An acrylic resin copolymer modified emulsified asphalt and a method for preparing the same

Abstract

The present application relates to bituminous material preparation technical field, specifically disclose a kind of acrylic resin copolymer modified emulsified asphalt and preparation method thereof, the acrylic resin composite emulsion provided by the present application can form stable reinforcing network in asphalt matrix after blending with emulsified asphalt, wherein, rigid component helps to improve the high-temperature deformation resistance and mechanical strength of material, flexible segment is endowed with good low-temperature toughness, modified lignin as interface compatibilizer and reinforcing point, further optimize the interface combination and overall stability of polymer phase and asphalt phase, so as to improve the high and low temperature resistance and mechanical properties of emulsified asphalt.

Description

Technical Field

[0001] This invention relates to the field of asphalt material preparation technology, specifically to an acrylic resin copolymer modified emulsified asphalt and its preparation method. Background Technology

[0002] Asphalt, as an important building material, has long been widely used in highway, bridge, and airport runway projects due to its good compressive strength, water resistance, and relatively low cost. However, its inherent drawbacks have gradually become apparent, particularly its excessive fluidity at high temperatures and its tendency to crack at low temperatures. Furthermore, its environmental pollution is a pressing issue. Especially during asphalt application, the high-temperature melting and volatility of the asphalt during construction can potentially release harmful volatile organic compounds (VOCs), causing environmental pollution. Therefore, how to improve the performance of asphalt and reduce its environmental impact without sacrificing its inherent properties has become a pressing technical problem in the field of road engineering.

[0003] In recent years, research on emulsified asphalt has received increasing attention. As a new type of environmentally friendly material, emulsified asphalt is gradually becoming one of the alternative materials to asphalt due to its low VOC emissions, low solvent content, and relatively high safety during construction. Emulsified asphalt has good workability and environmental friendliness, but it still has certain shortcomings in terms of low-temperature performance, aging resistance, and mechanical properties. In particular, when water-based emulsified asphalt is exposed to high-temperature or extremely cold climatic conditions, its mechanical properties and durability are limited.

[0004] To address the aforementioned issues, a common method is to modify emulsified asphalt with polymer latex to obtain modified emulsified asphalt. Commonly used polymer latexes include styrene-butadiene latex and styrene-acrylic latex. Styrene-acrylic latex can effectively improve the toughness of asphalt. Its general preparation method involves polymerizing styrene and acrylate to obtain styrene-acrylic latex, then emulsifying the base asphalt to obtain emulsified asphalt. Subsequently, the styrene-acrylic latex and emulsified asphalt are mixed to obtain modified emulsified asphalt. However, with the development of the highway industry, the requirements for the applicable environment of asphalt are becoming increasingly stringent, and the high and low temperature performance of the asphalt products obtained above still needs further improvement. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide an acrylic resin copolymer-modified emulsified asphalt and its preparation method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing acrylic resin copolymer modified emulsified asphalt, comprising the following steps: S1. Preparation of modified lignin Alkali lignin was dissolved in an aqueous solution of dioxane, and then heptadecanylaminoethyl imidazoline and formaldehyde were added to the solution. The mixture was heated and stirred to produce modified lignin.

[0007] In this step, the mass ratio of alkali lignin, heptadecanylaminoethyl imidazoline, and formaldehyde is 10:8-12:5-10. For example, 10:8:5, 10:8:8, 10:8:10, 10:10:5, 10:10:8, 10:10:10, 10:12:5, 10:12:8, and 10:12:10 can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0008] In this step, the mass fraction of the dioxane aqueous solution is 40-60%, for example, 40%, 45%, 50%, 55%, 60%, but not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0009] In this step, the temperature for heating and stirring the reaction is 50-65℃, for example, 50℃, 55℃, 60℃, or 65℃ can be selected; the time for heating and stirring the reaction is 3-6 hours, for example, 3 hours, 4 hours, 5 hours, or 6 hours can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0010] In this step, heptadecanylaminoethylimidazoline contains long-chain alkylene groups, amino groups, and an imidazoline ring. Its amino group can react with formaldehyde to generate an intermediate, which then undergoes a Mannich reaction with the phenolic hydroxyl groups of lignin, grafting the long flexible chain and imidazoline ring structure onto the lignin skeleton. The introduced long-chain alkylene groups enhance the compatibility of lignin with pitch hydrocarbon components and reduce phase separation. At the same time, the introduction of double bond structures facilitates subsequent reactions.

