Epoxy-terminated polyurethane toughener for bridge and tunnel pavements, and preparation method therefor and use method therefor

Abstract

The present invention relates to an epoxy-terminated polyurethane toughener for bridge and tunnel pavements, and a preparation method therefor and a use method therefor. The toughener is prepared by terminating a polyurethane prepolymer using an epoxy group of an epoxy compound under the catalytic action of nano-modified imidazole, wherein the epoxy groups react with NCO groups at the end part of the polyurethane prepolymer, and a five-membered ring structure with a high cohesive energy is introduced into a polyurethane molecular chain. The epoxy‑terminated toughening agent contains five‑membered ring structures in the main chain, which are formed at relatively low temperatures through the reaction between epoxy groups and isocyanate groups catalyzed by the nano‑modified imidazole. The five-membered ring has a relatively high cohesive energy and a relatively large steric hindrance effect, resulting in a good high- and low-temperature stability and a wide damping temperature range. After being cured, the toughener has a high-temperature rutting resistance, a medium-temperature fatigue resistance, and a low-temperature crack resistance, thereby solving the problem of the insufficient toughness of epoxy mixtures in conventional pavements.

Description

An epoxy end-sealing polyurethane toughening agent for bridge and tunnel pavement, its preparation and application method Technical Field

[0001] This invention relates to the field of bridge and tunnel paving materials technology, and in particular to an epoxy end-capping polyurethane toughening agent for bridge and tunnel paving, its preparation and application method. Background Technology

[0002] Epoxy resin, as a thermosetting polymer material, is widely used in bridge and tunnel pavement due to its excellent strength, adhesion, and high-temperature rutting resistance, representing a significant breakthrough in solving this global challenge. However, unmodified epoxy resin often suffers from excessive strength but insufficient toughness. This imbalance limits its performance in certain applications, particularly in bridge and tunnel pavement where high toughness and fatigue resistance are required.

[0003] To address this issue, the research team explored methods for modifying epoxy resin using polyurethane as a toughening agent. The flexibility of polyurethane combined with the rigidity of epoxy resin, through the formation of a synchronous interpenetrating network structure, achieves complementary properties between the two materials. This significantly improves the toughness of epoxy resin while maintaining its excellent mechanical properties. This modification method makes the application of epoxy resin in bridge and tunnel pavement more widespread and reliable.

[0004] However, unmodified polyurethane contains highly reactive NCO groups, which readily react with moisture in the air, leading to gelation and affecting the long-term storage stability of the material. Furthermore, during construction, the high reactivity of NCO groups with amine curing agents results in a short residence time for the mixture, making it difficult to meet the time window requirements for construction.

[0005] Chinese patent CN116854884A, a preliminary application of the research team, discloses a toughening agent for high-toughness epoxy resins used in road and bridge construction. This agent comprises a monohydroxy epoxy-terminated polyurethane prepolymer and a phenol-terminated polyurethane prepolymer in a mass ratio of 100:50-200. The agent achieves control over the mechanical properties of the modified epoxy resin binder by adjusting the ratio of the monohydroxy epoxy-terminated polyurethane prepolymer to the phenol-terminated polyurethane prepolymer in the toughening agent, thereby adjusting the synchronous interpenetrating network structure. However, the synthesis process of this toughening agent is relatively complex, requires high temperature precision, and is prone to resulting in low yield during production.

[0006] Therefore, developing toughening agents that are simple to manufacture, have a high yield, and meet the requirements for construction and workability is of great significance to the field of bridge and tunnel paving.

[0007] The information disclosed in this background section is intended only to enhance the understanding of the overall background of the present invention and should not be construed as an admission or in any way implying that the information constitutes prior art known to those skilled in the art. Summary of the Invention

[0008] The first objective of this invention is to provide an epoxy end-capping polyurethane toughening agent for bridge and tunnel pavement, used to toughen and modify epoxy resin to prepare a high- and low-temperature stable epoxy mixture for bridge and tunnel pavement, thereby solving the problem of insufficient toughness of epoxy mixtures in conventional pavement.

