A building waterproofing material, its preparation method and film-forming method

Abstract

This invention discloses a building waterproofing material, its preparation method, and its film-forming method, relating to the field of building waterproofing technology. The invention comprises, by weight, 40-60 parts of a triblock copolymer aqueous dispersion, 8-15 parts of a self-healing active component, 5-10 parts of a penetrating crystallizer, 15-25 parts of a nanofiller, 1-3 parts of a dispersant, 0.3-1.0 parts of a defoamer, 0.2-0.8 parts of a leveling agent, 0.3-1.2 parts of a thickener, and 5-15 parts of deionized water; wherein the triblock copolymer aqueous dispersion comprises a triblock copolymer formed by the sequential linkage of A-block, B-block, and C-block; it solves the problems of existing building waterproofing materials in terms of crack resistance, self-healing ability, durability, and construction adaptability.

Description

Technical Field

[0001] This invention relates to the field of building waterproofing technology, specifically to a building waterproofing material, its preparation method, and its film-forming method. Background Technology

[0002] In the field of building waterproofing engineering, especially for concrete structures such as basements, tunnels, and pipe galleries that are subjected to high water pressure and deformation conditions for extended periods, extremely stringent requirements are placed on the performance of waterproofing materials. Traditional waterproofing materials, such as polymer-modified cement-based coatings, acrylic elastic coatings, and penetrating crystalline materials, generally face a series of persistent challenges in practical applications.

[0003] First, the core issue is the insufficient crack resistance and durability of the materials. Concrete substrates are prone to microcracks due to temperature changes, drying shrinkage, or loads, while traditional waterproofing material layers often have limited toughness and cannot effectively follow the deformation of the substrate, leading to cracking of the coating itself and the formation of seepage channels. Once cracks appear, ordinary materials lack self-repair capabilities, and the leakage points will continue to expand, requiring external repairs, which are costly and difficult to eradicate completely. Second, existing self-healing technologies have significant limitations. For example, microencapsulation technology relies on the uniformity of capsule dispersion and the timing of rupture, resulting in limited repair capacity and difficulty in responding to repeated cracking; while penetrating crystallizing materials can generate repair crystals, the reaction speed is slow and the repair depth is shallow, making the repair effect on wider cracks (such as those greater than 0.3 mm) unsatisfactory, and the recovery rate of impermeability pressure after repair is often low.

[0004] Furthermore, the long-term performance degradation of materials is significant. Under complex environments such as prolonged immersion in water, freeze-thaw cycles, and acid / alkali corrosion, the tensile strength, adhesion, and elongation of traditional materials will decrease substantially, and their actual service life is often far below the designed 15-20 year requirement, leading to frequent renovations and maintenance. In addition, construction adaptability is also a major constraint. Many high-performance materials have strict requirements for the dryness of the substrate and the ambient temperature and humidity. When applied to damp substrates or in low-temperature environments, their bonding reliability will be significantly reduced, affecting the overall integrity of the waterproofing system. Summary of the Invention

[0005] The purpose of this invention is to provide a building waterproofing material, a preparation method, and a film-forming method, so as to solve the problems of existing building waterproofing materials in terms of crack resistance, self-healing ability, durability, and construction adaptability.

[0006] To solve the above problems, the present invention employs the following technical means: A building waterproofing material, by weight, comprises 40-60 parts of a triblock copolymer aqueous dispersion, 8-15 parts of a self-healing active component, 5-10 parts of a penetrating crystallizer, 15-25 parts of a nanofiller, 1-3 parts of a dispersant, 0.3-1.0 parts of a defoamer, 0.2-0.8 parts of a leveling agent, 0.3-1.2 parts of a thickener, and 5-15 parts of deionized water; The triblock copolymer aqueous dispersion comprises a triblock copolymer formed by sequentially connecting A block, B block and C block.

[0007] Preferably, the A block is a copolymer segment of butyl acrylate and isooctyl acrylate.

[0008] Furthermore, the B block is a polyethylene glycol segment, and the molecular weight of the polyethylene glycol is 1000~2000.

[0009] Furthermore, the C block is a polymer segment containing disulfide bonds or borate ester bonds.

