Quick-drying moisture-curing composite layer coating as well as preparation method and application thereof

Abstract

The invention discloses a quick-drying moisture-curing composite layer coating as well as a preparation method and application thereof, and belongs to the technical field of coatings for renovating and repairing railroad bridges. The quick-drying moisture-curing composite layer coating comprises the following components in parts by weight: primer and finish paint, the primer comprises a component A and a component B; the component A comprises 45-60 parts of epoxy resin, 5-10 parts of polysulfide rubber, 5-10 parts of zinc phosphate, 2-6 parts of sodium lauryl sulfate, 2-4 parts of a surfactant, 8-12 parts of self-made fluorine modified hydrotalcite and 5-10 parts of xylene; the component B is prepared from 45 to 55 parts of modified curing agent, 20 to 30 parts of ethanol and 1 to 3 parts of DMP-30 accelerant. The component B in the primer coating contains the reaction accelerator, the ethanol and the modified curing agent, so that moisture curing at a relatively high speed can be realized; and the steel structure of the railway bridge can be renovated and repaired within a short time.

Description

Technical Field

[0001] The present invention belongs to the technical field of coatings for railway bridge renovation and repair, and specifically relates to a quick-drying moisture-curing composite layer coating and a preparation method and application thereof. Background Art

[0002] Traditional coatings consume a lot of energy during the curing process and take a long time to cure. There is also the problem of volatile organic compounds (VOCs) emissions. Moisture-curing coatings can achieve rapid curing of the coating under the action of moisture, and have excellent hardness and durability after curing. They can also effectively reduce VOCs emissions. They not only improve production efficiency and reduce coating costs, but also reduce energy consumption, which is in line with the green and efficient development trend of modern manufacturing.

[0003] The prior art includes a Chinese invention patent with application number: CN202210717063.3, which discloses a solvent-free wet-on-wet epoxy anticorrosive primer and its preparation method. The anticorrosive coating consists of component A and component B, and the weight proportions of component A and component B are as follows: component A: 10-50 parts of composite epoxy resin, 1-30 parts of inactive diluent, 1-30 parts of pigment, 1-20 parts of antirust pigment, 10-50 parts of filler, 1-10 parts of rheological additive, and 1-5 parts of dispersant; component B: 90-100 parts of composite amine curing agent and 5-15 parts of reaction accelerator. The application scenarios of the above-mentioned prior art are mainly limited to the first coating of steel structures and bridges; they cannot be well applied to the renovation and repair of railway bridges.

[0004] Specifically for the paint used for railway bridge renovation and repair, the general repair environment mainly involves operations at the skylight point (12:00-4:00 in the morning), during which time period is low temperature, high humidity, and there are dewdrops; the existing bridge steel structure is affected by the outdoors. When renovating and repairing the bridge, it is difficult to obtain an ideal surface treatment state due to the constraints of the shape of the bridge steel structure components and on-site construction conditions. In addition, the difficulty of on-site renovation and repair will lead to poor pre-treatment.

[0005] However, if the coating prepared by the above-mentioned prior art is applied on a steel structure that has not been strictly surface treated, the bottom biting phenomenon may occur, and the bonding strength of the above-mentioned prior art still needs to be improved.

[0006] Therefore, in order to solve the above technical problems, the present application provides a quick-drying moisture-curing composite layer coating and its preparation method and application, which can complete the purpose of railway bridge renovation and repair within the window time. Summary of the invention

[0007] In order to solve the defects existing in the above technical solutions, the purpose of the present invention is to provide a fast-drying moisture-curing composite layer coating and its preparation method and application. The purpose of the present invention can be achieved by the following technical solutions: a fast-drying moisture-curing composite layer coating, including a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 45-60 parts of epoxy resin, 5-10 parts of polysulfide rubber, 5-10 parts of zinc phosphate, 2-6 parts of sodium lauryl sulfate, 2-4 parts of surfactant, 8-12 parts of homemade fluorine-modified hydrotalcite, and 5-10 parts of xylene; The B component includes: 45-55 parts of modified curing agent, 20-30 parts of ethanol, and 1-3 parts of DMP-30 accelerator; The epoxy resin is bisphenol A epoxy resin NPEL-128; purchased from Nanya Electronic Materials Kunshan Co., Ltd. The surfactant is any one of BYK-348 and BYK-307; The modified curing agent is a modified fatty amine curing agent XH-466D; it is purchased from Shenzhen Jiadida New Material Technology Co., Ltd.