[0009] The above-mentioned technical objective of the present invention is achieved through the following technical solution:

[0010] An epoxy-terminated polyurethane toughening agent for bridge and tunnel paving is prepared by end-capping a polyurethane prepolymer with the epoxy groups of an epoxy compound under the catalysis of nano-modified imidazole.

[0011] In this process, the NCO groups at the ends of the polyurethane prepolymer preferentially react with epoxy groups under the action of nano-modified imidazole, introducing a five-membered ring structure into the polyurethane molecular chain. Based on the large steric hindrance and high cohesive energy of this structure, the toughness and high and low temperature stability of the material are significantly improved.

[0012] Furthermore, in the reaction, the molar ratio of epoxy groups to NCO groups at the ends of the polyurethane prepolymer is 2.00~2.05:1. To ensure that the epoxy groups can completely cap the isocyanate groups, the epoxy compound should be in slight excess to ensure that there is no NCO residue in the system.

[0013] Furthermore, the epoxy compound is one or more of E55, E51, and E44. To achieve epoxy end-capping of the isocyanate-terminated polyurethane prepolymer, this invention utilizes the reaction between the epoxy groups in the epoxy compound and the isocyanate groups in the terminal isocyanate groups to graft the epoxy compound onto the molecular structure of the polyurethane prepolymer, thereby achieving an epoxy-terminated polyurethane prepolymer.

[0014] The process route of this invention is designed with the following two-step reaction:

[0015] First step reaction:

[0016] ;

[0017] Second step reaction:

[0018] ;

[0019] Furthermore, the polyurethane prepolymer is prepared by reacting polyisocyanate and polyether polyol, wherein the molar ratio of NCO groups in the polyisocyanate to OH groups in the polyether polyol is 2.00~2.05:1.

[0020] Furthermore, the polyether polyol is one or more of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran ether diol.

[0021] Furthermore, the polyisocyanate is one or more of TDI, MDI, and HDI.

[0022] Furthermore, the dosage of nano-modified imidazole is 0.1wt%~0.5wt%. Due to the high cohesive energy of the five-membered ring formed after the reaction of epoxy groups with NCO, the energy barrier during the reaction is relatively large, which to some extent makes the reaction difficult. Although unmodified imidazole can lower the activation energy of the reaction between NCO and epoxy groups, the reaction temperature is still relatively high, and the isocyanate-terminated polyurethane prepolymers tend to self-polymerize under high temperature conditions. To promote the reaction between epoxy groups and NCO groups, nano-modified imidazole catalysts are preferred. Imidazole catalysts are loaded onto the surface of nanoparticles. Utilizing the good dispersibility, large specific surface area, and prominent quantum effects of nanoparticles, the catalytic reaction occurs at more catalytic centers, improving catalytic efficiency. This further reduces the difficulty of the reaction between epoxy groups in the epoxy compound and isocyanate groups in the isocyanate-terminated polyurethane prepolymers, inhibiting the self-polymerization reaction between isocyanate groups, and providing an effective route for preparing five-membered ring compounds with excellent performance.

[0023] Furthermore, the modified imidazole is a strong base. Under alkaline conditions, the active hydrogen atom on the secondary imidazole amine preferentially reacts with the highly reactive isocyanate group to form an urethane bond. Then, the nitrogen atom on the tertiary amine acts as a nucleophile and forms an active intermediate with the isocyanate group. The intermediate then undergoes addition with an epoxy group to form a five-membered ring structure. The temperature can be reduced by 15-35°C after catalysis by nano-modified imidazole. This temperature difference prevents most of the isocyanate groups from self-polymerizing, ensuring that isocyanate groups in the system can react with epoxy groups to form a five-membered ring structure.

[0024] Nanoparticles include silica (SiO2), titanium dioxide (TiO2), aluminum oxide (Al2O3), and zinc oxide (ZnO). Nanoparticles possess high specific surface area and excellent surface activity, serving to provide a highly dispersed support structure for imidazole. Through the interaction between nanoparticles and imidazole, the molecular structure and charge distribution of imidazole are altered, changing its catalytic activity and thus lowering the activation energy of the reaction, enabling the reaction to proceed efficiently at lower temperatures.

