CN107970868A - Externally-repaired and internally-fixed polyurea-based double-wall self-repairing microcapsule and preparation method thereof - Google Patents

Abstract

The invention provides a double-walled microcapsule system using an aliphatic isocyanate-amino-terminated polyether polymer as a repair agent and an amine-based chain extender as a curing agent. Externally repaired and internally solid polyurea-based double-walled self-healing microcapsules, including an inner capsule wall and an outer capsule wall; the inner capsule wall is coated with an amine-based chain extender emulsion, and the outer capsule wall is coated with a pre- Polymer emulsion; both the inner layer capsule wall and the outer layer capsule wall are polyurea prepared by interfacial polymerization, and the inner layer capsule wall polyurea is composed of the amine-based chain extender emulsion coated by the inner layer capsule wall and the outer layer The capsule wall-coated prepolymer emulsion is obtained by reacting; the outer capsule wall polyurea is obtained by reacting the amine-based chain extender emulsion and the outer capsule wall-coated prepolymer emulsion. The repairing agent and the curing agent are stored in the inner capsule core and the outer capsule core respectively, which not only solves the problem of low contact rate between the repairing agent and the curing agent, but also reacts quickly between the repairing agent and the curing agent, thus realizing crack cracking. The rapid repair has broad application prospects.

Description

Externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules and preparation method thereof

technical field

The invention belongs to the field of organic composite materials, and relates to a self-repairing material, in particular to a polyurea-based double-wall self-repairing microcapsule with external repair and internal solidification and a preparation method thereof, which are applied to building disaster prevention and reduction, coating protection and repair, etc. engineering field.

Background technique

With the continuous development of society, the construction industry has also developed rapidly, and various high-rise buildings, bridges and roads have been dug up one after another. Concrete is widely used in the field of construction because of its wide range of sources, high compressive strength, easy construction and high durability. However, concrete structures are highly prone to cracks during their service life. With the change of load and the passage of time, the cracks will gradually expand into cracks, and even extend to the surface, causing the concrete material to crack. After forming through cracks, concrete is vulnerable to erosion and damage from the external environment and various harmful factors, such as steel bar corrosion, carbonation, chloride ion corrosion and sulfate corrosion, etc., which will eventually lead to cracking and damage of concrete materials, seriously affecting the quality of concrete materials. Durability, and may even cause sudden building damage and irreparable human and financial losses. Similarly, coatings, as the most commonly used protective materials, have been widely used in infrastructure, aerospace, automobile manufacturing and other fields. However, the coating is easily affected by external factors during the service process, causing changes in its internal chemical structure, causing micro-cracks of different sizes and local damage, and greatly reducing the mechanical properties of the coating. Pooling eventually leads to flaking of the coating making it ineffective to protect the substrate. Since these microcrack damages are difficult to detect with the naked eye, conventional repair methods are often difficult to achieve the desired effect. Therefore, the influence of microscopic cracks on the service performance of materials has received more and more attention and attention. Traditional repair methods mainly include surface repair method, local repair method and grouting method. These methods repair surface cracks and local cracks, and cannot repair micro-cracks inside the matrix. The erosion of the environment, and it is difficult to effectively control the regeneration of cracks.

In 2001, White et al. published an article on polymer self-healing technology in the journal Natural Science for the first time, which made self-healing technology widely used. In this technical background, researchers began to realize the self-repair of concrete structures in active mode through the principle of bionic self-repair. When cracks appear in the concrete structure, under the action of micro-cracks, the additives are forced to break by capillary force to release the repair agent and enter the cracks, repair and prevent the further growth of cracks, thus forming an active repair network system inside the concrete. Microcapsule self-repair technology, as an important part of self-repair concrete material structure, has great application prospects in many aspects of civil engineering construction and repair in the future. This method does not require additional manual monitoring and high costs for surface maintenance, prolongs the life of the concrete structure and saves part of the operating costs of building materials.

At present, the microcapsule self-repair system mainly includes single-wall microcapsule repair system, single-wall double-microcapsule repair system and double-wall microcapsule system. Early research focused on single-wall microcapsule systems, which encapsulated repair agents in microcapsules and contained catalysts in the repaired matrix. The single-wall microcapsule system mainly includes DCPD-Grubbs system, urea-formaldehyde resin (UF) system, inner-coated dicyclopentadiene (DCPD) system and epoxy resin curing agent system. However, the above system has the following problems: (1) The microcapsules have poor thermochemical stability; (2) The reaction curing film forming speed is slow and cannot effectively fill the cracks; (3) The catalyst is expensive and easy to deactivate; (4) Application of self-healing system The scope is narrow and can only be limited to certain substrates. Invention patent ZL200710044358.4 discloses "polyurea microcapsules and its preparation method". The invention provides a polyurea microcapsule and a preparation method thereof. The preparation method comprises the following steps: (1) adding an organic phase containing diphenylmethane diisocyanate to an aqueous phase containing a surfactant, stirring and emulsifying to obtain emulsion A (2) Diethylenetriamine is added to an aqueous solution containing a surfactant to obtain a continuous phase solution B; (3) The continuous phase solution B is added to emulsion A to initiate interfacial polymerization on the oil-water interface to obtain polyurea microcapsules containing suspension. The polyurea wall material of the microcapsule system in this invention is generated by the interfacial polymerization reaction between isocyanate and amino compound, which solves the problem of slow curing and film-forming speed; however, what this system obtains is a linear polyurea capsule wall structure. The performance of the wall material is not good enough to protect the core material. Secondly, the invention uses an oil-in-water emulsion in the preparation process of the isocyanate emulsion, which leads to the premature failure of the isocyanate due to its sensitivity to water, which is not conducive to the subsequent reaction to form polyurea microcapsules. In addition, the polyurea microcapsule has a single-wall structure, and there are still problems such as low repair efficiency of the single-wall microcapsule system.

