US2107288A - Liquid composition for degreasing surfaces and process of preparation - Google Patents

Description

Patented Feb. 8, 1938 UNITED STATES LIQUID COMPOSITION FOR DEGREASING SURFACES AND PROCESS TION F PREPARA- Alton F. Curran, Maiden, Mass, assignor to The Curran Corporation, Maiden, Mass., a corporation of Massachusetts No Drawing. Application January 11, 1936, Serial No. 58,758

9 Claims.

This invention relates to a liquid composition for degreasing and otherwise conditioning surfaces and the process of preparing such composition. While not limited thereto, the composition of the present irfvention is intended for the purpose of degreasing metal surfaces of all kinds while at the same time exposing the surface to the action of free caustic alkali in desired amount, depending upon the particular metal being treated and the particular effect to be produced on the metal surface.

From the standpoint of its stability and physical homogeneity, the liquid composition of the present invention can be considered as a solution of liquid soap and free alkali in an organic solvent which is preferably greatly diluted with another organic solvent of high effectiveness as a grease solvent. The stability and physical homogeneity of such a composition is attributable 20 to the fact that other than the very small amount of water of reaction present therein, it is subsantialiy anhydrous. Indeed, when a substantial amount of additional water is admixed therewith, say, about 15%, its soap content tends to 25 separate out, possibly on account of the saltingout effect of the substantial amount of aqueous alkali solution produced therein.

Generally speaking, the composition of the present invention is prepared by dissolving caustic alkali in a suitable organic solv'entin the substantial absence of water and adding the re- 1 suiting solution to liquid soap-forming substance in amount calculated to yield liquid soap solu-' tion containing free alkali. The resulting composition is compatible or miscible with a large amount of various grease solvents, such as pine oil, kerosene, light fuel oil, and liquid hydrocarbons in general, chlorinated hydrocarbons and the like. While grease solvent may appear in the composition as sold, it is generally preferable that the user add most, if not all, of the grease solvent to the composition preparatory to its use so as to save the expense-of packaging and shipping the grease solvent, which is avail able virtually everywhere and is readily miscible with the composition.

An important advantage of the composition of the present invention is its ready self-emulsifiability in water. This means that once the composition has been applied to a metal or other surface to be degreased and the grease solvent has been permitted to penetrate the grease and render it sufficiently fluid to be readily emulsifiable in water, water may be delivered in copious quan- 55 tity, as from a hose nozzle, onto the surface so as to wash away the grease in emulsified form together with the composition, the soap content of the composition dissolving inthe water-and acting as 'the emulsifying agent forthe solventmodified grease and the grease solvent. The

quality of self-emulsifiability of the composition is traceable to its free alkali content; for when it is devoid of free alkali, it does not lend itself to being readily or cleanly washed away together with greasy substance from'the surface to which it is applied. The ready self-emulsifiabilityof the composition may be displayed by pouring a While it is possible to use-various alkalies, ineluding caustic soda, for saponi'fying soap-form-- ing substances to produce the liquid or semiliquid soap component of the compositions of the. present invention, causticpotash is generally preferable for such purpose as it yields'liquid soaps from a wider variety of saponifiable substances, for instance, inexpensive saponifiable substances such as are most practicable for such compositions. Thus, the inexpensive liquid saponifiable substance known on the market as Tallol yields upon saponification' with caustic potash a liquid soap of especially high greaseemulsifying potency probably by reason of the fact that this saponifiable substance which is available as a by-product from kraft pulp manufacture, is rich in both rosinacids and fatty acids of complex character. I may hence use Tallol as the soap-forming substance and saponify such substance to form a soap of suitable character with caustic potash-or with a mixture of caustic potash and caustic soda containing up to about 50%by Weight of caustic soda. Other alkalies, such as ammonia, or alkali equivalent or bases, such as triethylanolamine and other amines, may be used in lieu of caustic potash to produce the desired liquid or gell-like soap, but because such other alkalies or alkali equivalents are more expensive than caustic potash and present no particular advantage thereover for my purpose, I consider them less desirable, excepting perhaps in special cases.

