CA2060718A1 - Soil-removal microemulsion compositions and methods for making them and using them - Google Patents
Soil-removal microemulsion compositions and methods for making them and using themInfo
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Abstract
ABSTRACT OF THE DISCLOSURE
Disclosed are emulsions made by simple agitation of about 99.9-20% water and about 0.1-80% progenitor solutions, the latter containing at least one surfactant, at least one solvent, and at least one emulsifier, the solvent being of selected polarity and all the ingredients being of selected refractive index. Also disclosed are methods of obtaining emulsions of a desired cleaning ability (which may be targeted to a specific cleaning task) and cost using a correlation (polarity/refractive index function) between cleaning ability, polarity of the solvent and refractive index of the solvent and other additives.
Disclosed are emulsions made by simple agitation of about 99.9-20% water and about 0.1-80% progenitor solutions, the latter containing at least one surfactant, at least one solvent, and at least one emulsifier, the solvent being of selected polarity and all the ingredients being of selected refractive index. Also disclosed are methods of obtaining emulsions of a desired cleaning ability (which may be targeted to a specific cleaning task) and cost using a correlation (polarity/refractive index function) between cleaning ability, polarity of the solvent and refractive index of the solvent and other additives.
Description
SOIL-REMOVAL ~ICRO~MU1SION COMæOSITIONS
AND M~T~ODS FOR MARING TERM AND ~SING TEEM
FI~LD OF T~E INV2NTION
This invention relates to novel soil-removal emulsion or microemul~ion compositions of optimized cleaning power which ar~ made by a method that is simpler than methods fo~ making emulsion microemulsion or biliquid fo~m polyaphron compositions currently known in the art. In another aspect, the invention relates to a method for using such compositions for cleaning (especially industrial cleaning) purposes.
BACRGROUND OF_T~E INVENTION
Biliquid foams consist of a water-insoluble liquid "bubble" (or "globule" or "internal phase") trapped within a film of an aqueous surfactant-containing solution ("external"
or "continuous phase"). Biliquid foams have very small "bub-bles" (e.g., of a diameter in the order of a micron or even asubmicron). The foams have been recognized for use in cleaning generally because such bubbles are said to be stable and to have a relatively large surface/volume ratio.
U.S. Patent 4,486,333 issued December 4, 1984 to Sebba discloses and claims a method for preparing such a biliquid foam composition of the polyaphron type (Col. 1, lines 35-47~
for use inter alia in cleaning (Col. 6, lines 31-41) or in mak-ing dispersions from concentrates of emulsified liquids (Col. 6 lines 23-31) to be used, e.g., in solvent extraction. The '333 polyaprhons have globules of 0.1-10 microns and a PVR (phase volume ratio, i.e., ratio of volume of discontinuous phase to volume of lamellar continuous phase) of up to about 50.
First, according to '333, an ordinary gas foam is prepared using water and~or another hydrogen-bonded liquid such as an alco~_i or glycol and a water-soluble surfactant;
intermittentiy, a limlted amount of a nonpolar water-immiscibLe liquid is added and the mixture is agitated to cause the nonpolar liquid to spread on the foam surface and to form no~coalescing globules of nonpolar liquid dispersed in a continuous phase of hydrogen-bonded liquid. Each globule is encapsulated in a double-surfaced film of surfactant and water.
The nonpolar liquid and the surfactant are said to be selected to have a spreading coefficient greater than or equal to zero to permit the nonpolar liquid to initially spread as a thin sheet on the surfactant-containing aqueous lamellae and then to break up in-to fragments and globules (of 0.1-10 micron size) (~ol. 2, lines 55-68).
The total amount of nonpolar liquid thus encapsulated is between 40 and 98% by volume of the entire composition and the PVR is at least 1.5 and up to 49 ('333, claim 1~.
The surfactant in '333 can be any anionic, cationic or nonionic surfactant that would produce a good foam (as long as it fulfills the above spreading coefficient relationship) and it is used in an amount preferably at least about 0.3% by weight of the water (Col. 4, lines 26-32).
The '333 nonpolar liquid also preferably contains a small (up to 5% by weight) quantity of a soluble nonionic surfactant that pe~mits the nonpolar liquid to spread on the aqueous film (Col. 4, lines 50-62).
The '333 invention suffers from the disadvantage that it is difficult to prepare. Also, there is no attempt to tailor a particular polyaphron to a given cleaning task other than as a fuel additive and as a foaming gel although cosmetic applications are alluded to. See, e.g., '333 Example 4.
U.S. Patent No. 4,606,913 issued to Aronson on August 19, 1986 also concerns high-internal phase emulsions (i.e., emulsions in ~hich the internal phase constitutes 74-75% of the total volume) (Col. 1, lines 9-16). Use in industrial cleaning applications is disclosed ~Col. 1, line 30).
The '913 patent recogni~es that choice of the emul-sifier affects the stability of these emulsions and further proposes the incorporation of "an electrolyte' in the emulsion, particularly in the aqueous phase to improve stability.
Although any type of electrolyte is said to be suita~le and trivalent inorganic salts are said to be preferred, only magnesium sulfate and potassium sulfate are claimed (Col. 9, 10line 9; Col. 10, line 60).
~he emulsifiers generally named in the '913 patent are conventional, generally nonionic, emulsifiers usually having an HLB (hydrophilic to lyophilic balance) between 1 and 7 and are said to include comhinations of sorbitan trioleates; mono- and 15multi-phosphoric esters of oleic acid; polyoxyethylene sorbitol hexastearate~, ethylene glycol fatty acid esters, glycerol mono-180 stearates, and sorbitan monooleates; polyoxyethylene 2-oleyl ethers, glycerol/fatty alcohol ethers, esters of polyalcohols, polyethoxylated 2-oleyl alcohols, synthetic 20primary alcohol ethylene oxide condensates; and mono- and di-glycerides of fat-forming fatty acids (Col. 5, lines 34-67).
Emulsifiers are said to be present at 5-30% by weight of the external phase.
The '913 emulsions are said to be prepared by incor-25porating the emulsifier in the oil phase and the electrolyte in the aqueous phase and adding the aqueous phase to the oil phase in small aliquots (not more than 15% of the total oil phase at a time).
U.S. Patent No. 3,976,582 issued to Douglas on August 3024, 1976 discloses a method for making and stabilizing micellar systems including microemulsions having maximum zeta potential for optimizing the recovery of petroleum from shale rock and other subterraneous formations and minimizing the undesirable adsorption of surfactant or rock formations.
35The micell~r systems are said to be made in accordance with known techniques. They comprise 5-20% surfactants (which can be anionic or cationic), 5-60% hydrocar~on solvent, 10-60 electrolyte-containing water and 1-3.5~ "co-surfactant'~.
Cosurfactants are co-solubilizers i.e., semipolar organic compounds, prefe-dbly alcohols.
The ~5~2 invention involves measuri~g th~ zeta poten-tial of a range of micellar systems (varying in aqueous phase content) (the zeta potential is normalized to account for differences in electric conductivity) and selecting as optimum those compositions that have a maximum or near maximum systemic zeta potential.
U.S. Patent No. 4,542,745 discloses an oil-in-water emulsion for use in medical ultrasonic probes containing as the aqueous phase water and alcohol, glycerol or lower alkylene glycol. Th~ oil phase is silicone fluid and is in droplets of 0.15 microns to 1.5 microns in diameter.
U.S. Patent No. 3,813,345 issued to Urton on May 28, 1974 is directed to a method for reducing the micelle size of an oil-in-water emulsion (wherein the oil phase contains an organic solvent, a surfactant and an unsaturated organic compound soluble in the solvent and the aqueous phase in water) by adding to such an emulsion a water-soluble resin with a high number of positive-ion accepting sites and equilibrating this resin with a positive ion donor to cause it to have the same sign of (surface) charge (positive or negative) as the micel-les, there~y causing further subdivision of the micelles. The disclosed use for such micellar systems is in insecticide preparations.
U.S. Patent No. 4,472,291 issued to Rosano on September 18, 1984 discloses viscous oil-in-water microemulsions contain-ing a surfactant, a co-surfactant (emulsifier~ and a secondary surfactant which has the property of increasing the viscosity of the microemulsion. The stated uses of such microemulsions include hard surface cleaners, shampoos, lotions, salves or creams, car waxes, window cleaners, anti~rust formulations and floor polishes (col. 5, lines 35-40).
U.S. Patent No. 4,592,859 issued to Smith-Johannsen on June 3, 1986 is directed to stable suspensions of oil and water in which the droplets of the discontinuous phase are surrounded by colloidal particles having a ~eta potential within the range of +18 to -18 ~V. The suspensions are prepared by adding to water a combination of surfactants (anionic and cationic) which form colloidal particles with the requisite zeta potential.
The oil phase is then added. Disclosed uses include cleaning and polishing compositions, paints, varnishes, impregnants ~or porous surfaces, cosmetics, cement additives, industrial oils and waxes. Pharmaceutical and agricultural uses are also mentioned.
All of the foregoing prior art ~ystems entail compli-cated and time-consuming formulation methods, and/or are not suitable for industrial cleaning applications. They require special equipment and/or calculations and/or sophisticated additives (such as water soluble resins or electrolytes) as well as specific methods of addition of the dispersed phase to achieve the necessary stability and/or globule configuration (si7e and type of the dispersed phase). As a result, the prior art systems are expensive and, most important, their use is confined to specialty applications and they lack the ver-satility necessary for an industrial-type cleaning composikion.
