DD218636A5 - CORROSION INHIBITING WATER ACCOMPANIMENTS AND METHOD FOR THE PRODUCTION THEREOF - Google Patents

Abstract

The invention relates to corrosion-inhibiting water additives and a process for their preparation. The inventive water additives contain as active ingredient organic phosphates of the general formula IR1R1 N2 H3 nPO4 (I) R2R2 N2 and zinc phosphate. In the general formula (I), R 1 represents hydrogen or cyclohexyl group, R 2 represents cyclohexyl group and has a value of 0.5 to 3. The water additives of the present invention are prepared by reacting 5 to 85% phosphoric acid with cyclohexylamine or dicyclohexylamine and adding to the mixture before or after the conversion to the organic phosphate, at most 10% of zinc phosphate or a zinc compound forming zinc phosphate with phosphoric acid is added. The inventive corrosion-inhibiting water additives can be used in cold water and hot water Kuehlkreislaeufen to reduce the corrosion rate.

Description

". Berlin, 27. 9. 1984 AP C 23 A / 263 215 2 64 000 11

Corrosion inhibiting water additives and process for their preparation

Field of application of the invention

The invention relates to corrosion-inhibiting water additives and a process for their preparation. The water additives according to the invention are used in cold water and hot water cooling circuits for reducing the corrosion rate.

Characteristic of the known technical solutions

It is known that the corrosion of metals in aqueous solutions in the majority of cases is essentially an electrochemical process, the speed of which depends on the velocity of two reactions occurring at the surface of the metal and coupled to each other: that of the anodic reaction in which Course that the ion atoms of the metal emerge from the lattice and go into solution with the release of electrons, and that of the cathodic reaction in which a depolarizer binds the electrons released in the anodic reaction (Rozenfeld: A korrozio inhibitorai, Muzzaki Könyvkiado, Budapest 1981). ,

It is also known that in comparison with the other methods of corrosion protection, for example the use of corrosion resistant materials, modification of the corrosion load, use of protective coatings and sheaths, active protection methods (Kovacs Klara: KorrSzios alapfogalmak * Müszaki könyvkiado, Budapest 1965), corrosive

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protection by means of inhibitors has the advantage of simplicity and low costs.

The cycle of corrosion must be closed so that it can be closed, ie chemicals which, when added to the water, stop the anodic reaction, at the same time inhibit corrosion or agents which reduce the rate of the cathodic reaction. also reduce the rate of corrosion "Accordingly, one basically distinguishes .Anodeninhibitoren and cathode inhibitors · The third group, the inhibitors is formed by the organic films, the. Both processes inhibit (Kammer, Prank .: The UAIC Water Handbook, McGraw-Hill, Inc., T979).

· Chromate and orthophosphate are the most effective of the anodic inhibitors · The application of chromate is limited by aspects of environmental protection, inhibiting the use of orthophosphate, that possibly dicalcium phosphate can deposit and worsen the heat transfer · In the case of pure anodine inhibitors Corrosion rate also depends on the concentration of the inhibitor: if the concentration falls below a critical value, the corrosion rate is not reduced by the inhibitor, but increased ·

The cathode inhibitors - for example, polyphosphonates, zinc - do not have such problems, but their corrosion rate lowering effect is less than that of the anode inhibitors. The organic film formers, generally long carbon chain amines, form a film on the surface of the metal Thus, between water and metal a dynamic obstacle that inhibits the corrosion processes · The film formers have the

Disadvantage that "with the formation of a small ice in the film, the corrosion attacks concentrated on the unprotected place where it quickly destroys the metal (pitting).

In order to increase the effectiveness of the individual inhibitors, combinations of inhibitors of different types are frequently used lately, mixtures having a synergistic effect are sought (Betz: Handbook of Industrial Water Conditioning, 1976, and KURIZET S-207, 'Prospectus).

ι.

Object of the invention

The aim of the invention is to provide new corrosion-inhibiting water additives which can be prepared in a simple and economical manner and which have a stronger inhibiting effect than known additives. .--

Explanation of the essence of the invention

The invention has for its object to find compounds that have a stronger korrosionsinhibier.ende effect than the known means.

