Epoxy powder coating resistant to long-term cathodic disbondment and method for its production

Abstract

The present application relates to the technical field of powder coating, and proposes an epoxy powder coating resistant to long-term cathodic disbonding and a preparation method thereof.The epoxy powder coating resistant to long-term cathodic disbonding comprises the following components in parts by weight: 40-60 parts of bisphenol A type epoxy resin, 10-30 parts of modified epoxy resin, 8-15 parts of curing agent, 15-25 parts of filler, 0.5-1.5 parts of leveling agent, 0.1-0.5 parts of degassing agent, and 0.1-0.5 parts of imidazole; the modified epoxy resin comprises brominated epoxy resin and isocyanate modified epoxy resin; and the curing agent comprises phenolic curing agent and boron amine complex.Through the technical solution, the problem of poor long-term cathodic disbonding resistance of the epoxy powder coating in the related art is solved.

Description

Technical Field

[0001] This invention relates to the field of powder coating technology, specifically to an epoxy powder coating resistant to long-term cathodic disbondment and its preparation method. Background Technology

[0002] For long-distance oil and gas pipelines today, corrosion prevention methods include applying anti-corrosion coatings and cathodic protection. The biggest and most insurmountable bottleneck for coatings is their susceptibility to localized defects, which can exacerbate corrosion of the substrate. Cathodic protection, without a coating, faces extremely high currents, resulting in high costs. Therefore, the best corrosion prevention method is to combine coatings and cathodic protection, achieving excellent corrosion protection while maintaining cost-effectiveness. However, cathodic protection requires minimal coating peeling under cathodic current conditions.

[0003] Epoxy powder coatings are applied as a single layer or 3PE structure underlayer for corrosion protection of substrates in long-distance oil and gas pipelines. Although epoxy powder coatings exhibit better cathodic disbondment resistance than epoxy coal tar pitch and coal tar enamel, traditional epoxy powder coatings use dihydroamine or phenolic curing agents to cure bisphenol A type epoxy resin. While short-term cathodic disbondment performance is good, the increasingly stringent requirements for service life and operating environment of long-distance pipelines necessitate coatings with the ability to maintain cathodic disbondment resistance over the long term, especially at higher temperatures. Therefore, it is necessary to develop epoxy powder coating products with resistance to long-term and high-temperature cathodic disbondment. Summary of the Invention

[0004] This invention proposes an epoxy powder coating resistant to long-term cathodic disbondment and its preparation method, which solves the problem of poor resistance to long-term cathodic disbondment in related technologies.

[0005] The technical solution of the present invention is as follows: This invention proposes an epoxy powder coating resistant to long-term cathodic disbondment, comprising the following components in parts by weight: 40-60 parts of bisphenol A type epoxy resin, 10-30 parts of modified epoxy resin, 8-15 parts of curing agent, 15-25 parts of filler, 0.5-1.5 parts of leveling agent, 0.1-0.5 parts of degassing agent, and 0.1-0.5 parts of imidazole; The modified epoxy resin includes brominated epoxy resin and isocyanate modified epoxy resin.

[0006] As a further technical solution, the filler is one or more of titanium dioxide, silica powder, carbon black, and fumed silica; the curing agent is a phenolic curing agent or a combination of a phenolic curing agent and a boronamine complex; the leveling agent is an organosilicon leveling agent and / or an acrylate leveling agent; the degassing agent is one or two of benzoin and polyethylene wax; the boronamine complex includes one or more of monoethylamine-boron trifluoride complex, n-hexylamine-boron trifluoride complex, and aniline-boron trifluoride complex.

[0007] As a further technical solution, the mass ratio of the brominated epoxy resin to the isocyanate-modified epoxy resin is 1:0.3~1.

[0008] As a further technical solution, the epoxy equivalent of the isocyanate-modified epoxy resin is 350~500g / eq.

[0009] As a further technical solution, the epoxy equivalent of the brominated epoxy resin is greater than that of the isocyanate-modified epoxy resin.

[0010] As a further technical solution, the epoxy equivalent of the brominated epoxy resin is 620~750 g / eq.

