US2965577A

US2965577A - Corrosion inhibitor composition and method of using same

Info

Publication number: US2965577A
Application number: US637612A
Authority: US
Inventors: Heimann Hugo; Kohn David Harry; Israel Yecheskel
Original assignee: Technion Research and Development Foundation Ltd
Current assignee: Technion Research and Development Foundation Ltd
Priority date: 1956-05-06
Filing date: 1957-02-01
Publication date: 1960-12-20
Anticipated expiration: 1977-12-20
Also published as: GB803541A

Description

United States Patent 0 CORROSION INHIBITOR COMPOSITION AND METHOD OF USING SAME Hugo Heimann, Kiryath Bialilr, and David Harry Kolm and Yecheskel Israel, Haifa, Israel, assignors of onefourth to Techuion Research and Development Foundation Limited, Haifa, Israel, a company of Israel No Drawing. Filed Feb. 1, 1957, Ser. No. 637,612

Claims priority, application Israel May 6, 1956 16 Claims. (Cl. 252148) This invention relates to pickles for the treatment of metal surfaces.

The usual pickles are aqueous solutions of mineral acids, or of substances having an acid reaction or being capable of splitting off acids, which serve for cleaning metal surfaces by removing coatings or films of metal oxides, carbonates, sulfides or the like, or of oil or of other impurities. As the acids or acidic substances are apt not only to remove the coating or film but also to affect the metal itself, they are usually admixed with inhibitors, i.e. substances that have the property of preventing the attack on the metal or, at least, to slow it down to such an extent that the operator can safely determine the correct time of withdrawal of the metal from the pickling bath.

However, known icklin 'nhibitors have the desired effect on iron and steel only and, even in that case, they have, in general to be used in relatively high proportions. Known Pickling inhibitors have been found to have virtually no protective effect in the case of metals which are even more susceptible of being attacked by acids, such as alu um a zinc.

The present invention, therefore, has for its object to provide a pickle mixture (which term will be used hereafter for the sake of brevity, for the designation of pickles admixed with pickling inhibitors) capable of use for cleaning not only iron or steel surfaces, but also those of other metals which are more readily attacked by pickling agents, especially aluminum and zinc.

The invention consists in pickle mixtures containing as pickling inhibitors at least one aromatic or araliphatic aldehyde, and at least one basic nitrogen-containing aromatic compound.

In the context of this specification and the appended claims, the term aromatic includes, besides the aromatic hydrocarbon proper, also heterocyclic compounds of aromatic character, in accordance with the usage of modern textbooks of organic chemistry. (See, e.g. P. Karrer, Lehrbuch der org. Chemie, 1954.) Further, the term araliphatic aldehyde" is used to denote aliphatic aldehydes substituted by an aryl group, examples of such compounds being phenylacetaldehyde, cinnamaldehyde, etc.

The following aromatic aldehydes have been successfully used in carrying out the present invention:

Benzaldehyde Salicylaldehyde Vanillin Furfuraldehyde Phenylacetaldehyde a-Naphthaldehyde Cinnamaldehyde Para-hydroxybenzaldehyde The following nitrogen-containing aromatic compounds have been successfully used in carrying out the present invention:

Aniline Cinchonine Pyridine Cocaine Quinoline, Brucinc Nicotine drtfter 168 hour 2,965,577 Patented Dec. 20, 1960 "ice The application of pickle mixtures according to the invention are manifold. As examples there can be cited: thi kjfgu fl mwigflfigt, e.g. aluminum ettles; the doom atio o uminum a d zinc surfaces prior to galvanic coating; the preparation of clean aluminum and zinc surfaces prior to welding; the preparation of extremely clean aluminum and zinc surfaces for chemical reactions in which these metals are required to have a reactive surface without any oxide barrier; the protection of containers made from f aluminum or zinc and containing either free acid, or substances which are able to split 06 acids in the course i of time, from being attacked by these acids, etc.

The total proportion of the inhibitors in the pickle mixture, as well as the relative proportions of the inhibitor components, must be adapted to individual cases. On an average, mole of the aldehyde component and 0.01 mole of the N-compound component, both per liter of pickle mixture, have proved to be favorable.

The invention is illustrated in the following examples,

to which it is not limited. In these examples, strips of different metals -4 x 5 cms. in size were used and were treated at different temperatures and with different acids containing inhibitors in accordance with this invention. In order to afford a proper basis for comparison, control tests were carried out on strips of the same metals, using the same acids but in the absence of inhibitors. The control tests were as follows:

(1) Aluminum strips 4 x 5 cms. were immersed in hydrochloric acid of 10% strength, at room temperature; they were completely dissolved within 35 minutes;

(2) Aluminum strips 4 x 5 cms. were immersed in 10% sulphuric acid; they dissolved slowly but, nevertheless, at a rate three times that obtaining when an inhibitor Example I The pickle mixture was composed of mls. of aqueous hydrochloric acid of 10% strength by weight, 0.53 g. of a 40% aqueous nicotine sulfate solution, and 0.3 g. of benzaldehyde.

