Long-acting durable waterproof coating with self-repairing function and synthesis method thereof

Abstract

The invention discloses a long-acting durable waterproof paint with a self-repairing function and a synthesis method thereof, and relates to the technical field of waterproof paints.The long-acting durable waterproof paint is prepared from self-repairing matrix resin, a bi-component microcapsule self-repairing agent, a fluorine-silicon modified waterproof agent, a nano reinforcing filler and a weather-proof additive; through the synergistic effect of a dynamic disulfide bond and an interpenetrating network, the balance of molecular-level self-repairing and macroscopic mechanical properties is achieved, the efficiency bottleneck of single-component self-repairing is broken through through a two-component microcapsule system, a three-dimensional cross-linked structure of the fluorosilicone modifier endows the super-amphiphobic property, meanwhile, the hydrophobic and oleophobic properties are achieved, and the self-repairing effect is good. In addition, a multi-scale reinforcing system is constructed through the gradient nano filler, so that the crack growth needs to consume higher energy, and finally, the integrity of the microcapsule and the accurate control of the crosslinking degree of the resin are ensured through a specific curing process in the synthesis process, so that the waterproof coating finished product has excellent self-repairing capability, weather resistance and waterproof performance.

Description

Technical Field

[0001] The present invention relates to the technical field of waterproof coatings, and in particular to a long-lasting and durable waterproof coating with a self-repairing function and a synthesis method thereof. Background Art

[0002] Paint refers to a thin film material that is applied to the surface of an object and forms a layer of film with protective, decorative or other special functions (such as anti-corrosion, waterproofing, rust prevention, insulation, etc.) after drying or curing. It is usually made of raw materials such as film-forming substances (resins / base materials), pigments, solvents and additives. Common types include wall latex paint, wood paint, metal anti-rust paint, car paint, artistic paint, etc.

[0003] Waterproof coating is a special coating designed to prevent water penetration. It protects substrates (such as walls, roofs, basements, etc.) from water erosion by forming a dense, continuous waterproof membrane. Its main types include polyurethane waterproof coating, JS polymer cement-based, acrylic waterproof coating and asphalt-based coating, etc., which are widely used in the construction field, engineering field and home scenes.

[0004] Most existing waterproof coatings have a single component, are prone to cracking and failure, and have insufficient durability. Cracks that open can easily cause leakage. The coating itself lacks self-repairing ability and is affected by ultraviolet rays / humidity and heat, which can accelerate aging. It has poor weather resistance and insufficient tensile strength, resulting in weak mechanical properties of the coating itself. In addition, the construction is complex and requires multiple layers of coating, which makes it difficult to meet the long-term protection needs of extreme environments. Therefore, the present invention proposes a long-lasting and durable waterproof coating with self-repairing function and a synthesis method thereof to solve the problems existing in the prior art. Summary of the Invention

[0005] In response to the above problems, the purpose of the present invention is to propose a long-lasting and durable waterproof coating with self-repairing function and a synthesis method thereof, so as to solve the problems of existing waterproof coatings such as insufficient durability, lack of self-repairing ability, poor weather resistance and weak mechanical properties.

[0006] In order to achieve the purpose of the present invention, the present invention is implemented through the following technical scheme: a long-lasting and durable waterproof coating with self-repairing function, comprising the following raw materials in parts by weight: 50 to 70 parts of self-repairing matrix resin, 8 to 15 parts of two-component microcapsule self-repairing agent, 12 to 18 parts of fluorosilicone modified waterproofing agent, 10 to 20 parts of nano-reinforced filler and 3 to 6 parts of weathering additive; the self-repairing matrix resin is a polyurethane-epoxy interpenetrating network polymer containing dynamic disulfide bonds, and the two-component microcapsule self-repairing agent is composed of a mixture of type A microcapsules encapsulating isocyanate curing agent HDI trimer and type B microcapsules encapsulating epoxy resin prepolymer, and the mixing mass ratio of type A microcapsules to type B microcapsules is 1:1.2 to 1.5.

[0007] A further improvement is that the dynamic disulfide bond is introduced by adding 4,4'-disulfadiphenylamine as a chain extender during the polyurethane prepolymer synthesis stage, wherein the 4,4'-disulfadiphenylamine accounts for 2.5-4.0% of the total mass of the resin to form a reversible cross-linked network structure.

