A guanidine-based hyperbranched polysiloxane coating corrosion inhibitor and its preparation method, waterborne epoxy anti-corrosion coating and application

Abstract

The present invention provides a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor and its preparation method, a waterborne epoxy anti-corrosion coating and its application. The preparation method of the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor includes: adding a catalyst to a mixed solution of γ-glycidyletheroxypropyltrimethoxysilane and triethylene glycol, raising the temperature after hydrolysis reaction, continuing dehydration reaction, and then adding 1,1,3,3-tetramethylguanidine to carry out epoxy ring-opening reaction to obtain a dark yellow thick liquid, which is the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor. Compared with the prior art, the present invention uses the Schiff base (-C=N- bond) in the guanidine-based hyperbranched polysiloxane to form a stable complex with metal substrate iron ions, 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 of the waterborne epoxy coating. At the same time, the prepared waterborne epoxy coating has no VOC emission during construction and curing.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings, and specifically relates to a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor and its preparation method, a waterborne epoxy anti-corrosion coating and applications thereof. Background Art

[0002] Coating anti-corrosion coatings are an important way to slow down metal corrosion. Adding coating corrosion inhibitors to coatings can improve the comprehensive protection effect of the coatings. Currently, the commonly used coating corrosion inhibitors mainly include three categories: inorganic corrosion inhibitors, organic phosphorus-containing corrosion inhibitors, and organosilicon corrosion inhibitors. Among them, organic phosphorus-containing corrosion inhibitors can cause eutrophication of water bodies, promote the growth of algae, cause water quality deterioration and harm the aquatic ecosystem; inorganic corrosion inhibitors generally contain heavy metal lead, which is harmful to the environment. Under high temperature, high pressure or specific pH values, their corrosion inhibition effect will be significantly reduced, and they are prone to form precipitates or scale, increasing the maintenance cost; organosilicon corrosion inhibitors do not contain heavy metals, are more easily biodegradable, reduce environmental pollution, and have high chemical stability. Even at high temperatures (≤300 °C) or extreme pH values, they can maintain good corrosion inhibition effects.

[0003] The application of hyperbranched polysiloxane in the coating field is mainly used as a coating corrosion inhibitor. It has low toxicity and is environmentally friendly. Added to epoxy coatings, it can effectively inhibit flash rust and improve the adhesion and saltwater resistance of the paint film, etc. Chinese invention patent CN19119495A discloses a hyperbranched polysiloxane epoxy anti-corrosion coating and its preparation method and applications. A hyperbranched polysiloxane coating corrosion inhibitor with epoxy groups at the ends is mainly prepared by the catalytic reaction of p-dimethylaminobenzaldehyde and small molecule silanes in an alcohol solution; the solvent-based epoxy coating system prepared with this epoxy group-containing hyperbranched polysiloxane coating corrosion inhibitor can maintain the paint film without blistering for more than 5000 h in salt spray and saltwater resistance; however, in this epoxy coating, on the one hand, the mass ratio of the epoxy group-containing hyperbranched polysiloxane coating corrosion inhibitor to epoxy resin is 0.4 - 1.1:1, and the addition amount of its hyperbranched polysiloxane coating corrosion inhibitor is relatively high; on the other hand, active diluents also need to be added to the coating system to reduce the VOC emissions during the curing process of the paint film. However, as a solvent-based epoxy resin coating system, it is impossible to avoid releasing VOC during the curing process, causing environmental pollution, especially when it is applied to the marine environment, it will cause irreversible damage to seawater and marine organisms.

[0004] Therefore, there is an urgent need to provide an environmentally friendly waterborne epoxy anti-corrosion coating with high salt spray and saltwater corrosion resistance. Summary of the Invention

[0005] The purpose of the present invention is to provide a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor and its preparation method and a waterborne epoxy anti-corrosion coating.

[0006] As one of the invention purposes, the present invention provides a preparation method of a guanidyl hyperbranched polysiloxane coating corrosion inhibitor. By adding 1,1,3,3-tetramethylguanidine to epoxy-based hyperbranched polysiloxane for epoxy ring-opening reaction, the guanidyl hyperbranched polysiloxane coating corrosion inhibitor is obtained.

