A fast-drying moisture-curing composite layer coating, its preparation method and application

Abstract

The present invention discloses a quick-drying moisture-curing composite layer coating, its preparation method and application, belonging to the technical field of coatings for railway bridge renovation and repair; by weight, its composition is as follows. The quick-drying moisture-curing composite layer coating includes a primer and a topcoat; the primer includes component A and component B; component A includes: 45-60 parts of epoxy resin, 5-10 parts of polysulfide rubber, 5-10 parts of zinc phosphate, 2-6 parts of sodium dodecyl sulfate, 2-4 parts of surfactant, 8-12 parts of self-made fluorine-modified hydrotalcite, 5-10 parts of xylene; component B includes: 45-55 parts of modified curing agent, 20-30 parts of ethanol, 1-3 parts of DMP-30 accelerator. Component B in the primer coating of this application contains a reaction accelerator, ethanol, and a modified curing agent, which can achieve moisture curing at a relatively fast speed; and can complete the renovation and repair of the steel structure of railway bridges in a relatively short time.

Description

Technical Field

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

[0002] Traditional coatings consume a large amount of energy during the curing process, have a long curing time, and also have the problem of volatile organic compound (VOCs) emissions; while moisture-curing coatings can achieve rapid curing of the coating under the action of moisture, and have excellent hardness and durability after curing, and can also effectively reduce VOCs emissions; it not only improves production efficiency, reduces painting costs but also reduces energy consumption, meeting the green and efficient development trend of modern manufacturing.

[0003] There is a prior art such as the Chinese invention patent with the application number: CN202210717063.3, which discloses a solvent-free wet-on-wet construction epoxy anti-corrosion primer and its preparation method. This anti-corrosion coating consists of component A and component B. The weight parts of component A and component B are as follows: Component A: 10 - 50 parts of composite epoxy resin, 1 - 30 parts of non-active diluent, 1 - 30 parts of pigment, 1 - 20 parts of anti-rust pigment, 10 - 50 parts of filler, 1 - 10 parts of rheology aid, 1 - 5 parts of dispersant; Component B: 90 - 100 parts of composite amine curing agent, 5 - 15 parts of reaction accelerator. The application scenarios of the above prior art are mainly limited to the first coating of steel structures and bridges; it cannot be well applied to the renovation and repair of railway bridges.

[0004] Specifically for coatings used in railway bridge renovation and repair, the general repair environment mainly involves operations during the skylight period (from 12:00 am to 4:00 am). This time period is characterized by low temperature, high humidity, and dew. Existing bridge steel structures, affected by the outdoors, are difficult to obtain an ideal surface treatment state during bridge renovation and repair due to the shape of the components of the bridge steel structure and the constraints of on-site construction conditions. Coupled with the great difficulty of on-site renovation and repair, the pretreatment will be very poor.

[0005] When the coating prepared by the above prior art is applied to a steel structure without strict surface treatment, the phenomenon of bottom biting may occur, and there is still room for improvement in the bonding strength of the above prior art.

[0006] Therefore, in order to solve the above technical problems, the present application provides a quick-drying moisture-curing composite layer coating, its preparation method and application for the purpose of railway bridge renovation and repair that can be completed within the skylight period. Summary of the Invention

[0007] To solve the defect problems existing in the above technical solutions; the purpose of the present invention is to provide a fast-drying moisture-curing composite layer coating, its preparation method and application. The purpose of the present invention can be achieved through the following technical solutions: A fast-drying moisture-curing composite layer coating, including a primer and a topcoat;

[0008] The primer includes component A and component B;

[0009] Component A includes: 45-60 parts of bisphenol A epoxy resin, 5-10 parts of polysulfide rubber, 5-10 parts of zinc phosphate, 2-6 parts of sodium dodecyl sulfate, 2-4 parts of surfactant, 8-12 parts of self-made fluorine-modified hydrotalcite, 5-10 parts of xylene;

[0010] Component B includes: 45-55 parts of modified curing agent, 20-30 parts of ethanol, 1-3 parts of DMP-30 accelerator;

[0011] The epoxy resin is bisphenol A epoxy resin NPEL-128; purchased from South Asia Electronic Materials Kunshan Co., Ltd.

