Double-layer composite wall material reducing agent sustained-release microcapsule as well as preparation method and application thereof
By using the reducing agent sustained-release microcapsules coated with double-layer composite wall materials, the problem of single-layer microcapsules being prone to rupture during asphalt mixing is solved, and a more stable and slow reduction agent release is achieved, which significantly improves the anti-aging performance of asphalt pavement.
Patent Information
- Application Number
- CN202510169782.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-17
- Publication Date
- 2025-05-09
AI Technical Summary
Existing single-layer sustained-release microcapsules are prone to rupture when mixed with asphalt, resulting in premature leakage of reducing agents, weakening the sustained-release function, and affecting the anti-aging performance of asphalt pavement.
The preparation method of double-layer composite wall reducing agent sustained release microcapsules is adopted. By wrapping a single-layer microcapsule in a composite wall aqueous solution, the mechanical properties of the microcapsules are enhanced by combining wall materials such as chitosan, gum arabic and nanosilicon dioxide.
It significantly extends the acting time of the reducing agent, improves the anti-aging performance of the asphalt, ensures the stability and sustained release performance of the reducing agent, and reduces the cost of pavement aging and maintenance.
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Abstract
Description
Technical Field
[0001] The invention relates to the technical field of highway maintenance, and in particular to a double-layer composite wall material reducing agent slow-release microcapsule and a preparation method and application thereof. Background Art
[0002] With the development of my country's highway industry, the scale of high-grade highway construction has continued to increase, and the quality requirements for asphalt pavements have become higher and higher. In particular, the greenhouse effect has continued to worsen in recent years, and extreme high temperature weather has become more frequent. The research on the mechanical properties of asphalt pavements has also received more attention. Due to the poor durability and weather resistance of ordinary asphalt pavements, they are prone to cracking, rutting, aging and other problems, which reduce the quality and service life of the pavement and increase the maintenance cost. In general, if the asphalt pavement is only functionally damaged, overhauling or even re-paving will result in a waste of resources.
[0003] Emulsified asphalt is melted at high temperature, mechanically stirred, dispersed into particles and suspended in an aqueous solution containing an emulsifier to form an oil-in-water asphalt emulsion. Emulsified asphalt is liquid at room temperature, avoiding the heating process before construction. It can be sprayed, spread or mixed at room temperature. Therefore, spraying emulsified asphalt on the aged asphalt pavement through the corresponding equipment can renew and restore the aged asphalt on the road surface, while protecting the asphalt that has not yet aged, so that it maintains its original performance and slows down the aging time. During maintenance, the performance of the pavement can be maintained by simply repairing pavement cracks, preventive maintenance of horizontal and vertical cracks, and local or large-scale crack maintenance.
[0004] Studies have shown that wrapping the reducing agent with a suitable wall material to make a single-layer slow-release microcapsule can prolong the time of the reducing agent's action and improve the anti-aging performance of asphalt. However, since the single-layer slow-release microcapsules are easily broken during the process of mixing with asphalt to make modified asphalt, the wrapped reducing agent core material leaks out prematurely, which weakens the slow-release function of the microcapsules, affects the use effect of modified asphalt, accelerates the aging of asphalt pavements, and increases the cost of road maintenance. As a result, the purpose of specific release and controlled release cannot be achieved, and the optimization effect is not obvious. Therefore, it is urgent to improve the mechanical properties of slow-release microcapsules to improve the anti-aging ability of asphalt pavements. Summary of the invention
[0005] The invention provides a double-layer composite wall material reducing agent slow-release microcapsule and a preparation method and application thereof, aiming to solve the problem that the existing single-layer slow-release microcapsule has poor mechanical properties and cannot effectively improve the anti-aging ability of asphalt pavement.
