Polyurethane of bio-based polyether polyol and preparation method thereof

Abstract

The invention relates to polyurethane of bio-based polyether polyol and a preparation method thereof, and the polyurethane of bio-based polyether polyol is prepared from the following components in parts by weight: 20 to 30 parts of coconut shell-based polyol, 10 to 20 parts of glycerol, 10 to 20 parts of polybasic acid, 2 to 4 parts of antioxidant, 5 to 8 parts of boron trifluoride ether compound, 5 to 10 parts of isocyanate and 60 to 80 parts of deionized water. Excellent physical and chemical properties and environment-friendly characteristics are realized. The polyurethane not only has excellent wear resistance, strength, low thermal conductivity and acid and alkali resistance, but also has good biocompatibility and degradability, and is widely applicable to the fields of buildings, coatings, furniture, packaging and the like. The invention provides a feasible technical route for the development of high-performance and low-environmental-influence polymer materials, and is helpful for promoting the cyclic utilization and sustainable development of wastes.

Description

Technical Field

[0001] The invention provides a polyurethane of a bio-based polyether polyol and a preparation method thereof, belonging to the technical field of material science and engineering. Background Art

[0002] With the increasing global attention to sustainable development and environmental protection, the research and development of bio-based materials has become an important research direction in the field of materials science and engineering. Polyurethane, as the most widely used type of modern polymer materials, covers a variety of forms such as insulating materials, coatings, elastomers, foams and adhesives, and is widely used in construction, automobiles, homes and electronic products. This makes it play a key role in modern industry and daily life. However, the production of traditional polyurethane materials mainly relies on petroleum-based chemical raw materials, which not only leads to resource depletion problems, but also causes serious environmental pollution. It can be seen that the development of bio-based polyurethane based on renewable resources has important economic and environmental significance.

[0003] Bio-based polyurethane uses renewable resources as raw materials and shows significant ecological and economic advantages. First, by using renewable resources, bio-based polyurethane effectively reduces dependence on fossil fuels, thereby reducing greenhouse gas emissions and the environmental burden of the entire production process. Secondly, this type of material usually has good biocompatibility and degradability, making its application prospects in medical, packaging and other fields more extensive.

[0004] Coconut shells are an abundant agricultural waste, the main components of which are cellulose, hemicellulose and lignin. Studies have shown that by properly chemically treating coconut shells, their cellulose content can be significantly increased, providing high-quality raw materials for the preparation of bio-based polyether polyols. For example, using sodium hydroxide to treat coconut shells can effectively remove lignin, thereby improving the purity of cellulose. This not only contributes to the recycling of resources and the improvement of economic benefits, but also reduces the environmental burden. More importantly, using bio-based materials, such as cellulose, as a synthetic raw material for polyurethane can enable the product to inherit some of the excellent properties of cellulose, such as thermal insulation, acid and alkali resistance, etc., giving polyurethane more functions to adapt to more application scenarios.

[0005] In the synthesis process of polyurethane, the reaction between isocyanate and polyol is a core link. Different types of isocyanate have a significant impact on the physical and chemical properties of the final polyurethane. In addition, the selection of catalysts is also an important factor in ensuring reaction efficiency and product quality. For example, boron trifluoride ether compounds can effectively increase the reaction rate and improve the overall performance of polyurethane due to their characteristics as Lewis acids. At the same time, the addition of antioxidants can enhance the antioxidant capacity of polyurethane during long-term use, thereby ensuring the stability and durability of the material.

[0006] Polyurethanes based on bio-based polyether polyols show broad market prospects in the fields of green buildings, environmentally friendly coatings and biodegradable packaging. However, there are still some challenges in developing bio-based polyurethanes with excellent performance and economic feasibility. First, how to optimize the reaction conditions to improve the final performance of polyurethane is an important issue; second, the price and availability of bio-based raw materials must also be guaranteed to maintain their competitiveness with traditional petroleum-based materials. Therefore, researchers need to further explore new bio-based raw materials and their preparation processes to achieve the industrial production of high-performance, biodegradable polyurethane materials.

[0007] In summary, polyurethanes based on bio-based polyether polyols conform to the development trend of the times, meet the requirements of environmental protection and sustainable development, and open up a broad vision for the development and application of new materials. Through in-depth research and innovation, more high-performance, low-environmental-impact new polyurethane materials are expected to be introduced in the future, promoting the combination of the development of materials science and environmental protection. Summary of the invention

[0008] The invention provides a polyurethane of a bio-based polyether polyol and a preparation method thereof, aiming to prepare polyurethane with excellent performance by utilizing renewable resources and environmentally friendly materials to meet the growing demand for green materials.

