Preparation method of marine polymer cement-based hydrophobic coating

Abstract

This invention relates to the field of cement-based material preparation, specifically disclosing a method for preparing a polymer cement-based hydrophobic coating for marine engineering. The method includes the following steps: mixing modified fluoroacrylic emulsion, mixing water, film-forming aid, and dispersant, then adding the mixture to a powder mixture formed by cement powder and filler, and finally stirring until homogeneous to obtain the hydrophobic cement-based coating. The proportions of each raw material are: 30-60 parts by weight of modified fluoroacrylic emulsion, 10-25 parts by weight of mixing water, 1-3 parts by weight of film-forming aid, 0.2-1 parts by weight of dispersant, and 80-120 parts by weight of the mixed powder. This invention, based on a modified fluoroacrylic emulsion that combines excellent stability, hydrophobic film properties, and cement compatibility, effectively overcomes the problem of insufficient hydrophobicity in traditional polymer cement-based coatings.

Description

Technical Field

[0001] This invention relates to the field of cement-based material preparation, and specifically to a method for preparing a polymer cement-based hydrophobic coating for marine engineering. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] With rapid economic development, the construction industry is still in a state of flux. Cement-based materials are irreplaceable and crucial materials in construction projects, and their usage is enormous. However, concrete structures serving in special environments such as marine engineering are subject to long-term invasion by corrosive media such as soluble chlorides, magnesium salts, and sulfates, causing problems such as corrosion of internal steel bars and deterioration of concrete structural performance, which seriously affects the service life of concrete structures.

[0004] Polymer cement-based coatings, through the synergistic development of the cement hydration and hardening process and the polymer film-forming process, as well as the physicochemical combination between the two, form an organic-inorganic composite network structure that combines rigidity, flexibility, and density. Furthermore, polymer cement-based coatings possess advantages such as strong compositional design flexibility, synergistic performance enhancement, and good mechanical properties, corrosion resistance, and weather resistance, and are currently widely used in various protective engineering projects. However, traditional polymer cement-based coatings generally suffer from poor hydrophobicity, failing to effectively block the transport of corrosive media such as water and salt, making it difficult to meet the protective requirements of concrete structures in marine engineering. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a method for preparing a polymer cement-based hydrophobic coating for marine engineering. The method utilizes a modified fluoroacrylic emulsion that combines excellent stability, hydrophobicity of the film, and cement compatibility, effectively overcoming the insufficient hydrophobicity of traditional polymer cement-based coatings. To achieve the above objectives, this invention discloses the following technical solution.

[0006] A method for preparing a polymer cement-based hydrophobic coating for marine engineering includes the following steps:

[0007] (1) Inorganic nanoparticles were added to an aqueous system containing an aqueous superdispersant to form an aqueous suspension, which was then adjusted to alkaline to obtain an alkaline dispersion system. Dopamine monomer was added to the system and reacted, followed by the addition of a fluorinated nucleophile to continue the reaction. After the reaction was completed, the solid product was separated, washed, and dried to obtain modified inorganic particles for later use.

[0008] (2) Mix methyl methacrylate monomer, butyl acrylate monomer and hexafluorobutyl methacrylate monomer to obtain an oil phase mixture; mix it with the aqueous dispersion of the modified inorganic particles and pre-emulsify it to obtain a pre-emulsion for later use.

[0009] (3) Add the modified inorganic particles and initiator from step (1) to water, mix well, and heat and keep warm to obtain a seed emulsion-based aqueous phase system for later use.

[0010] (4) Add a portion of the pre-emulsion to the aqueous phase system of the seed emulsion and heat to react, thereby obtaining the seed emulsion. Then add the remaining pre-emulsion and continue heating to react. After the reaction is completed, add an initiator to the reaction system and continue the reaction at a constant temperature to obtain the modified fluoropropylene emulsion.

[0011] (5) After mixing the modified fluoroacrylic emulsion, mixing water, film-forming aid and dispersant, add the mixed powder formed by cement powder and filler, and then stir evenly to obtain hydrophobic cement-based coating.

[0012] Further, in step (1), the mass ratio of the inorganic nanoparticles to the aqueous superdispersant is 100:1~5.

[0013] Further, in step (1), the inorganic nanoparticles include at least one of the following: SiO2, TiO2, Fe3O4, CaCO3, ZnO, graphene, metakaolin, cellulose nanocrystals, etc.

[0014] Further, in step (1), the aqueous superdispersant includes at least one of the following: polyether modified styrene-maleic anhydride copolymer, polyoxyethylene ether type polycarboxylic acid superdispersant, polyester type polycarboxylic acid superdispersant, polyether-polyester block type polycarboxylic acid superdispersant.

[0015] Further, in step (1), the pH of the alkaline dispersion system is 7.5~9.0. Optionally, the aqueous suspension can be adjusted to alkalinity by adding any one of Tris-HCl buffer, borax-boric acid buffer, etc.

[0016] Further, in step (1), the mass ratio of the dopamine monomer, the fluorinated nucleophile, and the inorganic nanoparticles is 1~4:1~4:20.

