Waterproof protective coating for steel structure and preparation method and application thereof

Abstract

This invention relates to a waterproof protective coating for steel structures, its preparation method, and its application. The waterproof coating comprises component A and component B; component A includes a polymer emulsion; component B, by weight percentage, comprises: 71%-82% cement, 15%-18% propylene glycol, 5%-12% ethanol, 0.5%-1.2% sodium benzoate, and 1%-2.5% sodium dehydroacetate. This coating exhibits good long-term stability and can achieve the required performance indicators for primer, intermediate coat, and topcoat of water-based anti-corrosion coatings for steel structures with a single layer, simplifying the protection of steel structures. Furthermore, the coating possesses excellent density, passivates the surface of the steel structure, exhibits strong adhesion to the substrate, demonstrates good weather resistance, and provides excellent decorative properties, making it a long-lasting and cost-effective waterproof and anti-corrosion coating.

Description

Technical Field

[0001] This invention relates to a waterproof and protective coating for steel structures, its preparation method, and its application. Background Technology

[0002] Polymer-modified cement coatings exhibit excellent adhesion to metals such as aluminum and iron, or metal alloys. Furthermore, the coatings are moderately alkaline, effectively preventing the electrochemical corrosion reaction of metal components caused by hydrogen evolution in air, thus providing corrosion protection. The calcium hydroxide continuously released from the reaction of cement with water can combine with metals such as aluminum and iron to form dense calcium aluminate, calcium ferrite, and other metal salts. These metal salts provide a strong protective layer to the surface of metal components, preventing oxygen corrosion from the air.

[0003] Polymer-modified cement coatings optimize their material composition to form a dense protective structure. Furthermore, after their own damage, they can catalyze the release of other protective materials in an aqueous medium, forming a multi-layered metal structure for protection and corrosion prevention. They exhibit excellent physical and chemical properties in protecting metal structures.

[0004] However, existing polymer-modified cementitious coatings are primarily used for waterproofing concrete structures and cannot be directly applied to the protection of metal structures such as steel structures. This is because the cement component in the coating undergoes a hydration reaction upon contact with water. Therefore, the cement must be provided in powder form during application, and other components, such as liquid components like polymer emulsions, must be mixed with the cement powder on-site. After mixing, the cement begins its hydration reaction. However, air trapped in the powder cannot escape during the hydration reaction and thus solidifies within the coating structure, creating pores in the coating film and resulting in an insufficiently dense film. Consequently, when the coating is used outdoors, these pores retain external water, and repeated freeze-thaw cycles or environmental changes can damage the protected material, rendering it unsuitable for metal structures such as steel structures.

[0005] Anti-corrosion coatings for building steel structures typically employ a three-layer application design: primer, intermediate coat, and topcoat, to meet different functional requirements such as electrochemical corrosion protection and weather resistance. However, this necessitates multiple applications of coatings with varying properties, resulting in a complex protective process and significantly increased costs. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a waterproof protective coating for steel structures that addresses the shortcomings and deficiencies of the prior art. This coating has good long-term stability and can meet the requirements of water-based anti-corrosion coatings for steel structures as primers, intermediate coats and top coats with a single layer of coating material, thus simplifying the protection of steel structures.

[0007] To solve the above technical problems, the technical solution adopted by the present invention is as follows:

[0008] A waterproof coating comprising component A and component B; component A comprising a polymer emulsion; and component B comprising, by weight percentage: 71%-82% cement, 15%-18% propylene glycol, 5%-12% ethanol, 0.5%-1.2% sodium benzoate and 1%-2.5% sodium dehydroacetate.

[0009] In some embodiments, the polymer emulsion is selected from one or more combinations of acrylate emulsions, styrene-acrylic emulsions, and silicone-acrylic emulsions. Under the alkaline action of cement in component B, the acrylate groups on the side chains of components such as acrylate emulsions, styrene-acrylic emulsions, and silicone-acrylic emulsions in component A undergo hydrolysis, generating carboxyl groups on the polymer side chains. These carboxyl groups can react with cement.

[0010] In some embodiments, the polymer emulsion is an acrylate emulsion.

