A highly elastic polyurethane-asphalt composite road crack repair material and its preparation method

Abstract

This invention relates to the field of building materials technology, specifically to a highly elastic polyurethane-asphalt composite road crack repair material and its preparation method, comprising the following raw materials: asphalt-based material, functionalized modified polyurethane, polyether-polyolefin block copolymer, functionalized rubber, 2,6-di-tert-butyl-4-methylphenol, and sodium polyacrylate. In this invention, the functionalized modified polyurethane introduces lipophilic functional groups into its molecular chain, enabling it to interact with the hydrocarbon groups in asphalt to form a more stable synergistic network structure, thereby effectively reducing phase separation between polyurethane and asphalt. This modified polyurethane not only improves the elasticity, flexibility, and temperature resistance of the composite material but also optimizes its processing performance, enhances interfacial bonding, and further improves the repair effect and road durability.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, and more specifically, to a highly elastic polyurethane-asphalt composite road crack repair material and its preparation method. Background Technology

[0002] Asphalt, as an important road construction material, possesses excellent compressive strength and durability. However, it is prone to embrittlement at low temperatures, lacking sufficient elasticity and toughness, leading to cracks and deformation in roads. Polyurethane, due to its excellent elasticity, wear resistance, and low-temperature performance, has become an important additive for enhancing the elasticity of asphalt. By compounding polyurethane with asphalt, the elasticity, crack resistance, and weather resistance of the material can be effectively improved, thereby increasing the service life of roads and driving safety. Existing technologies typically involve directly introducing polyurethane components into the asphalt system, utilizing the high elasticity of polyurethane to reinforce the asphalt and solve the problem of traditional asphalt cracking under low-temperature conditions. This method is not only simple but can also improve the flexibility, crack resistance, and high-temperature resistance of composite materials to a certain extent.

[0003] However, due to the significant differences between polyurethane and asphalt in polarity, phase structure, and thermal reaction conditions, it is difficult for them to form a stable synergistic network structure. This leads to phase separation during the use of the material and insufficient interfacial bonding, which affects the overall performance of the composite material. In view of this, we propose a highly elastic polyurethane-asphalt composite road crack repair material and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide a highly elastic polyurethane-asphalt composite road crack repair material and its preparation method, in order to solve the problem mentioned in the background art that due to the significant differences between polyurethane and asphalt in polarity, phase structure and thermal reaction conditions, it is difficult for the two to form a stable synergistic network structure, which leads to phase separation and insufficient interfacial bonding during the use of the material, thus affecting the overall performance of the composite material.

[0005] This invention provides a highly elastic polyurethane-asphalt composite road crack repair material, comprising the following raw materials: asphalt-based material, functionalized modified polyurethane, polyether-polyolefin block copolymer, functionalized rubber, 2,6-di-tert-butyl-4-methylphenol, and sodium polyacrylate;

[0006] The functionalized modified polyurethane is prepared by introducing p-hexadecylaniline into the reaction system of polyether polyol and diphenylmethane diisocyanate to generate a prepolymer containing a lipophilic long chain, which is then extended by 1,4-butanediol.

[0007] Preferably, the composition includes 60-85 parts by weight of the asphalt-based material, 10-30 parts by weight of the functionalized modified polyurethane, 1-5 parts by weight of the polyether-polyolefin block copolymer, 5-15 parts by weight of the functionalized rubber, 0.1-1.0 parts by weight of 2,6-di-tert-butyl-4-methylphenol, and 0.5-2.0 parts by weight of sodium polyacrylate.

[0008] Preferably, the preparation method of the functionalized modified polyurethane is as follows:

[0009] Polyether polyol and p-hexadecylaniline are added to a reaction vessel, heated to 60-90℃ under nitrogen protection, mixed and dehydrated at a stirring speed of 200-400 rpm for 1-3 hours to obtain a polyol mixture.

[0010] A mixture of polyols was mixed with diphenylmethane diisocyanate and reacted at 70-100℃ with a stirring speed of 300-600 rpm for 2-5 hours to obtain a functionalized polyurethane prepolymer. Then, 1,4-butanediol was added and the mixture was stirred at 60-90℃ with a stirring speed of 200-500 rpm for 1-2 hours to carry out a chain growth reaction, thereby obtaining a functionalized modified polyurethane.