[0012] The surfactant is any one of BYK-348 and BYK-307;

[0013] The modified curing agent is modified aliphatic amine curing agent XH-466D; purchased from Shenzhen Jiadida New Material Technology Co., Ltd.

[0014] Preparation method of self-made fluorine-modified hydrotalcite: Weigh 15 g of magnesium nitrate hexahydrate and 8 g of aluminum nitrate nonahydrate, dissolve them in 100 mL of deionized water. Under nitrogen protection, continue to add 20 mL of deionized water to the solution, and at the same time add a NaOH solution with a concentration of 0.1 mol / L to adjust the pH value of the solution to 10-11; then place the prepared solution in a 70°C constant temperature water bath and stir for 10 h, then raise the temperature to 100°C and crystallize for 8 h; filter and wash with water until the pH value is 7; then place it in a vacuum dryer and dry for 5 h to obtain the intermediate product; place the intermediate product in a muffle furnace at 500°C and calcine for 4 h, and cool to room temperature under nitrogen protection. Add the intermediate product to a 0.1 mol / L KF aqueous solution, stir at room temperature for 24 h, and finally filter, wash with water, and vacuum dry to obtain self-made fluorine-modified hydrotalcite.

[0015] Furthermore, in the preparation process of the self-made fluorine-modified hydrotalcite, each gram of the intermediate product requires 100 mL of a 0.1 mol / L KF aqueous solution;

[0016] Furthermore, the CAS number of magnesium nitrate hexahydrate in the preparation process of the self-made fluorine-modified hydrotalcite is: 13446-18-9;

[0017] Furthermore, the CAS number of aluminum nitrate nonahydrate in the preparation process of the self-made fluorine-modified hydrotalcite is: 7784-27-2.

[0018] The preparation method of the primer: Under room temperature conditions, the components of Component A are weighed sequentially according to the formula and placed in a container. After adding each component, it is stirred evenly for 5 minutes. After adding the last raw material, it is stirred evenly again and left to stand for 4 - 8 hours. Then it is sealed with a lid and stored in a dry and cool place for later use; Under room temperature conditions, the 3 components in Component B are accurately weighed and placed in a stirring container, stirred evenly for 5 minutes, then sealed with a lid and stored in a dry and cool place for later 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. After adding Component B, continue to stir for 3 minutes; Then the primer is prepared and can be used for spraying construction.

[0019] In the preparation process of the primer, the mass ratio of Component A to Component B is Component A: Component B = 1:1;

[0020] 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, 0.3 - 0.8 parts of leveling agent;

[0021] The polyether polyol is polyether triol;

[0022] Specifically, the polyether polyol used in this application is polyether triol, purchased from Shandong BlueStar Dongda Polyether Co., Ltd., with the brand number EP3600, its Mn = 6000, water content ≤ 0.05%, and functionality of 3;

[0023] The plasticizer is any one of dinonyl phthalate or didecyl phthalate.

[0024] The preparation method of the modified silica powder: Weigh 10g of silica powder, 0.4g of KH550, and 1.1g of tridecafluorooctyltriethoxysilane; Add KH550 and tridecafluorooctyltriethoxysilane to the mixed solution of deionized water and alcohol, and heat to 50 degrees Celsius, keep for 1 hour to ensure the hydrolysis of the coupling agent to form a hydrolysis solution; Place the silica powder in ethanol and disperse it with a high-speed disperser for 1 hour to form a silica powder suspension; Add the hydrolysis solution to the evenly stirred silica powder suspension and continue to stir for 0.5 hours; Then dry the suspension in an air flow oven at 120 degrees Celsius and pass it through a 150-mesh sieve to obtain the self-made modified silica powder.

[0025] 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.

[0026] The invention discloses an application of a quick-drying moisture-curing composite coating in the renovation and repair of railway bridge steel structures.

[0027] 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.

