Self-repairing composite waterproof sheet and preparation method thereof

Abstract

The present invention belongs to the field of polymer chemical materials technology, specifically relating to a self-healing composite waterproof sheet and its preparation method. Its raw materials include the following components: bisphenol A diglycidyl ether, fluorosilane-modified nano-SiO2, graphene slurry, polydimethylsiloxane, epoxy-terminated polydimethylsiloxane, urea-formaldehyde prepolymer, silane coupling agent, sodium dodecylbenzenesulfonate, FSO-100 fluorocarbon surfactant, CTBN adhesive, curing agent, epoxy accelerator DMP-30, and diluent. Through the collaborative design of a gradient structure of a hard skeleton and soft coating, chemical anchoring of low-surface-energy fillers, localized microcapsule filling, and thermally triggered dynamic bond rearrangement, the present invention achieves a balance between load-bearing strength, long-term hydrophobicity, weather-resistant barrier, and repeatable thermal self-healing properties, while avoiding common defects such as the difficulty of achieving room-temperature self-healing, the easy agglomeration of hydrophobic particles, and the easy delamination of the coating.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer chemical materials, and in particular relates to a self-repairing composite waterproof sheet and a preparation method thereof. Background Art

[0002] In recent years, polymer materials have been widely used in the field of waterproof sheet materials. Researchers have improved the hydrophobicity, durability and environmental adaptability of materials through molecular design, composite modification and functionalization strategies. In existing technologies, polyvinyl chloride (PVC), thermoplastic polyolefin (TPO), polyurethane (PU) and modified asphalt are the mainstream waterproof substrates. Among them, PVC occupies a large market share due to its low cost, high mechanical strength and easy processing, but its embrittlement caused by plasticizer migration limits its long-term waterproof stability; TPO achieves a balance between weather resistance and flexibility through ethylene-propylene copolymerization, but the seam welding process is complicated and prone to interfacial leakage due to thermal stress; polyurethane exhibits excellent elasticity and adhesion due to its adjustable soft and hard segment structure, but pure PU has poor hydrolysis resistance and is prone to molecular chain breakage after long-term immersion in water. It needs to be enhanced with hydrophobic fillers (such as graphene, fluorinated nanosilica) or surface coatings (organic silicone, fluorocarbon resin) to enhance its waterproof performance. In addition, although the high-strength waterproof system represented by epoxy resin-inorganic nanocomposite materials improves the barrier properties through the intercalation of nanoparticles (montmorillonite, carbon nanotubes), the high filling amount easily leads to brittleness of the material and it is difficult to meet the flexibility requirements. Under the trend of environmental protection, bio-based polymers (such as polylactic acid and starch-based materials) have attracted attention due to their degradable properties, but their natural hydrophilicity and low water resistance require them to rely on chemical modification (esterification, grafting hydrophobic segments) or blending with synthetic polymers, and such processes are often accompanied by problems such as poor interfacial compatibility and a sudden drop in mechanical properties. Existing technologies generally face multiple contradictions: the game between hydrophobic modification and mechanical properties (such as fluorination treatment reduces material toughness), the balance between long-term weather resistance and short-term costs (such as nanofillers are expensive and easy to agglomerate), and the conflict between environmental protection needs and traditional petroleum-based materials. Therefore, based on the above defects, it is extremely necessary to develop a composite waterproof sheet that has high hydrophobicity, long-term durability, and self-healing properties. Summary of the Invention

[0003] In view of the defects of the prior art, the object of the present invention is to provide a self-repairing composite waterproof sheet and a preparation method thereof.

[0004] The technical effect described in the present invention is achieved through the following technical scheme: a self-repairing composite waterproof sheet, whose constituent raw materials include the following components in parts by weight: 180-200 parts of bisphenol A diglycidyl ether, 10-12 parts of fluorosilane-modified nano-SiO2, 2-3 parts of graphene slurry, 10-15 parts of polydimethylsiloxane, 4-5 parts of epoxy-terminated polydimethylsiloxane, 8-10 parts of urea-formaldehyde prepolymer, 0.3-0.4 parts of silane coupling agent, 1.2-1.5 parts of sodium dodecylbenzene sulfonate, 0.1-0.12 parts of FSO-100 fluorocarbon surfactant, 6-8 parts of CTBN adhesive, 40-60 parts of curing agent, 0.5-0.8 parts of epoxy accelerator DMP-30 and 3-5 parts of diluent.

[0005] Preferably, the specific preparation steps of the fluorosilane-modified nano-SiO2 are as follows:

[0006] S1: Dry the nano-SiO2 at 120°C for 4-6 hours, then add it to anhydrous ethanol, ultrasonicate it at 300W for 30-60 minutes, add 0.4-0.6% perfluorooctyltriethoxysilane and 0.1-0.2% triethylamine dropwise, adjust the pH to 3-4 with acetic acid, heat it in a water bath to 50-60°C, stir it for 6-8 hours, filter it, rinse it with pentane and ethanol three times in sequence, and dry it at 50°C for 12-24 hours to obtain fluorosilane-modified nano-SiO2;

[0007] Preferably, in step S1, the ratio of the amount of nano-SiO2 to anhydrous ethanol is 1g:100-150mL;

[0008] Preferably, the graphene slurry is obtained by uniformly dispersing graphene, polyvinyl pyrrolidone and ethylene glycol monophenyl ether in a dosage ratio of 1 g:0.1 g:9 mL;

[0009] Preferably, the specific preparation steps of the urea-formaldehyde prepolymer are as follows:

[0010] S101: Add formaldehyde solution to a container, stir continuously at 200-300 rpm, add urea in three batches, add 10 wt% NaOH solution dropwise to adjust the pH to 8-9, heat to 70-75°C, react for 40-80 minutes, and obtain a transparent solution;

