Anti-ultraviolet low-temperature self-repairing asphalt modifier for high and cold high altitude as well as preparation and application of anti-ultraviolet low-temperature self-repairing asphalt modifier

Abstract

The invention relates to an anti-ultraviolet low-temperature self-repairing asphalt modifier for high-cold and high-altitude areas and preparation and application thereof.The modifier is a micron-sized capsule with a core-shell structure, the capsule core is biomass regenerated oil, the capsule wall is made of thermosetting resin doped with a nano ultraviolet screening agent, and the nano ultraviolet screening agent is added into the capsule wall. The surface of the outermost layer of the capsule wall is also grafted with a silane coupling agent. Compared with the prior art, nano ZnO is fixed on the capsule wall to form an ultraviolet shielding layer by using an in-situ polymerization method, so that the photo-oxidative aging of asphalt is effectively delayed; when the asphalt generates microcracks due to low temperature, crack tip stress triggers the microcapsules to break to release capsule core biomass oil, so that self-healing of the cracks is realized; meanwhile, the silane coupling agent on the surface enhances the interfacial adhesion of asphalt and aggregate, and the provided modifier can effectively solve the technical problems of fast aging, low-temperature cracking and serious water damage of asphalt pavements in high-cold and high-altitude areas.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, and relates to an anti-ultraviolet low-temperature self-healing asphalt modifier for high-altitude and cold regions and its preparation method. Background Technology

[0002] For high-altitude and cold regions, the climate is extremely harsh, and asphalt pavements face unique service environment challenges: (1) Strong ultraviolet radiation: The atmosphere is thin in high-altitude areas, and the intensity of ultraviolet radiation is much higher than in plains. Strong ultraviolet radiation will cause the light components (saturated components and aromatic components) in asphalt to undergo photo-oxidation reaction, transforming into asphalt, which will cause the road surface to harden and become brittle rapidly, resulting in surface cracking.

[0003] (2) Extreme low temperature and large temperature difference: The winter in this region is long, the temperature is extremely low and the daily temperature difference is large. The stiffness modulus of the aged asphalt increases and the stress relaxation ability decreases, making it very easy to produce low temperature shrinkage cracks.

[0004] (3) Frequent freeze-thaw cycles: The region experiences frequent rain and snow. After water seeps into the microcracks, it generates expansion pressure under repeated freeze-thaw cycles, causing the interface between asphalt and acid aggregate (a common lithology in the region) to peel off, resulting in severe water damage.

[0005] Therefore, in order to overcome the aforementioned service environment challenges, asphalt pavement needs to be modified. However, existing modification technologies generally have limitations: (1) Simply adding carbon black or UV absorbers can resist aging, but cannot repair cracks that have already formed at low temperatures.

[0006] (2) Directly adding bio-oil and other regenerators can improve low-temperature performance, but bio-oil has poor heat resistance and will significantly reduce the high-temperature rutting resistance of asphalt.

[0007] (3) Existing self-healing microcapsules usually have smooth outer walls and weak interfacial adhesion with asphalt and aggregates, making them prone to becoming "stripping points" under freeze-thaw cycles.

[0008] Therefore, there is an urgent need to develop a new type of functional material that can solve the above three major technical problems in a "one-stop" manner. Summary of the Invention

[0009] The purpose of this invention is to provide an anti-ultraviolet low-temperature self-healing asphalt modifier for high-altitude and cold regions, as well as its preparation and application, to solve the technical problems of rapid aging, low-temperature cracking and severe water damage of asphalt pavements in high-altitude and cold regions.

[0010] The objective of this invention can be achieved through the following technical solutions: In one aspect, the present invention provides an anti-ultraviolet low-temperature self-healing asphalt modifier for high-altitude and cold regions, which is a micron-sized capsule with a core-shell structure, wherein the core is biomass recycled oil, the capsule wall is made of thermosetting resin doped with nano-ultraviolet shielding agent, and the outermost surface of the capsule wall is also grafted with a silane coupling agent.

[0011] Furthermore, the biomass-regenerated oil is selected from one or more of waste vegetable oil extracts, acidified oils, or biodiesel byproducts, and its kinematic viscosity at 25°C is 50~500 mmHg. 2 / s.

