US2369946A - Art of protecting metal surfaces - Google Patents

Description

Patented F eb. 20, 1945 UN'ITED STATES'PATENT orrlcs Jacob Maurice Cohen, Washington, D. C.

No Drawing. Application January 25, 1941. Serial No. 375,993

8 Claims. 106-14) This invention relates to the art of protecting surfaces of metals such as iron, aluminum, magnesium, zinc, copper and alloys thereof such as steel, brass, and the aluminum-magnesium alloys, when exposed to fresh or sea water, to the atmosphere, and to like active influences.

It has heretofore been proposed for this purpose to employ various mixtures of soaps, oils and greases, and pitches or asphalts; but such materials have not been effective and available for providing a satisfactory continuous, thin, adherent and protective coating which can be easily andsimply supplied and removed.

- A feature of the present invention, therefore, is the provision of a composition which can be so employed, and which can be utilized in several forms or conditions according to the purposes to be attained.

In order to assure proper adhesion, compounds are selected which are capable of afilxing themselves to metal surfaces, and may be characterized as polar compounds with cation properties and charges which are attracted by the metal so that the substances thus become deposited upon the exposed surface, and resist. removal by simple mechanical means. Such compounds are preferably provided in the form of a solution or suspension in a volatile solvent which permits the molecules of the polar compound to be delivered to the metal surface to establish a continuous and thin film thereon.

The composition comprises ingredients which ently preferred. Chemically .pure lanolin has surface and closely adherent thereto. Further. such a film preferably must be capable of quick and easy removal by easily available and employable means, such as a hydrocarbon lubricant which is to be active upon the cleared surface, or condensed-steam when the composition has been used to protect the steam-exposed surfaces of pipes, etc.

The basic fatty substance is present as a major ingredient of the base. It has been found that lanolin or wool fat is highly satisfactory for the purpose, and is the presently preferred material. It is desirable that this lanoliii should be free of substances which may interfere with its capabilities of adherence to'the metal surface. Commercial lanolin, being apuritled wool fat. is presbeen found utilizable but less effective, and the relatively impure wool grease has a sufficient effect for many purposes; and other animal fats such as lard, tallow, etc. may-be substituted when proper precaution is taken with respect to other ingredients including agents for preventing rancidity. These fatty substances are characterized in containing the fatty esters .ofwater-insoluble aliphatic acids such as oleic, palmltic, stearic, lanopalmic, lanoceric. etc., and having at least I substantially 16 carbon atoms in the carbon are effective conjointly to accomplish the deposition of an adherent film and to maintain this film in place and resistant to the aforesaid in' fluences. It comprises a substantially neutral fatty material of unctuous or greasy consistency, a higher aliphatic acid, and a substance competent of offsetting any tendency toward excessive effect of the acid and preferably also being effective as an inhibitor of change in the other materials and itself having polar properties. Such a composition may have added thereto an extremely fine, preferably colloidal, metallic oxide, such as cuprous oxide, a lower lead oxide, etc., as a preservative and stain for indicating that the metal surface has been properly covered. For the usual application of a thin and adherent film, the basic composition is extended by a volatile solvent so that it may be employed in a dilute condition; and such a composition is effective for permitting the deposition of the polar compounds during the course of evaporation of the solvent, with an assurance that the film will be continuous over the metal solvents, rather than a-uniform film. Butter is' excepted from the fatty substances 'utilizable as chain. It has been found that compositions ineluding tallow aremore waxy than those with lanolin, and have a marked adherence so that it is difiicult to remove the film later: while those with lard tend to form rings with hydrocarbon being a substance in which acid radicals have relatively few carbon atoms in the carbon chain, said acids commonly being classified as watersoluble. r

The higher aliphatic acid is a substantially saturated material and itself a polar compound which contains a carboxyl group capable of at-' tachment to a metal surface, with an aliphatic chain which renders it capable of blending with or effecting a Joint solution with the fatty'substance. Water-insoluble monocarboxyl acids are valuable, as being little subject to change? and preferably have a straight chain formation of, say, ten to twenty carbon atoms. Lower members tend toward water solubility: while'higher members are too stiff in desirable proportions of composition. Oleic acid is the presently preferred material, although other substances of this nature, such as stearie acid, palmitic acid. and the like may be employed as a full or partial substitute. n

In order to prevent an excessive action of the oleic acid, by which direct attack upon the metal might occur, a tertiary amine is employed, and appears to be effective without far-reaching direct esterification of the oleic acid. Triphenylamine, triethanolamine, and other aryl, alkyl, and

alkaryl tertiary amines may be used; a, solution in thiocyanate is advantageous. Quaternary amines having the properties of the specified tertiary amines are also effective.

