A coating agent for pervious concrete and a method for preparing the same

Abstract

This application relates to the field of overlay materials, and more specifically to an overlay agent for permeable concrete and its preparation method. The overlay agent for permeable concrete, by weight, comprises at least the following raw materials: 60-80 parts silicone-acrylic emulsion, 4-8 parts composite film-forming agent, 0.6-1.2 parts wetting agent, 4-10 parts functional agent, 0.4-0.8 parts defoamer, 1-3 parts inorganic thickener, 5-12 parts color paste, and 10-20 parts deionized water. The overlay agent prepared in this application not only possesses advantages such as high hardness, strong adhesion, and good hydrolysis resistance, but also maintains good weather resistance, a long open time, and salt and alkali resistance, fully meeting the comprehensive performance requirements of permeable concrete in complex environments.

Description

Technical Field

[0001] This application relates to the field of overlay materials, and more specifically to an overlay agent for permeable concrete and its preparation method. Background Technology

[0002] Permeable concrete, as an eco-friendly building material, is widely used in sponge city construction, municipal roads, plazas, and parking lots due to its excellent permeability and environmental protection properties. However, the porous structure of permeable concrete, while giving it its permeability, also brings problems such as low surface strength, easy wear, poor weather resistance, susceptibility to salt and alkali corrosion, and clogging by dirt. To solve these problems, a surface coating agent is usually applied to protect and reinforce its surface, thereby extending its service life and maintaining its permeability.

[0003] Currently, common permeable concrete overcoats on the market are mainly based on material systems such as acrylic resin, epoxy resin, polyurethane, or silicone. Acrylic resin overcoats are low in cost and easy to apply, but their hardness and abrasion resistance are often insufficient. Prolonged exposure to ultraviolet radiation and humid environments can easily lead to hydrolysis and yellowing, causing the coating to chalk and peel off. Epoxy resin overcoats, while possessing high adhesive strength and hardness, have poor weather resistance and are prone to embrittlement, loss of gloss, and even cracking under outdoor ultraviolet radiation and temperature changes. Furthermore, their two-component system has a short application window and insufficient open time, making them unsuitable for large-area application. Polyurethane materials offer good flexibility and abrasion resistance, but still suffer from insufficient hydrolytic stability, especially prone to degradation in high-temperature and high-humidity environments, affecting long-term protective effects. Silicone materials exhibit excellent weather resistance and hydrophobicity; however, their adhesion strength to the concrete substrate is relatively low, and their hardness often fails to meet high scratch resistance requirements.

[0004] Furthermore, existing topcoat agents generally perform poorly in resisting salt and alkali corrosion, especially in cold northern regions where snow-melting salt erosion occurs or in coastal areas with salt spray conditions, where the coating is prone to blistering, peeling, and performance degradation. Additionally, many products have short open times, making it difficult for construction workers to adjust their application schedule. Delayed application can lead to uneven film formation and noticeable seams, affecting the overall aesthetics and protective effect.

[0005] Existing permeable concrete overlay agent technologies still suffer from problems such as poor balance between hardness and toughness, insufficient adhesion strength to porous concrete substrates, inadequate resistance to hydrolysis and UV aging, weak resistance to salt and alkali corrosion, and short open time during construction. These issues make it difficult to fully meet the requirements for the use and construction adaptability of permeable concrete in complex environments. Therefore, how to prepare a permeable concrete overlay agent with excellent comprehensive performance has become one of the important issues faced by those skilled in the art. Through in-depth research in this technical field, the applicant has finally proposed an overlay agent for permeable concrete and its preparation method in this application. The overlay agent prepared in this application not only has advantages such as high hardness, strong adhesion, and good hydrolysis resistance, but also maintains good weather resistance, a long open time, and salt and alkali resistance, fully meeting the comprehensive performance requirements of permeable concrete in complex environments. Summary of the Invention

[0006] To achieve the above objectives, this application provides the following technical solution: The first aspect of this application provides a surface treatment agent for permeable concrete, which, by weight, comprises the following raw materials: 60-80 parts of silicone-acrylic emulsion, 4-8 parts of composite film-forming agent, 0.6-1.2 parts of wetting agent, 4-10 parts of functional agent, 0.4-0.8 parts of defoamer, 1-3 parts of inorganic thickener, 5-12 parts of color paste, and 10-20 parts of deionized water.