[0008] Preparation method of homemade fluorine-modified hydrotalcite: weigh 15g magnesium nitrate hexahydrate and 8g aluminum nitrate nonahydrate and dissolve them in 100mL deionized water. Under nitrogen protection, continue to drip 20mL deionized water into the solution, and at the same time drip a 0.1mol / L NaOH solution to adjust the pH value of the solution to 10-11; then place the obtained solution in a 70℃ constant temperature water bath and stir for 10h, then heat it to 100℃ and crystallize for 8h; filter and wash with water until the pH value is 7; then place it in a vacuum dryer and dry it for 5h to prepare the intermediate product; place the intermediate product in a 500℃ muffle furnace and calcine it for 4h, and cool it to room temperature under nitrogen protection. Add the intermediate product to a 0.1mol / L KF aqueous solution, stir it at room temperature for 24h, and finally filter, wash with water, and vacuum dry it to prepare the homemade fluorine-modified hydrotalcite.

[0009] Furthermore, in the preparation process of the homemade fluorine-modified hydrotalcite, 100 mL of KF aqueous solution with a concentration of 0.1 mol / L is required per gram of intermediate product; Furthermore, the CAS number of magnesium nitrate hexahydrate in the preparation process of the homemade fluorine-modified hydrotalcite is: 13446-18-9; Furthermore, the CAS number of aluminum nitrate nonahydrate in the preparation process of the homemade fluorine-modified hydrotalcite is: 7784-27-2.

[0010] The preparation method of the primer comprises the following steps: at room temperature, weighing component A in sequence according to a formula and placing it in a container; after each component is added, stirring it fully and evenly for 5 minutes; after adding the last raw material, stirring it fully and evenly again, standing it for 4-8 hours, then covering and sealing it, and placing it in a dry and cool place for use; at room temperature, the three components in component B are accurately weighed, placed in a stirring container, stirring it fully and evenly for 5 minutes, then covering and sealing it, and placing it in a dry and cool place for use; during storage, component A and component B need to be stored separately to avoid reaction; during construction, first pour component A into the stirring container, then add component B while stirring it, and continue stirring for 3 minutes after component B is added; thus, the primer is prepared and can be used for spraying construction.

[0011] During the preparation of the primer, the mass ratio of component A to component B is component A: component B = 1:1; The topcoat; its components include: 70-80 parts of polyether polyol, 10-15 parts of 4,4-diphenylmethane diisocyanate, 0.1-0.3 parts of dibutyltin dilaurate, 5-8 parts of plasticizer, 8-12 parts of modified silica powder, 4-8 parts of latent curing agent, 0.1-0.3 parts of defoaming agent, and 0.3-0.8 parts of leveling agent; The polyether polyol is a polyether triol; In specific implementation, the polyether polyol used in this application is a polyether triol purchased from Shandong Bluestar Dongda Polyether Company, with a brand name of EP3600, Mn = 6000, moisture ≤ 0.05%, and functionality of 3; The plasticizer is any one of dinonyl phthalate or didecyl phthalate.

[0012] The preparation method of the modified silicon micropowder is as follows: 10g of silicon micropowder, 0.4g of KH550, and 1.1g of tridecafluorooctyl triethoxysilane are weighed; KH550 and tridecafluorooctyl triethoxysilane are added to a mixed solution of deionized water and alcohol, and heated to 50 degrees Celsius for 1 hour to ensure the hydrolysis of the coupling agent to form a hydrolyzate; the silicon micropowder is placed in ethanol, and dispersed for 1 hour using a high-speed disperser to form a silicon micropowder suspension; the hydrolyzate is added to the stirred silicon micropowder suspension, and stirring is continued for 0.5 hours; the suspension is then dried in an air flow oven at 120 degrees Celsius, and passed through a 150-mesh sieve to prepare the homemade modified silicon micropowder.

