Novel compound for synthesizing polyurethane asphalt cold patch material, high-cohesiveness polyurethane cold patch asphalt and preparation method of high-cohesiveness polyurethane cold patch asphalt

Abstract

The invention discloses a novel compound for synthesizing a polyurethane asphalt cold patch material, the compound is aromatic isocyanate simultaneously containing an epoxy group and a long-chain alkoxy group, the epoxy group is located at the ortho-position of the isocyanate group, and the long-chain alkoxy group is located at the para-position of the isocyanate group; the prepared novel compound has three groups. When the novel compound is used for preparing the polyurethane cold patch asphalt, polyhydric alcohols are not needed to be added into the system, the reaction can be carried out only by water, and the reaction rate is controlled by a catalyst. Isocyanate of the novel compound reacts with water for crosslinking to form a network structure, and epoxy groups are subjected to ring opening polymerization on the surface of alkaline aggregate or under the action of an amine curing agent to form a three-dimensional cross-linked network, so that the bonding performance and the compactness of the cold patch asphalt are effectively improved, the pit slot repairing quality is further improved, and the service life of a road is prolonged. The hydrophobic group and the water-resistant group of the novel compound can form a layer of waterproof film on the surface of the cold patch material after the cold patch asphalt forms strength, so that water is prevented from entering an interlayer interface to cause segregation of asphalt and aggregate.

Description

Technical Field

[0001] This invention relates to asphalt cold patching materials, specifically to a novel compound for synthesizing polyurethane asphalt cold patching material, high-adhesion polyurethane cold patching asphalt, and its preparation method. Background Technology

[0002] Asphalt pavement is widely used on highways of all grades due to its advantages such as strong adaptability, driving comfort, and simple maintenance. However, due to factors such as traffic load, natural environment, and service life, asphalt pavement will develop pavement defects such as potholes, ruts, and cracks. With the combined effects of rainwater infiltration and traffic load, the loss of fine aggregates in the structural layers will be further accelerated, leading to softening of the base or subbase layer and affecting the stability of the pavement structure. This not only reduces pavement smoothness and driving comfort, but also significantly reduces the service life of asphalt pavement, and in severe cases, threatens driving safety. Therefore, timely repair of potholes and other defects is necessary. Cold patching materials are all-weather, unaffected by rain, snow, or low temperatures, and do not require heating during use. They are energy-saving, environmentally friendly, and easy to apply, making them one of the mainstream materials for pavement repair. Cold patching asphalt is the key raw material that determines the performance of cold patching materials. However, in existing technologies, cold patching asphalt suffers from poor initial adhesion, insufficient early strength, and poor resistance to water damage, resulting in a shorter service life and limited application range.

[0003] Therefore, it is necessary to address the problems of poor initial adhesion, insufficient early strength, and poor water damage resistance in cold patch asphalt, improve the road performance of cold patch materials, and extend the service life of roads. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a novel compound for synthesizing polyurethane cold patch asphalt, high-adhesion polyurethane cold patch asphalt and its preparation method, which improves the road performance of cold patch asphalt by enhancing the initial adhesion, improving early strength and enhancing water damage resistance of the asphalt.

[0005] This invention relates to a novel compound for synthesizing polyurethane asphalt cold patching material. The compound is an aromatic isocyanate containing both an epoxy group and a long-chain alkoxy group, wherein the epoxy group is located at the ortho position of the isocyanate and the long-chain alkoxy group is located at the para position of the isocyanate.

[0006] Furthermore, the long-chain alkoxy group is a dodecyloxy group;

[0007] Furthermore, the compound is 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, with the following structural formula:

[0008] This invention also discloses a method for synthesizing a novel compound for synthesizing polyurethane asphalt cold patching material, comprising the following steps:

[0009] 4-Dodecyloxy-2-(2,3-epoxypropoxy)benzoic acid was synthesized from 2,4-dihydroxybenzoic acid to prepare epoxy acid solid products. Then, the epoxy acid solid products were subjected to acyl chlorination and Curtius rearrangement.

