Guanidyl hyperbranched polysiloxane coating corrosion inhibitor, preparation method of guanidyl hyperbranched polysiloxane coating corrosion inhibitor, waterborne epoxy anticorrosive paint and application of waterborne epoxy anticorrosive paint

Abstract

The invention provides a guanidyl hyperbranched polysiloxane coating corrosion inhibitor, a preparation method of the guanidyl hyperbranched polysiloxane coating corrosion inhibitor, a waterborne epoxy anticorrosive paint and application of the waterborne epoxy anticorrosive paint. The preparation method of the guanidyl hyperbranched polysiloxane coating corrosion inhibitor comprises the following steps: adding a catalyst into a mixed solution of gamma-glycidyl ether oxypropyl trimethoxy silane and triethylene glycol; the preparation method comprises the following steps: carrying out a hydrolysis reaction, heating, continuing a dehydration reaction, adding 1, 1, 3, 3-tetramethylguanidine, and carrying out an epoxy ring-opening reaction to obtain a deep yellow thick liquid, namely the guanidyl hyperbranched polysiloxane coating corrosion inhibitor. Compared with the prior art, Schiff base (-C = N-bond) in guanidyl hyperbranched polysiloxane and metal substrate iron ions are utilized to form a stable complex, and the stable complex is adsorbed on the metal surface to form a passive film, so that the flash rust phenomenon can be inhibited, and the adhesive force and saline resistance of a waterborne epoxy coating can be improved; meanwhile, the prepared waterborne epoxy coating is free of VOC emission in the construction and curing process.

Description

Technical Field

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

[0002] Applying anti-corrosion coatings is an important way to slow down metal corrosion. Adding coating corrosion inhibitors to the coating can improve the comprehensive protective effect of the coating. Currently, the commonly used coating corrosion inhibitors mainly include three types: inorganic corrosion inhibitors, organic phosphorus corrosion inhibitors and silicone corrosion inhibitors. Among them, organic phosphorus corrosion inhibitors will cause eutrophication of water bodies, promote algae growth, cause water quality deterioration and endanger aquatic ecosystems; inorganic corrosion inhibitors generally contain heavy metal lead, which is harmful to the environment. Under high temperature, high pressure or specific pH value, its corrosion inhibition effect will be significantly reduced, and it is easy to form precipitation or scaling, increasing maintenance costs; silicone corrosion inhibitors do not contain heavy metals, are more easily biodegradable, reduce environmental pollution, and have high chemical stability. Even at high temperature (≤300℃) or extreme pH values, they can maintain good corrosion inhibition effects.

[0003] The application of hyperbranched polysiloxane in the coating field is mainly as a coating corrosion inhibitor. It has low toxicity and is environmentally friendly. When added to epoxy coatings, it can effectively inhibit flash rust, improve the adhesion of the paint film and its salt water resistance, etc. Chinese invention patent CN19119495A discloses a hyperbranched polysiloxane epoxy anticorrosive coating and its preparation method and application, which is mainly prepared by catalytic reaction of p-dimethylaminobenzaldehyde and small molecule silane in alcohol solution to obtain a hyperbranched polysiloxane coating corrosion inhibitor with an epoxy end group; the solvent-based epoxy coating system prepared by using the epoxy hyperbranched polysiloxane coating corrosion inhibitor can keep the paint film resistant to salt spray and salt water for more than 5000 hours without blistering; however, in the epoxy coating, on the one hand, the mass ratio of the epoxy hyperbranched polysiloxane coating corrosion inhibitor to the epoxy resin is 0.4-1.1:1, and the addition amount of the hyperbranched polysiloxane coating corrosion inhibitor is relatively high; on the other hand, an active diluent is also required to be added to the coating system to reduce the VOC emission during the curing process of the paint film, but as a solvent-based epoxy resin coating system, it is inevitable to release VOC during the curing process, which causes pollution to the environment, especially when it is applied to the marine environment, it causes irreversible damage to seawater and marine life.

