CH709580A2 - Corrosion inhibitors, improved color and anti-corrosive coating. - Google Patents

Abstract

The present invention is concerned with corrosion inhibitor formulations and anticorrosion paints or anticorrosive primers. Corrosion-protective inks containing anion-exchanging polymers in the form of basic anions and in nitrite form or nitrate form as well as an alkaline earth metal and alkaline phosphate ensure effective corrosion protection of iron alloys by passivation. Preference is given to polymers having imidazolium groups or phosphonium groups. According to a preferred embodiment, an anticorrosive formulation further contains alkaline earth phosphate particles to provide a system for slowly releasing anticorrosive ions even in low ionic water so that the metal to be protected is constantly in a passive state and in an optimum alkaline state pH interval is maintained.

Description

Technical area

This patent application is concerned with corrosion inhibitors and corrosion-protective coatings such as anti-corrosion paints. This invention is particularly concerned with corrosion inhibitors and anticorrosive coatings and anticorrosive paints for iron, steel and other iron alloy articles. This invention further concerns the preparation of anticorrosive primer additives.

Background of the invention

In our patent application 10 2014 207 517.3 of 21.4.2014 was a combination of anion-exchanging polymers or copolymers with quaternary alkyl ammonium groups (or quaternary Arylalkylammoniumgruppen) in hydroxide form and in nitrite form with a sparingly soluble, non-corrosive salt such For example, an alkaline earth metal phosphate such as Ca3 (PO4) 2 presented as inexpensive corrosion inhibitors for iron alloys. These anion-exchanging polymers containing quaternary ammonium groups in addition to commercial, strongly basic anion exchangers in hydroxide form or nitrite form in particular water-insoluble, soluble in a solvent copolymers which are obtainable by copolymerization of Vinylbenzyltrialkylammoniumchlorid or diallyldimethylammonium chloride with styrene and / or butadiene together with subsequent ion exchange into the hydroxide form or nitrite form.

However, there is a compatibility problem of these corrosion inhibitors and primers containing these corrosion inhibitors, to numerous polymers of conventional topcoats and light metals, which can lead to peeling of the paint layers or an etching of the base metal. For the primers in question can release such alkaline solutions that e.g. an acrylate-based topcoat would undergo alkaline hydrolysis of the ester groups.

Brief description of the invention

The present invention deals with corrosion inhibitors and anticorrosive paints which solve these compatibility problems.

It has been found that corrosion inhibitors containing anion-exchanging polymers (or copolymers) with quaternary alkylammonium groups or quaternary arylalkylammonium groups in nitrite form or other quaternary Alkylammoniumnitrite or quaternary Arylalkylammoniumnitrite and sparingly soluble salts such as alkaline earth metal phosphates such as Ca3 (PO4) 2, iron Steel and other iron alloys also protect, if instead of anion-exchanging polymers in hydroxide form other polymers (or copolymers) with alkylammonium groups (or quaternary arylalkylammonium groups) in the form of a weaker basic anion such as in the form of a carboxylic acid anion such as in acetate form or Benzoate form can be added.

It has also been found that epoxy resin-based paints, their epoxy resins, hardeners or other reactive additives such as reactive diluents carry appropriate functional groups such as imidazolium, ammonium or phosphonium groups, and a salt such as an alkaline earth metal phosphate (eg Calcium phosphate), show the desired corrosion protection. For the production of these colors, however, no large-scale radical copolymerization of special monomers is required.

According to a further embodiment of the present invention, the epoxy-based corrosion protection paints according to the invention can be used in a primer.

Short description of the drawing figures

These and the other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings, wherein: <Tb> FIG. Figure 1 shows the structure of another class of copolymers with quaternary alkyl ammonium groups in the acetate form (or hydroxide form) and nitrite form as part of a preparation of corrosion inhibitors according to an embodiment of the present invention; <Tb> FIG. Figure 2 shows the structure of copolymers with imidazolium groups in the acetate form (or hydroxide form) and nitrite form and t-butyl acrylate (or t-butyl methacrylate) according to another embodiment of the present invention; <Tb> FIG. 3 <SEP> shows the structure of copolymers with pyridinium groups in the acetate form (X <-> = acetate or hydroxide form X <-> = OH <->) and nitrite form (X <-> = NO2 <->) and t-butyl acrylate (or t-butyl methacrylate) according to another embodiment of the present invention; <Tb> FIG. Figure 4 shows the structure of copolymers having triphenyl phosphonium groups (for example in the acetate form (or hydroxide form) and nitrite form) and t-butyl acrylate (or t-butyl methacrylate) according to a further embodiment of the present invention; <Tb> FIG. Fig. 5 shows the structure of copolymers having julolidinium groups (for example, in the acetate form (or hydroxide form) and nitrite form) and t-butyl acrylate (or t-butyl methacrylate) according to another embodiment of the present invention; <Tb> FIG. FIG. 6 shows the change in the pH of a preparation according to the invention from anion-exchanging polymers having quaternary ammonium groups and strontium phosphate in purest water according to a further embodiment of the present invention by slow release of hydroxide ions; <Tb> FIG. 7A and 7B show an epoxy resin with functional imidazolium group according to the invention in nitrate (X.sup.- = NO.sub.3.sup.-) or in the form of basic anions X.sup.-, such as, for example, in acetate form (FIG. X <-> = CH 3 COO); <Tb> FIG. 8 shows a hardener with a functional imidazolium group according to the invention in nitrate (X.sup.- = NO.sub.3.sup.-) or in the form of basic anions X.sup.-, for example in acetate form (X.sup.-) CH3COO); and <Tb> FIG. FIG. 9 shows a reactive component with an inventive functional imidazolium group in nitrate (X.sup.- = NO.sub.3.sup.-) or in the form of basic anions X.sup.-such as, for example, in acetate form (X.sup.- = CH.sub.3COO.sub.3) <->);

These and the other features, aspects, and advantages of the present invention will become better understood with regard to the following description and appended claims.