[0006] To achieve its purpose, the present invention adopts the following technical solution: A method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule comprises the following steps: (1) preparing a single-layer microcapsule; first, dissolving β-cyclodextrin in water and heating to obtain a β-cyclodextrin clear solution with a concentration of 5 to 9 wt%, then dissolving a reducing agent in an ethanol solution at a volume ratio of 1:15 to 25 to obtain a reducing agent solution, finally adding the reducing agent solution to the β-cyclodextrin clear solution, heating and stirring to mix, then refrigerating to precipitate, filtering, washing, and drying to obtain a single-layer microcapsule; (2) preparing a composite wall material aqueous solution; firstly, mixing the wall material and silicon dioxide at a mass ratio of 1.5 to 2.5:1 to obtain a composite wall material, then adding the composite wall material into hot water, shearing and dispersing it, and then cooling it to room temperature to obtain a composite wall material aqueous solution; (3) preparing double-layer composite wall material reducing agent sustained-release microcapsules; adding the single-layer microcapsules obtained in step (1) to the composite wall material aqueous solution in step (2), emulsifying evenly and shaking at a constant temperature, and spray drying or freeze drying to obtain double-layer composite wall material reducing agent sustained-release microcapsules.
[0007] Furthermore, in step (1), the heating temperature when the β-cyclodextrin is dissolved in water is 40-70°C; when the reducing agent solution and the β-cyclodextrin clarified solution are mixed, the heating and stirring temperature is 40-70°C, the stirring rate is 300-500rpm, and the stirring time is 4-6h; and the refrigeration temperature is 0-4°C.
[0008] Furthermore, in step (1), the reducing agent is one or a mixture of unsaturated fatty acids, aromatic compounds or surfactants; and the molar ratio of the reducing agent to β-cyclodextrin is 1:0.6-1.4.
[0009] Furthermore, in step (2), the wall material is one of chitosan, gum arabic, soy protein, modified starch or polyvinyl alcohol, and the concentration of the composite wall material aqueous solution is 5-10wt%; the silicon dioxide is nano silicon dioxide with a particle size of 20-60nm; the temperature of the hot water added with the composite wall material is 80-100°C, and the shear dispersion is performed by a high-speed disperser at 8000-12000r / min for 1-2min.
[0010] Furthermore, the weight ratio of the composite wall material in the composite wall material aqueous solution of step (2) to the single-layer microcapsules in step (1) is 1:3-5.
[0011] Furthermore, in step (3), the inlet temperature of the spray drying is 170-230°C, the outlet temperature is 90-100°C, and the air volume is 750-850m 3 / h, the feed rate is 15-25ml / min, the pressure pump is 0.1-0.4MPa; the freezing temperature of freeze drying is -70--50℃, the freezing time is 4-6h, the vacuum pressure of the drying chamber is <10Pa; the temperature of constant temperature oscillation is 40-70℃.
[0012] The double-layer composite wall material reducing agent sustained-release microcapsules are prepared by the preparation method.
[0013] A double-layer composite wall material reducing agent slow-release microcapsule modified asphalt comprises 4-6 parts of double-layer composite wall material reducing agent slow-release microcapsules and 94-96 parts of road asphalt in parts by mass.
[0014] Furthermore, according to the formula, the double-layer composite wall material reducing agent slow-release microcapsules and road asphalt are heated and mixed respectively, and stirred until fully melted to obtain the double-layer composite wall material reducing agent slow-release microcapsules modified asphalt.
[0015] Furthermore, the double-layer composite wall material reducing agent slow-release microcapsules and road asphalt are heated in an oven, the heating temperature is 155-165° C., the heating time is 1-3 hours, and the stirring speed is 550-650 rpm.
[0016] The beneficial effects of the present invention are as follows: 1. The single-layer microcapsules and double-layer composite wall material reducing agent sustained-release microcapsules prepared by the method of the present invention were tested for reducing agent retention rate under the same temperature conditions, and the double-layer microcapsules formed by coating with a single wall material under the same conditions were observed as a control. The results showed that the reducing agent release rate in the double-layer composite wall material reducing agent sustained-release microcapsules was the slowest and the reducing agent retention rate was the highest, indicating that the sustained-release performance of the three was compared, the double-layer composite wall material reducing agent sustained-release microcapsules> double-layer microcapsules> single-layer microcapsules, and the double-layer composite wall material reducing agent sustained-release microcapsules can effectively prolong the action time of the reducing agent. After the double-layer composite wall material reducing agent sustained-release microcapsules prepared by the present invention are mixed with road asphalt, the reducing agent repairs the road surface damage caused by aging, cracking, potholes, looseness, etc. through the processes of penetration and curing, replenishes the asphalt components lost due to aging and cracking of the road surface layer, and restores the viscoelastic properties of the asphalt. The reducing agent core wrapped by the double-layer composite wall material reducing agent sustained-release microcapsules is not easy to leak, and the sustained-release performance is better, which prolongs the action time of the reducing agent and effectively improves the anti-aging ability of the asphalt.
