Hyperbranched polysiloxane coating corrosion inhibitor and preparation method thereof, hyperbranched polysiloxane epoxy anticorrosive paint and preparation method and application thereof

Abstract

The invention provides a hyperbranched polysiloxane coating corrosion inhibitor and a preparation method thereof, a hyperbranched polysiloxane epoxy anticorrosive paint and a preparation method and application thereof. The hyperbranched polysiloxane coating corrosion inhibitor is prepared by catalytic reaction of p-dimethylaminobenzaldehyde and small molecular silane in an alcoholic solution. The coating comprises 30-50 parts of epoxy resin, 20-35 parts of a hyperbranched polysiloxane coating corrosion inhibitor, 5-10 parts of an active diluent, 2-2.5 parts of a silane coupling agent, 15-30 parts of filler, 1.5-2.5 parts of an auxiliary agent and 15-20 parts of a curing agent. Compared with the prior art, an imine group in hyperbranched polysiloxane and a metal substrate form a stable complex, the stable complex is adsorbed on the metal surface to form a protective film, the erosion rate of a corrosive medium to the metal substrate is effectively reduced, the corrosion resistance of a coating is improved, meanwhile, the coating prepared by adopting the reactive diluent is high in solid content and good in corrosion resistance, and the service life of the coating is prolonged. VOC emission in the paint film curing process is low.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and in particular relates to a hyperbranched polysiloxane coating corrosion inhibitor and a preparation method thereof, a hyperbranched polysiloxane epoxy anticorrosive coating and a preparation method and application thereof. Background Art

[0002] Applying anti-corrosion coatings on metal surfaces is an effective way to slow down metal corrosion. Adding corrosion inhibitors to the coating will improve the comprehensive protective effect of the coating. The coating corrosion inhibitors used in the early days mainly contained lead or chromium compounds. These two types of compounds have a long history of use and good effects. However, due to the pollution caused by lead and chromium compounds to the environment, with the increasing awareness of environmental protection, research and development of environmentally friendly coating corrosion inhibitors has become a top priority.

[0003] The application of hyperbranched polysiloxane in the field of coatings is mainly as a coating additive. It has low toxicity and is environmentally friendly. It can also improve the performance of coatings, such as increasing the hardness of the coating film, reducing surface energy, and enhancing wear resistance and chemical corrosion resistance.

[0004] The patent with publication number CN 114891440 A published on August 12, 2022, discloses a hyperbranched polysiloxane-epoxy resin self-stratification coating and its preparation method, including components A and B, by weight, component A includes 60-150 parts of hyperbranched polysiloxane, 30-200 parts of epoxy resin, 35-150 parts of organic solvent, and component B includes 20-200 parts of amine curing agent, 5-90 parts of organic solvent. Components A and B are fully mixed, and hyperbranched polysiloxane-epoxy resin self-stratification coating can be obtained after room temperature curing, and the resulting coating will not be completely separated while spontaneously stratified, solving the problem of interlayer adhesion caused by forming a clear phase interface, and effectively improving the basic mechanical properties and corrosion resistance of the paint film. However, it does not record the specific effects of salt water resistance and salt spray performance, and the hyperbranched polysiloxane prepared by the patent has no corrosion inhibition function. Summary of the invention

[0005] The invention aims to provide a hyperbranched polysiloxane coating corrosion inhibitor and a preparation method thereof. The hyperbranched polysiloxane coating corrosion inhibitor is prepared by catalytic reaction of p-dimethylaminobenzaldehyde and small molecular silane in an alcohol solution. The prepared hyperbranched polysiloxane contains an imine group, which can form a stable complex with a metal surface and be adsorbed on the metal surface to form a protective film, thereby effectively slowing down the erosion rate of a corrosive medium on a metal substrate and improving the anti-corrosion performance of the coating.

[0006] The purpose of the present invention is to provide a hyperbranched polysiloxane epoxy anticorrosive coating and a preparation method thereof, by adding a hyperbranched polysiloxane coating corrosion inhibitor to an epoxy resin, the comprehensive protective performance of the coating is improved; and by using an active diluent, VOC emissions can be effectively reduced during the curing process of the paint film.

[0007] Another object of the present invention is to provide an application of a hyperbranched polysiloxane epoxy anticorrosive coating for metal protection.

[0008] The specific technical solutions of the present invention are as follows:

[0009] A method for preparing a hyperbranched polysiloxane coating corrosion inhibitor, specifically comprising:

[0010] Dissolve p-dimethylaminobenzaldehyde and silane in an alcohol solvent, add a catalyst dropwise under a protective atmosphere, heat and stir to react, separate and purify to obtain the product.

