SE437672B - SET TO STABILIZE A FLUID COMPOSITION OF A DISPERSION OF OIL AND WATER FOR METAL WORKING - Google Patents

Description

25 U 'b! Ln 40 'areas 2114> .; §¿fi eüa¶'r \ 8300937-3 for lubricating and cooling various metal surfaces in metalworking processes, such as cutting, turning, drilling, grinding, hardening and the like. Previously, compositions for metalworking have not shown any longer service life. For example, in use, the oil and water emulsions or dispersions usually deteriorate or even degrade physically within a limited period of time, which can even be as short as a few weeks. The deterioration of the emulsions has been attributed to a number of causes present in metalworking processes, including the incorporation of foreign materials, such as sand or dirt, metal particles, polyvalent metal ions, bacteria and the conditions of metalworking, including pressure and temperature. etc, as well as other factors.

The shortcomings in long-term stability of metalworking compositions have therefore led to serious direct and indirect inconveniences for their use in metalworking processes. For example, the short life of metalworking fluids increases the labor and material costs associated with the handling and utilization of the fluids in metalworking systems. Furthermore, the degradation of such fluids causes an increase in the wear on the metalworking apparatus itself and reduces the service life of the tools due to the quality losses of the metalworking fluids. Other additional effects of the deterioration of metalworking fluids include increased disposal of workpieces, reduced production and increased costs associated with wasted time, costly disposal of discarded fluids, occupational safety problems in their use, and pollution of the environment. Therefore, metalworking compositions which have an extended service life and are stabilized against degradation due to the conditions of metalworking, as well as other desirable properties, are of great importance, not only for the industry in which they are used, but also for the surrounding environment.

Various attempts have been made in the past to improve metalworking compositions and to attempt to overcome or minimize the direct and indirect inconveniences of using such metalworking fluids. Examples of prior art patents in this field are U.S. Pat. Nos. 2,688,146, 3,240,701, S 244,630 and 3,365,397. Such patents and also other attempts have been made to overcome the factors which contribute to the emulsions. deterioration and degradation. However, the results of such experiments have been unsatisfactory, and there has been a need for improved compositions for metalworking which would give free rein and overcome new results. the present problems and inconveniences.

The antimicrobial activity of certain metal complexes, such as the dialkali monocarbon (II) citrates, has been determined by their toxic and growth inhibitory activity against a variety of microorganisms in a medium of oil emulsions, used as coolants in various processing processes. The effect of the metal complexes in industrial coolants has been determined where microorganisms have been shown to be able to reproduce. As essential, it has also been shown that at alkaline pH values under the conditions for metalworking, the metal complexes were remarkably effective.

The present invention relates to fluid compositions for metalworking and to methods for stabilizing them, and further develops the discoveries in this field. According to the invention, emulsions for metalworking, i.e. dispersions of oil and water, are stabilized by the addition of an effective stabilizing amount of a metal complex of a metal ion and a polyfunctional organic ligand. These metal complexes are also described in Swedish patent application 7709143-7. The stabilizing metal complex is characterized by very unexpected dissociation properties by protons in aqueous solution, whereby a controlled release of metal ion to the oil and water dispersions is achieved while imparting stability during the metalworking to the dispersions. These dissociation properties are illustrated by a sigmoid-shaped curve in a right-angled coordinate system of the negative logarithm of the metal ion concentration versus the negative logarithm of the hydrogen ion concentration, ie a pM-pH diagram.

Quite unexpectedly, it has been found that fluids for metalworking can be stabilized against attack and deterioration from various causes. Thus, according to a feature of the invention, fluids for metalworking have been stabilized against degradation by a generally acting stabilizer additive of metal complexes. As also stated, for example, certain metal complexes are active as antimicrobial agents in emulsions for metalworking. It has also been found that these metal complexes provide other stabilizing properties to the fluids for metalworking and provide benefits and improvements that have hitherto not been achievable in fluids for metalworking. This resistance is achieved not only against bacteria, but the fluids are stabilized against degradation by physico-chemical and physical causes, associated with the conditions in the processing of metals, including then heat, pressure, and the presence of particles from the processing, polyvalent ions , etc. Bestän-, .-, ~, av _ * '- ~ .v ,,, ..,.' .VVLL:.: ... »_ .. '.« - V »fw-r t, n,» "?:?'>": 'F “" "~.?' vggymï, 'm1 -nga “_ ..- i - f ... s -__ 10 15 20 25 50 40 8300937-3. The suitability of fluids for metalworking in accordance with the present invention has been found to be significant. For example, for industrial refrigerants, the service life of fluids has been extended from a period of, for example, a few weeks to almost a year or more, and the present results indicate that the service life can even be extended indefinitely. The stabilizing metal complexes themselves are very resistant at relatively high alkaline pH values of the order of about 9 or 10 to about 12. In an alkaline pH range above 7 to about 9, within which fluids for metalworking are intended to operate, they provide stabilizing complexes very beneficial stabilizing effects on the fluids for metalworking. It has also been found in this context that compositions for metalworking can be provided with a stabilizing metal complex in very small amounts, namely amounts which may be below those which would exert a biocidal action, but notwithstanding this, such metalworking fluids can be stabilized against degradation, caused of all the factors in the environment for metalworking.

Thus, the object of the compositions and methods according to the invention is to provide stability to otherwise degradable oil and water dispersions, which can be subjected to degradation for a number of reasons. For example, fluids for metalworking can be imparted biological stability by incorporating the metal complexes even in amounts less than biocidal amounts. On the other hand, a general emulsion stability can be achieved by incorporating amounts of the metal complexes to stabilize the emulsions against degradation by external sources, such as metal particles, polyvalent metal ions and the like. Furthermore, fluids for metalworking can be given resistance properties to extreme pressures and temperatures by using the stabilizers according to the invention. According to another feature of the invention, the compositions of the invention also maintain the required pH control in fluids for metalworking by a buffering action, and reduce the chemical action of other components on the emulsified particles, which action would otherwise have a tendency to decrease stability. These and other advantages of a stabilizing effect are achieved in accordance with the invention, and will become more apparent from the present description. The theories or underlying causes of the relatively unexpected activities of the metal complex stabilizers of the invention have been investigated. Although the intention is not to limit the invention by any theoretical reasoning, it is believed that this may facilitate a further understanding of the features and unexpected results obtained in accordance with the art. the invention. For dispersions of oil and water (whether they consist of oil in water or water in oil) it is assumed that such dispersions can be either biodegradable, chemically degradable by chemical components in the fluid, and physically degradable by such conditions as mechanical forces. , or by combinations of two or more of these factors. It is known that such dispersions of oil and water contain emulsifiers, and that these emulsifiers are typically of the anionic and / or nonionic type. Due to their hydrophilic-hydrophobic nature, the emulsifiers enable the suspension of the oil particles in a continuous phase of the liquid. Electronegative moieties, such as carboxyl and sulfonate groups in the emulsifier, provide electronegative surface charges to the oil droplet. The combined electronegativity of such an emulsified particle is commonly referred to as the zeta potential. This zeta potential is related to the force and distance over which the emulsified particles can repel each other and thus prevent flocculation. This of course constitutes an excessive simplification of such dispersions of oil and water. However, it would have been expected that the addition of a highly charged divalent metal cation or a similar component in the stabilizing metal complexes would interfere with the stability of the emulsion and possibly cause flocculation by neutralizing the highly electronegative nature of the emulsion droplets.

