Multifunctional hydrophobic and oleophobic concrete curing film agent as well as preparation method and application thereof

Abstract

The invention discloses a multifunctional hydrophobic and oleophobic concrete curing film agent as well as a preparation method and application thereof. The preparation method comprises preparation of a first-layer film agent and preparation of a second-layer film agent, the preparation of the first-layer film agent comprises the following steps: adding a polymer monomer, nano silicon dioxide, polycarboxylate, lauryl sodium sulfate, polyvinyl alcohol, a water reducing agent and an anti-ultraviolet agent into water, stirring to form an emulsion, adding an initiator under the protection of nitrogen, and carrying out a polymerization reaction to obtain the first-layer film agent; the preparation of the second-layer film agent comprises the following steps: adding a hydrophobic and oleophobic material, a silane coupling agent and a catalyst into a solvent, and uniformly stirring to obtain the second-layer film agent; the hydrophobic and oleophobic material comprises polydimethylsiloxane and polyvinylidene fluoride. The concrete curing film agent prepared by the invention has good effects of filling, permeating and repairing gaps, has multiple functions of water reduction, water resistance, oil resistance, hydrophobicity, crack prevention and the like, is durable in use stability, and effectively expands the use universality of the curing film agent.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete curing material development, and relates to a multifunctional hydrophobic and oleophobic concrete curing membrane agent, a preparation method and application thereof. Background Art

[0002] Concrete is one of the most widely used materials in modern construction and infrastructure. However, during long-term service, concrete structures are easily affected by environmental factors such as water penetration, oil erosion, ultraviolet radiation, temperature changes and mechanical wear. These factors can cause microcracks, pore expansion, spalling and strength reduction on the concrete surface, seriously affecting the durability and safety of the structure. Traditional concrete curing agents are mostly single-function-based, such as waterproofing agents, sealants or surface repair agents, which cannot simultaneously meet the multiple protection needs of concrete in complex environments. In addition, some curing materials have problems such as poor adhesion, insufficient durability, weak UV resistance, and possible release of harmful substances during construction, which limits their application in actual engineering. In recent years, the development of nanomaterials and polymer modification technology has provided new ideas for the innovation of concrete curing materials. For example, nano-SiO2 can be used to repair micropores and cracks in concrete due to its high activity and filling properties; hydrophobic and oleophobic materials such as silicone and fluorocarbon resin can form a dense protective layer on the concrete surface to improve its waterproof and oil-proof properties. However, it is still a technical challenge to integrate these functions into a curing membrane and ensure that it is easy to construct, environmentally friendly and efficient. Therefore, there is an urgent need for a multifunctional concrete curing membrane that can not only form a protective film with high water retention on the concrete surface, but also has multiple functions such as filling and repairing, hydrophobic and oil-repellent, UV resistance and crack prevention, so as to meet the higher requirements of modern engineering for the durability and safety of concrete structures. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a multifunctional hydrophobic and oleophobic concrete curing membrane agent and a preparation method and application thereof, thereby solving the technical problems in the prior art that the concrete curing agent has a single function, cannot take into account high water retention, filling and repairing, hydrophobicity and oleophobicity, UV resistance, crack prevention and has a short service life.

[0004] The present invention is achieved through the following technical solutions: A method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane, comprising the preparation of a first layer of membrane and the preparation of a second layer of membrane; The preparation of the first film agent comprises: adding 100-200 parts of a polymer monomer, 10-50 parts of nano-silicon dioxide, 1-5 parts of a polycarboxylate, 0.5-2 parts of sodium lauryl sulfate, 1-3 parts of polyvinyl alcohol, 5-15 parts of a water reducer, and 2-8 parts of an anti-ultraviolet agent to 600-900 parts of water by weight, stirring to form a uniform emulsion, adding 1-5 parts of an initiator under nitrogen protection, and performing an emulsion polymerization reaction to obtain the first film agent; The preparation of the second layer of membrane comprises: adding 50 to 100 parts of hydrophobic and oleophobic materials, 2 to 5 parts of silane coupling agents, and 0.5 to 2 parts of catalysts into 100 to 200 parts of solvents by weight, stirring and dissolving to form a uniform solution, and filtering to obtain the second layer of membrane; the hydrophobic and oleophobic materials comprise polydimethylsiloxane and polyvinylidene fluoride.

[0005] Preferably, the particle size of the nano-silicon dioxide is 10-50 nm.

[0006] Preferably, the reaction temperature of the emulsion polymerization reaction is 70-80° C. and the reaction time is 2-4 hours.

[0007] Preferably, in terms of weight parts, the polydimethylsiloxane is 30 to 60 parts, and the polyvinylidene fluoride is 20 to 40 parts.

[0008] Preferably, during the preparation of the second film layer, stirring is performed for 2 to 3 hours.

[0009] Preferably, during the preparation of the second layer of the film, a 200-mesh filter is used for filtering.

[0010] A multifunctional hydrophobic and oil-repellent concrete curing film is prepared by the above method; after drying, the curing film has a water absorption rate greater than 6%, a water contact angle greater than 100°, an oil drop contact angle greater than 100°, a sun protection factor greater than 9, and a crack area less than 400 nm 2 / m 2 .

[0011] In the application of the above-mentioned multifunctional hydrophobic and oleophobic concrete curing membrane, a first layer of the membrane is first applied to the concrete surface, and after curing, a second layer of the membrane is applied to the surface.

[0012] Preferably, the coating amount of the first layer of film is 0.2-0.5 kg / m 2 The coating amount of the second layer of film is 0.1~0.3 kg / m 2 .

[0013] Preferably, after the first layer of the membrane is applied to the concrete surface, it is cured at room temperature for 4 to 6 hours; after the second layer of the membrane is applied, it is cured at room temperature for 2 to 4 hours.