[0011] The molar ratio of the p-dimethylaminobenzaldehyde to the silane is 1:(1-1.2).

[0012] The silane is one or a combination of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.

[0013] The amount of the alcohol solvent added is 1.0 to 1.5 times the total mass of p-dimethylaminobenzaldehyde and silane;

[0014] The alcohol solvent is one or a combination of methanol or ethanol;

[0015] The amount of the catalyst added is 1 / 1000 to 5 / 1000 of the total mass of p-dimethylaminobenzaldehyde and silane;

[0016] The catalyst is glacial acetic acid;

[0017] The protective atmosphere refers to an argon atmosphere;

[0018] The heating and stirring reaction refers to: stirring and reacting in a 50-60°C water bath at 200-300 r / min for 12-15 hours to allow the amino group and the aldehyde group to fully react and dehydrate to form a carbon-nitrogen double bond;

[0019] The separation and purification refers to: removing the alcohol solvent and the catalyst by rotary evaporation to obtain a dark yellow thick liquid, which is the hyperbranched polysiloxane.

[0020] The invention provides a hyperbranched polysiloxane coating corrosion inhibitor, which is prepared by the above method.

[0021] The invention provides a hyperbranched polysiloxane epoxy anticorrosive coating, the raw materials of which include the hyperbranched polysiloxane coating corrosion inhibitor.

[0022] The hyperbranched polysiloxane epoxy anticorrosive coating comprises the following raw materials in parts by weight:

[0023] 30-50 parts of epoxy resin, 20-35 parts of hyperbranched polysiloxane coating corrosion inhibitor, 5-10 parts of active diluent, 2-2.5 parts of silane coupling agent, 15-30 parts of filler, 1.5-2.5 parts of auxiliary agent and 15-20 parts of curing agent.

[0024] The epoxy resin is selected from one or more combinations of epoxy E20, epoxy E44 or epoxy E51.

[0025] The active diluent is selected from one or more combinations of octyl glycidyl ether, phenyl glycidyl ether, and resorcinol bisglycidyl ether.

[0026] The silane coupling agent is selected from one or a combination of KH550, KH560 or KH570;

[0027] The filler is selected from one or more combinations of graphene, red iron oxide and talcum powder.

[0028] The auxiliary agent is selected from one or a combination of anti-settling agents or dispersants.

[0029] The anti-settling agent is selected from fumed silica.

[0030] The dispersant is selected from EFKA4010.

[0031] The curing agent includes one or more combinations of polyamide, alicyclic amine and aromatic amine.

[0032] The present invention provides a method for preparing a hyperbranched polysiloxane epoxy anticorrosive coating, which is specifically:

[0033] Add epoxy resin and active diluent to the hyperbranched polysiloxane coating corrosion inhibitor, stir and disperse, then add filler and additive, stir, grind, finally add silane coupling agent and curing agent, stir evenly, and obtain hyperbranched polysiloxane epoxy anticorrosive coating.

[0034] The stirring dispersion refers to dispersion at 500-800 r / min for 10-15 min;

[0035] The stirring means: stirring at 1500-2000 r / min for 20-40 min;

[0036] The grinding means: grinding until the coating fineness is 50 μm.

[0037] The invention provides an application of a hyperbranched polysiloxane epoxy anticorrosive coating for metal protection, especially for the fields of ship corrosion protection, marine steel structures, containers, and marine engineering steel structures.

[0038] The present invention utilizes the imine group in the hyperbranched polysiloxane to form a stable complex with the metal substrate, which is adsorbed on the metal surface to form a protective film, effectively slowing down the erosion rate of the corrosive medium on the metal substrate, improving the anti-corrosion performance of the coating, and can replace the pollution of the environment by traditional lead or chromium coating corrosion inhibitors. In addition, the present invention uses active diluents to prepare the coating with high solid content, and less VOC emissions during the curing process of the paint film. The hyperbranched polysiloxane epoxy anti-corrosion coating prepared by the technical solution of the present invention has a salt spray resistance of ≥5000h, a salt water resistance of ≥5000h, an impact resistance of ≤50kg·cm, a 100-grid adhesion of level 0, and a long-term corrosion protection function.

