A modified bio-based polymer and a method for preparing the same

Abstract

This invention discloses a modified bio-based polymer and its preparation method, belonging to the field of polymer technology. The modified bio-based polymer prepared by this invention comprises the following raw material components: bio-based polyisocyanate monomer, polyol mixture, amino acids, catalyst, neutralizing agent, chain extender, composite filler, antioxidant, and organosilicon coupling agent. The polyol mixture is a mixture of bis(2-amino-4,6-di(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, biomass polyol, and 4-hydroxymethyl-2-furanaldehyde. The composite filler is a mixture of nitrided carbon-based flame-retardant filler and porous nitrogen-doped carbon-based filler. The modified bio-based polymer prepared by this invention exhibits good flame retardancy and good mechanical properties.

Description

Technical Field

[0001] This invention relates to a modified bio-based polymer and its preparation method. Background Technology

[0002] With increasingly stringent global environmental regulations, the search for environmentally friendly materials has become a crucial research direction. Against this backdrop, bio-based polymers, due to their renewability and environmental friendliness, have gradually become a research hotspot in materials science. In particular, bio-based polyurethane (Bio-PU), with its excellent biodegradability and biocompatibility, has shown enormous application potential in textiles, medicine, packaging, and other fields.

[0003] However, traditional bio-based polyurethane molecular chains contain a large number of hydrocarbon structures, making the materials highly flammable and releasing toxic fumes during combustion, posing a serious threat to human health and environmental safety. Although studies have attempted to improve flame retardant properties by adding bio-based flame retardants (such as lignin and cellulose derivatives), the results have been less than ideal. On the one hand, these flame retardants have low flame retardant efficiency; on the other hand, they have poor compatibility with the polyurethane matrix, leading to poor uniformity and stability of the composite material. More seriously, excessive addition of flame retardants can cause a significant decrease in the material's mechanical properties, further limiting its application range.

[0004] Besides the flame retardancy issue, bio-based raw materials (such as polylactic acid polyols) also have certain limitations. These raw materials typically have high molecular chain rigidity and low crystallinity, resulting in polyurethane materials that exhibit greater brittleness and lower heat resistance. For example, the tensile strength of pure polylactic acid polyurethane is usually less than 20 MPa, far below the standard requirements for industrial applications.

[0005] Therefore, there is an urgent need to develop a modified bio-based polymer that aims to improve its flame retardancy and mechanical properties while maintaining its original advantages of degradability and biocompatibility. Summary of the Invention

[0006] The purpose of this invention is to provide a modified bio-based polymer and its preparation method to solve the technical problems mentioned in the background section.

[0007] The technical solution to achieve the objective of this invention is:

[0008] In a first aspect, the present invention provides a modified bio-based polymer, comprising, by mass parts: 45-55 parts by mass of bio-based polyisocyanate monomer, 45-55 parts by mass of polyol mixture, 4-6 parts by mass of amino acid, 0.05-0.25 parts by mass of catalyst, 0.1-1 parts by mass of neutralizer, 3-7 parts by mass of chain extender, 24-30 parts by mass of composite filler, 1-3 parts by mass of antioxidant, 1.5-2.1 parts by mass of organosilicon coupling agent, 3-5 parts by mass of solvent, and 40-45 parts by mass of water.

[0009] The bio-based polyisocyanate monomer is lysine diisocyanate.

[0010] Furthermore, the polyol mixture is obtained by mixing bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, biomass polyol, and 4-hydroxymethyl-2-furan carbaldehyde; the biomass polyol includes any one of palm oil polyol, cashew nut shell oil polyol, soybean oil polyol, polylactic acid polyol, and castor oil polyol.

[0011] The amino acids include at least two combinations of cysteine, arginine, and glycine.

[0012] The catalyst is either dibutyltin dilaurate or stannous octoate.

[0013] The chain extender is any one of 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, and 1,4-butanediol.

[0014] The neutralizing agent is any one of triethylamine, triethylenediamine, or ethylenediamine.

[0015] The antioxidant is obtained by mixing citric acid and antioxidant 1010 in a mass ratio of 1:1.

[0016] The solvent used is acetone.

[0017] Furthermore, the composite filler is obtained by mixing carbon nitride-based flame retardant filler and porous nitrogen-doped carbon-based filler at a mass ratio of 2:1.

[0018] Furthermore, the carbon nitride-based flame retardant filler is prepared by in-situ chemical impregnation of carbon nitride with zinc nitrate hexahydrate and 2-methylimidazole as precursors, followed by calcination under nitrogen and modification with organic phosphonates.

[0019] Furthermore, the porous nitrogen-doped carbon-based filler is obtained by calcining biomass folic acid as a carbon and nitrogen precursor, zinc nitrate hexahydrate as a pore-forming agent, and potassium bromide as a pore-forming aid under an inert gas atmosphere.

[0020] In a second aspect, the present invention provides a method for preparing the modified bio-based polymer as described in the first aspect, the preparation steps including:

[0021] (1) Weigh and mix each raw material component according to the mass fraction;

[0022] (2) Under nitrogen protection, the polyol mixture weighed in step (1) is placed in the reactor and heated to 78-82°C. Then, bio-based polyisocyanate monomer and catalyst are added and reacted for 2-4 hours. Then, solvent and chain extender are added and stirred for another 2-4 hours. In this step, the polyol mixture is grafted with isocyanate through the reaction of active groups such as hydroxyl groups to obtain polyurethane prepolymer.