A basic composition thus comprises lanolin or wool fat, about 75 parts by weight; finely divided cuprous oxide, about to 15 parts (preferably about 2 percent); oleic acid, about 5 percent: and a tertiary aromatic amine for neutralizing, about /2 to 5 parts (preferably about 1 percent). This basic composition is then completed by extending in a hydrocarbon solvent in the proportions by volume of about 20 percent of the base to 80 percent of mineral spirits, naphtha, or other like volatile or low boiling compound or mixture. In compounding the materials, it is preferred to dissolve the lanolin, oleic acid and tertiary amine in individual quantities of the solvent, and then to mix these mechanically while introducing the cuprous oxide. Finally, the basic composition is completed by intro- :ducing the rest of the solvent.

I This composition is capable of direct employment, particularly upon warming of composition and article for securing an economically thin coating; but preferably is further modified to obtain certain valuable characteristics which adapt the material to specific purposes.

- Example I A composition, which may be used for the cleaning of metal and metal surfaces and for the .lubrication and continued protection of such sur- Iaces by the deposit of a thin film of preservative Y and lubricating nature, is prepared by taking substantially 30 parts of the above diluted basic composition, with 3 parts of a lubricating oil such asSAE 30 toSAE 0, and 66% parts of a volatile chlorinated hydrocarbon such as carbon tetrachloride, trichlorethylene, or the types employed in refrigerating machines. These ingredients are stirred until a uniform mixture results. l This composition is particularly useful in cleaning dust, grease, cosmoline, etc., from machine tools, printing machinery, boilers, engines, turbines, ypewriters, precision instruments, addmachines, etc. It is effective not only for removing the accumulation of hardened grease,

oil and dust, but leaves a thin coating of fiuid nature which provides lubrication. It is effective, for example, to prevent corrosion of metal after contact of metal by sweating hands.

For-use on typewriters and like machines, one and. two thirds percent of oil is preferred: for use inside steam or internal combustion engines five percent are desirable. One and a half percent is a desirable economic minimum to maintain.

' It may be applied by spraying under high pressure of 100 to 150 pounds per square inch, or even by spraying at low pressures with a hand spray: and can be employed directly by a brush, by --d1pp1n8. by. a rag, or by flushing, i. e., by filling the article therewith and then emptying.

'. The film is non-drying, and provides a sub stantial protection against corrosion. If desired, it may be removed by common solvents such as kerosene, gasoline, carbon tetrachloride, etc. The film is a few ten-thousandths of an inch thick and is transparent, so that the condition of the surface may be observed. It is non-abrasive, non-drying, non-inflammable under ordinary conditions, and is harmless in contact with the skin.

Example 11 A composition which is effective upon metal surfaces which have been wet with water, to displace this water and provide a. protective film, may be made by mixing substantially 95.6 parts of the diluted basic composition above with 4.4 parts of a wetting agent. This wetting agent should be soluble in the hydrocarbon solvents, and also in water. Various commercial agents of this type may be employed, such as dioctylsodium-sulfosuccinate (commercially available as Aerosol OT).

This composition may be employed by spraying or by direct dipping, brushing, etc. After evaporation of the solvent, a thin adherent film is left. When employed upon metal which has been wetted, as by immersion of machinery or instruments in salt wate, the surfaces may be directly treated with this composition, without prior removal of all the water and adherent moisture. It appears least active on metal in the presence of distilled water, but its activity increases as the concentration of electrolyte in the water increases. It operates to penetrate and displace the water from the metal surfaces and forms its protective coating directly upon the metal. i

It can be removed by the presence of an excess of water, particularly if hot, and hence it is useful in rust-proofing the waterside of boiler tubes,

the steam or waterside of engines, pumps, etc., when ships are decommissioned: in such cases, no problem of removal is involved, as the film immediately forms an emulsion in the presence of an excess of water or the condensed steam, and is immediately ejected. Further, it blends with normal lubricants, so that the engine, etc., of the decommissioned ship can be immediately started after the 'same oiling as would be employed upon cleaned surfaces. However, it can be cleaned away, if so desired, by use of the standard solvents of lanolin.

