A coating composition for bridge concrete and a method for preparing the same

Abstract

The application belongs to the technical field of paint preparation, and particularly relates to a paint composition for bridge concrete and a preparation method thereof. The paint composition for bridge concrete comprises acrylic emulsion, modified diatomite, cationic beta-cyclodextrin, nano-silicon dioxide, dispersing agent, defoaming agent, leveling agent and water. The preparation process of the modified diatomite is as follows: the diatomite is pretreated; the pretreated diatomite is added into a solution of vinyl triethoxysilane, and the pretreated diatomite is obtained after reaction; the pretreated diatomite is added into a solution of tripropyleneglycol dipropyl acrylate, 2-hydroxy-4-methacryloyloxybenzophenone and initiator, and the modified diatomite is obtained after heating reaction. The application significantly improves the ultraviolet aging resistance, water resistance and corrosion resistance of the paint by introducing the modified diatomite and cationic cyclodextrin.

Description

Technical Field

[0001] This invention belongs to the field of coating preparation technology, specifically relating to a coating composition for bridge concrete and its preparation method. Background Technology

[0002] In bridge construction, concrete, as the primary building material, directly affects the safety and service life of the bridge due to its stability and durability. However, bridge concrete is exposed to the natural environment for extended periods, subject to erosion from various factors such as ultraviolet radiation, wind, rain, and chemical corrosion. This leads to surface cracking, spalling, and corrosion, severely impacting the bridge's aesthetics and safety. Therefore, developing a coating composition for bridge concrete is of great significance for improving bridge durability and safety.

[0003] Concrete is a porous material, easily penetrated by water and corrosive media, leading to corrosion and reduced service life. To address this vulnerability, various protective coatings have been developed. These coatings primarily function to prevent water and corrosive media from penetrating the concrete, thus slowing corrosion and extending its lifespan. Common types of existing bridge concrete protective coatings include penetrating and film-forming types. Penetrating coatings form a dense, waterproof layer on the concrete surface through penetration, preventing the intrusion of water and corrosive media. However, these coatings have limited protective durability and poor recoating properties, making them unsuitable for long-term protection. Film-forming coatings, on the other hand, form a complete protective layer on the concrete surface, offering better protection. While traditional bridge concrete protective coatings can protect concrete from environmental erosion to some extent, they still have shortcomings in weather resistance, waterproofing, and corrosion resistance. Especially under ultraviolet radiation, the coatings are prone to aging, leading to a decline in coating performance and affecting their protective effect. Furthermore, traditional coatings also have limitations in waterproofing and corrosion prevention, making them unsuitable for long-term protection.

[0004] To address the aforementioned technical challenges, developing a coating with strong resistance to UV aging, weathering, and waterproofing and corrosion protection is of great significance for extending the service life of bridge concrete, enhancing its aesthetics, and promoting environmental protection and sustainable development. Summary of the Invention

[0005] The primary objective of this invention is to provide a coating composition for bridge concrete. By pretreating and modifying diatomaceous earth to introduce groups capable of absorbing ultraviolet light, and simultaneously adding cationic β-cyclodextrin, the synergistic effects of these components significantly improve the coating's resistance to ultraviolet aging, water resistance, and corrosion resistance. This coating not only provides excellent protection but also reduces maintenance costs and extends the service life of bridges, which is of great significance for ensuring the safety and stability of bridges.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A coating composition for bridge concrete comprises the following raw materials in parts by weight: 40-60 parts acrylic emulsion, 15-25 parts modified diatomaceous earth, 5-10 parts cationic β-cyclodextrin, 5-10 parts nano silica, 1-5 parts dispersant, 1-3 parts defoamer, 0.5-1 part leveling agent, and 20-30 parts water. The preparation process of the modified diatomaceous earth is as follows: (1) Pre-treat the diatomaceous earth; (2) Add the diatomaceous earth pretreated in step (1) to a solution of vinyltriethoxysilane, and after the reaction, pre-modified diatomaceous earth is obtained; (3) Add the pre-modified diatomaceous earth from step (2) to a solution of tripropylene glycol diacrylate, then add 2-hydroxy-4-methylacryloyloxybenzophenone and an initiator, and heat the reaction to obtain modified diatomaceous earth.

