US2717843A - Sheet for protection of metals from corrosion and method of making - Google Patents

Description

SHEET FOR PROTEQTIDN 0F METALS FROM CORROSION AND METHOD OF MAKING Aaron Wachter, Oakland, and Nathan Stillman, El Cerrito, Califi, assignors to Shell Development Company, Emeryvilie, Califi, a corporation of Delaware No Drawing. Application July 7, 1952, Serial No. 297,562

17 Claims. (Cl. 117156) The present invention relates to novel vapor phase corrosio'n inhibiting compositions and products thereof. tMore particularly, it relates to articles comprising a substantially solid material which contains, or is impregcorrodible metals in moist air. The materials impregnated with these mixtures may be of the kind suitable for packaging, inserting in a package, or for enclosing metals.

During storage, handling, jects comprising or consisting of a corrodible metal exoften necessary to prevent their corrosion. Heretofore, various methods used for this purpose have been unsatiscumbersomeness, necessity of using an excessive amount of labor and time.

Partially or completely enclosed metal housed, packaged, boxed, enveloped,

It is an object of this invention to obviate the above and other defects, and to provide novel compositions and/or products and articles, which materials may be used as the enclosing or packaging means per se, or be which materials are capable of intially solid materials containing, coated upon, impregnated therein or otherwise physically incorporated there- By the latter is meant a salt of an organic base and a phosphoric acid wherein at least approximately two of the acid (hydroxyl) radicals of the latter have been combined with at least two molecules of the same or different organic bases. The term ionic means capable of ionizing in a conventional ionizing medium, such as an} aqueous medium.

It has further been discovered that said corrosioninhibition is etfected by one or more of the present mixtures in proximity to the metal to be protected, which mixture comprises essentially an ionic organic nitrogenbase phosphate salt and an ionic metal nitrite contained or impregnated within a substantially solid organic material. It is believed that the vapors which arise from one or more of the present mixtures are a result of ion interchange between the at least two essential component base-phosphate salt mixed with a metal 2,717,843 Patented Sept. 13, 1955 salts of the mixture, and that these vapors are composed essentially of a volatile organic base nitrite.

It was further discovered that said corrosion-inhibition fibrous materials impregnated with first: an amine phossecondary amine phosphate, and second: a water-soluble ionic metal nitrite. More particularly,

nitrite and magnesium nitrite.

The term present mixtures or the term mixtures of salts as used herein mean mixtures of a metal nitrite salt and a water-soluble organic base salt of an acid other than nitrous acid. Preferably, a present mixture comprises essentially a water-soluble organic nitrite.

In general, the organic phosphate salt and the metal nitrite may be introduced into the substantially solid organic material by solutions, suspensions, dispersions, or emulsions in any media so long as sufficient water is about 9. The organic material acts as a carrier of the present corrosion-inhibiting composition and may also act as a means of enclosure for a metal.

of said mixture.

With reference to the above-described media for the present corrosion-inhibitors, these media are also substantially non-reactive chemically with the inhibitors under the conditions of impregnation, etc. If some slight tained from the present invention.

In general, the present compositions of an organic phosphate salt and a metal nitrite salt function in any pH of 6 to a pH of about 9. By an atmosphere is meant a gas (commonly moist air), a liquid, a gel, a semi-solid, a grease, or an at least partially permeable solid, or a mixture of any one or all of these, so long as the atmosphere permits the volatile organic base nitrites (formed from the present compositions) to diifuse or be transferred by other natural forces to the surface of the metal.

In general, the organic phosphate and the metal nitrite can be introduced or impregnated into a suitable carrier, preferably an organic material, either approximately simultaneously or in a stepwise fashion, one after the other. Either the phosphate or the nitrite may be introduced first, the order of introduction not being material in the invention so long as both the phosphate and the nitrite are retained in suflicient quantities in the material impregnated. Insofar as manner of impregnation is concerned, any practicable manner known heretofore to those skilled in the art of impregnation, may be used. One may impregnate the organic material or any substantially neutral material retentive of the organic phosphates, by simply immersing or soaking the material in, impressing or spraying upon it first a simple water solution of the organic phosphates(s) followed by a similar or like manner of introducing the nitrite(s) into the organic material. This is a preferred order of impregnation in that usually the organic material retains the organic phosphate better from an initial aqueous impregnation and then reacts better with the metal nitrite when it is impregnated, then precipitating the relatively water-insoluble organic base nitrite salt into the organic material.