[0007] Preferably, the mass ratio of the composite film-forming agent to the functional agent in the silicone-acrylic emulsion is (6.5~7.5):(0.5~0.7):(0.6~1).

[0008] More preferably, the mass ratio of the composite film-forming agent to the functional agent in the silicone-acrylic emulsion is (7~7.3):(0.6~0.65):(0.8~0.9).

[0009] Preferably, the composite film-forming agent is a combination of dodecyl alcohol ester and ethylene glycol butyl ether.

[0010] Preferably, the mass ratio of the dodecyl alcohol ester to ethylene glycol butyl ether is (2.5~3.2):(1~1.3).

[0011] More preferably, the mass ratio of the dodecyl alcohol ester to ethylene glycol butyl ether is (2.8~3):(1~1.1).

[0012] Preferably, the wetting agent is at least one selected from ammonium polyacrylate, sodium polycarboxylate, and sodium polyacrylate.

[0013] More preferably, the wetting agent is ammonium polyacrylate.

[0014] Preferably, the functional agent is a combination of polycarbodiimide and epoxy-terminated polydimethylsiloxane.

[0015] Preferably, the mass ratio of the polycarbodiimide to the epoxy-terminated polydimethylsiloxane is (1.5~2.5):(1~1.2).

[0016] More preferably, the mass ratio of the polycarbodiimide to the epoxy-terminated polydimethylsiloxane is (2~2.2):(1~1.1).

[0017] Most preferably, the mass ratio of the polycarbodiimide to the epoxy-terminated polydimethylsiloxane is 2:1.

[0018] This application significantly enhances the overall performance of permeable concrete overcoat agents by incorporating functional agents. The active ingredients in this composition interact with the main polymer of the overcoat agent and the surface of the concrete substrate during the curing process. Intermolecular cross-linking forms a denser network structure within the coating, enhancing its rigidity and wear resistance. Furthermore, the specific functional groups it contains form a strong chemical bond with the substrate surface, greatly improving adhesion. In addition, this composition forms a stable protective layer on the coating surface, effectively blocking moisture, ultraviolet radiation, and corrosive salts and alkalis, thereby delaying coating aging and extending its service life. This multi-layered protective mechanism results in an overcoat with both excellent physical properties and long-lasting durability.

[0019] Preferably, the defoamer is at least one of silicone defoamers.

[0020] Preferably, the inorganic thickener is at least one selected from bentonite, magnesium aluminum silicate, montmorillonite, fumed silica, and sodium silicate.

[0021] More preferably, the inorganic thickener is bentonite or magnesium aluminum silicate.

[0022] Most preferably, the inorganic thickener is bentonite.

[0023] Preferably, the color paste is any one of iron oxide red paste, titanium nickel yellow paste, and high pigment carbon black paste.

[0024] Preferably, the surface treatment agent for permeable concrete, by weight, further comprises: 5-15 parts polymer additive, 0.3-0.6 parts ultraviolet absorber, 0.5-1.5 parts water repellent, and 0.1-0.3 parts bactericide.

[0025] Preferably, the mass ratio of the silicone-acrylic emulsion to the polymer additive is (6.5~7.5):(0.8~1.2).

[0026] More preferably, the mass ratio of the silicone-acrylic emulsion to the polymer additive is (7~7.3):(0.9~1).

[0027] Preferably, the polymer additive is a combination of an aqueous polyurethane dispersion and a pure acrylic emulsion.

[0028] Preferably, the mass ratio of the aqueous polyurethane dispersion to the pure acrylic emulsion is (0.5~0.8):1.

[0029] More preferably, the mass ratio of the aqueous polyurethane dispersion to the pure acrylic emulsion is 0.6:1.

[0030] Preferably, the aqueous polyurethane dispersion is Bayhydrol® UH 2888, manufactured by Covestro, Germany.

[0031] Preferably, the pure acrylic emulsion is Acronal® LR 8960, manufactured by BASF, Germany.

