Modified polyaniline-epoxy zinc-rich primer

Abstract

The invention discloses a modified polyaniline-epoxy zinc-rich primer, which is prepared from the following ingredients in parts by mass: 30 to 50 parts of epoxy resin matrixes, 40 to 60 parts of zinc powder, 5 to 15 parts of diatomite modified polyaniline compounds, 10 to 20 parts of curing agents, 20 to 40 parts of solvents and 1 to 5 parts of auxiliary agents. The diatomite is adopted to modify polyaniline, so that the conductivity of the obtained material can be improved, the use amount of zinc powder is reduced, and the production cost is reduced; the added polyaniline has passive film forming ability, and the diatomite has good adsorbability, so that the corrosion-resistant service life of the obtained modified polyaniline-epoxy zinc-rich primer can be effectively prolonged.

Description

Technical Field

[0001] The invention belongs to the technical field of anti-corrosion coatings, and in particular relates to a modified polyaniline-epoxy zinc-rich primer. Background Art

[0002] Epoxy zinc-rich coatings, a core material in the heavy-duty corrosion protection field, rely on the sacrificial anodic effect of zinc powder for its protection mechanism: the zinc powder forms a conductive network in the coating, corroding before the base metal, thereby delaying the rust of the metal substrate. However, the zinc powder content in traditional epoxy zinc-rich coatings must reach above 70wt% to form a continuous conductive path. This high zinc ratio brings significant drawbacks:

[0003] Currently, zinc is a strategic resource with volatile prices. High zinc content contributes to high coating costs. Furthermore, zinc production is energy-intensive, and the release of zinc ions after coating aging can pollute waterways and soil, contradicting the trend toward green chemistry. Furthermore, excessive zinc powder reduces coating density, leading to decreased adhesion (conventional zinc-rich coatings have a cross-hatch adhesion of only 3-4 MPa) and poor impact resistance (often below 50 kg·cm in the ASTM D2794 test). Furthermore, zinc sludge can easily accumulate in humid environments, accelerating coating peeling.

[0004] To reduce zinc content, researchers have attempted to introduce conductive polymers (such as polyaniline) as auxiliary anti-corrosion components. However, the rigid molecular chains and strong π-π interactions of polyaniline easily lead to its aggregation in epoxy resin (particle size is usually >1μm), forming local defects that serve as corrosion diffusion channels.

[0005] Prior art has proposed using carbon nanotubes (CNTs) to load polyaniline, leveraging the CNTs' conductive network to enhance the coating's charge transfer efficiency. However, CNTs are expensive and difficult to disperse uniformly. Other researchers have used montmorillonite intercalated with polyaniline, exploiting its layered structure to limit the migration of corrosive media. However, the stacking of montmorillonite sheets hinders the adsorption and release of corrosion-inhibiting ions, and the modification process requires multiple ion exchanges, making it complex.

[0006] In view of this, this application is hereby filed. Summary of the Invention

[0007] The present invention aims to solve one of the technical problems in the related art to at least a certain extent. To this end, an embodiment of the present invention provides a modified polyaniline-epoxy zinc-rich primer.

[0008] In one aspect, an embodiment of the present invention provides a modified polyaniline-epoxy zinc-rich primer, comprising the following components in parts by weight: 30-50 parts of an epoxy resin matrix, 40-60 parts of zinc powder, 5-15 parts of a diatomaceous earth-modified polyaniline composite, 10-20 parts of a curing agent, 20-40 parts of a solvent, and 1-5 parts of an additive.

[0009] In some embodiments, the diatomite-modified polyaniline composite is prepared by a method comprising the following steps: dispersing diatomite in an acidic solution of aniline monomer, then adding an oxidant to carry out a polymerization reaction, and filtering, washing, drying, and grinding the reaction product to obtain the diatomite-modified polyaniline composite.

[0010] In some embodiments, the particle size of the diatomaceous earth is 5 to 30 μm;

[0011] and / or, the mass ratio of the diatomaceous earth to the aniline monomer is 1:1 to 1:3;

[0012] And / or, the acidic solution is a hydrochloric acid solution or a sulfuric acid solution, and the concentration of the acidic solution is 0.5 to 2 mol / L.

[0013] In some embodiments, the oxidizing agent comprises at least one of ammonium persulfate, potassium persulfate, or sodium persulfate;

[0014] and / or, the molar ratio of the oxidant to the aniline monomer is 1:1 to 1:1.2;

[0015] And / or, the reaction temperature of the polymerization reaction is 0-5° C., and the reaction time is 6-12 hours.