[0025] The second objective of this invention is to provide a method for preparing an epoxy end-capping polyurethane toughening agent for bridge and tunnel paving, which has the same technical effect.

[0026] The above-mentioned technical objective of the present invention is achieved by the following technical solution:

[0027] In step S1, the dehydrated polyol is placed in a reactor, and polyisocyanate is added in proportion. The reaction is carried out at 75±2℃ under N2 conditions until the NCO content in the synthesized product reaches the target value (1 / 2 of the initial NCO content), thus obtaining the isocyanate-terminated polyurethane prepolymer. Specifically, the target value here varies depending on the type of polyol and polyisocyanate. Reaching the target value (half of the initial value) indicates the formation of NCO-terminated polyurethane, which is a key indicator for determining whether this step of the reaction has reached its endpoint and whether the next step can proceed.

[0028] An epoxy compound and nano-modified imidazole are added to an S2-terminated isocyanate-based polyurethane prepolymer in a certain proportion, and then reacted at 160℃ under N2 conditions until the residual NCO content in the synthesized product is ≤0.1%, thus obtaining an epoxy-terminated polyurethane prepolymer.

[0029] Preferably, in step S1, the polyol is dehydrated at 105°C and under N2 conditions, and the polyisocyanate is gradually added dropwise to the dehydrated polyol according to a molar ratio of n(NCO) / n(OH) of 2.00~2.05 / 1, and reacted at 75±2°C and under N2 conditions until the NCO content in the synthesized product reaches the theoretical value, thereby obtaining the isocyanate-terminated polyurethane prepolymer;

[0030] Preferably, in step S2, an epoxy compound is added to the isocyanate-terminated polyurethane prepolymer in S1 at a ratio of n(NCO) / n(C2O) of 1 / 2.00~2.05, and 0.1wt%~0.5wt% of nano-modified imidazole is added. Then, the reaction is carried out at 120℃ and under N2 conditions until the residual NCO content in the synthesized product is ≤0.1%, thereby obtaining the epoxy-terminated polyurethane prepolymer.

[0031] The third objective of this invention is to provide a method for using an epoxy end-capping polyurethane toughening agent for bridge and tunnel pavement. The agent is mixed with liquid epoxy resin, reactive diluent, coupling agent, curing agent and other components to prepare an epoxy binder for bridge and tunnel pavement. The binder is then added to an asphalt mixing tank to prepare a high and low temperature stable epoxy mixture for bridge and tunnel pavement, which has the same technical effect.

[0032] The above-mentioned technical objective of the present invention is achieved by the following technical solution:

[0033] A method for using an epoxy end-sealing polyurethane toughening agent for bridge and tunnel pavement includes the following steps:

[0034] P1. Mix liquid epoxy resin, epoxy end-capping polyurethane toughening agent for bridge and tunnel pavement, reactive diluent and coupling agent evenly to obtain component A of bridge and tunnel pavement material.

[0035] P2. Mix the polyetheramine curing agent and the low molecular weight polyamide curing agent evenly to obtain component B of the bridge and tunnel pavement material.

[0036] P3. Mix the bridge and tunnel pavement material A component in P1 and the bridge and tunnel pavement material B component in P2 evenly to obtain the bridge and tunnel pavement material binder.

[0037] P4. Mix the bridge and tunnel pavement binder and graded stone materials in P3 evenly to obtain the bridge and tunnel pavement mixture.

[0038] Furthermore, the specific method for using an epoxy end-sealing polyurethane toughening agent for bridge and tunnel pavement is as follows:

[0039] P1. Weigh out liquid epoxy resin, epoxy end-capping polyurethane toughening agent for bridge and tunnel pavement, reactive diluent, coupling agent and other components in a ratio of 10~20:70~80:10:1. Then gradually heat to 40~60℃ and stir for 1~3 hours to obtain component A of bridge and tunnel pavement material.