[0017] Further, in step (1), the fluorinated nucleophile includes at least one of 1H,1H-perfluorooctylthiol, 1H,1H-perfluorooctylamine, trifluoroethylamine, etc.

[0018] Furthermore, in step (1), the reaction time after adding the dopamine monomer is 0.5~6h.

[0019] Furthermore, in step (1), the reaction continues for 2 to 12 hours after the addition of the fluorinated nucleophile.

[0020] Furthermore, in step (1), the detergent used for washing includes at least one of deionized water, anhydrous ethanol, acetone, etc.

[0021] Furthermore, in step (1), the drying temperature is 40~80℃ and the time is 6~24h.

[0022] Further, in step (2), the mass ratio of the methyl methacrylate (MMA) monomer, butyl acrylate (BA) monomer, and hexafluorobutyl methacrylate (HFMA) monomer is 10~20:5~10:1~2.

[0023] Further, in step (2), the mass ratio of the modified inorganic particles to the oil phase mixture is 0.5~2.5:1~2. The amount of water is sufficient to ensure that the modified inorganic particles and the oil phase are mixed evenly.

[0024] Furthermore, in step (2), the pre-emulsification is performed at a shear rate of 3000~5000 rpm for a time of 20~60 min.

[0025] Further, in step (3), the mass ratio of the modified inorganic particles to the initiator is 0.5~2.5:0.01~0.06. Optionally, the initiator includes at least one of potassium persulfate, ammonium persulfate, etc.

[0026] Furthermore, in step (3), the heating and heat preservation temperature is 70~80℃.

[0027] Further, in step (4), the total mass ratio of the pre-emulsion to the seed emulsion-based aqueous phase system is 2-5:1. The pre-emulsion constitutes 10-15% of the total pre-emulsion mass.

[0028] Further, in step (4), the heating reaction temperature is 70~80℃ and the time is 15~20min, thereby obtaining the seed emulsion.

[0029] Furthermore, in step (4), the continued heating reaction and the continued heat preservation reaction are both at a temperature of 70~80℃ and a time of 1~2h.

[0030] Further, in step (4), the initiator is 0.05~0.2% of the mass of the pre-emulsion. Optionally, the initiator includes at least one of potassium persulfate, ammonium persulfate, etc.

[0031] Further, in step (5), the proportions of each raw material are as follows: 30-60 parts by weight of modified fluoropropylene emulsion, 10-25 parts by weight of mixing water, 1-3 parts by weight of film-forming aid, 0.2-1 parts by weight of dispersant, and 80-120 parts by weight of mixed powder. Optionally, the mass ratio of cement powder to filler in the mixed powder is 3-4:5-6.

[0032] Further, in step (5), the cement includes at least one of silicate cement, sulfoaluminate cement, etc.

[0033] Further, in step (5), the filler includes at least one of calcium carbonate powder, mica powder, titanium dioxide, talc powder, etc. Optionally, the fineness of the filler is 200~500 mesh.

[0034] Further, in step (5), the film-forming aid includes at least one of: dodecyl alcohol ester (dodecyl alcohol ester), dipropylene glycol butyl ether, propylene glycol phenyl ether, etc.

[0035] Further, in step (5), the dispersant includes at least one of the following: polycarboxylate dispersant, sodium polyacrylate, sodium hexametaphosphate, etc.

[0036] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0037] First, this invention utilizes the spontaneous oxidative polymerization of dopamine (PDA) in an alkaline aqueous phase and the Michael addition reaction of its quinone derivatives to in-situ graft fluorinated hydrophobic segments onto the surface of inorganic nanoparticles, forming modified inorganic particles. To this end, this invention first utilizes the strong steric hindrance effect of the aforementioned aqueous superdispersant to achieve monodisperse stability of the inorganic nanoparticles in the aqueous phase, while simultaneously providing prerequisites for the homologous compatibility of the coatings and cement-based materials of this invention and the interfacial chemical bonding during the hydration process. Then, this invention utilizes the fluorinated hydrophobic segments to provide the thermodynamic driving force for the directional adsorption of inorganic nanoparticles at the water-oil interface. Through this time-series control of the aqueous superdispersant pre-intercalation – dopamine polymerization coating – fluorinated segment covalent grafting, a topological amphiphilic structure combining steric repulsion and hydrophilic-hydrophobic properties is constructed on the surface of the inorganic nanoparticles.

[0038] Furthermore, this invention utilizes an oil-phase mixture formed from methyl methacrylate monomer, butyl acrylate monomer, and hexafluorobutyl methacrylate monomer, along with the modified inorganic particles, to prepare a pre-emulsion. This achieves a completely small-molecule emulsion system, fundamentally avoiding the hydrophilic defects caused by the residue of traditional small-molecule surfactants after film formation, as well as the diffusion of water transport channels and calcium ion instability during cement hydration. This is because the topological amphiphilic nature of the modified inorganic particles forces them to the water / oil interface, where they tightly arrange themselves at the interface based on irreversible thermodynamic adsorption energy, forming a dense, rigid particle interface. Ultimately, a stable oil-in-water monomer droplet is constructed, with the oil phase as the core and the modified inorganic particles as the emulsifier shell. Simultaneously, this oil-phase core provides the sole reaction site for subsequent free radical polymerization; the polymerization reaction can only occur inside the droplet, on the oil phase side of the solid-liquid interface where the modified nanoparticles contact the monomer.