[0016] In some embodiments, the epoxy resin matrix includes at least one of E-44 epoxy resin, E-20 bisphenol A epoxy resin, and E-51 epoxy resin.

[0017] In some embodiments, the zinc powder is spherical zinc powder with a particle size of 325-800 mesh.

[0018] In some embodiments, the curing agent includes at least one of polyamide, cardanol-modified amine, and Mannich base.

[0019] In some embodiments, the solvent includes at least one of xylene and n-butanol.

[0020] In some embodiments, the auxiliary agent includes at least one of silicon dioxide, polyamide wax, silicone leveling agent, and defoaming agent.

[0021] On the other hand, the embodiments of the present invention further provide the use of the modified polyaniline-epoxy zinc-rich primer in preparing corrosion-resistant coatings for steel parts.

[0022] The advantages and beneficial effects of the embodiments of the present invention are as follows:

[0023] The embodiment of the present invention optimizes the design of the epoxy zinc-rich primer formulation and introduces a diatomaceous earth-modified polyaniline composite, so that the obtained modified polyaniline-epoxy zinc-rich primer has good conductivity, a low zinc powder dosage, low cost, and excellent corrosion resistance and life. DETAILED DESCRIPTION

[0024] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments derived by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Unless otherwise defined, technical or scientific terms used in the present invention shall have the same meaning as commonly understood by persons having ordinary skills in the field to which the present invention belongs.

[0026] Where values ​​are described herein as ranges, it should be understood that such disclosure includes disclosure of all possible sub-ranges within that range, as well as specific values ​​falling within that range, regardless of whether a specific value or sub-range is explicitly stated.

[0027] As used herein, the words "comprise," "include," and "includes" and variations thereof mean that additional elements or integers may be included although permitted but not specifically described.

[0028] In this article, the term "and / or" is merely a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0029] In one aspect, an embodiment of the present invention provides a modified polyaniline-epoxy zinc-rich primer, comprising the following components in parts by weight: 30-50 parts of an epoxy resin matrix, 40-60 parts of zinc powder, 5-15 parts of a diatomaceous earth-modified polyaniline composite, 10-20 parts of a curing agent, 20-40 parts of a solvent, and 1-5 parts of an additive.

[0030] In some embodiments, the diatomite-modified polyaniline composite is prepared by a method comprising the following steps: dispersing diatomite in an acidic solution of aniline monomer, then adding an oxidant to carry out a polymerization reaction, and filtering, washing, drying, and grinding the reaction product to obtain the diatomite-modified polyaniline composite.

[0031] In the embodiment of the present invention, polyaniline is modified using diatomaceous earth. Diatomaceous earth has a porous structure and a high specific surface area. It can serve as a dispersion carrier for polyaniline and effectively prevent the agglomeration of polyaniline nanoparticles, thereby forming a uniform conductive network in the coating. The sacrificial anode effect of zinc powder synergistically enhances the overall conductivity of the coating, making electron transmission between zinc powder particles more efficient. This can reduce the amount of zinc powder used while ensuring the cathodic protection effect, thereby reducing production costs.

[0032] Furthermore, by introducing polyaniline, the embodiments of the present invention can also cooperate with the cathodic protection effect of zinc powder, and further extend the corrosion resistance life of the coating through the passivation film forming ability of polyaniline (inhibiting the oxidation reaction of the metal substrate) and the adsorption property of diatomaceous earth (capturing corrosive media such as chloride ions).

[0033] In some embodiments, the diatomaceous earth has a particle size of 5 to 30 μm. The inventors have found through research that if the particle size of the diatomaceous earth is too large, its specific surface area will be significantly reduced, thereby weakening the diatomaceous earth's adsorption capacity for aniline monomer and causing uneven in-situ polymerization. However, if the particle size is too small, the particles are likely to agglomerate, blocking the porous structure of the diatomaceous earth, thereby hindering the diffusion and polymerization of the aniline monomer.

[0034] And / or, the mass ratio of the diatomaceous earth to the aniline monomer is 1:1 to 1:3. The inventors have found through research that if the amount of aniline monomer added is too high, excessive free polyaniline will be generated, destroying the structural stability of the composite; but if the amount of aniline monomer added is too small, the polymerization coverage of the diatomaceous earth surface will be insufficient, the conductive network will be incompletely constructed, and the cathodic protection efficiency will be reduced. Therefore, in the embodiment of the present invention, the amount of aniline monomer added is controlled within the above range;

[0035] And / or, the acidic solution is a hydrochloric acid solution or a sulfuric acid solution, and the concentration of the acidic solution is 0.5 to 2 mol / L.

