DE102014207517A1 - Corrosion inhibitors, improved color and anti-corrosive coating - Google Patents

Abstract

The present invention is concerned with corrosion inhibitor preparations and anti-corrosive paints or anti-corrosive primers. Corrosion-protective paints, which contain quaternary alkylammonium hydroxides or functional polymers with these groups as well as quaternary alkylammonium nitrites or functional polymers with quaternary alkylammonium nitrite groups as well as an alkaline earth and alkali phosphate, guarantee an effective corrosion protection of iron alloys.

Description

Technical area

This invention is concerned with corrosion inhibitors and anticorrosive coatings. This invention is particularly concerned with corrosion inhibitors and anticorrosion coatings for iron, steel and other iron alloy articles. This invention further concerns the preparation of anticorrosive primer additives.

Background of the invention

Iron and steel are particularly affected by corrosion and significant costs are caused by the corrosion of iron and steel components exposed to rain and atmospheric atmospheric oxygen.

Effective conventional corrosion protection coatings for iron alloys contain materials such as metallic cadmium, red lead (Pb ₃ O _4), calcium plumbate or chromium (VI) compounds such as strontium chromate or zinc chromate, which increasingly regulated for reasons of environmental protection and safety at work or to be banned.

Other anti-corrosive coatings contain heavy metals such as zinc with less toxicity, but these are not electrochemically fully effective in the form of a subsequently applied paint because many of the metal particles in a paint are not electrically conductive to the base metal to be protected, which is to be cathodically protected from corrosion. Therefore, these zinc paints are less effective than electrodeposited or hot dip galvanized zinc coatings. Since it is not possible to galvanize steel structures or hot-dip galvanized with a layer of zinc, which are fixed (for example, on a building as a railing or other components) in a place of use, it is currently not possible satisfactorily, effective corrosion protection environmentally friendly materials for iron alloy parts.

Because environmentally friendly corrosion inhibitors and anticorrosive paints according to the prior art are much less effective than the above proven more toxic corrosion protection coatings or corrosion protection additives, which is why iron or steel parts that are protected with these environmentally friendly anticorrosive coatings, rust relatively easily.

For the above reasons, there is a need for an improved anticorrosive paint that effectively prevents corrosion and can be applied as a conventional paint.

Brief description of the invention

The present invention deals with an anticorrosive paint which solves these problems.

It has been found that alkyl quaternary ammonium hydroxides and quaternary alkyl phosphonium hydroxides, and especially polymers having these functional groups, effectively prevent the corrosion of steel and iron alloys. Oxidizing additives, in particular nitrites, considerably improve the corrosion protection by these organic corrosion inhibitors according to the invention. Quaternary alkyl ammonium nitrites and anion exchangers in nitrite form may preferably be used as the nitrite ion source. The corrosion protection afforded by these classes of compounds is also favored over rainwater by the presence of metal phosphates, especially alkaline earth phosphates and alkali phosphates. Therefore, a paint containing these compounds or polymers provides effective corrosion protection and is at the same time much more environmentally friendly than effective but less environmentally friendly corrosion inhibitors.

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:

1A shows the structure of hydroxide type quaternary ammonium compounds as corrosion inhibitors according to an embodiment of the present invention;

1B shows the structure of nitrate-form quaternary ammonium compounds as corrosion inhibitors according to an embodiment of the present invention;

2A shows the structure of functional polymers having quaternary ammonium groups in the hydroxide form as corrosion inhibitors as corrosion inhibitors according to another embodiment (2A) of the present invention obtainable by polymerization of allylamines;

2 B shows the structure of functional polymers with nitrate-form quaternary ammonium groups as corrosion inhibitors as corrosion inhibitors according to another embodiment (2A) of the present invention obtainable by polymerization of allylamines;

3A shows the structure of functional polymers having quaternary ammonium groups in the hydroxide form as corrosion inhibitors according to an embodiment (2B) of the present invention, which are obtainable by polymerization of vinylbenzyl chloride;

3B Figure 4 shows the structure of functional polymers with nitrate-form quaternary ammonium groups as corrosion inhibitors according to an embodiment (2B) of the present invention obtainable by polymerization of vinylbenzyl chloride;