[0039] Furthermore, this invention utilizes the inherent polymerization-inhibiting effect of the catechol group in the dopamine (PDA) structure to design a thermal initiator interface pre-activation strategy, using an initiator to prepare the modified inorganic particles into a seed emulsion-based aqueous system. This is because the primary free radicals generated by the homolytic cleavage of the initiator in the aqueous phase preferentially undergo an interface quenching reaction with the phenolic hydroxyl groups on the surface of the nanoparticles, eliminating the polymerization-inhibiting groups; subsequently, large molecular active free radicals are generated in situ on the PDA molecular chain through a hydrogen extraction reaction. This "surface pre-activation" mechanism precisely anchors the primary nucleation sites of free radical polymerization in step (4) to the solid-liquid interface of the monomer droplet, effectively inhibiting homogeneous nucleation in the aqueous phase from the root, while avoiding phase separation between the polymer and the inorganic nanoparticles, ensuring that the polymerization reaction is controllable throughout the monomer droplet process.

[0040] Finally, this invention utilizes a starved semi-continuous droplet addition strategy to introduce a seed emulsion-based aqueous phase system into the pre-emulsion containing the monomers. This causes the interfacial polymerization rate of the oil-phase droplets formed by the monomers to be much greater than their diffusion rate within the droplets, forcing monomers with different polymerization rates to copolymerize at the solid-liquid interface within the droplets. The final result is the modified fluoroacrylic emulsion dispersed with latex particles consisting of a flexible organic core of polyacrylate / fluoropolymer and a rigid modified nanoparticle shell.

[0041] When using this modified fluoropolymer emulsion to prepare cement-based coatings, during the film-forming process, the outer shell can undergo strong coordination chelation with cement hydration units and synergistic cross-linking with pozzolanic hydration, forming a dense organic-inorganic composite network. Meanwhile, the fluorinated segments of the core spontaneously accumulate at the coating-air interface, forming a synergistic effect with the micro / nano rough structure constructed by nanoparticles, ultimately endowing the coating with excellent mechanical dissipation crack resistance and macroscopic superhydrophobic protective properties. Simultaneously, the high stability of this modified fluoropolymer emulsion also helps improve its compatibility with cement materials. This is because the small-molecule surfactants used in traditional emulsions react with the large number of polyvalent cations (such as Ca2+) released during cement hydration. 2+ Precipitation and demulsification easily occur in strong alkaline environments. However, the modified fluoroacrylic emulsion constructed using inorganic nanoparticles in this invention exhibits a strong steric hindrance effect, endowing the emulsion with excellent anti-electrolyte and alkali resistance, thereby avoiding demulsification and agglomeration when mixed with cement, ensuring the density and mechanical properties of the coating. Furthermore, the modified inorganic particles in the modified fluoroacrylic emulsion can also improve the microstructure roughness and mechanical properties of the polymer film, thus constructing a micro-nano rough structure similar to the surface of a lotus leaf. Combined with the extremely low surface energy of the fluoropropionic acid ester segments, the two produce a synergistic effect, significantly increasing the water contact angle of the coating surface and significantly enhancing the barrier effect of the coating against water and chloride salts and other corrosive media. Attached Figure Description

[0042] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein:

[0043] Figure 1 The image shows a sample of the modified fluoroacrylic emulsion prepared in Example 1 below.

[0044] Figure 2 The following is a graph showing the water contact angle test results of Example 1.

[0045] Figure 3 The image shows a sample of the modified fluoroacrylic emulsion prepared in Example 2 below.

[0046] Figure 4 The following is a graph showing the water contact angle test results for Example 2.

[0047] Figure 5 The image shows a sample of the modified fluoroacrylic emulsion prepared in Example 3 below.

[0048] Figure 6 The following is a graph showing the water contact angle test results for Example 3.

[0049] Figure 7The image shows a sample of the modified fluoroacrylic emulsion prepared in Comparative Example 1 below.

[0050] Figure 8 The following is a graph showing the water contact angle test results of Comparative Example 1.

[0051] Figure 9 The image shows a sample of the modified fluoroacrylic emulsion prepared in Comparative Example 2 below.

[0052] Figure 10 The following is a graph showing the water contact angle test results of Comparative Example 2.

[0053] Figure 11 The image shows a sample of the modified fluoroacrylic emulsion prepared in Comparative Example 3 below.

[0054] Figure 12 The following is a graph showing the water contact angle test results for Comparative Example 3.

[0055] Figure 13 The image below shows a commercially available fluoropropylene emulsion sample used in Comparative Example 4.

[0056] Figure 14 The following is a graph showing the water contact angle test results for Comparative Example 4.