[0014] Preferably, after applying the first layer of the membrane to the concrete surface, the membrane is dried at 40-60° C. for 2-3 hours; after applying the second layer of the membrane, the membrane is dried at 40-60° C. for 1-2 hours.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: The invention discloses a method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane, which specifically includes the preparation of a first layer of membrane and a second layer of membrane. In the preparation of the first layer of membrane, polymer monomers form polymer chains in an emulsion polymerization reaction, and these polymer chains are mutually entangled and cross-linked to finally form a membrane layer with certain strength and toughness, which can deeply penetrate into the pores and micro cracks of concrete to play an effective filling and repairing role; nano silicon dioxide is used as a filler and a reinforcing agent to improve the density, hardness and wear resistance of the membrane layer, and at the same time, it can also enhance the bonding force between the membrane layer and the concrete substrate; polycarboxylate is used as a dispersant to improve the dispersibility of each component in water, prevent particle agglomeration, and make the emulsion more uniform and stable. In addition, polycarboxylate can also adjust the rheological properties of the emulsion to a certain extent, which is convenient for construction operation; sodium dodecyl sulfate is used as an emulsifier, which has excellent emulsification, dispersing and wetting properties. In the process of preparing the membrane, it can reduce the surface tension of water, promote the polymer monomer, etc. The uniform dispersion of components in water also helps the emulsion polymerization reaction; polyvinyl alcohol, as a stabilizer, can improve the stability of the emulsion and prevent the high molecular monomer from agglomerating during the polymerization process; the water reducer can reduce the content of free water in the film layer and promote the densification and hardening of the film layer; the anti-ultraviolet agent can absorb or reflect ultraviolet rays to prevent the film layer from aging and degradation due to ultraviolet radiation; under the protection of nitrogen, the initiator can initiate the emulsion polymerization reaction of the high molecular monomer, so that chemical bonds are formed between the monomer molecules, thereby generating high molecular polymers; the hydrophobic and oleophobic material is the core component of the second layer of the membrane agent, which gives the membrane layer hydrophobic and oleophobic properties. When the concrete surface is covered with this membrane agent, it can effectively prevent the penetration of water and oil stains and protect the concrete substrate from damage; the silane coupling agent can improve the film-forming properties of the membrane agent, making the membrane layer more uniform and dense, and improving the adhesion and durability of the membrane layer; the catalyst can accelerate the chemical reaction rate of each component in the second layer of the membrane agent, so that the membrane agent can cure into a film faster. In addition, the hydrophobic and oleophobic materials also effectively ensure the high elasticity and flexibility of the film, effectively alleviate the stress concentration caused by temperature changes and external forces, and prevent the generation and expansion of cracks. In addition, during the preparation of the first layer of the film, the polymer monomer is polymerized under nitrogen protection, which effectively avoids the influence of oxygen in the air on the polymerization reaction, making the polymerization product more uniform and less by-products, and improving the uniformity, density and mechanical strength of the cured film. Moreover, polydimethylsiloxane and polyvinylidene fluoride are used as hydrophobic and oleophobic materials. Under the action of the catalyst, the silicone resin and the fluorocarbon resin undergo a cross-linking reaction, so that the second layer of the film forms a dense cross-linked network structure, which accelerates the curing time during curing and ensures the mechanical stability of the film.In addition, when in use, the nano-silicon dioxide in the first layer of the membrane can form a Si-O-Si chemical bond with the silane coupling agent in the second layer of the membrane, effectively improving the bonding strength between the first layer of the membrane and the second layer of the membrane, and extending the service life of the multifunctional hydrophobic and oleophobic concrete curing membrane. In summary, the concrete curing membrane prepared by the present invention has good filling, penetration, and gap repairing effects on one hand, and at the same time, has good water reduction, waterproof, oil-proof, hydrophobic, crack prevention and other multiple functions, and has long-lasting stability in use, effectively expanding the wide range of use of the curing membrane.

[0016] Furthermore, another inventive point of the present invention is that the particle size of the nano-silicon dioxide is 10-50 nm. First, the small particle size of the nano-silicon dioxide makes it more evenly dispersed in the film agent, and can fill more tiny gaps, thereby improving the density and dense structure of the film layer, and helping to prevent the penetration of moisture and oil. In addition, the small particle size of the nano-silicon dioxide can enhance the hardness and wear resistance of the film layer, making the film layer more durable and not easy to break when subjected to external forces; at the same time, the nano effect of the nano-silicon dioxide can increase the bonding area between the nano-silicon dioxide and the concrete substrate, forming more chemical bonds and physical bonding points, thereby improving the bonding force between the film layer and the substrate, and ensuring that the film layer forms a stable and durable protective layer on the concrete surface; moreover, the particle size of 10-50 nm makes the dispersion of the nano-silicon dioxide in the film agent easier and more even, which helps to reduce the agglomeration and precipitation phenomena during the construction process, and improve the construction efficiency and quality. The addition of nano-silicon dioxide can also adjust the rheological properties of the film agent to a certain extent, making it easier to coat and shape, and meet the needs under different construction conditions.

[0017] Further, another inventive point of the present invention is that the reaction temperature of the emulsion polymerization reaction is 70-80°C and the time is 2-4h. First, the appropriate temperature range can accelerate the polymerization reaction, so that the polymerization rate between the high molecular monomers is moderate, neither too fast to cause the reaction to be difficult to control, nor too slow to cause low production efficiency. In addition, within this temperature range, the high molecular monomer can more effectively carry out chain growth reaction to generate polymers with higher molecular weight. High molecular weight polymers usually have better physical and mechanical properties and chemical stability, which helps to improve the overall performance of the film. At the same time, in the emulsion polymerization reaction, the dispersibility of the polymer has a great influence on the performance of the film. The appropriate reaction temperature and time help to form a stable and uniform emulsion system, so that the polymer particles maintain a good dispersion state in water, reduce the occurrence of agglomeration and precipitation, and help to ensure that the polymerization reaction is fully carried out, so that the product has a stable composition and uniform performance, which helps to reduce the by-products and impurities generated by incomplete or over-reaction, thereby improving the quality of the film.