[0008] A further improvement is that the fluorosilicone modified waterproofing agent is prepared by RAFT polymerization of perfluoroalkylethyl acrylate and γ-methacryloxypropyltrimethoxysilane, and the molar ratio of the fluorosilicone segments is 3 to 5:1.

[0009] A further improvement is that the nano-reinforced filler is a three-dimensional gradient structure composite modified by a silane coupling agent, and is made of flaky boron nitride, porous silica nanospheres and carbon fiber chopped strands in a mass ratio of 40-60%: 20-30wt%: 20-30wt%. The flaky boron nitride, porous silica nanospheres and carbon fiber chopped strands form a three-dimensional interpenetrating network in a high-speed vortex field.

[0010] A further improvement is that the method for preparing the three-dimensional gradient structure complex comprises the following steps:

[0011] S1, first oxidize the carbon fiber chopped strands in concentrated nitric acid for 2 hours to form a surface carboxyl material;

[0012] S2, coating the surface of the boron nitride sheet with a porous silicon dioxide layer by an alternating deposition method;

[0013] S3. Then, the modified carbon fiber and the sheet-like composite form a spatial network structure through electrostatic self-assembly.

[0014] A further improvement is that the weathering agent is composed of a mixture of ultraviolet absorber, antioxidant, light stabilizer and heat stabilizer, and the mixing mass ratio of the ultraviolet absorber, antioxidant, light stabilizer and heat stabilizer is 0.8-1.5:1.2-2.0:0.5-1.0:0.5-1.5.

[0015] A method for synthesizing a long-lasting and durable waterproof coating with a self-repairing function comprises the following steps:

[0016] Step 1: Shear and disperse the self-repairing matrix resin and the fluorosilicone modified waterproofing agent under vacuum conditions;

[0017] Step 2: Add nano-reinforced fillers in three equal amounts and simultaneously apply pulsed ultrasound to evenly disperse the nano-fillers in the coating;

[0018] Step 3: Premix the two-component microcapsule self-repairing agent and the weathering additive, and then mix them under the protection of inert gas;

[0019] Step 4: Pre-curing the mixture at 60-70°C for 2 hours, then curing at 120-130°C for 1 hour, and finally aging at room temperature for 48 hours;

[0020] Step 5: Disperse and homogenize the cured paint, and then adjust the paint viscosity to the construction requirements to obtain a long-lasting and durable waterproof paint product with self-repairing function.

[0021] A further improvement is that in step three, ultrasonic-assisted dispersion is used when the two-component microcapsule self-repairing agent is added, and the duration is 8 to 12 minutes.

[0022] The beneficial effects of the present invention are as follows: the present invention uses a self-healing matrix resin as the main material, and auxiliary additions include a two-component microcapsule self-healing agent, a fluorosilicone modified waterproofing agent, a nano-reinforced filler and a weather-resistant additive to prepare a finished waterproof coating. Through the synergistic effect of dynamic disulfide bonds and interpenetrating networks, a balance between molecular-level self-healing and macroscopic mechanical properties is achieved. The efficiency bottleneck of single-component self-healing is broken through the two-component microcapsule system, and the three-dimensional cross-linked structure of the fluorosilicone modifier imparts super-amphiphobic properties, which is both hydrophobic and oleophobic. In addition, a multi-scale reinforcement system is constructed by gradient nanofillers, so that crack propagation requires higher energy consumption. Finally, during the synthesis process, a specific curing process is used to ensure the precise control of microcapsule integrity and resin cross-linking degree, so that the finished waterproof coating has excellent self-healing ability, weather resistance and waterproof performance, can maintain good mechanical properties in a variety of environments, and meet the long-term use requirements in harsh environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic flow chart of the synthesis method of the long-lasting and durable waterproof coating with self-repairing function of the present invention. DETAILED DESCRIPTION

[0024] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0025] The development of waterproof coatings has gone through several stages, from the earliest asphalt waterproof coatings to modern high-performance polymer waterproof coatings. In recent years, with the continuous updating and iteration of construction technology, waterproof coatings have become an indispensable building material product in the modern construction engineering industry. Application scenarios include roofs, underground, exterior walls and interiors of buildings, as well as municipal projects such as urban roads, bridges and underground spaces.

