Modified bio-based polymer and preparation method thereof

Abstract

The invention discloses a modified bio-based polymer and a preparation method thereof, and belongs to the technical field of high-molecular polymers. The modified bio-based polymer prepared by the invention comprises the following raw material components: a bio-based polyisocyanate monomer, a polyol mixture, amino acid, a catalyst, a neutralizer, a chain extender, a composite filler, an antioxidant and an organic silicon coupling agent, wherein the polyol mixture is a mixture of bis (2-amino-4, 6-bis (hydroxyethyl amino)-1, 3, 5-triazinyl) phosphinic acid, biomass polyol and 4-hydroxymethyl-2-furan formaldehyde, and the catalyst is a mixture of a catalyst, a catalyst and a catalyst. The composite filler is obtained by mixing a carbon nitride-based flame-retardant filler and a porous nitrogen-doped carbon-based filler; the modified bio-based polymer prepared by the preparation method disclosed by the invention is relatively good in flame retardance and relatively good in mechanical property.

Description

Technical Field

[0001] The present invention relates to a modified bio - based polymer and a preparation method thereof. Background Art

[0002] With the increasingly strict global environmental protection regulations, finding environmentally friendly materials has become an important research direction. Against this background, bio - based polymers have gradually become a research hotspot in the field of materials science due to their renewability and environmental friendliness. In particular, bio - based polyurethane (Bio - PU) has shown great application potential in the fields of textiles, medicine, packaging, etc. due to its excellent degradability and biocompatibility.

[0003] However, traditional bio - based polyurethane molecules contain a large number of hydrocarbon structures in their molecular chains. These structures make the material extremely flammable and release toxic smoke during combustion, posing a serious threat to human health and environmental safety. Although there have been studies attempting to improve its flame - retardant performance by adding bio - based flame retardants (such as lignin, cellulose derivatives, etc.), the effects are not ideal. On the one hand, the flame - retardant efficiency of such flame retardants is relatively low; on the other hand, their compatibility with the polyurethane matrix is poor, resulting in poor uniformity and stability of the composite material. More seriously, excessive addition of flame retardants may cause a significant decrease in the mechanical properties of the material, further restricting its application scope.

[0004] In addition to the flame - retardant problem, bio - based raw materials (such as polylactic acid polyol) also have certain limitations. Such raw materials usually have a relatively high molecular chain rigidity and a low crystallinity, resulting in the finally synthesized polyurethane material showing relatively large brittleness and low heat resistance. Taking pure polylactic acid polyurethane as an example, its tensile strength is usually less than 20 MPa, far lower than the standard requirements for industrial applications.

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

[0006] The object of the present invention is to provide a modified bio - based polymer and a preparation method thereof to solve the technical problems mentioned in the above background art.

[0007] The technical solution for achieving the object of the present invention is as follows:

[0008] In the first aspect, the present invention provides a modified bio-based polymer. By mass fraction, the raw material components include: 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 part 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 organosilane 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] Further, the polyol mixture is obtained by mixing bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphinic acid, biomass polyol, and 4-hydroxymethyl-2-furaldehyde; the biomass polyol includes any one of palm oil polyol, cashew shell oil polyol, soybean oil polyol, polylactic acid polyol, and castor oil polyol.

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

[0012] The catalyst is any one of 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 neutralizer 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 is acetone.

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

[0018] Further, 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 an organic phosphite.

[0019] Further, the porous nitrogen-doped carbon-based filler is obtained by using biomass folic acid as a carbon and nitrogen precursor, zinc nitrate hexahydrate as a pore former, potassium bromide as a pore-forming aid, and calcination in an inert gas atmosphere.

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

[0021] (1) Weigh and proportion each raw material component according to mass parts;

[0022] (2) Under the condition of nitrogen protection, put the polyol mixture weighed in step (1) into a reactor, heat it up to 78 - 82 °C, then add a bio-based polyisocyanate monomer and a catalyst, and react for 2 - 4 h. Subsequently, add a solvent and a chain extender, and continue stirring for 2 - 4 h. In this step, the polyol mixture reacts and grafts through active groups such as hydroxyl groups with isocyanate to obtain a polyurethane prepolymer;

