Preparation method of polypyrrole / melamine resin double-shell microcapsules

Abstract

This invention relates to a method for preparing polypyrrole / melamine resin double-shell microcapsules, belonging to the field of asphalt repair agents. Specifically, it involves a polypyrrole / melamine resin double-shell microcapsule and its preparation method, addressing the problems of traditional asphalt pavement repair methods being time-consuming, energy-intensive, and having a significant impact on traffic. This invention incorporates polypyrrole / melamine resin double-shell electrothermal self-healing microcapsules into asphalt pavements, which can both repair the pavement and remove snow accumulation. The steps include: 1) mixing an emulsifier with water, adding a pH adjuster, heating, adjusting the pH value, cooling to room temperature, and washing to obtain self-healing microcapsules; 2) immersing the prepared self-healing microcapsules successively in pyrrole and oxidant solutions, allowing pyrrole to polymerize on the surface of the microcapsules, and then immersing them in distilled water to remove excess pyrrole monomers and oxidant to obtain a polypyrrole / melamine resin double-shell electrothermal self-healing microgel.

Description

Technical Field

[0001] This invention belongs to the field of asphalt repair agents, specifically relating to a microcapsule with a polypyrrole / melamine resin double-shell structure and its preparation method. Background Technology

[0002] Snow accumulation on asphalt roads in winter poses a serious threat to traffic safety. Current snow removal methods are inefficient and have a significant impact on pavement durability and the environment. Furthermore, asphalt roads suffer aging damage under environmental and load factors, especially surface damage, which not only affects pavement lifespan but also endangers traffic safety. Traditional asphalt pavement repair methods are time-consuming and energy-intensive, causing significant disruption to traffic and inconveniencing daily travel. To address these issues, a layer of conductive polypyrrole is coated onto the surface of microcapsules containing asphalt repair agents. Incorporating these electrothermal self-healing microcapsules with a polypyrrole / melamine resin double-shell structure into asphalt pavements can both repair the road surface and remove snow accumulation. Summary of the Invention

[0003] The purpose of this invention is to provide a microcapsule with a polypyrrole / melamine resin double-shell structure and its preparation method.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a polypyrrole / melamine resin bilayer shell microcapsule includes the following steps: 1) Preparation of self-healing microcapsules: Emulsifier and water were mixed, and a pH adjuster was added to adjust the pH value. The mixture was stirred at 400 rpm for 2 hours, then the asphalt repair agent core liquid was added, and the stirring speed was increased to 5000 rpm for high-speed emulsification for 15 minutes. The stirring speed was reduced to 400 rpm, and the wall material was added dropwise to the emulsion at a rate of 5 ml / min. After the wall material was added, the temperature was uniformly increased at a rate of 2 degrees Celsius / min. When the temperature reached 60 degrees Celsius, the pH was adjusted again to 4 using the pH adjuster. The temperature was then increased to 80 degrees Celsius and stabilized for 2 hours. After cooling to room temperature, the microcapsules were washed to obtain self-healing microcapsules. 2) Chemical preparation of the polypyrrole layer: The self-healing microcapsules prepared in step 1 were successively immersed in pyrrole and oxidant solutions, allowing pyrrole to polymerize on the surface of the microcapsules. Afterwards, the microcapsules were immersed in distilled water to remove excess pyrrole monomers and oxidant, resulting in an electrothermal self-healing microgel with a polypyrrole / melamine resin double-shell structure.

[0005] The emulsifier is styrene maleic anhydride, OP-10, Span-80, Tween-80, or sodium dodecyl sulfate.

[0006] The wall material is one of epoxy resin, melamine resin, phenolic resin, unsaturated polyester resin, and sodium alginate.

[0007] The core fluid is a mixture of liquid dodecane, tetradecane, hexadecane, octadecane, and paraffin.

[0008] The mass ratio of the emulsifier, core material, and wall material is 1:(5-10):(5-30).

[0009] The oxidant is one of ferric chloride, ammonium persulfate, hydrogen peroxide, and potassium iodate.

[0010] The concentration of pyrrole monomer is 0.8-2 mol / L, and the concentration of oxidant is 0.4-1 mol / L.

