Epoxy graphene zinc-containing coating as well as preparation method and application thereof

Abstract

The invention relates to an epoxy graphene zinc-containing coating as well as a preparation method and application thereof. The coating comprises a paint vehicle and a curing agent in a mass ratio of (10-14): 1, the paint comprises the following components in parts by mass: 10-20 parts of a first solvent, 10-20 parts of first epoxy resin, 1-3 parts of graphene slurry, 30-40 parts of zinc powder, 30-50 parts of a filler and 1-2 parts of an auxiliary agent, the graphene slurry comprises the following components in parts by weight: 75-95 parts of a second solvent, 3-6 parts of a macromolecular hyperdispersant, 1-5 parts of a carboxylate dispersant, 8-12 parts of graphene powder and 1-2 parts of a thickening agent. The graphene slurry which can stably exist for a long time is prepared by compounding the hyperdispersant and the carboxylate dispersant, and then the graphene and the epoxy resin are bridged together through the hydrogen-bond interaction of the dispersant, so that the graphene is uniformly dispersed in the coating, and the salt spray performance can reach more than 5000h under the conditions of low zinc content and low graphene dosage.

Description

Technical Field

[0001] The present invention belongs to the field of epoxy coatings, and particularly relates to an epoxy graphene zinc-containing coating, a preparation method thereof, and an application thereof. Background Art

[0002] Epoxy graphene zinc powder coating is a high-performance anti-corrosion coating, which has the advantages of flexible coating film, high adhesion, strong anti-corrosion property, etc., and is more and more widely used in the fields of bridges, high-speed railway stations, airports, petrochemical industry, wind power generation, etc. The anti-corrosion principle of epoxy zinc-rich coating (zinc powder content ≥ 60%) is the cathodic protection effect of zinc powder. In the coating film, zinc powder accumulates with each other to form a conductive path. Since the potential of zinc is lower than that of iron, zinc will react chemically prior to iron, thereby achieving the purpose of protecting the iron substrate.

[0003] Graphene has a conjugated structure and high electron mobility. After being added to the zinc powder coating, good conductivity between zinc powders can be ensured through the effective overlap of graphene sheets, thereby forming a conductive network. At the same time, since the overlap efficiency of the sheets is higher than that of spherical packing, adding graphene can also reduce the dosage of zinc powder to a certain extent.

[0004] However, it is very difficult to disperse graphene evenly in the zinc powder coating, and it is extremely easy to agglomerate in the coating, which results in a large dosage of graphene in the epoxy zinc powder coating, usually more than 4‰, leading to a high formulation cost and affecting its application; moreover, due to reasons such as poor anti-corrosion performance of commercially available epoxy curing agents, for the existing epoxy graphene zinc powder coating to achieve a salt spray resistance performance of 5000h, the dosage of zinc powder will still be more than 50%, which greatly wastes zinc resources, increases energy consumption and increases carbon dioxide emissions. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above technical deficiencies, and provide an epoxy graphene zinc-containing coating, a preparation method thereof, and an application thereof, so as to solve the technical problems in the prior art that the large dosages of zinc powder and graphene in the epoxy graphene zinc-containing coating lead to high costs, or it is difficult to balance the salt spray resistance performance.

[0006] To achieve the above technical purpose, the technical solution provided by the present invention is as follows: In the first aspect, the present invention provides an epoxy graphene zinc-containing coating, which includes a paint and a curing agent with a mass ratio of (10 - 14):1; by mass parts, the components of the paint include: 10 - 20 parts of a first solvent, 10 - 20 parts of a first epoxy resin, 1 - 3 parts of a graphene slurry, 30 - 40 parts of zinc powder, 30 - 50 parts of a filler, and 1 - 2 parts of an auxiliary agent; the components of the graphene slurry include: 75 - 95 parts of a second solvent, 3 - 6 parts of a high molecular type super dispersant, 1 - 5 parts of a carboxylate dispersant, 8 - 12 parts of a graphene powder, and 1 - 2 parts of a thickener.

