A method for preparing a self-healing superhydrophobic hybrid bio-based polyurethane coating

Abstract

The application discloses a preparation method of a self-repairing super-hydrophobic composite bio-based polyurethane coating and relates to a polyurethane coating preparation method, which takes Jatropha curcas oil as raw material, takes alcohol as a ring-opening agent, prepares Jatropha curcas-based polyester polyol, and prepares a self-repairing super-hydrophobic composite bio-based polyurethane by using polytetrahydrofuran as a chain extender. The introduction of the synergistic self-repairing function of the double dynamic network structure enhances the mechanical strength and elasticity of the material. The disulfide bond and hydrogen bond in the polyurethane can be dynamically broken and reconnected, so that the damaged area can be self-repaired without external intervention. The introduction of the super-hydrophobic function can effectively resist the adhesion of water and other liquids on the surface of the material, which not only greatly enhances the resistance of the material to the external environment, but also exhibits excellent protective performance in the initial use stage of the material, which is particularly crucial for maintaining the structural integrity and aesthetic appearance of the material. The self-repairing super-hydrophobic ability greatly prolongs the service life of the material and reduces the maintenance cost.

Description

Technical Field

[0001] This invention relates to a method for preparing a bio-based polyurethane coating, and more particularly to a method for preparing a self-healing superhydrophobic composite bio-based polyurethane coating. Background Technology

[0002] Polyurethane is a multifunctional material widely used in various industrial and consumer products, including foams, coatings, adhesives, and sealants. Traditional polyurethane raw materials are typically derived from non-renewable petroleum resources, which is particularly relevant given the current global emphasis on environmental awareness and sustainable development. Therefore, bio-based polyurethane has attracted widespread attention due to its use of renewable resources as raw materials, becoming a potential alternative to traditional polyurethane. However, despite its excellent eco-friendly properties, bio-based polyurethane still faces some performance limitations in practical applications, such as susceptibility to damage and maintenance difficulties. Currently, high-value-added functionalized bio-based polyurethane holds great promise for further exploration.

[0003] Under various environmental stresses such as ultraviolet radiation, chemical corrosion, or mechanical wear, material surfaces undergo degradation, cracking, or other forms of damage. This damage not only weakens the structural integrity of the material but also affects its functionality. To address these challenges, the development of self-healing capabilities plays a crucial role in materials science, significantly improving material durability and reducing maintenance costs. Typical dynamic covalent bonds in self-healing materials include dynamic disulfide bonds, DA bonds, imine bonds, and borosilicate bonds. Non-covalent bonds with reversible cross-linking mechanisms include hydrogen bonds, van der Waals forces, and metal coordination bonds. Dynamic disulfide bonds can self-repair at room temperature without external energy or catalysts, making the repair process more economical and environmentally friendly. Multiple hydrogen bonds, due to their reversibility and low binding energy, can spontaneously break and reconnect under different environmental conditions. This property allows materials to recover rapidly after damage. The synergistic function of dynamic disulfide bonds and multiple hydrogen bonds enables reversible self-healing at low temperatures, enhancing the material's self-healing ability.

[0004] The design inspiration for biomimetic superhydrophobic surfaces comes from many phenomena in nature, such as the self-cleaning lotus leaf, the waterproof legs of water butterflies, the waterproof wings of butterflies, and the anti-fog eyes of mosquitoes. These natural properties are applied to the development of materials with self-cleaning, anti-icing, anti-corrosion, and antibacterial functions. Wettability describes the ability of water to diffuse on a solid surface and is a key indicator for measuring surface properties. Generally, when the water contact angle θ < 90°, the surface is considered hydrophilic; when the contact angle 90° < θ < 150°, the surface is hydrophobic; and if the contact angle θ > 150°, the surface is defined as a superhydrophobic surface.

