Reactive cationic asphalt emulsifier as well as preparation method and application thereof

Abstract

The invention discloses a reactive cationic asphalt emulsifier and a preparation method and application thereof, and belongs to the technical field of road engineering materials, the emulsifier has a [A]-[B]-[C] three-section structure, [A] is an epoxy chain segment, [B] is a polyether chain segment (which is a polyether flexible chain segment), and [C] is a polyamine and derivative chain segment thereof. Precise regulation and control of the performance of the emulsifier can be realized by regulating and controlling the type of epoxy resin, the types of polyamine and derivatives thereof, the molecular weight of polyether (such as polyethylene glycol diglycidyl ether) and the amine hydrogen / epoxy ratio. Emulsified asphalt prepared by adopting the emulsifier has the advantages of excellent storage stability, outstanding low-temperature ductility, firm interface bonding (forming a covalent bond with asphalt) and the like, and can be widely applied to road maintenance projects such as micro-surfacing, slurry seal and cold regeneration.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, and particularly relates to a reactive cationic asphalt emulsifier, its preparation method, and its application. Background Technology

[0002] Emulsified asphalt is an oil-in-water or water-in-oil emulsion formed by dispersing hot melt asphalt in water containing an emulsifier through mechanical shearing. It is widely used in road maintenance projects such as micro-surfacing, slurry seal, and cold recycling.

[0003] Traditional cationic asphalt emulsifiers are mostly small molecule compounds, such as alkylamines, quaternary ammonium salts, and imidazoline compounds. Although these emulsifiers can achieve asphalt emulsification, they have the following problems: (1) Small molecule emulsifiers are prone to migrate from the asphalt film, affecting road performance; (2) The low-temperature ductility of emulsified asphalt is significantly lower than that of base asphalt, usually decreasing by 40-60%; (3) The emulsification ability of high-viscosity asphalts such as SBS modified asphalt is insufficient; (4) Emulsified asphalt has poor storage stability and is prone to stratification and sedimentation.

[0004] To address the aforementioned issues, researchers have developed polymeric emulsifiers. CN118580511A discloses a hyperbranched resin polymer asphalt emulsifier with excellent properties such as high strength, high toughness, impact resistance, hydrophobicity, and corrosion resistance. CN120757692A discloses a polymeric asphalt emulsifier with good emulsifying ability. However, these emulsifiers are all non-reactive, exhibiting only physical adsorption with asphalt, resulting in limited interfacial bonding strength and insufficient long-term durability. Furthermore, CN 106883379A discloses a method for preparing a waterborne epoxy resin curing agent. This emulsifier is mainly used for curing reactions with waterborne epoxy resins; structurally, this waterborne epoxy resin curing agent has polyamine structures at both ends and does not involve the addition of acid for protonation, thus it is uncharged.

[0005] Therefore, developing a high-performance emulsifier with excellent storage stability, outstanding low-temperature performance, and the ability to form chemical bonds with asphalt has significant industrial application value. Summary of the Invention

[0006] To address the problems of insufficient low-temperature performance, weak interfacial bonding, and insufficient long-term durability of existing emulsifiers, this invention proposes a reactive cationic asphalt emulsifier, its preparation method, and its application.

[0007] To achieve the above objectives, the present invention provides the following technical solution: This invention provides a reactive cationic asphalt emulsifier having a three-segment structure of [A]-[B]-[C], wherein [A] is an epoxy segment, [B] is a polyether segment (which is a flexible polyether segment), and [C] is a polyamine and its derivative segment.

[0008] This invention achieves precise control over emulsifier performance by adjusting the type of epoxy resin, the type of polyamine and its derivatives, the molecular weight of polyether (such as polyethylene glycol diglycidyl ether), and the amine-to-epoxy ratio. This solves the problems of insufficient low-temperature performance, weak interfacial bonding, and insufficient long-term durability of existing emulsifiers. Specifically: existing conventional asphalt emulsifiers are mostly small-molecule emulsifiers, which are difficult to improve the flexibility of asphalt at low temperatures; secondly, conventional emulsifiers are prone to migration and accumulation on the asphalt surface under the influence of external moisture, leading to increased water absorption and affecting the interfacial adhesion of asphalt; furthermore, under long-term external moisture, moisture diffuses into the interior of the asphalt, causing asphalt performance degradation and thus affecting its long-term durability. The polyether segments in the emulsifier of this invention have good flexibility, improving the low-temperature ductility of the emulsifier; the epoxy groups have a certain polarity, enhancing the interfacial adhesion with aggregates such as mineral aggregates; the active groups (epoxy groups, imine groups) in the emulsifier can react with each other or with asphalt to form a cross-linked structure, improving the durability of emulsified asphalt. Emulsified asphalt prepared using the emulsifier of this invention has advantages such as excellent storage stability, outstanding low-temperature ductility, and strong interfacial bonding (forming covalent bonds with asphalt). It can be widely used in road maintenance projects such as micro-surfacing, slurry seal, and cold recycling.

[0009] Furthermore, the epoxy segment is composed of epoxy resin (EP), which is selected from at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and alicyclic epoxy resin, preferably bisphenol A type epoxy resin; The polyether segment is selected from at least one of polyethylene glycol (PEG) segments, polypropylene glycol segments, and polyethylene glycol-polypropylene glycol block copolymer segments, preferably polyethylene glycol (PEG) segments; The polyamine and its derivative segments contain nitrogen-containing cationic groups.