[0012] Furthermore, the thermosetting resin is melamine-urea-formaldehyde (MUF) resin or polyurea resin. The nano-ultraviolet shielding agent is nano-zinc oxide or nano-titanium oxide.

[0013] Furthermore, the particle size of the nano-UV shielding agent is 20~100 nm.

[0014] Furthermore, the silane coupling agent is selected from any one of KH-550, KH-560 or KH-570.

[0015] Furthermore, the biomass recycled oil accounts for 40-70% of the total mass of the micron-sized capsules; The amount of the nano-UV shielding agent is 5-10% of the mass of the thermosetting resin, preferably 8%.

[0016] The high-altitude, cold-resistant, UV-resistant, low-temperature self-healing asphalt modifier of this invention adopts a triple-functional design of "core regeneration - core wall shielding - surface thickening": (1) Core structure: The core is made of biomass oil rich in light components. During the construction and normal service of asphalt pavement, the bio-oil is sealed and does not reduce the high-temperature performance of asphalt. When low temperature and aging cause microcracks to form, the stress concentration at the crack tip punctures the capsule, releasing the bio-oil, dissolving and softening the aged asphalt at the crack, and achieving self-healing.

[0017] (2) Shielding structure: Nano-ZnO and other nano-UV shielding agents are in situ doped into the capsule wall material. They can form a dense protective net in the microcapsule shell, which not only protects the internal bio-oil from photolysis, but also protects the surrounding asphalt mortar like a "sunshade".

[0018] (3) Interface structure: Silane coupling agent is grafted onto the outermost layer of the microcapsule. The coupling agent is like "double-sided tape", with one end anchored to the surface of the microcapsule by chemical bonds, and the other end mainly reacting with the hydroxyl groups on the surface of the acid aggregate, thereby constructing a strong interface of "aggregate-coupling agent-microcapsule-asphalt", which significantly resists freeze-thaw spalling.

[0019] In a second aspect, the present invention provides a method for preparing an anti-ultraviolet low-temperature self-healing asphalt modifier for high-altitude and cold regions as described in the first aspect, comprising the following steps: S1. Biomass recycled oil is mixed with an emulsifier to form an oil-in-water emulsion under high-speed shear conditions; S2. Add the nano UV shielding agent to the prepolymer solution of the thermosetting resin and then ultrasonically disperse it evenly. S3. The mixture obtained in S2 is added dropwise to the oil-in-water emulsion in S1, the pH value is adjusted to an acidic environment, and the temperature is raised to initiate a condensation reaction, so that the wall material is deposited and solidified on the surface of the oil droplet to form a microcapsule with the capsule wall covering the capsule core. S4. Add silane coupling agent to the reaction system in S3, keep the temperature for reaction, so that the silane coupling agent is grafted onto the surface of the microcapsule. S5. Filter, wash and dry the reaction product obtained in S4 to obtain micron-sized capsules, which are the target products.

[0020] Furthermore, in step S2, the nano-UV shielding agent undergoes a hydrophobic modification treatment on its surface before being added. Specifically, the hydrophobic modification process involves placing the nano-UV shielding agent in anhydrous ethanol. Furthermore, in S3, the pH value of the acidic environment is 3.5~5.0, the temperature of the polycondensation reaction is 60~85℃, and the time is 2~4h; In S4, the amount of silane coupling agent added is 1.0% to 3.0% of the theoretical total mass of the micron-sized capsules (i.e., the sum of the mass of biomass regenerated oil and thermosetting resin).

[0021] In a third aspect, the present invention provides the application of the UV-resistant low-temperature self-healing asphalt modifier for high-altitude and cold regions as described in the first aspect, wherein the modifier is added to the base asphalt as an admixture, and the admixture amount is 3.0% to 8.0% of the mass of the base asphalt.

[0022] Compared with the prior art, the present invention has the following advantages: (1) Extended UV resistance life: Compared with ordinary asphalt, the modified asphalt of this invention has a significantly reduced softening point increment under strong ultraviolet radiation and a significantly improved ductility retention rate.