[0007] Further, the mass ratio of vinyltriethoxysilane to pretreated diatomaceous earth in step (2) is 1:(7.5-10).

[0008] Furthermore, the temperature of the reaction in step (2) is 60-70℃, and the reaction time is 3-5h.

[0009] Further, the solvent in the vinyltriethoxysilane solution in step (2) is composed of ethanol and water in a volume ratio of 4:1.

[0010] Further, the initiator in step (3) is azobisisobutyronitrile, and the solvent in the solution of tripropylene glycol diacrylate is DMF.

[0011] Further, the mass ratio of the pre-modified diatomaceous earth, tripropylene glycol diacrylate, 2-hydroxy-4-methacryloyloxybenzophenone, and initiator in step (3) is 100:(10-15):(1-1.5):(0.5-1).

[0012] Furthermore, the heating reaction in step (3) is carried out at a temperature of 55-65°C for 4-5 hours.

[0013] Furthermore, the solvent in the solution of tripropylene glycol diacrylate is DMF.

[0014] Further, the pretreatment process of the diatomaceous earth in step (1) is as follows: Add diatomaceous earth to a 5% nitric acid solution, stir at 75-80℃ for 2-3 hours, then filter, wash with pure water until neutral, dry, and calcine at 400-500℃ for 2-3 hours to obtain the final product.

[0015] Furthermore, the preparation method of the cationic β-cyclodextrin includes the following steps: β-Cyclodextrin was added to NaOH solution, followed by 2,3-epoxypropyltrimethylammonium chloride and an aqueous ethanol solution. The mixture was reacted at 60-70℃ for 3-4 hours to obtain cationic β-cyclodextrin.

[0016] A second objective of the present invention is to provide a method for preparing a coating composition for bridge concrete.

[0017] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a coating composition for bridge concrete includes the following steps: According to the stated weight proportions, the acrylic emulsion, dispersant, defoamer, leveling agent, and water are mixed and stirred evenly. Then, modified diatomaceous earth, cationic β-cyclodextrin, and nano-silica are added and stirred to obtain the final product.

[0018] Compared with the prior art, the main advantages of the present invention are as follows: 1. This invention improves the specific surface area of ​​diatomaceous earth through pretreatment, followed by pre-modification with vinyltriethoxysilane, successfully introducing double bonds into the vinyl group. The pre-modified diatomaceous earth reacts with 2-hydroxy-4-methacryloyloxybenzophenone and tripropylene glycol diacrylate under the action of an initiator. The acrylate double bonds in 2-hydroxy-4-methacryloyloxybenzophenone undergo free radical copolymerization with tripropylene glycol diacrylate and the vinyl groups on the surface of the diatomaceous earth, thereby introducing groups that absorb ultraviolet light, resulting in modified diatomaceous earth. Adding this modified diatomaceous earth to coatings can improve its dispersibility and interfacial compatibility, reduce UV-induced aging caused by interfacial defects, and improve the mechanical properties of the coating. On the other hand, the introduction of 2-hydroxy-4-methacryloyloxybenzophenone further improves its UV aging resistance, and by forming a polymer network structure on the diatomaceous earth surface, it avoids migration and loss in the coating, improves stability, effectively enhances the coating's UV aging resistance, and improves its weather resistance.

[0019] 2. The porous structure of the modified diatomaceous earth of this invention can adsorb cationic β-cyclodextrin, which helps to form a dense film structure on the coating surface. This film structure not only improves the anti-corrosion performance of the coating and effectively resists the erosion of chemicals such as acids and alkalis, but also improves the wear resistance and impact resistance of the coating.

