DE1246358B - Mixture to prevent corrosion on metal surfaces - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

PATENT OFFICE

EDITORIAL

Int. Cl .:

C23f

German class: 48 dl -11/14

Number: 1 246 358

File number: B 70877 VI b / 48 d 1

Filing date: February 25, 1963

Opened on August 3, 1967

The invention relates to a mixture for preventing corrosion on surfaces of metals, especially of copper, copper alloys and ferrous metals, when exposed to aqueous, Solutions containing dissolved salts and gases.

Water works, especially when substances like chlorides, sulphates, sulphides, bisulphates or gases like Oxygen, hydrogen sulfide, carbon dioxide and chlorine are dissolved in it, corrosive to ferrous metals, Copper and copper alloys. The rate of corrosion depends on the im Substances dissolved in water still depend significantly on the temperature and pH of the aqueous solution. For example, an increase in the temperature of the aqueous solution by 14 ° C. doubles the rate of corrosion of copper alloys.

Corrosion is always an unpleasant phenomenon that must be prevented.

For example, efforts are being made in the paper industry to prevent copper alloys from being made Fourdrinier machine screens are prematurely destroyed by corrosion. Investigations showed that the main factors affecting the useful life of such screens, damage to the screen, more mechanical Wear and corrosion are. These factors can be used alone or in combination with one another works.

It has been found that in addition to damage and mechanical wear, several types of corrosion of copper alloys are important for influencing the service life of a Fourdrinier wire. These Types of corrosion are:

(1) Surface corrosion, in which the surface of the warp and weft wires is fairly uniform corrodes, which leads to a decrease in wire diameter. Generally a Brass weft wire corrodes faster than bronze warp wire. The surface corrosion leads to a fairly uniform surface etching, sometimes accompanied by tarnishing or discoloration.

(2) Galvanic or bimetallic corrosion is caused by two different types Metals or alloys come into contact and form a galvanic element. This occurs e.g. B. between the brass shot and the bronze chain of a Fourdrinier, the Brass shot corroded pretty quickly. Obviously, the corrosion on seams falls into these Category.

Mixture to prevent corrosion on metal surfaces

Applicant:

Buckman Laboratories, Inc.,

Memphis, Tenn. (V. St. A.)

Representative:

Dipl.-Ing. F. Weickmann,

Dr.-Ing. A. Weickmann,

Dipl.-Ing. H. Weickmann

and Dipl.-Phys. Dr. K. Fincke, patent attorneys, Munich 27, Möhlstr. 22nd

Named as inventor:

Stanley Joseph Buckman,

John Dominic Pera,

William Paul Purcell, Memphis, Tenn. (V. St. A.)

Claimed priority:

V. St. v. America July 16, 1962 (210 240) - -

(3) Pitting and dezincification are usually associated with the formation of a copper sulfide film on the surface of the wire. When such films break or become porous, localized corrosion occurs, resulting in metal loss, creating pits or pits These surface films often experience zinc loss from the brass chain Impact pitting results from the turbulent flow of a liquid over a metal surface, leaving elongated pits behind.

(4) Corrosion fatigue and intergranular corrosion appear to be related. The corrosion lowers the resistance to fatigue, and the presence of fatigue stresses results in an increased tendency to corrosion. Grain corrosion calls embrittlement emerges.

Because of the important role played by the Fourdrinier in papermaking and because of it extraordinary sensitivity to mechanical stresses, wear and tear and other harmful ones

709 619/674

Corrosion in waterflood systems is also an important factor in oil production. In this context, a discussion of the causes and the extent is provided

5 of the corrosion in such systems is based on the treatise by L. C. C a s e entitled "Will corrosion eat up the water-flood profit? "in The Oil and Gas Journal, p. 76, January 16, 1961, referenced, [η this article is chemical corrosion

ίο as a result of the action of dissolved oxygen, hydrogen sulfide and carbon dioxide and bacterial corrosion are discussed. An organism which commonly occurs with bacterial corrosion is Desulfovibrio desulfuricans;

15 this is due to metabolic processes which sulfate is reduced, hydrogen sulfide in freedom. From this article it appears that the Corrosion in water flush systems is a major problem.