[0023] (3) Add a neutralizing agent to the polyurethane prepolymer obtained in step (2) after it has cooled to room temperature. React at room temperature for 15-25 minutes, then add deionized water, amino acids, and antioxidants. Continue stirring for 25-35 minutes. Next, add 0.1 times the mass of deionized water, ethanol, organosilicon coupling agent, and composite filler. Stir until evenly dispersed, then heat to 75-85°C under air conditions and stir under light for 8-10 hours. At this time, the loading of monatomic zinc in the carbon nitride-based flame retardant filler can form zinc-nitrogen coordination bonds with nitrogen atoms in carbon nitride at the atomic level, forming active sites. Under light conditions, the metal coordination... The center can conduct electron transfer channels, adjust the band gap structure, effectively separate photogenerated electron-hole pairs, catalyze oxygen in the air, and form hydrogen peroxide in the reaction system. Then, under the combined action of hydrogen peroxide and porous nitrogen-doped carbon-based filler, it catalyzes the selective oxidation of furfural to form maleic acid. Maleic acid reacts with amino groups in the system to form maleamide compounds. Then, the temperature is raised to 128-132℃ and the reaction is stirred for 11-13 hours. During this process, the maleamide compounds are dehydrated to form maleimide compounds. At the same time, citric acid and amino acids are dehydrated multiple times to form pyridone compounds, thus obtaining modified bio-based polymers.

[0024] The principles involved in step (3) are as follows:

[0025]

[0026] Furthermore, the mass ratio of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, biomass polyol, and 4-hydroxymethyl-2-furanaldehyde in the polyol mixture is 13.5–16.5: 27–33: 4.5–5.5.

[0027] Further, the preparation method of the carbon nitride-based flame-retardant filler in the composite filler is as follows: 1 part by mass of carbon nitride is placed in 32 parts by mass of methanol and ultrasonically stirred for 1-2 hours. Then, 0.19-0.2 parts by mass of zinc nitrate hexahydrate is added and stirring is continued for 8-10 hours. After precipitation overnight, 0.18-0.19 parts by mass of 2-methylimidazole is added and stirring is continued for 24 hours. The mixture is then washed three times with methanol and vacuum dried at 60°C for 10-12 hours. Finally, the mixture is calcined in a nitrogen tube furnace at a temperature increased at 5°C / min to 400°C for 1.5-2.5 hours. After cooling to room temperature, carbon nitride composite filler was obtained. 6.8-7 parts by weight of carbon nitride composite filler were mixed with 200 parts by weight of deionized water and ultrasonically dispersed for 30 min. Then, 21-22 parts by weight of 2-carboxyethylphenylphosphonic acid were added and ultrasonically dispersed for another 1 h. Then, sodium hydroxide was added to adjust the pH to 5-6 and the temperature was raised to 80-90℃. Finally, 10-12 wt% aluminum sulfate solution was added dropwise at 1-3 s / drop and the reaction was kept at the temperature for 3.5-4.5 h under stirring. After filtration, washing and drying, carbon nitride-based flame retardant filler was obtained.

[0028] Further, the preparation method of the porous nitrogen-doped carbon-based filler in the composite filler is as follows: 0.65-0.67 parts by mass of folic acid are dissolved in 100 parts by mass of pure water. Under stirring conditions, 0.33-0.35 parts by mass of 1 mol / L potassium hydroxide solution are added and stirred until the folic acid is completely dissolved. Then, 1.1-1.3 parts by mass of potassium bromide are added and completely dispersed. Then, 0.62-0.63 parts by mass of zinc nitrate are added and mixed and shaken. After standing at room temperature for 1 hour, the mixture is freeze-dried. Then, under nitrogen protection, the mixture is placed in a tube furnace and heated to 800℃ at a heating rate of 3℃ / min for 2 hours. After cooling to room temperature at a rate of 3℃ / min, the potassium bromide is removed by washing with deionized water and dried to obtain the porous nitrogen-doped carbon-based filler.

[0029] Furthermore, the light source is an LED. 365nm or LED 420nm .

[0030] By adopting the above technical solution, the present invention has the following beneficial effects:

[0031] (1) The modified bio-based polymer disclosed in this invention comprises, by mass parts, 45-55 parts of bio-based polyisocyanate monomer, 45-55 parts of polyol mixture, 4-6 parts of amino acid, 0.05-0.25 parts of catalyst, 0.1-1 parts of neutralizer, 3-7 parts of chain extender, 24-30 parts of composite filler, 1-3 parts of antioxidant, and 1.5-2.1 parts of organosilicon coupling agent; the modified bio-based polymer prepared by the above formula has better flame retardancy, antioxidant properties, flame retardancy, UV aging resistance, and mechanical properties.

[0032] (2) The modified bio-based polymer of the present invention adds amino acids, wherein amino acids, as the basic building blocks of proteins, are compounds in which one amino group and one carboxyl group are attached to the same carbon atom. Polyurethane synthesized using amino acids and their derivatives usually has good degradability and biocompatibility. After decomposition, the amino acid part becomes amino acid residues, which are not toxic to the human body and the environment.

[0033] (3) The amino acid used in this invention is at least cysteine, and the antioxidant is a mixture of citric acid and antioxidant 1010. On the one hand, it can give the bio-based polymer better antioxidant properties. On the other hand, citric acid and amino acid undergo multiple dehydration reactions to form a compound containing a conjugated pyridone group, which effectively gives the modified bio-based polymer better UV resistance.