[0057] Figure 15 The image shows a sample of the modified fluoroacrylic emulsion prepared in Comparative Example 5 below.

[0058] Figure 16 The following is a graph showing the water contact angle test results of Comparative Example 5. Detailed Implementation

[0059] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0060] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials described herein are for illustrative purposes only.

[0061] Example 1: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, comprising the following steps:

[0062] (1) A superdispersant (polyether-modified styrene-maleic anhydride copolymer, from BYK, product model: DISPERBYK-190) was added to water to form an aqueous phase system. Then, inorganic nanoparticles (nano SiO2) were added to the superdispersant at a mass ratio of 100:3, and the mixture was ultrasonically dispersed for 2 min to form a dispersion. Tris-HCl buffer was then added to the dispersion to adjust the pH to 8, resulting in an alkaline dispersion system. Dopamine monomer was added to the system and reacted for 4 hours. Then, a fluorinated nucleophile (1H,1H-perfluorooctyl thiol) was added and the reaction continued for 7 hours. The mass ratio of dopamine monomer, fluorinated nucleophile, and inorganic nanoparticles was 2:3:20. After completion, the solid product was separated by centrifugation, washed with deionized water, and dried at 60°C for 20 hours to obtain modified inorganic particles for later use.

[0063] (2) The modified inorganic particles are added to water to form a dispersed aqueous solution for later use. Methyl methacrylate monomer, butyl acrylate monomer, and hexafluorobutyl methacrylate monomer are mixed at a mass ratio of 15:8:1.5 and stirred evenly to obtain an oil phase mixture. Then, the oil phase mixture is mixed with the dispersed aqueous solution at a mass ratio of 2:1.5 and subjected to shear treatment (shear rate of 4000 rpm for 30 min) to obtain a pre-emulsion for later use.

[0064] (3) Add the modified inorganic particles from step (1) and potassium persulfate to water at a mass ratio of 2:0.035, stir evenly, heat to 75°C and maintain the temperature to obtain a seed emulsion-based aqueous phase system for later use.

[0065] (4) Take 2.5 times the mass of the pre-emulsion in the basic aqueous phase system of the seed emulsion. First, add 10% of the pre-emulsion to the basic aqueous phase system of the seed emulsion and heat to 75°C for 20 minutes with stirring to obtain the seed emulsion. Then, add the remaining pre-emulsion and continue heating at 75°C for 1.5 hours. After completion, add 0.1% of potassium persulfate (based on the total mass of the pre-emulsion) to the reaction system and keep it at 75°C for 1.5 hours to obtain the modified fluoropropylene emulsion (e.g., ...). Figure 1 (As shown), for later use.

[0066] (5) Take the following components in the following proportions: 45 parts by weight of the modified fluoroacrylic emulsion of this embodiment, 20 parts by weight of mixing water, 2.5 parts by weight of film-forming aid (dodecyl alcohol ester), 0.5 parts by weight of dispersant (sodium hexametaphosphate), and 100 parts by weight of mixed powder, wherein the mixed powder is composed of silicate cement and 350-mesh mica powder in a mass ratio of 4:6. First, mix the modified fluoroacrylic emulsion with the mixing water and stir for 2 minutes, then add the film-forming aid and dispersant and stir for 5 minutes, and finally add the mixed powder and stir for 5 minutes to obtain the polymer cement-based hydrophobic coating.

[0067] Performance testing: (1) The modified fluoroacrylic emulsion prepared in this embodiment was placed in a centrifuge tube and centrifuged at 4000 rpm for 30 min. Then, the emulsion was observed to determine whether it exhibited stratification, precipitation, flocculation, or demulsification to measure its centrifugal stability. (2) The modified fluoroacrylic emulsion prepared in this embodiment was placed in a 10% CaCl2 solution and stirred until homogeneous. After standing for 7 days, the emulsion was observed to determine whether it exhibited flocculation, stratification, or agglomeration to measure its stability in a high calcium ion environment. (3) The polymer cement-based hydrophobic coating was applied to the surface of the mold. Then, it was cured for 96 h under standard conditions (temperature (23±2)℃, relative humidity (50±5)%). After demolding, it was cured for 48 h at 40±2℃ and then cured for 4 h under standard conditions (same as above). After completion, the water contact angle of the coating was tested using an optical contact angle measuring instrument (model: JC2000D3A). Figure 2 As shown in Table 1, the hydrophobic properties of the coating were measured to evaluate its performance.

[0068] Table 1

[0069] Performance indicators Stratification Flocculation Water contact angle Test Results No layering No flocculation 136.8°

[0070] Example 2: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, comprising the following steps:

[0071] (1) A superdispersant (polyether-modified styrene-maleic anhydride copolymer, from BYK, product model: DISPERBYK-190) was added to water to form an aqueous phase system. Then, inorganic nanoparticles (nano ZnO) were added to the superdispersant at a mass ratio of 100:1, and the mixture was ultrasonically dispersed for 2 min to form a dispersion. Tris-HCl buffer was then added to the dispersion to adjust the pH to 7.5, resulting in an alkaline dispersion system. Dopamine monomer was added to the system and reacted for 6 hours. Then, a fluorinated nucleophile (trifluoroethylamine) was added and the reaction continued for 12 hours. The mass ratio of dopamine monomer, fluorinated nucleophile, and inorganic nanoparticles was 4:4:20. After completion, the solid product was separated by centrifugation, washed with deionized water, and dried at 80°C for 6 hours to obtain modified inorganic particles for later use.