Description of the embodiments

In our patent application DE 10 2014 207 517.3 of 21.4.2014, a combination of anion-exchanging polymers or copolymers with quaternary alkyl ammonium groups in hydroxide form and nitrite form with a sparingly soluble, non-corrosive salt such as an alkaline earth metal phosphate such as Ca3 ( PO4) 2 presented as corrosion inhibitors for iron alloys.

Without being bound by theory, it is believed that the anti-corrosive effect of these polymers is based on <tb> 1. <SEP> Corrosion promoting anions such as chloride ions are trapped by the polymer layer, <tb> 2. <SEP> alkaline hydroxide anions that prevent corrosion by passivating iron alloys, <tb> 3. <SEP> the quaternary ammonium compounds also show a corrosive effect and effect as a biocide. By adding a poorly water-soluble salt such as an alkaline earth metal phosphate, a system for the very slow release of alkaline hydroxide anions (and nitrite ions) in the presence of low-ionic water (such as rainwater) is formed by the anion exchanger low Phosphation traces, which are dissolved in contact of water to alkaline earth metal phosphate particles in an inventive anticorrosion paint, removed from the solution equilibrium and replaced by alkaline hydroxide ions (and nitrite ions). In this way, the metal part to be protected in the presence of water is kept permanently in an alkaline pH interval favorable for the passivation of iron (see FIG. 6) and thus passivated and extremely effectively preventive even in a considerable extent around a color layer according to the invention even on bare, uncoated Protect against rust. If the inventive coating according to the invention is coated as a primer with hydrophobic lacquers, this corrosion protection system is effective only where corrosion due to the ingress of moisture threatens.

At the same time, the inventive preparation is environmentally friendly, since the novel polymers are not soluble in water and can not be washed out and thus do not end up in the environment.

However, the novel polymers and preparations are only partially compatible with conventional paints such as acrylate-based, since the strong alkaline solutions that can be released from them by water, hydrolytically attack conventional paints and, for example, polymers of methacrylic acid esters or acrylic esters can saponify.

However, it has been found that instead of anion-exchanging polymers in hydroxide form in such a corrosion-protective preparation and anion-exchanging polymers in the form of a weaker basic anion can be used to obtain a satisfactory effect as a corrosion inhibitor.

As such weaker basic counter anions in copolymers with quaternary alkylammonium groups (or quaternary arylalkylammonium groups), in particular anions of organic carboxylic acids are preferred.

Preference is given to all carboxylic acid anions which form readily soluble salts with the cation of the sparingly soluble salt (in many examples doubly positively charged calcium and strontium ions or zinc ions).

More preferred are anions of weak carboxylic acids with the largest possible pKs (i.e., the lowest possible acid constant Ks), which should be above a value of 4.0, optimally above a value of 4.7.

Also preferred are anions of aliphatic and aromatic dicarboxylic acids such as azelaic acid and phthalate anions, although other anions of dicarboxylic acids may also be suitable. The dicarboxylic acids may be branched or unbranched, contain double or triple bonds or carry substituents such as hydroxyl groups, nitro groups or cyano groups.

More preferred are anions of weak dicarboxylic acids (pKs> 4.0 for the second stage), which-depending on the cation of the sparingly soluble salt in the anti-corrosive preparation-readily soluble lithium salts, alkaline earth salts or zinc salts form such as tartrate anions, Anions of maleic acid, fumarate anions or phthalate anions.

The use of anions of tricarboxylic acids, the easily soluble salts with Erdalkalibzw. Zinc ions are also preferred as long as they are elutable from the anion-exchanging polymer with anions of the sparingly soluble salt.

Anions with ≥ 4 carboxylic acid groups are usually eluted only with difficulty and are less suitable, even if individual anions could be suitable.

Preference is given to anions of monocarboxylic acids because of their ease of elution, their readily soluble alkaline earth salts and (apart from formic acid) the favorable pKa value of the carboxylic acids.

Highly preferred short-chain aliphatic monocarboxylic anions of C1-C5 carboxylic acids (formate to valerate anions) such as acetate ions or propionate anions and anions of aromatic monocarboxylic acids such as benzoate ions, although longer-chain carboxylic acids may be suitable could. The carboxylic acids in question may be branched or unbranched and bear substituents such as hydroxyl groups or halogens. The subject carboxylic acid anions may further contain double bonds or triple bonds such as cinnamic acid anions.

Optimal is the use of copolymers with quaternary alkylammonium groups (or arylalkylammonium groups) in acetate form.

Also preferred are polymers in the form of other basic anions such as hydrogencarbonate ions, hydrogen phosphate ions, phosphate ions, tetraborate anions, borate anions, hydrogen borate anions, carbonate ions, alkyl carbonate anions or silicate ions. Also preferred are as further polymers in the form of molybdate ions, tungstate ions or vanadate ions, although other anions such as chromate ions may also be suitable.

More preferred are polymers in the form of bicarbonate ions, hydrogen phosphate ions, hydrogen borate anions and silicate ions such as Si3O7 <2>.

According to another preferred embodiment of the present invention, polymers in nitrite form can be wholly or partly replaced by polymers in nitrate form, which are more stable. Polymers in the form of other oxidizing anions such as permanganate and manganate ions may also be suitable.

Preferred inventive anticorrosive preparations contain a molar ratio of polymers with quaternary ammonium groups in nitrite form or nitrate form to polymers with quaternary ammonium groups in the form of such basic anions or hydroxide form based on the functional groups between 20: 1 to 1:20. Preference is given to a molar ratio of 10: 1 to 1:10, more preferably a molar ratio of 5: 1 to 1: 5, optimally a molar ratio of 1: 1 to 3: 1 with a slight excess of polymers in nitrite Shape. Preparations with a molar ratio above 20: 1 may show too short a protective effect, while preparations with a molar ratio of less than 1:20 do not ensure satisfactory corrosion protection, although ratios above 100: 1 or below 1: 100 still a certain short-term Can show protective effect.

Basic anions (e.g., hydroxide ions, acetate ions) and nitrite ions may be bonded to a single anion exchange polymer resin rather than two resins according to another preferred embodiment of the present invention.