[0007] In a second aspect, the present invention provides a method for preparing an epoxy graphene zinc-containing coating, comprising the following steps: adding a polymer-type superdispersant, a carboxylate dispersant, and graphene powder into a second solvent, stirring evenly, and then adding a thickener to obtain a graphene slurry; adding a first epoxy resin into a first solvent, mixing evenly, adding the graphene slurry and dispersing evenly, then adding zinc powder, fillers, and additives, and dispersing evenly to obtain a paint; mixing the paint and a curing agent evenly to obtain an epoxy graphene zinc-containing coating.

[0008] In a third aspect, the present invention provides an application of the epoxy graphene zinc-containing coating in preparing a heavy-duty anti-corrosion coating.

[0009] Compared with the prior art, the beneficial effects of the present invention include: In the present invention, by compounding a superdispersant and a carboxylate dispersant, graphene is evenly dispersed in a solvent to prepare a graphene slurry that can stably exist for a long time; then, using this graphene slurry to prepare a paint, through the hydrogen bond action of the dispersant, graphene and epoxy resin are bridged together, so that graphene is evenly dispersed in the coating. Therefore, the present invention can effectively reduce the zinc content and graphene content in the epoxy graphene zinc-containing coating. Under low zinc content and low graphene dosage, the salt spray performance can reach more than 5000h, and it can be used as a primer for heavy-duty anti-corrosion coatings, having good application prospects. Specific Embodiments

[0010] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the following further elaborates on the present invention in conjunction with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0011] Due to reasons such as the difficulty of evenly dispersing graphene in zinc powder coatings and the poor anti-corrosion performance of commercially available epoxy curing agents, for the existing epoxy graphene zinc powder coatings to achieve a salt spray resistance performance of 5000h, the zinc powder dosage will be above 50%, which greatly wastes zinc resources, increases energy consumption, and increases carbon dioxide emissions. At the same time, the dosage of graphene usually exceeds 4‰, resulting in a relatively high formulation cost and affecting its application.

[0012] Based on this, the present invention first prepares a graphene slurry, which can evenly disperse graphene in the coating, thereby reducing the dosage of graphene and the cost; then, through formula optimization, a paint for an epoxy graphene zinc-containing coating is prepared; and to improve the salt spray resistance of the coating and reduce the zinc powder dosage, a curing agent for a heavy-duty anti-corrosion epoxy coating is prepared. The thus-prepared epoxy graphene zinc-containing coating can achieve a salt spray resistance performance of more than 5000h under low zinc content (30%) and low graphene dosage (2‰). At the same time, this product has a low cost and broad application prospects.

[0013] In a first aspect, the present invention provides an epoxy graphene zinc-containing coating, comprising a paint and a curing agent in a mass ratio of (10 to 14):1; by mass parts, the components of the paint include: 10 to 20 parts of a first solvent, 10 to 20 parts of a first epoxy resin, 1 to 3 parts of a graphene slurry, 30 to 40 parts of zinc powder, 30 to 50 parts of a filler, and 1 to 2 parts of an additive; the components of the graphene slurry include: 75 to 95 parts of a second solvent, 3 to 6 parts of a polymer type superdispersant, 1 to 5 parts of a carboxylate dispersant, 8 to 12 parts of graphene powder, and 1 to 2 parts of a thickener.

[0014] Preferably, the first solvent includes xylene and n-butanol in a mass ratio of (5 to 10):(5 to 10).

[0015] Preferably, the first epoxy resin includes E20 epoxy resin.

[0016] Preferably, the filler includes ferrophosphorus powder.

[0017] Preferably, the additive includes organic bentonite; organic bentonite is added as a thickener in the paint of the present invention.

[0018] Preferably, the second solvent includes xylene and n-butanol in a mass ratio of (60 to 70):(15 to 25).

[0019] Preferably, the polymer type superdispersant includes polyester superdispersant SP-24000 (Shanghai Zhehua).

[0020] Preferably, the carboxylate dispersant includes alkyl ammonium salt of polycarboxylic acid ATU 203 (BYK). Preferably, the thickener includes polyamide wax powder.

[0021] Preferably, by mass parts, the curing agent includes 20 to 30 parts of phenylenediamine, 30 to 40 parts of a second epoxy resin, 15 to 25 parts of benzyl alcohol, and 20 to 25 parts of a third solvent.