[0018] Furthermore, another inventive point of the present invention is that the hydrophobic and oleophobic material includes 30 to 60 parts of polydimethylsiloxane and 20 to 40 parts of polyvinylidene fluoride. First, polydimethylsiloxane (PDMS) has extremely low surface energy and exhibits excellent hydrophobicity and oleophobicity. It can effectively prevent the penetration of water and oil stains and provide lasting protection for concrete. PDMS also has good chemical stability and weather resistance and can maintain stable performance in various harsh environments. Polyvinylidene fluoride (PVDF) also has excellent hydrophobicity and chemical corrosion resistance, as well as good thermal stability and mechanical properties, and can maintain stable performance under high temperature and mechanical stress. In the present invention, PDMS and PVDF are mixed in a certain proportion to exert the synergistic effect of the two. The excellent hydrophobicity of PDMS and the chemical corrosion resistance and thermal stability of PVDF are combined to further improve the overall performance of the membrane. This synergistic effect enables the membrane to exhibit more outstanding performance in terms of waterproofing, antifouling, weather resistance, etc., and provide more comprehensive and lasting protection for concrete.

[0019] Furthermore, another inventive point of the present invention is that in the process of preparing the second layer of film, stirring is performed for 2 to 3 hours. The stirring time can ensure that the hydrophobic and oleophobic materials, silane coupling agents, catalysts and other components are fully dissolved and evenly mixed in the solvent. By continuously stirring for 2 to 3 hours, the agglomeration and stratification between the components can be minimized, and the uniformity and stability of the solution can be improved. Sufficient stirring helps to promote contact and collision between molecules, and helps to form a more stable film solution with better performance; in addition, during the stirring process, the components in the solution are evenly dispersed, which helps to form a uniform and dense film layer in the subsequent coating or spraying process. The uniform film layer can provide better hydrophobic and oleophobic effects, while reducing the performance differences caused by uneven film thickness, and during the stirring process, the gas in the solution (such as dissolved air) will be gradually discharged, reducing the generation of bubbles in the film solution. Bubbles will form defects in the film layer, reducing the density and performance of the film layer. By fully stirring, the presence of bubbles can be minimized and the quality of the film layer can be improved.

[0020] Furthermore, another inventive point of the present invention is that in the process of preparing the second layer of film, a 200-mesh filter is used for filtering. First, the 200-mesh filter has a high filtering accuracy and can effectively remove suspended particles, impurities and incompletely dissolved solid particles in the solution. If these impurities are not filtered out, they may affect the transparency and uniformity of the film, and then affect its use effect; secondly, by filtering, pollutants such as microorganisms and dust in the solution can be further reduced, the sanitary standards of the film can be improved, and its safety and stability in subsequent use can be ensured; in addition, the filtered solution is clearer and more uniform, which helps to form a uniform and dense film layer during the coating or spraying process. The uniform film layer not only has a beautiful appearance, but also has more stable and reliable performance. In addition, the unfiltered solution may contain defects such as bubbles and particles. These defects will form pinholes, pitting and other defects in the film layer, affecting the integrity and performance of the film layer. By filtering, the generation of these defects can be significantly reduced and the quality of the film layer can be improved.

[0021] In addition, the present invention also discloses the application of a multifunctional hydrophobic and oil-repellent concrete curing membrane prepared by the above method, wherein the first layer of membrane is first applied to the concrete surface, and after curing, filling and repairing are effectively achieved, and then the second layer of membrane is applied on the surface thereof to effectively form a waterproof and oil-releasing layer. Specifically, the first layer of membrane can penetrate into the tiny cracks and pores on the concrete surface to achieve filling and repairing, thereby enhancing the flatness and density of the concrete surface, which helps to reduce the penetration of moisture and harmful substances and improve the durability of the concrete. The second layer of membrane forms a solid waterproof and oil-releasing layer on the concrete surface, effectively isolating external erosion such as moisture and oil stains, and further protecting the concrete from damage. This dual protection mechanism can significantly improve the long-term service life of the concrete. The curing membrane of the present invention can achieve a waterproof and oil-releasing effect through two layers of coating, which greatly simplifies the construction process. The membrane has a faster curing speed and can form a stable protective layer in a shorter time, thereby shortening the overall construction period.

[0022] Furthermore, another inventive point of the present invention is that the coating amount of the first layer of film is 0.2-0.5 kg / m 2 The coating amount of the second layer of film is 0.1~0.3 kg / m 2 The coating amount of the first layer of film is set at 0.2~0.5 kg / m 2 , enough to fill and repair the tiny cracks and pores on the concrete surface, forming a solid base layer. The coating amount of the second layer of membrane is controlled at 0.1~0.3 kg / m 2, a uniform and dense waterproof and oil-releasing layer can be formed on the basis of the first layer, which is neither too thick to waste materials nor too thin to affect the effect. The different coating amounts of the two layers of membrane agents cooperate with each other to jointly improve the protective ability of the concrete surface. The first layer focuses on filling and repairing, while the second layer focuses on waterproofing and oil release. The synergistic effect of the two significantly improves the durability of the concrete.

[0023] Furthermore, another inventive point of the present invention is that after the first layer of membrane is applied to the concrete surface, it is cured at room temperature for 4 to 6 hours; after the second layer of membrane is applied, it is cured at room temperature for 2 to 4 hours. Giving each layer of membrane enough curing time can ensure that the chemical substances in the membrane are fully reacted to form a stable and dense film layer, which not only improves the strength and durability of the film layer, but also helps to reduce the problems of film shedding and cracking caused by insufficient curing. Sufficient curing time helps the membrane to form a stronger bond with the concrete surface, so that the film layer is more firmly attached to the concrete surface and is not easy to peel off. The setting of curing at room temperature enables the membrane system to adapt to a wider range of environmental conditions, without the need for special heating or cooling equipment, and reduces construction costs.