[0017] 2. The materials used in the preparation of the composite wall material aqueous solution are all high molecular polymers with highly complex clustered branches. There are a large number of hydrogen bonds inside the molecules, which make them have good physical and mechanical properties such as adsorption and moisture retention. When used as wall materials, they can prevent premature leakage of internal reducing agents. In addition, nano-silicon dioxide has a small particle size, a large specific surface area, a strong adsorption capacity, good chemical stability, and high temperature resistance. As a wall material, it has a significant sustained-release effect, which can effectively improve the performance of microcapsules, realize the protection and controlled release of reducing agents, and the overall preparation process is green and environmentally friendly, and can realize automated production. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1This is a comparison chart of the high temperature sustained-release performance of the single-layer / double-layer / double-layer composite wall material reducing agent sustained-release microcapsules in Example 1 of the present invention; Figure 2 This is a comparison chart of high temperature sustained-release performance of single-layer / double-layer / double-layer composite wall material reducing agent sustained-release microcapsules in Example 2 of the present invention; Figure 3 This is a comparison chart of high temperature sustained-release performance of single-layer / double-layer / double-layer composite wall material reducing agent sustained-release microcapsules in Example 3 of the present invention; Figure 4 This is a comparison chart of component contents of the single-layer / double-layer / double-layer composite wall material reducing agent slow-release microcapsule modified asphalt after short-term aging in Examples 1-3 of the present invention; Figure 5 This is a comparison chart of component contents of the single-layer / double-layer / double-layer composite wall material reducing agent slow-release microcapsule modified asphalt after long-term aging in Examples 1-3 of the present invention; Figure 6 This is a scanning electron microscope photograph of the double-layer composite wall material reducing agent sustained-release microcapsule in Example 1 of the present invention. DETAILED DESCRIPTION
[0019] The present invention will be further described below in conjunction with embodiments: In the following embodiments of the present invention, double-layer microcapsules are prepared by coating single-layer microcapsules with a single wall material, and the double-layer microcapsules are used as a control to compare with the double-layer composite wall material reducing agent sustained-release microcapsules prepared in the present invention to analyze the improvement of the reducing agent retention rate and the anti-aging property of asphalt.
[0020] Example 1 The present invention is a method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule, comprising the following steps: (1) Preparation of single-layer microcapsules D1; first, weigh 7 g of β-cyclodextrin, dissolve it in 100 ml of distilled water, and heat it to 50°C to obtain a β-cyclodextrin clear solution with a concentration of 7 wt%; then weigh linolenic acid at a molar ratio of 1:1 to β-cyclodextrin, add it as a reducing agent into an anhydrous ethanol solution to dissolve it to obtain a reducing agent solution, wherein the volume ratio of the reducing agent to anhydrous ethanol is 1:20; finally, add the reducing agent solution into the β-cyclodextrin clear solution, heat and stir at 50°C for 5 h, and the stirring rate is 300 rpm, so that the β-cyclodextrin clear solution and the reducing agent solution are fully mixed, and then refrigerate at 0°C to precipitate it, and obtain the single-layer microcapsules D1 after filtering, washing, and drying; (2) Preparation of double-layer microcapsules D2: First, 8 g of chitosan was dissolved in 100 ml of water to obtain a wall material aqueous solution with a concentration of 8%, and then the single-layer microcapsules D1 obtained in step (1) were added to the wall material aqueous solution at a weight ratio of 1:4 to the wall material. After the emulsification was uniform, the mixture was shaken at a constant temperature of 50°C and spray-dried to obtain double-layer microcapsules D2; wherein the inlet temperature of the spray-drying was 200°C, the outlet temperature was 95°C, and the air inlet volume was 750m3. 3 / h, feed rate is 20ml / min, pressure pump is 0.1MPa; (3) preparing a composite wall material aqueous solution; first, chitosan and 20 nm silica were mixed at a mass ratio of 1.5:1 to obtain a composite wall material, then the composite wall material was added to 80°C hot water, sheared and dispersed at 8000 r / min for 2 min using a high-speed disperser, and cooled to room temperature to obtain a composite wall material aqueous solution with a concentration of 8%; (4) preparing double-layer composite wall material reducing agent sustained-release microcapsules D3; adding the single-layer microcapsules D1 obtained in step (1) to the composite wall material aqueous solution obtained in step (3) at a weight ratio of composite wall material to single-layer microcapsules D1 of 1:4, and after being emulsified uniformly, shaking at a constant temperature of 50°C, and spray drying to obtain double-layer composite wall material reducing agent sustained-release microcapsules D3. The scanning electron microscope photograph of the obtained double-layer composite wall material reducing agent sustained-release microcapsules is as follows: Figure 6 As shown; wherein, the parameters of spray drying are the same as those in step (2).