[0026] Polyurethane waterproof coatings are widely recognized in the field of building waterproofing due to their excellent mechanical properties, resistance to dilute acid and alkali corrosion, and strong bonding with concrete. Compared with two-component polyurethane waterproof coatings that need to be pre-mixed in a certain proportion, single-component polyurethane waterproof coatings do not require stirring before construction and can be used right out of the bucket, which places lower requirements on construction workers. Therefore, it is the best-selling type of polyurethane waterproof coatings.

[0027] Example 1

[0028] This embodiment provides a long-lasting and durable waterproof coating with a self-repairing function, comprising the following raw materials in parts by weight: 50 parts of a self-repairing matrix resin, 8 parts of a two-component microcapsule self-repairing agent, 12 parts of a fluorosilicone modified waterproofing agent, 10 parts of a nano-reinforced filler, and 3 parts of a weathering agent. The self-repairing matrix resin is a polyurethane-epoxy interpenetrating network polymer (IPN) containing dynamic disulfide bonds, has a reversible cross-linked network structure, and can achieve self-repair under certain conditions. The two-component microcapsule self-repairing agent is composed of type A microcapsules (wall material: polyurea formaldehyde, particle size 5-15 μm) encapsulating an isocyanate curing agent HDI trimer and type B microcapsules (wall material: gelatin-gum arabic complex, particle size 8-20 μm) encapsulating an epoxy resin prepolymer, which are mixed in a mass ratio of 1:1.2. When the coating is damaged, the microcapsules release the repair agent to achieve a self-repairing function.

[0029] In this embodiment, during the synthesis of the polyurethane-epoxy interpenetrating network polymer, a polyurethane prepolymer is first prepared. Then, 4,4'-dithiodiphenylamine is added as a chain extender during the polyurethane prepolymer synthesis stage to introduce dynamic disulfide bonds, which account for 2.5% of the total mass of the resin, forming a reversible cross-linked network structure with a bond energy of ≤250 kJ / mol. The reversible cross-linked network structure has a disulfide bond recombination rate of ≥95% under the conditions of 25°C / 24h and a tensile strength recovery rate of ≥90% after repair. The specific steps are as follows:

[0030] Preparation of polyurethane prepolymer: polyurethane prepolymer and epoxy resin are mixed in a mass ratio of 1:1.5 to form the basic structure of interpenetrating polymer network (IPN);

[0031] Chain extender addition: 4,4'-dithiodiphenylamine was added to the polyurethane prepolymer at a concentration of 2.5% by weight to introduce dynamic disulfide bonds through chain extension reaction.

[0032] Subsequent treatment: After sufficient reaction, curing and aging treatment are carried out to form a polyurethane-epoxy interpenetrating network polymer with self-repairing function.

[0033] In this embodiment, the fluorosilicone modified waterproofing agent is prepared by RAFT polymerization of perfluoroalkylethyl acrylate (an acrylate monomer containing a perfluoroalkyl group, which gives the polymer low surface energy and excellent waterproof properties) and γ-methacryloxypropyltrimethoxysilane (an acrylate monomer containing a silane coupling agent, which improves the adhesion and durability of the polymer to the substrate). The molar ratio of perfluoroalkylethyl acrylate to γ-methacryloxypropyltrimethoxysilane in the fluorosilicone segment is 3:1, and the surface energy is ≤12mN / m, which gives the coating excellent waterproof properties. Selection of chain transfer agent: In this embodiment, dithioester- or trithioester-terminated polydimethylsiloxane (PDMS) is selected as the macromolecular chain transfer agent to introduce the siloxane segment.

[0034] Initiator: In this example, azobisisobutyronitrile (AIBN) was used as an initiator to initiate the polymerization reaction;

[0035] Polymerization conditions: In this embodiment, the polymerization reaction was carried out under an inert atmosphere (N2 protection) at a temperature of 60-80°C.

[0036] In this embodiment, the nano-reinforced filler is a three-dimensional gradient structure composite modified by a silane coupling agent, with a porosity of 40-60%, comprising:

[0037] Flake boron nitride (thickness 20-50 nm, aspect ratio ≥ 200) 40 wt%;

[0038] Porous silica nanospheres (pore size 5-15 nm) 30 wt%;

[0039] 30wt% of carbon fiber chopped strands (length 50-80μm, aspect ratio 50-80);

[0040] The three form a three-dimensional interpenetrating network in the high-speed vortex field, improving the mechanical properties of the coating. The compressive strength of the coating is ≥80 MPa. The preparation method of the three-dimensional gradient structure composite of this embodiment includes the following steps:

[0041] S1. Surface carboxylation of carbon fiber chopped strands

[0042] The carbon fiber chopped strands were oxidized in concentrated nitric acid for 2 hours to form a surface carboxyl material with a surface carboxyl density of more than 0.8 mmol / g, thereby achieving surface modification of the carbon fiber chopped strands and obtaining modified carbon fibers. The purpose is to increase the active functional groups on the carbon fiber surface and improve its binding ability with subsequent materials.