[0032] Furthermore, the addition of polymer additives effectively enhances the overall durability of the coating, particularly in terms of weather resistance, hydrolysis resistance, and salt and alkali resistance. The complementary properties of the two polymers achieve a good balance between rigidity and flexibility, thus preventing coating cracking or powdering. During film formation, the two raw materials form a synergistic protective composite structure, ensuring the coating possesses necessary surface hardness while providing a degree of flexibility and elasticity to help it adapt to minor deformations of the substrate and alleviate external stress. More importantly, the two polymers interact to build a dense protective barrier within the coating, effectively blocking the intrusion of moisture, ultraviolet radiation, and corrosive salts and alkalis, thereby slowing down the material aging process.

[0033] Preferably, the ultraviolet absorber is a benzotriazole or triazine.

[0034] Preferably, the hydrophobic agent is at least one of organosilane, silicone resin emulsion, and aminosilane.

[0035] More preferably, the hydrophobic agent is an organosilane.

[0036] Preferably, the bactericide is an isothiazolinone or a Kathon.

[0037] More preferably, the bactericide is isothiazolinone.

[0038] A method for preparing a surface coating agent for permeable concrete includes the following steps: S1: After adding deionized water to the reaction tank, the rotation speed is adjusted to 250~300 r / min. A bactericide, a water-repellent agent, and a polymer additive are added to the dropper and slowly dripped into the reaction tank. Then, a silicone-acrylic emulsion, a composite film-forming agent, and a functional agent are dripped into the reaction tank, and the rotation speed is adjusted to 400~500 r / min until the emulsion is evenly dispersed. S2: The remaining raw materials, except for the color paste, are slowly dripped into the reaction tank sequentially, dispersing for 15~20 minutes after each addition until no oil shrinkage occurs. S3: Finally, the rotation speed is adjusted to 700~800 r / min, and after dispersing for 10~15 minutes until the viscosity stabilizes, the color paste is slowly added and dispersed for 8~10 minutes until the color is fully mixed and uniform, thus obtaining the final product.

[0039] The beneficial effects of this application are: 1. The surface coating agent prepared in this application not only has the advantages of high hardness, strong adhesion and good hydrolysis resistance, but also has good weather resistance, long open time and salt and alkali resistance, which fully meets the comprehensive performance requirements of permeable concrete in complex environments.

[0040] 2. This application significantly improves the overall performance of permeable concrete overcoat agents by adding functional agents. These agents primarily form a stable protective layer on the coating surface, effectively blocking the erosion of moisture, ultraviolet rays, and corrosive salts and alkalis, thereby delaying coating aging and extending its service life. This multi-layered protective mechanism results in an overcoat layer that possesses both excellent physical properties and long-lasting durability.

[0041] 3. The addition of polymer additives in this application effectively improves the overall durability of the coating, particularly in terms of weather resistance, hydrolysis resistance, and salt and alkali resistance. These two polymer raw materials form a synergistic protective composite structure during film formation to exert their effects, ensuring the coating possesses the necessary surface hardness while providing a certain degree of flexibility and elasticity to help the coating adapt to minor deformations of the substrate and alleviate external stress. More importantly, the two polymers interact to build a dense protective barrier within the coating. This barrier effectively blocks the intrusion of moisture, ultraviolet radiation, and corrosive salt and alkali substances, thereby delaying the material aging process. Detailed Implementation

[0042] In the following specific embodiments, unless otherwise specified, the sources / preparation methods of some raw materials are as follows: Example 1

[0043] A surface treatment agent for permeable concrete, comprising, by weight, the following raw materials: 70.5 parts silicone-acrylic emulsion, 6.2 parts composite film-forming agent, 1.1 parts wetting agent, 8.8 parts functional agent, 0.45 parts defoamer, 2.2 parts inorganic thickener, 7.5 parts color paste, 10 parts polymer additive, 0.4 parts ultraviolet absorber, 0.8 parts water-repellent agent, 0.12 parts bactericide, and 16 parts deionized water.

[0044] The silicone-acrylic emulsion, model BF-400B, is from Tangyi Chemical in Jining, China.

[0045] The composite film-forming agent is a combination of dodecyl alcohol ester and ethylene glycol butyl ether in a mass ratio of 3:1.

[0046] The wetting agent is ammonium polyacrylate, model 3000, manufactured by Guangzhou Jinkai Chemical Co., Ltd.; the defoamer is organosilicon BYK-088; the inorganic thickener is bentonite; and the color paste is iron oxide red paste.

