A polymer modified asphalt, a preparation method and application thereof

Abstract

The application relates to the technical field of asphalt, and provides high-molecular modified asphalt as well as a preparation method and application thereof, wherein the high-molecular modified asphalt comprises the following raw materials in mass fractions: 100 parts of base asphalt, 3-5 parts of star-shaped SBS elastomer, 0.3-1.2 parts of a hydroxyl-terminated aliphatic hyperbranched polyester macromolecule, and 0.1-0.3 parts of a composite antioxidant. The hydroxyl-terminated aliphatic hyperbranched polyester macromolecule has multiple high-activity hydroxyl groups on the surface of the molecule, can generate a large number of hydrogen bond association nodes at the interface between the continuous phase of the asphalt and the swollen SBS dispersed phase, reduces the interfacial tension of the two phases, and inhibits the floating stratification of the polymer at high temperature from the thermodynamic root. In combination with a corresponding constant-temperature low-speed association ripening process, a continuous and complete interfacial association network can be formed, the agglomeration stratification is avoided during long-term storage, and the engineering use performance is stable.

Description

Technical Field

[0001] This invention belongs to the field of asphalt technology, and particularly relates to a polymer-modified asphalt, its preparation method, and its application. Background Technology

[0002] Currently, asphalt is the core base material for road engineering and waterproofing projects, possessing advantages such as strong adhesion, good plasticity, and low cost. However, virgin matrix asphalt suffers from defects such as easy flow at high temperatures, easy cracking at low temperatures, poor aging resistance, and insufficient water stability, failing to meet the long-term use requirements of high-grade highways and heavy-duty traffic pavements. Polymer-modified asphalt, by adding polymer modifiers to matrix asphalt, can significantly improve the overall performance of asphalt and is currently the mainstream technical direction for asphalt material modification.

[0003] Currently, SBS modified asphalt is the most widely used in engineering applications. SBS elastomers can form an elastic network structure in asphalt, effectively improving the high and low temperature performance of asphalt. However, existing conventional SBS modified asphalt has inherent technical defects: First, SBS is a linear block polymer, and its polarity and solubility parameters differ significantly from those of the base asphalt. The two have poor thermodynamic compatibility, and polymer agglomeration, phase separation, and stratification are prone to occur during high-temperature storage, resulting in poor storage stability and significant performance degradation after long-term storage. Second, conventional SBS modified systems are only physical blending systems. There are no chemical bonds between the polymer and the asphalt, and they only rely on intermolecular forces for interaction. Under the influence of external environments such as high temperature, ultraviolet radiation, and rain erosion, the elastic network is prone to collapse, resulting in poor resistance to thermo-oxidative aging and ultraviolet aging. Road surfaces are prone to rutting, cracking, loosening, water damage, and other diseases. Third, traditional modification schemes often add ordinary small-molecule compatibilizers and polyolefin compatibilizers to improve compatibility. This can only achieve surface physical compatibilization and cannot build a stable structure at the molecular level. The modification effect is limited and easily replaceable, resulting in a significant bottleneck in performance improvement. At the same time, there is a common problem that high-temperature stability and low-temperature crack resistance are mutually restrictive and difficult to achieve simultaneously.

[0004] To solve the above-mentioned technical problems, this invention designs a polymer-modified asphalt, its preparation method, and its application. Summary of the Invention

[0005] This invention provides a polymer-modified asphalt, its preparation method, and its application, aiming to solve the problems of poor storage stability, weak aging resistance, and difficulty in simultaneously achieving high-temperature stability and low-temperature crack resistance in existing modified asphalt.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a polymer-modified asphalt, comprising the following raw materials in parts by weight: 100 parts of base asphalt, 3-5 parts of star-shaped SBS elastomer, 0.3-1.2 parts of hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.1-0.3 parts of composite antioxidant.

[0007] Based on the above technical solution, the terminal hydroxyl aliphatic hyperbranched polyester polymer has a generation number of 2 to 4, a number average molecular weight of 1800 to 3500 g / mol, and a molecular surface hydroxyl functionality of 12 to 24.

[0008] Based on the above technical solution, the star-shaped SBS elastomer is a block copolymer with a block mass ratio of S:B=3:7 and a melt flow rate of 0.8~1.5g / 10min.

[0009] Based on the above technical solution, the base asphalt is 70# or 90# road petroleum base asphalt.

[0010] Based on the above technical solution, the composite antioxidant is antioxidant 1010 and antioxidant 168, and the mass ratio of antioxidant 1010 and antioxidant 168 is 1:2.