[0011] S2. Preparation of acrylic resin composite emulsion Modified lignin, emulsifier, and tert-dodecyl mercaptan were added to deionized water and stirred until homogeneous. Nitrogen gas was then introduced to purge air. Methyl methacrylate, acrylic acid, and butyl acrylate were then added to the mixture. The mixture was stirred and heated to 55-60°C. Persulfate initiator was added, and the mixture was kept at this temperature for further reaction. After the reaction was completed, an acrylic resin composite emulsion was obtained.

[0012] In this step, the mass ratio of modified lignin, emulsifier, tert-dodecyl mercaptan, methyl methacrylate, acrylic acid, butyl acrylate and persulfate is 4-8:2-4:0.3-0.6:15-20:10-15:20-25:0.5-1.0.

[0013] In this step, the emulsifier is selected from sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, OP-10, AEO-9, or NP-15.

[0014] In this step, the persulfate is selected from sodium persulfate, potassium persulfate, or ammonium persulfate.

[0015] In this step, the heat preservation reaction time is 3-5 hours.

[0016] In this step, through the copolymerization reaction of double bonds, modified lignin becomes part of the acrylic copolymer chain. The rigidity of the polymethyl methacrylate segments in the copolymer and the heat resistance of the lignin aromatic ring structure together improve the asphalt binder's resistance to softening at high temperatures. At the same time, the "reinforcing" effect of the polymer network and the "filling-reinforcing" effect of the modified lignin particles can effectively transfer and disperse stress, improving the strength, toughness, and fatigue resistance of the asphalt. Furthermore, the flexible long chains introduced by the modified lignin help maintain the flexibility of the material at low temperatures, offsetting some of the brittleness risk caused by the increase of rigid components, and improving the low-temperature performance of the asphalt.

[0017] The imidazoline ring in the modified lignin provided by this invention is itself a nitrogen-containing heterocycle. Its nitrogen atom can be protonated and carries a positive charge, exhibiting cationic surface activity, making the modified lignin a kind of emulsion stabilizer, effectively preventing the latex particles generated during polymerization from agglomerating with each other.

[0018] S3. Preparation of acrylic resin copolymer modified emulsified asphalt An acrylic resin composite emulsion is added to emulsified asphalt, and then sheared using a shearing machine to obtain acrylic resin copolymer modified emulsified asphalt.

[0019] In this step, the mass ratio of acrylic resin composite emulsion to emulsified asphalt is 4-8:100. For example, 4:100, 5:100, 6:100, 7:100, and 8:100 can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0020] In this step, the shearing rate is 300-400 r / min, for example, 300 r / min, 320 r / min, 340 r / min, 360 r / min, 380 r / min, or 400 r / min can be selected; the shearing time is 10-20 min, for example, 10 min, 15 min, or 20 min can be selected, but it is not limited to the listed values. Other unlisted values ​​within the range are also applicable.

[0021] The present invention also provides an acrylic resin copolymer modified emulsified asphalt prepared by the above preparation method.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) In this invention, alkali lignin is grafted and modified by the Mannich reaction, and long flexible chains and imidazoline ring structures are grafted onto the lignin skeleton. The introduced long-chain alkenyl groups enhance the compatibility of lignin with pitch hydrocarbon components and reduce phase separation. At the same time, the introduction of double bond structures facilitates the subsequent reaction.

[0023] (2) In this invention, lignin is modified into part of the acrylic copolymer chain through the copolymerization reaction of double bonds. The rigidity of the polymethyl methacrylate chain segment in the copolymer and the heat resistance of the aromatic ring structure of lignin together improve the asphalt binder's resistance to softening at high temperature. At the same time, the "reinforcing" effect of the polymer network and the "filling-reinforcing" effect of the modified lignin particles can effectively transfer and disperse stress, improve the strength, toughness and fatigue resistance of asphalt. Furthermore, the flexible long chain introduced by the modified lignin helps to maintain the flexibility of the material at low temperature, offsetting some of the brittleness risk caused by the increase of rigid components, and improving the low temperature performance of asphalt.