[0011] Preferably, the amount of p-hexadecylaniline added is 5-15% of the mass of the polyether polyol.

[0012] Preferably, the feeding ratio of the polyol mixture to diphenylmethane diisocyanate is controlled so that the molar ratio of NCO to OH is between 1.05 and 1.30.

[0013] Preferably, N,N-dimethylethanolamine is added during the preparation of the functionalized polyurethane prepolymer, and the amount added is 0.5-1.0% of the mass of the polyol mixture.

[0014] Preferably, the molar ratio of the amount of 1,4-butanediol added to the NCO groups in the prepolymer is 0.8-1.1.

[0015] On the other hand, the present invention provides a method for preparing a highly elastic polyurethane-asphalt composite road crack repair material, which includes the following steps:

[0016] S1.1 Weigh the raw materials according to their weight proportions;

[0017] S1.2. Heat the asphalt-based material to 120-150℃ to melt and flow it. Add the functionalized modified polyurethane under stirring conditions and mix for 30-60 minutes at a shear rate of 1000-3000 rpm. Then add the polyether-polyolefin block copolymer, functionalized rubber, 2,6-di-tert-butyl-4-methylphenol and sodium polyacrylate in sequence, and continue stirring and mixing for 20-40 minutes to obtain a high-elasticity polyurethane-asphalt composite road crack repair material.

[0018] Sodium polyacrylate needs to be pre-treated by drying before use: place it in a forced-air drying oven at 105±5℃ for 4-6 hours to dry it to a moisture content of less than 0.2wt%, and then place it in a desiccator to cool to room temperature for use.

[0019] Preferably, in S1.2, the functionalized rubber is selected from one or more of epoxidized natural rubber, carboxylated nitrile rubber, and maleic anhydride grafted rubber.

[0020] Preferably, in S1.2, the polyether-polyolefin block copolymer is an ethylene oxide-propylene oxide block copolymer or a polyether-polyethylene / polypropylene block copolymer.

[0021] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0022] In this invention, a highly elastic polyurethane-asphalt composite road crack repair material and its preparation method are disclosed. The functionalized modified polyurethane introduces lipophilic functional groups (such as p-hexadecylaniline) into the molecular chain, enabling it to interact with the hydrocarbon groups in the asphalt to form a more stable synergistic network structure, thereby effectively reducing the phase separation phenomenon between polyurethane and asphalt. This modified polyurethane not only improves the elasticity, flexibility, and temperature resistance and crack resistance of the composite material, but also optimizes the processing performance of the material, enhances the interfacial bonding force, and further improves the repair effect and road durability. Detailed Implementation

[0023] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0024] This invention provides a highly elastic polyurethane-asphalt composite road crack repair material, comprising the following raw materials: asphalt-based material, functionalized modified polyurethane, polyether-polyolefin block copolymer, functionalized rubber, 2,6-di-tert-butyl-4-methylphenol, and sodium polyacrylate;

[0025] The functionalized modified polyurethane is prepared by introducing p-hexadecylaniline into the reaction system of polyether polyol and diphenylmethane diisocyanate to generate a prepolymer containing a lipophilic long chain, which is then extended by 1,4-butanediol.

[0026] The polyether polyol (number average molecular weight of 3000 g / mol, hydroxyl value of 56 mg KOH / g) was purchased from Hubei Jusheng Technology Co., Ltd.

[0027] Hexadecylaniline (CAS No.: 79098-13-8) was purchased from Hubei Shishun Biotechnology Co., Ltd.

[0028] Diphenylmethane diisocyanate (CAS No.: 101-68-8) was purchased from Condis Chemical (Hubei) Co., Ltd.

[0029] 1,4-Butanediol (CAS No.: 110-63-4, purity: CP, 98%), 2,6-di-tert-butyl-4-methylphenol (CAS No.: 128-37-0), and sodium polyacrylate (CAS No.: 9003-04-7) were all purchased from Shanghai Yuanye Biotechnology Co., Ltd.