Thus, in a broader sense, the invention relates to a method for stabilizing dispersions of oil and water and stabilized compositions, by adding thereto a polyvalent metal ion, which forms a coordinative bond with the electronegative emulsifier. The stabilizing effects of such a coordinative bond are achieved due to the fact that the electronegativity still exists to prevent the degradation of the emulsion and furthermore that the other influential points of the emulsifier are now blocked against enzymatic degradation and enable the metal ion to be transported as a lubricant means in the interface layer for the interface between tool and workpiece.

This method is attributed to the highly electronegative nature of the emulsified droplet, which either initiates or contributes to the dissociation of the metal complex and enables a coordination of the metal cation with the electronegative parts of the emulsified droplets, for example carboxyl, sulfonate or alcoholic hydroxyl groups. with the emulsifier. This blocking of these biologically actuable or functional groups prevents an enzymatic degradation of these structures azooazv-3 6 such structures, this enzymatic degradation being common in and associated with microbial metabolism. However, it is quite unexpected that the addition of the metal complexes or the introduction of such metal ions has been found not to cause emulsion degradation of the electronegatively charged emulsion droplets. This is because although the amount of positively charged ions in association with the electronegative surface of the oil droplet is sufficient to achieve a biological stability, it is not sufficient to reduce the electronegativity of the particle to degrade the emulsion. Therefore, the effect of forming coordinative structures with emulsifiers is apparently a new method of stabilizing emulsions.

It has also been found that an incorporation of the stabilizers of metal complexes according to the invention contributes to resistance properties of the emulsion to extreme temperatures and pressures during metalworking processes. Such resistance to extreme temperatures and pressures is provided by the coordinated structure of metal ions and emulsifiers in the stabilized metalworking compositions of the invention. These properties are exhibited by the metal cation or metal complex, which is transferred to and then associated with the electronegative individuals of the emulsified droplets, as indicated above. The emulsified droplets are continuously brought into intimate contact with the interface between tool and workpiece that exists in metalworking processes. During the heat and pressure present in the metalworking process, for example, the copper associated with the emulsified droplets enters the interface in an oxidation-reduction process which acts to lubricate the metal surfaces, but without any degradation of the emulsion to an unusable state. In practice, moreover, probably due to the formation of highly reactive cations at the interface between tool and workpiece in each machining process with metallic substrates, the metalworking fluid is provided with metal ions, which by displacement have a tendency to replace the cations contained in the metal complex and further enables them to migrate and be associated with electronegative structures of the emulsified particles, so that in practice they cover them with cations.

HHHU the chemical nature of the metal complex stabilizer is such that it is highly soluble in aqueous systems, due to its unique proton dissociating properties at pH under the metalworking conditions, it dissociates easily so that metal cation is transferred to the oil phase of the emulsion from the aqueous phase. This surprising phenomenon has been shown by two-phase extraction of the oil and water emulsion system, treated with the metal complex at concentrations which are even considerably below those which are found to have biocidal effects. More specifically, emulsions have been tested which have been treated with disodium monocopper (II) citrate at a content which gives about 50 to about 100 mg of Cu 2+ per liter of emulsion, for example when 1/10 - 1 / S of the biocidal dosage in a particular medium. Examination of the mixture of metal complexes of emulsions by two-phase extraction using chloroform or other chlorinated hydrocarbons shows that the copper is present in the organic phase. Although the exact mechanism of this reaction has not been specifically elucidated, however, the biological, chemical and physicochemical stability obtained by treating emulsions with the metal complexes of the invention has been empirically observed. Furthermore, the biostability imparted by less than biocidal or biostatic amounts of metal complexes is considered to be remarkable and must be attributed to reactions of components in the organic phase which render them insensitive to bacterial attack as opposed to a direct cation reaction with microbial individuals. in connection with the aqueous phase. Due to their unique properties in water, the anionic ligand units in the stabilizing metal complex also enable polyvalent cations formed in the metalworking process to react with them and chelate. For example, it has been noted above that polyvalent metal cations can be formed in the machining process, such as cations of iron, aluminum and the like. On the other hand, other such polyvalent metal cations, such as calcium and magnesium, may be present in the aqueous medium used in metalworking fluids. These ions may otherwise be referred to as "formed ions", i.e. those formed by machining processes, or "native ions", i.e. those which are present in themselves in the aqueous media of the fluid compositions for metalworking. These polyvalent cations normally interfere with the metalworking processes and further contribute to the instability of the emulsified particles. However, it has been empirically established that the stabilizers of the present invention make the emulsions resistant to disturbances of such polyvalent metal ions, i.e. those which are either formed or which are themselves present in fluids for metalworking. Thus, the stabilizing components in the metalworking compositions of the present invention have a tendency to dissociate not only to impart stability to the emulsified particles through their association. »\ -. : ai .- - 1g_HÅ f, hå ?; 0 ~ “mi Gives years? 10 15 20 25 30 35 40 8300937-3 ß tion with them and the associated advantages, but the complexes also bind unwanted polyvalent components in the media.

According to another preferred feature of the invention, the anionic component of the metal complex provides a buffering effect to maintain the pH of the metalworking composition at a level which is very suitable, normally at about 8.5. Such buffering prevents the action of acidic components, which may otherwise adversely affect the processed metal. Even health risks such as skin irritations are minimized by using a pH that is kept mildly alkaline.

The metal complexes used as a stabilizer in the compositions and methods of the invention release large amounts of metal ions from their coordinative structures at a pH of from about 4 to about 9, and most preferably at a pH between about 7 and about 9 or 10, i.e. the values which normally occurs in metalworking compositions. Due to their unique dissociation properties, which are illustrated by the sigmoid-shaped curve in a pM-pH diagram, these agents provide, when required, a controlled release of metal ions at a pH that is compatible with conditions for metalworking. Furthermore, due to the organic ligand type of the metal complex, as stated above, the activity of other polyvalent metal cations or other foreign components in the fluids for metalworking will be inhibited, which would otherwise either cause instability or adversely affect the stability of the emulsions. for metalworking. Therefore, the metal complex stabilizers of the invention are distinguishable from other metal complexes in which metal cations are complexed with such organic ligands represented by ethylenediaminetetraacetic acid (EDTA), diethylenetriaminopentaacetic acid (DTPA), other amino acids or the like, and which have a relatively high stability or chemical resistance and does not make the metal ion available in amounts that are coordinatively bound to the electronegative emulsifiers to any significant extent, and which therefore cannot give the emulsion stability.

