Preparation method and application of ductility enhancer for SBS (styrene-butadiene-styrene) modified asphalt

Abstract

The invention relates to the technical field of road asphalt, in particular to a ductility improver for SBS modified asphalt as well as a preparation method and application of the ductility improver for SBS modified asphalt, and the preparation method of the ductility improver for SBS modified asphalt comprises the following steps: adding phosphoric acid into tert-butyl alcohol to obtain a solution; adding epoxidized soybean oil and deionized water into tert-butyl alcohol to obtain a mixed solution, dropwise adding the mixed solution into the solution for reaction, and performing washing and rotary evaporation to obtain phosphoric acid modified epoxidized soybean oil; adding polyether polyol, isocyanate and a catalyst into a reaction container for reaction, adding the phosphoric acid modified epoxidized soybean oil and the modified nano silicon dioxide, and continuously reacting to obtain the ductility enhancer. The ductility improver for the SBS modified asphalt prepared by the invention has an excellent ductility increasing effect, the preparation method is simple, the heat resistance is good, and the ductility improver is not easy to separate out.

Description

Technical Field

[0001] This invention relates to the field of road asphalt technology, specifically to a method for preparing and applying an elastomeric agent for SBS modified asphalt. Background Technology

[0002] Asphalt is a complex mixture composed of hydrocarbons and their derivatives, commonly used in road construction, waterproofing projects, and other fields. Asphalt itself has inherent defects, such as easy flow at high temperatures and brittleness at low temperatures. While SBS (styrene-butadiene-styrene block copolymer), a mainstream modifier, can significantly improve the high-temperature stability and elasticity of asphalt, its large difference in polarity with asphalt leads to insufficient compatibility. Furthermore, its low-temperature ductility index still fails to meet the requirements for crack resistance in cold regions and high-grade highways. Simply increasing the amount of SBS also increases production costs. To address this contradiction, ductile additives have emerged. Their technological development has gradually evolved from early single plasticizing additives (such as phthalates) to reactive / synergistic additives (such as maleic anhydride grafts and vegetable oil-based complexes). These additives weaken intermolecular forces by inserting into polymer molecular chains and forming physicochemical interactions with SBS and asphalt components. This improves low-temperature ductility while also enhancing compatibility and thermal stability. Some products can even reduce the amount of SBS used, aligning with the needs of green sustainability and engineering economics.

[0003] Patent CN119350864A discloses a ductile agent for SBS modified asphalt, SBS modified asphalt, and its preparation method. The ductile agent for SBS modified asphalt provided by this invention includes POE, DOA, and epoxidized vegetable oil. POE possesses weather resistance, aging resistance, and toughening properties; DOA has good anti-aging properties; and epoxidized vegetable oil has plasticizing properties. Both POE and DOA have good compatibility with DOA, and both also have good compatibility with the SBS required for subsequent applications. The synergistic effect of POE, DOA, and epoxidized vegetable oil improves the compatibility between the base asphalt and the modifier, greatly improving the storage performance and low-temperature performance of asphalt materials, and effectively mitigating problems such as rutting and cracking in asphalt pavements. However, DOA and epoxidized vegetable oil are both small molecules that easily migrate out of SBS modified asphalt, leading to a long-term decrease in compatibility.

[0004] Patent CN109971195B discloses a modified asphalt and its preparation method, comprising the following components in parts by weight: 90-94 parts base asphalt; 1-5 parts SBS 4303; 1-2 parts SBS LG501; 1-2 parts compatibilizer; 0.5-1 part elastomeric agent; and 0.1-0.3 parts stabilizer. The elastomeric agent is furfural extract oil. The modified asphalt provided by this invention has excellent performance and meets the prescribed standards. However, furfural extract oil is prone to volatilization at high temperatures, which can accelerate the hardening and cracking of the modified asphalt.