[0011] This application also includes a polypyrrole / melamine resin double-shell microcapsule obtained by the preparation method described above, wherein the thermal decomposition temperature of the microcapsule is 300-350 degrees Celsius.

[0012] Compared with the prior art, the beneficial effects of the present invention are: This invention coats the surface of self-healing microcapsules with a layer of polypyrrole conductive material, increasing the electrical and thermal conductivity of the microcapsules. It also increases the strength of the microcapsules, ensuring they are only destroyed when microcracks appear in the asphalt, preventing premature rupture and release of the repair agent. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the process for preparing polypyrrole / melamine resin bilayer shell microcapsules according to the present invention; Figure 2 The image shows a scanning electron microscope (SEM) image of the polypyrrole / melamine resin bilayer shell microcapsule prepared in Example 1. Detailed Implementation

[0014] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and preferred embodiments.

[0015] Example 1: Preparation method of polypyrrole / melamine resin double shell structure microcapsules The specific preparation method is as follows: The preparation method is divided into two steps. (1) The first step is the preparation of self-healing microcapsules: 1.5 g of styrene maleic anhydride is mixed with 400 ml of water and then 5% sodium hydroxide solution is added to adjust the pH value to 10. Stir at 400 rpm for 2 hours. Add 15 g of asphalt repair agent and increase the speed to 5000 rpm for high-speed emulsification for 15 minutes. Adjust the speed to 400 rpm and add 30 g of wall material methyl methacrylate (polymerization degree of 300) dropwise to the emulsion at a rate of 5 ml / min. Heat at a rate of 2 degrees Celsius / min. When the temperature rises to 60 degrees Celsius, start slowly adding 2% acetic acid solution and continue heating. When the pH value is adjusted to 4, stop adding 2% acetic acid solution and continue heating to 80 degrees Celsius for stable polymerization for 2 hours. After cooling to room temperature, wash to obtain self-healing microcapsules. (2) Then, the polypyrrole layer was prepared by chemical method: The self-healing microcapsules containing the repair agent prepared in step (1) were immersed in a 0.8 mol / L pyrrole solution for 1 hour, and then quickly transferred to a 0.3 mol / L ferric chloride solution for 1 hour. After that, the obtained microcapsules were immersed in distilled water for more than 12 hours to remove excess pyrrole monomers and attached oxidants, resulting in electrothermal self-healing microcapsules with a polypyrrole / melamine resin double-shell structure containing the repair agent. The mass ratio of the core material to the wall material of the prepared microcapsules was 1:2, so the shell of the microcapsules was thick and the stability of the microcapsules was high. However, the cost of making the microcapsules was high.

[0016] Example 2: Preparation method of polypyrrole / melamine resin double shell structure microcapsules The specific preparation method is as follows: The preparation method is divided into two steps. (1) The first step is the preparation of self-healing microcapsules: 1.5 g of styrene maleic anhydride is mixed with 400 ml of water and then 5% sodium hydroxide solution is added to adjust the pH value to 10. Stir at 400 rpm for 2 hours. Add 15 g of asphalt repair agent and increase the speed to 5000 rpm for high-speed emulsification for 15 minutes. Adjust the speed to 400 rpm and add 30 g of wall material methyl methacrylate (polymerization degree of 300) dropwise to the emulsion at a rate of 5 ml / min. Heat at a rate of 2 degrees Celsius / min. When the temperature rises to 60 degrees Celsius, start slowly adding 2% acetic acid solution and continue heating. When the pH value is adjusted to 4, stop adding 2% acetic acid solution and continue heating to 80 degrees Celsius for stable polymerization for 2 hours. After cooling to room temperature, wash to obtain self-healing microcapsules. (2) Then, the polypyrrole layer was prepared by chemical method: The self-healing microcapsules containing the repair agent prepared in step (1) were immersed in a 1 mol / L pyrrole solution for 1 hour, and then quickly transferred to a 0.3 mol / L ferric chloride solution for 1 hour. After that, the obtained microcapsules were immersed in distilled water for more than 12 hours to remove excess pyrrole monomers and attached oxidants, resulting in electrothermal self-healing microcapsules with a polypyrrole / melamine resin double-shell structure containing the repair agent. The shell thickness of the prepared microcapsules was consistent with that in Example 1. Due to the increased concentration of pyrrole monomers in step 2, the polypyrrole on the surface of the self-healing microcapsules was more dense and its conductivity was increased.