Such known complexes also do not provide a controlled release of metal ion or have dissociation properties as illustrated by a sigmoid-shaped pM-pH diagram. Due to their stability and chemical resistance, such known metal complexes tend to dissociate to a lesser extent in a relatively linear way. Furthermore, the present invention provides complexes which in high concentrations can be dissolved in water due to their ionic nature and yet remain in stable form. This solubility property, especially in alkaline medium, as in the present case, enables the preparation of concentrates, azooazv-3 which in an emulsion system can, when required, give metal ions to impart stability to the emulsion in metalworking. Such solubility properties are to be distinguished from the relatively insoluble metal compounds previously known in which metal cation-anion components are used and which are substantially insoluble in such media, or the metal complexes which, although they may be soluble, binds the metal ion in such a complex state that it is only to a small extent dissociated, and therefore is hardly available for the release of metal ions and coordination with the emulsified particles.

The term "metalworking fluid compositions" as used in the present specification and which is well known to those skilled in the art means those fluids which serve to lubricate, cool, clean and prevent degradation of metal surfaces during metalworking processes. Such fluids are well known to those skilled in the metalworking industry.

There are two basic areas for metalworking, namely mechanical processes such as cutting, drilling, reaming, turning, milling, reaming, grinding, etc., together with forming, bending, rolling, drawing and the like, as well as non-mechanical processes. , for washing, cooling after heat treatment and the like.

It is generally believed that compositions for metalworking in mechanical processes provide lubricating, cooling, cleaning and rust inhibiting functions, while in non-mechanical processes they primarily provide cleaning, rust inhibiting and cooling functions.

The oil and water dispersions which form the metalworking compositions containing the stabilizer in accordance with the invention may, as stated above, be of either the type of oil in water or of the type of water in oil. These dispersions have commonly been referred to as oil emulsions or soluble oil compositions. Such compositions are essentially characterized by two phases, i.e. a liquid-in-liquid system, in which there is a dispersed phase and a continuous phase. Conventionally, they have been commonly referred to as emulsions, when the particle size of the dispersed phase is of the order of magnitude greater than about 0.1 microns in particle size. When the particle size is in a colloidal range from about 1 nm to about 0.1 μm, the dispersion may be of the colloidal type. Whether it is desired to designate them as a coarse emulsion or colloidal suspensions, the fluid compositions consist essentially of organic phases and aqueous phases, i.e. of a two-phase system, consisting of a liquid in another liquid, with which the first liquid is immiscible. . Furthermore, the term "oil" is intended to include a large group of substances, whether or not they are «., _., __ - Y" '\ _ f' ~ rv »., ._, 1 -" "* = fl 2 F "" "" '' f ll * 10 20 25 50 40 * rr- "Mræšgïggllrolïßï-» l-EP-iïe "" "i 8300937-3 re of mineral, vegetable, animal, essential or edible origin. used for metalworking, however, usually originates from the group of mineral oils, either of petroleum or derived from petroleum, and especially then of the group of lubricating oils.

These dispersions include emulsifiers, which are typically of the anionic or nonionic type. In the case of the anionic agents, the anionic moiety has the polar character required to produce the desired surfactant effects, and it provides electronegativity to the suspended oil droplets or particles. In non-ionic agents, the electronegativity is provided to the oil particle through a high density of the inherent electronegativity. Most commonly, the emulsifiers used in metalworking emulsions are nonionic and / or nonionic surfactants. The anionic surfactants contain a negatively charged, ion-containing moiety and an oil-dispersible or oleophilic moiety in the molecule of the surfactant.

The surfactant may be (1) saponified fatty acids or soaps, or (2) saponified petroleum oil, such as sodium salts of organic sulphonates or sulphates, or (3) saponified esters, alcohols or glycols, the latter are well known as anionic, synthetic surfactants. Examples of these anionic detergents include the alkylaryl sulfonates or amine salts thereof, such as sulfonates of dodecylbenzene or diethanolamine salts of dodecylbenzenesulfonic acid, the sulfates of straight chain primary alcohols or fatty alcohols (G6-C24), which are products of the oxoprocess (e.g. sodium lauryl sulfate). A saponified, light petroleum oil, such as sulfonated petroleum distillation residue (eg mahogany oil), is common. In general, the majority of surfactants or emulsifiers are anionic type of alkali or amine salts of organic acids. Sulfonic acids are often used in which the structure of the organic moiety is not well known, as is the case with the well-known "petroleum sulfonates". Most of these sulfonates contain many chemical individuals, and most of them are given the group name "alkylaryl sulfonate". This simply means that a paraffinic hydrocarbon is bound to an aromatic or benzene hydrocarbon nucleus, usually benzene or naphthalene, and that the aromatic moiety has been sulfonated. Examples of saponified fatty acids (C6-C24) are the sodium or potassium salts of myristic acid, palmitic acid, stearic acid, oleic acid or linoleic acid or mixtures thereof. This group of anionic surfactants also includes alkali and alkaline earth metal salts of neutral phosphoric acid esters of oxyalkylated (oxyethylated) high alkylphenols or aliphatic monohydric alcohols. 10 26 25 so 35 40 i, 8300937 * 3 Examples are potassium and sodium salts of phosphate esters of isodecyl alcohol and ethylene oxide adducts. Thus, here anionic surfactants or emulsifiers include soaps or synthetic surfactants from the group of alkali, alkaline earth and amine salts of organic sulfonates, phosphates or sulfates.

The nonionic surfactants suitable for use usually have hydrophilic moieties or side chains which are usually of the polyoxyalkylene type. The oil-soluble or dispersible portion of the molecule is derived from either fatty acids, alcohol, amides or amines. By appropriately selecting the starting material and adjusting the length of the polyoxyalkylene chain, the surfactant moieties of nonionic surfactants can be varied in a well known manner. Suitable examples of nonionic surfactants include alkylphenoxy polyoxyethylene glycols, for example ethylene oxide adducts of either octyl, nonyl or tridecylphenol and the like.

These indicated nonionic surfactants are usually prepared by a reaction between alkylphenol and ethylene oxide. Other specific examples of nonionic detergents include glycerol monooleate, oleyl isopropanolamide, sorbitol dioleate, alkylolamides prepared by reacting alkanolamides such as monoisopropanolamine, diethanolamine or monobutanolamine with fatty acids such as oleic acid, pelargonic acid, lauric acid and elaidic acid.