I The film deposited by this composition is usually somewhat thicker than the film deposited by the composition of Example I, but is less than a half-thousandth in thickness, non-drying.

transparent, non-abrasive, and harmless in contact with the hands.

Example III A composition for permanent protection of metal which may be exposed to severe weather conditions can be prepared by mixing 72.4 parts of the diluted basic composition above, 21.4 parts of non-acid bituminous base material (preferably polar) which may contain about 4 percentof a leaded compound, and 6.2 parts of a hard wax. The bituminous base material may be selected from the asphaltic or tar distillates having a high boiling point and of non-acid character such as Alox commercial oxidired petroleum fractions, usually being a complex mixture of organic esters, alcohols, lactones, and ketones of high molecular weights; being about 8200,sp.gr., 40-43 B., viscosity 48-58 seconds (Baybolt) at 210, inp. 104-107 F" flash 350-370 aacacse acid number 0.0-5.0, iodine number 20.

R, (maximum): neutral or slightly-alkaline roofin asphalts are effective. The hard-wax is preferably a hard petrolatum wax, such as Petrowax, but neutral waxes such as carnauba. montan, petrolatum, etc., waxes, may be employed to give the desired body so that dirt particles will not cut through easily.

This composition has a much darker color than those of the above examples, and deposits a film less than a thousandth of an inch thick, with a sufficient transparency to permit inspection of the conditions on the metal surfaces. It can be employed upon machinery of all kinds, gives excellent surfaces on machinery which is used or stored outdoors, and protects even against frequent handling or abrasion of machinery indoors I or outdoors. The film is heavier than those of the compositions above, and normally this composition is not recommended for employment on sensitive instruments, where' the thickness or weight characteristics may be of importance.

The composition may be employed by dipping, spraying or brushing, but should be employed upon a clean metal surface from which all foreign matter has been removed. For example, the compositions of the above examples may be used to clean the surface and expel moisture, and then the present composition may be employed directly over the film deposited thereby.

The film is sumciently transparent, non-abra' sive, harmless in contact with the skin, soluble in any of the aforesaid common solvents and in lubricating oils, and is capable of providing protection for at least two years for metal surfaces exposed to outside conditions, provided that the film is not removed by a solvent or by abrasion during the time.

Example IV A composition similar to that of Example 111, but providing a thinner film not so resistant to abrasion by wind or water, may be prepared by mixing 65 parts of the diluted basic composition above, and 35 parts of petrolatum.

This composition deposits a film which is capable of preserving metal of all kinds against corrosion during storage or use indoors, and may be employed on machine tools, hand tools, fine instruments, engines, turbines, dies and fixtures, metal sheets, tinplate, etc. The composition may be applied by dipping, spraying or brushing, and should be applied over a clean metal surface: the surface may be cleaned by the use of the compositions of Examples 1 and II above, and then the present composition applied directly thereover. The film may be removed, if desired, by use of the common solvents or lubricating oil.

The deposited film is sufllciently transparent. non-abrasive, harmlessto the skin, and may be easily removed when so desired. On metal surwith lubricant, water, etc., in contact with the mospherlc influences.

protected surfaces which thereby are cleared of the protecting compound, so that the clean metal is shortly provided for contact with any sliding parts, etc or the waterside of boiler tubes may be quickly cleared of the material for efflcient heat transfer.

With each composition, the coating is very thin, beingof the order of less t an a thousandth of an inch, and is stable a inst any normal at- The films are extremely tenacious, and correspondingly resistant to the. penetration of any reagent which is not a solvent thereof.

,It is obvious that the invention is not limited to specific examples of practice as stated, but that compositions may be made and employed in various ways, within the scope of the appended claims.

