Hot-melt type super high viscosity modified asphalt waterproof coating and preparation method thereof

Abstract

The present application relates to the technical fields of coating composition and high polymer material modification, in particular to a hot-melt type super-high viscosity modified asphalt waterproof coating and a preparation method thereof; the coating comprises base asphalt, polymer elastomer modifier, multifunctional reactive tackifying modifier, crosslinking system and the like, and is prepared through melting stirring, shearing dispersion and heat preservation development; the core is to prepare the multifunctional tackifying modifier containing specific reactive groups through the reaction of hydroxyl-terminated polybutadiene, diisocyanate, dopamine and amino silane coupling agent, and to promote the in-situ chemical crosslinking reaction of multiple components in the development stage; the present application utilizes the stable coordination bond and condensation bond formed between the multifunctional modifier and the base surface, and constructs the interpenetrating crosslinking network inside the system, effectively removes the water film on the base surface, and significantly improves the dry and wet base surface peeling strength, heat aging retention rate and low temperature flexibility of the coating.

Description

Technical Field

[0001] This invention relates to the field of coating compositions and polymer material modification technology, specifically to a hot-melt ultra-high viscosity modified asphalt waterproof coating and its preparation method. Background Technology

[0002] In the field of building waterproofing, hot-melt modified bitumen waterproofing coatings are widely used products, and their interfacial adhesion process is crucial. To ensure the long-term stability of the waterproofing system, a strong bond is usually required between the coating and inorganic substrates such as concrete. Traditional coating formulations often rely on the addition of components such as petroleum resins to provide a simple physical tackifier. This physical adhesion mechanism lacks both active groups that can interact with inorganic substrates and reaction sites that participate in in-situ cross-linking, making it difficult to form stable chemical bonds at the interface. Especially when the substrate contains water, the water film is difficult to effectively dissipate, resulting in interfacial adhesion failure and a decrease in overall waterproofing reliability.

[0003] While some existing technologies have attempted to improve performance by adjusting the ratio of elastomers or base asphalt, these methods generally suffer from weak interfacial bonding and insufficient cohesive strength. Furthermore, most existing modified asphalt systems neglect to introduce specific structures between the coating and the substrate that can form stable coordination and condensation bonds, resulting in limited adhesion in humid environments. In addition, traditional formulations lack effective mechanisms for building internal interpenetrating cross-linked networks when facing changes such as high-temperature thermal aging or alternating low-temperature environments, leading to the migration and precipitation of small-molecule resins and causing coating embrittlement, making it difficult to meet the complex and variable requirements of actual engineering services. Therefore, how to provide a hot-melt ultra-high viscosity modified asphalt waterproof coating that combines excellent dry and wet substrate peel strength, high thermal aging retention rate, and good low-temperature flexibility is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a hot-melt, ultra-high viscosity modified bitumen waterproof coating, aiming to solve the problems of existing coatings that rely solely on physical thickening and lack chemical bonding and in-situ crosslinking mechanisms, resulting in easy adhesion failure on damp substrates, insufficient cohesive strength, and easy resin migration and precipitation causing coating embrittlement. Specifically, the technical solution of this invention is as follows:

[0005] A hot-melt, ultra-high viscosity modified bitumen waterproof coating, wherein the raw materials for preparing the waterproof coating, by weight, include:

[0006] 40-60 parts of base asphalt; 5-15 parts of polymer elastomer modifier; 3-10 parts of multifunctional reactive tackifier; 5-12 parts of softening oil; 10-25 parts of filler; 0.1-1 part of crosslinking agent; 0.05-0.5 parts of crosslinking accelerator;

[0007] The multifunctional reactive thickening modifier is prepared by a method comprising the following steps:

[0008] The hydroxyl-terminated polybutadiene, diisocyanate, dopamine hydrochloride, and aminosilane coupling agent are mixed in a molar ratio of 1:(1.5-2.5):(0.5-1.5):(0.5-1.5). The hydroxyl-terminated polybutadiene is then dehydrated under vacuum, cooled, and diisocyanate and a catalyst are added under nitrogen protection. The amount of catalyst is 0.05-0.5% of the mass of the hydroxyl-terminated polybutadiene. The reaction yields a polyurethane-polybutadiene prepolymer with terminal isocyanate.