[0020] 3. By improving the coating's resistance to ultraviolet aging and its waterproof and anti-corrosion properties, this invention can significantly extend the coating's service life, reduce the frequency of maintenance and replacement, and thus lower the cost of use. Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to specific embodiments. However, those skilled in the art should understand that the following embodiments are only for illustrating the present invention and should not be regarded as limiting the present invention. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, the reagents or instruments used are all conventional products obtained through commercial channels.

[0022] The dispersant in this invention is hexadecyltrimethylammonium bromide, the leveling agent is tris(hydroxymethyl)aminomethane, and the defoamer is oleate.

[0023] Example 1 A coating composition for bridge concrete comprises the following raw materials in parts by weight: 50 parts acrylic emulsion, 20 parts modified diatomaceous earth, 7 parts cationic β-cyclodextrin, 7 parts nano silica, 3 parts dispersant, 2 parts defoamer, 0.7 parts leveling agent, and 25 parts water. The preparation process of the cationic β-cyclodextrin is as follows: Weigh β-cyclodextrin and add it to a 0.1 mol / L NaOH solution to obtain a 1 g / mL solution. Then add 2,3-epoxypropyltrimethylammonium chloride and an aqueous ethanol solution (ethanol to water volume ratio of 2:5), wherein the mass ratio of β-cyclodextrin to 2,3-epoxypropyltrimethylammonium chloride is 1:3. Heat to 70℃ and react for 4 h. Adjust the pH to 7 and dry under vacuum at 65℃ for 24 h to obtain cationic β-cyclodextrin.

[0024] The preparation process of the modified diatomaceous earth is as follows: (1) Add diatomaceous earth to a 5% nitric acid solution to obtain a 2% dispersion. Stir at 75°C for 2.5 h, then filter, wash with pure water until neutral, dry, and calcine at 450°C for 2.5 h to obtain the pretreated diatomaceous earth. (2) Add the pretreated diatomaceous earth and vinyltriethoxysilane from step (1) to an aqueous solution of ethanol (volume ratio of ethanol to water is 4:1), wherein the mass ratio of vinyltriethoxysilane to pretreated diatomaceous earth is 1:10, and the volume ratio of pretreated diatomaceous earth to aqueous solution of ethanol is 10g:150mL; react at 65℃ for 4h, and obtain pre-modified diatomaceous earth after filtration, washing and drying. (3) Add the pre-modified diatomaceous earth and tripropylene glycol diacrylate from step (2) to N,N-dimethylformamide (DMF), wherein the ratio of the pre-modified diatomaceous earth to DMF is 1g:20mL; then add 2-hydroxy-4-methacryloyloxybenzophenone and initiator (azobisisobutyronitrile), wherein the mass ratio of the pre-modified diatomaceous earth, tripropylene glycol diacrylate, 2-hydroxy-4-methacryloyloxybenzophenone and initiator is 100:12.5:1.2:0.75, heat to 60℃ and react for 4.5h, filter, wash and dry to obtain modified diatomaceous earth.

[0025] A method for preparing a coating composition for bridge concrete includes the following steps: Based on the above weight proportions, mix and stir the acrylic emulsion, dispersant, defoamer, leveling agent, and water until homogeneous. Then add modified diatomaceous earth, cationic β-cyclodextrin, and nano silica, and stir to obtain the final product.