[0040] P2. Weigh out the polyetheramine curing agent and low molecular weight polyamide curing agent in a ratio of 1~2:1~2, then gradually heat to 40~60℃ and stir for 1~3 hours to obtain component B of the bridge and tunnel pavement material.

[0041] P3. Preheat the high-toughness epoxy A component of P1 and the high-toughness epoxy B component of P2 to 30~40℃ respectively. Then weigh the A component and the B component at a mass ratio of 2~4:1 and stir them for 1~3 minutes to obtain the bridge and tunnel pavement material binder.

[0042] P4. Add the high-toughness epoxy binder for road and bridge construction in P3 to the mixing tank in proportion and mix it evenly with the graded stone to obtain the bridge and tunnel pavement material mixture. The mass ratio between the graded stone and the high-toughness epoxy binder for road and bridge construction is 100:6.0~8.0.

[0043] By employing the above technical solution, the present invention has at least the following beneficial effects:

[0044] (1) This invention uses epoxy compounds to end-cap isocyanate-based polyurethanes, and the resulting toughening agent has an NCO content of less than 0.1%, which meets the requirements for long-term storage stability. Secondly, the toughening agent contains epoxy groups at both ends, which match the curing rate of epoxy resin and have good compatibility. In addition, while grafting epoxy groups, a five-membered ring structure with high cohesive energy is introduced into the main chain, which has good high and low temperature stability, thereby significantly broadening the damping temperature range of the modified epoxy material, enabling it to maintain excellent mechanical properties over a wide range of temperature changes in winter and summer. Furthermore, the five-membered ring has a large steric hindrance, which allows for a certain amount of space for movement between molecular chains. Under external forces, the molecular chains have enough space to slip and twist, thereby better dispersing and absorbing energy, further improving the toughness of the material.

[0045] (2) The present invention modifies imidazole catalysts with nanoparticles, which can significantly reduce the reaction energy barrier between isocyanate groups and epoxy groups, and lower the temperature threshold of the aforementioned end-capping reaction. Under normal temperature conditions, this reaction is usually difficult to carry out, while under high temperature conditions, isocyanate groups tend to undergo self-polymerization. Although ordinary imidazole catalysts can reduce the reaction energy barrier between the two, the reaction temperature is still relatively high. Nanoparticle-modified imidazole catalysts have the characteristics of large specific surface area and prominent quantum effect, which allows the catalytic reaction sites to occur on more catalytic centers, improves catalytic efficiency, further reduces the reaction temperature, avoids side reactions, and provides an effective way to prepare five-membered ring compounds with excellent performance.

[0046] (3) This invention allows for highly flexible molecular design of epoxy-terminated polyurethane toughening agents by adjusting the types and proportions of polyurethane and epoxy compounds. By adjusting the types and proportions, a series of toughening agents with five-membered ring structures can be customized. This structure, as a key performance enhancement unit, is closely related to the molecular properties of the selected epoxy compound. Epoxy compounds with different epoxy group contents, molecular weights, and functional group distributions can exhibit different reactivity and crosslinking abilities in the end-capping reaction. The resulting toughening agents with five-membered ring structures can be prepared by combining and matching according to actual application requirements, achieving adjustable and controllable performance parameters such as material strength, toughness, and fatigue performance. Attached Figure Description

[0047] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0048] Figure 1 is a schematic diagram of the five-membered ring structure in the toughening agent prepared by the present invention. Detailed Implementation

[0049] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0050] Sources of raw materials used in the examples:

[0051] Polyisocyanates: TDI-80, MDI-100, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0052] Polyols: PPG1000, PPG2000, PPG4000, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0053] Epoxy compounds: E51, E44, Sigma-Aldrich (Shanghai) Trading Co., Ltd.

[0054] Catalyst: Imidazole, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0055] Reactive diluents: XY748, XY622, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0056] Coupling agent: KH560, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0057] Polyetheramine: D230, D400, Huntsman Corporation, USA.

[0058] Low molecular weight polyamides: Versamid 115, Versamid 140, Huntsman Corporation, USA.

