Corrosion inhibitor

Abstract

The present invention relates to a corrosion inhibitor additive for imparting corrosion resistance to metals and a corrosion inhibitor coating containing the additive. The corrosion inhibitor additive comprises a first corrosion inhibitor comprising an organic cation in a cation exchange resin and a second corrosion inhibitor comprising a phosphate compound. The corrosion inhibitor additive is intended for incorporation into a coating containing at least a polymeric binder.

Description

Technical Field

[0001] The present invention relates to a corrosion inhibitor and a corrosion protection coating provided for coating metals, particularly iron-based metals. The corrosion inhibitor also protects aluminum, magnesium, zinc, and their alloys (including galvanized steel), and thus, in this example, improves the corrosion resistance of the underlying steel.

Background Art

[0002] Corrosion inhibitors, sometimes referred to as corrosion-inhibiting pigments, currently exist in the form of low-solubility inorganic salt powders dispersed in organic coatings (coatings) and have been conventionally used to protect a wide range of metal surfaces including steel and galvanized steel. A typical steel coating system is shown in FIG. 1 and consists of a steel substrate 2, a metal coating 4 (for sacrificially protecting the steel substrate, typically made of zinc or a zinc alloy), a conversion coating 6 (which improves the adhesion between the metal coating and the organic coating and provides corrosion inhibition), a primer (undercoat) 8, and a barrier 10 (typically made of a polymer coating).

[0003] The primer can be composed of only a polymer, a polymer and a solvent, a polymer and water, 100% solids or a powder, and is mixed with a corrosion inhibitor such as zinc or strontium chromate. As shown in FIG. 2, when the barrier material is broken, inhibitory species derived from zinc or strontium chromate elute from the primer 8 and form a precipitate or a protective layer around the break point, thus protecting the underlying steel substrate 2. This is represented in FIG. 2.

[0004] Conventional rust preventives consist of poorly soluble chromium salts such as zinc or strontium chromate, which have environmentally unacceptable levels of toxicity. Alternative environmentally acceptable (Cr(vi)-free) rust pigments are used, which are typically based on poorly soluble phosphate technology, but which are always less effective than the chromate counterparts. This is at least in part a result of the low solubility of the phosphates. Thus, in a corrosive environment, a significant amount of time must elapse until there is a sufficient concentration of phosphate anions to react with the metal cations, resulting in a time lag in the progress of corrosion without being hindered. This problem has been solved to some extent by improving the solubility of the phosphates and typically in combination with a high loading of phosphates of 30% by weight of the total weight of the liquid coating (paint). A further problem associated with phosphates is that elution progresses over time, impairing the barrier protection of the coating. This also has an adverse environmental impact because it increases the amount of rust-preventing species required to protect the substrate for a reasonable period of time.

[0005] An on-demand corrosion inhibitor is also known, an example of which is shown in Patent Document 1 (WO2018 / 1978659), and this corrosion inhibitor species is stored within the coating until the point in time when it is needed (i.e., so-called "on-demand" release). The on-demand corrosion inhibitor may consist of an organic cation such as benzotriazolate, which is provided within a cation exchange resin such as a styrene / divinylbenzene copolymer having a negatively charged group such as a sulfonated group. When an electrolyte (consisting of cations and anions) is present in a corrosive environment, the cations are sequestered by the cation exchange resin, and this cation exchange resin releases benzotriazolate (protonated benzotriazole) into the electrolyte, and the electrolyte becomes deprotonated and changes into the form of anions. One end of the azole group forms a bond with the metal surface, and metal ions also release anodic dissolution. A precipitate is formed by the reaction of the benzotriazole anion and the metal cation, and a restraining film is formed that blocks the surface from further corrosion attack.

[0006] The present invention aims to provide an alternative corrosion inhibitor for protecting metals that has a high corrosion prevention effect and is also advantageous in terms of cost.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0008] According to one aspect of the present invention, - a first corrosion inhibitor containing an organic cation (organic cation) in a cation exchange resin and - a second corrosion inhibitor containing a phosphoric acid compound A corrosion prevention additive containing is provided.