This invention is directed in one aspect to emulsions or microemulsions prepared by simple agitation of water and quantities of single-phase compositions thereafter "progenitor solutions") which contain a combination of at least one surfactant, at least one solvent and at least one emulsifier, the solvent ~eing of selected polarity and all ingredients being of selected refractive index. The resulting emul-sion~microemulsions ~hereafter simply "emulsions") are highly stable and have optimal cleaning ability for a variety of in-dustrial cleaning applications. The foregoing emulsions contain between about 0.1 and about 80% of progenitor solution.
In another aspect, the present invention provides a convenient guide (more specifically a function of solvent polarity and "collective refractive index"--defined below) for varying any ingre~ient used in the foregoing progenitor solutions and/or tile amount of such ingredient in a manner which increases the cleanlng ability of emulsions formed using the progenitor solutions. The emulsions of the present invention can thus be optimized for cleaninq ability (and ca~
be targeted to a particular cleaning ta~k) and, if desired, cost, without using expensive ingredients (such as exotic surfactants or emulsifiers) without using electrolytes and without using special equipment (e.g. equipment to measure zeta potentials).
In yet a third aspect, the present invention is directed to methods of using the foregoing progenitor solutions and emulsions for particular industrial cleaning and soil-removal applications including without limitation removal of tar and/or oil or greases from sand, industrial equipment and other inanimate objects, such as removing thick oils and other soils from hard surfaces (metal, wood, glass concrete, etc.).
DBTAIL~D DE:SCRIPTION OF_TE~E INVENTION
The present invention involves first the formation of stable "single-phase" progenitor solutions which contain 60 to 98% of an organic solvent (preferably 70 to 90%), l to 20% of a surfactant or combination of surfactants soluble in the solvent (preferably S to 20~); and 1 to 20~ of an emulsifier (preferably 2 to 8%)o ~he progenitor solutions are then used to prepare stable emulsions or microemulsions (water-in-oil or preferably oil-in-water) having powerful soil-removal capacity. Both the progenitor solutions and the emulsions made from them can be formulated to be particularly effective in one or more par-ticular cleanlng applications. In fact, the emulsions of the present invention even when produced from a small percentage of progenitor solution (and containing therefore a small per-centage of cleaning agents) are particularly effective soil removal agents. Depending on the choice of solvents, surfac~
tants and emulsifiers, and on the extent of dilution either a true emulsion or a microemulsion may form from the progenitor solutions. Typically true emulsions, i.e. opaque milky liquids result on dilution. ~owever, true microemulsions, i.e.
translucent or almost transparent liquids are also occasionally observed.
It is well known in the art that in order to have effective cleaning agents, the soil to be removed must be penetrated, solvated and removed (sequestrated) from the substrate and dispersed in a cleaning medium. Penetration and dispersion are achieved by surfactants. Ionic surfactants affect the electrostatic propertie~ of the surface to which they adsorb (or film in which they are resident). Nonionic surfactants by orienting their hydrophilic moiety into the so-called Stern layer surrounding a wetted soil particle (assumirlg the medium is aqueous) promote dispersion and inhibit ag-glomeration.
Similar principles apply to stabilization of cleaning emulsion compositions. Stability of an emulsion is promoted by surfactants which act as emulsifiers. They should have good solubility in both the agueous and the oil phase. Often, combinations of surfactants are more effective as emulsifiers than single compounds, as is well known in the art. See, generally Surfactants and Interfacial Phenomena, M.J. Rosen, Wil~y 1978.
The electrical properties of a film or surface are very important in stability of cleaning emulsions and in effective-ness of cleaning ability. The electrostatic surface charges can be measured, but expensive equipment is necessary. A
simpler method for optimi~ing stability and cleaning perfor-mance of emulsions is provided below by the present invention.
Refractive index and polarity of a liquid provide a measure of the electrostatic properties of that liquid. The present inventor was able to correlate the cleaning ability of various emulsions to the polarity and refractive index of their ingredients and corresponding concentration of each ingredient in the progenitor solution. Stabili~ation of the resulting emulsion is governed by the equilibrium of the surfactants within the progenitor sol~tion i.e., surfactants/emulsifiexs are added until they aTe _Dle to completely emulsify or suspend particles of a liquid in a second immiscible liquid. Thi~ is done by routine e~perimentation well within the skill of the axt.
According to the present invention, an arbitrary polarity scale is first established for various s~l~ents ~ased on the physiochemical characteristics of each solvent. This can be done by using , for example, Snyder's Yolarity Index, incorporated by reference. See Snyder, I.R., J. Chromatoqraphy Sci., 16:223, 1978. However, any other polarity scale could be used to generate a polaritytindex function (defined infra).
Table 1 below contains nonlimiting examples of solvents suitable for use in this invention and their assigned polarities ton a scale from 1 to 10).
A collective polarity P can then be calculated for the solvent components of a particular composition as the weighted sum of the polarity of the solvents contained in a given composition according to the formula:
P = (SiPi) where i is an integer from 1 to n, n is the total number of solvents in the composition; Si is the weight fraction of each solvent based on the total composition of the progenitor solution; and Pi is the polarity of that solvent.
Refractive index values for the emulsifiers, surfac-tants and solvents are used to calculate a collective refrac-tive index ND in the same manner ND = ~ XiNi wherein Xi is the weight fraction of a particular component (surface active agent or solvent) and N is the refractive index of the same component. Refractive indices for solvents are ~ .
readily available in the literature (see, e.g., The Merck Index, 11th Fd. and the Handbook of Chemistry and Physics, Chemical Rubber Publ. Co., Cleveland, Ohio) as are those for surfactants.
The ability of each composition to clean a particular type of soil is then measured and the results are correlated with the following empirical polarity/refractive index function (PIF): ~10.N
(10-P) See Figures 1-3 by way of nonlimiting example.
In Figures 1~3 the ability of compositions within the invention to remove tarsand soil when formulated into emulsion containing 10% of a progenitor solution is plo-tted against the polarity/Lndex function f~r each composition. (See data points.) The three figures correspond to the data of Table 3 for 3 types of emulsifier Emulsogen IT (Fig. 2~, Emulsogen SHT (Fig. 1) and Emulsogen EL (Fig. 3). The straight lines drawn through Fi~ures 1-3 represent the best straight-line fit but the cleaning ability is assessed much more accurately by reference to the critical PIF value. Critical PIF value is a value of the polarity index function which when matched or exceeded by variation of the content and chemical identity of the constituents of a progenitor solution results in formation of emulsions essentially all of which have cleaning ability of 60% or more (when cleaning ability is measured by the procedure of the Examples). Critical PIF is thus a function of the particular cleaning task, and is independent of the ingredients of the progenitor solution.
It transpires from Figures 1-3 that tarsand soil (to be removed to a substantial extent, i.e. 60-100%) needs a cleaning composition with a high polarity-index function (in the c~se of Figs. 1-3 given the polarity scale used and the experimental procedure and parameters for assessing cleaning ability the critical PIF value is no less than about 6; in fact a substan-tial increase in cleaning ability is almost universally observed when the PIF is higher than the critical value). This means that the best compositions for cleaning tarsands should have both relatively high polarity and relatively high index of refraction. Indeed, the preferred compositions exempliied below have a collective rPfractive index ND f about 1.4 or more and a collective so'~ent polarity of about 3.0 or more.
Thus, once the critical value of the polarity-index function has been identified, it is possible to conveniently select emulsions that will have a desired cleaning ability for a given task by selecting a com~ination of ingredients and contents which will yield an emulsion with a PIF value equalling or exceeding the critical value. The selection can be refined further ~if desired) using no more than routine experimentation consistent with the present disclosure.
Similar empirical plots can be generated for other 1~ soils than tarsand using only routine experimentation. Thus, the combination of the present invention can be optimized for each cleaning use by identifying the critical polarity index function value for a particular application. It should be emphasized, however, that the cleaning compositions that are most effective for tarsands are also generally effective for other industrial cleaning tasks as tarsand removal is a particularly difficult cleaning task. It is also possible to develop straight-line models for the relationship between soil-cleaning ability and Polarity/Index Function value for each type of soil by using various statistical techniques such as linear regression analysis applied to data such as those of Table 3. In practice, however, this does not appear to be necessary as it is nor~ally easy to identify the critical value for the polarity-index function (which may or may not be numerically the same for different cleaning applications).
It is envisioned that each progenitor solution within the invention will contain at least one organic solvent suit-able for removing the target soil(s), i.e., having sufficient affinity to the soil to solvate it. Nonlimiting examples of species and categories of suitable commercially available sol-vents and their assigned polarities are set forth in Table 1.
.
TA~I,E 1 SOLVENT GEN13RIC NA~ /CATEGORY POI~RITY
Sol~esso 150 aromatic hydrocarbons solvent 3 Butyl Carbitol diethylene glycol monobutyl ether 7 Exxate 600 alkyl oxo-alcohol esters 8 of acetic acid Tabs D menthadiene solvent 5 ~enzyl Alcohol phenyl carbinol 6 Isopropyl Alcohol 9.5 Methyl Carbitol diethylene glycol monomethyl ether 9 Carbitol di0thylene glycol monoethyl ether 8 Isopar K isoparaffinic hydrocarbon solvent 1.5 Xero K paraffinic hydrocarbon solvent 1.5 Nonaromatic solvents, especially those having a flash point higher than 140F, are preferred for enviro~mental reasons.
