DE4118895A1 - Corrosion protecting agent for metals (alloys) - comprises polymeric quat. ammonium borate obtd. by reacting amine(s) with ethylene-oxide or propylene oxide and boric acid - Google Patents

Abstract

A corrosion protection agent (I) for metals (alloys) comprises polymeric quat. ammonium borate obtd. by simultaneously reacting amines of formula (II) and (III) with 2-20 (3-10) mol. ethylene or propylene oxide and 0.6-1.5 (1) mol. boric acid, boric acid esters or boric acid salts (each per mol. N-equiv.). In the formulae R1 = 8-22C alkyl or alkenyl; or when R2 and R3 = -(C2H4O)xH or -(C3H6O)xH, R1 = 1-4C alkyl; R2 = H, 1-22C alkyl, -(C2H4O)xH, -(C3H6O)xH or -CH2CH2CH2NH2; R3 = H, -(C2H4O)xH, -(C3H6O)xH or -CH2CH2CH2NH2; R4 and R6 = 1-4C alkyl, -(C2H4O)xH or -(C3H6O)xH; R5 and R7 = -(C2H4O)xH, -(C3H6O)xH; A = -(CH2)n-, -(CH2CH2OCH2CH2)n- or -(CH2CH2NHCH2CH2) x = 1-55; and z = 1-20. The growth of microorganisms in aq. systems is suppressed without being toxic to the water. USE - (I) are used in corrosion coating materials, in the prodn. of a temporary corrosion protecting film, and as coolants, cooling lubricants, borehole flushing fluids, cutting fluids, rolling fluids, hydraulic fluids, heat transfer media and as an additive to wood protection agents. (6pp Dwg.No.0/0)

Description

The present invention relates to a water-miscible Corrosion inhibitor for surfaces of Ferrous metals and their alloys and others endangered metals such as copper, zinc or aluminum, which are in contact with corrosive media or can come.

In particular, the invention relates to a Corrosion inhibitor for use in Cooling circuits, heat exchangers, in drilling, cutting and rolling fluids, but also in protective coatings or corrosion-inhibiting coatings.

In technical processes arising in the presence of Water or other corrosive substances play always raises the problem of Corrosion protection, when metals susceptible to corrosion, such as iron, aluminum, zinc, copper or their Alloys, for example by cleaning processes,  Cooling water, coolants, hydraulic fluids and other functional solutions and emulsions be claimed.

Many different means are known in the Contact media or paints or coatings on Protecting metals or inhibiting corrosion Act. These include nitrites, zinc salts, organic Chromates, silazanes, cationic wetting agents, ketenes, Phenol or benzene derivatives, various amines, amides, Imines, quaternary ammonium salts, unsaturated alcohols, Phosphoric acid derivatives, boric acid and their esters.

All of these compounds have their disadvantages Use does not always justify.

In tapping systems, these are often deficient chemical Stability and incompatibility or lack of Miscibility with the paint system, whereby its Liability may be affected. In addition, the anyway low concentration due to partial degradation too lead faster inefficiency.

In aqueous systems, many of these agents can be used not in the targeted low concentrations use. Some are also due to their toxicity can not be used in aqueous systems. This is true z. For nitrites that are toxic, are polluting and carcinogenic with amines Form nitrosamines. Zinc salts are allowed due to Water pollution regulations only in very small Concentrate into the waters. same for for chromates.  

A common problem with technical Applications of aqueous solutions is the infestation with Micro-organisms that form undesirable deposits, cause unpleasant odors, form toxic gases and lead to microbial corrosion and possibly the Can reduce anti-corrosion agents.

Usually, this risk is due to the addition of Biocides are prevented or biocides are needed dosed or at regular intervals as Shock treatment used. This highly effective Biocides, for example phenols, chlorinated phenols, Heterocycles, chlorinated heterocycles, glutaric dialdehyde, fat-soluble amines and formaldehyde-releasing condensates however, endanger the health of the Operators, when dealing with these substances in Touch comes. This is particularly blatant Problem with cooling lubricants in the Metalworking, where the operator in close Contact with the fluids works.

It is therefore an object of the invention, a To provide corrosion inhibitors, the on the one hand its effectiveness in protective coatings as well unfolds as in aqueous and organic media such as z. B. in cooling circuits, heat transfer or Coolants, on the other hand, but also a shows sufficient biocidal activity, so that in aqueous Suppresses the growth of microorganisms without being toxic and endangering water.

The solution of the problem is carried out by an agent according to of claims 1 to 6 and its use according to the Claims 7 to 17.