[0030] N,N-Dimethylethanolamine (CAS No.: 108-01-0) was purchased from Changzhou Guxu Chemical Co., Ltd.

[0031] The functionalized rubber is selected from one or more of epoxidized natural rubber, carboxylated nitrile rubber, and maleic anhydride grafted rubber, and is preferably epoxidized natural rubber in the embodiments of the present invention.

[0032] Epoxidized natural rubber (epoxide content 50%) was purchased from Shandong Senya New Materials Co., Ltd.

[0033] The polyether-polyolefin block copolymer is an ethylene oxide-propylene oxide block copolymer or a polyether-polyethylene / polypropylene block copolymer, and in this embodiment of the invention, an ethylene oxide-propylene oxide block copolymer is preferred.

[0034] The ethylene oxide-propylene oxide block copolymer (average molecular weight approximately 8350) was purchased from Nanjing Dulai Biotechnology Co., Ltd.

[0035] Example 1: A method for preparing a highly elastic polyurethane-asphalt composite road crack repair material, comprising the following steps:

[0036] S1.1 Weigh the following raw materials by weight: 60 parts by weight of asphalt-based material, 10 parts by weight of functionalized modified polyurethane, 1 part by weight of ethylene oxide-propylene oxide block copolymer, 5 parts by weight of epoxidized natural rubber, 0.1 parts by weight of 2,6-di-tert-butyl-4-methylphenol, and 0.5 parts by weight of sodium polyacrylate.

[0037] S1.2. Heat the asphalt-based material to 120°C to melt and flow it. Add the functionalized modified polyurethane under stirring conditions and mix for 30 minutes at a shear rate of 1000 rpm. Then add ethylene oxide-propylene oxide block copolymer, epoxidized natural rubber, 2,6-di-tert-butyl-4-methylphenol and sodium polyacrylate in sequence, and continue stirring and mixing for 20 minutes to obtain a high-elasticity polyurethane-asphalt composite road crack repair material.

[0038] The preparation method of functionalized modified polyurethane is as follows:

[0039] Polyether polyol and p-hexadecylaniline were added to a reactor, wherein the amount of p-hexadecylaniline added was 10% of the mass of polyether polyol. The mixture was heated to 60°C under nitrogen protection, and stirred at 200 rpm for 1 hour to obtain a polyol mixture.

[0040] A mixture of polyols was mixed with diphenylmethane diisocyanate (with the molar ratio of NCO to OH controlled at 1.18), and then N,N-dimethylethanolamine was added at a mass of 0.5% of the polyol mixture. The mixture was reacted at 70°C with a stirring speed of 300 rpm for 2 h to obtain a functionalized polyurethane prepolymer. Subsequently, 1,4-butanediol (with a molar ratio of 0.8 to the NCO groups in the prepolymer) was added, and the mixture was stirred at 60°C with a stirring speed of 200 rpm for 1 h to carry out a chain growth reaction, thereby obtaining a functionalized modified polyurethane.

[0041] Example 2: The difference between this example and Example 1 is that the amount of hexadecylaniline added is 5% of the mass of the polyether polyol.

[0042] Example 3: The difference between this example and Example 1 is that the amount of hexadecylaniline added is 15% of the mass of the polyether polyol.

[0043] Example 4: The difference between this example and Example 1 is that the feeding ratio of the polyol mixture and diphenylmethane diisocyanate is controlled at the molar ratio of NCO to OH at 1.05.

[0044] Example 5: The difference between this example and Example 1 is that the feeding ratio of the polyol mixture and diphenylmethane diisocyanate is controlled at the molar ratio of NCO to OH at 1.30.

[0045] The procedure for determining the interfacial bonding strength (shear strength) between polyurethane and asphalt is as follows: Functionalized modified polyurethane and standard base asphalt are heated to their respective process temperatures (e.g., polyurethane 80℃, asphalt 160℃). A small amount of polyurethane is then uniformly coated onto the clean fracture surface of a standard asphalt concrete specimen. This is quickly aligned and bonded to another identical specimen, with slight pressure applied. The specimen is cured at room temperature for 7 days to form a standard asphalt-polyurethane-asphalt "sandwich" lap shear specimen. The cured specimen is then installed in the shear fixture of a universal testing machine, ensuring the force-bearing surfaces are parallel. A shear force is applied at a constant displacement rate (e.g., 5 mm / min) until the bonded interface fails. The maximum load during the entire shearing process is recorded and divided by the bonded area of ​​the specimen to calculate the lap shear strength (unit: MPa). A higher value indicates a stronger interfacial bonding strength between the polyurethane and asphalt, and better compatibility.