~roadly, suitable solvents include without limitation aliphatic, aromatic, terpenic, paraffinic, isoparaffinic and olefinic hydrocarbons, alcohols and glycol ethers of the formula CnO(E0)x(PO)yH wherein Cn is an alkyl radical having n carbon atoms (n i5 from 1 to 6), E0 is a -CH2-CH20- (x is an integer from 0 to 4), P0 is -C~(CH3)-CH2-0- or -CH2-C~(CH3)0-(y is an integer from 0 to 4), benzyl alcohol, alkyloxoalcohol esters of lower aliphatic acids, substituted glycols of the formula CnO(E0)xCn (with n and x as defined a~ove), glycols of the formula H(E0)xH and H(PO)yH (wherein E0, P0, x and y have been defined above) and acetate esters of glycol ethers.
The progenitor solution will contain at least one surfactant soluble in the solvent. The choice of surfactant depends on the compatibility with the solvent and/or solvent composition of the progenitor solution and the soil to be removed. Compatibility of the surfactant with solvent and soil is determined from supplier information or is within the ordinary skill in the art including at times routine experimen-tation. Preferably, the cleaning emulsion will contain at least two surfactants which may be nonionic and/or cationic and or amphoteric. Both (or all) surfactants are preferably incor-porated in the progenitor solution. Anionic and zwitterionic surfactants can also be used.
Suitable surfactants generally include without limita-tion those disclosed, e.g., in Norris U.S. Patent No. 3,663,961 (5/23/72) incorporated by refP_ence and in Surfactants ~nd 5 Interfacial Phenomena by MiltcJ. Rosen, John Wiley ~ Sons, 1978, pp. 1-17, also incorporated by reference. Other suitable surfactants include:
Suitable anionic surfactants generally include without limitation water-soluble salts of alkylbenzene sulfonates, alkyl sulfates, alkyl polyethoxy ether sulfates, paraffin sulfonates, alpha-olefin sulfonates, alpha-sulfocarboxylates and their esters, alkyl glyceryl ether sulfonates, fatty acid monoglyceride sulfates and sulfonates, alkyl phenol polyethoxy ether sulfates, 2-acryloxy-alkane-l-sulfonates, and beta-alkyloxy alkane sulfonates. For more specific examples, see U.S. Patent No. 4,414,128, col. 3, lines 60-68 & col. 4, incorporated by reference.
Suitable nonionic surfactants include alkoxylated compounds produced by the condensation of alkylene oxide groups with an organic hydrophobic compound (aliphatic, aromatic or arylaliphatic). The length of the polyoxy alkylene group should be controlled (which can be accomplished in a manner known per se) so that the resulting surfactant is liquid and, where applicable, soluble in the solvent or solvent mixture 2S used for the progenitor solution. More specific examples of these nonionic surfactants are disclosed, e.g., in U.S. Patent No. 4,414,128, col. 5, lines 14-68 and col. 6, lines 1-14, incorporated by reference.
Suitable cationic surfactants include without limita-tion those disclosed in U.S. Patent No. 3,813,345, col. 8, lines 42-53, incorporated by reference.
Amphoteric and zwitterionic surfactants include without limitation those disclosed in U.S. Patent No. 4,414,128, col.
6, lines 31-66, incorporated by reference.
Preferred are surfactants such as nonionic ethoxylates (e.g. Igepals, Surfonics) anionic surfactants (such as Sulframin, Sulframin AOS) and cationic surfactants (such as Bardacs, Hyamine, Genamin 8). All materials disclosed or referenced herein are readily commercially available.
In general, the choice of emulsifier will depend on (a) the desired stability of the emulsion; (b) whether an oil-in-water or a water-in-oil emulsion is desired; and (c) the type of soil to be removed. A hydrophilic emulsifier will best stabili~e O/W emulsions while a liophilic emulsifier stabilize6 best W/O emulsions. A highly oxidized SOLl would require a more hydrophobic emulsifier than a relatively unoxidized 80il~
In principle any emulsifier that contributes to the desired PIF
Yalue can be used, including without limitation those disclosed in Aronson U.S. Patent No. 4,606,913.
Preferred examples of emulsifiers include the follow-ing:
Table 2 Emulsifier Composition Supplier Example _ _ Igepal Ca 420 Ethoxylated octyl phenol GAF
Brij 92 Ethoxylated (2) oleyl ether ICI
Span 80 Sorbitan monooleate ICI
Span 85 Sorbitan trioleate ICI
Atmos 300 Mono and di glycerides of fat forming fatty acids ICI
Drewmulse GMO Glycerol monooleate PVO
Kessco Ester Glycerol monooleate ARMAK
Drewpole 10-4-0 Decaglycerol tetraoleate PVO
Liposorb SQO Sorbitan Sesquioleate Lipo Chemicals Magnesium oleate Ethoxylated (3) oleyl ether Croda Volpo 3 Bodag GMR Glycerol mono ricinoleate Hodag Emulsogen E = Combination of fatty amine American salts with alkyl aryl poly- Hoechst Corp.
glycol ethers Emulsogen M = Fatty alcohol polyglycol ether '~
Emulsogen A = Fatty alcohol polyglycol ether ester Emulsogen B~ = Ami.ne salt of a7~vl sulfamide carbonylic acid Emulsogen D.G. Alkyl aryl polyglycol ether ~mulgin IT-60 Fatty acid polyglycol ~enkel Chem.
ester Corp.
Emulgin TL-55 Fatty acid polyglycol ester "
Icomeen T-15 Fatty amine ethoxylates BASF
Emulan FM Triethanolamine monooleic BASF
acid ester Marlowet OFW Mixture of n-alkyl benzene Huls Canada, sulfonate, carboxylic acid Inc.
polyglycol esters and alkyl polyclycol ether The incorporation of electrolytes is not necessary, but if desired for a particular application, electrolytes could be used as additional optional ingredients. Suitable electrolytes include monovalent divalent and polyvalent inorganic salts such as halides sulfates, carbonates and phosphates, of alkali metals, alkaline earth metals and heavy metals and mixtures of such salts. It is emphasized, however, that electrolytes are not necessary.
The progenitor solutions of the present invention are prepared by blending surfactants, emulsifiers and solvents (as well as optional ingredients such as thickening agents, dyes, perfumes, preservatives, anti-oxidants, etc.) in normal conventional equipment commonly used in the chemical specialty industry. For example, simple mixing or blending vessels such as stainless steel tanks equipped with an agitator (e.g. a Lightnin~ mixer) are sufficient. Solvents are added first into the blending vessel. The agitation is started and the remain-ing ingredients s~lrfactants, emulsifiers, etc. are added and blended until the mixture is homogeneous. This may require mixing at e.g. 50-200 rpm for several minutes to several hours depending on tank volume and agitator si~e.
The emulsions of the present invention are prepared by -- 5 simple dilution of the progenitor solution into water with normal agitation. The water can be any temperature, e.g. as required for the cleaning application, but it is preferably warm (e~g. 50~C or above). Soft water is preferred.
The emulsions can contain from 0.1 to 80% of the - 10progenitor ~olution. Generally, a 1-10% concentration is ~ufficient for most industrial cleaning jobs, and is pref~rred.
The in~ention is further illustrated below by reference to specific non-limiting Examples.
Example 1: Soil Removal Assessment 15Standard tarsand soils were prepared by smearing 2.5 cm x 2.5 cm x 0.3 cm tarsand (alternatively jesco grease or 80-10 mixtures of tarsand and jesco could have been similarly prepared) on Q-panels (i.e., metal testing panels having a Q-shaped hole) and baking the applied soil for 30 minutes at 20120~C. The panels were thereafter left to attain atmospheric equilibrium for 24 hours. This procedure is referred to in the claims as Q-panel testing.
Other test soils such as multi-use and automotive greases, gear oils, or automotive under coatings could be 25prepared for assessment in the same manner.
Finally, test soils could be alternatively prepared as follows: Roofing tars or soils containing plasticizers or any type of soil com~ination (greases, oils, waxes, etc.) are smeared on metal panels and exposed to the elements (e.g., on 30roofs or walls) for aging. The applied soil thickness is in all cases controlled via an applicator gauge.
Example 2: Preparation of Progenitor Solutions and Emulsions To a 2000 ml beaker containing a magnetic stirring bar 35placed on a magnetic stirrer 100 g of Solvesso 150 were added followed by 100 g Tabs D, 100 g methyl carbitol, 75 g of Rexonic 91-8, 75 g Hyamine 3500 and finally 50 g of Icomeen T-150 The final mixture was stirred for 30 minutes and then stored for use. This resulted in progenitor solution 20.
Additional solutions were made in the ~ame manner with sub-stitutions of various ingredients, In all cases the emulsifierwas added last to the mixture of solvent(s) and surfactant.
The ingredients and amounts for all the resulting progenitor solutions of this Example 2 are set forth in Table 3. In each case only one emulsifier was used and thus Solution No. l, for example, is really 3 different compositions: one with Emulsogen IT, one with Emulsogen S~T and one with Emul-sogen EL.
