CA1067480A - Lubricant-coolant emulsion additive - Google Patents

Abstract

Abstract of the Disclosure Method for adding a fatty acid to an oil-in-water type emulsion during use without detrimentally affecting the properties of the emulsion, comprising providing a solution of (A) the fatty acid and (B) a liquid in which the fatty acid is readily soluble, selected from the group consisting of at least one polyoxyalkylene glycerol, at least one monoalkyl ether of a polyoxyalkylene glycol where the alkyl group has at least four carbon atoms and the alkylene group has at least two repeating units, and diethylene glycol di-t-butyl ether, and adding said solution to the emulsion.

Description

1C)67480 .
This invention relates to oil-in-water lubri-cant-coolant emulsions used in metalworking operations such as rollingr cutting, cupping, drawing and ironingr milling, scalping, drillingr grindingr punching, and the like. In particular, it reiates to a method for adding a fatty acid to such emulsions, thereb~ maintaining a preselected level of lubricity agent in the emulsion.
In methods of shaping metals in which lubrication is required, it haa become common practice to use lO~ emulsions in place of prior used non-aqueous hydrocarbon ; lubricants. Por~example, in rolling a metal suoh as aluminumr magnesium, or steel through steel work rolls it is usual to use an emulsion to flood the tool and the , .
workpiece. As used herein "tool" is used broadly to 15~ refer to any piece of equipment with which the metal is in contact during~the metalworking operation, e.g.,~
rol1sr punches, diesr drills, cutting devices,~r1nding~
devices, and the like. The emulsion serves the dual function~of both coolant and lubricant. As a~coolant in~
20 ~ cutting operations, the emulsion helps to control the~
: , temperature of the cutting tool. As a coolant in other shaping operationsr for exampler in rolling, the pattern . .
of distribution of thQ emulsion on the work rolls is regulated to control the temperature gradient of the rolls 25~ ~ transversely to the work s~tock and hence the shape of the rolls is controlled. The rate of ~low of the emulsion ;~ onto the metal being shaped regulates the temperature thereof during the various stages of shaping.

l8rO09-F -l-A~ '' ., .

~ la674so As a lubricant, the emulsion serves (1) to control the frictional forces existincJ between the work-piece and the toolî (2) to promote the development of desired tool coatings during the shaping process, e.g., rolled-coating during rolling; (3) to prevent excessive transfer of metal from the workpiece to the tool or rom the tool to the workpiece, e.g., between the rolls and the workpiece as in rolling operation; and (4) to facili-tate removal of the workpiece from the tool, e.g., as ln punching operations.
Typical emulsions that have been used for metal shaping operations such as rolling or cutting have con-sisted essentially of from about 0.5 to 20~ by weight of an oil in the water, the oil being a mixture referred to~
in the trade as a neat soluble oil or simply soluble oil.;~
Such~neat soluble oil lS ~widely~sold as a concentrate ~
containing, generally, about 70-90 percent by weight of a base oil, such a~s a light mineral oil, from about~l to ~ ~ about 20 percent by weight, based~on said neat soluble oil, ~;
; 20 ~ of one or more anionic and/or nonionic oil-in-water emulsi-fying agents and the balance substantially water. For most metal shaping~operations, the neat soluble oil must~
contain from about 0.5 to about 15 percent by weight lubricity additives such as long chain alcohoIs, e.g., C12 to C16 alcoholsr long ohain fatty aclds, e.g.r C12 to ~ -C22 acids such as oleic aoidr and salts or esters thereofr~ ~ ~
::: : :
~ e.g., alkanolamine~soapsr or, esters such as butyl stearates ; ~ which serve as extreme pressure agents. Emulsions are made up conventionally by admixing one of the commercially a~ailable substantially water-free concentrates with .
, ' " ' 18,009-F --2-~)67~