Preferred inventive anticorrosive preparations also contain at least one sparingly soluble salt such as alkaline earth metal phosphates such as calcium phosphate in a molar ratio to the functional groups of the above polymers between 0.1 and 2.0. A molar ratio between 0.1 and 0.9 is preferred, a molar ratio between 0.1 and 0.5 is more preferred for alkaline earth phosphates, a molar ratio between 0.1 and 0.25 is most preferred and a molar ratio of 1 / (mz) for anions Y <z> <-> of a salt MenYm, ie 0.167 for calcium phosphate is optimal. Substance ratios below 0.01 do not provide a satisfactory corrosion protection against rainwater while molar ratios above 0.5 offer no significant advantage.

Instead of alkaline earth phosphates such as calcium phosphate (Ca3 (PO4) 2), strontium phosphate, barium phosphate, magnesium phosphate, lithium phosphate and other sparingly soluble alkaline earth salts such as carbonates, chromates, molybdate or oxalates with a charge ≥ 2 can be used. However, preferred are alkaline earth metal phosphates.

Copolymers (or terpolymers) of vinylbenzyltrimethylammonium chloride and methacrylates, acrylates and styrene are preferred as well as copolymers of diallyldimethylammonium chloride with acrylates, methacrylates or styrene, whose glass transition temperature preferably between 30 ° C and 100 ° C as copolymers with anion exchange effect , strongly preferred between 40 ° C and 80 ° C. Also preferred are copolymers (or terpolymers) of acrylamidopropyltrimethylammonium chloride (as well as analogous esters attached to quaternary ammonium groups, see Figure 1) bearing a quaternary ammonium group attached via a molecular bridge (BR in Figure 1) with acrylates, methacrylates or styrene.

According to one embodiment of the present invention, the tert-butyl esters of acrylic acid (t-butyl acrylate, ie R5 = t-butyl, R3 = H) or methacrylic acid (t-butyl methacrylate, ie R5 = t-butyl, R3 = CH3) and styrene as monomers for alkali-resistant copolymers are strongly preferred, since they also provide homopolymers as resistant to relatively strong alkalis (pH <12) resistant polymers. Such copolymers provide good resistance to alkaline solutions as well as alkaline oxidation products of base metals, so that the paint can not be decomposed by alkaline solutions. Also preferred as further monomers are methyl methacrylate (MMA).

According to another embodiment of the present invention, preference is given to anion-exchange polymers (or copolymers or terpolymers) which contain imidazolium groups, pyridinium groups, pyrrolium groups or quaternary phosphonium groups instead of quaternary ammonium groups, although other positively charged quaternary groups Groups of, for example, heterocyclic compounds as well as trimethylenediamine (DABCO) or quinuclidine or sulfonium groups, benzimidazolium groups or triazolium groups may also be suitable.

A mole fraction of monomers having positively charged functional groups, such as, for example, quaternary ammonium groups, imidazolium groups or phosphonium groups on all monomers (including monomers without charged groups) for the preparation of the anion-exchanging polymers according to the invention between 0.01 mol% and 30 mol% is preferred. More preferred is a mole fraction of between 1 mol% and 20 mol%. Most preferably, a mole fraction of the functionalized monomers is between 5 mole% and 10 mole%. Polymers with a molar fraction below 0.01 mol% do not provide reliable corrosion protection, whereas polymers with a molar fraction above 30 mol% are soluble in water and would therefore be washed off by water and rain from the object to be protected.

In a further embodiment of the present invention, inert polymers such as polystyrene or poly (t-butyl acrylate) may be further added to a preparation according to the invention.

Although the formation of nitrosaraines from quaternary ammonium ions and nitrite in sufficient alkaline solution is practically impossible even in ppt traces, N-alkyl-imidazolium groups, pyridinium groups, pyrrolium groups or quaternary phosphonium groups have the advantage of even after oxidative cleavage of one or more N-alkyl groups (or P-alkyl groups) in acidic solution to form no nitrosamines. Particularly preferred are alkali-resistant 1-alkyl-2-alkyl-3-alkyl-imidazolium groups such as, for example, 1-alkyl-2-isopropyl-3-alkylimidazolium groups or 1-alkyl-2-methyl-3-alkylimidazolium groups, Tris (2, 4, 6-Trialkoxyphenyl) benzylphosphonium groups such as tris (2, 4, 6-trimethoxyphenyl) benzylphosphonium groups (see FIG. 4, R = CH30-) or tetrabenzylphosphonium groups in which from the outset no nitrosamines although other alkali-resistant quaternary phosphonium groups with oxidation-resistant substituents may also be suitable.

Also particularly preferred are imidazolium derivatives which carry alkyl groups or benzyl groups on both nitrogen atoms (see Fig. Fig. 2), although other substituents may also be suitable. These form no nitrosamines even after oxidative cleavage of the N-alkyl groups with suitable substituents, and the starting materials are available at low cost on a large scale.

Most preferred are the more resistant to bases imidazolium groups which can be prepared from 2-alkylimidazole, so for example 2-isopropyl-1-methyl-3-benzylimidazolium groups being preferred as alkyl substituents isopropyl and methyl groups, although also other alkyl groups such as t-butyl groups or trifluoromethyl groups come into question. Less preferred are phenyl, benzyl and cyclohexyl substituents in this 2-position of imidazole, since the respective, so substituted imidazoles can form nitrosamines in acidic solution with nitrite. The imidazoles in question can be bound to the polymer chain by reaction with copolymers of vinylbenzyl chloride (obtained, for example, by emulsion polymerization) and converted into imidazolium salts. Alternatively, comparable copolymers may also be prepared by direct copolymerization of vinylimidazoles, allylimidazoles or imidazolyl derivatives (eg 2- (1H-imidazol-1-yl) ethyl ester) of acrylic acid or methacrylic acid such as 2- (1H-imidazol-1-yl) ethyl methacrylate other monomers are produced.

The groups in question can be bonded to the polymer main chain by oxidation-resistant bridges according to another embodiment of the present invention. Such difluoromethyl bridges can be generated by chlorodifluoromethylation of aromatics using chlorodifluoroacetic anhydride. This has the advantage that possibly formed nitrosamines remain bound to the polymer until their decomposition (for example due to UV irradiation).