[0017] Example 3: Preparation method of polypyrrole / melamine resin double shell structure microcapsules The specific preparation method is as follows: The preparation method is divided into two steps. (1) The first step is the preparation of self-healing microcapsules: 1.5 g of styrene maleic anhydride is mixed with 400 ml of water and then 5% sodium hydroxide solution is added to adjust the pH value to 10. Stir at 400 rpm for 2 hours. Add 15 g of asphalt repair agent and increase the speed to 5000 rpm for high-speed emulsification for 15 minutes. Adjust the speed to 400 rpm and add 15 g of wall material methyl hydroxymethyl melamine resin (polymerization degree of 300) dropwise to the emulsion at a rate of 5 ml / min. Heat at a uniform rate of 2 degrees Celsius / min. When the temperature rises to 60 degrees Celsius, start slowly adding 2% acetic acid solution and continue to heat. When the pH value is adjusted to 4, stop adding 2% acetic acid solution and continue to heat to 80 degrees Celsius for stable polymerization for 2 hours. After cooling to room temperature, wash to obtain self-healing microcapsules. (2) Then, the polypyrrole layer was prepared by chemical method: The self-healing microcapsules containing the repair agent prepared in step (1) were immersed in a 1 mol / L pyrrole solution for 1 hour, and then quickly transferred to a 0.8 mol / L ferric chloride solution for 1 hour. After that, the obtained microcapsules were immersed in distilled water for more than 12 hours to remove excess pyrrole monomers and attached oxidants, resulting in electrothermal self-healing microcapsules with a polypyrrole / melamine resin double-shell structure containing the repair agent. The ratio of the core material to the wall material of the prepared microcapsules was 1:1, and the shell thickness was reduced, but the manufacturing cost was greatly reduced. Due to the increased concentration of the oxidant in step two, the polymerization rate of the pyrrole monomers increased, the pyrrole polymerized more densely on the capsule surface, and the conductivity increased.

[0018] Example 4: Preparation method of polypyrrole / melamine resin double shell structure microcapsules The specific preparation method is as follows: The preparation method is divided into two steps. (1) The first step is the preparation of self-healing microcapsules: 1.5 g of styrene maleic anhydride is mixed with 400 ml of water and then 5% sodium hydroxide solution is added to adjust the pH value to 10. Stir at 400 rpm for 2 hours. Add 15 g of asphalt repair agent and increase the speed to 5000 rpm for high-speed emulsification for 15 minutes. Adjust the speed to 400 rpm and add 15 g of wall material methyl methacrylate (polymerization degree of 300) dropwise to the emulsion at a rate of 5 ml / min. Heat at a rate of 2 degrees Celsius / min. When the temperature rises to 60 degrees Celsius, start slowly adding 2% acetic acid solution and continue heating. When the pH value is adjusted to 4, stop adding 2% acetic acid solution and continue heating to 80 degrees Celsius for stable polymerization for 2 hours. After cooling to room temperature, wash to obtain self-healing microcapsules. (2) Then, the polypyrrole layer was prepared by chemical method: The self-healing microcapsules containing the repair agent prepared in step (1) were immersed in a 2 mol / L pyrrole solution for 1 hour, and then quickly transferred to a 0.8 mol / L ferric chloride solution for 1 hour. After that, the obtained microcapsules were immersed in distilled water for more than 12 hours to remove excess pyrrole monomers and attached oxidants, so as to obtain electrothermal self-healing microcapsules with a polypyrrole / melamine resin double shell structure containing the repair agent. The ratio of core material to wall material of the prepared microcapsules was 1:1, and the shell thickness was reduced but the manufacturing cost was greatly reduced. Due to the increased concentration of pyrrole monomers in step (2), the pyrrole polymerized densely on the capsule surface, and the conductivity increased.