The metalworking compositions are typically composed in a well known manner of a combination of a lubricating oil, such as a solvent-refined paraffinic or naphthenic oil, an anionic type emulsifier, as described above, and special additives, including conventional anti-corrosion agents and the like. . In the industry, such compositions are usually used as concentrates, and these are then mixed with a sufficient amount of water to give an emulsion. The amount of water will vary, depending on various factors and on whether the emulsion is of the oil-in-water or water-in-oil type. For example, the oil phase may vary over a wide range from about 1% to about 95% or more by weight, the remainder being the aqueous phase and other amounts of the emulsifiers and additives. Usually the amount of an emulsifier is in the range from about 5 to about 50% by weight. In lubricating and cutting oil compositions, the concentrate is mixed with a sufficient volume of water to give an emulsion which, by volume, contains about 90 to about 99 percent water and 10 to 1 volume percent of the oil composition. The constituents of the oil concentrate usually comprise about 30 to about 90 percent lubricating oil, about 10 to about 25 percent emulsifier and the remainder possibly consisting of --- ~ »...._ r ..___, Pål? WL szooesv-z 12 10 20 25 30 35 40 ma Quarrfj; 1-11 _ additives of previously specified type.

The stabilizing metal ion is present in the lubricating oil composition in a sufficient amount to achieve stability in metalworking. This effective amount can vary, depending on a number of factors, including the particular metal being processed, the pH, impurities and amounts of oil and water phases, emulsifiers, metalworking cations, the specific metal complex and the like. Generally, however, for example, in an emulsion prepared from an oil concentrate composition of the type described above, the stabilizing metal ion is usually present in an amount in the range of from about 10 to about 500 mg of metal ion per liter of oil phase.

When a metal complex provides the metal ion, the complex is added to the aqueous phase. After such addition, the metal ion migrates to form coordinative bonds with the emulsifier as described above, so that an equilibrium is achieved between the oil and water phases. As the metal ion is depleted from either phase during metalworking, more complexes can be added to maintain the effective stabilizing amount. More specifically, in a cutting or lubricating oil composition for processing iron and consisting of about 97% by volume of water and 3% by volume of oil, as indicated above, with about 10-15% of emulsifier and with disodium monocopper (II) citrate as a stabilizing agent, a toxic effect against bacteria to be obtained with 500 mg of copper per liter of aqueous phase. As stated above, however, the emulsion can be given stability in metalworking with as little as 10-100 mg per liter of the copper cation, or considerably below the toxicity level. However, amounts of the metal complexing agent or ion outside these ranges may also be used.

The stabilizers according to the invention for metalworking can be added to the emulsion in several ways. For example, the stabilizing metal complex can be added to the aqueous phase of the emulsion before the preparation, after which the oil concentrate with the oil, the emulsifier and the additives can be added, after which the emulsion is prepared, optionally with some mixing. On the other hand, the emulsion can be prepared first and the stabilizing metal complex is then added to the formed emulsion. The emulsion is prepared so that the metal complexing agent is not degraded. Specifically, in the case of metal complexes of zinc, nickel and copper citrate, these are relatively resistant under alkaline conditions up to a pH of about 12, but still give the desired stabilizing effect to emulsions for metalworking in an alkaline pH up to about 9 or 10. Thus, the pH of the alkaline side is adjusted from about 7 to about 10 in the fluid compositions so that the metal complex does not first decompose and so that a pH in approximately the range of middle of about 8.5 is obtained.

In a presently preferred embodiment, the agent according to the invention comprises a monometallic complex of a polyvalent metal and a polyfunctional organic ligand in a ratio of 1: 1 between metal and ligand, the complex having dissociation properties which are illustrated by a sigmoidal curve in a pM pH diagram. A specific example of a metal complex is dialkali monocopper (II) citrate, such as disodium, dipotassium or dilitium monocopper (II) citrate. These dialkali monocouples (II) citrates have a dissociation ability which is illustrated by a sigmoid curve, in which the two directions of the curve meet at a point in the pH range from about 7 to 9. It has been found that these monocouples (II) complexes in basic medium with a pH of the order of about 9 to about 12 are very stable, ie have an effective stability constant Keff of the order of about 1012 to about 101.Ee Keff for these mono-copper (II) citrate complexes at a pH of however, about 7-8 is of the order of about 105 to about 108. Thus, at or about a pH of about 7-8, the effective stability constant of the monocopper (II) citrate complex is considerably lower (one thousand to several hundred thousand times lower), and a Substantial concentration of free Cu2 + is available for toxic or stabilizing activity.

For example, about 10% of the copper in the complex is in the ionized state at or around pH 7, while about 0.1% of the copper is ionized at or around pH 9. This would not be the case for an EDTA or polyamine complex of a polyvalent metal such as copper, as its stability constant (1014 to 1016) will vary only slightly in the normal pH range of 7 to 9. Such EDTAs complexes do indeed show a pH effect on the stability constant, but it is illustrated by a smooth monotonous curve and achieves a limiting effect on proton-induced dissociation at pH values from about 7 to about 9, and gives only from about 0.001% ionized units at or around pH 7 to as little as 0.00001% ionized units at or around pH 9 It will be appreciated that the stabilizing or antimicrobial complexes will be effective over a pH range of from about 5 to about 12. Above pH about 12 the complexes have a tendency to be destroyed by the alkaline medium. and precipitates therefrom as hydrated metal oxides. Below pH about 6, i.e. about 3 to about 6, the volatility of the metal complex causes a high content of free Cu2 + in solution, which will affect the biostability and other stabilizing functions, as stated above. within the intermediate range from about 7 to about 9, the regulated “release is most effective. Thus, these complexes provide a controlled release of metal ion in an amount of about 10 to about 0.1% of a complexed metal in the pH range of about 7 to 9 and this metal ion is then available for coordinating, antimicrobial and stabilizing effects.

In accordance with the present description and the presently preferred embodiment, it is apparent that other metal complexes of polyfunctional organic ligands fall within the scope of the invention when they exhibit dissociation properties characterized by a sigmoid curve in a conventional pM-pH diagram. For example, on the basis of the complex of monometallic-polyfunctional organic ligand according to the invention, other metal ions of the monovalent or polyvalent type can be used, especially when divalent and polyvalent cations, such as zinc, nickel, chromium, bismuth, mercury, silver, cobalt and others similar metal or heavy metal cations. The complexes of heavier metals are considered more toxic than those of the lighter metals. Other polyfunctional organic ligands may be used in place of the citric acid specifically exemplified as a preferred embodiment of the invention. However, the citrate compounds provide a preferred buffering action at a pH of about 8.5, which is an additional advantage of metalworking fluids stabilized with such metal complexes. Other polyfunctional ligands include the larger group of alpha- or beta-hydroxy-polycarboxylic acids, to which group citric acid belongs. Other functional substituents, such as alpha- or beta-amino, sulfhydro, phosphinol, etc., may also be included as substituents in the molecule of the metal complexes of the invention, and similar results may be obtained. From the formula point of view of the metal complex in the lex, the monometallic complex of copper and citric acid generally corresponds to a complex formula illustrated by either of the structural formulas (A) and (B). 5 f »> lå e; '»Labs u 1. - 10 15 8300937-3 (A) °% C, .0 \ o / H o * c-CHZ- ç -moln / zv (B) From considerations of free energy appears (A) - form constitute the preferred. A single proton introduced into the complex structure illustrated by either the form of (A) or (B) prevents the formation of stable 5- or 6-membered coordinate rings. With the introduction of a proton, only 7-free rings can be inserted by coordinating the electron donor of the aceum, and such 7-free rings are volatile. Therefore, the complex molecule dissociates and releases the metal ion to its toxic or stabilizing effects.