[0023] (3) Add a neutralizing agent to the polyurethane prepolymer obtained in step (2) cooled to room temperature and react at room temperature for 15 - 25 min. Then, continue to add deionized water, an amino acid, and an antioxidant, and continue stirring for 25 - 35 min. Then, add ethanol, a silicone coupling agent, and a composite filler which are 0.1 times the mass of the deionized water, stir and disperse evenly, and then heat up to 75 - 85 °C under air conditions and stir for 8 - 10 h under light conditions. At this time, the loading of single-atom zinc in the carbon nitride-based flame retardant filler can form a zinc-nitrogen coordination bond with nitrogen atoms in carbon nitride at the atomic level to form active sites. Under light conditions, the metal coordination center can conduct an electron transfer channel, adjust the band gap structure, effectively separate photo-generated electron-hole pairs, catalyze oxygen in the air, form hydrogen peroxide in the reaction system, and then catalyze the selective oxidation of furfural to form maleic acid under the combined action of hydrogen peroxide and the porous nitrogen-doped carbon-based filler. Maleic acid reacts with amino groups in the system to form a maleamide compound, and then heat up to 128 - 132 °C and continue stirring and reacting for 11 - 13 h. During this process, the maleamide compound dehydrates to form a maleimide compound, and at the same time, citric acid and the amino acid dehydrate multiple times to form a pyridone-based compound, obtaining the modified bio-based polymer.

[0024] Some of the principles in step (3) are as follows:

[0025]

[0026] Furthermore, the mass ratio of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl) phosphinic acid, biomass polyol, and 4-hydroxymethyl-2-furaldehyde 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: Put 1 part by mass of carbon nitride into 32 parts by mass of methanol, ultrasonically stir for 1 - 2 h, then add 0.19 - 0.2 part by mass of zinc nitrate hexahydrate and continue stirring for 8 - 10 h, age overnight, then add 0.18 - 0.19 part by mass of 2-methylimidazole, continue stirring for 24 h, then wash with methanol 3 times and vacuum dry at 60 °C for 10 - 12 h, then heat to 400 °C at a rate of 5 °C / min and calcine in a nitrogen tube furnace for 1.5 - 2.5 h, after cooling to room temperature, obtain the carbon nitride composite filler; Mix 6.8 - 7 parts by mass of the carbon nitride composite filler with 200 parts by mass of deionized water, ultrasonically disperse for 30 min, then add 21 - 22 parts by mass of 2-carboxyethylphenylphosphinic acid, continue ultrasonic treatment for 1 h, then add sodium hydroxide to adjust the pH to 5 - 6 and heat to 80 - 90 °C, finally dropwise add a 10 - 12 wt% aluminum sulfate solution at a rate of 1 - 3 drops / s, and keep the reaction at a constant temperature under stirring for 3.5 - 4.5 h, filter, wash, and dry to obtain the carbon nitride-based flame retardant filler.

[0028] Further, the preparation method of the porous nitrogen-doped carbon-based filler in the composite filler is as follows: Dissolve 0.65 - 0.67 part by mass of folic acid in 100 parts by mass of pure water, add 0.33 - 0.35 part by mass of 1 mol / L potassium hydroxide solution under stirring until the folic acid is completely dissolved, then add 1.1 - 1.3 parts by mass of potassium bromide, after complete dispersion, add 0.62 - 0.63 part by mass of zinc nitrate and mix well, let stand at room temperature for 1 h and then freeze-dry, then under the condition of nitrogen protection, put it into a tube furnace, heat to 800 °C at a heating rate of 3 °C / min and calcine for 2 h, then cool to room temperature at a rate of 3 °C / min, then wash with deionized water to remove potassium bromide, and dry to obtain the porous nitrogen-doped carbon-based filler.

[0029] Further, the light source for illumination uses an LED 365nm or an LED 420nm 。

[0030] Adopting the above technical solutions, the present invention has the following beneficial effects:

[0031] (1) The modified bio-based polymer disclosed in the present invention, by mass, the raw material components include: 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 part by mass of catalyst, 0.1 - 1 part 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; The modified bio-based polymer prepared from the foregoing formula has better flame retardancy, antioxidant property, flame retardancy, anti-ultraviolet aging property, and mechanical properties.

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

[0033] (3) The amino acids of the present invention at least adopt cysteine, and the antioxidant adopts a mixture of citric acid and antioxidant 1010. On the one hand, it can endow the bio-based polymer with good antioxidant properties. On the other hand, citric acid undergoes multiple dehydration reactions with amino acids to form a compound containing a conjugated structure pyridone group, effectively endowing the modified bio-based polymer with good UV resistance.