The organic-solvent employed to carry the alkali to the saponifiable substance may, in some cases, advantageously be a phenol. When substance in amount more than that necessary for stantiallyj anhydrous caustic alkali is added to cresylic acid, it dissolves and reactsto form alkali cresylate. Alkaliin excess of that forming the cresylate does not'go into solution. Accordingly, I' add to the cresylic acid an amount of caustic alkali calculated to react withsubstantially all of the cresylic-acid. Alkali cresylate containing combined therewith. alkali in. amount much greater than that necessary to saponify the liquid soap-forming substance isthen added to such substance, with the result that the alkali radical disassociates itself from" the cresylic and.

radical to combine with the soap-forming substance. Indeed, when alkalias alkali cresylateis added to the liquid soap-forming substance in.- amount'theoretically necessary to saponify such substance, substantially all of the alkali disassociates itself from the cresylic acid to combine .with the soap-forming substance. By'addingalkali asalkali cresylate in amount greater than that capable of combining with the soap-form- .ing substance, the alkali'cresylate provided-in the composition tends to hydrolyze and thus to furinduce prompt self-emulsifiability of the compo-- sition. To this end, after the soap-forming substance has been treated with alkali combined as cresylate in'amount calc'ulated to effect substan tially complete saponiflcation of the 'soap-form-' ing substance, ,additionalffree alkali is added in the form of a substantially anhydrous solution in suitable inert organic solvent, preferably ethyl,

"'butyl, or" other alcohol, and in amount greater thanthattheoretically capable. of combining with the free cresylic acid originally combined with alkali but then transferred tothe soap-forming substance. If "desired, such inert organic liquids as diethylene glycolwmonobutyl ether, and diacetone, all-"of which are solvents of caustic alkali, might be used in lieu ofalcohol. Insome instances, as when maximum alkalinity in the finished composition is desired from a given alkali usage beyond that necessary for saponification -of the soap-forming substance, the use of cresylic acid asa solvent or carrier for the alkaliis dispensed with and alkali in the form of a substantially anhydrous solution in. suitable inert organic solvent is added to thesoap-forming subsaponifying such substance.

It'is, of course,-possible to prepare a wide range of compositions embodying the present invention from suitable raw materials employed in various amounts. It is to be understood, therefore, that the particular compositions and their mode of preparation presently to be described are merely illustrative. use Tallol as the soap-forming substance. The Tallol' sold'on the market may contain various proportions of rosin acids and fatty acids, but, for my purpose, I regard as most satisfactory a grade of Tallol containing about 45% to 70% of rosin' acids, about 45% to 20% of" fatty acids, and about-lO% of inert or unsaponifiableorganic substance probably of the nature of hydrocarbon. Thus, I=may start-with, say, IOO'pa-rts by weight of Tallol'specifically composed of 45% rosin acids, 45% fatty acids, and-10% inert'sub- As" already indicated, I prefer to stance. I have determined that thisspeciflc Tal 101 requires about 16parts by weight of caustic potash for substantially complete saponiflcation. In saponifying the Tallol, I add thereto the substantially anhydrous solution of caustic potash in inert organic solvent or carrier. When the carrier is cresylic acid, 32 parts by weight of cresylic acid should be used for carrying or transferring to the parts by weight of 'Tallol the 16 parts by weight of caustic potash required for substantially complete saponification. I hence admix caustic potash with cresylic acid in such proportions to cause the potash to consume the cresylic acid completely by reaction to form liquid cresylate and simultaneously to go into solution. The resulting liquid cresylate is then combined with the Tallol, in consequence of which the potassiumradical disassociates itself practically completely from the cresylate to saponify the -'I allol, thereby regenerating the cresylic acid.

When grease solvent is added to the resulting Tallol-soap-containing composition, the composition does not emulsify or wash away as easily as desired from a surface to which it is applied. I have found, however, that when an inert organic liquid solution of free alkali in substantially anhydrous condition is added'to the composition, it is rendered readily self-emulsifying even when a large amount of water-immiscible grease solvent is associated with the composition. One way of furnishing the composition with free alkali is to dissolve substantially dry caustic'potash in substantially anhydrous, inert organic liquid miscible with the composition, for instance, ethyl, butyl, or other alcohol. The amount of dissolved free alkali added to the composition is preferably in excess of that theoretically combinablewith the cresylic acid regenerated in the composition. Thus, to the particular composition hereinbefore described, I add more than 16 parts by weight of dissolved caustic potash, for instance, as much as 30 or even more parts by weight of caustic potash. The caustic potash may be dissolved completely in, say, 2 to 3 parts of itsweightof ethyl or butyl alcohol and the resulting alcoholic solution added to the composition. The resulting composition containing free caustic alkali is compatible or miscible with a large amountof grease solvent, such as, kerosene, light fuel oil, pine oil, xylol, trichlorethylene, carbon tetrachloride, etc., which may be used to dilute the composition at any time preparatory to use.