[0010] Furthermore, the following steps are included:

[0011] Step 1: 2,4-Dihydroxybenzoic acid, 1-bromododecane and K2CO3 were refluxed in anhydrous acetone and recrystallized. Then, the obtained 4-dodecyloxy-2-hydroxybenzoic acid was mixed with epichlorohydrin, potassium carbonate and dimethylformamide and reacted to extract the white solid product epoxy acid.

[0012] Step 2: The white solid product epoxy acid is subjected to acyl chloride reaction and then Curtius rearrangement.

[0013] Further, in step 2, the white solid product epoxy acid and SOCl2 are refluxed in dichloromethane and rotary evaporated to obtain crude acyl chloride. Then, the crude acyl chloride, diphenyl azidophosphate and triethylamine are reacted in toluene. Finally, the product is obtained by filtration, washing and vacuum distillation.

[0014] Furthermore, the reaction temperature is 70-90℃.

[0015] The present invention also discloses a high-adhesion polyurethane cold patch asphalt, the raw materials comprising the following components by weight: 20-30 parts solvent oil, 90-100 parts asphalt, 10-20 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 5-8 parts curing agent, and 0.05-0.1 parts catalyst.

[0016] Furthermore, the raw materials include the following components by weight: 25 parts solvent oil, 95 parts asphalt, 15 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 7 parts curing agent, and 0.07 parts catalyst.

[0017] Furthermore, the catalyst is dibutyltin dilaurate.

[0018] The beneficial effects of this invention are as follows: The novel compound for synthesizing polyurethane cold patch asphalt, the high-adhesion polyurethane cold patch asphalt, and the preparation method thereof of this invention contain three groups, one of which is an epoxy group (water-resistant and adhesive group), exhibiting high adhesiveness and capable of ring-opening reaction under alkaline conditions, forming covalent bonds with bond energies far exceeding hydrogen bonds and van der Waals forces. Simultaneously, the volume expansion rate during epoxy ring-opening polymerization is 2-5%, which can fill micro-cracks at the asphalt mixture interface, eliminate shrinkage stress, and the three-dimensional dense network structure formed after curing can prevent water molecules from entering the asphalt mixture. The epoxy group is located ortho-to the isocyanate group; due to the electron-withdrawing effect of the isocyanate group, it can significantly enhance the activity of epoxy ring-opening, accelerate the epoxy ring-opening rate, and shorten the time required for epoxy curing to form strength. The second group is a para-long-chain alkoxy group (-OC). 12 H 25 The first type of compound contains hydrophobic groups, which enhance compatibility with asphalt alkane components (like dissolves like), reduce crystallinity, and improve molecular flexibility. Long-chain alkanes also provide a secondary hydrophobic barrier, hindering water molecule penetration. The second type is isocyanate groups (bonding groups), which react with water to form urea groups, creating a polyurethane cross-linked network that enhances the bond between asphalt and aggregates. This novel compound is used to prepare polyurethane cold-mix asphalt. In this system, no polyols are needed; only water is required for the reaction, and the reaction rate is directly controlled by the catalyst. The isocyanate in the novel compound reacts with water to form a cross-linked network structure, and the epoxy groups undergo ring-opening polymerization on the surface of alkaline aggregates or under the action of amine curing agents to form a three-dimensional cross-linked network. This effectively improves the bonding performance and density of cold-mix asphalt, further enhancing pothole repair quality and extending road service life. After the cold-mix asphalt has developed strength, the hydrophobic and water-resistant groups of the novel compound can form a waterproof membrane on the surface of the cold-mix material, preventing water from entering the interlayer interface and causing segregation between asphalt and aggregates. Detailed Implementation

[0019] To better understand the present invention, the following embodiments are further illustrations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0020] Unless otherwise specified, the experimental methods used in the embodiments are conventional methods, and the materials and reagents used are commercially available unless otherwise specified.