For purposes of impregnation, the organic base phosphate salt and the metal nitrite salt generally cannot be mixed in the same water solution prior to impregnation because the low solubility of the organic base nitrite salt causes it to precipitate out, thereby tending to prevent impregnation of a suificient concentration of the nitrite in the solid organic material. Also, if both the phosphate salt and the nitrite salt are mixed in the same water solution, an important advantage is lost in that the precipitation of the organic nitrite salt does not take place intimately and in finely divided incipient form within the interstices and upon the fibers of the organic material. As a result, a strong attachment of the precipitate thereto does not occur in such a case. However, where a simple water solution is not used and the aqueous solvent is modified by having a sufiicient uantity of an organic solvent therein for keeping any potential precipitate of organic base nitrite salt in solution, then the organic base phosphate and metal nitrite may be mixed in such a liquid organic solvent-Water blend, and the resultant solution applied in a single step to the organic material. In this modified mode of impregnation, however, precipitation or fixing of the organic base nitrite salt in the organic material will not take place so long as the specified organic solvent-water blend is present. Therefore, in this case simple immersion of the organic material (e. g., paper, a synthetic textile fabric, or cloth) in the aqueous organic solvent will not be sufficient unless the concentrations of the organic base phosphate salt and the metal nitrite are higher than that used in the water impregnation or high enough that evaporation of the solvent from the immersed material leaves at least a minimum concentration therein of active ingredients. Minimum concentrations are later specified below. Suitable solvents for the organic base phosphate salts, besides water, include methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, as well as mixtures of these alcohols with water, benzene-alcohol-water mixture, etc. The water-soluble metal nitrites are also soluble in the lower alcohols, particularly when admixed with a relatively small ratio of water.

In using the latter modified impregnation procedure, it is often desirable to wet or soak a sheet of the organic material in a solution of the mixed organic prosphate salt and the metal nitrite, withdraw the wet sheet, and then dry it by any suitable means, such as a conventional steam-heated drying press.

A particularly advantageous modified form of the compositions of the present invention is obtained by coating the present mixtures of the salts as suspensions or pastes which contain a suitable binder, onto the solid organic material carrier, e. g., paper. In forming the resultant compositions, a surface-active agent or a colloid may be employed advantageously with the suspension to stabilize it and impart improved wetting and adhering qualities to the suspension so that it is bound more effectively to the organic material carrier. The binder is used in adapted amounts suitable for a given finished coated paper, for example. Suitable binders, which bind the present mixtures of salts to the preferred fibrous materials (or other carriers), are glues, casein glues, mucilaginous materials, natural or synthetic adhesives, gums, and water-soluble or colloidally dispersible resins including these conventionally employed in the papermaking and textile fabric-manufacturing industries. Starch, dextrin, and/or shellac may also be employed. It is not always essential that appreciable ionic interchange occurs between the salts of the present mixtures at the time of coating or impregnation so long as a later introduction of moisture gives suificient interchange (yield of volatile organic base nitrite) to meet the corrosioninhibiting purpose at hand.

The vapor phase inhibiting organic base nitrite salt liberated by interaction in the present mixtures should have preferably at least a vapor pressure of approximately 0.00002 mm. Hg at 21 C. Better results are obtainable from such a liberated organic base nitrite having a vapor pressure greater than about 0.0001 mm. Hg at 21 C. while a more rapid inhibition of corrosion is obtainable with such a liberated organic nitrite salt having a vapor pressure greater than about 0.001 mm. Hg at 21 C. The compositions described herein provide a highly satisfactory means for maintaining a corrosion-inhibiting atmosphere of organic base nitrite salt vapors in contact with a metal in the proximity of the compositions.

The compositions and articles of the present invention may be realized and/ or utilized in a number of ways which may ditfer in detail but not in the essentialities of the invention. Thus, these compositions may be prepared by impregnating or coating any sheet, film, fabric, or other inert solid material with the present mixtures. Preferably the solid material chosen for impregnation has at least a fibrous structure so as to allow for absorption and adsorption of the present mixture of salts between and upon the individual fibers of the carrier material. Where a carrier material is not particularly absorbent, it may advantageously be coated with one of the present mixtures of salts.

It was found particularly effective to impregnate the present mixture of salts into a kraft paper or other strong papers, the composition as a whole being also impregnated, if necessary, with a sufiicient amount of basicreacting material, preferably an organic amine or other organic nitrogenous base, to render the composition with a pH value of at least approximately 6.