[0010] For example, the bisphenol A type epoxy resin is selected from E-44 epoxy resin, E-51 epoxy resin or E-20 epoxy resin.

[0011] Furthermore, the number-average molecular weight (Mn) of the polyether segments is 400-4000; The nitrogen-containing cation group is selected from at least one of primary amine salts, secondary amine salts, tertiary amine salts, quaternary ammonium salts, and imidazoline salts.

[0012] Furthermore, the reactive cationic asphalt emulsifier has a three-segment structure of [EP]-[PEG]-[PA], wherein [EP] is an epoxy segment, [PEG] is a polyethylene glycol segment, and [PA] is a polyamine and its derivative segment; The epoxy value of the epoxy resin is 0.2-0.6 mol / 100g, preferably 0.4-0.5 mol / 100g; the Mn of the polyethylene glycol segments is 600-2000, preferably 800-1500.

[0013] Furthermore, the polyamine and its derivatives are selected from one of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA).

[0014] For example, the polyethylene glycol segment is selected from polyethylene glycol diglycidyl ether.

[0015] Furthermore, the raw materials for the reactive cationic asphalt emulsifier are selected from one of the following compositions: E-44 epoxy resin, polyethylene glycol diglycidyl ether (Mn=1000), triethylenetetramine, triphenylphosphine, and hydrochloric acid; E-51 epoxy resin, polyethylene glycol diglycidyl ether (Mn=800), diethylenetriamine, triphenylphosphine, and hydrochloric acid; E-20 epoxy resin, polyethylene glycol diglycidyl ether (Mn=2000), tetraethylenepentamine, triphenylphosphine, and hydrochloric acid.

[0016] The present invention also provides a method for preparing the above-mentioned reactive cationic asphalt emulsifier, comprising the following steps: (1) The epoxy resin and the polymer that makes up the polyether segment are copolymerized in an organic solvent and a catalyst is added to catalyze the reaction to obtain an epoxy-polyether copolymer intermediate. (2) The epoxy-polyether copolymer intermediate obtained in step (1) is subjected to an amination reaction with polyamines and their derivatives. The reaction conditions are controlled to retain the epoxy group part, so as to obtain an amine-containing copolymer. (3) The amine-containing copolymer obtained in step (2) is protonated with a pH adjuster to adjust the pH to 1.5-3.5 to obtain the reactive cationic asphalt emulsifier.

[0017] Furthermore, in step (1), the copolymerization reaction is carried out at a temperature of 50-90°C for 2-6 hours; In step (1), the organic solvent is selected from at least one of anhydrous ethanol, isopropanol, isobutanol and propylene glycol methyl ether; In step (2), the amination reaction is carried out at a temperature of 40-80°C for 1-4 hours, and the molar ratio of amine hydrogen to epoxy is controlled to be 0.5:1 to 1.2:1, preferably 0.6:1 to 0.9:1. In step (3), the protonation treatment is performed at a temperature of 20-40°C for 0.5-2 hours.

[0018] Furthermore, the catalyst is selected from triphenylphosphine, triethylamine, and N,N-dimethylbenzylamine, and is used in an amount of 0.1-1% of the epoxy resin mass. The pH adjuster is selected from hydrochloric acid or phosphoric acid.

[0019] An exemplary method for preparing a reactive cationic asphalt emulsifier includes the following steps: (1) Epoxy resin and polyethylene glycol diglycidyl ether were copolymerized in the presence of triphenylphosphine to obtain an epoxy-polyether copolymer intermediate; (2) The intermediate obtained in step (1) is subjected to an amination reaction with polyamines and their derivatives. The reaction conditions are controlled to retain the epoxy group, and an amine-containing copolymer is obtained. (3) The product obtained in step (2) is protonated with hydrochloric acid and the pH is adjusted to 1.5-3.5 to obtain the target emulsifier.

[0020] This invention also provides the application of a reactive cationic asphalt emulsifier in the preparation of emulsified asphalt.

[0021] Compared with the prior art, the present invention has the following advantages and technical effects: 1. Excellent storage stability: Due to its high molecular structure and multiple charge centers, the reactive cationic asphalt emulsifier of this invention forms an emulsion with electrostatic repulsion and steric hindrance synergistic effect between particles. The storage stability is ≤1% after 5 days, which is far superior to the requirement of ≤5% in the national standard "Technical Specification for Construction of Highway Asphalt Pavement (JTG F40-2004)".

[0022] 2. Outstanding low-temperature performance: The introduction of polyether flexible segments significantly improves the low-temperature ductility of reactive cationic asphalt emulsifiers, with a ductility of ≥80cm at 15℃, which is more than 100% higher than traditional small molecule emulsifiers and 30-50% higher than existing polymeric emulsifiers.

[0023] 3. Strong interfacial bonding: The retained epoxy groups can form covalent bonds with the active groups (carboxyl groups, hydroxyl groups, etc.) in asphalt, increasing the interfacial shear strength by more than 50% and significantly enhancing the durability of the pavement.