[0021] This embodiment describes a novel compound for synthesizing polyurethane asphalt cold patching material. The compound is an aromatic isocyanate containing both epoxy groups and long-chain alkoxy groups. The epoxy groups are located ortho-positions on the isocyanate, and the long-chain alkoxy groups are located para-positions on the isocyanate. The core skeleton is an aromatic isocyanate containing isocyanate groups, epoxy groups, and long-chain alkoxy groups. The epoxy groups and isocyanate groups are located ortho-positions on the benzene ring, and the long-chain alkoxy groups are located para-positions on the benzene ring. This compound can react with moisture in the air to crosslink and cure, forming a polyurethane crosslinked network, without the need for polyols.

[0022] The preferred choice is the long-chain alkoxy group, dodecyloxy; the three-dimensional dense network structure formed after the epoxy group is cured can prevent water molecules from entering the asphalt mixture, while the dodecyloxy group can better provide a secondary hydrophobic barrier to prevent water molecule penetration, thus achieving a synergistic effect of hydrophobicity and water resistance.

[0023] In this embodiment, the compound is 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, and its structural formula is:

[0024]

[0025] Position 1: Isocyanate group (-N=C=O); Position 2: Glycoloxy group (-O-CH2-CH(O)CH2); Position 3: Hydrogen (H); Position 4: Dodecyloxy group (-OC) 12 H 25 ); 5-position, hydrogen (H); 6-position, hydrogen (H). Contains three binding groups: the first is an epoxy group, which has high reactive bonding ability and can undergo ring-opening reaction under alkaline conditions to form covalent bonds with bond energies much higher than hydrogen bonds and van der Waals forces. Simultaneously, the volume expansion rate during epoxy ring-opening polymerization is 2-5%, filling micro-cracks at the asphalt mixture interface and eliminating shrinkage stress. The second is a para-long-chain alkoxy group, which enhances compatibility with the asphalt alkane components (like dissolves like), reduces crystallinity, and improves molecular flexibility. The third is an isocyanate group, which reacts with water to ultimately form urea groups, forming a polyurethane cross-linked network that enhances the bonding ability between asphalt and aggregates. Two hydrophobic / water-resistant groups: the first is an epoxy group, which, after curing, forms a three-dimensional dense network structure that prevents water molecules from entering the asphalt mixture. The second is a dodecyloxy group, where long-chain alkanes provide a secondary hydrophobic barrier to prevent water molecule penetration.

[0026] This embodiment also discloses a method for synthesizing a novel compound for synthesizing polyurethane asphalt cold patching material, comprising the following steps:

[0027] 4-Dodecyloxy-2-(2,3-epoxypropoxy)benzoic acid was synthesized from 2,4-dihydroxybenzoic acid, followed by the preparation of epoxy acid solid products. These epoxy acid solid products were then subjected to acylation followed by Curtius rearrangement.

[0028] Step 1 involves recrystallizing 2,4-dihydroxybenzoic acid, 1-bromododecane, and K₂CO₃ under reflux in anhydrous acetone. The resulting 4-dodecyloxy-2-hydroxybenzoic acid is then reacted with epichlorohydrin, potassium carbonate, and dimethylformamide to extract a white solid product, epoxy acid. The recrystallization process includes filtration, rotary evaporation, and recrystallization (ethanol / water), which is existing technology and will not be detailed here. The extraction process includes ice-water precipitation, ethyl acetate extraction, and column chromatography (petroleum ether:ethyl acetate = 3:1), which is also existing technology and will not be detailed here.

[0029] Step 2: The white solid product epoxy acid is subjected to acyl chloride reaction followed by Curtius rearrangement: The white solid product epoxy acid and SOCl2 are refluxed in dichloromethane and rotary evaporated to obtain crude acyl chloride. Then, the crude acyl chloride, diphenyl azidophosphate and triethylamine are reacted in toluene at a reaction temperature of 70-90℃. Finally, the product is obtained by filtration, washing and vacuum distillation at 145-150℃ / 0.5mmHg. The obtained target product is a colorless oil.