[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-based hyperbranched polysiloxane to 1,1,3,3-tetramethylguanidine is 1:(1-2).

[0009] As a preferred embodiment, the preparation method of the guanidyl hyperbranched polysiloxane coating corrosion inhibitor includes the following specific steps:

[0010] S1. Dissolve γ-glycidoxypropyltrimethoxysilane and triethylene glycol in an organic solvent to form a mixed solution. Under a protective atmosphere, dropwise add a catalyst and carry out a hydrolysis reaction under stirring conditions to obtain a first reaction system;

[0011] S2. Heat up the first reaction system to continue the dehydration reaction, and obtain a second reaction system through post-treatment;

[0012] S3. Add 1,1,3,3-tetramethylguanidine to the second reaction system to carry out an epoxy ring-opening reaction to obtain a dark yellow thick liquid, which is the guanidyl hyperbranched polysiloxane coating corrosion inhibitor.

[0013] As a preferred embodiment, in S1, the reaction conditions of the hydrolysis reaction are a reaction temperature of 50-60 °C and a reaction time of 4-6 h.

[0014] As a preferred embodiment, in S2, the reaction conditions of the dehydration reaction are a reaction temperature of 100-110 °C and a reaction time of 3-6 h.

[0015] As a preferred embodiment, the post-treatment includes vacuum filtration to remove by-products and organic solvents.

[0016] As a preferred embodiment, the molar ratio of γ-glycidoxypropyltrimethoxysilane to triethylene glycol is 1:(3-5).

[0017] As a preferred embodiment, the addition amount of the organic solvent is 1.0-1.5 times the total mass of γ-glycidoxypropyltrimethoxysilane and triethylene glycol.

[0018] As a preferred embodiment, the addition amount of the catalyst is 1 / 1000 to 3 / 1000 of the total mass of γ-glycidyletheroxypropyltrimethoxysilane.

[0019] As a preferred embodiment, the organic is methanol and / or ethanol.

[0020] As a preferred embodiment, the catalyst is 0.5 wt% HCl solution and / or 5 wt% HAC solution.

[0021] As a preferred embodiment, the protective atmosphere is at least one of nitrogen or inert gas.

[0022] Preferably, the inert gas is argon.

[0023] As one of the invention purposes, the present invention also provides a guanidyl hyperbranched polysiloxane coating corrosion inhibitor prepared by the foregoing preparation method.

[0024] As one of the invention purposes, the present invention also provides an aqueous epoxy anticorrosive coating, comprising the foregoing guanidyl hyperbranched polysiloxane coating corrosion inhibitor.

[0025] As a preferred embodiment, by mass, the components of the aqueous epoxy anticorrosive coating include: 40 to 50 parts of aqueous epoxy resin, 10 to 15 parts of guanidyl 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 auxiliary agent, and 10 to 20 parts of curing agent.

[0026] As a preferred embodiment, the aqueous epoxy resin is selected from one or a combination of epoxy E20, epoxy E44 or epoxy E51.

[0027] As a preferred embodiment, the filler is selected from one or a combination of boron nitride, barium sulfate, copper chromite black, talcum powder.

[0028] As a preferred embodiment, the auxiliary agent is selected from a settling agent and / or an antifoaming agent.

[0029] As a preferred embodiment, the settling agent is selected from bentonite.

[0030] As a preferred embodiment, the antifoaming agent is selected from Dow Corning DC-65.

[0031] As a preferred embodiment, the curing agent is one or a combination of polyamide, alicyclic amine and aromatic amine.

[0032] As one of the invention purposes, the present invention also provides a preparation method of the foregoing waterborne epoxy anti-corrosion coating, and the specific steps include: adding waterborne epoxy resin and deionized water into the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, stirring and dispersing, then adding fillers and additives, stirring, grinding, and finally adding a curing agent and stirring evenly to obtain the guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating.