[0024] 4. High process controllability: By adjusting the type of epoxy resin, polyamine chain length, PEG molecular weight and amine-to-epoxy ratio, the performance of the emulsifier can be precisely controlled to meet the needs of different application scenarios. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the molecular structure of the reactive cationic asphalt emulsifier of the present invention. Detailed Implementation

[0026] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0027] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0028] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0029] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0030] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0031] An embodiment of the present invention provides a reactive cationic asphalt emulsifier (molecular structure schematic diagram shown below). Figure 1As shown), it has a three-segment structure of [A]-[B]-[C], where [A] is an epoxy segment, [B] is a polyether segment (which is a flexible polyether segment), and [C] is a polyamine and its derivative segment.

[0032] In a preferred embodiment of the present invention, the epoxy segment is composed of epoxy resin, which is selected from at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and alicyclic epoxy resin, preferably bisphenol A type epoxy resin. The polyether segment is selected from at least one of polyethylene glycol (PEG) segments, polypropylene glycol segments, and polyethylene glycol-polypropylene glycol block copolymer segments, preferably polyethylene glycol (PEG) segments; Polyamines and their derivatives contain nitrogen-containing cationic groups in their chain segments.

[0033] For example, the bisphenol A type epoxy resin is selected from E-44 epoxy resin, E-51 epoxy resin or E-20 epoxy resin.

[0034] In a preferred embodiment of the present invention, the Mn of the polyether segment is 400-4000; The nitrogen-containing cation group is selected from at least one of primary amine salts, secondary amine salts, tertiary amine salts, quaternary ammonium salts, and imidazoline salts.

[0035] In a preferred embodiment of the present invention, the reactive cationic asphalt emulsifier has a three-segment structure of [EP]-[PEG]-[PA], wherein [EP] is an epoxy segment, [PEG] is a polyethylene glycol segment, and [PA] is a polyamine and its derivative segment; The epoxy value of the epoxy resin is 0.2-0.6 mol / 100g, preferably 0.4-0.5 mol / 100g; the Mn of the polyethylene glycol segments is 600-2000, preferably 800-1500.

[0036] In a preferred embodiment of the present invention, the polyamine and its derivatives are selected from one of ethylenediamine (EDA), diethylenetriamine (DETA), triethylenetetramine (TETA), and tetraethylenepentamine (TEPA).

[0037] For example, the polyethylene glycol segment is selected from polyethylene glycol diglycidyl ether.

[0038] In a preferred embodiment of the present invention, the raw material for the reactive cationic asphalt emulsifier is selected from one of the following compositions: E-44 epoxy resin, polyethylene glycol diglycidyl ether (Mn=1000), triethylenetetramine, triphenylphosphine, and hydrochloric acid; E-51 epoxy resin, polyethylene glycol diglycidyl ether (Mn=800), diethylenetriamine, triphenylphosphine, and hydrochloric acid; E-20 epoxy resin, polyethylene glycol diglycidyl ether (Mn=2000), tetraethylenepentamine, triphenylphosphine, and hydrochloric acid.

[0039] The present invention also provides a method for preparing the above-mentioned reactive cationic asphalt emulsifier, comprising the following steps: (1) The epoxy resin is copolymerized with the polymer organic solvent that makes up the polyether segment, and a catalyst is added for catalysis to obtain an epoxy-polyether copolymer intermediate; (2) The epoxy-polyether copolymer intermediate obtained in step (1) is subjected to an amination reaction with polyamines and their derivatives. The reaction conditions are controlled to retain the epoxy group part, so as to obtain an amine-containing copolymer. (3) The amine-containing copolymer obtained in step (2) is protonated with a pH adjuster to adjust the pH to 1.5-3.5 to obtain a reactive cationic asphalt emulsifier.

[0040] In a preferred embodiment of the present invention, in step (1), the temperature of the copolymerization reaction is 50-90°C and the time is 2-6 hours; In step (1), the organic solvent is selected from at least one of anhydrous ethanol, isopropanol, isobutanol and propylene glycol methyl ether; In step (2), the amination reaction is carried out at a temperature of 40-80℃ for 1-4 hours, and the molar ratio of amine hydrogen to epoxy is controlled to be 0.5:1 to 1.2:1, preferably 0.6:1 to 0.9:1. In step (3), the protonation treatment temperature is 20-40℃ and the time is 0.5-2 hours.

[0041] In a preferred embodiment of the present invention, the catalyst is selected from one of triphenylphosphine, triethylamine, and N,N-dimethylbenzylamine, and the amount of catalyst used is 0.1-1% of the mass of the epoxy resin; The pH adjuster is selected from hydrochloric acid or phosphoric acid, preferably hydrochloric acid.

[0042] An exemplary method for preparing a reactive cationic asphalt emulsifier includes the following steps: (1) Epoxy resin and polyethylene glycol diglycidyl ether were copolymerized in the presence of triphenylphosphine to obtain an epoxy-polyether copolymer intermediate; (2) The intermediate obtained in step (1) is subjected to an amination reaction with polyamines and their derivatives. The reaction conditions are controlled to retain the epoxy group, and an amine-containing copolymer is obtained. (3) The product obtained in step (2) is protonated with hydrochloric acid and the pH is adjusted to 1.5-3.5 to obtain the target emulsifier.