[0059] Example 1

[0060] An epoxy-terminated polyurethane toughening agent for bridge and tunnel pavement is disclosed. The toughening agent is prepared by end-capping a polyurethane prepolymer with the epoxy groups of epoxy compound E51 under the catalysis of nano-modified imidazole. In this process, the NCO groups at the end of the polyurethane prepolymer preferentially react with the epoxy groups under the action of nano-modified imidazole, introducing a five-membered ring structure as shown in Figure 1 into the polyurethane molecular chain. Based on the large steric hindrance and high cohesive energy of this structure, the toughness and high and low temperature stability of the material are significantly improved.

[0061] <Preparation of epoxy-end polyurethane toughening agents for bridge and tunnel pavement>

[0062] S1. After dehydrating PPG1000 at 105℃ and N2 for 2 hours, TDI-80 was uniformly dropped into the dehydrated PPG1000 over two hours at a molar ratio of n(NCO) / n(OH) of 2.05 / 1, and reacted at 75±2℃ and N2 until the NCO content in the synthesized product reached the theoretical value, thus obtaining the isocyanate-terminated polyurethane prepolymer.

[0063] S2, with a molar ratio of n(NCO) / n(C2O) of 1 / 2.05, E51 was added to the isocyanate-based polyurethane prepolymer in S1, along with 0.1 wt% of catalyst-modified imidazole. The reaction was then carried out at 120 °C under N2 conditions until the residual NCO content in the synthesized product was ≤0.1%, thus obtaining epoxy end-capping polyurethane toughening agent Z1 for bridge and tunnel pavement.

[0064] <Preparation of epoxy-sealed polyurethane binder for bridge and tunnel paving>

[0065] P1. Weigh the above raw materials in the following order according to the ratio of liquid epoxy: toughening agent Z1: reactive diluent: coupling agent = 10: 80: 10: 1, and stir and mix them at 60°C for 1 hour to obtain component A of bridge and tunnel pavement material.

[0066] P2. Weigh the above raw materials in sequence according to the ratio of polyetheramine curing agent D400: low molecular weight polyamide curing agent Versamid 115 = 1:1, and stir and mix them at 40°C for 1 hour to obtain the bridge and tunnel pavement material component B.

[0067] P3. Weigh out components A and B of the high-toughness epoxy for road and bridge construction at a mass ratio of 3:1, and mix them at room temperature for 2 minutes to obtain bridge and tunnel pavement binder B1. After curing for RT / 7 days, relevant performance tests are conducted, and the relevant performance is shown in Table 1.

[0068] <Preparation of epoxy-end-capped polyurethane compound for bridge and tunnel paving>

[0069] P4. After the above-prepared bridge and tunnel pavement material binder B1 is mixed evenly with the stone, bridge and tunnel pavement material mixture M1 is prepared. After RT / 7d curing, relevant performance tests are carried out, and the relevant performance is shown in Table 1.

[0070] Table 1 Performance test data in Example 1

[0071]

[0072] Example 2

[0073] <Preparation of epoxy-end polyurethane toughening agents for bridge and tunnel pavement>

[0074] S1. After dehydrating PPG2000 at 105℃ and N2 for 2 hours, TDI-80 was added dropwise to the dehydrated PPG2000 at a constant rate over two hours at a molar ratio of n(NCO) / n(OH) of 2.05 / 1. The mixture was then reacted at 75±2℃ and N2 until the NCO content in the synthesized product reached the theoretical value, thus obtaining the isocyanate-terminated polyurethane prepolymer.

[0075] S2, with a molar ratio of n(NCO) / n(C2O) of 1 / 2.05, E44 was added to the isocyanate-based polyurethane prepolymer in S1, along with 0.1 wt% of catalyst-modified imidazole. The reaction was then carried out at 120 °C under N2 conditions until the residual NCO content in the synthesized product was ≤0.1%, thus obtaining epoxy end-capping polyurethane toughening agent Z2 for bridge and tunnel pavement.