A composition prepared as hereinbefore described is readily self-emulsifiable; and this property is, as already indicated, exhibited at once by its break-up upon being added to water into a milky emulsion substantially devoid of visible grease solvent particles even when grease solvent is by far its largest single component. The composition is an excellent degreasing agency especially for metal surfaces and is useful for such purposes as degreasing metals preparatory to electro-plating and cleaning the bores of firearms and cannons. The grease solvent component 'of the composition gets at the grease contamination present on a surface and conditions it for prompt emulsiflcation and its free alkali component tends to react with such saponiflable ingredient as may be associated with the grease contamination to form a soluble soap which is dissolved and washed away along with the composition and unsaponiflable grease ingredients under the action of wash water. When metals of the class of iron or steel are treated with the composition, such metal oxide as may be present on the surface tends to react with the free alkali content of the compositionand .to be washed away along with the wash water employed in removing the composition. The metal surface is thus well-conditioned for an electroplating operationf The free alkali component of the composition also tends to etch the metal surface and thus to leave it with a tooth conducive to good bonding afiinity for metal plating. When the composition is applied to metals of the class of aluminum, which tend to react with alkali to form an oxide coating, it may be of value in that its .degreasing action is attended by formation of an oxide coating. After washing the composition from oxide-coated aluminum, the aluminum is useful for some purposes as such or it may be coated or dyed. Thus, the dyeing of the oxide-coated aluminum surface may be efiected with dyes capable of reacting with the oxide coating to generate insoluble color lakes.

In lieu of using cresylic acid or other phenol as a carrier for substantially anhydrous caustic alkali, an alcoholic or equivalent inert organic liquid solution of the causticalkali may supply both the alkali necessary to ,saponify the soapforming substance and the free alkali desired in the finished composition. Thus, substantially dry caustic potash in excess of 16 parts by weight may be dissolved in the appropriate volume of ethyl, butyl, or other alcohol and the alcoholic caustic potash solution then admixed with the 100 parts by weight of Tallol hereinbefore described to produce the desired finished composition containing free'alkali. Since the amount of free alkali used in excess of 16 parts by weight determines the free alkalinity of the resulting composition, this amount is controlled, 1

depending upon the particular use to which the composition is to be put. A composition de-' void of alkali cresylate is preferred for a use wherein maximum free alkalinity is desired, for instance, in forming oxide-coated aluminum. In this connection, it might be noted that when cresylic acid is used as an alkali carrier in the preparation of a composition, it is necessary in 2 order to impart to the composition the property of ready seli-emulsifiability to provide alkali in amount greater than that necessary for saponifying the [*allol soap and combining with all of the cresylic acid. It is thus seen that by avoid ing the use of cresylic acid, it is possible through the use of a given amount of alkali to realize finished compositions of maximum free alkalinity.- In those instances, however, when an instantly self-emulsifying composition having minimum tendency to attack metal is desired, the provision of alkali as alkali cresylate in the composition may be preferable even though alkali must be used in amount beyond that necessary to form the soap and cresylate in order to impart to the composition the quality of ready self-emulsifiability. Compositions thus prepared with an alkali cresylate content may be closely controlled in their reactivity on metals. Apparently the alkali cresylate content of such compositions hydrolyzes to liberate free alkali and the hydroxyl ions thus generated repress the ionization of the free alkali present therein beyond that combinable as cresylate. In any event, a cresylate-containing composition wherein there is free alkali beyond that combinable as cresylate has the desired property of ready self-emulsifiability probably on account of its considersolvent to surfaces, for instance, to metal surfaces to be degreased and/or otherwise conditioned thereby. The compositions thus applied are preferably anhydrous, excepting for the small amount of water liberated in the saponification of the soap-forming substance and the small amount of water liberated in the formation of The various compositions of the present invention exhibit the property of true solutions in so far as concerns their substantial physical homogeneity and stability and, in fact, when diluted with large amount of grease solvent, such as'kerosene, are

of clear, sparkling appearance and highly penetrative of grease contaminations. preciable amount of water is added to such compositions, they become unstable in the respect that soap particlestend to separate out therefrom. However, the small amount of water of reaction present in such compositions is sufficient to promote reactivity of their free alkali content with metal surfaces when the free alkali content is unrepressed and suflicicntly great to promote such reactivity; and the small amount of water of reaction present in such compositions is also sufficient to promote hydrolysis of the alkali cresylate and thus to ensure a sufficient buffer efiect against a small free alkali'contcnt in the compositions beyond that combinable as cresylate to inhibit any appreciable attack on metal surfaces.

In lieu'of using Tallol as the liquid soap-forming substance of my compositions, I may use such other liquid soap-forming substance as liquid fatty acid or an admixture of fatty acid and rosin in suitable proportions. Thus, the'liquid.