[0005] Therefore, there is an urgent need in the market for a ductile agent for SBS modified asphalt with excellent ductile properties and heat resistance. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to obtain an SBS modified asphalt ductile agent with excellent ductile and heat resistance properties, and which is simple to prepare and does not easily precipitate.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: This invention provides a method for preparing an elastomeric agent for SBS modified asphalt, comprising the following steps: S1. Add phosphoric acid to tert-butanol and reflux at 60-65℃ for 20-30 min to obtain a solution; add epoxidized soybean oil and deionized water to tert-butanol and stir for 5-10 min to obtain a mixture; add the mixture dropwise to the solution and heat to 85-95℃ to react for 5-7 h to obtain the product; add the product to ethyl acetate, stir to dissolve, add to a separatory funnel, wash, and rotary evaporate to obtain phosphoric acid modified epoxidized soybean oil; S2. Add polyether polyol, isocyanate, and catalyst to a reaction vessel and react at 70-80℃ for 1-2 hours. Cool down to 60-70℃, add phosphoric acid-modified epoxidized soybean oil and modified nano-silica obtained in step S1, and react for 1-2 hours to obtain the elastomeric agent.

[0008] This application first uses phosphoric acid-modified epoxidized soybean oil, then reacts it with polyether polyol, modified nano-silica, and isocyanate to prepare a novel polymer material. This polymer material has a polyether structure in its main chain and epoxy and phosphate groups on its side chains, enabling it to form good compatibility and synergistic effects with SBS and asphalt molecules. This is likely because the polyether segments themselves have good miscibility and affinity with the oil components in asphalt, allowing them to be uniformly dispersed in the asphalt matrix like a "lubricant." Simultaneously, the flexible long chains of the polyether main chain can physically entangle and interpenetrate with the polybutadiene soft segments in the SBS molecules, physically binding the ductile agent and the SBS network together. This enhances the connection between SBS molecules and prevents phase separation and floating of SBS due to poor compatibility with asphalt, greatly improving the stability of the system. The phosphate groups have strong polarity and reactivity, and can interact strongly with highly polar substances in asphalt, including forming hydrogen bonds, acid-base interactions, and even esterification reactions. This strong interaction ensures that the ductile agent is tightly anchored in the asphalt matrix, making it difficult for it to precipitate. The strong interfacial bonding force allows stress to be effectively transferred between the two phases, thereby improving the strength, ductility, heat resistance and crack resistance of SBS modified asphalt. This ductile agent is not only suitable for ordinary SBS and asphalt, but can also be widely used in modified SBS and special asphalt products, such as asphalt for cold regions and high crack resistance asphalt, providing a wider range of applications for SBS and asphalt and meeting the needs of different environments and projects.

[0009] In some embodiments, the mass ratio of phosphoric acid to epoxidized soybean oil is (0.08-0.12):1.

[0010] In some embodiments, the mass ratio of the polyether polyol to the isocyanate is (1.8-2.8):1.

[0011] In some embodiments, the polyether polyol is one or more of PEG, PPG, and PTMG.

[0012] Preferably, the polyether polyol is PTMG.

[0013] In some embodiments, the mass ratio of isocyanate to phosphoric acid-modified epoxidized soybean oil in step S2 is 1:(0.4-0.8).

[0014] In some embodiments, the catalyst is an organometallic catalyst.

[0015] Preferably, the catalyst is dibutyltin dilaurate.

[0016] In some embodiments, the mass ratio of isocyanate to modified nano-silica in step S2 is 1:(0.15-0.25). In some embodiments, the method for preparing the modified nano-silica includes the following steps: adding KH-550 silane coupling agent to an aqueous ethanol solution, adding nano-silica, sonicating at 40-50°C for 2-3 hours, and drying to obtain modified nano-silica.

[0017] Preferably, the mass ratio of the KH-550 silane coupling agent to nano-silica is (0.01-0.05):1.

[0018] This application utilizes the amino-containing silane coupling agent KH-550 to modify nano-silica. This not only imbues the surface of the nano-silica with active groups capable of reacting with isocyanate groups, improving the dispersibility of the modified nano-silica in the ductile agent, but also, through the formation of urea groups, further enhances the toughness and heat resistance of the SBS-modified asphalt matrix by constructing a strong dynamic hydrogen bond network. The uniform dispersion of nano-silica particles within the SBS-modified asphalt matrix effectively blocks the intrusion of oxygen and ultraviolet radiation, delaying the oxidation and aging process of the asphalt and giving the SBS-modified asphalt matrix long-lasting ductility.