[0034] (4) The composite filler of the present invention is obtained by mixing carbon nitride-based flame retardant filler and porous nitrogen-doped carbon-based filler. The carbon nitride-based flame retardant filler is prepared by in-situ chemical impregnation of carbon nitride with zinc nitrate hexahydrate and 2-methylimidazole as precursors, followed by calcination under nitrogen and modification with organic phosphonates. The carbon nitride sheets act as a physical barrier, blocking the release of smoke particles and reducing the total amount of smoke generated during combustion. The introduction of organic phosphonates decomposes during combustion to generate phosphate-containing salts, promoting the formation of residual char in the matrix and inhibiting... The exchange of heat and oxygen within and outside the matrix, along with the dense carbon layer, reduces the thermal decomposition rate of the matrix and delays further pyrolysis of the material. Simultaneously, phosphorus-oxygen free radicals are generated and quench gaseous active free radicals through the free radical scavenging effect. Furthermore, a large amount of non-combustible gases (CO2, NH3, H2O, etc.) are generated in the gaseous products, absorbing the heat of combustion while diluting the oxygen concentration and disrupting the combustion microenvironment, thus achieving excellent flame retardant effects. The addition of porous nitrogen-doped carbon-based fillers can effectively increase the mechanical properties of the modified bio-based polymer by acting as physical crosslinking points.

[0035] (5) The polyol mixture of the present invention includes at least bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid and 4-hydroxymethyl-2-furan carbaldehyde. The flame retardant properties of the modified bio-based polymer can be further improved by introducing bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid.

[0036] (6) In the preparation of the modified bio-based polymer of the present invention, after adding organosilicon coupling agent and composite filler, the reaction is carried out under light and air conditions, followed by dehydration reaction. 2-furan carboxaldehyde in the modified bio-based polymer is catalytically oxidized to maleic acid under the combined action of composite filler. Maleic acid reacts with unreacted amino groups in the system to form maleimide, which increases the crosslinking density of the modified bio-based polymer, makes up for the influence of the aforementioned catalytic oxidation process on the mechanical properties of the system, and further improves the mechanical properties and flame retardant properties of the modified bio-based polymer. Detailed Implementation

[0037] To better understand the above technical solution, the following will provide a detailed explanation of the technical solution in conjunction with specific implementation methods.

[0038] Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention.

[0039] The following embodiments are only used to illustrate the technical solutions of the present invention more clearly, and should not be used to limit the scope of protection of the present invention.

[0040] The following are some of the raw materials used in the embodiments and comparative examples of this invention:

[0041] The preparation steps of carbon nitride are as follows: 15 parts by mass of urea are heated to 550°C in a muffle furnace at 2°C / min and calcined for 4 hours, then cooled to room temperature. The mixture is then heated to 550°C in air at 5°C / min and calcined for 1 hour. After cooling to room temperature, the mixture is heated to 550°C and calcined for 1 hour. After cooling to room temperature, carbon nitride is obtained.

[0042] The preparation steps of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid are as follows: 6.2 parts by weight of cyanuric chloride solid and 8.9 parts by weight of acetone are stirred and mixed evenly. Then, 2.29 parts by weight of 25 wt% ammonia water and 1.345 parts by weight of 5M sodium hydroxide aqueous solution are added dropwise at 2-4 seconds per drop. The reaction is carried out at 0-5°C for 3 hours. The temperature is then raised to 50°C, and 2.054 parts by weight of ethanolamine and 1.345 parts by weight of 5M sodium hydroxide aqueous solution are added dropwise at 2-4 seconds per drop. The reaction is continued for 8 hours. After evaporating the acetone at 58°C, the temperature is raised to 90°C, and 2.054 parts by weight of ethanolamine and 1.345 parts by weight of 5M sodium hydroxide aqueous solution are added dropwise again at 2-4 seconds per drop. A 5M sodium hydroxide aqueous solution was added, and the reaction was continued for 8 hours. After cooling to room temperature, the mixture was filtered, washed three times with acetone and deionized water, and dried in an oven at 50°C for 12 hours to obtain intermediate A. 3.212 parts by mass of intermediate A, 0.474 parts by mass of paraformaldehyde, and 0.795 parts by mass of sodium hypophosphite were mixed, and 20 parts by mass of glacial acetic acid were added. The mixture was heated to 120°C and stirred for 30 minutes. Then, 1.53 parts by mass of acetic anhydride were added. After the addition was complete, the mixture was stirred for another 7 hours. After the reaction was complete, the mixture was cooled to room temperature, washed repeatedly with deionized water, and filtered to obtain a white solid. The solid was dried in an oven for 12 hours to obtain bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid.

[0043] The preparation mechanism of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid is as follows:

[0044]

[0045] The bio-based polyisocyanate monomer uses lysine diisocyanate.

[0046] The polyol mixture is obtained by mixing bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, biomass polyol, and 4-hydroxymethyl-2-furan carbaldehyde; the biomass polyol is polylactic acid polyol PLA1000 with a hydroxyl value of 95-125 mgKOH / g.

[0047] The amino acid is obtained by mixing cysteine ​​and arginine in a mass ratio of 1:1.

[0048] The catalyst is dibutyltin dilaurate.

[0049] The chain extender is 1,4-butanediol.

[0050] The neutralizing agent is triethylamine.

[0051] The antioxidant is obtained by mixing citric acid and antioxidant 1010 in a mass ratio of 1:1.

[0052] Acetone was used as the solvent.

[0053] The composite filler is obtained by mixing carbon nitride-based flame retardant filler and porous nitrogen-doped carbon-based filler at a mass ratio of 2:1.

[0054] The silane coupling agent used is silane coupling agent KH550.