[0028] The present invention has the beneficial effects:

[0029] 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;

[0030] 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;

[0031] 3. The silica fume introduced into the topcoat of this application is co-modified by KH550 and tridecafluorooctyltriethoxysilane. The tridecafluorooctyltriethoxysilane among them can form hydrophobic C-F chains on the surface of the silica fume, reducing the surface energy of the topcoat, significantly increasing the water contact angle, and being able to reduce water adsorption and improve water resistance. And KH550 can form Si-O-Si bonds on the surface of the silica fume, which can enhance the combination of the silica fume and polyether polyol, reduce the agglomeration of the silica fume filler, improve the dispersibility, and enhance the weather resistance of the topcoat.

[0032] 4. The primer used in this application is a fluoride ion intercalation modified primer. The modified hydrotalcite can be better compatible with epoxy resin. And the modified silica fume in the topcoat is also a fluorinated silane modified silica fume. Although fluorine is introduced in 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 action of the two, a continuous hydrophobic interface layer can be formed in the composite coating, making the composite coating have beneficial weather resistance and anti-corrosion performance. Detailed Embodiments

[0033] To make the purpose, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with embodiments. The illustrative embodiments and descriptions of the present invention are only used to explain the present invention and do not limit the present invention. In addition, for the numerical ranges in the present invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each intermediate value within any stated value or stated range and each smaller range between any other stated value or intermediate value within the stated range are also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded from the range.

[0034] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which the present invention pertains. Although the present invention only describes preferred methods and materials, any methods and materials similar or equivalent to those described herein can 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 related to the documents. In case of conflict with any incorporated document, the content of this specification shall prevail.

[0035] Without departing from the scope or spirit of the present invention, various improvements and changes can be made to the specific embodiments of the present invention specification, which are obvious to those skilled in the art. Other embodiments obtained from the specification of the present invention are obvious to those skilled in the art. The specification and embodiments of the present invention are only exemplary.

[0036] The terms "comprising", "including", "having", "containing", etc. used in this text are all open-ended terms, meaning including but not limited to.

[0037] The "parts" mentioned in the following examples are all parts by weight.

[0038] Example 1

[0039] A fast-drying moisture-curing composite layer coating comprises a primer and a topcoat;

[0040] The primer comprises Component A and Component B;

[0041] Component A in the primer comprises: 45 parts of bisphenol A epoxy resin, 5 parts of polysulfide rubber, 5 parts of zinc phosphate, 2 parts of sodium dodecyl sulfate, 2 parts of surfactant, 8 parts of self-made fluorine-modified hydrotalcite, and 5 parts of xylene;

[0042] Component B in the primer comprises: 45 parts of modified curing agent, 20 parts of ethanol, and 1 part of DMP-30 accelerator;

[0043] The epoxy resin is bisphenol A epoxy resin NPEL-128, purchased from South Asia Electronic Materials Kunshan Co., Ltd.;

[0044] The surfactant is BYK-348;

[0045] The modified curing agent is modified aliphatic amine curing agent XH-466D, purchased from Shenzhen Jiadida New Material Technology Co., Ltd.

[0046] The preparation method of the self-made fluorine-modified hydrotalcite in Component A is as follows: Weigh 15 g of magnesium nitrate hexahydrate and 8 g of aluminum nitrate nonahydrate and dissolve them in 100 mL of deionized water. Under nitrogen protection, continue to add 20 mL of deionized water to the solution, and at the same time, add a NaOH solution with a concentration of 0.1 mol / L to adjust the pH value of the solution to 10 - 11; then place the prepared solution in a 70 °C constant temperature water bath and stir for 10 h, and then raise the temperature to 100 °C for crystallization for 8 h; filter and wash with water until the pH value is 7; then place it in a vacuum dryer and dry for 5 h to obtain the intermediate product; place the intermediate product in a muffle furnace at 500 °C and calcine for 4 h, and cool to room temperature under nitrogen protection. Add the intermediate product to a KF aqueous solution with a concentration of 0.1 mol / L, stir at room temperature for 24 h, and finally filter, wash with water, and vacuum dry to obtain the self-made fluorine-modified hydrotalcite;

[0047] Specifically, during the preparation process of the self-made fluorine-modified hydrotalcite, 100 mL of a KF aqueous solution with a concentration of 0.1 mol / L is required for each gram of the intermediate product;

[0048] In specific implementation, the CAS number of magnesium nitrate hexahydrate in the preparation process of the self-made fluorine-modified hydrotalcite is: 13446-18-9;

[0049] In specific implementation, the CAS number of aluminum nitrate nonahydrate in the preparation process of the self-made fluorine-modified hydrotalcite is: 7784-27-2.