[0009] Under light-protected and nitrogen-protected conditions, dopamine hydrochloride was dissolved in an anhydrous organic solvent, an acid-binding agent was added, and the mixture was stirred thoroughly. The precipitate was removed by filtration to obtain a free dopamine solution. The free dopamine solution was then added dropwise to the isocyanate-terminated polyurethane-polybutadiene prepolymer for reaction.

[0010] After the reaction, the temperature is increased, and an aminosilane coupling agent is added to continue the reaction;

[0011] After the reaction is complete, the anhydrous organic solvent is removed by vacuum distillation to obtain the multifunctional reactive thickening modifier.

[0012] Preferably, in the preparation step of the multifunctional reactive thickening modifier, the number average molecular weight of the hydroxyl-terminated polybutadiene is 2000-3000; the vacuum dehydration temperature is 100-110℃ and the time is 2h; the cooling temperature is reduced to 60℃; and the reaction time to obtain the isocyanate-terminated polyurethane-polybutadiene prepolymer is 3-4h.

[0013] Preferably, in the preparation step of the multifunctional reactive thickening modifier, the diisocyanate is isophorone diisocyanate, the catalyst is dibutyltin dilaurate; the organic solvent is anhydrous N,N-dimethylformamide, the acid-binding agent is triethylamine, and the molar ratio of dopamine hydrochloride to triethylamine is 1:1; the aminosilane coupling agent is 3-aminopropyltriethoxysilane.

[0014] Preferably, in the preparation step of the multifunctional reactive thickening modifier, the temperature for adding the free dopamine solution dropwise to the isocyanate-terminated polyurethane-polybutadiene prepolymer for reaction is 0-10°C for 2 hours; the temperature for adding the aminosilane coupling agent to continue the reaction is 40°C for 1 hour; and the temperature for vacuum distillation is 60°C.

[0015] Preferably, the base asphalt is 70# road petroleum asphalt or 90# road petroleum asphalt; the polymer elastomer modifier is styrene-butadiene-styrene block copolymer or styrene-isoprene-styrene block copolymer; and the softening oil is naphthenic oil or aromatic oil.

[0016] Preferably, the filler is one or more of talc, heavy calcium carbonate and silica powder; the crosslinking agent is sulfur or dicumyl peroxide; and the crosslinking accelerator is one or a combination of tetramethylthiuram disulfide and zinc oxide.

[0017] Another object of the present invention is to provide a method for preparing the aforementioned hot-melt ultra-high viscosity modified bitumen waterproof coating, comprising the following steps,

[0018] The base asphalt is heated to melt, the softening oil is added and stirred evenly, and then the polymer elastomer modifier is added in batches, and the mixture is kept warm and stirred to allow it to swell fully;

[0019] The system is transferred to a high-shear disperser for shear dispersion, so that the polymer elastomer modifier is dispersed in the matrix asphalt;

[0020] Reduce the rotation speed and add the filler, the multifunctional reactive thickener modifier, the crosslinking agent and the crosslinking accelerator in sequence. Keep the mixture warm and allow it to develop, so that the multifunctional reactive thickener modifier, the polymer elastomer modifier and the base asphalt undergo a chemical crosslinking reaction.

[0021] The material is cooled and discharged to obtain the hot-melt ultra-high viscosity modified asphalt waterproof coating.

[0022] Preferably, the base asphalt is heated to a melting temperature of 170-180°C; the temperature for heat preservation and stirring is 170°C, and the time is 40-60 minutes.

[0023] Preferably, the high shear disperser has a rotation speed of 4000-5000 r / min and a shear dispersion time of 45-60 min; the rotation speed is then reduced to 1000 r / min.

[0024] Preferably, the temperature for heat preservation and development is 160-170℃, and the time is 1.5-2 hours; the temperature for cooling and discharging is 140℃.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. This invention introduces specific reactive groups into the system by adding a multifunctional reactive tackifier prepared from hydroxyl-terminated polybutadiene, diisocyanate, dopamine hydrochloride, and an aminosilane coupling agent. This modifier can form stable chemical bonds with inorganic substrates, effectively repelling water films on the substrate. Compared to traditional single physical tackifying methods, this waterproof coating improves the interfacial peel strength on both dry and damp substrates, mitigating the defect of easy adhesion failure in humid environments.

