A polyurethane composite material embedded with a liquid healing network and a method of making the same

Abstract

The application discloses a kind of polyurethane composite material embedded liquid repair network and preparation method thereof, belong to high polymer material technical field, it is by polyurethane prepolymer 40-60 parts, repair agent carrier particle 5-20 parts, liquid repair agent 10-30 parts and dispersing agent 0.1-1 parts composition.The material of the application solves the problem that polyurethane material is easily damaged in long-term use, and the repair efficiency is low.The composite material material of the application has fast, efficient and self-adapting repair performance under large-scale damage and multiple damage, and is suitable for complex environment such as acid and alkali, high temperature, has important application prospect in various industrial equipment, flexible electronic equipment, automobile, building and other fields.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a polyurethane composite material with an embedded liquid repair network and its preparation method. Background Technology

[0002] In modern industry, polyurethane materials are widely used in various fields such as automobiles, aerospace, construction, and electronic equipment due to their excellent mechanical properties, wear resistance, weather resistance, and good processability. These advantages make polyurethane materials an important component of many high-performance products. However, during long-term use, they are inevitably affected by the external environment, especially under high load, high temperature, or harsh climatic conditions, where materials are prone to cracking, fatigue, or aging. This damage not only affects the service life of the material but may also lead to equipment failure or structural failure, thereby affecting the safety and reliability of the product. Therefore, how to improve the damage resistance of polyurethane materials and extend their service life has become an important research direction in the field of materials science.

[0003] With the continuous development of technology, self-healing materials have gradually become one of the hot topics in high-performance materials research. Self-healing materials can automatically restore their structure and function after encountering external damage, avoiding the cumbersome process of traditional repair methods, and possess high application potential, especially in aerospace, automotive, construction, and electronic equipment fields. Existing self-healing polyurethane materials mainly rely on mechanisms such as dynamic covalent bonds or hydrogen bonds to achieve self-healing. However, under conditions of large-area cracks or repeated damage, the repair efficiency and material integrity decrease significantly, mainly due to restricted molecular migration and depletion of repair resources. Furthermore, the performance of these materials in complex chemical environments and extreme temperatures often fails to meet practical requirements.

[0004] Existing invention patent CN 110305466 A proposes a polyurethane / epoxy resin blend with shape memory, self-healing, and recyclability functions, and its preparation method. This polyurethane / epoxy resin blend is a homogeneous blend of polyurethane and epoxy resin, or a two-phase split-phase blend formed by cross-linking and curing a blend of the two with a curing agent. The polyurethane is a linear polyurethane material with disulfide bonds in its main chain, the epoxy resin is a cyclic hydrogen resin prepolymer with furan rings in its side groups, and the curing agent contains maleimide groups. The preparation method of the homogeneous polyurethane / epoxy resin blend is as follows: the polyurethane and epoxy resin prepolymer are dissolved in an organic solvent, stirred and blended at 60–80°C, and dried at 60–80°C after uniform stirring. This invention improves the shape memory, self-healing, and recyclability of polyurethane materials through a blending method, enhances the mechanical properties of polyurethane at room temperature, and does not affect the recyclability of polyurethane at high temperatures. However, it does not solve problems such as repeated damage repair, rapid response, and performance stability under complex environments, making it unsuitable for widespread application. Existing technology, patent CN 111499833 A, introduces a self-healing polyurethane resin by incorporating disulfide-containing self-healing functional groups (polythiol) into polyurethane. While considering corrosion resistance, the distribution and release mechanism of its repair agent is relatively simple, and this technology does not fully consider repeated repair capabilities and long-term environmental adaptability, making it unsuitable for widespread application.