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Emulsions were made containing 10% of each progenitor solution in about 50C water by introducing a 10% vol. aliquot of progenitor solution into 90% vol. of water with agitation until homogeneous.
As apparent from Table 3, the co~_entration of the emulsifier was maintained at a constant level (5~) throughout all systems tested (except for progenitor solution 21-1). The same was done with the surfactant concentration (15%). This was done to normalize the data and does not imply that the emulsifiers and surfactants are limited to the amounts listed in Table 3. Various solvents of high and low polarity were used. The emulsions were transferred to a pump spray bottle and hand-sprayed onto the tarsand spray panels for one minute.
(Thi~ is also part of the Q-panel testing procedure.) The amount of tarsand removed was visually estimated and recorded. The results are also set forth in Table 3. The soil removal ability for various emulsions can be vastly different even when the ingredients are present in the same proportions. See in particular the systems that have identical surfactants and solvents but different emulsifiers. See also the systems that have the same surfactants and emulsifiers but different solvents. The emulsion stability was tested at 4C, 35C and at ambient temperatures for those emulsions that gave satisfactory cleaning performance. Stability testing involved preparations of emulsions containing 10~ and 20% of a mother solution in water and left to stand at 4C for three months;
ambient temperature for three months and 35~C for three months.
No coalescence was observed at this time; only occasionally minimal "creaming" occurred at 35C.
Example 3: Correlation of Polarity Index Function and Cleaninq Ability The collective polarities for each solvent mixture of each progenitor solution in Table 3 are set forth in Table 4 below:
TP.BLE: 4 COI,LE CTIVE POLARITI~:S FOR SOLVE~IT
Progenitor Solution of Solvent Polarity 1 ~.8 ~ 2.9 4 3.0 2.9 6 3.25 ~ 3.2 9 3.1 3.6 13 3.5 14 1.2 4.0 16 2.4 17 1.2 18 1.2 19 3.0 3.2 221-1 2.93 The collective refractive indices for the emulsions o~
Table 4 are set forth in Table 5 below:
9 ~ ~ 3 _ I I I I I I g~ I I g} I ~ ;; ~ ~
~' ~ ~' I I I I y I I
W I I I W I I I ~
_ I I ~ W
~ I I I I I I I I I h ~
I I I I I I I I I
o I I I I I I i I I I I I I I I I I I I I I
_ I I I ~ I 1 8 ~, Figures 1-3 represent a plot of the cleaning ability for tarsand 50il removal against the polarity/index function (PIF) of each composition of Table 3.
The critical PIF value of about 6 in Figs. 1-3 has been use ul in determining the best cleaning emulsion for the following soils:
: tarsand tarsand-jesco grease multi-use gr~ases ;- 10 gear oils Thus the data points in Figs. 1-3 permit the selection o~ the most effective progenitor solution to assess the optimum efficacity for tarsand solid removal. Alternatively, they lend themselves to utilizing and selecting a different solvent and/or surface active agents to yield the desired polarity/in-dex function (which should be at least equal to the critical value)~ ~It should be noted that the index of water was not used in computing the datapoints of Figures 1-3 ~ecause all the emulsions had the same amount of water.) Ideally, the PIF OL
the progenitor solution should be as close to the critical value as will yield the desired cleaning ability. Further improvements in cleaning ability can be effected using no more than routine experimentation.
Similar graphs can be generated in the manner disclosed above for other emulsions of different ingredients and proper-ties and for different cleaning tasks under different condi-tions. For example, emulsions containing 10% of progenitor solution #5 containing Emulsogen IT, and progenitor solution #3 containing Emulsogen SHT were effective against tarsand but not jesco oil. However, all compositions that worked on jesco (a tougher soil) also worked on tarsand. Particularly preferred progenitor solutions are solutions #15 and #20 in Table 3.
Also the following are preferred:
Isopar K 68.3 39.3 6.0 d-limonene 25.0 12.9 8.0 87.0 methyl carbitol 68.4 40.2 45.0 butyl carbitol 35.0 Eco~een T 1.7 3.0 Emulsogen A 1.7 0.9 l.O 1.0 2.0 Emulsogen T 2.5 Comperlan VOD 0.8 1.0 Emulsogen ~15 4.9 4.5 4.5 1~0 1~
~yamine DMB 451 6.5 7.5 7.5 Igepal C0630 6.5 7.5 7.5 Also particularly preferred are emulsions containing from about 0.5 to about 30% of one of the for~going preferred progenitor solutions.
AND M~T~ODS FOR MARING TERM AND ~SING TEEM
FI~LD OF T~E INV2NTION
This invention relates to novel soil-removal emulsion or microemul~ion compositions of optimized cleaning power which ar~ made by a method that is simpler than methods fo~ making emulsion microemulsion or biliquid fo~m polyaphron compositions currently known in the art. In another aspect, the invention relates to a method for using such compositions for cleaning (especially industrial cleaning) purposes.
BACRGROUND OF_T~E INVENTION
Biliquid foams consist of a water-insoluble liquid "bubble" (or "globule" or "internal phase") trapped within a film of an aqueous surfactant-containing solution ("external"
or "continuous phase"). Biliquid foams have very small "bub-bles" (e.g., of a diameter in the order of a micron or even asubmicron). The foams have been recognized for use in cleaning generally because such bubbles are said to be stable and to have a relatively large surface/volume ratio.
U.S. Patent 4,486,333 issued December 4, 1984 to Sebba discloses and claims a method for preparing such a biliquid foam composition of the polyaphron type (Col. 1, lines 35-47~
for use inter alia in cleaning (Col. 6, lines 31-41) or in mak-ing dispersions from concentrates of emulsified liquids (Col. 6 lines 23-31) to be used, e.g., in solvent extraction. The '333 polyaprhons have globules of 0.1-10 microns and a PVR (phase volume ratio, i.e., ratio of volume of discontinuous phase to volume of lamellar continuous phase) of up to about 50.
First, according to '333, an ordinary gas foam is prepared using water and~or another hydrogen-bonded liquid such as an alco~_i or glycol and a water-soluble surfactant;
intermittentiy, a limlted amount of a nonpolar water-immiscibLe liquid is added and the mixture is agitated to cause the nonpolar liquid to spread on the foam surface and to form no~coalescing globules of nonpolar liquid dispersed in a continuous phase of hydrogen-bonded liquid. Each globule is encapsulated in a double-surfaced film of surfactant and water.
The nonpolar liquid and the surfactant are said to be selected to have a spreading coefficient greater than or equal to zero to permit the nonpolar liquid to initially spread as a thin sheet on the surfactant-containing aqueous lamellae and then to break up in-to fragments and globules (of 0.1-10 micron size) (~ol. 2, lines 55-68).
The total amount of nonpolar liquid thus encapsulated is between 40 and 98% by volume of the entire composition and the PVR is at least 1.5 and up to 49 ('333, claim 1~.
The surfactant in '333 can be any anionic, cationic or nonionic surfactant that would produce a good foam (as long as it fulfills the above spreading coefficient relationship) and it is used in an amount preferably at least about 0.3% by weight of the water (Col. 4, lines 26-32).
The '333 nonpolar liquid also preferably contains a small (up to 5% by weight) quantity of a soluble nonionic surfactant that pe~mits the nonpolar liquid to spread on the aqueous film (Col. 4, lines 50-62).
The '333 invention suffers from the disadvantage that it is difficult to prepare. Also, there is no attempt to tailor a particular polyaphron to a given cleaning task other than as a fuel additive and as a foaming gel although cosmetic applications are alluded to. See, e.g., '333 Example 4.
U.S. Patent No. 4,606,913 issued to Aronson on August 19, 1986 also concerns high-internal phase emulsions (i.e., emulsions in ~hich the internal phase constitutes 74-75% of the total volume) (Col. 1, lines 9-16). Use in industrial cleaning applications is disclosed ~Col. 1, line 30).
The '913 patent recogni~es that choice of the emul-sifier affects the stability of these emulsions and further proposes the incorporation of "an electrolyte' in the emulsion, particularly in the aqueous phase to improve stability.
Although any type of electrolyte is said to be suita~le and trivalent inorganic salts are said to be preferred, only magnesium sulfate and potassium sulfate are claimed (Col. 9, 10line 9; Col. 10, line 60).
~he emulsifiers generally named in the '913 patent are conventional, generally nonionic, emulsifiers usually having an HLB (hydrophilic to lyophilic balance) between 1 and 7 and are said to include comhinations of sorbitan trioleates; mono- and 15multi-phosphoric esters of oleic acid; polyoxyethylene sorbitol hexastearate~, ethylene glycol fatty acid esters, glycerol mono-180 stearates, and sorbitan monooleates; polyoxyethylene 2-oleyl ethers, glycerol/fatty alcohol ethers, esters of polyalcohols, polyethoxylated 2-oleyl alcohols, synthetic 20primary alcohol ethylene oxide condensates; and mono- and di-glycerides of fat-forming fatty acids (Col. 5, lines 34-67).
Emulsifiers are said to be present at 5-30% by weight of the external phase.
The '913 emulsions are said to be prepared by incor-25porating the emulsifier in the oil phase and the electrolyte in the aqueous phase and adding the aqueous phase to the oil phase in small aliquots (not more than 15% of the total oil phase at a time).