In comparison, metal complexes of EDTA or other polyamines require four or more protons and consequently a higher acidity to dissociate the complex, and this is the reason for the low pH effect that such complexes show in a pM-pH diagram.

The structural shapes (A) and (B) can be more generally illustrated by the following models: Model A 10 15 20 8300937-3 w Model BF “Z (R) X: M (R) In these models, the solid line segments denote a chemical bond between elements in the structural structure of the molecule, X, Y and Z denote electron pair donors, (R) denotes any elemental or molecular entity or group, and M denotes a metal, and wherein the proton affinity of X is higher than that of Z, Y or R. It appears because other Lewis base proton pairs and other metal ions can in these structural models replace oxygen, divalent copper or even the carbon atoms to form a molecular model which will be similarly dissociated upon introduction of a proton, or units which occur similarly, which is expressed in the sigmoid-shaped curve in a pM-pH diagram.

The molecular models thus constitute alternative expressions for the stabilizing agents according to the invention.

The invention and its various embodiments and advantages are further illustrated by the following examples, the detailed description and the drawing, which show the preparation of the complexes and their activity.

PREPARATION OF COMPLEX A. Dilitium monocopper (II) citrate 10 millimoles of lithium citrate were dissolved in 10 ml of water, and to this solution was added 10 millimoles of copper (II) chloride (CuCl 2 '2 H 2 O) portionwise with stirring to form a deep blue solution. This was neutralized to a pH of about 7 with 10 millimoles of lithium hydroxide (LiOH'H 2 O). When this solution was recovered to dryness, a deep blue, to a fine powder was obtained, and the lithium chloride was extracted 5 times with SO ml of dry methanol at 3S ° C. The remaining blue solid product was evacuated to remove methanol and dried. A try semi-crystalline solid product. This solid product was ground to crystallize the salt from systems of water and organic solvent, but the solid product obtained was microcrystalline to amorphous, probably due to the extremely hygroscopic nature of the salt and the high negative charge on the ionized molecule. The following formula is proposed for the 1: 1 complex of copper and citrate, based on 10 15 20 u b! ü) 35 83ÛÛ93? ~ "17 determination of the structure and the analyzes described below.

In Li2CuC6H4O7-XHZO Depending on the degree of hydration, the following formula weights (F.W.) and corresponding percentage of copper contents can be proposed: Li2CuC6H4O7'XH2O F.W. 265.51 for X = 0, '% Cu = 23.93 F.W. 283.51 for X = 1,% Cu = 22.41 F.W. 301.54 for X = 2,% Cu = 21.07 F.W. 319.56 for X = 3,% Cu = 19.88 The detected copper content of various dried samples of the solid complex varied from 20 to 23%. The compound (solid complex 1: 1) was extremely soluble in water. A solution with a strength of up to 2 * molars could very easily be prepared. Up to pH 11.5, there was no effect on the solubility of the compound in water. Above this pH, the complex decomposed to a greenish brown precipitate, probably hydrated Icopar oxides. The 1: 1 solid complex can be used as a stabilizer with or without removal of lithium chloride formed in the preparation.

B. Disodium Copper (II) Citrate (1) Equimolar solutions of copper chloride and sodium citrate were added to water in the same manner as in A above to give a deep blue solution having a pH of about 5. A 50 ml sample of this solution was charged to a separator funnel, after which an equal volume of anhydrous acetm1 was added and the funnel was shaken for mixing. When the whole was allowed to stand, a two-phase system had been obtained, in which a blue liquid phase was present at the bottom of the funnel in a reduced volume of about 25 ml. ml) was slightly cloudy and colorless, while it had been crystal clear before shaking. The blue liquid, which was oily and viscous, was drained from the funnel and collected in a second separatory funnel, while the cloudy supernatant was placed in a beaker and evaporated to dryness over a water bath. An amount of about 25 ml of anhydrous acetone was added to the second separatory funnel, giving an almost instantaneous formation of a plastic-like mass having the bottom of the funnel there, in contrast to the oily liquid. existed. the superphase from the plastic mass was charged into a second beaker and was designated as superphase Z. An addition of distilled water to the plastic-like mass resulted in an immediate redissolution of the material. The total volume of the redissolved substance was adjusted to 25 ml, whereby a viscous, oily liquid was formed again. After recovery to dryness of the upper phase 1, microscopic examination of the dry residue showed the presence of clear and large amounts of sodium chloride crystals. Recovery of supernatant 2 gave a very finely divided, powdery residue which contained a small number of clear sodium chloride crystals. Analysis of the twice extracted blue and oily solution with respect to the copper cold showed that the solution contained about 125 mg of copper per ml, so that it thereby constituted a concentrate of the metal complex, which had originally contained 25 mg per ml.

The large reduction in the amount of sodium chloride in the upper phase 2 showed that most of the contaminating salt by-product had been removed.

A portion of the concentrate was allowed to evaporate, whereby a clear crystalline material was obtained. (2) The procedure of the preceding paragraph 1 was repeated, except that the pH of the first blue solution formed was adjusted from about pH S to about pH 7 with KOH solution to neutralize the formed HCl.

After extraction and collection in the same manner as above, a concentrate of the metal complex was obtained, which on collection gave a clear crystalline material. (3) K fi quimolar amounts of copper sulphate and sodium citrate were combined in the same manner as in paragraph 1, after which the pH was adjusted to about 7 with NaHO. Extraction and collection of the resulting blue solution in the same manner as above gave an amorphous powder which had no visible crystalline structure.

The following formula is proposed for the disodium copper (II) citrate prepared according to the above paragraphs 1-3, based on structural determination and analyzes described below: NaZCuC6HZ07 ° XH2O C. Disodium monozinc citrate Using the following ingredients, a complex zinc stabilizer is prepared , analogous to the copper complex according to B above: PÖÖRQIJALIW _. _ .- 10 15 20 35 8300937-3 19 50 ml. cold water 29.4 g. trisodium citrate dihydrate 13.6 g. zinc chloride (ZnCl2) concentrated HCl NaOH lozenges The zinc chloride was ground to fine particles using a mortar and pestle, and then dissolved in the water, after which the pH was adjusted to between 0.5 and 1.0 with HCl. The sodium citrate was added slowly with the addition of HCl to keep the pH below 1.0. When all the material was dissolved, the solution was slowly neutralized with NaOH / pastels. The material remaining in solution at pH 7.2 was decanted, adjusted to pH 8.5 ~ 9.0, and then extracted with a double volume of a 50:50 solution of methanol and acetone. The material was collected in Buchner funnel using Whatman filter paper number 42. Alternatively, the solution can be vacuum dried at 70 ° C.