[0024] Furthermore, another inventive point of the present invention is that after the first layer of membrane is applied to the concrete surface, it is dried at 40-60°C for 2-3 hours; after the second layer of membrane is applied, it is dried at 40-60°C for 1-2 hours. Here, at a higher temperature (40-60°C), the solvent in the membrane evaporates faster, and the chemical reaction rate is also increased accordingly, thereby significantly shortening the curing and drying time of the membrane layer, which helps to speed up the construction progress and improve the construction efficiency; in addition, high-temperature drying helps the chemical substances in the membrane layer to react more fully to form a more dense and uniform structure. This helps to improve the waterproof, oil-proof, and wear-resistant properties of the membrane layer. At high temperatures, bubbles and pores in the membrane layer are more easily discharged, reducing coating defects caused by bubbles and pores, such as pinholes and pitting. At the same time, in a cold or low-temperature environment, the curing and drying speed of the membrane will be significantly slowed down. By heating and drying, construction can be carried out in a low-temperature environment, which broadens the application range of the membrane. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0026] Figure 1(a) and (b) are SEM images of the surface of ordinary concrete without using a curing film at different magnifications, and (c) and (d) are SEM images of the surface of ordinary concrete after using the curing film prepared in Example 1 of the present invention at different magnifications; Figure 2 Test results of the hydrophobicity (a) and oleophobicity (b) of the surface of the protective film agent prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to understand the characteristics and effects of the present invention, the following is a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used in the text are the common meanings understood by those skilled in the art for the present invention. In the event of a conflict, the definition in this specification shall prevail.

[0028] The theories or mechanisms described and disclosed herein, whether correct or incorrect, should not limit the scope of the present invention in any way, that is, the present invention can be implemented without being limited by any specific theory or mechanism.

[0029] In this article, all features such as values, quantities, contents and concentrations defined in the form of numerical ranges or percentage ranges are for simplicity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to have included and specifically disclosed all possible secondary ranges and individual values ​​within the range (including integers and fractions).

[0030] In this document, unless otherwise specified, “includes,” “including,” “contains,” “has,” or similar terms cover the meanings of “consisting of” and “mainly consisting of,” for example, “A includes a” covers the meanings of “A includes a and other” and “A only includes a.”

[0031] In this document, in order to make the description concise, not all possible combinations of various technical features in various embodiments or examples are described. Therefore, as long as there is no contradiction in the combination of these technical features, the various technical features in various embodiments or examples can be combined arbitrarily, and all possible combinations should be considered to be within the scope of this specification.

[0032] The present invention provides a method for preparing a multifunctional hydrophobic and oleophobic concrete curing film, including the preparation of a first layer of film and the preparation of a second layer of film; The preparation of the first layer of film comprises: according to the weight parts, adding 100-200 parts of high molecular monomer, 10-50 parts of nano-silicon dioxide, 1-5 parts of polycarboxylate (as a dispersant), 0.5-2 parts of sodium dodecyl sulfate (as an emulsifier), 1-3 parts of polyvinyl alcohol (PVA, as a stabilizer), 5-15 parts of water reducer, and 2-8 parts of anti-ultraviolet agent into 600-900 parts of water, stirring to form a uniform emulsion, heating to 70-80° C. under nitrogen protection, adding 1-5 parts of initiator, and performing emulsion polymerization for 2-4 hours to obtain the first layer of film; The particle size of the nano-silicon dioxide is 10-50 nm, and the preferred particle size is 20-30 nm.

[0033] In terms of weight percentage, the polymer monomer includes 50-100 parts of methyl methacrylate (MMA), 30-70 parts of butyl acrylate (BA) and 20-30 parts of styrene (St), and the weight ratio of the three is preferably 5:3:2.

[0034] The initiator includes ammonium persulfate (APS) and azobisisobutyronitrile (AIBN) in a mass ratio of 1:1.

[0035] The water reducer is at least one of a naphthalene-based water reducer and a polycarboxylic acid-based water reducer.

[0036] The anti-ultraviolet agent is at least one of a benzophenone ultraviolet absorber (UV-531) and a hindered amine light stabilizer (HALS).

[0037] The preparation of the second layer of membrane comprises: adding 50 to 100 parts of hydrophobic and oleophobic materials, 2 to 5 parts of silane coupling agents (KH-570), and 0.5 to 2 parts of catalysts to 100 to 200 parts of solvents by weight, stirring and dissolving for 2 to 3 hours to form a uniform solution, and filtering with a 200-mesh filter to obtain the second layer of membrane.

[0038] The hydrophobic and oleophobic material includes 30 to 60 parts of polydimethylsiloxane (PDMS, a type of silicone resin) and 20 to 40 parts of polyvinylidene fluoride (PVDF, a type of fluorocarbon resin), and the preferred mass ratio is 3:2.

[0039] The solvent includes at least one of ethanol and n-butanol.

[0040] The catalyst is an organic tin compound catalyst, specifically dibutyltin dilaurate.

[0041] In addition, the present invention also discloses a multifunctional hydrophobic and oil-repellent concrete curing film prepared by the method of the present invention. After curing, the curing film has a 7d compressive strength ratio of 85% to 97%, a 28d compressive strength ratio of 90% to 95%, an effective water absorption rate of 5% to 15%, a contact angle of oil droplets on the concrete surface of >100°, a sun protection factor of >9 (SPF), and a crack area of ​​<400 nm. 2 / m 2 .

[0042] In addition, the present invention also discloses the use of the above-mentioned multifunctional hydrophobic and oleophobic concrete curing membrane agent, firstly applying a first layer of the membrane agent on the concrete surface, with a coating amount of 0.2-0.5 kg / m 2 . Naturally cure at room temperature for 4~6 hours, or dry at 40~60℃ for 2~3 hours to form a dense polymer film, which can fill, penetrate and repair gaps. After the first layer of film is cured, use a spraying device to evenly spray the second layer of film on its surface at an interval of 4~6 hours, with a spraying amount of 0.1~0.3kg / m 2 Dry naturally for 2~4 hours at room temperature, or dry for 1~2 hours at 40~60℃ to form a dense hydrophobic and oleophobic protective layer, which has the functions of reducing water, waterproofing, oil-proofing, hydrophobing and preventing crack formation.