[0009] To achieve the purpose of the invention, the technical solution adopted by the present invention is: a polyurethane of a bio-based polyether polyol, wherein the composition of the polyurethane of the bio-based polyether polyol is, by weight, 20-30 parts of coconut shell polyol, 10-20 parts of glycerol, 10-20 parts of polyacid, 2-4 parts of antioxidant, 5-8 parts of boron trifluoride ether compound, 5-10 parts of isocyanate, and 60-80 parts of deionized water; the preparation method of the coconut shell polyol comprises the following steps: S1 washes the collected fresh coconut shells to remove impurities and dirt on the surface, and uses a drying device to dry the washed coconut shells at a temperature of 60-80°C for about 12-24 hours until the moisture content of the coconut shells is 2-10%; uses a crusher to crush the dried coconut shells, and the particle size after crushing should be controlled at 1-5mm; uses a sieve with a mesh number of 40-80 to screen after crushing, and crushes the particles that do not reach the target particle size again; S2: Soak the pretreated coconut shell in a sodium hydroxide solution with a concentration of 5-12wt%, and the mass volume ratio of coconut shell to sodium hydroxide is set to 1:3-5 g / mL; stir and react at a speed of 500-100 rpm at a temperature of 80-100°C for 1-3 hours, so as to effectively remove lignin and increase the cellulose content of the coconut shell. After the reaction is completed, filter and separate the filtrate and residue; soak the residue in a hydrogen peroxide solution with a concentration of 3-10wt%, and the mass volume ratio of the residue to hydrogen peroxide is set to 5:1-5 g / mL, adjust the pH value of the mixed solution to 10-12, react for 2-5 hours, until the residue becomes nearly white, filter and remove the filtrate, and obtain coconut shell fiber with a high cellulose content; S3: placing coconut shell fiber in a 1-N-allyl-2,3-dimethylimidazolium chloride solution, wherein the amount of 1-N-allyl-2,3-dimethylimidazolium chloride solution added is 10 to 20 times the mass of the coconut shell fiber, heating the mixture at 80 to 90°C, and stirring at a speed of 500 to 100 rpm for 2 to 4 hours until the coconut shell is completely dissolved to form a transparent solution; after completion, using a centrifuge to separate the coconut shell solution from the 1-N-allyl-2,3-dimethylimidazolium chloride solution to remove undissolved residues, and subjecting the obtained coconut shell solution to ultrasonic treatment in an ultrasonic treatment device at a frequency of 20 to 30 kHz, a power of 800 to 1000 W, and a treatment time of 30 to 40 minutes. After the treatment is completed, cooling is performed, and the ionic liquid and water are removed by freeze drying to obtain coconut shell-based nanocellulose; S4 dissolves the obtained coconut shell-based nanocellulose in dichloromethane to ensure that the nanocellulose is fully dispersed, and stirs at 100-200 rpm for 20-40 minutes at 50-60°C to completely dissolve it; adds polyols and catalysts to the solution, and stirs at 100-200 rpm for 30-60 minutes to fully mix it; reacts the mixture at 50-80°C for 3-6 hours. After the reaction is completed, stop heating and wait for the solution to cool to room temperature; transfers the reaction mixture to a precipitation separation device, and uses anhydrous ethanol to induce the precipitation of the modified nanocellulose; repeatedly washes the precipitate with deionized water to remove unreacted polyols and catalysts; after washing, dries in an oven with a set temperature of 50-60°C until constant weight is reached, ensuring complete removal of moisture and solvent to obtain coconut shell-based polyols.

[0010] According to a polyurethane of a bio-based polyether polyol, the polyol described in S4 is a combination of one or more of ethylene glycol, propylene glycol, and glycerol.

[0011] According to a polyurethane of a bio-based polyether polyol, the catalyst in S4 is a combination of one or more of triphenylphosphine, triethylamine, and dimethylaminopyridine.

[0012] According to a polyurethane of a bio-based polyether polyol, the boron trifluoride ether compound is one or a combination of boron trifluoride ethyl ether complex and boron trifluoride butyl ether complex.

[0013] According to a polyurethane of a bio-based polyether polyol, the preparation method of 1-N-allyl-2,3-dimethylimidazolium chloride comprises the following process: S1: Add 2,3-dimethylimidazole to the reaction bottle, add allyl chloride under nitrogen protection, and stir the mixture at 100-200 rpm with a magnetic stirrer at 60-80°C for 2-4 hours; S2 After the reaction is completed, the mixture is cooled to room temperature and unreacted reagents and solvents are removed by distillation; the reaction mixture is poured into a separatory funnel, deionized water is added, and washed to remove water-soluble impurities; the obtained precipitate is dissolved in dichloromethane by separation chromatography to remove impurities in the organic layer; finally, the obtained liquid is poured into a dryer, and anhydrous magnesium sulfate desiccant is used to remove excess water to obtain the desired 1-N-allyl-2,3-dimethylimidazole chloride.

[0014] According to a polyurethane of a bio-based polyether polyol, the antioxidant is a combination of one or more of tert-butyl hydroxyanisole, tert-butyl hydroxyphenylene glycol, and N-graphene acid amine.

[0015] According to a polyurethane of a bio-based polyether polyol, the polyacid is a combination of one or more of maleic anhydride and phthalic acid.

[0016] According to a polyurethane of bio-based polyether polyol, the isocyanate is a combination of one or more of methyl isocyanate, polyester isocyanate, diphenylmethane isocyanate and toluene diisocyanate.

[0017] According to a polyurethane of a bio-based polyether polyol, the preparation method comprises the following steps: S1: In a multifunctional reactor, add coconut shell-based polyol, isocyanate, and polyol in order according to the formula weight, and stir the entire mixture at a speed of 200-400 rpm for 1-2 hours under nitrogen protection to make it evenly mixed; use a water bath to heat the mixture, control the temperature of the mixture at 60-80°C, and stir at a speed of 100-200 rpm for 2-4 hours; then add boron trifluoride ether compound and antioxidant, continue to use water bath heating to control the temperature at 90-110°C, react for 1-2 hours to ensure complete reaction and enhance the chemical stability of polyurethane; finally, add polyacid and react at a temperature of 110-130°C for 1-2 hours to promote cross-linking reaction and enhance the mechanical properties of the material; S2: The reaction mixture is naturally cooled to room temperature under nitrogen protection, and centrifuged at 3000-6000 rpm for 10-20 minutes using a high-speed centrifuge; after centrifugation, the precipitate is washed 2-3 times with deionized water to ensure that the residual additives are completely removed; and then the finished product is dried in a vacuum drying oven at a temperature of 40-50°C to ensure the stability and color of the polyurethane, thereby obtaining the desired bio-based polyether polyol polyurethane. Compared with the prior art, the present invention has the following advantages:

[0018] (1) Environmentally friendly: Using renewable resources as raw materials reduces dependence on petroleum-based chemical raw materials, thereby reducing environmental impact and greenhouse gas emissions during the production process.