The present invention now relates to an effective corrosion preventive mixture, in particular for copper, copper alloys and ferrous metals whose surfaces come into contact with aqueous solution come.

25 This mixture inhibits when in small amounts of an aqueous, corrosive liquid is added, their corrosive effect. It is characterized by a content of 20 to 80 parts an alkali metal salt of 2-mercaptobenzothiazole

30 and 20 to 80 parts of an N, N-dimethylamide of a straight-chain carboxylic acid containing 18 carbon atoms and contains at least one carbon-carbon double bond. Generally speaking, the corrosion of

35 copper, copper alloys and ferrous metals, which with an aqueous, dissolved corrosive compounds containing system are in contact, inhibited by the fact that such an aqueous System a mixture containing an alkali metal salt

40 des 2-mercaptobenzothiazole and an N, N-dimethylamide a straight-chain unsaturated carboxylic acid is added.

To give just one example, the combination of alkali metal salts, the 2-mercaptobenzene

45 thiazols and of Ν, Ν-dimethylamides of long-chain unsaturated fatty acids give the fourdrinier treated with them excellent protection. With Screens treated with the mixtures of the invention resist the formation of copper sulfide

50 Reaction of hydrogen sulfide with the sieves. The sieves come with a sufficient amount of the Mixture coated in such a way that they wear an effective protective film that protects them against the effects of protects oxidizing, corrosive agents;

55 the 2-mercaptobenzothiazole acts as an antioxidant, since it is converted into a disulfide, namely benzthiazolyl disulfide.

C-S-S-C

The machine sieve must be exposed to any influences
Chunks that are between the various reels
and the machine sieve and that
Expand the machine sieve, be protected. to
this purpose are in different positions relative
water showers arranged for the machine sieve, which are all on the machine sieve and
Wash away larger pieces of material accumulating on the screen deflection rollers. A method is known for delaying or eliminating the corrosion of Fourdrinier sieves in which an inhibitor (corrosion preventive mixture) is introduced into the water shower system
is given so that a uniform coating of the
Sieve is created. When adding the inhibitor
happens continuously, the surface of the
Sieves continuously exposed to the inhibitor solution.
In some cases, however, the discontinuous addition of the inhibitor to the shower system also results
an excellent effect against corrosion and
an extended useful life of the screen. Another
Known method for preventing corrosion, for example on the sieves of Fourdrinier machines, consists in using the inhibitor
Paper pulp and water consisting of a mixture of a
Paper machine, the one with the fourdrinier machine
comes in contact to admit.

In the known methods one used the
Compound 2-mercaptobenzothiazole or its salts
either alone or in combination with others
organic or inorganic substances as corrosion inhibitors. However, these known corrosion inhibitors protect z. B. Fourdrinier screens not sufficiently protected from corrosion. For example, caused
they only provide inadequate protection against the effects
of dissolved gases, such as B. hydrogen sulfide; the
Fourdrinier screens also received no anti-smear film;
such a protective film is necessary if excessive mechanical wear is to be prevented
target. In addition, many additives are theirs
Use together with 2-mercaptobenzothiazole
has been proposed not compatible with
certain other chemicals used in papermaking.

In the oil industry, too, you have a permanent one
Fight against corrosion, for example of drill hole inserts made of steel and other metals that are under
Exposure to water and natural, dissolved
Salt solutions containing sulfides and / or carbon dioxide are available. Corrosive sulfide salt solutions can contain alkali metal and alkaline earth metal sulfides and hydrogen sulfide. Hydrogen sulfide is in water, saline solutions, and crude oil
very soluble and forms corrosive effects
Solutions that destroy borehole operations
and on their corrosion-sensitive equipment
cause. Corrosion takes place in both acidic as
also take place in alkaline salt solutions.