[0050] The preparation method of the primer: Under room temperature conditions, the components of component A are weighed in sequence and placed in a container. After adding each component, it is stirred evenly for 5 minutes. After adding the last raw material, it is stirred evenly again and left standing for 4-8 hours. Then it is sealed with a lid and stored in a dry and cool place for later use; Under room temperature conditions, the 3 components in component B are accurately weighed, placed in a stirring container, and stirred evenly for 5 minutes. Then it is sealed with a lid and stored in a dry and cool place for later 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, and then stir while adding component B. After component B is added, continue to stir for 3 minutes; The primer is thus prepared and can be used for spraying construction.

[0051] In the preparation process of the primer, the mass ratio of component A to component B is component A: component B = 1:1;

[0052] The components of the topcoat include: 70 parts of polyether polyol, 10 parts of 4,4-diphenylmethane diisocyanate, 0.1 part of dibutyltin dilaurate, 5 parts of plasticizer, 8 parts of modified silica powder, 4 parts of latent curing agent, 0.1 part of defoaming agent, 0.3 part of leveling agent;

[0053] The polyether polyol is polyether triol;

[0054] In specific implementation, the polyether polyol used in this application is polyether triol, purchased from Shandong Bluestar Dongda Polyether Company, with the brand number EP3600, its Mn = 6000, water content ≤ 0.05%, and functionality of 3;

[0055] The plasticizer is any one of dioctyl phthalate.

[0056] The preparation method of the modified silica powder: Weigh 10 g of silica powder, 0.4 g of KH550, and 1.1 g of tridecafluorooctyltriethoxysilane; Add KH550 and tridecafluorooctyltriethoxysilane to the mixed solution of deionized water and alcohol, and heat to 50 degrees Celsius and keep it for 1 hour to ensure the hydrolysis of the coupling agent to form a hydrolysis solution; Place the silica powder in ethanol and disperse it with a high-speed disperser for 1 hour to form a silica powder suspension; Add the hydrolysis solution to the evenly stirred silica powder suspension and continue to stir for 0.5 hour; Then the suspension is dried in an air flow oven at 120 degrees Celsius and passed through a 150-mesh sieve to prepare the self-made modified silica powder.

[0057] Preparation of the topcoat: First, add polyether triol into a dry three-necked flask, vacuum dehydrate at 120 °C for 0.5 - 1 h, cool down to about 60 °C, add diphenylmethane diisocyanate and plasticizer, stir evenly, then add dibutyltin dilaurate, slowly heat up to 80 °C, keep the temperature for reaction for 2 h under the protection of dry nitrogen, cool down and discharge to obtain a prepolymer; Subsequently, place it in a high-speed dispersion kettle, control the temperature at 40 - 50 °C, slowly add modified silica powder, disperse at high speed for 30 min, then add latent curing agent and defoamer, stir at low speed for 5 min; Finally, add leveling agent and stir at low speed for 3 min; After fully dispersing evenly, the primer for spraying can be prepared.

[0058] Example 2

[0059] A fast-drying moisture-curing composite layer coating includes a primer and a topcoat;

[0060] The primer includes component A and component B;

[0061] Component A includes: 48 parts of epoxy resin, 5 parts of polysulfide rubber, 6 parts of zinc phosphate, 3 parts of sodium dodecyl sulfate, 3 parts of surfactant, 9 parts of self-made fluorine-modified hydrotalcite, 6 parts of xylene;

[0062] Component B includes: 48 parts of modified curing agent, 23 parts of ethanol, 1.5 parts of DMP-30 accelerator;

[0063] The surfactant is BYK-348;

[0064] 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 defoamer, 0.5 parts of leveling agent;

[0065] The plasticizer is dinonyl phthalate;

[0066] Among them, the preparation method of the self-made 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 the same as those in Example 1.