[0011] In some embodiments, the polymer emulsion is a Dow EC1791 emulsion.

[0012] In some embodiments, component A further includes an additive selected from one or more combinations of defoamers, preservatives, color pastes, and wetting agents. The defoamer may be an organosilicon defoamer, etc., and the color paste may be an iron-red color paste, etc.

[0013] In some embodiments, component A comprises 95%-99% polymer emulsion and 1%-5% additives, by weight percentage.

[0014] In some embodiments, component A comprises, by weight percentage, 95%-99% polymer emulsion, 0.2%-1.0% defoamer, 0.02%-2.5% preservative, and 0.5%-2.0% colorant.

[0015] In some embodiments, the mass ratio of component A to component B is 1:1-1.4.

[0016] In some embodiments, the cement is selected from one or a combination of two of white cement and gray cement.

[0017] In some embodiments, the cement is white cement.

[0018] The white cement in this invention refers to white silicate cement, which is a hydraulic cementitious material made by grinding white silicate cement clinker with low iron oxide content, an appropriate amount of gypsum, and mixed materials (limestone and kiln ash).

[0019] In some embodiments, the cement is 52.5 white cement.

[0020] In some embodiments, the ethanol is industrial ethanol. Industrial ethanol contains a certain amount of water, but is less expensive. Using the formulation of this invention, industrial ethanol can be used, and the water content will not cause rapid solidification of component B.

[0021] In existing polymer-modified cement coatings, air trapped in the powder component cannot escape during the hydration reaction and is solidified within the coating structure, resulting in pores in the coating film and insufficient film density. The inventors of this application have discovered that when the powder component (i.e., component B of this application) uses a mixed solvent of propylene glycol and ethanol as a carrier, it can disperse and degas the cement in the powder component. Powder component B can then form a pre-dispersed liquid without air entrainment. When this pre-dispersed liquid is mixed with liquid component A, no air will be present in the polymer-modified cement coating, thus resulting in a denser coating film. This application, by simultaneously adding propylene glycol and ethanol to component B, solves the problem that when cement powder is directly mixed with polymer emulsion, the air trapped in the cement powder cannot be expelled in time and is embedded in the resulting coating during cement curing, reducing the film density.

[0022] The cement component in component B, as a filler in the coating, enables the waterproof and anti-corrosion coating of this application to provide a long-term alkaline environment for the steel structure surface, thereby protecting the steel structure.

[0023] Polymer emulsions possess high elasticity. Adding polymer emulsions to component A imparts high elasticity to the coating, enabling it to meet the temperature deformation requirements of the underlying components and providing long-term protection against deformation fatigue. Simultaneously, the acrylic side-chain structure in the polymer emulsion can passivate iron ions in the metal or steel structure, forming a self-protective layer, i.e., a passivation layer. This passivation layer acts as a transition between the metal or steel structure and the coating, enhancing the adhesion between the coating and the metal or steel structure.

[0024] Industrial ethanol is relatively inexpensive, so it is commonly used as the ethanol component in component B. However, industrial ethanol contains a certain amount of water, which can react with the cement in component B through a hydration reaction, potentially causing component B to solidify within a short period. This prevents component B from mixing with component A, resulting in an unusable coating. The inventors of this application have discovered that by controlling the mass percentage of ethanol in component B and simultaneously adding sodium benzoate and sodium dehydroacetate, component B can be prevented from solidifying, allowing it to form a coating with component A and ensuring the long-term stability of the coating. Sodium benzoate and sodium dehydroacetate in component B are typically preservatives, and existing technologies have not recognized their ability to prevent the solidification of the cement component in polymer-modified coatings.

[0025] If the content of propylene glycol in component B is too low, it will cause the cement hydration reaction of component B to be too fast, which will lead to higher porosity, higher water absorption, and lower strength of the coating film.

[0026] The present invention further provides a method for preparing the above-mentioned waterproof coating, the method comprising the following steps:

[0027] 1) Stir component A to obtain liquid component A;

[0028] 2) Mix and stir the propylene glycol, ethanol, sodium benzoate and sodium dehydroacetate in component B, add the cement in component B and stir to disperse, to obtain liquid component B;

[0029] 3) Mix the liquid component A and liquid component B to obtain the waterproof coating.