water. The commercial concentrates usually contain up to Q.5 percen-t by weight oE a bactericide and from about 0.5 to abou~ 5 percent by weight o~ a coupling agent, i.e., a substance which stabilizes the concentrate during storage prior to use.
Since, as will become apparent, this invention employs an additive solu-tion as a means for controlling the concentration of a lubricity additive, i.e., the active ingredient in the oil phase of the emulsion, to avoid confusion the phràse "lubriclty agent~s)" is used hereinafter to refer to the active component usually referred to in the trade as "lubricity additive". "Fatty acid-type lubricity agent(s)" refers to long chain fatty acids and ; mixtures thereof, and may, but need not necessarily, - inolude one or re alkali metal or ammonium salts thereof.
"Free fatty acid(s)" refers to long chain fatty acids and mixtures thereof, substantially free from their corresponding alkalL metal and ammonium soaps.
The composition of the neat soluble oil~itself forms no part of the present invention. The method and :~ :
composition of the invention are usable with substantially all~of the commonly known and used, commeroially available;
neat soluble oils, without modification of the soluble oil per se.
~ Representative commercial compounded oils, i.e., soluble oils, include, for example, Solvac 1535G,*
Prosol 44,*Prosol 66, Prosol 172*, and Mobil 200C,* all supplied ~y Mobil Oil Company, Rollex A*supplied by the Shell Chemical :
Company; RolKleen #53*supplied by the D. A. Stuart Oil Company, Limited; A-100*supplied by Far Best; Tandemol C86*
.
*Trademark ~ ~
' ' ' ' ' ' ' ' ~ ' 18,009-F -3-~ .

:, " ~067~80 and Tandemol K87*supplied by E. F. Houghton and Company;
Texaco 591*supplied by Texaco, Inc.; and Quakerol 538 *
supplied by the Quaker Chemical Corporation.
A typical neat soluble oil that is commercially available has the following general cornposition, by weight:
- Com~onents Percent ~ight Mineral Oil 83 ; Lubricity Agents 11 Emulsifiers 4 ~10 Coupling Agents 0.5 Bactericide 0.5 Detergent The base oil used in making up a neat soluble oil generally is selected from a light hydrocarbon or ; 15 light hydrocarbon mixture having a viscosity of about 40 to 200 Saybolt Universal Seconds (SUS) at 100F~ However, other lubricious materials such as fatty oils, e.g.,-palm oil, or synthetic materials, e.g., palm oll substi-tutes are also used as a base oil in making up soluble oil. Such other lubricity materials may have viscosities as high as about 850 SUS.
For the purposes of the following description and the appended claims r the term base oil is understood b ~ to encompass the light hydrocarbon or hydrocarbon mixtures recognized as light mineral oils, in addition to lubricious materials including vegetable oils, such as palm oil, animal fats such as lard oil, and palm oil substitutes and the equivalents thereof, e.g., polyglycols and ethers and esters thereof, silicones and polysilicones, carbonates, mercaptals, formals, and other synthetic lubricating oils *Trademark 18,009-F -4-.~,,i ~Pf;i74tiO

known to the art, selected from those which are non--stainin~ of the particular metal being shaped.
~ Suitable anionic oil-in-water emulsifiers used in sufficient amount to emulsify the base oil include, for example: (1) alkylar~lsulfonates such as the higher alkylbenzene sulfonates wherein higher alkyl means an alkyl group having at least 8 carbon atoms, e.g., C12-:
H25C6H4SO3Na; (2) fatty alkyl sulfates such as CH3(CH2)10OSO3Na; (3) the sulfonated fatty amines such ~ as C17H33CON(CH3)C2H~SO3Na; (4~ the alkali metal salts of sulfonated~fatty acids; and the like. The other al-kali metal salts of these compounds and the triethanolamine :
salts are equivalents of the sodium salts described above.
The alkanolamine soaps of long chain fatty acids are par~
ticularly suitable, e.g., diisopropanolamine~ diethanol-amine or monoethano1amlne salts of olelc acid, pa1mltlc ~ ~ acid or stearic acid, the salts being useful~sing1y~or ; ~ ~ as mixtures.
Suitable nonionic~oil-in-water emulsifiers in-clude the nonionic ethers such as those derived from alkylphenols and ethylene oxide, e.g., C8H17C6H4OC2H4(OC2-~4)XOH wherein x has a value of 9 to 14 or more, the primary alcohol-ethylene oxide adducts, and the secondary alcohol-ethylene oxlde;adducts.
~hen one of the described emulsions is placed in service in metal shaping operations it tends to work well initially both as a coolant and as a lubricant; in fact, it is commonly observed that the metal surace obtained in metal shaping operations is improved after several days of using the emulsion. The effectiveness of emulsions as `:

~ 18,009-F ~5-~, `` ` ~067480 .
lubricants, however, has been observed to deteriorate thereafter. Use of filtration techniques combined with control of water hardness, such as taught in U. S. Patent Nos. 3,408,8~3 and 3,409,551, greatly prolongs the life of an emulsion, and is certainly preferrèd even when using the present invention. Nevertheless, a~decrease in the quality and capacity of production occurs where only filtratiQn and control of hardness is used.
Some degree of suocess has been achieved in con-~ trol of emulsions by monitoring and adjusting the pH, ~` by adding base oils and/or emulsifiers to control the oil particle size, and the amount of free oil (i.e., non--emulsified) and emulsified oil in the system, and the like.
:
~ It has also been reallzed that control o~ the ~
balance of the various lubricity agents (not to be confused with the base oil) in~the~oil phase is critical,~and it is this aspect which is the subject of the present invention.
As an emulsion is used,~the~lubrlcity agents are gradually~
20~ ~ depleted, for example, by carry oùt on the workpiece, by degradation by bacteria and heat, by reaction with metal fines and other contaminating substances, and the like.
Moreover, par~icularly where an emulsion is used wherein~
:
the emulsified oiI phase comprises a relatively low percentage of the total emulsion, various oils entering the system, such as leaking gear lube oil, hydraulic oil, and the like, can act às diluents of the lubrici-ty agents.
~ To further explain this latter point~, ~or any ; ~ given operation, it is known there is an optimum range of emulsified oil content in the emulsion. As oil is carried : : ~ , . . . -. .
.

18,009-F e6_ out on the workpiece, neat oil containing the lubricity agent can be added to the emulsion to restore both the oil level and the lubricity agent, assuming there is no oil leaking into the system. Where oil is leaking into the S system, however, as is most always the case, the leaking oil usually does not contain the required lubriaity a~ents. Moreover, while much o it separates as free oil, at least some of the leaking oil becomes emulsi~ied in the system, by design or naturally. Particularly where an emulsion is empIoyed where the emulsified oil content is designed to be relatively low, e.g~, on the order of~2 to 12 weight percent of~the emulsion, the net result is ~;~ that the amount of newly emulsified oil entering the . ~
system through leakage represents a significant fractiGn of that lost through carryout. Consequently, little neat ~oil containing the lubrlcity agent can be added without upsetting the oil:water ratlo, so that while~the~total;
amount of emulsified oil remains more or less constant~or ~: : ; ; lS depIeted at a relatively~slow rate, the lubricity~ ;
~;20 ~ ; agent is depleted at a much faster rate. ~Unless the proper balance of lubrlcity agents is restored,~ a host of problems arise, such as excessive tool wear, scratching of the surface of the workpiece, and in extreme cases, actual .
tearing or~wrinkling of the workpiece, and the~like. ~ ;
Any substance which is added to the emulsion actua}ly first contacts the continuous aqueous phase. The various lubricity agents, however, must be worked into the discontinuous oil phase, or at least onto the oil droplet surface, to be effective. Thus, it is not surprising that ~ poor additive recovery is obtained where attempts have been 18,009-F -7- -~ ~ .

~06748Q

made to add the additive directly to the emulsion. That others not practicing this invention are experiencing such dificulties has been illustrated recently in a paper by R.
G. Tidwell, "Modern Hot ~ill Emulsion Controls", presented S in May, 1975, at the 1975 Annual Meeting of the American Society of Lubrication Engineers Non-Ferrous Metals Council wherein it was stated "A 50 percent recovery ~i.e. effective incorporation into the oil phase of the emulsion] of most fatty additives will generally be a good recovery " In the same paper Tidwell suggests a 75 percent recovery can be realized i the additives are added to neat oil and then made into an emulsion in a tank equipped with an agitator and a heat source. Nevertheless, the inability to easily~
add lubricity agents to the emulsion leads to waste of raw materials, premature disposal of emulsions, variations in : product quality, loss of production, and generally in-efficient operation.
: The present invention comprises a method for . adding a substantially water-immiscible fatty acid-type : 20 lubricity agent to the discontinuous neat oil phase of a neat oil-in-water lubricant-coolan~ emulsion or use in metalworking operations wherein a workpiece is contacted by a tool, comprising addlng a solution to the emulsion, said solution comprising ~5 (A) at least one free fatty acid and ~B) a liquid in which said Component (~) is readily soluble, selected from the group consisting of (ij at least one polyoxyalkylene glycerol, (ii) at least one monoalkyl ether of a polyoxyalkylene glycol where the 18,009-~ -8-~'', :