[0019] (2) Excellent performance: By optimizing the raw material composition and synthesis process, the polyurethane of the present invention has excellent physical and chemical properties, showing excellent wear resistance, strength, low thermal conductivity and acid and alkali resistance, and can meet a variety of application requirements.

[0020] (3) Biocompatibility and degradability: This polyurethane material performs well in terms of biocompatibility and degradability, and is suitable for use in a variety of fields with high environmental protection requirements.

[0021] (4) Economic efficiency: Using agricultural waste as raw materials reduces the cost of raw materials. At the same time, through subsequent utilization, it can achieve resource recycling and improve economic benefits.

[0022] (5) Simple and operable preparation process: The polyurethane preparation method provided by the present invention is simple and easy to operate, suitable for large-scale industrial production, and has good market application potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 From left to right are scanning electron microscope images of coconut shell-based nanocellulose prepared in Examples 4, 5 and 6 respectively. DETAILED DESCRIPTION Embodiment 1

[0024] 2,3-Dimethylimidazole was added to a reaction bottle, and allyl chloride was added under nitrogen protection. The mixture was stirred at 100 rpm for 2 hours at 60°C using a magnetic stirrer. After the reaction was completed, the mixture was cooled to room temperature, and unreacted reagents and solvents were removed by distillation. The reaction mixture was poured into a separatory funnel, deionized water was added, and the mixture was washed to remove water-soluble impurities. The obtained precipitate was dissolved in dichloromethane by separation chromatography to remove impurities in the organic layer. Finally, the obtained liquid was poured into a dryer, and anhydrous magnesium sulfate desiccant was used to remove excess water to obtain the desired 1-N-allyl-2,3-dimethylimidazole chloride. Embodiment 2

[0025] 2,3-dimethylimidazole was added to a reaction bottle, and allyl chloride was added under nitrogen protection. The mixture was stirred at 150 rpm for 3 hours at 70°C using a magnetic stirrer. After the reaction, the mixture was cooled to room temperature, and unreacted reagents and solvents were removed by distillation. The reaction mixture was poured into a separatory funnel, deionized water was added, and the mixture was washed to remove water-soluble impurities. The obtained precipitate was dissolved in dichloromethane by separation chromatography to remove impurities in the organic layer. Finally, the obtained liquid was poured into a dryer, and anhydrous magnesium sulfate desiccant was used to remove excess water to obtain the desired 1-N-allyl-2,3-dimethylimidazole chloride. Embodiment 3

[0026] 2,3-Dimethylimidazole was added to a reaction bottle, and allyl chloride was added under nitrogen protection. The mixture was stirred at 200 rpm for 4 hours at 80°C using a magnetic stirrer. After the reaction was completed, the mixture was cooled to room temperature, and unreacted reagents and solvents were removed by distillation. The reaction mixture was poured into a separatory funnel, deionized water was added, and washed to remove water-soluble impurities. The obtained precipitate was dissolved in dichloromethane by separation chromatography to remove impurities in the organic layer. Finally, the obtained liquid was poured into a dryer, and anhydrous magnesium sulfate desiccant was used to remove excess water to obtain the desired 1-N-allyl-2,3-dimethylimidazole chloride. Embodiment 4

[0027] The collected fresh coconut shells were washed to remove impurities and dirt on the surface, and the washed coconut shells were dried using a drying equipment at a temperature of 60°C for about 12 hours until the moisture content of the coconut shells was 2%; the dried coconut shells were crushed using a crusher, and the particle size after crushing should be controlled at 1 mm; after crushing, a sieve with a mesh size of 40 was used for screening, and particles that did not reach the target particle size were crushed again; the pretreated coconut shells were soaked in a 5wt% sodium hydroxide solution, and the mass volume ratio of coconut shells to sodium hydroxide was set to 1:3g / mL; the reaction was stirred at a speed of 500rpm for 1 hour at a temperature of 80°C, thereby effectively removing lignin and increasing the cellulose content of the coconut shells. After the reaction, the filtrate and the residue were separated; the residue was soaked in a 3wt% hydrogen peroxide solution, and the mass volume ratio of the residue to hydrogen peroxide was set to 5:1g / mL, and the pH value of the mixed solution was adjusted to 10, react for 2 hours until the filter residue becomes nearly white, filter and remove the filtrate to obtain coconut shell fiber with high cellulose content; place the coconut shell fiber in the 1-N-allyl-2,3-dimethylimidazolium chloride solution prepared in Example 1, the addition amount of 1-N-allyl-2,3-dimethylimidazolium chloride solution is 10 times the mass of the coconut shell fiber, heat the mixture at 80°C, and stir at a speed of 500 rpm for 2 hours until the coconut shell is completely dissolved to form a transparent solution; after completion, use a centrifuge to separate the coconut shell solution from the 1-N-allyl-2,3-dimethylimidazolium chloride solution to remove undissolved residues, and perform ultrasonic treatment on the obtained coconut shell solution in an ultrasonic treatment equipment at a frequency of 20 kHz, a power of 800 W, and a treatment time of 30 minutes. After the treatment is completed, cool it, remove the ionic liquid and water by freeze drying, and obtain coconut shell-based nanocellulose, which is characterized by scanning electron microscopy, such as Figure 1 As shown, the diameter is about 16~22 nm and the length is about 320~2400 nm.