[0039] Compared with the prior art, the coating corrosion inhibitor hyperbranched polysiloxane prepared by the present invention contains an imine group, which can form a stable complex with the metal surface, adsorb on the metal surface to form a protective film, effectively slow down the erosion rate of the corrosive medium on the metal substrate, and improve the anti-corrosion performance of the coating. At the same time, an active diluent is used, the coating solid content is high, and the VOC emission is low during the curing process of the paint film. Compared with traditional corrosion inhibitors containing heavy metals, hyperbranched polysiloxane has low toxicity and less harm to the environment and human body. At the same time, the synthesis process of hyperbranched polysiloxane is relatively simple, the reaction conditions are mild, and it is easy to realize industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a schematic diagram of the synthesis of hyperbranched polysiloxane according to Example 1 of the present invention;

[0041] Figure 2 This is the infrared spectrum of the hyperbranched polysiloxane prepared in Example 1 of the present invention;

[0042] Figure 3 Photo of a 100-grid adhesion test after the anti-corrosion coating prepared in Example 2 of the present invention was sprayed on the carbon steel surface. DETAILED DESCRIPTION

[0043] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0045] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0046] Example 1

[0047] A method for preparing a hyperbranched polysiloxane epoxy anticorrosive coating, the specific preparation steps comprising:

[0048] 1) Preparation of hyperbranched polysiloxane coating corrosion inhibitor:

[0049] In a three-necked flask, 1 mol of p-dimethylaminobenzaldehyde and 1 mol of 3-aminopropyltriethoxysilane were dissolved in 380 g of ethanol solvent. Under an argon atmosphere, 0.4 g of catalyst glacial acetic acid was added dropwise. The mixture was stirred at 250 r / min at 50°C for 15 h to dehydrate the amino and aldehyde groups to form carbon-nitrogen double bonds. The alcohol solvent ethanol and the catalyst glacial acetic acid were removed by rotary evaporation at 50°C for 4 h to obtain a dark yellow thick liquid, which was the hyperbranched polysiloxane. Figure 1 is a schematic diagram of the preparation of hyperbranched polysiloxane; the infrared spectrum of the hyperbranched polysiloxane is shown in Figure 2 .

[0050] In the infrared spectrum ( Figure 2 ), 1100cm -1 、810cm -1 、585cm -1 The absorption peaks at 1657cm correspond to the antisymmetric stretching vibration, symmetric stretching vibration and bending vibration of Si-O-Si bond respectively; -1 The characteristic contraction vibration absorption peak of -C=N- is generated at 2800~1900cm -1 The absorption peak corresponds to the stretching vibration absorption peak of the CH bond; the infrared results show that the amino and aldehyde groups have been dehydrated to form carbon-nitrogen double bonds, and the ethoxysilane has been hydrolyzed to form hyperbranched polysiloxane.

[0051] 2) Preparation of hyperbranched polysiloxane epoxy anticorrosive coating:

[0052] To 20g of the hyperbranched polysiloxane coating corrosion inhibitor prepared in step 1), 30g of epoxy resin E44 (the epoxy resin was purchased from Shandong Deyuan Epoxy Technology Co., Ltd.) and 8g of active diluent resorcinol bisglycidyl ether (purchased from Aladdin Reagent Company) were added, dispersed at 800r / min for 15min, then 25g of red iron oxide, 1.0g of EFKA4010 and 0.5g of fumed silica were added, stirred at 2000r / min for 30min, ground to a coating fineness of 50μm, and finally 2.5g of silane coupling agent KH560 and 15g of polyamide curing agent (brand number 8115, purchased from Dongguan Zhenhe Resin Technology Co., Ltd.) were added, and stirred evenly to obtain a hyperbranched polysiloxane epoxy anticorrosive coating.

[0053] The hyperbranched polysiloxane epoxy anticorrosive coating prepared in Example 1 was sprayed onto a carbon steel plate (substrate sandblasting Sa2.5 level) using compressed air, and cured at room temperature 25°C for 24 hours, and the film thickness was controlled to be 100±5 μm, thereby obtaining a hyperbranched polysiloxane epoxy anticorrosive coating. The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating are shown in Table 1.

[0054] Table 1 Performance test results of embodiments and comparative examples

[0055]

[0056] In Table 1, the salt water resistance and salt spray resistance of Example 1 and Example 2 are both ≥5000h, which means that the paint film is not damaged after 5000h. Therefore, the salt water resistance and salt spray resistance of Example 1 and Example 2 are both ≥5000h.

[0057] Example 2

[0058] This embodiment provides a hyperbranched polysiloxane epoxy anticorrosive coating, and its preparation method is basically the same as that of Example 1, except that 25g of hyperbranched polysiloxane and 20g of red iron oxide are added to the epoxy resin, and the rest are the same.

[0059] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in Example 2 are shown in Table 1. The coating prepared in Example 2 was sprayed on the surface of carbon steel and a 100-grid adhesion test was performed. The test results are shown in Table 1. Figure 3 .

[0060] Figure 3 This is a photograph of the coating prepared in Example 2 being sprayed onto a carbon steel plate and subjected to a 100-grid adhesion test. The paint film did not break or fall off at the scribe line, and the 100-grid adhesion test was level 0, indicating that the coating has good bonding performance on the carbon steel plate.