I claim:

1. A liquid composition for depositing a protective film upon metals, comprising a base and a faces which are stored indoors, the film has a pro- Examples 111 and IV, it is preferred toemploy the compositions of Examples 1 and II, for

" preliminary cleaning operations. With any of these compositions, the metal is the mechanism may be immediately returned to service by operating it under normal conditions volatile solvent therefor; said base having as the major ingredient thereof parts by weight of a substantially neutral semi-solid polar fatty compound of unctuous consistency and of cation properties and having the acid portion of the molecules thereof essentially consisting of a water-insoluble aliphatic acid with at least sub-, stantially 16 carbon atoms in the carbon chain, and also including about 5 parts of a waterinsoluble higher aliphatic acid with 10 to 20 car-- bon atoms in the aliphatic chain whereby the said higher acid is compatible with the animal fat, and to 5 parts of a tertiary amine present in an amount for preventing far-reaching direct esterification of the said higher-acid.

2. A liquid composition for depositing a protective film upon metals, comprising a base and a volatile solvent therefor; said base having as the major ingredient thereof 75 parts by weight of a substantially neutral semi-solid polar animal fat of cation properties and having the acid portions of the molecules thereof essentially consisting of a water-insoluble aliphatic acid with at least substantially 16 carbon atoms in the carbon chain,

,and also including about 6 parts of a water-insoluble higher aliphatic acid with 10 to 20 carbon atoms in the ,aliphatic chain whereby the said Qhigher acid is'compatible with the animal fat, and /2 to 5 parts of a tertiary amine present in an amount for preventing direct attack by the said higher acid upon the metal and for preventing far-reaching direct esteriflcation of the said higher acid.

3. A liquid composition for depositing a protective film upon metals. comprising a base and a volatile solvent therefor; said base having as the major ingredient thereof .75 parts by weight of lanolin, and also including about 5 parts 'of a weter-insoluble higher aliphatic acid with 10 M30 carbon atoms in the aliphatic chain whereby the acid is compatible with the animal fat, and V to 5 parts of a tertiary amine present in an amount for preventing direct attack by the acid upon the metal and for preventing far-rechinlg direct'esterification of the acid.

protected: but

4. A liquid composition for depositing a protective film upon metals, comprising a base and a volatile solvent therefor; said base having as the major ingredient thereof 75 parts by weight of lanolin, and also including about 5 parts of a water-insoluble higher aliphatic acid with 10 to 20 carbon atoms in the aliphatic chain wherewater-insoluble higher aliphatic acid with 10 to I 20 carbon atoms in-the aliphatic chain whereby the acid is compatible with the animal fat, and to parts of a tertiary amine present in an amount for preventing direct attack by the acid upon the metal and for preventing far-reaching direct esteriflcation of the acid, said solvent being present in a proportion of approximately 4:1 relative to the base. and also including petrolatum in a proportion of approximately onethird of the composition.

6. A liquid composition for depositing a protective'i'ilm upon metals, comprising a base and a volatile solvent therefor; said base having as the major v ingredient thereof 75 parts by weight of lanolin, and also including about 5 parts of a water-insoluble higher aliphatic acid with to 20 carbon atoms in. the aliphatic chain whereby the acid is compatible with the animal fat, and

/2 to 5 parts of a. tertiary amine present in an amount for preventing direct attack by the acid upon the metal and for preventing far-reaching direct esterification of the acid, and also including anon-acid bituminous base in the approximate proportion of /5 of the composition, and also containing a hard wax in the proportion of from 1 to 10 percent of the composition.

7. A liquid composition for depositing a protective film upon metals, comprising a base and a volatile solvent therefor; said base having as the major ingredient thereof 75 parts by weight of lanolin, and also including about 6 parts of a water-insoluble higher aliphatic acid with 10 to carbon atoms in the aliphatic chain whereby the acid is compatible with the animal fat, and 1 to 5 parts of a tertiary amine present in an am unt for preventing direct attack by the acid upon the metal and for preventing far-reaching direct esteriiication of the acid, and 1 to 8 percent of a wetting agent soluble in water and in said solvent. 8.;A liquid composition for depositing a protective film upon metals, comprising a base and a volatile solvent therefor; said base having as the major ingredient thereof 75 parts by weight of lanolin, and also including about 5 parts of a water insoluble higher aliphatic acid with 10 to 20 carbon atoms in the aliphatic chain whereby the acid is compatible with the animal fat, and to 5 parts of a tertiary amine present in an amount for preventing direct attack by the acid upon the metal and for preventing far-reaching direct esteriiicatlon of the acid, said solvent com prising light mineral spirits and a chlorinated light hydrocarbon, and also containing a' few percent of a lubricating oil.

JACOB MAURICE COHEN.