Into this solution an aluminum strip was submerged at 20 C. and the following losses were observed:

I Mg. 2.2 17.1

After 24 hours Example 2 On repeating the same experiment at 40 C., the following losses were observed:

Mg. After 1 hour 1.9 After 3 hour 4 Example 3 n submersion of an aluminum strip into this solution at a temperature of 20 C., the following losses were observed:

Mg. After 24 hour 3.6 After 168 hour 21 Example 4 0n repeating the last experiment at 40 C., the following losses were observed:

Mg. After 1 hour 3 After 3 hours 5 4 Example 5 On submersion of a in a solution prepared according to Example and at 20 C., the following losses were observed:

Mg. After 24 hours 6.5 After 168 hours 26.4

Example 6 The pickle m xture was composed of 100 ml. of hydrochloric acid solution of strength by weight, 0.53 g. of a 40% nicotine sulfate solution and 0.27 g. of furfuraldehyde.

On submersion of an aluminum strip at a temperature of 20 C., the following losses were observed:

Mg. After 24 hours 3.6 After 72 hours 14 Example 7 On repeating the last experiment at a temperature of 40 C., the following losses were observed:

Mg. After 1 hour 1.8 After 3 hour 4.4

Example 8 The pickle mixture was composed of 100 ml. of an aqueous hydrochloric acid solution of 10% strength by Weight, 0.36 g. of cinchonine sulfate and 0.34 g. of phenylacetaldehyde.

On submersion into this solution of an aluminum strip at 20 C., the following losses were observed:

Mg. .After 24 hours 3.2 After 72 hours 7.6

Example 9 On repeating the experiment according to Example 8 with a zinc strip, the following losses were observed:

Mg. After 24 hour 2.8 After 72 hour 7.1

Example 10 The pickle mixture was composed of 100 ml. of an aqueous hydrochloric acid solution of 10% strength by weight, 0.53 g. of a 40% aqueous nicotine sulfate solution. 0.3 g. of benzaldehyde and 0.5 g. of furfuraldehyde.

On submersion into this solution of an aluminum strip at a temperature of 30' C., a loss of 30.0 mg. was observed after 96 hours.

Example 11 The pickle mixture was composed of 100 ml. of an aqueous hydrochloric acid solution of 15% strength by weight, 0.3 g. of benzaldchyde and 0.5 g. of a 40% aqueous nicotine sulfate solution.

On submersion into this solution of an aluminum strip at a temperature of C., a loss of 26 mg. was observed after three days.

4 Example 12 The pickle mixture was composed of ml. of an aqueous sulfuric acid solution of 10% strength by weight, 0.3 g. of benzaldehyde and 0.36 g. of cinchonine sulfate.

On submersion into that solution of a zinc strip at a temperature of 20 C., a loss of 11 mg. was observed after three days.

Example 13 By repeating the last experiment but using a 20% sulfuric acid solution, a loss of 9 mg. was observed after 24 hours.

Example 14 The pickling mixture was composed of 100 ml. of an aqueous hydrochloric acid solution of 10% strength by weight, 0.44 g. a-naphthaldehyde and 0.36 g. cinchonine sulfate.

On submersion into this solution of an aluminum strip at 20 C. for two days, a loss of 6 mg. was observed, and after twelve days, the loss was 28 mg.

Example 15 On repeating the experiment according to Example 14 with a zinc strip, the following losses were observed:

Mg. After 2 days 6 After 12 days 15 After 30 days 62 it is possible to prepare inhibitor concentrates by dissolving the components in a common solvent. A few drops of such a concentrate are then added to the acid solutions whenever needed.

Such concentrates may for example, be composed as follows:

15 g. of benzaldehyde 25 g. of nicotine sulfate 45 g. of methanol 15 g. of ethylacetate 15 g. of benzaldehyde 25 g. of nicotine sulfate 60 g. of dimethylformamide 25 g. of a 40% aqueous nicotine sulfate solution 15 g. of benzaldehyde 60 g. of methylcellosolve which is the trade name of 2- mcthoxy ethanol or glycol monomethyl ether.

Although it appears that nicotine, cinchoninc and other alkaloids are very suitable for the purposes of the present invention, it is not always practical to use these sub stances on an industrial scale owing to their relatively high price. In such cases, other simpler and cheaper basic N-compounds may be used, as illustrated in the following examples:

Example 16 The pickle mixture was composed of 100 ml. of an aqueous hydrochloric acid solution, 10% strength by weight, 0.3 g. benzaldehyde and 0.1 g. aniline.