[0076] <Preparation of epoxy-sealed polyurethane binder for bridge and tunnel paving>

[0077] P1. Weigh the above raw materials in the following order according to the ratio of liquid epoxy: toughening agent Z1: reactive diluent: coupling agent = 10: 80: 10: 1, and stir and mix them at 60°C for 1 hour to obtain component A of bridge and tunnel pavement material.

[0078] P2. Weigh the above raw materials in sequence according to the ratio of polyetheramine curing agent D400: low molecular weight polyamide curing agent Versamid 115 = 1:1, and stir and mix them at 40°C for 1 hour to obtain the bridge and tunnel pavement material component B.

[0079] P3. Weigh out components A and B of the high-toughness epoxy for road and bridge construction at a mass ratio of 3:1, and mix them at room temperature for 2 minutes to obtain bridge and tunnel pavement binder B2. After curing for RT / 7 days, relevant performance tests are conducted, and the relevant performance is shown in Table 2.

[0080] <Preparation of epoxy-end-capped polyurethane compound for bridge and tunnel paving>

[0081] P4. After mixing the bridge and tunnel pavement binder B2 obtained above with the stone material evenly, bridge and tunnel pavement mixture M2 is prepared. After RT / 7d curing, relevant performance tests are carried out, and the relevant performance is shown in Table 2.

[0082] Table 2 Performance test data in Example 2

[0083]

[0084] Example 3

[0085] <Preparation of epoxy-end polyurethane toughening agents for bridge and tunnel pavement>

[0086] S1. After dehydrating PPG4000 at 105℃ and N2 for 2 hours, TDI-80 was added dropwise to the dehydrated PPG4000 at a constant rate over two hours at a molar ratio of n(NCO) / n(OH) of 2.05 / 1. The mixture was then reacted at 75±2℃ and N2 until the NCO content in the synthesized product reached the theoretical value, thus obtaining the isocyanate-terminated polyurethane prepolymer.

[0087] S2, with a molar ratio of n(NCO) / n(C2O) of 1 / 2.05, E51 was added to the isocyanate-based polyurethane prepolymer in S1, along with 0.1 wt% of catalyst-modified imidazole. The reaction was then carried out at 120 °C under N2 conditions until the residual NCO content in the synthesized product was ≤0.1%, thus obtaining epoxy end-capping polyurethane toughening agent Z1 for bridge and tunnel pavement.

[0088] <Preparation of epoxy-sealed polyurethane binder for bridge and tunnel paving>

[0089] P1. Weigh the above raw materials in the following order according to the ratio of liquid epoxy: toughening agent Z1: reactive diluent: coupling agent = 10: 80: 10: 1, and stir and mix them at 60°C for 1 hour to obtain component A of bridge and tunnel pavement material.

[0090] P2. Weigh the above raw materials in sequence according to the ratio of polyetheramine curing agent D400: low molecular weight polyamide curing agent Versamid 115 = 1:1, and stir and mix them at 40°C for 1 hour to obtain the bridge and tunnel pavement material component B.

[0091] P3. Weigh out components A and B of the high-toughness epoxy for road and bridge construction at a mass ratio of 3:1, and mix them at room temperature for 2 minutes to obtain bridge and tunnel pavement binder B1. After curing for RT / 7 days, relevant performance tests are conducted, and the relevant performance is shown in Table 1.

[0092] <Preparation of epoxy-end-capped polyurethane compound for bridge and tunnel paving>

[0093] P4. After mixing the bridge and tunnel pavement binder B1 prepared above with the stone material evenly, bridge and tunnel pavement mixture M1 is prepared. After RT / 7d curing, relevant performance tests are carried out, and the relevant performance is shown in Table 3.

[0094] Table 3 Performance test data in Example 3

[0095]

[0096] Example 4

[0097] <Preparation of epoxy-end polyurethane toughening agents for bridge and tunnel paving>

[0098] S1. After dehydrating PPG4000 at 105℃ and N2 for 2 hours, TDI-80 was added dropwise to the dehydrated PPG4000 at a molar ratio of n(NCO) / n(OH) of 2.00~2.05 / 1 over two hours, and the reaction was carried out at 75±2℃ and N2 until the NCO content in the synthesized product reached the theoretical value, thus obtaining the isocyanate-terminated polyurethane prepolymer.