Representative examples of inert solid materials which are suitable for forming the present compositions with the present mixturees of salts, include: paper; textile fabrics, e. g., of cotton, wool, silk; wood; modified or stiffened papers such as card-board, fiber-board, and laminated papers; synthetic fabrics or fibers such as rayons, polyamides, nylons, polyvinylbutyral, polyethylene; asbestos, charcoal, alumina gel, silica gel, metal foils, etc.

In many cases it is advantageous to treat or impregnate one or more paper laminates with the mixture of organo base phosphate salt and water-soluble metal nitrite. Those laminates are then fabricated into a finished laminated product or article. The impregnated paper laminates may be used as corrosion-inhibiting means for the interior of a package, or may be placed close to a corrodible metal to protect it. In such cases, the outer laminate may be metal foil, such as tin or aluminum foil, preferably of sufiicient thickness so as to contain no pinholes. Results similar to those with the above laminates have also been obtained by impregnating paper with the mixture of an organo base phosphate salt and a metal nitrite and having one side of the paper coated with a film of wax. With this prepared paper, it is possible to ect with one layer of this paper, and corrosion. An intimately ground mixmixtures of salts may be dispersed in wax and impregnated into paper. An aqueous wax emulsion may be used for this purpose and the water mechanically pressed out of the impregnated paper. Other well-known coating materials may be used in place of Wax for dispersion or incorporation of the present mixtures whether before or after disposal of the coating material upon suitable solid materials. Among these, reference may be made to polyethylene, blends of polyethylene with waxes, polyalkylene resins, alkyd resins (e. g., of phthalic anhydride and glycerol), ethyl cellulose, polyamide resins, etc.

Although any ionic salt of an organic base and a nonmtrite anion may be employed as one of the essential and wherein each R may be the hydrogen atom or a suitable organic radical such as alkyl, aryl, phenyl, aralkyl, alkaryl, alkenyl, alicyclic and/or heterocyclic radicals.

ong the many acidic phosphate or nuclei-contain ng compounds which may thus be employed to form the non-volatile organic base salts, there are: the various phosphoric acids, the various phosphorous acids, monoand di-alkyl ester-phosphoric acids wherein, for example, the alkyl group is an ethyl, propyl, dodecyl, etc., radical; also cycloalkyl (naphthenic, terpenic, bornyl, cyclohexyl) acidic phospho esters.

Although phosphate anions are preferred for forming the organic base, non-nitrite, anionate salt component of the present mixtures other water-solubilizing anions may be used. Organic anions can be used as well as inorganic anions. ions are preferred. Examples of suitable anions are oxalate, benzoate, acetate, propionate, citrate, tartarate, borate, nitrate, sulfate, chloride, chromate, iodate, carbonate, etc. limitation upon the anion is that it be from an acid sufiiciently strong to form a salt With the organic base.

Organic base phosphates or other anionate salts which have been found applicable for use in conjunction with representative types of primary amines, secondary amines, tertiary amines, cyclic secondary amines of the type of piperidine, oxazines, morpholine, thiazines, thiaoxazines, pyrollidines, diazoles, imidazolines, diazines, pyrimidines; and various nitrogenous bases such as guanidine, urea, thiourea, hydrazines, hydroxylamines, etc. The various known sulvfonium organic bases are also suitable for forming sulfonium phosphate salts for use in the present invention. In any of the organic base nuclei (used to form the present organic base anionate salts),

Of the organic anions, the carboxylate I 1937 edition, in

to a secondarycarbon atom of an organic radical, as typified by a di-isobutyl amine phosphate, a di-isopropylamine phosphate, a difor example, in The by N. V. Sidgwick, Organic Chemistry by Paul Karrer, 1938 edition, and in Organic Chemistry by Fieser and Fieser, 1944 edition.

More specifically and preferably, organic nitrogenbase salts of a phosphoric acid include phosphoric acid salts of the following:

1. Primary amines such as (a) Primary amines in which the amino group is attached to a secondary or tertiary aliphatic carbon atom as in the following structural formulas:

is described, Organic Chemistry of Nitrogen wherein R1, R2 and R5 are hydrocarbon radicals which are aliphatic, alicyclic, heterocyclic, aromatic, or aland may, if desired, contain preferably not more than one olefinic double bond, or R1 and R are joined as indicated by R to form with the CH-group a cyclo-alip .atic or heterocyclic-aliphatic ring radical Rt CI'I (b) Primary amines in which the amino group is attached to an aralkyl group as in the following structural formula:

wherein R4 is an aromatic hydrocarbon radical, preferably a phenyl or substituted (Preferably alkylated) phenyl radical and n is an integer which is preferably 1 or 2;

c) Simple primary aliphatic amines, such as methyl amine.