In the subsequent research, a single-wall double microcapsule system appeared. This system includes two kinds of microcapsules, one is coated with repairing agent, and the other is coated with curing agent. The single-wall double microcapsule system solves the following problems of the single-wall microcapsule system to a certain extent: (1) It is necessary to add a catalyst to the substrate to achieve self-repair; (2) The repair effect caused by the premature deactivation of the catalyst is not good. Good; (3) The production cost is too high. However, there are still problems in the single-wall double microcapsule system that the repairing agent and the curing agent cannot be in contact at the same time, cannot be repaired quickly, and have a complex response mechanism to cracks. Under these technical backgrounds, some researchers reported a double-walled microcapsule system. Compared with the single-wall microcapsule system, the double-wall coated microcapsule system has better stability, thus reducing the probability of inactivation of the restoration agent and the curing agent; at the same time, it also greatly increases the contact probability of the restoration agent and the catalyst, Avoid the adverse effect of adding too much repair agent and catalyst on the concrete performance.

Invention patent ZL201110146711.6 discloses "a preparation method of reinforced epoxy resin/curing agent double-walled microcapsules". This application provides a method for preparing a double-walled self-repairing microcapsule in which epoxy resin or epoxy resin and carbon nanotubes are combined as an inner capsule core repair agent, and a curing agent is used as an outer capsule core. However, the repair agent epoxy resin in the double-wall microcapsule system prepared by this method can only exert a good repair effect under the condition of heating, and cannot achieve rapid and effective repair at room temperature; in addition, the polyurea formaldehyde capsule wall it uses The production process of the method is relatively complicated, which increases the cost and difficulty of practical application.

Invention patent ZL200510014698.3 discloses "Preparation method of polyurea-urea-formaldehyde resin double-layer microcapsules". The invention adopts the interfacial polymerization method, using glutaraldehyde-modified polyamine compounds and diisocyanate compounds as monomers for interfacial polymerization to prepare polyurea microcapsules; adopts the in-situ polymerization method, using the polyurea microcapsules as the core, and Urea and formaldehyde are monomers, and form a urea-formaldehyde resin shell under acidic conditions to obtain polyurea-urea-formaldehyde double-layer microcapsules. In the invention, two different systems of interfacial polymerization and in-situ polymerization were respectively selected in the two preparation processes, and the in-situ polymerization method has certain requirements on the solubility of the core material and the generated capsule wall material, which not only limits the reagents. types, and make the process more complicated and increase the difficulty of operation. Secondly, the invention uses an oil-in-water emulsion in the preparation process of the isocyanate emulsion, which leads to the premature failure of the isocyanate due to its sensitivity to water, which is not conducive to the subsequent reaction to form polyurea microcapsules. In addition, this invention uses toluene diisocyanate with high toxicity and volatility, which is very easy to cause great pollution to the environment; Excessive dependence on different pH values further increases operational complexity.

Contents of the invention

Aiming at the technical problems existing in the existing self-repairing double-walled microcapsule system, the present invention provides a double-walled microcapsule with aliphatic isocyanate-amino-terminated polyether polymer as a repairing agent and an amine-based chain extender as a curing agent. Capsule system. The repairing agent and the curing agent are stored in the inner capsule core and the outer capsule core respectively, which not only solves the problem of low contact rate between the repairing agent and the curing agent, but also reacts quickly between the repairing agent and the curing agent, thus realizing crack cracking. The rapid repair has broad application prospects.

Technical scheme of the present invention:

Externally repaired and internally solid polyurea-based double-walled self-healing microcapsules, including an inner capsule wall and an outer capsule wall; the inner capsule wall is coated with an amine-based chain extender emulsion, and the outer capsule wall is coated with a pre- Polymer emulsion; both the inner layer capsule wall and the outer layer capsule wall are polyurea prepared by interfacial polymerization, and the inner layer capsule wall polyurea is composed of the amine-based chain extender emulsion coated by the inner layer capsule wall and the outer layer The capsule wall-coated prepolymer emulsion is obtained by reacting; the outer capsule wall polyurea is obtained by reacting the amine-based chain extender emulsion and the outer capsule wall-coated prepolymer emulsion. The preparation method of externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules comprises the following steps:

(1) Preparation of prepolymer emulsion: mix an appropriate amount of aliphatic isocyanate repair agent, amino-terminated polyether, emulsifier and solvent under high-speed stirring to prepare a prepolymer emulsion; specifically: aliphatic isocyanate repair Agent and amino-terminated polyether are mixed evenly according to the mass ratio of 1:1-1:5 to obtain a prepolymer; stir evenly at a speed of 2000-3500rmp, add emulsifier and solvent, and at a speed of 1500-3500rpm, 60 ℃-70℃ for 2-3h to obtain a prepolymer emulsion; the amount of the emulsifier is 5%-10% of the mass of the prepolymer, and the mass ratio of the emulsifier to the solvent is 1:150-1:160 .

