US2303256A - Grease and process of making same - Google Patents

Description

Patented Nov. 24, 1942 GREASE AND PROCESS OF MAKING SAME James Allan Camelrord, Niagara. Falls, N. E, as. signor to Alox Corporation, New York, N. Y., a corporation of New York so Drawing. Application November 12,1940, Serial No. 365,541

7 Claims. (Cl. 252-39) This invention is concerned with. improved lugroup of solid to semi-solid lubricants comprising mixtures of fatty acids soaps and mineral oils. The greases to which the present invention is confined comprise metallic soaps of pre-selected petroleum acids, by which latter expression are here broadly meant the saturated aliphatic carboxylic (and hydroxycarboxylic) acids of relatively high molecular weight produced by the controlled, liquid-phase, partial oxidation of a mixture of mineral hydrocarbons by the process described in U. S. Patent No. 1,768,523 to Arthur W. Burwell.

An object of the present invention is the provision of improved lubricating greases which are readily deformed at very low temperatures (e. g., at temperatures encountered in the upper air). Another object of invention is the provision of lubricating greases 'which do not become actually solid at low temperatures. It is a specific object of invention to provide permanently deformable barium soap greases.

I have found that lubricatinggreases possessing very desirable and surprising properties-and in particular the very desirable property of remaining readily deformable at very low temperatures--may be produced by dispersing in .very low cold test, substantially wax-free, mineral lubricating oils metallic soaps (particularly barium soaps) of relatively high molecular weight petroleum acids produced, by the aforesaid Burwell process of oxidation, from substantially wax-free normally liquid fractions of petroleum.

The invention will now be described in greater particularity and with reference to the following illustrative examples:

195 mg. KOH/gram) 250 Barium hydrate 135 Water 60 Thoroughly de-waxed naphthenic base lubricating oil, S. U. V. 130/210 F 610 Melting point of finished grease 320 F. before milling and 310 F. after milling.

Worked penetration at 77 F.--255.

The general technic of preparing the grease was as follows:

- proximately 200 parts).

The petroleum acids were heated with a portion of the hydrocarbon lubricating 'oil stock (ap- The barium hydroxide was dispersed in the water and this dispersion was slowly added, by portions, to the above mixture of petroleum acids and lubricating oil, at a temperature of approximately 200 F., with constant mechanical agitation. Heat was then applied gradually until all the water was driven oil, which was at a temperature of approximately 300 F. The remainder of the hydrocarbon oil was then added slowly but continuously with agitation of the soap-oil mass. Heating was continued until the final temperature was in excess of 350 F. f

The temperature selected for the heating treatment is not critical below the flash point of the hydrocarbon oil used as diluent: I may hold the temperature during soap-formation at from about 140 F. to say 250 F. as desired, and I may dehydrate at a temperature between about 300 F. and about 400 F. or even higher. The rate of addition of the aqueous dispersion of barium hydroxide is adjusted to the readily visible progress of soap formation, so as to maintain the homogeneity of the soap oil mixture. Addition of the barium hydroxide preferably is carefully controlled to give a finished product which is not basic but rather neutral, or even slightly acid.

Should any lumpiness 'of the reaction mixture appear during progress of the soap-forming step, that condition may be met by temporarily suspending additions of barium hydroxide, raising the temperature, and continuing the stirring until the mass is again smooth. Any rubberiness in the grease is destroyed by milling.

As will be obvious to one skilled in this art, the proportion between the soap and the oil is not critical and may be adjusted to suit the particular requirements: the larger the proportion of oil to soap, the more nearly fluid the grease. The ratio (between soap and oil) may vary between 0.085 and 1.5 parts by weight of the soap to 1 part by weight of the oil. i

Example 2 l Parts by 3 weight Separated petroleum acids from the oxidation of a thoroughly de-waxed lubricating oil fraction, S. U. V. 140/210 F. (saponification number mg. KOH/gram) 300 Barium hydrate 72 Thoroughly dewaxed Mid-Continent lubricating oil, S. U. V. /210 F 650 Water 35 Melting point of finished grease 290 F. before milling, and 285 F. after milling.

Worked penetration at 77 F.2l5.

Example 3 Parts by weight Separated petroleum acids from the oxidation of a thoroughly de-waxed lubricat- Melting point of finished grease 245 F. before milling, and 240 F. after milling.

Worked penetration at 77 F.-320.

' The soap-forming step of the above illustrated examples may, if desired, be practiced upon the crude oxidation reaction mixture (containing, besides the aforesaid petroleum acids and their esters and lactones, some unoxidized hydrocarbons and a material proportion of neutral and unsaponifiable partially oxidized compounds including alcoholic, ketonic and keto-alcoholic derivatives of the original hydrocarbons): in that event, the resulting product is, of course, a mixture of barium soaps contaminated by said unsaponifiables. For obvious reasons, I prefer first to effect separation of the petroleum acids and to practice the soap-forming step upon the so-separated petroleum acids-rich portion of the crude oxidation reaction mixture.