[0027] 2. The preparation method of the present invention adds a crosslinking agent and a crosslinking accelerator during the heat preservation and development stage, which promotes the chemical crosslinking reaction of the multifunctional reactive thickening modifier, the polymer elastomer modifier, and the matrix asphalt. This crosslinking mechanism constructs a stable network structure inside the system, effectively restricting the migration and precipitation of components and reducing the risk of coating embrittlement. This structure enables the waterproof coating to have excellent cohesive strength, improves the peel strength retention rate after heat aging, and has good low-temperature flexibility.

[0028] 3. In the preparation of a multifunctional reactive thickening modifier, this invention involves controlling the reaction of terminally hydroxyl-terminated polybutadiene with diisocyanate to generate a specific prepolymer, which is then further reacted with a free dopamine solution and an aminosilane coupling agent. This process ensures that the modifier molecular chain possesses both active segments capable of participating in subsequent chemical crosslinking and reactive sites that enhance interfacial adhesion. This approach effectively improves the overall compatibility of the coating, achieving a good combination of high adhesion and heat resistance. Detailed Implementation

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below; the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0030] Example 1:

[0031] This embodiment provides a hot-melt ultra-high viscosity modified bitumen waterproof coating, specifically including the preparation of a multifunctional reactive thickening modifier and the preparation of the waterproof coating;

[0032] Preparation of multifunctional reactive thickening modifiers:

[0033] S1. 200g of hydroxyl-terminated polybutadiene with a number-average molecular weight of 2500 was added to a three-necked flask equipped with a mechanical stirrer, thermometer, and condenser. The mixture was dehydrated under vacuum at 110℃ for 2 hours. After dehydration, the temperature was lowered to 60℃, and nitrogen gas was introduced for protection. 35.5g of isophorone diisocyanate and 0.10g of dibutyltin dilaurate were added, and the reaction was maintained at 60℃ for 3 hours to obtain isocyanate-terminated polyurethane-polybutadiene prepolymer. The mass fraction of isocyanate groups in the isocyanate-terminated polyurethane-polybutadiene prepolymer was measured to be 2.8%. This isocyanate-terminated polyurethane-polybutadiene prepolymer serves as the basic framework for subsequent grafting reactions. The active isocyanate groups at its ends can provide reaction sites for subsequent grafting of dopamine and silane coupling agents, ensuring that the modifier has multifunctional properties.

[0034] S2. Under light-protected and nitrogen-protected conditions, 15.2 g of dopamine hydrochloride was dissolved in 100 mL of anhydrous N,N-dimethylformamide, and 8.1 g of triethylamine was added. The mixture was stirred for 30 min, and the precipitated triethylamine hydrochloride was removed by filtration to obtain a free dopamine solution. This free dopamine solution removed the binding of the hydrochloride and released highly reactive amino groups, which could fully participate in the subsequent addition reaction, thereby introducing catechol groups with strong wet adhesion into the polymer molecular chain. This free dopamine solution was added dropwise to the isocyanate-terminated polyurethane-polybutadiene prepolymer obtained in step S1 at 0 °C, and the reaction was maintained at 5 °C for 2 h, so that the amino groups in the dopamine could undergo an addition reaction with some of the isocyanate groups.

[0035] S3. Heat the system to 40℃, add 8.8g of γ-aminopropyltriethoxysilane, and continue the reaction for 1 hour; confirm the reaction temperature at 2270℃ using infrared detection. The characteristic absorption peak of the terminal isocyanate group disappears;

[0036] S4. The solvent was removed by vacuum distillation at 60℃ to obtain a dark brown, viscous, multifunctional reactive thickening modifier, denoted as MD-1. The yield of this modifier was calculated to be 96.5%. Surface elemental analysis of MD-1 using X-ray photoelectron spectroscopy confirmed the presence of characteristic peaks for N1s and Si2p. Simultaneously, Fourier transform infrared spectroscopy confirmed the presence of peaks in the 3300-3400 cm⁻¹ range. -1 A distinct broad absorption peak for the phenolic hydroxyl group appeared in the range, as well as at 1080 cm⁻¹. -1 The presence of characteristic stretching vibration peaks of Si-OC nearby fully demonstrates the successful grafting of dopamine and silane coupling agent;