[0026] Example 2 A coating composition for bridge concrete comprises the following raw materials in parts by weight: 40 parts acrylic emulsion, 15 parts modified diatomaceous earth, 5 parts cationic β-cyclodextrin, 5 parts nano silica, 1 part dispersant, 1 part defoamer, 0.5 parts leveling agent, and 20 parts water. The preparation process of the cationic β-cyclodextrin is the same as in Example 1; The preparation process of the modified diatomaceous earth is as follows: (1) Add diatomaceous earth to a nitric acid solution with a mass fraction of 5% to obtain a dispersion with a mass fraction of 2%. Stir at 75°C for 3 hours, then filter, wash with pure water until neutral, dry, and calcine at 400°C for 3 hours to obtain the pretreated diatomaceous earth. (2) The diatomaceous earth and vinyltriethoxysilane pretreated in step (1) were added to an aqueous solution of ethanol (the volume ratio of ethanol to water was 4:1), wherein the mass ratio of vinyltriethoxysilane to pretreated diatomaceous earth was 1:7.5, and the volume ratio of pretreated diatomaceous earth to aqueous solution of ethanol was 10g:150mL; the reaction was carried out at 60℃ for 5h, and the pre-modified diatomaceous earth was obtained after filtration, washing and drying. (3) Add the pre-modified diatomaceous earth and tripropylene glycol diacrylate from step (2) to DMF, wherein the ratio of the pre-modified diatomaceous earth to DMF is 1g:20mL; then add 2-hydroxy-4-methacryloyloxybenzophenone and initiator (azobisisobutyronitrile), wherein the mass ratio of the pre-modified diatomaceous earth, tripropylene glycol diacrylate, 2-hydroxy-4-methacryloyloxybenzophenone and initiator is 100:10:1:0.5, heat to 55℃ and react for 5h, filter, wash and dry to obtain modified diatomaceous earth.

[0027] A method for preparing a coating composition for bridge concrete includes the following steps: Based on the above weight proportions, mix and stir the acrylic emulsion, dispersant, defoamer, leveling agent, and water until homogeneous. Then add modified diatomaceous earth, cationic β-cyclodextrin, and nano silica, and stir to obtain the final product.

[0028] Example 3 A coating composition for bridge concrete comprises the following raw materials in parts by weight: 60 parts acrylic emulsion, 25 parts modified diatomaceous earth, 10 parts cationic β-cyclodextrin, 10 parts nano silica, 5 parts dispersant, 3 parts defoamer, 1 part leveling agent, and 30 parts water. The preparation process of the cationic β-cyclodextrin is the same as in Example 1; The preparation process of the modified diatomaceous earth is as follows: (1) Add diatomaceous earth to a nitric acid solution with a mass fraction of 5% to obtain a dispersion with a mass fraction of 2%. Stir at 80°C for 2 hours, then filter, wash with pure water until neutral, dry, and calcine at 450°C for 2 hours to obtain the pretreated diatomaceous earth. (2) The diatomaceous earth and vinyltriethoxysilane pretreated in step (1) are added to an aqueous solution of ethanol (the volume ratio of ethanol to water is 4:1), the mass ratio of vinyltriethoxysilane to pretreated diatomaceous earth is 1:9, and the volume ratio of pretreated diatomaceous earth to aqueous solution of ethanol is 10g:150mL; react at 70℃ for 3h, filter, wash and dry to obtain pre-modified diatomaceous earth; (3) Add the pre-modified diatomaceous earth and tripropylene glycol diacrylate from step (2) to DMF, wherein the ratio of the pre-modified diatomaceous earth to DMF is 1g:20mL; then add 2-hydroxy-4-methacryloyloxybenzophenone and initiator (azobisisobutyronitrile), wherein the mass ratio of the pre-modified diatomaceous earth, tripropylene glycol diacrylate, 2-hydroxy-4-methacryloyloxybenzophenone and initiator is 100:15:1.5:1; heat to 65℃ and react for 4h, then filter, wash and dry to obtain modified diatomaceous earth.

[0029] A method for preparing a coating composition for bridge concrete includes the following steps: Based on the above weight proportions, mix and stir the acrylic emulsion, dispersant, defoamer, leveling agent, and water until homogeneous. Then add modified diatomaceous earth, cationic β-cyclodextrin, and nano silica, and stir to obtain the final product.

[0030] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the modified diatomaceous earth is replaced with a mixture of diatomaceous earth, tripropylene glycol diacrylate and 2-hydroxy-4-methacryloyloxybenzophenone, and the amounts of diatomaceous earth, tripropylene glycol diacrylate and 2-hydroxy-4-methacryloyloxybenzophenone are the same as in Example 1.