According to the invention contain the new corrosion-inhibiting water additives as the active ingredient organic phosphates of the general formula I.

^H 3-n ^PO 4

A ':

and zinc phosphate. In the general formula I stand

R, j is hydrogen or cyclohexyl group, -Rg is cyclohezyl group and

η for a value of 0.5 to 3,

The water additives according to the invention can be used in cold water and hot water cooling circuits for reducing the corrosion rate.

The inhibiting water additives according to the present invention do not have the disadvantages of the individual types of inhibitors. They can be made from easily accessible materials with a simple process and cheap. be presented. Their corrosion-inhibiting effect reaches or exceeds that of the known commercially available agents, d. H. the inhibitors according to the invention are optimal under the aspect of "cost / effectiveness"

By taking place in a manner known per se application of the invention, inhibiting water additives' in cold water and hot water cooling circuits, a safe, highly effective corrosion protection can be achieved.

According to the invention, the organic phosphates of general formula I are prepared in a simple chemical reaction by adding cyclohexylamine or dicyclohexylamine to 5 to 85% strength phosphoric acid with constant stirring and cooling. Depending on the concentration of the phosphoric acid, the organic compounds Pho spho!) / Compounds of the general formula I in the pure state or in the form of an aqueous solution.The excellently effective water additives according to the invention are obtained by reacting the organic phosphate of the general formula I.

not more than 10 % zinc phosphate added. The zinc can also be introduced by dissolving zinc oxide in the phosphoric acid in the first step and then adding cyclohexylamine or dicyclohexylamine to the resulting solution.

In contrast to the known water treatment agents, the water additives according to the invention contain C yelohexy1 amine or dicyclohexylamine phosphate. The use of these compounds in the field of corrosion protection is not yet known "Their combination with zinc phosphate must be considered as new · * ....".

The corrosion-inhibiting water additives according to the invention have the following advantages:

they inhibit corrosion by all three mechanisms of inhibition: anodic (phosphate), cathodic (zinc), and pilmic (cyclohexyl or dicyclohexylamine), thereby providing the highest possible safety,

they inhibit the corrosion process even at high water temperature,

they can be produced in a simple manner by means of devices customary in the chemical industry (autoclave),

- as a result of their simple manufacture, they are cheaper than agents which offer a similar protective effect,

they have a neutral or almost neutral character and therefore hardly influence the pH of the treated water,

they do not contain environmentally damaging chromate,

- in comparison, with a similar one. Protective agent providing phosphate-containing agents only a lower concentration of phosphate in the water needs to be maintained,

- in comparison with a similar ¹ Schutzwirlcung offered zinciferous means only a lower zinc concentration is required in the treated water,

in contrast to the known phosphorus-containing agents, the addition of inhibitors of the inhibition of tricalcium phosphate is either not at all or only to a much lesser extent necessary,

- possible contamination of the water with copper (II) ions does not diminish the effectiveness of the water additives according to the invention,

' Embodiment

The invention will be explained in more detail with reference to the following examples.

Example 1 '.

474 liters of ion-free water are placed in a double-walled, enameled, autoclave equipped with a stirrer. 234 liters of 85% strength phosphoric acid are added thereto. 58 g of zinc oxide are dissolved in the acid with stirring. 86.2 kg of dicyclohezylamine are added to the solution at about 90 kg / h with continuous stirring and with water cooling turned on. After the addition has ended, the mixture is stirred for a further 10 minutes and then drawn off into barrels (expediently in barrels made of plastic) ·

Characteristics of the product:

pH: 7 to 8

Density: 1.04 g / cm ³ at 20 ^° C.

Composition: Zinc 70 to 90 mg / kg

Phosphate 52 to 56 g / kg dicyclohexylamine · 140 to 150 g / kg

Example 2

In a beaker of 100 cm.sup.r volume, 0.01 g of zinc oxide is dissolved in 56.7 g of 85% strength phosphoric acid. In a 2-liter glass beaker, 40.8 g of cyclohexylamine are dissolved in 903 g of distilled water. The zinc oxide-containing phosphoric acid is then allowed to flow slowly into the amine solution with constant stirring, within about 10 minutes.