4A shows the structure of functional copolymers having quaternary ammonium groups in the hydroxide form as corrosion inhibitors obtainable by copolymerizing allylamines with other monomers according to a third embodiment (3A) of the present invention;

4B shows the structure of functional copolymers with nitrate-form quaternary ammonium groups as corrosion inhibitors obtainable by copolymerizing allylamines with other monomers according to a third embodiment (3A) of the present invention;

4C shows the structure of functional copolymers with quaternary ammonium groups in the hydroxide or nitrite form as corrosion inhibitors, which are obtainable by copolymerization of diallyldimethylammonium salts with other monomers, according to a third embodiment (3A) of the present invention;

5A Figure 3 shows the structure of functional copolymer with quaternary ammonium groups in the hydroxide form according to one embodiment (Figure 3B) of the present invention, obtainable by copolymerization of vinylbenzyl chlorides with other monomers; and

5B Figure 4 shows the structure of functional quaternary ammonium nitrite-form copolymer according to one embodiment (Figure 3B) of the present invention obtainable by copolymerization of vinylbenzyl chlorides with other monomers.

These and 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

Effective corrosion protection is important to the usefulness of iron alloys that are affected by corrosion in the atmosphere. Many known anticorrosive coatings contain toxic heavy metals such as cadmium, lead oxide (Mennige, Pb ₃ O ₄ ), calcium plumbate or carcinogenic chromium (VI) compounds such as strontium chromate or zinc chromate, which for environmental and occupational safety reasons, for example in the EU regulations RoHS (2002 / 95 / EC) and the REACH Regulation (1907/2006) were increasingly regulated or banned.

Other anti-corrosive coatings include metals such as zinc, which must be applied by hot dip galvanizing or electroplating during manufacture, but which, for example, can not be applied to mounted objects on buildings. For example, it is almost impossible to subsequently apply such a protective layer on the iron parts of a mounted bridge at the site of the bridge. Colors that contain zinc particles are less effective than metallic zinc layers because only a fraction of the zinc particles in the paint make electrical contact with the base metal of iron.

Other corrosion inhibitors such as hydrazine, hydrazine salts or ascorbic acid, which are used, for example, in cooling water for corrosion protection in closed cooling circuits, are not compatible for use on an iron part or in a paint, because they are easily soluble in water and would be washed out by rainwater.

It has been found that polymers containing quaternary alkyl ammonium hydroxides, as well as functional polymers having such functional groups, effectively prevent the corrosion of iron alloys and steel. Inks containing these quaternary alkyl ammonium hydroxides or quaternary alkyl phosphonium hydroxides or polymers containing these quaternary alkyl ammonium hydroxide or quaternary alkyl phosphonium hydroxide groups, which can be obtained, for example, by polymerization of monomers having at least one alkyl ammonium group, for example in the hydroxide form, effectively protect iron and iron alloys against corrosion. This is especially true when combined with sparingly soluble salts such as alkaline earth phosphates.

Within this application quaternary arylalkylammonium hydroxides are considered to be equivalent to quaternary alkylammonium hydroxides. In addition, quaternary alkylphosphonium hydroxides or (the corresponding alkyl quaternary alkyl phosphonium hydroxide functional groups on a polymer) or tertiary alkyl sulfonium hydroxides should be treated as equivalent to quaternary alkyl ammonium hydroxides. quaternary Arylalkylphosphonium hydroxide groups should also be treated as equivalent to quaternary alkylammonium hydroxide groups. This refers to quaternary ammonium or phosphonium salts and all monomers as well as polymers having quaternary alkylphosphonium hydroxide groups which are also to be treated as equivalent to polymers having quaternary alkylammonium hydroxide groups.

Within this application, the term anion exchange polymers is used as a synonym for polymers according to the invention for paints having corrosion inhibitor properties, since these polymers act as strongly basic anion exchangers.

Within this application, the term "available through ..." is intended to describe a possible route of preparation for a product which is equally obtainable by an alternative route of preparation (such as chloromethylation of a polystyrene resin rather than polymerization of appropriate monomers). The preparation route specified by means of the term "obtainable by ..." may also be called a theoretical synthon (for example a tetraalkylammonium hydroxide), which in the case of a synthesis in practice for technical reasons by another starting material (eg the chloride) and an additional reaction step (eg, conversion of the chloride to the hydroxide) would be substituted.