[0005] Traditional polyurethane is mainly derived from non-renewable petroleum resources and often cannot recover on its own after being subjected to mechanical damage or chemical corrosion. In addition, its surface hydrophilicity leads to the accumulation of pollutants and the growth of microorganisms, thereby accelerating material degradation and shortening service life. Summary of the Invention

[0006] The present invention aims to provide a method for preparing a self-healing superhydrophobic composite bio-based polyurethane coating. This method constructs a COC ternary oxygen-bridged ring molecule using bio-based jatropha oil, selectively oxidizes the double bonds to epoxy jatropha oil, and converts them into bio-based polyols via ring-opening to achieve internal cross-linking sites within the polymer. A dual dynamic network is constructed within the polymer using dynamic disulfide bonds and reversible quadruple hydrogen bonds. Octadecylamine active amino groups provide hydrogen atoms for chemical bonding with the isocyanate at the polyurethane terminus, thus preparing a self-healing superhydrophobic composite bio-based polyurethane. The prepared polyurethane exhibits excellent mechanical properties, strong low-temperature self-healing performance, and extremely low energy consumption.

[0007] The present invention adopts the following technical solution.

[0008] A method for preparing a self-healing superhydrophobic composite bio-based polyurethane, comprising the following raw materials in parts by weight: 100-150 parts of jatropha oil bio-based polyol, 16-20 parts of polytetrahydrofuran, 10-30 parts of isophorone diisocyanate, 2-6 parts of 2,2-dimethylolpropionic acid, 3-8 parts of N,N-dimethylformamide, 1-2 parts of dibutyltin dilaurate, 2-5 parts of 2,2'-diaminodiphenyl disulfide, 2-5 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil, 1-3 parts of triethylamine, 5-10 parts of octadecylamine, and 5-10 parts of ethyl acetate.

[0009] Specifically, the following steps are included:

[0010] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added, and the mixture was reacted for 3 hours. The mixture was then cooled to 50°C, and 2 parts of 2,2'-diaminodiphenyl disulfide and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added, and the reaction was continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, 5 parts of octadecylamine were added, and the reaction was continued for 2 hours to finally obtain the polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was then sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After curing at room temperature for 48 hours, a bio-based polyurethane with self-healing and superhydrophobic functions was obtained.

[0011] Further, the preparation steps of the jatropha oil bio-based polyol are as follows: 100 parts of jatropha oil and 5 parts of formic acid are mixed and reacted at 40°C for 10 min, then 8 parts of hydrogen peroxide are added and reacted for 30 min. The temperature is then raised to 60°C and the reaction continues for 5 h to obtain epoxidized jatropha oil. 4-6 parts of ring-opening agent, 10-15 parts of water, and 5-8 parts of sulfuric acid catalyst are poured into a beaker and continuously stirred and heated to the boiling point of the ring-opening agent. Then, the epoxidized jatropha oil is added to the mixture, and the reaction continues for 30 min. Then, 3-5 parts of sodium bicarbonate are added to cool the reaction. After cooling to room temperature, the precipitate is discarded. Excess ring-opening agent and water are removed by vacuum distillation to obtain the jatropha oil bio-based polyol.

[0012] Furthermore, the ring-opening agent is an alcohol compound containing a hydroxyl group, such as methanol, ethanol, or propanol.

[0013] Furthermore, the stirring speed of the magnetic stirrer is 500~600 r / min. The emulsification speed of the polyurethane prepolymer is 10000~12000 r / min.

[0014] Furthermore, the ring-opening condition for epoxidized jatropha oil is to reach the boiling point of the ring-opening agent.

[0015] The beneficial effects of this invention are as follows:

[0016] 1. Replacing petroleum-based polyols with jatropha-based polyester polyols as the soft segments of polyurethane reduces dependence on non-renewable resources, improves environmental friendliness, and achieves a green upgrade of polyurethane materials.

[0017] 2. Using 2,2'-diaminodiphenyl disulfide containing dynamic disulfide bonds and 5-(2-hydroxyethyl)-6-methyl-2-aminouracil dimer containing quadruple hydrogen bonds as chain extenders, a dual dynamic network is formed inside the polyurethane prepolymer by relying on the physical crosslinking of the quadruple hydrogen bonds and the covalent crosslinking of the disulfide bonds of the dimer. The formation of the dual dynamic network enables the polyurethane to have reversible self-healing under low temperature requirements, thereby enhancing the self-healing ability of the material.