[0004] Therefore, there is an urgent need to provide an environmentally friendly water-based epoxy anti-corrosion coating that is highly resistant to salt spray and salt water corrosion. Summary of the invention

[0005] The purpose of the present invention is to provide a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor and a preparation method thereof, and a water-based epoxy anticorrosive coating.

[0006] As one of the objects of the invention, the present invention provides a method for preparing a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, wherein 1,1,3,3-tetramethylguanidine is added to an epoxy hyperbranched polysiloxane to carry out an epoxy ring-opening reaction, thereby obtaining the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0007] As a preferred embodiment, the reaction conditions of the epoxy ring-opening reaction include a reaction temperature of 50-70° C. and a reaction time of 6-8 h.

[0008] As a preferred embodiment, the molar ratio of the epoxy hyperbranched polysiloxane to 1,1,3,3-tetramethylguanidine is 1:(1-2).

[0009] As a preferred embodiment, the preparation method of the guanidine hyperbranched polysiloxane coating corrosion inhibitor comprises the following specific steps: S1. Dissolving γ-glycidyloxypropyltrimethoxysilane and triethylene glycol in an organic solvent to form a mixed solution, adding a catalyst dropwise under a protective atmosphere, and performing a hydrolysis reaction under stirring to obtain a first reaction system; S2. The first reaction system is heated to continue the dehydration reaction, and the second reaction system is obtained by post-treatment; S3. Add 1,1,3,3-tetramethylguanidine to the second reaction system to carry out epoxy ring-opening reaction to obtain a dark yellow thick liquid, which is the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0010] As a preferred embodiment, in S1, the reaction conditions of the hydrolysis reaction are reaction temperature of 50-60° C. and reaction time of 4-6 h.

[0011] As a preferred embodiment, in S2, the reaction conditions of the dehydration reaction are reaction temperature of 100-110° C. and reaction time of 3-6 h.

[0012] As a preferred embodiment, the post-treatment includes vacuum filtration to remove by-products and organic solvents.

[0013] As a preferred embodiment, the molar ratio of γ-glycidyloxypropyltrimethoxysilane to triethylene glycol is 1:(3-5).

[0014] As a preferred embodiment, the amount of the organic solvent added is 1.0 to 1.5 times the total mass of γ-glycidyloxypropyltrimethoxysilane and triethylene glycol.

[0015] As a preferred embodiment, the added amount of the catalyst is 1 / 1000 to 3 / 1000 of the total mass of γ-glycidyloxypropyltrimethoxysilane.

[0016] As a preferred embodiment, the organic is methanol and / or ethanol.

[0017] As a preferred embodiment, the catalyst is 0.5 wt % HCl solution and / or 5 wt % HAC solution.

[0018] As a preferred embodiment, the protective atmosphere is at least one of nitrogen or an inert gas.

[0019] Preferably, the inert gas is argon.

[0020] As one of the objects of the invention, the present invention also provides a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor prepared by the aforementioned preparation method.

[0021] As one of the objects of the invention, the present invention also provides a water-based epoxy anti-corrosion coating, comprising the aforementioned guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0022] As a preferred embodiment, the components of the waterborne epoxy anti-corrosion coating include, by mass: 40 to 50 parts of waterborne epoxy resin, 10 to 15 parts of guanidine hyperbranched polysiloxane coating corrosion inhibitor, 5 to 10 parts of deionized water, 3 to 5 parts of epoxy phosphate, 25 to 40 parts of filler, 1.5 to 2.5 parts of additives, and 10 to 20 parts of curing agent.

[0023] As a preferred embodiment, the waterborne epoxy resin is selected from one or more combinations of epoxy E20, epoxy E44 or epoxy E51.

[0024] As a preferred embodiment, the filler is selected from one or more combinations of boron nitride, barium sulfate, copper chrome black, and talc.

[0025] As a preferred embodiment, the auxiliary agent is selected from an anti-settling agent and / or a defoaming agent.

[0026] As a preferred embodiment, the anti-settling agent is selected from bentonite.