[0043] S2, the surface of the flake boron nitride is coated with a porous silicon dioxide layer

[0044] By using an alternating deposition method, porous silica nanospheres are used to coat the surface of boron nitride flakes with a porous silica layer with a thickness of 10 to 15 nm to obtain a flake composite. This achieves silica coating on the surface of boron nitride and forms a layer of silica with a porous structure on the surface of the boron nitride nanosheets, thereby enhancing its compatibility with carbon fibers.

[0045] S3, forming a spatial network structure through electrostatic self-assembly

[0046] By using electrostatic self-assembly technology, the modified carbon fiber and the sheet-like composite form a three-dimensional interpenetrating spatial network structure. By controlling the Zeta potential (from +35mV to -20mV), the carbon fiber and the boron nitride / silicon dioxide composite are evenly dispersed and tightly bonded.

[0047] In this embodiment, the weathering additive contains a quadruple synergistic stabilization system to improve the weather resistance and anti-aging properties of the coating. The quadruple synergistic stabilization system includes an ultraviolet absorber, an antioxidant, a light stabilizer, and a heat stabilizer, wherein:

[0048] Ultraviolet light absorber: Benzotriazole derivatives. In this example, 0.8 parts of 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol is used. As a highly efficient ultraviolet light absorber, it can absorb ultraviolet light and convert it into harmless heat energy, preventing ultraviolet light from damaging the coating and protecting the coating from photodegradation caused by ultraviolet light, thereby extending the service life of the coating.

[0049] Antioxidant: a complex of hindered phenols and phosphites. In this embodiment, 1.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] + tris(2,4-di-tert-butylphenyl)phosphite (1:1 complex) are selected. The hindered phenol antioxidant can capture free radicals and inhibit the occurrence of oxidation reactions, while the phosphite antioxidant decomposes peroxides and prevents the continuation of the oxidation chain reaction. The two work synergistically to improve the antioxidant properties of the coating.

[0050] Light stabilizer: HALS compound. In this example, 0.5 parts of bis(1,2,2,6,6-pentamethylpiperidinyl) sebacate is used. As a highly effective light stabilizer, HALS can capture free radicals, interrupt the photooxidation process, and prevent the coating from aging due to light exposure. It also works synergistically with the UV absorber to further improve the light resistance and weather resistance of the coating.

[0051] Thermal stabilizer: organic tin-calcium stearate complex. In this embodiment, 0.5 parts of dibutyltin dilaurate-calcium stearate are selected. As a composite thermal stabilizer, it can stabilize the coating at high temperatures, prevent thermal degradation, protect the coating from maintaining stable performance in high temperature environments, and extend its service life.

[0052] See also Figure 1 This embodiment also provides a method for synthesizing a long-lasting and durable waterproof coating with a self-repairing function, comprising the following steps:

[0053] Step 1: Shear and disperse the self-repairing matrix resin and the fluorosilicone modified waterproofing agent under vacuum conditions at a speed of 1000 r / min for 40 minutes and a temperature of 40±2°C to ensure that the two are fully mixed;

[0054] Step 2: Add nano-reinforced filler in equal amounts three times, with an interval of 10 minutes between each addition, and simultaneously apply pulsed ultrasound (28kHz, 0.5W / cm 3 ), control the system temperature ≤ 45 ° C to ensure that the nanofiller is evenly dispersed in the coating;

[0055] Step 3: After premixing the two-component microcapsule self-healing agent and the weathering additive, mix them at a low speed of 500 r / min for 15 minutes under the protection of inert gas (N2) to prevent damage to the microcapsules;

[0056] In this embodiment, ultrasonic assisted dispersion is used when adding the two-component microcapsule self-repairing agent, with a frequency of 28 kHz and a power density of 0.5 W / cm 3 , duration 8min, control microcapsule breakage rate <3%