[0005] Therefore, providing a polyurethane composite material with an embedded liquid repair network that can achieve rapid and efficient repair under large-scale damage, and improve the ability to repair multiple times and environmental adaptability is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the present invention, by embedding a liquid repair network in a polyurethane matrix, utilizes the high fluidity of the liquid repair agent and the controllable release characteristics of the micro-nano carrier to not only achieve rapid and efficient repair under large-scale damage, but also significantly improve the ability to repair multiple times and environmental adaptability, providing a new technical solution for the practical application of self-healing materials.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A polyurethane composite material with an embedded liquid repair network comprises the following raw materials in parts by weight:

[0009] The mixture consists of 40-60 parts of polyurethane prepolymer, 5-20 parts of repair agent carrier particles, 10-30 parts of liquid repair agent, and 0.1-1 parts of dispersant.

[0010] The polyurethane prepolymer is prepared by mixing isocyanate and polyol in a molar ratio of 1.8-2.2:1 under the catalysis of a catalyst; and the amount of catalyst used is 0.5-2 parts.

[0011] The liquid repair agent is made by mixing epoxy resin and thiol in a mass ratio of 1-4:1, and is used for cross-linking reaction at cracks.

[0012] Furthermore, the isocyanate is 4,4'-diphenylmethane diisocyanate (MDI), and the polyol is a polyether polyol or a polyester polyol.

[0013] Furthermore, the repair agent carrier particles are modified SiO2 microspheres, the surface of which is treated with a silane coupling agent to improve the bonding strength with the polyurethane matrix, and the microsphere particle size is 10-100 nm.

[0014] In this invention, the microsphere particle size is controlled within the range of 10-100 nm because SiO2 microspheres in this range are at the nanoscale, which can improve the strength, toughness, and impact resistance of the polyurethane matrix. Particle sizes smaller than 10 nm may lead to microsphere agglomeration, reducing dispersibility and reinforcing effect; while particle sizes larger than 100 nm will weaken the interfacial effect of nano-reinforcement, reducing the uniformity and performance of the material. Simultaneously, the epoxy resin to thiol mass ratio is controlled at 1-4:1 because the epoxy groups in the epoxy resin molecule provide cross-linking points, and their ratio directly determines the rigidity and structural stability of the repair network. The thiol groups (-SH) in the thiol undergo a rapid addition reaction with the epoxy groups, forming flexible segments and increasing the ductility of the repair network. When the mass ratio is close to 1:1, the number of thiol groups is close to the stoichiometric requirements of the epoxy groups, forming a high-density cross-linked network, suitable for enhancing the strength after repair. When the mass ratio is 4:1, the thiol groups are slightly excessive, increasing the proportion of flexible segments, and the repair material has better toughness and fatigue resistance, adapting to large strain environments. Increased epoxy resin content raises the viscosity of the repair agent, potentially reducing its penetration into cracks. The proportion of thiol can be appropriately increased depending on the application to effectively reduce viscosity and improve the fluidity and filling properties of the repair agent in microcracks.

[0015] Furthermore, the catalyst is diphenylphosphonic acid, which can accelerate the cross-linking reaction between epoxy groups and thiol groups in the liquid repair agent and improve the repair efficiency; the dispersant is polyether-modified siloxane, which is used to improve the dispersibility of the repair agent carrier particles in the prepolymer.

[0016] Furthermore, the present invention also includes 0.5-5 parts of additives for enhancing weather resistance or mechanical properties.

[0017] Furthermore, the additive is any one or a mixture of antioxidants, ultraviolet absorbers, and flame retardants.

[0018] Furthermore, the antioxidant is 2,6-di-tert-butyl-p-cresol, the ultraviolet absorber is benzophenone, and the flame retardant is decabromostilbene.

[0019] The additives described in this invention can enhance the weather resistance, UV resistance, and flame retardant properties of composite materials. These additives can be selected according to actual application requirements, improving material stability while meeting the requirements for long-term use in different environments.