[0018] 3. Using octadecylamine, which has a low surface energy and a long carbon chain, as a hydrophobic end-capping agent, the amino group provides hydrogen atoms and utilizes the bonding between the amino group and the isocyanate at the end of the polyurethane to introduce a low surface energy long carbon chain structure, giving the material excellent superhydrophobic properties, effectively resisting liquid adhesion, and significantly enhancing the durability and protective ability of polyurethane in various environments. Detailed Implementation Example 1

[0019] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added, and the mixture was reacted for 3 hours. The mixture was then cooled to 50°C, and 2 parts of 2,2'-diaminodiphenyl disulfide and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added, and the reaction was continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, 5 parts of octadecylamine were added, and the reaction was continued for 2 hours to finally obtain the polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was then sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After standing and curing at room temperature for 48 hours, a bio-based polyurethane coating with self-healing and superhydrophobic functions was obtained. Example 2

[0020] 120 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added, and the mixture was reacted for 3 hours. The mixture was then cooled to 50°C, and 2 parts of 2,2'-diaminodiphenyl disulfide and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added, and the reaction was continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, 5 parts of octadecylamine were added, and the reaction was continued for 2 hours, finally yielding a polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was then sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After standing and curing at room temperature for 48 hours, a bio-based polyurethane coating with self-healing and superhydrophobic functions was obtained. Example 3

[0021] 150 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added. The mixture was reacted for 3 hours. The mixture was then cooled to 50°C, and 2 parts of 2,2'-diaminodiphenyl disulfide and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added. The reaction was continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, 5 parts of octadecylamine were added, and the reaction was continued for 2 hours to finally obtain the polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was then sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After standing and curing at room temperature for 48 hours, a bio-based polyurethane coating with self-healing and superhydrophobic functions was obtained.

[0022] Comparative Example 1

[0023] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added. The mixture was reacted for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, 5 parts of octadecylamine were added, and the reaction was continued for 2 hours to obtain a polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After curing at room temperature for 48 hours, a bio-based polyurethane coating with high hydrophobicity was obtained.

[0024] Comparative Example 2

[0025] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added. The mixture was reacted for 3 hours. The mixture was then cooled to 50°C, and 2 parts of 2,2'-diaminodiphenyl disulfide and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added. The reaction was continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, the polyurethane prepolymer was finally obtained. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was then sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After standing and curing at room temperature for 48 hours, a bio-based polyurethane coating with self-healing function was obtained.

[0026] Comparative Example 3

[0027] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added. The mixture was reacted for 3 hours. The mixture was cooled to 50°C, and 2 parts of 2,2'-diaminodiphenyl disulfide were added, and the reaction continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, a polyurethane prepolymer was finally obtained. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After curing at room temperature for 48 hours, a self-healing bio-based polyurethane coating was obtained.

[0028] Comparative Example 4

[0029] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added. The mixture was reacted for 3 hours. The mixture was cooled to 50°C, and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added. The reaction was continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, a polyurethane prepolymer was finally obtained. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After curing at room temperature for 48 hours, a self-healing bio-based polyurethane coating was obtained.

[0030] Comparative Example 5

[0031] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added. The mixture was reacted for 3 hours. The mixture was then cooled to 50°C, and 2 parts of 2,2'-diaminodiphenyl disulfide were added, and the reaction continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, 5 parts of octadecylamine were added, and the reaction continued for 2 hours to obtain the final polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was then sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After curing at room temperature for 48 hours, a bio-based polyurethane coating with self-healing and high hydrophobicity was obtained.

[0032] Comparative Example 6

[0033] 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed. The mixture was stirred and dispersed in a water bath using a magnetic stirrer for 10 minutes. Then, the temperature was raised to 80°C, and under nitrogen protection, 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added. The mixture was reacted for 3 hours. The mixture was then cooled to 50°C, and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added. The reaction was continued for 3 hours. The temperature was further lowered to 40°C, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 minutes, 5 parts of octadecylamine were added, and the reaction was continued for 2 hours to obtain the final polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 hour. The emulsified polyurethane was then sprayed onto a steel sheet using a spray gun at a pressure of 1.5 atm. After curing at room temperature for 48 hours, a bio-based polyurethane coating with self-healing and high hydrophobicity was obtained.