C —SH + [O]

The mixtures prepared according to the invention have an only weakly alkaline pH. These stable solutions that are easily handled and the 65 diluted solutions in water do not foam and to be protected system supplied with metering pumps give systems used in paper mills can be. If these mixtures with water even have a defoaming effect. Because the diluted They provide stable emulsions, and amides are very unreactive and very non-reactive

are resistant to hydrolysis, these blends are compatible with most of the systems found in paper mills, compatible. They also act as a cleaning agent and solvent for cellulose resin, the is an annoying component of some pulps used in paper mills.

Before proceeding to the specific examples which illustrate the invention, it seems appropriate to the nature of the necessary for the procedure To indicate materials in general.

Any alkali metal salts of 2-mercaptobenzothiazole can be used in the process according to the invention will. Among the examples of specific salts, because of their price and their accessibility preferred include the sodium and potassium salts.

Suitable Ν, Ν-dimethylamides of straight-chain Carboxylic acids are those made from carboxylic acids containing 18 carbon atoms. In addition to the 18 carbon atoms, these acids have at least one carbon-carbon double bond on. Specific acids that can be classified in this category include oleic acid, Linoleic acid, linolenic acid, ricinoleic acid and mixtures thereof. The mixed ones are also suitable Acids found in tall oil, castor oil, corn oil, cottonseed oil, linseed oil, olive oil, peanut oil, rapeseed oil, Safflower oil, sesame oil and soybean oil are included. A mixture of carboxylic acids designed for use is particularly suitable in the process according to the invention is that which as tall oil fatty acid under called Unitol ACD (registered trademark) is commercially available. A typical analysis follows of this product:

Table 1

Fatty acids, ° / o

Resin acids,%

Unsaponifiable, ° / ₀ ....

Linoleic acid,%

Oleic acid,%

Saturated acid, ° / o · ■ ·

Acid number

Saponification number

Color according to G ard η er
Viscosity, SSU 37.8 ⁰ C

Gardner seconds

specific weight

15.6 ° C / 15.6 ° C

Titer, ⁰ C

Flash point, ⁰ C

Focus, ⁰ C

Prescribed area

98.8 to 99.7 0.2 to 0.6 0.1 to 0.6

2.0 to 2.8 198 to 201 198 to 202 -3 to

-1 to 1.0

Typical analysis

98.9 0.5 0.6 45 51 2.4 199 200

3 + 105 0.9

0.905

0.0 190.6 223.9

The amounts of the two components that make up the active ingredients of the corrosion inhibitor mixtures can form, in the range of 20 to 80 parts of the alkali metal salt of 2-mercaptobenzothiazole, the are mixed with 20 to 80 parts of the Ν, Ν-dimethylamide of the carboxylic acid, vary. Something better Results are obtained when the ratio of the two components that make up the corrosion inhibitor form, between 40 to 60 parts of the alkali metal salt of 2-mercaptobenzothiazole to 40 to 60 parts of the Ν, Ν-dimethylamide is a straight-chain carboxylic acid. Under parts are used here in the following examples and understood in the claims as parts by weight.

When the corrosion inhibitor mixture according to the invention in connection with a Fourdrinier machine is used, it can be added to the aqueous, circulating in the machine and in with the Fourdrinier Coming into contact in amounts of at least 0.5 to 1000 parts per million parts of the solution aqueous solution are added. An equivalent

ίο amount of inhibitor (0.5 to 100 parts inhibitor per Million parts of downhole fluids) is also suitable for use in water flushing operations. Larger amounts of the inhibitor can be used, but this is undesirable because it does so the cost is increased while no corresponding useful results are obtained. When the corrosion inhibitor is added to the water shower system, it usually becomes a higher concentration applied, the shower water used between 5 and 5000 parts per million parts lies.