To prevent oxidative cleavage of N-alkyl groups, which may lead to the formation of undesirable tertiary or even secondary amines, oxidation-resistant substituents may be introduced on the nitrogen according to another embodiment of the present invention. Oxidation-resistant substituents on nitrogen atoms are, in particular, oxidation-resistant perfluoroalkyl groups such as, for example, N-trifluoromethyl groups, which can be introduced by means of electrophilic trifluoromethylation. Oxidation-resistant perfluoroalkyl groups are also possible as substituents in the 2-position on the imidazole ring in order to improve the alkali resistance of the imidazolium ring. Alternatively, such copolymers may be prepared by copolymerizing vinylimidazoles with other monomers.

Also preferred are polymers with pyridinium groups (see Fig. 3). Since pyridine also does not form nitrosamines according to the literature, such polymers should also show no nitrosamine formation on oxidative cleavage of the pyridine ring. Such polymers may alternatively be prepared by copolymerization of vinyl pyridines with other monomers.

According to a further embodiment of the present invention, preference is likewise given to polymers having positively charged quaternary ammonium groups in which the nitrogen atoms are present in bicyclic systems, for example N-alkylated 1,2,4,5-tetrahydropyrrolo [3, 2, 1] hi] indole or more preferably N-alkylated julolidine (2, 3, 6, 7-tetrahydro-1H, 5H-pyrido [3,2,1-ij] quinoline) which, via a suitable bridge, crosses one of the carbon atoms on the main polymer chain are bound (see Fig. 5). In the case of oxidative cleavage of two alkyl groups on the nitrogen atom, amines can be formed here, thanks to the three bridges to the polymer main chain, which remain firmly bound to the polymer even in the event of subsequent formation of nitrosamines, so that no nitrosamines can be released. Alternatively, alkylated quinuclidine can be linked to a polymer chain in an analogous manner to achieve this advantage. Similarly advantageous would be a bond of the quaternary nitrogen atom via two bridges.

Most preferred are copolymers which are obtainable by copolymerization of t-butyl acrylate or t-butyl methacrylate or alkyl methacrylates such as methyl methacrylate or styrene with the synthons vinylbenzyltrimethylammonium hydroxide or a Vinylbenzyltrimethylammoniumcarboxylat, in particular vinylbenzyltrimethylammonium acetate and vinylbenzyltrimethylammonium nitrate, as well as copolymers obtained by copolymerization of t-butyl Butyl acrylate or t-butyl methacrylate or alkyl methacrylates such as methyl methacrylate or styrene with 1-vinylbenzyl-2-alkyl-3-alkylimidazolium hydroxide (ie, 3- (4-ethenylbenzyl) -1-alkyl-2-alkyl-1H-imidazole-3-ium hydroxide ) or 1-vinylbenzyl-2-alkyl-3-alkylimidazolium carboxylate, in particular 1-vinylbenzyl-2-alkyl-3-alkylimidazolium acetate, and at least one monomer selected from the group consisting of 1-vinylbenzyl-2-alkyl-3-alkylimidazolium nitrate or 1-vinylbenzyl 2-alkyl-3-alkylimidazoliumnitrit would be available.

Instead of polymers having such functional groups, it is also possible to add ionic liquids which are soluble in the lacquer according to the invention. Preferred ionic liquids are those based on imidazolium ions such as, for example, 1-butyl-3-methylimidazolium acetate (bmim acetate) and 1-butyl-3-methylimidazolium nitrite (bmim nitrite), more preferably ionic liquids with organic cations having longer-chain alkyl groups such as For example, 1-hexyl-3-methylimidazoliumacetat (or nitrite) or 1-methyl-3-octylimidazoliumacetat (or nitrite). The respective alkyl groups in the 2-position or 3-position of the imidazole ring may be C 1 -C 22 -alkyl groups. Also preferred are ionic liquids based on pyridinium salts. Likewise preferred are ionic liquids which contain trimethoxysilyl groups in the cation as a function of the carrier material. Ionic liquids can also be used in combination with the functional polymers according to the invention.

According to a further embodiment of the present invention, ionic liquids bound to supports such as silica, glass or silicate particles or cyclodextrins are used as corrosion inhibitors. Preferred for this purpose are ionic liquids with cations having trimethoxysilyl groups or with anions such as bis (trifluoromethane) sulfonimide.

Preferred are ionic liquids with basic anions such as hydroxide, acetate, benzoate and other carboxylic acid anions and nitrite anions or, for example, molybdate anions, tungstate anions or vanadate anions, although other anions such as chromate anions may be suitable can.

More preferred are polymers having anion exchange properties which are provided in the form of a basic anion (e.g., in hydroxide form or acetate form) and partially converted to the nitrite form.

As sparingly soluble salts in the novel anticorrosive preparations functional polymers with basic anions and nitrite anions (or corresponding ionic liquid) with sparingly soluble salts particularly sparingly soluble alkaline earth phosphates, lithium phosphate and phosphates of transition metals such as zinc phosphate are preferred, although also other salts that contain no corrosion-promoting anions may be suitable. Calcium phosphate and strontium phosphate are more preferred. Most preferred is a mixture of phosphates with different solubility product.

According to one embodiment of the present invention are soluble in an organic solvent long-chain copolymers (or terpolymers) with positively charged anion-exchanging groups in the respective anion form (eg in acetate form and nitrite form) in a solvent as Conventional physically drying film-forming agents having a corrosion-protecting effect in the presence of sparingly soluble salts with corrosion-protecting anions, such as, for example, alkaline earth metal phosphates, are preferred.

According to another embodiment of environmentally friendly paints with high solids content and low solvent content short-chain copolymers are dissolved in higher concentrations in solvents.

According to a further embodiment of the present invention, anticorrosive preparations according to the invention are suitable for use in water-based paints. By adding small amounts of a hydrophobic solvent such as ethers can be achieved that the reaction to release corrosion-protective anions does not start or delayed despite the presence of water.

Corrosion-protecting anion exchange polymer salt preparations according to the present invention are compatible with polymers having epoxy groups and the anion-exchanging copolymers according to the invention may themselves carry epoxy groups and be cured by epoxy crosslinking reactions.