[0023] (2) Intelligent low temperature self-repair: In response to the frequent low temperature cracking in high-altitude and cold regions, it realizes passive repair without human intervention, effectively heals micro cracks and prevents crack propagation.

[0024] (3) Enhanced resistance to water damage: It solves the problem of weak bonding between traditional microcapsules and the matrix interface. Through chemical bonding, it can maintain structural integrity even in frequent freeze-thaw environments. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the modifier's structure; Figure 2 This is a schematic diagram illustrating the role of modifiers in asphalt pavement. Figure 3 This is a schematic diagram illustrating the function of the nano-UV shielding agent in the modifier. Detailed Implementation

[0026] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0027] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0028] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0029] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0030] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0031] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0032] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0033] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0034] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0035] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0036] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0037] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0038] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0039] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0040] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0041] In the following embodiments, the waste vegetable oil was purchased from Guangguo Bioenergy (Nanjing) Co., Ltd., UCO-01; and the styrene-maleic anhydride copolymer (SMA) was purchased from Nanjing Yinxin Chemical Co., Ltd., SMA-1000. Unless otherwise specified, all other raw materials or processing techniques are commercially available materials or conventional processing techniques in the art.

[0042] Example 1: Preparation of modifier (1) Preparation of prepolymer: Melamine, urea and 37wt% formaldehyde solution were mixed in a mass ratio of 5:2:10, distilled water was added, the pH was adjusted to 8.5 with triethanolamine, and the mixture was stirred in a 70℃ water bath for 60 minutes to obtain a transparent MUF prepolymer solution.

[0043] (2) Nanoparticle doping: Weigh 8% of the prepolymer mass of nano ZnO (average particle size 40nm), disperse it in anhydrous ethanol, add KH-570 coupling agent, and mechanically stir the reaction for 4 hours under constant temperature water bath at 60℃ to perform surface hydrophobic treatment. Then centrifuge and dry for later use. Then add it to the above prepolymer solution and ultrasonically disperse for 30 minutes to prevent agglomeration.

[0044] (3) Emulsification and granulation: Weigh 50g of waste vegetable oil (which needs to be filtered to remove impurities beforehand) and add it to 200mL of an aqueous solution containing 1.5wt% styrene-maleic anhydride copolymer (SMA). Emulsify for 15 minutes at 4000 rpm using a high-shear emulsifier to form a stable oil-in-water emulsion.

[0045] (4) In-situ polymerization coating: The prepolymer solution containing nano-ZnO in step (2) is slowly added dropwise to the above oil-in-water emulsion. After the addition is complete, the pH is slowly adjusted to 4.0 with citric acid solution, the temperature is raised to 75°C, and the reaction is carried out at a low speed of 500 rpm for 3 hours to solidify the capsule wall.

[0046] (5) Surface grafting modification: (5) Surface grafting modification: When the reaction is nearing its end, without cooling, add KH-550 silane coupling agent directly to the suspension (the amount added is 1.0% of the theoretical total mass of the microcapsules), maintain the temperature at 60℃ and continue stirring for 1 hour, so that the silane coupling agent is grafted onto the outermost surface of the microcapsules through chemical bonds.

[0047] (6) Post-processing: The product was filtered, washed three times alternately with deionized water and anhydrous ethanol, and dried in an oven at 60°C for 24 hours to obtain white powder microcapsules.

[0048] Example 2: Application effect verification To verify the effectiveness of the present invention, three types of asphalt samples were prepared for comparison: (1) Base asphalt: 70# road petroleum asphalt.

[0049] (2) Ordinary microcapsule modified bitumen: 5% ordinary bio-oil microcapsules without ZnO doping and without grafting coupling agent were added (the rest is the same as in Example 1).

[0050] (3) Modified asphalt of the present invention: 5% of the modifier prepared in Example 1 is added.

[0051] The test results are as follows: 1. UV aging resistance: The sample was placed in a UV aging chamber and aged for 7 days in a high-altitude, high-radiation environment (for details of the test process, see: Research on damage mechanism and performance improvement of asphalt pavement for concrete bridge deck in high-altitude and cold regions [D]. Southeast University, 2023).