[0030] Starting with 2,4-dihydroxybenzoic acid, epoxy groups were selectively introduced to generate isocyanate. The reaction route is as follows:

[0031]

[0032] This embodiment also discloses a polyurethane cold patch asphalt, the raw materials comprising the following components by weight: 20-30 parts solvent oil, 90-100 parts asphalt, 10-15 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 5-8 parts curing agent, and 0.05-0.1 parts catalyst; the prepared compound 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene is used to prepare a high-adhesion polyurethane cold patch asphalt material, the raw materials mainly including solvent asphalt and 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, the cold patch asphalt after mixing with asphalt has the following characteristics:

[0033] 1. Unlike the reaction mechanism of traditional two-component polyurethane, this system does not require the addition of polyols; only water is needed for the crosslinking reaction (reaction 1), and the reaction rate is controlled by a catalyst. Additionally, epoxy groups undergo crosslinking reactions on the surface of alkaline aggregates or under the action of amine curing agents to generate a three-dimensional network structure (reaction 2).

[0034] Two curing reactions:

[0035] Reaction 1: 1-Isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene reacts with water to produce an amine, carbon dioxide, and substituted urea.

[0036]

[0037] Reaction 2: (Ring-opening of epoxy groups, requires an alkaline environment or amine curing agent)

[0038]

[0039] 2. By controlling the catalyst dosage and isocyanate reaction rate, the curing time of cold-applied asphalt can be controlled, thus shortening the early strength formation time.

[0040] 3. Thanks to the network structure formed by isocyanate crosslinking and the three-dimensional crosslinked network formed by the ring-opening polymerization of epoxy groups on the surface of alkaline aggregates or under the action of amine curing agents, the bonding performance and density of cold patch asphalt are effectively improved, further enhancing the quality of pothole repair and extending the service life of roads.

[0041] 4. Improved resistance to water damage is due to the hydrophobic / water-resistant groups in 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene. After the cold-mixed asphalt has developed strength, it can form a waterproof membrane on the surface of the cold-mixed material, preventing water from entering the interlayer interface and causing segregation of asphalt and aggregate.

[0042] Compound 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene contains epoxy, dodecyloxy, and isocyanate groups, which can enhance the bond strength between cold-patch asphalt and the original pavement. The dodecyloxy group in the compound improves the water resistance of the cured cold-patch asphalt. The epoxy groups, after curing, form a cross-linked hydrophobic network, further enhancing the water resistance of the cold-patch material and hindering water penetration. The epoxy and isocyanate groups complement each other; the isocyanate groups react quickly, providing rapid initial strength to the cold-patch material, while the epoxy groups react more slowly, further providing long-term strength and durability by covalently anchoring the aggregate.

[0043] In a preferred embodiment, the raw materials comprise the following components by weight: 25 parts solvent oil, 95 parts asphalt, 15 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 7 parts curing agent, and 0.07 parts catalyst; wherein the catalyst is dibutyltin dilaurate.

[0044] Example 1

[0045] Synthesis of 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene

[0046] Step 1: Synthesis of 4-dodecyloxy-2-(2,3-epoxypropoxy)benzoic acid

[0047] 50 g of 2,4-dihydroxybenzoic acid, 106 g of 1-bromododecane, and 90 g of K₂CO₃ were refluxed in 500 mL of anhydrous acetone for 24 h. The mixture was then filtered, rotary evaporated, and recrystallized (ethanol / water) to obtain 4-dodecyloxy-2-hydroxybenzoic acid. 80 g of 4-dodecyloxy-2-hydroxybenzoic acid was mixed with 115 g of epichlorohydrin and 70 g of potassium carbonate in 300 mL of DMF and reacted at 60 °C for 12 h. The mixture was then precipitated in ice water, extracted with ethyl acetate, and subjected to column chromatography (petroleum ether:ethyl acetate = 3:1) to obtain the epoxy acid product (white solid).

[0048] Step 2: Curtius rearrangement to form isocyanate

[0049] Acyl chloride: 70g of epoxy acid and 72g of SOCl2 were refluxed in dichloromethane (200mL) for 6h, and the crude acyl chloride was obtained by rotary evaporation.