[0034] (4) The composite filler of the present invention is obtained by mixing a carbon nitride-based flame retardant filler and a porous nitrogen-doped carbon-based filler. Among them, 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 treatment under nitrogen and modification with an organic hypophosphite. The carbon nitride lamellae play a physical barrier role, blocking the release of smoke particles and reducing the total smoke generation amount during combustion; the introduction of the organic hypophosphite decomposes to form phosphoric acid-containing salts during combustion, promoting the formation of char residues in the matrix, inhibiting the exchange of heat and oxygen inside and outside the matrix, and the dense char layer also reduces the thermal decomposition rate of the matrix and delays the further cracking of the material; at the same time, phosphorus-oxygen free radicals are generated and the gas-phase active free radicals are quenched through the free radical capture effect, and a large amount of incombustible gases (such as CO2, NH3, H2O, etc.) are also generated in the gas-phase products, absorbing the combustion heat and diluting the oxygen concentration at the same time, destroying the combustion microenvironment and achieving good flame retardant effects; after adding the porous nitrogen-doped carbon-based filler, it can effectively increase the mechanical properties of the modified bio-based polymer as physical cross-linking points.

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

[0036] (6) When preparing the modified biobased polymer of the present invention, after adding the organosilane coupling agent and the composite filler, the reaction is carried out under light and air conditions, and then the dehydration reaction is carried out. 2-Furaldehyde in the modified biobased polymer is catalytically oxidized to maleic acid under the combined action of the composite filler. The maleic acid reacts with the unreacted amino groups in the system to form maleimide, which increases the crosslinking density of the modified biobased polymer, compensates for the influence on the mechanical properties of the system during the aforementioned catalytic oxidation process, and further improves the mechanical properties and flame retardancy of the modified biobased polymer. Detailed implementation manners

[0037] In order to better understand the above technical solution, the following will describe the above technical solution in detail in combination with specific implementation manners.

[0038] Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

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

[0040] Some raw materials of the embodiments and comparative examples of the present invention are as follows:

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

[0042] The preparation steps of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphinic acid are as follows: Stir and mix 6.2 parts by mass of cyanuric chloride solid and 8.9 parts by mass of acetone evenly, and then simultaneously dropwise add 2.29 parts by mass of 25 wt% ammonia water and 1.345 parts by mass of 5 M sodium hydroxide aqueous solution at a rate of 2 - 4 drops / s, react at 0 - 5 °C for 3 h, then raise the temperature to 50 °C, and simultaneously dropwise add 2.054 parts by mass of ethanolamine and 1.345 parts by mass of 5 M sodium hydroxide aqueous solution at a rate of 2 - 4 drops / s. After continuously reacting for 8 h, evaporate acetone at 58 °C, then raise the temperature to 90 °C, and again simultaneously dropwise add 2.054 parts by mass of ethanolamine and 1.345 parts by mass of 5 M sodium hydroxide aqueous solution at a rate of 2 - 4 drops / s, continue to react for 8 h. After cooling to room temperature, filter, wash repeatedly with acetone and deionized water for 3 times, and dry in an oven at 50 °C for 12 h to obtain intermediate A; Mix 3.212 parts by mass of intermediate A, 0.474 parts by mass of paraformaldehyde, and 0.795 parts by mass of sodium hypophosphite, add 20 parts by mass of glacial acetic acid, raise the temperature to 120 °C and stir to react for 30 min, then add 1.53 parts by mass of acetic anhydride. After dropping, continue to stir and react for 7 h. After the reaction is completed, cool to room temperature, wash repeatedly with deionized water, filter by suction to obtain a white solid, and dry in an oven for 12 h to obtain bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphinic acid;

[0043] Among them, the preparation mechanism of bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl)phosphinic 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)phosphinic acid, bio-based polyol, and 4-hydroxymethyl-2-furaldehyde; The bio-based polyol uses 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 neutralizer is triethylamine.

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

[0052] The solvent used is acetone.

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

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

[0055] (Example 1)

[0056] A preparation method of a modified bio-based polymer, the preparation steps include:

[0057] (1) Weigh and mix the raw material components according to the following mass fractions: 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 part by mass of catalyst, 0.1 part 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, 40 parts by mass of water;

[0058] (2) Under the protection of nitrogen, put the weighed polyol mixture in step (1) into a reactor, heat up to 78 °C, then add the bio-based polyisocyanate monomer and catalyst, react for 2 h, then add the solvent and chain extender, and continue stirring for 2 h. In this step, the polyol mixture reacts and grafts through active groups such as hydroxyl groups with isocyanate to obtain a polyurethane prepolymer;