[0057] Step 4: Using a gradient curing process: first pre-curing at 60 ° C for 2 hours (dynamic disulfide bond pre-reorganization) to promote the pre-reorganization of dynamic disulfide bonds, then curing at 120 ° C for 1 hour (epoxy-isocyanate deep crosslinking) to achieve deep crosslinking of epoxy-isocyanate, and finally aging at room temperature for 48 hours (hydrophobic segment self-assembly) to complete the self-assembly of the hydrophobic segment to obtain the cured coating;

[0058] This embodiment applies an alternating temperature field during curing: Stepwise heating (rate 2°C / min) promotes the release of repair agents from microcapsules and their directional diffusion into the crack area;

[0059] Step 5: Disperse and homogenize the cured coating, and then adjust the coating viscosity to the construction requirements to obtain a long-lasting and durable waterproof coating with self-repairing function;

[0060] The specific steps of dispersing and homogenizing in this embodiment are as follows: the cured coating is placed in a high-speed disperser, sheared and dispersed at a speed of 800 r / min for 20 min, and pulsed ultrasound (28 kHz, 0.5 W / cm 3 ), destroy possible local agglomeration and improve the dispersibility of nanofillers and microcapsules.

[0061] The performance test of the self-repairing, long-lasting waterproof coating prepared in this embodiment was conducted, and the results are as follows:

[0062] Self-repair efficiency: 25℃ / 24h repair scratches (50μm width), the first repair rate is ≥92%, the five-cycle repair rate is ≥85%, the coating can self-repair multiple times, extending the service life;

[0063] Durability: After 3000h of QUV aging, the gloss retention rate is ≥92%, and the tensile strength retention rate is ≥96%. This shows that the coating has excellent weather resistance and aging resistance.

[0064] Waterproof: static contact angle ≥156°, rolling angle ≤4°, dynamic water flushing test (1MPa / 168h) permeability coefficient ≤5×10 -14 m / s, and the waterproof recovery rate after repair is ≥98%, which shows that the coating has excellent waterproof effect;

[0065] Mechanical properties: After 1000 hours in a high temperature and high humidity environment (85°C / relative humidity 95%), the tensile strength retention rate of the coating is above 95%. This shows that the coating still maintains good mechanical properties in a high temperature and high humidity environment.

[0066] In summary, the coating has passed multiple performance tests and demonstrated excellent self-healing ability, weather resistance, waterproofness and mechanical properties. It can meet long-term use requirements and is suitable for various harsh environments.

[0067] Example 2

[0068] This embodiment provides a long-lasting and durable waterproof coating with a self-repairing function, comprising the following raw materials in parts by weight: 70 parts of a self-repairing matrix resin, 15 parts of a two-component microcapsule self-repairing agent, 18 parts of a fluorosilicone modified waterproofing agent, 20 parts of a nano-reinforced filler, and 6 parts of a weathering agent. The self-repairing matrix resin is a polyurethane-epoxy interpenetrating network polymer (IPN) containing dynamic disulfide bonds, has a reversible cross-linked network structure, and can achieve self-repair under certain conditions. The two-component microcapsule self-repairing agent is composed of type A microcapsules (wall material: polyurea formaldehyde, particle size 5-15 μm) encapsulating an isocyanate curing agent HDI trimer and type B microcapsules (wall material: gelatin-gum arabic complex, particle size 8-20 μm) encapsulating an epoxy resin prepolymer, which are mixed in a mass ratio of 1:1.5. When the coating is damaged, the microcapsules release the repair agent to achieve a self-repairing function.

[0069] In this embodiment, during the synthesis of the polyurethane-epoxy interpenetrating network polymer, a polyurethane prepolymer is first prepared. Then, 4,4'-dithiodiphenylamine is added as a chain extender during the synthesis of the polyurethane prepolymer to introduce dynamic disulfide bonds, which account for 4.0% of the total mass of the resin, forming a reversible cross-linked network structure with a bond energy of ≤250 kJ / mol. The reversible cross-linked network structure has a disulfide bond recombination rate of ≥95% under the conditions of 70°C / 10 min, and a tensile strength recovery rate of ≥90% after repair. The specific steps are as follows:

[0070] Preparation of polyurethane prepolymer: polyurethane prepolymer and epoxy resin are mixed in a mass ratio of 1:1.5 to form the basic structure of interpenetrating polymer network (IPN);

[0071] Chain extender addition: 4,4'-dithiodiphenylamine, accounting for 4.0% of the total mass of the resin, was added to the polyurethane prepolymer to introduce dynamic disulfide bonds through chain extension reaction;

[0072] Subsequent treatment: After sufficient reaction, curing and aging treatment are carried out to form a polyurethane-epoxy interpenetrating network polymer with self-repairing function.