[0043] The multifunctional hydrophobic and oleophobic concrete curing membrane of the present invention integrates multiple functions such as filling, penetration, repairing, water reduction, waterproofing, oil resistance, water repellency and crack prevention through the design of a double-layer membrane. This comprehensive solution realizes multiple protections in a single material, and solves the shortcomings of the curing agent in the prior art that the function is single and cannot fully protect the concrete structure. The durability and service life of the concrete are improved. The polymer monomer in the first layer of the membrane is combined with nano-silicon dioxide, which can penetrate deeply into the pores and micro-cracks of the concrete, playing an effective filling and repairing role. The addition of nano-SiO2 improves the mechanical strength and wear resistance of the membrane and enhances the density and strength of the concrete. The hydrophobic and oleophobic protective layer formed by the second layer of the membrane further prevents the intrusion of moisture, oil and harmful substances, delays the aging process of the concrete, and significantly extends the service life of the structure. The silicone resin and fluorocarbon resin in the second layer of the membrane have excellent waterproof, oil-proof and crack-resistant properties, which give the concrete surface excellent hydrophobic and oleophobic properties, reducing the risk of water and oil erosion on the concrete. At the same time, the high elasticity and flexibility of the membrane effectively alleviate the stress concentration caused by temperature changes and external forces, and prevent the generation and expansion of cracks. The anti-ultraviolet agent (UV-531 and HALS) added to the membrane improves the material's anti-ultraviolet ability and prevents light aging and degradation. Whether in high temperature or severe cold environment, the membrane can maintain stable physical and chemical properties and is suitable for concrete structures under various climatic conditions. The curing membrane of the present invention adopts a construction method combining coating and spraying, which is simple to operate and does not require special equipment. The first layer of the membrane can be evenly applied by rolling or brushing, and the second layer of the membrane can be sprayed using conventional spraying equipment. It is suitable for various concrete projects such as roads, bridges, tunnels, airport runways, and seaports. The selection of environmentally friendly materials reduces the emission of volatile organic compounds (VOCs) and reduces the harm to construction personnel and the environment. The material itself does not contain toxic and harmful substances, meets national environmental protection standards, and meets the requirements of green buildings. By integrating multiple functions in a single product, the use of multiple curing materials and construction steps are reduced, and the overall cost is reduced. The high durability and long-term protection ability of the film agent reduces the cost of subsequent maintenance and repair, and has good economic benefits.

[0044] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0045] The following examples use conventional instruments and equipment in the art. The experimental methods in the following examples where specific conditions are not specified are usually carried out under conventional conditions or under conditions recommended by the manufacturer. The various raw materials used in the following examples are conventional commercial products unless otherwise specified, and their specifications are conventional specifications in the art. In the specification of the present invention and the following examples, unless otherwise specified, "%" means weight percentage, "part" means weight part, and ratio means weight ratio.

[0046] Example 1 A method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane, comprising the preparation of a first layer of membrane and the preparation of a second layer of membrane; The preparation of the first layer of film is specifically as follows: Material preparation: polymer monomers: MMA (50g), BA (30g), St (20g); deionized water (800g); emulsifier SDS (2g); initiator APS (1g), AIBN (1g) dissolved in 50g deionized water; SiO2 (30g); polycarboxylate (2g); PVA (2g); deionized water (300g) for dispersion of nano-SiO2; polycarboxylate water reducer (8g); UV-531 (2g) Preparation steps: MMA, BA and St were added into the reactor in a mass ratio of 5:3:2, and 800 g of deionized water and 2 g of emulsifier SDS were added, and stirred to form a uniform emulsion.

[0047] Under nitrogen protection, the temperature was raised to 75°C, and aqueous solutions of initiators APS and AIBN were added (1g APS and 1g AIBN were dissolved in 50g deionized water), and emulsion polymerization was carried out for 3 hours to form a polymer emulsion.

[0048] Mix 30g of nano-SiO2, 2g of polycarboxylate and 2g of PVA, add 800g of deionized water, and disperse by ultrasonic for 45 minutes to form a stable nano-SiO2 dispersion. Slowly add the nano-SiO2 dispersion into the polymer emulsion, stir evenly, add 8g of polycarboxylate water reducer and anti-ultraviolet agent (2g of UV-531, 2g of HALS), continue stirring for 30 minutes, and obtain the first layer of film.

[0049] The preparation of the second layer of film is specifically as follows: PDMS (40 g), PVDF (30 g), KH-570 (3 g), dibutyltin dilaurate (1 g), ethanol (75 g), n-butanol (75 g). Add PDMS, PVDF, KH-570 and catalyst to a mixed solvent of ethanol and n-butanol, stir evenly for 2 hours to form a uniform solution. Filter with a 200-mesh filter to remove insoluble matter to obtain the second layer of membrane.

[0050] Example 2 A method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane, comprising the preparation of a first layer of membrane and the preparation of a second layer of membrane; Wherein, the preparation of the first layer of film is specifically as follows: Material preparation: polymer monomers: MMA (60g), BA (36g), St (24g), deionized water (700g), emulsifier SDS (1.5g), initiator APS (1.5g) and AIBN (1.5g) dissolved in 60g deionized water, SiO2 (40g), polycarboxylate (3g), PVA (2g); deionized water (700g) is used for the dispersion of nano-SiO2, polycarboxylate water reducer (10g), HALS (3g) Preparation steps: MMA, BA and St were added into the reactor in a mass ratio of 5:3:2, and 700 g of deionized water and 1.5 g of emulsifier SDS were added, and stirred to form a uniform emulsion.