[0021] The single-layer microcapsule D1, double-layer microcapsule D2 and double-layer composite wall material reducing agent slow-release microcapsule D3 are used to prepare single-layer reducing agent slow-release microcapsule modified asphalt A1, double-layer reducing agent slow-release microcapsule modified asphalt A2 and double-layer composite wall material reducing agent slow-release microcapsule modified asphalt A3, respectively, comprising the following steps: (1) According to the formula, 5 parts of single-layer microcapsules D1, 5 parts of double-layer microcapsules D2, 5 parts of double-layer composite wall material reducing agent slow-release microcapsules D3 and 95 parts of road asphalt were placed in an oven at 160°C and heated for 2 h; (2) In an oven at 160°C, the heated single-layer microcapsules D1, double-layer microcapsules D2, and double-layer composite wall material reducing agent slow-release microcapsules D3 were added to road asphalt, and stirred at a speed of 600 rpm until fully melted, thereby obtaining single-layer reducing agent slow-release microcapsule modified asphalt A1, double-layer reducing agent slow-release microcapsule modified asphalt A2, and double-layer composite wall material reducing agent slow-release microcapsule modified asphalt A3, respectively.
[0022] Example 2 The present invention is a method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule, comprising the following steps: (1) Preparation of single-layer microcapsules F1; first, weigh 5 g of β-cyclodextrin, dissolve it in 100 ml of distilled water, and heat it at 40°C to obtain a β-cyclodextrin clear solution with a concentration of 5 wt%; then weigh p-hydroxybenzaldehyde at a molar ratio of 1:1.4 to β-cyclodextrin, add it as a reducing agent into an anhydrous ethanol solution to dissolve it to obtain a reducing agent solution, wherein the volume ratio of the reducing agent to anhydrous ethanol is 1:15; finally, add the reducing agent solution into the β-cyclodextrin clear solution, heat and stir at 40°C for 4 h, and stir at a rate of 400 rpm to fully mix the β-cyclodextrin clear solution and the reducing agent solution, and then refrigerate at 4°C to precipitate it, and filter, wash, and dry to obtain single-layer microcapsules F1; (2) Preparation of double-layer microcapsules F2: first, dissolving 5 g of chitosan in 100 ml of water to obtain a 5% wall material aqueous solution, then adding the single-layer microcapsules F1 obtained in step (1) to the wall material aqueous solution at a weight ratio of 1:3 between the wall material and the single-layer microcapsules F1, and after uniform emulsification, shaking at a constant temperature of 40° C., and freeze-drying to obtain double-layer microcapsules F2; wherein the freezing temperature of freeze-drying is -70° C., the freezing time is 4 h, and the vacuum pressure of the drying chamber is 9 Pa; (3) Preparing a composite wall material aqueous solution; first, mixing soybean protein and 40 nm silica at a mass ratio of 2:1 to obtain a composite wall material, then adding the composite wall material into 90°C hot water, using a high-speed disperser to shear and disperse at 10,000 r / min for 1 min, and cooling to room temperature to obtain a 5% composite wall material aqueous solution; (4) preparing double-layer composite wall material reducing agent sustained-release microcapsules F3; adding the single-layer microcapsules D1 obtained in step (1) to the composite wall material aqueous solution obtained in step (3) at a weight ratio of composite wall material to single-layer microcapsules F1 of 1:3, and after being emulsified uniformly, shaking at a constant temperature of 40° C., and freeze-drying to obtain double-layer composite wall material reducing agent sustained-release microcapsules F3; wherein the freeze-drying parameters are the same as those in step (2).