[0011] S102: Slowly add 10 wt % formic acid solution to the transparent solution in step S101, adjust the pH to 4.5-5.5, cool to 60-65° C., continue the reaction for 50-80 min, cool to 30° C., add 10 wt % NaOH solution to adjust the pH to 7-8 to terminate the reaction, and distill under reduced pressure at 50-60° C. to a solid content of 60-65%, to obtain a urea-formaldehyde prepolymer;

[0012] Preferably, in step S101, the specific operation of adding urea in three batches is: adding 50% urea for the first time, and adding an equal amount of 25% urea for the remaining two times; the ratio of the amount of urea to formaldehyde solution is 3g:5.5-7.5mL;

[0013] Preferably, the epoxy-terminated polydimethylsiloxane is a glycidoxypropyl-terminated polydimethylsiloxane;

[0014] Preferably, the silane coupling agent is any one of KH-550 silane coupling agent and KH-560 silane coupling agent;

[0015] Preferably, the curing agent is 4,4'-diphenyldisulfide;

[0016] Preferably, the diluent is epoxidized soybean oil;

[0017] Preferably, another aspect of the present invention is to provide a method for preparing a self-repairing composite waterproof sheet material, the specific preparation steps being as follows:

[0018] S201: Melting epoxy-terminated polydimethylsiloxane in a water bath at 50-60° C., vacuum degassing for 5 minutes to obtain pre-melted epoxy-terminated polydimethylsiloxane; mixing polydimethylsiloxane with one-fifth part by weight of fluorosilane-modified nano-SiO2, and ultrasonically treating to obtain a uniform oil phase;

[0019] S202: Sodium dodecylbenzenesulfonate was added to 100 parts by weight of deionized water, and the mixture was stirred at 800 rpm to dissolve uniformly. Then, the uniform oil phase prepared in step S201 was slowly added dropwise at a rate of 1 to 2 mL / min, and sheared to obtain an emulsion.

[0020] S203: 10 wt% HCl was added dropwise to the emulsion prepared in step S202 to adjust the pH to 3, and the mixture was heated to 45-50°C. A silane coupling agent and a urea-formaldehyde prepolymer were added in sequence, and the mixture was mixed evenly. The mixture was heated to 70°C, and the pH was adjusted to 4-4.5. The reaction was maintained for 2-4 hours, and the mixture was cooled and centrifuged at 3000 rpm for 5 minutes. The supernatant was discarded, and the mixture was washed with deionized water for 3 times. The mixture was dried under vacuum at 50°C for 12-24 hours to obtain PDMS@SiO2 microcapsules.

[0021] S204: adding two-thirds of bisphenol A diglycidyl ether and CTBN adhesive into a container, heating to 60-70° C., stirring and mixing evenly, then reducing the temperature to 40-45° C., adding graphene slurry, stirring at 300 rpm for 10-20 minutes, adding epoxy accelerator DMP-30, curing agent and diluent, vacuum degassing, and infusion curing to obtain a semi-cured bottom skeleton resin;

[0022] S205: The pre-melted epoxy-terminated polydimethylsiloxane prepared in step S201 and the remaining weight parts of bisphenol A diglycidyl ether are mixed, and then FSO-100 fluorocarbon surfactant and fluorosilane-modified nano-SiO2 are added in sequence, and shearing treatment is carried out at 3000 rpm for 2 to 5 minutes. The PDMS@SiO2 microcapsules prepared in step S203 are added, and stirring treatment is carried out at 300 rpm for 2 to 5 minutes. Vacuum degassing is performed, and the semi-cured base skeleton resin prepared in step S204 is coated with it to a thickness of 120 to 150 μm. After the double-stage curing treatment, the self-repairing composite waterproof sheet is treated with deionized water mist at 80°C for 3 to 5 minutes, and then dried with hot air at 60°C to obtain the self-repairing composite waterproof sheet;

[0023] Preferably, in step S201, the ultrasonic treatment parameters are: 200-300W, 20kHz, time 10-20min;

[0024] Preferably, in step S204, the vacuum degassing parameters are: treatment at -0.09 MPa for 30 to 60 minutes, with intermittent degassing twice;

[0025] Preferably, in step S204, the specific operation of the perfusion curing is as follows: on a 6 mm aluminum alloy flat mold preheated at 60°C, a layer of 25 μm polyester release cloth is laid, and then 6 layers of alkali-free glass fiber plain cloth are stacked. After the stacking is completed, perfusion is performed at a speed of 1.5 to 3 cm / min. After the perfusion is completed, a vacuum of -0.09 MPaa is maintained and the temperature is increased to 60°C at a rate of 1°C / min. The temperature is kept constant for 1 to 2 hours, and then a vacuum of -0.03 MPa is maintained, and the mold is naturally cooled to 35°C.

[0026] Preferably, in step S205, the vacuum degassing parameters are: treatment at -0.09 MPa for 8 to 10 minutes;

[0027] Preferably, in step S205, the specific parameters of the two-stage curing treatment are: in a vacuum environment, heating to 80°C at a rate of 1°C / min, maintaining the constant temperature for 2 to 3 hours, then continuing to heat to 120°C, maintaining the constant temperature for 2 to 3 hours, and then naturally cooling to 50°C.