As reactants for these epoxy resins, aromatic carboxylic acid anhydrides such as pyromellitic anhydride or phthalic anhydride are preferred. In one embodiment of the present invention, tertiary amines such as triethylenediamine (DABCO) and imidazoles are preferred as the catalyst for the curing of the epoxy resins.

In a further embodiment of the present invention, anticorrosive preparations according to the invention are used in powder coatings for powder coating of metal objects. For this purpose, the above resins are suitable with additional epoxy groups.

In a further embodiment of the present invention, corrosion protection systems according to the invention are used as a constituent of electrocoating paints (CDL paints). For this purpose, additional functional groups such as teit.-amines in protonated form (preferably with the carboxylic anion of the anion exchanger groups) necessary to make these polymers water-soluble, in addition reactive groups such as epoxy groups for later crosslinking of the cathodically deposited dip coatings.

The preparation of the novel polymers is preferably carried out by polymerization of unsaturated compounds having aromatic or aliphatic radicals which can undergo a subsequent alkylation reaction with amines or nitrogen-containing heterocycles such as imidazole, such as vinylbenzyl chloride with acrylates, methacrylates or styrene and subsequent reaction with a tertiary amine such as trimethylamine, triethylamine or other trialkylamines or nitrogen-containing heterocycles such as imidazole, more preferably 2, 3-dimethylimidazole, 2-isopropyl-3-methylimidazole, 2-methyl-3-butylimidazole, 2-isopropyl-3-butylimidazole, although other substituted imidazoles or benzimidazoles may be suitable.

In a preferred process, 1-vinylimidazole, more preferably 1-vinyl-2-methylimidazole, 1-vinyl-2-isopropylimidazole is polymerized with acrylates such as t-butylmethacrylate, methacrylates such as t-butylmethacrylate or methylmethacrylate, and the product is subsequently polymerized with alkylating agents such as methyl iodide or 1-bromobutane converted into polymers with imidazolium groups. In a particularly preferred embodiment of this process, an alkyl carbonate is used as the alkylating agent.

Instead of the later functionalization, vinylbenzyltrimethylammonium halides or 1-vinylimidazolium salts can also be polymerized directly in a suitable solvent with the methacrylates or acrylates or styrene.

The resulting polymers in the halide form can be completely or preferably partially converted into the nitrite form by ion exchange such as by several hours of exposure to alkali hydroxide solution in the hydroxide form, sodium acetate solution in the acetate form and become.

A partial conversion of the polymers with anion-exchanging groups in hydroxide form or acetate form into the nitrite form is more preferred in order to always keep the polymer in a basic medium.

The resulting in the case of alkylation with alkyl carbonates products in carbonate form can be converted directly into the acetate form by reaction with Bronsted acids such as acetic acid, wherein the products formed are advantageously free of interfering corrosion-promoting halide ions such as chloride ions.

Although a free-radical polymerization reaction is the most preferred preparation process for the preparation of the functional polymers of this invention, anionic or cationic polymerization reactions may also be suitable for preparation. Instead of polymers which are obtained by polymerization, polymers which are obtained by polycondensation or polyaddition, if they are compatible with alkaline media and nitrite or nitrate ions, can also be used for the anticorrosive preparations according to the invention. Functional polymers prepared by graft polymerisation are also suitable.

According to a further embodiment of the present invention, the novel polymers with anion-exchanging groups in nitrite form are likewise suitable for the protection of other metals such as, for example, light metals such as, for example, aluminum alloys. The preparations in question also suitably contain a sparingly water-soluble salt, such as an alkaline earth metal phosphate. The preparations may further contain other corrosion inhibitors such as benzothiazoles or benzotriazole.

It has also been found that epoxy resins, hardeners or other reactive components such as reactive diluents having such functional groups can be prepared relatively easily. Such epoxy resins contain reactive diluents having one or two epoxide groups or, as binders, a plurality of epoxide groups, typically two to four epoxide groups.

For the purposes of this patent application, weakly basic anions are understood as meaning anions of conjugated acids with a negative logarithmic acid constant pKs between about 3.75 (formic acid) and about 10.33 (HCO3 <-> / CO3 <2>), thus a base constant pKb = 14-pKsbetween 3.67 and 10:25 are understood.

Epoxide resins according to the invention are bisphenol A-based epoxides such as bisphenol A diglycidyl ether (BADGE, FIG. 1A), higher molecular weight bisphenol A-epichlorohydrin resins (see FIG. 1B) with n = 0.1 to n = 26, Bisphenol-F-epichlorohydrin resin are used, which at least one erfmdungsgemäße functional group such as imidazolium groups, ammonium groups or phosphonium groups in nitrate form, nitrite form or form of weakly basic anions such as carboxylate form such as acetate Form, maleate form, borate form, hydrogen phosphate form, dicyanamide form, silicate form, bicarbonate form, phosphate form or carbonate form, although other acid anions such as lactate anions may be suitable. It is also possible to use a mixture of such compounds with weakly basic anions.

In addition to these weakly basic anions, it is also possible to use such compounds in hydroxide form, insofar as the more strongly basic hydroxide ions are compatible with other materials used, such as topcoats. However, preferred are weakly basic anions to avoid such compatibility problems.

Preference is given to epoxy resins such as bisphenol A diglycidyl ether (BADGE) with appropriate functional group or at low temperatures <80 ° C liquid low molecular weight bisphenol-A-epichlorohydrin resins with n = 0.1 to n = 1.1 with appropriate functional group.

Preferred as epoxy resins are also functionalized t-butyl acrylate copolymers with glycidyl methacrylate.

Such inventive epoxy resins with such functional groups can be crosslinked with amines or carboxylic anhydrides as a curing agent. However, epoxy resins in nitrite form must not be cross-linked with amines in order to exclude the formation of nitrosamines.

