Preparation method of waterborne polyurethane with flame-retardant, antibacterial and self-repairing functions

Abstract

The invention discloses a preparation method of waterborne polyurethane with flame-retardant, antibacterial and self-repairing functions. The waterborne polyurethane is prepared by blending an aluminum-zinc modified sodium phytate solution and a waterborne polyurethane emulsion, and the aluminum-zinc modified sodium phytate solution is prepared by respectively adding aluminum and zinc metal salts into a sodium phytate solution and carrying out chelation reaction; the waterborne polyurethane emulsion is prepared by the following steps: reacting high-molecular diol, dimethylolpropionic acid and diisocyanate, carrying out chain extension through 1, 4-butanediol and diselenediol, neutralizing through triethylamine, and adding melamine during emulsification to carry out water-phase chain extension and crosslinking. According to the invention, phosphorus, nitrogen and double selenium are introduced to provide flame retardant property, zinc and phytic acid can endow antibacterial property, and double selenium bonds, metal coordination bonds and hydrogen bonds can provide good room-temperature self-repairing function. The method provided by the invention is green and environment-friendly, and the prepared material has excellent flame-retardant, antibacterial and self-repairing functions and can be applied to many fields such as leather finishing and floor painting.

Description

Technical Field

[0001] The present invention relates to a preparation method of a waterborne polyurethane with flame retardant, antibacterial and self-healing functions, in particular to the preparation of a waterborne polyurethane containing double selenium dynamic bonds with flame retardant, antibacterial and self-healing functions based on aluminum-zinc modified sodium phytate, belonging to the fields of leather finishing and floor painting, etc. Background Art

[0002] Waterborne polyurethane is a polymer material that uses water instead of organic solvents as the dispersion medium. Due to its light weight, stable chemical properties, excellent mechanical properties, easy processing, good wear resistance, pollution-free and other characteristics, it is widely used in the fields of construction, medical treatment, leather, aerospace, automotive and military industry, etc. However, the vast majority of waterborne polyurethane materials without flame retardant treatment are extremely flammable, and toxic gases will be generated during combustion and accompanied by a melting drop phenomenon. This defect greatly limits its application in many fields. Therefore, it is necessary to carry out flame retardant treatment on it to improve the safety during the use of the material. At the same time, due to the existence of a large number of hydrophilic groups, waterborne polyurethane is prone to breed bacteria during the actual application process as a finishing and film material, which not only destroys its original properties and quality, but also poses a potential threat to human health. Therefore, it is necessary to endow waterborne polyurethane with certain antibacterial functions.

[0003] In addition, waterborne polyurethane as a finishing and film material is inevitably exposed to the environment for a long time during use. After being subjected to external force collision, chemical corrosion and other effects, problems such as microcracks and aging occur, and even product fracture may occur in severe cases. To solve this problem, some dynamic covalent bonds or dynamic non-covalent bonds can be introduced into waterborne polyurethane to endow it with self-healing function, thereby improving the protection ability and service life of the product. However, most of the existing self-healing waterborne polyurethane materials use high-temperature self-healing and have poor mechanical properties.

[0004] With the rapid development of modern society and the complexity of the material use environment, single-functional waterborne polyurethane can no longer meet the actual application requirements well. The industry has high expectations for multi-functional materials, especially waterborne polyurethane with flame retardant function, antibacterial function and self-healing function in one. The development of such multi-functional materials will be able to better meet the actual requirements of waterborne polyurethane in application fields such as finishing and film materials. However, at present, waterborne polyurethane with all of the above three functions has not been reported, and only waterborne polyurethane with two of these functions has been reported in the existing reports.

[0005] As disclosed in Chinese Patent (CN114560983B), a flame-retardant self-healing waterborne polyurethane composite finishing agent and its preparation method and application are provided. First, amino-functionalized nanoparticles react with hexachlorocyclotriphosphazene and diamine to obtain amino-terminated hyperbranched polyphosphazene-modified nanoparticles (HBPC), which are then added to an isocyanate-terminated prepolymer solution and reacted with 2,2'-diaminodiphenyl disulfide and 5,6-diamino-1,3-dimethyluracil. The material utilizes the hyperbranched structure in HBPC and the synergistic flame-retardant effect of phosphorus-nitrogen (P-N) to enhance the flame-retardant performance, and promotes self-healing by means of disulfide bonds, hydrogen bonds, and the mobility of the hyperbranched structure. However, the flame-retardant components used contain halogens, which cause great harm to the environment and do not have antibacterial properties, limiting its practical application scope.