[0073] In this embodiment, the fluorosilicone modified waterproofing agent is prepared by RAFT polymerization of perfluoroalkylethyl acrylate (an acrylate monomer containing a perfluoroalkyl group, which gives the polymer low surface energy and excellent waterproof properties) and γ-methacryloxypropyltrimethoxysilane (an acrylate monomer containing a silane coupling agent, which improves the adhesion and durability of the polymer to the substrate). The molar ratio of perfluoroalkylethyl acrylate to γ-methacryloxypropyltrimethoxysilane in the fluorosilicone segment is 5:1, and the surface energy is ≤12mN / m, which gives the coating excellent waterproof properties. Selection of chain transfer agent: In this embodiment, dithioester- or trithioester-terminated polydimethylsiloxane (PDMS) is selected as the macromolecular chain transfer agent to introduce the siloxane segment.

[0074] Initiator: In this example, azobisisobutyronitrile (AIBN) was used as an initiator to initiate the polymerization reaction;

[0075] Polymerization conditions: In this embodiment, the polymerization reaction was carried out under an inert atmosphere (N2 protection) at a temperature of 60-80°C.

[0076] In this embodiment, the nano-reinforced filler is a three-dimensional gradient structure composite modified by a silane coupling agent, with a porosity of 40-60%, comprising:

[0077] Flake boron nitride (thickness 20-50 nm, aspect ratio ≥ 200) 60 wt%;

[0078] Porous silica nanospheres (pore size 5-15 nm) 20 wt%;

[0079] Carbon fiber chopped strands (length 50-80 μm, aspect ratio 50-80) 20 wt%;

[0080] The three form a three-dimensional interpenetrating network in the high-speed vortex field, improving the mechanical properties of the coating. The compressive strength of the coating is ≥80 MPa. The preparation method of the three-dimensional gradient structure composite of this embodiment includes the following steps:

[0081] S1. Surface carboxylation of carbon fiber chopped strands

[0082] The carbon fiber chopped strands were oxidized in concentrated nitric acid for 2 hours to form surface carboxyl groups, with the surface carboxyl density reaching more than 0.8 mmol / g, thereby achieving surface modification of the carbon fiber chopped strands and obtaining modified carbon fibers. The purpose is to increase the active functional groups on the carbon fiber surface and improve its bonding ability with subsequent materials.

[0083] S2, the surface of the flake boron nitride is coated with a porous silicon dioxide layer

[0084] By using an alternating deposition method, porous silica nanospheres are used to coat the surface of boron nitride flakes with a porous silica layer with a thickness of 10 to 15 nm to obtain a flake composite. This achieves silica coating on the surface of boron nitride and forms a layer of silica with a porous structure on the surface of the boron nitride nanosheets, thereby enhancing its compatibility with carbon fibers.

[0085] S3, forming a spatial network structure through electrostatic self-assembly

[0086] By using electrostatic self-assembly technology, the modified carbon fiber and the sheet-like composite form a three-dimensional interpenetrating spatial network structure. By controlling the Zeta potential (from +35mV to -20mV), the carbon fiber and the boron nitride / silicon dioxide composite are evenly dispersed and tightly bonded.

[0087] In this embodiment, the weathering additive contains a quadruple synergistic stabilization system to improve the weather resistance and anti-aging properties of the coating. The quadruple synergistic stabilization system includes an ultraviolet absorber, an antioxidant, a light stabilizer, and a heat stabilizer, wherein:

[0088] Ultraviolet light absorber: Benzotriazole derivatives. In this example, 1.5 parts of 2-(2H-benzotriazole-2-yl)-4,6-di-tert-amylphenol is used. As a highly efficient ultraviolet light absorber, it can absorb ultraviolet light and convert it into harmless heat energy, preventing ultraviolet light from damaging the coating and protecting the coating from photodegradation caused by ultraviolet light, thereby extending the service life of the coating.

