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CN-121988242-A - Formaldehyde-free bi-component microcapsule for self-repairing asphalt pavement and preparation method thereof

CN121988242ACN 121988242 ACN121988242 ACN 121988242ACN-121988242-A

Abstract

The invention provides a formaldehyde-free bi-component microcapsule for self-repairing an asphalt pavement and a preparation method thereof, wherein formaldehyde-free refers to the fact that formaldehyde or a formaldehyde releasing agent is not used as a reaction raw material in the preparation process, and formaldehyde-containing resin systems such as urea formaldehyde resin or melamine-urea formaldehyde resin are not adopted in the shell wall. The system comprises a first microcapsule group for encapsulating epoxy resin and a second microcapsule group for encapsulating an acid-sensitive latent amine curing agent, wherein the shell walls of the two groups are polyurethane or polyurea shell walls formed by an interfacial polymerization method under an alkaline condition, when cracks are expanded to the microcapsules in the road use process, the two groups of microcapsules are synergistically broken and release a repairing agent component, so that the epoxy resin and the latent amine curing agent are subjected to curing reaction.

Inventors

  • WANG YAJUN
  • ZHANG JINYU
  • YANG HAORU
  • ZHANG SHUO
  • LIU SHUAIQING

Assignees

  • 兰州大学

Dates

Publication Date
20260508
Application Date
20260123

Claims (12)

  1. 1. A formaldehyde-free bi-component microcapsule system for self-repairing asphalt pavement, characterized in that the microcapsule system comprises: a) A first population of microcapsules 1 encapsulating an epoxy resin 4; b) Encapsulating a second population 2 of microcapsules of an acid-sensitive latent amine curative 5; The shell walls of the first microcapsule group 1 and the second microcapsule group 2 are polyurethane shell walls or polyurea shell walls 3 prepared by adopting an interfacial polymerization method under the condition that the pH value is more than or equal to 7.0, and the mechanical properties of the first microcapsule group 1 and the second microcapsule group 2 are matched to realize cooperative rupture.
  2. 2. The microcapsule system according to claim 1, wherein the mechanical property matching is defined by performing a compression fracture test on single microcapsules by using a nanoindentation technology, wherein the number of test samples of each microcapsule group is not less than 50, and the average fracture forces of the first microcapsule group and the second microcapsule group are respectively F1 and F2, so that the following conditions are satisfied: 。
  3. 3. Microcapsule system according to claim 2, characterized in that: 。
  4. 4. The microcapsule system according to claim 1, wherein the acid-sensitive latent amine curing agent is a moisture-activated latent amine curing agent.
  5. 5. The microcapsule system of claim 4 wherein the moisture-activated latent amine curing agent is a ketimine.
  6. 6. The microcapsule system according to claim 1, wherein the microcapsules have an initial thermal decomposition temperature Td5% higher than 200 ℃, and an average particle diameter D50 of 10 μm to 200 μm.
  7. 7. A process for the preparation of a microcapsule system suitable for the self-repair of bitumen as claimed in any one of claims 1 to 6, comprising the steps of: (one) preparing a first population of microcapsules encapsulating an epoxy resin; (II) preparing a second population of microcapsules encapsulating an acid-sensitive latent amine curing agent; thirdly, mixing the first microcapsule group and the second microcapsule group according to a mass ratio of 50:10-150:60 to obtain the microcapsule system; Wherein, the microcapsule preparation in the step (I) and the step (II) adopts an interfacial polymerization method to form a polyurethane shell wall or a polyurea shell wall, and the pH value of the system in the shell forming process is maintained to be more than or equal to 7.0.
  8. 8. The method of preparing a microcapsule system for asphalt self-repair according to claim 7, wherein the step (two) comprises the steps of: (1) Preparing an aqueous phase, namely providing the aqueous phase, wherein the aqueous phase comprises an emulsion stabilizer or a protective colloid, adding one or more active hydrogen-containing monomers, and adjusting the pH value of the aqueous phase to be more than or equal to 7.0; (2) Oil phase preparation by dissolving one or more polyisocyanates in the acid-sensitive latent amine curing agent to form an oil phase; (3) Emulsifying and dispersing, namely dispersing the oil phase into the water phase under stirring or shearing to form an oil/water emulsion; (4) Reacting for 10-60 min at 20-35 ℃, then heating to 50-70 ℃ for interfacial polymerization for 3-10 h, reacting the polyisocyanate with the active hydrogen-containing monomer at an oil interface or a water interface to form a polyurea shell wall or a polyurethane shell wall and coating the core material; Wherein, in the interfacial polymerization reaction process, the pH value of the system is regulated and maintained to be more than or equal to 7.0 by adding an alkaline regulator; (5) And (3) post-treatment, namely separating, washing and drying the obtained microcapsules.
  9. 9. The method of claim 8, wherein the shell wall is a polyurea shell wall and the active hydrogen-containing monomer is one or more polyamines.
  10. 10. The method of preparing a bitumen self-healing microcapsule system according to claim 8, wherein the shell wall is a polyurethane shell wall and the active hydrogen containing monomer is one or more polyols, and microcapsules with a shell wall thickness of 2.0 μm to 3.0 μm are prepared by adjusting the mass ratio of the acid sensitive latent amine curing agent to the polyisocyanate to 80:20.
  11. 11. The self-repairing modified asphalt is characterized by comprising an asphalt matrix and the microcapsule system of claim 1, wherein the first microcapsule group and the second microcapsule group in the microcapsule system are mixed according to the mass ratio of 50:10-150:60, and the total addition amount of the microcapsule system is 1-wt% wt% of the mass of the asphalt matrix.
  12. 12. A preparation method of self-repairing modified asphalt is characterized by heating an asphalt matrix to 140 ℃ to be in a flowing state, adding a microcapsule system, and stirring for 30-60 min by 300-800 rpm to uniformly disperse microcapsules, wherein the microcapsule system is characterized in that the mass ratio of a first microcapsule group to a second microcapsule group in the microcapsule system is 50:10-150:60, and the addition amount of the microcapsule system is 1 wt% -5 wt% of the mass of the asphalt matrix.