[0009] It has been found that there is an unexpected synergistic effect between the actions of this first corrosion inhibitor and the second corrosion inhibitor. A smart corrosion inhibitor incorporating a first corrosion inhibitor that releases ions only in a corrosive environment and a second corrosion inhibitor that is not a smart corrosion inhibitor but releases phosphate ions into solution under normal aqueous conditions can provide corrosion protection and can yield significantly beneficial results. For example, under conditions of corrosion due to perforation of a coating on a metal, it has been found that the first corrosion inhibitor reacts immediately to form a precipitate with the released metal cations (metal positive ions). This reaction is very fast and can minimize the progress of corrosion. However, in such an aqueous environment, phosphate anions elute from the phosphate, reacting with the remaining metal cations to form a precipitate of metal phosphate. The composite precipitate formed from the first and second corrosion inhibitors provides a strong protective layer that prevents further corrosion.

[0010] Contrary to expected teachings, adding a second corrosion inhibitor in the form of a phosphate compound to a first corrosion inhibitor in the form of a smart corrosion inhibitor in the form of organic cations in a cation exchange resin would not be expected to result in beneficial performance compared to using the first corrosion inhibitor alone. A combination of low-performance rust inhibitors consisting of phosphate compounds would be expected to have a harmful effect on the first rust inhibitor or at least have no effect, but instead, it has been found that there is a synergistic effect. Furthermore, there is also the effect that the action of the first corrosion inhibitor on the second corrosion inhibitor reduces the dissolution rate of the second corrosion inhibitor from the coating.

[0011] The first corrosion inhibitor and the second corrosion inhibitor preferably consist of corrosion-inhibiting pigments or may each be individually referred to as a corrosion-inhibiting pigment.

[0012] The corrosion-inhibiting additive is particularly beneficial for protecting iron-based metals (e.g., mild steel), non-ferrous materials such as aluminum, and zinc-plated coatings of metals such as zinc-plated steel.

[0013] A phosphate compound is a compound that releases phosphate anions into a solution. Thus, in an aqueous environment, phosphate anions are released. These phosphate anions react with metal cations present in a corrosive environment to form solid precipitates. The phosphate compound may be composed of phosphates and / or polyphosphates and / or phosphosilicates (silicate phosphates). Examples of suitable phosphate compounds are one or more metal phosphates such as zinc phosphate, which is the most commercially common corrosion inhibitor pigment. This phosphate compound may be composed of polyphosphate compounds such as strontium, calcium, magnesium or aluminum polyphosphates. The advantage of using this polyphosphate compound is, for example, an improved dissolution rate compared to metal phosphates. Other suitable phosphate compounds are, for example, phosphosilicates such as calcium strontium phosphosilicate. The phosphate compound may consist of a mixture of a plurality of different phosphate compounds.

[0014] The expectation of adding an additive consisting of a first and a second corrosion inhibitor to the coating is that since phosphates are difficult to dissolve, whether the first corrosion inhibitor has no effect on dealing with corrosive ions through the release of organic cations or will have a harmful effect by influencing this process in some way. However, by using a phosphate-based second corrosion inhibitor, significant performance advantages have been shown. Phosphate-based rust inhibitors are known to form a protective layer, but due to their low solubility, usually this rate is very slow and corrosion may progress before the ions form precipitates in the solution. However, when organic cations are released at high speed, they interfere with the anode and cathode sites and react immediately with corrosion. However, phosphate cations are much slower than the organic cations from the first corrosion inhibitor, but are still gradually released at the corrosion site and then are found to effectively form on the anode site and the already formed precipitate. This means that a much more stable and long-term protective precipitate is formed than from the first corrosion inhibitor alone.

[0015] The first and second corrosion inhibitors are advantageously fine particles. This can impart corrosion protection to the substrate by dispersion within the coating. The first and second corrosion inhibitors may be provided as a mixture or in an unmixed state with instructions for the user to mix appropriately. However, in either form, the first and second corrosion inhibitors are not chemically bonded. Preferably, the mixture has a usable weight ratio of the first corrosion inhibitor to the second corrosion inhibitor in the range of 2:15 to 15:2 respectively. The mixture may have a usable weight ratio of the first corrosion inhibitor to the second corrosion inhibitor in the range of 1:5 to 5:1 respectively. More preferably, the mixture has a usable weight ratio of the first corrosion inhibitor to the second corrosion inhibitor in the ranges of 1:4 to 4:1 and 1:3 to 3:1 respectively.