Wherein, the NCO group content of the aliphatic isocyanate repairing agent is 3%-12%, and the average functionality is 1.5 to 5.0; the aliphatic isocyanate repairing agent is isophorone diisocyanate (IPDI) , hexamethylene diisocyanate (HDI), 1,4-cyclohexane diisocyanate, cyclohexylmethane-4,4-diisocyanate, allophanate of 1,6-hexamethylene diisocyanate or HDI Trimer system; the amino-terminated polyether is polyetheramine D400, polyetheramine D230, polyetheramine D2000, 3,5-dimethylthiotoluene-2,6-diamine, 3,5-diethyl 2,4-diamine, 3,5-dimethylthiotoluene-2,4-diamine, 1,4-butanediamine or 1,6-hexanediamine.

(2) Preparation of amine-based chain extender emulsion: mix amine-based chain extender, solvent and emulsifier evenly under high-speed stirring to prepare amine-based chain extender emulsion; specifically: take an appropriate amount of emulsifier and solvent, Stir at a rotational speed of -2500rmp until uniformly mixed; the mass ratio of the emulsifier to solvent is 1:40-1:50; add an amine-based chain extender, and stir at a rotational speed of 1000-2500rmp until uniformly mixed to obtain an amine Based chain extender emulsion; the amount of the emulsifier is 10%-20% of the mass of the amine based chain extender.

Wherein, the amine-based chain extender is diethyltoluenediamine, dimethylthiotoluenediamine, N,N'-dialkylmethyldiphenylamine, cyclohexanediamine, MDH chloride, ethyl Diamine, 1,3-diaminopropane, 1,4-diaminobutane, diethylenetriamine, pentaethylenehexamine, hexaethylenediamine, tetraethylenepentamine, pentaethylene Ethylhexamine, Polyetheramine D400, Polyetheramine D230, Ethylenediamine or 3,3'-4,4'-diamino-diphenylmethane MOCA.

(3) Preparation of polyurea-encapsulated double-walled microcapsules: Add the prepolymer emulsion prepared in step (1) dropwise to the amine-based chain extender emulsion prepared in step (2) to synthesize the inner wall material of the microcapsules to form a single Wall microcapsule emulsion; then add emulsifier, solvent and excess prepolymer emulsion to the above emulsion, drop in amine-based chain extender emulsion after emulsification, synthesize the outer wall material of microcapsules, and form double-wall microcapsule emulsion. Specifically:

①Mix the amine-based chain extender emulsion and the prepolymer emulsion at a mass ratio of 1.5:1-3:1, and heat it at 60°C-70°C for 2-3 hours at a speed of 800-2500rmp to form a single-walled microstructure. Capsule emulsion; the principle is: the surface of the amine-based chain extender emulsion droplet adsorbs the prepolymer emulsion droplet, and through the polymerization reaction of the prepolymer and the amine-based chain extender, the synthesis of the inner wall material of the microcapsule is completed to form a single-walled microcapsule. Capsule lotion. Change the traditional oil-in-water emulsion to avoid premature reaction between isocyanate and water in the emulsion and cause failure.

2. Add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsifier is in the single-wall microcapsule- The mass fraction in the prepolymer composite emulsified droplet system is 4%-6%; the mass ratio of the emulsifier and the solvent is 1:140-1:160 ; after the emulsification is completed, drop into the amine-based chain extender emulsion, so The mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:1.2-1:3; at a speed of 1000-3500rmp, heat at 60°C-70°C for 2-3h to form a double-walled microcapsule emulsion; principle The method is: the emulsion droplet of the amine-based chain extender is adsorbed on the surface of the prepolymer emulsion droplet, and the synthesis of the outer wall material of the microcapsule is completed through the polymerization reaction of the prepolymer and the amine-based chain extender.

③ Centrifuge, dry, dry and wash the double-walled microcapsule emulsion to obtain polyurea-encapsulated polyurea-based double-walled self-healing microcapsules with a particle size distribution of 10 μm-200 μm. Step 2. When preparing the double-walled microcapsule emulsion, 1-5 drops of defoamer can also be added while adding the chain extender emulsion; the defoamer is n-butanol, 1,4-butanediol, polyoxypropylene poly Oxyethylene glyceryl ether or dimethicone. The prepolymer emulsion and amine-based chain extender emulsion used in this application not only serve as repairing agent and curing agent respectively, but also react with each other to form inner and outer capsule walls, with high utilization rate, thus greatly simplifying the process flow . Under the action of the crack tip, the prepolymer and the amine-based chain extender can quickly undergo a curing reaction, which not only simplifies the interaction mechanism between the repairing agent and the curing agent, but also realizes the rapid repair of cracks and improves the repairing efficiency.

The emulsifier described in the above steps is sodium dodecylbenzenesulfonate, OP-10, stearyl polyoxyethylene ether, gum arabic, polyoxyethylene ether, fatty ammonia polyoxyethylene ether or polyvinyl alcohol ; The solvent is ethyl acetate, acetone, cyclohexane, cyclopentane, toluene or chlorobenzene.