2. Secondary amines, such as secondary amines in which the amino group is attached to an aliphatic carbon wherein R1 and R2 are hydrocarbon radicals as in 1 (a) and wherein R1 and R2 may be joined to form with the 7 NH-group a nitrogen-containing heterocyclic ring represented as which is either N-alicyclic or contains in the R3 portion of the organic ring, atoms of the type of oxygen and/or sulfur.

3. Tertiary amines.

4. Quaternary ammonium bases.

Specific examples of organic nitrogen bases suitable for preparation of the organic nitrogen-base non-corrosive anionate salts for utility in the practice of the present invention include:

Primary amines: methylamine, isopropyl amine, 2- aminobutane, tertiary butyl amine, Z-Qminor-mcthylpentane, various amyl, hexyl, heptyl, octyl, and higher homologous primary amines wherein the amine group is attached to a secondary or tertiary carbon atom; cyclopentyl amine, alkylated cyclopentyl amines, cyclohexylamine, mono-methyl cyclohexylamines, dimethyl cyclohexylamines, trimethyl cyclohexylamines, other alkylated cyclohexylamines, bornyl amine, fenchyl amine, cycloterpenyl amines, pinyl amine, benzylamine, betaphenylethylamine, alkylated benzylamines, tetrahydrobetanaphthylamine, allyl amine, betamethyl allyl amine, betachloro allyl amine, and their homologs and analogs.

Secondary amines: di-methyl-, di-ethyl-, di-n-propyl-, di-isopropyl-, di-butyl amines; various secondary amines derived from amyl, hexyl, heptyl, octyl, and higher homologous alkyl groups, methyl isobutyl amine, N- methyl N-tertiary-butyl amine, N-alkyl N-cyclohexyl amine, N-alkyl N-bornyl amine, di-bornyl amine, N- mcthyl N cycloterpenyl amine, N-isopropyl N-( l)- menthyl amine, N-alkyl N-benzyl amines and their homologs and analogs; dicyclopentyl amine, dicyclohexyl amine, alkylated dicyclohexyl amines; diphenylamine, dibenzylamine, di-(beta phenyl ethyl) amine; piperidine, piperazine, alkylated piperidines or piperazines; 1,4-alkylated and unalkylated oxazines such as morpholine and 2,4,4,6-tetramethyl tetrahydro-l,3-oxazine; alkylated 1,3-hiazine such as 2,4,4,6-tetramethyl tetrahydro-3-thiazine.

Second amine type derivatives of alkylene diamines, such as:

bases including pyridinium wherein R1 and R3 may be like or different aliphatic, alicyclic, aralkyl, alkarylalkyl, heterocyclic, terpenic radicals, and wherein R2 is an alkylene or cycloalkylene radical. These R1 and R3 radicals for instance, may be isopropyl, butyl, cyclohexyl, benzyl, and/or bornyl radicals. The R2 radical is preferably an ethylene or propylene radical.

Tertiary amines: trimethyl amine, triethylamine, trin-propylamine, tri-isopropylamine, tributylamine, higher homologous and isomeric trialkylamines, variously N- substituted tertiary amines having different organic radicals on the amino nitrogen atom, e. g., alkyl alicyclic, bornyl, fenchyl, aralkyl, and like homologs and analogs; and tertiary amine type derivatives of alkylene diamines.

Various organic nitrogenous bases particularly guanidine, alkylated guaindines, alkylated thioureas, and also diazoles, imidazoles, imidazolines, e. g., 2-heptyl-2- imidazoline, diazines, pyrimidines, and the basic derivatives of these and other organic nitrogenous-base nuclei.

Quaternary ammonium bases: tetramethyl and higher tetra-alkyl ammonium bases; trimethyl benzyl-, trimethyl cyclohexyl-, tributyl decyl ammonium bases; various quaternary N- substituted ammonium bases having various organic radicals (of the type described above) on the quaternary nitrogen atom; pyridinium and alkylated pyridinium or quinolinium quaternary ammonium bases having an alkyl, cycloalkyl, or aralkyl group on the quaternary nitrogen atom, including methyl, butyl, cyclohexyl, benzyl groups and like homologs or analogs.

The various hydrocarbon radicals or groups of the above organic nitrogen bases may also contain stable and inert polar substituent atoms or radicals, such as, chlorine, ether, thio-ether, alcohol, free amino, or nitro groups. Neutral ketone, ester and nitrile groups and aliphatic unsaturation may also be present, particularly in the case of allyl and chlorallyl groups.