[0010] In this way, the copolymer segments of butyl acrylate and isooctyl acrylate in block A serve as a highly elastic continuous phase, ensuring that the polymer matrix has a low glass transition temperature and high elongation. The polyethylene glycol in block B, with a molecular weight of 1000-2000, acts as a phase change buffer unit, connected to block A by chemical bonds. By controlling the length and grafting density of the polyethylene glycol segments, it can undergo an effective phase change without forming large-area crystalline regions that would damage the overall flexibility of the matrix. The polymer segments in block C, containing disulfide bonds or borate ester bonds, act as moisture-responsive shape memory units. In the dry state, they form a "stationary phase," and upon contact with water, the dynamic bonds reversibly open, causing the modulus of the water-contaminated region to drop sharply, thereby restoring the shape under the drive of entropy elasticity stored internally.

[0011] Through living polymerization, the A-block is ensured to dominate, providing a continuous phase and bulk elasticity. The B and C blocks are chemically bonded to the main chain, but their lengths and proportions are strictly controlled, resulting in dispersed, size-constrained functional microdomains. The crystallization of polyethylene glycol is confined within these nanodomains, minimizing the interference of its melt-crystallization behavior on the overall chain segment movement. The physical crosslinking points formed by the C-block through dynamic bonds are dispersed, rather than continuous, rigid phases, thus introducing phase change buffering and shape memory effects while maintaining the material's high elasticity.

[0012] Specifically, the dynamic disulfide bonds or borate ester bonds in the C-block can specifically respond to the intrusion of water molecules. The intrusion of water molecules reversibly opens the dynamic bonds, causing the modulus of the C-block microregion to decrease sharply and selectively at the crack, thereby releasing the stored elastic deformation energy and driving the crack to close. This achieves a shape memory effect triggered by the leakage water itself without the need for an external heat source.

[0013] Furthermore, by setting a specific matrix, the effects of active crack suppression and active crack closure can be achieved.

[0014] Furthermore, the nanofiller comprises nano-silica and nano-calcium carbonate, wherein the nanofiller is made of nanoparticles that have been surface modified with a silane coupling agent.

[0015] In this way, the nanofiller can be uniformly dispersed in the aforementioned film-forming matrix. During the temperature-programmed film formation process, the nanofiller migrates and anchors at the phase interface between the A-block and B / C-block microregions. This increases the interaction forces at the phase interface, stabilizes the microscopic phase separation structure, and makes the final elastic / phase transition / memory interpenetrating network denser and more robust.

[0016] Moreover, when using nano-calcium carbonate, it can act as a heterogeneous nucleating agent in the B-block crystallization process, which refines the crystal size of polyethylene glycol during programmed temperature film formation, resulting in more efficient stress buffering capacity and smaller property fluctuations.

[0017] Furthermore, a method for preparing the aforementioned building waterproofing material includes the following steps: The penetrating crystallizer, nanofiller, dispersant and a portion of deionized water are mixed and dispersed at high speed to obtain a first mixture; Add the triblock copolymer aqueous dispersion to the first mixture and stir at medium speed to obtain a second mixture; Add the self-healing active component, defoamer, and leveling agent to the second mixture and stir at low speed; Add the thickener to the material after low-speed stirring to adjust the viscosity; The material after viscosity adjustment is filtered and degassed.

[0018] Preferably, the high-speed dispersion is performed at a speed of 800-1000 rpm for 20 minutes; the medium-speed stirring is performed at a speed of 400-600 rpm for 15 minutes; and the low-speed stirring is performed at a speed of 200-300 rpm for 15 minutes.

[0019] Furthermore, a film-forming method, using the aforementioned building waterproofing material to form a waterproof coating, includes the following steps: The building waterproofing material is coated onto the surface of the substrate to form a wet film; The wet film is initially dried at 20~30℃; In this step, which is the first stage of film formation, water evaporates rapidly, and the chain segments are relaxed, allowing the film-forming matrix to move closer together, accumulate, and deform.

[0020] The pre-dried coating is heated from 20-30°C to 45-55°C at a rate of 0.5-2°C / min. In this step, as the second stage of film formation, phase separation and polyethylene glycol crystallization are induced by programmed temperature increase.