[0024] (3) The acrylic resin composite emulsion provided by the present invention can form a stable reinforcing network in the asphalt matrix after being blended with and dehydrated with emulsified asphalt. The rigid component helps to improve the high temperature resistance and mechanical strength of the material, while the flexible segment provides good low temperature toughness. The modified lignin, as an interface compatibilizer and reinforcing point, further optimizes the interface bonding and overall stability between the polymer phase and the asphalt phase, thereby comprehensively improving the high and low temperature resistance and mechanical properties of emulsified asphalt. Attached Figure Description

[0025] Figure 1 This is a microstructure diagram of the acrylic resin copolymer-modified emulsified asphalt prepared in Example 1 of the present invention. Detailed Implementation

[0026] The present invention will be further described in detail below through specific preferred embodiments, but the present invention is not limited to the following embodiments.

[0027] It should be noted that, unless otherwise specified, all chemical reagents involved in this invention were purchased through commercial channels.

[0028] The alkali lignin used in this embodiment of the invention has a number average molecular weight of 6000-7000 Da; the formaldehyde mass fraction is 37%; the emulsifier is selected from OP-10; the emulsified asphalt is cationic emulsified asphalt with a solid content of 65%, a softening point of 52.6℃, and a ductility (5cm / min, 5℃) of 30.7.

[0029] Example 1 A method for preparing acrylic resin copolymer modified emulsified asphalt includes the following steps: S1. Dissolve 10g of alkali lignin in 150mL of 50wt% dioxane aqueous solution, then add 8g of heptadecanylaminoethyl imidazoline and 5g of formaldehyde. Heat and stir at 50℃ for 6h. After the reaction is complete, remove dioxane by rotary evaporation, precipitate the product with 0.1mol / L HCl solution, and obtain modified lignin by centrifugation, washing and drying. S2. Add 4g of modified lignin, 2g of emulsifier OP-10 and 0.3g of tert-dodecyl mercaptan to 150mL of deionized water, stir well, purge with nitrogen to remove air, then add 15g of methyl methacrylate, 10g of acrylic acid and 20g of butyl acrylate, stir and heat to 55℃, add 0.5g of initiator ammonium persulfate, keep the reaction at 55℃ for 5h, and after the reaction is completed, obtain acrylic resin composite emulsion; S3. Add 40g of acrylic resin composite emulsion to 1000g of emulsified asphalt, and shear it evenly using a shearing machine at a shearing rate of 300r / min for 20min to obtain acrylic resin copolymer modified emulsified asphalt.

[0030] The microstructure of the acrylic resin copolymer-modified emulsified asphalt prepared in this embodiment is as follows: Figure 1 As shown, from Figure 1 As can be seen, the modified emulsified asphalt microdroplets are approximately spherical in shape, relatively uniform in size, and evenly distributed with no obvious agglomeration, demonstrating good dispersion stability.

[0031] Example 2 A method for preparing acrylic resin copolymer modified emulsified asphalt includes the following steps: S1. Dissolve 10g of alkali lignin in 150mL of 50wt% dioxane aqueous solution, then add 12g of heptadecanylaminoethyl imidazoline and 10g of formaldehyde, heat and stir at 65℃ for 3h. After the reaction is completed, remove dioxane by rotary evaporation, precipitate the product with 0.1mol / L HCl solution, centrifuge, wash and dry to obtain modified lignin. S2. Add 6g of modified lignin, 3g of emulsifier OP-10 and 0.5g of tert-dodecyl mercaptan to 150mL of deionized water, stir well, purge with nitrogen to remove air, then add 18g of methyl methacrylate, 12g of acrylic acid and 22g of butyl acrylate, stir and heat to 60℃, add 0.8g of initiator ammonium persulfate, keep the reaction at 60℃ for 3h, and after the reaction is completed, obtain acrylic resin composite emulsion; S3. Add 50g of acrylic resin composite emulsion to 1000g of emulsified asphalt, and shear it evenly using a shearing machine at a shearing rate of 300r / min for 20min to obtain acrylic resin copolymer modified emulsified asphalt.