[0046] Elastic recovery rate determination method (tensile-recovery cycle test): Functionalized modified polyurethane is cast and cured to form a standard dumbbell-shaped tensile specimen; the specimen is accurately clamped onto the fixture of a universal testing machine, and the gauge length is set; first, the specimen is stretched to a set strain (e.g., 100%, i.e., twice the original length) at a constant rate (e.g., 100 mm / min), and then immediately unloaded to zero force at the same rate; after unloading, the specimen is allowed to stand for a period of time (e.g., 1 minute), and its residual permanent deformation length is accurately measured; the elastic recovery rate is calculated using the following formula: Elastic recovery rate = [(total tensile length - permanent deformation length) / total tensile length] × 100%.

[0047] Thermal stability determination method (thermogravimetric analysis): Take a small amount of fully cured functionalized modified polyurethane powder (about 5-10 mg) and place it in the sample crucible of the thermogravimetric analyzer; under an inert gas atmosphere (such as nitrogen), heat from room temperature to 600°C or higher at a constant heating rate (such as 10°C / min), and the instrument continuously and accurately records the change in sample mass with temperature or time; from the obtained thermogravimetric curve, read the temperature corresponding to a 5% weight loss during heating. The higher this temperature, the better the heat resistance.

[0048] Table 1 Performance data of functionalized modified polyurethane

[0049]

[0050] Comparing Examples 1, 2, and 3 in Table 1, the interfacial bonding strength continuously improved (from 2.1 MPa to 3.2 MPa) as the amount of hexadecylaniline added increased from 5% to 15%. This is because the long-chain alkyl and aromatic groups introduced by hexadecylaniline greatly enhance the affinity between polyurethane and asphalt oil, thereby effectively improving compatibility.

[0051] Adding an appropriate amount (10%) has little effect on elasticity, but excessive amounts (15%) will lead to a significant decrease in elasticity. This is because excessive long-chain flexible groups will destroy the regular hard segment structure in polyurethane molecules and weaken its physical cross-linking points; thermal stability, on the other hand, increases slightly with the amount added.

[0052] Comparing Examples 1, 4, and 5 in Table 1, a lower NCO / OH ratio (1.05) means longer flexible soft segments and fewer hard segment crosslinks, thus the material exhibits the highest elastic recovery rate (95%), but the lowest thermal stability (290°C). Conversely, a high NCO / OH ratio (1.30) forms more thermally stable crosslinked structures such as urethane esters and introduces more aromatic rings into the main chain, increasing the thermal decomposition temperature (305°C). However, the excessively high crosslink density also restricts molecular chain movement, resulting in a significant decrease in elasticity to 85%.

[0053] The higher NCO / OH ratio (1.30) also results in stronger interfacial bonding; this is because there are more unreacted free NCO groups in the system, which can further react with asphalt or moisture, hydroxyl groups in the environment during high-temperature mixing and subsequent use to form stronger chemical bonds.

[0054] Example 6: A method for preparing a highly elastic polyurethane-asphalt composite road crack repair material, comprising the following steps:

[0055] S1.1 Weigh the following raw materials by weight: 70 parts by weight of asphalt-based material, 10 parts by weight of functionalized modified polyurethane, 3 parts by weight of ethylene oxide-propylene oxide block copolymer, 10 parts by weight of epoxidized natural rubber, 0.5 parts by weight of 2,6-di-tert-butyl-4-methylphenol, and 1.2 parts by weight of sodium polyacrylate.

[0056] S1.2. Heat the asphalt-based material to 130℃ to melt and flow it. Add the functionalized modified polyurethane under stirring conditions and mix for 45 minutes at a shear rate of 2000 rpm. Then add ethylene oxide-propylene oxide block copolymer, epoxidized natural rubber, 2,6-di-tert-butyl-4-methylphenol and sodium polyacrylate in sequence, and continue stirring and mixing for 30 minutes to obtain a high-elasticity polyurethane-asphalt composite road crack repair material.