Using the self-repairing system of the polyurea-based double-walled microcapsules, the mass fraction of the polyurea-based double-walled microcapsules in the self-repairing system is 5%-18%; the self-repairing system is self-repairing concrete Or self-healing coatings. Beneficial effects of the present invention:

(1) By adopting the double-walled microcapsule structure of the present invention, the repairing agent and the chain extender can be stored inside the microcapsules in liquid form before microcracks appear on the base material, which effectively solves the problem of poor thermochemical stability of other microcapsules , easy deactivation and other issues;

(2) The aliphatic isocyanate-amino-terminated polyether polymer used in the present invention can quickly undergo a curing reaction when encountering an amine-based chain extender, which solves the problem that the curing film-forming rate is slow and cannot effectively prevent cracks from expanding;

(3) The capsule wall adopted in the present invention is a polyurea shell, which has excellent physical and chemical properties, and its shell strength can realize effective wrapping of the capsule core material without significantly affecting the concrete strength. While prolonging the service life of concrete;

(4) The double-walled microcapsule structure of the present invention does not need to be heated in application, and can respond to cracks at room temperature to realize self-repair of concrete.

Description of drawings

Accompanying drawing 1 is the structural representation of double-walled microcapsule.

Detailed ways

Below in conjunction with embodiment the present invention will be further described.

Example 1:

Externally repaired and internally solid polyurea-based double-walled self-healing microcapsules, including an inner capsule wall and an outer capsule wall; the inner capsule wall is coated with an amine-based chain extender emulsion, and the outer capsule wall is coated with a pre- Polymer emulsion; both the inner capsule wall and the outer capsule wall are polyurea prepared by interfacial polymerization, and the polyurea is coated with the amine-based chain extender emulsion coated by the inner capsule wall and the outer capsule wall The prepolymer emulsion reaction is obtained.

The preparation method of externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules comprises the following steps:

(1) Preparation of prepolymer emulsion: aliphatic isocyanate repair agent isophorone diisocyanate (IPDI) and amino-terminated polyether polyetheramine D400 are mixed uniformly according to a mass ratio of 1:1 to obtain a prepolymer; Stir evenly at a rotating speed of 2200rpm, add an emulsifier and a solvent, and heat at 65°C for 2-3h at a rotating speed of 2000rpm to obtain a prepolymer emulsion; the amount of the emulsifier is 10% of the mass of the prepolymer, and the The mass ratio of emulsifier and solvent is 1:150.

(2) Preparation of amine-based chain extender emulsion: take an appropriate amount of emulsifier and solvent, stir at a speed of 1200rmp until mixed evenly; the mass ratio of the emulsifier to solvent is 1:44; add amine-based chain extender two Ethyltoluenediamine was stirred at a rotational speed of 2500rmp until uniformly mixed to prepare an emulsion of an amine-based chain extender; the amount of the emulsifier was 18% of the mass of the amine-based chain extender.

(3) Preparation of polyurea-encapsulated double-walled microcapsules: ①Mix the amine-based chain extender emulsion and the prepolymer emulsion in a mass ratio of 3:1, and heat it at 62°C for 2-3 hours at a speed of 800rmp. Form a single-wall microcapsule emulsion; the principle is: the surface of the amine-based chain extender emulsion droplet adsorbs the prepolymer emulsion droplet, and through the polymerization reaction of the prepolymer and the amine-based chain extender, the synthesis of the inner wall material of the microcapsule is completed. A single-walled microcapsule emulsion is formed. Change the traditional oil-in-water emulsion to avoid premature reaction between isocyanate and water in the emulsion and cause failure.

2. Add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsifier is in the single-wall microcapsule- The mass fraction in the prepolymer composite emulsified droplet system is 5%; The mass ratio of described emulsifier and solvent is 1:160 ; After emulsification is completed, drip into amine-based chain extender emulsion and 1-5 defoamer, The defoamer is 1,4-butanediol, and the mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:3; at a speed of 1000rmp, heat at 62°C for 2-3h to form a double-walled Microcapsule emulsion; the principle is: the surface of the prepolymer emulsion droplet adsorbs the amine-based chain extender emulsion droplet, and the synthesis of the outer wall material of the microcapsule is completed through the polymerization reaction of the prepolymer and the amine-based chain extender.

③ The double-wall microcapsule emulsion is centrifuged, dried, dried and washed to obtain polyurea-encapsulated polyurea-based double-wall self-healing microcapsules.

The emulsifier described in the above steps is sodium dodecylbenzenesulfonate; the solvent is ethyl acetate.

The prepolymer emulsion and amine-based chain extender emulsion used in this application not only serve as repairing agent and curing agent respectively, but also react with each other to form inner and outer capsule walls, with high utilization rate, thus greatly simplifying the process flow . Under the action of the crack tip, the prepolymer and the amine-based chain extender can quickly undergo a curing reaction, which not only simplifies the interaction mechanism between the repairing agent and the curing agent, but also realizes the rapid repair of cracks and improves the repairing efficiency.

The self-repairing concrete adopts the polyurea-based double-wall microcapsules, and the mass fraction of the polyurea-based double-wall microcapsules in the self-repairing concrete is 8%.