[0030] In some implementations, the stirring in step 1) is carried out in a vacuum stirring apparatus.

[0031] In some implementations, the mixing and stirring in step 2) are carried out in a vacuum stirring apparatus.

[0032] In some embodiments, the stirring and dispersion in step 2) is carried out in a vacuum stirring apparatus.

[0033] In some implementations, the stirring time in step 1) is 5-60 minutes.

[0034] In some implementations, the mixing and stirring time in step 2) is 5-60 minutes.

[0035] In some implementations, the stirring and dispersion time in step 2) is 5-60 minutes.

[0036] The present invention further provides the use of the above-mentioned waterproof coating for the protection of metal structures.

[0037] The present invention further provides the use of the above-mentioned waterproof coating for the protection of steel structures.

[0038] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0039] 1) The addition of propylene glycol and ethanol to component B of the present invention can solve the problem that when cement powder is directly mixed with polymer emulsion, the air trapped in the cement powder cannot be discharged in time and is buried in the coating during the cement curing period, thus reducing the density of the coating film.

[0040] 2) By controlling the content of ethanol and propylene glycol in component B, and by adding sodium benzoate and sodium dehydroacetate, this invention can ensure that component B meets the requirements of long-term storage without stratification or cement hydration and setting.

[0041] 3) The waterproof coating of this invention simultaneously meets the index requirements of primer, intermediate coat, and topcoat in HG / T 5176-2017 water-based anti-corrosion coatings for steel structures. Using the waterproof coating of this invention, a single layer of material can meet the anti-corrosion performance requirements. It can simplify the tedious process of construction design requiring three layers of primer, intermediate coat, and topcoat in the prior art.

[0042] 4) The waterproof coating of this invention meets the performance indicators of anti-corrosion coatings in HG / T 5176-2017 (Waterborne Anti-corrosion Coatings for Steel Structures) and HG / T 20720-2020 (Construction and Acceptance Specifications for Waterborne Anti-corrosion Coatings for Steel Structures in Industrial Buildings). It can be applied in one coat, simultaneously meeting the requirements for primer passivation, intermediate layer oxidation resistance, and topcoat weather resistance.

[0043] 5) The waterproof coating of the present invention has the characteristics of good density, passivation of steel structure surface, strong adhesion to substrate, good weather resistance, and excellent decoration. It is a waterproof and anti-corrosion coating with long service life and high cost performance. Detailed Implementation

[0044] The technical solutions of the present invention will be described in detail below with reference to specific embodiments, so that those skilled in the art can better understand and implement the technical solutions of the present invention, but the present invention is not limited to the scope of the examples described.

[0045] Example 1

[0046] This embodiment provides a waterproof coating, the raw material composition of which is as follows:

[0047] Liquid component A: Dow EC1791 emulsion 98.98 wt%, silicone defoamer 0.2 wt%, preservative 0.02 wt%, iron oxide red paste 0.8 wt%;

[0048] Liquid component B: 73wt% white cement (52.5 grade), 15wt% propylene glycol, 10wt% ethanol (industrial ethanol), 1.0wt% sodium benzoate, and 1.0wt% sodium dehydroacetate;

[0049] The preparation method is as follows:

[0050] Liquid component A: All raw materials are sequentially added to a vacuum mixing device, and the vacuum pump is turned on and stirred for 15 minutes to obtain liquid component A;

[0051] Liquid component B: Propylene glycol, ethanol, sodium benzoate, and sodium dehydroacetate are added sequentially to a vacuum mixer and stirred for 20 minutes. Then, 52.5 white cement is added and stirred. The vacuum pump is then turned on and stirred for 25 minutes to disperse the mixture. This is liquid component B.

[0052] Performance testing: Liquid component A and liquid component B were mixed evenly at a mass ratio of 1:1 and tested according to standard HG / T5176-2017, meeting all indicators for the bottom, middle, and top grades; the dry film elasticity met the Type II indicator in GBT23445, and the density was 2.6 g / cm³. 3 The water absorption rate is less than 4%, and the porosity is less than 5%. Application requirements: Apply two coats to the protected substrate, achieving a final film thickness of 1.0 mm, with no cracking. Specific performance characteristics are shown in Table 1 below.

