Self-repairing PU material and preparation method thereof
By introducing core-shell self-healing microspheres and reinforced carbon nanotubes into PU materials, a porous structure is constructed, achieving self-healing and improved mechanical properties of PU materials, thus solving the problems of insufficient self-healing ability and weak mechanical properties of traditional PU materials.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SUZHOU RUIGAO QIHANG NEW MATERIALS CO LTD
- Filing Date
- 2026-06-09
- Publication Date
- 2026-07-31
AI Technical Summary
Existing PU foam materials lack self-healing capabilities and are difficult to heal themselves after damage. Furthermore, traditional modification methods cannot simultaneously improve mechanical properties and structural stability.
A porous structure is constructed by using core-shell self-healing microspheres and a polyurethane foam layer doped with reinforced carbon nanotubes, through chemical reaction and physical cross-linking, to achieve self-healing and mechanical reinforcement.
The material can heal itself after being damaged, maintain high mechanical strength, and significantly improve the material's self-healing ability and mechanical properties.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of polymer materials technology, specifically to a self-healing PU material and its preparation method. Background Technology
[0002] Polyurethane (PU) foam composites are widely used in artificial leather, decorative materials, flexible padding, and composite fabrics due to their advantages such as light weight, flexibility, good cushioning, and easy processing. Conventional PU foam materials are prepared by polymerizing and foaming polyols and isocyanates. Although they have basic molding and performance properties, they are easily subjected to external friction, bending, scratching and other forces during actual service, which can cause microcracks and surface scratches. This not only damages the integrity of the material's appearance, but also easily causes the cracks to expand further, resulting in a gradual decline in mechanical properties and a shortened service life.
[0003] Most existing PU foam materials currently lack self-repair capabilities. Once damaged, they are difficult to heal on their own and can only be repaired manually or replaced directly, increasing the cost of use and maintenance. At the same time, the traditional PU foam matrix has a simple cross-linking network and insufficient stability of the cell structure, resulting in weak tensile and tear resistance mechanical properties. Even though some studies have modified the material by adding ordinary carbon nanotubes and inorganic fillers, they can only slightly improve the basic mechanical strength. The fillers tend to agglomerate and have poor dispersion in the matrix, resulting in weak bonding force with the polyurethane interface and making it difficult to build a stable reinforcing network. Therefore, it is impossible to achieve both high strength and long-term structural stability.
[0004] In addition, most existing self-healing modified PU materials are modified by doping with a single repair component, lacking the controlled-release repair mechanism of core-shell coated functional microspheres. This makes it difficult to release active components in a targeted manner to achieve chemical bond recombination after damage is triggered. Furthermore, conventional modification systems do not perform dual functionalization modification on carbon nanotubes, which cannot form a synergistic adaptation effect of structure and functional groups with self-healing microspheres and PU foam matrix. This often results in a shortcoming: good self-healing effect but insufficient mechanical strength, or significant mechanical improvement but lack of self-healing ability. It is difficult to simultaneously achieve excellent initial mechanical properties, damage resistance, and the ability to self-heal and retain strength after damage.
[0005] To address this technical deficiency, a solution is proposed. Summary of the Invention
[0006] The purpose of this invention is to provide a self-healing PU material and its preparation method, which solves the technical problem of further improving the self-healing ability of self-healing PU materials and the strength of PU materials before and after self-healing in the prior art.
[0007] The objective of this invention can be achieved through the following technical solutions: A self-healing PU material includes, from bottom to top, a base fabric layer, a PU foam layer adhered to the base fabric layer, a PU surface layer adhered to the PU foam layer, and a coating layer applied to the PU surface layer; The PU foam layer is prepared by foaming core-shell self-healing microspheres and reinforced carbon nanotube-doped polytetrahydrofuran ether diol with 4,4-diisocyanate dicyclohexylmethane after catalytic polymerization.
[0008] Furthermore, the preparation method of the PU foam layer is as follows: Under a nitrogen atmosphere, core-shell self-healing microspheres and reinforced carbon nanotubes are added to a reactor containing N,N-dimethylacetamide. After stirring for 40-60 minutes, polytetrahydrofuran ether diol and 4,4-diisocyanate dicyclohexylmethane are added. The mixture is heated to 60-70°C and stirred for 1-2 hours. Then, dibutyltin dilaurate is added. The mixture is stirred at 60-70°C for 20-30 minutes. Deionized water and polyether silicone oil are added. The mixture is stirred at 1500-2000 r / min until the material turns milky white. The mixture is then poured into a mold at 40-50°C and foamed for 5-8 minutes. After foaming, the mixture is allowed to stand for 3-4 hours before demolding. Finally, the mixture is transferred to a drying oven at 80-90°C for 6-8 hours to mature, thus obtaining the PU foam layer.