[0059] (3) Add the neutralizer to the polyurethane prepolymer obtained in step (2) cooled to room temperature and react at room temperature for 15 min, then continue to add deionized water, amino acid, antioxidant, and continue stirring for 25 min. Then add ethanol with a mass 0.1 times that of deionized water, organosilicon coupling agent, and composite filler, stir and disperse evenly, then heat up to 75 °C under air conditions, and use LED 365nm for light irradiation. Under the light irradiation condition, stir for 8 h. At this time, the single-atom zinc loaded in the carbon nitride-based flame retardant filler can form a zinc-nitrogen coordination bond with the nitrogen atoms in the carbon nitride at the atomic level to form active sites. Under the light irradiation condition, the metal coordination center can conduct the electron transfer channel, adjust the band gap structure, effectively separate the photo-generated electron-hole pairs, catalyze the oxygen in the air, form hydrogen peroxide in the reaction system, and then under the combined action of hydrogen peroxide and the porous nitrogen-doped carbon-based filler, catalyze the selective oxidation of furfural to form maleic acid. Maleic acid reacts with the amino group in the system to form a maleamide compound, and then heat up to 128 °C and continue stirring and reacting for 11 h. During this process, the maleamide compound dehydrates to form a maleimide compound, and at the same time, citric acid and amino acid dehydrate multiple times to form a pyridone-based compound, obtaining the modified bio-based polymer.

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

[0061] The preparation method of the carbon nitride-based flame retardant filler in the composite filler is as follows: Put 1 part by mass of carbon nitride into 32 parts by mass of methanol and stir ultrasonically for 1 h. Then add 0.19 part by mass of zinc nitrate hexahydrate and continue stirring for 8 h. Let it precipitate overnight. Then add 0.18 part by mass of 2-methylimidazole and continue stirring for 24 h. Then wash it with methanol 3 times and dry it in vacuo at 60 °C for 10 h. Then heat it to 400 °C at a rate of 5 °C / min and calcine it in a nitrogen tube furnace for 1.5 h. After cooling to room temperature, carbon nitride composite filler is obtained; Mix 6.8 parts by mass of the carbon nitride composite filler with 200 parts by mass of deionized water, disperse it ultrasonically for 30 min. Then add 21 parts by mass of 2-carboxyethylphenylphosphinic acid and continue ultrasonic treatment for 1 h. Then add sodium hydroxide to adjust the pH to 5 and heat it to 80 °C. Finally, dropwise add 10 wt% aluminum sulfate solution at a rate of 1 drop / s and keep the reaction warm under stirring for 3.5 h. Filter, wash, and dry to obtain the carbon nitride-based flame retardant filler.

[0062] The preparation method of the porous nitrogen-doped carbon-based filler in the composite filler is as follows: Dissolve 0.65 part by mass of folic acid in 100 parts by mass of pure water. Add 0.33 part by mass of 1 mol / L potassium hydroxide solution under stirring and stir until the folic acid is completely dissolved. Then add 1.1 parts by mass of potassium bromide. After complete dispersion, add 0.62 part by mass of zinc nitrate and mix well. Let it stand at room temperature for 1 h and then freeze-dry. Then, under the protection of nitrogen, put it into a tube furnace and heat it to 800 °C at a heating rate of 3 °C / min and calcine for 2 h, and then cool it to room temperature at a rate of 3 °C / min. Then wash it with deionized water to remove potassium bromide and dry it to obtain the porous nitrogen-doped carbon-based filler.

[0063] (Example 2)

[0064] A preparation method of a modified bio-based polymer, the preparation steps include:

[0065] (1) Weigh and mix the following raw material components 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 part by mass of catalyst, 0.6 part 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 the condition of nitrogen protection, put the weighed polyol mixture in step (1) into a reactor, heat up to 80 °C, then add the bio-based polyisocyanate monomer and catalyst, react for 3 h, then add the solvent and chain extender, and continue stirring for 3 h. In this step, the polyol mixture reacts and grafts through active groups such as hydroxyl groups with isocyanate to obtain a polyurethane prepolymer;

[0067] (3) Add a neutralizing agent to the polyurethane prepolymer obtained in step (2) cooled to room temperature and react at room temperature for 20 min, then continue to add deionized water, amino acid, antioxidant, and continue stirring for 30 min. Then add ethanol, organosilicon coupling agent, and composite filler which are 0.1 times the mass of deionized water, stir and disperse evenly, heat up to 80 °C under air conditions, and use LED 420nm for light irradiation, and stir for 9 h under light irradiation conditions. At this time, the loading of single-atom zinc in the carbon nitride-based flame retardant filler can form a zinc-nitrogen coordination bond with nitrogen atoms in carbon nitride at the atomic level to form active sites. Under light irradiation conditions, the metal coordination center can conduct the electron transfer channel, adjust the band gap structure, effectively separate the photo-generated electron-hole pairs, catalyze oxygen in the air, form hydrogen peroxide in the reaction system, and then catalyze the selective oxidation of furfural to form maleic acid under the combined action of hydrogen peroxide and the porous nitrogen-doped carbon-based filler. Maleic acid reacts with amino groups in the system to form maleamide compounds, and then heat up to 130 °C and continue stirring and reacting for 12 h. During this process, the maleamide compounds dehydrate to form maleimide compounds, and at the same time, citric acid and amino acids dehydrate multiple times to form pyridone-based compounds, obtaining a modified bio-based polymer.