[0016] The first and second corrosion inhibitors may form a coating for application to a substrate in combination with a polymer binder.

[0017] This coating can be applied to a metal substrate as part of a coating system such that other materials or additives are supplied into the coating and / or an additional coating layer is applied to the substrate. This coating can be referred to as a primer (undercoat) or a direct coating onto the metal or a powder coating (film). The solid, preferably particulate, first and second corrosion inhibitors incorporated within or together with the polymer binder form an organic paint, coating or primer. Thus, this paint or coating can be used to coat a substrate such as a metal object (e.g., sheet). The first and second corrosion inhibitors are dispersed through the coating.

[0018] Also according to the present invention, there is provided a coating for a metal substrate comprising a first corrosion inhibitor containing an organic cation in a cation exchange resin and a second corrosion inhibitor containing a phosphoric acid compound, wherein the first and second corrosion inhibitors are provided in a polymer binder.

[0019] The range of the weight ratio in which the first corrosion inhibitor and the second corrosion inhibitor can be used is preferably between 2:15 and 15:2, more preferably between 1:5 and 5:1, and still more preferably between 1:4 and 4:1, respectively.

[0020] The coating can have a weight ratio of 2 to 25% by weight of the first corrosion inhibitor in the wet form of the coating and 2 to 25% by weight of the second corrosion inhibitor in the wet form of the coating, and the total weight percentage of the first and second corrosion inhibitors in the combination in the coating does not substantially exceed 30%. Accordingly, the combined first and second corrosion inhibitors can be 4 to 30% by weight, more preferably 5 to 20% by weight of the total weight of the coating in the wet form. This amount is often expressed as the pigment volume concentration (PVC) of the dried coating and is typically within the overall range of 4 to 30 PVC. Exemplary embodiments of the various weights of the first and second corrosion inhibitors relative to the total weight of the coating are presented. This is in comparison to the soluble phosphate technology currently used as a corrosion inhibiting pigment, where approximately 30% by weight of the wet form of the coating is composed of soluble phosphate, which means that the phosphate loading is significantly reduced.

[0021] The polymer binder of the coating serves to hold the individual first and second corrosion inhibitors and bind them within the polymer. It is beneficial but not essential for the polymer to be liquid at room temperature and pressure and it can be provided in the form of solid fine particles for powder coating the substrate. In this embodiment, the polymer is also preferably provided as fine particles together with the first and second corrosion inhibitors in the form of fine particles dispersed in the polymer. It is beneficial for the first and second corrosion inhibitors to be solid at room temperature and pressure and be dispersed via the polymer binder. The polymer binder may be selected from one or more of acrylic, epoxy, polyurethane, polyester, alkyd, silicone or polyvinyl butyral.

[0022] An organic cation is any cation consisting of at least carbon and hydrogen atoms that falls within the general definition of an organic compound. The organic cation in the cation exchange resin provides a first corrosion inhibitor having an improved ability to impart corrosion resistance and beneficial properties that act as an environmentally acceptable smart release corrosion inhibitor. Such a corrosion inhibitor enables the dissociation of the organic cation from the cation exchange resin under conditions where a corrosive electrolyte is present, sequesters the protonated form of the ion (preferably benzotriazole), and can form a precipitate or barrier layer upon deprotonation to prevent further corrosion.

[0023] The organic cation is preferably an azole, oxime, or hydrophobic amino acid, and the azole is characterized as being any of a number of compounds characterized by a 5-membered ring containing at least one nitrogen atom. This organic cation is preferably a benzotriazole or a derivative thereof such as 5-methylbenzotriazole. Benzotriazole is a solid provided as a powder at room temperature and pressure, and protonation of benzotriazole yields a positively charged benzotriazole that is attracted to the cation exchange resin to provide a corrosion inhibitor. It has been found that organic cations consisting of a benzene ring, particularly benzotriazole, are beneficial.