[0009] Reaction mechanism for preparing PU foam layer: In a nitrogen-protected atmosphere, core-shell self-healing microspheres and reinforced carbon nanotubes are first fully dispersed in N,N-dimethylacetamide medium to eliminate filler agglomeration and achieve a uniform and stable distribution. Subsequently, the hydroxyl groups of polytetrahydrofuran ether diol undergo addition polymerization with the isocyanate groups of 4,4-diisocyanate dicyclohexylmethane to generate a polyurethane prepolymer. Then, dibutyltin dilaurate is added as a catalyst to promote further molecular chain growth and mild cross-linking, perfecting the polymer matrix network. Finally, deionized water, a foaming agent, is introduced into the system to... Ionized water reacts with isocyanate groups to generate carbon dioxide gas, which serves as the foaming gas source. Polyether silicone oil is enriched at the gas-liquid interface, reducing the surface tension of the system, preventing bubble coalescence and rupture, and allowing the bubbles to be uniformly dispersed within the system. Finally, the material is injected into a mold and gradually solidifies to form a continuous porous foam skeleton structure. Subsequent curing further completes the residual cross-linking reaction, stabilizing the molecular network and pore structure. Core-shell self-healing microspheres and reinforced carbon nanotubes are uniformly distributed in the polyurethane foam matrix in the form of physical doping, ultimately yielding a composite modified PU foam layer.
[0010] Furthermore, the ratio of the core-shell self-healing microspheres, reinforced carbon nanotubes, N,N-dimethylacetamide, polytetrahydrofuran ether diol, dibutyltin dilaurate, deionized water, and polyether silicone oil is 2.0-3.0g:1.0-1.5g:80-100mL:45g:0.4g:2.5-3.5mL:0.4-0.6g, and the amount of 4,4-diisocyanate dicyclohexylmethane added is 0.52 times the total molar amount of the heavy hydroxyl groups of polytetrahydrofuran ether diol.
[0011] Furthermore, the preparation method of the core-shell self-healing functional microspheres is as follows: polyetheramine and polymethyl methacrylate are added to a reaction vessel containing dichloromethane and stirred for 10-20 min. Then, a mixed solution is added and stirred at 20-30℃ and 2000-3000 r / min for 20-30 min. Next, an aqueous solution of polyvinyl alcohol is added and stirred at 40-50℃ and 1000-1500 r / min for 3-4 h. After naturally cooling to room temperature, the product is centrifuged and collected. The product is washed 2-3 times with deionized water and then transferred to a drying oven and dried at 40-50℃ to obtain core-shell self-healing functional microspheres.
[0012] Reaction mechanism for preparing core-shell self-healing microspheres: Polyetheramine and polymethyl methacrylate were dissolved in dichloromethane as an organic solvent. This organic phase was then mixed with an aqueous phase containing Tween 80 and Span 20. After mechanical shearing, a stable oil-in-water emulsion was formed. Polyvinyl alcohol was then added to further stabilize the emulsion system. During the heating and stirring process, dichloromethane gradually evaporated, and dissolved polymethyl methacrylate continuously precipitated and solidified on the surface of the droplets, encapsulating the polyetheramine inside to form a core-shell structure precursor. Subsequently, impurities and residual solvents were removed by cooling, centrifugation, washing, and low-temperature drying, finally producing core-shell microspheres with polyetheramine as the core and polymethyl methacrylate as the shell. When the microspheres are stimulated by stress, the shell breaks and releases polyetheramine, which can chemically react with the polyurethane matrix, thereby endowing the material with self-healing properties.
[0013] Furthermore, the ratio of the amount of polyetheramine, polymethyl methacrylate, dichloromethane, the mixed solution, and the polyvinyl alcohol aqueous solution is 4g:2g:20-28mL:80mL:100mL, and the mass fraction of the polyvinyl alcohol aqueous solution is 1%; the mixed solution is obtained by dissolving 0.72g Tween 80 and 0.48g Span 20 in 80mL of deionized water.
[0014] Furthermore, the enhanced carbon nanotubes are prepared by the following steps: A1. Carboxylated carbon nanotubes and 1-hydroxyethyl-3-methylimidazolium chloride were added to a reaction vessel containing N,N-dimethylformamide and stirred for 20-30 min. Then, dicyclohexylcarbodiimide and 4-dimethylaminopyridine were added. The temperature was raised to 50-60℃ and reacted for 10-12 h. After that, the temperature was raised to 100-120℃ and reacted for 20-24 h. After the reaction was completed, the product was separated by centrifugation. The product was washed 2-3 times with anhydrous ethanol and then transferred to a vacuum drying oven and dried at 60℃ to constant weight to obtain pretreated carbon nanotubes. A2. Add β-aminopropionic acid and potassium hydroxide to a reaction vessel containing deionized water. Stir at 60-70℃ for 10-12 hours, then add pretreated carbon nanotubes and continue stirring for 6-8 hours. After the reaction is complete, centrifuge to separate the product. Wash the product with deionized water 2-3 times and place it in a vacuum drying oven to dry at 80℃ to constant weight to obtain reinforced carbon nanotubes.