[0023] The single-layer microcapsule F1, double-layer microcapsule F2 and double-layer composite wall material reducing agent slow-release microcapsule F3 are used to prepare single-layer reducing agent slow-release microcapsule modified asphalt B1, double-layer reducing agent slow-release microcapsule modified asphalt B2 and double-layer composite wall material reducing agent slow-release microcapsule modified asphalt B3, respectively, comprising the following steps: (1) According to the formula, 4 parts of single-layer microcapsules F1, 4 parts of double-layer microcapsules F2, 4 parts of double-layer composite wall material reducing agent slow-release microcapsules F3 and 96 parts of road asphalt were placed in an oven at 155°C and heated for 1 hour; (2) In an oven at 155°C, the heated single-layer microcapsules F1, double-layer microcapsules F2, and double-layer composite wall material reducing agent slow-release microcapsules F3 were added to road asphalt, and stirred at a speed of 550 rpm until fully melted, thereby obtaining single-layer reducing agent slow-release microcapsule modified asphalt B1, double-layer reducing agent slow-release microcapsule modified asphalt B2, and double-layer composite wall material reducing agent slow-release microcapsule modified asphalt B3, respectively.
[0024] Example 3 The present invention is a method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule, comprising the following steps: (1) Preparation of single-layer microcapsules H1; first, weigh 9 g of β-cyclodextrin, dissolve it in 100 ml of distilled water, and heat it to 70°C to obtain a β-cyclodextrin clear solution with a concentration of 9 wt%; then weigh an alkyl polyoxyethylene ether with a molar ratio of 1:0.6 to β-cyclodextrin, add it as a reducing agent into an anhydrous ethanol solution to dissolve it to obtain a reducing agent solution, wherein the volume ratio of the reducing agent to anhydrous ethanol is 1:25; finally, add the reducing agent solution into the β-cyclodextrin clear solution, heat and stir at 70°C for 6 h, and the stirring rate is 500 rpm, so that the β-cyclodextrin clear solution and the reducing agent solution are fully mixed, and then refrigerate at 2°C to precipitate it, and filter, wash, and dry to obtain single-layer microcapsules H1; (2) Preparation of double-layer microcapsules H2: First, 10 g of chitosan was dissolved in 100 ml of water to obtain a 10% wall material aqueous solution, and then the single-layer microcapsules H1 obtained in step (1) were added to the wall material aqueous solution at a weight ratio of 1:5 to the wall material. After the emulsification was uniform, the mixture was shaken at a constant temperature of 70°C and spray-dried to obtain double-layer microcapsules H2; wherein the inlet temperature of the spray-drying was 230°C, the outlet temperature was 100°C, and the air inlet volume was 850m 3 / h, feed rate is 25ml / min, pressure pump is 0.4MPa; (3) Preparing a composite wall material aqueous solution; first, polyvinyl alcohol and 60 nm silicon dioxide were mixed at a mass ratio of 2.5:1 to obtain a composite wall material, then the composite wall material was added to 100° C. hot water, and a high-speed disperser was used for shear dispersion at 12000 r / min for 1 min, and then cooled to room temperature to obtain a 10% composite wall material aqueous solution; (4) preparing double-layer composite wall material reducing agent sustained-release microcapsules H3; adding the single-layer microcapsules H1 obtained in step (1) to the composite wall material aqueous solution obtained in step (3) at a weight ratio of composite wall material to single-layer microcapsules H1 of 1:5, and after being emulsified uniformly, shaking at a constant temperature of 70° C., and spray drying to obtain double-layer composite wall material reducing agent sustained-release microcapsules H3; wherein the spray drying parameters are the same as those in step (2).