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

[0069] The preparation method of the carbon nitride-based flame retardant filler in the composite filler is as follows: Put 1 part by mass of carbon nitride into 32 parts by mass of methanol, stir ultrasonically for 1.5 h, then add 0.195 part by mass of zinc nitrate hexahydrate and continue stirring for 9 h, precipitate overnight, then add 0.185 part by mass of 2-methylimidazole, continue stirring for 24 h, then wash with methanol 3 times and vacuum dry at 60 °C for 11 h, then heat up to 400 °C at a rate of 5 °C / min and calcine in a nitrogen tube furnace for 2 h. After cooling to room temperature, obtain the carbon nitride composite filler; Mix 6.9 parts by mass of the carbon nitride composite filler with 200 parts by mass of deionized water, disperse ultrasonically for 30 min, then add 21.5 parts by mass of 2-carboxyethylphenylphosphinic acid, continue ultrasonic for 1 h, then add sodium hydroxide to adjust the pH to 5.5 and heat up to 85 °C, and finally dropwise add 11 wt% aluminum sulfate solution at a rate of 2 drops / s, keep the temperature and react under stirring for 4 h, filter, wash, and dry to obtain the carbon nitride-based flame retardant filler.

[0070] The preparation method of the porous nitrogen-doped carbon-based filler in the composite filler is as follows: Dissolve 0.66 parts by mass of folic acid in 100 parts by mass of pure water, add 0.34 parts by mass of 1 mol / L potassium hydroxide solution under stirring conditions, stir until the folic acid is completely dissolved, then add 1.2 parts by mass of potassium bromide, add 0.625 parts by mass of zinc nitrate after complete dispersion and mix well, let it stand at room temperature for 1 h and then freeze-dry. Then, under the protection of nitrogen, put it into a tubular furnace and heat it to 800 °C at a heating rate of 3 °C / min and calcine for 2 h, and then cool it to room temperature at a rate of 3 °C / min. Subsequently, wash it with deionized water to remove potassium bromide and dry it to obtain the porous nitrogen-doped carbon-based filler.

[0071] (Example 3)

[0072] A preparation method of a modified bio-based polymer, the preparation steps include:

[0073] (1) Weigh and mix the raw material components 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 part 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, 40 - 45 parts by mass of water;

[0074] (2) Under the protection of nitrogen, put the weighed polyol mixture in step (1) into a reactor, heat it to 78 - 82 °C, then add the bio-based polyisocyanate monomer and catalyst, react for 2 - 4 h, then add the solvent and chain extender, and continue to stir for 2 - 4 h. In this step, the polyol mixture reacts and grafts through active groups such as hydroxyl groups with isocyanate to obtain a polyurethane prepolymer;

[0075] (3) Add the neutralizer to the polyurethane prepolymer obtained in step (2) cooled to room temperature and react at room temperature for 15 - 25 min, then continue to add deionized water, amino acid, antioxidant, and continue to stir for 25 - 35 min. Then add ethanol which is 0.1 times the mass of deionized water, organosilicon coupling agent, and composite filler, stir and disperse evenly, and then heat it to 75 - 85 °C under air conditions, and use LED 420nmPerform illumination and stir for 8 - 10 h under illumination conditions. At this time, the loading of single - atom 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 illumination conditions, the metal coordination center can conduct the electron transfer channel, adjust the band - gap structure, effectively separate photo - generated electron - hole pairs, catalyze oxygen in the air, form hydrogen peroxide in the reaction system, and then catalyze the selective oxidation of furfural to form maleic acid under the combined action of hydrogen peroxide and porous nitrogen - doped carbon - based filler. Maleic acid reacts with amino groups in the system to form maleamide compounds, and then the temperature is raised to 128 - 132 °C and stirring reaction continues for 11 - 13 h. During this process, maleamide compounds dehydrate to form maleimide compounds, and at the same time, citric acid and amino acids dehydrate multiple times to form pyridone - based compounds, obtaining the modified bio - based polymer.