D. Disodium Mono Nickel Citrate A nickel complex stabilizer. was prepared with the following ingredients: 40 ml of cold water 38.4 g of anhydrous citric acid 47.5 g of nickel chloride (NiCl2), finely ground NaGH flakes The citric acid was dissolved in the water, and the nickel salt was added slowly under constant monitoring of pH. When all the material was in solution, NaOH flakes were added slowly (to minimize heat generation) to adjust the pH to between 4.0 and 5.0. The yield was about 100 ml, containing about 117 mg per ml of Niz +.

E. Disodium mono-mercury citrate A mercury complex stabilizer was prepared using the following ingredients: 40 ml of water 2.2 g of mercury oxide (HgO) 1.9 g of anhydrous citric acid NaOH pistils The citric acid was dissolved in water, and the solution was heated to at most SOOC. H 2 O was added slowly with vigorous stirring, and allowed to react until the solution was clear. The pH was adjusted with NaOH lozenges to 8.5-9.0, ensuring that the temperature did not exceed 50 ° C. The material can be crystallized by either of the methods described for the zinc complex of C above.

DETERMINATION OF THE DISOCIATION OF THE METAL COMPLEX The dissociating ability of the 1: 1 copper citrate complex prepared by the above methods was determined over a pH range from 3 to 12 using a Copper (II) Specific Electrodepion Copper (II) Specific Electrode. solution of copper citrate complex 1: 1 (0.0068 molar) was adjusted to pH 3, 4, S, 6, 7, 8, 9, 10, 11 and 12, the content of free copper ion then being determined using the copper ion specific electrode The following values for the content of free copper ions in the indicated pH values were obtained, and the negative logarithms of the copper ion contents were determined: pH Cu2 + pM '3 3.2 x 10'3 2.495 4 9.0 x 10'4 - 3.046 5 2 .5 X 10'4 3,602 6 5.3 X 10'5 4.276 7 1.0 X 10'5 5,000 s, s, 0 x 10'8 7.097 9 s, sx 10'12 11.055 10 '9.6 x 10 "13 12,018 11 3,3 x 1o'13 12,482 12 1,34x 10o" 15 '12, s7z From the table data, a pM-pH curve has been calculated to show a dependence between the content of free Cuzi-ion and the pH-value, such as v isas in the drawing. The drawing is a diagram (solid line) in a right-angled coordinate system of the negative logarithm of the metal ion concentration (pM) against the negative logarithm of the vâte ion concentration (pH) at the points given in the table above.

This diagram is a sigmoid-shaped curve showing the proton-induced dissociation properties of the metal complex. At the pH range of about 9-12, the complex is very stable and the content of free Cu2 + is low. At a pH of about 7, the complex is relatively unstable free Cu + + a stabilizing effect. Within the range between about 7 and about 9 is and the dissociation to is considerable, enabling 10 '15 20 25 50 35 40 M azoosv-3 Z + available for controlled release, and from about 10 to Cu about 0.1% dissociation of Cu 2+ from the complex occurs. This unexpected behavior of the dissociation relative to the pH value makes the complexes particularly effective as antimicrobial or stabilizing agents for metalworking compositions.

For comparison, the dashed line shows a curve for a Cu-EDTA complex, as indicated by A. Ringbom: "Complexation in Analytical Chemistry", J. Wiley & Sons, N.Y., 1963, p. 360. It can be seen that the effect of pH on pH-EDTA complexes is illustrated by a smooth, monotonic curve which achieves a limiting effect of proton-induced dissociation at pH about 7-9, whereby only about 0.001-0.00001% ionized units are obtained, for example.

Complex with the ratio of a metal: a citrate has been proposed to be present in dilute solutions according to a publication by M. Bobtelsky and J. Jordan, J. Amer. Chem. Soc¿, volume 67 (1945), page 1824. However, no one has reported the remarkable antimicrobial or emulsion stabilizing activities of these derivatives or their ability to form coordinate structures with emulsified droplets.

Furthermore, further unique properties of such complexes in metalworking fluids have also been discovered, as set forth herein in detail.

Solid metal complexes of dialkalaimonocopper (II) citrate have also been prepared, and such solid forms are highly unexpected. It has also been possible to prepare solutions of such metal complexes in high concentrations. The type of such complexes has been definitively determined using analytical criteria, namely (1) the molar ratio method set forth by Yoe and Jones (JH Yoe and AL Jones: Ind. Eng. Chem. Anal., Edition 16, 111, 1944). ; (2) the method of continuous variation, attributed to Job and modified by Vosburg and Cooper [W.C. Vosburg and G.R. Cooper: J. Am.

Chem.Cos., 63, 437, 1941); (3) the dependence of complex formation on pH, and (4) determination of the apparent stability constant of the complex.

Spectrophotometric examinations, including visible and ultraviolet spectroscopy, pH determinations, and even infrared spectroscopic measurements have been used as an additional means to confirm the detection of the formation and molecular composition of the copper (II) citrate complex: 1.

The 1: 1 copper complexes used herein as antimicrobial or stabilizing agents are highly soluble, indicating that such complexes are of an ionic nature. This is further supported by the observation that the colored solution band for the complex is a @% s \ ¿¿¿¿n¿Ti? E fl ü fl â CÉÜÉKÉÃÉTÉ 8300937-3 zz rerat mot anoden (positive electrode) in electrophoretic investigations. Visible and ultraviolet spectra show the formation of a compound 1: 1. The fetal reaction for the complex formation of the structural formula B appears to be as follows: - o \ 40 + 00C \ c (cH coo ') * c / Ewa cooï H "m-'í U + HO / z. z <- \ O / ° zz (n cuz * + V '-, (2) H + råygasï ______ H20 i Km = ECu-ZÜ íšitratsíl. -2 Keff = WELL.

[Cu * j ÉitratSfI 5 Instead of only the groups C00- complexing, the alcohol OH is thus ionized and included in the coordination. This forms a stable S-free and probably 6-free ring. Thus, the reaction proceeds to the right (stabilized) by OH- (base), since the product H + is then removed as the reaction proceeds. This results in a very high effective stability constant of Keff. The value of Keff for such a reaction is pH dependent, memä also dependent on the absolute stability constant, Kabs through the following relations: eff = ífcrritirfaz_l__ L-Cuzå] [Citratáf] [Cucitraf] I H Ü Bluzïl Elitrate 3l | K abs _ - * l Kabs '_ Keff KH .I' J-PQQB, ~ 10 15 20 25 35 40 23 83ÛÛ937 "3 It has been found that Kabs for the complex 1: 1 has a constant value of about 1013 (a strong complex) over a pH range of about 9-12.