[0043] This invention also provides the application of a reactive cationic asphalt emulsifier in the preparation of emulsified asphalt.

[0044] In the emulsified asphalt of the present invention, the amount of reactive cationic asphalt emulsifier is 1-5% of the mass of the emulsified asphalt.

[0045] In a preferred embodiment of the present invention, the pH value of the emulsified asphalt is 1.5-4.0.

[0046] In a preferred embodiment of the present invention, the preparation method of emulsified asphalt is as follows: a reactive cationic asphalt emulsifier is mixed with water, and the pH is adjusted to 2.0-3.5 (preferably pH=2.5) to obtain a soap solution. The obtained soap solution is stirred and mixed evenly with the base asphalt under heating conditions (preferably by shear emulsification using a colloid mill) to obtain emulsified asphalt.

[0047] In the preparation method of emulsified asphalt of the present invention, the heating temperature is 120-140℃, preferably 130℃, and the stirring time is 3 minutes.

[0048] In the preparation method of emulsified asphalt of the present invention, the mass ratio of base asphalt to water is (5-7):(3-5), preferably 6:4.

[0049] For example, the base asphalt is 70# base asphalt.

[0050] The storage stability (5 days, 25℃) of the emulsified asphalt of this invention is ≤2%; the ductility of the evaporation residue at 15℃ is ≥60cm; and the softening point of the evaporation residue is ≥48℃.

[0051] The emulsified asphalt of the present invention can be used in road maintenance projects, including for microsurfacing, slurry seal, cold recycling, and fog seal.

[0052] In practical applications, the emulsified asphalt of this invention is mixed with aggregates, then spread and compacted.

[0053] Unless otherwise specified, the room temperature in this invention is 25±2℃.

[0054] All raw materials used in the embodiments of the present invention were obtained through commercial purchase.

[0055] It should be noted that any aspects not described in detail in this invention are conventional practices in the field and are not the focus of this invention.

[0056] The technical solution of the present invention will be further illustrated by the following embodiments.

[0057] Example 1: Preparation of E-44-PEG1000-TETA-HCl emulsifier 1.1 Raw Materials E-44 epoxy resin (epoxy value 0.44 mol / 100g): 100 g; Polyethylene glycol diglycidyl ether (PEG-DGE, Mn=1000): 50 g; Triethylenetetramine (TETA): 15 g; Triphenylphosphine (catalyst): 0.3 g; Hydrochloric acid (36% by mass, used as a pH adjuster): as needed; Anhydrous ethanol: 200 mL; Propylene glycol methyl ether: 150 mL; Deionized water: 200 mL.

[0058] 1.2 Preparation steps (1) Dissolve E-44 epoxy resin and PEG-DGE in 200 mL of anhydrous ethanol, add triphenylphosphine (0.5% of the mass of E-44 epoxy resin), heat to 80 °C under nitrogen protection, react for 4 hours, stop the reaction when the epoxy value drops to 60% of the initial value, remove the solvent by rotary evaporation, and obtain epoxy-polyether copolymer (EP-PEG) intermediate.

[0059] (2) Dissolve the EP-PEG intermediate in 150 mL of propylene glycol methyl ether, heat to 60 °C, add TETA dropwise, keep the reaction at the temperature for 2 hours, and stop the reaction when the epoxy value drops to 15% of the initial value (ammonia hydrogen / epoxy molar ratio = 0.8:1). Remove the solvent by rotary evaporation to obtain the amination product (EP-PEG-TETA).

[0060] (3) Disperse the amination product in 200 mL of deionized water, lower the temperature to 30 °C, add hydrochloric acid to adjust the pH to 2.5, and continue the reaction for 1 hour to obtain the target emulsifier (i.e., E-44-PEG1000-TETA-HCl emulsifier) ​​with a solid content of about 40%.

[0061] Emulsification performance test Mix the above emulsifier with water to prepare a 2.5% (mass concentration) aqueous solution, adjust the pH to 2.5, and then emulsify the above aqueous solution with 70# base asphalt heated to 130℃ (70# base asphalt: water = 6:4, mass ratio) by shearing for 3 minutes through a colloid mill to obtain emulsified asphalt (the emulsifier accounts for 2.5% of the mass of the emulsified asphalt).

[0062] Example 2 Preparation of E-51-PEG800-DETA-HCl emulsifier The method described in Example 1 differs in that: Epoxy resin: E-51 (epoxy value 0.51 mol / 100g); PEG-DGE: Mn=800; Polyamine: Diethylenetriamine (DETA) 10 g; Amine hydrogen / epoxy: 0.9:1 (molar ratio).

[0063] Example 3 Preparation of E-20-PEG2000-TEPA-HCl emulsifier The method described in Example 1 differs in that: Epoxy resin: E-20 (epoxy value 0.20 mol / 100g); PEG-DGE: Mn=2000; Polyamine: Tetraethylenepentamine (TEPA) 20 g; Amine hydrogen / epoxy: 0.7:1 (molar ratio).