The presence of additional Alkylammoniumnitriten improves the achievable corrosion protection quite considerably.

According to the first embodiment of the invention, anticorrosive preparations according to the invention, for example paints according to the invention, contain at least one quaternary alkylammonium hydroxide, as described in US Pat 1 and an analogous alkyl ammonium nitrite to effectively inhibit corrosion. The addition of the acting as oxidizing Alkylammoniumnitrite or nitrite ions promote corrosion protection by quaternary alkylammonium hydroxides. Paints according to a second preferred embodiment of the invention comprise at least one polymer which is obtainable by polymerization of monomers having at least one quaternary Alkalyammoniumhydroxid group, as these in 2 and 3 are shown. Such polymers can be used in the form of a fine dispersion of small polymer particles obtainable, for example, by milling polymer beads. For such polymers as a corrosion inhibitor, addition of oxidants (such as anion exchangers in the nitrite form) as inhibitors significantly improves the anticorrosion effect.

In the exclusive use of polymers with quaternary ammonium groups in nitrite form with calcium phosphate corrosion was found in some samples, however, even after a shorter exposure to water in corrosion tests, so that a combination according to the invention with polymers with quaternary ammonium groups in hydroxide form is strongly preferred.

Preferred anticorrosive preparations according to the invention contain a molar ratio of polymers with quaternary ammonium groups in nitrite form to polymers with quaternary ammonium groups in hydroxide form, based on the functional groups, between 20: 1 and 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 of less than 20: 1 may show too short a protective effect, whereas preparations with a molar ratio of more than 1:20 do not ensure satisfactory corrosion protection.

Colors with the addition of these preferred polymeric corrosion inhibitors according to the invention meet high environmental protection requirements since the polymers in question are completely insoluble in water. There is therefore no risk that the organic component, which is classified as highly hazardous to water (water hazard class 3), is washed out and gets into the environment. This is a significant advantage of the preferred second and third embodiments of the present invention.

Paints containing a solution of a polymer in a suitable solvent obtainable by polymerization of monomers having a quaternary alkylammonium group in the hydroxide or nitrite form, as described in U.S. Pat 4 respectively. 5 are most preferred. With such anticorrosion paints, it is possible to protect the entire surface of an iron part from corrosion.

These alkyl quaternary ammonium salts and polymers obtainable by polymerizing a monomer having at least one alkyl quaternary ammonium salt group are environmentally friendly. Therefore, paints containing these corrosion inhibitors may replace conventional anti-corrosive paints that are affected by the relevant EU regulations and directives.

Quaternary alkylammonium hydroxides such as tetrabutylammonium hydroxide, tetramethylammonium hydroxide or benzyltrialkylammonium hydroxides or the corresponding nitrites can be used as preferred corrosion inhibitors according to the first Embodiment of the present invention are replaced by other alkyl quaternary ammonium hydroxides or nitrites. Alkylphosphonium hydroxides can also be used as corrosion inhibitors.

Paints containing a dispersion of finely ground, strongly basic anion exchangers, as obtainable by chloromethylation of polystyrene and subsequent conversion to quaternary alkyl ammonium groups in hydroxide form, as described in US Pat 2 and 3 and under trade names such as "DOWEX MONOSPHERE 550A UPW" from Dow Chemical Company, Midland, MI, USA or "AMBERLITE IRA 402" (RTM) or "AMBERSEP 900" (RTM) from Rohm & Haas Company, Philadelphia, PA. USA are more preferred according to the second embodiment of the invention.

A maximum particle size of the ground anion exchange particles according to this embodiment of less than 250 μm is preferred, a particle size of less than 30 μm is more preferred and a particle size of less than 10 μm is most preferred. A particle size of less than 3 microns is optimal. Particles larger than 250 μm in diameter cause unevenness in the coating.

Anti-corrosive paints according to the second and third embodiments of the present invention contain at least one polymer containing quaternary alkylammonium groups in hydroxide or nitrite form. A preparation containing several different polymers can also be used.