[0025] The single-layer microcapsule H1, double-layer microcapsule H2 and double-layer composite wall material reducing agent slow-release microcapsule H3 are used to prepare single-layer reducing agent slow-release microcapsule modified asphalt C1, double-layer reducing agent slow-release microcapsule modified asphalt C2 and double-layer composite wall material reducing agent slow-release microcapsule modified asphalt C3, respectively, comprising the following steps: (1) According to the formula, 6 parts of single-layer microcapsules H1, 6 parts of double-layer microcapsules H2, 6 parts of double-layer composite wall material reducing agent slow-release microcapsules H3 and 94 parts of road asphalt were placed in an oven at 165°C and heated for 1 h; (2) In an oven at 165°C, the heated single-layer microcapsules H1, double-layer microcapsules H2, and double-layer composite wall material reducing agent slow-release microcapsules H3 were added to road asphalt, and stirred at a speed of 650 rpm until fully melted, thereby obtaining single-layer reducing agent slow-release microcapsule modified asphalt C1, double-layer reducing agent slow-release microcapsule modified asphalt C2, and double-layer composite wall material reducing agent slow-release microcapsule modified asphalt C3, respectively.
[0026] The high temperature sustained release performance of the single-layer microcapsules, double-layer microcapsules and double-layer composite wall material reducing agent sustained-release microcapsules prepared in Examples 1-3 was tested by an oven heating method. Specifically, the single-layer microcapsules, double-layer microcapsules and double-layer composite wall material reducing agent sustained-release microcapsules were evenly spread on a culture dish, and then placed in a blast drying oven, and dried continuously at 80°C for 30 hours, and samples were taken every 2 hours. The amount of reducing agent retained in the microcapsules was calculated by the mass change. The test results are shown in FIG. Figure 1-3 shown.
[0027] analyze Figure 1-3 It can be seen that after continuous baking in an oven at 80°C for 30 hours, the reducing agent retention rate in the single-layer microcapsule is as low as 47.3%, and the reducing agent retention rate in the double-layer microcapsule coated with a single wall material is as low as 54.9%, and the reducing agent retention rate only increases by 7.6%. The reducing agent retention rate in the double-layer composite wall material reducing agent sustained-release microcapsules prepared by the method of the present invention is as low as 72.5%, and the reducing agent retention rate increases by 25.2%, which is 3.3 times the reducing agent retention rate of the double-layer microcapsules. In addition, during the baking process, the reducing agent release rate in the single-layer microcapsules, double-layer microcapsules and double-layer composite wall material reducing agent sustained-release microcapsules shows an obvious slowing trend. The reducing agent release rate in the double-layer composite wall material reducing agent sustained-release microcapsules is the slowest and the reducing agent retention rate is the highest, indicating that compared with the sustained-release performance of the three, the double-layer composite wall material reducing agent sustained-release microcapsules>double-layer microcapsules>single-layer microcapsules, and the double-layer composite wall material reducing agent sustained-release microcapsules have better sustained-release performance, which can effectively prolong the action time of the reducing agent and significantly improve the anti-aging performance of asphalt.
[0028] In actual use, the content of asphaltene, colloid, saturated components and aromatic components in asphalt are important bases for judging asphalt aging, and asphalt aging is divided into short-term aging and long-term aging. Short-term aging adopts the rotating thin film oven test method (RTFO) to simulate the aging of asphalt during mixing, transportation, storage and paving; long-term aging adopts the pressure vessel aging test method (PAV) to accelerate the aging of asphalt with high temperature and compressed air, which is used to simulate the oxidative aging of asphalt during road use. All modified asphalt samples prepared in Examples 1-3 were subjected to short-term aging and long-term aging, and the contents of the four components were measured. The short-term aging results are shown in the figure. Figure 4 As shown, the long-term aging results are Figure 5 shown.
[0029] analyze Figure 4-5 It can be seen that after aging of asphalt, the content of asphaltene and colloid increased, and the content of saturated fraction did not change significantly. The base asphalt without slow-release microcapsules of reducing agent significantly reduced the content of aromatic fraction after short-term and long-term aging, while the rate of reduction of aromatic fraction of all modified asphalts A1 to C3 with slow-release microcapsules of reducing agent significantly decreased after short-term and long-term aging, indicating that the base asphalt was more seriously aged than the modified asphalt A1 to C3, and the addition of reducing agent microcapsules to asphalt could significantly slow down its aging process. For the same reducing agent, whether it is short-term aging or long-term aging, the slow-release microcapsules of reducing agent in double-layer composite wall material can more effectively improve the anti-aging property of asphalt.