[0020] This invention also provides a method for preparing the above-mentioned polyurethane composite material with embedded liquid repair network, comprising the following steps:

[0021] (1) Injection and encapsulation of liquid repair agent: Heat epoxy resin to viscous flow state at 50-60℃; slowly add thiol while stirring continuously to ensure uniform mixing; continue stirring for 10-15 minutes until a uniform and transparent liquid repair agent is formed.

[0022] (2) Weigh each raw material according to the above weight proportions, mix the liquid repair agent with the repair agent carrier particles; treat the repair agent and carrier mixture under vacuum conditions for 10-20 minutes to ensure that the liquid repair agent penetrates into the carrier pores; rapidly freeze the carrier injected with liquid repair agent at -40℃; use freeze-drying equipment to perform vacuum freeze-drying to remove excess solvent and ensure stable storage of the repair agent;

[0023] (3) Preparation of polyurethane prepolymer: A polyurethane prepolymer with controllable viscosity is prepared by reacting isocyanate with polyol under the action of a catalyst;

[0024] (4) Molding of composite material: The carrier particles of the encapsulating repair agent are ultrasonically and uniformly dispersed in the polyurethane prepolymer, and then shaped by molding, casting or spraying process, and cured at 50-80℃ for 2-6h to obtain a polyurethane composite material with embedded liquid repair network.

[0025] Furthermore, the preparation method of the repair agent carrier particles is as follows: SiO2 microspheres are dispersed in anhydrous ethanol to ensure that the particles are fully suspended, 0.1-5% of silane coupling agent is added, and the mixture is stirred evenly; the mixture is refluxed at 60°C for 2-4 hours to allow the silane coupling agent to form chemical bonds with the SiO2 surface; the mixture is washed multiple times with ethanol to remove unreacted silane coupling agent, and finally dried at 80°C to obtain modified SiO2 microspheres.

[0026] Furthermore, the silane coupling agent is γ-aminopropyltriethoxysilane or γ-methacryloyloxypropyltrimethoxysilane.

[0027] Furthermore, the vacuum pressure in step (2) is 10 Pa, the freeze-drying temperature is -60 °C, and the freeze-drying time is 12-24 h.

[0028] Furthermore, the composite material prepared by this invention can achieve self-healing under acidic and alkaline environments (pH 2-12) and high temperature conditions (below 200°C).

[0029] This invention addresses the problems of low repair efficiency and long repair time in existing technologies for large-scale damage through the synergistic effect of liquid repair agents and micro / nano carriers. The high fluidity of the liquid repair agent and the controllable release mechanism of the micro / nano carriers enable the material to respond rapidly and achieve efficient repair upon damage. The repair agent, stored and released through the micro / nano carriers, can rapidly penetrate and fill cracks upon their occurrence, subsequently curing rapidly through the crosslinking reaction of epoxy resin and thiol, thereby restoring the material's mechanical properties. Compared to existing technologies, this invention significantly shortens the repair time and maintains good repair performance under repeated damage and complex environmental conditions.

[0030] In the technical solution of this invention, the micro / nano carrier is SiO2 microspheres with a surface silanization treatment, which have a highly controllable pore structure (see appendix). Figure 1 This technology effectively loads liquid repair agents. Through vacuum-assisted injection, the liquid repair agent can be fully filled into the pores of the microspheres, ensuring stable storage and uniform distribution. Simultaneously, the nanoscale size and high specific surface area of ​​the microspheres ensure good dispersion of the repair agent within the material, avoiding local aggregation or sedimentation. Furthermore, utilizing the high reactivity of epoxy and thiol groups, rapid cross-linking and curing after crack filling is achieved. When damage occurs, the liquid repair agent is released induction by the crack, filling the crack and reacting rapidly under environmental conditions (such as humidity or temperature) to form a dense cured layer, restoring the material's integrity and mechanical properties. The low viscosity of the liquid repair agent allows it to quickly penetrate deep into the crack, while the high activity of the cross-linking reaction further shortens the curing time. Compared to traditional repair materials that require external heating or long periods of static storage, the liquid repair network can complete initial repair within minutes.