[0061] Comparative Example 1

[0062] This comparative example provides a hyperbranched polysiloxane epoxy anticorrosive coating, the preparation method of which is substantially the same as that of Example 1, except that no hyperbranched polysiloxane is added, and 45 g of red iron oxide is added. The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in this comparative example 1 are shown in Table 1.

[0063] Comparative Example 2

[0064] This comparative example provides an epoxy graphene anti-corrosion coating, and its preparation method is basically the same as that of Example 1, except that: no silane coupling agent KH560 is added, and 27.5g of red iron oxide is added. The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in this comparative example 2 are shown in Table 1.

[0065] By comparing the test results of Example 1 and Comparative Example 1, adding hyperbranched polysiloxane to the epoxy resin can significantly improve the pull-out adhesion and hardness of the paint film, and at the same time, the salt water resistance and salt spray resistance of the paint film are significantly improved.

[0066] By comparing the test results of Example 1 and Comparative Example 2, the use of silane coupling agent can improve the pull-out adhesion, salt water resistance and salt spray resistance of the paint film. The main reason is that the molecular structure of the silane coupling agent is: YR-Si(OR)3 (where Y represents an organic functional group, and SiOR represents a silane alkoxy group). Among them, the silane alkoxy group is reactive to inorganic substances (fillers), can be adsorbed on the surface of the iron oxide red filler, and the organic functional group is compatible with the organic epoxy resin. Therefore, when the silane coupling agent is added to the epoxy coating system, a bonding layer of an organic matrix-silane coupling agent-inorganic matrix can be formed, which improves the dispersion performance of fillers and hyperbranched polysiloxanes in epoxy resins, thereby improving the compactness and adhesion of the coating, and the salt water resistance and salt spray resistance will also increase.

[0067] The description of the above embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the protection scope of the present invention.

Claims

1. A method for preparing a hyperbranched polysiloxane coating corrosion inhibitor, It is characterized in that The preparation method is specifically: The para-dimethylaminobenzaldehyde and silane are dissolved in an alcohol solvent, a catalyst is added dropwise under a protective atmosphere, the reaction is carried out by heating and stirring, and the reaction is separated and purified to obtain a hyperbranched polysiloxane coating corrosion inhibitor.

2. The preparation method according to claim 1, It is characterized in that The molar ratio of p-dimethylaminobenzaldehyde to silane is 1:(1-1.2); the silane is one or a combination of 3-aminopropyltriethoxysilane and 3-aminopropyltrimethoxysilane.

3. The preparation method according to claim 1 or 2, It is characterized in that The added amount of the alcohol solvent is 1.0 to 1.5 times the total mass of p-dimethylaminobenzaldehyde and silane; the alcohol solvent is one or a combination of methanol or ethanol.

4. The preparation method according to claim 1 or 2, It is characterized in that The added amount of the catalyst is 1 / 1000 to 5 / 1000 of the total mass of p-dimethylaminobenzaldehyde and silane; and the catalyst is glacial acetic acid.

5. The preparation method according to claim 1 or 2, It is characterized in that The heating and stirring reaction refers to: stirring the reaction at 50-60° C. for 12-15 hours.

6. A hyperbranched polysiloxane coating corrosion inhibitor prepared by the preparation method according to any one of claims 1 to 5.

7. A hyperbranched polysiloxane epoxy anticorrosive coating, It is characterized in that The raw material of the hyperbranched polysiloxane epoxy anticorrosive coating includes the hyperbranched polysiloxane coating corrosion inhibitor according to claim 6.

8. The hyperbranched polysiloxane epoxy anticorrosive coating according to claim 7, It is characterized in that The hyperbranched polysiloxane epoxy anticorrosive coating comprises the following raw materials in parts by weight: 30-50 parts of epoxy resin, 20-35 parts of hyperbranched polysiloxane coating corrosion inhibitor, 5-10 parts of active diluent, 2-2.5 parts of silane coupling agent, 15-30 parts of filler, 1.5-2.5 parts of auxiliary agent and 15-20 parts of curing agent.

9. A method for preparing the hyperbranched polysiloxane epoxy anticorrosive coating according to claim 7 or 8, It is characterized in that The preparation method is specifically: Add epoxy resin and active diluent to the hyperbranched polysiloxane coating corrosion inhibitor, stir and disperse, then add filler and additive, stir, grind, finally add silane coupling agent and curing agent, stir evenly, and obtain hyperbranched polysiloxane epoxy anticorrosive coating.

10. An application of the hyperbranched polysiloxane epoxy anticorrosive coating according to claim 7 or 8, It is characterized in that For metal protection.

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