[0033] Preferably, the stirring and dispersing means dispersing for 10 - 15 min under the condition of 500 - 800 r / min.

[0034] Preferably, the stirring includes a stirring speed of 1500 - 2000 r / min and a stirring time of 20 - 40 min.

[0035] Preferably, the grinding includes a coating fineness of 40 μm.

[0036] The beneficial technical effects obtained by the present invention:

[0037] 1. The guanidine-based hyperbranched polysiloxane provided by the present invention contains a large number of Schiff bases (-C=N- bonds), which can form stable complexes with metal substrates (such as iron ions), adsorb on the metal surface to form a passivation film, not only can inhibit the flash rust phenomenon, but also can improve the adhesion, 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, without adding active diluents, and there is no VOC emission during construction and curing, with the characteristics of environmental protection and no pollution. Applying it to the surface of ships used in the ocean can avoid pollution and damage to the marine environment and marine organisms.

[0038] 2. The coating formed on the metal surface by the guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating prepared by adopting the technical scheme of the present invention, due to the passivation film formed by the Schiff base and the metal substrate, endows the metal surface with stronger corrosion resistance and salt spray resistance. Its salt spray resistance is ≥2000 h, salt water resistance is ≥2000 h, impact resistance is ≤50 kg·cm, and cross-cut adhesion is grade 0. Therefore, it has a more excellent corrosion protection function compared with the existing waterborne anti-corrosion coatings.

[0039] 3. Compared with the prior art, the guanidine-based hyperbranched polysiloxane used as the coating corrosion inhibitor prepared by the present invention contains a Schiff base (-C=N- bond) structure, and this group structure can form a stable complex with the metal surface, adsorb on the metal surface to form a protective film, effectively inhibiting the occurrence of flash rust during the coating process of waterborne coatings. At the same time, combined with epoxy phosphate, it can improve the comprehensive protection performance of the coating; compared with the traditional heavy metal-containing corrosion inhibitors, the guanidine-based hyperbranched polysiloxane has low toxicity and less harm to the environment and human body; moreover, the reaction conditions in the synthesis process of the guanidine-based hyperbranched polysiloxane are mild and it is easy to realize large-scale industrial production.

[0040] 4. The tetramethylguanidine provided by the present invention is an organic compound containing an imino group (-C=N-), which has good thermal stability and reactivity. It undergoes a ring-opening chemical reaction with the epoxy groups in the epoxy resin, introducing a guanidine group with higher activity and easier coordination with metals at the end groups of the hyperbranched polysiloxane. When it is coated on the surface of the metal substrate, the bonding strength is stronger, and the adhesion performance is also stronger. Moreover, after ring-opening, a large number of hydroxyl groups are also contained at the end groups, which can assist in forming hydrogen bond bonding with the surface of the metal substrate, assisting the binding force between the coating and the metal substrate, thereby improving the adhesion performance of the coating, and the paint film is not easily peeled off and bubbled.

[0041] 5. Compared with the hyperbranched polysiloxane coating corrosion inhibitor with epoxy groups at the end groups provided in the prior art, when the hyperbranched polysiloxane coating corrosion inhibitor with guanidine groups at the end groups provided by the present invention is applied to the waterborne epoxy resin system, the salt spray resistance and salt water resistance of the coating are significantly improved.

[0042] 6. The end groups of the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor provided by the present invention contain a large number of active guanidine groups and hydroxyl groups, so that the addition amount thereof in the waterborne epoxy resin can be reduced. The mass ratio of the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor to the waterborne epoxy resin is only 0.2~0.375:1, which is far lower than the addition amount of the epoxy-based hyperbranched polysiloxane in the solvent-based epoxy resin system (0.4~1.1:1). Description of the Drawings

[0043] Figures 1a - 1c It is a schematic diagram of the synthesis of the guanidine-based hyperbranched polysiloxane provided in Example 1 of the present invention.

[0044] Figure 2 It is an infrared spectrum diagram of the guanidine-based hyperbranched polysiloxane prepared in Example 1 of the present invention.