[0011] Secondly, the present invention provides a method for preparing polymer-modified asphalt, comprising the following steps: S1, Preheating and dehydration of base asphalt: The base asphalt is put into a closed reaction vessel and heated to 155-165°C. It is stirred at a constant temperature for 10-15 minutes to effectively remove free water and micro bubbles from the asphalt and obtain uniform molten base asphalt. S2, segmented and batch-wise low-speed swelling: Divide the star-shaped SBS elastomer into 2 to 3 equal parts, add each part to the molten matrix asphalt in batches at intervals of 8 to 10 minutes, control the stirring speed, and swell at a constant temperature for a certain period of time to allow the SBS particles to be fully impregnated, stretched, and initially dispersed. S3, Closed-loop high-temperature high-speed shear modification: The system is heated to 170-180℃, and terminal hydroxyl aliphatic hyperbranched polyester polymer is added in one go. The entire process is closed and air is isolated. High-speed shearing is performed for a certain period of time to achieve micron-level uniform dispersion of trace amounts of terminal hydroxyl aliphatic hyperbranched polyester, and to promote hydrogen bond orientation and physical affinity between surface hydroxyl groups and pitch polar components. S4, isothermal dynamic association curing: After shearing, the system is cooled to 160-165℃, and a composite antioxidant is added. The system is then stirred at a constant temperature and low speed for association curing. During the curing stage, the hyperbranched polyester terminal hydroxyl groups undergo multi-point hydrogen bonding and physical entanglement with the asphalt resin, asphaltenes, and SBS molecular chains to construct a continuous three-dimensional interpenetrating network. After association, the system is naturally cooled to room temperature to obtain the finished polymer-modified asphalt.

[0012] Based on the above technical solution, in step S2, the stirring speed is controlled to be 300-400 r / min, and the constant temperature swelling time is 25-35 min.

[0013] Based on the above technical solution, in step S3, the shearing speed is 4500-5500 r / min and the shearing time is 20-25 min.

[0014] Based on the above technical solution, in step S4, the rotation speed of the constant temperature low-speed stirring association maturation is 50~200 r / min, and the time is 40~60 min.

[0015] Thirdly, the present invention provides the application of polymer-modified asphalt prepared according to the above embodiments or by the preparation method of polymer-modified asphalt as described in the above embodiments in road surface materials.

[0016] Compared with related technologies, the beneficial effects of the present invention are as follows: 1. This invention significantly improves the compatibility of asphalt two phases by adding trace amounts of terminal hydroxyl aliphatic hyperbranched polyester as a modifier, and its storage stability is far superior to existing modified products. The terminal hydroxyl aliphatic hyperbranched polyester molecule has multiple highly active hydroxyl groups on its surface, which can generate a large number of hydrogen bond association nodes at the interface between the continuous asphalt phase and the swollen SBS dispersed phase, reducing the interfacial tension between the two phases and inhibiting polymer stratification at high temperatures from a thermodynamic perspective. Combined with a corresponding isothermal low-speed association curing process, a continuous and complete interfacial hydrogen bond association network can be formed. The softening point difference of the polymer-modified asphalt is ≤0.3℃, and there is no agglomeration or stratification during long-term storage, resulting in stable performance in engineering applications.

[0017] 2. The spherical rigid nodes of the terminal hydroxyl aliphatic hyperbranched polyester of the present invention are interspersed in the SBS elastic network to form a three-dimensional spatial constraint structure, which effectively restricts the slippage of asphalt molecules at high temperatures, significantly increases the softening point, and enhances the road surface's resistance to rutting. At the same time, the large amount of free volume inside the terminal hydroxyl aliphatic hyperbranched polyester molecules can disperse shrinkage stress at low temperatures, block the propagation of microcracks, and maintain a low-temperature ductility of more than 28.5 cm at 5°C, without the problem of low-temperature embrittlement. High-temperature stability and low-temperature crack resistance are simultaneously and synergistically improved, making it suitable for various road conditions such as high-temperature heavy loads and severe cold with large temperature differences.

[0018] 3. The dense three-dimensional network formed by hydroxyl association in this invention can act as a physical barrier, preventing oxygen and high-temperature media from penetrating the asphalt matrix and reducing macromolecular oxidation chain scission. The compounded antioxidants 1010 and 168 form a synergistic antioxidant system, simultaneously capturing free radicals and decomposing peroxides. Penetration retention can reach over 87%, with minimal hardening during the mixing and paving stage, resulting in slow performance degradation of the pavement over long-term use.