U.S. Patent No. 3,976,582 issued to Douglas on August 3024, 1976 discloses a method for making and stabilizing micellar systems including microemulsions having maximum zeta potential for optimizing the recovery of petroleum from shale rock and other subterraneous formations and minimizing the undesirable adsorption of surfactant or rock formations.
35The micell~r systems are said to be made in accordance with known techniques. They comprise 5-20% surfactants (which can be anionic or cationic), 5-60% hydrocar~on solvent, 10-60 electrolyte-containing water and 1-3.5~ "co-surfactant'~.
Cosurfactants are co-solubilizers i.e., semipolar organic compounds, prefe-dbly alcohols.
The ~5~2 invention involves measuri~g th~ zeta poten-tial of a range of micellar systems (varying in aqueous phase content) (the zeta potential is normalized to account for differences in electric conductivity) and selecting as optimum those compositions that have a maximum or near maximum systemic zeta potential.
U.S. Patent No. 4,542,745 discloses an oil-in-water emulsion for use in medical ultrasonic probes containing as the aqueous phase water and alcohol, glycerol or lower alkylene glycol. Th~ oil phase is silicone fluid and is in droplets of 0.15 microns to 1.5 microns in diameter.
U.S. Patent No. 3,813,345 issued to Urton on May 28, 1974 is directed to a method for reducing the micelle size of an oil-in-water emulsion (wherein the oil phase contains an organic solvent, a surfactant and an unsaturated organic compound soluble in the solvent and the aqueous phase in water) by adding to such an emulsion a water-soluble resin with a high number of positive-ion accepting sites and equilibrating this resin with a positive ion donor to cause it to have the same sign of (surface) charge (positive or negative) as the micel-les, there~y causing further subdivision of the micelles. The disclosed use for such micellar systems is in insecticide preparations.
U.S. Patent No. 4,472,291 issued to Rosano on September 18, 1984 discloses viscous oil-in-water microemulsions contain-ing a surfactant, a co-surfactant (emulsifier~ and a secondary surfactant which has the property of increasing the viscosity of the microemulsion. The stated uses of such microemulsions include hard surface cleaners, shampoos, lotions, salves or creams, car waxes, window cleaners, anti~rust formulations and floor polishes (col. 5, lines 35-40).
U.S. Patent No. 4,592,859 issued to Smith-Johannsen on June 3, 1986 is directed to stable suspensions of oil and water in which the droplets of the discontinuous phase are surrounded by colloidal particles having a ~eta potential within the range of +18 to -18 ~V. The suspensions are prepared by adding to water a combination of surfactants (anionic and cationic) which form colloidal particles with the requisite zeta potential.
The oil phase is then added. Disclosed uses include cleaning and polishing compositions, paints, varnishes, impregnants ~or porous surfaces, cosmetics, cement additives, industrial oils and waxes. Pharmaceutical and agricultural uses are also mentioned.
All of the foregoing prior art ~ystems entail compli-cated and time-consuming formulation methods, and/or are not suitable for industrial cleaning applications. They require special equipment and/or calculations and/or sophisticated additives (such as water soluble resins or electrolytes) as well as specific methods of addition of the dispersed phase to achieve the necessary stability and/or globule configuration (si7e and type of the dispersed phase). As a result, the prior art systems are expensive and, most important, their use is confined to specialty applications and they lack the ver-satility necessary for an industrial-type cleaning composikion.
This invention is directed in one aspect to emulsions or microemulsions prepared by simple agitation of water and quantities of single-phase compositions thereafter "progenitor solutions") which contain a combination of at least one surfactant, at least one solvent and at least one emulsifier, the solvent ~eing of selected polarity and all ingredients being of selected refractive index. The resulting emul-sion~microemulsions ~hereafter simply "emulsions") are highly stable and have optimal cleaning ability for a variety of in-dustrial cleaning applications. The foregoing emulsions contain between about 0.1 and about 80% of progenitor solution.
In another aspect, the present invention provides a convenient guide (more specifically a function of solvent polarity and "collective refractive index"--defined below) for varying any ingre~ient used in the foregoing progenitor solutions and/or tile amount of such ingredient in a manner which increases the cleanlng ability of emulsions formed using the progenitor solutions. The emulsions of the present invention can thus be optimized for cleaninq ability (and ca~
be targeted to a particular cleaning ta~k) and, if desired, cost, without using expensive ingredients (such as exotic surfactants or emulsifiers) without using electrolytes and without using special equipment (e.g. equipment to measure zeta potentials).
In yet a third aspect, the present invention is directed to methods of using the foregoing progenitor solutions and emulsions for particular industrial cleaning and soil-removal applications including without limitation removal of tar and/or oil or greases from sand, industrial equipment and other inanimate objects, such as removing thick oils and other soils from hard surfaces (metal, wood, glass concrete, etc.).
DBTAIL~D DE:SCRIPTION OF_TE~E INVENTION
The present invention involves first the formation of stable "single-phase" progenitor solutions which contain 60 to 98% of an organic solvent (preferably 70 to 90%), l to 20% of a surfactant or combination of surfactants soluble in the solvent (preferably S to 20~); and 1 to 20~ of an emulsifier (preferably 2 to 8%)o ~he progenitor solutions are then used to prepare stable emulsions or microemulsions (water-in-oil or preferably oil-in-water) having powerful soil-removal capacity. Both the progenitor solutions and the emulsions made from them can be formulated to be particularly effective in one or more par-ticular cleanlng applications. In fact, the emulsions of the present invention even when produced from a small percentage of progenitor solution (and containing therefore a small per-centage of cleaning agents) are particularly effective soil removal agents. Depending on the choice of solvents, surfac~
tants and emulsifiers, and on the extent of dilution either a true emulsion or a microemulsion may form from the progenitor solutions. Typically true emulsions, i.e. opaque milky liquids result on dilution. ~owever, true microemulsions, i.e.
translucent or almost transparent liquids are also occasionally observed.
It is well known in the art that in order to have effective cleaning agents, the soil to be removed must be penetrated, solvated and removed (sequestrated) from the substrate and dispersed in a cleaning medium. Penetration and dispersion are achieved by surfactants. Ionic surfactants affect the electrostatic propertie~ of the surface to which they adsorb (or film in which they are resident). Nonionic surfactants by orienting their hydrophilic moiety into the so-called Stern layer surrounding a wetted soil particle (assumirlg the medium is aqueous) promote dispersion and inhibit ag-glomeration.
Similar principles apply to stabilization of cleaning emulsion compositions. Stability of an emulsion is promoted by surfactants which act as emulsifiers. They should have good solubility in both the agueous and the oil phase. Often, combinations of surfactants are more effective as emulsifiers than single compounds, as is well known in the art. See, generally Surfactants and Interfacial Phenomena, M.J. Rosen, Wil~y 1978.
The electrical properties of a film or surface are very important in stability of cleaning emulsions and in effective-ness of cleaning ability. The electrostatic surface charges can be measured, but expensive equipment is necessary. A
simpler method for optimi~ing stability and cleaning perfor-mance of emulsions is provided below by the present invention.
Refractive index and polarity of a liquid provide a measure of the electrostatic properties of that liquid. The present inventor was able to correlate the cleaning ability of various emulsions to the polarity and refractive index of their ingredients and corresponding concentration of each ingredient in the progenitor solution. Stabili~ation of the resulting emulsion is governed by the equilibrium of the surfactants within the progenitor sol~tion i.e., surfactants/emulsifiexs are added until they aTe _Dle to completely emulsify or suspend particles of a liquid in a second immiscible liquid. Thi~ is done by routine e~perimentation well within the skill of the axt.
According to the present invention, an arbitrary polarity scale is first established for various s~l~ents ~ased on the physiochemical characteristics of each solvent. This can be done by using , for example, Snyder's Yolarity Index, incorporated by reference. See Snyder, I.R., J. Chromatoqraphy Sci., 16:223, 1978. However, any other polarity scale could be used to generate a polaritytindex function (defined infra).
Table 1 below contains nonlimiting examples of solvents suitable for use in this invention and their assigned polarities ton a scale from 1 to 10).
A collective polarity P can then be calculated for the solvent components of a particular composition as the weighted sum of the polarity of the solvents contained in a given composition according to the formula:
P = (SiPi) where i is an integer from 1 to n, n is the total number of solvents in the composition; Si is the weight fraction of each solvent based on the total composition of the progenitor solution; and Pi is the polarity of that solvent.
Refractive index values for the emulsifiers, surfac-tants and solvents are used to calculate a collective refrac-tive index ND in the same manner ND = ~ XiNi wherein Xi is the weight fraction of a particular component (surface active agent or solvent) and N is the refractive index of the same component. Refractive indices for solvents are ~ .
readily available in the literature (see, e.g., The Merck Index, 11th Fd. and the Handbook of Chemistry and Physics, Chemical Rubber Publ. Co., Cleveland, Ohio) as are those for surfactants.
The ability of each composition to clean a particular type of soil is then measured and the results are correlated with the following empirical polarity/refractive index function (PIF): ~10.N
(10-P) See Figures 1-3 by way of nonlimiting example.