[0051] Under nitrogen protection, the temperature was raised to 78°C, and aqueous solutions of initiators APS and AIBN were added (1.5 g of APS and 1.5 g of AIBN were dissolved in 60 g of deionized water), and emulsion polymerization was carried out for 3 hours to form a polymer emulsion.

[0052] Mix 40g of nano-SiO2, 3g of polycarboxylate and 2g of PVA, add 700g of deionized water, and disperse by ultrasonic for 50min to form a stable nano-SiO2 dispersion. Slowly add the nano-SiO2 dispersion into the polymer emulsion, stir evenly, add 8g of polycarboxylate water reducer and 3g of UV resistant agent (HALS), and continue stirring for 30min to obtain the first film.

[0053] Preparation of the second film: Raw materials: PDMS (50 g), PVDF (35 g), KH-570 (4 g), dibutyltin dilaurate (1.5 g), ethanol (90 g).

[0054] PDMS, PVDF, KH-570 and the catalyst were added to the ethanol solvent, stirred evenly for 2.5 hours to form a uniform solution, and filtered through a 200-mesh filter to remove insoluble matter to prepare the second layer of membrane.

[0055] Example 3 A method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane comprises: MMA, BA, and St were added to the reactor in a mass ratio of 5:3:2, and 900 g of deionized water and 2 g of emulsifier SDS were added, and stirred to form a uniform emulsion. Under nitrogen protection, the temperature was raised to 75°C, and an aqueous solution of initiators APS and AIBN (1 g APS and 1 g AIBN were dissolved in 50 g deionized water) was added, and the emulsion polymerization reaction was carried out for 3 hours to form a polymer emulsion.

[0056] Mix 40g of nano-SiO2, 2g of polycarboxylate and 2g of PVA, add 800g of deionized water, and disperse by ultrasonic for 45 minutes to form a stable nano-SiO2 dispersion. Slowly add the nano-SiO2 dispersion into the polymer emulsion, stir evenly, add 8g of polycarboxylate water reducer and anti-ultraviolet agent (3g of UV-531, 4g of HALS), continue stirring for 30 minutes, and obtain the first film. The rest is the same as in Example 2.

[0057] Example 4 The difference from Example 2 is that the amount of nano-SiO2 added is 45g, that is, nano-SiO2 is added to 900g of deionized water, and ultrasonic dispersion is performed for 60min to form a stable nano-SiO2 dispersion. The nano-SiO2 dispersion is slowly added to the polymer emulsion, stirred evenly, and 8g of polycarboxylic acid-based water reducer and 3g of anti-ultraviolet agent (HALS) are added, and stirring is continued for 30min to obtain the first layer of film. The rest is the same as Example 2.

[0058] Example 5 The difference from Example 2 is that the amount of nano-SiO2 added is 30g, that is, nano-SiO2 is added to 900g of deionized water, and ultrasonic dispersion is performed for 60min to form a stable nano-SiO2 dispersion. The nano-SiO2 dispersion is slowly added to the polymer emulsion, stirred evenly, and 8g of polycarboxylic acid-based water reducer and 3g of anti-ultraviolet agent (HALS) are added, and stirring is continued for 30min to obtain the first layer of film. The rest is the same as Example 2.

[0059] Figure 1 (a) and (b) are SEM images of ordinary concrete surfaces without curing membranes at different magnifications, and (c) and (d) are SEM images of ordinary concrete surfaces after using the protective film prepared in Example 1 of the present invention at different magnifications. It can be seen from the figure that the surface structure of ordinary concrete is rough and uneven, showing obvious irregularities. This texture indicates that the coating may require additional layers to ensure complete surface coverage and uniformity. At the same time, the presence of cracks and gaps indicates that the surface is porous and uneven, resulting in incomplete coverage. The surface after curing membranes has a lower magnification of 220 times and 300 times, respectively, providing a wider surface overview than the first set of images. Figure 1Compared to (a) and (b), the surface texture is smoother and more consistent, filling the gaps, making the surface more uniform and reducing the roughness in the first layer. A smoother and more protective layer is formed, indicating that the second coating significantly enhances the effectiveness of the curing membrane. This is important to ensure the hydrophobic and oleophobic protection of the concrete surface, improving its durability and resistance to environmental factors.

[0060] Figure 2 The test results of the hydrophobicity (a) and oleophobicity (b) of the protective film prepared in Example 1 of the present invention. As can be seen from the figure, the concrete curing film exhibits high hydrophobicity (125°) and oleophobicity (109°) at the same time, which means that it can protect the concrete surface from erosion by various liquids while being waterproof and oil-proof. This multifunctional property makes it very suitable for environments that need to resist water and oil pollution at the same time, such as traffic roads, industrial facilities or other building surfaces exposed to complex environments.

[0061] In order to test the performance of the multifunctional hydrophobic and oleophobic concrete curing film prepared by the present invention, the first layer of the film prepared in Examples 1 to 5 was evenly applied to the concrete surface by roller coating, and the coating amount was 0.3 kg / m 2 . Naturally cure at room temperature for 5 hours to form a dense polymer film. After the first layer of film agent is cured (5 hours interval), use a spraying device to evenly spray the second layer of film agent on its surface, with a spraying amount of 0.2 kg / m 2 . Dry naturally for 3 hours at room temperature to form a dense hydrophobic and oleophobic protective layer. After curing, the curing film was tested in accordance with the provisions of JC901-2002 "Cement Concrete Curing Agent", including 7d compressive strength ratio, 28d compressive strength ratio, waterproofness, oleophobicity, sun protection factor and crack area. The test results are shown in Table 1: Table 1 Test results of concrete curing membrane

[0062] According to the test results in Table 1, after the concrete membrane is cured by the multifunctional concrete curing membrane prepared in Examples 1 to 5, its 7d compressive strength ratio is 85% to 97%, its 28d compressive strength ratio is 90% to 95%, its effective water absorption rate is 5% to 15%, the contact angle of the oil drop on the concrete surface is measured to be >100°, the sun protection factor is >9 (SPF), and the crack area is <400 nm 2 / m 2 It is shown that the concrete curing agents prepared in Examples 1 to 5 are all first-class products. The multifunctional concrete curing membrane has excellent performance in compressive strength development, effective water absorption control, crack prevention, excellent oil resistance and good sun protection ability, which further verifies its significant effect in improving the performance and durability of concrete structures.