The use of a polymer having quaternary alkylammonium hydroxide or alkylammonium nitrite groups, which is soluble in solvents, is most preferred. Polymers that are soluble in organic solvents such as acetone, toluene, xylene, tetrahydrofuran, dimethylsulfoxide (DMSO), dimethylformamide, alcohol or a mixture of such solvents are preferred, although polymers used in other solvents (such as N-methylpyrrolidinone (NMP) or a mixture thereof with other solvents) are also usable.

However, as polymers having novel alkylammonium groups, it is also possible to use reactive resins, such as, for example, As epoxy resins are used, which harden by a crosslinking reaction on the object to be protected.

Paints or primers containing alkyl quaternary ammonium quaternary groups may further contain polymers comprising an alkali-resistant polymer such as a polyolefin such as polystyrene, polystyrene copolymers such as polystyrene-butadiene copolymers, SEBS or SBS, polyethylene copolymers such as poly (vinyl alcohol -co-ethylene), although other alkali-resistant polymers such as epoxy resins or polyurethane-based or polyacrylamide-based paints may also be suitable.

In addition, the mole fraction of polymers having quaternary alkylammonium hydroxide groups in coatings according to the second embodiment of the present invention should be appropriately selected. A mass-related ion exchange capacity of 10 ^-3 meq / g to 7.1 meq / g is preferred although larger capacities may also be useful. A mass-related capacity of 10 ^-2 meq / g to 1.2 meq / g is more preferable, and a capacity of 0.1 meq / g to 1.2 meq / g is most preferable. Preparations with weight-related ion exchange capacities of less than 10 ^-3 meq / g do not prevent corrosion for extended periods of time, while preparations with a capacity greater than 7.1 meq / g are difficult to produce.

Functional copolymers obtained by polymerization and subsequent alkylation of allylamine and conversion into the free hydroxide or nitrite form or by polymerization of quaternary allylalkylammonium salts such as diallyldimethylammonium chloride and subsequent conversion into the hydroxide or nitrite form (see 4 ) are preferred according to a third embodiment of the present invention. Alternatively, such functional polymers as those described in U.S. Pat 5 are prepared by a reaction of a polymer having an alkyl halide group such as polyvinyl benzyl chloride with an amine such as trimethylamine. Copolymers which are preparable by copolymerization of allylamine with a monomer stable in strongly alkaline medium (such as an alkene such as butadiene or styrene) and subsequent alkylation and conversion into free quaternary alkylammonium hydroxide groups and which have the lowest possible solubility in water, are optimal. These copolymers can also by copolymerization of quaternary allylalkylammonium salts such. For example, diallyldimethylammonium chloride can be prepared with alkali-resistant monomers such as styrene and subsequent conversion to the hydroxide form.

Corrosion-protective paints according to the present invention contain at least one copolymer containing quaternary alkylammonium hydroxide groups. A preparation containing several different copolymers can also be used.

In addition, corrosion-protective inks according to the invention additionally contain an anion-exchanging copolymer in the nitrite form. In the exclusive use of anion exchangers in nitrite form with calcium phosphate corrosion was found in some samples, however, even after a shorter exposure to water in corrosion tests, so that a combination according to the invention with anion-exchanging copolymers in hydroxide form is highly preferred.

In order to ensure the compatibility of the above primers according to the invention with subsequent color layers, an intermediate layer or a topcoat which is resistant to strong bases, such as, for example, paints based on polyolefins, such as polystyrene, in particular polystyrene-butadiene copolymers or alkali-resistant epoxy resin coatings obtained by reaction be cured with amines used. The latter epoxy paints are preferred, although other paints such as polyurethane paints may also be used.

The most preferred inks include corrosion inhibitors of the invention and an alkali-resistant paint (containing at least one alkali-stable polymer system such as amine-cured epoxy resins, which may further contain at least one pigment, at least one plasticizer, and at least one UV stabilizer if desired).

The above anticorrosion paints of the present invention may also be used by powder coating using thermoplastic polymers or thermosetting resins.