[0052] The softening point of the base asphalt increased from 48.4℃ before aging to 60.4℃ after aging, an increase of 12℃; the ductility at 5℃ decreased from 18.5 cm before aging to 5.2 cm, with a ductility retention rate of 28.1%.

[0053] The modified asphalt of this invention has a softening point that increases from 55.6℃ before aging to 60.6℃ after aging, an increase of 6℃; and a ductility of 5℃ that changes from 26.8 cm before aging to 20.4 cm after aging, with a ductility retention rate of 76.1%.

[0054] Conclusion: The nano-ZnO on the capsule wall effectively played a shielding role.

[0055] 2. Low-temperature self-healing performance (BBR test): The beam bending creep test was carried out at -18℃. The load was first applied to induce cracking, and after healing at room temperature for 24 hours, the load was applied again.

[0056] Ordinary microcapsule modified asphalt: stiffness modulus recovery rate is about 60%.

[0057] The modified asphalt of this invention has a stiffness modulus recovery rate of 88%.

[0058] Conclusion: Bio-oil release effectively achieved regeneration and healing of cracks.

[0059] 3. Water damage resistance (freeze-thaw splitting test TSR): Ordinary microcapsule modified bitumen: TSR value is 81% (there is a risk of peeling at the microcapsule interface).

[0060] The modified asphalt of this invention has a TSR value increased to 93%.

[0061] Conclusion: Surface-grafted silane coupling agents significantly enhance interfacial adhesion and are suitable for cold, rainy, and snowy environments.

[0062] To further verify the role and importance of each component in the modifier of the present invention, the following comparative examples 1 to 3 were designed.

[0063] Comparative Example 1 (Verifying the role of nano-ZnO): The only difference between this comparative example and Example 1 is that no nano-UV shielding agent (nano-ZnO) was added. That is, in step (2), the nano-ZnO was not weighed, modified, or added, and the subsequent emulsification and polymerization reactions were carried out directly. The remaining preparation steps, raw material types, and amounts were consistent with those in Example 1.

[0064] The results showed that, in Comparative Example 1, after the removal of nano-ZnO, although the microcapsule structure remained, the softening point increment of the asphalt increased from 5.0℃ to 10.8℃, and the ductility at 5℃ after aging was 6.5 cm (close to the level of the base asphalt). This demonstrates that the nano-ZnO embedded in the capsule wall constitutes an effective ultraviolet shielding layer, protecting the asphalt matrix from photo-oxidative damage.

[0065] Comparative Example 2 (verifying the effect of silane coupling agent modification): The only difference between this comparative example and Example 1 is that step (5) surface grafting modification is omitted. That is, after the microcapsule preparation reaction is completed, KH-550 silane coupling agent is not added for final surface treatment, and cooling, washing and drying are performed directly. The remaining preparation steps and raw materials are the same as in Example 1.

[0066] The results showed that, in Comparative Example 2 without surface coupling agent modification, after a 48-hour storage stability test, the softening point of the upper part of the sample tube reached 59.4℃, while the softening point of the lower part was 53.8℃, a difference of 5.6℃. This indicates that the microcapsules have extremely poor compatibility with asphalt, resulting in severe floating or agglomeration during storage. Simultaneously, due to the weak interfacial bonding, the microcapsules easily detached from the asphalt under stress, leading to a decrease in ductility. This demonstrates that KH-550 surface grafting is a key step in achieving stable dispersion of the modifier.

[0067] Comparative Example 3 (Verifying the importance of MUF resin wall materials): The only difference between this comparative example and Example 1 is that the capsule wall resin matrix is ​​changed to ordinary urea-formaldehyde resin (UF). That is, in the prepolymer preparation step (1), melamine is not added, and only urea and formaldehyde are reacted to prepare the urea-formaldehyde prepolymer, and the molar ratio of formaldehyde to urea is kept at 1.5:1. The remaining preparation steps and raw materials are the same as in Example 1.