[0006] As disclosed in Chinese Patent (CN116285300A), an antibacterial and flame-retardant waterborne polyurethane emulsion and its preparation method and application are provided. After synthesizing an antibacterial and flame-retardant monomer from a halogenated alcohol or a halogenated thiol and a tertiary phosphorus compound, it is then mixed with an isocyanate-terminated polyurethane. The synthesized quaternary phosphonium salt antibacterial agent has the synergistic flame-retardant and anti-bacterial adhesion properties of phosphorus and sulfur. However, too much organic solvent (50 - 300 parts by weight) is used in the preparation process, which does not conform to the concept of green environmental protection of waterborne polyurethane, and no self-healing functional structural unit is introduced, resulting in the prepared material having no self-healing function and greatly limiting its application.

[0007] As disclosed in Chinese Patent (CN116694219A), a preparation method of a visible light-induced MXene / waterborne polyurethane antibacterial and self-healing composite coating is provided. First, 5-(2-hydroxyethyl)-6-methyl-2-aminouracil (HMA) is added as a chain extender with a quadruple hydrogen bond motif to the synthesis of waterborne polyurethane, and then chemically polymerized with Ti3C2Tx-MXene. MXene itself has a nearly 100% photothermal conversion efficiency, and the high temperature obtained through photothermal conversion can solve the problem of the coating not being antibacterial, while the quadruple hydrogen bond motif endows the coating with self-healing properties. However, under visible light irradiation, a weak light intensity will lead to a slow photothermal conversion rate. At the same time, fluorine elements are added during the production of Ti3C2Tx-MXene, which are not easily removed subsequently, thus posing potential environmental pollution. In addition, no flame-retardant functional components are introduced into this material, resulting in its lack of flame-retardant function and inability to be applied in high-temperature environments.

[0008] As disclosed in Chinese Patent (CN112724358B), a preparation method of waterborne flame-retardant self-healing polyurethane based on modified graphene is provided. First, nitrogen, phosphorus, and silicon-modified nano-graphene oxide is prepared by ultrasonic pulverization of aminocyclotriphosphazene and isocyanate group-silane covalently modified graphene oxide, and then reacted with diisocyanate to obtain a prepolymer solution. Finally, it is capped with bis-selenol and emulsified. The flame retardancy of the material is synergistically improved by the modification of phosphorus, nitrogen, and silicon, and at the same time, a bis-selenium bond is introduced to endow the material with good room-temperature light-induced self-healing function. However, when preparing nitrogen, phosphorus, and silicon-modified nano-graphene oxide, the preparation conditions are relatively harsh (requiring an anhydrous environment), and it is easy for some graphene to remain un-pulverized, resulting in a decrease in the stability of the emulsion. In addition, the material lacks components with antibacterial functions, leading to a lack of ability to resist bacterial erosion and a decrease in its service life.

[0009] Phytic acid, as a biomass material with a high phosphorus content, has received extensive attention in the field of flame retardancy and plays a role in both gas-phase flame retardancy and condensed-phase flame retardancy (Polymer Testing, 2023, 124). However, phytic acid alone cannot solve the dripping problem of waterborne polyurethane. Given the strong metal chelating ability of phytic acid, chelating phytic acid with metal ions can increase the viscosity of the system, thus largely avoiding dripping. At the same time, when the added metal ions have antibacterial ability, after superimposing with phytic acid with antibacterial ability, the antibacterial function of the material will be further enhanced. Therefore, phytic acid chelated with metal ions can be used as an excellent flame retardant and antibacterial agent. In view of the fact that a single flame retardant component often fails to meet the requirements of high-efficiency flame retardancy. In recent years, studies have shown that the flame retardant effect of the phosphorus-nitrogen synergy is more excellent (Polymer Degradation and Stability, 2017, 144(10): 62-69). Melamine has a stable triazine ring and three amino groups, which can sublime and absorb a large amount of heat at high temperatures. In addition, ammonia gas generated by the decomposition of melamine dilutes the combustible gas and forms a thermally stable condensed phase containing melam, melem, and melon. At the same time, melamine can form a three-dimensional network structure with the main chain of waterborne polyurethane, thereby improving the mechanical properties and viscosity of the material. Therefore, when melamine and phytic acid chelated with metal ions are applied to the waterborne polyurethane system together, it is expected to avoid the introduction of halogens and greatly improve the flame retardancy and antibacterial functions of the material.