[0027] As a preferred embodiment, the defoaming agent is selected from Dow Corning DC-65.

[0028] As a preferred embodiment, the curing agent is a combination of one or more of polyamide, alicyclic amine and aromatic amine.

[0029] As one of the purposes of the invention, the present invention also provides a method for preparing the aforementioned water-based epoxy anti-corrosion coating, the specific steps comprising: adding water-based epoxy resin and deionized water to the guanidine hyperbranched polysiloxane coating corrosion inhibitor, stirring and dispersing, then adding fillers and additives, stirring, grinding, and finally adding a curing agent, stirring evenly, to obtain a guanidine hyperbranched polysiloxane water-based epoxy anti-corrosion coating.

[0030] Preferably, the stirring dispersion refers to dispersion at 500-800 r / min for 10-15 min.

[0031] Preferably, the stirring comprises a stirring speed of 1500-2000 r / min and a stirring time of 20-40 min.

[0032] Preferably, the grinding includes grinding the coating to a fineness of 40 μm.

[0033] Beneficial technical effects obtained by the present invention: 1. The guanidine hyperbranched polysiloxane provided by the present invention contains a large amount of Schiff bases (-C=N-bonds), which can form a stable complex with a metal substrate (such as iron ions), and adsorb on the metal surface to form a passivation film, which can not only inhibit the flash rust phenomenon, but also improve the adhesion and salt water resistance and salt spray resistance of the waterborne epoxy coating. Moreover, the waterborne epoxy coating prepared by the present invention is an environmentally friendly epoxy coating, which does not require the addition of active diluents, and has no VOC emissions during the construction and curing process. It has the characteristics of environmental protection and pollution-free. It is applied to the surface of ships used in the ocean to avoid pollution and damage to the marine environment and marine life.

[0034] 2. The coating formed on the metal surface by the guanidine hyperbranched polysiloxane water-based epoxy anti-corrosion coating prepared by the technical solution of the present invention has a passivation film formed between the Schiff base and the metal substrate, which gives the metal surface stronger corrosion resistance and salt spray resistance. The salt spray resistance is ≥2000h, the salt water resistance is ≥2000h, the impact resistance is ≤50kg·cm, and the 100-grid adhesion is level 0. Therefore, compared with the existing water-based anti-corrosion coating, it has a better corrosion protection function.

[0035] 3. Compared with the prior art, the coating corrosion inhibitor guanidine hyperbranched polysiloxane prepared by the present invention contains a Schiff base (-C=N-bond) structure, and the group structure can form a stable complex with the metal surface, adsorb on the metal surface to form a protective film, effectively inhibit the occurrence of flash rust during the coating process of water-based paint, and at the same time, with epoxy phosphate, the comprehensive protective performance of the coating can be improved; compared with traditional heavy metal-containing corrosion inhibitors, guanidine hyperbranched polysiloxane has low toxicity and less harm to the environment and human body; and the reaction conditions in the synthesis process of guanidine hyperbranched polysiloxane are mild, and it is easy to realize large-scale industrial production.

[0036] 4. The tetramethylguanidine provided by the present invention is an organic compound containing an imine group (-C=N-), which has good thermal stability and reactivity, undergoes a ring-opening chemical reaction with the epoxy group in the epoxy resin, introduces a guanidine group with higher activity and more easily coordinated with the metal at the end group of the hyperbranched polysiloxane, and is coated on the surface of the metal substrate, with stronger bonding strength and stronger adhesion performance. In addition, the rear end group after the ring opening also contains a large number of hydroxyl groups, which can assist in hydrogen bonding with the surface of the metal substrate, assist in the bonding strength between the coating and the metal substrate, thereby improving the adhesion performance of the coating, and the paint film is not easy to fall off and bubble.

[0037] 5. Compared with the hyperbranched polysiloxane coating corrosion inhibitor with an epoxy end group provided in the prior art, the hyperbranched polysiloxane coating corrosion inhibitor with a guanidine end group provided by the present invention is applied to a water-based epoxy resin system, and the salt spray resistance and salt water resistance of the coating are significantly improved.