[0067] Example 3

[0068] A fast-drying moisture-curing composite layer coating includes a primer and a topcoat;

[0069] The primer includes component A and component B;

[0070] The component A includes: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, 10 parts of self-made fluorine-modified hydrotalcite, and 8 parts of xylene;

[0071] The component B includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator;

[0072] The surfactant is BYK-307;

[0073] The topcoat; its components include: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 part of dibutyltin dilaurate, 6 parts of plasticizer, 10 parts of modified silica powder, 6 parts of latent curing agent, 0.2 part of defoamer, and 0.6 part of leveling agent;

[0074] The plasticizer is any one of dioctyl phthalate;

[0075] Among them, the preparation methods of the self-made fluorine-modified hydrotalcite, the primer, the modified silica powder, and the topcoat in Example 3 are all the same as those in Example 1.

[0076] Example 4

[0077] A fast-drying moisture-curing composite layer coating includes a primer and a topcoat;

[0078] The primer includes component A and component B;

[0079] The component A includes: 56 parts of epoxy resin, 9 parts of polysulfide rubber, 9 parts of zinc phosphate, 5 parts of sodium dodecyl sulfate, 4 parts of surfactant, 11 parts of self-made fluorine-modified hydrotalcite, and 9 parts of xylene;

[0080] The component B includes: 53 parts of modified curing agent, 28 parts of ethanol, and 2.5 parts of DMP-30 accelerator;

[0081] The surfactant is BYK-307;

[0082] The topcoat; its components include: 78 parts of polyether polyol, 14 parts of 4,4-diphenylmethane diisocyanate, 0.25 part of dibutyltin dilaurate, 7 parts of plasticizer, 11 parts of modified silica powder, 7 parts of latent curing agent, 0.25 part of defoamer, and 0.7 part of leveling agent;

[0083] The plasticizer is dinonyl phthalate;

[0084] Among them, the preparation methods of the self-made fluorine-modified hydrotalcite, the primer, the modified silica powder, and the topcoat in Example 4 are all the same as those in Example 1.

[0085] Example 5

[0086] A quick-drying moisture-curing composite layer coating includes a primer and a topcoat;

[0087] The primer includes component A and component B;

[0088] Component A includes: 60 parts of epoxy resin, 10 parts of polysulfide rubber, 10 parts of zinc phosphate, 6 parts of sodium dodecyl sulfate, 4 parts of surfactant, 12 parts of self-made fluorine-modified hydrotalcite, and 10 parts of xylene;

[0089] Component B includes: 55 parts of modified curing agent, 30 parts of ethanol, and 3 parts of DMP-30 accelerator;

[0090] The surfactant is BYK-307;

[0091] 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 defoamer, and 0.8 parts of leveling agent;

[0092] The plasticizer is dioctyl phthalate;

[0093] Among them, the preparation method of the self-made 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 the same as those in Example 1.

[0094] Comparative Example 1

[0095] A primer, the primer includes component A and component B;

[0096] Component A includes: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, and 8 parts of xylene;

[0097] Component B includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator;

[0098] Among them, the preparation method of the primer in Comparative Example 1 is the same as that in Example 3.

[0099] Comparative Example 2

[0100] A primer, the primer includes component A and component B;

[0101] Component A includes: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, 10 parts of hydrotalcite, and 8 parts of xylene;

[0102] The component B includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator;

[0103] Among them, the preparation method of the primer in Comparative Example 2 is the same as that in Example 3.