[0022] More preferably, the phenylenediamine includes one or two of o-phenylenediamine, m-phenylenediamine, and p-phenylenediamine; More preferably, the second epoxy resin includes E12 epoxy resin.

[0023] More preferably, the third solvent includes xylene.

[0024] In a second aspect, the present invention provides a preparation method of an epoxy graphene zinc-containing coating, comprising the following steps: Adding the polymer type superdispersant, the carboxylate dispersant, and the graphene powder into the second solvent, stirring evenly, and then adding the thickener to obtain the graphene slurry; Add the first epoxy resin to the first solvent, mix evenly, then add the graphene slurry and disperse evenly. Next, add zinc powder, fillers and additives, and disperse evenly to obtain the paint; Mix the paint and the curing agent evenly to obtain the epoxy graphene zinc-containing coating.

[0025] Preferably, the preparation steps of the curing agent include: mixing p-phenylenediamine, the second epoxy resin, benzyl alcohol and the third solvent evenly, heating to 55-65 °C, keeping warm for 5-7 h, and then cooling to room temperature to obtain the curing agent.

[0026] In a third aspect, the present invention provides an application of the epoxy graphene zinc-containing coating in the preparation of a heavy anti-corrosion coating.

[0027] The main mechanism and advantages of the present invention are as follows: First, prepare the graphene slurry: by compounding a hyperdispersant and a carboxylate dispersant, uniformly disperse graphene in the solvent to prepare a graphene slurry that can stably exist for a long time; Secondly, prepare the graphene paint: through the hydrogen bond action of the dispersant, bridge graphene and epoxy resin together, so as to uniformly disperse graphene in the coating; Thirdly, prepare a self-made epoxy curing agent: through the ternary polymerization of p-phenylenediamine, E12 epoxy resin and benzyl alcohol, and utilize the corrosion resistance of the benzene ring and the flexibility of E12 resin to prepare an epoxy curing agent with both flexibility and corrosion resistance; In the present invention, the paint and the self-made epoxy curing agent are mixed in proportion to obtain the epoxy graphene zinc-containing coating; the present invention adopts the self-made graphene slurry and the self-made epoxy curing agent. The prepared coating still has excellent salt spray resistance (5000 h) when significantly reducing the zinc powder dosage (from 50% to 30%) and the graphene dosage (from 4‰ to about 2‰), and has a higher cost performance. At the same time, it can save zinc resources, reduce energy consumption and carbon dioxide emissions.

[0028] The following further elaborates on the present invention through specific examples.

[0029] Example 1 An epoxy graphene zinc-containing coating and its preparation method include the following steps: (1) Preparation of graphene slurry: Mix 640 g of xylene and 200 g of n-butanol evenly, then add 35 g of polyester hyperdispersant SP-24000 and 15 g of alkyl ammonium salt of polycarboxylic acid ATU 203. Disperse at a speed of 400 r / min for 5 minutes, then add 100 g of graphene powder, and then stir at a speed of 800 r / min for 1 h, and then add 10 g of polyamide wax powder to obtain the graphene slurry; (2) Preparation of paint: Mix 90 g of xylene and 60 g of n-butanol evenly, then add 150 g of E20 epoxy resin. Stir at a speed of 600 r / min for 10 minutes, then add 20 g of graphene slurry. Disperse at a speed of 800 r / min for 0.5 h, add 320 g of zinc powder, 350 g of ferrophosphorus powder, and 10 g of organic bentonite, and disperse at a speed of 1000 r / min for 1 h to obtain the paint; (3) Preparation of curing agent: Put 280 g of phenylenediamine, 330 g of E12 epoxy resin, 170 g of benzyl alcohol, and 220 g of xylene into a dropping kettle and mix evenly to obtain a mixture. Heat up to 60 °C, stir at a speed of 300 r / min, keep warm for 6 h, and then cool down to room temperature to obtain the curing agent; (4) Preparation of epoxy graphene zinc-containing coating: Mix the paint and the curing agent evenly according to a mass ratio of 12:1 to prepare the epoxy graphene zinc-containing coating. In this epoxy graphene zinc-containing coating, the zinc powder content is 30%, and the graphene content is 2‰.