[0031] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that cationic β-cyclodextrin is replaced with β-cyclodextrin; otherwise, they are the same as in Example 1.

[0032] To characterize the performance of the above products, the following tests were conducted to verify their effectiveness.

[0033] Experimental Example 1 To test the UV resistance of the protective coatings of Examples 1-3 and Comparative Examples 1-2 of the present invention, the coatings prepared in each group were applied to the surface of concrete samples, and the aging resistance time of each coating was tested according to the standard of ASTM D4587. The results are shown in Table 1.

[0034] Table 1 As shown in Table 1, the coatings of Examples 1-3 exhibit excellent UV resistance, significantly superior to those of Comparative Examples 1-2, with a maximum aging resistance time of approximately 1000 hours, indicating relatively long-lasting UV stability. This is because the present invention first vinyl-modifies diatomaceous earth, and then copolymerizes it with tripropylene glycol diacrylate and 2-hydroxy-4-methacryloyloxybenzophenone, introducing UV-absorbing groups to form a polymer network structure. Adding this modified diatomaceous earth to the coating further enhances its UV aging resistance. In Comparative Example 1, directly mixing diatomaceous earth, tripropylene glycol diacrylate, and 2-hydroxy-4-methacryloyloxybenzophenone fails to form a polymer network structure on the diatomaceous earth surface, resulting in poorer UV stability of the coating.

[0035] Experimental Example 2 The protective coatings of Examples 1-3 and Comparative Examples 1-2 were applied to concrete test blocks and left for 24 hours. The following performance tests were then conducted on the protective coatings: (1) Water resistance: The dry film thickness is 50μm. The water resistance of the coating in the early stage is tested according to the test standard of GB / T9274-1988. The time when the coating begins to blister, crack, peel off and lose gloss is recorded.

[0036] (2) Abrasion resistance: The abrasion resistance of the coating was tested according to the test standard of GB / T1768-89. The grinding speed was set to 500r and the load was 500g. (3) Acid and alkali resistance: The acid and alkali resistance of the coating were tested according to the test standard GB / T 9274-1988. The time it took for the coating to be immersed in 5 g / L hydrochloric acid solution and 5 g / L sodium hydroxide solution until wrinkles appeared was recorded.

[0037] (4) Impact resistance: Record the impact resistance of the coating according to the test standard of GB / T1732-93 "Test Method for Impact Resistance of Coating Film".

[0038] (5) Adhesion: The adhesion of the coating is tested according to the test standard GB / T 5210-2006.

[0039] The test results are shown in Table 2.

[0040] Table 2 As can be seen from the test results in Table 2, the coatings prepared in Examples 1-3 of this invention have superior waterproof performance, acid and alkali corrosion resistance, wear resistance, and impact resistance.

[0041] Compared to Example 1, Comparative Example 1, which replaced the modified diatomaceous earth with diatomaceous earth, tripropylene glycol diacrylate, and 2-hydroxy-4-methacryloyloxybenzophenone, showed a significant decrease in the coating's impact resistance and abrasion resistance. The interfacial compatibility of the diatomaceous earth and other components in the coating deteriorated, affecting the material's mechanical properties. Furthermore, the three components—diatomaceous earth, tripropylene glycol diacrylate, and 2-hydroxy-4-methacryloyloxybenzophenone—could not effectively form a polymer network structure on the diatomaceous earth surface, resulting in inferior corrosion resistance and weather resistance compared to Example 1.

[0042] Compared to Example 1, in Comparative Example 2, replacing cationic β-cyclodextrin with β-cyclodextrin resulted in a decrease in all properties of the coating. This is because the modified diatomaceous earth in the coating components of this invention can adsorb cationic β-cyclodextrin through its porous structure, forming a dense film structure on the coating surface. This film structure prevents corrosive ions such as acids and alkalis from entering the coating, thereby effectively increasing the coating's waterproof and corrosion-resistant properties. The combined effect of modified diatomaceous earth, cationic β-cyclodextrin, and other components improves the overall performance of the coating.