[0089] Antioxidant: a complex of hindered phenols and phosphites. In this embodiment, 2.0 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] + tris(2,4-di-tert-butylphenyl)phosphite (1:1 complex) are selected. The hindered phenol antioxidant can capture free radicals and inhibit the occurrence of oxidation reactions, while the phosphite antioxidant decomposes peroxides and prevents the continuation of the oxidation chain reaction. The two work synergistically to improve the antioxidant properties of the coating.

[0090] Light stabilizer: HALS compound. In this example, 1.0 part of bis(1,2,2,6,6-pentamethylpiperidinyl) sebacate is used. As a highly effective light stabilizer, HALS can capture free radicals, interrupt the photooxidation process, and prevent the coating from aging due to light exposure. It also works synergistically with the UV absorber to further improve the light resistance and weather resistance of the coating.

[0091] Thermal stabilizer: organic tin-calcium stearate complex. In this embodiment, 1.5 parts of dibutyltin dilaurate-calcium stearate are selected. As a composite thermal stabilizer, it can stabilize the coating at high temperatures, prevent thermal degradation, protect the coating from maintaining stable performance in high temperature environments, and extend its service life.

[0092] See also Figure 1 This embodiment also provides a method for synthesizing a long-lasting and durable waterproof coating with a self-repairing function, comprising the following steps:

[0093] Step 1: Shear and disperse the self-repairing matrix resin and the fluorosilicone modified waterproofing agent under vacuum conditions at a speed of 1500r / min for 60min and a temperature of 40±2℃ to ensure that the two are fully mixed;

[0094] Step 2: Add nano-reinforced filler in equal amounts three times, with an interval of 10 minutes between each addition, and simultaneously apply pulsed ultrasound (28kHz, 0.5W / cm 3 ), control the system temperature ≤ 45 ° C to ensure that the nanofiller is evenly dispersed in the coating;

[0095] Step 3: After premixing the two-component microcapsule self-healing agent and the weathering additive, mix them at a low speed of 800 r / min for 20 minutes under the protection of inert gas (N2) to avoid damage to the microcapsules;

[0096] In this embodiment, ultrasonic assisted dispersion is used when adding the two-component microcapsule self-repairing agent, with a frequency of 28 kHz and a power density of 0.8 W / cm 3 , duration 12min, control microcapsule breakage rate <3%

[0097] Step 4: Using a gradient curing process: first pre-curing at 70°C for 2 hours (dynamic disulfide bond pre-reorganization) to promote the pre-reorganization of dynamic disulfide bonds, then curing at 130°C for 1 hour (epoxy-isocyanate deep crosslinking) to achieve deep crosslinking of epoxy-isocyanate, and finally aging at room temperature for 48 hours (hydrophobic segment self-assembly) to complete the self-assembly of the hydrophobic segments and obtain the cured coating;

[0098] This embodiment applies an alternating temperature field during curing: Stepwise heating (rate 2°C / min) promotes the release of repair agents from microcapsules and their directional diffusion into the crack area;

[0099] Step 5: Disperse and homogenize the cured coating, and then adjust the coating viscosity to the construction requirements to obtain a long-lasting and durable waterproof coating with self-repairing function;

[0100] The specific steps of dispersing and homogenizing in this embodiment are as follows: placing the cured coating in a high-speed disperser, shearing and dispersing at a speed of 1200 r / min for 30 min, and simultaneously applying pulsed ultrasound (28 kHz, 0.5 W / cm 3 ), destroy possible local agglomeration and improve the dispersibility of nanofillers and microcapsules.

[0101] The performance test of the self-repairing, long-lasting waterproof coating prepared in this embodiment was conducted, and the results are as follows:

[0102] Self-repair efficiency: 25℃ / 24h repair scratches (50μm width), the first repair rate is ≥92%, the five-cycle repair rate is ≥85%, the coating can self-repair multiple times, extending the service life;

[0103] Durability: After 3000h of QUV aging, the gloss retention rate is ≥92%, and the tensile strength retention rate is ≥96%. This shows that the coating has excellent weather resistance and aging resistance.

[0104] Waterproof: static contact angle ≥156°, rolling angle ≤4°, dynamic water flushing test (1MPa / 168h) permeability coefficient ≤5×10 -14 m / s, and the waterproof recovery rate after repair is ≥98%, which shows that the coating has excellent waterproof effect;

[0105] Mechanical properties: After 1000 hours in a high temperature and high humidity environment (85°C / relative humidity 95%), the tensile strength retention rate of the coating is above 95%. This shows that the coating still maintains good mechanical properties in a high temperature and high humidity environment.