[0055] (Example 1)

[0056] A method for preparing a modified bio-based polymer, comprising the following steps:

[0057] (1) Weigh and mix the raw materials according to the following mass parts: 55 parts by mass of bio-based polyisocyanate monomer, 45 parts by mass of polyol mixture, 4 parts by mass of amino acid, 0.05 parts by mass of catalyst, 0.1 parts by mass of neutralizer, 3 parts by mass of chain extender, 24 parts by mass of composite filler, 1 part by mass of antioxidant, 1.5 parts by mass of organosilicon coupling agent, 3 parts by mass of solvent, and 40 parts by mass of water;

[0058] (2) Under nitrogen protection, the polyol mixture weighed in step (1) is placed in the reactor and heated to 78°C. Then, bio-based polyisocyanate monomer and catalyst are added and reacted for 2 hours. Then, solvent and chain extender are added and stirred for another 2 hours. In this step, the polyol mixture is grafted with isocyanate through the reaction of active groups such as hydroxyl groups to obtain polyurethane prepolymer.

[0059] (3) Add a neutralizing agent to the polyurethane prepolymer obtained in step (2) after it has cooled to room temperature. React at room temperature for 15 minutes, then add deionized water, amino acids, and antioxidants. Continue stirring for 25 minutes. Next, add 0.1 times the mass of deionized water, ethanol, organosilicon coupling agent, and composite filler. Stir until evenly dispersed, then heat to 75°C under air conditions and use LEDs. 365nm The mixture was irradiated and stirred for 8 hours. During this time, the single-atom zinc loading in the carbon nitride-based flame retardant filler could form zinc-nitrogen coordination bonds with nitrogen atoms in the carbon nitride at the atomic level, forming active sites. Under light irradiation, the metal coordination centers could conduct electron transfer channels, adjust the band gap structure, effectively separate photogenerated electron-hole pairs, and catalyze the formation of hydrogen peroxide in the reaction system to produce oxygen in the air. Subsequently, under the combined action of hydrogen peroxide and porous nitrogen-doped carbon-based filler, furfural was selectively oxidized to form maleic acid. Maleic acid reacted with amino groups in the system to form maleamide compounds. The temperature was then raised to 128°C and the reaction was stirred for 11 hours. During this process, the maleamide compounds were dehydrated to form maleimide compounds, while citric acid and amino acids were dehydrated multiple times to form pyridone compounds, resulting in modified bio-based polymers.

[0060] The mass ratio of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, biomass polyol, and 4-hydroxymethyl-2-furanaldehyde in the polyol mixture is 13.5:27:4.5.

[0061] The preparation method of carbon nitride-based flame retardant filler in composite filler is as follows: 1 part by mass of carbon nitride is placed in 32 parts by mass of methanol and ultrasonically stirred for 1 hour. Then, 0.19 parts by mass of zinc nitrate hexahydrate is added and stirring is continued for 8 hours. After precipitation overnight, 0.18 parts by mass of 2-methylimidazole is added and stirring is continued for 24 hours. After washing three times with methanol, it is vacuum dried at 60℃ for 10 hours. Then, it is calcined in a nitrogen tube furnace at 400℃ at a rate of 5℃ / min for 1.5 hours. After cooling to room temperature, carbon nitride composite filler is obtained. 6.8 parts by mass of carbon nitride composite filler is mixed with 200 parts by mass of deionized water and ultrasonically dispersed for 30 minutes. Then, 21 parts by mass of 2-carboxyethylphenylphosphonic acid is added and ultrasonically dispersed for 1 hour. Then, sodium hydroxide is added to adjust the pH to 5 and the temperature is raised to 80℃. Finally, 10 wt% aluminum sulfate solution is added dropwise at 1 second / drop, and the reaction is maintained at a constant temperature for 3.5 hours under stirring. After filtration, washing, and drying, carbon nitride-based flame retardant filler is obtained.

[0062] The preparation method of porous nitrogen-doped carbon-based filler in composite filler is as follows: 0.65 parts by mass of folic acid are dissolved in 100 parts by mass of pure water. Under stirring, 0.33 parts by mass of 1 mol / L potassium hydroxide solution is added and stirred until the folic acid is completely dissolved. Then, 1.1 parts by mass of potassium bromide is added and completely dispersed. Then, 0.62 parts by mass of zinc nitrate is added and mixed and shaken. After standing at room temperature for 1 hour, it is freeze-dried. Then, under nitrogen protection, it is placed in a tube furnace and heated to 800℃ at a heating rate of 3℃ / min for 2 hours. Then, it is cooled to room temperature at a rate of 3℃ / min. Then, it is washed with deionized water to remove potassium bromide and dried to obtain porous nitrogen-doped carbon-based filler.

[0063] (Example 2)

[0064] A method for preparing a modified bio-based polymer, comprising the following steps:

[0065] (1) Weigh and mix each raw material component according to the following mass parts: 50 parts by mass of bio-based polyisocyanate monomer, 50 parts by mass of polyol mixture, 5 parts by mass of amino acid, 0.15 parts by mass of catalyst, 0.6 parts by mass of neutralizer, 5 parts by mass of chain extender, 27 parts by mass of composite filler, 2 parts by mass of antioxidant, 1.8 parts by mass of organosilicon coupling agent, 4 parts by mass of solvent, and 43 parts by mass of water;

[0066] (2) Under nitrogen protection, the polyol mixture weighed in step (1) is placed in the reactor, heated to 80°C, and then bio-based polyisocyanate monomer and catalyst are added. The reaction is carried out for 3 hours, and then solvent and chain extender are added. The mixture is stirred for another 3 hours. In this step, the polyol mixture is grafted with isocyanate through the reaction of active groups such as hydroxyl groups to obtain polyurethane prepolymer.