[0024] The cation exchange resin, which may also be referred to as a cation exchange polymer, is preferably an insoluble matrix formed of a plurality of particles, sometimes referred to as beads. These beads may have a diameter in the range of 0.2 to 3.0 mm. This ion exchange resin provides ion exchange sites.

[0025] The cation exchange resin is preferably an organic cation exchange resin. This organic cation exchange resin may be a styrene / divinylbenzene copolymer having a negatively charged group such as a sulfonated group. It has been found beneficial that this organic cation exchange resin is an organic cation exchange resin that attracts organic cations to provide a corrosion inhibitor. Divinylbenzene is preferably a styrene-based divinylbenzene copolymer having a sulfonated functional group.

[0026] The irregular particle sizes of the first corrosion inhibitor and preferably the second corrosion inhibitor are preferably less than 100 microns, more preferably less than 50 microns, still more preferably less than 20 microns, and still more preferably less than 5 microns, depending on the use of the coating.

[0027] Also, according to the present invention, - A first corrosion inhibitor containing an organic cation in a cation exchange resin and - A second corrosion inhibitor composed of a phosphate compound and - A polymer binder and A method for producing a corrosion-inhibiting coating comprising combining them is provided.

[0028] The combination of the first and second corrosion inhibitors and the polymer binder is preferably mixed. The polymer binder may be in a liquid state when combined with the first and second corrosion inhibitors. The first and second corrosion inhibitors are each preferably in the form of irregularly formed particles, and preferably in the form of a powder within the size range described in the claims.

[0029] Also, according to the present invention, a method for protecting a metal substrate comprising applying a corrosion-inhibiting coating to the substrate, the corrosion-inhibiting coating comprising - A first corrosion inhibitor containing an organic cation in a cation exchange resin and - A second corrosion inhibitor containing a phosphate compound and - A polymer binder and A method consisting of is provided.

[0030] This corrosion prevention coating is preferably applied directly to a metal substrate or a pretreated metal substrate. When using powder coating technology, this coating is in solid (particle) form; otherwise, the polymer binder can be applied to the substrate in liquid form at room temperature and pressure. This corrosion prevention coating may be referred to as a primer.

[0031] The present invention will be illustrated only by way of example with reference to the following figures.

Brief Description of the Drawings

[0032]

Figure 1

Figure 2

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Figure 3b

Figure 3c

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Figure 3e

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Figure 4B

Figure 5

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Figure 10

Figure 11

Mode for Carrying Out the Invention

[0033] The present invention has been developed to provide an alternative corrosion inhibitor.

[0034] Referring to FIG. 3, there is a primer 8 in which first and second corrosion inhibitors 30, 32 are dispersed on a metal substrate 2. This primer is coated with a barrier coating 10. The first corrosion inhibitor 30 is composed of organic cations in a cation exchange resin and is provided in particulate form. Although only an example, the organic cation is benzotriazole or its derivative, and the cation exchange resin is a copolymer of styrene and / or divinylbenzene having a negatively charged sulfonated functional group. The second corrosion inhibitor 32 is composed of a phosphate compound such as zinc phosphate, strontium polyphosphate, or calcium strontium phosphosilicate (phosphosilicate), and this is also provided in particulate form. The first and second corrosion inhibitors are combined with a desired amount of a polymer binder for coating to provide a metal coating, which is applied to the metal substrate 2 in liquid form and dried before applying the barrier coating 10.

[0035] It is understood that the first and second corrosion inhibitors 30, 32 may be added to the polymer binder after combination or may be added independently. In any case, the particulate corrosion inhibitor is dispersed through the coating.

[0036] The coating contains 2 to 15% by weight of the first corrosion inhibitor of the coating in wet form and 2 to 15% by weight of the second corrosion inhibitor of the coating in wet form. Further, preferably, this coating may be 2 to 10% by weight of the first corrosion inhibitor of the coating in wet form and 2 to 10% by weight of the second corrosion inhibitor of the coating in wet form. There is a beneficial corrosion resistance effect over such a weight% range, and since the first corrosion inhibitor reduces the leaching rate from the second corrosion inhibitor, it has been found that a reduction in the relative weight% of the second corrosion inhibitor can be achieved. Also, it is preferable that the first corrosion inhibitor and the second corrosion inhibitor have a usable ratio of the first corrosion inhibitor to the second corrosion inhibitor in the range of 1:5 and 5:1, respectively.