According to a further embodiment of the present invention are thiols, especially thiols having two to four thiol groups per molecule such as pentaerythritol tetra (3-mercaptopropionate) (THIOCURE <>> PETMP, registered trademark of Bruno Bock Chemische Fabrik GmbH & Co. KG Eichholzer Str. 23, 21436 Marschacht) are preferred as reactants for epoxy resins instead of amines. Such thiols can also carry quaternary ammonium, phosphonium or imidazolium groups according to the invention with anticorrosive anions as counterions.

As a hardener, all known in the art hardener for epoxy resins can be used, provided that they are compatible with the anticorrosive anions used and provide alkali-resistant products, ie in particular polysulfides, polyamides, imidazolines, adducts of amines with epoxides, Mannich bases, ketimines Acrylonitrile adducts with ethyleneamines, dialkylaminopropylamines, hexamethylenediamine and other long-chain diamines, polyetheramines, polymeric amines, aromatic-aliphatic amines such as meta-xylenediamine (MXDA), cyclic aliphatic amines, dicyandiamide, melamine, guanamines, aromatic amines, phenolic novolak resins, Resole resins, amino-formaldehyde resins (such as urea-formaldehyde or melamine-formaldehyde resins), although other hardeners such as carboxylic hydrazides and hydrazines may be suitable. These hardeners can also carry corrosion-protecting functional groups according to the invention.

Preference is given to epoxy resins having functional groups according to the invention in nitrate form or form of weakly basic anions and amine hardeners such as, for example, ethylenediamine, dipropylenetriamine, 4,4-diamino-3,3-dimethyldicyclohexylmethane, 4,4-diaminodiphenylmethane , Ketimine, polyamidoamine from dicarboxylic acids and ethylenediamine, and unmodified or substituted dicyandiamide.

According to a further embodiment of the present invention, it is also possible to use hardeners which carry functional groups according to the invention, as shown in FIG. 2. Such functionalized curing agents are also suitable for curing conventional epoxy resins to obtain a corrosion-protective epoxy resin coating according to the invention.

According to a further embodiment of the present invention, reactive diluents according to FIG. 3 are admixed with the epoxy resin which contains an ionic liquid carrying epoxide groups in nitrate form, nitrite form or in the form of weakly basic anions.

Preferred inventive anticorrosion paints contain a molar ratio of quaternary nitrogen or phosphorus compounds in nitrite form or nitrate form to those in the form of such basic anions or hydroxide form based on the functional groups between 20: 1 to 1:20. Preferred is a molar ratio of 10: 1 to 1:10, more preferably a molar ratio of 5: 1 to 1: 5, optimally, a molar ratio of 1: 1 to 3: 1 with a slight excess of compounds in nitrite or. Nitrate form. Preparations with a molar ratio above 20: 1 may show too short a protective effect, while preparations with a molar ratio of less than 1:20 do not ensure satisfactory corrosion protection, although ratios above 100: 1 or below 1: 100 still a certain short-term Can show protective effect.

Preference is given as inventive corrosion-protective reactive diluent 1-glycidyl-3-alkylimidazoliumnitrat with unbranched or branched C1-C12-alkyl groups such as 1-glycidyl-3-butylimidazoliumnitrat or 1-glycidyl-3-alkylimidazoliumacetat with C1-C12-alkyl groups such as for example, 1-glycidyl-3-butylimidazolium acetate. Also preferred are 1,3-diglycidylimidazolium nitrate or 1,3-diglycidylimidazolium acetate or similar compounds having at least two glycidyl groups and an imidazolium ring. Also preferred are glycidyltrimethylammonium nitrate and glycidyltrimethylammonium acetate.

Highly preferred are 1-glycidyl-2-alkyl-3-butylimidazolium nitrate or 1-glycidyl-2-alkyl-3-butylimidazolium acetate and 1,3-diglycidylimidazolium nitrate or acetate with alkyl groups such as methyl groups (see FIG 3), ethyl groups, isopropyl groups and n-butyl and t-butyl groups.

Also preferred are 1- (1, 2-epoxyethyl) -3-alkylimidazolium nitrate or acetate with C1-C12-alkyl groups such as 1- (1, 2-epoxyethyl) -3-methylimidazolium nitrate or acetate, 1 - (1, 2-epoxyethyl) -3-ethylimidazolium nitrate or acetate, 1- (1,2-epoxyethyl) -3-n-propylimidazolium nitrate or acetate, 1- (1,2-epoxyethyl) -3-isopropylimidazolium nitrate or acetate, 1- (1, 2-epoxyethyl) -3-butylimidazolium nitrate or acetate, 1- (1, 2-epoxyethyl) -3-pentylimidazolium nitrate or acetate, 1- (1, 2-epoxyethyl) 3-hexylimidazolium nitrate or acetate. More preferred are 1- (1,2-epoxyethyl) -2- (alkyl) n-3- (alkyl) i-imidazolium nitrate or acetate with C1-C12 alkyl groups in the 3-position and methyl, ethyl, isopropyl , n-butyl and t-butyl groups in the 2-position.

Likewise preferred as corrosion-protective reactive diluent preparations according to the invention are N-glycidylpyridinium acetate in a mixture with N-glycidylpyridinium nitrate.

Glycidyltrialkylammoniumacetate in admixture with Glycidyltrialkylammoniumnitrate with unbranched or branched C1-C12-alkyl groups such as glycidyltributylammonium acetate in admixture with glycidyltributylammonium nitrate or glycidyltrimethylammonium acetate in admixture with glycidyltrimethylammonium nitrate are preferred as inventive corrosion-protective reactive diluent preparations. Analogous glycidyl trialkylphosphonium cations are also preferred.

In all embodiments, an equimolar mole fraction of ionic bodies (ie, epoxy resins, hardeners or reactive diluents with novel ammonium, imidazolium or phosphonium groups) in nitrate form (or nitrite form) to ionic bodies in the form of basic anions (for example, in acetate form) from 1 part nitrate form to 1 part acetate form most preferably, although lower levels of the nitrate form or acetate form provide some protection against corrosion.