It has been found that polymeric quaternary ammonium borates whose preparation has been described in DE 38 27 721 A1, dissolved in water, as microemulsions or as Component in protective coatings very good show anti-corrosive properties and the best meet the demands made. In addition to one good biocidal effect, it adheres well to metallic Surfaces and is used directly from the Media deposited.

Advantageously, the excellent effect Creep of these compounds Made of metal surfaces, which also uneven surfaces and Seam well protected and pitting avoided can.

The compounds mentioned are capable of corrosion metallic materials in the acidic, neutral and to effectively inhibit weakly alkaline region, the protective effect being particularly in flowing, neutral aqueous media is independent of whether Oxygen is dissolved or not.

In organic solvents are dissolved Ammonium borates according to the invention in the temporary Corrosion protection of iron and steel semi-finished products Can be used as it easily for further processing can be removed.

Incorporated in paint or paint formulations They as permanent corrosion inhibitors.

The universal applicability of these borates is especially surprising, as salt-like quaternary  Ammonium borates prepared by reacting a quaternary ammonium compound with boric acid or a Borate, although usable, but serious Disadvantages show, for. B. they adhere to relatively weak Metal, are water polluting and to some extent plant toxic.

Polymeric used according to the invention quaternary Ammonium borates by reaction of ethylene oxide or propylene oxide with secondary amines and boric acid are preserved, however, with water and certain organic solvents in any ratio miscible, and these solutions or microemulsions show on metals the effects described above. Surprisingly, these are also biocidal Boron compounds in dilution readily biodegradable and very easily remove adsorptively from waste water.

The polymeric quaternary ammonium borates are obtained by simultaneous reaction of amines of general formulas I or II

with 2 to 20, preferably 3 to 10, moles of ethylene or Propylene oxide and 0.6 to 1.5, preferably 1 mol Boric acid, boric acid esters or boric acid salts, each per mole of nitrogen equivalent, wherein

R¹ is C₈-C₂₂-alkyl or C₈-C₂₂-alkenyl or, when R² and R³ are groups of the formula - (C₂H₄O) _x H or - (C₃H₆O) _x H, R¹ can also be C₁ also C₁-C₄-alkyl,
R² is hydrogen, C₁-C₂₂-alkyl or a group of the formulas - (C₂H₄O) _x H, - (C₃H₆O) _x H or -CH₂CH₂CH₂NH₂,
R³ is hydrogen or a group of the formulas - (C₂H₄O) _x H, - (C₃H₆O) _x H or -CH₂CH₂CH₂NH₂,
R⁴ and R⁶ are C₁-C₄-alkyl or a group of the formula - (C₂H₄O) _x H or - (C₃H₆O) _x ,
R⁵ and R⁷ is a group of the formula - (C₂H₄O) _x H or - (C₃H₆O) _x H,
A is a group of the formulas - (CH₂) _n -, - (CH₂CH₂OCH₂CH₂) _n - or - (CH₂CH₂NHCH₂CH₂) _n ,
x are numbers from 1 to 55 and n is an integer from 1 to 20.

As amines of the above formulas, the following are preferred:

• 1. Amines of the formula I, wherein R¹ is C₈-C₂₂-alkyl, R² is C₈-C₂₂-alkyl or C₁-C₄-alkyl and R³ is hydrogen or a group of the formula - (C₂H₄O) _x H or - (C₃H₆O) _x H.
• 2. Amines of the formula I, wherein R¹ is C₈-C₂₂-alkyl and R² and R³ is hydrogen.  
• 3. Amines of the formula I, wherein R¹ is C₁-C₄-alkyl or C₈-C₂₂-alkyl and R² and R³ are groups of the formulas - (C₂H₄O) _x H or - (C₃H₆O) _x H, where the sum of the ethylene oxide groups in both radicals R² and R³ is 2 to 20.
• 4. Amines of the formula I, wherein R¹ is C₈-C₂₂-alkyl, R² Hydrogen or a group of the formula -CH₂CH₂CH₂NH₂ and R³ is a group of the formula Mean -CH₂CH₂CH₂NH₂.
• 5. amines of formula II, wherein A, R⁴, R⁵, R⁶ and R⁷ have the meanings given above and wherein the sum of all ethylene oxide groups 4 to 30 is.