[0028] The obtained coconut shell-based nanocellulose was tested for carboxyl content. The test method was as follows: The total carboxyl content in the prepared coconut shell-based nanocellulose was determined by alkaline hydrolysis and reverse titration, that is, 0.5 g of sample was added to 40 ml (70%) ethanol solution, and the resulting suspension was stirred continuously for 30 minutes. Then 20 ml (0.5 M) NaOH solution was added to the suspension and hydrolyzed at 60 ° C for 48 hours. Phenolphthalein was used as an indicator to titrate the unconsumed NaOH after hydrolysis with HCl (0.5 M) solution.

[0029]

[0030] In the formula is the volume of NaOH, The volume of HCl consumed in the titration is is the concentration of HCl, m is the dry weight of coconut shell-based nanocellulose, and the results show that the total carboxyl content of coconut shell-based nanocellulose is 0.32 mmol g -1 .

[0031] The obtained coconut shell-based nanocellulose was dissolved in dichloromethane to ensure that the nanocellulose was fully dispersed, and stirred at 50°C at a speed of 100 rpm for 20 minutes to completely dissolve it; ethylene glycol and triphenylphosphine were added to the solution, and stirred at a speed of 100 rpm for 30 minutes to fully mix it; the mixture was reacted at 50°C for 3 hours. After the reaction was completed, the heating was stopped and the solution was cooled to room temperature; the reaction mixture was transferred to a precipitation separation device, and anhydrous ethanol was used to induce the precipitation of the modified nanocellulose; the precipitate was repeatedly washed with deionized water to remove unreacted ethylene glycol and triphenylphosphine; after washing, it was dried in an oven with a set temperature of 50°C until constant weight was reached to ensure that water and solvent were completely removed to obtain coconut shell-based polyol, and the obtained coconut shell-based polyol was tested for carboxyl content according to formula (1), and the result was 0.15 mmol g -1 <0.32 mmol g -1 (Carboxyl content of coconut shell-based nanocellulose), which shows that surface ethylene glycol was successfully grafted onto the molecular chain of coconut shell-based nanocellulose. Embodiment 5

[0032] The collected fresh coconut shells were washed to remove impurities and dirt on the surface, and the washed coconut shells were dried using a drying equipment at a temperature of 70°C for about 18 hours until the moisture content of the coconut shells was 6%; the dried coconut shells were crushed using a crusher, and the particle size after crushing should be controlled at 3mm; after crushing, a 60-mesh sieve was used for screening, and particles that did not reach the target particle size were crushed again; the pretreated coconut shells were soaked in a sodium hydroxide solution with a concentration of 8wt%, and the mass volume ratio of coconut shells to sodium hydroxide was set to 1:4g / mL; the reaction was stirred at a speed of 750rpm for 2 hours at a temperature of 90°C, thereby effectively removing lignin and increasing the cellulose content of the coconut shells. After the reaction, the filtrate and the residue were separated; the residue was soaked in a hydrogen peroxide solution with a concentration of 6wt%, and the mass volume ratio of the residue to hydrogen peroxide was set to 5:3g / mL, and the pH value of the mixed solution was adjusted to 11, react for 3 hours until the filter residue becomes nearly white, filter and remove the filtrate to obtain coconut shell fiber with high cellulose content; place the coconut shell fiber in the 1-N-allyl-2,3-dimethylimidazolium chloride solution prepared in Example 2, the addition amount of 1-N-allyl-2,3-dimethylimidazolium chloride solution is 15 times the mass of the coconut shell fiber, heat the mixture at 85°C, and stir at a speed of 750rpm for 3 hours until the coconut shell is completely dissolved to form a transparent solution; after completion, use a centrifuge to separate the coconut shell solution from the 1-N-allyl-2,3-dimethylimidazolium chloride solution to remove undissolved residues, and perform ultrasonic treatment on the obtained coconut shell solution in an ultrasonic treatment equipment at a frequency of 25kHz, a power of 900W, and a treatment time of 35 minutes. After the treatment is completed, cool it, and remove the ionic liquid and water by freeze drying to obtain coconut shell-based nanocellulose, which is characterized by scanning electron microscopy, such as Figure 1 As shown in the figure, the diameter is about 16-21 nm; the length is 80-340 nm. The carboxyl content of the coconut shell-based nanocellulose prepared in this example was tested using formula (1), and the result was 0.43 mmol g -1 .