[0067] (3) Add a neutralizing agent to the polyurethane prepolymer obtained in step (2) after it has cooled to room temperature. React at room temperature for 20 minutes, then add deionized water, amino acids, and antioxidants. Continue stirring for 30 minutes. Next, add 0.1 times the mass of deionized water, ethanol, organosilicon coupling agent, and composite filler. Stir until evenly dispersed, then heat to 80°C under air conditions and use LEDs. 420nm The mixture was irradiated and stirred for 9 hours. During this time, the single-atom zinc loading in the carbon nitride-based flame retardant filler could form zinc-nitrogen coordination bonds with nitrogen atoms in the carbon nitride at the atomic level, forming active sites. Under light irradiation, the metal coordination centers could conduct electron transfer channels, adjust the band gap structure, effectively separate photogenerated electron-hole pairs, and catalyze the formation of hydrogen peroxide in the reaction system to produce oxygen in the air. Subsequently, under the combined action of hydrogen peroxide and porous nitrogen-doped carbon-based filler, furfural was selectively oxidized to form maleic acid. Maleic acid reacted with amino groups in the system to form maleamide compounds. The temperature was then raised to 130°C and the reaction was stirred for another 12 hours. During this process, the maleamide compounds were dehydrated to form maleimide compounds, while citric acid and amino acids were dehydrated multiple times to form pyridone compounds, resulting in modified bio-based polymers.

[0068] The mass ratio of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, biomass polyol, and 4-hydroxymethyl-2-furanaldehyde in the polyol mixture is 15:30:5.

[0069] The preparation method of carbon nitride-based flame retardant filler in composite filler is as follows: 1 part by mass of carbon nitride is placed in 32 parts by mass of methanol and ultrasonically stirred for 1.5 h. Then, 0.195 parts by mass of zinc nitrate hexahydrate is added and stirring is continued for 9 h. After precipitation overnight, 0.185 parts by mass of 2-methylimidazole is added and stirring is continued for 24 h. After washing three times with methanol, it is vacuum dried at 60℃ for 11 h. Then, it is calcined in a nitrogen tube furnace at 5℃ / min to 400℃ for 2 h. After cooling to room temperature, carbon nitride composite filler is obtained. 6.9 parts by mass of carbon nitride composite filler is mixed with 200 parts by mass of deionized water and ultrasonically dispersed for 30 min. Then, 21.5 parts by mass of 2-carboxyethylphenylphosphonic acid is added and ultrasonically dispersed for 1 h. Then, sodium hydroxide is added to adjust the pH to 5.5 and the temperature is raised to 85℃. Finally, 11 wt% aluminum sulfate solution is added dropwise at 2 s / drop and the reaction is kept at the temperature for 4 h under stirring. After filtration, washing, and drying, carbon nitride-based flame retardant filler is obtained.

[0070] The preparation method of porous nitrogen-doped carbon-based filler in composite filler is as follows: 0.66 parts by mass of folic acid is dissolved in 100 parts by mass of pure water. 0.34 parts by mass of 1 mol / L potassium hydroxide solution is added under stirring. The mixture is stirred until the folic acid is completely dissolved. Then, 1.2 parts by mass of potassium bromide is added. After complete dispersion, 0.625 parts by mass of zinc nitrate is added and mixed well. After standing at room temperature for 1 hour, the mixture is freeze-dried. Then, under nitrogen protection, the mixture is placed in a tube furnace and heated to 800℃ at a heating rate of 3℃ / min for 2 hours. After cooling to room temperature at a rate of 3℃ / min, the potassium bromide is removed by washing with deionized water and dried to obtain the porous nitrogen-doped carbon-based filler.

[0071] (Example 3)

[0072] A method for preparing a modified bio-based polymer, comprising the following steps:

[0073] (1) Weigh and mix the raw materials according to the following mass parts: 45-55 parts by mass of bio-based polyisocyanate monomer, 45-55 parts by mass of polyol mixture, 4-6 parts by mass of amino acid, 0.05-0.25 parts by mass of catalyst, 0.1-1 parts by mass of neutralizer, 3-7 parts by mass of chain extender, 24-30 parts by mass of composite filler, 1-3 parts by mass of antioxidant, 1.5-2.1 parts by mass of organosilicon coupling agent, 3-5 parts by mass of solvent, and 40-45 parts by mass of water;

[0074] (2) Under nitrogen protection, the polyol mixture weighed in step (1) is placed in the reactor and heated to 78-82°C. Then, bio-based polyisocyanate monomer and catalyst are added and reacted for 2-4 hours. Then, solvent and chain extender are added and stirred for another 2-4 hours. In this step, the polyol mixture is grafted with isocyanate through the reaction of active groups such as hydroxyl groups to obtain polyurethane prepolymer.

[0075] (3) Add a neutralizing agent to the polyurethane prepolymer obtained in step (2) after it has cooled to room temperature. React at room temperature for 15-25 minutes, then add deionized water, amino acids, and antioxidants. Continue stirring for 25-35 minutes. Next, add 0.1 times the mass of deionized water of ethanol, organosilicon coupling agent, and composite filler. Stir until evenly dispersed, then heat to 75-85°C under air conditions and use LEDs. 420nmThe mixture is then irradiated and stirred for 8–10 hours. During this time, the single-atom zinc loading in the carbon nitride-based flame retardant filler can form zinc-nitrogen coordination bonds with nitrogen atoms in the carbon nitride at the atomic level, forming active sites. Under light irradiation, the metal coordination centers can conduct electron transfer channels, adjust the band gap structure, effectively separate photogenerated electron-hole pairs, and catalyze oxygen in the air to form hydrogen peroxide in the reaction system. Subsequently, under the combined action of hydrogen peroxide and porous nitrogen-doped carbon-based filler, furfural is selectively oxidized to form maleic acid. Maleic acid reacts with amino groups in the system to form maleamide compounds. The temperature is then raised to 128–132℃ and the reaction is stirred for 11–13 hours. During this process, the maleamide compounds are dehydrated to form maleimide compounds, while citric acid and amino acids are dehydrated multiple times to form pyridone compounds, resulting in modified bio-based polymers.