Manufacturers or users of the machine sieve can also use these mixtures to apply a coating to the sieves that provides corrosion resistance during shipping and storage. The sieves can be sprayed or dipped, wherein a solution is used in which the concentration of the inhibitor may be up to 5 ° / _0th

For convenience and ease of handling, the corrosion inhibitor mixture is used generally in the form of a solution of the two active ingredients, the alkali metal salt of 2-mercaptobenzothiazole and of Ν, Ν-dimethylamide, in one or more inert solvents in the Traded, the amount of the two active ingredients between 40 and 70 parts and the one of the solvent is between 30 and 60 parts. For example, one solution includes that for sale is particularly suitable, about 30 parts of potassium-2-mercaptobenzothiazole, about 30 parts of Ν, Ν-dimethylamides of tall oil fatty acids, about 30 parts of water and about 10 parts of hexylene glycol. In addition to water and hexylene glycol, suitable solvents include aliphatic alcohols, such as. B. methanol, ethanol and isopropanol, ketones, such as. B. acetone, glycols, such as ethylene glycol, diethylene glycol and hexylene glycol, and glycol ethers, such as. B. the methyl and ethyl ether of ethylene and diethylene glycol.

Hexylene glycol is included in the above solution to ensure that the solution is at resistant to low temperatures. It is obvious to the person skilled in the art that the alcohols mentioned and glycols can equally well be used for this purpose.

In order to more clearly disclose the nature of the present invention, the following are illustrative Examples given. It should be noted that the invention does not apply to that in these examples any specific conditions or details given.

example 1

Machine sieve samples were cut into 16.93 x 19.05 mm pieces, washed with petroleum ether and dried under vacuum. The dry samples were then based on a semi-micro balance

Weighed exactly 0.01 mg and each was ^{immersed in 100 cm 3 of} a solution containing 250 parts per million of a combination of K.alium-2-mercaptobenzthiazoI and the Ν, Ν-dimethylamides of tall oil fatty acids. The analysis of the tall oil fatty acids used to prepare the mixture of Ν, Ν-dimethylamides is given in Table 1. The amounts of potassium 2-mercaptobenzothiazole and Ν, Ν-dimethylamides used as active ingredients were between 100 and 0 parts and 0 and 100 parts, respectively.

Each solution was diluted with an aluminum sulfate or sodium hydroxide solution to a pH of 5.0, 6.5 or 8.0 set. The sieves were kept in the solutions for 15 hours at 40 ° C. At the end At this time the sieves were removed, rinsed with water, air dried and weighed.

The weight changes between the original weights of the sieves and the weights after treatment with the inhibitor solution are listed in Table IT.

Table Il

Weight gain of strips of machine sieves after treatment with solutions containing 250 parts per million of the corrosion inhibitor mixtures

Potassium-2-mercaptobenzothiazole

Ν, Ν-dimethylamides
of tall oil fatty acids

Potassium-2-mercaptobenzothiazole

Ν, Ν-dimethylamides
of tall oil fatty acids

pH 5.0
pH 6.5
pH 8.0

Concentration in the test solutions, parts per million

250
0

225 200 175 150 125 100 75 50 25th 25th 50 75 100 125 150 175 200 225

Part in that part of the test solution that consists of the active ingredients

100
0

0.82
0.34
0.23

90 80 70 60 50 40 30th 20th 10 10 20th 30th 40 50 60 70 80 90

Weight gain in mg

0.67 1.35 4.71 5.95 6.76 4.83 0.21 0.24 0.96 0.72 1.96 4.08 4.61 6.24 4.39 4.80 1.55 1.20 1.10 3.45 5.88 7.55 9.70 4.11 3.66 2.64 2.06

These results show that potassium 2-mercaptobenzothiazole or the Ν, Ν-dimethylamides of tall oil fatty acids, when used separately, the Sieve samples are much less effective than mixtures, which are mixtures of the two materials, in coating sieve samples contain. In particular, these results show that the solutions containing 20 to 80 parts of potassium-2-mercaptobenzothiazole and contained 20 to 80 parts of the Ν, Ν-dimethylamides of tall oil fatty acids, the sieves very much effectively provided with protective coatings. Solutions containing 40 to 60 parts of potassium-2-mercaptobenzothiazole and Containing 40 to 60 parts of the Ν, Ν-dimethylamides of tall oil fatty acids gave the sieves the most potent Protective covers.

Examples 2 to 4

In each of these examples, the procedure of Example 1 was repeated except that in Examples 2, 3 and 4 N, N-dimethyloleic acid amide, N, N-dimethylamides of linseed oil fatty acids or Ν, Ν-dimethyllinoleic acid amide was used. the Results were similar to those obtained in Example 1.