[0031] In this invention, the dispersion of micro-nano carriers within a polyurethane matrix forms a "lattice" structure. Each microsphere is a node for storing and releasing repair agents. As cracks propagate, multiple repair agent nodes are gradually triggered to release, resulting in a synergistic repair effect. This process is similar to information transmission or signal activation in a network system. Each node in the network structure can work independently, and damage in different regions can independently induce the release of repair agents.

[0032] The composite material of this invention can be widely used in various industrial equipment, aerospace vehicles, automobiles, construction, flexible electronic devices and other fields, and has significant advantages in terms of damage resistance and extended service life. Attached Figure Description

[0033] Figure 1The surface morphology diagram of the micro / nano carrier provided by this invention;

[0034] Figure 2 The images provided by this invention show the morphological changes of the composite material before and after repair, where (a) and (c) are macroscopic and microscopic images before repair, respectively; and (b) and (d) are macroscopic and microscopic images after repair, respectively. Detailed Implementation

[0035] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1

[0037] Polyurethane composite material I comprises the following components: 50g polyurethane prepolymer, 10g repair agent carrier particles, 15g liquid repair agent, 1g catalyst, 0.5g dispersant, and 2g additive (antioxidant).

[0038] The preparation method of this polyurethane composite material I is as follows:

[0039] (1) Disperse 15g of SiO2 microspheres in anhydrous ethanol to ensure complete suspension of the particles. Add 0.5g of γ-aminopropyltriethoxysilane and stir until homogeneous. Reflux at 60℃ for 2h to form chemical bonds between the silane coupling agent and SiO2. Wash repeatedly with ethanol to remove unreacted coupling agent, and dry at 80℃.

[0040] (2) Heat epoxy resin (10g) to 60℃ to make it viscous. Slowly add thiol (3.33g) and stir evenly for 10 minutes to obtain liquid repair agent. Mix the obtained liquid repair agent with modified SiO2 microspheres at a mass ratio of 1.5:1 and treat under vacuum for 10 minutes. Ensure that the liquid repair agent penetrates into the pores of the carrier; rapidly freeze the carrier injected with liquid repair agent at -40℃; use a freeze dryer to freeze dry at -60℃ and 10pa vacuum for 18 hours to remove excess solvent and ensure stable storage of the repair agent.

[0041] (3) React MDI and polyether polyol at a molar ratio of 1.9:1, add catalyst (1g), and stir at 200-500 rpm for 2-4 hours at 60°C to obtain the desired polyurethane prepolymer.

[0042] (4) The carrier particles of the encapsulating repair agent were uniformly dispersed in the polyurethane prepolymer and ultrasonically dispersed for 30 min. The mixture was then molded using a compression molding process and cured at 50°C for 4 h to obtain polyurethane composite material I.

[0043] Example 2

[0044] Polyurethane composite material II comprises the following components: 45g polyurethane prepolymer, 12g repair agent carrier particles, 20g liquid repair agent, 1.5g catalyst, 0.3g dispersant, and 1.5g additive (UV absorber).

[0045] The preparation and application methods of the polyurethane composite material II are the same as those in Example 1, thus obtaining polyurethane composite material II.

[0046] Example 3

[0047] Polyurethane composite material III comprises the following components: 55g polyurethane prepolymer, 8g repair agent carrier particles, 12g liquid repair agent, 0.8g catalyst, 0.8g dispersant, and 4g additive (flame retardant).

[0048] The preparation and application methods of the polyurethane composite material III are the same as those in Example 1, thus obtaining polyurethane composite material III.

[0049] Example 4

[0050] Polyurethane composite material IV comprises the following components: 40g polyurethane prepolymer, 9g repair agent carrier particles, 18g liquid repair agent, 1g catalyst, 0.4g dispersant, and 3g additive (antioxidant).