[0047] The functional agent is a combination of polycarbodiimide and epoxy-terminated polydimethylsiloxane in a mass ratio of 2:1.

[0048] Polycarbodiimide, coating grade, Wuhan Huaxiang Kejie.

[0049] Epoxy-terminated polydimethylsiloxane, industrial grade, Wuhan Kemic.

[0050] The polymer additive is a combination of an aqueous polyurethane dispersion and a pure acrylic emulsion at a mass ratio of 0.6:1; the aqueous polyurethane dispersion is Bayhydrol® UH 2888, Covestro, Germany; and the pure acrylic emulsion is Acronal® LR 8960, BASF, Germany.

[0051] The UV absorber is benzotriazole-based TINUVIN® 1130.

[0052] The water-repellent agent is organosilane BS 1306, manufactured by Wacker Chemie, Germany.

[0053] The bactericide is isothiazolinone, from Shandong Kasong New Materials.

[0054] A method for preparing a surface coating agent for permeable concrete includes the following steps: S1: After adding deionized water to the reaction tank, the rotation speed is adjusted to 300 r / min. Bactericide, water-repellent agent, and polymer additive are added to the dropper and slowly dripped into the reaction tank. Then, silicone-acrylic emulsion, composite film-forming agent, and functional agent are dripped into the reaction tank, and the rotation speed is adjusted to 500 r / min until the emulsion is evenly dispersed; S2: The remaining raw materials, except for the color paste, are slowly dripped into the reaction tank in sequence, and each addition is dispersed for 18 minutes until no oil shrinkage occurs; S3: Finally, the rotation speed is adjusted to 800 r / min, and after dispersing for 12 minutes until the viscosity stabilizes, the color paste is slowly added and dispersed for 10 minutes until the color is fully mixed and uniform, thus obtaining the final product.

[0055] Example 2 This embodiment differs from Embodiment 1 only in the following aspects: A surface coating agent for permeable concrete, by weight, comprises the following raw materials: 75 parts silicone-acrylic emulsion, 7 parts composite film-forming agent, 1.1 parts wetting agent, 9.5 parts functional agent, 0.45 parts defoamer, 2.2 parts inorganic thickener, 7.5 parts color paste, 9.5 parts polymer additive, 0.4 parts ultraviolet absorber, 0.8 parts water-repellent agent, 0.12 parts bactericide, and 14 parts deionized water.

[0056] The composite film-forming agent is a combination of dodecyl alcohol ester and ethylene glycol butyl ether in a mass ratio of 2.5:1.

[0057] The remaining implementation methods are the same.

[0058] Example 3 This embodiment differs from Embodiment 1 only in the following aspects: A surface coating agent for permeable concrete, by weight, comprises the following raw materials: 67.5 parts silicone-acrylic emulsion, 5.8 parts composite film-forming agent, 1.1 parts wetting agent, 7.5 parts functional agent, 0.45 parts defoamer, 2.2 parts inorganic thickener, 7.5 parts color paste, 8.5 parts polymer additive, 0.4 parts ultraviolet absorber, 0.8 parts water-repellent agent, 0.12 parts bactericide, and 15 parts deionized water.

[0059] The mass ratio of polycarbodiimide to epoxy-terminated polydimethylsiloxane is 2.5:1.

[0060] The remaining implementation methods are the same.

[0061] Comparative Example 1 This comparative example differs from Example 1 only in the following aspects: A topcoat agent for permeable concrete, by weight, comprises the following raw materials: 80 parts silicone-acrylic emulsion, 8.5 parts composite film-forming agent, 1.5 parts wetting agent, 2 parts functional agent, 0.6 parts defoamer, 2.6 parts inorganic thickener, 8.8 parts color paste, 12 parts polymer additive, 0.6 parts ultraviolet absorber, 0.8 parts water-repellent agent, 0.15 parts bactericide, and 18.5 parts deionized water.

[0062] The remaining implementation methods are the same.

[0063] Comparative Example 2 This comparative example differs from Example 1 only in the following aspects: A topcoat agent for permeable concrete, comprising, by weight, the following raw materials: 80.5 parts silicone-acrylic emulsion, 6.2 parts composite film-forming agent, 1.1 parts wetting agent, 8.8 parts functional agent, 0.45 parts defoamer, 2.2 parts inorganic thickener, 7.5 parts color paste, 3.5 parts polymer additive, 0.4 parts ultraviolet absorber, 0.8 parts water-repellent agent, 0.12 parts bactericide, and 16 parts deionized water.