[0045] Figure 3 It is a nuclear magnetic carbon spectrum diagram of the guanidine-based hyperbranched polysiloxane prepared in Example 1 of the present invention. Detailed Embodiments

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0047] A preparation method of a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, the specific steps include: dissolving γ-glycidoxypropyltrimethoxysilane (abbreviated as KH560) and triethylene glycol (abbreviated as TEG) into an alcohol solvent, under a protective atmosphere, adding a catalyst dropwise, and then heating to 100-110 °C for reaction for 3-6 h, carrying out vacuum filtration to remove by-products water and ethanol, and then adding 1,1,3,3-tetramethylguanidine (abbreviated as TMG), and continuing the reaction 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.

[0048] In some specific embodiments, the molar ratio of KH560 to TEG is 1:(3-5).

[0049] In some specific embodiments, the addition amount of the alcohol solvent is 1.0-1.5 times the total mass of KH560 and TEG.

[0050] In some specific embodiments, the alcohol solvent is one or a combination of several of methanol or ethanol.

[0051] In some specific embodiments, the addition amount of the catalyst is 1 / 1000-3 / 1000 of the total mass of KH560 and TEG.

[0052] In some specific embodiments, the catalyst is one or a combination of several of 0.5wt% HCl solution or 5wt% HAC solution.

[0053] In some specific embodiments, the protective atmosphere is one or a combination of several of nitrogen or argon.

[0054] In some specific embodiments, the molar ratio of KH560 to TMG is 1:(1-2).

[0055] In some specific embodiments, the vacuum filtration means removing by-products water and ethanol by vacuum rotary evaporation to obtain a dark yellow thick liquid, which is the guanidine-based hyperbranched polysiloxane.

[0056] A guanidine-based hyperbranched polysiloxane coating corrosion inhibitor provided by the present invention is prepared by the above method.

[0057] A guanidine-based hyperbranched polysiloxane waterborne epoxy anticorrosive coating provided by the present invention, the raw materials of which include the above guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0058] In some specific embodiments, the guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating comprises the following raw materials in parts by mass: 40-50 parts of waterborne epoxy resin, 10-15 parts of guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, 5-10 parts of deionized water, 3-5 parts of epoxy phosphate ester, 20-40 parts of filler, 1.5-2.5 parts of auxiliary agent, and 10-20 parts of curing agent.

[0059] In some specific embodiments, the waterborne epoxy resin is selected from one or more combinations of waterborne epoxy E20 and waterborne epoxy E44.

[0060] In some specific embodiments, the filler is selected from one or more combinations of boron nitride, barium sulfate, copper chromite black, and talcum powder.

[0061] In some specific embodiments, the auxiliary agent is selected from one or several combinations of anti-settling agent or defoaming agent.

[0062] In some specific embodiments, the anti-settling agent is selected from bentonite.

[0063] In some specific embodiments, the defoaming agent is selected from Dow Corning DC-65.

[0064] In some specific embodiments, the curing agent includes one or more combinations of polyamide, alicyclic amine, and aromatic amine.

[0065] A preparation method of the guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating provided by the present invention is specifically as follows: Add waterborne epoxy resin and deionized water to the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, stir and disperse, then add the filler and auxiliary agent, stir and grind, and finally add the curing agent and stir evenly to obtain the guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating.

[0066] In some specific embodiments, the stirring and dispersing means dispersing for 10-15 minutes under the condition of 500-800 r / min.

[0067] In some specific embodiments, the stirring includes a stirring speed of 1500-2000 r / min and a stirring time of 20-40 minutes.

[0068] In some specific embodiments, the grinding includes making the fineness of the coating 30-50 μm.

[0069] The present invention provides a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor. Hyperbranched polysiloxane is prepared by catalytic reaction of γ-glycidoxypropyltrimethoxysilane (abbreviated as KH560) and triethylene glycol (abbreviated as TEG) in an alcohol solution, and then reacted with 1,1,3,3-tetramethylguanidine (abbreviated as TMG) by epoxy ring-opening reaction to obtain the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor, which can be used as a guanidine-based hyperbranched polysiloxane coating corrosion inhibitor.

