MX2008006577A - Corrosion-reducing composition and use thereof - Google Patents

Abstract

The invention relates to a composition which comprises at least one liquefying agent for a hydraulic composition and at least one aminoalcohol, selected from the group consisting of 2-amino-2-methyl-1-propanol and N-aminopropyl-monomethyl ethanolamine. The invention also relates to the use of said composition for reducing corrosion, especially on steel formwork in precast components or on concrete steel of concrete constructions.

Description

CORROSION REDUCING COMPOSITION AND ITS USE Technical Field The invention relates to the field of corrosion inhibitors in steel, in particular in steel obturators in prefabricated elements or in reinforcing steel for concrete constructions. The invention relates especially to a composition comprising at least one plasticizer for a hydraulic setting composition and at least one amino alcohol selected from the group consisting of 2-amino-2-methyl-1-propanol and N-aminopropylmonomethylethanolamine. Previous Technique Steel shutters are concrete casting molds in which fresh concrete is introduced to produce concrete components, also known as prefabricated elements. After curing the concrete, the steel shutter is normally removed again. Corrosion of the steel obturator represents a major problem and can lead to a reduction in the quality of the concrete, in particular the surface quality of the concrete, and for example, to undesirable traces of oxide in visible concrete. To suppress the oxide, a concrete release agent also known as forming oil, is generally applied to the steel sealant before use. These forming oils have the disadvantage that they only have a limited capacity to suppress corrosion and thus formation of rust and also have to be applied individually to each piece of the steel plug before each use, which is not so economical as it is environmentally contaminating. The use of steel as reinforcement in constructions is wide. Concretes reinforced with steel are of particular importance. The steel is introduced into a hydraulic setting material and reinforces it. Steel is used particularly in elongated form, especially as rods or grids, and is also frequently referred to by those skilled in the art as reinforcing or reinforcing iron. The corrosion of steel present in hydraulic setting materials is of great economic importance. The corrosion of steel inserts reduces their strength and thus the strength of the concrete. Furthermore, corrosion products such as iron oxides or iron oxide hydrates have a higher volume than steel without corrosion. This results in tensions in the concrete that can lead to cracks or separation or detachment of entire pieces. The addition of corrosion inhibitors such as nitrites, amines, alkanolamines, their mixtures with inorganic or organic acids or phosphoric esters to fresh concrete or surface treatment of reinforced concrete with cured steel with a penetrating corrosion inhibitor is known. However, in order to exhibit their action, corrosion inhibitors must be used in large quantities, which can be a disadvantage both from an economic point of view and from an ecological point of view. The use of concrete plasticizers has been known for a long time. For example, it is known from EP 1 138 697 B1 or EP 1 061 089 B1 that (meth) acrylate polymers having ester side chains and, if appropriate, amide, are suitable as a concrete plasticizer. Here, this concrete plasticizer is added as an additive to cement or cement before grinding and leads to a high degree of plasticization or reduction of the water requirement of the concrete or mortar produced therein. Description of the Invention It is therefore an object of the present invention to provide compositions for reducing corrosion, in particular in steel or reinforcing steel seals, which overcome the disadvantages of the prior art. It has now surprisingly been found that a composition comprising at least one plasticizer for a hydraulic setting composition and at least one amino alcohol selected from the group consisting of 2-amino-2-methyl-1-propanol and N-aminopropylmonomethylethanolamine, It is highly convenient to avoid or reduce corrosion in steel shutter or reinforcing steel. further, these compositions have excellent processability and high stability. METHODS OF CARRYING OUT THE INVENTION The present invention relates to a composition comprising or consisting of at least one plasticizer for a hydraulic setting composition and at least one amino alcohol selected from the group consisting of 2-amino-2-methyl-1 - propanol and N-aminopropylmonomethylethanolamine. Particular preference is given to a composition comprising or consisting of at least one plasticizer and 2-amino-2-methyl-1-propanol. N-Aminopropylmonomethylethanolamine is also referred to as 2 - [(3-aminopropyl) methylamino] ethanol (CAS No. 41999-70-6). The amino alcohol at least of the composition according to the invention is 2-amino-2-methyl-1-propanol or N-aminopropylmonomethylethanolamine or a mixture of 2-amino-2-methyl-1-propanol and N-aminopropylmonomethylethanolamine. Possible plasticizers are those that are suitable for plasticizing a hydraulic setting composition or reducing its water requirement. For the purposes of this invention, "plasticizers" include superplasticizers that are often also referred to as fluidizers. In a preferred embodiment, the plasticizer comprises or consists of polycarboxylate, preferably polycarboxylate ether (PCE). The polycarboxylate preferably comprises or consists of at least one polymer A of the formula (I).