[0013] Preparation of the topcoat: first, add polyether triol into a dry three-necked flask, vacuum dehydrate at 120°C for 0.5-1h, cool to about 60°C, add diphenylmethane diisocyanate and plasticizer, stir evenly, then add dibutyltin dilaurate, slowly heat to 80°C, keep warm for reaction for 2h under the protection of dry nitrogen, cool and discharge to obtain a prepolymer; then place it in a high-speed dispersion kettle, control the temperature at 40-50 degrees Celsius, slowly add modified silicon micropowder, disperse at high speed for 30 minutes, add latent curing agent and defoaming agent, and stir at low speed for 5 minutes; finally, add leveling agent and stir at low speed for 3 minutes; after sufficient dispersion, a primer that can be used for spraying is prepared.

[0014] The invention discloses an application of a quick-drying moisture-curing composite coating in the renovation and repair of railway bridge steel structures.

[0015] When the quick-drying moisture-curing composite layer coating is used, the railway bridge to be renovated or repaired is first polished, then dusted, and then a primer is sprayed. After the primer is moisture-cured to a surface dry state, a topcoat is sprayed, thus completing the renovation and repair of the steel structure of the railway bridge.

[0016] The present invention has the beneficial effects: 1. The present application introduces self-made fluorine-modified hydrotalcite into the primer, wherein the layered structure of the hydrotalcite itself can fill the tiny defects on the surface of the substrate, so it has a strong covering ability on the rough or contaminated surface; it can be used for the renovation and maintenance of bridge steel structures, and the layered structure and large surface area of ​​the hydrotalcite can provide more contact points, thereby enhancing the adhesion between the primer and the surface of the steel structure; the hydrotalcite modified by fluorine ion intercalation has an increased interlayer spacing, which can alleviate the stress concentration on the primer surface, thereby weakening the generation and expansion of cracks; the larger interlayer space can also reduce the interaction between particles and promote the dispersion of the modified hydrotalcite in the primer; and the modified hydrotalcite added to the primer can act as a barrier to prevent further erosion by moisture and corrosive substances, improve the salt spray resistance of the primer, and thus enhance the corrosion resistance of the primer; 2. The component B in the primer coating of the present application contains a reaction accelerator and ethanol, as well as a modified fatty amine curing agent, which can achieve a relatively fast moisture curing; the reaction accelerator can catalyze the reaction between the epoxy group and the amine group; the ethanol can absorb moisture in the environment and is easy to volatilize itself; so that the renovation and repair of the steel structure of the railway bridge can be completed in a relatively short time; so that it has a faster surface drying and actual drying speed; 3. The silicon micropowder introduced in the topcoat of the present application is modified by KH550 and tridecafluorooctyl triethoxysilane, wherein tridecafluorooctyl triethoxysilane can form a hydrophobic CF chain on the surface of silicon micropowder, reduce the surface energy of the topcoat, significantly increase the water contact angle, and reduce water adsorption and improve water resistance; and KH550 can form Si-O-Si bonds on the surface of silicon micropowder, which can enhance the combination of silicon micropowder and polyether polyol, reduce the agglomeration of silicon micropowder filler, improve dispersibility, and improve the weather resistance of the topcoat; 4. The primer used in the present application is a fluorine ion intercalation modified primer, and the modified hydrotalcite can be better compatible with epoxy resin; and the modified silica powder in the topcoat also uses fluorinated silane modified silica powder; although fluorine is introduced into both the primer and the topcoat, the hydrotalcite in the primer has a layered structure and can also increase the interlayer adhesion between the primer and the topcoat. Under the synergistic effect of the two, a continuous hydrophobic interface layer can be formed in the composite coating, so that the composite layer coating has beneficial weather resistance and anti-corrosion properties. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiment, and the illustrative embodiments of the present invention and its description are only used to explain the present invention, and are not used as limitation of the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper limit and the lower limit of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the range is also included in the present invention. The upper limit and lower limit of these smaller ranges can be independently included or excluded in the scope.

[0018] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0019] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0020] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0021] The "parts" indicated in the following examples are all parts by weight.

[0022] Example 1 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; Component A in the primer includes: 45 parts of epoxy resin, 5 parts of polysulfide rubber, 5 parts of zinc phosphate, 2 parts of sodium lauryl sulfate, 2 parts of surfactant, 8 parts of homemade fluorine-modified hydrotalcite, and 5 parts of xylene; Component B in the primer includes: 45 parts of modified curing agent, 20 parts of ethanol, and 1 part of DMP-30 accelerator; The epoxy resin is bisphenol A epoxy resin NPEL-128, purchased from Nanya Electronic Materials Kunshan Co., Ltd. The surfactant is BYK-348; The modified curing agent is a modified fatty amine curing agent XH-466D, which is purchased from Shenzhen Jiadida New Material Technology Co., Ltd.