[0038] 6. The end groups of the guanidine hyperbranched polysiloxane coating corrosion inhibitor provided by the present invention contain a large number of active guanidine groups and hydroxyl groups, thereby reducing the amount of the guanidine hyperbranched polysiloxane coating corrosion inhibitor added to the water-based epoxy resin. The mass ratio of the guanidine hyperbranched polysiloxane coating corrosion inhibitor to the water-based epoxy resin is only 0.2~0.375:1, which is much lower than the amount of epoxy hyperbranched polysiloxane added in the solvent-based epoxy resin system (0.4~1.1:1). BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1a-Figure 1c This is a schematic diagram of the synthesis of the guanidine hyperbranched polysiloxane provided in Example 1 of the present invention.

[0040] Figure 2 This is the infrared spectrum of the guanidine hyperbranched polysiloxane prepared in Example 1 of the present invention.

[0041] Figure 3 This is the NMR carbon spectrum of the guanidine hyperbranched polysiloxane prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0042] 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 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.

[0043] A preparation method of a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor comprises the following specific steps: dissolving γ-glycidyloxypropyltrimethoxysilane (KH560 for short) and triethylene glycol (TEG for short) in an alcohol solvent, adding a catalyst dropwise under a protective atmosphere, then heating to 100-110° C. for reaction for 3-6 h, vacuum filtering to remove byproducts of water and ethanol, then adding 1,1,3,3-tetramethylguanidine (TMG for short), and continuing to react at 50-70° C. for 6-8 h to obtain a dark yellow thick liquid, which is the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0044] In some specific embodiments, the molar ratio of KH560 to TEG is 1:(3-5).

[0045] In some specific embodiments, the amount of the alcohol solvent added is 1.0 to 1.5 times the total mass of KH560 and TEG.

[0046] In some specific embodiments, the alcohol solvent is methanol or ethanol or a combination thereof.

[0047] In some specific embodiments, the added amount of the catalyst is 1 / 1000 to 3 / 1000 of the total mass of KH560 and TEG.

[0048] In some specific embodiments, the catalyst is one or a combination of 0.5 wt % HCl solution or 5 wt % HAC solution.

[0049] In some specific embodiments, the protective atmosphere is nitrogen or argon, or a combination of these.

[0050] In some specific embodiments, the molar ratio of KH560 to TMG is 1:(1-2).

[0051] In some specific embodiments, the vacuum filtration refers to vacuum rotary evaporation to remove byproducts of water and ethanol to obtain a dark yellow thick liquid, which is the guanidine hyperbranched polysiloxane.

[0052] The invention provides a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, which is prepared by the above method.

[0053] The invention provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating, the raw materials of which include the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0054] In some specific embodiments, the guanidine hyperbranched polysiloxane waterborne epoxy anti-corrosion coating comprises the following raw materials in parts by weight: 40 to 50 parts of waterborne epoxy resin, 10 to 15 parts of guanidine hyperbranched polysiloxane coating corrosion inhibitor, 5 to 10 parts of deionized water, 3 to 5 parts of epoxy phosphate, 20 to 40 parts of filler, 1.5 to 2.5 parts of additives, and 10 to 20 parts of curing agent.

[0055] In some specific embodiments, the waterborne epoxy resin is selected from a combination of one or more of waterborne epoxy E20 and waterborne epoxy E44.

[0056] In some specific embodiments, the filler is selected from one or more combinations of boron nitride, barium sulfate, copper chrome black, and talc.

[0057] In some specific embodiments, the auxiliary agent is selected from one or a combination of anti-settling agents or defoaming agents.

[0058] In some specific embodiments, the anti-settling agent is selected from bentonite.

[0059] In some specific embodiments, the defoaming agent is selected from Dow Corning DC-65.

[0060] In some specific embodiments, the curing agent includes one or more combinations of polyamide, alicyclic amine and aromatic amine.