[0037] Preparation of waterproof coating:

[0038] By weight, take 50 parts of 70# road petroleum asphalt, 8 parts of naphthenic oil, 10 parts of styrene-butadiene-styrene block copolymer, 15 parts of talc, 10 parts of heavy calcium carbonate, 6 parts of MD-1, 0.2 parts of sulfur, 0.1 parts of tetramethylthiuram disulfide, and 0.3 parts of zinc oxide.

[0039] The base asphalt was heated to 175℃ to melt, and naphthenic oil was added and stirred evenly. Styrene-butadiene-styrene block copolymer was added in batches and stirred at 170℃ for 45 min to allow it to swell fully. The system was then transferred to a high-shear disperser and sheared at 4500 r / min for 50 min. The speed was reduced to 1000 r / min, and talc, heavy calcium carbonate, MD-1, sulfur, tetramethylthiuram disulfide, and zinc oxide were added in sequence. The mixture was kept at 165℃ for 1.5 h to develop. The mixture was then cooled to 140℃ and discharged to obtain a hot-melt ultra-high viscosity modified asphalt waterproof coating.

[0040] Example 2:

[0041] The difference between this embodiment and Embodiment 1 is that the raw material ratio and process parameters are adjusted to the lower limit of the range, while the other steps are the same;

[0042] Preparation of multifunctional reactive thickening modifiers:

[0043] 200g of hydroxyl-terminated polybutadiene with a number average molecular weight of 2000 was dehydrated under vacuum at 100℃ for 2h. After cooling to 60℃, a mixture of hydroxyl-terminated polybutadiene, isophorone diisocyanate, dopamine hydrochloride, and γ-aminopropyltriethoxysilane in a molar ratio of 1:1.5:0.5:0.5 was added under nitrogen protection. The amount of anhydrous N,N-dimethylformamide used to dissolve dopamine hydrochloride was adjusted to 62.5mL accordingly. The amount of triethylamine was adjusted to 5.06 g according to the equimolar ratio with dopamine hydrochloride; the amount of dibutyltin dilaurate catalyst was 0.05% of the mass of hydroxyl-terminated polybutadiene; the prepolymerization reaction was carried out for 3 h; the dopamine dropwise addition reaction temperature was controlled at 10 °C and the reaction was carried out for 2 h; after adding γ-aminopropyltriethoxysilane, the reaction was carried out at 40 °C for 1 h; the solvent was removed under reduced pressure at 60 °C to obtain the modifier MD-2, and the yield of the modifier was calculated to be 95.8% by weighing;

[0044] Preparation of waterproof coating:

[0045] By weight, take 40 parts of 70# road petroleum asphalt, 5 parts of aromatic oil, 5 parts of styrene-isoprene-styrene block copolymer, 10 parts of silica powder, 3 parts of MD-2, 0.1 parts of dicumyl peroxide, and 0.05 parts of tetramethylthiuram disulfide.

[0046] The base asphalt was heated to 170℃ and melted. Aromatic oil was added and stirred evenly. Styrene-isoprene-styrene block copolymer was added in batches and stirred at 170℃ for 40 min. Shearing was performed at 4000 r / min for 45 min. After the speed was reduced to 1000 r / min, silica powder, MD-2, dicumyl peroxide and tetramethylthiuram disulfide were added and the mixture was kept at 160℃ for 1.5 h. The mixture was then cooled to 140℃ and discharged.