Here, the symbols M each represent, independently of each other, H +, an alkali metal ion, alkaline earth metal ion, divalent or trivalent metal ion, ammonium ion or organic ammonium group. Here and then, the term "independently of each other" in each case means that a substituent has different possible meanings in the same molecule. Thus, for example carboxyl groups and sodium carboxylate groups can be simultaneously present in the polymer A of the formula (I), ie the radicals R in this case can be H + and Na + independently of each other. It will be clear to a person skilled in the art that first the group in question is a carboxylate to which the M ion is ligated and second the charge of the polyvalent ions M has to be balanced by counterions. In addition, the substituents R each independently of one another are hydrogen or methyl. This means that the polymer A is a poly (acrylate), poly (methacrylate) or poly ((meth) acrylate) substituted. In addition, the substituents R1 and R2 are each independently of one another, C C2o-alkyl, cycloalkyl, alkylaryl or - [AO] n -R4. Here, A is a C2-C4-alkylene group and R4 is a CrC20-alkyl, cyclohexyl or alkylaryl group, while n is from 2 to 250, in particular from 8 to 200, particularly preferably from 11 to 150.

In addition, each of the substituents R3 are independently of one another, -NH2, -NR5R6, -OR7NR8R9. Here, R5 and R6 are each independently of each other H or a C-C2o-alkyl, cycloalkyl or alkylaryl or aryl group or a hydroxyalkyl group or an acetoxyethyl group (CH3-CO-O-CH2-CH2-) or a group hydroxyisopropyl (HO-CH (CH3) -CH2-) or acetoxyisopropyl (CH3-CO-O-CH (CH3) -CH2-) or R5 and R6 together form a ring in which the nitrogen of -NR5R6 is part, in order of building a morpholine or imidazoline ring. In addition, the substituents R8 and R9 are each independently, a CrC20-alkyl, cycloalkyl, alkylaryl, aryl or hydroxyalkyl group and R7 is a linear or branched C2-C4-alkylene group, in particular C2-C isomers-alkylenes , preferably ethylene, propylene, isopropylene or -C (CH 3) 2 -CH 2 -. Finally, indices a, b, c and d indicate the molar proportions of these structural elements in polymer A of formula (I). These structural elements are present in the proportion of a / b / c / d = (0.05 - 0.9) / (0.05 - 0.9) / (0 - 0.8) / (0 - 0.5), in particular a / b / c / d = (0.1 - 0.9) / (0.1 - 0.9) / (0 - 0.5) / (0 - 0.1), preferably a / b / c / d = (0.1 - 0.9) / (0.1 - 0.9) / (0 - 0.3) / (0 - 0.06), while the sum a + b + c + d = 1. The sum c + d preferably greater than 0. The ratio of polymer A of formula (I) is typically 10 to 100% by weight, in particular from 25 to 50% by weight, based on the weight of the plasticizer. Polymer A can be prepared by free radical polymerization of the respective monomers. or by reaction of polymer analogs of a polycarboxylic acid of the formula (III) In the analogous polymer reaction, the polycarboxylic acid is esterified or amidated by means of alcohols, suitable amines. Details regarding analogous reactions of polymers are described, for example, in EP 1 138 697 B1 on page 7 line 20 to page 8 line 50 and in the examples there or in EP 1 061 089 B1 on page 4, line 54 to page 5 line 38 and in the examples there. In a variant, as described in EP 1 348 729 A1 on page 3 to page 5 in the examples, polymer A can be prepared in the solid state. It has been found that a particularly preferred embodiment of the polymer is one in which c + d > 0, in particular d > 0. As radical R3, -NH-CH2-CH2-OH, in particular, it has been found to be particularly advantageous. These polymers A have a chemically bound ethanolamine that can be separated. Ethanolamine is an extremely efficient corrosion inhibitor. Due to the chemical connection of the corrosion inhibitor, the odor is greatly reduced compared to the case where it is only added by mixing. In addition, it has been found that these A polymers also exhibit significantly greater plasticizing properties. In a further preferred embodiment, the plasticizer of the present composition according to the invention comprises or consists of at least