Example 2:

Different from Example 1,

The preparation method of externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules comprises the following steps:

(1) Preparation of prepolymer emulsion: aliphatic isocyanate repair agent 1,4-cyclohexane diisocyanate and amino-terminated polyether 3,5-dimethylthiotoluene-2,6-diamine according to 1: Mix evenly with a mass ratio of 2 to obtain a prepolymer; stir evenly at a rotating speed of 2000rmp, add an emulsifier and a solvent, and heat at 68°C for 2-3h at a rotating speed of 2300rpm to obtain a prepolymer emulsion; the emulsifier The amount is 9% of the mass of the prepolymer, and the mass ratio of the emulsifier to the solvent is 1:154.

(2) Preparation of amine-based chain extender emulsion: take an appropriate amount of emulsifier and solvent, stir at a speed of 1000rmp until mixed evenly; the mass ratio of the emulsifier and solvent is 1:46; add the amine-based chain extender ring Hexanediamine was stirred at a rotational speed of 2000rmp until uniformly mixed to prepare an emulsion of an amine-based chain extender; the amount of the emulsifier was 20% of the mass of the amine-based chain extender.

(3) Preparation of polyurea-encapsulated double-walled microcapsules: ①Mix the amine-based chain extender emulsion and the prepolymer emulsion at a mass ratio of 1.5:1, and heat it at 65°C for 2-3 hours at a speed of 1000rmp. Formation of single-walled microcapsule emulsions;

2. Add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsifier is in the single-wall microcapsule- The mass fraction in the prepolymer composite emulsified droplet system is 5.5%; the mass ratio of the emulsifier and solvent is 1:155 ; after the emulsification is completed, drip into the amine-based chain extender emulsion and 1-5 drops of defoamer; The defoamer is n-butanol, and the mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:1.2; at a rotating speed of 3500rmp, heat at 65°C for 2-3h to form a double-walled microcapsule emulsion .

③ The double-wall microcapsule emulsion is centrifuged, dried, dried and washed to obtain polyurea-encapsulated polyurea-based double-wall self-healing microcapsules.

The emulsifier described in the above steps is stearyl polyoxyethylene ether; the solvent is acetone.

The self-healing coating of polyurea-based double-wall microcapsules is adopted, and the mass fraction of the polyurea-based double-wall microcapsules in the self-healing epoxy coating is 10%.

Example 3:

Different from Example 1,

The preparation method of externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules comprises the following steps:

(1) Preparation of prepolymer emulsion: the allophanate of the aliphatic isocyanate repair agent 1,6-hexamethylene diisocyanate and the amino-terminated polyether 1,4 butanediamine according to the mass of 1:3 Mix evenly to obtain a prepolymer; stir evenly at a rotating speed of 3000rmp, add an emulsifier and a solvent, and heat at 70°C for 2-3h at a rotating speed of 3000rpm to obtain a prepolymer emulsion; the amount of the emulsifier is 6% of the polymer mass, the mass ratio of the emulsifier to the solvent is 1:158.

(2) Preparation of amine-based chain extender emulsion: take an appropriate amount of emulsifier and solvent, stir at a speed of 1600rmp until mixed evenly; the mass ratio of the emulsifier to solvent is 1:48; add amine-based chain extender B Stir the diamine at a rotational speed of 1000rmp until it is evenly mixed to prepare an emulsion of an amine-based chain extender; the amount of the emulsifier is 10% of the mass of the amine-based chain extender.

(3) Preparation of polyurea-encapsulated double-walled microcapsules: ①Mix the amine-based chain extender emulsion and the prepolymer emulsion at a mass ratio of 1.8:1, and heat at 68°C for 2-3 hours at a speed of 2500rmp. Form a single-wall microcapsule emulsion; 2. add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsification The massfraction of agent in the single-wall microcapsule-prepolymer composite emulsified droplet system is 4.5%; The mass ratio of described emulsifier and solvent is 1:150 ; After emulsification is finished, drop into amine-based chain extender emulsion, so The mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:2; at a rotation speed of 1500rmp, the temperature is kept at 68°C for 2-3h to form a double-walled microcapsule emulsion.

③ The double-wall microcapsule emulsion is centrifuged, dried, dried and washed to obtain polyurea-encapsulated polyurea-based double-wall self-healing microcapsules.

The emulsifier described in the above steps is polyoxyethylene ether; the solvent is cyclohexane.

The self-repairing concrete adopts the polyurea-based double-wall microcapsules, and the mass fraction of the polyurea-based double-wall microcapsules in the self-repairing concrete is 12%.

Example 4:

Different from Example 1,

The preparation method of externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules comprises the following steps:

(1) Preparation of prepolymer emulsion: the aliphatic isocyanate repair agent hexamethylene diisocyanate (HDI) and amino-terminated polyether polyetheramine D230 are uniformly mixed in a mass ratio of 1:4 to obtain a prepolymer; Stir evenly at a rotating speed of 2800rpm, add an emulsifier and a solvent, and keep warm at 60°C for 2-3h at a rotating speed of 3500rpm to obtain a prepolymer emulsion; the amount of the emulsifier is 7% of the mass of the prepolymer, and the The mass ratio of emulsifier to solvent is 1:156.