[0028] The beneficial effects of the present invention are as follows:

[0029] The present invention uses bisphenol A epoxy resin and 4,4'-dithiodiphenylamine to partially cure into a highly cross-linked skeleton to form the basic skeleton, and uses CTBN adhesive to impart toughness without destroying strength; 4,4'-dithiodiphenylamine is used as a potential accelerator to keep the curing at 60°C, retaining some epoxy and disulfide bond active sites, providing reliable covalent bonding for the subsequent second-step coating, and avoiding the interface delamination defects that are prone to occur in traditional double-layer composites. The top layer of resin that is subsequently applied is blended with a small amount of glycidoxypropyl-terminated polydimethylsiloxane (terminated epoxy-PDMS) and bisphenol A epoxy resin to lower the glass transition temperature and increase the mobility of the chain segments during subsequent heating, thereby completing crack closure in conjunction with disulfide bond exchange under the action of an external heat source (such as hot air or infrared lamp), achieving both heat-triggered reversible repair and avoiding the disadvantage that disulfide bonds are difficult to respond at room temperature. Fluorosilane-modified nano-SiO2 particles perform a dual role in the formulation. Their fluoroalkyl groups impart low surface energy, while the silanol residues condense with the epoxy network during the staged curing phase, achieving chemical anchoring. Furthermore, by adding a trace amount of fluorosurfactant to the formulation and combining it with a slow curing temperature, some particles are encouraged to migrate toward the air interface, forming a durable, rough, hydrophobic layer. This reduces the risk of hydrophobic particle agglomeration in the resin, ensuring environmental viability while strictly controlling the trace amount of fluorosurfactant used. The PDMS@SiO2 microcapsules are completely retained in the coating through gentle shearing and low vacuum treatment, ensuring that the capsules do not leak during normal use. If a deep scratch damages the shell wall, the shed polydimethylsiloxane (PDMS-oil) carrying the SiO2 quickly fills the grooves, providing lubrication and new roughness for subsequent thermal repair, compensating for the difficulty of surface restoration through network rearrangement alone.

[0030] The present invention embeds graphene sheets, after being well dispersed with ethylene glycol monophenyl ether, into a two-layer network, introducing a continuous barrier and heat conduction channel for the resin. The layered structure significantly extends the permeation path of water vapor and oxygen, improving weather resistance. The moderate thermal conductivity also makes external heating more uniform, shortens the disulfide bond activation time, and overcomes the problems of local overheating or inefficient repair. The entire curing process uses a gradual thermal cycle of pre-curing, temperature-increasing leveling curing, and high-temperature final curing and cross-linking. This not only leaves a viscosity gap for particle / segment migration, but also ensures the final cross-linking degree and dimensional stability. The final water mist and hot air treatment removes floating powder and once again promotes the arrangement of polydimethylsiloxane and fluorinated particles on the surface, compensating for surface unevenness that may be introduced during the film formation process.

[0031] In summary, the present invention achieves a balance between load-bearing strength, long-term hydrophobicity, weather-resistant barrier and repeatable thermal self-repairing through the coordinated design of the gradient structure of the hard skeleton and soft coating, chemical anchoring of low surface energy fillers, local filling of microcapsules and heat-triggered dynamic bond rearrangement, while avoiding common defects such as the difficulty of achieving room temperature self-repair, easy agglomeration of hydrophobic particles, and easy stratification of the coating. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 3 is a graph showing the hydrophobicity test results of the self-repairing composite waterproof sheet materials prepared in Example 3 of the present invention and Comparative Examples 1 to 4;

[0034] Figure 2 1 is a graph showing the self-repairing test results of the self-repairing composite waterproof sheet materials prepared in Example 3 of the present invention and Comparative Example 2;

[0035] Figure 3 This is a scanning electron microscope image of the self-repairing test of the self-repairing composite waterproof sheet prepared in Example 3 of the present invention;

[0036] Figure 4 3 is a graph showing the water vapor barrier test results of the self-repairing composite waterproof sheet material prepared in Example 3 of the present invention and Comparative Examples 1 to 4. DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention. It should be noted that unless otherwise specified, the raw materials involved in the present invention were purchased through conventional commercial channels.

[0038] Example 1: A self-repairing composite waterproof sheet, whose raw materials include the following components in parts by weight: 180 parts of bisphenol A diglycidyl ether, 10 parts of fluorosilane-modified nano-SiO2, 2 parts of graphene slurry, 10 parts of polydimethylsiloxane, 5 parts of epoxy-terminated polydimethylsiloxane, 10 parts of urea-formaldehyde prepolymer, 0.4 parts of silane coupling agent, 1.5 parts of sodium dodecylbenzenesulfonate, 0.1 parts of FSO-100 fluorocarbon surfactant, 6 parts of CTBN adhesive, 40 parts of curing agent, 0.5 parts of epoxy accelerator DMP-30 and 3 parts of diluent.

[0039] 1. The specific preparation steps of fluorosilane modified nano-SiO2 are as follows:

[0040] S1: 1 g of nano-SiO2 was dried at 120°C for 4 h, then added to 100 mL of anhydrous ethanol and ultrasonically treated at 300 W for 30 min. 0.6 mL of perfluorooctyltriethoxysilane and 0.2 mL of triethylamine were added dropwise. The pH was adjusted to 4 with acetic acid. The mixture was heated in a water bath to 50°C and stirred for 8 h. The mixture was filtered, rinsed three times with pentane and then ethanol, and dried at 50°C for 12 h to obtain fluorosilane-modified nano-SiO2.

[0041] 2. The graphene slurry is obtained by mixing and evenly dispersing graphene, polyvinyl pyrrolidone, and ethylene glycol monophenyl ether in a ratio of 1 g:0.1 g:9 mL;

[0042] 3. The specific preparation steps of urea-formaldehyde prepolymer are as follows:

[0043] S101: 55 mL of formaldehyde solution was added to a container, and the mixture was stirred continuously at 200 rpm. 30 g of urea was added in three batches, with 50% urea added in the first batch and 25% urea added in the remaining two batches. 10 wt % NaOH solution was then added dropwise to adjust the pH to 8. The mixture was heated to 70°C and reacted for 80 min to obtain a transparent solution.