[0023] The preparation method of the homemade fluorine-modified hydrotalcite in the A component is as follows: weigh 15g of magnesium nitrate hexahydrate and 8g of aluminum nitrate nonahydrate and dissolve them in 100mL of deionized water. Under nitrogen protection, continue to drip 20mL of deionized water into the solution, and at the same time drip a NaOH solution with a concentration of 0.1mol / L, and adjust the pH value of the solution to 10-11; then place the obtained solution in a 70°C constant temperature water bath and stir for 10h, then heat it to 100°C and crystallize for 8h; filter and wash with water until the pH value is 7; then place it in a vacuum dryer and dry it for 5h to prepare the intermediate product; place the intermediate product in a 500°C muffle furnace and calcine it for 4h, and cool it to room temperature under nitrogen protection. Add the intermediate product to a KF aqueous solution with a concentration of 0.1mol / L, stir it at room temperature for 24h, and finally filter, wash with water, and vacuum dry it to prepare the homemade fluorine-modified hydrotalcite; In a specific implementation, during the preparation process of the homemade fluorine-modified hydrotalcite, 100 mL of a 0.1 mol / L KF aqueous solution is required per gram of the intermediate product; In a specific implementation, the CAS number of magnesium nitrate hexahydrate in the preparation process of the homemade fluorine-modified hydrotalcite is: 13446-18-9; In a specific implementation, the CAS number of aluminum nitrate nonahydrate in the preparation process of the homemade fluorine-modified hydrotalcite is: 7784-27-2.

[0024] The preparation method of the primer comprises the following steps: at room temperature, weighing component A in sequence according to a formula and placing it in a container; after each component is added, stirring it fully and evenly for 5 minutes; after adding the last raw material, stirring it fully and evenly again, standing it for 4-8 hours, then covering and sealing it, and placing it in a dry and cool place for use; at room temperature, the three components in component B are accurately weighed, placed in a stirring container, stirring it fully and evenly for 5 minutes, then covering and sealing it, and placing it in a dry and cool place for use; during storage, component A and component B need to be stored separately to avoid reaction; during construction, first pour component A into the stirring container, then add component B while stirring it, and continue stirring for 3 minutes after component B is added; thus, the primer is prepared and can be used for spraying construction.

[0025] During the preparation of the primer, the mass ratio of component A to component B is component A: component B = 1:1; The topcoat comprises: 70 parts of polyether polyol, 10 parts of 4,4-diphenylmethane diisocyanate, 0.1 parts of dibutyltin dilaurate, 5 parts of plasticizer, 8 parts of modified silica powder, 4 parts of latent curing agent, 0.1 parts of defoaming agent and 0.3 parts of leveling agent; The polyether polyol is a polyether triol; In specific implementation, the polyether polyol used in this application is a polyether triol purchased from Shandong Bluestar Dongda Polyether Company, with a brand name of EP3600, Mn = 6000, moisture ≤ 0.05%, and functionality of 3; The plasticizer is any one of didecyl phthalate.

[0026] The preparation method of the modified silicon micropowder is as follows: 10g of silicon micropowder, 0.4g of KH550, and 1.1g of tridecafluorooctyl triethoxysilane are weighed; KH550 and tridecafluorooctyl triethoxysilane are added to a mixed solution of deionized water and alcohol, and heated to 50 degrees Celsius for 1 hour to ensure the hydrolysis of the coupling agent to form a hydrolyzate; the silicon micropowder is placed in ethanol, and dispersed for 1 hour using a high-speed disperser to form a silicon micropowder suspension; the hydrolyzate is added to the stirred silicon micropowder suspension, and stirring is continued for 0.5 hours; the suspension is then dried in an air flow oven at 120 degrees Celsius, and passed through a 150-mesh sieve to prepare the homemade modified silicon micropowder.