Preferred catalysts for the preparation of functional polymers according to the invention are azo compounds such as AIBN (azobisisobutyronitrile) or peroxides such as BPO (dibenzoyl peroxide), t-butyl hydroperoxide, alkali metal persulfates or hydrogen peroxide. More preferred are azo compounds such as 2,2'-azobis (methyl-2-methylpropionates).

Preferred quaternary alkylammonium hydroxides or nitrites according to the first embodiment of the present invention as in 1 have substituents R ₁ to R ₄ as C ₁ -C ₈ alkyl groups. R ₁ can also be selected as an aryl system such as a phenyl radical, substituted phenyl or naphthyl groups. More preferably, substituents R ₁ to R _{4 are} each selected as C ₁ to C ₄ alkyl groups. Most preferred are symmetrically substituted quaternary alkyl ammonium salts with R ₁ = R ₂ = R ₃ = R ₄ selected as C ₁ -C ₄ alkyl groups although other substituents such as R ₁ = hydroxyethyl could also be useful.

Useful polymers for coating formulations according to the second embodiment of the present invention include polymers having quaternary alkyl ammonium groups in hydroxide form, such as polymers available commercially as strongly basic anion exchangers or soluble anion exchangers, which are known in the art 2 and 3 are shown.

Preferred quaternary Alkylammoniumhydroxidgruppen or alkylammonium nitrite groups of polymers according to the third embodiment of the present invention as described in 4 and 5 also have alkyl groups R ₁ -R ₃ of C ₁ -C ₈ alkyl groups. R ₁ can also be selected as an aryl system such as a phenyl radical, a substituted phenyl radical or a naphthyl radical. More preferred as R ₁ -R _{3 are} lower alkyl groups, especially C ₁ -C ₄ alkyl groups. The substituents R ₄ -R ₇ depend on the other monomer of the copolymer. For example, R ₄ -R _{6 may be selected} as hydrogen and R ₇ may be selected as the phenyl group for a styrene monomer of the copolymer. As a preferred ratio of the monomers, a mole fraction is chosen so that the copolymer obtained is soluble in organic solvents such as acetone, butyl acetate or toluene, but the copolymer remains insoluble in water. In addition, a suitable molar ratio of monomers with quaternary alkylammonium hydroxide groups (x (MN ⁺ OH ^- ) = n (MN ⁺ OH ^- ) / n _ges. ) Or alkylammonium nitrite groups, ie the ratio of the molar amount of these monomers to the total molar amount of all Monomers selected. As the bulk capacity of the resulting copolymer having quaternary alkylammonium groups, a value of 10 ^-5 meq / g to 2.0 meq / g is preferred, although larger capacities would also be advantageously used. A capacity of 10 ^-3 meq / g to 1.1 meq / g is more preferable, a capacity of 10 ^-2 meq / g to 1.1 meq / g is most preferable, a capacity of 0.1 meq / g to 1.1 meq / g optimal. The same mass capacities are selected if a preparation of a plurality of such copolymers or a preparation of copolymers and quaternary alkylammonium hydroxide anion exchange resins is used. Bulk capacities below 10 ^-5 meq / g are less effective in preventing corrosion over extended periods of time, while copolymers with capacities greater than 2.0 meq / g are difficult to produce.

When other non-functionalized polymers are present in said anticorrosion paint or anticorrosive coating, the above referred to in the mass capacity of the above Copolymers are increased so that the mass-related capacity of the entire preparation is within the limits above. For example, when adding unfunctionalized polymer in a paint consisting of 30 mole percent copolymer and 70 mole percent unfunctionalized polymer, the bulk capacity of the above copolymer should be increased by a factor of three, ie one Capacity from 0.3 meq / g to 3.3 meq / g would be optimal.

The second monomer for the preparation of the copolymer is selected as a monomer which provides an alkali-resistant polymer. Preferred monomers are alkenes such as styrene, unsubstituted or substituted ethylenes, propylenes, butadiene, tetrafluoroethylene, hexafluoropropene or vinylidene fluoride, vinyl chloride, although other monomers may also be useful.

The above copolymers can be used with other alkali-resistant polymers or alkali-resistant pigments such as phthalocyanines, titanium dioxide, etc. in one color or as a component of a primer.