[0064] Comparative Example 1: Traditional Small Molecule Cationic Emulsifiers Traditional small-molecule cationic emulsifier cetyltrimethylammonium bromide (CTAB) was selected as the emulsifier, with a dosage of 2.5 wt% (i.e., CTAB accounts for 2.5% of the total mass of emulsified asphalt), and pH=3.0 (i.e., the pH of CTAB was first adjusted to 3.0 before it was mixed with 70# base asphalt). Emulsified asphalt was prepared according to the same process as in Example 1.

[0065] The properties of the emulsified asphalt prepared in Examples 1-3 and Comparative Example 1 were tested according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering (JTG 3410-2025)". The results are shown in Table 1.

[0066] Table 1. Performance of emulsified asphalt in Examples 1-3 and Comparative Example 1 Based on the data in Table 1, we can see that: 1. The performance of the emulsified asphalt prepared by the reactive cationic asphalt emulsifiers of Examples 1-3 is significantly improved compared with that of the conventional small molecule cationic emulsifier in Comparative Example 1, which proves the superiority of the polymer chain segments (providing steric hindrance stability) and reactive epoxy groups (providing chemical bonding) of the present invention.

[0067] 2. The emulsified asphalt of Example 1 exhibits a relatively balanced performance in terms of storage stability, low-temperature ductility, softening point, and interfacial strength, and is the preferred solution among Examples 1-3.

[0068] 3. Although traditional small-molecule cationic emulsifiers are easy to emulsify, they can no longer meet the requirements of modern high-grade road construction in terms of long-term storage stability (4.5%), low-temperature adaptability (35cm), and durability (0.8MPa).

[0069] Examples 4-5: Different types of epoxy resin Following the method of Example 1, reactive cationic asphalt emulsifiers were prepared by changing only the type of epoxy resin. Emulsified asphalt was prepared according to the performance test of Example 1. The performance of emulsified asphalt with different epoxy resin types, including Example 1, is shown in Table 2.

[0070] Table 2 Properties of emulsified asphalt prepared with different epoxy resin types Examples 6-7: Different polyether segments Following the method of Example 1, reactive cationic asphalt emulsifiers were prepared by changing only the type of polyether segments. Emulsified asphalt was prepared according to the performance test of Example 1. The performance of emulsified asphalt with different epoxy resin types, including Example 1, is shown in Table 3.

[0071] Table 3. Properties of emulsified asphalt prepared with different polyether segment types Example 8: Optimization of Amine-to-Hydrogen / Epoxy Ratio Following the method of Example 1, a reactive cationic asphalt emulsifier was prepared by fixing the ratio of E-44 epoxy, PEG1000, and TETA and changing the amine-hydrogen / epoxy ratio (molar ratio). Emulsified asphalt was prepared according to the performance test of Example 1. The performance of emulsified asphalt with different amine-hydrogen / epoxy ratios, including Example 1, is shown in Table 4.

[0072] Table 4. Effect of different amine hydrogen / epoxy ratios on the properties of emulsified asphalt Based on the data in Table 4, we can see that: 1. Changes in epoxy retention rate As the amine-to-hydrogen / epoxy molar ratio (ammonia-to-hydrogen ratio) increased from 0.6:1 to 1.2:1, the epoxy retention rate continuously decreased from 45% to 8%. This is because a higher amine-to-hydrogen ratio results in a more complete amination reaction, with more epoxy groups being consumed by the ring-opening process of the amine, leading to a reduction in the amount of epoxy groups remaining in the intermediate. When the amine-to-hydrogen ratio is 0.6:1, the amount of amine is insufficient, and a significant amount of epoxy remains unreacted; while at 1.2:1, the amine is in excess, and the epoxy is almost completely consumed.

[0073] 2. Changes in storage stability Storage stability initially decreases and then increases, reaching its optimum at a ratio of 0.8:1 (0.9%). The reasons are as follows: 0.6:1: High epoxy retention rate, but low amination degree, fewer hydrophilic amine groups in the emulsifier molecule, resulting in insufficient emulsification ability, larger emulsion particles, and poor stability (1.8%).

[0074] 0.8:1: The epoxy retention rate is moderate (31%), while introducing a sufficient number of amine groups. The hydrophilic and lipophilic balance is good, and the residual epoxy can interact moderately with the asphalt in the future. The resulting emulsion particles are fine and uniform, and the synergistic effect of electrostatics and steric hindrance is the strongest. Therefore, the storage stability is optimal.

[0075] 1.0:1 and 1.2:1: The epoxy retention rate is too low, the emulsifier molecules lack sufficient hydrophobic epoxy segments, the hydrophilicity is too strong, and at the same time, the intermolecular cross-linking or aggregation may be caused by excessive amination, which will reduce the stability of the emulsion.

[0076] 3. Changes in low-temperature ductility The ductility at 15℃ peaked at a ratio of 0.8:1 (88 cm), decreasing with both excessively high and low ratios. This indicates that an appropriate amount of residual epoxy groups (approximately 31%) allows the emulsifier to form a suitable chemical bond with the asphalt, improving the asphalt's flexibility; simultaneously, the flexible segments of the PEG chain are fully utilized. When the epoxy retention rate is too high (45%), excessive residual epoxy in the emulsifier may lead to over-reaction with the asphalt, causing the system to become brittle and reducing the ductility (78 cm). When the epoxy retention rate is too low (8%-18%), the emulsifier almost loses its reactivity, with physical adsorption as the primary mode of interaction with the asphalt. Furthermore, its strong hydrophilicity may cause the residual emulsifier to have a plasticizing or destructive effect on the asphalt, further reducing the ductility.