[0050] Curtius rearrangement: Acyl chloride, diphenyl azidophosphate, and 40 g Et3N were reacted in toluene (300 mL) at 80 °C for 8 h. After filtration, washing, and vacuum distillation (145-150 °C / 0.5 mmHg), the target product (colorless oil) was obtained.

[0051] Example 2

[0052] Synthesis of 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene

[0053] Step 1: Synthesis of 4-dodecyloxy-2-(2,3-epoxypropoxy)benzoic acid

[0054] 50 g of 2,4-dihydroxybenzoic acid, 106 g of 1-bromododecane, and 90 g of K₂CO₃ were refluxed in 500 mL of anhydrous acetone for 24 h. The mixture was then filtered, rotary evaporated, and recrystallized (ethanol / water) to obtain 4-dodecyloxy-2-hydroxybenzoic acid. 70 g of 4-dodecyloxy-2-hydroxybenzoic acid was mixed with 103 g of epichlorohydrin and 63 g of potassium carbonate in 300 mL of DMF and reacted at 60 °C for 12 h. The mixture was then precipitated in ice water, extracted with ethyl acetate, and subjected to column chromatography (petroleum ether:ethyl acetate = 3:1) to obtain the epoxy acid product (white solid).

[0055] Step 2: Curtius rearrangement to form isocyanate

[0056] Acyl chloride: 50g of epoxy acid and 51g of SOCl2 were refluxed in dichloromethane (200mL) for 6h, and the crude acyl chloride was obtained by rotary evaporation.

[0057] Curtius rearrangement: acyl chloride, diphenyl azidophosphate, and 36 g of Et3N was reacted in toluene (300 mL) at 80 °C for 7 h. After filtration, washing, and vacuum distillation (145-150 °C / 0.5 mmHg), the target product (colorless oil) was obtained.

[0058] Example 3

[0059] Synthesis of 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene

[0060] Step 1: Synthesis of 4-dodecyloxy-2-(2,3-epoxypropoxy)benzoic acid

[0061] 63 g of 2,4-dihydroxybenzoic acid, 112 g of 1-bromododecane, and 93 g of K₂CO₃ were refluxed in 500 mL of anhydrous acetone for 24 h. The mixture was then filtered, rotary evaporated, and recrystallized (ethanol / water) to obtain 4-dodecyloxy-2-hydroxybenzoic acid. 88 g of 4-dodecyloxy-2-hydroxybenzoic acid was mixed with 133 g of epichlorohydrin and 73 g of potassium carbonate in 300 mL of DMF and reacted at 60 °C for 12 h. The mixture was then precipitated in ice water, extracted with ethyl acetate, and subjected to column chromatography (petroleum ether:ethyl acetate = 3:1) to obtain the epoxy acid product (white solid).

[0062] Step 2: Curtius rearrangement to form isocyanate

[0063] Acyl chloride: 70g of epoxy acid and 72g of SOCl2 were refluxed in dichloromethane (200mL) for 6h, and the crude acyl chloride was obtained by rotary evaporation.

[0064] Curtius rearrangement: Acyl chloride, diphenyl azidophosphate, and 36 g Et3N were reacted in toluene (300 mL) at 80 °C for 8 h. After filtration, washing, and vacuum distillation (145-150 °C / 0.5 mmHg), the target product (colorless oil) was obtained.

[0065] Example 4

[0066] The polyurethane cold-patch asphalt of this embodiment comprises the following components by weight: 25 parts solvent oil, 95 parts asphalt, 10 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 5 parts amine curing agent, and 0.07 parts catalyst. The above raw materials are directly mixed and stirred to obtain the polyurethane cold-patch asphalt. The 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene was prepared using the method described in Example 1.

[0067] Example 5

[0068] The polyurethane cold-patch asphalt of this embodiment comprises the following components by weight: 25 parts solvent oil, 95 parts asphalt, 10 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 7 parts amine curing agent, and 0.07 parts catalyst. The above raw materials are directly mixed and stirred to obtain the polyurethane cold-patch asphalt. The 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene was prepared using the method described in Example 1.