[0011] As a further technical solution, when the curing agent is a phenolic curing agent and a boronamine complex, the mass ratio of the phenolic curing agent to the boronamine complex is 1:0.1~0.3.

[0012] As a further technical solution, the boronamine complex is a hexylamine-boron trifluoride complex.

[0013] As a further technical solution, the filler is a sodium p-bromobenzenesulfinate modified filler.

[0014] As a further technical solution, the preparation method of the sodium p-bromobenzenesulfinate modified filler includes the following steps: dissolving sodium p-bromobenzenesulfinate in water and mixing it with the filler, drying it to obtain the sodium p-bromobenzenesulfinate modified filler; the mass ratio of sodium p-bromobenzenesulfinate to filler is 1:15~18.

[0015] In this invention, sodium p-bromobenzenesulfinate is used to modify the filler before it is added to components such as epoxy resin, which further improves the resistance of epoxy powder coating to long-term cathodic disbondment.

[0016] The present invention also proposes a method for preparing an epoxy powder coating resistant to long-term cathodic disbondment, comprising the following steps: mixing the components of the epoxy powder coating, extruding and crushing, and grinding to obtain the epoxy powder coating.

[0017] The working principle and beneficial effects of this invention are as follows: In this invention, by introducing brominated epoxy resin and isocyanate-modified epoxy resin into epoxy resin, the synergistic effect of brominated epoxy resin and isocyanate-modified epoxy resin significantly improves the resistance of epoxy powder coating to long-term cathodic disbondment. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] In the following examples and comparative examples, The type of bisphenol A epoxy resin is 904; The brominated epoxy resin with an epoxy equivalent of 210~240 g / eq is designated as YDB-228. The brominated epoxy resin with an epoxy equivalent of 620~680 g / eq is designated as YDB-406. The brominated epoxy resin with an epoxy equivalent of 690~750 g / eq is designated as YDB-408. The brominated epoxy resin with an epoxy equivalent of 900~1000g / eq is designated as YDB-410P. The isocyanate-modified epoxy resin with an epoxy equivalent of 350~500 g / eq, model Amanda 1177HTM(V), was purchased from Daqing Qinglu Langrun Technology Co., Ltd. The phenolic curing agent, model Amanda 969A-2, was purchased from Daqing Qinglu Langrun Technology Co., Ltd.

[0020] Example 1 An epoxy powder coating resistant to long-term cathodic disbondment comprises the following components in parts by weight: 60 parts bisphenol A type epoxy resin, 10 parts modified epoxy resin, 8 parts curing agent, 6 parts titanium dioxide, 13.3 parts silica powder, 0.5 parts carbon black, 0.2 parts fumed silica, 1 part acrylate leveling agent, 0.5 parts benzoin, and 0.5 parts imidazole. Among them, the modified epoxy resin is a brominated epoxy resin and an isocyanate modified epoxy resin with a mass ratio of 1:0.2. The epoxy equivalent of the brominated epoxy resin is 900~1000g / eq, and the epoxy equivalent of the isocyanate modified epoxy resin is 350~500g / eq. The curing agent is a phenolic curing agent; A method for preparing epoxy powder coating resistant to long-term cathodic disbondment includes the following steps: mixing the components of epoxy powder coating, extruding and crushing, and grinding to obtain epoxy powder coating.

[0021] Example 2 An epoxy powder coating resistant to long-term cathodic disbondment comprises the following components in parts by weight: 50 parts epoxy resin, 20 parts modified epoxy resin, 10 parts curing agent, 6 parts titanium dioxide, 11.4 parts silica powder, 0.5 parts carbon black, 0.2 parts fumed silica, 1 part acrylate leveling agent, 0.5 parts benzoin, and 0.4 parts imidazole. Among them, the modified epoxy resin is a brominated epoxy resin and an isocyanate modified epoxy resin with a mass ratio of 1:0.2. The epoxy equivalent of the brominated epoxy resin is 900~1000g / eq, and the epoxy equivalent of the isocyanate modified epoxy resin is 350~500g / eq. The curing agent is a phenolic curing agent; A method for preparing epoxy powder coating resistant to long-term cathodic disbondment includes the following steps: mixing the components of epoxy powder coating, extruding and crushing, and grinding to obtain epoxy powder coating.

