US3565678A - Method of protecting the finish of metal against oxidative deterioration - Google Patents

Abstract

OPTICALLY TRANSPARENT UNIFIED EMULSIONS OF WATER AND OIL ARE DISCLOSED. THESE EMULSIONS, WHEN INCORPORATED WITH APPROPRIATE CORROSION INHIBITORS AND APPLIED TO METALLIC SURFACES, PROVIDE STORAGE PROTECTION FOR THE METAL AGAINST EXTREMELY HIGH HUMIDITY LEVELS AND EXTREME CYCLES OF TEMPERATURE AND HUMIDITY.

Description

3,565,678 METHOD OF PROTECTING THE FINISH F METAL AGAINST OXIDATIVE DETERIORATION Keith L. Johnson, Matteson, and Harry T. Anderson, Clarendon Hills, Ill., assignors to Swift & Company, Chicago, Ill., a corporation of Delaware N0 Drawing. Filed Apr. 26, 1968, Ser. No. 724,613 Int. Cl. BOlf 17/22; C23f 11/00 US. Cl. 117-134 6 Claims ABSTRACT OF THE DISCLOSURE Optically transparent unified emulsions of water and oil are disclosed. These emulsions, when incorporated with appropriate corrosion inhibitors and applied to metallic surfaces, provide storage protection for the metal against extremely high humidity levels and extreme cycles of temperature and humidity.

This invention is directed to compositions useful in the treatment of metal surfaces. More particularly, the invention relates to the protection of ferrous metals during storage. In addition, the invention concerns a method of protecting the finish of metal strip, sheet or plate, including coated or plated metal, against scratching and oxidative deterioration which comprises applying emulsified oil compositions to the surface of metal and forming a film of oil thereon.

Generally speaking, stainless steel is that steel which contains an element such as nickel and/ or chromium and does not readily tarnish on exposure to the atmosphere. However, the major production of steel strip or steel sheet is of the mild or non-stainless variety and the rusting and/ or corrosion of the non-stainless steels during storage in the mills and warehouses is a considerable problem. This oxidative deterioration has been partially alleviated by controlling the humidity and chemical content of the air coming in contact with the stored product. In addition to controlling the environment, mineral oil and mineral oil solutions containing various corrosion inhibitors have been utilized for the prevention of oxidation during storage.

However, complete and accurate control of the environment is not only expensive, but is impractical as well. Further, in regard to the oil layer present on the metallic surface, it must not interfere with any subsequent coating application such as plating, lacquering or lithograp-hing. In those cases where the oils used do interfere in additional processing steps, it is required that the oil be substantially removed at some time prior to further processing the metal. This removal of the oil film is dlifiCllit and generally requires scrubbing with alkaline cleaning agents or vapor phase degreasing.

In addition to difiiculties in removing the oil, mineral oil (and other oils) treatments are not wholly satisfactory from a performance standpoint in eliminating oxidation and other corrosion inasmuch as the oil frequently pinholes when exposed to high atmospheric moisture levels resulting in a product having localized rusting or corrosion. By pinholing is meant the fact that there is incomplete coverage of the metal surface or coverage of such a thin nature at various spots on the metal that the surface is exposed to the atmosphere.

Therefore, it can be readily seen that a method for protecting ferrous metals without incurring operational and economic difficulties heretofore experienced would be highly desirable in the art.

tates Patent Ofi ice 3,565,678 Patented Feb. 23, 1971 It is therefore an object of this invention to provide a means for preventing substantial oxidation deterioratron to metal surfaces.

Another object of the invention is to provide a novel composltion which when coated upon ferrous surfaces will protect them against extremely high humidity levels and extreme cycles of temperature and humidity.

Still another object of the invention is to provide a composition capable of protecting ferrous surfaces, yet is capable of being readily removed by contact with water.

Another object of the invention is the formation of an emulsifying agent which is capable of producing optically transparent unified emulsions.

Additional objects, if not specifically set forth herein, will be readily apparent to those skilled in the art from the detailed description of the invention which follows.