In Figures 1~3 the ability of compositions within the invention to remove tarsand soil when formulated into emulsion containing 10% of a progenitor solution is plo-tted against the polarity/Lndex function f~r each composition. (See data points.) The three figures correspond to the data of Table 3 for 3 types of emulsifier Emulsogen IT (Fig. 2~, Emulsogen SHT (Fig. 1) and Emulsogen EL (Fig. 3). The straight lines drawn through Fi~ures 1-3 represent the best straight-line fit but the cleaning ability is assessed much more accurately by reference to the critical PIF value. Critical PIF value is a value of the polarity index function which when matched or exceeded by variation of the content and chemical identity of the constituents of a progenitor solution results in formation of emulsions essentially all of which have cleaning ability of 60% or more (when cleaning ability is measured by the procedure of the Examples). Critical PIF is thus a function of the particular cleaning task, and is independent of the ingredients of the progenitor solution.
It transpires from Figures 1-3 that tarsand soil (to be removed to a substantial extent, i.e. 60-100%) needs a cleaning composition with a high polarity-index function (in the c~se of Figs. 1-3 given the polarity scale used and the experimental procedure and parameters for assessing cleaning ability the critical PIF value is no less than about 6; in fact a substan-tial increase in cleaning ability is almost universally observed when the PIF is higher than the critical value). This means that the best compositions for cleaning tarsands should have both relatively high polarity and relatively high index of refraction. Indeed, the preferred compositions exempliied below have a collective rPfractive index ND f about 1.4 or more and a collective so'~ent polarity of about 3.0 or more.
Thus, once the critical value of the polarity-index function has been identified, it is possible to conveniently select emulsions that will have a desired cleaning ability for a given task by selecting a com~ination of ingredients and contents which will yield an emulsion with a PIF value equalling or exceeding the critical value. The selection can be refined further ~if desired) using no more than routine experimentation consistent with the present disclosure.
Similar empirical plots can be generated for other 1~ soils than tarsand using only routine experimentation. Thus, the combination of the present invention can be optimized for each cleaning use by identifying the critical polarity index function value for a particular application. It should be emphasized, however, that the cleaning compositions that are most effective for tarsands are also generally effective for other industrial cleaning tasks as tarsand removal is a particularly difficult cleaning task. It is also possible to develop straight-line models for the relationship between soil-cleaning ability and Polarity/Index Function value for each type of soil by using various statistical techniques such as linear regression analysis applied to data such as those of Table 3. In practice, however, this does not appear to be necessary as it is nor~ally easy to identify the critical value for the polarity-index function (which may or may not be numerically the same for different cleaning applications).
It is envisioned that each progenitor solution within the invention will contain at least one organic solvent suit-able for removing the target soil(s), i.e., having sufficient affinity to the soil to solvate it. Nonlimiting examples of species and categories of suitable commercially available sol-vents and their assigned polarities are set forth in Table 1.
.
TA~I,E 1 SOLVENT GEN13RIC NA~ /CATEGORY POI~RITY
Sol~esso 150 aromatic hydrocarbons solvent 3 Butyl Carbitol diethylene glycol monobutyl ether 7 Exxate 600 alkyl oxo-alcohol esters 8 of acetic acid Tabs D menthadiene solvent 5 ~enzyl Alcohol phenyl carbinol 6 Isopropyl Alcohol 9.5 Methyl Carbitol diethylene glycol monomethyl ether 9 Carbitol di0thylene glycol monoethyl ether 8 Isopar K isoparaffinic hydrocarbon solvent 1.5 Xero K paraffinic hydrocarbon solvent 1.5 Nonaromatic solvents, especially those having a flash point higher than 140F, are preferred for enviro~mental reasons.
~roadly, suitable solvents include without limitation aliphatic, aromatic, terpenic, paraffinic, isoparaffinic and olefinic hydrocarbons, alcohols and glycol ethers of the formula CnO(E0)x(PO)yH wherein Cn is an alkyl radical having n carbon atoms (n i5 from 1 to 6), E0 is a -CH2-CH20- (x is an integer from 0 to 4), P0 is -C~(CH3)-CH2-0- or -CH2-C~(CH3)0-(y is an integer from 0 to 4), benzyl alcohol, alkyloxoalcohol esters of lower aliphatic acids, substituted glycols of the formula CnO(E0)xCn (with n and x as defined a~ove), glycols of the formula H(E0)xH and H(PO)yH (wherein E0, P0, x and y have been defined above) and acetate esters of glycol ethers.
The progenitor solution will contain at least one surfactant soluble in the solvent. The choice of surfactant depends on the compatibility with the solvent and/or solvent composition of the progenitor solution and the soil to be removed. Compatibility of the surfactant with solvent and soil is determined from supplier information or is within the ordinary skill in the art including at times routine experimen-tation. Preferably, the cleaning emulsion will contain at least two surfactants which may be nonionic and/or cationic and or amphoteric. Both (or all) surfactants are preferably incor-porated in the progenitor solution. Anionic and zwitterionic surfactants can also be used.
Suitable surfactants generally include without limita-tion those disclosed, e.g., in Norris U.S. Patent No. 3,663,961 (5/23/72) incorporated by refP_ence and in Surfactants ~nd 5 Interfacial Phenomena by MiltcJ. Rosen, John Wiley ~ Sons, 1978, pp. 1-17, also incorporated by reference. Other suitable surfactants include:
Suitable anionic surfactants generally include without limitation water-soluble salts of alkylbenzene sulfonates, alkyl sulfates, alkyl polyethoxy ether sulfates, paraffin sulfonates, alpha-olefin sulfonates, alpha-sulfocarboxylates and their esters, alkyl glyceryl ether sulfonates, fatty acid monoglyceride sulfates and sulfonates, alkyl phenol polyethoxy ether sulfates, 2-acryloxy-alkane-l-sulfonates, and beta-alkyloxy alkane sulfonates. For more specific examples, see U.S. Patent No. 4,414,128, col. 3, lines 60-68 & col. 4, incorporated by reference.
Suitable nonionic surfactants include alkoxylated compounds produced by the condensation of alkylene oxide groups with an organic hydrophobic compound (aliphatic, aromatic or arylaliphatic). The length of the polyoxy alkylene group should be controlled (which can be accomplished in a manner known per se) so that the resulting surfactant is liquid and, where applicable, soluble in the solvent or solvent mixture 2S used for the progenitor solution. More specific examples of these nonionic surfactants are disclosed, e.g., in U.S. Patent No. 4,414,128, col. 5, lines 14-68 and col. 6, lines 1-14, incorporated by reference.
Suitable cationic surfactants include without limita-tion those disclosed in U.S. Patent No. 3,813,345, col. 8, lines 42-53, incorporated by reference.
Amphoteric and zwitterionic surfactants include without limitation those disclosed in U.S. Patent No. 4,414,128, col.
6, lines 31-66, incorporated by reference.
Preferred are surfactants such as nonionic ethoxylates (e.g. Igepals, Surfonics) anionic surfactants (such as Sulframin, Sulframin AOS) and cationic surfactants (such as Bardacs, Hyamine, Genamin 8). All materials disclosed or referenced herein are readily commercially available.
In general, the choice of emulsifier will depend on (a) the desired stability of the emulsion; (b) whether an oil-in-water or a water-in-oil emulsion is desired; and (c) the type of soil to be removed. A hydrophilic emulsifier will best stabili~e O/W emulsions while a liophilic emulsifier stabilize6 best W/O emulsions. A highly oxidized SOLl would require a more hydrophobic emulsifier than a relatively unoxidized 80il~
In principle any emulsifier that contributes to the desired PIF
Yalue can be used, including without limitation those disclosed in Aronson U.S. Patent No. 4,606,913.
Preferred examples of emulsifiers include the follow-ing:
Table 2 Emulsifier Composition Supplier Example _ _ Igepal Ca 420 Ethoxylated octyl phenol GAF
Brij 92 Ethoxylated (2) oleyl ether ICI
Span 80 Sorbitan monooleate ICI
Span 85 Sorbitan trioleate ICI
Atmos 300 Mono and di glycerides of fat forming fatty acids ICI
Drewmulse GMO Glycerol monooleate PVO
Kessco Ester Glycerol monooleate ARMAK
Drewpole 10-4-0 Decaglycerol tetraoleate PVO
Liposorb SQO Sorbitan Sesquioleate Lipo Chemicals Magnesium oleate Ethoxylated (3) oleyl ether Croda Volpo 3 Bodag GMR Glycerol mono ricinoleate Hodag Emulsogen E = Combination of fatty amine American salts with alkyl aryl poly- Hoechst Corp.
glycol ethers Emulsogen M = Fatty alcohol polyglycol ether '~
Emulsogen A = Fatty alcohol polyglycol ether ester Emulsogen B~ = Ami.ne salt of a7~vl sulfamide carbonylic acid Emulsogen D.G. Alkyl aryl polyglycol ether ~mulgin IT-60 Fatty acid polyglycol ~enkel Chem.
ester Corp.
Emulgin TL-55 Fatty acid polyglycol ester "
Icomeen T-15 Fatty amine ethoxylates BASF
Emulan FM Triethanolamine monooleic BASF
acid ester Marlowet OFW Mixture of n-alkyl benzene Huls Canada, sulfonate, carboxylic acid Inc.
polyglycol esters and alkyl polyclycol ether The incorporation of electrolytes is not necessary, but if desired for a particular application, electrolytes could be used as additional optional ingredients. Suitable electrolytes include monovalent divalent and polyvalent inorganic salts such as halides sulfates, carbonates and phosphates, of alkali metals, alkaline earth metals and heavy metals and mixtures of such salts. It is emphasized, however, that electrolytes are not necessary.