(2) Preparation of amine-based chain extender emulsion: take an appropriate amount of emulsifier and solvent, and stir at a speed of 1800rmp until uniformly mixed; the mass ratio of the emulsifier to solvent is 1:50; add amine-based chain extender 1 , 4-diaminobutane, stirred at a rotating speed of 1500rmp until uniformly mixed to prepare an emulsion of an amine-based chain extender; the amount of the emulsifier is 12% of the mass of the amine-based chain extender.

(3) Preparation of polyurea-encapsulated double-walled microcapsules: ①Mix the amine-based chain extender emulsion and the prepolymer emulsion at a mass ratio of 2.8:1, and heat it at 70°C for 2-3 hours at a speed of 1500rmp. Form a single-wall microcapsule emulsion; 2. add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsification The massfraction of agent in the single-wall microcapsule-prepolymer composite emulsified droplet system is 4%; The mass ratio of described emulsifier and solvent is 1:140 ; After emulsification is finished, drop into amine-based chain extender emulsion and add 1-5 drops of defoamer; the defoamer is polyoxypropylene polyoxyethylene glyceryl ether, and the mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:2.8; at a rotating speed of 2200rmp, Incubate at 70°C for 2-3 hours to form a double-walled microcapsule emulsion.

③ The double-wall microcapsule emulsion is centrifuged, dried, dried and washed to obtain polyurea-encapsulated polyurea-based double-wall self-healing microcapsules.

The emulsifier described in the above steps is polyoxyethylene ether; the solvent is cyclopentane.

The self-healing coating of polyurea-based double-wall microcapsules is adopted, and the mass fraction of the polyurea-based double-wall microcapsules in the self-healing epoxy coating is 15%.

Example 5:

Different from Example 1,

The preparation method of externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules comprises the following steps:

(1) Preparation of prepolymer emulsion: aliphatic isocyanate repair agent cyclohexylmethane-4,4-diisocyanate and amino-terminated polyether 3,5-diethyltoluene-2,4-diamine according to 1: Mix evenly with a mass ratio of 5 to obtain a prepolymer; stir evenly at a rotating speed of 2600rmp, add an emulsifier and a solvent, and heat at 62°C for 2-3h at a rotating speed of 1500rpm to obtain a prepolymer emulsion; the emulsifier The amount is 8% of the mass of the prepolymer, and the mass ratio of the emulsifier to the solvent is 1:152.

(2) Preparation of amine-based chain extender emulsion: take an appropriate amount of emulsifier and solvent, stir at a speed of 2000rmp until mixed evenly; the mass ratio of the emulsifier to solvent is 1:40; add amine-based chain extender IV Ethylene pentamine was stirred at a rotational speed of 1400rmp until uniformly mixed to obtain an emulsion of an amine-based chain extender; the amount of the emulsifier was 14% of the mass of the amine-based chain extender.

(3) Preparation of polyurea-encapsulated double-walled microcapsules: ①Mix the amine-based chain extender emulsion and the prepolymer emulsion at a mass ratio of 2.5:1, and heat it at 60°C for 2-3 hours at a speed of 1800rmp. Form a single-wall microcapsule emulsion; 2. add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsification The massfraction of agent in the single-wall microcapsule-prepolymer composite emulsified droplet system is 6%; The mass ratio of described emulsifier and solvent is 1:145 ; After emulsification is finished, drop into amine-based chain extender emulsion, so The mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:1.5; at a rotational speed of 3000rmp, the temperature is kept at 60°C for 2-3h to form a double-walled microcapsule emulsion.

③ The double-wall microcapsule emulsion is centrifuged, dried, dried and washed to obtain polyurea-encapsulated polyurea-based double-wall self-healing microcapsules.

The emulsifier described in the above steps is fatty ammonia polyoxyethylene ether; the solvent is toluene.

The self-healing coating of polyurea-based double-wall microcapsules is adopted, and the mass fraction of the polyurea-based double-wall microcapsules in the self-healing epoxy coating is 18%.

Embodiment 6:

Different from Example 1,

The preparation method of externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules comprises the following steps:

(1) Preparation of prepolymer emulsion: mix the aliphatic isocyanate repair agent HDI trimer system with amino-terminated polyether 1,6 hexamethylenediamine according to the mass ratio of 1:3.5 to obtain the prepolymer; at 3500rmp Stir evenly under the rotating speed of 2600rpm, add emulsifier and solvent, under the rotating speed of 2600rpm, 65 ℃ of insulations 2-3h, obtain prepolymer emulsion; The amount of described emulsifier is 5% of prepolymer mass, and described emulsifier The mass ratio of solvent and solvent is 1:160.

(2) Preparation of amine-based chain extender emulsion: take an appropriate amount of emulsifier and solvent, stir at a rotating speed of 2500rmp until uniformly mixed; the mass ratio of the emulsifier to solvent is 1:42; add the amine-based chain extender poly Etheramine D400 was stirred at a rotational speed of 1200rmp until uniformly mixed to prepare an emulsion of an amine-based chain extender; the amount of the emulsifier was 16% of the mass of the amine-based chain extender.