In the case of the alkylene oxide groups of the formulas - (C ₂ H ₄ O) _x H and - (C ₃ H ₆ ) _x H, the group of the formula - (C ₂ H ₄ O) _x H is preferred. Instead of the pure polyoxethylene and polyoxpropylene groups, it is also possible for those radicals which are composed of both ethylene oxide and propylene oxide units to be present.

The reaction of the amines with the boric acid and the Alkylene oxide takes place in such a way that in one Autoclave the respective amine and the boric acid submitted and the alkylene oxide is added. The Reaction temperature is generally 60 to 130 ° C, preferably 60 to 125 ° C, in particular 60 up to 100 ° C. The reaction pressure is 50 to 600 kPa. The addition of the alkylene oxide among these Reaction conditions occur over a period of 1  up to 5 hours. For post-reaction, the mixture is at the specified pressure for 3 to 12 hours on one Temperature of 70 to 120 ° C, preferably 70 to Kept at 100 ° C.

Instead of boric acid and its esters, such as z. B. Trimethylborsäureester, or their salts, For example, be used Na-borate. In the Reaction arise as by-products water and Polyglycols.

The obtained polymeric quaternary Ammonium compounds essentially contain as Structural feature Groups of the formula

or groups of the formula

when the reaction was made with ethylene oxide.

The presence of polymeric or oligomeric quaternary Ammonium borate arises already from the fact that in the Reaction between amines of formulas I and II with Boric acid and alkylene oxide water is formed.  

The polymeric quaternary ammonium borates can with Water to be diluted; they are well soluble in Glycols, glycol ethers, ethers, lower alcohols or in mixtures of these solvents with chloroform or methylene chloride. The viscosity is between 1 and 100 Pas, but can in individual cases up to 300 Pas rich. The viscosity of the polymeric quaternary Ammonium borate is dependent on the Reaction temperature, higher reaction temperatures lead to lower viscosities.

After completion of the reaction, the obtained Crude solution of the polymeric quaternary ammonium borates without further purification and workup as a concentrate directly or together with others known per se Additives used as corrosion inhibitor become.

A removal of the by-products is possible in the However, practice is often unnecessary. The removal of the Glycols are especially unnecessary if at the same time Frost protection is desirable or glycols themselves serve as a heat transfer medium.

The polymeric quaternaries used according to the invention Ammonium borates can be diluted with water as desired, whereby stable microemulsions can form. you are miscible with cationic surfactants and can used together with these in aqueous solutions become.

Aqueous solutions of the polymers according to the invention Quaternary ammonium borates are acidic, but neutral stable even in a weakly basic environment.  

Preferably, solutions having a pH of 0 until about 9 used.

Good corrosion protection is achieved when used liquids about 1 wt .-% polymers containing quaternary ammonium borates. Can be used until to 10% by weight. Preferably, with concentrations of 3 to 5 wt .-% worked, which has the advantage that on Places where the protective film has detached, Immediately by excess dissolved borates make a new movie. This applies to both aqueous as well as for organic solutions. It is advisable however, in solutions that are corrosive Ingredients, such. As glycol, higher Use concentrations.

The advantageous corrosion protection effect comes Surprisingly, by mixing the Borates according to the invention to chromium-free but corrosive Wood preservatives, the aminic compounds included. The production of such Wood preservative is particularly difficult as the used mixing vessel are heavily attacked. By adding the borates according to the invention is the Corrosiveness of such wood preservatives strong reduced.

Together with commonly used fillers, Pigments, adhesives and solubilizers may be the Borates according to the invention also in protective paint systems which are used as binders in general contain usual resins.  

Show good anti-corrosive properties Paint formulations containing about 1 to 10% by weight contain polymeric quaternary ammonium borates. Preferably used are paints with 3 to 5 wt .-% borate and a binder content of up to about 40% by weight. These paintings show after the Dry a very good anti-corrosive effect, but also a smooth surface that works well if needed can be provided with a final coat.

The following examples serve for further explanation of the invention, without them on this to limit.

Examples example 1

2 mm thick steel (120 x 50 mm) test plates (ST 13, Material number. 1033.3 according to DIN 1623 part 1) are with Toluol carefully degreased and weighed. The sample sheets are placed in suitable containers so that they with the edge on a lower edge of the container and with the top edge at the opposite Container side surface abut.

Subsequently, corrosion inhibitors containing Solutions or comparison solutions filled up so that the Sheets up to about 1.5 cm below the upper edge are covered. After 7, 14 and 28 days, the Corrosion protection assessed. To this end the sheets are rinsed under running water,  and possibly adhering corrosion products with diluted hydrochloric acid removed at room temperature. After the sheets are again treated with toluene and they are weighed and weighed assessed.