The linseed oil fatty acids used to prepare the mixture of Ν, Ν-dimethylamides used in Example 3 used contained 6% palmitic acid, 4% stearic acid, 22% oleic acid, 17% linoleic acid and 51% linolenic acid.

Example 5

The same procedure as in Example 1 was carried out with mixtures containing potassium-2-mercaptobenzothiazole and the Ν, Ν-dimethylamides of spermacetic oil fatty acids. The one used to make the amide mixture Spermacetic oil fatty acids used contained 8% oleic acid, 12% arachidonic acid and 80% Erucic acid.

The results were not similar to those obtained in Example 1. With potassium-2-mercaptobenzothiazole very little protective coating was obtained, but the amount of coating increased as it increased Concentration of the dimethylamide too, so that the mixture with 90 parts of Ν, Ν-dimethylamides of Spermacetic oil fatty acids and 10 parts potassium-2-mercaptobenzothiazole yielded the greatest amount of protective coating. The Ν, Ν-dimethylamides alone also gave a significant amount of protective coating.

Example 6

In this example, sieve samples, as described in Examples 1 to 4, were treated with the same combinations and amounts of potassium-2-mercaptobenzothiazole and Ν, Ν-dimethylamides of tall oil fatty acids, oleic acid, linseed oil fatty acids and linoleic acid. The sieves were then contained in 100 cm ³ of a sodium hydrosulfide solution containing 3 parts per million of sulphide and was either adjusted with aluminum sulphate or sodium hydroxide to a pH value of 5.0, 6.5 or 8.0, placed. The samples were held at 40 ° C. for 15 hours, removed from the solution, rinsed with water, dried and examined to determine the extent to which a dark color had occurred. The sieves that had been treated with the dimethylamides alone had become strongly dark in color at all three pH values. The sieves that had been treated with the potassium-2-mercaptobenzothiazole alone were less darkly colored, but those that had been treated with the combination

i 246 358

ίο

Nations of the two materials had been treated were only slightly dark in color, which indicated that the strongest protection against sulphide had been obtained.

Example 7

The effectiveness of the mixtures according to the invention in preventing the corrosion of steel was determined determined by the weight loss of a steel test sample that is corrosive in the presence of the inhibitor mixture Conditions with the weight loss of a similar steel test sample to the subjected to the same corrosive conditions in the absence of the inhibitor became.

The following test procedure was used: Dry bottles for soft drinks were each ^{filled with 185 cm 3 of} fresh salt solution which had been obtained from a spring well immediately before use. During the filling of the saline solution into the bottle, the saline solution was kept under a nitrogen blanket to prevent contact with air. Various amounts of the corrosion inhibitor mixture were then added to the bottles to give concentrations of 0.6 and 12 parts per million of the inhibitors made up of approximately equal parts by weight of chew-2-mercaptobenzothiazole and N, N-dimethylamides of tall oil fatty acids. A 12.70 x 184.15 x 0.635 mm sample of steel washer material, cleaned and weighed, was then placed in each bottle and each bottle was sealed with a new cap. The bottles were then mounted on a wheel so that the bottoms of the bottles were on the circumference with the caps facing the center of the wheel.

After all of the bottles were mounted on the wheel, the whole device became one Brought air oven held at 32.2 ° C. The wheel was turned on for a period of 24 hours rotated. The metal samples were removed from the bottles, cleaned, and weighed to remove the Determine weight loss.

The inhibitor mixture protected the steel samples to a considerable extent. Your effectiveness was comparable to that obtained with such widely used corrosion inhibitors, such as long chain amines and diamines and imidazolines. In addition, the mixtures the alkali metal salts of 2-mercaptobenzothiazole and Ν, Ν-dimethylamides of long-chain unsaturated Compared to the commonly used corrosion inhibitors, carboxylic acids contain more desirable properties. For example, amines and diamines are very reactive compounds, and they are with many other materials that are found in industrial systems that Corrosion protection require, occur, incompatible. The ring structure of imidazolines is made by Split alkalis. In comparison, the mixtures according to the invention are stable and proportionate not very responsive.