In general the invention is preferably practiced by using as the non-nitrite salt, a phosphate salt formed by the addition of a phosphoric acid to a trivalent basic nitrogen atom of a nitrogenous organic compound.

The salts of a phosphoric acid or of other non-corrosive acid anions with the organic nitrogen-bases described above are preferably prepared by a relatively simple neutralization of such a base with the desired acid. If desired, it is effective to use two moles of an organo-nitrogen-base or an amine to react with one mole of a tribasic phosphoric acid, thus forming a diaminohydrogen-phosphate.

The amount or concentration of each of the essential components of the present mixtures, namely Water-soluble organic base salts and Water-soluble metal nitrite salts respectively, which may be present in the compositions and articles of this invention, may vary within wide limits, but it is preferred to use them in the smallest effective concentrations. The concentrations of each of the respective salts are preferably so chosen that interaction etween them in the impregnated fibrous material allows between approximately 0.05 gm. and about 5.0 gm. of the reaction product, a volatile organic base-nitrite salt, to form per square foot of the exposed or free surface of the substantially solid material employed therewith. The best or optimum results in most cases of fairly severe usage are obtained by having the respective salts present in amounts sufiicient to form by ionic interchange between about 0.5 gm. and about 2 gm. of a volatile organic base-nitrite salt per each square foot of such a surface. It is preferable to adjust the respective concentrations of the organic base salt and the metal nitrite salt in the material so that the organic cations are approximately stiochiometricaliy equivalent to the nitrite anions provided by the metal nitrite salt, although slight excesses, up to about 10% or 20% of either of the salts can be used without serious adverse effects.

The range of concentrations of the organic base salt in the impregnating solution will usually vary from about 1 wt. per cent to about 25 wt. per cent (or saturation, which ever is higher) in a given solvent. More often it is preferred to impregnate a fibrous material with between about 5% and about 20% by weight in solution of one or more of the specified salts. Also, the same concentrations for impregnation are useful for the aqueous metal nitrite solutions; in general, it is preferable to employ a somewhat higher solution ccncentration of the metal nitrite, such as about two to three times that employed for the organo phosphate salt.

The time required for the dipping or impregnating operations is readily determined (as to meet specific conditions for final concentrations of salts desired in the impregnated material) by empirical aliquot tests. For most purposes, however, the time of immersion of a fibrous material in an impregnating solution need not be more than about one minute, although longer times may be used; and in many cases immersion for approximately about one to about ten seconds in about a 10 wt. per cent concentration of impregnant in Water has been found to suffice.

Stability of the organic base-nitrite salts (i. e., vapor phase inhibitors), formed from interaction of the present mixtures of salts, is usually adversely afiiected when said organic nitrites are present in a composition or environment which, on contact with or dispersion in water, yields an aqueous phase which is appreciably acidic, that is has a pH value of less than approximately 6. Also this stability of the liberated organic nitrite salts is frequently adversely afiected by elevated temperatures, e. g., of the order of 120 F. or 150 These undesirable effects may be materially lessened, and even be entirely obviated by the simultaneous presence in the present mixtures of a basic-reacting agent, i. e., an alkaline agent or a compound which reacts as a base in the presence of acidic-reacting materials. As such basic-reacting stabilizers there may be used an organic or inorganic compound which, when dis persed in water, yields an aqueous phase having a pH of at least 7 and preferably somewhat higher than a pH of 7. As such stabilizers, reference is made. to amines, guanidine, alkaline and alkaline earth metal hydroxides, carbonates and bicarbonates, organic bases, basic salts, etc. The amount of stabilizer, when necessary, should be between about 0.1% and about by weight of the organic base nitrite salt to be liberated from the present mixtures, although larger or smaller amounts may be used.

In cases where the absorbent substantially solid material has a demand or chemical afiinity for an organic base, particularly for the amine employed to prepare the phosphate salt thereof, and which interacts in the impregnated material to liberate an amine nitrite, then it is preferable to treat such a solid absorbent material with the free amine until this demand is satisfied.

The novel compositions of substantially solid materials containing the metaIs normally corrodible in presence of an oxygen-containing gas and water. The broad class of covering or enveloping materials described herein containing said mixtures may be advantageously wrapped over, cloaked around, inserted near, draped over, or otherwise disposed in the immediate vicinity of metal parts, so long as at least sufiicient exterior coating or enbecause of the organic nitrite being insuificiently soluble in water or aqueous sity for the production of nitrous acid formerly needed to For purposes of further illustration, reference will now be made to the following examples, it being understood that there is no intention of being limited to the specific details disclosed therein.