[0068] The results showed that in Comparative Example 3, which used ordinary urea-formaldehyde resin (UF) as the wall material, a large number of microcapsules ruptured prematurely during the shear mixing process with high-temperature asphalt (160°C) due to the high brittleness and poor heat resistance of UF resin. This resulted in premature release of the core material and loss of the microcapsule's "slow-release repair" function. Consequently, its ductility after aging (9.2 cm) was significantly lower than that of Example 1, which used melamine-modified resin (MUF) (20.4 cm). This demonstrates that introducing melamine to enhance the capsule wall strength is a necessary condition for adapting to the high-temperature asphalt mixing process.

[0069] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A UV-resistant, low-temperature self-healing asphalt modifier for high-altitude and cold regions, characterized in that, It is a micron-sized capsule with a core-shell structure, wherein the core is biomass recycled oil, the capsule wall is made of thermosetting resin doped with nano-UV shielding agent, and the outermost surface of the capsule wall is also grafted with silane coupling agent.

2. The UV-resistant, low-temperature self-healing asphalt modifier for high-altitude and cold regions according to claim 1, characterized in that, The biomass-regenerated oil is selected from one or more of waste vegetable oil extracts, acidified oils, or biodiesel byproducts, and its kinematic viscosity at 25°C is 50~500 mmHg. 2 / s.

3. The UV-resistant, low-temperature self-healing asphalt modifier for high-altitude and cold regions according to claim 1, characterized in that, The thermosetting resin is melamine-urea-formaldehyde resin or polyurea resin; The nano-ultraviolet shielding agent is nano-zinc oxide or nano-titanium oxide.

4. The UV-resistant, low-temperature self-healing asphalt modifier for high-altitude and cold regions according to claim 3, characterized in that, The particle size of the nano-ultraviolet shielding agent is 20~100 nm.

5. The UV-resistant, low-temperature self-healing asphalt modifier for high-altitude and cold regions according to claim 1, characterized in that, The silane coupling agent is selected from any one of KH-550, KH-560 or KH-570.

6. The UV-resistant, low-temperature self-healing asphalt modifier for high-altitude and cold regions according to claim 1, characterized in that, The biomass recycled oil accounts for 40-70% of the total mass of the micron-sized capsules; The amount of the nano-UV shielding agent used is 5-10% of the mass of the thermosetting resin.

7. The preparation method of the UV-resistant low-temperature self-healing asphalt modifier for high-altitude and cold regions as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Biomass recycled oil is mixed with an emulsifier to form an oil-in-water emulsion under high-speed shear conditions; S2. Add the nano UV shielding agent to the prepolymer solution of the thermosetting resin and then ultrasonically disperse it evenly. S3. The mixture obtained in S2 is added dropwise to the oil-in-water emulsion in S1, the pH value is adjusted to an acidic environment, and the temperature is raised to initiate a condensation reaction, so that the wall material is deposited and solidified on the surface of the oil droplet to form a microcapsule with the capsule wall covering the capsule core. S4. Add silane coupling agent to the reaction system in S3, keep the temperature for reaction, so that the silane coupling agent is grafted onto the surface of the microcapsule. S5. Filter, wash and dry the reaction product obtained in S4 to obtain micron-sized capsules, which are the target products.

8. The preparation method of the UV-resistant low-temperature self-healing asphalt modifier for high-altitude and cold regions according to claim 7, characterized in that, In S2, the nano-UV shielding agent undergoes a hydrophobic modification treatment on its surface before being added.

9. The preparation method of the UV-resistant low-temperature self-healing asphalt modifier for high-altitude and cold regions according to claim 7, characterized in that, In S3, the pH value of the acidic environment is 3.5~5.0, the temperature of the polycondensation reaction is 60~85℃, and the time is 2~4h; In S4, the amount of silane coupling agent added is 1.0% to 3.0% of the theoretical total mass of the micron-sized capsule.

10. The application of the UV-resistant, low-temperature self-healing asphalt modifier for high-altitude and cold regions as described in any one of claims 1-6, characterized in that, The modifier is added to the base asphalt as an admixture, and the dosage is 3.0% to 8.0% of the mass of the base asphalt.

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