[0033] The obtained coconut shell-based nanocellulose was dissolved in dichloromethane to ensure that the nanocellulose was fully dispersed, and stirred at 55°C at a speed of 150 rpm for 30 minutes to completely dissolve it; propylene glycol and triethylamine were added to the solution, and stirred at a speed of 150 rpm for 45 minutes to fully mix it; the mixture was reacted at 65°C for 4 hours. After the reaction was completed, the heating was stopped and the solution was cooled to room temperature; the reaction mixture was transferred to a precipitation separation device, and anhydrous ethanol was used to induce the precipitation of the modified nanocellulose; the precipitate was repeatedly washed with deionized water to remove unreacted propylene glycol and triethylamine; after washing, it was dried in an oven with a set temperature of 55°C until constant weight was reached to ensure that water and solvent were completely removed to obtain coconut shell-based polyol, and the obtained coconut shell-based polyol was tested for carboxyl content according to formula (1), and the result was 0.14 mmol g -1 <0.43 mmol g -1 (Carboxyl content of coconut shell-based nanocellulose), this result shows that propylene glycol was successfully grafted onto the molecular chain of coconut shell-based nanocellulose. Embodiment 6

[0034] The collected fresh coconut shells were washed to remove impurities and dirt on the surface, and the washed coconut shells were dried using a drying equipment at a temperature of 80°C for about 24 hours until the moisture content of the coconut shells was 10%; the dried coconut shells were crushed using a crusher, and the particle size after crushing should be controlled at 5 mm; after crushing, they were screened using a sieve with a mesh size of 80, and the particles that did not reach the target particle size were crushed again; the pretreated coconut shells were soaked in a 12wt% sodium hydroxide solution, and the mass volume ratio of coconut shells to sodium hydroxide was set to 1:5 g / mL; the reaction was stirred at a speed of 100 rpm at a temperature of 100°C for 3 hours, thereby effectively removing lignin and increasing the cellulose content of the coconut shells. After the reaction was completed, the filtrate and the residue were filtered to separate; the residue was soaked in a 10wt% hydrogen peroxide solution, and the mass volume ratio of the residue to hydrogen peroxide was set to 5:5 g / mL, the pH value of the mixed solution was adjusted to 12, and the reaction was continued for 5 hours until the filter residue turned nearly white, and the filtrate was removed by filtration to obtain coconut shell fiber with high cellulose content, which was characterized by scanning electron microscopy. Figure 1 As shown in the figure, the diameter is about 12-18 nm; the length is 150-280 nm. The carboxyl content of the coconut shell-based nanocellulose prepared in this example was tested using formula (1), and the result was 0.39 mmol g -1 .

[0035] The coconut shell fiber is placed in the 1-N-allyl-2,3-dimethylimidazolium chloride solution prepared in Example 3, the amount of 1-N-allyl-2,3-dimethylimidazolium chloride solution added is 20 times the mass of the coconut shell fiber, the mixture is heated at 90°C, and stirred at a speed of 100 rpm for 2-4 hours until the coconut shell is completely dissolved to form a transparent solution; after completion, the coconut shell solution and the 1-N-allyl-2,3-dimethylimidazolium chloride solution are separated by a centrifuge to remove undissolved residues, and the obtained coconut shell solution is ultrasonically treated in an ultrasonic treatment equipment at a frequency of 30 kHz, a power of 1000 W, and a treatment time of 40 minutes. After the treatment is completed, it is cooled, and the ionic liquid and water are removed by freeze drying to obtain coconut shell-based nanocellulose; the obtained coconut shell-based nanocellulose Cellulose was dissolved in dichloromethane to ensure that the nanocellulose was fully dispersed, and the mixture was stirred at 60°C at a speed of 200 rpm for 40 minutes to completely dissolve it; glycerol and dimethylaminopyridine were added to the solution, and stirred at a speed of 200 rpm for 60 minutes to fully mix it; the mixture was reacted at 80°C for 6 hours. After the reaction was completed, the heating was stopped and the solution was cooled to room temperature; the reaction mixture was transferred to a precipitation separation device, and anhydrous ethanol was used to induce the precipitation of the modified nanocellulose; the precipitate was repeatedly washed with deionized water to remove unreacted glycerol and dimethylaminopyridine; after washing, the precipitate was dried in an oven at a set temperature of 60°C until constant weight was reached to ensure that water and solvent were completely removed to obtain coconut shell-based polyol, and the obtained coconut shell-based polyol was tested for carboxyl content according to formula (1), and the result was 0.13 mmol g -1 <0.39 mmol g -1 (Carboxyl content of coconut shell-based nanocellulose), which shows that glycerol was successfully grafted onto the molecular chain of coconut shell-based nanocellulose. Embodiment 7

[0036] In a multifunctional reactor, the coconut shell-based polyol, methyl isocyanate and glycerol prepared in Example 4 are added in sequence according to the formula weight, and the whole mixture is stirred at a speed of 200 rpm for 1 hour under nitrogen protection to make it uniformly mixed; a water bath is used to heat the mixture, the temperature of the mixture is controlled at 60°C, and the mixture is stirred at a speed of 100 rpm for 2 hours; then boron trifluoride ether complex and tert-butyl hydroxyanisole are added, and the water bath heating is continued to control the temperature at 90°C, and the reaction is carried out for 1 hour to ensure complete reaction and enhance the chemical stability of the polyurethane; finally, maleic anhydride is added and reacted at a temperature of 110°C for 1 hour to promote the cross-linking reaction and enhance the mechanical properties of the material; the reaction mixture is naturally cooled to room temperature under nitrogen protection, and a high-speed centrifuge is used to centrifuge at a speed of 3000 rpm for 10 minutes; after the centrifugation is completed, the precipitate is washed twice with deionized water to ensure that the residual additives are completely removed; then a vacuum drying oven is used to dry the finished product at a temperature of 40°C to ensure the stability and color of the polyurethane, and the desired bio-based polyether polyol polyurethane is obtained. Embodiment 8