[0010] Diselene has the ability to self-repair at room temperature under light illumination and quench oxygen active groups, and is gradually being applied in the fields of flame retardancy and self-repair (ACS Applied Materials & Interfaces, 2023, 15(12): 16118 - 31). However, due to the decrease in the mechanical properties of the material caused by the low bond energy of diselene (172 KJ / mol) and the inability to form a stable carbon layer in an environment above 500 °C, it needs to be used in combination with other flame retardants and self-repair agents, and the strength can be improved through molecular structure design or appropriate modification to enhance the self-repair and flame retardant properties to achieve more excellent actual use effects.

[0011] In the present invention, aluminum and zinc metal salts are first added to a prepared sodium phytate solution with a configured concentration respectively to obtain an aluminum-zinc modified sodium phytate solution through a metal chelation reaction. Then, a high molecular diol, dimethylolpropionic acid, and diisocyanate are reacted, and then chain-extended with 1,4-butanediol and diselene diol, neutralized with triethylamine, and melamine is added during emulsification for aqueous phase chain extension and crosslinking to obtain an aqueous polyurethane emulsion. Finally, the aluminum-zinc modified sodium phytate solution is added to the emulsion to prepare an aqueous polyurethane with flame retardant, antibacterial, and self-repair functions. In the present invention, the high-efficiency self-repair at room temperature is achieved through the combined action of the coordination bond formed by the chelation reaction of metal ions with sodium phytate, the coordination bond formed by metal ions with carboxyl ions on the main chain of the aqueous polyurethane, the hydrogen bond formed by the aluminum-zinc modified sodium phytate with the main chain of the aqueous polyurethane, and the diselene bond formed by adding the diselene diol chain extender; the introduction of phosphorus elements in phytic acid, nitrogen elements in melamine, and diselene realizes the synergistic flame retardancy in the gas phase and condensed phase. At the same time, the formation of melamine crosslinking and metal coordination bonds increases the viscosity of the system, thereby playing a role in anti-dripping. The dual antibacterial ability of zinc and phytic acid can endow the material with antibacterial properties. In addition, the three-dimensional crosslinking network structure formed by melamine, the hydrogen bond formed by phytic acid, and the coordination bond formed by metal ions can solve the problem of the decrease in mechanical properties caused by the introduction of low bond energy diselene bonds, significantly improving the mechanical properties of the material. The material prepared in the present invention is an aqueous system, does not contain organic solvents, is green and environmentally friendly, has a flame retardant function and overcomes the problem of non-anti-dripping of aqueous polyurethane, and at the same time has excellent self-repair performance, antibacterial performance, and mechanical properties, and can be applied to fields such as leather finishing and floor painting. Summary of the Invention

[0012] The present invention designs a preparation method of a waterborne polyurethane with flame retardant, antibacterial and self-healing functions. First, aluminum and zinc metal salts are respectively added to a prepared sodium phytate solution with a certain concentration, and an aluminum-zinc modified sodium phytate solution is obtained through a metal chelation reaction. Then, a high molecular diol, dimethylolpropionic acid and diisocyanate are reacted, and then chain-extended with 1,4-butanediol and diselenide diol, neutralized with triethylamine, and melamine is added during emulsification for aqueous phase chain extension and crosslinking to obtain a waterborne polyurethane emulsion. Finally, the aluminum-zinc modified sodium phytate solution is added to the emulsion to obtain the product.

[0013] The waterborne polyurethane with flame retardant, antibacterial and self-healing functions provided by the present invention is characterized in that:

[0014] 1. For the waterborne polyurethane with flame retardant, antibacterial and self-healing functions provided by the present invention, through the synergistic action of aluminum-zinc modified sodium phytate, melamine and diselenide, multiple flame retardant methods such as capturing active free radicals, dehydrating and carbonizing, generating incombustible gases and forming a dense carbon layer during combustion are achieved, so as to obtain the synergistic flame retardant effect of gas-phase flame retardancy and condensed-phase flame retardancy, which can significantly improve the flame retardant ability of the material. At the same time, the crosslinking of melamine and the formation of metal coordination bonds increase the viscosity of the system, solving the problem that waterborne polyurethane is not resistant to melt dripping.