[0047] Example 3:

[0048] The difference between this embodiment and Embodiment 1 is that an intermediate ratio and a different combination of fillers are used, while the other steps are the same;

[0049] Preparation of multifunctional reactive thickening modifiers:

[0050] 200g of hydroxyl-terminated polybutadiene with a number average molecular weight of 2500 was dehydrated under vacuum at 105℃ for 2h. After cooling to 60℃, raw materials prepared according to the molar ratio of hydroxyl-terminated polybutadiene, isophorone diisocyanate, dopamine hydrochloride, and γ-aminopropyltriethoxysilane 1:2.0:1.0:1.0 were added under nitrogen protection. The amount of anhydrous N,N-dimethylformamide used to dissolve dopamine hydrochloride was adjusted to 100mL, and the amount of triethylamine was adjusted to 8.1g according to the equimolar ratio with dopamine hydrochloride. The amount of dibutyltin dilaurate was 0.10% of the mass of hydroxyl-terminated polybutadiene. The prepolymerization reaction was carried out for 3.5h. The dopamine dropwise addition reaction temperature was controlled at 5℃ and the reaction was carried out for 2h. After adding γ-aminopropyltriethoxysilane, the reaction was carried out at 40℃ for 1h. The solvent was removed under reduced pressure at 60℃ to obtain the modifier MD-3.

[0051] Preparation of waterproof coating:

[0052] By weight, take 50 parts of 90# road petroleum asphalt, 9 parts of naphthenic oil, 9 parts of styrene-butadiene-styrene block copolymer, 12 parts of talc, 8 parts of heavy calcium carbonate, 2 parts of silica powder, 6 parts of MD-3, 0.25 parts of sulfur, 0.10 parts of tetramethylthiuram disulfide, and 0.25 parts of zinc oxide.

[0053] The base asphalt was heated to 175℃ and melted. Naphthenic oil was added and stirred evenly. Styrene-butadiene-styrene block copolymer was added in batches and stirred at 170℃ for 50 min. Shearing was carried out at 4500 r / min for 50 min. After the speed was reduced to 1000 r / min, all components were added and the mixture was kept at 165℃ for 1.8 h. The mixture was then cooled to 140℃ and discharged.

[0054] Example 4:

[0055] The difference between this embodiment and Embodiment 1 is that the upper limit of the raw material ratio and process parameters is adjusted, while the other steps are the same;

[0056] Preparation of multifunctional reactive thickening modifiers:

[0057] 200g of hydroxyl-terminated polybutadiene with a number average molecular weight of 3000 was dehydrated under vacuum at 110℃ for 2h; after cooling to 60℃, raw materials prepared in the molar ratio of hydroxyl-terminated polybutadiene, isophorone diisocyanate, dopamine hydrochloride, and γ-aminopropyltriethoxysilane 1:2.5:1.5:1.5 were added under nitrogen protection; the amount of dibutyltin dilaurate was 0.5% of the mass of hydroxyl-terminated polybutadiene; the prepolymerization reaction was carried out for 4h; the dopamine dropwise reaction was controlled at 0℃ and the reaction was carried out for 2h; after adding γ-aminopropyltriethoxysilane, the reaction was carried out at 40℃ for 1h; the solvent was removed under reduced pressure at 60℃ to obtain the modifier MD-4;

[0058] Preparation of waterproof coating:

[0059] By weight, take 60 parts of 90# road petroleum asphalt, 12 parts of naphthenic oil, 15 parts of styrene-butadiene-styrene block copolymer, 15 parts of talc, 10 parts of heavy calcium carbonate, 10 parts of MD-4, 1.0 part of sulfur, 0.2 parts of tetramethylthiuram disulfide, and 0.3 parts of zinc oxide.

[0060] The base asphalt was heated to 180℃ to melt, and naphthenic oil was added and stirred evenly. Styrene-butadiene-styrene block copolymer was added in batches and stirred at 170℃ for 60 min. Shearing was carried out at 5000 r / min for 60 min. After the speed was reduced to 1000 r / min, all components were added and the mixture was kept at 170℃ for 2 h to develop. The mixture was then cooled to 140℃ and discharged.

[0061] Comparative Example 1:

[0062] The difference between this comparative example and Example 1 is that the 6 parts of MD-1 in Example 1 are replaced with 6 parts of C9 petroleum resin, while the other raw material types, addition amounts, operating steps and process parameters are exactly the same as in Example 1.