[0043] In summary, the introduction of modified diatomaceous earth in this invention not only improves the UV resistance and mechanical properties of the coating, but also enhances its waterproof and anti-corrosion properties through its porous structure and the dense film structure formed by adsorbed cationic cyclodextrin, significantly extending the service life of the coating.

[0044] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. The basic principles and main features of the present invention have been described above with specific implementation schemes. Based on the present invention, some modifications or substitutions can be made, but these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of protection claimed by the present invention.

Claims

1. A coating composition for bridge concrete, characterized in that, The raw materials include the following parts by weight: 40-60 parts acrylic emulsion, 15-25 parts modified diatomaceous earth, 5-10 parts cationic β-cyclodextrin, 5-10 parts nano silica, 1-5 parts dispersant, 1-3 parts defoamer, 0.5-1 part leveling agent, and 20-30 parts water. The preparation process of the modified diatomaceous earth is as follows: (1) Pre-treat the diatomaceous earth; (2) Add the pretreated diatomaceous earth from step (1) to a solution of vinyltriethoxysilane, and after the reaction, pre-modified diatomaceous earth is obtained; (3) Add the pre-modified diatomaceous earth from step (2) to a solution of tripropylene glycol diacrylate, then add 2-hydroxy-4-methylacryloyloxybenzophenone and an initiator, and heat the reaction to obtain modified diatomaceous earth.

2. The coating composition for bridge concrete according to claim 1, characterized in that, The mass ratio of vinyltriethoxysilane to pretreated diatomaceous earth in step (2) is 1:(7.5-10).

3. The coating composition for bridge concrete according to claim 1, characterized in that, The reaction temperature in step (2) is 60-70℃, and the reaction time is 3-5h.

4. The coating composition for bridge concrete according to claim 1, characterized in that, The solvent in the vinyltriethoxysilane solution in step (2) is composed of ethanol and water in a volume ratio of 4:

1.

5. The coating composition for bridge concrete according to claim 1, characterized in that, The initiator in step (3) is azobisisobutyronitrile, and the solvent in the solution of tripropylene glycol diacrylate is DMF.

6. The coating composition for bridge concrete according to claim 1, characterized in that, The mass ratio of the pre-modified diatomaceous earth, tripropylene glycol diacrylate, 2-hydroxy-4-methacryloyloxybenzophenone, and initiator in step (3) is 100:(10-15):(1-1.5):(0.5-1).

7. The coating composition for bridge concrete according to claim 1, characterized in that, The heating reaction in step (3) is carried out at a temperature of 55-65℃ for 4-5 hours.

8. The coating composition for bridge concrete according to claim 1, characterized in that, The pretreatment process of diatomaceous earth in step (1) is as follows: Add diatomaceous earth to a 5% nitric acid solution, stir at 75-80℃ for 2-3 hours, then filter, wash with pure water until neutral, dry, and calcine at 400-500℃ for 2-3 hours to obtain the final product.

9. The coating composition for bridge concrete according to claim 1, characterized in that, The preparation method of the cationic β-cyclodextrin includes the following steps: β-Cyclodextrin was added to NaOH solution, followed by 2,3-epoxypropyltrimethylammonium chloride and an aqueous ethanol solution. The mixture was reacted at 60-70℃ for 3-4 hours to obtain cationic β-cyclodextrin.

10. A method for preparing a coating composition for bridge concrete according to any one of claims 1-9, characterized in that, Includes the following steps: According to the stated weight proportions, the acrylic emulsion, dispersant, defoamer, leveling agent, and water are mixed and stirred evenly. Then, modified diatomaceous earth, cationic β-cyclodextrin, and nano-silica are added and stirred to obtain the final product.

Images