[0053] Example 2

[0054] This embodiment also provides a waterproof coating, whose preparation process is the same as that of Example 1, the only difference being that its raw material composition is different from that of Example 1, and the composition is as follows:

[0055] Liquid component A: 98 wt% Dow EC1791 emulsion, 1.0 wt% silicone defoamer, 0.05 wt% preservative, and 0.95 wt% colorant;

[0056] Liquid component B: 75wt% white cement (52.5 grade), 15wt% propylene glycol, 8wt% ethanol (industrial ethanol), 0.5wt% sodium benzoate, and 1.5wt% sodium dehydroacetate.

[0057] Performance testing: Liquid component A and liquid component B were mixed evenly at a mass ratio of 1:1.4 and tested according to standard HG / T5176-2017, meeting all indicators for the bottom, middle, and top grades; the dry film elasticity met the Type II indicator in GBT23445, and the density was greater than 2.8 g / cm³. 3 Application requirements: Apply two coats to the protected substrate, achieving a final film thickness of 1.0 mm, with no cracking. Specific performance characteristics are shown in Table 1 below.

[0058] Example 3

[0059] This embodiment also provides a waterproof coating, whose preparation process is the same as that of Example 1, the only difference being that its raw material composition is different from that of Example 1, and the composition is as follows:

[0060] Liquid component A: 98 wt% Dow EC1791 emulsion, 1.0 wt% silicone defoamer, 0.05 wt% preservative, and 0.95 wt% colorant;

[0061] Liquid component B: 71wt% white cement (52.5 grade), 18wt% propylene glycol, 9wt% ethanol (industrial ethanol), 0.5wt% sodium benzoate, and 1.5wt% sodium dehydroacetate.

[0062] The performance test was the same as in Example 1, and the specific performance is shown in Table 1 below.

[0063] Example 4

[0064] This embodiment also provides a waterproof coating, whose preparation process is the same as that of Example 1, the only difference being that its raw material composition is different from that of Example 1, and the composition is as follows:

[0065] Liquid component A: 98 wt% Dow EC1791 emulsion, 1.0 wt% silicone defoamer, 0.05 wt% preservative, and 0.95 wt% colorant;

[0066] Liquid component B: 73.5 wt% white cement (52.5 grade), 18 wt% propylene glycol, 5 wt% ethanol (industrial ethanol), 1.0 wt% sodium benzoate, and 2.5 wt% sodium dehydroacetate.

[0067] The performance test was the same as in Example 1, and the specific performance is shown in Table 1 below.

[0068] Comparative Example 1

[0069] This comparative example provides a waterproof coating, whose preparation process is the same as in Example 1, except that component B in its raw material composition differs from that in Example 1. Specifically, component B consists of 73 wt% 52.5 white cement, 5 wt% propylene glycol, 20 wt% ethanol (industrial ethanol), 1.0 wt% sodium benzoate, and 1.0 wt% sodium dehydroacetate. The result is that component B solidifies within 24 hours after preparation, rendering the coating unusable. This is because industrial ethanol contains a certain amount of water; when the amount of industrial ethanol is excessive, component B contains too much water, causing premature hydration with the white cement.

[0070] Comparative Example 2

[0071] This comparative example provides a waterproof coating, whose preparation process is the same as in Example 1, except that component B in its raw material composition is different from that in Example 1, and sodium benzoate and sodium dehydroacetate are not added. Specifically, component B consists of 75 wt% 52.5 white cement, 15 wt% propylene glycol, and 10 wt% ethanol (industrial ethanol). The result is that the water in the ethanol of component B participates in the cement hydration reaction, and component B solidifies within 24 hours after preparation, rendering the coating unusable.

[0072] Comparative Example 3

[0073] This comparative example provides a waterproof coating, whose preparation process is the same as in Example 1, except that component B in its raw material composition is different from that in Example 1, and ethanol is not added. Specifically, component B consists of 83 wt% 52.5 white cement, 15 wt% propylene glycol, 1.0 wt% sodium benzoate, and 1.0 wt% sodium dehydroacetate. The result is that after components A and B are mixed, the solvent evaporates too slowly, and the coating cannot dry completely within 24 hours; the drying time is longer than 24 hours.