[0077] 4. Changes in softening point The softening point decreased with increasing amine-to-hydrogen ratio, reaching its highest point (52.5℃) at 0.6:1 and its lowest point (49.2℃) at 1.2:1. This is because the emulsifier with a high epoxy retention rate (0.6:1) can crosslink the residual epoxy with the active groups in the asphalt after demulsification, improving the high-temperature stiffness of the residue. As the amine-to-hydrogen ratio increases, the epoxy retention rate decreases, this crosslinking effect weakens, and the softening point gradually decreases. At a ratio of 0.8:1, the softening point (52.3℃) still remains at a relatively high level, balancing high-temperature performance.

[0078] 5. Changes in interfacial shear strength The interfacial shear strength also peaked at 0.8:1 (2.2 MPa), showing a trend of first increasing and then decreasing. This is because: Interfacial strength depends on the balance between chemical bonding and physical adsorption between the emulsifier and the aggregate / asphalt. At a ratio of 0.6:1, there is more epoxy but fewer amine groups, resulting in insufficient hydrophilicity and incomplete adsorption of the emulsifier on the aggregate surface. Furthermore, excessive epoxy may lead to interfacial brittleness. At ratios of 1.0:1 and 1.2:1, there is too little epoxy, lacking sufficient reaction sites to form strong chemical bonds, resulting in weak physical adsorption as the dominant interface strength. At a ratio of 0.8:1, the number of amine groups and residual epoxy achieve the optimal match, allowing for the adsorption of negatively charged aggregate surfaces through amine cations and the formation of covalent bonds between residual epoxy and the active groups of asphalt and aggregate, thus achieving the strongest interfacial bonding.

[0079] Table 2 clearly shows that the amine-to-hydrogen (amineH) / epoxy ratio plays a crucial regulatory role in the structure and performance of the emulsifier. An amineH / epoxy ratio of 0.8:1 is optimal, at which the epoxy retention rate is approximately 31%, the emulsifier exhibits suitable hydrophilicity and reactivity, and the resulting emulsified asphalt exhibits the best overall performance: optimal storage stability (0.9%), highest low-temperature ductility (88 cm), and highest interfacial shear strength (2.2 MPa), while maintaining a high softening point (52.3℃).

[0080] Examples 9-10: PEG Molecular Weight Gradient Experiment Following the method of Example 1, a reactive cationic asphalt emulsifier was prepared by fixing the amounts of E-44 epoxy and TETA and changing the molecular weight of PEG-DGE. Emulsified asphalt was prepared according to the performance test of Example 1. The performance of emulsified asphalt with different molecular weights of PEG-DGE, including Example 1, is shown in Table 5.

[0081] Table 5. Effect of PEG-DGE molecular weight on emulsified asphalt properties As can be seen from the data in Table 5: 1. The effect of PEG molecular weight on storage stability As the number-average molecular weight of PEG increased from 600 to 2000, the 5-day storage stability of emulsified asphalt continuously improved from 1.8% to 0.5%, showing a clear positive correlation. The reasons are as follows: Enhanced steric hindrance effect: PEG segments are the hydrophilic portions of emulsifier molecules, extending into the aqueous phase in the emulsion system. The larger the PEG molecular weight, the longer its polyether chain, and the thicker the steric hindrance layer formed on the surface of asphalt particles. This three-dimensional barrier effectively prevents collision and aggregation between asphalt particles, thereby significantly improving the storage stability of the emulsion.

[0082] Enhanced interfacial membrane strength: The adsorption membrane formed by long-chain PEG molecules at the oil-water interface is more dense and flexible, which enhances the mechanical strength of the interfacial membrane and further inhibits particle aggregation.

[0083] Example 9 (Mn=600): The PEG chain segments are relatively short and the steric hindrance effect is limited. It mainly relies on electrostatic repulsion to maintain stability, so the stability is relatively poor (1.8%), but it is still better than traditional small molecule cationic emulsifiers (4.5% in Comparative Example 1).

[0084] Example 1 (Mn=1000): With a moderate PEG chain length, steric hindrance begins to play a significant role, and the stability is improved to 0.9%.

[0085] Example 10 (Mn=2000): The long PEG chain forms a strong steric barrier, achieving optimal stability (0.5%), which verifies the advantage of the "synergistic effect of electrostatic repulsion and steric hindrance" of the reactive cationic asphalt emulsifier of the present invention.

[0086] 2. Effect of PEG molecular weight on low-temperature ductility The ductility at 15℃ continuously increases with increasing PEG molecular weight: 76 cm⁻¹ for Mn=600, rising to 88 cm⁻¹ for Mn=1000, and reaching 94 cm⁻¹ for Mn=2000. The reasons are as follows: Toughening effect of flexible segments: PEG molecular chains have high flexibility and are typical soft segments. When these flexible segments are chemically bonded to emulsifier molecules and eventually enter asphalt residues, they can lower the glass transition temperature of asphalt and improve its flexibility and deformability at low temperatures.