[0027] Preparation of the topcoat: first, add polyether triol into a dry three-necked flask, vacuum dehydrate at 120°C for 0.5-1h, cool to about 60°C, add diphenylmethane diisocyanate and plasticizer, stir evenly, then add dibutyltin dilaurate, slowly heat to 80°C, keep warm for reaction for 2h under dry nitrogen protection, cool and discharge to obtain a prepolymer; then place it in a high-speed dispersion kettle, control the temperature at 40-50 degrees Celsius, slowly add modified silicon micropowder, disperse at high speed for 30 minutes, add latent curing agent and defoaming agent, and stir at low speed for 5 minutes; finally, add leveling agent and stir at low speed for 3 minutes; after sufficient dispersion, a primer that can be used for spraying is prepared.

[0028] Example 2 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 48 parts of epoxy resin, 5 parts of polysulfide rubber, 6 parts of zinc phosphate, 3 parts of sodium lauryl sulfate, 3 parts of surfactant, 9 parts of homemade fluorine-modified hydrotalcite, and 6 parts of xylene; The B component includes: 48 parts of modified curing agent, 23 parts of ethanol, and 1.5 parts of DMP-30 accelerator; The surfactant is BYK-348; The topcoat; its components include: 72 parts of polyether polyol, 11 parts of 4,4-diphenylmethane diisocyanate, 0.15 parts of dibutyltin dilaurate, 6 parts of plasticizer, 9 parts of modified silica powder, 5 parts of latent curing agent, 0.15 parts of defoaming agent, and 0.5 parts of leveling agent; The plasticizer is dinonyl phthalate; Among them, the preparation method of the homemade fluorine-modified hydrotalcite, the preparation method of the primer, the preparation method of the modified silica powder, and the preparation method of the topcoat in Example 2 are all consistent with those in Example 1.

[0029] Example 3 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, 10 parts of homemade fluorine-modified hydrotalcite, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; The surfactant is BYK-307; The topcoat; its components include: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 parts of dibutyltin dilaurate, 6 parts of plasticizer, 10 parts of modified silica powder, 6 parts of latent curing agent, 0.2 parts of defoaming agent, and 0.6 parts of leveling agent; The plasticizer is any one of didecyl phthalate; Among them, the preparation method of the homemade fluorine-modified hydrotalcite, the preparation method of the primer, the preparation method of the modified silica powder, and the preparation method of the topcoat in Example 3 are all consistent with those in Example 1.

[0030] Example 4 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 56 parts of epoxy resin, 9 parts of polysulfide rubber, 9 parts of zinc phosphate, 5 parts of sodium lauryl sulfate, 4 parts of surfactant, 11 parts of homemade fluorine-modified hydrotalcite, and 9 parts of xylene; The B component includes: 53 parts of modified curing agent, 28 parts of ethanol, and 2.5 parts of DMP-30 accelerator; The surfactant is BYK-307; The topcoat; its components include: 78 parts of polyether polyol, 14 parts of 4,4-diphenylmethane diisocyanate, 0.25 parts of dibutyltin dilaurate, 7 parts of plasticizer, 11 parts of modified silica powder, 7 parts of latent curing agent, 0.25 parts of defoaming agent, and 0.7 parts of leveling agent; The plasticizer is dinonyl phthalate; Among them, the preparation method of the homemade fluorine-modified hydrotalcite, the preparation method of the primer, the preparation method of the modified silica powder, and the preparation method of the topcoat in Example 4 are all consistent with those in Example 1.

[0031] Example 5 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 60 parts of epoxy resin, 10 parts of polysulfide rubber, 10 parts of zinc phosphate, 6 parts of sodium lauryl sulfate, 4 parts of surfactant, 12 parts of homemade fluorine-modified hydrotalcite, and 10 parts of xylene; The B component includes: 55 parts of modified curing agent, 30 parts of ethanol, and 3 parts of DMP-30 accelerator; The surfactant is BYK-307; The topcoat; its components include: 80 parts of polyether polyol, 15 parts of 4,4-diphenylmethane diisocyanate, 0.3 parts of dibutyltin dilaurate, 8 parts of plasticizer, 12 parts of modified silica powder, 8 parts of latent curing agent, 0.3 parts of defoaming agent, and 0.8 parts of leveling agent; The plasticizer is didecyl phthalate; Among them, the preparation method of the homemade fluorine-modified hydrotalcite, the preparation method of the primer, the preparation method of the modified silica powder, and the preparation method of the topcoat in Example 5 are all consistent with those in Example 1.

[0032] Comparative Example 1 A primer, comprising component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; Wherein, the preparation method of the primer in Comparative Example 1 is consistent with that in Example 3.