[0021] During the programmed heating process, the hydrophobic A-blocks aggregate together, while the hydrophilic B-blocks and polar C-blocks also aggregate individually. The crystallization of the B-blocks during heating serves as the driving force for self-assembly, pulling the A-blocks and C-blocks together, thus aligning them within the amorphous cross-section of the B-blocks.

[0022] Furthermore, during the programmed heating process, as moisture evaporates and polymer chain segments move, the added nanofillers undergo directional migration driven by the phase separation of different polymer blocks. This leads to their enrichment at the phase interface between block A and blocks B / C. Consequently, the nanoparticles are positioned at key nodes of the interpenetrating network, stabilizing the phase interface, refining the functional microregions, and achieving phase transformation stress buffering and shape memory recovery effects.

[0023] Finally, in the third stage, the coating is cured at 60~70°C.

[0024] During this stage, the dynamic covalent bonds in the C-blocks are completely removed and reorganized and strengthened under thermal drive, forming a robust physical cross-linking network within the C-block aggregated microregions and at the interface between the microregions and the A phase. Ultimately, the A-blocks form a continuous, elastic matrix; the B-blocks are dispersed within it as microcrystalline bundles; and the C-blocks exist as microregions rich in physical cross-linking points. The B-blocks and C-blocks partially interpenetrate and entangle in space, forming a stable structure of a semi-interpenetrating / partially interpenetrating network.

[0025] Preferably, the temperature rise rate is 1°C / minute.

[0026] Furthermore, the final curing time is 1 to 2 hours.

[0027] The present invention has the following beneficial effects when applied: The polyethylene glycol microcrystalline regions dispersed in the coating undergo a reversible crystallization-melting phase transition when the ambient temperature changes, effectively absorbing and buffering the internal stress caused by thermal expansion and contraction, and significantly inhibiting the initiation of microcracks from the source. When moisture seeps in through the cracks, the C-block microregions containing dynamic covalent bonds soften upon contact with water, reducing their modulus. Driven by internal entropy elasticity, they generate shrinkage recovery force, which is transferred to the entire polymer network through chemical bonds. This actively drives the materials on both sides of the microcrack to move closer together, achieving physical narrowing or closure of the crack. After the crack is physically narrowed, a more favorable narrow space is created for the chemical reaction between the self-healing active components and the penetrating crystallizing agent. The two can generate a repair more quickly and thoroughly, achieving the dual effects of physical closure and chemical healing, which greatly improves the repair efficiency and repair strength. Furthermore, through a programmed temperature film-forming process, the triblock copolymer is guided to undergo microphase separation, ultimately forming an interpenetrating network structure with the A-block as the continuous elastic phase, the crystalline phase B-block, and the physically cross-linked phase C-block as the dispersed phase. By integrating elasticity, phase transition, and memory functions at the nanoscale, the material maintains high elongation and flexibility while also possessing rapid response characteristics. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0029] Therefore, the following detailed description of embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0030] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other.

[0031] An aqueous dispersion of a triblock copolymer was prepared.

[0032] The first step is to synthesize a polyethylene glycol macromolecular chain transfer agent; The monohydroxy polyethylene glycol was esterified with a RAFT chain transfer agent in the presence of a dehydrating agent and a catalyst at low temperature under an inert atmosphere. In this embodiment, the RAFT chain transfer agent was a compound containing a carboxylic acid and a dithioester structure; the dehydrating agent was dicyclohexylcarbodiimide; the catalyst was 4-dimethylaminopyridine; and the esterification reaction was carried out at 0–5 °C.

[0033] After the esterification reaction was completed, the product was purified to obtain a polyethylene glycol macromolecular chain transfer agent with RAFT dithioester end groups, which was used as a B-block precursor and chain transfer agent for subsequent polymerization.

[0034] The second step involves using a polyethylene glycol macromolecular chain transfer agent with RAFT disulfide end groups as an initiator to synthesize a polyethylene glycol-b-polybutyl acrylate diblock copolymer. A polyethylene glycol macromolecular chain transfer agent with RAFT disulfide end group, butyl acrylate, functional monomer acrylic acid, and initiator azobisisobutyronitrile were dissolved in the solvent 1,4-dioxane.