[0034] Performance testing

[0035] Test 1: Self-healing performance test

[0036] Scratches were made on the surface of the coating with a blade, and the surface was left to heal at room temperature for 24 hours. The surface of the sample was then observed under an optical microscope to see if it had healed.

[0037] Test 2: Contact Angle Test

[0038] Static water contact angle (WCA) tests were conducted on the three sets of examples and six sets of comparative examples. Approximately 5 μl of water droplets were placed on the polyurethane coating surface, and the angle was observed. When WCA ≥ 150°, the surface wetting state reached superhydrophobicity.

[0039] Test 3: Abrasion Resistance Test

[0040] Using sandpaper (1200 mesh) as the abrasive surface and a superhydrophobic surface as the abrasive surface, the sample was pulled at a speed of 3 cm / s under a pressure of 12.5 kPa, with a test distance of 15 cm. This experiment was repeated 20 times, and the surface contact angle was measured after the test.

[0041] Table 1 Performance test results of the examples and comparative examples

[0042] Contact angle Contact angle after friction Can the scratches be repaired? Scratch repair level Example 1 157.6 154.7 able powerful Example 2 155.1 153.4 able powerful Example 3 153.3 152.2 able powerful Comparative Example 1 134.8 122.5 no none Comparative Example 2 101.9 100.4 able powerful Comparative Example 3 87.6 84.8 able weak Comparative Example 4 89.2 73.9 able weak Comparative Example 5 137.3 130.2 able weak Comparative Example 6 138.7 127.1 able middle .

Claims

1. A method for preparing a self-healing superhydrophobic composite bio-based polyurethane coating, characterized in that, The method includes the following preparation steps: 100 parts of jatropha oil bio-based polyol, 16 parts of polytetrahydrofuran, 2 parts of 2,2-dimethylolpropionic acid, and 3 parts of N,N-dimethylformamide were mixed and dispersed in a water bath using a magnetic stirrer for 10 min. Then, the temperature was raised to 80℃, and 10 parts of isophorone diisocyanate and 1 part of dibutyltin dilaurate were slowly added under nitrogen protection. The mixture was reacted for 3 h. The mixture was cooled to 50℃, and 2 parts of 2,2'-diaminodiphenyl disulfide and 2 parts of 5-(2-hydroxyethyl)-6-methyl-2-aminouracil were added. The reaction was continued for 3 h. The temperature was further lowered to 40℃, and 1 part of triethylamine was added to neutralize the system. After reacting for 30 min, 5 parts of octadecylamine were added, and the reaction was continued for 2 h to finally obtain a polyurethane prepolymer. The prepolymer was dispersed in 5 parts of ethyl acetate and emulsified for 1 h to obtain a bio-based polyurethane with self-healing and superhydrophobic functions.

2. The method for preparing a self-healing superhydrophobic composite bio-based polyurethane coating according to claim 1, characterized in that, The steps for preparing the jatropha oil bio-based polyol are as follows: 100 parts of jatropha oil and 5 parts of formic acid are mixed and reacted at 40°C for 10 minutes, 8 parts of hydrogen peroxide are added and reacted for 30 minutes, and the temperature is raised to 60°C and the reaction continues for 5 hours to obtain epoxidized jatropha oil; 4-6 parts of ring-opening agent, 10-15 parts of water and 5-8 parts of sulfuric acid catalyst are poured into a beaker and continuously stirred and heated to the boiling point of the ring-opening agent; then the epoxidized jatropha oil is added to the mixture and the reaction continues for 30 minutes, and then 3-5 parts of sodium bicarbonate are added to cool the reaction; after cooling to room temperature, the sediment is discarded; excess ring-opening agent and water are removed by vacuum distillation to obtain the jatropha oil bio-based polyol.

3. The method for preparing a self-healing superhydrophobic composite bio-based polyurethane coating according to claim 2, characterized in that, The ring-opening agent is an alcohol compound containing a hydroxyl group.

4. The method for preparing a self-healing superhydrophobic composite bio-based polyurethane coating according to claim 1, characterized in that, The stirring speed of the magnetic stirrer is 500~600 r / min; the emulsification speed of the polyurethane prepolymer is 10000~12000 r / min.