[0019] In some embodiments, the average particle size of the nano-silica is 10-30 nm.

[0020] Another aspect of the present invention provides an application of a ductile agent for SBS modified asphalt, wherein the ductile agent is present in an amount of 1-5 wt% in the SBS modified asphalt.

[0021] Compared with the prior art, the present invention has the following beneficial effects: (1) The extruder prepared by reacting phosphoric acid modified epoxidized soybean oil with polyether polyol, modified nano silica and isocyanate has excellent extrudement and heat resistance properties, and the preparation process is simple and not easy to precipitate.

[0022] (2) The main chain of the ductile agent prepared by the present invention contains a polyether structure, and the side chain contains epoxy groups and phosphate groups. The polyether segments have good compatibility with SBS and asphalt molecules. The epoxy groups and phosphate groups are tightly anchored in the asphalt matrix by hydrogen bonding with the polar substances in the asphalt, making it difficult for the ductile agent to precipitate. This not only prevents the phase separation and floating of SBS due to poor compatibility with asphalt, but also builds a strong interfacial bond so that stress can be effectively transferred between the two phases, thereby improving the strength, ductility and crack resistance of SBS modified asphalt.

[0023] (3) By using KH-550 modified nano-silica, the modified nano-silica can be linked with the ductile agent through urea bonds, which not only improves its dispersibility in the ductile agent, but also constructs a strong dynamic hydrogen bond network, further enhancing the toughness and heat resistance of the SBS modified asphalt matrix. Furthermore, the nano-silica particles can effectively block the intrusion of oxygen and ultraviolet light, delaying the oxidation and aging process of asphalt, thus giving the SBS modified asphalt matrix long-lasting ductility. Detailed Implementation

[0024] The present invention will be described below with reference to specific embodiments. It should be noted that the following embodiments are examples of the present invention and are used only to illustrate the invention, not to limit it. Other combinations and various modifications within the scope of the present invention can be made without departing from its spirit or scope.

[0025] In the following examples and comparative examples, the compounds and related reagents used were all commercially available. The average particle size of the nano-silica was 20 nm, and it was purchased from Shanghai Maoguo Nanotechnology Co., Ltd. The number average molecular weight of PTMG was 1000. The CAS number of epoxidized soybean oil was 8013-07-8.

[0026] Preparation Example 1 The preparation method of modified nano-silica includes the following steps: adding 0.3g of KH-550 silane coupling agent to 70g of 85wt% ethanol aqueous solution, adding 10g of nano-silica, sonicating at 45℃ for 2.5h, and drying to obtain modified nano-silica.

[0027] Example 1 A method for preparing an elastomeric agent for SBS modified asphalt includes the following steps: S1. Add 10g of phosphoric acid to 15g of tert-butanol and reflux at 62℃ for 25min to obtain a solution; add 100g of epoxidized soybean oil and 10g of deionized water to 25g of tert-butanol and stir for 8min to obtain a mixture. Add the mixture dropwise to the solution and heat to 90℃ for 6h to obtain the product. Add the product to ethyl acetate, stir to dissolve, add to a separatory funnel, wash with deionized water until neutral, and take the upper layer liquid for rotary evaporation to obtain phosphoric acid modified epoxidized soybean oil. S2. Add 23g PTMG, 10g MDI, and 0.1g dibutyltin dilaurate to the reaction vessel and react at 75℃ for 1.5h. Cool down to 65℃, add 6g of phosphoric acid modified epoxidized soybean oil obtained in step S1 and 2g of modified nano silica, and react for 1.5h to obtain the elastomeric agent.

[0028] Example 2 A method for preparing an elastomeric agent for SBS modified asphalt includes the following steps: S1. Add 8g of phosphoric acid to 15g of tert-butanol and reflux at 60℃ for 30min to obtain a solution; add 100g of epoxidized soybean oil and 10g of deionized water to 25g of tert-butanol and stir for 5min to obtain a mixture. Add the mixture dropwise to the solution and heat to 85℃ for 7h to obtain the product. Add the product to ethyl acetate, stir to dissolve, add to a separatory funnel, wash with deionized water until neutral, and take the upper layer liquid for rotary evaporation to obtain phosphoric acid modified epoxidized soybean oil. S2. Add 18g PTMG, 10g MDI, and 0.1g dibutyltin dilaurate to the reaction vessel and react at 70℃ for 2h. Then, cool the mixture to 60℃, add 4g of phosphoric acid-modified epoxidized soybean oil obtained in step S1 and 1.5g of modified nano-silica, and react for 2h to obtain the elongation agent.