[0030] Example 2 The difference from Example 1 is only that: adjust the dosage of phenylenediamine to 250 g and the dosage of benzyl alcohol to 200 g, and the other steps and conditions are the same as those in Example 1.

[0031] Example 3 The difference from Example 1 is only that: adjust the dosage of phenylenediamine to 300 g and the dosage of benzyl alcohol to 150 g, and the other steps and conditions are the same as those in Example 1.

[0032] Example 4 The difference from Example 1 is only that: adjust the dosage of the polymeric hyperdispersant to 30 g and the dosage of the carboxylate dispersant to 20 g, and the other steps and conditions are the same as those in Example 1.

[0033] Example 5 The difference from Example 1 is only that: adjust the dosage of the polymeric hyperdispersant to 40 g and the dosage of the carboxylate dispersant to 10 g, and the other steps and conditions are the same as those in Example 1.

[0034] Comparative Example 1 The difference from Example 1 is only that: use the commercially available graphene slurry KNG-CC401 (Xiamen Kenna) to replace the graphene slurry obtained in step (1), and the other steps and conditions are the same as those in Example 1.

[0035] Comparative Example 2 The difference from Example 1 is only that: use the commercially available curing agent NX-2003 (Cardolite, phenolic amine curing agent) to replace the curing agent obtained in step (3), and the other steps and conditions are the same as those in Example 1.

[0036] Comparative Example 3 The difference from Example 1 is only that: commercially available graphene slurry KNG-CC401 (Xiamen Kenna) is used to replace the graphene slurry obtained in step (1), and commercially available curing agent NX-2003 (Cardolite, phenolic amine curing agent) is used to replace the curing agent obtained in step (3), and other steps and conditions are the same as those in Example 1.

[0037] Comparative Example 4 The difference from Example 1 is only that: the dosage of phenylenediamine is adjusted to 190 g, and the dosage of benzyl alcohol is adjusted to 260 g, and other steps and conditions are the same as those in Example 1.

[0038] Comparative Example 5 The difference from Example 1 is only that: benzyl alcohol in step (3) is removed and replaced with xylene, and other steps and conditions are the same as those in Example 1.

[0039] Performance Test Coatings were prepared using the epoxy graphene zinc-containing coatings prepared in Examples 1-5 and Comparative Examples 1-5, and the salt spray performance of the coatings was tested according to GB / T 1771 "Paints and varnishes - Determination of resistance to neutral salt spray", and the test results are shown in Table 1.

[0040] Table 1 Comparison of Salt Spray Performance of Coatings

[0041] Remarks: The zinc powder content is 30% and the graphene content is 2‰ for all.

[0042] As can be seen from Table 1: under the conditions of low zinc powder dosage (30%) and low graphene dosage (2‰), the epoxy graphene zinc-containing coatings (Examples 1-5) prepared by the present invention can all achieve a salt spray resistance of more than 5000 h.

[0043] When commercially available graphene slurry is used (Comparative Example 1), since the graphene cannot undergo chemical bridging with the epoxy resin, the graphene cannot be uniformly dispersed in the coating, and its salt spray resistance is reduced by about 35% compared with Example 1.

[0044] When commercially available curing agent is used (Comparative Example 2), due to the poor anti-corrosion performance of the existing curing agent, the salt spray resistance of the coating is reduced by about 50% compared with Example 1.

[0045] When commercially available graphene slurry and commercially available curing agent are used (Comparative Example 3), due to the non-uniform dispersion of graphene in the coating and the poor anti-corrosion performance of the existing curing agent, its salt spray performance is the worst, and it is reduced by about 68% compared with the Example.

[0046] When the dosage of phenylenediamine decreases (Comparative Example 4), since the dosage of E12 remains unchanged and the dosage of benzyl alcohol increases, during the preparation of the curing agent, a large amount of phenylenediamine is consumed by the addition reaction, resulting in a decrease in the active hydrogen content of the curing agent, an excessive epoxy / amine ratio, and a decrease in the salt spray resistance of the coating film.