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

[0077] The preparation method of the carbon nitride - based flame - retardant filler in the composite filler is as follows: Put 1 part by mass of carbon nitride into 32 parts by mass of methanol and stir ultrasonically for 1 - 2 h, then add 0.19 - 0.2 part by mass of zinc nitrate hexahydrate and continue stirring for 8 - 10 h, precipitate overnight, then add 0.18 - 0.19 part by mass of 2 - methylimidazole and continue stirring for 24 h. Then wash with methanol 3 times and vacuum - dry at 60 °C for 10 - 12 h. Then heat up to 400 °C at a rate of 5 °C / min and calcine in a nitrogen - tube furnace for 1.5 - 2.5 h. After cooling to room temperature, obtain the carbon nitride composite filler; Mix 6.8 - 7 parts by mass of the carbon nitride composite filler with 200 parts by mass of deionized water, disperse ultrasonically for 30 min, then add 21 - 22 parts by mass of 2 - carboxyethylphenylphosphinic acid and continue ultrasonic treatment for 1 h. Then add sodium hydroxide to adjust the pH to 5 - 6 and heat up to 80 - 90 °C. Finally, drop - add a 10 - 12 wt% aluminum sulfate solution at a rate of 1 - 3 drops / s and keep the reaction under stirring for 3.5 - 4.5 h. Filter, wash, and dry to obtain the carbon nitride - based flame - retardant filler.

[0078] The preparation method of the porous nitrogen-doped carbon-based filler in the composite filler is as follows: Dissolve 0.65 - 0.67 parts by mass of folic acid in 100 parts by mass of pure water, add 0.33 - 0.35 parts by mass of 1 mol / L potassium hydroxide solution under stirring conditions, stir until the folic acid is completely dissolved, then add 1.1 - 1.3 parts by mass of potassium bromide, after complete dispersion, add 0.62 - 0.63 parts by mass of zinc nitrate and mix well. Let it stand at room temperature for 1 h and then freeze-dry. Then, under the condition of nitrogen protection, put it into a tube furnace, heat it to 800 °C at a heating rate of 3 °C / min and calcine for 2 h, and then cool it to room temperature at a rate of 3 °C / min. Subsequently, wash it with deionized water to remove potassium bromide and dry it to obtain the 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 only mixed by bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl) phosphinic acid and biomass polyol; the remaining steps and components are the same as those in Example 2.

[0081] (Comparative Example 2)

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

[0085] (Comparative Example 4)

[0086] The difference between Comparative Example 4 and Example 2 is that the raw material components of the modified bio-based polymer by mass fraction include:

[0087] 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, 18 parts by mass of carbon nitride-based flame retardant filler, porous nitrogen-doped carbon-based filler, 2 parts by mass of antioxidant, 1.8 parts by mass of organosilicon coupling agent, 4 parts by mass of solvent, 43 parts by mass of water; the remaining steps and components are the same as those in Example 2.

[0088] (Comparative Example 5)

[0089] The difference between Comparative Example 5 and Example 2 is that the raw material components of the modified bio-based polymer by mass fraction include:

[0090] 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 part by mass of catalyst, 0.6 part by mass of neutralizer, 5 parts by mass of chain extender, 9 parts by mass of porous nitrogen-doped carbon-based filler, 2 parts by mass of antioxidant, 1.8 parts by mass of organosilicon coupling agent, 4 parts by mass of solvent, 43 parts by mass of water; the remaining steps and components are the same as those in Example 2.

[0091] (Comparative Example 6)

[0092] The difference between Comparative Example 6 and Example 2 is only in step (3), specifically: (3) After adding the neutralizer to the polyurethane prepolymer obtained in step (2) cooled to room temperature and reacting at room temperature for 20 min, deionized water, amino acid, and antioxidant were added and stirring was continued for 30 min. Then, ethanol, organosilicon coupling agent, and composite filler, which were 0.1 times the mass of the deionized water, were added and stirred until evenly dispersed. Then, the temperature was raised to 80 °C under air conditions and stirring reaction was carried out for 9 h. Subsequently, the temperature was raised to 130 °C and stirring reaction was continued for 12 h to obtain a modified bio-based polymer; the remaining steps and components are the same as those in Example 2.

[0093] (Comparative Example 7)

[0094] The difference between Comparative Example 7 and Example 2 is only in step (3), specifically: (3) After adding the neutralizer to the polyurethane prepolymer obtained in step (2) cooled to room temperature and reacting at room temperature for 20 min, deionized water, amino acid, and antioxidant were added and stirring was continued for 30 min. Then, ethanol, organosilicon coupling agent, and composite filler, which were 0.1 times the mass of the deionized water, were added and stirred until evenly dispersed. Then, LED 420nm was used for illumination, and stirring reaction was carried out for 9 h under the illumination condition. Subsequently, the temperature was raised to 130 °C and stirring reaction was continued for 12 h to obtain a modified bio-based polymer; the remaining steps and components are the same as those in Example 2.