Parameters of the product obtained:

Color: colorless or pale yellow.

pH value: 4 to 5

Density: 1.03 g / cm ³ at 20 ^° C.

Composition: Zinc 7 to 9 mg / 1

Phosphate, 46 to 50 g / l Cyclohexylamine 40 to 44 g / l

Example 3

0.97 mg of zinc oxide are dissolved in 1.97 g of 85% phosphoric acid. * This solution is added to 4.5 g of dicyclohexylamine with vigorous stirring. «

Parameters of the product obtained:

pH: 7 to 8, in 20% aqueous solution Appearance: white, crystalline substance

Composition: Zinc 0.0035 to 0.0040 %

Phosphate 25 to 27 % dicyclohexylamine 68 to 71 % water 4 to 6 %

Example 4

612 liters of ion-free water are added to a double-walled stirrer-enamelled autoclave of 1 liter volume. 47.8 liters of 85% phosphoric acid are added to the water. With water cooling on and with constant stirring, 99 liters of dicyclohexylamine are added to the water Autoclave given · The product is bottled in barrels.

Parameter of the product:

Color: colorless or pale yellow pH value: 3 to 4.

Density; 1.05 g / cm ³ at 20 ⁰ C.

Composition: zinc . '. 11 to 13 mg / kg

'. ·' :. ' Phosphate 80 to 90 g / kg

Dicyclohexylamine 110 to 120 g / kg

The corrosion-inhibiting effect of the water additives according to the invention was proved with the following experiments:

Trial 1

The effect of pretreatment with the agent prepared according to Example 1 (hereinafter Σ-102) and treatment with the agent prepared according to Example 3 (hereinafter X-100) was compared to the action of some known commercially available agents. The comparative experiments were carried out in the manner known from the relevant literature (Kemmer, Prank H .: The HALCO Water Handbook,

McGraw-Hill, Inc, 1979, and Betz: Handbook of Industrial Water Conditioning, 1976) by comparing Etalon's measured * Corrosion Rate (mm / year) values, and Comparative Relative Inhibitor Activity (relative to the untreated control Value of the corrosion rate in percent). In the case of the known water additives, the concentration specified by the manufacturer was selected for pretreatment and treatment.

Parameters of the experiments:

Duration of the corrosion test 72 hours Temperature of the water 90 ⁰ G Slurry every 24 hours ventilation continuous PH value 7.5 to 8.5

Main parameters of the water used:

Total calcium hardness (in CaCO3) 80 to 100 mg / l

Conductivity, .500 to 600 , uS

Alkalinity (InCaCO ₃ ) "40 to 60 mg / l

Total iron 0.1 to 0.2 mg / 1

Sulfate 140 to 160 mg / l

Chloride 20 to 30 mg / l

Silica 3 to 5 mg / 1

The results are summarized in Table I. It can be seen from the table that the additives according to the invention achieve or exceed the effect of the best commercially available products.

Trial 2

The agent of Example 4 (hereinafter X-10E01) became the continuous treatment and its modified form

(tenfold zinc content) (hereinafter X-1021) used for pretreatment. The results were compared with those of known means. The parameters of the experiment and the quality of the water corresponded to those given in experiment 1. The results are also shown in Table I. The water additives according to the invention achieve or exceed the effect of the known agents.

Trial 3

In this experiment, the agent according to Example 2 (hereinafter X-103) was used for pretreatment and for continuous treatment and compared with the known agents according to Experiment 1. The parameters of the experiment and the quality of the water were the same as in experiment 1. It can be seen from the values given in Table I that the agent X-103 according to the invention offers better corrosion protection than the commercial corrosion inhibitors.

Trial 4 """.