[0099] S2, with a molar ratio of n(NCO) / n(C2O) of 1 / 2.00~2.05, E51 was added to the isocyanate-based polyurethane prepolymer in S1, along with 0.1wt% of catalyst-modified imidazole. The reaction was then carried out at 120℃ under N2 conditions until the residual NCO content in the synthesized product was ≤0.1%, thus obtaining epoxy end-capping polyurethane toughening agent Z1 for bridge and tunnel pavement.

[0100] <Preparation of epoxy-sealed polyurethane binder for bridge and tunnel paving>

[0101] P1. Weigh the above raw materials in the following order according to the ratio of liquid epoxy: toughening agent Z1: reactive diluent: coupling agent = 10: 80: 10: 1, and stir and mix them at 60°C for 1 hour to obtain component A of bridge and tunnel pavement material.

[0102] P2. Weigh the above raw materials in sequence according to the ratio of polyetheramine curing agent D400: low molecular weight polyamide curing agent Versamid 115 = 1:1, and stir and mix them at 40°C for 1 hour to obtain the bridge and tunnel pavement material component B.

[0103] P3. Weigh out components A and B of the high-toughness epoxy for road and bridge construction at a mass ratio of 3:1, and mix them at room temperature for 2 minutes to obtain bridge and tunnel pavement binder B1. After curing for RT / 7 days, relevant performance tests are conducted, and the relevant performance is shown in Table 1.

[0104] <Preparation of epoxy-end-capped polyurethane compound for bridge and tunnel paving>

[0105] P4. After mixing the above-prepared bridge and tunnel pavement binder B1 with the stone material evenly, bridge and tunnel pavement mixture M1 is prepared. After RT / 7d curing, relevant performance tests are conducted, and the relevant performance is shown in Table 3.

[0106] Table 4 Performance test data in Example 4

[0107]

[0108] Comparative Example 1

[0109] Compared to Example 1, the polyurethane toughening agent for bridge and tunnel pavement in Comparative Example 1 did not use epoxy compounds to end-cap the polyurethane; it was entirely composed of polyurethane with terminal isocyanate groups, and the remaining steps were the same as in Example 1. Because the polyurethane toughening agent contains highly reactive isocyanate groups, a gel reaction occurs approximately 10 minutes after mixing with an amine curing agent, which fails to meet the technical requirements for workability and ease of construction in bridge and tunnel pavement.

[0110] Table 5 Performance test data from Comparative Example 1

[0111]

[0112] Comparative Example 2

[0113] Compared to Example 2, in Comparative Example 2, the polyurethane toughening agent for bridge and tunnel pavement was modified with epoxy compounds without the addition of a catalyst. Consequently, the resulting toughening agent molecular chain did not form a five-membered ring structure, and the system contained a large number of unreacted epoxy compounds and isocyanate groups, failing to achieve the end-capping reaction. When mixed with an amine curing agent, a gel reaction occurred in approximately 15 minutes, failing to meet the technical requirements for workability and ease of construction in bridge and tunnel pavement.

[0114] Table 6 Performance test data from Comparative Example 2

[0115]

[0116] Comparative Example 3

[0117] Compared with Example 3, in Comparative Example 3, the catalyst added when the polyurethane toughening agent for bridge and tunnel pavement was modified with epoxy compound end-capping was unmodified imidazole. Although the addition of unmodified imidazole catalyst can reduce the activation energy of the reaction between NCO groups and epoxy groups, the temperature at which the two can react is still high. At 120°C, the NCO groups and epoxy groups in the system are still difficult to react, and a large number of isocyanate groups still exist in the system. When they are mixed with amine curing agents, a gel reaction occurs in about 25 minutes, which cannot meet the technical requirements of bridge and tunnel pavement for workability.