[0019] Example 5: Preparation method of polypyrrole / melamine resin double shell structure microcapsules The specific preparation method is as follows: The preparation method is divided into two steps. (1) The first step is the preparation of self-healing microcapsules: 1.5 g of styrene maleic anhydride is mixed with 400 ml of water and then 5% sodium hydroxide solution is added to adjust the pH value to 10. Stir at 400 rpm for 2 hours. Add 15 g of asphalt repair agent and increase the speed to 5000 rpm for high-speed emulsification for 15 minutes. Adjust the speed to 400 rpm and add 45 g of wall material methyl methacrylate (polymerization degree of 300) dropwise to the emulsion at a rate of 5 ml / min. Heat at a rate of 2 degrees Celsius / min. When the temperature rises to 60 degrees Celsius, start slowly adding 2% acetic acid solution and continue heating. When the pH value is adjusted to 4, stop adding 2% acetic acid solution and continue heating to 80 degrees Celsius for stable polymerization for 2 hours. After cooling to room temperature, wash to obtain self-healing microcapsules. (2) Then, the polypyrrole layer was prepared by chemical method: The self-healing microcapsules containing the repair agent prepared in step (1) were immersed in a 1 mol / L pyrrole solution for 1 hour, and then quickly transferred to a 0.8 mol / L ferric chloride solution for 1 hour. After that, the obtained microcapsules were immersed in distilled water for more than 12 hours to remove excess pyrrole monomers and attached oxidants, so as to obtain electrothermal self-healing microcapsules with a polypyrrole / melamine resin double-shell structure containing the repair agent. The ratio of the core material to the wall material of the prepared microcapsules was 1:3, the thickness of the capsule shell was greatly increased, and the stability and compression resistance of the capsule were increased.

[0020] The above description is only a preferred embodiment of the present invention. For those skilled in the art, there will be changes in the specific implementation and application scope based on the ideas of the present invention. The content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for preparing microcapsules with a polypyrrole / melamine resin double-shell structure, characterized in that, Includes the following steps: 1) Preparation of self-healing microcapsules: After mixing emulsifier and water, add pH adjuster to adjust pH value; after stirring, add asphalt repair agent core liquid and increase rotation speed for high-speed emulsification; reduce rotation speed and drop wall material into emulsion; after the wall material is dropped, raise temperature. When the temperature reaches 60 degrees Celsius, adjust pH value again with pH adjuster, continue to raise temperature to 80 degrees Celsius and stabilize. After cooling to room temperature, wash to obtain self-healing microcapsules. 2.2) Chemical method for preparing polypyrrole layer: The self-healing microcapsules prepared in step 1) are immersed in pyrrole and oxidant solutions respectively to allow pyrrole to polymerize on the surface of the microcapsules; then, they are immersed in distilled water to remove excess pyrrole monomers and oxidant to obtain electrothermal self-healing microgel with a polypyrrole / melamine resin double shell structure.

3. The method for preparing microcapsules with a polypyrrole / melamine resin double-shell structure according to claim 1, characterized in that, The emulsifier is styrene maleic anhydride, OP-10, Span-80, Tween-80, or sodium dodecyl sulfate.

4. The method for preparing microcapsules with a polypyrrole / melamine resin double-shell structure according to claim 1, characterized in that, The wall material is one of epoxy resin, melamine resin, phenolic resin, unsaturated polyester resin, and sodium alginate.

5. The method for preparing microcapsules with a polypyrrole / melamine resin double-shell structure according to claim 1, characterized in that, The core fluid is a mixture of liquid dodecane, tetradecane, hexadecane, octadecane, and paraffin.

6. The method for preparing microcapsules with a polypyrrole / melamine resin double-shell structure according to claim 1, characterized in that, The mass ratio of the emulsifier, core material, and wall material is 1:(5-10):(5-30).

7. The method for preparing microcapsules with a polypyrrole / melamine resin double-shell structure according to claim 1, characterized in that, The oxidant is one of ferric chloride, ammonium persulfate, hydrogen peroxide, and potassium iodate.

8. The method for preparing microcapsules with a polypyrrole / melamine resin double-shell structure according to claim 1, characterized in that, The concentration of pyrrole monomer is 0.8-2 mol / L, and the concentration of oxidant is 0.4-1 mol / L.

9. A microcapsule with a polypyrrole / melamine resin double-shell structure obtained by the preparation method according to any one of claims 1-7, characterized in that, The thermal decomposition temperature of the microcapsules is 300-350 degrees Celsius.

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