[0044] S102: Slowly add 10 wt % formic acid solution to the transparent solution in step S101, adjust the pH to 5.5, cool to 60° C., continue the reaction for 80 min, cool to 30° C., add 10 wt % NaOH solution to adjust the pH to 7 to terminate the reaction, and distill under reduced pressure at 50° C. to a solid content of 62%, to obtain a urea-formaldehyde prepolymer;

[0045] 4. The specific preparation steps of the self-repairing composite waterproof sheet are as follows:

[0046] S201: Melt glycidoxypropyl-terminated polydimethylsiloxane in a water bath at 50°C and degas under vacuum for 5 minutes to obtain pre-melted epoxy-terminated polydimethylsiloxane; mix the polydimethylsiloxane with one-fifth of fluorosilane-modified nano-SiO2 and ultrasonicate at 200W, 20kHz for 20 minutes to obtain a uniform oil phase;

[0047] S202: Sodium dodecylbenzenesulfonate was added to 100 parts by weight of deionized water, and the mixture was stirred at 800 rpm to dissolve uniformly. Then, the uniform oil phase prepared in step S201 was slowly added dropwise at a rate of 1.5 mL / min, and sheared to obtain an emulsion.

[0048] S203: 10 wt% HCl was added dropwise to the emulsion prepared in step S202 to adjust the pH to 3, and the mixture was heated to 45°C. KH-550 silane coupling agent and urea-formaldehyde prepolymer were added in sequence. After mixing, the mixture was heated to 70°C, the pH was adjusted to 4, and the reaction was maintained for 4 hours. The mixture was cooled, centrifuged at 3000 rpm for 5 minutes, the supernatant was discarded, and the mixture was washed with deionized water for 3 times. The mixture was vacuum dried at 50°C for 24 hours to obtain PDMS@SiO2 microcapsules.

[0049] S204: Add two-thirds of bisphenol A diglycidyl ether and CTBN adhesive into a container, heat to 60°C, stir and mix evenly, then reduce the temperature to 40°C, then add graphene slurry, stir at 300rpm for 10min, add epoxy accelerator DMP-30, 4,4'-dithiodiphenylamine and epoxy soybean oil, and vacuum degassing for 30min at -0.09MPa, with an average of two intermittent degassings, then lay a layer of 25μm polyester release cloth on a 6mm aluminum alloy flat mold preheated at 60°C, and then stack 6 layers of alkali-free glass fiber plain cloth. After stacking, pour at 1.5cm / min, maintain a vacuum of -0.09MPaa after pouring, and heat to 60°C at a rate of 1°C / min, keep constant temperature for 1h, then maintain a vacuum of -0.03MPa, and naturally cool to 35°C to obtain a semi-cured bottom skeleton resin;

[0050] S205: The pre-melted epoxy-terminated polydimethylsiloxane prepared in step S201 and the remaining weight parts of bisphenol A diglycidyl ether are mixed, and then FSO-100 fluorocarbon surfactant and fluorosilane-modified nano-SiO2 are added in sequence, and shearing treatment is carried out at 3000rpm for 2 minutes. The PDMS@SiO2 microcapsules prepared in step S203 are added, and stirring treatment is carried out at 300rpm for 2 minutes. Vacuum degassing treatment is carried out at -0.09MPa for 8 minutes, and the semi-cured bottom skeleton resin prepared in step S204 is coated with a thickness of 120μm. Under a vacuum environment, the temperature is increased to 80℃ at a rate of 1℃ / min, and the temperature is maintained for 2 hours. Then, the temperature is continued to be increased to 120℃, and the temperature is maintained for 2 hours. Then, it is naturally cooled to 50℃, and treated with 80℃ deionized water mist for 3 minutes. Then, it is blown dry with hot air at 60℃ to obtain a self-repairing composite waterproof sheet.

[0051] Example 2: A self-repairing composite waterproof sheet, whose constituent raw materials include the following components in parts by weight: 200 parts of bisphenol A diglycidyl ether, 12 parts of fluorosilane-modified nano-SiO2, 3 parts of graphene slurry, 15 parts of polydimethylsiloxane, 4 parts of epoxy-terminated polydimethylsiloxane, 8 parts of urea-formaldehyde prepolymer, 0.3 parts of silane coupling agent, 1.2 parts of sodium dodecylbenzenesulfonate, 0.12 parts of FSO-100 fluorocarbon surfactant, 8 parts of CTBN adhesive, 60 parts of curing agent, 0.8 parts of epoxy accelerator DMP-30 and 5 parts of diluent.

[0052] 1. The specific preparation steps of fluorosilane modified nano-SiO2 are as follows:

[0053] S1: 1 g of nano-SiO2 was dried at 120°C for 6 h, then added to 120 mL of anhydrous ethanol and ultrasonically treated at 300 W for 60 min. 0.6 mL of perfluorooctyltriethoxysilane and 0.18 mL of triethylamine were added dropwise. The pH was adjusted to 3 with acetic acid. The mixture was heated in a water bath to 60°C and stirred for 6 h. The mixture was filtered, rinsed three times with pentane and then ethanol, and dried at 50°C for 24 h to obtain fluorosilane-modified nano-SiO2.

[0054] 2. The graphene slurry is obtained by mixing and evenly dispersing graphene, polyvinyl pyrrolidone, and ethylene glycol monophenyl ether in a ratio of 1 g:0.1 g:9 mL;

[0055] 3. The specific preparation steps of urea-formaldehyde prepolymer are as follows:

[0056] S101: 65 mL of formaldehyde solution was added to a container, and the mixture was stirred continuously at 250 rpm. 30 g of urea was added in three batches, with 50% urea added in the first batch and 25% urea added in the remaining two batches. 10 wt % NaOH solution was then added dropwise to adjust the pH to 9. The mixture was heated to 73°C and reacted for 40 min to obtain a transparent solution.

