US2398075A - Grease manufacture - Google Patents

Description

Patented Apr. 9, 1946 GREASE MANUFACTURE Lawrence C. Brunstrum. Chicago, 111., and Hubert J. Liehe, Hammond, Ind., auignors to Standard Oil Company, Chicago, 111., a corporation of Indiana No Drawing. Application July 21, 1943, Serial No. 495.804

16 Claims.

This invention relates to the manufacture of lubricating greases. More particularly it relates to the manufacture of non-separating lime greases having high drop points and low penetra- I tion differentials between the unworked and worked state. Specifically, this invention relates to a novel hydration process applicable in the manufacture of novel as wellas conventional lime grease compositions.

This invention relates to lime greases which are gel-like composites of a lime soap and hydrocarbon oil requiring a small but essential proportion of water to obtain and maintain proper dispersion of the lime soap in the oil. This water appears to be water of hydration, closely associated with. the lime soap and distinguishable from water which may be merely emulsified in the grease. The exact proportion of water required to hydrate the lime soap will vary with the nature of the soap and of the oil with which it is combined to produce a grease.

Probably the most critical and unsatisfactory step in the previously known processes for the manufacture of lime greases is the hydration step. Both in the openand closed-kettle methods of lime grease manufacture the hydration step is characterized by difficulty of control and reproduction, so that large batches of grease are often ruined at this stage.

From the standpoint of lime grease manufacture, commercial soap stocks can be characterized as follows:

Approximate Ap roximate 'l ypc iodine Exam 1e tYter, C. number 9 Typical 40 40 Tallow. Premium.. 46 24 Hydroiol46. Special 50+ -10 Stearic acid.

ber below about 20 can not be hydrated by known processes to prepare satisfactory greases.

It is an object of this invention to provide a novel and useful hydration process for lime soaps. Another object of this invention is to provide a hydration process for lime soaps in grease manufacture characterized by ease of control and reproducibility. An additional object of this invention is to increase the ease of hydration of lime soaps used in grease manufacture. A further obiect of this invention is to provide a hydration process which can be applied successfully in the hydration of lime soaps of substantially saturated 5 fatty acids having a titer above about 47 C. and an iodine number below about 20. Yet another object of this invention is to provide novel lime grease compositions characterized by great stability against soap separation and oil leakage, high drop points and low penetration differential between the unworked and the worked state.

Briefly, we have found that certain substances function as assistants in the hydration of lime soaps. These substances will hereinafter be referred to as hydration assistants, We have found that hydration assistants increase the ease of hydration of lime soaps known to be hydratable and useful in the preparation of lime greases and also render possible the hydration of lime soaps which could not be hydrated heretofore and which can now be used in the preparation of novel and useful greases.

We have found that surface active substances in general function as hydration assistants in the hydration of lime soaps, However, preferentially water soluble surface active substances function more desirably as hydration assistants in our process and constitute a preferred class of hydration assistants. We can in some instances use mixtures of preferentially water soluble and preferentially oil soluble hydration assistants in our process.

By surface active substances we mean to denote substances which, in small proportions of less than about 2.5% by weight, based on the lime grease, appreciably reduce the interfacial tension between water or an aqueous phase and a hydrophobic liquid or solid phase. A very broad class of compounds, many of which are in commercial production, fall within the terms of the above definition of surface active substances capable of functioning as hydration assistants in our process. Examples of various classes of compounds capable of functioning as hydration assistants in our process include sulfated higher alcohols, alkyl sulfonates, petroleum sulfonates, alkyl aromatic sulfonates, alkyl phenol sulfonates, sulfonated fatty acid amides, sulfonated fatty esters, sulfated fatty esters, sulfated fatty acids, quaternary ammonium halides, phosphorated alcohols, alkyl phosphoric acid soaps, fatty acid soaps of alkylolamines, substituted amides of alkyl phosphates, high molecular weight amines, sulfonated high molecular weight amines, sulfated glycerylamldes, alkylated amino esters of long chain fatty acids,

the action of any given hydration assistant or defined mixture of hydration assistants is quite specific and its applicability and efficiency is dependent on the specific soap used and the nature of the hydrocarbon oil blended with the soap in grease making. Thus, when readily hydratable lime soaps are being hydrated, relatively weak hydration assistants will exert an appreciable influence. With a difilcultly hydratable lime soap it will be necessary to use a strong hydration assistant having the power of greatly reducing interfacial tension at low concentrations between water or an aqueous phase and a hydrophobic solid or liquid phase.