[0106] In summary, the coating has passed multiple performance tests and demonstrated excellent self-healing ability, weather resistance, waterproofness and mechanical properties. It can meet long-term use requirements and is suitable for various harsh environments.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A long-lasting and durable waterproof coating with self-repairing function, characterized in that: The invention comprises the following raw materials in parts by weight: 50 to 70 parts of a self-repairing matrix resin, 8 to 15 parts of a two-component microcapsule self-repairing agent, 12 to 18 parts of a fluorosilicone modified waterproofing agent, 10 to 20 parts of a nano-reinforced filler and 3 to 6 parts of a weathering agent; the self-repairing matrix resin is a polyurethane-epoxy interpenetrating network polymer containing dynamic disulfide bonds; the two-component microcapsule self-repairing agent is composed of a mixture of type A microcapsules encapsulating an isocyanate curing agent HDI trimer and type B microcapsules encapsulating an epoxy resin prepolymer; and the mixing mass ratio of type A microcapsules to type B microcapsules is 1:1.2 to 1.

5.

2. The long-lasting and durable waterproof coating with self-repairing function according to claim 1, characterized in that: The dynamic disulfide bond is introduced by adding 4,4'-disulfide diphenylamine as a chain extender during the polyurethane prepolymer synthesis stage, wherein the 4,4'-disulfide diphenylamine accounts for 2.5-4.0% of the total mass of the resin to form a reversible cross-linked network structure.

3. The long-lasting and durable waterproof coating with self-repairing function according to claim 1, characterized in that: The fluorosilicone modified waterproofing agent is prepared by RAFT polymerization of perfluoroalkyl ethyl acrylate and gamma-methacryloxypropyltrimethoxysilane, and the molar ratio of the fluorosilicone segments is 3 to 5:

1.

4. The long-lasting and durable waterproof coating with self-repairing function according to claim 1, characterized in that: The nano-reinforced filler is a three-dimensional gradient structure composite modified by a silane coupling agent, and is made of flaky boron nitride, porous silica nanospheres and carbon fiber chopped strands in a mass ratio of 40-60%: 20-30wt%: 20-30wt%. The flaky boron nitride, porous silica nanospheres and carbon fiber chopped strands form a three-dimensional interpenetrating network in a high-speed vortex field.

5. The long-lasting and durable waterproof coating with self-repairing function according to claim 4, characterized in that: The preparation method of the three-dimensional gradient structure complex comprises the following steps: S1, first oxidize the carbon fiber chopped strands in concentrated nitric acid for 2 hours to form a surface carboxyl material; S2, coating the surface of the boron nitride sheet with a porous silicon dioxide layer by an alternating deposition method; S3. Then, the modified carbon fiber and the sheet-like composite form a spatial network structure through electrostatic self-assembly.

6. The long-lasting and durable waterproof coating with self-repairing function according to claim 1, characterized in that: The weathering agent is composed of a mixture of an ultraviolet absorber, an antioxidant, a light stabilizer and a heat stabilizer, and the mixing mass ratio of the ultraviolet absorber, the antioxidant, the light stabilizer and the heat stabilizer is 0.8-1.5:1.2-2.0:0.5-1.0:0.5-1.

5.

7. A method for synthesizing a long-lasting and durable waterproof coating with self-repairing function as claimed in any one of claims 1 to 6, characterized in that: The following steps are involved: Step 1: Shear and disperse the self-repairing matrix resin and the fluorosilicone modified waterproofing agent under vacuum conditions; Step 2: Add nano-reinforced fillers in three equal amounts and simultaneously apply pulsed ultrasound to evenly disperse the nano-fillers in the coating; Step 3: Premix the two-component microcapsule self-repairing agent and the weathering additive, and then mix them under the protection of inert gas; Step 4: Pre-curing the mixture at 60-70°C for 2 hours, then curing at 120-130°C for 1 hour, and finally aging at room temperature for 48 hours; Step 5: Disperse and homogenize the cured paint, and then adjust the paint viscosity to the construction requirements to obtain a long-lasting and durable waterproof paint product with self-repairing function.

8. The method for synthesizing a long-lasting and durable waterproof coating with self-repairing function according to claim 7, characterized in that: In the step three, the two-component microcapsule self-repairing agent is added by ultrasonic-assisted dispersion, and the duration is 8 to 12 minutes.

Images