The Ν, Ν-dimethylamides mentioned in the examples can by means of the usual in the literature described method are produced. In this synthesis process, fatty acids are through Effects of phosphorus trichloride, phosphorus pentachloride or thionyl chloride converted into acyl chlorides. The acyl chlorides are then reacted with dimethylamine to form the amides. At a In other methods, fatty acids are heated to approximately 93 ° C and an excess of dimethylamine is left bubble through the reaction vessel. Excess amine and that formed by the reaction Water is removed by distillation and the process continued until the reaction is complete The dimethylamides can be purified by fractional distillation, but it is not required when the products are used as corrosion inhibitors in the manner described here.

The dimethylamides of shorter-chain saturated acids are liquids and could be used in combination can be used with alkali metal salts of 2-mercaptobenzothiazole. Those made from these acids However, amides do not provide the same degree of protection as those from the unsaturated acids 18 carbon atoms produced amides. [Saturated acids with chain lengths of up to 22 carbon atoms can also be used, but their amides are not as effective as the preferred Amides. Furthermore, the amides produced from the longer-chain saturated acids are solid and therefore difficult to set.

Amines other than dimethylamine can be used by means of the methods described above Manufacture amides of fatty acids. In this way from primary and longer-chain secondary dialkylamines produced amides are not as effective as the Ν, Ν-dimethylamides used according to the invention, when used as one of the components of the corrosion inhibitor mixture.

While particular embodiments of the invention have been described, it will be understood of course, the invention is not limited to these as many modifications are made can. When the inhibitor mixtures of the invention are used in water flush systems it may be advisable to use these mixtures in conjunction with a bactericide. For more information on the use of bactericides in treating water flushing water for secondary recovery, reference is made to U.S. Pat. No. 2,839,467 and in references cited in this patent with regard to this subject matter. Other Uses for the corrosion inhibitor according to the invention are readily apparent to those skilled in the art.

Claims (11)

Patent claims: 1. Corrosion-preventing mixture for copper, copper alloys and ferrous metals, the surfaces of which come into contact with aqueous solution, characterized by a content of 20 to 80 parts of an alkali metal salt of 2- mercapto hiazole and 20 to 80 parts of a Ν, Ν-dimethylamide of a straight chain Carboxylic acid containing "18 carbon atoms and at least one carbon-carbon double bond. 2. Mixture according to claim 1, characterized by a content of 40 to 60 parts of an alkali metal salt of 2-mercaptobenzothiazole and 40 to 60 parts of a Ν, Ν-dimethylamide of a straight chain Carboxylic acid that has 18 carbon atoms and at least one carbon-carbon double bond contains. 709 619/67 ' 3. Mixture according to claim 1, characterized in that it takes the place of the straight-chain carboxylic acid a mixture of straight-chain carboxylic acids containing 18 carbon atoms and at least have a carbon-carbon double bond, contains. 4. Mixture according to claim 1, characterized in that the carboxylic acid is a Mixture of acids derived from tall oil. 5. Mixture according to claim 1, characterized in that the carboxylic acid is a mixture of Linseed oil is derived from acids. 6. Mixture according to claim 1, characterized in that that the Ν, Ν-dimethylamide N, N-dimethyloleic acid amide is. 7. Mixture according to claim 1, characterized in that the Ν, Ν-dimethylamide N, N-dimethyllinoleic acid amide is. 8. Mixture according to claim 1, characterized in that the Ν, Ν-dimethylamide N, N-dimethyllinolenic acid amide is. 9. Mixture according to claims 1 to 3, characterized in that it is divided into 30 to 60 parts an inert solvent is dissolved. 10. Mixture according to claim 9, characterized in that the inert solvent consists of about 30 parts of water and about 10 parts of hexylene glycol. 11. Use of the mixture according to claims 1 to 3 in amounts of at least 0.5 parts per million parts of the aqueous solution with consisting of copper or copper alloys Screening of paper machines comes into contact. Considered publications:
U.S. Patent No. 1,750,651.