[0036] In some embodiments, the oxidizing agent comprises at least one of ammonium persulfate, potassium persulfate, or sodium persulfate;

[0037] and / or, the molar ratio of the oxidant to the aniline monomer is 1:1 to 1:1.2;

[0038] And / or, the reaction temperature of the polymerization reaction is 0-5° C., and the reaction time is 6-12 hours. The inventors have found through research that if the polymerization reaction temperature is too high, the reaction rate will be too fast, the molecular weight distribution will become broad, and the conductivity and thermal stability of the obtained diatomite-modified polyaniline composite will be reduced; however, if the reaction temperature is too low, the reaction kinetics will be hindered, the polymerization will be incomplete, and the conversion rate of aniline monomer will be reduced.

[0039] And / or, the drying method is vacuum drying, and the vacuum drying temperature is 60-80° C.; if the drying temperature is higher than 80° C., it is easy to cause the risk of polyaniline dedoping, resulting in loss of conductivity.

[0040] In some embodiments, the epoxy resin matrix includes at least one of E-44 epoxy resin, E-20 bisphenol A epoxy resin, and E-51 epoxy resin.

[0041] In some embodiments, the zinc powder is spherical with a particle size of 325-800 mesh. Compared to zinc powders of other shapes, the spherical zinc powder used in the present invention has a higher bulk density, which can reduce the amount of epoxy resin used and the porosity, and provide a more uniform conductive network, thereby improving the efficiency of cathodic protection current distribution.

[0042] In some embodiments, the curing agent includes at least one of polyamide, cardanol-modified amine, and Mannich base.

[0043] In some embodiments, the solvent includes at least one of xylene and n-butanol.

[0044] In some embodiments, the additive comprises at least one of silica, polyamide wax, a silicone leveling agent, and a defoamer. It should be noted that the components of the additives can be added by those skilled in the art as needed to enhance the functionality of the resulting modified polyaniline-epoxy zinc-rich primer. Furthermore, the specific material selection of the defoamer and other raw materials is not particularly limited and can be selected by those skilled in the art as needed.

[0045] On the other hand, the embodiments of the present invention further provide the use of the modified polyaniline-epoxy zinc-rich primer in preparing corrosion-resistant coatings for steel parts.

[0046] The following are non-limiting examples and comparative examples of the present invention. It should be noted that the comparative examples are not prior art and are provided solely for comparison with the examples and are not intended to limit the present invention. Unless otherwise noted, the various raw materials used in the examples and comparative examples are conventional commercially available products or can be prepared by known methods.

[0047] Example 1

[0048] This embodiment provides a modified polyaniline-epoxy zinc-rich primer, comprising the following components in parts by mass: 30 parts of epoxy resin matrix, 60 parts of zinc powder, 5 parts of diatomaceous earth modified polyaniline composite, 10 parts of curing agent, 30 parts of solvent, and 5 parts of additive.

[0049] In this embodiment, a diatomaceous earth-modified polyaniline composite is prepared by a method comprising the following steps: dispersing diatomaceous earth with a particle size of 30 μm in an acidic hydrochloric acid solution of aniline monomer (wherein the mass ratio of diatomaceous earth to aniline monomer is 1:1; the concentration of the hydrochloric acid solution is 1 mol / L), followed by adding ammonium persulfate (the molar ratio of ammonium persulfate to aniline monomer is 1:1), and conducting a polymerization reaction at 5° C. for 6 h. After the reaction is completed, the reaction product is filtered, then repeatedly washed until neutral, and then vacuum dried at 60° C. until the mass is constant, and then ground to obtain a diatomaceous earth-modified polyaniline composite.

[0050] In this embodiment, the epoxy resin matrix is ​​E-44 epoxy resin.

[0051] In this embodiment, the zinc powder is spherical zinc powder with a particle size of 325 meshes.

[0052] In this embodiment, the curing agent is cardanol-modified amine.

[0053] In this embodiment, the solvent is xylene.

[0054] In this embodiment, the auxiliary agent is a mixture of 1.5 parts of fumed silica, 2 parts of polyamide wax, 0.8 parts of BYK-331 type silicone leveling agent, and 0.7 parts of BYK-066N type defoaming agent.

[0055] Example 2

[0056] This embodiment is substantially the same as embodiment 1, except that the mass fraction of the diatomaceous earth modified polyaniline composite in the modified polyaniline-epoxy zinc-rich primer in this embodiment is 10 parts.

[0057] Example 3

[0058] This embodiment is substantially the same as embodiment 1, except that the mass fraction of the diatomaceous earth modified polyaniline composite in the modified polyaniline-epoxy zinc-rich primer in this embodiment is 15 parts.