[0057] The preparation method of functionalized modified polyurethane is as follows:

[0058] Polyether polyol and p-hexadecylaniline were added to a reactor, wherein the amount of p-hexadecylaniline added was 10% of the mass of polyether polyol. The mixture was heated to 75°C under nitrogen protection, and stirred at 300 rpm for 2 hours to obtain a polyol mixture.

[0059] A mixture of polyols was mixed with diphenylmethane diisocyanate (with the molar ratio of NCO to OH controlled at 1.18), and then N,N-dimethylethanolamine was added at a mass of 0.8% of the polyol mixture. The mixture was reacted at 85°C with a stirring speed of 400 rpm for 4 h to obtain a functionalized polyurethane prepolymer. Subsequently, 1,4-butanediol (with a molar ratio of 1.0 to the NCO groups in the prepolymer) was added, and the mixture was stirred at 75°C with a stirring speed of 400 rpm for 2 h to carry out a chain growth reaction, thereby obtaining a functionalized modified polyurethane.

[0060] Example 7: The difference between this example and Example 6 is that 20 parts by weight of functionalized modified polyurethane are used.

[0061] Example 8: The difference between this example and Example 6 is that 30 parts by weight of functionalized modified polyurethane are used.

[0062] Example 9: A method for preparing a highly elastic polyurethane-asphalt composite road crack repair material, comprising the following steps:

[0063] S1.1 Weigh the following raw materials by weight: 85 parts by weight of asphalt-based material, 20 parts by weight of functionalized modified polyurethane, 5 parts by weight of ethylene oxide-propylene oxide block copolymer, 15 parts by weight of epoxidized natural rubber, 1.0 part by weight of 2,6-di-tert-butyl-4-methylphenol, and 2.0 parts by weight of sodium polyacrylate.

[0064] S1.2. Heat the asphalt-based material to 150°C to melt and flow it. Add the functionalized modified polyurethane under stirring conditions and mix for 60 minutes at a shear rate of 3000 rpm. Then add ethylene oxide-propylene oxide block copolymer, epoxidized natural rubber, 2,6-di-tert-butyl-4-methylphenol and sodium polyacrylate in sequence, and continue stirring and mixing for 40 minutes to obtain a high-elasticity polyurethane-asphalt composite road crack repair material.

[0065] The preparation method of functionalized modified polyurethane is as follows:

[0066] Polyether polyol and p-hexadecylaniline were added to a reactor, wherein the amount of p-hexadecylaniline added was 10% of the mass of polyether polyol. The mixture was heated to 75°C under nitrogen protection, and stirred at 300 rpm for 2 hours to obtain a polyol mixture.

[0067] A mixture of polyols was mixed with diphenylmethane diisocyanate (with the molar ratio of NCO to OH controlled at 1.18), and then N,N-dimethylethanolamine was added at a mass of 0.8% of the polyol mixture. The mixture was reacted at 85°C with a stirring speed of 400 rpm for 4 h to obtain a functionalized polyurethane prepolymer. Subsequently, 1,4-butanediol (with a molar ratio of 1.0 to the NCO groups in the prepolymer) was added, and the mixture was stirred at 75°C with a stirring speed of 400 rpm for 2 h to carry out a chain growth reaction, thereby obtaining a functionalized modified polyurethane.

[0068] Procedure for determining interfacial bond strength: While the prepared repair material is still hot, pour it into a specially made metal or plastic mold to form a disc-shaped sample with a diameter of approximately 10 mm and a thickness of approximately 2 mm. Simultaneously, prepare two clean, dry standard asphalt mixture rutting slab specimens (or concrete blocks). Heat the two rutting slab specimens in an oven to 140°C. After removing them, quickly place the prepared repair material disc at the center of one surface. Immediately align and press the other specimen down, applying constant pressure. Cool to room temperature and cure for at least 24 hours to ensure a strong bond between the three components. The bonded composite specimen is placed in a constant temperature environment of -10℃ for at least 4 hours. Then, it is mounted on a universal testing machine, and a special pull-out head is used to apply a vertical upward pull force at a constant rate (e.g., 10 mm / min) to the area of ​​the repair material until the specimen fails at the bonding interface or inside the material. The maximum pull-out force is recorded and divided by the bonding area to calculate the low-temperature bond strength (unit: MPa). This strength value directly reflects the interfacial bonding ability between the repair material and the old pavement, as well as the anti-debonding and anti-cracking performance at low temperatures.