[0063] Comparative Example 2:

[0064] The difference between this comparative example and Example 1 is that: in the preparation process of the multifunctional reactive thickening modifier, dopamine hydrochloride and triethylamine are omitted, while the other raw material types, addition amounts, operation steps and process parameters are exactly the same as in Example 1; in order to consume the same amount of residual terminal isocyanate groups, the amount of γ-aminopropyltriethoxysilane is increased accordingly in step S3 to obtain a comparative modifier without catechol groups, which is used to prepare waterproof coatings.

[0065] Comparative Example 3:

[0066] The difference between this comparative example and Example 1 is that in the preparation process of the multifunctional reactive thickening modifier, γ-aminopropyltriethoxysilane is replaced with an equimolar amount of n-butylamine. The other raw material types, addition amounts, operating steps and process parameters are exactly the same as in Example 1, resulting in a comparative modifier without siloxy groups, which is then used to prepare waterproof coatings.

[0067] Comparative Example 4:

[0068] The difference between this comparative example and Example 1 is that sulfur is omitted in the preparation of the waterproof coating, while the types of other raw materials, the amount added, the operating steps and the process parameters are exactly the same as in Example 1.

[0069] Comparative Example 5:

[0070] The difference between this comparative example and Example 1 is that the heat preservation and development temperature during the preparation of the waterproof coating is changed from 165℃ to 150℃, while the heat preservation and development time remains 1.5h. The other raw material types, addition amounts, operating steps, and process parameters are exactly the same as in Example 1.

[0071] Performance Testing and Datasheets

[0072] The coatings obtained in each embodiment and comparative example were applied to the surface of a C30 concrete slab. Samples were prepared with the same coating amount and then hot-melted into a film. The dry film thickness was controlled to be 1.5 mm. The test items included peel strength on a dry substrate, peel strength on a damp substrate, peel strength after heat aging at 80°C for 168 h, low-temperature flexibility, and heat resistance at 90°C. The moisture content of the damp substrate was controlled to be 8%. The peel strength test was conducted according to standard GB / T328.20, using a 180° tensile angle and a tensile rate of 50 mm / min. The low-temperature flexibility test was conducted according to standard GB / T328.14, using a bending shaft with a diameter of 20 mm. The heat resistance test was conducted according to standard GB / T328.11. In this specification, the number-average molecular weight of hydroxyl-terminated polybutadiene was determined by gel permeation chromatography, and the mass fraction of terminal isocyanate groups was determined by di-n-butylamine titration.

[0073] The sample performance test data for each embodiment and comparative example are shown in Table 1:

[0074] Table 1. Coating Performance Test Data

[0075]

[0076] As can be seen from the comparison of the test results of Example 1 and Comparative Example 1 in Table 1, after replacing the multifunctional reactive tackifier with C9 petroleum resin, the peel strength on dry substrate, peel strength on wet substrate, and peel strength after heat aging all decreased significantly, and the low-temperature flexibility also deteriorated. The underlying mechanism is that C9 petroleum resin only provides physical tackification and does not contain catechol groups and silanoxy groups that can interact with inorganic substrates, nor does it contain active double bonds of polybutadiene that can participate in in-situ crosslinking. This makes it difficult to form stable coordination bonds and condensation bonds at the interface, and it is also difficult to form a stable network structure inside the system. On wet substrates, the water film is difficult to be effectively dissipated, and the interfacial adhesion failure is more obvious. Under heat aging conditions, small molecule resins are prone to migration and precipitation, causing coating embrittlement, thus significantly deteriorating the relevant data.

[0077] As can be seen from the comparison of the test results of Example 1 and Comparative Example 2 in Table 1, after omitting dopamine grafting, the peel strength of the wet substrate decreased from 2.80 MPa to 1.10 MPa, and the wet retention rate was significantly reduced, while the decrease in peel strength after heat aging was relatively small. The underlying mechanism is that the catechol group is the key active structure for wet interface adhesion, which can form coordination with calcium ions, aluminum ions and iron ions in the concrete substrate and improve the wetting and displacement ability of the wet substrate. After the absence of this structure, the modifier can still participate in part of the interfacial bonding and system crosslinking by relying on silane oxygen and crosslinking double bonds. Therefore, the dry strength and aging retention rate are still maintained at a high level, but the wet adhesion ability is obviously insufficient.