[0104] Comparative Example 3

[0105] A fast-drying moisture-curing composite layer coating includes a primer and a topcoat;

[0106] The primer includes component A and component B;

[0107] Component A includes: 52 parts of epoxy resin, 8 parts of polythiol rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, 10 parts of self-made fluorine-modified hydrotalcite, and 8 parts of xylene;

[0108] The component B includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator;

[0109] 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 defoamer, and 0.6 parts of leveling agent;

[0110] Among them, the preparation method of the self-made fluorine-modified hydrotalcite, the preparation method of the primer, and the preparation method of the topcoat in Example 3 are all the same as those in Example 3.

[0111] Comparative Example 4

[0112] A fast-drying moisture-curing composite layer coating includes a primer and a topcoat;

[0113] The primer includes component A and component B;

[0114] Component A includes: 52 parts of epoxy resin, 8 parts of polythiol rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, 10 parts of self-made fluorine-modified hydrotalcite, and 8 parts of xylene;

[0115] The component B includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator;

[0116] 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 defoamer, and 0.6 parts of leveling agent;

[0117] Among them, the preparation method of the self-made fluorine-modified hydrotalcite, the preparation method of the primer, and the preparation method of the topcoat in Example 3 are all the same as those in Example 3.

[0118] Comparative Example 5

[0119] A fast-drying moisture-curing composite layer coating comprises a primer and a topcoat;

[0120] The primer comprises Component A and Component B;

[0121] Component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, 10 parts of hydrotalcite, 8 parts of xylene;

[0122] Component B comprises: 50 parts of modified curing agent, 25 parts of ethanol, 2 parts of DMP-30 accelerator;

[0123] The topcoat; its components comprise: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 part of dibutyltin dilaurate, 6 parts of plasticizer, 10 parts of silica powder, 6 parts of latent curing agent, 0.2 part of defoamer, 0.6 part of leveling agent;

[0124] Among them, the preparation methods of the primer and the topcoat in Example 3 are both the same as those in Example 3.

[0125] Comparative Example 6

[0126] A fast-drying moisture-curing composite layer coating comprises a primer and a topcoat;

[0127] The primer comprises Component A and Component B;

[0128] Component A comprises: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, 8 parts of xylene;

[0129] Component B comprises: 50 parts of modified curing agent, 25 parts of ethanol, 2 parts of DMP-30 accelerator;

[0130] The topcoat; its components comprise: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 part of dibutyltin dilaurate, 6 parts of plasticizer, 6 parts of latent curing agent, 0.2 part of defoamer, 0.6 part of leveling agent;

[0131] Among them, the preparation methods of the primer and the topcoat in Example 3 are both the same as those in Example 3.

[0132] Comparative Example 7

[0133] A fast-drying moisture-curing composite layer coating comprises a primer and a topcoat;

[0134] The primer comprises Component A and Component B;

[0135] The component A includes: 52 parts of epoxy resin, 8 parts of polysulfide rubber, 8 parts of zinc phosphate, 4 parts of sodium dodecyl sulfate, 3 parts of surfactant, 10 parts of hydrotalcite, and 8 parts of xylene;

[0136] The component B includes: 50 parts of modified curing agent, 25 parts of ethanol, and 2 parts of DMP-30 accelerator;

[0137] The topcoat, its components include: 75 parts of polyether polyol, 12 parts of 4,4-diphenylmethane diisocyanate, 0.2 part of dibutyltin dilaurate, 6 parts of plasticizer, 10 parts of modified silica powder, 6 parts of latent curing agent, 0.2 part of defoamer, and 0.6 part of leveling agent;

[0138] Among them, the preparation methods of the primer, the modified silica powder, and the topcoat in Comparative Example 7 are all the same as those in Example 3.