[0032] Example 3 A method for preparing acrylic resin copolymer modified emulsified asphalt includes the following steps: S1. Dissolve 10g of alkali lignin in 150mL of 50wt% dioxane aqueous solution, then add 10g of heptadecanylaminoethyl imidazoline and 8g of formaldehyde, heat and stir at 60℃ for 4h. After the reaction is completed, remove dioxane by rotary evaporation, precipitate the product with 0.1mol / L HCl solution, centrifuge, wash and dry to obtain modified lignin. S2. Add 8g of modified lignin, 4g of emulsifier OP-10 and 0.6g of tert-dodecyl mercaptan to 150mL of deionized water, stir well, purge with nitrogen to remove air, then add 20g of methyl methacrylate, 15g of acrylic acid and 25g of butyl acrylate, stir and heat to 60℃, add 1g of initiator ammonium persulfate, keep the reaction at 60℃ for 3h, and after the reaction is completed, obtain acrylic resin composite emulsion; S3. Add 60g of acrylic resin composite emulsion to 1000g of emulsified asphalt, and shear it evenly using a shearing machine at a shearing rate of 400r / min for 10min to obtain acrylic resin copolymer modified emulsified asphalt.

[0033] Example 4 A method for preparing acrylic resin copolymer modified emulsified asphalt includes the following steps: S1. Dissolve 10g of alkali lignin in 150mL of 50wt% dioxane aqueous solution, then add 8g of heptadecenylamine ethyl imidazoline and 8g of formaldehyde, heat and stir at 60℃ for 4h. After the reaction is completed, remove dioxane by rotary evaporation, precipitate the product with 0.1mol / L HCl solution, centrifuge, wash and dry to obtain modified lignin. S2. Add 6g of modified lignin, 3g of emulsifier OP-10 and 0.5g of tert-dodecyl mercaptan to 150mL of deionized water, stir well, purge with nitrogen to remove air, then add 18g of methyl methacrylate, 12g of acrylic acid and 25g of butyl acrylate, stir and heat to 55℃, add 0.8g of initiator ammonium persulfate, keep the reaction at 55℃ for 5h, and after the reaction is completed, obtain acrylic resin composite emulsion; S3. Add 80g of acrylic resin composite emulsion to 1000g of emulsified asphalt, and shear it evenly using a shearing machine at a shearing rate of 400r / min for 10min to obtain acrylic resin copolymer modified emulsified asphalt.

[0034] Comparative Example 1 A method for preparing acrylic resin copolymer modified emulsified asphalt includes the following steps: S1. Add 4g of emulsifier OP-10 and 0.6g of tert-dodecyl mercaptan to 150mL of deionized water, stir well, purge with nitrogen to remove air, then add 20g of methyl methacrylate, 15g of acrylic acid and 25g of butyl acrylate, stir and heat to 60℃, add 1g of initiator ammonium persulfate, keep the reaction at 60℃ for 3h, and after the reaction is completed, obtain acrylic resin composite emulsion; S2. Add 60g of acrylic resin composite emulsion to 1000g of emulsified asphalt, and shear it evenly using a shearing machine at a shearing rate of 400r / min for 10min to obtain acrylic resin copolymer modified emulsified asphalt.

[0035] Compared with Comparative Example 1 and Example 3, no modified lignin was added.

[0036] Comparative Example 2 A method for preparing acrylic resin copolymer modified emulsified asphalt includes the following steps: S1. Add 8g of alkali lignin, 4g of emulsifier OP-10 and 0.6g of tert-dodecyl mercaptan to 150mL of deionized water, stir well, purge with nitrogen to remove air, then add 20g of methyl methacrylate, 15g of acrylic acid and 25g of butyl acrylate, stir and heat to 60℃, add 1g of initiator ammonium persulfate, keep the reaction at 60℃ for 3h, and after the reaction is completed, obtain acrylic resin composite emulsion; S2. Add 60g of acrylic resin composite emulsion to 1000g of emulsified asphalt, and shear it evenly using a shearing machine at a shearing rate of 400r / min for 10min to obtain acrylic resin copolymer modified emulsified asphalt.

[0037] Compared with Comparative Example 2 and Example 3, no modification treatment was performed on the alkali lignin.