[0057] S102: Slowly add 10 wt % formic acid solution to the transparent solution in step S101, adjust the pH to 4.5, cool to 63° C., continue the reaction for 50 min, cool to 30° C., add 10 wt % NaOH solution to adjust the pH to 8 to terminate the reaction, and distill under reduced pressure at 60° C. to a solid content of 65% to obtain a urea-formaldehyde prepolymer;

[0058] 4. The specific preparation steps of the self-repairing composite waterproof sheet are as follows:

[0059] S201: Melting glycidoxypropyl-terminated polydimethylsiloxane in a water bath at 55°C and vacuum degassing for 5 minutes to obtain pre-melted epoxy-terminated polydimethylsiloxane; mixing polydimethylsiloxane with one-fifth part by weight of fluorosilane-modified nano-SiO2 and ultrasonically treating at 250W, 20kHz for 10 minutes to obtain a uniform oil phase;

[0060] S202: Sodium dodecylbenzenesulfonate was added to 100 parts by weight of deionized water, and the mixture was stirred at 800 rpm to dissolve uniformly. Then, the uniform oil phase prepared in step S201 was slowly added dropwise at a rate of 2 mL / min, and sheared to obtain an emulsion.

[0061] S203: 10 wt% HCl was added dropwise to the emulsion prepared in step S202 to adjust the pH to 3, and the mixture was heated to 50°C. KH-560 silane coupling agent and urea-formaldehyde prepolymer were added in sequence. After mixing, the mixture was heated to 70°C, the pH was adjusted to 4.5, and the reaction was maintained for 2 h. The mixture was cooled, centrifuged at 3000 rpm for 5 min, the supernatant was discarded, and the mixture was washed with deionized water for 3 times. The mixture was vacuum dried at 50°C for 12 h to obtain PDMS@SiO2 microcapsules.

[0062] S204: Add two-thirds of bisphenol A diglycidyl ether and CTBN adhesive into a container, heat to 65°C, stir and mix evenly, then reduce the temperature to 43°C, add graphene slurry, stir at 300rpm for 20min, add epoxy accelerator DMP-30, 4,4'-dithiodiphenylamine and epoxy soybean oil, and vacuum degassing for 60min at -0.09MPa, with two intermittent degassings on average. Then, on a 6mm aluminum alloy flat mold preheated at 60°C, lay a layer of 25μm polyester release cloth, and then stack 6 layers of alkali-free glass fiber plain cloth. After stacking, pour at 3cm / min, maintain a vacuum of -0.09MPaa after pouring, and heat to 60°C at a rate of 1°C / min, keep constant temperature for 2h, then maintain a vacuum of -0.03MPa, and naturally cool to 35°C to obtain a semi-cured bottom skeleton resin;

[0063] S205: The pre-melted epoxy-terminated polydimethylsiloxane prepared in step S201 and the remaining weight parts of bisphenol A diglycidyl ether are mixed, and then FSO-100 fluorocarbon surfactant and fluorosilane-modified nano-SiO2 are added in sequence, and shearing treatment is carried out at 3000rpm for 5 minutes. The PDMS@SiO2 microcapsules prepared in step S203 are added, and stirring treatment is carried out at 300rpm for 5 minutes. Vacuum degassing treatment is carried out at -0.09MPa for 10 minutes, and the semi-cured bottom skeleton resin prepared in step S204 is coated with a thickness of 140μm. Under a vacuum environment, the temperature is increased to 80℃ at a rate of 1℃ / min, and the temperature is maintained for 3 hours. Then, the temperature is continued to be increased to 120℃, and the temperature is maintained for 3 hours. Then, it is naturally cooled to 50℃, and deionized water mist treatment is carried out at 80℃ for 5 minutes. Then, it is blown dry with hot air at 60℃ to obtain a self-repairing composite waterproof sheet.

[0064] Example 3: A self-repairing composite waterproof sheet, whose constituent raw materials include the following components in parts by weight: 190 parts of bisphenol A diglycidyl ether, 11 parts of fluorosilane-modified nano-SiO2, 2.5 parts of graphene slurry, 12 parts of polydimethylsiloxane, 4.5 parts of epoxy-terminated polydimethylsiloxane, 9 parts of urea-formaldehyde prepolymer, 0.35 parts of silane coupling agent, 1.3 parts of sodium dodecylbenzene sulfonate, 0.11 parts of FSO-100 fluorocarbon surfactant, 7 parts of CTBN adhesive, 50 parts of curing agent, 0.6 parts of epoxy accelerator DMP-30 and 4 parts of diluent.

[0065] 1. The specific preparation steps of fluorosilane modified nano-SiO2 are as follows:

[0066] S1: 1 g of nano-SiO2 was dried at 120°C for 5 h, then added to 150 mL of anhydrous ethanol and ultrasonically treated at 300 W for 50 min. 0.6 mL of perfluorooctyltriethoxysilane and 0.15 mL of triethylamine were added dropwise. The pH was adjusted to 3.5 with acetic acid. The mixture was heated in a water bath to 55°C and stirred for 7 h. The mixture was filtered, rinsed three times with pentane and then ethanol, and dried at 50°C for 20 h to obtain fluorosilane-modified nano-SiO2.

[0067] 2. The graphene slurry is obtained by mixing and evenly dispersing graphene, polyvinyl pyrrolidone, and ethylene glycol monophenyl ether in a ratio of 1 g:0.1 g:9 mL;

[0068] 3. The specific preparation steps of urea-formaldehyde prepolymer are as follows:

[0069] S101: 75 mL of formaldehyde solution was added to a container, and the mixture was stirred continuously at 300 rpm. 30 g of urea was added in three batches, with 50% urea added in the first batch and 25% urea added in the remaining two batches. 10 wt % NaOH solution was then added dropwise to adjust the pH to 8.5. The mixture was heated to 75° C. and reacted for 60 min to obtain a transparent solution.

[0070] S102: Slowly add 10 wt % formic acid solution to the transparent solution in step S101, adjust the pH to 5, cool to 65° C., continue the reaction for 70 min, cool to 30° C., add 10 wt % NaOH solution to adjust the pH to 7.5 to terminate the reaction, and distill under reduced pressure at 55° C. to a solid content of 60%, to obtain a urea-formaldehyde prepolymer;

[0071] 4. The specific preparation steps of the self-repairing composite waterproof sheet are as follows:

[0072] S201: Melt glycidoxypropyl-terminated polydimethylsiloxane in a water bath at 60°C and degas under vacuum for 5 minutes to obtain pre-melted epoxy-terminated polydimethylsiloxane; mix the polydimethylsiloxane with one-fifth of fluorosilane-modified nano-SiO2 and ultrasonicate at 300W and 20kHz for 15 minutes to obtain a uniform oil phase;

[0073] S202: Sodium dodecylbenzenesulfonate was added to 100 parts by weight of deionized water, and the mixture was stirred at 800 rpm to dissolve uniformly. Then, the uniform oil phase prepared in step S201 was slowly added dropwise at a rate of 1 mL / min, and sheared to obtain an emulsion.