[0139] Test example: The primers prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to the following performance tests, including:

[0140] Referring to the test method in the industry standard HG / / T 4564-2013 "Epoxy Coatings with Low Surface Treatment Tolerance", the compatibility with the old paint film was tested; if the surface of the paint film is flat, without phenomena such as lifting and wrinkling, and the cross-cut test with the old paint film ≤ Grade 1, it is "no abnormality";

[0141] Referring to GB / T 1728-2020 "Determination of Drying Time of Paint Films and Putty Films", the surface drying time and actual drying time of the primer film were measured, and the relative humidity during drying was greater than 60%;

[0142] Referring to GB / T 5210-2006 "Paints and Varnishes - Pull-off Adhesion Test", the adhesion test of the primer coating film was completed;

[0143] Referring to GB / T 10125-2021 "Artificial Atmosphere Corrosion Tests - Salt Spray Tests", the salt spray resistance performance test of the primer was carried out;

[0144] The test results are shown in Table 1:

[0145] Table 1

[0146]

[0147] Comprehensive performance analysis: In this application, self-made fluorine-modified hydrotalcite is introduced into the primer. The layered structure of hydrotalcite itself can fill the tiny defects on the substrate surface, so it has a strong covering ability for 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 hydrotalcite can provide more contact points, thus enhancing the adhesion between the primer and the steel structure surface; the hydrotalcite modified by fluoride ion intercalation has an increased layer spacing, which can relieve 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 modified hydrotalcite in the primer; and when the modified hydrotalcite is incorporated into the primer, it can act as a barrier to block the further erosion of moisture and corrosive substances, improve the salt spray resistance of the primer, and thus enhance the corrosion resistance of the primer.

[0148] Component B in the primer coating of this application contains a reaction promoter, ethanol, and a modified curing agent, which can achieve moisture curing at a relatively fast speed; the reaction promoter therein can catalyze the reaction between epoxy groups and amine groups; ethanol can absorb moisture in the environment and is easy to volatilize itself; so that the renovation and repair of railway bridge steel structures can be completed in a relatively short time; while in Comparative Example 2, because no hydrotalcite is incorporated, it has a faster surface drying and through drying speed.

[0149] Test examples: The composite layer coatings prepared in Examples 1-5 and Comparative Examples 3-7 were subjected to the following performance tests, including:

[0150] Referring to GB / T 19250-2013, "Polyurethane Waterproof Coating", the 30-day water absorption rate of the composite layer coating was tested;

[0151] The water contact angle was tested by using a contact angle measuring instrument;

[0152] Referring to GB-T 1865, "Paints and varnishes - Artificial weathering and exposure to artificial radiation - Filtered xenon-arc radiation", the artificial weathering resistance of the composite layer coating was tested;

[0153] Referring to GB / T 9274, "Paints and varnishes - Determination of resistance to liquid media", the acid resistance and alkali resistance of the prepared composite layer coating were tested.

[0154] The test results are shown in Table 2:

[0155] Table 2

[0156]

[0157] Comprehensive performance analysis: There are obvious performance differences in the performance indicators of Comparative Examples 3, 4, 5, and 6 compared with Examples 1-5. The possible reason is that the silica powder introduced in the topcoat of this application is co-modified by KH550 and 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane. Among them, 1,1,2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-heptadecafluorooctyltriethoxysilane can form hydrophobic C-F chains on the surface of the silica powder, 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 silica powder, which can enhance the combination of the silica powder and the polyether polyol, reduce the agglomeration of the silica powder filler, improve the dispersibility, and improve the weather resistance of the topcoat.

[0158] The difference between Comparative Example 7 and Example 3 is that only the primer does not use the self-made fluorine-modified hydrotalcite. Its water contact angle and resistance to artificial weathering are the most excellent among the comparative examples, but there is still a certain performance gap with Examples 1-5. The possible reason is that the primer in Examples 1-5 of this application uses a fluoride ion intercalation-modified primer. 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 in 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, making the composite coating have beneficial weather resistance and anti-corrosion performance.