Anticorrosion paint according to the invention with anion exchanger polymers with groups -NR ₃ ⁺ X ^q- (in the hydroxide and nitrite form, ie X ^- = OH ^- , X ^- = NO ₂ ^- ) additionally contains a heavy one in a preferred embodiment of the present invention water-soluble salt Me _n Y _m with another anion Y ^z- , which is bound more strongly by said anion exchanger. Within this patent application, the term "auxiliary corrosion inhibitor" is used for said sparingly water-soluble salts.

Suitable salts for this purpose are metal salts, in particular alkaline earth metal salts and alkali metal salts, although it is also possible to use salts with organic cations (quaternary alkylammonium salts) or anions (for example citrates). Preference is given to salts with anions which themselves develop anticorrosion effects, but bind more strongly to anion exchangers than nitrite ions, in particular phosphates and chromates, but also molybdate, tungstates and titanates.

In a particularly preferred embodiment of the invention, both the counter anion X ^q- in the anion exchange resin and the anion Y ^{z- of} the sparingly water-soluble salt are chosen so that both act as corrosion inhibitors for iron alloys. The use of strongly basic anion-exchange resins, or copolymers with strongly basic anion exchanger in the hydroxide form (dg With anions X ^q = OH ^-) with anions such as phosphate ions (ie, sparingly water-soluble phosphate is more preferred, although anion exchange resins in of other forms with corrosion inhibitor anions such as anion exchange resins in the nitrite, nitrate or hydrogen phosphate form (ie X ^q = NO ₂ ^- , NO ₃ ^- , HPO ₄ ^2- ) and sparingly water soluble salts such as Chromates, molybdates or tungstates or other multiply charged anions may also be useful Corrosion promoting anions such as chloride ions which promote pitting despite passivation should be avoided.

According to a more preferred embodiment of the invention, an alkaline earth salt is used as the sparingly water-soluble salt, although other salts such as alkali phosphates (eg, lithium phosphate or the slightly soluble sodium phosphate) or transition metal salts would also be useful. Calcium phosphate Ca ₃ (PO ₄ ) ₂ , strontium phosphate Sr ₃ (PO ₄ ) ₂ and barium phosphate Ba ₃ (PO ₄ ) ₂ and lithium phosphate (Li ₃ PO ₄ ) are more preferred, although other metal phosphates (such as zinc phosphate) or hydrogen phosphates may also be useful can. Strontium phosphate Sr ₃ (PO ₄ ) ₂ is most preferred.

Without being bound to any theory, it is believed that the sparingly water-soluble salt in the paint layer slowly dissolves in contact with water to a low equilibrium concentration. It is believed that the thus released low concentration anions from the salt are slowly exchanged with the anions in the ion exchange resin (or copolymer having anion exchange functionality) and thereby slowly release anions in the eluate which effectively counteract the metal surface by passivation Protect corrosion. With a low solubility of the salt (c (Y ^z ) ≈10 ^-7 mol / l), this process can be delayed over long periods of time in order to protect a corrosion-protective environment over long periods by delayed release of corrosion-protecting anions (X ^q = OH ^). , NO ₂ ^- ).

Equilibrium concentrations of anions from the salt Y ^z of c (Y ^z ) ≈ 10 ^-5 mol / l to 10 ^-7 mol / l for pure salt in pure water are preferred, concentrations of c (Y ^z ) ≈ 10 ^{- 6} mol / l to 10 ^-7 mol / l are more preferable. For metal salts with metal cations such as alkaline earth metal Me ²⁺ (z = 2) are the preferred values for the solubility L because of the relationship between the solubility product L and the above saturation concentration c (Y ^z) L = 8/27 c (Y ^{z) 5} between about 3 10 ^-26 (mol / l) ⁵ and 3 10 ^-36 (mol / l) ⁵ . Equilibrium concentrations c (Y ^z- ) ^greater than 10 ^-5 moles or corresponding solubility products greater than 3 10 ^-26 (mol / l) ⁵ provide a preparation which releases too fast an excessive concentration of inhibiting anions, while an equilibrium concentration c (Y ^z- ) below 10 ^-7 mol / l and a corresponding solubility product below 3 10 ^-36 (mol / l) ⁵ the release of anticorrosive anions X ^q- too much delay. The use of a mixture of salts such. B. several alkaline earth phosphates with different solubility products is possible. It is likewise possible to choose a small amount of the salt (for example as phosphate) as easily soluble alkali phosphate, in order to ensure rapid passivation of the exposed base metal for the immediate prevention of corrosion processes in the case of a new scratch in the paint layer down to the base metal.