The progenitor solutions of the present invention are prepared by blending surfactants, emulsifiers and solvents (as well as optional ingredients such as thickening agents, dyes, perfumes, preservatives, anti-oxidants, etc.) in normal conventional equipment commonly used in the chemical specialty industry. For example, simple mixing or blending vessels such as stainless steel tanks equipped with an agitator (e.g. a Lightnin~ mixer) are sufficient. Solvents are added first into the blending vessel. The agitation is started and the remain-ing ingredients s~lrfactants, emulsifiers, etc. are added and blended until the mixture is homogeneous. This may require mixing at e.g. 50-200 rpm for several minutes to several hours depending on tank volume and agitator si~e.
The emulsions of the present invention are prepared by -- 5 simple dilution of the progenitor solution into water with normal agitation. The water can be any temperature, e.g. as required for the cleaning application, but it is preferably warm (e~g. 50~C or above). Soft water is preferred.
The emulsions can contain from 0.1 to 80% of the - 10progenitor ~olution. Generally, a 1-10% concentration is ~ufficient for most industrial cleaning jobs, and is pref~rred.
The in~ention is further illustrated below by reference to specific non-limiting Examples.
Example 1: Soil Removal Assessment 15Standard tarsand soils were prepared by smearing 2.5 cm x 2.5 cm x 0.3 cm tarsand (alternatively jesco grease or 80-10 mixtures of tarsand and jesco could have been similarly prepared) on Q-panels (i.e., metal testing panels having a Q-shaped hole) and baking the applied soil for 30 minutes at 20120~C. The panels were thereafter left to attain atmospheric equilibrium for 24 hours. This procedure is referred to in the claims as Q-panel testing.
Other test soils such as multi-use and automotive greases, gear oils, or automotive under coatings could be 25prepared for assessment in the same manner.
Finally, test soils could be alternatively prepared as follows: Roofing tars or soils containing plasticizers or any type of soil com~ination (greases, oils, waxes, etc.) are smeared on metal panels and exposed to the elements (e.g., on 30roofs or walls) for aging. The applied soil thickness is in all cases controlled via an applicator gauge.
Example 2: Preparation of Progenitor Solutions and Emulsions To a 2000 ml beaker containing a magnetic stirring bar 35placed on a magnetic stirrer 100 g of Solvesso 150 were added followed by 100 g Tabs D, 100 g methyl carbitol, 75 g of Rexonic 91-8, 75 g Hyamine 3500 and finally 50 g of Icomeen T-150 The final mixture was stirred for 30 minutes and then stored for use. This resulted in progenitor solution 20.
Additional solutions were made in the ~ame manner with sub-stitutions of various ingredients, In all cases the emulsifierwas added last to the mixture of solvent(s) and surfactant.
The ingredients and amounts for all the resulting progenitor solutions of this Example 2 are set forth in Table 3. In each case only one emulsifier was used and thus Solution No. l, for example, is really 3 different compositions: one with Emulsogen IT, one with Emulsogen S~T and one with Emul-sogen EL.
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~o ~, I l ' I 'o I I I o ~ ao` _J_l I ~ I I I o I I * ~ I I I I I I ~ o -'`' I ~n l I I ~
Emulsions were made containing 10% of each progenitor solution in about 50C water by introducing a 10% vol. aliquot of progenitor solution into 90% vol. of water with agitation until homogeneous.
As apparent from Table 3, the co~_entration of the emulsifier was maintained at a constant level (5~) throughout all systems tested (except for progenitor solution 21-1). The same was done with the surfactant concentration (15%). This was done to normalize the data and does not imply that the emulsifiers and surfactants are limited to the amounts listed in Table 3. Various solvents of high and low polarity were used. The emulsions were transferred to a pump spray bottle and hand-sprayed onto the tarsand spray panels for one minute.
(Thi~ is also part of the Q-panel testing procedure.) The amount of tarsand removed was visually estimated and recorded. The results are also set forth in Table 3. The soil removal ability for various emulsions can be vastly different even when the ingredients are present in the same proportions. See in particular the systems that have identical surfactants and solvents but different emulsifiers. See also the systems that have the same surfactants and emulsifiers but different solvents. The emulsion stability was tested at 4C, 35C and at ambient temperatures for those emulsions that gave satisfactory cleaning performance. Stability testing involved preparations of emulsions containing 10~ and 20% of a mother solution in water and left to stand at 4C for three months;
ambient temperature for three months and 35~C for three months.
No coalescence was observed at this time; only occasionally minimal "creaming" occurred at 35C.
Example 3: Correlation of Polarity Index Function and Cleaninq Ability The collective polarities for each solvent mixture of each progenitor solution in Table 3 are set forth in Table 4 below:
TP.BLE: 4 COI,LE CTIVE POLARITI~:S FOR SOLVE~IT
Progenitor Solution of Solvent Polarity 1 ~.8 ~ 2.9 4 3.0 2.9 6 3.25 ~ 3.2 9 3.1 3.6 13 3.5 14 1.2 4.0 16 2.4 17 1.2 18 1.2 19 3.0 3.2 221-1 2.93 The collective refractive indices for the emulsions o~
Table 4 are set forth in Table 5 below:
9 ~ ~ 3 _ I I I I I I g~ I I g} I ~ ;; ~ ~
~' ~ ~' I I I I y I I
W I I I W I I I ~
_ I I ~ W
~ I I I I I I I I I h ~
I I I I I I I I I
o I I I I I I i I I I I I I I I I I I I I I
_ I I I ~ I 1 8 ~, Figures 1-3 represent a plot of the cleaning ability for tarsand 50il removal against the polarity/index function (PIF) of each composition of Table 3.
The critical PIF value of about 6 in Figs. 1-3 has been use ul in determining the best cleaning emulsion for the following soils:
: tarsand tarsand-jesco grease multi-use gr~ases ;- 10 gear oils Thus the data points in Figs. 1-3 permit the selection o~ the most effective progenitor solution to assess the optimum efficacity for tarsand solid removal. Alternatively, they lend themselves to utilizing and selecting a different solvent and/or surface active agents to yield the desired polarity/in-dex function (which should be at least equal to the critical value)~ ~It should be noted that the index of water was not used in computing the datapoints of Figures 1-3 ~ecause all the emulsions had the same amount of water.) Ideally, the PIF OL
the progenitor solution should be as close to the critical value as will yield the desired cleaning ability. Further improvements in cleaning ability can be effected using no more than routine experimentation.
Similar graphs can be generated in the manner disclosed above for other emulsions of different ingredients and proper-ties and for different cleaning tasks under different condi-tions. For example, emulsions containing 10% of progenitor solution #5 containing Emulsogen IT, and progenitor solution #3 containing Emulsogen SHT were effective against tarsand but not jesco oil. However, all compositions that worked on jesco (a tougher soil) also worked on tarsand. Particularly preferred progenitor solutions are solutions #15 and #20 in Table 3.
Also the following are preferred:
Isopar K 68.3 39.3 6.0 d-limonene 25.0 12.9 8.0 87.0 methyl carbitol 68.4 40.2 45.0 butyl carbitol 35.0 Eco~een T 1.7 3.0 Emulsogen A 1.7 0.9 l.O 1.0 2.0 Emulsogen T 2.5 Comperlan VOD 0.8 1.0 Emulsogen ~15 4.9 4.5 4.5 1~0 1~
~yamine DMB 451 6.5 7.5 7.5 Igepal C0630 6.5 7.5 7.5 Also particularly preferred are emulsions containing from about 0.5 to about 30% of one of the for~going preferred progenitor solutions.
Claims (25)
1. An emulsion comprising (a) 0.1-80% of a progenitor solution comprising the following ingredients:
(i) 60 to 98% of at least one solvent (ii) 1 to 20% of at least one emulsifier surfactant, and (iii) 1 to 20% of at least one additional surfactant; and (b) the balance being 99.9-20% water;
said emulsion having been prepared by simple addition of the progenitor solution to warm water with ordinary agitation; said ingredients being selected to yield a polarity index function (PIF) being defined as having a value at least equal to a previously established critical value wherein ND is the collective refractive index of the progenitor solution and P is the collective polarity of said at least one solvent; said critical value being the PIF value of emulsions that have an ability to clean at least 60% of a soil, when said emulsions are subjected to Q-panel testing and containing 10%
of a progenitor solution.
(i) 60 to 98% of at least one solvent (ii) 1 to 20% of at least one emulsifier surfactant, and (iii) 1 to 20% of at least one additional surfactant; and (b) the balance being 99.9-20% water;
said emulsion having been prepared by simple addition of the progenitor solution to warm water with ordinary agitation; said ingredients being selected to yield a polarity index function (PIF) being defined as having a value at least equal to a previously established critical value wherein ND is the collective refractive index of the progenitor solution and P is the collective polarity of said at least one solvent; said critical value being the PIF value of emulsions that have an ability to clean at least 60% of a soil, when said emulsions are subjected to Q-panel testing and containing 10%
of a progenitor solution.