[0019] 4. The segmented and batch-based low-speed swelling process of this invention allows the SBS elastomer to be fully impregnated and expanded, avoiding local agglomeration caused by one-time feeding; the high-speed shearing stage is completely sealed under negative pressure to isolate air and avoid premature oxidation and loss due to high temperature; the low-speed constant-temperature associative curing process can protect the formed associative network from being torn by turbulence and ensure that the system materials and additives are mixed evenly; the entire set of process parameters is standardized, and the industrial continuous production has high repeatability, and the quality of the engineering products is stable and controllable. Detailed Implementation

[0020] The invention will be further illustrated below with reference to examples: The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0022] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0023] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0024] In the following examples and comparative examples, the base asphalt was purchased from Qilu Petrochemical's 70# and 90# base asphalts; the star-shaped SBS elastomer was purchased from Baling Petrochemical Co., Ltd., model YH-792; the hydroxyl-terminated aliphatic hyperbranched polyester polymer was purchased from Wuhan Hyperbranched Resin Technology Co., Ltd., model HyPer H303; antioxidant 1010 and antioxidant 168 were purchased from BASF (China) Co., Ltd., with antioxidant 1010 model Irganox 1010 and antioxidant 168 model Irgafos 168.

[0025] Example 1 This disclosure provides a polymer-modified asphalt comprising the following raw materials in parts by weight: 100 parts of base asphalt, 3.9 parts of star-shaped SBS elastomer, 0.4 parts of hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.1 parts of composite antioxidant, wherein the composite antioxidant is a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:2.

[0026] This embodiment provides a polymer-modified asphalt, which is prepared by the following method, including the following steps: S1, Preheating and dehydration of base asphalt: 90# base asphalt is put into a closed reaction vessel and heated to 160°C. Stirred at a constant temperature for 12 minutes to completely remove free water and tiny air bubbles from the asphalt and obtain uniformly molten base asphalt. S2, segmented and batch-wise low-speed swelling: Divide the star-shaped SBS elastomer into two equal parts and add them to the molten matrix asphalt at intervals of 9 minutes. Control the stirring speed at 350 r / min and swell at a constant temperature for 30 minutes. S3, Closed-loop high-temperature high-speed shear modification: The system is heated to 175℃, and 3rd generation end-hydroxyl aliphatic hyperbranched polyester polymer is added at one time. The entire process is closed to isolate air. Under closed conditions, high-speed shearing is performed at a speed of 5000r / min for 22min. S4, Constant Temperature Dynamic Association and Maturation: After shearing, the system is cooled to 162℃, a composite antioxidant is added, and the system is stirred at a constant temperature and low speed for 50 minutes at a speed of 100r / min. After association, the system is naturally cooled to room temperature to obtain the finished polymer modified asphalt.

[0027] Example 2 This disclosure provides a polymer-modified asphalt comprising the following raw materials in parts by weight: 100 parts base asphalt, 4.4 parts star-shaped SBS elastomer, 0.7 parts hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.2 parts composite antioxidant. The preparation method is the same as in Example 1.

[0028] Example 3 This disclosure provides a polymer-modified asphalt comprising the following raw materials in parts by weight: 100 parts base asphalt, 5 parts star-shaped SBS elastomer, 1.1 parts hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.2 parts composite antioxidant. The preparation method is the same as in Example 1.

[0029] Example 4 This disclosure provides a polymer-modified asphalt comprising the following raw materials in parts by weight: 100 parts base asphalt, 4.8 parts star-shaped SBS elastomer, 0.8 parts hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.2 parts composite antioxidant. The preparation method is the same as in Example 1.

[0030] Comparative Example 1 This comparative example provides a modified asphalt comprising the following raw materials in parts by weight: 100 parts base asphalt, 4.2 parts star-shaped SBS elastomer, non-terminated hydroxyl aliphatic hyperbranched polyester polymer, and no composite antioxidant.

[0031] The preparation method of the modified asphalt in this comparative example is as follows: the base asphalt is heated to 160°C and then all the star-shaped SBS elastomer is added at one time. After stirring at 350 r / min for 30 min, the temperature is directly raised to 175°C and sheared at 5000 r / min for 22 min. After shearing, the material is directly discharged and cooled to obtain the polymer modified asphalt.