[0047] When the dosages of phenylenediamine and E12 remain unchanged and the curing agent does not contain benzyl alcohol (Comparative Example 5), during the preparation of the curing agent, phenylenediamine only reacts with E12, resulting in an increase in the active hydrogen content of the curing agent, an excessively low epoxy / amine ratio, and a significant decrease in the salt spray resistance of the coating film.

[0048] In summary, the present invention prepares a uniformly dispersed graphene slurry by compounding a polymer-type hyperdispersant and a carboxylate dispersant; prepares a paint by screening the amounts of epoxy resin, filler, zinc powder, graphene, etc.; prepares a curing agent with excellent performance through the ternary polymerization of phenylenediamine, E12 epoxy resin, and benzyl alcohol. The epoxy graphene zinc-containing coating prepared from the paint and the curing agent can achieve a salt spray performance of over 5000 h at a low zinc content (30%) and a low graphene dosage (2‰), and can be used as a primer for heavy-duty anti-corrosion coatings, showing good application prospects.

[0049] The specific embodiments of the present invention described above do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. An epoxy graphene zinc-containing coating, characterized in that: Including paint and curing agent in a mass ratio of (10-14):1; calculated by mass, The components of the paint include: 10-20 parts of a first solvent, 10-20 parts of a first epoxy resin, 1-3 parts of a graphene slurry, 30-40 parts of zinc powder, 30-50 parts of a filler and 1-2 parts of an additive; The components of the graphene slurry include: 75-95 parts of a second solvent, 3-6 parts of a polymer type super dispersant, 1-5 parts of a carboxylate dispersant, 8-12 parts of graphene powder and 1-2 parts of a thickener.

2. The epoxy graphene zinc-containing coating according to claim 1, characterized in that: The first epoxy resin includes E20 epoxy resin.

3. The epoxy graphene zinc-containing coating according to claim 1, characterized in that: The first solvent comprises xylene and n-butanol in a mass ratio of (5-10):(5-10); The filler includes ferrophosphorus powder; The auxiliary agent includes organic bentonite.

4. The epoxy graphene zinc-containing coating according to claim 1, characterized in that: The second solvent comprises xylene and n-butanol in a mass ratio of (60-70):(15-25); The thickener includes polyamide wax powder.

5. The epoxy graphene zinc-containing coating according to claim 1, characterized in that: The polymer type super dispersant includes polyester type super dispersant; the carboxylate type dispersant includes alkyl ammonium salt of polycarboxylic acid.

6. The epoxy graphene zinc-containing coating according to claim 1, characterized in that: The curing agent comprises 20 to 30 parts of phenylenediamine, 30 to 40 parts of a second epoxy resin, 15 to 25 parts of benzyl alcohol and 20 to 25 parts of a third solvent in parts by mass.

7. The epoxy graphene zinc-containing coating according to claim 6, characterized in that: The phenylenediamine includes one or two of o-phenylenediamine, m-phenylenediamine and p-phenylenediamine; The second epoxy resin includes E12 epoxy resin; The third solvent includes xylene.

8. The method for preparing the epoxy graphene zinc-containing coating according to any one of claims 1 to 7, characterized in that: The following steps are involved: Adding a polymeric hyperdispersant, a carboxylate dispersant and graphene powder into a second solvent, stirring evenly, and then adding a thickener to obtain a graphene slurry; The first epoxy resin is added to the first solvent, and after mixing evenly, the graphene slurry is added and dispersed evenly, and then zinc powder, filler and additive are added and dispersed evenly to obtain a paint; The paint and the curing agent are mixed evenly to obtain the epoxy graphene zinc-containing coating.

9. The method for preparing the epoxy graphene zinc-containing coating according to claim 8, characterized in that: The preparation steps of the curing agent include: uniformly mixing phenylenediamine, a second epoxy resin, benzyl alcohol and a third solvent, heating to 55-65° C., keeping the temperature for 5-7 hours and then cooling to room temperature to obtain the curing agent.

10. Use of the epoxy graphene zinc-containing coating as described in any one of claims 1 to 7 in the preparation of heavy-duty anti-corrosion coatings.

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