[0087] Molecular chain length and toughening effect: The larger the molecular weight of PEG and the longer the chain segments, the stronger its flexibility and mobility, and the more significant its toughening effect on asphalt systems. Long-chain PEG can form a more effective flexible network or stress dispersion center in asphalt, absorb more energy under low-temperature stress, and delay crack propagation.

[0088] Example 9 (Mn=600): The PEG chain is shorter, resulting in limited toughening effect. The ductility is 76 cm, which is better than that of Comparative Example 1 (35 cm).

[0089] Example 10 (Mn=2000): The long PEG chain fully exerted its toughening effect, with an elongation of up to 94 cm, which is a further improvement compared to Example 1 (88 cm), demonstrating the technical effect of the polyether flexible segment in significantly improving low-temperature ductility.

[0090] 3. Effect of PEG molecular weight on softening point The softening point exhibits a fluctuating trend of first increasing and then decreasing with increasing PEG molecular weight: it is 51.2℃ when Mn=600, rises to 52.3℃ when Mn=1000, and decreases to 50.2℃ when Mn=2000. This is because the softening point is affected by two opposing factors: Crosslinking / interpenetrating network reinforcement effect: The epoxy groups in the emulsifier can react with the active components of asphalt to form chemical crosslinking or interpenetrating networks, improving high-temperature stiffness. The length of the PEG chain, as part of the molecular backbone, affects the spatial distribution and reactivity accessibility of the epoxy groups.

[0091] Flexible segment softening effect: PEG itself is a low-melting-point flexible segment. Excessive or excessively long PEG chains may have an internal plasticizing effect on the asphalt system, which reduces the high-temperature stiffness to a certain extent.

[0092] Example 9 (Mn=600): The PEG chain is relatively short and the plasticizing effect is weak, but the small steric hindrance may allow the epoxy groups to react more fully. The actual softening point is 51.2℃, which is moderate.

[0093] Example 1 (Mn=1000): The PEG length is moderate, achieving the best balance: it can improve ductility with moderate flexibility without excessively softening high-temperature performance; at the same time, the spatial distribution of epoxy groups is conducive to forming effective cross-links with asphalt, thus the softening point is the highest (52.3℃).

[0094] Example 10 (Mn=2000): Although the ductility is optimal, the excessively long PEG flexible chain may produce a significant internal plasticizing effect, which weakens the high-temperature network strength to some extent; or the long-chain PEG may "dilute" or shield some epoxy reaction sites, resulting in a decrease in crosslinking density, and thus the softening point drops back to 50.2℃.

[0095] Examples 11-13 Comparison of different polyamine types Following the method of Example 1, E-44 epoxy and PEG1000 were fixed, and reactive cationic asphalt emulsifiers were prepared by changing the polyamine type. Emulsified asphalt was prepared according to the performance test of Example 1. The performance of emulsified asphalt with different polyamine types, including Example 1, is shown in Table 6.

[0096] Table 6. Effect of Polyamine Type on Emulsified Asphalt Properties 1. The effect of polyamine type on storage stability As the polyamine chain length and number of amino groups increased (from EDA to TEPA), the 5-day storage stability of emulsified asphalt changed continuously from 3.2% to 0.7%. The reasons are as follows: Charge density increases: From EDA (2 amino groups) to TEPA (5 amino groups), the number of protonable amino groups in the molecule increases sequentially. After acidification with hydrochloric acid, these amino groups are converted into ammonium cations (NH4+). + This significantly increases the positive charge density carried by the emulsifier molecules. The higher charge density enhances the electrostatic repulsion between asphalt particles, effectively preventing particle aggregation.

[0097] Enhanced steric hindrance: As the polyamine chain length increases (EDA is short-chain, TEPA is long-chain), the volume of the hydrophilic head group of the emulsifier molecule increases. At the oil-water interface, these larger hydrophilic head groups form a thicker hydration layer and steric hindrance layer, further hindering particle collision and aggregation.

[0098] Synergistic effect: TETA and TEPA have both high charge density and large molecular volume, and the synergistic effect of electrostatic repulsion and steric hindrance is the strongest. Therefore, their storage stability is the best, far superior to EDA and DETA.

[0099] 2. The effect of polyamine type on low-temperature ductility The ductility at 15℃ initially increases and then decreases with increasing polyamine chain length, for the following reasons: Contribution to molecular chain flexibility: The ethylene (-CH2-CH2-) in polyamine molecules is a flexible segment. As the polyamine chain length increases (from EDA to TEPA), the number of flexible ethylene segments introduced into the emulsifier molecule increases. These flexible segments can play an internal toughening role after entering the asphalt system, improving low-temperature ductility.

[0100] Crosslinking density balance: Polyamines serve as both providers of hydrophilic groups and curing agents in the reaction with epoxy. Longer-chain polyamines (TETA, TEPA) can retain more unreacted amine groups after amination (for protonation), while the molecule itself can act as a flexible spacer. However, when the polyamine chain is too long (TEPA), the large degree of rotational freedom within the molecule or the excessive crosslinking / entanglement with residual epoxy may restrict the mobility of the macromolecular chain to some extent, resulting in a slight decrease in ductility compared to TETA.