[0015] Reaction mechanism for preparing reinforced carbon nanotubes: Carboxylated carbon nanotubes, with numerous active carboxyl functional groups on their surface, are uniformly dispersed in an N,N-dimethylformamide solvent system. 1-Hydroxyethyl-3-methylimidazolium chloride, containing hydroxyl and imidazolium cationic structures, undergoes esterification condensation between the carboxyl groups on the carbon nanotube surface and the hydroxyl groups of the imidazolium ionic liquid under the activation of dicyclohexylcarbodiimide dehydration condensation and the catalysis of 4-dimethylaminopyridine. This results in the stable covalent grafting of imidazolium cationic groups onto the carbon nanotube surface, yielding pretreated carbon nanotubes with surface-bonded imidazolium chloride. Following this, β-aminopropyl... An acid and potassium hydroxide are mixed and reacted in an aqueous solution. The acid-base neutralization causes β-aminopropionic acid to deprotonate and form aminopropionate anions. Then, pretreated carbon nanotubes are added. Taking advantage of the anion exchange property of ionic liquids, chloride ions on the surface of the pretreated carbon nanotubes undergo electrostatic ion exchange with aminopropionate anions in the system. The aminopropionate ions replace chloride ions and are fixed in the imidazole cation coordination environment. Finally, the carbon nanotube surface is covalently grafted with imidazole cations and coordinated with aminopropionate anions, resulting in reinforced carbon nanotubes.
[0016] Furthermore, in step A1, the ratio of carboxylated carbon nanotubes, 1-hydroxyethyl-3-methylimidazolium chloride, N,N-dimethylformamide, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1g:2.2-2.5g:35-45mL:0.45-0.55g:0.08-0.12g.
[0017] Furthermore, in step A2, the ratio of β-aminopropionic acid, potassium hydroxide, deionized water, and pretreated carbon nanotubes is 1g:1g:25-35mL:1.8-2.2g.
[0018] Furthermore, the self-healing PU material is prepared by the following steps: S1. Add deionized water and color paste to PU resin and stir evenly to obtain PU mixture. Coat the PU mixture onto release paper with a coating thickness of 0.15±0.01mm and a machine speed of 15±3m / min. After coating, use stepped heating to dry the product at temperatures of 90℃, 100℃, 110℃, 120℃, 130℃, and 135℃, with a total drying time of 4min. Set the same time period for each temperature to obtain the PU surface layer. S2. Apply adhesive to the PU surface layer by roller, then bond the PU foam layer to it, and use a stepped heating and drying method with temperatures of 100℃, 110℃ and 125℃ in sequence, for a total drying time of 15 minutes. Set the same time period for each temperature to obtain the PU surface layer bonded to the PU foam layer. S3. Apply adhesive to the PU surface layer by roller, then stack non-woven fabric on top, and heat and dry in a stepped manner at temperatures of 135℃, 140℃, and 145℃, with a drying time of 12 minutes. Set the same time period for each temperature. After drying, curl the fabric to obtain a self-healing PU material.
[0019] Furthermore, in step S1, the ratio of the amount of PU resin, deionized water and pigment is 100g:20-25mL:8-12g.
[0020] The present invention has the following beneficial effects: 1. In the preparation method of the self-healing PU material of this application, the core-shell self-healing functional microspheres can break the shell when the material is scratched and subjected to stress, releasing the internal polyetheramine active component to react chemically with the polyurethane matrix. The continuous porous structure of the PU foam layer provides a spatial channel for the diffusion of the active component and the interfacial recombination. At the same time, the modified and reinforced carbon nanotubes can stabilize the matrix network structure and inhibit the further propagation of damage cracks. The special structure of the three and the functional groups of the elements match and cooperate with each other, so that the self-healing PU material has excellent self-healing ability. After being damaged, the scratch can be self-healed by light or mild heating environment. After repair, it can still maintain a high mechanical strength retention rate, which greatly improves the defects of traditional PU materials that cannot heal themselves after damage and have serious performance degradation.
[0021] 2. In the preparation method of the self-healing PU material of this application, the surface of the modified reinforced carbon nanotubes is grafted with imidazole cations and aminopropionic acid functional groups, which can form covalent bonds and electrostatic coordination multiple interface interactions with the polyurethane molecular chains of the PU foam layer. This constructs an interlaced reinforcing network in the foam matrix, effectively transferring and dispersing the stress, inhibiting molecular chain slippage and cell structure deformation. The core-shell self-healing functional microspheres, as rigid fillers, are uniformly dispersed in the pores and molecular chain gaps of the PU foam layer, playing a role in physical filling and supporting the skeleton, reducing internal defects in the foam layer. The two, together with the three-dimensional porous cross-linked structure of the PU foam layer, form a mechanically synergistic reinforcing system, which greatly improves the tensile strength and tear strength of the self-healing PU material. This overcomes the problems of easy cell collapse, low mechanical strength, and poor tear resistance of traditional PU foam materials from a structural perspective. Detailed Implementation
[0022] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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.