[0033] Comparative Example 2 A primer, comprising component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, 10 parts of hydrotalcite, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; Among them, the preparation method of the primer in Comparative Example 2 is consistent with that in Example 3.

[0034] Comparative Example 3 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, 10 parts of homemade fluorine-modified hydrotalcite, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; The topcoat; its components include: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 parts of dibutyltin dilaurate, 6 parts of plasticizer, 6 parts of latent curing agent, 0.2 parts of defoaming agent, and 0.6 parts of leveling agent; Among them, the preparation method of the homemade fluorine-modified hydrotalcite, the preparation method of the primer, and the preparation method of the topcoat in Example 3 are all consistent with Example 3.

[0035] Comparative Example 4 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, 10 parts of homemade fluorine-modified hydrotalcite, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; The topcoat; its components include: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 parts of dibutyltin dilaurate, 6 parts of plasticizer, 10 parts of silica powder, 6 parts of latent curing agent, 0.2 parts of defoaming agent, and 0.6 parts of leveling agent; Among them, the preparation method of the homemade fluorine-modified hydrotalcite, the preparation method of the primer, and the preparation method of the topcoat in Example 3 are all consistent with Example 3.

[0036] Comparative Example 5 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, 10 parts of hydrotalcite, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; The topcoat; its components include: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 parts of dibutyltin dilaurate, 6 parts of plasticizer, 10 parts of silica powder, 6 parts of latent curing agent, 0.2 parts of defoaming agent, and 0.6 parts of leveling agent; Among them, the preparation method of the primer and the preparation method of the topcoat in Example 3 are consistent with those in Example 3.

[0037] Comparative Example 6 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; The topcoat; its components include: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 parts of dibutyltin dilaurate, 6 parts of plasticizer, 6 parts of latent curing agent, 0.2 parts of defoaming agent, and 0.6 parts of leveling agent; Among them, the preparation method of the primer and the preparation method of the topcoat in Example 3 are consistent with those in Example 3.

[0038] Comparative Example 7 A quick-drying moisture-curing composite coating comprises a primer and a topcoat; The primer comprises component A and component B; The component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium lauryl sulfate, 3 parts of surfactant, 10 parts of hydrotalcite, and 8 parts of xylene; The B component includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator; The topcoat comprises: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 parts of dibutyltin dilaurate, 6 parts of plasticizer, 10 parts of modified silica powder, 6 parts of latent curing agent, 0.2 parts of defoaming agent and 0.6 parts of leveling agent; Among them, the preparation method of the primer, the preparation method of the modified silica powder, and the preparation method of the topcoat in Comparative Example 7 are all consistent with those in Example 3.

[0039] Test Example: The primers prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to the following performance tests, including: Refer to the test method in the industry standard HG / / T 4564-2013 "Epoxy Coatings with Low Surface Treatment Tolerance" to test compatibility with the old paint film; if the paint film surface is flat, without bites, wrinkles, etc., and the cross-cut test with the old paint film is ≤ level 1, it is "no abnormality"; Refer to GB / T 1728-2020 "Determination of Drying Time of Paint Film and Putty Film" to measure the surface drying time and actual drying time of the primer film. The relative humidity during drying is greater than 60%; Refer to GB / T 5210-2006 "Pull-off adhesion test for paints and varnishes" to complete the test of primer film adhesion; Refer to GB / T 10125-2021 "Artificial atmosphere corrosion test salt spray test" to test the salt spray resistance of the primer; The test results are shown in Table 1: Table 1 Comprehensive performance analysis: This application introduces homemade fluorine-modified hydrotalcite into the primer, wherein the layered structure of the hydrotalcite itself can fill the tiny defects on the surface of the substrate, so it has a strong covering ability on rough or contaminated surfaces; it can be used for the renovation and maintenance of bridge steel structures, and the layered structure and large surface area of ​​the hydrotalcite can provide more contact points, thereby enhancing the adhesion between the primer and the surface of the steel structure; the hydrotalcite modified by fluorine ion intercalation has an increased interlayer spacing, which can alleviate the stress concentration on the primer surface, thereby weakening the generation and expansion of cracks; the larger interlayer space can also reduce the interaction between particles and promote the dispersion of the modified hydrotalcite in the primer; and the modified hydrotalcite added to the primer can act as a barrier to block further erosion by moisture and corrosive substances, improve the salt spray resistance of the primer, and thus enhance the corrosion resistance of the primer.