[0037] Next, the step of protecting the metal substrate 2 will be described under the conditions of a corrosive environment due to the breakage of the protective film of the substrate. Referring to FIG. 3(b), the barrier coating 10 and the primer 8 are broken. Therefore, the corrosive ions 34 can communicate with the substrate 2, whereby it is affected by corrosion. Referring to FIG. 3(c), when there is an electrolyte (composed of cations and anions) containing the corrosive ions 34, the first corrosion inhibitor 30 acts by the cations being isolated by the cation exchange resin and the protonated benzotriazole being released into the electrolyte and deprotonated (this moderates the pH of the under film), and finally changing to its anionic form at a pH exceeding 7.2. Also, when benzotriazole becomes neutral, there is an effect that a barrier layer is formed on the metal surface. One end of the azole group binds to the metal surface and also binds to the metal ions released by anodic dissolution. The adsorbed benzotriazole suppresses the electron transfer reaction, and the precipitate 36 formed by the reaction of the benzotriazole anion and the metal cation is considered to block the surface against further corrosion attacks. This reaction is very fast and can minimize the progress of corrosion.

[0038] In addition to the reaction of the first corrosion inhibitor 30, under the conditions of such an aqueous environment, phosphate anions elute from the phosphate, which react with the remaining metal cations to form precipitates (or deposits) of metal phosphates 40. The precipitate of the combination formed from the first and second corrosion inhibitors provides a strong protective layer for preventing further corrosion. Thus, as shown in detail in FIG. 3(e), the exchange of corrosion ions with the ion exchange resin occurs rapidly. In a preferred embodiment, benzotriazolate (BTA) is rapidly released to form a film on the metal surface and complex with any dissolved metal ions 42. Thereafter, the phosphate has sufficient time to dissolve in the electrolyte. Therefore, regardless of whether phosphate anions immediately appear at a concentration sufficient to form a protective layer, the phosphate anions appear slowly, but when they appear, they react with the metal cations to surely form a continuous film and fill the gaps of BTA. The combination of the two precipitates is stacked in multiple layers.

[0039] The coating described above can be used in a multi-layer system on coated hot-dip galvanized (HDG) steel to protect against corrosion of the underlying film. It can also be used on uncoated steel to protect against corrosion.

[0040] In each of the following examples, the first corrosion inhibitor is composed of a negatively charged sulfonated functional group cation exchange resin and a benzotriazole cation in a divinylbenzene copolymer.

[0041] Figures 4(a) and 4(b) are comparative photographs of the same steel panel after 1000 hours in a corrosive environment. In Figure 4(a), a steel panel coated with a commercially available two-component (2-pack) epoxy primer having a composition containing 3 wt% zinc phosphate is compared. It can be seen that a cross is drawn on each panel, both on the coating and the panel, according to standard corrosion test procedures. This is compared with Figure 4(b) showing the same steel substrate coated with the same two-component epoxy primer to which 5 wt% of a particulate first corrosion inhibitor composed of organic cations in a cation exchange resin (benzotriazole cations in a negatively charged sulfonated functional group cation exchange resin and a divinylbenzene copolymer) is added. The significant reduction in corrosion shown in Figure 4(b) is readily apparent.

[0042] Figure 4(c) is another industrially available two-component epoxy primer having 3 wt% zinc phosphate, and this Figure 4(c) shows the degree of corrosion after 1000 hours. In comparison, Figures 4(d) and 4(e) show the same two-component epoxy primer with 5% and 1%, respectively, of the first corrosion inhibitor composed of organic cations in a cation exchange resin incorporated therein. It is clear that the inclusion of the first corrosion inhibitor has a significant effect on the visible reduction of corrosion.