[0069] Example 6

[0070] The polyurethane cold-patch asphalt of this embodiment comprises the following components by weight: 25 parts solvent oil, 95 parts asphalt, 10 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 5 parts amine curing agent, and 0.1 parts catalyst. The above raw materials are directly mixed and stirred to obtain the polyurethane cold-patch asphalt. The 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene was prepared using the method described in Example 1.

[0071] Example 7

[0072] The polyurethane cold-patch asphalt of this embodiment comprises the following components by weight: 25 parts solvent oil, 95 parts asphalt, 15 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 5 parts amine curing agent, and 0.07 parts catalyst. The above raw materials are directly mixed and stirred to obtain the polyurethane cold-patch asphalt. The 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene was prepared using the method described in Example 1.

[0073] Example 8

[0074] The polyurethane cold-patch asphalt of this embodiment comprises the following components by weight: 25 parts solvent oil, 95 parts asphalt, 23 parts 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 5 parts amine curing agent, and 0.07 parts catalyst. The above raw materials are directly mixed and stirred to obtain the polyurethane cold-patch asphalt. The 1-isocyanate-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene was prepared using the method described in Example 1.

[0075] Comparative Example 1

[0076] The cold patch asphalt in this comparative example contains the following components by weight: 25 parts solvent oil and 95 parts asphalt. The above raw materials are directly mixed and stirred to obtain cold patch asphalt, i.e., traditional cold patch asphalt.

[0077] Table 1 Comparative Test Scheme for Polyurethane Cold-Matched Asphalt Performance

[0078]

[0079] The Marshall stability, immersion Marshall stability, residual stability, water loss resistance, rutting dynamic stability, and abrasion resistance tests in Table 1 were obtained from asphalt mixtures prepared with cold-mixed asphalt. The aggregate gradation was LB-13, and the aggregate type was limestone. The gradation distribution and the synthetic gradation used in the tests are shown in Table 2. The asphalt-aggregate ratio was determined to be 4.7%, and the mixture was mixed at room temperature for 150 s. Five specimens were prepared for each group, and the average value was taken.

[0080] Table 2. Gradation of LB-13 Cold Repair Material

[0081]

[0082] The cold-patch asphalt and cold-patch material obtained in Examples 4-8 and Comparative Example 1 were tested respectively. The test results are shown in Tables 2, 3, 4 and 5. The bond strength was tested according to the "Adhesion Test of Paints and Varnishes by Pull-Off Method" (GB / T5210-2006). Marshall stability, water immersion Marshall stability, residual stability, water loss resistance, rutting test, and abrasion resistance were tested according to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011).

[0083] Table 3. Bond strength and Marshall stability of cold patch asphalt asphalt test results

[0084]

[0085] In terms of bond strength, compared with traditional cold-mix asphalt, the addition of the new compound significantly improved the bond strength of the cold-mix material, increasing from 1.53 MPa to approximately 3.0 MPa, a doubling. This is mainly because the network structure generated by the reaction of isocyanate groups in the new compound and the three-dimensional cross-linked network structure formed by the ring-opening polymerization of epoxy groups significantly improved the bond strength between the interfaces, ensuring that the aggregate-asphalt-base layer are tightly bonded together. The main variable in Examples 4, 7, and 8 was the dosage of the new compound, which was 10, 15, and 23 parts respectively. Example 7 showed a 22.3% increase in bond strength compared to Example 4, but Example 8 showed little change in bond strength compared to Example 7. This indicates that within a certain range, the addition of the new compound helps improve the bond strength of cold-mix asphalt, but the change is not significant if the dosage is too high. This is because the network structure generated by the two bonding groups at the optimal dosage is sufficient to completely encapsulate the asphalt and the interface; therefore, further increasing the dosage of the new compound has limited effect. The main variable in Examples 4 and 5 is the dosage of the amine curing agent. The latter shows an 8% increase in bond strength compared to the former, indicating that within a certain range, a higher amount of curing agent is beneficial for the formation of bond strength in cold-patch asphalt. This is because the more curing agent, the higher the probability of contact between the epoxy groups in the novel compound, resulting in more epoxy groups undergoing chemical reactions, more three-dimensional network structures formed, and better bond performance of the cold-patch asphalt. The main variable in Examples 4 and 6 is the dosage of the catalyst. The bond strength of the two groups is not significantly different, mainly because the catalyst participates very little in the reaction and has little impact on the number of cross-linked network structures formed.