[0037] In a multifunctional reactor, the coconut shell-based polyol, toluene diisocyanate and glycerol prepared in Example 5 were added in sequence according to the formula weight, and the whole mixture was stirred at a speed of 300 rpm for 1.5 hours under nitrogen protection to make it uniformly mixed; the mixture temperature was controlled at 70°C by water bath heating, and stirred at a speed of 150 rpm for 3 hours; then boron trifluoride ether complex and tert-butyl hydroxyphenylene glycol were added, and the temperature was continued to be controlled at 100°C by water bath heating, and the reaction was carried out for 1.5 hours to ensure complete reaction and enhance the chemical properties of polyurethane. stability; finally, maleic anhydride was added and reacted at a temperature of 120°C for 1.5 hours to promote the cross-linking reaction and enhance the mechanical properties of the material; the reaction mixture was naturally cooled to room temperature under nitrogen protection conditions, and centrifuged at 4500rpm for 15 minutes using a high-speed centrifuge; after centrifugation, the precipitate was washed twice with deionized water to ensure that the residual additives were completely removed; and then the finished product was dried in a vacuum drying oven at a temperature of 45°C to ensure the stability and color of the polyurethane, and the desired bio-based polyether polyol polyurethane was obtained. Embodiment 9

[0038] In a multifunctional reactor, coconut shell-based polyol, diphenylmethane isocyanate and glycerol prepared in Example 6 are added in sequence according to the formula weight, and the whole mixture is stirred at a speed of 400 rpm for 2 hours under nitrogen protection to make it uniformly mixed; a water bath is used to heat the mixture, the temperature of the mixture is controlled at 80°C, and the mixture is stirred at a speed of 200 rpm for 4 hours; then boron trifluoride ether complex and N-graphene acid amine are added, and the temperature is continued to be controlled at 110°C by water bath heating, and the reaction is carried out for 2 hours to ensure complete reaction and enhance the chemical stability of the polyurethane; finally, phthalic acid is added and reacted at a temperature of 130°C for 2 hours to promote the cross-linking reaction and enhance the mechanical properties of the material; the reaction mixture is naturally cooled to room temperature under nitrogen protection, and a high-speed centrifuge is used to centrifuge at a speed of 6000 rpm for 20 minutes; after the centrifugation, the precipitate is washed 3 times with deionized water to ensure that the residual additives are completely removed; then a vacuum drying oven is used to dry the finished product at a temperature of 50°C to ensure the stability and color of the polyurethane, and the desired bio-based polyether polyol polyurethane is obtained. Embodiment 10

[0039] Experiments were designed to test the wear resistance of the polyurethanes of the bio-based polyether polyols prepared in Examples 7, 8 and 9, and compared them with traditional petroleum-based polyurethanes.

[0040] The four samples were prepared into discs with a thickness of 3 mm and a diameter of 100 mm. The discs were tested on a wear tester at a speed of 60 rpm for 500 revolutions, and the wear loss (in mg) of each sample was recorded.

[0041] The experimental results are shown in the following table:

[0042] Polyurethanes made from bio-based polyether polyols are significantly better than traditional petroleum-based polyurethanes in terms of wear resistance, which indicates that they can maintain a better surface condition during use, reduce wear losses, and increase the service life of the material. Therefore, polyurethanes made from bio-based polyether polyols are suitable for applications that require wear-resistant materials. Embodiment 11

[0043] Experiments were designed to test the strength of the polyurethanes of the bio-based polyether polyols prepared in Examples 7, 8 and 9, and compared them with traditional petroleum-based polyurethanes.

[0044] The four samples were prepared into specimens of 10 mm × 10 mm × 100 mm, and the tensile strength and elongation at break were tested on an electronic universal testing machine. The loading rate was 5 mm / min, and the maximum tensile strength (in MPa) and elongation at break (in %) of each sample were recorded.

[0045] The experimental results are shown in the following table: sample Maximum tensile strength Elongation at break Example 7 Polyurethane of bio-based polyether polyol prepared 35.5MPa 300% Example 8 Polyurethane of bio-based polyether polyol 38.9MPa 327% Example 9 Polyurethane of bio-based polyether polyol prepared 42.3MPa 349% Petroleum-based polyurethane 32MPa 200% Polyurethanes made from bio-based polyether polyols have excellent strength and ductility, which is superior to petroleum-based polyurethanes. This means that they have higher load capacity and good toughness, making them suitable for applications that are subject to high loads or impacts, such as automotive parts, sports equipment, and high-strength structural materials. Embodiment 12

[0046] Experiments were designed to test the weather resistance of the polyurethanes of the bio-based polyether polyols prepared in Examples 7, 8, and 9, and compared them with traditional petroleum-based polyurethanes.

[0047] The four samples were prepared into 10mm×10mm specimens and subjected to UV light irradiation and water mist test in a weathering tester. The cycle was 8 hours of UV irradiation, followed by 24 hours of water mist immersion, and the test lasted for 500 hours. The surface hardness change, color change and surface adhesion of the samples were recorded.