Example 1 Samples of kraft wrapping paper were impregnated with certain salts as enumerated in the cases below by immersing 2 /2 by 3 /2 inch pieces of the paper for approximately ten seconds in water solutions (except where 10 weight, respectively, of: (l) disodium hydrogen phosphate, (2) sodium nitrite, and (3) dicyclohexylammonium phosphate (in methyl; alcohol). In the case of (4} the sample of paper was first immersed in a solution of dicyclohexylammoniurn phosphate as in (3) but then folfew seconds in an approximately 20% by weight sodium nitrite solution in water. The thus impregnated samples were then dried. A control piece of paper was also employed which had not been impregnated. Separate steel strips /z by 2 inches) were wrapped, respectively, inside the pieces of-papers prepared as described above. packages thus pre:

closed with stoppers and maintained at F. The results obtained from these tests are tabulated below:

Compound With Which Paper Appearance of Steel Testpregnated Strip After 625 Hours M (1) Disodiuin Hydrogen Phosphate Rust spots present-random distribution. (2) Sodium Nitrite Rust spots present, particularly near corners of wrap. (3) Dicyclohexylammonium phosphate Rust spots present-randorn distribution. (4) Dicyelohexylammonium phosphate No corrosion.

and sodium nitrite from dual impregnation. (5) Control (no impregnant) Rust spots present.

Example I] An aqueous slurry was prepared by adding to Water about 8.0 wt. per cent of casein, about 15.4 wt. per cent of dicyclohexylamine, about 3.8 phoric acid, and about in that order. A 5 x 5-inch piece of 30# kraft paper was coated with the slurry and then dried. The amount of slurry used was such that the total weight of dicyclohexylammonium and nitrite ions was equal to about 1 gram per square foot or" kraft paper.

A second sheet of paper was coated like the first, except that about 4.6 wt. per cent of acetic acid was used instead of the phosphoric acid in the slurry.

A 1" by l by 3" was stored outdoors for There was also placed in the carton a third steel bar wrapped in an uncoated and otherwise untreated piece of 30% kraft paper.

At the end of the three month period the steel bar in the untreated paper had 30% of its surface rusted, the steel bar in the paper coated with the first slurry had only a very slight trace (a very small fraction of 1%) of its surface rusted, and the steel bar in the paper coated with the second slurry was completely free of rust.

Example 111 noted otherwise) containing approximately 10% by compositions:

- wt. Organic w. wt. Metal wt. slurry No Binder percent base perc ent Acid percent nitrite percent M Casein. 8. 0 DICHA* 15. 4 Pl1osphoric 3. 8 5. 3 7.7 DICHA 14.9 (10 3.7 6.5 8.1 DICHA 15.6 .....(10 3.9 4.8 8. O DICHA... 15. 4 BOliC 4. 8 5. 3 8.0 DICHA-.. 15. 4 Phosphoric. 3.8 5. 8 8.0 DICHA... 15.4 -l d0 3.8 6.6 8. U DICHA 15. 4 Citric. 4. 9 5. 3 8. O DICH l5. 4 Acetic 4. 6 5. 3 8. 0 DICHA. 15. 4 Carbonic.-- 5. 3 *Dicyclohexylarnine.

Treated with 002 until all of DICHA converted to water-soluble salt.

Example IV Other slurries suitable for coating paper as in Examples II and III, were prepared as follows:

- wt. Organic wt. wt. Metal wt. Slurry Binder percent base percent Acld percent nitrite percent 6. 0 DICHA 15. 7 Phosphorio. 3. 8 NaNOz. 5. 4 8.0 DICHA 15.4 Sulfuric 3.7 NYLNO U 5.3 8. 0 DICEIAUt 15. 4 5. 8 5. 3

Tartarie This application is a continuation-in-part of our copending application, Serial No. 782,047, filed October 24, 1947, now abandoned, which is in turn a continuation-in-part of our copending application, Serial No. 557,358, filed October 5, 1944, now abandoned.