[0032] Comparative Example 2 This comparative example provides a modified asphalt comprising the following raw materials in parts by weight: 100 parts of base asphalt, 15 parts of epoxidized SBS elastomer, 4 parts of carboxyl-terminated hyperbranched polyester, 2 parts of end-epoxy hyperbranched polyester, 4 parts of modified carbon nanotubes, and 0.6 parts of composite anti-aging additive.

[0033] The preparation method of the modified asphalt in this comparative example is as follows: First, epoxidized SBS elastomer, carboxyl-terminated hyperbranched polyester and epoxy-terminated hyperbranched polyester are premixed to form a premix. After the 90# base asphalt is heated to 160℃ and melted, all the premix is ​​added at once. The mixture is stirred at 300r / min for 25min in an open environment. Then, modified carbon nanotubes and anti-aging additives are added in sequence and stirred for another 20min. After stirring, the mixture is directly discharged and cooled to obtain polymer modified asphalt.

[0034] Comparative Example 3 This comparative example provides a modified asphalt comprising the following raw materials in parts by weight: 100 parts base asphalt, 4.3 parts star-shaped SBS elastomer, 3.2 parts hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.5 parts composite antioxidant. The preparation method is the same as in Example 1.

[0035] Comparative Example 4 This comparative example provides a modified asphalt comprising the following raw materials in parts by weight: 100 parts base asphalt, 4.4 parts star-shaped SBS elastomer, 0.7 parts hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.2 parts composite antioxidant. The preparation method is the same as in Example 1.

[0036] The modified asphalt provided in this comparative example is prepared by the following method, including the following steps: S1, Preheating and dehydration of base asphalt: Put 90# base asphalt into a closed reaction vessel and heat it to 160°C. Stir at a constant temperature for 12 minutes to remove free water and tiny air bubbles from the asphalt and obtain uniformly molten base asphalt. S2, segmented and batch-wise low-speed swelling: Divide the star-shaped SBS elastomer into two equal parts and add them to the molten matrix asphalt at intervals of 9 minutes. Control the stirring speed at 350 r / min and swell at a constant temperature for 30 minutes. S3, Closed-loop high-temperature high-speed shear modification: The system is heated to 175℃, and third-generation terminal hydroxyl aliphatic hyperbranched polyester polymer is added in one go. The entire process is closed to isolate air. Under closed conditions, high-speed shearing is performed at a speed of 5000r / min for 22min. After the shearing process is completed, stirring is stopped directly, and the material is discharged naturally to room temperature to obtain modified asphalt.

[0037] According to JTG3410-2025 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering", the polymer-modified asphalt and modified asphalt prepared in the examples and comparative examples were uniformly tested. The test indicators were: penetration at 25℃, softening point, ductility at 5℃, difference in softening point after 48h storage segregation, and penetration retention rate after TFOT film heating and aging. The specific test results are shown in Table 1.

[0038] Table 1. Test results of the polymer-modified asphalt prepared in Examples 1-4 and the modified asphalt in Comparative Examples 1-4.

[0039] The storage segregation difference in all embodiments of this invention is ≤0.3℃, which is far lower than that of pure SBS in Comparative Example 1 (1.8℃), the existing technical formulation in Comparative Example 2 (1.1℃), and the uncured sample in Comparative Example 4 (0.9℃). The storage segregation difference in Comparative Example 3 is 0.6℃, which is higher than that of the embodiments, but still significantly better than that of Comparative Example 1. Although adding excessive hyperbranched polyester has a certain compatibilizing effect, it will seriously sacrifice low-temperature ductility. This proves that the combination of trace amounts of third-generation hydroxyl-terminated hyperbranched polyester and the associative curing process can eliminate two-phase separation at the molecular level, thereby achieving a significant improvement in the storage stability of polymer-modified asphalt.

[0040] In Examples 1-4, the softening point continued to rise as the amount of terminal hydroxyl hyperbranched polyester added increased. In Example 3, when the amount added was 1.1 parts, the softening point reached a maximum of 92.7°C, and the high-temperature deformation resistance was the best, which was much higher than that of Comparative Examples 1, 2 and 4. In Comparative Example 3, the amount of terminal hydroxyl hyperbranched polyester added was too much, and the softening point was 94.2°C. Although the high-temperature stability was excellent, the elongation at 5°C was as low as 20.1 cm, which sacrificed the low-temperature elongation.