The fatty acid soaps of alkali metals or ammonia, i. e.. ordinary detergent soaps of commerce, are weak hydration assistants in the hydration of lime soaps. Thus. we have found that the addition of sodium oleate in proportions up to 2% by weight, based on the finished grease. exerts no assisting effect in the hydration of lime soaps of substantially saturated fatt acids havin a titer above about 47 C. and an iodine number below about 20, although an assisting effect was observed in the hydration of more readily hydratable lime soaps. Because of their exceedingly weak or wholly inappreciable assisting effect. we exclude from the term hydrationassistant" used herein the ordinary detergent soaps of commerce, viz., fatty acid soaps of alkali metals or ammonia.

The hydration assistant can be added to the lime soap during its formation or at any stage of the grease manufacturing process prior to or concurrent with the hydration stage, provided only that the hydration assistant be not destroyed by any processing step prior to the hydration stage. The hydration assistant may be added to the soap with the water added for hydration or it may be separately introduced. We have found it desirable to employ preferentially water soluble hydration assistantsand to add them to the lime soap with the water used for hydration. It has been found highly desirable to apply our hydration process to substantially anhydrous lime soap bases. since we can obtain more uniform products than are obtainable by hydration of wet soap bases containing unknown or variable proportions of water.

Our process can be applied to the hydration of a substantially pure lime soap which is thereafter. blended with hot oil to produce a grease. However, we prefer to apply our hydration process to mixtures of hydrocarbon oil and lime soap. We prefer to prepare the lime soap in the presence of a portion of the oil and thereafter hydrate the lime soap and add the remainder of the oil to produce a grease of the desired consistency. Soap bases which can be hydrated by our process are usually mixtures of hydrocarbon oil and about 25 to about 50% of the lime soap, although somewhat higher or lower proportions of lime soap can be used. More reproducible results can be obtained in our hydration process if the soap base is substantially dehydrated before controlled hydration in the presence of a hydra tion assistant.

Lime soaps and lime soap bases for use in the manufacture of greases by our process can be prepared b conventional methods which form no part of the present invention. The lime soaps can contain added proportions, e. g. about 0.5 to about 15% by weight of soaps of sodium, barium. aluminum and the like. An especiall; desirable addition to the lime soaps are soda soaps. We have found that highly stable greases can be produced by the hydration of a lime soap containing small proportions, (e. g.. about 2 to about 15% by weight of the total soap) of the soda soap of the same or a different fatty acid than that combined in the lime soap. Lime greases as described in this specification and in the claims are intended to include any grease wherein the soap compounded with the hydrocarbon oil is predominantly a lime soap but may also contain small proportions of the soaps of other metals.

In order to produce and maintain a stable soap gel structure in lime greases, about 0.2 to about 2.0% of water by weight must be incorporated therein, depending on the characteristics and proportions of the specific ingredients used in the production of the grease.

The percentage of water required for hydration increases with increasing percentages of lime soaps and with increasing viscosity of the oil and titer of the fatty acid combined in the lime soap. The water requirement is also affected by the nature of the oil and the degree of unsaturation of the fatty acid combined in the lime soaps. 1

We prefer to add substantially only sufficient water to hydrate the lime soap. The addition of less than the quantity of water required for hydration results in the production of a murky and lumpy grease because of the presence of unhydrated soap. Unhydrated soap tends to settle upon the surface to be lubricated and operate as an abrasive. The addition of water in excess of that required for hydration results in the production of an unstable grease which tends to leak oil and to corrode bearing surfaces because of its content of emulsified water.

The optimum proportion of hydration assistant to be used will vary with the roperties not only of the hydration assistant but also with the properties of the lime soap and the oil used in the preparation of the grease. In general we can use about 0.1 to about 2.5% by weight of hydration assistant, based on the total grease, with satisfactory results.

Hydration can best be effected under carefully controlled, reproducible temperature conditions. We have found two selected ranges of temperatures wherein hydration can be effected very smoothly.

In the method which we shall designate as the low temperature hydration method, temperatures in the range of about F. to about 200 F. are used. Thorough agitation of the soap base is necessary. The use of a soda soap, e. g. sodium stearate, in proportions of about V6 to 6 of the lime soap by weight is advantageous. The hydration assistant may comprise from about 0.1 to about 2.5% by weight of the finished grease, depending on the efllcacy of the particular hydration assistant selected for use. Filling temperatures below about F. are ordinarily satisfactory.

In the method which we shall designate as the high temperature hydration method temperatures in the range of about 225 F. to about 240 F. are used. This method has been found to work well with lime soap bases which contain about 30 to about 45% by weight of lime soaps. The use of a soap mixture containing about 4 to. about 10% by weight of a soda soap, e. g. sodium stearate, based on lime soap, has been found to produce desirable greases of high stability. The hydration assistant may be added to the soap in one of the earlier stages of manufacture, or along with the water added in the hydration step. The lime grease produced by the high temperature method can be filled at temperatures in the range of about 190 F. to about 210 F. although in some cases it may be desirable to stir the grease down to about 150 F. and fill it at that temperature.

were made with calcium soaps of Hydrofol 51 fatty acids and sodium stearate. The soap content of these greases was, in all cases, 20% by weight.