Claims
1. A method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule, characterized in that: The following steps are involved: (1) preparing a single-layer microcapsule; first, dissolving β-cyclodextrin in water and heating to obtain a β-cyclodextrin clear solution with a concentration of 5 to 9 wt%, then dissolving a reducing agent in an ethanol solution at a volume ratio of 1:15 to 25 to obtain a reducing agent solution, finally adding the reducing agent solution to the β-cyclodextrin clear solution, heating and stirring to mix, then refrigerating to precipitate, filtering, washing, and drying to obtain a single-layer microcapsule; (2) preparing a composite wall material aqueous solution; firstly, mixing the wall material and silicon dioxide at a mass ratio of 1.5 to 2.5:1 to obtain a composite wall material, then adding the composite wall material into hot water, shearing and dispersing it, and then cooling it to room temperature to obtain a composite wall material aqueous solution; (3) preparing double-layer composite wall material reducing agent sustained-release microcapsules; adding the single-layer microcapsules obtained in step (1) to the composite wall material aqueous solution in step (2), emulsifying evenly and shaking at a constant temperature, and spray drying or freeze drying to obtain double-layer composite wall material reducing agent sustained-release microcapsules.
2. The method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule according to claim 1, characterized in that: In step (1), the heating temperature when the β-cyclodextrin is dissolved in water is 40-70°C; when the reducing agent solution and the β-cyclodextrin clarified solution are mixed, the heating and stirring temperature is 40-70°C, the stirring rate is 300-500rpm, and the stirring time is 4-6h; the refrigeration temperature is 0-4°C.
3. The method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule according to claim 2, characterized in that: In step (1), the reducing agent is one or a mixture of unsaturated fatty acids, aromatic compounds or surfactants; the molar ratio of the reducing agent to β-cyclodextrin is 1:0.6-1.
4.
4. The method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule according to claim 3, characterized in that: In step (2), the wall material is one of chitosan, gum arabic, soy protein, modified starch or polyvinyl alcohol, and the concentration of the composite wall material aqueous solution is 5-10wt%; the silicon dioxide is nano silicon dioxide with a particle size of 20-60nm; the temperature of the hot water added to the composite wall material is 80-100°C, and a high-speed disperser is used for shear dispersion at 8000-12000 r / min for 1-2 minutes.
5. The method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule according to claim 4, characterized in that: The weight ratio of the composite wall material in the composite wall material aqueous solution of step (2) to the single-layer microcapsules in step (1) is 1:3-5.
6. The method for preparing a double-layer composite wall material reducing agent sustained-release microcapsule according to claim 5, characterized in that: In step (3), the inlet temperature of the spray drying is 170-230°C, the outlet temperature is 90-100°C, and the air volume is 750-850m 3 / h, the feed rate is 15-25ml / min, the pressure pump is 0.1-0.4MPa; the freezing temperature of freeze drying is -70--50℃, the freezing time is 4-6h, the vacuum pressure of the drying chamber is <10Pa; the temperature of constant temperature oscillation is 40-70℃.
7. A double-layer composite wall material reducing agent sustained-release microcapsule prepared by the preparation method according to any one of claims 1 to 6.
8. A double-layer composite wall material reducing agent slow-release microcapsule modified asphalt, characterized in that: Calculated by weight, it comprises 4-6 parts of the double-layer composite wall material reducing agent slow-release microcapsules as claimed in claim 7 and 94-96 parts of road asphalt.
9. The method for preparing a double-layer composite wall material reducing agent slow-release microcapsule modified asphalt according to claim 8, characterized in that: According to the formula, the double-layer composite wall material reducing agent slow-release microcapsules and road asphalt are heated separately and then mixed, and stirred until fully melted to obtain the double-layer composite wall material reducing agent slow-release microcapsule modified asphalt.
10. The method for preparing a double-layer composite wall material reducing agent slow-release microcapsule modified asphalt according to claim 9, characterized in that: The double-layer composite wall material reducing agent slow-release microcapsules and road asphalt are heated in an oven at a temperature of 155-165° C. for 1-3 hours; the stirring speed is 550-650 rpm.