When an apalkali cresylate, when the latter compound also .appears in the composition.

fatty acid may be oleic acid or such other liquid iatty acids as are derived from fish, corn, castor, or similar oils. When liquid fatty acid and rosin are combined or mixed, the proportions employed in the mixture may be such as to approximate the composition of the Tallol available as a byproduct from kraft pulp manufacture. From the standpoint of excellence .or results and low cost, however, it is preferable to employ Tallol whenever Tallol is available.

In lieu of cresylic acid, such as the ortho, meta, and para cresol, other phenols, such as carbolic acid, xylenol, alpha and beta naphthols, hydrogenated phenol (hexalin), etc. might be used as the alkali solvent or carrier in preparing compositions embodying the present invention, but 'cresylic acid is preferable because of its low cost and the eminently satisfactory results realized therewith.

I claim:--

1. A substantially anhydrous, alkaline liquid composition for degreasing and cleaning purpose, said composition being possessed of homogeneity and stability characteristics comparable to those of a true solution and comprising watersoluble soap, alkali in free, water-soluble condition and combined as phenolate, and liquid hydrocarbon grease solvent, said composition being substantially devoidof water other than that incident to the formation of said soap and ,phenolate.

2. A substantially anhydrous, alkaline liquid composition for degreasing and cleaning purpose, said composition being possessed of homogeneity and stability characteristics comparable to those of a true solution and comprising watersoluble soap, alkali in free, water-soluble condition, and liquid hydrocarbon grease solvent, said composition being substantially devoid of water other than that incident to the formation of said soap.

a 3. A substantially anhydrous, alkaline liquid composition for degreasing and cleaning purpose, said composition being possessed of homogeneity and stability characteristics comparable to those of a true solution and comprising watersoluble soap, alkali in free, water-soluble -condition, an organic alkali-solvent, and liquid hydrocarbon grease solvent, said alkali-solvent being miscible with the other ingredients of said composition and said composition being substantially devoid of water other than that incident to the formation of saidsoap.

4. A substantially anhydrous, alkaline liquid composition for degreasing and cleaning purpose, said composition being possessed of homogeneity and stability characteristics comparable to those of atrue solutionand comprising watersoluble soap, alkali in free, water-soluble condition, an alcohol solvent of said free alkali, and liquid hydrocarbon grease solvent, said composition being substantially devoid of water other than that incident to the formation of said soap.

5. A liquid composition for degreasing and cleaning purpose, said composition being of alkalinecharacter and of homogeneity and stability characteristics comparable to those of a true solution and comprising liquid potassium soap, water-soluble alkali in free condition, an organic alkali-solvent, and liquid hydrocarbon grease solvent, said alkali solvent being miscible with the other ingredients of said composition and said composition being substantially devoid of water other than that incident to the formation of said soap and being broken down from its true solution characteristics upon the addition thereto of an appreciable amount of water.

6. A liquid composition for degreasing and cleaning purpose, said composition being of alkaline character and of homogeneity and stability amazes characteristics comparable to those of a true solution and comprising liquid potassium soap, water-soluble alkali. in free condition, an alcohol solvent of said alkali, and liquid hydrocarbon grease solvent, said composition being substantially devoid of water other than that incident to the formation of said soap and being broken down from its true solution characteristics upon the addition thereto of an appreciable amount of water.

'7. A substantially anhydrous, alkaline liquid composition for degreasing and cleaning purpose, said composition being possessed of homogeneity and stability characteristics comparable to those of a true solution and comprising liquid potassium soap, water-soluble alkali in free condition and combined as cresylate, and liquid hydrocarbon grease solvent, said composition being of ready self-emulsifiability in water and being substantially devoid of water other than that incident to the formation of said soap and cresylate.

8.- A process of preparing an alkaline, substantially homogeneous and stable liquid composition for degreasing and otherwise conditioning surfaces, which comprise admixing with liquid, fatty-acid-containing, soap-forming substance a substantially anhydrous organic liquid solvent containing dissolved therein water-soluble alkali in a form combinable with said substance to form water-soluble soap and in amount in excess of that necessary for saponifying said substance; said organic liquid solvent being miscible with the other ingredients of the resulting composition; and diluting the resulting liquid composition with liquid hydrocarbon grease solvent compatible therewith.

9. A process of preparing an alkaline, substantially homogeneous and stable liquid composition for degreasing and otherwise conditioning surfaces, which comprises admixing with liq uid, fatty-acid-containing, soap-forming substance substantially anhydrous organicliquid solvent containing dissolved therein caustic potash in amount in excess of that necessary for saponifying said substance; said organic liquid solvent being miscible with the other ingredients of the resulting composition; and diluting the resulting liquid composition with liquid hydrocarbon grease solvent compatible therewith.

ALTON F. CURRAN.