[0041] The 5℃ ductility of Comparative Example 1 and Comparative Example 2 were 22.3 cm and 25.7 cm, respectively, indicating poor low-temperature crack resistance. In Comparative Example 3, excessive addition of hyperbranched polyester reduced the ductility to 20.1 cm, causing embrittlement of the modified asphalt. In all embodiments of the present invention, the 5℃ ductility was ≥28.5 cm, while the softening point was significantly improved, solving the problem of mutual restriction between high-temperature and low-temperature performance in the prior art.

[0042] The TFOT penetration retention rate of the embodiments of the present invention is higher than 87%, which is significantly better than that of the comparative example. The present invention relies on the multi-point association of hydroxyl groups to form an association network to form a physical barrier layer, and with the help of composite antioxidants, it can inhibit thermo-oxidative aging in two ways, and has outstanding advantages in long-term service.

[0043] As can be seen from Comparative Example 4, under the same raw material ratio, after omitting the constant temperature association and maturation process in step S4, the segregation difference, low temperature ductility, and aging retention rate all deteriorated. This proves that association and maturation is an indispensable and important step for the present invention to achieve efficient compatibilization of trace polyester and construct a stable three-dimensional network.

[0044] When the amount of terminal hydroxyl hyperbranched polyester exceeds the 0.3-1.2 wt% limit of this invention, the low-temperature ductility decreases significantly, the construction viscosity increases, and the overall road performance deteriorates. This proves that the trace addition range limited by this invention is the optimal synergistic ratio, and that the excellent technical effects of this invention cannot be achieved by any amount.

[0045] The present invention has been described above by way of example, but the present invention is not limited to the specific embodiments described above. Any modifications or variations made based on the present invention are within the scope of protection claimed by the present invention.

Claims

1. A high polymer modified asphalt, characterized by, The raw materials include the following parts by weight: 100 parts of base bitumen, 3-5 parts of star-shaped SBS elastomer, 0.3-1.2 parts of hydroxyl-terminated aliphatic hyperbranched polyester polymer, and 0.1-0.3 parts of composite antioxidant.

2. The polymer-modified bitumen according to claim 1, characterized in that, The terminal hydroxyl aliphatic hyperbranched polyester polymer has a generation number of 2 to 4, a number-average molecular weight of 1800 to 3500 g / mol, and a molecular surface hydroxyl functionality of 12 to 24.

3. The polymer-modified bitumen of claim 1, wherein The star-shaped SBS elastomer is a block copolymer with a block mass ratio of S:B=3:7 and a melt flow rate of 0.8-1.5 g / 10 min.

4. The polymer-modified bitumen of claim 1, wherein The base asphalt is 70# or 90# road petroleum base asphalt.

5. The polymer-modified asphalt according to claim 1, characterized in that, The composite antioxidant is antioxidant 1010 and antioxidant 168, and the mass ratio of antioxidant 1010 to antioxidant 168 is 1:

2.

6. A method for preparing polymer-modified asphalt, characterized in that, Includes the following steps: S1, Preheating and dehydration of base asphalt: The base asphalt is put into a closed reaction vessel and heated to 155-165°C. It is stirred at a constant temperature for 10-15 minutes to remove free water and tiny air bubbles from the asphalt and obtain uniform molten base asphalt. S2, segmented and batch-wise low-speed swelling: Divide the star-shaped SBS elastomer into 2 to 3 equal parts, add each part into the molten matrix asphalt in batches at 8 to 10 minutes interval, control the stirring speed, and swell at a constant temperature for a certain period of time. S3, Closed-loop high-temperature high-speed shear modification: The system is heated to 170-180℃, and terminal hydroxyl aliphatic hyperbranched polyester polymer is added in one go. The entire process is closed to isolate air, and high-speed shearing is performed for a certain period of time. S4, Constant Temperature Dynamic Association and Maturation: After shearing, the system is cooled to 160-165℃, a composite antioxidant is added, and the system is stirred at a constant temperature and low speed for association and maturation. After association, the system is naturally cooled to room temperature to obtain the finished polymer modified asphalt.

7. The preparation method according to claim 6, characterized in that, In step S2, the stirring speed is controlled at 300-400 r / min, and the constant temperature swelling time is 25-35 min.

8. The preparation method according to claim 6, characterized in that, In step S3, the shearing speed is 4500-5500 r / min, and the shearing time is 20-25 min.

9. The preparation method according to claim 6, characterized in that, In step S4, the constant temperature and low speed stirring association maturation speed is 50~200 r / min, and the time is 40~60 min.

10. The application of polymer-modified asphalt prepared by any one of claims 1 to 5 or by any one of claims 6 to 9 in road surface materials.

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