[0022] Example 3 An epoxy powder coating resistant to long-term cathodic disbondment comprises the following components in parts by weight: 40 parts epoxy resin, 30 parts modified epoxy resin, 12 parts curing agent, 6 parts titanium dioxide, 9.6 parts silica powder, 0.5 parts carbon black, 0.2 parts fumed silica, 1 part acrylate leveling agent, 0.5 parts benzoin, and 0.2 parts imidazole. Among them, the modified epoxy resin is a brominated epoxy resin and an isocyanate modified epoxy resin with a mass ratio of 1:0.2. The epoxy equivalent of the brominated epoxy resin is 900~1000g / eq, and the epoxy equivalent of the isocyanate modified epoxy resin is 350~500g / eq. The curing agent is a phenolic curing agent; A method for preparing epoxy powder coating resistant to long-term cathodic disbondment includes the following steps: mixing the components of epoxy powder coating, extruding and crushing, and grinding to obtain epoxy powder coating.

[0023] Example 4 The only difference between this embodiment and Embodiment 3 is that the modified epoxy resin is a brominated epoxy resin and an isocyanate modified epoxy resin with a mass ratio of 1:0.3.

[0024] Example 5 The only difference between this embodiment and Embodiment 3 is that the modified epoxy resin is a brominated epoxy resin and an isocyanate modified epoxy resin with a mass ratio of 1:1.

[0025] Example 6 The only difference between this embodiment and Embodiment 3 is that the modified epoxy resin is a brominated epoxy resin and an isocyanate modified epoxy resin with a mass ratio of 1:1.2.

[0026] Example 7 The only difference between this embodiment and Embodiment 5 is that the epoxy equivalent of the brominated epoxy resin is 690~750 g / eq.

[0027] Example 8 The only difference between this embodiment and Embodiment 5 is that the epoxy equivalent of the brominated epoxy resin is 620~680 g / eq.

[0028] Example 9 The only difference between this embodiment and Embodiment 5 is that the epoxy equivalent of the brominated epoxy resin is 210~240 g / eq.

[0029] Example 10 The only difference between this embodiment and Example 8 is that the curing agent is a phenolic curing agent and a hexylamine-boron trifluoride complex with a mass ratio of 1:0.1.

[0030] Example 11 The only difference between this embodiment and Example 8 is that the curing agent is a phenolic curing agent and a hexylamine-boron trifluoride complex with a mass ratio of 1:0.3.

[0031] Example 12 The difference between this embodiment and Embodiment 11 is that the filler (titanium dioxide, silica powder, carbon black, fumed silica) was modified with sodium bromobenzenesulfinate. Specifically, the following steps were taken: 1g of sodium bromobenzenesulfinate was dissolved in 50g of water, 16g of the above filler was added and mixed, and dried to obtain sodium bromobenzenesulfinate modified filler.

[0032] Comparative Example 1 The only difference between this comparative example and Example 3 is that the modified epoxy resin is a brominated epoxy resin.

[0033] Comparative Example 2 The only difference between this comparative example and Example 3 is that the modified epoxy resin is an isocyanate-modified epoxy resin.

[0034] Comparative Example 3 The only difference between this comparative example and Example 3 is that no modified epoxy resin is added to the components of the epoxy powder coating.

[0035] The epoxy powder coatings prepared in Examples 1-12 and Comparative Examples 1-3 were used to obtain double-layer epoxy powder coating samples with a base layer thickness of 250 μm and a top layer thickness of 350 μm, respectively, according to the requirements of standard GB / T 39636-2020 "Technical Specification for Fusion-bonded Epoxy Powder Coating of Steel Pipelines". Cathodic disbondment resistance tests were conducted at 65℃, -1.5V, and 28 days. The water adhesion at 75℃ and 28 days and the bending performance at -30℃ and 3°C were also compared. The results are shown in the table below:

[0036] Compared with Comparative Examples 1-3, the epoxy powder coatings prepared in Examples 1-12 showed better resistance to cathodic disbondment, indicating that by introducing brominated epoxy resin and isocyanate-modified epoxy resin into the epoxy resin, and by utilizing the synergistic effect of brominated epoxy resin and isocyanate-modified epoxy resin, the resistance of epoxy powder coating to long-term cathodic disbondment was significantly improved.