~06748~) alkyl group has at least four carbbn atoms and the alkylene group has at least two repeating units, and (iii) diekhylene glyaol di-t-butyl ether, said liquid being further characterized in that it is com-patible with the emulsion, with the work-piece, and with the tool, the concentration of Component tA~ in the solution and the amount of solution added to the emulsion being mutually 10~ ~ ~selected so that sufficient fatty acid-type~lubricity agent is added to the oil phase of the emulsion to attain a preselected concentration of the~fatty acid-type Iubricity agent in the oil phase of the emulsion~without adversely affecting the emulsion. ;
.
15 ~ Component A must be a stable liquid at temperatures likely to be attained in the emulsion, i.e, both at about the time of emulsion contact with;the tool~
and the workpiece, and also during any recirculation step$
:
which might be practiced such as filtering, settling, ~ ~skimming, or the like~ Thus, it should have a~melting point of about room temperature, i.e., 20C? or less;
lubricity agents having a somewhat higher melting point can be employed if precautions are taken to assure the~
emulsion is not allowed to cool below that temperature, but such alternatives may not be practical from an economic ~ standpoint. By "stable liquid" is mean~ that at the ;~ ~ tempèrature o the emulsion, the lubricity agent must not decompose to products which are of no benefit in the emul-sion, or rapidly vaporize. It is not practical to set a~
quantitative limit on the maximum temperature likely to be : . . . . .
-' ~
18,009-F _g_ .~ :

~067480 .
attained in the emulsion, as those skilled in the art realize s~ch temperatures will vary over a considerable range depending on the particular operation being carried ou~. ~here the Component A is comprised of a mixture of two or more 12-22 carbon atom atty acids, the mixture should have a melting point o~ about 20C or less~
As hereinabove described, certain free fatty acids, e.g. oleic acid, as well as their corresponding alkali metal and ammonium soaps are known lubricity agents~
Such free fatty acids can be readily replenished in oil--in-water emulsions by adding to such an emulsion, while in use, an effective amount of a solution of the desired free fatty acid and Component B. Depending on the pH of the emulsion and assuming the presence of alkali metal and/or amine compounds in the emulsion, the free acid can also be added to control the concentration of both the acid and the respective soaps since an equilibrium between the free acid and the soaps is reached, the acid:soap ratio being determined principally by the pH of the system. While the acid:soap ratio can be altered by varying the pH of the emulsion, those skilled in the art will recognize that depending on the particular metalworking operation, a somewhat limited pH range is often dictated by other considerations such as susceptibility of the metal of the workpiece to corrosion.
To further illustrate, a preferred emulsion for use in the manufacture of two-piece aluminum cans is one containing from about 5 to about 15 weight percent emulsi-fied oil, wherein the base oil of the neat oil is a mineral oilD The p~ of such an emulsion is preferably aboùt 8 -.
18,009-F -10-1067~80 to about 9. Free oleic acid in solution with a Component B is added to the emulsion according to the present inven-tion to maintain both the level of free oleia acid at ~rom about 1.5 to about 10 weight percent of -the emuLsified oil phas~, as well as the total cOncentratiQn of free oleic acid and oleic acid soaps at from about 6 to about 13 weight percent of said oil phase. Experience to date indicates optimum performance is realized when said levels are maintained at about 3-8 percent and about 7-lO percent, ::
respecti~ely, for aluminum~and predominately aluminum (i~.e.
at least about 50 weight percent) alloys. Similarly, by adding the free acid to an emulsion according to the present invention, the total free acid and soap concentration particularly suited for any specific operation may be 15~ ~ ; maintalned,~e.g.~, about 1-3~weight percent~vf the oil phase of the emulsion for hot~rolllng of aluminum (including predominantly aluminum alloys) on a reversing mill, about 3-5~percent for hot~rolling of aluminum on a tandem mill, about 8-14 percent for cold rolling of steel~
on a tandem mill, and the like. ~ ;
Various suitable analytical techniques are known for use in determining the concentration of various lubricity agents present in an~emulsion. Wet~methods involving titrations may be used if desiredr but modern ~ instrumental methods, such as infrared absorption, are much easier if the-necessary instruments are available to the user, and such methods tend to be more accurate~as opportunity for human error is minimized. For example9 the following procedures have been used in determining the concentrations of free oleic acid, and free oleic acid - plus soaps thereofr~as expressed herelnO
.~ . .