[0061] The invention provides a method for preparing a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosion coating, which specifically comprises the following steps: adding a waterborne epoxy resin and deionized water to a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, stirring and dispersing, then adding a filler and an auxiliary agent, stirring, grinding, and finally adding a curing agent, stirring evenly, to obtain the guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosion coating.

[0062] In some specific embodiments, the stirring dispersion refers to dispersion at 500-800 r / min for 10-15 min.

[0063] In some specific embodiments, the stirring includes a stirring speed of 1500-2000 r / min and a stirring time of 20-40 min.

[0064] In some specific embodiments, the grinding includes grinding the coating to a fineness of 30-50 μm.

[0065] The invention provides a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor. The hyperbranched polysiloxane is prepared by catalytic reaction of γ-glycidyloxypropyltrimethoxysilane (KH560 for short) and triethylene glycol (TEG for short) in an alcohol solution, and then the hyperbranched polysiloxane is subjected to an epoxy ring-opening reaction with 1,1,3,3-tetramethylguanidine (TMG for short) to obtain the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor. The guanidine-based hyperbranched polysiloxane coating corrosion inhibitor can be used as the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0066] The guanidine-based hyperbranched polysiloxane contains a Schiff base (-C=N-bond) structure, which can form a stable complex with the iron ions of the metal substrate and be adsorbed on the metal surface to form a passivation film, which can not only prevent the occurrence of flash rust, but also improve the adhesion and salt water resistance of the water-based epoxy coating. At the same time, the water-based epoxy coating is prepared without VOC emissions during the construction and curing process.

[0067] As one of the purposes of the invention, the present invention provides a waterborne epoxy anti-corrosion coating based on guanidine hyperbranched polysiloxane, which improves the anti-flash rust performance of the waterborne epoxy coating by adding a guanidine hyperbranched polysiloxane coating corrosion inhibitor to the waterborne epoxy resin; and compounding with epoxy phosphate can synergistically improve the comprehensive protective performance of the waterborne epoxy coating.

[0068] Another object of the present invention is to provide an application of a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating for metal protection, including protection on metal steel structures, ships and containers.

[0069] The invention provides a guanidine-based hyperbranched polysiloxane epoxy anticorrosive coating for metal protection, especially for the protection of metal steel structures, ships and containers.

[0070] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0071] 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.

[0072] Example 1 This embodiment provides a method for preparing a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating, and the specific preparation steps include: 1) Preparation of guanidine hyperbranched polysiloxane coating corrosion inhibitor: See also Figure 1a-Figure 1c , is a schematic diagram of the principle of preparing hyperbranched polysiloxane in this embodiment, Specifically, the preparation steps of hyperbranched polysiloxane include: In a three-necked flask, 1 mol of γ-glycidyloxypropyltrimethoxysilane (KH560) and 4 mol of triethylene glycol (TEG) were dissolved in 380 g of ethanol solvent. Under an argon atmosphere, 0.4 g of 0.5 wt% HCl solution was added dropwise as a catalyst. The mixture was stirred at 250 r / min in a 50°C water bath for 5 h to hydrolyze KH560. Figure 1a The reaction is shown in the following formula; the temperature is then raised to 100°C for 4 h to allow the hydrolysis product of KH560 to react with TEG for dehydration, see Figure 1b The reaction formula shown in FIG. 1 was followed by vacuum filtration to remove byproducts of water, ethanol and HCl. Finally, 2 mol of 1,1,3,3-tetramethylguanidine (TMG) was added and the epoxy ring-opening reaction was carried out in a 60°C water bath for 6 h to obtain a dark yellow thick liquid, which was guanidine hyperbranched polysiloxane. Figure 1c The reaction shown in .

[0073] See also Figure 2 , the infrared spectra of the reactants KH560, TEG, TMG and the product guanidine hyperbranched polysiloxane. As can be seen from the figure, in the infrared spectrum, 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 results of infrared spectroscopy show that ethoxysilane has been hydrolyzed to form hyperbranched polysiloxane, and the epoxy groups in TMG and hyperbranched polysiloxane have undergone ring-opening reaction.