[0023] In this application, the polytetrahydrofuran ether diol is selected from Nantong Yuanrong Chemical Co., Ltd., CAS25190-06-1, with a molecular weight of 2000; In this application, the polyetheramine is selected from Wuhan Jiyesheng Chemical Co., Ltd., and has an amine value of 0.95; In this application, the polymethyl methacrylate is selected from Dongguan Changping Boiling Point Plastics Business Department, with the brand name SRG097; In this application, the carboxylated carbon nanotubes are selected from Xi'an Qiyue Biotechnology Co., Ltd., with a particle size of 8 nm and a length of 10 μm; In this application, the PU resin is selected from Hubei Chuangxin Polyurethane Materials Co., Ltd., CAS No. 51852-81-4, and grade CX-926. In this application, the colorant is selected from Zhejiang Zhongtan New Materials Co., Ltd., with the grade JY-6300 and a coloring strength of 100. In this application, the adhesive is selected from Shenzhen Yimeijia Epoxy Co., Ltd., and the model is 842; In this application, the nonwoven fabric is selected from Dezhou Runyue New Materials Co., Ltd., and has a thickness of 3.0 mm.
[0024] Example 1 This embodiment provides a method for preparing a PU foam layer, including the following steps: Step I: Preparation of core-shell self-healing functional microspheres Weigh out 72g of Tween 80 and 48g of Span 20 and dissolve them in 8000mL of deionized water to obtain a mixed solution; Weigh 40g of polyetheramine and 20g of polymethyl methacrylate and add them to a reactor containing 200mL of dichloromethane. After stirring for 10min, add 800mL of the mixed solution and stir at 20℃ and 2000r / min for 20min. Then add 1000mL of 1wt% polyvinyl alcohol aqueous solution and stir at 40℃ and 1000r / min for 3h. After naturally cooling to room temperature, centrifuge to separate the product, collect the product, wash the product twice with deionized water, transfer it to a drying oven, and dry it at 40℃ to obtain core-shell self-healing microspheres.
[0025] Step II: Preparation of reinforced carbon nanotubes Weigh 300g of carboxylated carbon nanotubes and 660g of 1-hydroxyethyl-3-methylimidazolium chloride and add them to a reaction vessel containing 1050mL of N,N-dimethylformamide. Stir for 20min, then add 135g of dicyclohexylcarbodiimide and 24g of 4-dimethylaminopyridine. Heat to 50℃ and react for 10h. Then continue to heat to 100℃ and react for 20h. After the reaction is completed, centrifuge and separate the product. Wash the product twice with anhydrous ethanol and transfer it to a vacuum drying oven. Dry it at 60℃ to constant weight to obtain pretreated carbon nanotubes. Weigh 100g of β-aminopropionic acid and 100g of potassium hydroxide and add them to a reaction vessel containing 2500mL of deionized water. Stir at 60℃ for 10h, then add 180g of pretreated carbon nanotubes and continue stirring for 6h. After the reaction is complete, centrifuge to separate the product. Wash the product twice with deionized water and place it in a vacuum drying oven to dry at 80℃ to constant weight to obtain reinforced carbon nanotubes.
[0026] Step III: Preparation of PU foam layer Under a nitrogen atmosphere, 20g of core-shell self-healing microspheres and 10g of reinforced carbon nanotubes were weighed and added to a reactor containing 800mL of N,N-dimethylacetamide. After stirring for 40min, 450g of polytetrahydrofuran ether glycol was added, and 4,4-diisocyanate dicyclohexylmethane was added at 0.52 times the total molar amount of hydroxyl groups in the polytetrahydrofuran ether glycol. The mixture was heated to 60℃ and stirred for 1h. Then, 4g of dibutyltin dilaurate was added, and the mixture was stirred at 60℃ for 20min. Finally, 25mL of deionized water and 4g of polyether silicone oil were added, and the mixture was stirred at 1500r / min until the material turned milky white. The mixture was poured into a mold at 40℃ and foamed for 5min. After foaming, the mixture was allowed to stand for 3h before demolding. Finally, it was transferred to an 80℃ drying oven for 6h to obtain a PU foam layer.