18rO09-F -ll-.~ ~. .

.
Free oleic acid was determined by extracting a representative sample of the emulsion having a known .
weight, with a known volume of carbon tetrachloride. A
portion of the carbon tetrachloride extract was trans-S ferred to a vial containing sodium chloride to absorb any entrained water, and thence to an optical cell ~or determina-tion of optical density at 1710 cm l, an absorption band characteristic of oleic acid. The optical density was compared with a standard curve to give the concentration of free oleic acid. A second representative sample was subjected to the same stepst except that prior~to the extraction step, the second sample was contacted with concentrated hydrochloric .
acid to convert any soaps to the free acid form~ From the optical density measurement, the total percent free oleic acid and oleic acid soap concentration was determined.~
Component B should be sufficiently effective as a solvent so that the necessary amount of Component A can be added to the emulsion without also adding so much of Component B that the emulsion is adversely affected. ;~
Preferably, Component B is selected so that a homogeneous solution can be prepared--at some temperature within the range of from about 20C up to about the temperature of the emulsion to which the solution is to be added--containiny at least about S weight percent and~more preEerably at least about 25 weight percent Co~mponent A. Most preferably, Components A and B are completely miscible with one another.
.
In proportions in which it i5 necessary to add Component B to the emulsion as a vehicle for introducing Component A into the emulsified o1l phase, Component B
must be compatible with the emulsion, e.g., it must not ~ ~ : ' ` ' ' ' ' .
l8,009-F -12~
,~.~;-`. . :

10~7480 cause the ~mulsion to become appreciably more tight ~smaller oil globule size) nor appreciably more loose (larger oil globule size), nor worse yet, cause the emulsion to break.
Similarly, at such concentrations it must be compatible with ~5 the workpiece and with the tool used in the metalworking operation, e.g., it must not cause undue corrosion or staining of the various metal surfaces.
Diethylene glycol di-t-butyl ether is suitable for use herein as Component B, as are monoalkyl ethers of polyoxyalkylene glycols where the alkyl group has at least four or more carbon atoms and the alkylene group has at least two repeating units, such as diethylene glycol n-butyl ether and higher homologs thereof which are liquids under the conditions hereinabove specified.
A preferred Component B for use herein, parti-cularly with oleic acid, is a polyoxyalkylene glycerol of the formula H2lO(C2H4O~C3H6O)yH
HCO(c2H4Otc3~6 )Y
N2co(c2H4o~c3H6o)yH~
Preferably the polyoxyalkylene glycerol has a molecular weight within the range of from about 2000 to about 3000, most preferably about 2600. When a filtered, recirculating ;
metalworking emulsion is ~reated periodically with a solution ;
of 1 part by volume oleic acid per about 0.1 to about 20 parts by volume of such a glycerol, preerably 1 part by volume oleic acid per 0.2 to 2 parts by volume of such - a glycerol, over a sustained period, higher production is attained following commencement of such treatment than without such treatment, the emulsion becomes cleaner , ' ' ' ' ~ .