We claim as our invention:

1. The method of preparing a substantially solid composition capable of inhibiting metal corrosion in the presence of moisture and air, which method comprises coating a paper with a suspension obtained by mixing water, a dicyclohexylamine phosphate and sodium nitrite in the presence of adhesive casein used in an amount suf ficient to bind the resultant mixture to said paper, the amounts of said phosphate and said nitrite being sufficient to form, by ionic interchange, between about 0.05 gram and about 5.0 grams of dicyclohexylamine nitrite per each square foot of paper surface thus coated, and drying the coated paper, said solid composition, when in contact with water, resulting in a liquid phase having a pH value of at least about 6.

2. The method of preparing a substantially solid composition capable of inhibiting metal corrosion in the presence of moisture and air, which method comprises coating a paper with a suspension obtained by mixing water, a secondary amine phosphate and an alkali metal nitrite in the presence of an effective binding amount of a colloidally dispersible adhesive for the resultant mixture to said paper, the amounts of said phosphate and said nitrite being suflicient to form, by ionic interchange, between about 0.05 gram and about 5.0 grams of a volatile secondary amine nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C. per each square foot of paper surface thus coated, and drying the coated paper, said solid composition, when in contact with water, resulting in a liquid phase having a pH value of at least about 6.

3. The method of preparing a substantially solid composition capable of inhibiting metal corrosion in the presence of moisture and air, which method comprises coating a substantially solid fibrous material with a suspension obtained by mixing water, a water-soluble organic nitrogen-base phosphate salt and a water-soluble metal nitrite in the presence of an efiective binding amount of an adhesive for the resultant mixture to said paper, the amounts of said phosphate and said nitrite being sufficient to form, by ionic interchange, a corrosion-inhibiting amount of a volatile organic nitrogen-base nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C., and drying the coated fibrous material, said solid composition, when in contact with water, resulting in a liquid phase having a pH value of at least about 6.

4. A material capable of inhibiting metal corrosion in the presence of moisture and air, which material comprises paper coated with a mixture of casein and the total product of ionic exchange of dicyclohexylamine phosphate and sodium nitrite in amounts such that the total of stoichiometrically equivalent amounts of dicyclohexylammonium ions and nitrite ions is between about 0.05 gram and about .0 grams per square foot of paper, said casein being present in an amount suificient to bind said ionic exchange product to said paper, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

5. A material capable of inhibiting metal corrosion in cyclohexylamine phosphate and sodium nitrite in amounts such that the total of stoichiometrically equivalent amounts of dicyclohexylammonium ions and nitrite ions between about 0.05 gram and about 5.0 grams per square foot of paper, said adhesive agent being present in an amount sufficient to bind said ionic exchange prodnot to said paper, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

6. A material capable of inhibiting metal corrosion in the presence of moisture and air, which material comprises paper impregnated with the total product of ionic exchange of dicyclohexylamine phosphate and sodium nitrite in amounts such that the total of stoichiometrically equivalent quantities of dicyclohexylammoniumions and nitrite ions is between about 0.05 gram and about 5.0 grams per square foot of paper, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

7. A material capable of inhibiting metal corrosion in the presence of moisture and air which material comprises paper coated with a mixture of an adhesive binding agent and the total product of ionic exchange of amine phosphate and a water-soluble alkali metal nitrite salt in amounts such that the total of stoichiometrically equivarent quantities of ammoniumcation and nitrite anion is sutiicient to form a corrosion-inhibiting amount of a volatile amine nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C., said adhesive agent being present in an amount suflicient to bind said ionic exchange product to said fibrous material, said material, when in contact with Water, yielding a liquid phase having a pH value of at least about 6.

8. A material capable of inhibiting metal corrosion in the presence of moisture and air which material comrises paper coated with a mixture of an adhesive binding agent and the total product of ionic exchange of an organic nitrogen-base phosphate salt and a water-soluble metal nitrite salt in amounts such that the total of stoichiometrically equivalent quantities of organic nitrogenbase cation and nitrite anion is sufilcient to form a corrosion-inhibiting amount of a volatile organic nitrogenbase nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C., said adhesive agent being present in an amount suflicient to bind said ionic exchange product to said fibrous material, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

9. A material capable of inhibiting metal corrosion in the presence of moisture and air, which material comprises a substantially inert solid fibrous material having physically associated therewith the total product of ionic exchange of an organic nitrogen-base phosphate salt and a water-soluble metal nitrite salt in amounts such that the total of stoichiometrically equivalent quantities of organic nitrogen-base cation and nitrite anion is sufiicient to form a corrosion-inhibiting amount of a volatile organic nitrogen-base nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C., said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