[0037] Compared with Example 3, the epoxy powder coatings prepared in Examples 4-6 showed better resistance to cathodic disbondment, indicating that by changing the mass ratio of brominated epoxy resin and isocyanate-modified epoxy resin, the resistance of epoxy powder coatings to long-term cathodic disbondment was further improved; however, in Example 6, the low epoxy equivalent of the brominated epoxy resin resulted in a decrease in flexural properties.

[0038] Compared to Example 5, the epoxy powder coatings prepared in Examples 7-9 showed better resistance to cathodic disbondment. However, as the epoxy equivalent of the brominated epoxy decreased, the toughness of the coating in Example 9 decreased, and cracking occurred. In summary, Examples 7-8 exhibited superior resistance to cathodic disbondment and bending resistance, especially Example 8, which showed better resistance to cathodic disbondment, adhesion, and bending resistance when the epoxy equivalent was 620-680 g / eq.

[0039] Compared with Example 8, the epoxy powder coatings prepared in Examples 10-11 showed better resistance to cathodic disbondment, indicating that the combination of phenolic curing agent and boronamine complex further improved the long-term resistance of epoxy powder coatings to cathodic disbondment.

[0040] Compared with Example 11, the epoxy powder coating prepared in Example 12 has better resistance to cathodic disbondment, indicating that modifying the filler with sodium p-bromobenzenesulfinate before adding it to components such as epoxy resin further improves the long-term resistance of the epoxy powder coating to cathodic disbondment.

[0041] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An epoxy powder coating resistant to long-term cathodic disbondment, characterized in that, It comprises the following components in parts by weight: 40-60 parts of bisphenol A type epoxy resin, 10-30 parts of modified epoxy resin, 8-15 parts of curing agent, 15-25 parts of filler, 0.5-1.5 parts of leveling agent, 0.1-0.5 parts of degassing agent, and 0.1-0.5 parts of imidazole; The modified epoxy resin includes brominated epoxy resin and isocyanate modified epoxy resin. The mass ratio of the brominated epoxy resin to the isocyanate-modified epoxy resin is 1:0.3~1; The isocyanate-modified epoxy resin has an epoxy equivalent of 350~500 g / eq; The epoxy equivalent of the brominated epoxy resin is 620~750 g / eq.

2. The epoxy powder coating resistant to long-term cathodic disbondment according to claim 1, characterized in that, The filler is one or more of titanium dioxide, silica powder, carbon black, and fumed silica; the curing agent is a phenolic curing agent or a combination of a phenolic curing agent and a boronamine complex; the leveling agent is an organosilicon leveling agent and / or an acrylate leveling agent; the degassing agent is one or two of benzoin and polyethylene wax; the boronamine complex includes one or more of monoethylamine-boron trifluoride complex, n-hexylamine-boron trifluoride complex, and aniline-boron trifluoride complex.

3. The epoxy powder coating resistant to long-term cathodic disbondment according to claim 2, characterized in that, When the curing agent is a combination of a phenolic curing agent and a boronamine complex, the mass ratio of the phenolic curing agent to the boronamine complex is 1:0.1~0.

3.

4. The epoxy powder coating resistant to long-term cathodic disbondment according to claim 1, characterized in that, The filler is a sodium p-bromobenzenesulfinate modified filler.

5. The epoxy powder coating resistant to long-term cathodic disbondment according to claim 4, characterized in that, The preparation method of the sodium p-bromobenzenesulfinate modified filler includes the following steps: dissolving sodium p-bromobenzenesulfinate in water and mixing it with the filler, drying it to obtain the sodium p-bromobenzenesulfinate modified filler; the mass ratio of sodium p-bromobenzenesulfinate to filler is 1:15~18.

6. A method for preparing an epoxy powder coating resistant to long-term cathodic disbondment according to any one of claims 1 to 5, characterized in that, Includes the following steps: The components of the epoxy powder coating are mixed, extruded, crushed, and ground to obtain the epoxy powder coating.

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