[0063] Example 6 A method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane, comprising the preparation of a first layer of membrane and the preparation of a second layer of membrane; The preparation of the first layer of film comprises: adding 100 parts of polymer monomer, 10 parts of nano-silicon dioxide, 1 part of polycarboxylate, 0.5 parts of sodium lauryl sulfate, 1 part of polyvinyl alcohol, 5 parts of water reducer, and 2 parts of anti-ultraviolet agent to 800 parts of water by weight, stirring to form a uniform emulsion, heating to 7° C. under nitrogen protection, adding 1 part of initiator, and performing emulsion polymerization for 4 hours to obtain the first layer of film; Wherein, the particle size of nano-silicon dioxide is 10nm.

[0064] In terms of weight percentage, the polymer monomer includes 50 parts of methyl methacrylate (MMA), 30 parts of butyl acrylate (BA) and 20 parts of styrene (St).

[0065] The initiator includes ammonium persulfate (APS) and azobisisobutyronitrile (AIBN) in a mass ratio of 1:1.

[0066] The water reducer is a naphthalene-based water reducer.

[0067] The anti-ultraviolet agent is a benzophenone ultraviolet absorber (UV-531).

[0068] The preparation of the second layer of membrane comprises: adding 50 parts of hydrophobic and oleophobic material, 2 parts of KH-570, and 0.5 parts of dibutyltin dilaurate to 100 parts of ethanol by weight, stirring and dissolving for 2 hours to form a uniform solution, and filtering with a 200-mesh filter to obtain the second layer of membrane.

[0069] The hydrophobic and oleophobic material includes 30 parts of polydimethylsiloxane and 20 parts of polyvinylidene fluoride.

[0070] In addition, this embodiment also discloses the application of the multifunctional hydrophobic and oleophobic concrete curing film prepared above. First, a first layer of the film is applied to the concrete surface, and the coating amount is 0.2 kg / m 2 , dried at 40℃ for 3h to form a dense polymer film. After the first layer of film agent is cured, the second layer of film agent is evenly sprayed on its surface using a spraying device after an interval of 4h, with a spraying amount of 0.1 kg / m 2 , dried at 40℃ for 2h to form a dense hydrophobic and oleophobic protective layer.

[0071] After curing, the 7d compressive strength ratio of the curing membrane is 85%, the 28d compressive strength ratio is 90%, the effective water absorption rate is 5%, the contact angle of the oil drop on the concrete surface is 105°, the sun protection factor is 9 (SPF), and the crack area is 395 nm. 2 / m 2 .

[0072] Example 7 A method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane, comprising the preparation of a first layer of membrane and the preparation of a second layer of membrane; The preparation of the first film agent comprises: adding 200 parts of polymer monomer, 50 parts of nano-silicon dioxide, 5 parts of polycarboxylate, 2 parts of sodium lauryl sulfate, 3 parts of polyvinyl alcohol, 15 parts of water reducer, and 8 parts of UV inhibitor into 900 parts of water by weight, stirring to form a uniform emulsion, heating to 80° C. under nitrogen protection, adding 5 parts of initiator, and performing emulsion polymerization for 2 hours to obtain the first film agent; Among them, the particle size of nano-silicon dioxide is 30nm.

[0073] In terms of weight percentage, the polymer monomer includes 100 parts of methyl methacrylate (MMA), 70 parts of butyl acrylate (BA) and 30 parts of styrene (St).

[0074] The initiator includes ammonium persulfate (APS) and azobisisobutyronitrile (AIBN) in a mass ratio of 1:1.

[0075] The water reducing agent is a polycarboxylic acid water reducing agent.

[0076] The anti-ultraviolet agent is a hindered amine light stabilizer (HALS).

[0077] The preparation of the second layer of membrane includes: adding 100 parts of hydrophobic and oleophobic material, 5 parts of KH-570, and 2 parts of dibutyltin dilaurate to 200 parts of n-butanol by weight, stirring and dissolving for 3 hours to form a uniform solution, and filtering with a 200-mesh filter to obtain the second layer of membrane.

[0078] The hydrophobic and oleophobic material includes 60 parts of polydimethylsiloxane and 40 parts of polyvinylidene fluoride.

[0079] In addition, this embodiment also discloses the application of the multifunctional hydrophobic and oleophobic concrete curing film prepared above. First, a first layer of the film is applied to the concrete surface, and the coating amount is 0.5 kg / m 2 , dried at 60℃ for 2h to form a dense polymer film. After the first layer of film agent is cured, the second layer of film agent is evenly sprayed on its surface using a spraying device at an interval of 6h, with a spraying amount of 0.3 kg / m 2, dried at 60℃ for 1h to form a dense hydrophobic and oleophobic protective layer.

[0080] After curing, the 7d compressive strength ratio of the curing membrane is 97%, the 28d compressive strength ratio is 95%, the effective water absorption rate is 15%, the contact angle of the oil drop on the concrete surface is 105°, the sun protection factor is 8 (SPF), and the crack area is 400 nm 2 / m 2 .