one polysaccharide, vinyl copolymer or at least one sulfonate, preferably based on a lignosulfonate, naphthalene sulfonate or melaminesulfonate. The vinyl copolymer is preferably based on a polyvinyl alcohol or polyvinyl ether. The plasticizer preferably comprises, consists of or is based on Na, Ca or Mg lignosulfonate, Na, Ca or Mg naphthalenesulfonate, Na or Ca melamine sulfonate or a melamine- or a sulfonated naphthalene-formaldehyde condensate. Particular preference is given to Na lignosulfonate or Na naphthalenesulfonate. In a further embodiment, the composition of the invention may contain additional additives, preferably a solvent, in particular water. The composition of the invention is preferably a dispersion, in particular an aqueous dispersion or a solution, in particular an aqueous solution. Suitable solvents are water and organic solvents. The selection is made according to technical considerations, but also preferably ecological, for example toxicity, water risk classes or biodegradability. Particularly useful organic solvents are alcohols, preferably methanol, ethanol, propanol, isopropanol, butanol, higher alcohols such as ethylene glycol, glycerol, polyether polyols such as polyethylene glycols and ether alcohols such as butyl glycol, methoxypropanol and alkyl polyethylene glycols, and also aldehydes , esters, ethers, amides or ketones, in particular acetone, methyl ethyl ketone, hydrocarbons, in particular methyl esters, ethyl esters, isopropyl esters, heptane, cyclohexane, xylene, toluene, mineral turpentine and mixtures thereof. Preferably it is given to ethyl acetate, ethanol, isopropanol or heptane and their mixtures. Particular preference is given to water as the solvent. Preference is also given to mixtures of water with alcohols having a water content greater than 50% by weight, preferably greater than 65% by weight, in particular greater than 80% by weight. Particular preference is given to a composition comprising Na lignosulfonate or Na 2-amino-2-methyl-1-propanol naphthalenesulfonate and water. Examples of additional additives are additives as is usual in concrete technology, in particular active surfactants, stabilizers against heat and light, mold release agents, chromate reducers, dyes, defoamers, accelerators, retarders, additional corrosion inhibitors, substances that introduce air or desaerean, pore formers, pumping aids, viscosity regulators, hydrophobic or thixotropic agents, shrinkage reducers. The proportion of the amino alcohol is from 0.1 to 20% by weight, preferably from 0.5 to 10% by weight, particularly preferably from 1 to 5% by weight, based on the total weight of the composition. The proportion of at least one plasticizer is from 10 to 99.9% by weight, preferably from 50 to 95% by weight, more preferably from 80 to 90% by weight, based on the total weight of the composition. The proportion of water or solvent is from 0 to 70% by weight, preferably from 5 to 50% by weight, more preferably from 10 to 40% by weight, based on the total weight of the composition. In a further embodiment, the present invention provides a hydraulic setting composition comprising or consisting of the composition of the invention and also at least one hydraulic setting binder. The hydraulic setting binder is preferably a mineral binder such as cement, gypsum, fly ash, fumed silica, slag, slag sand, lime filler or quicklime. Preferred hydraulic binders comprise at least one cement, in particular at least one cement according to European standard EN 197 or calcium sulphate in the anhydrite form, hemihydrate or dihydrate; or calcium hydroxide. Preference is given to portland cements, sulfoaluminate cements and high alumina cements, in particular portland cements. Mixtures of cements can lead to particularly good properties. For rapid curing, use is made in particular of binders containing fast-setting cement which preferably contain at least one cement with a high content of alumina or another source of aluminate, for example, clinker which supplies aluminate and, if appropriate, calcium sulphate and in the form of