The barium soap grease compositions of the invention may have melting points ranging from in excess of 320 F. to as low as 160 F. I have found, further, that these barium soap grease compositions as a group have, among others, the following properties: they are insoluble in water and not readily emulsifiable with water; they are readily deformable at very low temperatures; they have good anti-corrosive properties; their worked penetration values range from about 400 to about 100 at 77 F.; they are desirably smooth and unctuous, and after having been melted they reform (upon cooling), without separation, into homogeneous compositions having the same characteristics (e. g., appearance, lubricating ability, and physical properties generally) as'were possessed by the original greases.

I have found that the relative fluidity (or solidity) of the grease composition is afiected by the identity of the agent employed for accelerating the oxidation of the initial hydrocarbonaceous material. That is to say, I have found that the soaps of petroleum acids produced by the aid of a catalytic manganese compound yield greases which are much more fluid than those from soaps of apparently chemically identical petroleum acids produced in an oxidation wherein oxidation-acceleration had been effected by return to the oxidizer of partially oxidized, unsaponifiable, components of a previous oxidation batch. Accordingly, I may adjust the relative fluidity of the eventual grease composition to any desired value by appropriate mingling of petroleum acids from oxidations involving the two dissimilar oxidation-catalyzing or oxidationaccelerating materials. 7

While in the above examples the invention has been illustrated by reference to grease compositions in which the soap components are barium soaps, it is to be understood that the invention broadly includes grease compositions composed of low cold test, de-waxed lubricating ofls and metallic soaps, generally, of petroleum acids produced by the liquid-phase (Burwell process) 0111- 75 dation of normally liquid, substantially wax-free, mineral hydrocarbon mixtures. Thus, instead of using an oxide or hydroxide or carbonate, or other basically-reacting compound of barium, I may use an oxide, hydroxide, carbonate or other basically-reacting compound of calcium, strontium, or other alkaline earth metal, or of a heavy metal such as zinc or lead, or,where watersolubility is of lesser importance,even of an alkali metal such as sodium, potassium or lithium. The invention includes the concept of providing greases containing mixtures of the above mentioned soaps whereby to confer upon the greases particular properties to meet specific requirements.

This application contains subject matter in common with that of my copending application Serial No. 194,208, filed March 5, 1938.

I claim:

1. As a new product, a lubricating grease composition consisting essentially of a permanently readily deformable stable, homogeneous dispersion of an anhydrous, neutral to slightly acid, metallic soap of petroleum acids derived by oxidation of a substantially wax-free and normally liquid mineral hydrocarbons mixture in a substantially wax-free mineral lubricating oil, which grease composition, after having been melted, reforms upon cooling into the same homogeneous composition.

2. As a new product, a lubricating grease composition consisting essentially of a permanently readily deformable stable, homogeneous dispersion of an anhydrous, neutral to slightly acid, alkaline earth metal soap of petroleum acids derived by oxidation of a substantially wax-free and normally liquid mineral hydrocarbons mixture in a substantially wax-free mineral lubrieating oil, which grease composition, after having been melted, reforms upon cooling into the same homogeneous composition.

3. As a new product, a lubricating grease composition consisting essentially of a permanently readily deformable, stable, homogeneous dispersion of an anhydrous, neutral to slightly acid, barium soap of petroleum acids derived by oxidation of a substantially wax-free and normally liquid mineral hydrocarbons mixture in a substantially wax-free mineral lubricating oil, which grease composition, after having been melted, reforms upon cooling into the same homogeneous composition.

4. Process of forming a lubricating grease composition which is readily deformable at low temperature, which comprises treating a mixture of petroleum acids derived by oxidation of a substantially wax-free and normally liquid mineral hydrocarbons mixture with a basically-reacting inorganic compound of a metal in such proportions as to yield a soap product which is neutral to slightly acid, removing water from the resulting metallic soap mixture and extending the substantially anhydrous metallic soap mixture by admixture therewith of a substantially wax-free mineral lubricating oil to the production of a homogeneous grease.

5. Process of forming a lubricating grease composition which is readily deformable at low temperature, which comprises treating a mixture of petroleum acids derived by oxidation of a substantially wax-free and normally liquid mineral hydrocarbons mixture with a basically-reacting inorganic compound of an alkaline earth metal in such proportions as to yield asoap product which is neutral to slightly acid, dehydrating the tions as to yield a barium soap product which 1 is neutral to slightly acid, removing water from the resulting barium soap mixture, and extending the resulting anhydrous barium soap mixture by admixture therewith of a substantially waxfree mineral lubricating oil to the production of a homogeneous grease.

7. In a process of claim 4, the step which consists in dissolving said petroleum acids in substantially wax-free mineral lubricating oil before treating said petroleum acids with said basically-reacting metallic compound.

JAMES ALLAN CAMELFORD.