[0051] The preparation and application methods of the polyurethane composite material IV are the same as those in Example 1, thus obtaining polyurethane composite material IV.

[0052] Example 5

[0053] Polyurethane composite material V comprises the following components: 60g polyurethane prepolymer, 6g repair agent carrier particles, 10g liquid repair agent, 1.8g catalyst, 0.6g dispersant, and 1g additive (UV absorber).

[0054] The preparation and application methods of this polyurethane composite material V are the same as those in Example 1, thus obtaining polyurethane composite material V.

[0055] Example 6

[0056] Polyurethane composite material VI comprises the following components: 48g polyurethane prepolymer, 10g repair agent carrier particles, 14g liquid repair agent, 1.2g catalyst, 0.4g dispersant, and 2g additive (antioxidant).

[0057] The preparation and application methods of this polyurethane composite material VI are the same as those in Example 1, thus obtaining polyurethane composite material VI.

[0058] Example 7

[0059] Polyurethane composite material VII comprises the following components: 55g polyurethane prepolymer, 10g repair agent carrier particles, 12g liquid repair agent, 1g catalyst, 0.5g dispersant, and 3g additive (flame retardant).

[0060] The preparation and application methods of this polyurethane composite material VII are the same as those in Example 1, thus obtaining polyurethane composite material VII.

[0061] Example 8

[0062] Polyurethane composite material VIII comprises the following components: 53g polyurethane prepolymer, 7g repair agent carrier particles, 13g liquid repair agent, 1.5g catalyst, 0.6g dispersant, and 4g additive (antioxidant).

[0063] The preparation and application methods of the polyurethane composite material VIII are the same as those in Example 1, thus obtaining polyurethane composite material VIII.

[0064] Example 9

[0065] Polyurethane composite material IX comprises the following components: 50g polyurethane prepolymer, 11g repair agent carrier particles, 16g liquid repair agent, 1.3g catalyst, 0.5g dispersant, and 3g additive (flame retardant).

[0066] The preparation and application methods of the polyurethane composite material IX are the same as those in Example 1, thus obtaining polyurethane composite material IX.

[0067] Example 10

[0068] Polyurethane composite material X comprises the following components: 49g polyurethane prepolymer, 9g repair agent carrier particles, 17g liquid repair agent, 1.4g catalyst, 0.6g dispersant, and 4g additive (flame retardant).

[0069] The preparation and application methods of the polyurethane composite material X are the same as those in Example 1, resulting in polyurethane composite material X.

[0070] The polyurethane composite materials prepared in each embodiment were subjected to performance tests according to the test methods described above, and the performance test results are shown in Table 1.

[0071] Figure 1SEM images of the micro / nano carrier are shown, revealing a regular porous surface that indicates a strong storage capacity for the repair agent. A larger internal volume allows for the encapsulation of more repair agent, ensuring a sufficient supply of material during the self-healing process and thus improving repair efficiency. Furthermore, the uniform pore size allows for better control of the repair agent release rate, facilitating continuous supply during the repair process and ensuring complete crack closure. Figure 2 The images show the morphological changes of the composite material before and after repair. The repair efficiency was evaluated by artificially creating cracks. The macroscopic images show that the cracked material was almost completely repaired after one minute, indicating that the repair efficiency is high. The microscopic images further demonstrate that the cracks were not only covered on the surface, but the repair agent also penetrated into the deep layers of the cracks, providing effective structural reinforcement.

[0072] The performance test results show that Example 3 has the highest self-healing efficiency of 96%, while Example 9 shows outstanding performance in terms of hardness, impact resistance, tensile strength and self-healing efficiency, and has the best overall performance.