[0070] The guanidine-based hyperbranched polysiloxane contains Schiff base (-C=N- bond) structure, which can form stable complexes with metal substrate iron ions, adsorb on the metal surface to form a passivation film, not only can prevent flash rust from appearing, but also can improve the adhesion and salt water resistance of the waterborne epoxy coating. At the same time, when preparing the waterborne epoxy coating, there is no VOC emission during the construction and curing process.

[0071] As one of the purposes of the invention, the present invention provides a waterborne epoxy anti-corrosion coating based on guanidine-based hyperbranched polysiloxane. By adding the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor to the waterborne epoxy resin, the anti-flash rust performance of the waterborne epoxy coating can be improved; and by compounding with epoxy phosphate ester, the comprehensive protection performance of the waterborne epoxy coating can be synergistically improved.

[0072] Another purpose of the present invention is to provide an application of the guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating for metal protection, including protection on metal steel structures, ships and containers.

[0073] The present invention provides an application of a guanidine-based hyperbranched polysiloxane epoxy anti-corrosion coating for metal protection, especially in the protection fields of metal steel structures, ships and containers.

[0074] The test materials and reagents used in the following examples can be obtained from commercial channels without special instructions.

[0075] For those not specifying specific techniques or conditions in the examples, they can all be carried out according to the techniques or conditions described in the literature in this field or according to the product instructions.

[0076] Example 1

[0077] This example provides a preparation method of a guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating. The specific preparation steps include:

[0078] 1) Preparation of guanidine-based hyperbranched polysiloxane coating corrosion inhibitor:

[0079] See Figures 1a - 1c , which is a schematic diagram of the principle for preparing hyperbranched polysiloxane in this example.

[0080] Specifically, the preparation steps of hyperbranched polysiloxane include:

[0081] In a three-necked flask, 1 mol of γ-glycidoxypropyltrimethoxysilane (KH560) and 4 mol of triethylene glycol (abbreviated as 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, and the mixture was stirred at 250 r / min in a 50 °C water bath for 5 h to hydrolyze KH560. See Figure 1a the reaction formula shown; subsequently, the temperature was raised to 100 °C and the reaction was carried out for 4 h to allow the hydrolysis product of KH560 to react with TEG to dehydrate. See Figure 1b the reaction formula shown in ; vacuum filtration was carried out to remove by-products water, ethanol and HCl; finally, 2 mol of 1,1,3,3-tetramethylguanidine (abbreviated as 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-based hyperbranched polysiloxane. See Figure 1c the reaction formula shown in.

[0082] Refer to Figure 2 for the infrared spectra of the reactants KH560, TEG, TMG and the product guanidine-based hyperbranched polysiloxane. As can be seen from the figure, in the infrared spectrum, the absorption peaks at 1100 cm -1 , 810 cm -1 , 585 cm -1 correspond to the antisymmetric stretching vibration, symmetric stretching vibration and bending vibration of the Si-O-Si bond respectively; the characteristic contraction vibration absorption peak of -C=N- is generated at 1657 cm -1 ; the absorption peak at 2800~1900 cm -1 corresponds to the stretching vibration absorption peak of the C-H bond; the results of the infrared spectrum indicate that ethoxysilane has been hydrolyzed to form hyperbranched polysiloxane, and the epoxy groups in TMG and hyperbranched polysiloxane have undergone ring-opening reactions.

[0083] See Figure 3 for the carbon nuclear magnetic spectrum of guanidine-based hyperbranched polysiloxane; as can be seen from the figure, the signal peak corresponding to C1 (-CH3) is at 39.98 ppm, the signal peak corresponding to C2 (C-N) is at 49.04, and the signal peaks corresponding to C3 (-CH2), C4 (-CH2), C5 (-CH2) and C6 (C=N) are at 60.67, 70.26, 72.82 and 166.80 ppm respectively.