anhydrite, hemihydrate or dihydrate; and / or calcium hydroxide. Cement, in particular portland cement, is preferred as a constituent of the hydraulic binder. Particular preference is given to a low chromate cement. The composition of the invention is preferably added to the hydraulic setting binder, such that the proportion of the composition of the intention is from 0.1 to 5% by weight, preferably from 0.2 to 2% by weight, particularly preferably from 0.4 to 1.5% by weight, based on the weight of the hydraulic setting binder. The composition of the invention is produced by mixing the amino alcohol, 2-amino-2-methyl-1-propanol or N-aminopropylmonomethylethanolamine with at least one plasticizer, it being immaterial whether the amino alcohol is added to the plasticizer or vice versa. An aqueous composition or solution is produced by adding water or an organic solvent during the production of the plasticizer, in particular in the preparation of the polymer A of the formula (I), or by subsequent mixing of the plasticizer, the amino alcohol or the plasticizer and the amino alcohol with water or an organic solvent. Preference is given to mixing the plasticizer with water or an organic solvent, preferably water and subsequently adding the amino alcohol. The composition of the invention can be present as a clear or opaque solution or as a dispersion, i.e. as an emulsion or suspension. In the production of the hydraulic setting composition, the composition of the invention is preferably added simultaneously with the make-up water to the hydraulic setting composition, preferably the dry concrete mixture, or is mixed at the end in the setting composition Hydraulic after addition of replacement water. In a further embodiment, the present invention provides the use of the composition of the invention to reduce or prevent corrosion of steel, in particular corrosion of steel seals of prefabricated elements or reinforcing steel of concrete constructions. The composition of the invention is particularly useful for reducing or preventing corrosion in steel seals used for the production of prefabricated elements. In a further embodiment, the present invention provides the use of 2-amino-2-methyl-1-propanol and / or N-aminopropylmonomethylethanolamine to reduce or prevent corrosion in steel sealants of prefabricated elements or reinforcing steel of concrete constructions. . In a further embodiment, the present invention provides a method for reducing corrosion in steel seals of prefabricated elements or in steel reinforcements of steel reinforced concrete constructions, wherein the composition of the invention is added to fresh concrete and fresh concrete. gets in contact with the steel. The present invention further provides a concrete construction that has been prote against corrosion of steel seals or against corrosion of steel reinforcements and which comprises at least one composition according to the invention. The concrete construction is advantageously a building block or a component of an on-site or underground construction, in particular a building or tunnel, a road or a bridge, in particular a construction work that is produced from elements prefabricated The present invention therefore further provides a prefabricated element comprising the composition of the invention. The prefabricated element for example is a pipe, a wall, ceiling or floor plate, an element of pipe, strut or support, bridge support, bridge segment, linker, stairway or a platform. The present composition according to the invention has the advantage that it simultaneously acts as a plasticizer for hydraulic setting composition and as a corrosion inhibitor for steel. As a result, the corrosion protection is further improved over the corrosion inhibiting action of the amino alcohol because the use of the plasticizer reduces the amount of makeup water required in the production of concrete and thus decreases the water / cement value (value w / c). The lower the water / cement value, the obturator steel or steel inserts are less susceptible to come into contact with the concrete corrosion.

