parts soya bean oil is heated gradually to 280 C. The latter threeoils have drying properties. The sodium hydroxide goes into solution at about 180 to 200 C. and a soap is formed when the temperature of the mixture rises to the range between approximately 260 and 280 C.

My invention includes the employment ofother alkyl ethers of diethylene glycol, such, for example, as the methyl or butyl ethers in place of the ethyl ether of diethylene glycol.

The monoethyl ether of diethylene glycol,

which has a boiling point within a range of about 185 to 205 C., is largely evaporated during this heating step but a small amount still remains in the composition either in its original state or else modified by chemical reaction. -In any event the residue remaining is capable of acting as a bonding agent whereby such soap composition can be united or emulsified with mineral oil. Relatively large quantities of oil thus can be held as a stable emulsion which does not break down during severe use.

The mixture containing a small amount of an alkyl ether of diethylene glycol and in addition some glycerine which is formed during saponification, is allowed to cool to approximately room temperature and thereupon the desired form of mineral oil is added.- For example, for heavy ball bearing grease, medium heavy oil of 10? F. cold test can be used. For special purposes requiring the greaseto remain plastic at low temperatures, lighter oil having a cold test of minus 40 F. may be necessary. In general the conditions under which the lubricating grease is to be used will determine the character of the oil embodied in it. This oil and soap mixture in which mineral oil may constitute to per cent of the total mass is heated to a temperature within the range of about 200 to 220 C.,until a clear solution is obtained. It is allowed to cool with constant stirring until the mixture thickens. If insoluble particles, such as overcooked soap particles are present, they are removed by filtration while the solution is hot and unthickened.

In some cases, a fatty acid such'as 'stearic acid may be incorporated with the other ingredients. For example, a mixture consisting of 30 parts sodium hydroxide, parts monoethyl ether of diethylene glycol, 105 parts stearic acid, and a vegetable oil mixture consisting of 4 parts castor oil, 6 parts tung oil, 4 parts raw linseed oil and 26 parts soya bean oil is heated gradually to 280 C. The sodium hydroxide goes into solution at about 180 to 200 C. and the soap is formed when the temperature of the mixture is between approximately 260- and 280 C. The resulting anhydrous soap product which contains a small amount of monoethyl ether of diethylene glycol, some glycerine and perhaps other decomposition products is compounded with a chosen mineral oil as already described.

The grease made in accordance with my invention is extremely stable and is particularly adapted for high temperature and high pressure For example, a grease composed of 1 part (12.5%)

soap prepared in accordance with the preferred p s and part 1 '7.5%) heavy medium min-.

era] lubricating oil had :the following characteristics: a

Before heat Alter heat treatment treatment for 90 hours at 126 C.

10 Melting point 136" 0. 135 0. Free N aOH. 193% 13% The addition or the high boiling dispersing agent, such as the monoethyl ether of diethylene 5 glycol, performs at least two functions. First,

.it allows the alkali to go into solution at low temperature previous to the formation of the soap, and secondly, while much of the alkyl ether of diethylene glycol is evaporated during the gradual temperature .rise, themixture still retains a small amount in a somewhat difierent form that acts-as -a binding agent between the a mineral oil and soap. If an alkyl ether of diethylene' glycol is not used, the soap is only capable of holding a small quantity of mineral oil,

the excess oilseparating as the temperature rises and the lubricating properties of the grease thus being destroyed. However,'when' analkyl ether of diethylene'glycol is used and a smallamount of an alkyl ether of diethylene glycol or derivative thereof remains as a bonding agent after the I of the dispersing agent should remain in the mixture after the formation of the soap. The alkyl ethers of diethylene-glycol or the likelost by evaporation may be reclaimed by condensa- J tion and usedagain.

Although I have illustrated my'preferred lu-' bricating grease employing certain materials, my invention is not limited to the specific-ingredients previously disclosed' Other alkalis' or mixtures of the same may be used in place of sodium hydroxide, such as potassium hydroxide, calcium hydroxide and the like. However, as is well known to the art, the physical properties or a grease, and its practical utility for a particular condition of lubrication, are dependent, among'- other influencing factors, upon the particular al-' -kali or alkalis used in making the soap. As is commonly known, a grease containing a sodium soap of a particular fatty oil has a. higher melting point than a greasecontaining a calcium soap, or a mixture of calcium and sodium soaps of the same fatty oil. dlti'ons of lubrication'and for which a heat-resisting lubricant is required, greases containing sodi.-

- um soaps are therefore preferred. Varlousdry ing, semi-drying and now-drying vegetable oils may also be employed. Where extreme pressure lubricants 'are desired the drying oils may be readily chlorinated or sulphurized.

herein are by weight.

All modifications obvious to those skilled in the art and coming within the true spirit and scope of my invention are meant to be covered in 75 the claims appended hereto.

The boiling point of the dispersing agent use For high temperature con- What I claim as new and desire to secure by Letters Patent of the United States is:

.diethylene glycol and vegetable oil, heating the reaction products gradually to a temperature in i5 excess'of 180 C., cooling the mixture, and adding a preponderant proportion of mineral lubricating oil to the reaction products.

3. The process of making stable, high temperature lubricating grease'which comprises prepar- 20 ing anhydrous vegetable soap by reacting a non-1 aqueous mixture consisting of sodium hydroxide,

monoethyl ether of diethylene glycol and a mixture of vegetableoils comprising castor, tung, linseed and soya bean oils, heating the reaction 25 products gradually to a .temperature of about 280 C., cooling the mixture, adding a preponder ant'proportion of'mineral lubricating oil to the. reaction products, and heating the mixture until a clear solution is obtained. 30 4 'minor proportion of an anhydrous alkali metal 40 soap prepared by heating to reaction temperature a non-aqueous mixture consisting of an alkali metal -hydroxide, fatty material, and 'an-alkyl e'ther of diethylene glycol.

6. A stable, heat-resisting alkali metal soap 45 grease consisting. essentially of-a major proportion of minerallubricating oil and a minor'proportion of an anhydrous alkali metalsoap com-. posed of thereaction product of anon-aqueous mixture consistin f an alkali metal hydroxide,

drying and semi-drying oils, and-castor oil, and

suflicient alkyl ether of diethylene' glycol to leave in the product a residue of same as a bonding agent. 4

7. A stable, heat-resisting alkali metal soap 55 -grease consistingessentially of a preponderant proportion'of mineral lubricating oiland a minor proportion of an anhydrous alkali metal soap composed of the reaction product of a non aqueous mixture consisting of an alkali 'metal 4301 hydroxide, stearic acid, drying and. semi-dryingv oils and castor oil, and suflicient alkyl ether of diethylene glycol to leave in the product a residue of same'as a bonding agent."

8. A stable, heat-resisting sodium-soap grease 65:

consisting essentially of at'least about 85 per cent mineral lubricating oil and the-remainder consisting of an anhydrous sodium soap com-- posed of the reaction product of a non-aqueous All parts or percentage proportions mentioned mixture consisting of sodium hydroxide, stearic acid, castor oil, tung oil, linseed oil and scya bean as a bonding agent.

IRVING R.