[0027] Example 2 This embodiment provides a method for preparing a PU foam layer, including the following steps: Step I: Preparation of core-shell self-healing functional microspheres Weigh out 72g of Tween 80 and 48g of Span 20 and dissolve them in 8000mL of deionized water to obtain a mixed solution; Weigh 40g of polyetheramine and 20g of polymethyl methacrylate and add them to a reactor containing 240mL of dichloromethane. After stirring for 15min, add 800mL of the mixed solution and stir at 25℃ and 2500r / min for 25min. Then add 1000mL of 1wt% polyvinyl alcohol aqueous solution and stir at 45℃ and 1200r / min for 3.5h. After naturally cooling to room temperature, centrifuge to separate the product, collect the product, wash the product twice with deionized water, transfer it to a drying oven, and dry it at 45℃ to obtain core-shell self-healing microspheres.
[0028] Step II: Preparation of reinforced carbon nanotubes Weigh 300g of carboxylated carbon nanotubes and 705g of 1-hydroxyethyl-3-methylimidazolium chloride and add them to a reaction vessel containing 1200mL of N,N-dimethylformamide. Stir for 25min, then add 150g of dicyclohexylcarbodiimide and 30g of 4-dimethylaminopyridine. Heat to 55℃ and react for 11h. Then continue to heat to 110℃ and react for 22h. After the reaction is completed, centrifuge and separate the product. Wash the product twice with anhydrous ethanol and transfer it to a vacuum drying oven. Dry it at 60℃ to constant weight to obtain pretreated carbon nanotubes. Weigh 100g of β-aminopropionic acid and 100g of potassium hydroxide and add them to a reaction vessel containing 3000mL of deionized water. Stir at 65℃ for 11h, then add 200g of pretreated carbon nanotubes and continue stirring for 7h. After the reaction is complete, centrifuge to separate the product. Wash the product twice with deionized water and place it in a vacuum drying oven to dry at 80℃ to constant weight to obtain reinforced carbon nanotubes.
[0029] Step III: Preparation of PU foam layer Under a nitrogen atmosphere, 25g of core-shell self-healing microspheres and 12g of reinforced carbon nanotubes were weighed and added to a reactor containing 900mL of N,N-dimethylacetamide. After stirring for 50min, 450g of polytetrahydrofuran ether glycol was added, and 4,4-diisocyanate dicyclohexylmethane was added at 0.52 times the total molar amount of hydroxyl groups in the polytetrahydrofuran ether glycol. The mixture was heated to 65℃ and stirred for 1.5h. Then, 4g of dibutyltin dilaurate was added, and the mixture was stirred at 65℃ for 25min. Finally, 30mL of deionized water and 5g of polyether silicone oil were added, and the mixture was stirred at 1700r / min until the material turned milky white. The mixture was poured into a mold at 45℃ and foamed for 6min. After foaming, the mixture was allowed to stand for 3.5h before demolding. Finally, the mixture was transferred to an 85℃ drying oven for 7h to obtain a PU foam layer.
[0030] Example 3 This embodiment provides a method for preparing a PU foam layer, including the following steps: Step I: Preparation of core-shell self-healing functional microspheres Weigh out 72g of Tween 80 and 48g of Span 20 and dissolve them in 8000mL of deionized water to obtain a mixed solution; Weigh 40g of polyetheramine and 20g of polymethyl methacrylate and add them to a reactor containing 280mL of dichloromethane. After stirring for 20min, add 800mL of the mixed solution and stir at 30℃ and 3000r / min for 30min. Then add 1000mL of 1wt% polyvinyl alcohol aqueous solution and stir at 50℃ and 1500r / min for 4h. After naturally cooling to room temperature, centrifuge to separate the product and collect it. Wash the product three times with deionized water and transfer it to a drying oven to dry at 50℃ to obtain core-shell self-healing microspheres.
[0031] Step II: Preparation of reinforced carbon nanotubes Weigh 300g of carboxylated carbon nanotubes and 750g of 1-hydroxyethyl-3-methylimidazolium chloride and add them to a reaction vessel containing 1350mL of N,N-dimethylformamide. Stir for 30min, then add 165g of dicyclohexylcarbodiimide and 36g of 4-dimethylaminopyridine. Heat to 60℃ and react for 12h. Then continue to heat to 120℃ and react for 24h. After the reaction is completed, centrifuge and wash the product three times with anhydrous ethanol. Transfer the product to a vacuum drying oven and dry at 60℃ to constant weight to obtain pretreated carbon nanotubes. Weigh 100g of β-aminopropionic acid and 100g of potassium hydroxide and add them to a reaction vessel containing 3500mL of deionized water. Stir at 70℃ for 12h, then add 220g of pretreated carbon nanotubes and continue stirring for 8h. After the reaction is complete, centrifuge to separate the product. Wash the product three times with deionized water and place it in a vacuum drying oven to dry at 80℃ to constant weight to obtain reinforced carbon nanotubes.