[0074] See also Figure 3 , which is the NMR carbon spectrum of guanidino hyperbranched polysiloxane; as can be seen from the figure, the signal peak at 39.98ppm corresponds to C1(-CH3), the signal peak at 49.04 corresponds to C2(CN), and the signal peaks at 60.67, 70.26, 72.82 and 166.80ppm correspond to C3(-CH2), C4(-CH2), C5(-CH2) and C6(C=N), respectively.

[0075] 2) Preparation of waterborne epoxy anticorrosive coating: To 10g of the hyperbranched polysiloxane coating corrosion inhibitor prepared in step 1), add 40g of waterborne epoxy resin E20 (purchased from Shenzhen Yoshida Chemical Co., Ltd., with a brand name of F0704) and 5g of deionized water, disperse at 800r / min for 15min, then add 5g of epoxy phosphate and 25g of copper chrome black, 0.5g of Dow Corning DC-65 as a defoaming agent and 1.5g of bentonite as an anti-settling agent, stir at 2000r / min for 30min, grind to a coating fineness of 40μm, and finally add 13g of polyamide as a curing agent (purchased from Shenzhen Yoshida Chemical Co., Ltd., with a brand name of F0705), stir evenly, and obtain a waterborne epoxy anti-corrosion coating based on guanidine hyperbranched polysiloxane.

[0076] The water-based epoxy anti-corrosion coating based on guanidine hyperbranched polysiloxane 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 paint film thickness was controlled to be 100±5 μm, thereby obtaining a water-based epoxy anti-corrosion coating based on guanidine hyperbranched polysiloxane.

[0077] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating are shown in Table 1.

[0078] Example 2 This embodiment provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating, and its preparation method is basically the same as that of Example 1, except that 15 g of hyperbranched polysiloxane and 20 g of copper chrome black are added to the waterborne epoxy resin, and the rest are the same.

[0079] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in this example are shown in Table 1.

[0080] The coating prepared in the example was sprayed on the surface of carbon steel, and a 100-grid adhesion test and an impact resistance test were performed.

[0081] The coating formed by spraying the paint prepared in this embodiment onto a carbon steel plate was subjected to a 100-grid adhesion test. The paint film did not collapse or fall off at the scribe line, and the 100-grid adhesion test was level 0, indicating that the coating had good bonding performance on the carbon steel plate.

[0082] The coating prepared in the example was sprayed onto a carbon steel plate to test the impact resistance of the coating. The impact site was observed using a 4x magnifying glass. The paint film was intact without damage or cracks, indicating that the impact resistance on the carbon steel plate was good.

[0083] Example 3 This embodiment provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating, and its preparation method is basically the same as that of Example 1, except that in step 2), the amount of guanidine-based hyperbranched polysiloxane coating corrosion inhibitor added is 15 g.

[0084] Comparative Example 1 This comparative example provides a water-based epoxy anticorrosive coating, and its preparation method is basically the same as that of Example 1, except that: guanidine hyperbranched polysiloxane is not added, and 35g of copper chrome black is added; the other steps are the same.

[0085] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in this comparative example are shown in Table 1.

[0086] Comparative Example 2 This comparative example provides a guanidine-based hyperbranched polysiloxane water-based epoxy anticorrosive coating, and its preparation method is basically the same as that of Example 1, except that: epoxy phosphate is not added, and 30g of copper chrome black is added; the other steps are the same.

[0087] Comparative Example 3 This comparative example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating, the preparation method of which is substantially the same as that of Example 1, except that: in step 1), 1,1,3,3-tetramethylguanidine is not added. The other steps are the same.

[0088] Comparative Example 4 This comparative example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating, and its preparation method is basically the same as that of Example 1, except that 1,1,3,3-tetramethylguanidine is added to the epoxy hyperbranched polysiloxane, and the epoxy ring-opening reaction temperature is room temperature.