According to this embodiment, subsequent addition of a plasticizer or corrosion inhibitor and a process step is not necessary therefore saving on the use of the cement. This cement is therefore an easy-to-use product that can be produced in large quantities. A further advantage of the composition of the invention is that the corrosion inhibitor can be introduced directly into the hydraulic setting composition and the corrosion inhibitor does not have to be applied to the steel plug or steel inserts before the steel plug or inserts of steel be used. This results in improved corrosion protection and time saving. EXAMPLES The invention is illustrated below with the aid of examples. 1.1 Raw materials used Table 1: Raw materials used; percents are% by weight based on the total weight of the raw material. 1.2 Polymer A employee Table 2 Abbreviations used. Mw = average molecular weight The polymer A-1 indicated in table 3 is prepared from poly (meth) acrylic acid and by analogous polymer reaction with the corresponding alcohols and amines in a known manner. Polymer A-1 is present in partially neutralized form (NaOH). (M = H +, Na +). Polymer A is used as an aqueous solution in these examples. The polymer content is 40% by weight. This aqueous solution is referred to as A-1L. The concentrations of A-1 indicated in the following tables, in each case, are based on the content of aqueous solution A-1L.

Table 3 Polymer A-1 corresponds to formula (I) with M = H +, Na +. 2. Behavior of corrosion of plasticizer and amino alcohol in steel plates 5% by weight of cement (CEM I 42.5 R) is mixed with 95% by weight of water and this mixture is filtered. This results in "serum". A mixture of whey and amino alcohol or plasticizer, or whey, amino alcohol and plasticizer is produced and 3 drops of this mixture in each case are applied to a steel plate (20 x 20 cm, ST 35). The amounts of amino alcohol or plasticizer added to the serum are illustrated in Table 4. The figures in% in each case are the% by weight of aqueous solutions of the amino alcohol or the plasticizer, based on the total mixture of whey and the solutions aqueous of amino alcohol or plasticizer.

Table 4: Corrosion behavior of amino alcohol or plasticizers in serum or steel plates 3. Corrosion behavior in mortar mixtures in steel plates A standard mortar mix (1350 g of standard sand (according to EN 480 standard) , 450 g of cement (CEM I 42.5 R), 225 g of water, value w / c = 0.5%) is formulated with a mixture of plasticizers and amino alcohol and applied in a layer with a thickness of 1 cm to a filter paper. "white band" that rests or rests on a steel plate. After 24 hours, the severity of the corrosion on the steel plates is estimated visually (table 5). The figures in% for the addition in each case are the% by weight of amino alcohol or the plasticizer based on the total weight of cement.

Table 5: Corrosion behavior of mortar mixtures containing amine alcohol or plasticizer in steel plates 4. Depression, compressive strength and air pore content of concrete mixtures A concrete mixture of class C35 / 45 of resistance to compression, the class of depression F5 and having a maximum particle size of 16 mm (GK16) and a water / cement value (w / c value) of 0.45 is produced in accordance with EN 934 of 360 kg / m3 of CEM I 52.5 R. The concrete mixture is mixed with plasticizer or with a plasticizer / amino alcohol mixture and the depression is determined in accordance with EN 12350, the air pore content is determined in accordance with EN 12350 and the compressive strength of the cured prisms, is determined in accordance with EN 12390. The following plasticizers and amino alcohols are tested for (Table 6): Table 6: Plasticizers and amino alcohols and their mixtures. The addition is reported in% by weight based on the total weight of the plasticizer / amino alcohol mixture.

Table 7: Comparison of processability or consistency of concrete mixtures containing various plasticizer / amino alcohol mixtures. The results in Table 7 show that the processability and consistency of concrete mixtures containing plasticizer and amino alcohol remain as good as that of a concrete mix containing only plasticizer. Of course, the invention is not restricted to the examples shown and described. It goes without saying that the aforementioned characteristics of the invention can be used not only in the combination indicated in each case, but also in other modifications, combinations and alterations or alone without departing from the scope of the invention.

Claims (23)