The effect of a pretreatment with the invention 2-1Ö2 (Example 1) and a continuous treatment with the prepared according to Example 3 X-100 was compared with the effect of that agent which had shown the best effect in the experiment (combination of I + II + III) (for meaning of labels see page 13). The investigation extended to lower water temperatures, but the other parameters were similar to those already indicated. ,

The results are summarized in Table II. It can be seen that the erfin'dungsgemäße addition of water at least the corrosion-inhibiting effect of the best commercial means achieved.

Table I

Comparative study of the corrosion-inhibiting effect of various water additives

Pretreatment- cohesive- application search no. Oils mg / 1 medium Concentration- Inhibitory filtration Rate of action % mg / 1 (mm / year)

1 2 I 1000 III PW II 200 3 IV 200 IV 150 4 V 200 V + VI 100 VI 100 5 VII 200 VII 150 6 VIII 100 VIII 30 7 X-102 5000 X-100 150 8th X-1021 5000 X-1001 150 9 X-103 2000 X-103 300

2,203 0.069

0.726 0.194

1.90

1.76

0,068

0.032

0.212

0 97

67 92

14 20 97 99 90

Table II

Comparative study of the corrosion-inhibiting effect of various water additives.

[Try Mr. Pretreatment agent Concentration mg / 1 Treatment medium Concentration mg / 1 Water temperature ⁰ C Corrosion speed mm / year Inhibitor effect % 1 mm 30 0.814 0 2 I 1000 Ill 150 30 0,021 97 II 200 3 X-102 5000 X-100 150 30 0,021 97 4 - - - - 60 1,021 0 5 I 1000 III 150 60 0.024, 98 II 200 6 X-102 5000 X-100 150 60 0.024 98

Meaning of the names in Tables I and II

Polyphosphate zinc salt (3 % Zn), copper inhibitor (brand name: Kurizet S 207, manufacturer: KURITA.)

II ITatrium polyacrylate copolymer (Kurizet T 225, manufacturer: KURITA)

III polyphosphonate, zinc salt, copper inhibitor, phosphate (Kurizet S 611, KURITA)

IV inhibitor mixture of organic and inorganic components, zinc 34 mg / 1, copper 10 mg / 1 phosphate 20 % (Kurizet S 113, KUEITA)

Zinc-containing phosphonate inhibitor, zinc 13%> phosphate 17 % (Tecpractor 657 M, TSCPRO)

TI Organic Inhibitor (Tecpractor 2045, TECPRO)

Phosphate-containing inhibitor gin, 7 % phosphate (Betz 801, manufacturer: Betz)

Till zinc, organic phosphates and phosphonic acids containing agent, zinc 7.3 % _t phosphate 10 % (Drewgarde 187, manufacturer: Drew)

Claims (7)

invention claim ¹ ι 1. corrosion-inhibiting water additives, characterized in that they contain as active ingredient in an amount of 0.1 to 99 » 3%, an organic phosphate of the general formula I. ^{Η 3-η} ΓΟ 4 wherein RJ is hydrogen or cyclohexyl, R _{2 is} cyclohexyl and η is from 0.5 to 3, furthermore, at most 10 % of zinc phosphate and the solvents customary for such additives, preferably on the organic phosphate; Water, included · 2. Water additives according to item 1, characterized in that they contain as active ingredient as substituents R ^ a cyclohexyl group-carrying organic phosphates of the general formula I, 3 · Water additives according to item!, Characterized in that they contain as active ingredient as substituents R ₁ hydrogen-containing organic phosphates of the general formula I · 4. A process for the preparation of the corrosion-inhibiting 7 / asserzusätze according to one of the items 1 to 3, characterized in that reacting 5 to 85 % lge phosphoric acid with cyclohexylamine or dicyclohexylamine. 15 ' 5 # Method according to item 4, characterized in that the one reagent is continuously introduced into the other with constant stirring and cooling. 6. The method according to item 4 or 5, characterized in that the reaction mixture before, during or after the reaction based on the organic phosphate at most 10 % zinc phosphate or a phosphoric acid zinc phosphate-forming zinc compound added, Method according to one of the items 4 to 6, characterized in that the reaction is carried out without solvent or in an inert solvent, preferably water.