[0081] Example 8 A method for preparing a multifunctional hydrophobic and oleophobic concrete curing membrane, comprising the preparation of a first layer of membrane and the preparation of a second layer of membrane; The preparation of the first layer of film comprises: adding 150 parts of polymer monomer, 20 parts of nano-silicon dioxide, 3 parts of polycarboxylate, 1 part of sodium lauryl sulfate, 2 parts of polyvinyl alcohol, 10 parts of water reducer, and 6 parts of UV inhibitor into 800 parts of water by weight, stirring to form a uniform emulsion, heating to 75° C. under nitrogen protection, adding 2 parts of initiator, and performing emulsion polymerization for 3 hours to obtain the first layer of film; Wherein, the particle size of nano-silicon dioxide is 20nm.

[0082] In terms of weight percentage, the polymer monomer includes 80 parts of methyl methacrylate (MMA), 40 parts of butyl acrylate (BA) and 25 parts of styrene (St).

[0083] The initiator includes ammonium persulfate (APS) and azobisisobutyronitrile (AIBN) in a mass ratio of 1:1.

[0084] The water reducer is a naphthalene-based water reducer and a polycarboxylic acid-based water reducer.

[0085] The anti-ultraviolet agent is a benzophenone ultraviolet absorber (UV-531) and a hindered amine light stabilizer (HALS).

[0086] The preparation of the second layer of membrane comprises: adding 70 parts of hydrophobic and oleophobic material, 3 parts of KH-570, and 1 part of dibutyltin dilaurate to 150 parts of solvent by weight, stirring and dissolving for 2.5 hours to form a uniform solution, and filtering with a 200-mesh filter to obtain the second layer of membrane.

[0087] The hydrophobic and oleophobic material includes 40 parts of polydimethylsiloxane and 30 parts of polyvinylidene fluoride.

[0088] The solvents include ethanol and n-butanol.

[0089] In addition, this embodiment also discloses the application of the multifunctional hydrophobic and oleophobic concrete curing film prepared above. First, a first layer of the film is applied to the concrete surface, and the coating amount is 0.4 kg / m 2 , dried at 50℃ for 2.5h to form a dense polymer film. After the first layer of film is cured, the second layer of film is evenly sprayed on its surface using a spraying device after an interval of 5h, with a spraying amount of 0.2kg / m 2 Dry naturally for 3 hours at room temperature, or dry at 50℃ for 1.5 hours to form a dense hydrophobic and oleophobic protective layer.

[0090] After curing, the 7d compressive strength ratio of the curing membrane is 95%, the 28d compressive strength ratio is 93%, the effective water absorption rate is 10%, the contact angle of the oil drop on the concrete surface is 110°, the sun protection factor is 10 (SPF), and the crack area is 320 nm. 2 / m 2 .

[0091] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for preparing a multifunctional hydrophobic and oleophobic concrete curing film, characterized in that: The method comprises the preparation of a first film layer and the preparation of a second film layer; The preparation of the first film agent comprises: adding 100-200 parts of a polymer monomer, 10-50 parts of nano-silicon dioxide, 1-5 parts of a polycarboxylate, 0.5-2 parts of sodium lauryl sulfate, 1-3 parts of polyvinyl alcohol, 5-15 parts of a water reducer, and 2-8 parts of an anti-ultraviolet agent to 600-900 parts of water by weight, stirring to form a uniform emulsion, adding 1-5 parts of an initiator under nitrogen protection, and performing an emulsion polymerization reaction to obtain the first film agent; The preparation of the second layer of membrane comprises: adding 50 to 100 parts of hydrophobic and oleophobic materials, 2 to 5 parts of silane coupling agents, and 0.5 to 2 parts of catalysts into 100 to 200 parts of solvents by weight, stirring and dissolving to form a uniform solution, and filtering to obtain the second layer of membrane; the hydrophobic and oleophobic materials comprise polydimethylsiloxane and polyvinylidene fluoride.

2. The method for preparing a multifunctional hydrophobic and oleophobic concrete curing film according to claim 1, characterized in that: The particle size of the nano silicon dioxide is 10-50 nm.

3. The method for preparing a multifunctional hydrophobic and oleophobic concrete curing film according to claim 1, characterized in that: The reaction temperature of the emulsion polymerization reaction is 70-80° C., and the reaction time is 2-4 hours. In terms of weight percentage, the polydimethylsiloxane is 30-60 parts, and the polyvinylidene fluoride is 20-40 parts.

4. The method for preparing a multifunctional hydrophobic and oleophobic concrete curing film according to claim 1, characterized in that: During the preparation of the second film layer, stir for 2 to 3 hours.

5. The method for preparing a multifunctional hydrophobic and oleophobic concrete curing film according to claim 1, characterized in that: In the process of preparing the second layer of membrane, a 200-mesh filter was used for filtering.

6. A multifunctional hydrophobic and oleophobic concrete curing membrane, characterized in that: Prepared by the method described in any one of claims 1 to 5; after drying, the curing film has a water absorption rate greater than 6%, a water contact angle greater than 100°, an oil drop contact angle greater than 100°, a sun protection factor greater than 9, and a crack area less than 400 nm 2 / m 2 .

7. The use of a multifunctional hydrophobic and oleophobic concrete curing membrane agent as claimed in claim 6, characterized in that: First, apply the first layer of membrane agent to the concrete surface, and after curing, apply the second layer of membrane agent on its surface.

8. The use of a multifunctional hydrophobic and oleophobic concrete curing membrane according to claim 7, characterized in that: The coating amount of the first layer of film is 0.2~0.5 kg / m 2 The coating amount of the second layer of film is 0.1~0.3 kg / m 2 .

9. The use of a multifunctional hydrophobic and oleophobic concrete curing membrane according to claim 7, characterized in that: After applying the first layer of membrane agent on the concrete surface, cure it at room temperature for 4 to 6 hours; after applying the second layer of membrane agent, cure it at room temperature for 2 to 4 hours.

10. The use of a multifunctional hydrophobic and oleophobic concrete curing membrane according to claim 7, characterized in that: After applying the first layer of membrane agent on the concrete surface, dry it at 40~60℃ for 2~3h; after applying the second layer of membrane agent, dry it at 40~60℃ for 1~2h.

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