1. CLAIMS 1. A composition comprising at least one plasticizer for a hydraulic setting composition and at least one amino alcohol selected from the group consisting of 2-amino-2-methyl-1-propanol and N-aminopropylmonomethylethanolamine.
2. 2. The composition according to claim 1, characterized in that the plasticizer comprises or consists of at least one polycarboxylate, preferably at least one polycarboxylate ether.
3. 3. The composition according to claim 2, characterized in that the polycarboxylate comprises or consists of at least one polymer A of the formula (I) wherein the symbols M each represent, independently of each other, H +, an alkali metal ion, alkaline earth metal ion, divalent or trivalent metal ion, ammonium ion or organic ammonium group, each R independently of the others is hydrogen or methyl, R1 and R2 each independently are, C C2o-alkyl, cycloalkyl, alkylaryl or - [AO] n -R4, wherein A = C2-C-alkylene, R4 = C20-alkyl, cyclohexyl or alkylaryl and n = 2 - 250, R3 is -NH2, -NR5R6, - OR7NR8R9, wherein R5 and R6 each independently are H or C20-alkyl, cycloalkyl or alkylaryl or aryl group; or a hydroxyalkyl group, or an acetoxyethyl group (CH3-CO-O-CH2-CH2-) or hydroxyisopropyl (HO-CH (CH3) -CH2-) or acetoxyisopropyl (CH3-CO-O-CH (CH3) -CH2- ), or R5 and R6 together form a ring from which the nitrogen of -NR5R6 is part to build a morpholine or imidazoline ring, wherein R7 is a C2-C4-alkylene group, and R8 and R9 each independently of each other, are a CrC20-alkyl, cycloalkyl, alkylaryl, aryl or hydroxyalkyl group, a, b, c and d are molar proportions already a / b / c / d = (0.05 - 0.9) / (0.05 - 0.95) / (0 - 0.8) / (0 - 0.5), and a + b + c + d = 1.
4. 4. The composition according to claim 3, characterized in that n = 8-200, particularly preferably n = 11 - 150.
5. 5. The composition in accordance with claim 3 or 4, characterized in that a / b / c / d = (0.1 - 0.9) / (0.1 - 0.9) / (0 - 0.5) / (0 - 0.1), preferably a / b / c / d = (0.1 - 0.9) / (0.1 - 0.9) / (0 - 0.3) / (0 - 0.06).
6. 6. The composition according to claim 5, characterized in that c + d > 0.
7. The composition according to claim 1, characterized in that the plasticizer comprises or consists of at least one polysaccharide, vinyl copolymer or sulfonate, in particular a lignosulfonate, naphthalene sulfonate or melaminesulfonate.
8. The composition according to any of the preceding claims, characterized in that the composition is a dispersion, in particular an aqueous dispersion.
9. 9. The composition according to any of claims 1 to 7, characterized in that the composition is a solution, in particular an aqueous solution.
10. 10. The composition according to any of the preceding claims, characterized in that the composition additionally contains additional additives, preferably a solvent or water.
11. The composition according to any of the preceding claims, characterized in that the proportion of the amino alcohol is from 0.1 to 20% by weight, preferably from 0.5 to 10% by weight, particularly preferably from 1 to 5% by weight, based on the total weight of the composition.
12. The composition according to any of the preceding claims, characterized in that the proportion is at least one plasticizer of 10 to 99.9% by weight, preferably 50 to 95% by weight, more preferably 80 to 90% by weight , based on the total weight of a composition.
13. 13. A hydraulic setting composition comprising a composition according to any of claims 1 to 12 and at least one hydraulic setting binder.
14. 14. The use of a composition according to any of claims 1 to 12, to reduce corrosion of steel.
15. 15. The use according to claim 14, characterized in that the corrosion in steel shutters of prefabricated elements is reduced.
16. 16. The use according to claim 14, characterized in that the corrosion in reinforcing steel of concrete constructions is reduced.
17. 17. The use of 2-amino-2-methyl-1-propanol and / or N-aminopropylmono-methylethanolamine to reduce corrosion of steel obturators of prefabricated elements.
18. 18. The use of 2-amino-2-methyl-1-propanol and / or N-aminopropylmono-methylethanolamine to reduce corrosion in reinforcing steel of concrete constructions.
19. 19. A process for producing a composition according to any of claims 1 to 12, comprising the step of a) mixing the amino alcohol 2-amino-2-methyl-1-propanol or N-aminopropyl mono-methylethanolamine and at least one plasticizer .
20. 20. A method for reducing corrosion in steel sealants of prefabricated or reinforcing steel elements of steel reinforced concrete constructions, characterized in that a composition according to any of claims 1 to 12 is added to fresh concrete and concrete Fresh is put in contact with steel.
21. 21. A concrete construction comprising a composition according to any of claims 1 to 12.
22. 22. A concrete construction according to claim 21, characterized in that the concrete construction is a construction job or a component of the construction. construction on the ground or underground, in particular a construction, a road or road, a bridge or a tunnel.
23. 23. A prefabricated element comprising a composition according to any of claims 1 to 12.