[0074] S203: 10 wt% HCl was added dropwise to the emulsion prepared in step S202 to adjust the pH to 3, and the mixture was heated to 48°C. KH-560 silane coupling agent and urea-formaldehyde prepolymer were added in sequence. After mixing, the mixture was heated to 70°C, the pH was adjusted to 4.3, and the reaction was maintained for 3 hours. The mixture was cooled, centrifuged at 3000 rpm for 5 minutes, the supernatant was discarded, and the mixture was washed with deionized water for 3 times. The mixture was vacuum dried at 50°C for 20 hours to obtain PDMS@SiO2 microcapsules.

[0075] S204: Add two-thirds of bisphenol A diglycidyl ether and CTBN adhesive into a container, heat to 70°C, stir and mix evenly, then reduce the temperature to 45°C, add graphene slurry, stir at 300rpm for 15min, add epoxy accelerator DMP-30, 4,4'-dithiodiphenylamine and epoxy soybean oil, and vacuum degassing for 50min at -0.09MPa, with two intermittent degassings on average. Then, on a 6mm aluminum alloy flat mold preheated at 60°C, lay a layer of 25μm polyester release cloth, and then stack 6 layers of alkali-free glass fiber plain cloth. After stacking, pour at 2cm / min, maintain a vacuum of -0.09MPaa after pouring, and heat to 60°C at a rate of 1°C / min, keep constant temperature for 1.5h, then maintain a vacuum of -0.03MPa, and naturally cool to 35°C to obtain a semi-cured bottom skeleton resin;

[0076] S205: The pre-melted epoxy-terminated polydimethylsiloxane prepared in step S201 and the remaining weight parts of bisphenol A diglycidyl ether are mixed, and then FSO-100 fluorocarbon surfactant and fluorosilane-modified nano-SiO2 are added in sequence, and shearing treatment is carried out at 3000rpm for 3 minutes. The PDMS@SiO2 microcapsules prepared in step S203 are added, and stirring treatment is carried out at 300rpm for 3 minutes. Vacuum degassing treatment is carried out at -0.09MPa for 9 minutes, and the semi-cured bottom skeleton resin prepared in step S204 is coated with a thickness of 150μm. Under a vacuum environment, the temperature is increased to 80℃ at a rate of 1℃ / min, and the temperature is maintained for 2.5 hours. Then, the temperature is continued to be increased to 120℃, and the temperature is maintained for 2.5 hours. Then, the self-repairing composite waterproof sheet is naturally cooled to 50℃, and deionized water mist treatment is carried out at 80℃ for 4 minutes. Then, the self-repairing composite waterproof sheet is blown dry with hot air at 60℃.

[0077] Comparative Example 1: The operation of Comparative Example 1 is basically the same as that of Example 3, except that the curing treatment parameters are adjusted in Comparative Example 1, that is, after the infusion treatment in step S204 is completed, the temperature is raised to 100°C at a rate of 1°C / min and cured for 6 hours; the two-stage curing operation in step S205 is replaced by a curing treatment at 120°C for 5 hours.

[0078] Comparative Example 2: The operation of Comparative Example 2 is basically the same as that of Example 3, except that, in Comparative Example 2, the curing agent diaminodiphenyl sulfone is used instead of the curing agent 4,4'-disulfadiphenylamine; and the curing treatment parameters are adjusted, that is, after the perfusion treatment in step S204 is completed, the temperature is raised to 100°C at a rate of 1°C / min and the curing treatment is carried out for 6 hours.

[0079] Comparative Example 3: The operation of Comparative Example 3 is basically the same as that of Example 3, except that in Comparative Example 3, the graphene slurry is removed from the raw material.

[0080] Comparative Example 4: The operation of Comparative Example 4 is basically the same as that of Example 3, except that unmodified nano-SiO2 is used instead of fluorosilane-modified nano-SiO2 particles in Comparative Example 4, and FSO-100 fluorocarbon surfactant is removed from the raw materials.

[0081] Performance testing:

[0082] Mechanical property test: The self-repairing composite waterproof sheet samples prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were subjected to the following tests: the tensile strength was measured in accordance with GB / T 1040.1-2018; the flexural strength was measured in accordance with GB / T 9341-2008; the impact strength was measured using a plastic pendulum impact tester in accordance with GB / T 1843-2008, and the peel strength was measured in accordance with GB / T 2790-1995. The test results are shown in Table 1 below.

[0083] Table 1. Mechanical properties test results of self-repairing composite waterproof sheet

[0084]

[0085] It can be seen from the results in Table 1 that the composite waterproof sheet prepared by the present invention has excellent mechanical properties; it can be seen from the results of Comparative Example 1 and Example 3 that the bottom layer is cured to a high cross-linked state at one time before coating, and the interface relies only on physical infiltration, and the peel strength is significantly reduced. In addition, long-term high-temperature treatment may also aggravate the phase separation of CTBN, and SiO2 and PDMS are easy to precipitate, resulting in a significant decrease in impact toughness; it can be seen from the results of Comparative Example 2 and Example 3 that the use of curing agent diaminodiphenyl sulfone instead of curing agent 4,4'-disulfide diphenylamine makes the cross-linking more dense and the tensile strength slightly improved, but high-temperature curing leads to weakened bottom / top layer shear coupling, more brittle DDS, and the interface is prone to cracking. After the bond is replaced, the energy dissipation path is lost, and the top layer is solidified on the inert glass surface, lacking covalent bonding. The interface relies only on van der Waals forces and roughness bonding, and the impact toughness and peel strength decrease significantly. From the results of Comparative Example 3 and Example 3, it can be seen that the graphene sheet has little effect on the static strength, lacks sheet bridges, and the tensile, impact resistance and bending properties are slightly reduced. From the results of Comparative Example 4 and Example 3, it can be seen that the unmodified nanoparticles are hydrophilic and the fluorocarbon surfactant is missing. The nano-hydrophilic particles and the high surface energy interface lead to local agglomeration, and the tensile and bending strengths are affected to a certain extent. The peel strength is doubly weakened by the roughness-adhesion compatibility.