[0029] Example 3 A method for preparing an elastomeric agent for SBS modified asphalt includes the following steps: S1. Add 12g of phosphoric acid to 15g of tert-butanol and reflux at 65℃ for 20min to obtain a solution; add 100g of epoxidized soybean oil and 10g of deionized water to 25g of tert-butanol and stir for 10min to obtain a mixture. Add the mixture dropwise to the solution and heat to 95℃ for 5h to obtain the product. Add the product to ethyl acetate, stir to dissolve, add to a separatory funnel, wash with deionized water until neutral, and take the upper layer liquid for rotary evaporation to obtain phosphoric acid modified epoxidized soybean oil. S2. Add 28g PTMG, 10g MDI, and 0.1g dibutyltin dilaurate to a reaction vessel and react at 80℃ for 1h. Then, cool the mixture to 70℃, add 8g of phosphoric acid-modified epoxidized soybean oil obtained in step S1 and 2.5g of modified nano-silica, and react for 1h to obtain the elongation agent.

[0030] Example 4 An SBS-modified asphalt ductile agent and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the amount of phosphoric acid added is 14g.

[0031] Example 5 An SBS-modified asphalt ductile agent and its preparation method are disclosed. The specific implementation method is the same as in Example 1, except that the amount of PTMG added is 32g.

[0032] Example 6 An SBS-modified asphalt elastomeric agent and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the amount of phosphoric acid-modified epoxidized soybean oil added in step S2 is 2g.

[0033] Example 7 An SBS-modified asphalt ductile agent and its preparation method are disclosed. The specific implementation method is the same as that in Example 1, except that the amount of modified nano-silica added in step S2 is 3.5g.

[0034] Comparative Example 1 A method for preparing an elastomeric agent for SBS modified asphalt includes the following steps: S1. Add 10g of phosphoric acid to 15g of tert-butanol and reflux at 62℃ for 25min to obtain a solution; add 100g of epoxidized soybean oil and 10g of deionized water to 25g of tert-butanol and stir for 8min to obtain a mixture. Add the mixture dropwise to the solution and heat to 90℃ for 6h to obtain the product. Add the product to ethyl acetate, stir to dissolve, add to a separatory funnel, wash with deionized water until neutral, and take the upper layer liquid for rotary evaporation to obtain phosphoric acid modified epoxidized soybean oil. S2. Add 23g PTMG, 10g MDI, and 0.1g dibutyltin dilaurate to the reaction vessel and react at 75℃ for 1.5h. Then, cool the mixture to 65℃, add 6g of phosphoric acid-modified epoxidized soybean oil obtained in step S1, and react for 1.5h to obtain the elastomeric agent.

[0035] Comparative Example 2 A method for preparing an elastomeric agent for SBS modified asphalt includes the following steps: 23g PTMG, 10g MDI, and 0.1g dibutyltin dilaurate are added to a reaction vessel and reacted at 75°C for 1.5h. The temperature is then lowered to 65°C, 6g epoxidized soybean oil and 2g modified nano silica are added, and the reaction is continued for 1.5h to obtain the elastomeric agent.

[0036] Comparative Example 3 Epoxidized soybean oil is used directly as a lengthening agent.

[0037] Performance testing The SBS modified asphalt elastomeric agents obtained in the above embodiments and comparative examples were added to SBS modified asphalt (purchased from Beijing Herun Wantong Road Engineering Co., Ltd., model MS2MS3) at an addition amount of 3 wt%, and blended. After blending, the performance of each blended sample was tested according to the technical standard "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" JTG 3410-2025. The test results are shown in Table 1. Table 1