(3) Preparation of polyurea-encapsulated double-walled microcapsules: ①Mix the amine-based chain extender emulsion and the prepolymer emulsion at a mass ratio of 2:1, and heat it at 65°C for 2-3 hours at a speed of 2000rmp. Form a single-wall microcapsule emulsion; 2. add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsification The massfraction of agent in the single-wall microcapsule-prepolymer composite emulsified droplet system is 5%; The mass ratio of described emulsifier and solvent is 1:155 ; After emulsification is finished, drop into amine-based chain extender emulsion and 1 -5 drops of defoamer; the defoamer is polydimethylsiloxane, and the mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:2.4; at a speed of 1200rmp, 65°C Insulate for 2-3 hours to form a double-wall microcapsule emulsion; ③ centrifuge, dry, dry and wash the double-wall microcapsule emulsion to obtain a polyurea-encapsulated polyurea-based double-wall self-healing microcapsule capsule.

The emulsifier described in the above steps is polyvinyl alcohol; the solvent is chlorobenzene.

The self-repairing concrete adopts the polyurea-based double-wall microcapsules, and the mass fraction of the polyurea-based double-wall microcapsules in the self-repairing concrete is 6.5%.

Table 1 Example 1-6 prepares microscopic morphology characterization of microcapsules

Table 2 embodiment 1-6 prepares the mechanical property test of microcapsule

As can be seen from the characterization results in Table 1 and Table 2, the particle diameter of the microcapsules prepared in Examples 1-6 is 10-200 μm, the tensile strength is 10.47-13.55MPa, and the elongation at break is 242%-330%. Its hardness (A) is 40-52. Compared with the microcapsules in the prior art, the present invention can realize the control of the particle size of the microcapsules through different preparation conditions to meet the needs of different substrates; at the same time, the prepared double-walled microcapsules show better Excellent mechanical properties, effectively avoiding the failure of the microcapsules during the stirring process of adding the base material, so that the microcapsules can stably play a repairing role.

The microcapsules prepared in Examples 1, 3 and 6 were mixed into cement to prepare self-healing concrete. After curing for 28 days, take a group (each group containing 3 test blocks) of self-repairing concrete to test the initial compressive strength; take another group (each group containing 3 test blocks) to lightly compress the self-repairing concrete with a pressure testing machine Cracks were formed inside the concrete, and after half a month, the compressive strength of this group of self-healing concrete was tested. The microcapsules prepared in Examples 2, 4 and 5 were incorporated into the epoxy coating to prepare the self-healing epoxy coating. Take one group (each group contains 3 coatings) of self-healing coatings to test the initial tensile strength, and take another group (each group contains 3 coatings) to stretch the self-healing epoxy coatings with a tensile testing machine Cracks were generated inside, and half a month later, the tensile strength of this group of self-repairing epoxy coatings was tested, and the data shown in Table 3 were obtained.

Table 3 Example 1-6 prepares the mensuration of microcapsule self-healing system repair intensity

In summary, the external repair and internal solid polyurea-based double-wall self-healing microcapsules prepared by the interfacial polymerization method have good microscopic morphology, and the particle size is mainly distributed between 10-200 μm; mechanical tests show that the cured polyurea-based self-healing microcapsules Urea microcapsules are elastic materials (elongation at break 242-330%) with certain strength (tensile strength 10.47-13.91 MPa) and hardness (Shore A40-52). The experiment of pre-compressing cracks by mixing polyurea microcapsules into concrete and epoxy coatings shows that polyurea microcapsules have a certain repairing effect on cracks, and the compressive strength of concrete after repairing increases by 6.71%. The increase rate of tensile strength of epoxy coating is 16.09%.

Claims (10)

1. Externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules, including an inner capsule wall and an outer capsule wall; it is characterized in that: the inner capsule wall is coated with an amine-based chain extender emulsion, and the outer capsule wall is coated with an amine-based chain extender emulsion. The layer capsule wall is coated with prepolymer emulsion; the inner layer capsule wall and the outer layer capsule wall are both polyurea prepared by interfacial polymerization, and the inner layer capsule wall polyurea is made of amine-based expanded polyurea coated with the inner layer capsule wall. The chain agent emulsion is obtained by reacting the prepolymer emulsion coated with the outer capsule wall, and the polyurea of the outer capsule wall is obtained by reacting the amine-based chain extender emulsion with the prepolymer emulsion coated with the outer capsule wall 2. The preparation method of externally repaired and internally solid polyurea-based double-wall self-repairing microcapsules is characterized in that: it comprises the following steps: (1) preparing a prepolymer emulsion: mixing an appropriate amount of aliphatic isocyanate repairing agent, amino-terminated polyether , emulsifier and solvent are mixed uniformly under high-speed stirring to prepare prepolymer emulsion; (2) preparation of amine-based chain extender emulsion: the amine-based chain extender, solvent and emulsifier are mixed uniformly under high-speed stirring to prepare amine-based Chain extender emulsion; (3) preparation of polyurea-encapsulated double-walled microcapsules: adding the prepolymer emulsion prepared in step (1) dropwise to the amine-based chain extender emulsion prepared in step (2) to synthesize the microcapsule inner wall Wall material to form a single-wall microcapsule emulsion; then add emulsifier, solvent and excess prepolymer emulsion to the above emulsion, after the emulsification is completed, drop the amine-based chain extender emulsion to synthesize the outer wall material of the microcapsule to form a double-wall microcapsule emulsion. 3. The preparation method of external repair and internal solidification type polyurea-based double-wall self-repairing microcapsules according to claim 2, characterized in that: the preparation of polyurea-encapsulated double-wall microcapsules described in step (3) is specifically: ①Mix the amine-based chain extender emulsion and the prepolymer emulsion at a mass ratio of 1.5:1-3:1, and heat it at 60°C-70°C for 2-3 hours at a speed of 800-2500rpm to form a single-walled microstructure. Capsule emulsion; 2. add an appropriate amount of emulsifier, solvent and excessive prepolymer emulsion to the system obtained in step 1. to emulsify to form a single-wall microcapsule-prepolymer composite emulsified droplet system; the emulsifier is in the single-wall The mass fraction in the microcapsule-prepolymer composite emulsified droplet system is 4%-6%; the mass ratio of the emulsifier to the solvent is 1:140-1:160; after the emulsification is completed, drop the amine-based chain extender Emulsion, the mass ratio of the amine-based chain extender emulsion to the prepolymer emulsion is 1:1.2-1:3; At a speed of 1000-3500rpm, heat at 60°C-70°C for 2-3h to form a double-walled microcapsule emulsion; ③ Centrifuge the double-walled microcapsule emulsion to obtain polyurea-encapsulated externally repaired internally solid polyurea Based on double-walled self-healing microcapsules. 4. The preparation method of the externally repaired and internally solidified polyurea-based double-walled self-repairing microcapsules according to claim 2, characterized in that: the preparation of the prepolymer emulsion described in step (1) is specifically: aliphatic The isocyanate repair agent and the amino-terminated polyether are mixed evenly according to the mass ratio of 1:1-1:5 to obtain a prepolymer; stir evenly at a speed of 2000-3500rpm, add an emulsifier and a solvent, and at 60°C-70°C for 2-3h to obtain a prepolymer emulsion; the amount of the emulsifier is 5%-10% of the mass of the prepolymer, and the mass ratio of the emulsifier to the solvent is 1:150- 1:160. 5. The preparation method of the externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules according to claim 2, characterized in that: the preparation of the amine-based chain extender emulsion described in step (2) is specifically: taking an appropriate amount The emulsifier and solvent are stirred at a speed of 1000-2500rpm until they are evenly mixed; the mass ratio of the emulsifier to the solvent is 1:40-1:50; the amine-based chain extender is added at a speed of 1000-2500rpm Stir until uniformly mixed to prepare an emulsion of the amine-based chain extender; the amount of the emulsifier is 10%-20% of the mass of the amine-based chain extender. 6. According to the preparation method of the externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules according to any one of claims 3-5, it is characterized in that: the aliphatic isocyanate described in step (1) repairs The NCO group content of the agent is 3%-12%, and the average functionality is 1.5 to 5.0; the aliphatic isocyanate repair agent is isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI) , 1,4-cyclohexane diisocyanate, cyclohexylmethane-4,4-diisocyanate, allophanate or HDI trimer system of 1,6-hexamethylene diisocyanate; the amino-terminated poly The ether is polyetheramine D400, polyetheramine D230, polyetheramine D2000, 3,5-dimethylthiotoluene-2,6-diamine, 3,5-diethyltoluene-2,4-diamine, 3,5-dimethylthiotoluene-2,4-diamine, 1,4-butanediamine or 1,6-hexanediamine. 7. According to the preparation method of the externally repaired and internally solidified polyurea-based double-wall self-repairing microcapsules according to any one of claims 3-5, it is characterized in that: the amine-based chain extender described in step (2) Diethyltoluenediamine, dimethylthiotoluenediamine, N,N'-dialkylmethyldiphenylamine, cyclohexanediamine, MDH chloride, ethylenediamine, 1,3-diaminopropane , 1,4-diaminobutane, diethylenetriamine, pentaethylenehexamine, hexaethylenediamine, tetraethylenepentamine, pentaethylenehexamine, polyetheramine D400, Polyetheramine D230, ethylenediamine or 3,3'-4,4'-diamino-diphenylmethane MOCA. 8. According to the preparation method of the externally repaired and internally solidified polyurea-based double-walled self-repairing microcapsules according to any one of claims 3-5, it is characterized in that: the emulsification described in step (1)-(3) The agent is sodium dodecylbenzenesulfonate, OP-10, stearyl polyoxyethylene ether, gum arabic, polyoxyethylene ether, fatty ammonia polyoxyethylene ether or polyvinyl alcohol; the solvent is ethyl acetate esters, acetone, cyclohexane, cyclopentane, toluene or chlorobenzene. 9. According to the preparation method of the externally repaired and internally solidified polyurea-based double-walled self-repairing microcapsules according to any one of claims 3-5, it is characterized in that: 2. preparation of double-walled microcapsules described in step (3) In the case of emulsion, 1-5 drops of defoamer can also be added while adding the chain extender emulsion; the defoamer is n-butanol, 1,4-butanediol, polyoxypropylene polyoxyethylene glyceryl ether or poly Methylsiloxane. 10. The self-repairing system adopting the externally repairing and internally solidifying type polyurea-based double-wall self-repairing microcapsules according to claim 1, is characterized in that: The mass fraction of the polyurea-based double-walled microcapsules in the self-repairing system is 5%-18%; the self-repairing system is self-repairing concrete or self-repairing coating.