[0089] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in this comparative example are shown in Table 1.

[0090] Comparative Example 5 This comparative example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating, and its preparation method is basically the same as that of Example 1, except that in step 2), the added amount of the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor is 5 g.

[0091] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in this comparative example are shown in Table 1.

[0092] Table 1 Performance test results of embodiments and comparative examples ; It should be noted that in Table 1, whether flash rust occurs on the carbon steel surface refers to whether yellow rust appears on the coating surface after the coating on the carbon steel surface is cured.

[0093] As can be seen from Table 1, the salt water resistance and salt spray resistance of Examples 1 to 3 are both ≥ 2000h, which means that after measuring for 2000h, the paint film is not damaged. Therefore, the salt water resistance and salt spray resistance of the examples are both ≥ 2000h.

[0094] By comparing the test results of Example 1 and Comparative Example 1, adding guanidine hyperbranched polysiloxane to the epoxy resin can inhibit flash rust on the surface of the carbon steel substrate, significantly improve the pull-off adhesion of the paint film, and at the same time, the salt water resistance and salt spray resistance of the paint film are significantly improved.

[0095] By comparing the test results of Example 1 and Comparative Example 2, adding epoxy phosphate to the coating can improve the pull-out adhesion, salt water resistance and salt spray resistance of the paint film. The main reason is that epoxy phosphate has a certain rust conversion function, and the phosphate radical can react chemically with the iron of the substrate to form iron phosphate, which is chemically bonded and can improve the pull-out adhesion of the paint film. At the same time, iron phosphate is relatively stable. When the corrosive medium penetrates the coating, it can still produce a certain protective effect on the carbon steel substrate, inhibit the blistering of the coating, and improve the salt spray resistance of the water-based epoxy.

[0096] By comparing the test results of Example 1, Comparative Example 1 and Comparative Example 2, it is found that the added guanidine hyperbranched polysiloxane and epoxy phosphate have a synergistic effect in the waterborne epoxy coating. On the one hand, the Schiff base (-C=N-bond) in the guanidine hyperbranched polysiloxane forms a stable complex with the iron ions of the carbon steel substrate, and on the other hand, the epoxy phosphate forms iron phosphate with the carbon steel substrate, and the two can synergistically improve the comprehensive protective effect of the waterborne epoxy coating on carbon steel.

[0097] Further analysis of Comparative Example 3 shows that 1,1,3,3-tetramethylguanidine is not added to the comparative example, that is, the coating corrosion inhibitor obtained in Comparative Example 3 is epoxy hyperbranched polysiloxane. By comparing and analyzing Example 1 and Comparative Example 3, it can be seen that the coating corrosion inhibitor of Example 1 is guanidine epoxy hyperbranched polysiloxane, but the pull-off adhesion, salt water resistance and salt spray resistance of the paint film of Example 1 are significantly better than those of Comparative Example 3, indicating that the Schiff base structure of the end group has a better protective effect on the carbon steel substrate than the epoxy structure.

[0098] In Comparative Example 4, 1,1,3,3-tetramethylguanidine was added at room temperature to carry out epoxy ring-opening reaction. The test results showed that the epoxy group could not open at low temperature and no guanidine epoxy hyperbranched polysiloxane was generated. Compared with the results of Comparative Example 3, the salt water resistance and salt spray resistance were equivalent.

[0099] Example 1, Example 3 and Comparative Example 5 are comparisons of different addition amounts of guanidino-epoxy hyperbranched polysiloxane. It can be seen that when the addition ratio of guanidino-hyperbranched polysiloxane coating corrosion inhibition to water-based epoxy resin is 0.2~0.375:1, excellent protective effect can be obtained; at the same time, compared with the prior art, the addition amount is significantly reduced.

[0100] 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 guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, characterized in that: The guanidine-based hyperbranched polysiloxane coating corrosion inhibitor is obtained by adding 1,1,3,3-tetramethylguanidine to the epoxy hyperbranched polysiloxane to carry out an epoxy ring-opening reaction.