[0032] Step III: Preparation of PU foam layer Under a nitrogen atmosphere, 30g of core-shell self-healing microspheres and 15g of reinforced carbon nanotubes were weighed and added to a reactor containing 1000mL of N,N-dimethylacetamide. After stirring for 60min, 450g of polytetrahydrofuran ether glycol was added, and 4,4-diisocyanate dicyclohexylmethane was added at 0.52 times the total molar amount of hydroxyl groups in the polytetrahydrofuran ether glycol. The mixture was heated to 70℃ and stirred for 2h. Then, 4g of dibutyltin dilaurate was added, and the mixture was stirred at 70℃ for 30min. Finally, 35mL of deionized water and 6g of polyether silicone oil were added, and the mixture was stirred at 2000r / min until the material turned milky white. The mixture was poured into a mold at 50℃ and foamed for 8min. After foaming, the mixture was allowed to stand for 4h before demolding. Finally, it was transferred to a drying oven at 90℃ and cured for 8h to obtain the PU foam layer.
[0033] Example 4 This embodiment provides a method for preparing a self-healing PU material, including the following steps: Step 1: Prepare the PU surface layer Weigh 100g of PU resin, add 20mL of deionized water and 8g of color paste, stir evenly to obtain PU mixture, coat the PU mixture onto release paper, control the coating thickness at 0.14mm, control the machine speed at 12m / min, and then use stepped heating to dry the coating. The temperatures are 90℃, 100℃, 110℃, 120℃, 130℃ and 135℃ respectively, with a total drying time of 4min. Each temperature is set for the same time period to obtain the PU surface layer.
[0034] Step 2: Prepare the PU surface layer adhering to the PU foam layer. Adhesive is rolled onto the PU surface, and then the PU foam layer is bonded to it. The PU surface is dried by step heating, with the temperatures set at 100℃, 110℃, and 125℃ respectively, for a total drying time of 15 minutes. The same time period is set for each temperature to obtain the PU surface layer bonded to the PU foam layer.
[0035] Step 3: Preparation of self-healing PU material Adhesive is rolled onto the PU surface, and then non-woven fabric is stacked on top. The material is then heated and dried in a stepped manner at temperatures of 135℃, 140℃, and 145℃, with a drying time of 12 minutes for each temperature. The material is then rolled up after drying to obtain a self-healing PU material.
[0036] Example 5 This embodiment provides a method for preparing a self-healing PU material, including the following steps: Step 1: Prepare the PU surface layer Weigh 100g of PU resin, add 22mL of deionized water and 10g of color paste, stir evenly to obtain PU mixture, coat the PU mixture onto release paper, control the coating thickness at 0.15mm, control the machine speed at 15m / min, and then use stepped heating to dry the coating. The temperatures are 90℃, 100℃, 110℃, 120℃, 130℃ and 135℃ respectively, with a total drying time of 4min. Each temperature is set for the same time period to obtain the PU surface layer.
[0037] Step 2: Prepare the PU surface layer adhering to the PU foam layer. Adhesive is rolled onto the PU surface, and then the PU foam layer is bonded to it. The PU surface is dried by step heating, with the temperatures set at 100℃, 110℃, and 125℃ respectively, for a total drying time of 15 minutes. The same time period is set for each temperature to obtain the PU surface layer bonded to the PU foam layer.
[0038] Step 3: Preparation of self-healing PU material Adhesive is rolled onto the PU surface, and then non-woven fabric is stacked on top. The material is then heated and dried in a stepped manner at temperatures of 135℃, 140℃, and 145℃, with a drying time of 12 minutes for each temperature. The material is then rolled up after drying to obtain a self-healing PU material.
[0039] Example 6 This embodiment provides a method for preparing a self-healing PU material, including the following steps: Step 1: Prepare the PU surface layer Weigh 100g of PU resin, add 25mL of deionized water and 12g of color paste, stir evenly to obtain PU mixture, coat the PU mixture onto release paper, control the coating thickness at 0.16mm, control the machine speed at 18m / min, and then use stepped heating to dry, with temperatures successively at 90℃, 100℃, 110℃, 120℃, 130℃, and 135℃, and a total drying time of 4min. Set the same time period for each temperature to obtain the PU surface layer.
[0040] Step 2: Prepare the PU surface layer adhering to the PU foam layer. Adhesive is rolled onto the PU surface, and then the PU foam layer is bonded to it. The PU surface is dried by step heating, with the temperatures set at 100℃, 110℃, and 125℃ respectively, for a total drying time of 15 minutes. The same time period is set for each temperature to obtain the PU surface layer bonded to the PU foam layer.
[0041] Step 3: Preparation of self-healing PU material Adhesive is rolled onto the PU surface, and then non-woven fabric is stacked on top. The material is then heated and dried in a stepped manner at temperatures of 135℃, 140℃, and 145℃, with a drying time of 12 minutes for each temperature. The material is then rolled up after drying to obtain a self-healing PU material.