[0072] (2) The modified inorganic particles are added to water to form a dispersed aqueous solution for later use. Methyl methacrylate monomer, butyl acrylate monomer, and hexafluorobutyl methacrylate monomer are mixed at a mass ratio of 10:5:1 and stirred evenly to obtain an oil phase mixture. Then, the oil phase mixture is mixed with the dispersed aqueous solution at a mass ratio of 2.5:2 and subjected to shear treatment (shear rate of 3000 rpm for 60 min) to obtain a pre-emulsion for later use.

[0073] (3) Add the modified inorganic particles from step (1) and potassium persulfate to water at a mass ratio of 0.5:0.01, stir evenly, heat to 70°C and maintain the temperature to obtain a seed emulsion-based aqueous phase system for later use.

[0074] (4) Take twice the mass of the pre-emulsion of the seed emulsion base aqueous phase system. First, add 15% of the pre-emulsion to the seed emulsion base aqueous phase system and heat to 70°C for 20 minutes with stirring to obtain the seed emulsion. Then, add the remaining pre-emulsion and continue heating at 70°C for 2 hours. After completion, add 0.05% of potassium persulfate (based on the total mass of the pre-emulsion) to the reaction system and keep it at 70°C for 2 hours to obtain the modified fluoropropylene emulsion (e.g., ...). Figure 3 (As shown), for later use.

[0075] (5) Take the following components in the following proportions: 60 parts by weight of the modified fluoroacrylic emulsion of this embodiment, 25 parts by weight of mixing water, 3 parts by weight of film-forming aid (dipropylene glycol butyl ether), 1 part by weight of dispersant (sodium hexametaphosphate), and 120 parts by weight of mixed powder, wherein the mixed powder is composed of silicate cement and 200-mesh calcium carbonate powder at a mass ratio of 3:5. First, mix the modified fluoroacrylic emulsion with the mixing water and stir for 2 minutes, then add the film-forming aid and dispersant and stir for 5 minutes, and finally add the mixed powder and stir for 5 minutes to obtain the polymer cement-based hydrophobic coating.

[0076] Performance testing: The modified fluoroacrylic emulsion and polymer cementitious hydrophobic coating prepared in this embodiment were tested using the same method as in Example 1 above. The water contact angle was tested as follows: Figure 4 As shown in Table 2 below:

[0077] Table 2

[0078] Performance indicators Stratification Flocculation Water contact angle Test Results No layering No flocculation 135.2°

[0079] Example 3: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, comprising the following steps:

[0080] (1) A superdispersant (polyether-modified styrene-maleic anhydride copolymer, from BYK, product model: DISPERBYK-190) was added to water to form an aqueous phase system. Then, inorganic nanoparticles (nano Fe3O4) were added to the superdispersant at a mass ratio of 100:5, and the mixture was ultrasonically dispersed for 3 min to form a dispersion. Borax-boric acid buffer was then added to the dispersion to adjust the pH to 9, resulting in an alkaline dispersion system. Dopamine monomer was added to the system and reacted for 0.5 hours. Then, a fluorinated nucleophile (1H,1H-perfluorooctylamine) was added and the reaction continued for 2 hours. The mass ratio of dopamine monomer, fluorinated nucleophile, and inorganic nanoparticles was 1:1:20. After completion, the solid product was separated by centrifugation, washed with deionized water, and dried at 40°C for 24 hours to obtain modified inorganic particles for later use.

[0081] (2) The modified inorganic particles are added to water to form a dispersed aqueous solution for later use. Methyl methacrylate monomer, butyl acrylate monomer, and hexafluorobutyl methacrylate monomer are mixed at a mass ratio of 20:10:2 and stirred evenly to obtain an oil phase mixture. Then, the oil phase mixture is mixed with the dispersed aqueous solution at a mass ratio of 0.5:1 and subjected to shear treatment (shear rate of 5000 rpm for 20 min) to obtain a pre-emulsion for later use.

[0082] (3) Add the modified inorganic particles from step (1) and ammonium persulfate to water at a mass ratio of 2.5:0.06, stir evenly, heat to 80°C and maintain the temperature to obtain a seed emulsion-based aqueous phase system for later use.

[0083] (4) Take 5 times the mass of the pre-emulsion in the basic aqueous phase system of the seed emulsion. First, add 15% of the pre-emulsion to the basic aqueous phase system of the seed emulsion and heat to 80°C for 15 minutes with stirring to obtain the seed emulsion. Then, add the remaining pre-emulsion and continue heating at 80°C for 1 hour. After completion, add 0.2% of the total mass of the pre-emulsion to the reaction system with ammonium persulfate and keep the reaction at 80°C for 1 hour to obtain the modified fluoropropylene emulsion (e.g., ...). Figure 5 (As shown), for later use.