[0084] 2) Preparation of waterborne epoxy anticorrosive coating:

[0085] Add 40 g of waterborne epoxy resin E20 (purchased from Shenzhen Yitian Chemical Co., Ltd., product number F0704) and 5 g of deionized water to 10 g of the hyperbranched polysiloxane coating corrosion inhibitor prepared in step 1), disperse at 800 r / min for 15 min, then add 5 g of epoxy phosphate and 25 g of copper chromite black, 0.5 g of Dow Corning DC-65 as an antifoaming agent and 1.5 g of bentonite as an anti-settling agent, stir at 2000 r / min for 30 min, grind until the coating fineness reaches 40 μm, and finally add 13 g of polyamide as a curing agent (purchased from Shenzhen Yitian Chemical Co., Ltd., product number F0705), stir evenly to obtain the waterborne epoxy anti-corrosion coating based on guanidine-based hyperbranched polysiloxane.

[0086] Spray the waterborne epoxy anti-corrosion coating based on guanidine-based hyperbranched polysiloxane prepared in Example 1 onto a carbon steel plate (substrate sandblasted to Sa2.5 level) using compressed air, cure at room temperature of 25 °C for 24 h, and control the film thickness to be 100 ± 5 μm to obtain the waterborne epoxy anti-corrosion coating based on guanidine-based hyperbranched polysiloxane.

[0087] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of this coating are shown in Table 1.

[0088] Example 2

[0089] This example provides a waterborne epoxy anti-corrosion coating based on guanidine-based hyperbranched polysiloxane. Its preparation method is basically the same as that of Example 1, except that: add 15 g of hyperbranched polysiloxane and 20 g of copper chromite black to the waterborne epoxy resin, and the others are the same.

[0090] The adhesion, hardness, impact resistance, salt water resistance and salt spray resistance of the coating prepared in this example are shown in Table 1.

[0091] Spray the coating prepared in the example on the surface of carbon steel, and conduct cross-cut adhesion test and impact resistance test.

[0092] Conduct a cross-cut adhesion test on the coating formed by spraying the coating prepared in this example onto a carbon steel plate. The paint film at the scribed line did not break or peel off. The cross-cut adhesion test result was grade 0, indicating that the coating has good bonding performance on the carbon steel plate.

[0093] Conduct an impact resistance test on the coating formed by spraying the coating prepared in the example onto a carbon steel plate. Observe the impact area with a 4-fold magnifying glass. The paint film is intact, without damage or cracks, indicating good impact resistance on the carbon steel plate.

[0094] Example 3

[0095] This example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating, and its preparation method is basically the same as that of Example 1, except that in step 2), the addition amount of the guanidine-based hyperbranched polysiloxane coating inhibitor is 15 g.

[0096] Comparative Example 1

[0097] This comparative example provides a waterborne epoxy anti-corrosion coating, and its preparation method is basically the same as that of Example 1, except that: no guanidine-based hyperbranched polysiloxane is added, and 35 g of copper chromite black is added; the other steps are the same.

[0098] 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.

[0099] Comparative Example 2

[0100] This comparative example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating, and its preparation method is basically the same as that of Example 1, except that: no epoxy phosphate is added, and 30 g of copper chromite black is added; the other steps are the same.

[0101] Comparative Example 3

[0102] This comparative example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating, and its preparation method is basically 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.

[0103] Comparative Example 4

[0104] This comparative example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion 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-based hyperbranched polysiloxane, and the epoxy ring-opening reaction temperature is room temperature.

[0105] 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.

[0106] Comparative Example 5

[0107] This comparative example provides a guanidine-based hyperbranched polysiloxane waterborne epoxy anti-corrosion coating, and its preparation method is basically the same as that of Example 1, except that: in step 2), the addition amount of the guanidine-based hyperbranched polysiloxane coating inhibitor is 5 g.

[0108] 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.

[0109] Table 1 Performance test results of examples and comparative examples

[0110] ;

[0111] It should be specifically noted that in Table 1, whether flash rust appears on the surface of carbon steel refers to whether yellow rust appears on the surface of the coating after the coating on the carbon steel surface is cured by observation.

[0112] 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.