In general, it has been found that an optically transparent unified emulsion of water and oil can be prepared which, when incorporated with appropriate corrosion inhibitors and applied to metallic surfaces, will provide storage protection against extremely high humidity levels and extreme cycles of temperature and humidity. It is believed that the moisture content of this emulsion varies in such a manner so as to attain an equilibrium with the relative humidity of the atmosphere. This breathing of the film explains the lack of pinholing even when relatively great extremes of temperature and humidity are experienced by the metal in storage. A further advantage of the emulsions of this invention is that the materials are readily removable by the application of water; requiring no alkaline cleaning or vapor phase degreasing prior to most uses.

More specifically, the novel emulsifying agent of this invention comprises a ternary mixture of a condensation product of an alkylolamine having at least one acylata-ble hydrogen atom in the amino group and a fatty acylating substance having between about 12 and about 20 carbons in the fatty acyl group, a polyoxyethylene derivative wherein the polyoxyethylene portion has a molecular weight of between about 300 and about 2,000, and an ether of a low molecular weight alkylene glycol. The condensation product contains a predominant amount of amide which acts as the oil-solubilizing agent in the unified emulsion. The polyoxyethylene derivative, among other things, imparts a tolerance for water to the amide while the glycol gives increased tolerance for water and further acts as a viscosity stabilizer.

The ternary emulsifying agent has the ability to emulsify 20:80 to :20 mixtures of water and oil and has the further property of being effective when used in amounts such that the total weight of the oil and water exceeds the total weight of the emulsifier. Generally speaking, if an emulsified system is not transparent, it indicates that at least two phases are present which will eventually separate. In order to produce the unified emulsions (optically transparent) it has been required in the past that the emulsifying agent comprise at least 50%, by weight, of the emulsified system in order to prevent phase separation. Therefore, it was quite unexpected to find that the ternary emulsifier of this invention can be used in amounts as little as 20%, by weight, of the total emulsified system. Of course, larger amounts are effective and, generally, the amount of the emulsifying agent will range between about 20% and 50%, preferably between about 30% and 40%, by weight, of the total emulsified system.

More in detail as to the description of the various components, the condensation product may be further defined as comprising essentially fatty acid amides of the alkylolamine combined with a non-performance-affecting amount of fatty acid monoester of the alkylolamine as well as small amounts of free amine and glycerine if the acylating agent utilized is a glyceride. While it is not a preferred component of the system, the percentage of the ester, based on the weight of the condensate, can vary from about 10% to about 40% without substantially affecting the emulsifying performance. In general, the condensate when first formed will have an amidezester ratio of about 7:3, but after aging will end up with a low ester content. This low ester content of the condensate can be defined as less than about 10% based on the weight of the condensate.

In producing the amide, the acylating agent and alkylolamine, in ratios varying between about 1:2 to 2:1 are heated to a temperature of between about 140 C. and 200 C. for 1 /2 to 6 hours. In the working example set forth below, diethanolamine or diisopropanolarnine will be set forth. However, monoalkylanolamines such as monoethanolamine, or monopropanolamine may be used either alone or in mixtures with diethanolamine or diisopropanolamine to form the condensate. The alkylolamines useful in this invention contain about 1 to 4 carbons per alkyl radical and can be mixed alkylolamines such as ethyl isopropanolamine or mixtures of different alkylolamines. The acylating substance is preferably a monocarboxylic acid or derivative thereof having an average of about 12 to 22 carbon atoms in each acyl chain. By acylating substance, it is meant any substance which is capable of the formation or introduction of an acyl radical in or into the alkylolamine and includes carboxylic acids, carboxylic acid halides, carboxylic acid esters, and anhydrides. In regard to the esters, the term is meant to cover both esters of monohydric alcohols and esters of polyhydric alcohols such as the glycerol esters.

In forming the polyoxyethylene derivative, polyethylene glycol may be formed by the polymerization of ethylene oxide with ethylene glycol, and this followed by the acylating agent will produce the polyoxyethylene derivative. The polymer may be blocked at one end with a lower alkoxy group such as methoxy, ethoxy, propoxy or butoxy, etc. Of special importance are the polyethylene glycols having a molecular weight varying between about 200 and 2,000. Molecular weights of the preferred polyoxyethylenes will vary between 300 and 1000. An alternative route in making the polyoxyethylene derivatives is the ethoxylation of an active hydrogen compound such as a fatty alcohol, fatty acid, alkyl mercaptan or alkyl phenols. The ethoxylated material may be represented as follows:

wherein R is H, methyl, ethyl, propyl or butyl; R is a saturated or unsaturated fatty alkyl group of between about 12 and 30 carbons, or an alkyl phenol having 1 to 3 alkyl groups containing 2 to 12 carbons per group; and x will vary between about 8 and about 60. Particular fatty acids which may be ethoxylated include lauric, myristic, palmitic, stearic, arachidic, behenic, oleic, elucic, and linoleic acid, etc. A representative group of usable alohols comprises the mercaptans, such as dodecyl mercaptan, octadecyl mercaptan, eicosyl mercaptan, docosyl mercaptan, octacosyl mercaptan, triacontyl mercaptan, etc., and the corresponding oxo alcohols. The alkyl phenols which may 4 less than 8 carbons and preferably 4 or less, such as methyl, ethyl, propyl and butyl. The aryl portion of the ether may be described as phenol or substituted phenol containing 0 to 3 alkyl groups of l to 2 carbons per each alkyl group.

The ternary emusifying agent comprises about 20% to 50% of the condensation product containing a predominant amount of amides, about 40% to of the polyoxyethylene derivative and about 5% to 40% of the lower alkyl or aryl glycol ether. The condensate and polyoxyethylene derivative components may, if the fatty portion is to be the same, be prepared by esterification of essentially all the fatty acid in the composition followed by aminolysis of a portion of the fatty ester by an alkylolamine. This method, although generally preferred, is in no way limiting to the invention.

To form the unified, optically transparent emulsions of this invention, a mixture of water and hydrocarbon oil in the ratio of about 20:80 to 80:20 is combined, by means of agitation, with the ternary emulsifying agent in amount such that the emulsifying agent comprises about 20% to about 50%, by weight, of the total emulsified system. The hydrocarbon medium generally comprises refined mineral oil or fractions thereof. Refining may be by percolation, sulfuric acid treatment, extraction with selective solvents, propane precipitation, etc. Examples include petroleum naphtha cuts, mineral spirits, mineral seal oil, kerosene, gas oils, pertoleum ether; aromatic hydrocarbons such as benzene, o-xylene, m-xylene, p-xylene, butylbenzene, cumene; parafilnic hydrocarbons, e.g., hexane, dimethylpentane, octane, nonane, undecane, dodecane, and cycloparaffins.

Corrosion and rust inhibitors in amounts of 0% to- 2%, by weight of the unified emulsion, which may be utilized are represented by inorganic materials, amines, chelating agents, sequestering agents, and combinations thereof. Examples includes sodium meta silicate, diethanolamine, triethanolamine, higher fatty amines, sodium gluconate, sodium glucoheptonate, tetra sodium salt of ethylenediaminetetraacetic acid, diethanolammoniumethylorthophosphate, diethylammoniumlaurylphosphate, dimethanolarnine and diethanolamine saturated with chromic sulphate, etc.

The unified emulsions of this invention can be applied to the metal surface by spraying, dipping, brushing, swabbing trowelling, etc. The thickness of the oil-water film is not critical so long as a continuous film is deposited over the metal surface. Since the moisture content of the emulsion can vary between about 20:80 to 80:20, water to oil, the moisture content of the film can also vary depending upon the relative humidity of the atmosphere. For example, when the unified emulsion has a ratio of water to oil of 20:80, a considerable amount of moisture can be absorbed by the film without film failure. This breathing by the film explains the lack of pinholing even when relatively great extremes of temperature and humidity are experienced by the metal in storage.

In addition, the films of the unified emulsions are readily removable by the application of large amounts of water, i.e., flushing prior to most uses. In this connection, it is pointed out that no alkaline cleaning or vapor phase degreasing need be carried out in order to strip the film from'the metal surface.

The following examples are set forth merely to illustrate the invention and are not to be taken as any limitation of the invention which is set forth in the claims appended hereto:

EXAMPLE I Six hundred grams of polyethylene glycol having a molecular weight of about 600 was reacted with 400 grams of tall oil fatty acids in the presence of 2%. grams of toluene sulfonic acid under vacuum at a temperature of about 142 C. After a six-hour period, the unesterified fatty acid was determined by titration in alcohol to a thymolphthalein, end point to be 4.62%. Fifty-seven grams of di(2-hydroxyethyl)amine was added and the reaction mixture maintained at a temperature of 149 C. for an additional two hours. To this reaction product was added 300 grams of ethylene glycol monophenyl ether and 1,500 grams each of water and light lubricating oil. In addition, 25 grams of N(2-aminoethyl) piperazine was added as a corrosion inhibitor. A strip of steel sheet was coated with a thin layer of the unified emulsion, and it was observed that the film possessed excellent corrosion and rust inhibition in 100% humidity atmospheres and oscillating temperatures.