[0043] Figures 4(f) and 4(g) show comparative examples of the same steel panel. In Figure 4(f), a two-component epoxy with 3 wt% zinc phosphate and a topcoat are used, while in Figure 4(g), in addition to the two-component epoxy and topcoat with the same wt% of zinc phosphate, 5 wt% of a first corrosion inhibitor containing organic cations in a cation exchange resin is additionally used. As shown in Figure 4(g), the use of a combination of zinc phosphate and the first corrosion inhibitor readily reveals a reduction in corrosion.

[0044] Figures 5(a) and 5(b) show the same steel panel. The panel in Figure 5(a) is coated with a commercially available single-layer direct to metal (DTM) primer containing 5% loading of a first corrosion inhibitor. The panel in Figure 5(b) is coated with a commercially available single-layer DTM primer containing only 25% zinc phosphate. For each panel, the primer is not coated with a topcoat. When tested under the ASTM B117 standard salt spray test conditions, the bond between the coating and the metal was significantly weakened and delamination (interlayer delamination) occurred. In each test, the degree of delamination varied due to a gentle mechanical action on the coating. In the panel containing only zinc phosphate in Figure 5(b), it is easy to see that the corrosion of the panel affects the adhesion of the coating to the panel and the primer has significantly peeled off from the panel. Conversely, as shown in Figure 5(a), in the panel where the primer contains only the first corrosion inhibitor, although there is some delamination, mechanical force is required to remove the coating, indicating that the first corrosion inhibitor is improved compared to the primer containing zinc phosphate. The important thing is that this effect is evident in commercially available DTM primers.

[0045] Figures 6(a) and 6(b) are schematic diagrams of a standard corrosion test known as a scanning Kelvin probe (SKP) delamination test. In this test, a metal substrate 2 is provided, and a test area 4 is defined between an adhesive tape 6 and an insulating tape guide 8. As shown in Figure 6(b), a test protective coating (protective film) 10 is spread across the test area 4 using a coating bar 12, thereby covering the test area. An adhesive tape / coating barrier 14 is provided to form an electrolyte well 16, and thus a corrosion site 18 is provided at the interface between the electrolyte and the test area 4. Corrosion can be monitored in real time using a scanning Kelvin tip probe 20. When an electrolyte acts on the interface between the coating and the base metal, it causes cathodic detachment failure, resulting in the destruction of the bond between the base metal and the coating (film). As corrosion is established and progresses, the front line of cathodic delamination moves along the test piece.

[0046] Referring to FIGS. 7(a) and 7(b), in FIG. 7(a), the influence of peeling on a test coating (test coating) made of polyvinyl butyral in ethanol (15.5% by weight) containing zinc phosphate and in FIG. 7(b) containing a first corrosion inhibitor is presented using the test apparatus shown in FIG. 6. The position of the electrolyte well 16 is shown. The coating shown in FIG. 7(b) does not contain zinc phosphate. The influence of peeling can be clearly seen when both test pieces are completely peeled. This is compared with the test results of FIG. 5 where peeling was reduced (not prevented) with a commercial coating rather than a simple test coating.

[0047] When directly comparing the results shown in FIG. 7, the results shown in FIG. 8 are obtained, and a test coating (test coating) made of polyvinyl butyral in ethanol containing both a first corrosion inhibitor and zinc phosphate was applied to a mild steel test piece. The coating in FIG. 8(a) contains 8% by weight of the first corrosion inhibitor and 5% by weight of zinc phosphate, and the coating in FIG. 8(b) contains 4% by weight of the first corrosion inhibitor and 2.5% by weight of zinc phosphate. It can be seen that the effect of delamination is small. Therefore, the synergistic effect of the first corrosion inhibitor and the metal phosphate regarding the reduction of corrosion is obvious.

[0048] Referring to FIGS. 9(a) and 9(b), the test results of hot-dip galvanized steel using the same coating and weight percentages as those used in the test results shown in FIGS. 8(a) and 8(b) are shown. When directly compared with the same substrate in FIG. 9(c) with a coating that does not contain the first corrosion inhibitor, it is clear that complete peeling has occurred. FIGS. 9(a) and 9(b) show a slight peeling effect. Here too, the significant synergistic effect by using both the first and second corrosion inhibitors described in the claims is demonstrated.