[0078] As can be seen from the comparison of the test results of Example 1 and Comparative Example 3 in Table 1, after replacing γ-aminopropyltriethoxysilane with n-butylamine, the peel strength of both wet and dry substrates decreased, and the peel strength after thermal aging also decreased. The underlying mechanism is that silanoxy groups can be hydrolyzed to generate silanols during construction and service, and then condense with silanols on the surface of the concrete substrate to form stable chemical bonds. n-Butylamine only acts as a sealing agent and cannot provide inorganic substrate reaction sites, thus reducing the interfacial chemical bonding. Especially when the substrate contains trace amounts of moisture, the interfacial layer is more likely to become a weak area, resulting in a simultaneous decrease in wet and dry bond strength.

[0079] As can be seen from the comparison of the test results of Example 1 and Comparative Example 4 in Table 1, after omitting sulfur, the peel strength and low-temperature flexibility after heat aging are significantly reduced, and the peel strength of dry and wet substrates is also lower than that of Example 1. The underlying mechanism is that sulfur is an important component in constructing the in-situ crosslinking network, which can promote crosslinking between polybutadiene double bonds in the modifier, butadiene segments in styrene-butadiene-styrene block copolymers, and unsaturated components in asphalt. Without this component, although the modifier still contains interfacial active groups, it is difficult to be effectively fixed in the continuous phase of asphalt, the cohesive strength of the system decreases, and the segment movement and phase rearrangement are more obvious during heat aging. Therefore, the aging retention rate and low-temperature crack resistance are adversely affected.

[0080] As can be seen from the comparison of the test results of Example 1 and Comparative Example 5 in Table 1, after the heat preservation development temperature was reduced from 165℃ to 150℃, all bonding properties decreased, and the heat aging retention rate decreased significantly. The underlying mechanism is that the lower development temperature is not conducive to the full decomposition of the crosslinking agent and the full contact of the active segments, resulting in insufficient crosslinking reaction inside the system and a low interpenetrating network density. When the network construction is insufficient, the fixing effect between the modifier and the styrene-butadiene-styrene block copolymer and the asphalt is weakened, and the dispersion stability of the filler in the matrix also decreases. Therefore, it manifests as a decrease in initial adhesion and an accelerated decline in strength after aging.

[0081] As can be seen from the comparison of the test results of Examples 1 to 4 in Table 1, after adjusting the molecular weight of the terminal hydroxyl polybutadiene, the proportion of each monomer, the type of matrix asphalt, the type of elastomer, and the formulation ratio within the scope of the technical solution of the present invention, the resulting coatings all maintain excellent dry and wet substrate adhesion performance, aging retention rate, and low-temperature flexibility, indicating that the technical solution has stable feasibility. The comprehensive performance of Example 1 is better because the degree of grafting of the multifunctional reactive thickening modifier, the degree of silane end-capping, the amount of crosslinking agent, and the heat preservation and development conditions are well matched, and the interfacial bonding and the cohesive strength of the system are kept in a balanced state.

[0082] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any other way. Any person skilled in the art may make changes or modifications to the above-disclosed technical content to create equivalent embodiments for application in other fields. However, any conventional modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the technical solution of the present invention shall still fall within the protection scope of the technical solution of the present invention.

Claims

1. A hot-melt type ultra-high viscosity modified bitumen waterproof coating, characterized in that: The raw materials for preparing the waterproof coating, by weight, include: The mixture comprises: 40-60 parts of base asphalt; 5-15 parts of polymer elastomer modifier; 3-10 parts of multifunctional reactive thickening modifier; 5-12 parts of softening oil; 10-25 parts of filler; 0.1-1 part of crosslinking agent; and 0.05-0.5 parts of crosslinking accelerator. The multifunctional reactive thickening modifier is prepared by a method comprising the following steps: The hydroxyl-terminated polybutadiene, diisocyanate, dopamine hydrochloride, and aminosilane coupling agent are mixed in a molar ratio of 1:(1.5-2.5):(0.5-1.5):(0.5-1.5). The hydroxyl-terminated polybutadiene is then dehydrated under vacuum, cooled, and diisocyanate and a catalyst are added under nitrogen protection. The amount of catalyst is 0.05-0.5% of the mass of the hydroxyl-terminated polybutadiene. The reaction yields a polyurethane-polybutadiene prepolymer with terminal isocyanate. Under light-protected and nitrogen-protected conditions, dopamine hydrochloride was dissolved in an anhydrous organic solvent, an acid-binding agent was added, and the mixture was thoroughly stirred. The precipitate was removed by filtration to obtain a free dopamine solution. The free dopamine solution was then added dropwise to the isocyanate-terminated polyurethane-polybutadiene prepolymer for reaction. In the preparation step of the multifunctional reactive thickening modifier, the reaction temperature of the free dopamine solution added dropwise to the isocyanate-terminated polyurethane-polybutadiene prepolymer was 0-10℃, and the reaction time was 2 hours. After the reaction, the temperature was raised, and an aminosilane coupling agent was added to continue the reaction. The temperature at which the aminosilane coupling agent was added to continue the reaction was 40°C, and the time was 1 hour. After the reaction was completed, the anhydrous organic solvent was removed by vacuum distillation at 60°C to obtain the multifunctional reactive thickening modifier.