In Table 1, Anhydrous Wettal is a complex mixture whose active constituent can be represented by the structural formula O RL-O-CHsCHa-O-C HaOHr-0%0NH:CH:CH:OH

wherein the A suitable grease prepared by our low temperais ture hydration process had the following comradical is derived from coccanut oil fatty acids. position: W. A. 12 is a mixture of alkyl benzene sodium Pounds sulfonates wherein the alkyl group contains about Hydrofol i fatty acids 15.2 to about 16 carbon atoms and some sodium Stearic a 3.0 sulfate impurity. W. A. 3 is a purified form of Dry NaOI-I 0.5 W. A. 12 containing little or no sodium sulfate. Hydrated lime 2.4 Duponal W. A. is a mixture of the sodium-salts Aikyl benzene sodium sulfonate 0.26 of fatty alcohol sulfates, principally the sodium Mineral oil 79.0 salt of sulfated lauryl alcohol.

Table 1 Weight Hydration assistant Penetration 0 N ri 0 r: 798.50 0. 08011111 0 P V611 5 pg n Sodium Kind by v tgigl t Unworked Worked F in grease 4.5 Anhydrous Wettai. as 256 210 No leakage 230 5 0.5 270 275 do an 5 Diglyeoi steal-ate. 0. 5 5 W. A. 12 0.5 288 265 No leakage- 6 0.25 304 274 do 220 6 W. A. 3 0. 308 279 Slight leakage.-. 220 6 Duponol W.A. 0.5 320 802 Noieakage In the above example, the Hydrofol fatty acids are fatty acids obtained by the hydrogenation of fish oils, and have a titer of53 0., acid number of 196, an iodine value not greater than 6 and a saponification value of 194. The alkyl benzene sodium suifonate hydration assistant was present during the hydration of the lime soap base. We can use about 5 to about by weight of a lime soap, about 0.1 to about 2.5% by weight of a suitable hydration assistant and about 65 to about 95% by weight of a hydrocarbon oil in greases The penetration test shown in Table 1 is designated by the American Society for Testing Materials (A. S. TL-M.) and D 2l'I-38T (1939); the drop point is A. S. T. M. test D 566-T (1940). The oven test is one designed to test the stability of greases against leakage; in this test a grease is maintained for 7 days at 175 F. to determine if oil will separate or leak" therefrom.

A suitable formula for the preparation of a grease by our high temperature hydration method is as follows: I

Table 2 W ht llydration assistant Penetration Percent ratio of Drop 3 g gggi calcium to Pamant Ovcn test point,

in grease Sodmm Kind byweight Unworkod Worked F Soap in grease 8.. 20 8 g g g 'g a' 174 216 Noleakaga. 222

. Anhydrous Wet- 0.5 9 16 ta].

Diglycol steal-ate. l. 0 10 i6 10 was 0.2 11 18 30 Duponol W. A 0. 5 l2 18 30 Duponol W. A... 0. 5 13M. 18 30 w. A. 12 0.5 14 18 30 W. A. 12 0.5

prepared by our low temperature hydration proc- Pounds ess. Usually, hydrocarbon oils having a viscosity Hydrofol 51 fatty acids 16.7 in the range of about to about 1600 seconds Hydrated lime 2.6 Saybolt Universalat 100 F. can be used. Dry NaOH 0.1 Other greases prepared by our low temperature Water 0.5 method, particularly suitable as air brake lubri- Hydration assistant 0.5 These greases Hydrocarbon oil 80.5

cants, are described in Table 1.

We can use about 5 to about 30% by weight of a lime soap. about 0.1 to about 2.5% by weight of a suitable hydration assistance and about 65 to about 95% by weight of a hydrocarbon oil.

Other greases prepared by our high temperature hydration method are described in Table 2. These greases, with the exception of grease number 14 were made with calcium soaps of Hydrofol 51 fatty acids and sodium stearate. In grease number 14, a mixture of calcium and sodium soaps of Hydrofol 51 fatty acids was used.

Greases 11 and 13 were filled at 200 F., while greases 12 and 14 were filled at 160 F.

The examples given in Tables 1 and 2 are intended to be illustrative, but not limitative, of our invention.

It will be seen that we have provided a novel method for the hydration of lime soaps in the production of useful lubricating greases. We have also succeeded in producing novel greases not hitherto available to the art, characterized by their content of lime soaps of high titer fatty acids.