[0113] By comparing the test results of Example 1 and Comparative Example 1, adding guanidyl hyperbranched polysiloxane to epoxy resin can inhibit the generation of flash rust on the surface of carbon steel substrates, significantly improve the pull-off adhesion of the paint film, and at the same time significantly improve the salt water resistance and salt spray resistance of the paint film.

[0114] By comparing the test results of Example 1 and Comparative Example 2, adding epoxy phosphate ester to the coating can improve the pull-off adhesion, salt water resistance and salt spray resistance of the paint film. The main reason is that epoxy phosphate ester has a certain rust conversion function, and phosphate groups can chemically react with the iron of the substrate to form iron phosphate, which is chemically bonded and can improve the pull-off adhesion of the paint film. At the same time, iron phosphate is relatively stable. When the corrosive medium penetrates the coating, it can still provide a certain degree of protection for the carbon steel substrate, inhibit the coating from blistering, and improve the salt spray resistance of waterborne epoxy.

[0115] By comparing the test results of Example 1, Comparative Example 1 and Comparative Example 2, it is found that in waterborne epoxy coatings, the added guanidyl hyperbranched polysiloxane and epoxy phosphate ester have a synergistic effect. On the one hand, the Schiff base (-C=N- bond) in guanidyl hyperbranched polysiloxane forms a stable complex with iron ions on the carbon steel substrate. On the other hand, epoxy phosphate ester forms iron phosphate with the carbon steel substrate, and the two can synergistically improve the comprehensive protection effect of the waterborne epoxy coating on carbon steel.

[0116] Further analyzing Comparative Example 3, 1,1,3,3-tetramethylguanidine is not added in this comparative example, that is, the coating inhibitor obtained in Comparative Example 3 is epoxy-based hyperbranched polysiloxane. By comparing and analyzing Example 1 and Comparative Example 3, it can be seen that the coating inhibitor of Example 1 is guanidyl epoxy-based 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; it shows that the Schiff base structure at the end group has a better protective effect on the carbon steel substrate compared with the epoxy group structure.

[0117] In Comparative Example 4, the epoxy ring-opening reaction was carried out by adding 1,1,3,3-tetramethylguanidine at room temperature. The test results showed that the epoxy group could not be ring-opened under low-temperature conditions, and guanidyl epoxy hyperbranched polysiloxane was not formed. Compared with the results of Comparative Example 3, the saltwater resistance and salt spray resistance were comparable.

[0118] Examples 1, 3 and Comparative Example 5 were compared for different addition amounts of guanidyl epoxy hyperbranched polysiloxane. It can be seen that excellent protection effects can be obtained when the addition ratio of guanidyl hyperbranched polysiloxane coating corrosion inhibitor to waterborne epoxy resin is 0.2~0.375:1; at the same time, compared with the prior art, the addition amount is significantly reduced.

[0119] The above description of the embodiments is for the convenience of those of ordinary skill in the art to understand and use the invention. 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 labor. Therefore, the present invention is not limited to the above embodiments, and the improvements and modifications made by those skilled in the art without departing from the scope of the present invention according to the disclosure 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: Adding 1,1,3,3-tetramethylguanidine to the epoxy hyperbranched polysiloxane to carry out an epoxy ring-opening reaction, thereby obtaining the guanidine hyperbranched polysiloxane coating corrosion inhibitor; The guanidine hyperbranched polysiloxane coating corrosion inhibitor and epoxy phosphate ester act synergistically in the waterborne epoxy anticorrosive coating and coordinate with the metal substrate to form a passivation film; The waterborne epoxy anticorrosive coating comprises the guanidine-based hyperbranched polysiloxane coating corrosion inhibitor and a waterborne epoxy resin; The mass ratio of the guanidine hyperbranched polysiloxane coating corrosion inhibitor to the waterborne epoxy resin is 0.2-0.375:1; The structural formula of the guanidine hyperbranched polysiloxane coating corrosion inhibitor is: ； Among them, the structural formula of R is .

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 epoxy phosphate, filler and additives, stir and grind, finally add curing agent and stir evenly to 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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