[0086] Compared to traditional cold-mix asphalt, the cold-mix asphalt with the addition of the new compound showed significant improvements in Marshall stability, water-immersion Marshall stability, and residual stability. The Marshall stability was improved by approximately 100%, primarily due to the cross-linking network formed by the three groups in the new compound: epoxy groups and isocyanate groups. This enhanced the bond strength between the cold-mix asphalt and aggregates, tightly binding them together and resulting in higher Marshall stability. Regarding water-immersion Marshall stability, the traditional cold-mix asphalt showed a 25.9% decrease. This is because, firstly, voids exist at the interface between the aggregate and asphalt, allowing water to penetrate the aggregate surface and gradually separate the asphalt from the aggregate. Secondly, traditional cold-mix asphalt cannot prevent water from entering, leading to gradual segregation of the aggregate under water immersion and subsequent pavement damage. The introduction of novel compounds has led to the micro-expansion of the three-dimensional network structure formed by the cross-linking of epoxy groups, which helps to reduce the fine voids in cold patch materials, increase the interfacial adhesion between asphalt and aggregates, and block water from entering the pores at the interface. Meanwhile, the dodecyloxy group can form a hydrophobic film on the asphalt surface, which greatly improves the water resistance of cold patch asphalt. Therefore, the examples of introducing novel compounds all maintain high water immersion Marshall strength and residual stability.

[0087] Table 4. Performance Tests of Cold-Matching Material in Road Application

[0088]

[0089] Water loss resistance and abrasion resistance were tested using the wet wheel abrasion test (T0752-2011) for slurry mixtures. Water loss resistance was evaluated using the 6-day wet wheel abrasion value, and abrasion resistance was evaluated using the 1-hour wet wheel abrasion value. Compared to cold patch materials made from traditional cold-mix asphalt, the water loss resistance and abrasion resistance were improved by approximately 56.3% and 58.5%, respectively. The introduction of novel compounds significantly improved the water loss resistance and abrasion resistance of the cold patch material. This is because the three-dimensional network structure formed by the cross-linking of epoxy groups has high strength, giving the cold patch material good abrasion resistance. The combined effect of the three groups binds the asphalt and aggregate into a whole while also giving the cold patch material good water resistance and hydrophobicity, thus improving its water loss resistance and abrasion resistance. In Examples 4, 7, and 8, the main variable was the dosage of the novel compound, added at 10, 15, and 23 parts respectively. Results showed that increasing the dosage of the novel compound within a certain range improved the water loss resistance and abrasion resistance of the cold patch material. However, excessive addition did not significantly change the performance. This is because the network structure generated at the optimal dosage is sufficient to completely encapsulate the asphalt and the interface, and further increases in the dosage of the novel compound have limited effect. In Examples 4 and 5, the main variable was the dosage of the amine curing agent. Results showed that increasing the curing agent dosage within a certain range improved the water loss resistance and abrasion resistance of the cold patch material. Regarding rutting dynamic stability, it was approximately 13 times better than cold patch material made from traditional cold patch asphalt. This is mainly because the cross-linked network formed by the epoxy groups and isocyanate groups makes the cold patch material tightly bonded and very strong, and it is not easily deformed at 60°C. In summary, the introduction of the novel compound can significantly improve the road performance of cold patch material and extend the service life of roads.