[0048] The experimental results are shown in the following table: sample Hardness change Color Change Surface Adhesion Example 7 Polyurethane of bio-based polyether polyol prepared No significant changes Small changes (ΔE < 5) No peeling Example 8 Polyurethane of bio-based polyether polyol No significant changes Small changes (ΔE < 5) No peeling Example 9 Polyurethane of bio-based polyether polyol prepared No significant changes Small changes (ΔE < 5) No peeling Petroleum-based polyurethane Notable changes Significant change (ΔE > 10) Partial peeling Polyurethanes made from bio-based polyether polyols are far superior to petroleum-based polyurethanes in terms of weather resistance, and can better resist the effects of environmental factors such as ultraviolet rays and moisture, and maintain stable surface properties. This makes polyurethanes made from bio-based polyether polyols suitable for outdoor applications such as architectural coatings, outdoor furniture, and automotive exteriors, and can be used in harsh environments for a long time without losing performance. Embodiment 13

[0049] The designed experiment tested the thermal conductivity of the polyurethanes of the bio-based polyether polyols prepared in Examples 7, 8 and 9, and compared them with the traditional petroleum-based polyurethanes.

[0050] Four samples were prepared into square specimens with a thickness of 10 mm and an area of ​​100 mm × 100 mm. The specimens were placed in the thermal conductivity tester to ensure good contact with the sensor. The test conditions were set and the temperature gradient (ΔT) and heat flux (q) of the specimens were recorded. The thermal conductivity (k) was calculated using the formula:

[0051] Where d is the specimen thickness and A is the specimen area.

[0052] The thermal conductivity test is as follows: sample Heat flux Temperature gradient Thermal conductivity Example 7 Polyurethane of bio-based polyether polyol prepared 50 W / m² 10℃ 0.5 W / (mK) Example 8 Polyurethane of bio-based polyether polyol 55 W / m² 10℃ 0.55 W / (mK) Example 9 Polyurethane of bio-based polyether polyol prepared 60 W / m² 10℃ 0.6 W / (mK) Petroleum-based polyurethane 45 W / m² 10℃ 0.45 W / (mK) The thermal conductivity of bio-based polyurethane is no less than 0.5 W / (mK), which is higher than the 0.45 W / (mK) of petroleum-based polyurethane, indicating that the material has excellent performance in thermal insulation and is suitable for use in insulation and thermal insulation materials. Embodiment 14

[0053] The designed experiment tested the acid and alkali resistance of the polyurethanes of the bio-based polyether polyols prepared in Examples 7, 8 and 9, and compared them with the traditional petroleum-based polyurethanes.

[0054] Four samples were prepared into specimens with a thickness of 5 mm and a size of 50 mm × 50 mm. Two test liquids were prepared: 1 M HCl and 1 M NaOH. The specimens were immersed in HCl and NaOH solutions, respectively, for 7 days, during which the test liquids were replaced every 24 hours to maintain the concentration. After the immersion, the specimens were taken out, rinsed with distilled water, and dried at room temperature for 24 hours. The surface changes of the specimens were observed under a microscope, and the corrosion resistance was evaluated, and any cracks, discoloration, or material loss were recorded.

[0055] Acid and alkali resistance test is as follows: sample Soaking liquid Surface observation results Evaluate Example 7 Polyurethane of bio-based polyether polyol prepared HCl No change in surface microtexture Excellent corrosion resistance Example 7 Polyurethane of bio-based polyether polyol prepared NaOH Smooth surface, no obvious damage Excellent corrosion resistance Example 8 Polyurethane of bio-based polyether polyol HCl No change in surface microtexture Excellent corrosion resistance Example 8 Polyurethane of bio-based polyether polyol NaOH Smooth surface, no obvious damage Excellent corrosion resistance Example 9 Polyurethane of bio-based polyether polyol prepared HCl No change in surface microtexture Excellent corrosion resistance Example 9 Polyurethane of bio-based polyether polyol prepared NaOH Smooth surface, no obvious damage Excellent corrosion resistance Petroleum-based polyurethane HCl Obvious cracks on the surface Poor corrosion resistance Petroleum-based polyurethane NaOH Surface discoloration and damage Poor corrosion resistance Polyurethanes made from bio-based polyether polyols exhibit excellent corrosion resistance in acidic and alkaline environments, with no significant damage after immersion, whereas petroleum-based polyurethanes exhibit significant cracking and discoloration, with poor corrosion resistance. This makes polyurethanes made from bio-based polyether polyols suitable for applications requiring high acid and alkali resistance, such as chemical treatment and anti-corrosion coatings.