18,009-F -13-"` ~067480 , indicating fewer fines are being generated in the metal-working operation, the amount of unemulsified tramp oil is reduced, and the emulsion is more easily filterable, i.e., a lesser pressure is required to maintain the same rate of flow. Such a mixture ~1 part oleic acid and about Q~2 to 2 parts of the polyoxyalkylene ~lycerolj is readily stored in conventional steel drums for extended periods of six months or more without significant corrosion.
Six month laboratory immersion tests of coupons of 3004 I0 aluminum alloy and mild steel, run at ambiant temperature :: :
~;~ also showed no detectable corrosion.
As a practical matter, it is preerred to add as `
much Component A to the emulsion as necessary to attain the preselected level of lubricity agent in the emulsified oil phase, using as little of Component B as possible. Use of excess Component B is economically unsound; moreover whenever :
one adds another component to an already complex emulsion, there is always a risk that an extreme excess may detri-mentally affect the emulsion. If Component A is not com-20 ~ pletely dissolved in the solution to be added, i.e., if a homogeneous solution lS not attained, a larger proportion of Component B, or alternatively~use of a different Compo-nent B, is called for. An increase in the amount of unemulsified water-immiscible components in the emulsion system shortly after an addition~of the additive~solution, much of which is believed attributable to unemulsified lubricity agent, indicates a need for a greater proportion of Component B in the additive. Such an increase can be observed by microscopic examination of a sample of the emulsion. In extreme cases, such an increase of 18,009~F -14-:~ .

~06748(:~

unemulsified substances can readily be observed in fresh emulsions, i.e., having substantially no fines to impart a gray color, by a slight color change in the emulsion - a.g. a change from o~f white to slight'Ly yellow, or even by the appearance o oily globules on the surface. A
slight amount of experimentation may be required to arrive at an optimum ratio of Component A to Component B depending on the particular components being employed as well as the particular emulsion being treatedO Subject to the foregoing functional limitations, a suitable ratio is , generally from about 0.1 to about 20 parts of Component B by volume, per part of Component A, the upper limitl i.e., 20, being practical rather than critical. A pre-ferred Component B to Component A ratio is from about I5 0!2:1 up to 2:1, which, without being unduly wasteful, ;~ ~ provides a comfortable excess of Component B over the ::
minimum amount necessary to assure the Component A is substantially completely taken up in the emulsified oil phase. ~ ~
; 20 ~he additive solution may be added to the emulsion periodically as needed to maintain the concentra-tion of fatty acid-type lubricity agent(s) within a preselected operating range.~ Alternatively, the additive may be introduced continuously at a suitable rate if desired. Preferably, the addition is made at or in proximity to a point of agitation in the emulsion system, e.g. near a pump intake port.
The practice of the present invention is fur-ther illustrated by th- following example:. ~

. -18,009-F -15-,~ .
.: .

~0674~0 A 6000 gallon stable-to-filtration oil-in-water emulsion containing about 14+2 weight percenk Prosol 172 oil, a mineral oil based neat oil sold by Mobil Oil Co., containing about 6.5 to about 7 weight percent total oleic a~id and oleic acid soaps, virtually all of which are initially present as the soaps, was used for making bodies ~ -for two-piece aluminum cans by the draw and iron process.
About 1.5 million cans per day were mader with the emulsion - being treated using the technology of U. S. Patents 3,408,843 ; and 3,409,551, i.e , stabilization and~f1ne filtration through diatomaceous earth filters. ~Over the course of a week, there was a leakage of about 630 gallons of gear lube oil into the approximately 6000 gallon emulsion. During this time about 350 gallons of the neat soluble oiI was ~ . .
addedr mostly coming into the~sy~stem from the lubrication of the cups, i.e., the workpiece.~ The lubriaity agents in~the coolant-lubricant became out of balance principally, it :
is believed, as a result of the lea~age of gear Iube oil ~ ~ into the coolant. Using infrared absorption, it was détermined that the total lubricity agent in the circulat-ing emulsion had dropped to 4.25 weight percent of the emulsified oil phase. This lowered lubricity agent con-tent affected the operation of the body makers, also known as the ironers.
:~
Laborator~ Runs Various compounds were evaluated as carriers for use w1th oleic acid. Solutions were prepared con-taining two parts carrier, by volume, per part of oleic acid. Emulsicns were prepared containing water and, based ~: . . .