[0059] Example 4

[0060] This embodiment is substantially the same as embodiment 1, except that in the preparation of the diatomite-modified polyaniline composite in this embodiment, the mass ratio of diatomite to aniline monomer is 1:2.

[0061] Example 5

[0062] This embodiment is substantially the same as embodiment 1, except that in the preparation of the diatomite-modified polyaniline composite in this embodiment, the mass ratio of diatomite to aniline monomer is 1:3.

[0063] Comparative Example 1

[0064] This comparative example provides an epoxy zinc-rich primer, which is basically the same as Example 1, except that the epoxy zinc-rich primer in this comparative example does not contain a diatomaceous earth-modified polyaniline composite.

[0065] Comparative Example 2

[0066] This comparative example provides an epoxy zinc-rich primer, which is basically the same as Example 1, except that: the epoxy zinc-rich primer component of this comparative example does not contain a diatomaceous earth-modified polyaniline composite, but only contains diatomaceous earth in the same mass fraction.

[0067] Comparative Example 3

[0068] This comparative example provides an epoxy zinc-rich primer, which is basically the same as Example 1, except that the epoxy zinc-rich primer in this comparative example does not contain a diatomaceous earth-modified polyaniline composite, but only contains the same mass fraction of polyaniline.

[0069] Comparative Example 4

[0070] This comparative example provides a modified polyaniline-epoxy zinc-rich primer, which is basically the same as Example 1, except that: in the modified polyaniline-epoxy zinc-rich primer component of this comparative example, the mass fraction of the diatomaceous earth modified polyaniline composite is 20 parts.

[0071] The performance tests of the products obtained in the above examples and comparative examples were carried out, and the results are shown in Table 1.

[0072] Table 1

[0073]

[0074]

[0075] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples without contradiction.

[0076] Although the embodiments of the present invention have been shown and described above, it will be understood that the above embodiments are illustrative and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

Claims

1. A modified polyaniline-epoxy zinc-rich primer, characterized in that: The invention comprises the following components in parts by mass: 30-50 parts of epoxy resin matrix, 40-60 parts of zinc powder, 5-15 parts of diatomite modified polyaniline compound, 10-20 parts of curing agent, 20-40 parts of solvent and 1-5 parts of auxiliary agent.

2. The modified polyaniline-epoxy zinc-rich primer according to claim 1, characterized in that: The diatomite-modified polyaniline composite is prepared by a method comprising the following steps: dispersing diatomite in an acidic solution of aniline monomer, then adding an oxidant to carry out a polymerization reaction, and filtering, washing, drying, and grinding the reaction product to obtain the diatomite-modified polyaniline composite.

3. The modified polyaniline-epoxy zinc-rich primer according to claim 2, characterized in that: The particle size of the diatomaceous earth is 5 to 30 μm; And / or, the mass ratio of the diatomaceous earth to the aniline monomer is 1:1 to 1:3; And / or, the acidic solution is a hydrochloric acid solution or a sulfuric acid solution, and the concentration of the acidic solution is 0.5 to 2 mol / L.

4. The modified polyaniline-epoxy zinc-rich primer according to claim 2, characterized in that: The oxidant comprises at least one of ammonium persulfate, potassium persulfate or sodium persulfate; and / or, the molar ratio of the oxidant to the aniline monomer is 1:1 to 1:1.2; And / or, the reaction temperature of the polymerization reaction is 0-5° C., and the reaction time is 6-12 hours.

5. The modified polyaniline-epoxy zinc-rich primer according to claim 1, characterized in that: The epoxy resin matrix includes at least one of E-44 epoxy resin, E-20 bisphenol A epoxy resin, and E-51 epoxy resin.

6. The modified polyaniline-epoxy zinc-rich primer according to claim 1, characterized in that: The zinc powder is spherical zinc powder with a particle size of 325 to 800 meshes.

7. The modified polyaniline-epoxy zinc-rich primer according to claim 1, characterized in that: The curing agent includes at least one of polyamide, cardanol-modified amine, and Mannich base.

8. The modified polyaniline-epoxy zinc-rich primer according to claim 1, characterized in that: The solvent includes at least one of xylene and n-butanol.

9. The modified polyaniline-epoxy zinc-rich primer according to claim 1, characterized in that: The auxiliary agent includes at least one of silicon dioxide, polyamide wax, organic silicon leveling agent and defoaming agent.

10. Use of the modified polyaniline-epoxy zinc-rich primer according to any one of claims 1 to 9 in preparing corrosion-resistant coatings for steel parts.

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