[0159] The specific embodiments described above further elaborate on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A fast-drying moisture-curing composite layer coating, characterized in that, By weight parts, the quick-drying moisture-curing composite layer coating includes a primer and a topcoat; The primer includes component A and component B; Component A includes: 45 - 60 parts of epoxy resin, 5 - 10 parts of polysulfide rubber, 5 - 10 parts of zinc phosphate, 2 - 6 parts of sodium dodecyl sulfate, 2 - 4 parts of surfactant, 8 - 12 parts of self-made fluorine-modified hydrotalcite, and 5 - 10 parts of xylene; Component B includes: 45 - 55 parts of modified curing agent, 20 - 30 parts of ethanol, and 1 - 3 parts of DMP-30 accelerator; The topcoat, its components include: 70 - 80 parts of polyether polyol, 10 - 15 parts of 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 defoamer, and 0.3 - 0.8 parts of leveling agent; The self-made fluorine-modified hydrotalcite in the primer is prepared by the following method: Take magnesium nitrate hexahydrate and aluminum nitrate nonahydrate and dissolve them in deionized water. Under nitrogen protection, continue to drop deionized water into the solution while dropping NaOH solution to adjust the pH value of the solution to 10 - 11; Subsequently, place the prepared solution in a 70°C constant temperature water bath and stir for 10h, then raise the temperature to 100°C for crystallization for 8h; Filter and wash with water until the pH value is 7; Subsequently, place it in a vacuum dryer and dry for 5h to prepare the intermediate product; Place the intermediate product in a muffle furnace at 500°C and calcine for 4h, and cool to room temperature under nitrogen protection; Finally, add the intermediate product to the KF aqueous solution, stir at room temperature for 24h, and finally filter, wash with water, and vacuum dry to prepare the self-made fluorine-modified hydrotalcite.

2. The quick-drying moisture-curing composite layer coating according to claim 1, wherein The epoxy resin in component A of the primer is bisphenol A epoxy resin NPEL-128.

3. The fast-drying moisture-curing composite layer coating according to claim 1, characterized in that The surfactant in component A of the primer is any one of BYK-348 and BYK-307.

4. A fast-drying moisture-curing composite layer coating according to claim 1, characterized in that, The polyether polyol in the topcoat is polyether triol.

5. A quick-drying moisture-curing composite layer coating according to claim 1, characterized in that, The plasticizer in the topcoat is any one of dinonyl phthalate or didecyl phthalate.

6. The quick-drying moisture-curing composite layer coating according to any one of claims 1-5, characterized in that, The preparation method of the modified silica powder in the topcoat is: Add KH550 and tridecafluorooctyltriethoxysilane to the mixed solution of deionized water and alcohol, and heat to 50 degrees Celsius and keep for 1h to ensure the hydrolysis of the coupling agent to form a hydrolysis solution; Place the silica powder in ethanol and disperse it with a high-speed disperser for 1h to form a silica powder suspension; Add the hydrolysis solution to the uniformly stirred silica powder suspension and continue to stir for 0.5h; Subsequently, dry the suspension in a 120-degree Celsius air flow oven and pass it through a 150-mesh sieve to prepare the modified silica powder.

7. A method for preparing a quick-drying moisture-curing composite layer coating according to any one of claims 1-5, characterized in that, The preparation method of the primer is as follows: at room temperature, the components of Group A are weighed in sequence according to the formula and placed in a container. After adding each component, it is stirred evenly for 5 minutes. After adding the last raw material, it is stirred evenly again and left to stand for 4 - 8 hours. Then it is sealed with a lid and stored in a dry and cool place for standby; at room temperature, the three components in Group B are accurately weighed, placed in a stirring container, stirred evenly for 5 minutes, then sealed with a lid and stored in a dry and cool place for standby; during storage, components A and 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. After component B is added, continue to stir for 3 minutes; thus, the primer is prepared and can be used for spraying construction; During the preparation process 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, add polyether triol to a dry three-necked flask, vacuum dehydrate at 120 °C for 0.5 - 1 hour, cool down to 60 °C, add diphenylmethane diisocyanate and plasticizer, stir evenly, then add dibutyltin dilaurate, slowly heat up to 80 °C, and keep the temperature for 2 hours under the protection of dry nitrogen, then cool down and discharge to obtain a prepolymer; then place it in a high-speed dispersion kettle, control the temperature at 40 - 50 °C, slowly add modified silica powder, disperse at high speed for 30 minutes, then 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 being fully dispersed and homogenized, the topcoat that can be used for spraying is prepared.

8. Application of the quick-drying moisture-curing composite layer coating according to any one of claims 1 - 5 in the renovation and repair of railway bridge steel structures.

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