Further, in all embodiments, a substance ratio of sparingly water-soluble salts in the form of alkaline earth phosphates to above ionic bodies (in the form of simply negatively charged anions such as acetate or nitrate ions) is between 0.1: 1 and 1: 1 relative to Substance of the anions of the salt is preferred. Particularly preferred is a molar ratio of between 0.1: 1 and 0.5: 1. Most preferred is a molar ratio of between 0.1: 1 and 0.25: 1. A molar ratio of 0.167: 1 is optimal. For other sparingly soluble salts MenYmmit Anions Y <z> <-> is a molar ratio of l / (m z) of poorly water-soluble salt epoxides according to the invention with quaternary nitrogen groups (with simply negatively charged anions such as acetate and nitrate ions) optimal. Substance ratios below 0.01 do not provide satisfactory corrosion protection against rainwater while molar ratios above 1.0 offer no appreciable advantage.

An ion exchange capacity of the ionic bodies according to the invention in the paint of 0.01 meq / g to 7 meq / g is preferred. Highly preferred is an ion exchange capacity for inventive ionic body in the paint of 0.1 meq / g to 2 meq / g. Most preferred is an ion exchange capacity of 0.25 meq / g to 1.2 meq / g. Ion exchange capacities below 0.01 meq / g provide only short term corrosion protection. Ion exchange capacity over 7 meq / g are hard to beat due to the molecular weight of the substances used.

According to a further embodiment, the novel corrosion inhibitor resins or reactive diluents are used in a primer based on epoxy resin.

Such primers may also contain epoxy resins with amine-containing hardeners for inhibitors in the form of basic anions and in nitrate form. Also, the epoxy resins or amine-based curing agents themselves may carry additional nitrate or basic anionic quaternary ammonium, imidazolium or pyridinium groups.

According to a further embodiment of the present invention, instead of epoxy resins having corrosion-protecting functional groups according to the invention (quaternary ammonium, imidazolium or pyridinium or phosphonium groups with the said corrosion-protecting anions), isocyanates are preferred as crosslinking agents. Preferred as reaction components in this embodiment of the present invention are alcohols.

These alcohols may in a further embodiment of the present invention erfmdungsgemässe anticorrosive functional groups, especially quaternary ammonium, imidazolium, or pyridinium or phosphonium groups in nitrate form and acetate form.

In one embodiment of the present invention, capped isocyanates ("blocked isocyanates") are preferred for linking molecules with hydroxyl groups. Conventional capping agents such as diethyl malonate, 3,5-dimethyl-1,2-pyrazole or ethyl acetoacetate may be used as capping agents, although methyl ethyl ketoxime, 1,2,4-triazole, epsilon-caprolactam or phenols may also be used. Preference is given to such blocked isocyanates which carry inventive anticorrosive functional groups.

As such reactants with hydroxyl groups are in a further embodiment of the present invention with, for example, aminoalkanols modified epoxy resins preferred. More preferred as reaction partners are such modified epoxy resins in the form of water-soluble KTL dip coatings for the electrophoretic deposition of dip paints. The corrosion-protecting functional groups according to the invention may also be bonded to the modified epoxy resin or bound to both components instead of the blocked isocyanate.

According to a further embodiment of the present invention, instead of epoxy resins having corrosion-protecting functional groups according to the invention (quaternary ammonium, imidazolium or pyridinium or phosphonium groups with the said corrosion-protecting anions), alkyd resins having a corrosion-protecting functional group according to the invention, in particular alkyd resins, which carry a quaternary ammonium, imidazolium, or pyridinium or phosphonium groups in nitrate form and acetate form.

Preferred such alkyd resins are, for example, polyesters of phthalic acid with pentaerythritol and unsaturated carboxylic acids, a carboxylic acid carrying one of the above anticorrosive functional groups with a quaternary nitrogen atom (or phosphorus atom). Particularly preferred carboxylic acid is a substituted benzoic acid of benzoic acid-modified alkyd resins, in which part of the 9,12-linoleic acid in said ester has been replaced by benzoic acid with pentaerythritol. Alternatively, it is also possible to use a substituted phthalic acid in such alkyd resins which carries anticorrosive functional groups according to the invention.

Preferred for crosslinking in this embodiment as alkyd resin siccatives based on cobalt or manganese compounds.

According to a further embodiment of the present invention can also be an amino resin, for example a melamine resin such as hexamethoxymethyl melamine resin find use as a reactant (hardener) for alkyd resins in stoving. The amino resin used as hardener can also carry corrosion-protecting functional groups according to the invention.

According to a further embodiment of the present invention, instead of alkyd resins having corrosion-protecting functional groups according to the invention in stoving lacquers, acrylate resins or saturated polyesters can be used as reactants for amino resins which carry anticorrosive functional groups according to the invention.

BEST MODE TO CARRY OUT THE INVENTION

The following examples illustrate the best mode of carrying out embodiments of the invention. Examples 1-5 demonstrate the preparation of copolymers according to the invention for use as corrosion inhibitors with imidazolium groups, Example 6 the preparation of a copolymer having ammonium groups.

EXAMPLES

example 1

Copolymerization of t-butyl acrylate with vinylbenzyl chloride

23.44 g of t-butyl acrylate (98%, Sigma-Aldrich, Taufkirchen) and 3.45 g of vinylbenzyl chloride (97%, mixture of 3- and 4-isomers, Sigma-Aldrich, Taufkirchen) are each by shaking with 0.5% sodium hydroxide in a separating funnel freed from the stabilizers. 23.10 g of the t-butyl acrylate and 2.86 g of vinyl benzyl chloride are distilled in a round bottom flask with 25.26 g of distilled water and 153.7 mg of sodium lauryl sulfate (Sigma-Aldrich, Taufkirchen) in 1.2613 g. Water is added. After addition of a solution of 145.5 mg of sodium bicarbonate in 3.4148 g of distilled water and 0.45 g of ammonium peroxodisulfate (p.a., FlukaAG, Buchs, Switzerland) and 0.37 g of sodium peroxodisulfate (Bayer AG, Leverkusen), the flask is purged with argon for 20 minutes. Subsequently, the polymerization of the suspension is carried out by heating under reflux and vigorous stirring with a magnetic stirrer at 70 ° C for 3 hours. After cooling, the batch gives 13.6 g of agglomerate cake solid polymer and 49.7 g of a solution of a polymer latex.