10. A material capable of inhibiting metal corrosion in the presence of moisture and air which material comprises a substantially inert solid fibrous material coated with a mixture of an adhesive binding agent and the total product of ionic exchange of an organic nitrogen base phosphate salt and a water-soluble metal nitrite salt in amounts such that the total of stoichiometrically equivalent quantities of organic base cation and nitrite anion is suflicient to form a corrosion-inhibiting amount of a volatile organic base nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C., said adhesive agent being present in an amount sufficient to bind said ionic exchange product to said fibrous material, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

11. A material capable of inhibiting metal corrosion in the presence of moisture aid air, which material coinprises paper coated with a mixture of casein and the total product of ionic exchange of a dicyclohexylammonium carboxylate salt and sodium nitrite in amounts such that the total of stoichiometrically paper, said casein being present in an amount suflicient to bind said ionic exchange product to said paper, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

12. A material capable inhibiting metal corrosion in the presence of moisture and air, which material comprises paper coated with a mixture of casein and the total product of ionic exchange of the sodium salt of nitrous acid and the dicyclohexylarnmonium salt of the group consisting of phosphates and carboxylates in amounts such that the total of stoichiometrically equivalent amounts of dicyclohexylammonium ions and nitrite ions is between about 0.05 gram and about 5.0 grams per square foot of paper, said casein being present in an amount sufiicient to bind said ionic exchange product to said paper, said material, when in contact with water, yielding a liquid having a pH value of at least about 6.

13. A material capable of inhibiting metal corrosion in the presence of moisture and air, which material comprises an inert solid sheet packaging material having physically attached thereto the total product of ionic exchange of a water-soluble metallic salt of nitrous acid and an organic nitrogen base salt of the group consisting of phosphates and carboxylates in amounts such that the total of stoichiometrically equivalent quantities of organic base cation and nitrite anion is suificient to form a corrosion-inhibiting amount of a volatile organic base nitrite salt having a vapor pressure of at least 0.00002 mm. Hg at 21 C., said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6. p 1

14. A material capable of inhibiting metal corrosion in the presence of moisture and air, which material comprises an inert sheet packaging material having physically of phosphates and carboxylates having a vapor pressure C. and an organic amounts sufiicient to least 0.00002 mm. Hg at 21 C. in amounts suflicient to form a corrosion inhibiting composition, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 16. A material capable of inhibiting metal corrosion in the presence of moisture and air, which material comprises an inert solid sheet packaging material having physically attached thereto an alkali metal phosphate and a hydrocarbon ammonium nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C. in amounts sufficient to form a corrosion inhibiting composition, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

17. A material capable of inhibiting metal corrosion in the presence of moisture and air, which material comprises an inert solid sheet packaging material having physically attached thereto a sodium phosphate and a dicyclohexylammonium nitrite having a vapor pressure of at least 0.00002 mm. Hg at 21 C. in amounts sufiicient to form a corrosion inhibiting composition, said material, when in contact with water, yielding a liquid phase having a pH value of at least about 6.

References Cited in the file of this patent UNITED STATES PATENTS 2,304,950 Parker Dec. 15, 1942 2,416,734 Boggs Mar. 4, 1947 2,419,327 Wachter Apr. 22, 1947 2,574,526 Borden Nov. 13, 1951 2,577,219 Wachter Dec. 4, 1951 2,643,176 Wachter Iune 23, 1953 2,643,177 Wachter June 23, 1953

Claims (1)

1. THE METHOD OF PREPARING A SUBSTANTIALLY SOLID COMPOSITION CAPABLE OF INHIBITING METAL CORROSION ON THE PRESENCE OF MOISTURE AND AIR, WHICH METHOD COMPRISES COATING A PAPER WITH A SUSPENSION OBTAINED BY MIXING WATER, A DICYCLOHEXYLAMINE, PHOSPHATE AND SODIUM NITRITE IN THE PRESENCE OF ADHESIVE CASEIN USED IN AN AMOUNT SUFFICIENT TO BIND THE RESULTANT MIXTURE TO SAID PAPER, THE AMOUNTS OF SAID PHOSPHATE AND SAID NITRITE BEING SUFFICIENT TO FORM, BY IONIC INTERCHARGE, BETWEEN ABOUT 0.05 GRAM AND ABOUT 5.0 GRAMS OF DICYCLOHEXYLAMINE NITRITE PER EACH SQUARE FOOT OF PAPER SURFACE THUS COATED, AND DRYING THE COATED PAPER, SAID SOLID COMPOSITION, WHEN IN CONTACT WITH WATER, RESULTING IN A LIQUID PHASE HAVING A PH VALUE OF AT LEAST ABOUT 6.