0n submersion into this solution of an aluminum strip at 20 C. for three days, a loss of 9.5 mg. was observed.

Example 17 important applications is the use of the inhibitors of this invention in the protection of aluminum aerosol containers-where hydrolysis has been a real problem-and aluminum tubes and containers for other products which present a problem of corrosion.

We claim:

1. A pickle mixture for zinc and aluminum surfaces consisting essentially of an acid and, a hibitor, a $13 of at least one aldehyde compound selected from t group consisting of benzaldehyde, furfuraldehyde, phenyl acetaldehyde, alpha naphthaldehyde, and at least one basic N-containing aromatic compound selected from the group consisting of nicotine, cinchonine, aniline, quinoline, and pyridine, the quantity used of each of said compounds being suflicient to prevent corrosion when used in combination.

2. A pickle mixture according to claim 1, in which the N-compound is nicotine.

3. A pickle mixture according to claim 1, in which the N-compound is cinchonine.

4. A pickle mixture according to claim 1, in which the N-compound is aniline.

5. A pickle mixture according to claim 1, in which the N-compound is quinoline.

6. A pickle mixture according to claim 1, in which the N-compound is pyridine.

7. A pickle mixture according to claim 1, in which the aldehyde is benzaldehyde.

8. A pickle mixture according to claim 1, in which the aldehyde is furfuraldehyde.

9. A pickle mixture according to claim 1, in which the aldehyde is phenyl-acetaldehyde.

10. A pickle mixture according to claim 1, in which the aldehyde is a-naphthaldehyde.

11. A corrosion inhibitor composition for add'tion to aqueous solutions, capable of causing acidic corrosion to zinc and aluminum surfaces, consisting essentially of a mixture of at least e aldehyde compound selected from the group consisting of Benzaldehyde, furfuraidehyde, phenyl acetaldehyde, alpha naphthaldehyde, agd Lge t one basic N-containi atic compound selected rom the group consisting of nicotine, conchonine, aniline, quinoline, and pyridine, the quantity used of each of said compounds being suflicient to prevent corrosion when used in combination.

12. The method of pickling surfaces of metals selected from the group consisting of aluminum and zinc which comprises the step of: subjecting the metal to a bath containing an acid and an inhibitor consisting of a mixture of at least one aldehyde compound selected from the group consisting of benzaldehyde, furfuraldehyde, phenyl acetaldehyde, alpha naphthaldehyde, and at least one basic N-containing aromatic compound selected from the group consisting of nicotine, cinchonine, aniline, quinoline and pyridine, the quantity used of each of said compounds being suflicient to prevent corrosion when used in combination.

13. A method according to claim 12, wherein the metal surfaces comprise aluminum.

14. A method according to claim 12, wherein the metal surfaces comprise zinc.

15. An aerosol container formed of a material containing a metal selected from the group consisting of zinc and aluminum, containing therein a composition normally corrosive to said material, and an inhibitor consisting of a mixture of at least one aldehyde compound selected from the group consisting of benzaldehyde. furfuraldehyde, phenyl acetaldehyde, alpha naphthaldehyde, and at least one basic N-containing aromatic compound selected from the group consisting of nicotine, cinchonine, aniline, quinoline and pyridine, the quantity used of each of said compounds being sufiicient to prevent corrosion when used in combination.

16. An aerosol'container according to claim 15, wherein there is used about 0.03 mole of the aldehyde and about 0.01 mole of the basic N-containing aromatic com pound per litre of the product.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Corrosion Handbook by Uhlig, pp. 910,

911, pub. by John Wiley & Sons, Inc., NY. (1948).

Claims

11. A CORROSION INHIBITOR COMPOSITION FOR ADIDTION TO AQUEOUS SOLUTIONS, CAPABLE OF CAUSING ACIDIC CORROSION ZINC AND ALUMINUM SURFACES, CONSISTING ESSENTIALLY OF A MIXTURE OF AT LEAST ONE ALDEHYDE COMPOUND SELECTED FROM THE GROUP CONSISTING OF BENZALDEHYDE, FURFURALDEHYDE, PHENYL ACETALDEHYDE, ALPHA NAPHTHALDEHYDE, AND AT LEAST ONE BASIC N-CONTAINING AROMATIC COMPOUND SELECTED FROM THE GROUP CONSISTING OF NICOTINE, CONCHONINE, ANILINE, QUINOLINE, AND PYRIDINE, THE QUANTITY USED OF EACH OF SAID COMPOUNDS BEING SUFFICIENT TO PREVENT CORROSION WHEN USED IN COMBINATION.