[0038] As shown in Table 1, the elastomeric agents of Examples 1-3 of this invention have a good elastomeric effect, resulting in well-prepared blended samples with good elongation properties and suitable penetration. Even after heating, they maintain good elastomeric properties and suitable penetration. A comparison between Example 4 and Example 1 shows that changing the ratio of phosphoric acid and epoxidized soybean oil increases the phosphate group content in the elastomeric agent, leading to a large number of cross-linked network structures reacting with the asphalt matrix, thus reducing the elastomeric properties of the blended samples. A comparison between Example 5 and Example 1 shows that changing the ratio of polyether polyol and isocyanate makes it difficult for phosphoric acid-modified epoxidized soybean oil and modified nano-silica to react with isocyanate, resulting in a decrease in the elastomeric properties and heat resistance of the blended samples. A comparison between Example 6 and Example 1 shows that changing the ratio of isocyanate to phosphoric acid-modified epoxidized soybean oil... The reduced interaction between the ductile agent and SBS-modified asphalt leads to a decrease in the ductility and heat resistance of the blended sample. A comparison between Example 7 and Example 1 shows that changing the ratio of isocyanate to modified nano-silica decreases the aging resistance of both the ductile agent and SBS-modified asphalt, resulting in a decrease in the ductility of the blended sample. A comparison between Comparative Example 1 and Example 1 shows that without the addition of modified nano-silica, the decreased aging resistance of both the ductile agent and SBS-modified asphalt leads to poorer ductility of the blended sample. A comparison between Comparative Example 2 and Example 1 shows that directly adding epoxidized soybean oil to prepare the ductile agent results in a blended sample with poor ductility. A comparison between Comparative Example 3 and Example 1 shows that directly adding epoxidized soybean oil as a ductile agent results in a blended sample with poor ductility and heat resistance.

[0039] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing an elastomeric agent for SBS modified asphalt, characterized in that, Includes the following steps: S1. Add phosphoric acid to tert-butanol and reflux at 60-65℃ for 20-30 min to obtain a solution; add epoxidized soybean oil and deionized water to tert-butanol and stir for 5-10 min to obtain a mixture; add the mixture dropwise to the solution and heat to 85-95℃ to react for 5-7 h to obtain the product; add the product to ethyl acetate, stir to dissolve, add to a separatory funnel, wash, and rotary evaporate to obtain phosphoric acid modified epoxidized soybean oil; S2. Add polyether polyol, isocyanate, and catalyst to a reaction vessel and react at 70-80℃ for 1-2 hours. Cool down to 60-70℃, add phosphoric acid-modified epoxidized soybean oil and modified nano-silica obtained in step S1, and react for 1-2 hours to obtain the elastomeric agent.

2. The method for preparing the SBS-modified asphalt ductile agent according to claim 1, characterized in that, The mass ratio of phosphoric acid to epoxidized soybean oil is (0.08-0.12):

1.

3. The method for preparing the SBS-modified asphalt ductile agent according to claim 1, characterized in that, The mass ratio of the polyether polyol to the isocyanate is (1.8-2.8):

1.

4. The method for preparing the SBS-modified asphalt ductile agent according to claim 1, characterized in that, The polyether polyol is one or more of PEG, PPG, and PTMG.

5. The method for preparing the SBS-modified asphalt ductile agent according to claim 1, characterized in that, The mass ratio of isocyanate to phosphoric acid modified epoxidized soybean oil in step S2 is 1:(0.4-0.8).

6. The method for preparing the SBS-modified asphalt ductile agent according to claim 1, characterized in that, The catalyst is an organometallic catalyst.

7. The method for preparing the SBS-modified asphalt ductile agent according to claim 1, characterized in that, The mass ratio of isocyanate to modified nano-silica in step S2 is 1:(0.15-0.25).

8. The method for preparing the SBS-modified asphalt ductile agent according to claim 1, characterized in that, The method for preparing the modified nano-silica includes the following steps: adding KH-550 silane coupling agent to an ethanol aqueous solution, adding nano-silica, sonicating at 40-50℃ for 2-3 hours, and drying to obtain modified nano-silica.

9. The method for preparing the SBS-modified asphalt ductile agent according to claim 8, characterized in that, The average particle size of the nano-silica is 10-30 nm.

10. The application of an SBS-modified asphalt ductile agent obtained by the preparation method according to any one of claims 1-9, characterized in that, The content of the elastomeric agent in the SBS modified bitumen is 1-5 wt%.

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