A ratio of the molar amount n of the salt (auxiliary corrosion inhibitor) to the mass-related capacity w of the entire anion exchange resin of n / w = 0.01 to 0.67 - depending on the exposure to salts (such as road salt) - preferably for alkaline earth metal phosphates Me ₃ (PO ₄ ) ₂ , a ratio n / w of 0.1 to 0.67 is more preferred and a ratio n / w of between 0.25 and 0.67 is most preferred. For other salts with anions Y ^{z- of} a salt Me _n Y _m , the preferred ratio n / w is between 0.01 and m / z, the more preferred ratio between 0.1 and m / z. A ratio n / w over m / z is of little value, since the salt would release only a low equilibrium concentration of corrosion-protecting anions Y ^z- , while at a ratio of less than 0.01 a erfindungsmässe preparation without external salt exposure only for a short time corrosion-protective Anions X ^q would release.

Inks or primers according to the invention may also contain additional corrosion inhibitors such as molybdate. Paints or primers according to the invention may also contain UV stabilizers and plasticizers.

Inks or primers according to the invention can also be used on parts made of iron alloys that are galvanized or hot-dip galvanized.

The following examples illustrate the best mode of carrying out embodiments of the invention. Example 1 illustrates the preparation of strontium phosphate (Sr ₃ (PO ₄ ) ₂ ), Example 2 the use of anticorrosive formulations containing ground anion exchangers in hydroxide and nitrite form.

EXAMPLES

example 1

Preparation of Strontium Phosphate Sr ₃ (PO ₄ ) ₂

0.2162 g strontium nitrate (pa, Fluka, Taufkirchen) are dissolved in 21.6892 ml demineralised water (For all solutions, for washing and all tests, water in ion chromatographic grade, <1 μg / kg anions was used). 4.3508 g of potassium dihydrogen phosphate K ₂ HPO ₄ (Biochemica ultra grade, Fluka, Taufkirchen) in 4.0844 g demineralized water and 3.7462 g of a solution of 0.3016 g potassium hydroxide (86% KOH, pa, Fluka, Taufkirchen) in 3.8167 g demineralized water were added. All solutions were cooled to + 10 ° C. The strontium nitrate solution was added dropwise to the stirred solution of potassium hydrogen phosphate and potassium hydroxide. The resulting suspension of Sr ₃ (PO ₄ ) ₂ .4H ₂ O was filtered off with a glass suction funnel (porosity 4, covered with an additional filter paper Schleicher & Schuell, Germany, No. 595), the precipitate with demineralised water, absolute ethanol ( Riedel de Haen, Taufkirchen), absolute diethyl ether (Fluka AG, Buchs, Switzerland) and dried for several hours in a vacuum desiccator over silica gel. Subsequently, the product was converted to 500 ° C by heating in an oven at 250 ° C for 45 minutes in anhydrous Sr ₃ (PO ₄ ) ₂ and heating in a quartz crucible for 30 minutes.

Example 2

Preparation of anion exchangers in nitrite form

3.3934 g anion exchanger DOWEX 550A UPW (RTM) is suspended in 9.1 g demineralized water. A solution of 2.5966 g of sodium nitrite in 9.4 g of demineralized water is added and the suspension is stirred for 12 hours with a magnetic stirrer. Subsequently, the ion exchanger is sucked off with a glass frit and washed several times with demineralized water.