[0069] High-Temperature Stability (Rutting Factor) Determination Procedure: Heat the composite remediation material to a fluid state, pour or coat it onto a parallel plate fixture with a diameter of 25 mm or 8 mm, forming a sample layer approximately 1 mm or 2 mm thick; based on the material's estimated applicable temperature range (e.g., 30°C to 80°C), set at least four reasonably spaced test temperature points in the DSR software; install the fixture system containing the sample into the instrument and rapidly raise the temperature to the first target test temperature, holding it at that temperature for at least 1 minute to ensure temperature uniformity; perform a time scan of the sample at each set temperature point; typically, an appropriate temperature is used... In variable control mode (strain value set between 5% and 12%), sinusoidal alternating shear stress is applied at a fixed angular frequency (usually 10 rad / s, approximately 1.59 Hz), with a scanning time of 10-20 seconds. The instrument automatically records the complex shear modulus (G*) of the specimen resisting deformation and the phase angle (δ) between stress and strain at this temperature and frequency. The rutting factor is calculated: the DSR system software automatically calculates the rutting factor = G* / sinδ based on the collected G* and δ. This value directly reflects the material's ability to resist permanent deformation at high temperatures; the larger the value, the better the high-temperature stability.

[0070] Table 2 Performance data of high-elasticity polyurethane-asphalt composite road crack repair materials

[0071]

[0072] As shown in Table 2, the interfacial bonding strength increases linearly with the increase of functionalized modified polyurethane content (from 2.8 MPa to 4.0 MPa). This is because the functionalized modified polyurethane has more active sites at its terminal -NCO groups that can react chemically with active components in asphalt (such as carboxylic acid and sulfoxide) and the surface of aggregates, forming stronger covalent bonds. At the same time, more polyurethane molecules form a denser and more continuous interpenetrating network in the asphalt, which greatly enhances the physical anchoring and stress transfer efficiency.

[0073] High-temperature stability (rutting factor) increases dramatically with increasing content of functionalized modified polyurethane (from 4500 Pa to 8500 Pa). This is because polyurethane, especially its aromatic hard segments (derived from MDI), can form strong physical cross-linking points at high temperatures; the higher the doping content, the stronger and tougher this three-dimensional network skeleton composed of rigid segments becomes.

[0074] The elastic recovery rate first increases and then decreases with the increase of functionalized modified polyurethane content. In the rising stage (10 to 20 parts), an appropriate amount of polyurethane can form a complete and flexible elastic network. Its -NH-COO- soft segment (derived from polyether polyol and chain extender) provides excellent resilience and makes up for the viscoplasticity defects of pure asphalt.

[0075] During the descent phase (20 to 30 parts), excessive polyurethane can lead to excessively high crosslinking density in the system, restricting the movement of molecular chains and causing the material to harden. At the same time, the compatibility of polyurethane with other components such as asphalt and rubber will reach its limit, resulting in micro-phase separation, internal defects, and energy consumption during repeated stretching and recovery, which manifests as a decrease in elasticity.

[0076] Based on the above measurements, Example 7 provides the highest elastic recovery rate while maintaining excellent adhesion and high-temperature performance, and has the most balanced overall road performance. Therefore, Example 7 is selected as the optimal example.

[0077] Comparative Example 1: The difference between this example and Example 7 is that polyurethane is used instead of functionalized modified polyurethane.

[0078] Comparative Example 2: The difference between this example and Example 7 is that p-hexadecylaniline was not added.

[0079] Comparative Example 3: The difference between this example and Example 7 is that N,N-dimethylethanolamine was not added.