[0040] Component B in the primer coating of the present application contains a reaction accelerator and ethanol, as well as a modified curing agent, which can achieve moisture curing at a relatively fast speed; the reaction accelerator can catalyze the reaction of epoxy groups and amine groups; ethanol can absorb moisture in the environment and is easily volatilized; so that the renovation and repair of the steel structure of the railway bridge can be completed in a relatively short period of time; and since Comparative Example 2 does not contain hydrotalcite, it has a faster surface drying and actual drying speed.

[0041] Test Example: The composite layer coatings prepared in Examples 1-5 and Comparative Examples 3-7 were subjected to the following performance tests, including: Refer to GB / T 19250-2013, Polyurethane Waterproof Coatings, to test the 30-day water absorption rate of the composite coating; The water contact angle is tested by using a contact angle meter; Refer to GB-T 1865 "Paints and varnishes - Artificial weathering and artificial radiation exposure to filtered xenon arc radiation" to test the artificial weathering resistance of composite coatings; With reference to GB / T 9274 “Determination of resistance of paints and varnishes to liquid media”, the acid resistance and alkali resistance of the prepared composite layer coating were tested.

[0042] The test results are shown in Table 2: Table 2 Comprehensive performance analysis: Compared with Examples 1-5, the performance indicators of Comparative Examples 3, 4, 5, and 6 all have obvious performance differences. The possible reasons are: the silicon micropowder introduced in the topcoat of the present application is jointly modified by KH550 and tridecafluorooctyl triethoxysilane, wherein tridecafluorooctyl triethoxysilane can form a hydrophobic CF chain on the surface of the silicon micropowder, reduce the surface energy of the topcoat, significantly increase the water contact angle, and can reduce water adsorption and improve water resistance; and KH550 can form Si-O-Si bonds on the surface of the silicon micropowder, which can enhance the combination of silicon micropowder and polyether polyol, reduce the agglomeration of silicon micropowder filler, improve dispersibility, and improve the weather resistance of the topcoat.

[0043] The difference between Comparative Example 7 and Example 3 is that only the primer does not use the homemade fluorine-modified hydrotalcite. Its water contact angle and resistance to artificial weathering are the best among the comparative examples, but there is still a certain performance gap with Examples 1-5. The possible reason is that: the primers of Examples 1-5 of the present application use fluorine ion intercalation modified primers, and the modified hydrotalcite can be better compatible with epoxy resin; and the modified silicon micropowder in the topcoat also uses fluorinated silane modified silicon micropowder; although fluorine is introduced into both the primer and the topcoat, the layered structure of the hydrotalcite in the primer can also increase the interlayer adhesion between the primer and the topcoat. Under the synergistic effect of the two, a continuous hydrophobic interface layer can be formed in the composite coating, so that the composite layer coating has beneficial weather resistance and anti-corrosion properties.

[0044] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A quick-drying moisture-curing composite coating, characterized in that: The quick-drying moisture-curing composite coating comprises a primer and a topcoat in parts by weight; The primer comprises component A and component B; The component A comprises: 45-60 parts of epoxy resin, 5-10 parts of polysulfide rubber, 5-10 parts of zinc phosphate, 2-6 parts of sodium lauryl sulfate, 2-4 parts of surfactant, 8-12 parts of homemade fluorine-modified hydrotalcite, and 5-10 parts of xylene; The B component includes: 45-55 parts of modified curing agent, 20-30 parts of ethanol, and 1-3 parts of DMP-30 accelerator; The topcoat comprises components of: 70-80 parts of polyether polyol, 10-15 parts of 4,4-diphenylmethane diisocyanate, 0.1-0.3 parts of dibutyltin dilaurate, 5-8 parts of plasticizer, 8-12 parts of modified silica powder, 4-8 parts of latent curing agent, 0.1-0.3 parts of defoaming agent and 0.3-0.8 parts of leveling agent.

2. A quick-drying moisture-curing composite coating as claimed in claim 1, characterized in that: The epoxy resin in component A of the primer is bisphenol A type epoxy resin NPEL-128.

3. A quick-drying moisture-curing composite coating as claimed in claim 1, characterized in that: The surfactant in component A of the primer is any one of BYK-348 and BYK-307.