[0064] The remaining implementation methods are the same.

[0065] Comparative Example 3 The only difference between this comparative example and Example 1 is that the composite film-forming agent is a combination of dodecyl alcohol ester and ethylene glycol butyl ether in a mass ratio of 8:1.

[0066] The remaining implementation methods are the same.

[0067] Comparative Example 4 This comparative example differs from Example 1 only in the following way: the functional agent is a combination of polycarbodiimide and epoxy-terminated polydimethylsiloxane in a mass ratio of 1:3.

[0068] The remaining implementation methods are the same.

[0069] Comparative Example 5 This comparative example differs from Example 1 only in the following way: the functional agent is a combination of polycarbodiimide and epoxy-terminated polydimethylsiloxane in a mass ratio of 5:1.

[0070] The remaining implementation methods are the same.

[0071] Comparative Example 6 The only difference between this comparative example and Example 1 is that the polymer additive is a combination of an aqueous polyurethane dispersion and a pure acrylic emulsion, with a mass ratio of 0.2:1.

[0072] The remaining implementation methods are the same.

[0073] Performance testing 1. Hardness: The test references ASTM D3363-22. The topcoat is evenly applied to a flat glass plate using a wire bar applicator. The wet film thickness is controlled at 200μm. It is cured for 7 days at a temperature of 23±2℃ and a relative humidity of 50±5% to ensure complete curing. A pencil is fixed at a 45° angle to a pencil hardness tester, and a constant load of 750g is applied. The pencil is pushed on the coating surface at a speed of 1cm / s to create a scratch of at least 7mm. Starting with the hardest pencil, the hardness is gradually reduced until a pencil can no longer scratch the coating surface. The results are recorded in Table 1.

[0074] 2. Gloss: The test is conducted according to ASTM D523-14, similar to the hardness test. A film is prepared and cured on a flat glass plate to obtain a smooth, repeatable surface. The 60° angle gloss meter is calibrated using high-gloss and low-gloss standard plates. The gloss meter is placed stably on the paint film surface, and at least 10 values ​​are read in different areas. The average of the 10 readings is calculated as the final gloss value, and the results are recorded in Table 1.

[0075] 3. Water resistance: Apply a topcoat agent to the surface of actual permeable concrete test blocks (150mm×70mm×30mm) and cure for 7 days under standard conditions. In a constant temperature water bath (temperature strictly controlled at 25±1℃), immerse the test blocks with the coated side facing up in distilled water, ensuring the coated surface is 40-45mm below the water surface. After soaking for 96 hours, remove the blocks, blot dry the surface moisture with filter paper, and immediately visually inspect the coating. Check for bubbles, peeling, loss of gloss, discoloration, and wrinkling. Record the number of samples out of 50 parallel samples that exhibit any of the above-mentioned defects, calculate the pass rate, and record the results in Table 1.

[0076] 4. Abrasion resistance: Prepare a uniform coating in the center area of ​​a flat, clean glass plate, cure for 7 days, and the thickness should not be less than 45μm; use a Taber abrasion tester with a CS-10 rubber grinding wheel, under a 1kg load, run it idle for 50 revolutions to make the grinding wheel surface flat, fix the sample on the turntable, lower the loading arm, and rotate it 1000 revolutions under a 1kg load. Use a precision balance to weigh the sample before and after the test, and the difference between the two is the abrasion amount. Take the average value of 10 test results and record it in Table 1.

[0077] 5. Salt and alkali resistance: Apply a topcoat agent to the permeable concrete test block, and after sufficient curing, strictly seal the non-test surfaces and edges. Prepare a saturated Ca(OH)2 solution containing 3% NaCl. Immerse the test block with the coated side facing up in the above composite solution. The solution level should be at least 30 mm above the top of the coating. The temperature should be controlled at 45±2℃ to accelerate corrosion. Continue immersion for 168 hours. After the test, remove the test block and gently rinse off any salt and alkali residue with running water. Then blot dry with filter paper and immediately visually inspect the coating for blistering, peeling, cracking, chalking, significant discoloration, or loss of gloss. Record the number of samples with any of the above-mentioned destructive phenomena among 50 parallel samples, calculate the pass rate, and record the results in Table 1.