To determine the corrosion protection effect, only the Area taken into account throughout the whole Duration of the experiment was wetted.

Each 6 plates were with the following solutions examined:

• a) 0.1% polymeric quaternary ammonium borate (according to Example 1 of DE 38 27 721 A1) in H ₂ O least.
• b) 1% polymeric quaternary ammonium borate (according to Example 1 of DE 38 27 721 A1) in H ₂ O least.
• c) 5% polymeric quaternary ammonium borate (according to Example 1 of DE 38 27 721 A1) in H ₂ O least.
• d) desalted water having a pH of 6 to 7.

After 28 days showed up on the tested sheets following results:

Example 2

Made up of the following components Anti-corrosive paints made:

a. polymeric quaternary ammonium borate | 5% Medium-chain alkyd resin 36% talcum 15% Iron oxide powder (red) 7% titanium oxide 4% Bentone 1.1% dry mix 1.2% white spirit 30.7%

• b. For comparison, a paint was prepared, in the polymeric quaternary ammonium borate was omitted.

6 sheets each as used in Example 1 got a thin coat and were after the Dry in container with deionized water (pH 6 to 7) posed.

After 3 months, the sheets showed with paintings that contained polymeric quaternary ammonium borate (Formulation a.), A smooth paint surface. On all sheets with coatings without additive (formulation b.) bubbles and cracks had formed, under which rust had settled.

Claims (18)

1. anticorrosion agent for metals or metal alloys, characterized in that it contains polymeric quaternary ammonium borate, which is obtained by simultaneous reaction of amines of the general formulas I or II with from 2 to 20, preferably from 3 to 10, moles of ethylene or propylene oxide and from 0.6 to 1.5, preferably 1 mole of boric acid, boric acid esters or salts of boric acid, each per mole of nitrogen equivalent, wherein R¹ is C₈-C₂₂-alkyl or C₈-C₂₂- Alkenyl or, when R 2 and R 3 represent groups of the formula - (C₂H₄O) _x H or - (C₃H₆O) _x H, R 1 may also be C₁-C₄-alkyl,
R² is hydrogen, C₁-C₂₂-alkyl or a group of the formulas - (C₂H₄O) _x H, - (C₃H₆O) _x H or -CH₂CH₂CH₂NH₂,
R³ is hydrogen or a group of the formulas - (C₂H₄O) _x H, - (C₃H₆O) _x H or -CH₂CH₂CH₂NH₂,
R⁴ and R⁶ are C₁-C₄-alkyl or a group of the formula - (C₂H₄O) _x H or - (C₂H₆O) _x H,
R⁵ and R⁷ is a group of the formula - (C₂H₄O) _x H or - (C₃H₆O) _x H, A is a group of the formulas - (CH₂) _n -, - (CH₂CH₂OCH₂CH₂) _n - or - (CH₂CH₂NHCH₂CH₂) _n ,
x are numbers from 1 to 55 and n is an integer from 1 to 20. 2. Composition according to claim 1, characterized that it is dissolved in water. 3. Composition according to claim 1, characterized that it is dissolved in organic media. 4. Composition according to claims 1 to 3, characterized characterized in that it additionally has other general usual additives such. Biocides, surfactants, Contains antifoam. 5. Composition according to claims 1, 2 and 4, characterized characterized in that it contains polyols.   6. Composition according to claims 1, 3 and 4, characterized characterized in that it contains glycol. 7. Composition according to claims 1 to 6, characterized characterized in that it is polymeric, quaternary Ammonium borate in a concentration of 1 to Contains 10 wt .-%. 8. Composition according to claims 1 to 6, characterized characterized in that it is polymeric, quaternary Ammonium borate in a concentration of preferably 3 to 5 wt .-%. 9. Use of the agents according to claims 1 to 8 in corrosion coatings. 10. Use of the agents according to claims 1, 3, 4, 7 and 8 for making a temporary Corrosion protection film. 11. Use of the agent according to claim 10 as Coolant. 12. Use of the agent according to claim 10 as Coolants. 13. Use of the agent according to claim 10 as Drilling fluid. 14. Use of the agent according to claim 10 as Cutting fluid. 15. Use of the agent according to claim 10 as Rolling liquid.   16. Use of the agent according to claim 10 as Hydraulic fluid. 17. Use of the agent according to claim 10 as Heat exchange fluid. 18. Use of the agents according to claims 1 to 8 as an additive to corrosive acting Wood preservatives.