EXAMPLE II Three hundred grams of a commercial ethoxylated nonyl phenol having the nonyl group in the para position and being ethoxylated to 67.5% ethylene oxide was blended with 150 grams of a condensate of 75 parts of red oil with 25 parts of diethylolamine. One hundred fifty grams of butyl Cellosolve was blended in, followed by 500 grams of mineral seal oil and 500 grams of water. Ten grams of aqueous sodium silicate was added to the above as a corrosion inhibitor and the resulting unified emulsion coated on various strips of steel. The strips were placed in a humidity cabinet wherein the temperature varied from 70 F. to 150 F. and the humidity ranged from 30% humidity to 100% humidity over a period of several days. The unified emulsion showed excellent rust inhibition qualities.

EXAMPLE III Two hundred parts of dodecyl mercaptan ethoxylated to a level of about 60%, by weight, was blended with 130 parts of olive oil which had been heated in the presence of diisopropanolamine on a 2:1 weight basis for a fivehour period at 150 C. One hundred parts of diethylene glycol monopropyl ether, 270 parts of water and 270 parts of kerosene were then blended along with .5 sodium glucoheptonate as inhibitor, and the resulting unified emulsion was coated upon steel strips. Over various temperatures and humidity ranges, the film did not fail and the product remained uncorroded.

EXAMPLE IV Three hundred grams of the methyl esters of corn oil fatty acids was reacted with 450 grams of methoxypolyethylene glycol having a molecular weight of about 550 in the presence of 0.40% sodium methylate at a temperature of about 135 C. under vacuum. Two and one-half hours later, 43 grams of diethylolamine was added fol lowed by an additional two hours heating at roughly 135- 140 C. Seven hundred grams of a light-duty lubricating oil and 700 grams of water were added and the resulting material afiorded excellent corrosion and rust protection, especially when the steel sheets were stacked one on top of the other.

Obviously many modifications and variations of the invention as hereinbefore set forth may be made without departing grom the spirit and scope thereof, and, therefore, only such limitations should be imposed as are indicated in the appended claims.

We claim:

1. The method of protecting the finish of metal against oxidative deterioration which comprises applying to said metal a continuous, breathable film of a unified water and oil emulsion, said emulsion containing water and oil in a ratio of about 20:80 to 80:20 and combined with an emulsifying agent in an amount of about 20% to about 50%, by weight, based on the total emulsified system, said emulsifying agent comprising about 20% to about 50%, by weight, of a condensation product of a fatty acylating substance having an average of about 12 to about 22 carbons in the acyl group and an alkylolamine having at least one acylatable hydrogen atom in the amino group, about 40% to about by weight, of a polyoxyethylene derivative represented by one of the following formulas:

methyl, ethyl, propyl or butyl, R is a saturated or unsaturated fatty alkyl group having between about 12 and 30 carbons or an alkyl phenol having 13 alkyl groups containing about 3 to 12 carbons per group, and about 5% to about 40% of a lower alkyl or aryl ether of a glycol selected from the group consisting of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol and dipropylene glycol.

2. The method of claim 1 wherein the emulsion is sprayed upon the metal.

3. The method of claim 1 wherein the metal is nonstainless steel.

4. The method of claim 1 wherein the polyoxyethylene derivative is unsaturated fatty alkyl group having between about 12 and 30 carbons or an alkyl phenol having 1-3 alkyl groups containing about 3 to 12 carbons per group.

5. Method of claim 1 wherein the emulsion contains a corrosion inhibitor in an amount between 0 and 2% by weight of the unified emulsion.

6. The method of claim 5 wherein the corrosion inhibitor is a member selected from the group consisting of sodium meta silicate, diethanolamine, triethanolamine, higher fatty amines, sodium gluconate, sodium glucoheptonate, tetra sodium salt of ethylenediaminetetraacetic acid, diethanolammoniumethylorthophosphate, diethylammoniumlaurylphosphate, dimethanolamine and diethanolamine saturated with chromic sulphate.

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