[0042] Comparative Example 1 The difference between this comparative example and Example 6 is that step I is omitted, and core-shell self-healing microspheres are not added in step III.
[0043] Comparative Example 1 The difference between this comparative example and Example 6 is that step II is omitted, and reinforcing carbon nanotubes are not added in step III.
[0044] Performance testing: The tensile strength of the self-healing PU materials prepared in Examples 4-6 and Comparative Examples 1-2 was determined in accordance with the standard GB / T 6344-2008 "Determination of tensile strength and elongation at break of flexible foam polymer materials". The tear strength of the self-healing PU materials prepared in Examples 4-6 and Comparative Examples 1-2 was determined according to the standard GB / T 10808-2006 "Determination of tear strength of porous polymer elastic materials". Make a 1mm deep and 100mm long scratch on the test PU material with a blade, and then let it stand for a period of time under light or high temperature (40℃) conditions. Repeat the above tensile strength and tear strength tests. The specific test results are shown in Table 1 below: Table 1 - Performance Test Data of Samples
[0045] Data Analysis: Comparative analysis of the data in Table 1 above shows that the self-healing PU material prepared by this invention has an initial tensile strength of 2.59 MPa and a tear strength of 331 N / m. After scratch testing and repair under light / heat, the scratch surface shows no obvious traces, and the recovered tensile strength is 2.20 MPa and the tear strength is 284 N / m. Comparative Example 1, lacking core-shell self-healing microspheres in its formulation and only incorporating reinforced carbon nanotubes, lacked a core-shell structure capable of releasing polyetheramine active components. Consequently, it could not chemically self-heal after scratches occurred, relying solely on the weak physical rebound of the PU matrix. Comparative Example 1 initially exhibited a tensile strength of 1.68 MPa and a tear strength of 274 N / m. Although it retained some basic mechanical properties thanks to the reinforced carbon nanotubes, it could not achieve self-healing after damage, and the damage remained permanent. After repair, the tensile strength only decreased to 0.76 MPa and the tear strength to 158 N / m, showing a significant reduction in mechanical properties, far below the strength retention level after repair in the embodiments of this invention. This fully demonstrates that core-shell self-healing microspheres are the core key to endowing materials with self-healing capabilities and maintaining post-repair mechanical properties. Comparative Example 2, lacking reinforced carbon nanotubes in its formulation and only incorporating core-shell self-healing microspheres, lacked the interlaced reinforcing network constructed by modified carbon nanotubes. Consequently, it failed to provide support, force transmission, and deformation resistance to the PU foam layer's molecular chains and pore structure. Comparative Example 2 exhibited an initial tensile strength of only 1.12 MPa and a tear strength of only 183 N / m, significantly lower than the examples. Although the core-shell microspheres enabled scratch repair under light and heating conditions, the low base strength of the matrix resulted in a post-repair tensile strength of only 0.89 MPa and a tear strength of only 134 N / m. Furthermore, slight marks remained on the repaired surface, demonstrating a synergistic effect between the reinforced carbon nanotubes and the core-shell microspheres. The absence of carbon nanotubes simultaneously reduced both the material's initial strength and post-repair mechanical performance. The above description is merely an example and illustration of the structure of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the structure of the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.
[0046] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.
[0047] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to specific implementations. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.
Claims
1. A self-healing PU material, characterized in that, It includes, from bottom to top, a base fabric layer, a PU foam layer adhered to the base fabric layer, a PU surface layer adhered to the PU foam layer, and a coating layer applied to the PU surface layer; The PU foam layer is prepared by foaming core-shell self-healing microspheres and reinforced carbon nanotube-doped polytetrahydrofuran ether diol with 4,4-diisocyanate dicyclohexylmethane after catalytic polymerization.
2. The self-healing PU material according to claim 1, characterized in that, The preparation method of the PU foam layer is as follows: Under a nitrogen atmosphere, core-shell self-healing microspheres and reinforced carbon nanotubes are added to a reactor containing N,N-dimethylacetamide. After stirring for 40-60 minutes, polytetrahydrofuran ether diol and 4,4-diisocyanate dicyclohexylmethane are added. The mixture is heated to 60-70°C and stirred for 1-2 hours. Then, dibutyltin dilaurate is added and stirred at 60-70°C for 20-30 minutes. Finally, deionized water and polyether silicone oil are added and stirred at 1500-2000 r / min until the material turns milky white. The mixture is then poured into a mold at 40-50°C and foamed for 5-8 minutes. After foaming, the mixture is allowed to stand for 3-4 hours before demolding. Finally, it is transferred to a drying oven at 80-90°C for 6-8 hours to obtain the PU foam layer.