2. The method for preparing a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor according to claim 1, wherein The reaction conditions of the epoxy ring-opening reaction include a reaction temperature of 50 to 70° C. and a reaction time of 6 to 8 hours; The molar ratio of the epoxy hyperbranched polysiloxane to 1,1,3,3-tetramethylguanidine is 1:(1-2).

3. The preparation method of the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor according to claim 1 or 2, characterized in that: The specific steps include: S1. Dissolving γ-glycidyloxypropyltrimethoxysilane and triethylene glycol in an organic solvent to form a mixed solution, adding a catalyst dropwise under a protective atmosphere, and performing a hydrolysis reaction under stirring to obtain a hydrolysis reaction system; S2. The hydrolysis reaction system is further heated to perform a dehydration reaction, and the epoxy hyperbranched polysiloxane is obtained by post-treatment; S3. Add 1,1,3,3-tetramethylguanidine to the hyperbranched polysiloxane to carry out the epoxy ring-opening reaction to obtain a dark yellow thick liquid, which is the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

4. The method for preparing a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor according to claim 3, wherein: In S1, the reaction conditions of the hydrolysis reaction include a reaction temperature of 50-60° C. and a reaction time of 4-6 h; The molar ratio of γ-glycidyloxypropyltrimethoxysilane to triethylene glycol is 1:(3-5); The amount of the organic solvent added is 1.0 to 1.5 times the total mass of γ-glycidyloxypropyltrimethoxysilane and triethylene glycol; The amount of the catalyst added is 1 / 1000 to 3 / 1000 of the total mass of γ-glycidyloxypropyltrimethoxysilane; The catalyst is 0.5wt% HCl solution and / or 5wt% HAC solution; The protective atmosphere is at least one of nitrogen or an inert gas; The organic solvent is methanol and / or ethanol; And / or, in S2, the reaction conditions of the dehydration reaction include a reaction temperature of 100-110° C. and a reaction time of 3-6 h; The post-treatment includes vacuum filtration to remove by-products and organic solvents.

5. A guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, characterized in that: The preparation is obtained by the preparation method according to any one of claims 1 to 4.

6. A water-based epoxy anti-corrosion coating comprising the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor as claimed in claim 5.

7. The waterborne epoxy anticorrosive coating according to claim 6, characterized in that: Calculated by mass, the components of the waterborne epoxy anti-corrosion coating include: 40 to 50 parts of waterborne epoxy resin, 10 to 15 parts of the guanidine hyperbranched polysiloxane coating corrosion inhibitor, 5 to 10 parts of deionized water, 3 to 5 parts of epoxy phosphate, 25 to 40 parts of filler, 1.5 to 2.5 parts of additives, and 10 to 20 parts of curing agent.

8. The waterborne epoxy anticorrosive coating according to claim 7, characterized in that: The waterborne epoxy resin is selected from one or more combinations of epoxy E20, epoxy E44 or epoxy E51; The filler is selected from a combination of one or more of boron nitride, barium sulfate, copper chrome black, and talcum powder; And / or, the auxiliary agent is an anti-settling agent and / or a defoaming agent; And / or, the anti-settling agent is bentonite; And / or, the defoaming agent is Dow Corning DC-65; And / or, the curing agent is a combination of one or more of polyamide, alicyclic amine and aromatic amine.

9. A method for preparing a waterborne epoxy anticorrosive coating according to any one of claims 6 to 8, characterized in that: include: Add waterborne epoxy resin and deionized water to the guanidine hyperbranched polysiloxane coating corrosion inhibitor, stir and disperse, then add fillers and additives, stir and grind, finally add curing agent, stir evenly, and obtain guanidine hyperbranched polysiloxane waterborne epoxy anticorrosive coating.

10. Use of the waterborne epoxy anticorrosion coating according to any one of claims 6 to 8 in the field of anticorrosion of metal steel structures, ships and containers.

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