[0101] Optimal chain length: TETA (triethylenetetramine) achieves the best balance between chain length and number of amine groups, providing sufficient flexible segments while maintaining a suitable crosslinking density, thus resulting in the highest low-temperature ductility.

[0102] 3. Effect of polyamine type on softening point The softening point initially increases and then decreases with increasing polyamine chain length, for the following reasons: Network structure formation capability: The reaction between polyamines and epoxy groups can form cross-linked or interpenetrating network structures. TETA molecules have a moderate length and suitable inter-amine spacing, which may be most conducive to forming moderately cross-linked three-dimensional networks. This improves high-temperature stiffness without excessively embrittled the system, thus resulting in the highest softening point.

[0103] Limitations of EDA: EDA chains are too short, and the spacing between crosslinking points formed after reacting with epoxy is small, which may lead to an overly dense network structure and greater brittleness. At the same time, its hydrophilic head groups are too small, resulting in poor emulsification effect. The residual emulsifier has limited contribution to the performance of asphalt, and it has the lowest softening point.

[0104] TEPA's softening effect: TEPA has the longest chain length and the most flexible ethylene units. Although it can form a network, the flexibility of the long chain segments may have a certain internal plasticizing effect on high-temperature performance; at the same time, too many amine groups may lead to excessive hydrophilicity, and the dispersion state of the emulsifier in asphalt changes, resulting in a slightly lower softening point than TETA.

[0105] DETA is in the middle: DETA's performance is between EDA and TETA, with a softening point of 51.2℃, which is moderate.

[0106] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A reactive cationic asphalt emulsifier, characterized in that, The reactive cationic asphalt emulsifier has a three-segment structure of [A]-[B]-[C], where [A] is an epoxy segment, [B] is a polyether segment, and [C] is a polyamine and its derivative segment.

2. The reactive cationic asphalt emulsifier according to claim 1, characterized in that, The epoxy segments are composed of epoxy resin, and the epoxy resin is selected from at least one of bisphenol A type epoxy resin, bisphenol F type epoxy resin and alicyclic epoxy resin; The polyether segment is selected from at least one of polyethylene glycol segments, polypropylene glycol segments, and polyethylene glycol-polypropylene glycol block copolymer segments; The polyamine and its derivative segments contain nitrogen-containing cationic groups.

3. The reactive cationic asphalt emulsifier according to claim 2, characterized in that, The number-average molecular weight of the polyether segments is 400-4000; The nitrogen-containing cation group is selected from at least one of primary amine salts, secondary amine salts, tertiary amine salts, quaternary ammonium salts, and imidazoline salts.

4. The reactive cationic asphalt emulsifier according to claim 1, characterized in that, The reactive cationic asphalt emulsifier has a three-segment structure of [EP]-[PEG]-[PA], wherein [EP] is an epoxy segment, [PEG] is a polyethylene glycol segment, and [PA] is a polyamine and its derivative segment; The epoxy value of the epoxy resin in the epoxy segments is 0.2-0.6 mol / 100g, and the number average molecular weight of the polyethylene glycol segments is 600-2000.

5. The reactive cationic asphalt emulsifier according to claim 4, characterized in that, The polyamine and its derivatives are selected from one of ethylenediamine, diethylenetriamine, triethylenetetramine, and tetraethylenepentamine.

6. The reactive cationic asphalt emulsifier according to claim 2, characterized in that, The bisphenol A type epoxy resin is selected from E-44 epoxy resin, E-51 epoxy resin or E-20 epoxy resin.

7. A method for preparing a reactive cationic asphalt emulsifier according to any one of claims 1-6, characterized in that, Includes the following steps: (1) The epoxy resin and the polymer that makes up the polyether segment are copolymerized in an organic solvent and a catalyst is added to catalyze the reaction to obtain an epoxy-polyether copolymer intermediate. (2) The epoxy-polyether copolymer intermediate obtained in step (1) is subjected to an amination reaction with polyamines and their derivatives. The reaction conditions are controlled to retain the epoxy group part, so as to obtain an amine-containing copolymer. (3) The amine-containing copolymer obtained in step (2) is protonated with a pH adjuster to adjust the pH to 1.5-3.5 to obtain the reactive cationic asphalt emulsifier.

8. The method for preparing the reactive cationic asphalt emulsifier according to claim 7, characterized in that, In step (1), the copolymerization reaction is carried out at a temperature of 50-90°C for 2-6 hours. In step (1), the organic solvent is selected from at least one of anhydrous ethanol, isopropanol, isobutanol and propylene glycol methyl ether; In step (2), the amination reaction is carried out at a temperature of 40-80°C for 1-4 hours, and the molar ratio of amine hydrogen to epoxy is controlled to be 0.5:1 to 1.2:

1. In step (3), the protonation treatment is performed at a temperature of 20-40°C for 0.5-2 hours.

9. The method for preparing the reactive cationic asphalt emulsifier according to claim 7, characterized in that, The catalyst is selected from triphenylphosphine, triethylamine, and N,N-dimethylbenzylamine, and is used in an amount of 0.1-1% of the epoxy resin mass. The pH adjuster is selected from hydrochloric acid or phosphoric acid.

10. The use of a reactive cationic asphalt emulsifier as described in any one of claims 1-6 in the preparation of emulsified asphalt.

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