3. The self-healing PU material according to claim 2, characterized in that, The ratio of the core-shell self-healing microspheres, reinforced carbon nanotubes, N,N-dimethylacetamide, polytetrahydrofuran ether diol, dibutyltin dilaurate, deionized water, and polyether silicone oil is 2.0-3.0g:1.0-1.5g:80-100mL:45g:0.4g:2.5-3.5mL:0.4-0.6g. The amount of 4,4-diisocyanate dicyclohexylmethane added is 0.52 times the total molar amount of the heavy hydroxyl groups of polytetrahydrofuran ether diol.
4. The self-healing PU material according to claim 1, characterized in that, The preparation method of the core-shell self-healing functional microspheres is as follows: polyetheramine and polymethyl methacrylate are added to a reaction vessel containing dichloromethane and stirred for 10-20 min. Then, a mixed solution is added and stirred at 20-30℃ and 2000-3000 r / min for 20-30 min. Next, an aqueous solution of polyvinyl alcohol is added and stirred at 40-50℃ and 1000-1500 r / min for 3-4 h. After naturally cooling to room temperature, the product is centrifuged and collected. The product is washed 2-3 times with deionized water and then transferred to a drying oven and dried at 40-50℃ to obtain the core-shell self-healing functional microspheres.
5. The self-healing PU material according to claim 4, characterized in that, The ratio of polyetheramine, polymethyl methacrylate, dichloromethane, the mixed solution, and the polyvinyl alcohol aqueous solution is 4g:2g:20-28mL:80mL:100mL, and the mass fraction of the polyvinyl alcohol aqueous solution is 1%. The mixed solution is obtained by dissolving 0.72g Tween 80 and 0.48g Span 20 in 80mL of deionized water.
6. The self-healing PU material according to claim 1, characterized in that, The enhanced carbon nanotubes are prepared by the following steps: A1. Carboxylated carbon nanotubes and 1-hydroxyethyl-3-methylimidazolium chloride were added to a reaction vessel containing N,N-dimethylformamide and stirred for 20-30 min. Then, dicyclohexylcarbodiimide and 4-dimethylaminopyridine were added. The temperature was raised to 50-60℃ and reacted for 10-12 h. The temperature was then raised to 100-120℃ and reacted for 20-24 h. After the reaction was completed, the product was separated by centrifugation. The product was washed 2-3 times with anhydrous ethanol and then transferred to a vacuum drying oven and dried at 60℃ to constant weight to obtain pretreated carbon nanotubes. A2. Add β-aminopropionic acid and potassium hydroxide to a reaction vessel containing deionized water. Stir at 60-70℃ for 10-12 hours, then add pretreated carbon nanotubes and continue stirring for 6-8 hours. After the reaction is complete, centrifuge to separate the product. Wash the product with deionized water 2-3 times and place it in a vacuum drying oven to dry at 80℃ to constant weight to obtain reinforced carbon nanotubes.
7. The self-healing PU material according to claim 6, characterized in that, In step A1, the ratio of carboxylated carbon nanotubes, 1-hydroxyethyl-3-methylimidazolium chloride, N,N-dimethylformamide, dicyclohexylcarbodiimide, and 4-dimethylaminopyridine is 1g:2.2-2.5g:35-45mL:0.45-0.55g:0.08-0.12g.
8. The self-healing PU material according to claim 6, characterized in that, In step A2, the ratio of β-aminopropionic acid, potassium hydroxide, deionized water and pretreated carbon nanotubes is 1g:1g:25-35mL:1.8-2.2g.
9. A method for preparing a self-healing PU material according to any one of claims 1-8, characterized in that, The self-healing PU material is prepared by the following steps: S1. Add deionized water and color paste to PU resin and stir evenly to obtain PU mixture. Coat the PU mixture onto release paper with a coating thickness of 0.15±0.01mm and a machine speed of 15±3m / min. After coating, use stepped heating to dry the product at temperatures of 90℃, 100℃, 110℃, 120℃, 130℃, and 135℃, with a total drying time of 4min. Set the same time period for each temperature to obtain the PU surface layer. S2. Apply adhesive to the PU surface layer by roller, then bond the PU foam layer to it, and use a stepped heating and drying method with temperatures of 100℃, 110℃ and 125℃ in sequence, for a total drying time of 15 minutes. Set the same time period for each temperature to obtain the PU surface layer bonded to the PU foam layer. S3. Apply adhesive to the PU surface layer by roller, then stack non-woven fabric on top, and heat and dry in a stepped manner at temperatures of 135℃, 140℃, and 145℃, with a drying time of 12 minutes. Set the same time period for each temperature. After drying, curl the fabric to obtain a self-healing PU material.
10. A method for preparing a self-healing PU material according to claim 9, characterized in that, In step S1, the ratio of PU resin, deionized water and pigment is 100g:20-25mL:8-12g.