18,009-F ~ -16-.
on the total weight of the emulsion~ 10 percent Texaco 591 neat oil, which is a mineral oil based neat oil con-taining about 7 percent b~ weight total oleic aaid plus oleic acid soaps, substantially all of said 7 percent being present in the soap form~ rrhe solutions were slowly added to respective samples of the emulsion, with continuous agitation, in amounts so that based on the original weight of the oil phase in each sample, an additional 1, 5, and lO percent oleic acid was added~to respective samples~ As a control, I0 ~ oleic acid was added directlyr i.e. without a carrier vehicler to three samples of emulsion in amounts of 1, 5, and 10 per-cent respectively. In each instance, agitation was continued for about 5 minutes after addition of the additive, and the sample placed in a clean laboratory bottle for storage.
A polyoxyalkylene~glycerol of the type herein-~
above described having a nominal average molecular weight of about 2600, diethylene glycol n-butyl ether, and~dLethyl-ene glycol di-t-butyl ether were each found to be effective as carrier vehicles for the oleic acid~ Suah solutions ~
were all readily taken up by the emulsion at all three levels of additive addition, and remained stable even after 16 weeks without agitation, except at the 15 percent l~evel where slight Sreaming eventually occurred in~each. ~ By "slight creaming" is meant the~sample showed no sharp line of separation or increase~in particle size upon vlew-ing without magnificatlon, although that part of the emulsion near the top of the bottle was slightly different in appearance from that more near the bottom. The creaming ' ~ ` `

~ . ~
18,~09-F -17-~` .

~067480 was not so severe as to be considered an unaccepta~le separation, and a uniform emulsion was once again immediately obtained up`on mild agitation.
In contrast, a slight separation was abserved within a few minutes after agitation was ceased, in the conkrol to which had been added only l percent oIeic acid without a carrier. Large, clear yellow oîl puddles, e.g., several had d1ameters of l to 5 millimeters or more, formed on the surface of the control to which had been added l0 percent oleic acid without a carrier. The control to which had~been added 15 percent oleic acid withcut a carrier ~ -developed a yellow oil slick covering almost the entire surface of the fluid.
From the foregoing, lt is readily apparent that oleic acid is much more effectively added to a neat oil-:
in-water lubricant-coolan-t emulsion using the~method of the present invention~than by adding the oleic acid directly to the emulsion.
Other compounds tested in a similar manner and ~20 found to be ineffective~ or at best of only negligible effectiveness, in enhancing the incorporation of oleic acid into such an e ulsion included ethylene glycol methyl ether ana diethylene glycol ethyl ether (both monoalkyl , ,:
- ethers of a polyoxyalkylene glycol, but having less than four carbon atoms in the alkyl group); diethylene glycol methyl t-butyl ether (a dialkyl rather than a monoalkyl ether); and bis-[2-(methoxyethoxy)ethoxy] methaneD
- :

: ~ :
.
.
. , 18,009-F -18-~". .

Claims (18)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A method for adding a substantially water--immiscible fatty acid-type lubricity agent to the dis-continuous neat oil phase of a neat oil-in-water lubri-cant-coolant emulsion for use in metalworking operations wherein a workpiece is contacted by a tool, comprising adding a solution to the emulsion, said solution comprising (A) at least one free fatty acid and (B) a liquid in which said Component (A) is readily soluble, selected from the group consisting of (i) at least one polyoxyalkylene glycerol, (ii) at least one monoalkyl ether of a polyoxyalkylene glycol where the alkyl group has at least four carbon atoms and the alkylene group has at least two repeating units, and (iii) diethylene glycol di-t-butyl ether, said liquid being further characterized in that it is com-patible with the emulsion, with the work-piece, and with the tool, the concentration of Component (A) in the solution and the amount of solution added to the emulsion being mutually selected so that sufficient fatty acid-type lubricity agent is added to the oil phase of the emulsion to attain a preselected concentration of the fatty acid-type lubricity agent in the oil phase of the emulsion without adversely affecting the emulsion.

2. The method of Claim 1 wherein the neat oil contains a light mineral oil as a base oil

3. The method of Claim 1 wherein Component (A) is characterized by a melting point of about 20°C or less and comprises oleic acid.

4. The method of Claim 1 wherein component (B) is diethylene glycol di-t-butyl ether, diethylene glycol n-butyl ether, or a polyoxyalkylene glycerol of the formula .

5. The method of Claim 4 wherein the polyoxy-alkylene glycerol has a molecular weight within the range of from about 2000 to about 3000, and wherein the solution contains from about 0.1 to about 20 parts of the glycerol per part of Component (A), by volume.