We claim:

1. In the manufacture of a lime grease, the improvement which comprises hydrating a lime soap in the resence of a preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease. of appreciably reducing the interfacial tension between water and a hydrophobic phase.

2. In the manufacture of a lime grease, the improvement which comprises hydrating a lime soap in the presence of a perferentially watersoluble fatty alcohol sulfate.

3. In the manufacture of a lime grease, the improvement which comprises hydrating a lime soap in the presence of an alkyl benzene sodium sulfonate containing between about 10 and about 16 carbon atoms in the alkyl group.

4. In the manufacture of a lime grease, the improvement which comprises hydrating a lime soap in the presence of a surface active substance whose active constituent has the formula wherein the o N noradical is derived from cocoanut oil fatty acids.

5. In the manufacture of a lime grease, the improvement which comprises hydrating a substantially anhydrous lime soap in the presence of a preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease, of appreciably reducing the interfacial tension between water and a hydrophobic phase.

6. A process for the manufacture of a lime grease comprising preparing a mixture of a lime soap and oil comprising about to about 30% of lime soap, substantially dehydrating said mixture, and hydrating said lime soap by the addition of water and a preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease, of appreciably reducing the interfacial tension between water and a hydrophobic phase.

7. A process for the manufacture of a lime grease comprising preparing a mixture of a lime soap and hydrocarbon oil comprising about 5 to about 30% of lime soap and hydrating said lime soap in the presence of a preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease, of appreciably reducing the interfacial tension between water and hydrophobic phase, the hydration operation being effected at a temperature in the range of about F. to about 200 F.

8. A process for the manufacture of a lime grease comprising preparing a mixture of a lime soap and hydrocarbon oil comprising about 5 to about 30% of lime soap and hydrating said lime soap in the presence of r preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease, of appreciably reducing the interfacial tension between water and a ydrophobic phase, the hydration operation being effected at a temperature in the range of about 225 F. to about 240 F.

9. A process for the manufacture of a lime grease comprising preparing a mixture of a lime soap and hydrocarbon oil comprising about 5 to about 30% of lime soap, substantially dehydrating said mixture, and hydrating said lime soap in the presence of a preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease, of appreciably reducing the interfacial tension between water and a hydrophobic phase, the hydration operation being effected at a temperature in the range of about 225 F. to about 240 F.

10. A process for the manufacture of a lime grease comprising preparing a mixture of a hydrocarbon oil, a lime soap and a soda soap, said mixture comprising about 5 to about 30% of lime soap and about 0.1 to about 5.0% of soda soap, substantially dehydrating said mixture and hydrating said lime soap in the presence of a preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease, of appreciably reducing the interfacial tension between water and a hydrophobic phase.

11. A process for the manufacture of a lime grease comprising preparing a lime soap of a substantially saturated fatty acid having a titer about about 47 C. and an iodine number below about 20, and hydrating said lime soap in the presence of a preferentially water soluble surface active substance capable, in a small proportion less than about 2.5% by weight based on the lime grease, of appreciably reducing the interfacial tension between water and a hydrophobic phase.

12. A process for the manufacture of a lime grease comprising preparing a mixture of a lime soap and a hydrocarbon oil comprising about 5 to about 30% of lime soap, substantially dehydrating said mixture and hydrating said lime soap by the addition of water and a preferentially water soluble fatty alcohol sulfate.

13. A process for the manufacture of a lime grease comprising preparing a mixture of a lime soap and a hydrocarbon oil comprising about 5 to about 30% of lime soap, substantially dehydrating said mixture and hydrating said lime soap by the addition of water and an alkyl benzene sodium sulfonate containing between about 10 and about 16 carbon atoms in the alkyl group.

14. A process for the manufacture of a lime grease comprising preparing a mixture of a lime soap and a hydrocarbon oil comprising about 5 a preferentially water soluble surface active subto about 30% of lime soap, substantially dehydrating said mixture and hydrating said lime soap by the addition of water and a surface active substance whose active constituent has the formula radical is derived from cocoanut oil fatty acids.

'fatty acid having a titer above about 47 C. and

an iodine number below about 20, said mixture comprising about 0.1 to about 5% of soda soap and about 5 to about 30% of lime soap, substantially dehydrating said mixture, and hydrating said lime soap with water in the presence of a 15. A process for the manufacture of alime 15 preferentially water soluble surface active subabout 5 to about 30% of lime soap, and hydrat- 2o ing said lime soap with water in the presence of stance capable, in a small proportion less than about 2.5% by weight based on the lime grease,

of appreciably reducing the interfacial tension between water and a hydrophobic phase.

LAWRENCE C. BRUNSTRUM. HUBERT J. LIEHE.