[0074] Comparative Example 4

[0075] This comparative example provides a waterproof coating, whose preparation process is the same as in Example 1, except that component B in its raw material composition is different from that in Example 1, with a reduced amount of propylene glycol. Specifically, component B consists of 78 wt% 52.5 white cement, 10 wt% propylene glycol, 10 wt% ethanol (industrial ethanol), 1.0 wt% sodium benzoate, and 1.0 wt% sodium dehydroacetate. The result is that the cement hydration reaction is too rapid, leading to increased porosity, higher water absorption, and reduced strength in the coating film. Specific properties are shown in Table 1 below.

[0076] Table 1. Performance of waterproof coatings in each example and comparative example.

[0077]

[0078]

[0079] As shown in Table 1, when component B contains both propylene glycol and ethanol, the coating's density is improved. By controlling the propylene glycol content, the coating's performance can be improved. By controlling the ethanol content and adding sodium benzoate and sodium dehydroacetate to component B, it can be ensured that component B will not solidify, can form a coating with component A, and guarantee the coating's long-term stability.

[0080] The above embodiments are merely illustrative of the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

[0081] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

Claims

1. A waterproof coating, characterized in that: The waterproof coating comprises component A and component B; component A comprises a polymer emulsion; and component B comprises, by weight percentage, 71%-82% cement, 15%-18% propylene glycol, 5%-12% ethanol, 0.5%-1.2% sodium benzoate and 1%-2.5% sodium dehydroacetate.

2. The waterproof coating according to claim 1, characterized in that: The polymer emulsion is selected from one or more combinations of acrylate emulsions, styrene-acrylic emulsions, and silicone-acrylic emulsions.

3. The waterproof coating according to claim 1, characterized in that: The polymer emulsion is an acrylate emulsion.

4. The waterproof coating according to claim 1, characterized in that: The polymer emulsion is Dow EC1791 emulsion.

5. The waterproof coating according to claim 1, characterized in that: Component A further includes an auxiliary agent selected from one or more combinations of defoamers, preservatives, color pastes, and wetting agents.

6. The waterproof coating according to claim 5, characterized in that: Component A comprises 95%-99% polymer emulsion and 1%-5% additives, based on a weight percentage of component A.

7. The waterproof coating according to claim 5, characterized in that: Based on the weight percentage of component A, component A comprises 95%-99% polymer emulsion, 0.2%-1.0% defoamer, 0.02%-2.5% preservative, and 0.5%-2.0% color paste.

8. The waterproof coating according to claim 1, characterized in that: The mass ratio of component A to component B is 1:1-1.4; and / or, the ethanol is industrial ethanol.

9. The waterproof coating according to claim 1, characterized in that: The cement is selected from one or a combination of two of white cement and gray cement.

10. The waterproof coating according to claim 1, characterized in that: The cement is white cement.

11. The waterproof coating according to claim 1, characterized in that: The cement is 52.5 white cement.

12. The method for preparing the waterproof coating according to any one of claims 1-11, characterized in that: The preparation method includes the following steps: 1) Stir component A to obtain liquid component A; 2) Mix and stir the propylene glycol, ethanol, sodium benzoate and sodium dehydroacetate in component B, add the cement in component B and stir to disperse, to obtain liquid component B; 3) Mix the liquid component A and liquid component B to obtain the waterproof coating.

13. The preparation method according to claim 12, characterized in that: The stirring in step 1) is carried out in a vacuum stirring apparatus; and / or the mixing and stirring in step 2) is carried out in a vacuum stirring apparatus; and / or the stirring and dispersing in step 2) is carried out in a vacuum stirring apparatus; and / or the stirring time in step 1) is 5-60 min; and / or the mixing and stirring time in step 2) is 5-60 min; and / or the stirring and dispersing time in step 2) is 5-60 min.

14. Use of the waterproof coating according to any one of claims 1-11 for the protection of metal structures.

15. The use of the waterproof coating according to any one of claims 1-11 for the protection of steel structures.

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