[0078] Table 1 Performance Test Results

[0079] Analysis of Test Results: The final performance test results show that Examples 1-3 achieved superior overall performance compared to Comparative Examples 1-6. This is mainly due to the corresponding technical solutions specified in this application used in Examples 1-3, which significantly improved the overall performance of the permeable concrete overlay agent by adding functional agents. These agents primarily form a stable protective layer on the coating surface, effectively blocking the erosion of moisture, ultraviolet rays, and corrosive salts and alkalis, thereby delaying coating aging and extending its service life. Furthermore, the addition of polymer additives effectively improves the overall durability of the coating, particularly in terms of weather resistance, hydrolysis resistance, and salt and alkali resistance. In contrast, Comparative Examples 1-6, because they adopted different technical solutions than those specified in this application, showed a significant decrease in the effectiveness of their raw materials in the system, ultimately leading to a decline in the overall performance of the products.

[0080] The above description is the preferred embodiment of this application. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principles described in this application, and these improvements and modifications should also be considered within the scope of protection of this application.

Claims

1. A topcoat agent for permeable concrete, characterized in that: By weight, the raw materials include: 60-80 parts silicone-acrylic emulsion, 4-8 parts composite film-forming agent, 0.6-1.2 parts wetting agent, 4-10 parts functional agent, 0.4-0.8 parts defoamer, 1-3 parts inorganic thickener, 5-12 parts color paste, 10-20 parts deionized water, 5-15 parts polymer additives, 0.3-0.6 parts ultraviolet absorber, 0.5-1.5 parts water repellent, and 0.1-0.3 parts bactericide; The functional agent is a combination of polycarbodiimide and epoxy-terminated polydimethylsiloxane, with a mass ratio of (1.5~2.5):(1~1.2). The composite film-forming agent is a combination of dodecyl alcohol ester and ethylene glycol butyl ether, with a mass ratio of (2.5~3.2):(1~1.3).

2. The topcoat agent for permeable concrete according to claim 1, characterized in that: The mass ratio of the composite film-forming agent to the functional agent in the silicone-acrylic emulsion is (6.5~7.5):(0.5~0.7):(0.6~1).

3. The topcoat agent for permeable concrete according to claim 2, characterized in that: The inorganic thickener is at least one of bentonite, magnesium aluminum silicate, montmorillonite, fumed silica, and sodium silicate.

4. The surface treatment agent for permeable concrete according to claim 3, characterized in that: The wetting agent is at least one of ammonium polyacrylate, sodium polycarboxylate, and sodium polyacrylate.

5. The topcoat agent for permeable concrete according to claim 4, characterized in that: The mass ratio of the silicone-acrylic emulsion to the polymer additive is (6.5~7.5):(0.8~1.2).

6. The topcoat agent for permeable concrete according to claim 5, characterized in that: The polymer additive is a combination of an aqueous polyurethane dispersion and a pure acrylic emulsion, with a mass ratio of (0.5~0.8):

1.

7. The topcoat agent for permeable concrete according to claim 6, characterized in that: The aqueous polyurethane dispersion is Bayhydrol® UH 2888; the pure acrylic emulsion is Acronal® LR 8960.

8. A method for preparing a topcoat agent for permeable concrete according to any one of claims 1 to 7, characterized in that: Specifically, the following steps are included: S1: After adding deionized water to the reaction tank, adjust the rotation speed to 250~300 r / min. Add bactericide, water-repellent agent, and polymer additives to the dropper and slowly drop them into the reaction tank. Then, add silicone-acrylic emulsion, composite film-forming agent, and functional agent to the reaction tank and adjust the rotation speed to 400~500 r / min until the emulsion is evenly dispersed. S2: Add the remaining raw materials, except for the color paste, to the reaction tank in sequence at a slow speed. Disperse for 15~20 minutes after each addition until there is no oil shrinkage. S3: Finally, adjust the rotation speed to 700~800 r / min and disperse for 10~15 minutes until the viscosity stabilizes. Then, slowly add the color paste and disperse for 8~10 minutes until the color is fully mixed and even.

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