[0084] (5) Take the following components in the following proportions: 30 parts by weight of the modified fluoroacrylic emulsion of this embodiment, 10 parts by weight of mixing water, 1 part by weight of film-forming aid (propylene glycol phenyl ether), 0.2 parts by weight of dispersant (sodium polyacrylate), and 80 parts by weight of mixed powder, wherein the mixed powder is made by mixing silicate cement and 500-mesh talc powder in a mass ratio of 4:5. First, mix the modified fluoroacrylic emulsion with the mixing water and stir for 2 minutes, then add the film-forming aid and dispersant and stir for 5 minutes, and finally add the mixed powder and stir for 5 minutes to obtain the polymer cement-based hydrophobic coating.

[0085] Performance testing: The modified fluoroacrylic emulsion and polymer cementitious hydrophobic coating prepared in this embodiment were tested using the same method as in Example 1 above. The water contact angle was tested as follows: Figure 6 As shown in Table 3 below:

[0086] Table 3

[0087] Performance indicators Stratification Flocculation Water contact angle Test Results No layering No flocculation 134.8°

[0088] Comparative Example 1: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, similar to Example 1 above, except that the pre-emulsion in this example is prepared using the following method: Inorganic nanoparticles (nano SiO2) without any modification are added to water to form a dispersed aqueous solution for later use. Methyl methacrylate monomer, butyl acrylate monomer, and hexafluorobutyl methacrylate monomer are mixed at a mass ratio of 15:8:1.5 and stirred evenly to obtain an oil phase mixture. Then, the oil phase mixture is mixed with the dispersed aqueous solution at a mass ratio of 2:1.5 and subjected to shear treatment (shear rate of 4000 rpm for 30 min), after which the pre-emulsion is obtained.

[0089] Performance testing: The modified fluoroacrylic emulsion prepared in this example was tested using the same method as in Example 1 above (e.g., Figure 7 As shown), the performance indicators of the polymer cement-based hydrophobic coating are as follows, including the water contact angle test results. Figure 8 As shown in Table 4 below:

[0090] Table 4

[0091] Performance indicators Stratification Flocculation Water contact angle Test Results Clearly layered Large amount of flocculation 73.2°

[0092] Comparative Example 2: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, similar to Example 1 above, except that the modified inorganic particles in this example are prepared using the following method: A superdispersant (polyether-modified styrene-maleic anhydride copolymer, from BYK, product model: DISPERBYK-190) is added to water to form an aqueous phase system. Then, inorganic nanoparticles (nano SiO2) are added to the superdispersant at a mass ratio of 100:3, and the mixture is ultrasonically dispersed for 2 minutes to form a dispersion. Tris-HCl buffer is then added to the dispersion to adjust the pH to 8, resulting in an alkaline dispersion system. Dopamine monomer is then added to the system and reacted for 4 hours, with a mass ratio of dopamine monomer to inorganic nanoparticles of 2:20. After completion, the solid product is separated by centrifugation, washed with deionized water, and dried at 60°C for 20 hours to obtain the modified inorganic particles.

[0093] Performance testing: The modified fluoroacrylic emulsion prepared in this example was tested using the same method as in Example 1 above (e.g., Figure 9 As shown), the performance indicators of the polymer cement-based hydrophobic coating are as follows, including the water contact angle test results. Figure 10 As shown in Table 5, the test results for each performance indicator are as follows:

[0094] Table 5

[0095] Performance indicators Stratification Flocculation Water contact angle Test Results Slight stratification Large amount of flocculation 62.7°

[0096] Comparative Example 3: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, similar to Example 2 above, except that the modified inorganic particles in this example are prepared using the following method: A superdispersant (polyether-modified styrene-maleic anhydride copolymer, from BYK, product model: DISPERBYK-190) is added to water to form an aqueous phase system. Then, inorganic nanoparticles (nano ZnO) are added to the superdispersant at a mass ratio of 100:1, and the mixture is ultrasonically dispersed for 2 minutes to form a dispersion. Tris-HCl buffer is then added to the dispersion to adjust the pH to 7.5, resulting in an alkaline dispersion system. A fluorinated nucleophile (trifluoroethylamine) is then added to the system and reacted for 12 hours. The mass ratio of the fluorinated nucleophile to the inorganic nanoparticles is 4:20. After completion, the solid product is separated by centrifugation, washed with deionized water, and dried at 80°C for 6 hours to obtain the modified inorganic particles.