The apparent value of Kabs falls sharply at pH 7 to 9, and at pH values below about 7 there is a further decrease, which indicates that the complex exists at certain levels even at pH 3-7. Another essential feature of the complexes according to the invention is believed to work. to enable their function as highly effective bactericides. This can be exemplified when bacteria are grown in a medium having a pH of, for example, about 9 to about 11 and where a dialkalimonocopper (II) citrate complex is introduced. As stated above, the alkaline pH environment makes the monocopper (II) citrate complex very stable. It is assumed that the free copper ion, due to its immediate binding to the cell surface, would not be expected to pass through the cell membrane at all, or at least not as easily as the complex form. On the other hand, the complex passes easily through the cell membrane, which is probably due to (1) its organic nature, which could serve as a metabolic substrate, on which bacterial growth or proliferation depends, or (Z) the low-charge dianionic density of the complex, which facilitates permeability through the bacterial cell wall. After transport through the cell membrane, it can be expected that the complex would be subjected to a pH environment of the order of about 7. The special complex is fi h ° the transition is very volatile and labile, so that the copper ion is released in large quantities and quickly for denaturation of cell protein or other metabolic influence of the intracellular biochemical reactions, so that the cell is killed. In contrast, when other known complexes can be transferred under such conditions, these known complexes are relatively stable and kinetically inert, and will not be effective, since the copper is too strongly bound to be highly toxic even at the intracellular pH. the value of about 7.

The metal complexes of the present invention have extremely unique antimicrobial properties compared to prior art compounds. For example, the formation of heavy metal salts of carbonic acids is extremely common. However, with the exception of low molecular weight salts, these are usually insoluble in water. This is illustrated by the copper (II) citrate found in the literature, 5H, 0. This compound is prepared by heating u DikopparLII) cit- (Cu, citrate) 7 'a strongly basic solution of sodium citrate with Cu¿ +. the rate (a ratio of Z copper atoms to 1 citrate ion) precipitates from the solution. This copper (II) citrate has the following properties; (1) insolubility in water. With a total net charge of the compound of 0,2Cu2 + and citrate4_, the reaction is as follows + zçuz * + citrate3 "Cuzcitrate f H and is completed by the reaction of the product H + with OH- in basic medium; (2) light green color in solid form, and (3) elemental analysis confirming the ratio of ZCu to 1 citrate.The insolubility of the dicopparilic citrate has also limited the efficacy of this compound as a hackericide, and although previously suggested in pharmacological applications, its use has been limited.

Fluid compositions for metalworking can, as stated above, be composed of many different types of specific constituents. See, for example, the aforementioned patents and "American Society of Tool Engineers - Tool Engineer's Handbook", first edition 1953, page 357 et seq.

The invention is further illustrated by the following examples, which show fluids for metalworking and the principles of the invention. However, they have no limiting meaning.

Example 1. A cutting liquid composition is prepared by mixing the following ingredients, by volume. 1% sodium xylene sulfonate 9% naphthalene sulfonate 90% mineral oil, viscosity about 300.

This mixture was then used to prepare a 3% (v / v) emulsion by mixing with water, and the pH was adjusted to about 8.5-8.9 by the addition of hydrochloric acid. Disodium mono-copper (II) citrate, prepared as described above, is added to the emulsion in an amount of 100 mg of copper2 + per liter in the aqueous phase. When such a metalworking fluid is used in metal cutting processes, it has been found that all of the advantages set forth herein can be achieved.

Example 2. A fluid composition For grinding is prepared using the same process steps as in Example 1 and with similar results, except that 50 percent naphthenic sulfonate, 15 percent mineral oil (viscosity about 100) and preventive customs oil are used instead as constituents of the emulsion.

To show the coordination of metal ions with the emulsified droplets; asooszv-z pairs to achieve stabilizing effect according to the invention, the following experiments have been carried out.

Experiment 1. The ratio of the copper content of the oil and water phases to the oil content of the emulsion and to the original content of metal complexes.

Emulsions were prepared with a content of 2.5, 5.0 and 10.0 percent oil in water. 10 percent of each emulsion was pipetted into 16 x 100 ml test tubes. Test tubes of 1 ml of each were taken. To each of these test tubes was added disodium monocopper (II) citrate C (hereinafter referred to as the metal complex) until final levels of 50, 100 and 150 ppm, calculated as CuZ +. Samples of 1 ml were taken immediately after mixing the metal complex and the emulsions, and samples were taken again after 1 hour with occasional mixing during this time.

The oil samples were extracted by adding an equal volume of dichloroethane and a drop of saturated KCl solution, mixing and centrifuging for 5 minutes at top speed in a table top centrifuge. Five tenths of a ml of the organic phase (bottom phase 1) and 0.1 ml of the aqueous phase were taken out into different test tubes, and 4.9 ml of water were added to the aqueous phase sample. Two tenths of 1 ml of copper reagent was added to each tube with mixing, after which 0.2 ml of reagent No. 2 was added, all tubes were shaken well, and 5.0 ml of water was added to the tubes containing the organic extract, the tubes containing the organic phase were shaken again, and the organic material was allowed to sink to the bottom.

The optical densities of the tubes were read at 700 nm against suitable control samples, consisting of organic extracts or aqueous extracts of emulsions without any added metal complex. The results of the experiments are given in the following table. The percentage of copper content in each phase was determined by correcting the value A700 for volume differences between the organic extracts and the water extracts and adding the A700 values for each phase. The percentage value of "total A700" for each phase was assumed to be directly dependent on the total copper content in each phase.

N) ~ \ 8300937-3 Table 1. Total percentage of copper content in each phase as a function of time (T), oil content and copper content. 50 ppm metal complex as Cu2 + total percentage Cuz + Organic phase aqueous phase% oil TO T60 TO T60 2.5 0.9 0.0 99.1 100.0 5.0 13.0 22.7 87.0 77.3 10.0 19.2 25.9 80.8 74.1 100 ppm metal complex as Cu2 + percentage total content Cu2 + Organic phase aqueous phase% oil, T0 T60 TO T60 2.5 0.8 3.6 99.2 96.4 5.0 10, 6 12.2 89.4 87.8 10.0 12.7 13.6 87.3 86.4 150 ppm metal complex as Cu2 + percentage total Cuz + Organic phase aqueous phase% oil To T60 TO T60 2.5 1.0 1, 0 99.0 99.0 5.0 8.4 11.7 91.6 88.3 10.0 11.9 12.6 88.1 87.4 The results clearly show that at each content of metal complexes the total the copper content of the organic phase slowly with time. This effect is most marked in the samples containing 5.0 percent oil in the emulsion. The adsorption of Cu2 + into the oil phase seems, with enzymological terminology, to be of the first order with regard to the content of both oil and metal complexes, where the copper content in the oil flattens out at the saturation point of the oil. A Michaelis-Menten-type curve is to invert the transfer rate of Cu2 + into the oil phase, as discussed below.

At a given time and content of metal complexes, the total copper content in the organic phase is directly dependent on the oil content in the emulsion. This connection was clearest in the samples with 50 ppm metal complexes. The amount of copper in the organic phase depends on the content of oil in the sample, which shows that copper binds or coordinates directly to the surface of the lnjewnlikhnnu.