[0035] Under an inert atmosphere, the temperature was raised to 70-80℃ for RAFT solution polymerization. The length of the target polybutyl acrylate block was controlled by adjusting the molar ratio of butyl acrylate monomer to polyethylene glycol-RAFT.

[0036] After reaching the predetermined conversion rate, the reaction was terminated by cooling in an ice bath. The product was precipitated by adding it dropwise to methanol / water, filtered, washed, and dried to obtain a polyethylene glycol-b-polybutyl acrylate diblock copolymer. Its structure is polybutyl acrylate block-RAFT end group-polyethylene glycol block.

[0037] The third step is to synthesize triblock copolymers using diblock copolymers as macromolecular chain transfer agents. The polyethylene glycol-b-polybutyl acrylate diblock copolymer obtained in the second step is used as a macromolecular chain transfer agent, and a shape memory hard segment monomer is selected, in this embodiment, either bis(2-methacryloyloxyethyl) disulfide or methacrylate monomer. After mixing, N,N-dimethylformamide solvent and an initiator are added; in this embodiment, azobisisobutyronitrile is selected as the initiator.

[0038] After mixing, the reaction is carried out again in an inert atmosphere at 70-80°C. The molecular weight of the C-block is controlled by the feed ratio. The C-block should not be too long to avoid forming an excessively rigid phase that would compromise the overall flexibility of the material.

[0039] After the reaction was completed, the final triblock copolymer was obtained by precipitation, washing and drying.

[0040] The fourth step is to prepare the aqueous emulsion; The synthesized triblock copolymer was dissolved in acetone, and triethylamine was added to neutralize the carboxyl groups on the polymer chain.

[0041] Under high-speed shear stirring, the above solution was slowly added to deionized water to form an oil-in-water crude emulsion. Then, acetone was completely removed by vacuum distillation to obtain a stable and dispersed triblock copolymer aqueous emulsion with a solid content of approximately 40-50%.

[0042] Subsequently, waterproof materials are prepared: The penetrating crystallizer, nanofiller, dispersant and a portion of deionized water are mixed and dispersed at high speed at 800-1000 r / min for 20 minutes to form a uniform slurry.

[0043] Add the triblock copolymer emulsion to the above slurry and stir at a medium speed of 400-600 r / min for 15 minutes until homogeneous.

[0044] Add the self-healing active component, defoamer, and leveling agent, and stir at low speed for 15 minutes at 200-300 r / min. In this embodiment, the self-healing active component is active silicate.

[0045] Add a thickening agent to adjust the viscosity to the application viscosity.

[0046] Finally, it is filtered through a 100-mesh sieve, vacuum degassed, and then sealed and packaged.

[0047] In addition, the following methods are used to form the film during the film-forming process: The material is coated onto the substrate.

[0048] Then, the process involves temperature-controlled curing. In the first stage, some moisture is evaporated at 20~30℃, causing latex particles to accumulate. Chain segment relaxation is carried out in this stage.

[0049] In the second stage, the temperature is slowly increased to 50°C at a rate of 1°C / min. This process provides kinetic energy to the polymer chain segments, driving microphase separation of the A, B, and C triblocks. At the same time, the B block crystallizes in an orderly manner, initially forming microregions.

[0050] In the third stage, the temperature is further increased to 60-70℃ and held for 1-2 hours. During this stage, the moisture is completely removed, and the dynamic covalent bonds or strongly polar groups in the C-blocks recombine and strengthen under thermal drive, forming a stable physical cross-linked network.

[0051] Finally, a stable network structure with locally interpenetrating segments is formed, where segment A is the continuous elastic phase and segments B and C are the dispersed phases.

[0052] The following detailed description is based on specific embodiments. Example 1

[0053] The composition includes: 50 parts of an aqueous dispersion of a triblock copolymer with a molecular weight of 1500 and C-blocks containing dynamic disulfide bonds; 12 parts of a self-healing active component of a silicate-based crystallizing catalyst; 8 parts of an active sodium silicate penetrating crystallizer; 20 parts of nano-SiO2 and nano-CaCO3 modified with silane coupling agent; 2.5 parts of a nanofiller in a 1:1 mass ratio; 2.5 parts of an auxiliary agent system consisting of dispersant, defoamer, leveling agent, and thickener; and 7.5 parts of deionized water.