[0118] Table 7 Performance test data from Comparative Example 3

[0119]

[0120] Comparative Example 4

[0121] Compared with Example 4, the polyurethane toughening agent used in the bridge and tunnel pavement in Comparative Example 4 uses an oxime end-capping agent. Although the addition of the oxime end-capping agent can eliminate the NCO group in the system, it cannot form a five-membered ring structure with the polyurethane, nor does it introduce active epoxy groups at both ends of the polyurethane. Although the reactivity of the cured product is reduced, its toughness is poor and its damping temperature range is narrow.

[0122] Table 8 Performance test data from Comparative Example 4

[0123]

[0124] Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to this invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. An epoxy-terminated polyurethane flexibilizer for bridge deck pavement, characterized by, The toughening agent is prepared by capping the polyurethane prepolymer with the epoxy group of an epoxy compound under the catalysis of the nano-modified imidazole. The NCO group at the end of the polyurethane prepolymer is preferentially reacted with the epoxy group under the action of the nano-modified imidazole, and a five-membered ring structure is introduced into the polyurethane molecular chain.

2. The epoxy-terminated polyurethane flexibilizer for bridge deck pavement according to claim 1, characterized in that, In the reaction, the molar ratio of the epoxy group to the NCO group at the end of the polyurethane prepolymer is 2.00-2.05:

1.

3. The epoxy-terminated polyurethane flexibilizer for bridge deck pavement according to claim 1, characterized in that, The epoxy compound is one or more of E55, E51, and E44.

4. The epoxy-terminated polyurethane flexibilizer for bridge deck pavement according to claim 1, characterized in that, The polyurethane prepolymer is prepared by reacting a polyisocyanate and a polyether polyol, and the molar ratio of the NCO group in the polyisocyanate to the OH group in the polyether polyol is 2.00-2.05:

1.

5. The epoxy-terminated polyurethane flexibilizer for bridge deck pavement according to claim 4, characterized in that, The polyether polyol is one or more of polyethylene glycol, polypropylene glycol, and polytetrahydrofuran ether glycol.

6. The epoxy-terminated polyurethane flexibilizer for bridge deck pavement according to claim 4, characterized in that, The polyisocyanate is one or more of TDI, MDI, and HDI.

7. The epoxy-terminated polyurethane flexibilizer for bridge deck pavement according to claim 1, wherein The dosage of the nano-modified imidazole is 0.1wt%-0.5wt%, and the nano-modified imidazole is prepared by loading imidazole onto nanoparticles.

8. The method for preparing an epoxy-terminated polyurethane flexibilizer for bridge deck pavement according to any one of claims 1-7, characterized in that, The method comprises the following steps: S1: After water is removed, the polyol is placed in a reaction kettle, the polyisocyanate is added in proportion, and the reaction is carried out at 75±2℃ under N2 until the NCO content in the synthesis product reaches the target value (1 / 2 of the NCO content at the beginning of the reaction), to obtain an isocyanate-terminated polyurethane prepolymer; S2: The epoxy compound and the nano-modified imidazole are added to the isocyanate-terminated polyurethane prepolymer in proportion, and then the reaction is carried out at 120℃ under N2 until the residual NCO content in the synthesis product is ≤0.1%, to obtain an epoxy-capped polyurethane prepolymer.

9. The use of a bridge tunnel paving epoxy-terminated polyurethane flexibilizer according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: P1: Liquid epoxy resin, epoxy-capped polyurethane toughening agent, and other additives are mixed to obtain a bridge and tunnel paving material A component; P2: The polyether amine curing agent and the low molecular weight polyamide curing agent are stirred and uniformly mixed to obtain a bridge and tunnel paving material B component; P3: After the A component and the B component are stirred and uniformly mixed, a bridge and tunnel paving material binder is prepared; P4: The binder and the graded stone are stirred and uniformly mixed to prepare a bridge and tunnel paving material mixture.

10. The method of using a bridge deck pavement epoxy-terminated polyurethane flexibilizer according to claim 9, wherein, In step P1, the mass ratio of the liquid epoxy resin, the epoxy-capped polyurethane toughening agent, and the other additives is 10-20:70-80:10-15.

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