[0095] (Comparative Example 8)

[0096] The difference between Comparative Example 8 and Example 2 is only in step (3), specifically: (3) After adding the neutralizer to the polyurethane prepolymer obtained in step (2) cooled to room temperature and reacting at room temperature for 20 min, deionized water, amino acid, and antioxidant were added and stirring was continued for 30 min. Then, ethanol, organosilicon coupling agent, and composite filler, which were 0.1 times the mass of the deionized water, were added and stirred until evenly dispersed. Then, the temperature was raised to 80 °C under air conditions and LED 420nm was used for illumination, and stirring reaction was carried out for 9 h under the illumination condition to obtain a modified bio-based polymer; the remaining steps and components are the same as those in Example 2.

[0097] (Effect Example)

[0098] Mechanical properties: The tensile strength of the modified biobased polymers prepared in the examples and comparative examples was tested with reference to GB / T 1040.1-2018.

[0099] Flame retardant properties: The oxygen index of the modified biobased polymers prepared in the examples and comparative examples was tested with reference to GB / T 2406.

[0100] Anti-ultraviolet aging properties: The modified biobased polymers prepared in the examples and comparative examples were used in an ultraviolet accelerated aging test chamber to simulate the aging process of the materials in nature. The environmental temperature was set at 50 °C, the peak wavelength of ultraviolet radiation was 313 nm, and the power of the ultraviolet fluorescent lamp was 0.06 kW. The tensile strength change rates of the modified biobased polymers prepared in the examples and comparative examples were tested with reference to GB / T 1040.1-2018 at 0 h and 480 h of irradiation. The ultraviolet aging tensile strength change rate (%) = 100% * (tensile strength of the modified biobased polymer at 0 h of irradiation - tensile strength of the modified biobased polymer at 480 h of irradiation) / tensile strength of the modified biobased polymer at 0 h of irradiation.

[0101] The following Table 1 shows the performance test results of the modified biobased polymers prepared in Examples 1-3 and Comparative Examples 1-8:

[0102] Table 1

[0103]

[0104] It can be seen from Table 1 that the modified biobased polymers prepared in Examples 1-3 have good mechanical properties, flame retardancy, and anti-ultraviolet aging properties.

[0105] The difference between Comparative Example 1 and Example 2 is only that 4-hydroxymethyl-2-furaldehyde was not added to the polyol mixture in Comparative Example 1, and no maleimide polymer was formed in the prepared modified biobased polymer. The mechanical properties and flame retardancy are weaker than those of Examples 1-3. The relatively fast decline in mechanical properties indicates that the catalytic oxidation during the subsequent mixing process damaged the mechanical properties of the modified biobased polymer.

[0106] The difference between Comparative Example 2 and Example 2 is only that bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl) phosphinic acid was not added to the polyol mixture in Comparative Example 2, and a modified biobased polymer with a branched structure could not be formed. The dispersion of the filler and the degree of crosslinking were both affected, resulting in a decline in mechanical properties and significantly weaker flame retardancy than those of Examples 1-3.

[0107] The difference between Comparative Example 3 and Example 2 is only that citric acid was not added to the antioxidant in Comparative Example 3, and the anti-ultraviolet performance of the prepared modified biobased polymer decreased, probably because pyridone compounds could not be formed in the modified biobased polymer.

[0108] The difference between Comparative Example 4 and Example 2 is only that the raw material components of the modified bio-based polymer in Comparative Example 4 did not add porous nitrogen-doped carbon-based filler, and the mechanical properties of the prepared modified bio-based polymer decreased significantly. This may be due to the lack of physical crosslinking points, the failure to form maleimide polymer in the modified bio-based polymer, and the catalytic oxidation during the mixing process damaging the mechanical properties of the modified bio-based polymer.

[0109] The difference between Comparative Example 5 and Example 2 is only that the raw material components of the modified bio-based polymer in Comparative Example 5 did not add carbon nitride-based flame retardant filler, and the mechanical properties and flame retardancy of the prepared modified bio-based polymer decreased. This may be due to the failure to form maleimide polymer in the prepared modified bio-based polymer and the catalytic oxidation during the subsequent mixing process damaging the mechanical properties of the modified bio-based polymer.

[0110] The differences between Comparative Examples 6-8 and Example 2 are only that: in Comparative Example 6, the reaction in Step 3 was not carried out under light; in Comparative Example 7, the reaction in Step 3 under light was carried out at room temperature; in Comparative Example 8, high-temperature dehydration was not carried out after the light reaction in Step 3. The mechanical properties, flame retardancy and UV resistance of the prepared modified bio-based polymer decreased, indicating that pyridone was formed in the final dehydration reaction.

[0111] The specific embodiments described above have further elaborated on the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A modified biobased polymer, characterized in that, By mass fraction, the raw material components include: 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 part 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.