[0054] The test sample was prepared according to the preparation method described in the foregoing embodiment, and the film was formed by a programmed temperature rise process of initial drying at 25°C, increasing to 50°C at 1°C / min, and then curing at 65°C for 1.5 hours. Example 2

[0055] In this embodiment, the amount of the triblock copolymer dispersion from Example 1 is 45 parts, the self-healing active component is 10 parts, the nanofiller is 18 parts, and the deionized water is 12 parts. The remaining components are the same as in Example 1.

[0056] The preparation method and film formation method are the same as in Example 1. Example 3

[0057] In this embodiment, the molecular weight of the polyethylene glycol blocks in the triblock copolymer dispersion of Example 1 was adjusted to 2000, and the amount of the triblock copolymer dispersion was 55 parts, the self-healing active component was 10 parts, the nanofiller was 18 parts, and the deionized water was 12 parts. The remaining components were the same as in Example 1.

[0058] The preparation method and film formation method are the same as in Example 1.

[0059] Comparative Example 1 A conventional high-elasticity polymer waterproof coating is formed by using 50 parts of ordinary styrene-acrylic emulsion, 30 parts of 600-mesh heavy calcium carbonate filler, 3 parts of functional additives formed by conventional dispersing, defoaming and film-forming aids, and 17 parts of deionized water.

[0060] Comparative Example 2 It uses a commercially available rigid penetrating crystalline waterproofing material made of 70 parts Portland cement, 25 parts 100-200 mesh quartz sand, 5 parts conventional penetrating crystallization catalyst, and 25 parts water.

[0061] Comparative Example 3 The triblock copolymer dispersion in Example 1 was replaced with a polyethylene glycol-acrylate diblock copolymer dispersion without C blocks, with the same polyethylene glycol block molecular weight and content as in Example 1. The remaining components and amounts were exactly the same as in Example 1.

[0062] The film preparation process is the same as in Example 1, but since it does not contain the thermally crosslinked C block, the final curing temperature is adjusted to 50°C and held for 1 hour.

[0063] Comparative Example 4 The triblock copolymer dispersion in Example 1 was replaced with an acrylate-shape memory diblock copolymer dispersion without B blocks. The initial glass transition temperature was adjusted to be close to that of Example 1 by adjusting the proportion of soft segment monomers. The remaining components and amounts were exactly the same as in Example 1.

[0064] The preparation and film-forming process are the same as in Example 1.

[0065] Comparative Example 5 use: 45 parts of ordinary high-elastic acrylate emulsion, paraffin as the core material, 5 parts of phase change microcapsules with a phase change temperature of 20°C, 5 parts of moisture-responsive polyurethane as shape memory polymer powder with a particle size of less than 50 μm, and the remaining components such as self-healing active components, penetrating crystallizers, and nanofillers are the same as in Example 1.

[0066] The preparation and film-forming process involves simple mechanical mixing of all components and drying at room temperature to form a film.

[0067] The test results for the aforementioned embodiments and comparative examples are shown in the table below: Initial osmotic pressure resistance / MPa 1.35 1.28 1.4 0.42 0.75 1.2 1.25 0.9 Repairable crack width / mm 0.5 0.45 0.5 Unrepairable 0.2 0.3 0.4 0.25 24-hour visual restoration rate / % 95 92 94 0 48 70 85 55 Permeability retention rate after repair / % 102 98 101 - 65 82 88 70 Thermal stress cracking temperature range / ℃ -30~70 -28~65 -30~72 -10~50 -5~60 -25~65 -20~60 -15~55 -30℃ low temperature bending resistance No cracks No cracks No cracks cracking cracking No cracks minor cracks cracking Tensile strength / MPa 2.85 2.6 2.9 1.65 1.25 2.4 2.5 1.8 Elongation at break / % 680 650 670 380 85 600 620 350 Adhesion strength on damp substrate / MPa 1.4 1.3 1.45 0.72 0.65 1.1 1.2 0.85 The results show that the pressure retention rate after repair in Comparative Example 3 was significantly lower than that in Example 1, indicating the lack of active crack-sealing function, making it difficult for chemical repair to achieve a perfect interface. Comparative Example 4 showed a narrower thermal stress cracking temperature range and the appearance of cracks at low temperatures, indicating that active stress buffering is crucial for maintaining durability. Both products outperformed the traditional products in Comparative Examples 1 and 2, but neither reached the level of Example 1.