[0080] Table 3 Performance data of high-elasticity polyurethane-asphalt composite road crack repair material

[0081]

[0082] Compared with Example 7, Comparative Examples 1-2 showed a sharp decrease in interfacial bonding strength and a reduction in high-temperature stability. Ordinary polyurethane (Comparative Example 1) or unmodified polyurethane (Comparative Example 2) had a large difference in polarity with asphalt and poor compatibility, making it impossible to form effective molecular-level interpenetration and strong interfacial bonding. As a result, the two-phase interface was weak, the stress transfer efficiency was low, and the bonding and high-temperature performance deteriorated significantly.

[0083] Compared with Example 7, Comparative Example 3 showed a significant decrease in elastic recovery rate, while other properties also showed slight deterioration. N,N-dimethylethanolamine, as a reaction catalyst, can improve the polymerization rate and uniformity. Its absence leads to incomplete and uneven reaction between the polyurethane prepolymer and the chain extender, resulting in defects or insufficient branching in the final three-dimensional elastic network. This incomplete network is more prone to irreversible plastic deformation under stress, thus reducing the elastic recovery rate.

[0084] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely preferred examples and are not intended to limit the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A highly elastic polyurethane-asphalt composite road crack repair material, characterized in that, The product comprises the following raw materials: 60-85 parts by weight of asphalt-based material, 10-30 parts by weight of functionalized modified polyurethane, 1-5 parts by weight of ethylene oxide-propylene oxide block copolymer, 5-15 parts by weight of functionalized rubber, 0.1-1.0 parts by weight of 2,6-di-tert-butyl-4-methylphenol, and 0.5-2.0 parts by weight of sodium polyacrylate. The functionalized modified polyurethane is prepared by introducing p-hexadecylaniline into the reaction system of polyether polyol and diphenylmethane diisocyanate to generate a prepolymer containing a lipophilic long chain, which is then chain extended with 1,4-butanediol. The preparation method of the functionalized modified polyurethane is as follows: Polyether polyol and p-hexadecylaniline are added to a reaction vessel, heated to 60-90℃ under nitrogen protection, mixed and dehydrated at a stirring speed of 200-400 rpm for 1-3 hours to obtain a polyol mixture. A mixture of polyols was mixed with diphenylmethane diisocyanate and reacted at 70-100℃ with a stirring speed of 300-600 rpm for 2-5 hours to obtain a functionalized polyurethane prepolymer; then 1,4-butanediol was added and the mixture was stirred at 60-90℃ with a stirring speed of 200-500 rpm for 1-2 hours to carry out a chain growth reaction to obtain a functionalized modified polyurethane. The amount of p-hexadecylaniline added is 5-15% of the mass of the polyether polyol; The feeding ratio of the polyol mixture to diphenylmethane diisocyanate is controlled to have a molar ratio of NCO to OH of 1.05-1.30; In the preparation of functionalized polyurethane prepolymer, N,N-dimethylethanolamine is added, and the amount added is 0.5-1.0% of the mass of the polyol mixture.

2. The high-elasticity polyurethane-asphalt composite road crack repair material according to claim 1, characterized in that, The molar ratio of the amount of 1,4-butanediol added to the NCO groups in the prepolymer is 0.8-1.

1.

3. A method for preparing a high-elasticity polyurethane-asphalt composite road crack repair material, used to prepare the high-elasticity polyurethane-asphalt composite road crack repair material as described in any one of claims 1-2, characterized in that, The preparation method is as follows: S1.1 Weigh the raw materials according to their weight proportions; S1.

2. Heat the asphalt-based material to 120-150℃ to melt and flow it. Add the functionalized modified polyurethane under stirring conditions and mix for 30-60 minutes at a shear rate of 1000-3000 rpm. Then add ethylene oxide-propylene oxide block copolymer, functionalized rubber, 2,6-di-tert-butyl-4-methylphenol and sodium polyacrylate in sequence, and continue stirring and mixing for 20-40 minutes to obtain a high-elasticity polyurethane-asphalt composite road crack repair material.

4. The preparation method of the high-elasticity polyurethane-asphalt composite road crack repair material according to claim 3, characterized in that, In S1.2, the functionalized rubber is selected from one or more of epoxidized natural rubber, carboxylated nitrile rubber, and maleic anhydride grafted rubber.

Images