[0076] The mass ratio of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, biomass polyol, and 4-hydroxymethyl-2-furan carbaldehyde in the polyol mixture is 13.5–16.5: 27–33: 4.5–5.5.

[0077] The preparation method of carbon nitride-based flame-retardant filler in composite fillers is as follows: 1 part by mass of carbon nitride is placed in 32 parts by mass of methanol and ultrasonically stirred for 1-2 hours. Then, 0.19-0.2 parts by mass of zinc nitrate hexahydrate is added and stirring is continued for 8-10 hours. After precipitation overnight, 0.18-0.19 parts by mass of 2-methylimidazole is added and stirring is continued for 24 hours. The mixture is then washed three times with methanol and vacuum dried at 60℃ for 10-12 hours. Subsequently, the temperature is increased to 400℃ at 5℃ / min and calcined in a nitrogen tube furnace for 1.5-2.5 hours. The mixture is then cooled. After reaching room temperature, carbon nitride composite filler was obtained. 6.8-7 parts by weight of carbon nitride composite filler were mixed with 200 parts by weight of deionized water and ultrasonically dispersed for 30 min. Then, 21-22 parts by weight of 2-carboxyethylphenylphosphonic acid were added and ultrasonically dispersed for another 1 h. Sodium hydroxide was then added to adjust the pH to 5-6 and the temperature was raised to 80-90℃. Finally, 10-12 wt% aluminum sulfate solution was added dropwise at 1-3 s / drop and the reaction was kept at the temperature for 3.5-4.5 h under stirring. After filtration, washing, and drying, carbon nitride-based flame retardant filler was obtained.

[0078] The preparation method of porous nitrogen-doped carbon-based filler in composite filler is as follows: 0.65-0.67 parts by mass of folic acid are dissolved in 100 parts by mass of pure water. Under stirring, 0.33-0.35 parts by mass of 1 mol / L potassium hydroxide solution are added and stirred until the folic acid is completely dissolved. Then, 1.1-1.3 parts by mass of potassium bromide are added and completely dispersed. Then, 0.62-0.63 parts by mass of zinc nitrate are added and mixed well. After standing at room temperature for 1 hour, the mixture is freeze-dried. Then, under nitrogen protection, the mixture is placed in a tube furnace and heated to 800℃ at a heating rate of 3℃ / min for 2 hours. After cooling to room temperature at a rate of 3℃ / min, the potassium bromide is removed by washing with deionized water and dried to obtain porous nitrogen-doped carbon-based filler.

[0079] (Comparative Example 1)

[0080] The difference between Comparative Example 1 and Example 2 is that the polyol mixture is obtained by mixing only bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid and biomass polyol; the remaining steps and components are the same as in Example 2.

[0081] (Comparative Example 2)

[0082] The difference between Comparative Example 2 and Example 2 is that the polyol mixture is obtained by mixing only biomass polyol and 4-hydroxymethyl-2-furan carbaldehyde; the remaining steps and components are the same as in Example 2.

[0083] (Comparative Example 3)

[0084] The difference between Comparative Example 3 and Example 2 is that only antioxidant 1010 is used as the antioxidant; the remaining steps and components are the same as in Example 2.

[0085] (Comparative Example 4)

[0086] The difference between Comparative Example 4 and Example 2 is that the modified bio-based polymer, by mass parts, comprises the following raw material components:

[0087] 50 parts by weight of bio-based polyisocyanate monomer, 50 parts by weight of polyol mixture, 5 parts by weight of amino acid, 0.15 parts by weight of catalyst, 0.6 parts by weight of neutralizer, 5 parts by weight of chain extender, 18 parts by weight of carbon nitride-based flame retardant filler, porous nitrogen-doped carbon-based filler, 2 parts by weight of antioxidant, 1.8 parts by weight of organosilicon coupling agent, 4 parts by weight of solvent, and 43 parts by weight of water; the remaining steps and components are the same as in Example 2.

[0088] (Comparative Example 5)

[0089] The difference between Comparative Example 5 and Example 2 is that the modified bio-based polymer, by mass parts, comprises the following raw material components:

[0090] 50 parts by weight of bio-based polyisocyanate monomer, 50 parts by weight of polyol mixture, 5 parts by weight of amino acid, 0.15 parts by weight of catalyst, 0.6 parts by weight of neutralizer, 5 parts by weight of chain extender, 9 parts by weight of porous nitrogen-doped carbon-based filler, 2 parts by weight of antioxidant, 1.8 parts by weight of organosilicon coupling agent, 4 parts by weight of solvent, and 43 parts by weight of water; the remaining steps and components are the same as in Example 2.

[0091] (Comparative Example 6)

[0092] The difference between Comparative Example 6 and Example 2 lies only in step (3), which is as follows: (3) a neutralizing agent is added to the polyurethane prepolymer obtained in step (2) after cooling to room temperature and reacting at room temperature for 20 min. Then, deionized water, amino acids, and antioxidants are added and stirred for another 30 min. Then, ethanol, organosilicon coupling agent, and composite filler (0.1 times the mass of deionized water) are added and stirred and dispersed evenly. The temperature is then raised to 80°C under air conditions and stirred for 9 h. Subsequently, the temperature is raised to 130°C and stirred for another 12 h to obtain the modified bio-based polymer. The remaining steps and components are the same as in Example 2.