[0068] In Example 1, by chemically bonding polyethylene glycol phase change (B-block) and shape memory (C-block) to an elastic network (A-block) and constructing an interpenetrating network structure, the material maintains ultra-high elasticity while also possessing active crack suppression and active crack closure functions.

[0069] Compared with Example 1, Comparative Example 5 showed a significant lag in all performance indicators. The simple addition of phase change microcapsules and shape memory powder not only failed to achieve active functionality but also became a defect due to poor interfacial compatibility, damaging the material's mechanical properties, impermeability, and repair effect.

[0070] This application utilizes a unique process involving the synthesis of triblock copolymers and the induction of interpenetrating network structures through temperature-programmed induction to precisely position surface-modified nanofillers at the polymer phase interface. This allows the nanofillers to simultaneously perform a triple function: stabilizing the interpenetrating network structure, refining the polyethylene glycol crystalline regions, and enhancing the repair.

[0071] 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 building waterproofing material, characterized in that, The product comprises, by weight, 40-60 parts of a triblock copolymer aqueous dispersion, 8-15 parts of a self-healing active component, 5-10 parts of a penetrating crystallizer, 15-25 parts of a nanofiller, 1-3 parts of a dispersant, 0.3-1.0 parts of a defoamer, 0.2-0.8 parts of a leveling agent, 0.3-1.2 parts of a thickener, and 5-15 parts of deionized water; The triblock copolymer aqueous dispersion comprises a triblock copolymer formed by sequentially connecting A block, B block and C block.

2. The building waterproofing material according to claim 1, characterized in that, The A block is a copolymer segment of butyl acrylate and isooctyl acrylate.

3. The building waterproofing material according to claim 1, characterized in that, The B block is a polyethylene glycol segment, and the molecular weight of the polyethylene glycol is 1000~2000.

4. The building waterproofing material according to claim 1, characterized in that, The C-block is a polymer chain segment containing disulfide bonds or borate ester bonds.

5. The building waterproofing material according to claim 1, characterized in that, The nanofiller comprises nano-silica and nano-calcium carbonate.

6. A method for preparing a building waterproofing material according to any one of claims 1 to 5, characterized in that, Includes the following steps: The penetrating crystallizer, nanofiller, dispersant and a portion of deionized water are mixed and dispersed at high speed to obtain a first mixture; Add the triblock copolymer aqueous dispersion to the first mixture and stir at medium speed to obtain a second mixture; Add the self-healing active component, defoamer, and leveling agent to the second mixture and stir at low speed; Add the thickener to the material after low-speed stirring to adjust the viscosity; The material after viscosity adjustment is filtered and degassed.

7. The preparation method according to claim 6, characterized in that, The high-speed dispersion operates at a rotation speed of 800-1000 rpm for 20 minutes; the medium-speed stirring operates at a rotation speed of 400-600 rpm for 15 minutes; and the low-speed stirring operates at a rotation speed of 200-300 rpm for 15 minutes.

8. A film-forming method, characterized in that, Forming a waterproof coating using the building waterproofing material according to any one of claims 1 to 5 includes the following steps: The building waterproofing material is coated onto the surface of the substrate to form a wet film; The wet film is initially dried at 20~30℃; The pre-dried coating is heated from 20-30°C to 45-55°C at a rate of 0.5-2°C / min. The coating is then cured at 60-70°C.

9. The film-forming method according to claim 8, characterized in that, The temperature rise rate of the program is 1°C / minute.

10. The film-forming method according to claim 8, characterized in that, The final curing time is 1 to 2 hours.