Example 2

Reaction of the copolymer with 1,2-dimethylimidazole

0.4 g of the polymer agglomerate from Example 1 are stirred with 7.0 g of 1,2-dimethylimidazole (Sigma-Aldrich, Taufkirchen) for 28 hours at room temperature with a magnetic stirrer. It forms a slightly foaming dispersion of the desired polymers with imidazolium groups in chloride form.

Example 3

Drying of the imidazolium copolymer

1 ml of the dispersion of the copolymer with imidazolium groups from Example 2 are applied to a glass plate and dried at 80 ° C for at least 3 hours on the hotplate of a magnetic stirrer. From the rest of the dispersion is removed by vacuum distillation at 80 ° C, the excess of dimethylimidazole.

Example 4:

Conversion of the polymer into the hydroxide form or acetate form

The glass plate with the dried film of copolymers in the chloride form of Example 3 is immersed for 24 hours in 80 ml of 1 M potassium hydroxide solution (prepared from KOH purissimum p.a., Fluka, Taufkirchen). The result is a film of the copolymer with imidazolium in hydroxide form which by ion exchange with IM acetic acid, sodium acetate solution (or sodium nitrite solution or potassium nitrate solution or nitric acid) for a period of 24 hours in the acetate form (or nitrite form and nitrate). Form) is converted.

Example 5

Preparation of a dispersion of the copolymer in acetate form in a solvent

The acetate-form copolymer prepared by the method of Example 4 is dissolved in 20 ml of tetrahydrofuran (dried over molecular sieve, Fluka, Taufkirchen) with heating to 63 ° C under reflux.

Example 6

Preparation of a copolymer with quaternary ammonium groups

13.8 g of the latex from Example 1 are filled with 5.8 g of triethylamine (Fluka AG, Buchs) in a round bottom flask with stirring and heated at 40 ° C for 5 days with stirring. The resulting dispersion of a polymer having quaternary ammonium groups is worked up as in Examples 3-5.

The present invention is industrially applicable to the corrosion protection of iron alloys.

Although the present invention has been described in considerable detail with reference to certain preferred embodiments, other embodiments are possible. For example, it is possible to use a copolymer in the form of dicyanamide form. Therefore, the scope of the appended claims should not be limited to the description of the preferred embodiments herein.

The reader's attention is directed to all articles and documents filed concurrently or prior to this description in the context of this application, and with this description accessible to public inspection, and the contents of all such articles and documents are herein by reference.

All features disclosed in this specification (including all appended claims, abstract and drawings), and / or all steps of any process or process so published may be substituted by alternative features serving the same, equivalent, or similar purpose. unless otherwise stated. Thus, unless expressly stated otherwise, each feature disclosed is merely an example of only a generic order of equivalent or similar features.

Claims (10)

1. Anti-corrosive preparation containing at least one polymer with anion exchanger groups a) in the form of basic anions; and b) at least partially in the form of nitrate anions or nitrite anions. The anticorrosive composition according to claim 1, wherein as basic anions anions from the group of hydroxide anions, carboxylic anions, hydrogencarbonate anions, borate anions, hydrogen phosphate anions, silicate anions, carbonate anions, alkylcarbonate anions and dicyanamide Anions are used. 3. Corrosion-protecting preparation according to claim 1 to 2, wherein anion-exchanging polymers are present, which are present in whole or in part in acetate form. 4. Corrosion-protecting preparation according to claim 1 to 2, wherein anion-exchanging polymers are contained, which are wholly or partly in acetate form, in benzoate form, in propionate form or in phthalate form. 5. An anti-corrosive composition according to claim 1 to 4, which further contains a poorly water-soluble metal phosphate. 6. Corrosion-protecting preparation according to claim 1 to 5, which contains calcium phosphate, strontium phosphate or barium phosphate as the metal phosphate. 7. Corrosion-protecting preparation according to claim 1 to 6, wherein contain as anion-exchange polymers polymers with imidazolium groups, pyridinium groups or phosphonium groups. 8. An anticorrosive composition according to claim 1 to 7, wherein the contained anion-exchanging copolymers are copolymers or terpolymers of monomers with functional groups suitable for the preparation of anion exchanger groups with t-butyl acrylate or t-butyl methacrylate. 9. Polymers for one of the anti-corrosive preparations according to claim 1 to 8, which are obtainable by free-radical copolymerization of: a) 0.1 mol% to 30 mol% of at least one monomer from the group of vinylbenzyltrimethylammonium acetate, vinylbenzyltrimethylammonium nitrate, 3- (4-ethenylbenzyl) -1-alkyl-2-alkyl-1H-imidazolium acetate, 3- (4-ethenylbenzyl) -1-alkyl-2-alkyl-1H-imidazolium nitrate, 3- (4-ethenylbenzyl) -1-alkyl-2-alkyl-1H-imidazolium nitrite, 1-vinyl-2-alkyl-3-alkylimidazolium acetate, 1 Vinyl-2-alkyl-3-alkyl-imidazolium nitrate and 1-vinyl-2-alkyl-3-alkyl-imidazolium nitrite, vinylbenzyltrimethylphosphonium acetate, vinylbenzyltrimethylphosphonium nitrate, vinylbenzyltrimethylphosphonium acetate, 2- (1H-imidazol-1-yl) ethyl methacrylate and 2- (1H) 1H-imidazol-1-yl) ethyl acrylate, wherein said alkyl radicals on said imidazolium monomers are C 1 -C 22 alkyl groups; b) 70 mol% to 99.9 mol% of at least one monomer from the group of t-butyl acrylate, t-butyl methacrylate, methyl methacrylate and other methacrylic acid esters and acrylic acid or methacrylic acid and other monomers. 10. Anti-corrosive preparation, the a) contains a compound having at least one epoxy group and at least one quaternary ammonium, quaternary phosphonium, sulfonium, imidazolium or pyridinium group in the form of at least one basic anion; and b) contains a compound having at least one epoxy group and at least one quaternary ammonium, quaternary phosphonium, sulfonium, imidazolium or pyridinium group in the form of a nitrate or nitrite ion.