[0049] Figure 10 compares the coating (a) according to the invention recited in the claims with two known commercially available chromate coatings (b) and (c) for aerospace aluminum of 2024 T3. The coating tested in Figure 10(a) is the coating according to the invention containing a first corrosion inhibitor of 5PVC and a second corrosion inhibitor of 20PVC in a polymer binder, showing delamination after testing by a scanning Kelvin probe (SKP) delamination test. It is clear that the present invention strongly surpasses the conventional chromate-based coatings.

[0050] Figure 11 visually compares the presentation order of the same coatings shown in Figure 10 and cold-rolled steel. Here too, the effectiveness of the exemplary embodiments of the present invention is clearly visually shown.

[0051] It is believed that those skilled in the art will understand that the present invention is described only by way of example and that modifications and variations can be made without departing from the scope of protection conferred by the appended claims.

Claims

1. A corrosion prevention additive comprising a first corrosion inhibitor containing an organic cation of benzotriazole or its derivative in a cation exchange resin and a second corrosion inhibitor containing a phosphate compound, wherein the cation exchange resin is a styrene and / or divinylbenzene copolymer having a negatively charged group.

2. The corrosion prevention additive according to claim 1, wherein the phosphate compound consists of one or more metal phosphates.

3. The corrosion prevention additive according to claim 1, wherein the phosphate compound is a polyphosphate compound or a silicate compound.

4. The corrosion prevention additive according to claim 2, wherein the metal phosphate is zinc phosphate.

5. The corrosion prevention additive according to any one of claims 1 to 4, wherein the first corrosion inhibitor and the second corrosion inhibitor are fine particles.

6. The first corrosion inhibitor and the second corrosion inhibitor are provided as a mixture, and the usable weight ratio range of the first corrosion inhibitor and the second corrosion inhibitor is respectively 2:15 to 15:2, respectively 1:5 to 5:1, respectively 1:4 to 4:1, respectively 1:3 to 3:1, the corrosion prevention additive according to any one of claims 1 to 5.

7. A coating for a metal substrate comprising a first corrosion inhibitor containing an organic cation of benzotriazole or its derivative in a cation exchange resin and a second corrosion inhibitor containing a phosphate compound, wherein the cation exchange resin is a styrene and / or divinylbenzene copolymer having a negatively charged group, and the first corrosion inhibitor and the second corrosion inhibitor are provided in a polymer binder.

8. The coating according to claim 7, wherein the weight ratio of the first corrosion inhibitor and the second corrosion inhibitor is respectively between 2:15 and 15:2, respectively between 1:5 and 5:1, respectively between 1:4 and 4:1, respectively between 1:3 and 3:

1.

9. The coating according to claim 7, wherein the combined first corrosion inhibitor and second corrosion inhibitor are composed of 4 to 30% by weight of the coating weight in a wet form.

10. The coating according to claim 9, wherein the combined first corrosion inhibitor and second corrosion inhibitor are composed of 5 to 20% by weight of the coating weight in a wet form.

11. The coating according to any one of claims 7 to 10, wherein the polymer is a liquid at room temperature and room pressure.

12. The coating according to any one of claims 7 to 11, wherein the polymer binder is selected from one or more of acrylic, polyester, epoxy, silicone, alkyd polyurethane, or polyvinyl butyral.

13. A method for producing a corrosion prevention coating, comprising combining a first corrosion inhibitor containing an organic cation of benzotriazole or a derivative thereof in a cation exchange resin, a second corrosion inhibitor containing a phosphate compound, and a polymer binder, wherein the cation exchange resin is a styrene and / or divinylbenzene copolymer having a negatively charged group.

14. A method for protecting a metal substrate, comprising applying a corrosion prevention coating to the metal substrate, wherein the corrosion prevention coating comprises a first corrosion inhibitor containing an organic cation of benzotriazole or a derivative thereof in a cation exchange resin, a second corrosion inhibitor containing a phosphate compound, and a polymer binder, and the cation exchange resin is a styrene and / or divinylbenzene copolymer having a negatively charged group.

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