[0093] (Comparative Example 7)

[0094] The difference between Comparative Example 7 and Example 2 lies only in step (3), specifically: (3) a neutralizing agent is added to the polyurethane prepolymer obtained in step (2) after cooling to room temperature, and the reaction is carried out at room temperature for 20 minutes. Then, deionized water, amino acids, and antioxidants are added, and the mixture is stirred for another 30 minutes. Next, ethanol (0.1 times the mass of deionized water), organosilicon coupling agent, and composite filler are added, and the mixture is stirred and dispersed evenly. Then, LEDs are used under air conditions. 420nm The mixture was irradiated with light and stirred for 9 hours. Then the temperature was raised to 130°C and the reaction was stirred for another 12 hours to obtain the modified bio-based polymer. The remaining steps and components were the same as in Example 2.

[0095] (Comparative Example 8)

[0096] The difference between Comparative Example 8 and Example 2 lies only in step (3), specifically: (3) a neutralizing agent is added to the polyurethane prepolymer obtained in step (2) after cooling to room temperature, and the mixture is reacted at room temperature for 20 minutes. Then, deionized water, amino acids, and antioxidants are added, and the mixture is stirred for another 30 minutes. Next, ethanol (0.1 times the mass of deionized water), organosilicon coupling agent, and composite filler are added, and the mixture is stirred and dispersed evenly. The mixture is then heated to 80°C under air conditions and an LED is used. 420nm The mixture was irradiated and stirred for 9 hours under light conditions to obtain the modified bio-based polymer; the remaining steps and components were the same as in Example 2.

[0097] (Example of the effect)

[0098] Mechanical properties: The tensile strength of the modified bio-based polymers prepared in the examples and comparative examples was tested according to GB / T 1040.1-2018;

[0099] Flame retardant properties: The modified bio-based polymers prepared in the examples and comparative examples were tested according to the oxygen index test in GB / T2406.

[0100] UV aging resistance: The modified bio-based polymers prepared in the examples and comparative examples were used to simulate the aging process of materials in nature using an accelerated UV aging test chamber. The ambient temperature was set to 50℃, the peak wavelength of ultraviolet radiation was 313nm, and the power of the ultraviolet fluorescent lamp was 0.06kW. The tensile strength change rate of the modified bio-based polymers prepared in the examples and comparative examples was tested according to GB / T1040.1-2018 after irradiation for 0h and 480h. The UV aging tensile strength change rate (%) = 100% * (tensile strength of modified bio-based polymer after irradiation for 0h - tensile strength of modified bio-based polymer after irradiation for 480h) / tensile strength of modified bio-based polymer after irradiation for 0h.

[0101] Table 1 below shows the performance test results of the modified bio-based polymers obtained in Examples 1-3 and Comparative Examples 1-8:

[0102] Table 1

[0103]

[0104] Table 1 shows that the modified bio-based polymers prepared in Examples 1-3 have good mechanical properties, flame retardancy, and UV aging resistance.

[0105] The only difference between Comparative Example 1 and Example 2 is that 4-hydroxymethyl-2-furanaldehyde was not added to the polyol mixture in Comparative Example 1. Maleimide polymer was not formed in the modified bio-based polymer. The mechanical properties and flame retardancy were weaker than those in Examples 1-3. The rapid decline in mechanical properties indicates that the catalytic oxidation in the subsequent mixing process damaged the mechanical properties of the modified bio-based polymer.

[0106] The only difference between Comparative Example 2 and Example 2 is that the polyol mixture in Comparative Example 2 did not contain bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphonic acid, thus it could not form a branched modified bio-based polymer. The dispersibility and crosslinking degree of the filler were affected, the mechanical properties decreased, and the flame retardancy was significantly weaker than that of Examples 1-3.

[0107] The only difference between Comparative Example 3 and Example 2 is that citric acid was not added as an antioxidant in Comparative Example 3. The UV protection performance of the modified bio-based polymer decreased, possibly because the modified bio-based polymer could not form pyridone compounds.

[0108] The only difference between Comparative Example 4 and Example 2 is that the raw material components of the modified bio-based polymer in Comparative Example 4 did not contain porous nitrogen-doped carbon-based fillers. The mechanical properties of the resulting modified bio-based polymer were significantly reduced. This may be due to the lack of physical crosslinking points, the failure to form maleimide polymers in the modified bio-based polymer, and the damage to the mechanical properties of the modified bio-based polymer caused by catalytic oxidation during the mixing process.

[0109] The only difference between Comparative Example 5 and Example 2 is that the raw material components of the modified bio-based polymer in Comparative Example 5 did not contain carbon nitride-based flame retardant filler. The mechanical properties and flame retardancy of the resulting modified bio-based polymer were reduced. This may be because the modified bio-based polymer did not form maleimide polymer and the catalytic oxidation during the subsequent mixing process damaged the mechanical properties of the modified bio-based polymer.

[0110] The only difference between Comparative Examples 6-8 and Example 2 is that step 3 of Comparative Example 6 was not carried out under light; the reaction under light in step 3 of Comparative Example 7 was carried out at room temperature; and the modified bio-based polymer obtained after the light reaction in step 3 of Comparative Example 8 was not dehydrated at high temperature, indicating that the pyridone was formed in the final dehydration reaction.