Example 3

Demonstration of the anti-corrosive effect

From a 250 mm × 500 mm steel sheet (EAN 4001116381041, Alfer Aluminum GmbH, 79793 Wutöschingen, http://products.alfer.com/en/Products/Hardware/combitech-system-Sheets-and-accessories/Sheets-steel/Sheet-raw-steel.html ) samples of 50 mm × 50 mm are cut out and cleaned with acetone (Fluka, Taufkirchen). 0.2449 g of anion exchanger DOWEX 550A UPW (RTM) in the hydroxide form and 0.3160 g of anion exchanger from Example 2 above in the nitrite form are combined with a 1 ml of a solution of 0.5260 sodium phosphate dodecahydrate (Na 3 (PO 4) .12H ₂ O, Fluka, Taufkirchen). in 10.5119 g of demineralized water applied to the sheet sample. A strip of filter paper (Whatman S & S, No. 595) is placed on the sheet and moistened with demineralized water and kept moist. The sample shows no corrosion for extended periods of time.

Example 4

Demonstration of corrosion-protective long-term effect

As in Example 3, an iron sheet is coated with corrosion-protective polymers. As phosphate calcium phosphate or strontium phosphate from Example 1 is added. The samples show no corrosion over long periods of many days.

Example 5

Comparative sample 1

2.82 g of poly (vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP, Sigma-Aldrich, Taufkirchen) are dissolved in 22.14 g of acetone. To obtain a more homogeneous dispersion, the solution is irradiated intensively with ultrasonic waves for one hour. In a corrosion test as in Example 3, a steel sheet is coated with the resulting solution of PVDF-HFP in acetone. Within a few hours, the metal sheet shows significant corrosion on all defects of the paint layer.

Example 6

Comparative sample 2

One of the above sheet metal specimens is painted with a commercial zinc phosphate-based anticorrosion paint to a square area of 20 mm × 20 mm in the middle. The sheet shows severe corrosion on the uncoated surface in less than 5 hours.

Example 6

Production of a corrosion protection varnish

0.25 g of DOWEX 550A UPW (RTM) anion exchanger in hydroxide form (Sigma-Aldrich, Taufkirchen) and 0.25 g of anion exchanger in nitrite form from Example 2 are finely ground with a mortar and pestle (or a ball mill). To the resulting ion exchange powder is added 0.15 g of calcium phosphate (or 0.15 g of strontium phosphate from Example 1) and dispersed in a solution of 2.82 g of poly (vinylidene fluoride-co-hexafluoropropene) (PVDF-HFP) in 22.14 g of acetone from Example 5. The suspension is applied as anticorrosive paint on an iron sheet 50 mm × 50 mm.

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 corrosion inhibitor preparations according to the invention for the protection of other metal alloys than iron alloys. 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, which are susceptible of public disclosure with this description, and the contents of all such articles and documents are incorporated 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 was expressly stated. Thus, unless expressly stated otherwise, each feature disclosed is merely an example of only a generic order of equivalent or similar features.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited non-patent literature

• http://products.alfer.com/en/Products/Hardware/combitech-system-Sheets-and-accessories/Sheets-steel/Sheet-raw-steel.html [0069]

Claims (10)

Anticorrosive preparation containing at least one polymer having nitrite-form organic ammonium groups and at least one salt. An anticorrosive composition according to claim 1 which additionally contains at least one polymer having organic ammonium hydroxide groups. Anticorrosive preparation according to claim 1 to claim 2, which contains polymers with quaternary ammonium groups as polymers with organic ammonium groups. Anticorrosive preparation according to claim 1 to claim 3, which contains as anionic resins with organic ammonium groups as polymers with organic ammonium groups. An anticorrosive composition according to any of claims 1 to claim 4, wherein said quaternary ammonium hydroxide polymers and said quaternary ammonium nitrite polymers are water-insoluble polymers. An anticorrosive paint containing a corrosion protection composition according to claim 1 to claim 5 and an organic solvent for the polymers contained. An anticorrosive composition according to claim 1 to claim 6 wherein said salt is selected from at least one of calcium phosphate, strontium phosphate, barium phosphate, lithium phosphate, sodium phosphate, potassium phosphate and ammonium phosphate. An anticorrosive preparation according to claim 1 to claim 7, wherein as said salt at least one salt selected from the group of molybdate, tungstates, titanates or chromates. Anticorrosive preparation containing at least one quaternary ammonium hydroxide and at least one quaternary ammonium nitrite. An anticorrosive paint containing a anticorrosion composition according to claim 9, at least one polymer and an organic solvent for the polymers contained therein.

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