[0090] Table 5. Effect of curing agent dosage on Marshall stability of cold patching material

[0091]

[0092] The main variable in Examples 4 and 5 is the amount of amine curing agent. As shown in Table 4, adding 2 more parts of amine curing agent resulted in Example 5 having a higher final strength at 3 days than Example 4. This indicates that within a certain range, a larger amount of curing agent is beneficial for the epoxy groups to fully form a cross-linked network, thus improving the final strength of the cold-applied compound. Before 2 days, the differences between the two groups were not significant, mainly because the epoxy curing process forms a three-dimensional network structure relatively slowly.

[0093] Table 6. Effect of catalyst dosage on Marshall stability of cold-feed feed

[0094]

[0095] The main variable in Examples 4 and 6 is the amount of catalyst. As can be seen from Table 5, the addition of 0.03 parts of catalyst resulted in an increase in strength of Example 6 by about 33.8% in the first 2 hours compared to Example 4. This indicates that within a certain range, a larger amount of catalyst is beneficial for the rapid formation of cross-linked networks of isocyanate groups, which leads to a rapid increase in the initial strength of the cold-filled material.

[0096] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A novel compound for synthesizing polyurethane asphalt cold patching material, characterized in that: The compound is an aromatic isocyanate containing both an epoxy group and a long-chain alkoxy group, wherein the epoxy group is located at the ortho position of the isocyanate and the long-chain alkoxy group is located at the para position of the isocyanate.

2. The novel compound for synthesizing polyurethane asphalt cold patching material according to claim 1, characterized in that: The long-chain alkoxy group is dodecyloxy.

3. The novel compound for synthesizing polyurethane asphalt cold patching material according to claim 2, characterized in that: The compound is 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, and its structural formula is:

4. The method for synthesizing the novel compound for synthesizing polyurethane asphalt cold patching material according to claim 1, characterized in that: Includes the following steps: 4-Dodecyloxy-2-(2,3-epoxypropoxy)benzoic acid was synthesized from 2,4-dihydroxybenzoic acid to prepare epoxy acid solid products. Then, the epoxy acid solid products were subjected to acylation followed by Curtius rearrangement.

5. The method for synthesizing the novel compound for synthesizing polyurethane asphalt cold patching material according to claim 1, characterized in that: Includes the following steps: Step 1: 2,4-Dihydroxybenzoic acid, 1-bromododecane and K2CO3 were refluxed in anhydrous acetone and recrystallized. Then, the obtained 4-dodecyloxy-2-hydroxybenzoic acid was mixed with epichlorohydrin, potassium carbonate and dimethylformamide and reacted to extract the white solid product epoxy acid. Step 2: The white solid product epoxy acid is subjected to acyl chloride reaction and then Curtius rearrangement.

6. The method for synthesizing the novel compound for synthesizing polyurethane asphalt cold patching material according to claim 1, characterized in that: In step 2, the white solid product epoxy acid and SOCl2 are refluxed in dichloromethane and rotary evaporated to obtain crude acyl chloride. Then, the crude acyl chloride, diphenyl azidophosphate and triethylamine are reacted in toluene. Finally, the product is obtained by filtration, washing and vacuum distillation.

7. The method for synthesizing the novel compound for synthesizing polyurethane asphalt cold patching material according to claim 6, characterized in that: The reaction temperature is 70-90℃.

8. A high-adhesion polyurethane cold-patch asphalt, characterized in that: The raw materials include the following components by weight: 20-30 parts solvent oil, 90-100 parts asphalt, 10-15 parts 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 5-8 parts curing agent, and 0.05-0.1 parts catalyst.

9. The high-adhesion polyurethane cold-patch asphalt according to claim 1, characterized in that: The raw materials include the following components by weight: 25 parts solvent oil, 95 parts asphalt, 15 parts 1-isocyano-2-(2,3-epoxypropoxy)-4-dodecyloxybenzene, 7 parts curing agent, and 0.07 parts catalyst.

10. The high-adhesion polyurethane cold-patch asphalt according to claim 8, characterized in that: The curing agent is an amine curing agent, and the catalyst is dibutyltin dilaurate.

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