[0097] Performance testing: The modified fluoroacrylic emulsion prepared in this example was tested using the same method as in Example 1 above (e.g., Figure 11As shown), the performance indicators of the polymer cement-based hydrophobic coating are as follows, including the water contact angle test results. Figure 12 As shown in Table 6 below, the test results for each performance indicator are as follows:

[0098] Table 6

[0099] Performance indicators Stratification Flocculation Water contact angle Test Results Slight stratification Local flocculation 93.5°

[0100] Comparative Example 4: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, comprising the following steps:

[0101] The following components are prepared: 30 parts by weight of commercially available fluoroacrylic emulsion, 10 parts by weight of mixing water, 1 part by weight of film-forming aid (propylene glycol phenyl ether), 0.2 parts by weight of dispersant (sodium polyacrylate), and 80 parts by weight of mixed powder. The mixed powder is composed of silicate cement and 500-mesh talc powder mixed at a mass ratio of 4:5. First, the commercially available fluoroacrylic emulsion is mixed with the mixing water and stirred for 2 minutes. Then, the film-forming aid and dispersant are added and stirred for 5 minutes. Finally, the mixed powder is added and stirred for 5 minutes to obtain the polymer cement-based hydrophobic coating.

[0102] Performance testing: The commercially available fluoroacrylic emulsion (e.g., [example]) of this embodiment was tested using the same method as in Example 1 above. Figure 13 As shown), the performance indicators of the polymer cement-based hydrophobic coating are as follows, including the water contact angle test results. Figure 14 As shown in Table 7 below:

[0103] Table 7

[0104] Performance indicators Stratification Flocculation Water contact angle Test Results No layering Large amount of flocculation 108.3°

[0105] Comparative Example 5: A method for preparing a polymer cement-based hydrophobic coating for marine engineering, the same as in Example 2 above, except that the modified fluoroacrylic emulsion in this example is prepared by the following method:

[0106] (1) A superdispersant (polyether-modified styrene-maleic anhydride copolymer, from BYK, product model: DISPERBYK-190) was added to water to form an aqueous phase system. Then, inorganic nanoparticles (nano ZnO) were added to the superdispersant at a mass ratio of 100:1, and the mixture was ultrasonically dispersed for 2 min to form a dispersion. Tris-HCl buffer was then added to the dispersion to adjust the pH to 7.5, resulting in an alkaline dispersion system. Dopamine monomer was added to the system and reacted for 6 hours. Then, a fluorinated nucleophile (trifluoroethylamine) was added and the reaction continued for 12 hours. The mass ratio of dopamine monomer, fluorinated nucleophile, and inorganic nanoparticles was 4:4:20. After completion, the solid product was separated by centrifugation, washed with deionized water, and dried at 80°C for 6 hours to obtain modified inorganic particles for later use.

[0107] (2) The modified inorganic particles are added to water to form a dispersed aqueous solution for later use. Methyl methacrylate monomer, butyl acrylate monomer, and hexafluorobutyl methacrylate monomer are mixed at a mass ratio of 10:5:1 and stirred evenly to obtain an oil phase mixture. Then, the oil phase mixture is mixed with the dispersed aqueous solution at a mass ratio of 2.5:2 and subjected to shear treatment (shear rate of 3000 rpm for 60 min) to obtain a pre-emulsion. The pre-emulsion is then heated to 70°C and kept at that temperature for 4 hours to obtain a modified fluoroacrylic emulsion.

[0108] Performance testing: The modified fluoroacrylic emulsion prepared in this example was tested using the same method as in Example 1 above (e.g., Figure 15 As shown), the performance indicators of the polymer cement-based hydrophobic coating are as follows, including the water contact angle test results. Figure 16 As shown in Table 8, the test results for each performance indicator are as follows:

[0109] Table 8

[0110] Performance indicators Stratification Flocculation Water contact angle Test Results Slight stratification Local flocculation 110.2°

[0111] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a marine polymer cementitious hydrophobic coating, characterized in that, Includes the following steps: (1) Inorganic nanoparticles are added to an aqueous phase system containing an aqueous superdispersant to form an aqueous suspension. The suspension is adjusted to alkaline to obtain an alkaline dispersion system. Dopamine monomer is added to the system and reacted. A fluorinated nucleophile is added to continue the reaction. After the reaction is completed, the solid product is separated, washed, and dried to obtain modified inorganic particles for later use. (2) Mix methyl methacrylate monomer, butyl acrylate monomer and hexafluorobutyl methacrylate monomer to obtain an oil phase mixture; mix it with the aqueous dispersion of the modified inorganic particles and pre-emulsify it to obtain a pre-emulsion for later use; (3) Add the modified inorganic particles and initiator from step (1) to water, mix well, heat and keep warm to obtain a seed emulsion basic aqueous phase system for later use; (4) Add a portion of the pre-emulsion to the aqueous phase system of the seed emulsion and heat to react to obtain the seed emulsion; then add the remaining pre-emulsion and continue heating to react. After the reaction is completed, add an initiator to the reaction system and continue to keep the reaction at a constant temperature to obtain the modified fluoroacrylic emulsion. (5) After mixing the modified fluoroacrylic emulsion, mixing water, film-forming aid and dispersant, add the mixed powder formed by cement powder and filler, and then stir evenly to obtain hydrophobic cement-based coating. In step (1), the mass ratio of the inorganic nanoparticles to the aqueous superdispersant is 100:1~5; the aqueous superdispersant includes at least one of the following: polyether modified styrene-maleic anhydride copolymer, polyoxyethylene ether type polycarboxylic acid superdispersant, polyester type polycarboxylic acid superdispersant, and polyether-polyester block type polycarboxylic acid superdispersant. In step (1), the mass ratio of the dopamine monomer, the fluorinated nucleophile, and the inorganic nanoparticles is 1~4:1~4:20; the fluorinated nucleophile includes at least one of 1H,1H-perfluorooctylthiol, 1H,1H-perfluorooctylamine, and trifluoroethylamine. In step (2), the mass ratio of the modified inorganic particles to the oil phase mixture is 0.5~2.5:1~2; In step (3), the mass ratio of the modified inorganic particles to the initiator is 0.5~2.5:0.01~0.06; In step (4), the total mass ratio of the pre-emulsion to the seed emulsion base aqueous system is 2-5:1; wherein, a portion of the pre-emulsion is 10-15% of the total pre-emulsion mass; In step (5), the proportions of each raw material are as follows: 30-60 parts by weight of modified fluoroacrylic emulsion, 10-25 parts by weight of mixing water, 1-3 parts by weight of film-forming aid, 0.2-1 parts by weight of dispersant, and 80-120 parts by weight of mixed powder.

2. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, characterized in that, In step (1), the inorganic nanoparticles include at least one of SiO2, TiO2, Fe3O4, CaCO3, ZnO, graphene, metakaolin, and cellulose nanocrystals.

3. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, characterized in that, In step (1), the pH of the alkaline dispersion system is 7.5 to 9.

0.

4. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, characterized in that, In step (1), the aqueous suspension is adjusted to alkalinity by adding either Tris-HCl buffer or borax-boric acid buffer.

5. The method of preparing marine polymer cementitious hydrophobic coating as claimed in claim 1, wherein, In step (1), the reaction time after adding the dopamine monomer is 0.5 to 6 hours.

6. The method of preparing marine polymer cement-based hydrophobic coating according to claim 1, characterized in that, In step (1), the reaction continues for 2 to 12 hours after the addition of the fluorinated nucleophile.

7. The method of preparing marine polymer cementitious hydrophobic coating as claimed in claim 1, wherein, In step (1), the drying temperature is 40~80℃ and the time is 6~24h.

8. The method of preparing marine polymer cement-based hydrophobic coating according to claim 1, characterized in that, In step (2), the mass ratio of methyl methacrylate monomer, butyl acrylate monomer, and hexafluorobutyl methacrylate monomer is 10~20:5~10:1~2.

9. The method of preparing marine polymer cement-based hydrophobic coating according to claim 1, characterized in that, In step (2), the pre-emulsification is performed at a shear rate of 3000~5000 rpm for 20~60 min.

10. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, characterized in that, In step (3), the initiator includes at least one of potassium persulfate and ammonium persulfate.

11. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, characterized in that, In step (3), the heating and heat preservation temperature is 70~80℃.

12. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, characterized in that, In step (4), the heating reaction is carried out at a temperature of 70-80°C for 15-20 minutes to obtain the seed emulsion.

13. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, wherein, In step (4), the continued heating reaction and the continued heat preservation reaction are both carried out at a temperature of 70~80℃ for 1~2h.

14. The method of preparing a marine polymer cementitious hydrophobic coating according to claim 1, wherein, In step (4), the initiator is 0.05 to 0.2% of the mass of the pre-emulsion.

15. The method of preparing marine polymer cementitious hydrophobic coating as claimed in claim 1 wherein, In step (4), the initiator includes at least one of potassium persulfate and ammonium persulfate.

16. The method for preparing a polymer cement-based hydrophobic coating for marine engineering according to any one of claims 1-15, characterized in that, In step (5), the mass ratio of cement powder to filler in the mixed powder is 3~4:5~6.

17. The method for preparing a polymer cement-based hydrophobic coating for marine engineering according to any one of claims 1-15, characterized in that, In step (5), the cement includes at least one of silicate cement and sulfoaluminate cement.

18. The method for preparing a polymer cement-based hydrophobic coating for marine engineering according to any one of claims 1-15, characterized in that, In step (5), the filler includes at least one of calcium carbonate powder, mica powder, titanium dioxide, and talc powder.

19. The method for preparing a polymer cement-based hydrophobic coating for marine engineering according to any one of claims 1-15, characterized in that, In step (5), the fineness of the filler is 200~500 mesh.

20. The method for preparing a polymer cement-based hydrophobic coating for marine engineering according to any one of claims 1-15, characterized in that, In step (5), the film-forming aid includes at least one of dodecyl alcohol ester, dipropylene glycol butyl ether, and propylene glycol phenyl ether.

21. The method for preparing a polymer cement-based hydrophobic coating for marine engineering according to any one of claims 1-15, characterized in that, In step (5), the dispersant includes at least one of the following: polycarboxylate dispersant, sodium polyacrylate, and sodium hexametaphosphate.

Images