In-depth work has shown that the metal complex molecule is not extravagant in organic solvents. Since in this experiment copper was extracted into the organic solvent together with the oil, the metal may not still have been complexed with the citrate group. It is then possible that CU2 + is bound to the oil particles and extracted with them, and that citrate due to the high pH value has been complexed with divalent cations in the aqueous phase. Subsequent analyzes of the aqueous phases from such emulsions after extraction have shown that the citrate remains in the aqueous phase after the transition of Cuz +.

With an increasing content of metal complexes, an equivalent increase in the content of Cu 2+ in the organic phase could not be detected. This phenomenon enables a number of different mechanisms for the transition of Cu2 + to oil.

The size of the oil particles in the emulsion is certainly not uniform.

Therefore, the total surface area of the oil particles in the 10.0% oil emulsion is not four times as high as that in the 2.5% oil emulsion. The variations in particle size affect the amount of copper that can be transferred to the organic phase. An equilibrium can exist between copper in the oil and water phases. The "equilibrium constants" for transfer in both directions can be determined by the levels of metal complexes in the aqueous phase, ie the reactant content, and the levels of organic copper and citrate salts. The transfer of metal complexes can be described by the following formula: 4%% 5 = _ Metal1complex; f§Cu2 + + Nacítratšš = 9CuäY.olja + X3 + .pÉtrat3 'it = _ Cu2 + + oil X3 + + citratš When X3 + is a simple or complex cation with 3 positive charges, is determined by the dissociation constant for metal complexes at pH 9, and É3 by the adsorption rate of copper into the oil phase and the affinity between citrate and divalent and trivalent cations. It is clear that 4% is greater than-then and aá is greater than.Äâ, because with greatly increased time and shear, essentially all copper has been detected in the organic phase. The hypotheses of an equilibrium relationship and the time dependence of the adsorption agree well with Michaelís-Menten-type curves. Experiment 2. The dependence of the copper content in the oil and water phases on shear stresses on oil particles A 50% oil concentrate was subjected to shear by being passed three times through a homogenizer at 55 MPa. The oil particles were found to have a diameter below 0.1 μm. The same concentrate in the non-homogenized state was found to have a wide size distribution of the oil particles of 0.8-3 microns, with a mean diameter of about 1.5 microns.

You two concentrates were mixed with the boiling water to obtain 2% 2% oil emulsions in water, since an oil emulsion of this content in the previous experiment was found to give the highest adsorption rate of Cu2 + in the oil phase. A two ml sample of each emulsion was taken and centrifuged to remove any large particles. Metal complexes were added to each emulsion to a level of 100 ppm as Cu 2+, and two ml samples were taken and centrifuged immediately. Samples of one ml of the superphases were extracted and examined in the same manner as in Experiment 1. The emulsions were shaken gently for one hour, and samples of two ml were taken and treated in the manner described above after 10, 30 and 60 minutes.

The test results are given in the following table. The copper content in each phase was determined in the same manner as in Experiment 1.

Table Z. Percentage of total copper content in each phase as a function of time and homogenization _ Total content of Cu2 + in% (100 ppm metal complex added] Time Organic phase aqueous phase Ûnin) homogenized non-homogenized homogenized non-homogenized 0 13.5 11.3 86.5 88 .7 10 18.3 20.3 81.7 79.7 30 25.3 14.9 74.7 85.1 60 27.0 18.1 73.0 81.9 A comparison of these results with those from experiments 1 shows that considerably more copper has been adsorbed into the organic phase of the homogenized material, and slightly more into the organic phase of the non-homogenized material. If the content of metal complexes added to these samples, especially to the homogenized material, had increased, a higher copper content in the organic phase would have been expected. In a circulating refrigerant for metalworking and with high levels of divalent cations, such as Mg2 + and Ca2 + present and competing for the citrate group, the reaction rate of the copper adsorption LÅ1 and Äg) should be higher.

The results of this experiment clearly show the validity of a Míchaelis-Menten analysis of the copper adsorption rate. The maximum rate of uptake of copper in the organic phase of the homogenized sample occurs during the first 10 minutes after the addition of metal complexes to the refrigerant. From 10 to 60 minutes observe * a lower rate of copper adsorption. More copper has been taken up by the homogenized oil particles than the non-homogenized ones. And f; aPOOR QUALmr _ af. ¿_ F, 29 8300937-3 much higher original hnstlghct for copper eruptioncn nhstr ~ vcrns 3 the humogcníscrudc oljcprovct, this due to dun cnørmu ytnrcnn at oljcpart1k1nrnn. These effects mean that the copper adsorption to oil also constitutes a surface phenomenon, ie that the copper binds to the surface of the oil purifier rather than being incorporated into them.

It can be seen that other modifications of the invention are also possible without departing from its scope.

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Claims (13)

8300937-3 3,., Patcntkrav 1. I. A method of stabilizing a fluid composition of a dispersion of oil and water for metalworking, characterized in that a dispersion of oil and water is prepared with an emulsifier selected from anionic and nonionic agents and mixtures of these, and which gives the oil phase electronegativity, and that in the aqueous phase of the composition an effective stabilizing amount of a polyvalent metal ion is provided for bonding to the electronegative oil phase, so that the dispersion is imparted to stability. 2. A method according to claim 1, characterized in that the metal ion is incorporated into the aqueous phase in the form of a metal complex of the metal ion and a polyfunctional organic ligand, the complex having dissociation properties induced by protons in aqueous solution which are illustrated by a sigmoid-shaped curve in a right-angled coordinate system of the negative logarithm of the metal ion content versus the negative logarithm of the hydrogen ion content, so that these dissociation properties provide a controlled release of the metal ion to impart stability to the dispersion. 3. A method according to claim 2, characterized in that the dispersion is first prepared and the metal complex is incorporated in the aqueous phase of the dispersion. 4. A method according to claim Z, characterized in that the metal complex is incorporated into the aqueous phase of the composition before the dispersion is prepared. 5. A method according to claim 2, characterized in that the dispersion has an alkaline pH below about 12. 6. A method according to claim Z, characterized in that the dispersion has an alkaline pH in the range from about 7 to about 9. 7. A method according to claim 6, characterized in that the ligand of the complex upon dissociation acts as a buffer to maintain the pH within the stated range. 8. A method according to claim 2, characterized in that the complex consists of a dialkali monometallic chelate of a nlfa-hydroxypolycarboxylic acid. 9. A method according to claim 8, characterized in that the carbon is constituted by dialkalimonocopper (II) citrate. 8300937-3 10. H l k ä n n c t e c k n n t thereof, ntt kclutet is provided in admixture with water. 11. ll. k- from the fact that in the aqueous phase a dialkali is provided. Method according to kxuv 9. at an alkaline pH in the range of from about 7 to about 9. _ 12. A method according to claim 11, characterized in that about 10 to about 100 mg of copper metal ion per liter is incorporated into the aqueous phase. 13. A method according to claim 12, that the content of the aqueous phase of the composition is retained during the composition of the composition, the use of the composition in metalworking processes. PG