[0111] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A modified bio-based polymer, characterized in that, The raw material components include, by mass fraction: 45-55 parts of a bio-based polyisocyanate monomer, 45-55 parts of a polyol mixture, 4-6 parts of an amino acid, 0.05-0.25 parts of a catalyst, 0.1-1 parts of a neutralizing agent, 3-7 parts of a chain extender, 24-30 parts of a composite filler, 1-3 parts of an antioxidant, 1.5-2.1 parts of a silicone coupling agent, 3-5 parts of a solvent, and 40-45 parts of water; The polyol mixture is obtained by mixing bis(2-amino-4,6-di(hydroxyethylamino)-1,3,5-triazinyl) phosphinic acid, biomass polyol, and 4-hydroxymethyl-2-furfuraldehyde; the composite filler is obtained by mixing carbon nitride-based flame-retardant filler and porous nitrogen-doped carbon-based filler at a mass ratio of 2:1; the carbon nitride-based flame-retardant filler is prepared by in-situ chemical impregnation of zinc nitrate hexahydrate and 2-methylimidazole as precursors with carbon nitride, calcination under nitrogen, and modification with organic phosphinic acid salt; the porous nitrogen-doped carbon-based filler is prepared by calcination under an inert gas atmosphere using biomass folic acid as a carbon-nitrogen precursor, zinc nitrate as a pore former, and potassium bromide as a pore forming additive; The preparation steps of the modified bio-based polymer include: (1) each raw material component is weighed and dosed according to the corresponding mass fraction; (2) under nitrogen protection, the polyol mixture weighed in step (1) is placed in a reactor, heated to 78-82°C, then the bio-based polyisocyanate monomer and the catalyst are added, reacted for 2-4 h, then the solvent and the chain extender are added, and stirred for another 2-4 h to obtain a polyurethane prepolymer; (3) the polyurethane prepolymer obtained in step (2) is cooled to room temperature, the neutralizing agent is added, and reacted at room temperature for 15-25 min, then deionized water, 0.1 times the mass of deionized water, ethanol, amino acid, and antioxidant are added, and stirred for another 25-35 min, then the silicone coupling agent and the composite filler are added and stirred until uniformly dispersed, heated to 75-85°C under air, stirred under light for 8-10 h, then heated to 128-132°C and stirred for another 11-13 h to obtain the modified bio-based polymer.

2. A process for the preparation of a modified bio-based polymer as claimed in claim 1, characterized in that, The preparation steps include: (1) each raw material component is weighed and dosed according to the corresponding mass fraction; (2) under nitrogen protection, the polyol mixture weighed in step (1) is placed in a reactor, heated to 78-82°C, then the bio-based polyisocyanate monomer and the catalyst are added, reacted for 2-4 h, then the solvent and the chain extender are added, and stirred for another 2-4 h to obtain a polyurethane prepolymer; (3) adding a neutralizing agent to the polyurethane prepolymer obtained in step (2) at room temperature, and reacting for 15-25 min at room temperature, then continuously adding deionized water, 0.1 times the mass of deionized water of ethanol, an amino acid, and an antioxidant, and stirring for 25-35 min, then adding a silicone coupling agent and a composite filler, stirring to disperse uniformly, then heating to 75-85 DEG C under air, stirring for 8-10 h under light, then heating to 128-132 DEG C, and continuously stirring for 11-13 h, to obtain a modified bio-based polymer.

3. The method of preparing a modified bio-based polymer according to claim 2, characterized in that, The mass ratio of bis(2-amino-4,6-di(hydroxyethylamino)-1,3,5-triazinyl) phosphinic acid, biomass polyol, and 4-hydroxymethyl-2-furfural in the polyol mixture is 13.5-16.5:27-33:4.5-5.

5.

4. The method of preparing a modified bio-based polymer according to claim 2, characterized in that, The preparation method of the carbon nitride-based flame-retardant filler in the composite filler is as follows: 1 part by mass of carbon nitride is placed in 32 parts by mass of methanol and ultrasonically stirred for 1-2 h, then 0.19-0.2 parts by mass of zinc nitrate hexahydrate is added and stirring is continued for 8-10 h, and the mixture is allowed to stand overnight, then 0.18-0.19 parts by mass of 2-methylimidazole is added and stirring is continued for 24 h, then the mixture is washed with methanol for 3 times and vacuum dried at 60 DEG C for 10-12 h, then the mixture is calcined in a nitrogen tube furnace at 400 DEG C at a temperature increasing rate of 5 DEG C / min for 1.5-2.5 h, and after cooling to room temperature, a carbon nitride composite filler is obtained; 6.8-7 parts by mass of the carbon nitride composite filler is mixed with 200 parts by mass of deionized water, and ultrasonically dispersed for 30 min, then 21-22 parts by mass of 2-carboxyethyl phenyl phosphinic acid is added and ultrasonically stirred for 1 h, then sodium hydroxide is added to adjust the pH to 5-6 and the temperature to 80-90 DEG C, finally 10-12 wt% of an aluminum sulfate solution is added dropwise at a rate of 1-3 s / drop, and the mixture is allowed to react for 3.5-4.5 h under stirring, then filtered, washed, and dried to obtain a carbon nitride-based flame-retardant filler.

5. The method of preparing a modified bio-based polymer according to claim 2, characterized in that, The preparation method of the porous nitrogen-doped carbon-based filler in the composite filler is as follows: 0.65-0.67 parts by mass of folic acid is dissolved in 100 parts by mass of pure water, and 0.33-0.35 parts by mass of 1 mol / L potassium hydroxide solution is added under stirring until the folic acid is completely dissolved, then 1.1-1.3 parts by mass of potassium bromide is added, and after complete dispersion, 0.62-0.63 parts by mass of zinc nitrate is added and mixed and shaken, and the mixture is allowed to stand at room temperature for 1 h and then freeze-dried, then the mixture is placed in a tube furnace under nitrogen protection, and calcined at 800 DEG C at a temperature increasing rate of 3 DEG C / min for 2 h, and then cooled to room temperature at a temperature decreasing rate of 3 DEG C / min, then the mixture is washed with deionized water to remove the potassium bromide, and dried to obtain a porous nitrogen-doped carbon-based filler.

6. The method of preparing a modified bio-based polymer according to claim 2, characterized in that, The illumination source employs LEDs 365nm or LEDs 420nm .

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