[0086] Hydrophobicity test: Use a microinjector to add 5 μL of ultrapure water droplets at 5 different positions (four corners + center) on the surface of the sample (self-repairing composite waterproof sheet prepared in Example 3 and Comparative Examples 1 to 4) and calculate the contact angle. The results are as follows: Figure 1 As shown; after the above sample is tested at 85℃ / 85% humidity for 1000h, the contact angle is re-measured and the contact angle retention rate is calculated / (%) = contact angle after high temperature and high humidity test / contact angle before high temperature and high humidity test × 100%. The results are as follows Figure 1 shown.

[0087] Depend on Figure 1The results show that the composite waterproof sheet prepared by the present invention has excellent hydrophobic properties and can effectively avoid water erosion; from the results of Comparative Example 1 and Example 3, it can be seen that the viscosity of the top layer is too low due to one-time high-temperature curing, and the rough particles and PDMS partially sink. At the same time, the interface lacks semi-cured anchoring, and the rough layer is prone to micro-peeling after wet-heat cycling, resulting in a significant decrease in contact angle; from the results of Comparative Example 2 and Example 3, due to the lack of dynamic disulfide bonds, shallow cracks gradually open during the wet-heat test, and due to full curing, water vapor penetrates along the interface, and the rough layer curls and peels off from the edge; the area of ​​fluorosilane chain head hydrolyzed increases, and the roughness fails locally. Although the overall performance remains intact, the long-term performance decreases significantly; from the results of Comparative Example 3 and Example 3, it can be seen that the lack of graphene barrier leads to faster water vapor penetration, partial hydrolysis of the fluorosilane chain head, and destruction of the fluorosilane-SiO 2 / The hydrophobicity of the resin interface decreases to a certain extent; from the results of Comparative Example 4 and Example 3, it can be seen that the nanoparticles are not modified and there is no surfactant, the initial hydrophobic effect is limited, and the particles after wet heat treatment absorb water and expand, the surface energy increases, the rough layer collapses, the contact angle decreases significantly, and the hydrophobicity decreases seriously.

[0088] Self-repair test: The self-repairing composite waterproof sheet prepared in Example 3 and Comparative Example 2 was cut into 50 mm × 10 mm × 3 mm test strips and vacuum-dried at 60°C for 24 h to remove residual moisture. A 30N diamond bit was used to cut to a depth of 120 μm, so that the scratches penetrated the top layer and were expected to destroy part of the capsule. The test piece was then placed in a 90°C hot air oven for 10 min. After cooling to room temperature, the microscopic and interferometric measurements were repeated, and the crack shrinkage rate was calculated as (original crack cross-sectional area - remaining crack cross-sectional area after repair) / original crack cross-sectional area × 100%; the results are shown in FIG. Figure 2 The self-repairing composite waterproof sheet prepared in Example 3 was subjected to a 144-hour salt spray test and then a scratch repair test was performed. The test results are shown in FIG. Figure 3 shown.

[0089] Depend on Figure 2 and Figure 3 The results show that the self-repairing composite waterproof sheet prepared by the present invention has excellent self-repairing properties, and still has excellent self-repairing effects after the salt spray test, and can effectively cope with more complex environments; from the results of Example 3 and Comparative Example 2, it can be seen that when the curing agent is changed to diaminodiphenyl sulfone, the network lacks segment migration at 90°C and can only rely on exogenous filling, and the surface energy of the rigid diaminodiphenyl sulfone network is relatively high, and the wetting of the side walls by PDMS-oil is limited. Part of the filler shrinks along the cracks after cooling, leaving holes, and the self-repairing effect is significantly reduced.

[0090] Water vapor barrier test: The water vapor transmission rate of the self-repairing composite waterproof sheet prepared in Example 3 and Comparative Examples 1 to 4 was tested according to GB / T 17146-2015. The results are as follows: Figure 4 shown.

[0091] Depend on Figure 4 The results show that the present invention significantly reduces the water vapor permeability of the waterproof sheet through multi-level synergistic effects; from the results of Comparative Example 1 and Example 3, it can be seen that one-time high-temperature curing may lead to too low viscosity, which in turn leads to partial sedimentation of modified nano-SiO2 and PDMS, increased porosity of the top layer, and microcracks appear due to lack of chemical bonding at the interface, resulting in obvious water vapor permeation; from the results of Comparative Example 2 and Example 3, it can be seen that the graphene barrier is still there, with few initial gaps, but the microcracks caused by the lack of dynamic disulfide bonds cannot be healed, and the interface bonding layer becomes a side channel for water vapor, which infiltrates the surface of the water vapor. The permeability paths increase with the increase of test time; from the results of Comparative Example 3 and Example 3, it can be seen that the absence of graphene slurry leads to the disappearance of the maze effect, and the water vapor diffusion coefficient returns to the epoxy level. Although the rough and low surface energy still inhibits solubility, the water vapor permeability is still significantly increased; from the results of Comparative Example 4 and Example 3, it can be seen that the nanoparticles are unmodified and have no surfactant. The hydrophilic particle agglomeration and high surface energy make the surface hydrophilic and porous, and the lack of surfactant makes the particles unable to be directionally dense, and water vapor is easy to dissolve and diffuse, which leads to a significant increase in water vapor permeability.