Description

Formaldehyde-free bi-component microcapsule for self-repairing asphalt pavement and preparation method thereof Technical Field The invention relates to the technical fields of high polymer materials, microcapsule technology and road engineering materials, in particular to a formaldehyde-free bi-component microcapsule for self-repairing an asphalt pavement and a preparation method thereof, and relates to application of a microcapsule system in modified asphalt and asphalt mixture. Background The asphalt pavement is easy to generate microcracks under the actions of traffic load, temperature change and environmental aging, and the microcrack expansion can lead to macroscopic cracks and shorten the service life. The microcapsule self-repairing technology comprises the steps of embedding microcapsules containing repairing agents in an asphalt matrix, triggering cracks to be broken and releasing the repairing agents when cracks generated in the service process of the asphalt pavement are expanded to the microcapsules, and filling and curing the repairing agents in the cracks to restore the performance. In the prior art, the commonly used urea formaldehyde resin (UF) and melamine-urea formaldehyde resin (MUF) shell wall systems are usually prepared by adopting an in-situ polymerization method under an acidic condition (pH is about 2-5), and a latent amine curing agent (such as moisture activated ketimine) sensitive to acid is alkaline, and the acidic condition is easy to induce acid-base neutralization and leads to reduced activity of a core material and blocked shell formation, thereby influencing the encapsulation and repair effects. In addition, the scheme for preparing the epoxy microcapsule by the UF/MUF shell wall system possibly has the risks of free formaldehyde residue and release, and is not beneficial to environmental protection and application and popularization. Therefore, the prior art needs to provide a formaldehyde-free bi-component microcapsule system which can be prepared under alkaline conditions (pH is more than or equal to 7.0) by an interfacial polymerization method and can stably encapsulate an acid-sensitive latent amine curing agent, and a preparation method thereof, so that the self-repairing effect and long-term service reliability of an asphalt material are improved. Disclosure of Invention In order to solve the technical problems, the invention provides a formaldehyde-free bi-component microcapsule for self-repairing an asphalt pavement and a preparation method thereof. The invention aims to realize stable encapsulation of the latent amine curing agent sensitive to acid on the premise of not introducing formaldehyde and not adopting an acid catalysis in-situ polymerization method, and realize cooperative rupture and synchronous release under crack triggering through quantitative matching of mechanical properties of two types of microcapsules, thereby improving the strength recovery capability of the asphalt material after unaged and long-term aging. In the present specification, "formaldehyde-free" means that formaldehyde or a formaldehyde releasing agent is not used as a reaction raw material in the preparation process of the microcapsule shell wall, and the shell wall does not adopt formaldehyde-containing resin systems such as urea formaldehyde resin (UF) or melamine-urea formaldehyde resin (MUF). A formaldehyde-free microcapsule system for asphalt self-repair, the microcapsule system comprising: a) A first population of microcapsules encapsulating an epoxy resin; b) Encapsulating a second population of microcapsules of an acid-sensitive latent amine curing agent; The shell walls of the first microcapsule group and the second microcapsule group are polyurethane shell walls or polyurea shell walls prepared by adopting an interfacial polymerization method under the condition that the pH value is more than or equal to 7.0, and the mechanical properties of the first microcapsule group and the second microcapsule group are matched so as to realize synergistic rupture; specifically, the mechanical property matching is defined as that a nano indentation technology is adopted to carry out compression fracture test on single microcapsules, the test sample number of each microcapsule group is not less than 50, and the average fracture forces of a first microcapsule group and a second microcapsule group are respectively F1 and F2, so that the following conditions are satisfied: ; specifically, the first microcapsule population and the second microcapsule population also need to satisfy: ; specifically, the acid-sensitive latent amine curing agent is a moisture-activated latent amine curing agent. Specifically, the moisture-activated latent amine curing agent is a ketimine. Specifically, the microcapsules have an initial thermal decomposition temperature Td5% higher than 200 ℃, and an average particle diameter D50 of 10 μm to 200 μm. A preparation method of an asphalt self-repairing microcapsul