[0056] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A polyurethane of a bio-based polyether polyol, characterized in that: The composition of the polyurethane of the bio-based polyether polyol is as follows: 20-30 parts of coconut shell polyol, 10-20 parts of glycerol, 10-20 parts of polyacid, 2-4 parts of antioxidant, 5-8 parts of boron trifluoride ether compound, 5-10 parts of isocyanate, and 60-80 parts of deionized water. The preparation method of the coconut shell polyol comprises the following steps: S1 washes the collected fresh coconut shells to remove impurities and dirt on the surface, and uses a drying device to dry the washed coconut shells at a temperature of 60-80°C for about 12-24 hours until the moisture content of the coconut shells is 2-10%; uses a crusher to crush the dried coconut shells, and the particle size after crushing should be controlled at 1-5mm; uses a sieve with a mesh number of 40-80 to screen after crushing, and crushes the particles that do not reach the target particle size again; S2: Soak the pretreated coconut shell in a sodium hydroxide solution with a concentration of 5-12wt%, and the mass volume ratio of coconut shell to sodium hydroxide is set to 1:3-5 g / mL; stir and react at a speed of 500-100 rpm at a temperature of 80-100°C for 1-3 hours, so as to effectively remove lignin and increase the cellulose content of the coconut shell. After the reaction is completed, filter and separate the filtrate and residue; soak the residue in a hydrogen peroxide solution with a concentration of 3-10wt%, and the mass volume ratio of the residue to hydrogen peroxide is set to 5:1-5 g / mL, adjust the pH value of the mixed solution to 10-12, react for 2-5 hours, until the residue becomes nearly white, filter and remove the filtrate, and obtain coconut shell fiber with a high cellulose content; S3: placing coconut shell fiber in a 1-N-allyl-2,3-dimethylimidazolium chloride solution, wherein the amount of 1-N-allyl-2,3-dimethylimidazolium chloride solution added is 10 to 20 times the mass of the coconut shell fiber, heating the mixture at 80 to 90°C, and stirring at a speed of 500 to 100 rpm for 2 to 4 hours until the coconut shell is completely dissolved to form a transparent solution; after completion, using a centrifuge to separate the coconut shell solution from the 1-N-allyl-2,3-dimethylimidazolium chloride solution to remove undissolved residues, and subjecting the obtained coconut shell solution to ultrasonic treatment in an ultrasonic treatment device at a frequency of 20 to 30 kHz, a power of 800 to 1000 W, and a treatment time of 30 to 40 minutes. After the treatment is completed, cooling is performed, and the ionic liquid and water are removed by freeze drying to obtain coconut shell-based nanocellulose; S4 dissolves the obtained coconut shell-based nanocellulose in dichloromethane to ensure that the nanocellulose is fully dispersed, and stirs at 100-200 rpm for 20-40 minutes at 50-60°C to completely dissolve it; adds polyols and catalysts to the solution, and stirs at 100-200 rpm for 30-60 minutes to fully mix it; reacts the mixture at 50-80°C for 3-6 hours. After the reaction is completed, stop heating and wait for the solution to cool to room temperature; transfers the reaction mixture to a precipitation separation device, and uses anhydrous ethanol to induce the precipitation of the modified nanocellulose; repeatedly washes the precipitate with deionized water to remove unreacted polyols and catalysts; after washing, dries in an oven with a set temperature of 50-60°C until constant weight is reached, ensuring complete removal of moisture and solvent to obtain coconut shell-based polyols.

2. The polyurethane of a bio-based polyether polyol according to claim 1, characterized in that: The polyol described in S4 is a combination of one or more of ethylene glycol, propylene glycol and glycerol.

3. The polyurethane of a bio-based polyether polyol according to claim 1, characterized in that: S4 The catalyst is a combination of one or more of triphenylphosphine, triethylamine and dimethylaminopyridine.

4. The polyurethane of a bio-based polyether polyol according to claim 1, characterized in that: The boron trifluoride ether compound is one or a combination of boron trifluoride ethyl ether complex and boron trifluoride butyl ether complex.

5. The polyurethane of a bio-based polyether polyol according to claim 1, characterized in that: The preparation method of 1-N-allyl-2,3-dimethylimidazolium chloride comprises the following process: S1 Add 2,3-dimethylimidazole to the reaction bottle, add allyl chloride under nitrogen protection, and stir the mixture at 100-200 rpm with a magnetic stirrer at 60-80°C for 2-4 hours; S2 After the reaction is completed, the mixture is cooled to room temperature and unreacted reagents and solvents are removed by distillation; the reaction mixture is poured into a separatory funnel, deionized water is added, and washed to remove water-soluble impurities; The obtained precipitate is dissolved in dichloromethane through separation chromatography to remove impurities in the organic layer; finally, the obtained liquid is poured into a dryer, and anhydrous magnesium sulfate desiccant is used to remove excess water to obtain the desired 1-N-allyl-2,3-dimethylimidazole chloride.

6. The polyurethane of a bio-based polyether polyol according to claim 1, characterized in that: The antioxidant is a combination of one or more of tert-butyl hydroxyanisole, tert-butyl hydroxyphenylene glycol and N-graphene acid amine.

7. The polyurethane of a bio-based polyether polyol according to claim 1, characterized in that: The polyacid is a combination of one or more of maleic anhydride and phthalic acid.

8. The polyurethane of a bio-based polyether polyol according to claim 1, characterized in that: The isocyanate is a combination of one or more of methyl isocyanate, polyester isocyanate, diphenylmethane isocyanate and toluene diisocyanate.

9. The method for preparing polyurethane of bio-based polyether polyol according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: S1: In a multifunctional reactor, add coconut shell-based polyol, isocyanate, and polyol in order according to the formula weight, and stir the entire mixture at a speed of 200-400 rpm for 1-2 hours under nitrogen protection to make it evenly mixed; use a water bath to heat the mixture, control the temperature of the mixture at 60-80°C, and stir at a speed of 100-200 rpm for 2-4 hours; then add boron trifluoride ether compound and antioxidant, continue to use water bath heating to control the temperature at 90-110°C, react for 1-2 hours to ensure complete reaction and enhance the chemical stability of polyurethane; finally, add polyacid and react at a temperature of 110-130°C for 1-2 hours to promote cross-linking reaction and enhance the mechanical properties of the material; S2: The reaction mixture is naturally cooled to room temperature under nitrogen protection, and centrifuged at 3000-6000 rpm for 10-20 minutes using a high-speed centrifuge; after centrifugation, the precipitate is washed 2-3 times with deionized water to ensure that the residual additives are completely removed; and then the finished product is dried in a vacuum drying oven at a temperature of 40-50°C to ensure the stability and color of the polyurethane, thereby obtaining the desired bio-based polyether polyol polyurethane.

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