6. The method of Claim 4 wherein the molecular weight of the glycerol is about 2600, and wherein the solution contains from about 0.2 to about 2 parts of the glycerol per part of Component (A), by volume.

7. A method for working metals wherein the metal is substantially simultaneously contacted with a tool and a neat oil-in-water lubricant-coolant emulsion containing at least one water-immiscible fatty acid-type lubricity additive in the oil phase of said emulsion, wherein the coolant is collected, filtered and reused in a continuous system, and wherein the lubricity additive is subjected to depleting conditions as the emulsion is used, comprising the steps of:
maintaining a preselect d concentration of the lubricity additive in the oil phase of the emulsion by adding to said emulsion, said additive solution of Claim 1.

8. The method of Claim 7 wherein the metal being worked is aluminum or a predominately aluminum alloy or steel.

9. A method for maintaining a preselected amount of free oleic acid and soaps thereof in the oil phase of a recirculating, stable-to-filtration, neat oil--in-water lubricant-coolant emulsion for use in metal-working operations wherein a workpiece is contacted with a tool, comprising adding to said emulsion while said emulsion is in use, an additive solution comprised of (A) oleic acid and (B) a liquid in which the oleic acid is readily soluble, selected from the group consisting of (i) at least one polyoxyalkylene glycerol, (ii) at least one monoalkyl ether of a polyoxyalkylene glycol where the alkyl group has at least four carbon atoms and:
the alkylene group has at least two repeat-ing units, and (iii) diethylene glycol;
di-t-butyl ether, said liquid being further characterized in that it is compatible with the emulsion, with the workpiece, and with the tool, the concentration of the oleic acid in the solution and the amount of solution added to the emulsion being mutually selected so that when a soap:free acid equilibrium is attained, sufficient oleic acid is added to the oil phase of the emulsion to restore the oleic acid and oleic acid soap content of the oil phase to the respective preselected levels.

10. The method of Claim 9 wherein the emulsi-fied neat oil comprises from about 0.5 to about 20 percent by weight of the emulsion.

11. The method of Claim 9 wherein the emulsion is employed in the hot rolling of aluminum upon a reversing mill and wherein the total concentration of free oleic acid and oleic acid soap in the neat oil phase in the emulsion is maintained at from about 1 to about 3 weight percent of said phase.

12. The method of Claim 9 wherein the emulsion is employed in the hot rolling of aluminum on a tandem mill and wherein the total concentration of free oleic acid and oleic acid soap in the neat oil phase of the emulsion is maintained at from about 3 to about 5 weight percent of said phase.

13. The method of Claim 9 wherein the emulsion is employed in the cold rolling of steel on a tandem mill and wherein the total concentration of free oleic acid and oleic acid soap in the neat oil phase of the emulsion is maintained at from about 8 to about 14 weight percent of said phase.

14. The method of Claim 9 wherein the emulsion has a pH of from about 8 to about 9 and is employed in an aluminum can making operation; wherein the total concentration of oleic acid and oleic acid soap in the neat oil phase of the emulsion is maintained at from about 6 to about 13 weight percent of said phase; and wherein the concentration of oleic acid is maintained at from about 1.5 to about 10 weight percent of said phase.

15. The method of Claim 9 wherein the neat oil contains a light mineral oil as a base oil, wherein the molecular weight of the polyoxyalkylene glycerol is about 2600, and wherein the additive solution contains from about 0.1 to about 20 parts by volume of said glycerol per part of oleic acid.

16. The method of Claim 9 wherein the neat oil contains a light mineral oil as the base oil; wherein the emulsified oil phase of said emulsion comprises from about 5 to about 15 weight percent of said emulsion;
wherein the total concentration of oleic acid and the soaps thereof in said phase of the emulsion is maintained at from about 7 to about 10 weight percent of said phase; and wherein the concentration of oleic acid is maintained at about 3 to about 8 weight percent of said phase.

17. The method of Claim 9 wherein the molecular weight of said glycerol is about 2600 and wherein the addi-tive solution contains from about 0.1 to about 20 parts by volume of said glycerol per part of oleic acid.

18. The method of Claim 17 wherein the additive solution contains from about 0.2 to about 2 parts by volume of glycerol per part of oleic acid.