2. A method for cleaning industrial soils from a substrate comprising the steps of:
(a) applying to said substrate an emulsion having been prepared by simple agitation of about 0.1-80% of a progenitor solution and about 99.9-20% water, said progenitor solution comprising the following ingredients:
(i) 60 to 98% weight of at least one solvent (ii) 1 to 20% weight of at least one emulsifier surfactant; and (iii) 1 to 20% weight of at least one additional surfactant, said at least one solvent having collective polarity P
and said ingredients having collective refractive index ND and said emulsion having a polarity index function (PIF) value greater than a previously established critical value, said PIF
being defined as ; said critical value being the PIF
value of emulsions that would have the ability to clean at least 60% of a soil when subjected to Q-panel testing and containing 10% of a progenitor solution;
(b) contacting said emulsion with said soils for a period of time sufficient to remove said soils from said substrate; and (c) removing the spent emulsion from said substrate.
(a) applying to said substrate an emulsion having been prepared by simple agitation of about 0.1-80% of a progenitor solution and about 99.9-20% water, said progenitor solution comprising the following ingredients:
(i) 60 to 98% weight of at least one solvent (ii) 1 to 20% weight of at least one emulsifier surfactant; and (iii) 1 to 20% weight of at least one additional surfactant, said at least one solvent having collective polarity P
and said ingredients having collective refractive index ND and said emulsion having a polarity index function (PIF) value greater than a previously established critical value, said PIF
being defined as ; said critical value being the PIF
value of emulsions that would have the ability to clean at least 60% of a soil when subjected to Q-panel testing and containing 10% of a progenitor solution;
(b) contacting said emulsion with said soils for a period of time sufficient to remove said soils from said substrate; and (c) removing the spent emulsion from said substrate.
3. The emulsion of claim 1, wherein said at least one solvent has a collective polarity of at least about 2.0 and said progenitor solution has a collective refractive index of at least about 1.35.
4. The emulsion of claim 3, wherein:
said solvent is selected from the group consisting of aliphatic, aromatic, terpenic, paraffinic, isoparaffinic and olefinic hydrocarbons, alcohols and glycol ethers of the formula CnO(EO)x(PO)yH wherein Cn is an alkyl radical having n carbon atoms (n is from 1 to 6), EO is a -CH2-CH2O-(x is an integer from 0 to 4), PO is -CH(CH3)-CH2-O- or -CH2-CH(CH3)O- (y is an integer from 0 to 4), benzyl alcohol, alkyloxoalcohol esters of lower aliphatic acids, substituted glycols of the formula CnO(EO)xCn (with n and x as defined above), glycols of the formula H(EO)xH and H(PO)yH (wherein EO, PO, x and y have been defined above) and acetate esters of glycol ethers and combinations of at least two thereof;
said emulsifier is selected from the group consisting of cationic, nonionic and anionic emulsifier surfactants and combinations of at least two thereof; and said surfactant is selected from the group consisting of nonionic, cationic, anionic, zwitterionic and amphoteric surfactants and combinations of at least two thereof.
said solvent is selected from the group consisting of aliphatic, aromatic, terpenic, paraffinic, isoparaffinic and olefinic hydrocarbons, alcohols and glycol ethers of the formula CnO(EO)x(PO)yH wherein Cn is an alkyl radical having n carbon atoms (n is from 1 to 6), EO is a -CH2-CH2O-(x is an integer from 0 to 4), PO is -CH(CH3)-CH2-O- or -CH2-CH(CH3)O- (y is an integer from 0 to 4), benzyl alcohol, alkyloxoalcohol esters of lower aliphatic acids, substituted glycols of the formula CnO(EO)xCn (with n and x as defined above), glycols of the formula H(EO)xH and H(PO)yH (wherein EO, PO, x and y have been defined above) and acetate esters of glycol ethers and combinations of at least two thereof;
said emulsifier is selected from the group consisting of cationic, nonionic and anionic emulsifier surfactants and combinations of at least two thereof; and said surfactant is selected from the group consisting of nonionic, cationic, anionic, zwitterionic and amphoteric surfactants and combinations of at least two thereof.
5. The emulsion of claim 4, wherein said progenitor solution comprises 5% of one of a nonionic emulsifier consist-ing of a mixture of ethoxylated triglycerides with calcium aryl alkyl sulfonate, an anionic emulsifier consisting of the sodium salt of alkyl sulfonamido carboxylic acid and a nonionic emulsifier comprising a fatty acid polyglycol ester.
6. The emulsion of claim 5, wherein said progenitor solution comprises 7.5% of a cationic surfactant comprising nonylphenoxy poly(ethylenoxy)ethanol and 7.5% of one of nonionic surfactant comprising -N-alkyl(C12, C14, C16,)dimethyl benzyl ammonium chloride and a nonionic surfactant comprising nonylphenoxy polyethoxy ethanol.
7. The emulsion of claim 6, wherein said solvent comprises 60% Solvesso 150, 10% butyl carbitol, and 10% Tabs D.
8. The emulsion of claim 6, wherein said solvent comprises 60% Solvesso 150, 10% Tabs D and 10% benzyl alcohol and said emulsifier is Emulsogen IT.
9. The emulsion of claim 6, wherein said solvent comprises 60% Solvesso 150, 10% Tabs D, and 10% isopropyl alcohol.
10. The emulsion of claim 6, wherein said solvent comprises 50% Solvesso 150, 10% Tabs D, and 20% isopropyl alcohol.
11. The emulsion of claim 6, wherein said solvent comprises 60% Solvesso 150, 10% Tabs D, and 10% methyl car-bitol.
12. The emulsion of claim 6, wherein said solvent comprises 60% Solvesso 150, 10% Tabs D, and 10% carbitol.
13. The emulsion of claim 6, wherein said solvent comprises 50% Solvesso 150, 10% Tabs D, and 20% carbitol.
14. The emulsion of claim 6, wherein said solvent comprises 40% Solvesso 150, 10% Tabs D, and 30% carbitol.
15. The emulsion of claim 6, wherein said solvent comprises 70% Solvesso 150, and 10% carbitol.
16. The emulsion of claim 6, wherein said solvent comprises 60% Solvesso 150, and 20% carbitol.
17. The emulsion of claim 6, wherein said solvent comprises 80% Tabs D.
18. The emulsion of claim 6, wherein said solvent comprises 80% Solvesso 150.
19. The emulsion of claim 4, wherein said progenitor solution comprises 5% Icomeen T-15 cationic emulsifier.
20. The emulsion of claim 19, wherein said progenitor solution comprises 7.5% Hyamine 3500 cationic surfactant and 7.5% of one of Igepal CO-630 nonionic surfactant and Surfonic N91-8 nonionic surfactant.
21. The emulsion of claim 20, wherein said solvent is 60% Solvesso 150, 10% butyl carbitol, and 10% Tabs D.
22. The emulsion of claim 20, wherein said solvent is 60% Solvesso 150, and 10% butyl carbitol.
23. The method of claim 2 wherein said critical value is about 6.
24. The method of claim 23 wherein said soil is a tarsand soil.
25. An emulsion comprising (a) 0.1-80% of a progenitor solution comprising the following ingredients:
(i) 60 to 98% of at least one solvent (ii) 1 to 20% of at least one emulsifier surfactant, and (iii) 1 to 20% of at least one additional surfactant; and (b) the balance being 99.9-20% water;
said emulsion having been prepared by simple addition of the progenitor solution to warm water with ordinary agitation; said ingredients being selected to yield a polarity index function (PIF) being defined as having a value at least equal to a previously established critical value wherein ND is the collective refractive index of the progenitor solution and P is the collective polarity of said at least one solvent; said critical value being the PIF value of emulsions that would have a substantially increased ability to clean a soil compared to emulsions having a PIF below said critical value.
(i) 60 to 98% of at least one solvent (ii) 1 to 20% of at least one emulsifier surfactant, and (iii) 1 to 20% of at least one additional surfactant; and (b) the balance being 99.9-20% water;
said emulsion having been prepared by simple addition of the progenitor solution to warm water with ordinary agitation; said ingredients being selected to yield a polarity index function (PIF) being defined as having a value at least equal to a previously established critical value wherein ND is the collective refractive index of the progenitor solution and P is the collective polarity of said at least one solvent; said critical value being the PIF value of emulsions that would have a substantially increased ability to clean a soil compared to emulsions having a PIF below said critical value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2060718 CA2060718A1 (en) | 1992-02-05 | 1992-02-05 | Soil-removal microemulsion compositions and methods for making them and using them |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA 2060718 CA2060718A1 (en) | 1992-02-05 | 1992-02-05 | Soil-removal microemulsion compositions and methods for making them and using them |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2060718A1 true CA2060718A1 (en) | 1993-08-06 |
Family
ID=4149215
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2060718 Abandoned CA2060718A1 (en) | 1992-02-05 | 1992-02-05 | Soil-removal microemulsion compositions and methods for making them and using them |
Country Status (1)
| Country | Link |
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| CA (1) | CA2060718A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ITMI20091598A1 (en) * | 2009-09-18 | 2011-03-19 | Eni Spa | PROCEDURE FOR RECOVERY OF OILS FROM A SOLID MATRIX |
-
1992
- 1992-02-05 CA CA 2060718 patent/CA2060718A1/en not_active Abandoned
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| ITMI20091598A1 (en) * | 2009-09-18 | 2011-03-19 | Eni Spa | PROCEDURE FOR RECOVERY OF OILS FROM A SOLID MATRIX |
| WO2011033354A1 (en) * | 2009-09-18 | 2011-03-24 | Eni S.P.A. | Process for the recovery of oils from a solid matrix |
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