[0092] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A self-repairing composite waterproof sheet, characterized in that: The raw materials include the following components in parts by weight: 180-200 parts of bisphenol A diglycidyl ether, 10-12 parts of fluorosilane-modified nano-SiO2, 2-3 parts of graphene slurry, 10-15 parts of polydimethylsiloxane, 4-5 parts of epoxy-terminated polydimethylsiloxane, 8-10 parts of urea-formaldehyde prepolymer, 0.3-0.4 parts of silane coupling agent, 1.2-1.5 parts of sodium dodecylbenzene sulfonate, 0.1-0.12 parts of FSO-100 fluorocarbon surfactant, 6-8 parts of CTBN adhesive, 40-60 parts of curing agent, 0.5-0.8 parts of epoxy accelerator DMP-30 and 3-5 parts of diluent; The preparation steps of the self-repairing composite waterproof sheet are as follows: S201: Melting epoxy-terminated polydimethylsiloxane in a water bath, vacuum degassing, and obtaining pre-melted epoxy-terminated polydimethylsiloxane; mixing polydimethylsiloxane with one-fifth of fluorosilane-modified nano-SiO2, and ultrasonically treating the mixture to obtain a uniform oil phase; S202: adding sodium dodecylbenzenesulfonate to deionized water, stirring to dissolve uniformly, then slowly adding dropwise the uniform oil phase prepared in step S201, and shearing to obtain an emulsion; S203: HCl is added dropwise to the emulsion prepared in step S202 to adjust the pH, the mixture is heated, a silane coupling agent and a urea-formaldehyde prepolymer are added in sequence, the mixture is mixed evenly, the temperature is increased, the pH is adjusted, the reaction is maintained, the mixture is cooled, the mixture is centrifuged, the supernatant is discarded, the mixture is repeatedly washed with deionized water, and the mixture is vacuum dried to obtain PDMS@SiO2 microcapsules; S204: adding two-thirds of bisphenol A diglycidyl ether and CTBN adhesive into a container, heating, stirring and mixing, then lowering the temperature, adding graphene slurry, stirring, adding epoxy accelerator DMP-30, curing agent and diluent, vacuum degassing, and infusion curing to obtain a semi-cured bottom skeleton resin; S205: The pre-melted epoxy-terminated polydimethylsiloxane prepared in step S201 and the remaining weight parts of bisphenol A diglycidyl ether are mixed, and then FSO-100 fluorocarbon surfactant and fluorosilane-modified nano-SiO2 are added in sequence, sheared, and the PDMS@SiO2 microcapsules prepared in step S203 are added, stirred, vacuum degassed, and coated on the semi-cured base skeleton resin prepared in step S204. After a two-stage curing treatment, the self-repairing composite waterproof sheet is treated with deionized water mist and then dried with hot air to obtain the self-repairing composite waterproof sheet; In step S201, the ultrasonic treatment parameters are: 200-300W, 20kHz, and time 10-20min; In step S204, the vacuum degassing parameters are: treatment at -0.09 MPa for 30 to 60 minutes, with intermittent degassing twice; In step S204, the specific operation of the infusion curing is as follows: on a 6mm aluminum alloy flat mold preheated at 60°C, a layer of 25μm polyester release cloth is laid, and then 6 layers of alkali-free glass fiber plain cloth are stacked. After the stacking is completed, infusion is performed at a speed of 1.5-3cm / min. After the infusion is completed, a vacuum of -0.09MPa is maintained and the temperature is increased to 60°C at a rate of 1°C / min. The temperature is kept constant for 1-2 hours, and then a vacuum of -0.03MPa is maintained, and the mold is naturally cooled to 35°C. In step S205, the vacuum degassing parameters are: treatment at -0.09 MPa for 8 to 10 minutes; the specific parameters of the two-stage curing treatment are: in a vacuum environment, heating to 80°C at a rate of 1°C / min, maintaining the constant temperature for 2 to 3 hours, then continuing to heat to 120°C, maintaining the constant temperature for 2 to 3 hours, and then naturally cooling to 50°C.

2. The self-repairing composite waterproof sheet according to claim 1, characterized in that: The specific preparation steps of the fluorosilane-modified nano-SiO2 are as follows: S1: drying the nano-SiO2, then adding it to anhydrous ethanol, ultrasonically treating it, dropping perfluorooctyltriethoxysilane and triethylamine, adjusting the pH with acetic acid, heating it in a water bath, stirring it, filtering it, rinsing it repeatedly with pentane and ethanol in sequence, and drying it to obtain fluorosilane-modified nano-SiO2; In step S1, the ratio of the amount of the nano-SiO2 to the anhydrous ethanol is 1g:100-150mL.

3. The self-repairing composite waterproof sheet according to claim 2, characterized in that: The graphene slurry is obtained by uniformly dispersing graphene, polyvinyl pyrrolidone and ethylene glycol monophenyl ether in a dosage ratio of 1 g:0.1 g:9 mL.

4. The self-repairing composite waterproof sheet according to claim 3, characterized in that: The specific preparation steps of the urea-formaldehyde prepolymer are as follows: S101: Add formaldehyde solution to a container, continue stirring, and add urea in three batches, add NaOH solution dropwise to adjust the pH, increase the temperature, and react to obtain a transparent solution; S102: slowly adding formic acid solution to the transparent solution in step S101, adjusting the pH, cooling, continuing the reaction, cooling again, adding NaOH solution to adjust the pH to terminate the reaction, and performing reduced pressure distillation to obtain a urea-formaldehyde prepolymer.

5. The self-repairing composite waterproof sheet according to claim 4, characterized in that: In step S101, the specific operation of adding urea in three batches is: adding 50% urea for the first time, and adding equal amounts of 25% urea for the remaining two times; the ratio of the amount of urea to formaldehyde solution is 3g:5.5-7.5mL.

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