2. The hot-melt ultra-high viscosity modified bitumen waterproof coating as described in claim 1, characterized in that: In the preparation steps of the multifunctional reactive thickening modifier, the number average molecular weight of the hydroxyl-terminated polybutadiene is 2000-3000; the vacuum dehydration temperature is 100-110℃ and the time is 2h; the cooling temperature is reduced to 60℃; and the reaction time to obtain the isocyanate-terminated polyurethane-polybutadiene prepolymer is 3-4h.

3. The hot-melt ultra-high viscosity modified bitumen waterproof coating as described in claim 1, characterized in that: In the preparation steps of the multifunctional reactive thickening modifier, the diisocyanate is isophorone diisocyanate, the catalyst is dibutyltin dilaurate; the organic solvent is anhydrous N,N-dimethylformamide, the acid-binding agent is triethylamine, and the molar ratio of dopamine hydrochloride to triethylamine is 1:1; the aminosilane coupling agent is 3-aminopropyltriethoxysilane.

4. The hot-melt ultra-high viscosity modified bitumen waterproof coating as described in claim 1, characterized in that: The base asphalt is 70# or 90# road petroleum asphalt; the polymer elastomer modifier is styrene-butadiene-styrene block copolymer or styrene-isoprene-styrene block copolymer; and the softening oil is naphthenic oil or aromatic oil.

5. The hot-melt ultra-high viscosity modified bitumen waterproof coating as described in claim 1, characterized in that: The filler is one or more of talc, heavy calcium carbonate and silica powder; the crosslinking agent is sulfur or dicumyl peroxide; the crosslinking accelerator is one or a combination of tetramethylthiuram disulfide and zinc oxide.

6. A method for preparing a hot-melt ultra-high viscosity modified bitumen waterproof coating as described in any one of claims 1-5, characterized in that: Includes the following steps, The base asphalt is heated to melt, the softening oil is added and stirred evenly, and then the polymer elastomer modifier is added in batches, and the mixture is kept warm and stirred to allow it to swell fully; The system is transferred to a high-shear disperser for shear dispersion, so that the polymer elastomer modifier is dispersed in the matrix asphalt; Reduce the rotation speed and add the filler, the multifunctional reactive thickener modifier, the crosslinking agent and the crosslinking accelerator in sequence. Keep the mixture warm and allow it to develop, so that the multifunctional reactive thickener modifier, the polymer elastomer modifier and the base asphalt undergo a chemical crosslinking reaction. The material is cooled and discharged to obtain the hot-melt ultra-high viscosity modified asphalt waterproof coating.

7. The preparation method according to claim 6, characterized in that: The base asphalt is heated to a melting temperature of 170-180℃; the temperature for heat preservation and stirring is 170℃, and the time is 40-60 minutes.

8. The preparation method according to claim 6, characterized in that: The high-shear disperser operates at a speed of 4000-5000 r / min and a shearing and dispersion time of 45-60 min; the speed is then reduced to 1000 r / min.

9. The preparation method according to claim 6, characterized in that: The temperature for heat preservation and development is 160-170℃, and the time is 1.5-2 hours; the temperature for cooling and discharging is 140℃.

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