2. The modified biobased polymer according to claim 1, wherein, The polyol mixture is obtained by mixing bis(2-amino-4,6-bis(hydroxyethylamino)-1,3,5-triazinyl) phosphinic acid, biomass polyol, and 4-hydroxymethyl-2-furaldehyde.

3. The modified biobased polymer according to claim 1, wherein, The composite filler is obtained by mixing a carbon nitride-based flame retardant filler and a porous nitrogen-doped carbon-based filler in a mass ratio of 2:

1.

4. The modified biobased polymer according to claim 3, characterized in that, 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 phosphite.

5. The modified biobased polymer according to claim 3, wherein The porous nitrogen-doped carbon-based filler is obtained by using biomass folic acid as a carbon and nitrogen precursor, zinc nitrate hexahydrate as a pore former, potassium bromide as a pore-forming aid, and calcination in an inert gas atmosphere.

6. A method for preparing a modified biobased polymer according to any one of claims 1 to 5, characterized in that, The preparation steps include: (1) Weigh and mix each raw material component according to the mass fraction. (2) Under nitrogen protection, put the weighed polyol mixture in step (1) into a reactor, heat up to 78 - 82 °C, then add the bio-based polyisocyanate monomer and catalyst, react for 2 - 4 h, then add the solvent and chain extender, and continue stirring for 2 - 4 h to obtain a polyurethane prepolymer. (3) Add the neutralizer to the polyurethane prepolymer obtained in step (2) cooled to room temperature and react at room temperature for 15 - 25 min, then continue to add deionized water, ethanol 0.1 times the mass of deionized water, amino acid, and antioxidant, continue stirring for 25 - 35 min, then add the organosilicon coupling agent and composite filler, stir and disperse evenly, heat up to 75 - 85 °C under air conditions, stir for 8 - 10 h under light conditions, and then heat up to 128 - 132 °C and continue stirring and reacting for 11 - 13 h to obtain a modified bio-based polymer.

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

5.

8. The preparation method of the modified bio-based polymer according to claim 6, characterized in that, The preparation method of the carbon nitride-based flame retardant filler in the composite filler is as follows: Put 1 part by mass of carbon nitride into 32 parts by mass of methanol and stir ultrasonically for 1 - 2 h. Subsequently, add 0.19 - 0.2 part by mass of zinc nitrate hexahydrate and continue stirring for 8 - 10 h. Leave it to settle overnight, then add 0.18 - 0.19 part by mass of 2-methylimidazole and continue stirring for 24 h. Subsequently, wash it 3 times with methanol and then dry it in vacuum at 60 °C for 10 - 12 h. Then, heat it up to 400 °C at a rate of 5 °C / min and calcine it in a nitrogen tube furnace for 1.5 - 2.5 h. After cooling to room temperature, carbon nitride composite filler is obtained; Mix 6.8 - 7 parts by mass of the carbon nitride composite filler with 200 parts by mass of deionized water and disperse it ultrasonically for 30 min. Subsequently, add 21 - 22 parts by mass of 2-carboxyethylphenylphosphinic acid and continue ultrasonic treatment for 1 h. Then, add sodium hydroxide to adjust the pH to 5 - 6 and heat it up to 80 - 90 °C. Finally, dropwise add 10 - 12 wt% aluminum sulfate solution at a rate of 1 - 3 drops / s and keep the reaction warm under stirring conditions for 3.5 - 4.5 h. Filter, wash, and dry to obtain the carbon nitride-based flame retardant filler.

9. The preparation method of the modified biobased polymer according to claim 6, characterized in that, The preparation method of the porous nitrogen-doped carbon-based filler in the composite filler is as follows: Dissolve 0.65 - 0.67 part by mass of folic acid in 100 parts by mass of pure water. Under stirring conditions, add 0.33 - 0.35 part by mass of 1 mol / L potassium hydroxide solution and stir until the folic acid is completely dissolved. Subsequently, add 1.1 - 1.3 parts by mass of potassium bromide. After complete dispersion, add 0.62 - 0.63 part by mass of zinc nitrate and mix well. Let it stand at room temperature for 1 h and then freeze-dry it. Then, under the protection of nitrogen, put it into a tube furnace, heat it up to 800 °C at a heating rate of 3 °C / min, calcine it for 2 h, and then cool it to room temperature at a rate of 3 °C / min. Subsequently, wash it with deionized water to remove potassium bromide and dry it to obtain the porous nitrogen-doped carbon-based filler.

10. The preparation method of the modified biobased polymer according to claim 6, wherein, The light source uses an LED 365nm or an LED 420nm .

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