4. A quick-drying moisture-curing composite coating as claimed in claim 1, characterized in that: The modified curing agent in component B of the primer is a modified fatty amine curing agent XH-466D.

5. A quick-drying moisture-curing composite coating as claimed in claim 1, characterized in that: The polyether polyol in the topcoat is a polyether triol.

6. A quick-drying moisture-curing composite layer coating as claimed in claim 1, characterized in that: The plasticizer in the topcoat is any one of dinonyl phthalate and didecyl phthalate.

7. The fast-drying moisture-curing composite layer coating according to any one of claims 1 to 6, characterized in that: The preparation method of the homemade fluorine-modified hydrotalcite in the primer is as follows: magnesium nitrate hexahydrate and aluminum nitrate nonahydrate are dissolved in deionized water, and deionized water is continuously dripped into the solution under nitrogen protection, and NaOH solution is dripped at the same time to adjust the pH value of the solution to 10-11; the prepared solution is then placed in a 70°C constant temperature water bath and stirred for 10 hours, and then the temperature is raised to 100°C for crystallization for 8 hours; filtered, and washed with water until the pH value is 7; then placed in a vacuum dryer and dried for 5 hours to prepare an intermediate product; the intermediate product is placed in a 500°C muffle furnace for calcination for 4 hours, and cooled to room temperature under nitrogen protection; finally, the intermediate product is added to a KF aqueous solution, stirred at room temperature for 24 hours, and finally filtered, washed with water, and vacuum dried to prepare the homemade fluorine-modified hydrotalcite.

8. The fast-drying moisture-curing composite layer coating according to any one of claims 1 to 6, characterized in that: The preparation method of the modified silicon micropowder in the topcoat is as follows: KH550 and tridecafluorooctyl triethoxysilane are added to a mixed solution of deionized water and alcohol, and heated to 50 degrees Celsius for 1 hour to ensure the hydrolysis of the coupling agent to form a hydrolyzate; the silicon micropowder is placed in ethanol and dispersed by a high-speed disperser for 1 hour to form a silicon micropowder suspension; the hydrolyzate is added to the stirred silicon micropowder suspension, and stirring is continued for 0.5 hours; the suspension is then dried in an air flow oven at 120 degrees Celsius, and passed through a 150-mesh sieve to prepare the homemade modified silicon micropowder.

9. A method for preparing the fast-drying moisture-curing composite layer coating according to any one of claims 1 to 6, characterized in that: The preparation method of the primer is as follows: at room temperature, component A is weighed in sequence according to a formula and placed in a container; after each component is added, it is fully and evenly stirred for 5 minutes; after the last raw material is added, it is fully and evenly stirred again, and it is left to stand for 4-8 hours, then it is sealed with a cover, and placed in a dry and cool place for use; at room temperature, the three components in component B are accurately weighed, placed in a stirring container, fully and evenly stirred for 5 minutes, then it is sealed with a cover, and placed in a dry and cool place for use; during storage, component A and component B need to be stored separately to avoid reaction; during construction, component A is first poured into the stirring container, and then component B is added while stirring, and after component B is added, stirring is continued for 3 minutes; the primer is thus prepared and can be used for spraying construction; During the preparation of the primer, the mass ratio of component A to component B is component A: component B = 1:1; The preparation of the topcoat is as follows: first, polyether triol is added to a dry three-necked flask, vacuum dehydration is carried out at 120° C. for 0.5 to 1 h, the temperature is lowered to about 60° C., diphenylmethane diisocyanate and a plasticizer are added, and the mixture is stirred evenly, and then dibutyltin dilaurate is added, the temperature is slowly raised to 80° C., and the mixture is kept warm for reaction for 2 h under the protection of dry nitrogen, and the mixture is cooled and discharged to obtain a prepolymer; then, the prepolymer is placed in a high-speed dispersion kettle, the temperature is controlled at 40-50° C., modified silicon micropowder is slowly added, and after high-speed dispersion for 30 min, a latent curing agent and a defoaming agent are added, and the mixture is stirred at a low speed for 5 min; finally, a leveling agent is added, and the mixture is stirred at a low speed for 3 min; after being fully dispersed evenly, a primer that can be used for spraying is prepared.

10. Use of the quick-drying moisture-curing composite layer coating according to any one of claims 1 to 6 in the renovation and repair of railway bridge steel structures.

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