[0038] Comparative Example 3 A method for preparing acrylic resin copolymer modified emulsified asphalt includes the following steps: S1. Add 8g heptadecylamine ethyl imidazoline, 4g emulsifier OP-10 and 0.6g tert-dodecyl mercaptan to 150mL of deionized water, stir well, purge with nitrogen to remove air, then add 20g methyl methacrylate, 15g acrylic acid and 25g butyl acrylate, stir and heat to 60℃, add 1g initiator ammonium persulfate, keep the reaction at 60℃ for 3h, and after the reaction is completed, obtain acrylic resin composite emulsion; S2. Add 60g of acrylic resin composite emulsion to 1000g of emulsified asphalt, and shear it evenly using a shearing machine at a shearing rate of 400r / min for 10min to obtain acrylic resin copolymer modified emulsified asphalt.

[0039] Compared with Comparative Example 3 and Example 3, alkali lignin was replaced with heptadecenylaminoethyl imidazoline.

[0040] The acrylic resin copolymer modified emulsified asphalts prepared in Examples 1-4 and Comparative Examples 1-3 of this invention were subjected to performance testing. The softening point, ductility and penetration of the evaporation residue of the modified emulsified asphalt were tested in accordance with the method of JTG-E202025 "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering". The test results are shown in Table 1.

[0041] Table 1 Performance test results for different groups As can be seen from Table 1, compared with Comparative Examples 1-3, the acrylic resin copolymer modified emulsified asphalt prepared by the present invention has a higher softening point and greater low-temperature ductility, indicating that the modified emulsified asphalt obtained by the present invention has better high and low temperature resistance.

[0042] The evaporation residues of the acrylic resin copolymer modified emulsified asphalt prepared in Example 3 and Comparative Examples 1-3 of this invention were tested for viscosity toughness and low-temperature flexural creep properties. The test methods were based on JTG-E202025 "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering". The test results are shown in Table 2.

[0043] Table 2. Mechanical performance test results for different groups As can be seen from Table 2, compared with Comparative Examples 1-3, the acrylic resin copolymer modified emulsified asphalt prepared in this example has excellent viscosity, toughness and low-temperature performance.

[0044] Finally, it should be noted that the above embodiments do not limit the present invention in any way. Those skilled in the art can make modifications and improvements based on the present invention. Therefore, any modifications or improvements made without departing from the spirit of the present invention are within the scope of protection claimed by the present invention.

Claims

1. A method for preparing acrylic resin copolymer modified emulsified asphalt, characterized in that, Includes the following steps: S1. Dissolve alkali lignin in dioxane aqueous solution, then add heptadecanylaminoethyl imidazoline and formaldehyde, heat and stir to react, and obtain modified lignin. S2. Add modified lignin, emulsifier and tert-dodecyl mercaptan to deionized water, stir evenly, purge with nitrogen to remove air, then add methyl methacrylate, acrylic acid and butyl acrylate, stir and heat to 55-60℃, add initiator persulfate, keep the reaction at the temperature, and after the reaction is completed, obtain acrylic resin composite emulsion. S3. Add the acrylic resin composite emulsion to the emulsified asphalt and shear it using a shearing machine to obtain the acrylic resin copolymer modified emulsified asphalt. In step S1, the mass ratio of alkali lignin, heptadecanylaminoethyl imidazoline and formaldehyde is 10:8-12:5-10. In step S1, the temperature for heating and stirring the reaction is 50-65℃, and the reaction time is 3-6 hours. In step S2, the mass ratio of modified lignin, emulsifier, tert-dodecyl mercaptan, methyl methacrylate, acrylic acid, butyl acrylate and persulfate is 4-8:2-4:0.3-0.6:15-20:10-15:20-25:0.5-1.

0.

2. The preparation method according to claim 1, characterized in that, In step S2, the persulfate is selected from sodium persulfate, potassium persulfate, or ammonium persulfate.

3. The preparation method according to claim 1, characterized in that, In step S2, the heat preservation reaction time is 3-5 hours.

4. The preparation method according to claim 1, characterized in that, In step S3, the mass ratio of acrylic resin composite emulsion to emulsified asphalt is 4-8:

100.

5. The preparation method according to claim 1, characterized in that, In step S3, the shearing rate is 300-400 r / min and the shearing time is 10-20 min.

6. Acrylic resin copolymer modified emulsified asphalt prepared by the preparation method according to any one of claims 1-5.

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