[0073] Table 1. Coating performance test results

[0074]

[0075]

[0076] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A polyurethane composite material with an embedded liquid healing network, characterized in that, The following raw materials are included by weight: polyurethane prepolymer 40-60 parts, repair agent carrier particles 5-20 parts, liquid repair agent 10-30 parts, and dispersant 0.1-1 part; The polyurethane prepolymer is prepared by mixing isocyanate and polyol at a molar ratio of 1.8-2.2:1 under the catalysis of a catalyst; The liquid repair agent is prepared by mixing epoxy resin and mercaptan at a mass ratio of 1-4:1; The repair agent carrier particles are modified SiO2 microspheres, and the preparation method of the repair agent carrier particles is as follows: SiO2 microspheres are dispersed in anhydrous ethanol to ensure that the particles are fully suspended, 0.1-5% of a silane coupling agent is added, and stirring is uniform; refluxing at 60°C for 2-4h enables the silane coupling agent to form a chemical bond with the surface of SiO2; the unreacted silane coupling agent is removed by washing with ethanol for multiple times, and finally the modified SiO2 microspheres are obtained by drying at 80°C; The injection and packaging of the liquid repair agent: the epoxy resin is heated to a viscous flow state at 50-60°C; mercaptan is slowly added under continuous stirring to ensure uniform mixing; continue stirring for 10-15 min until a uniform transparent liquid repair agent is formed; mix the liquid repair agent with the repair agent carrier particles; treat the repair agent and carrier mixture under vacuum for 10-20 min to ensure that the liquid repair agent penetrates into the pores of the carrier; freeze the carrier injected with the liquid repair agent at -40°C; use a freeze-drying device to remove excess solvent by vacuum freeze-drying to ensure stable storage of the repair agent.

2. The polyurethane composite material of claim 1, wherein, The catalyst is diphenyl phosphonic acid, and the dispersant is polyether-modified siloxane.

3. The polyurethane composite material of claim 1, wherein the liquid-embedded self-healing network is characterized by, 0.5-5 parts of an additive are further included.

4. The polyurethane composite of claim 3, wherein the liquid-embedded self-healing network is characterized by, The additive is any one or more of an antioxidant, an ultraviolet absorber, and a flame retardant.

5. Process for the production of a polyurethane composite material with an embedded liquid healing network according to any one of claims 1 to 4, characterized in that The following steps are included: (1) heat the epoxy resin to a viscous flow state at 50-60°C; slowly add mercaptan under continuous stirring to ensure uniform mixing; continue stirring for 10-15 min until a uniform transparent liquid repair agent is formed; (2) according to any one of claims 1-4, the weight of each raw material is taken, the liquid repair agent is mixed with the repair agent carrier particles; treat the repair agent and carrier mixture under vacuum for 10-20 min to ensure that the liquid repair agent penetrates into the pores of the carrier; freeze the carrier injected with the liquid repair agent at -40°C; use a freeze-drying device to remove excess solvent by vacuum freeze-drying to ensure stable storage of the repair agent; (3) preparation of polyurethane prepolymer: prepare a polyurethane prepolymer with controllable viscosity by reacting isocyanate and polyol under the action of a catalyst; (4) molding of the composite material: uniformly disperse the carrier particles packaged with the repair agent in the polyurethane prepolymer by ultrasonic dispersion, add the remaining raw materials during the dispersion process, then mold by molding, pouring, or spraying process, and cure at 50-80°C for 2-6h to obtain a polyurethane composite material with an embedded liquid repair network.

6. The method for preparing a polyurethane composite material with an embedded liquid repair network according to claim 5, characterized in that, The silane coupling agent is γ-aminopropyl triethoxysilane or γ-methacryloyloxypropyl trimethoxysilane.

7. The method for preparing a polyurethane composite material with an embedded liquid repair network according to claim 5, characterized in that, The vacuum pressure in step (2) is 10 Pa, the freeze-drying temperature is -60°C, and the freeze-drying time is 12-24 h. The vacuum pressure in step (2) is 10 Pa, the freeze-drying temperature is -60°C, and the freeze-drying time is 12-24 h.

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