[0015] 2. For the waterborne polyurethane with flame retardant, antibacterial and self-healing functions provided by the present invention, after the zinc ions in its system are chelated with phytic acid, it has the dual bactericidal ability of destroying cell walls, cell membranes and generating oxidative stress reactions, and the bactericidal duration is long and stable, providing the function of the material to resist bacterial invasion.

[0016] 3. For the waterborne polyurethane with flame retardant, antibacterial and self-healing functions provided by the present invention, the coordination bonds formed by the chelation reaction of metal ions and sodium phytate in its system, the coordination bonds formed by metal ions and carboxyl ions on the main chain of waterborne polyurethane, the hydrogen bonds formed by aluminum-zinc modified sodium phytate and the main chain of waterborne polyurethane, and the diselenide bonds formed by adding diselenide diol chain extender work together to achieve the efficient self-healing of the material at room temperature.

[0017] 4. For the waterborne polyurethane with flame retardant, antibacterial and self-healing functions provided by the present invention, the three-dimensional network structure formed by melamine, the hydrogen bonds formed by phytic acid and the coordination bonds formed by metal ions in its system can overcome the problem of the decrease in mechanical properties caused by the introduction of low bond energy diselenide bonds, and significantly improve the mechanical properties of the material.

[0018] The purpose of the present invention is achieved through the following technical solutions:

[0019] The preparation method of the waterborne polyurethane with flame retardant, antibacterial and self-healing functions described in the present invention is as follows: First, aluminum and zinc metal salts are respectively added to the prepared sodium phytate solution with a certain concentration, and after metal chelation reaction, an aluminum-zinc modified sodium phytate solution is obtained. Then, a high molecular diol, dimethylolpropionic acid and diisocyanate are reacted, and then chain-extended with 1,4-butanediol and bis-selenium diol, neutralized with triethylamine, and melamine is added during emulsification for aqueous phase chain extension and crosslinking to obtain a waterborne polyurethane emulsion. Finally, the aluminum-zinc modified sodium phytate solution is added to the emulsion. Among them, the mass ratios of each raw material component are as follows:

[0020] Zinc metal salt 0.01 - 0.2;

[0021] Aluminum metal salt 0.01 - 0.2;

[0022] Sodium phytate 1 - 10;

[0023] High molecular diol 25 - 70;

[0024] Dimethylolpropionic acid 3 - 7;

[0025] Diisocyanate 10 - 25;

[0026] Catalyst 0.01 - 0.02;

[0027] 1,4-butanediol 0.4 - 4;

[0028] Bis-selenium diol 0.4 - 6;

[0029] Triethylamine 3 - 6;

[0030] Deionized water 150 - 300;

[0031] Melamine 0.5 - 5;

[0032] The waterborne polyurethane with flame retardant, antibacterial and self-healing functions is prepared by the following specific method:

[0033] (1) Dissolve sodium phytate in deionized water to prepare a sodium phytate solution with a concentration of 5 - 25 wt%; then add zinc metal salt to the sodium phytate solution, stir mechanically, and reflux at 80 - 100 °C for 1 - 2 h; then add aluminum metal salt, stir mechanically, and reflux at 80 - 100 °C for 1 - 2 h to obtain an aluminum-zinc modified sodium phytate solution;

[0034] (2) Add the dry polymer diol, dimethylolpropionic acid, diisocyanate, and catalyst into a dry three-necked flask equipped with a mechanical stirrer, and react at 65-90 °C for 2-3 h to obtain an isocyanate-terminated prepolymer; cool down to 50-60 °C, add 1,4-butanediol and diselenodiol, and react for 2-4 h; cool down to 30-40 °C, add triethylamine to neutralize the reaction for 10-20 min to obtain an isocyanate-terminated chain-extended product; then dissolve melamine in deionized water and add it to the three-necked flask, and carry out high-speed emulsification reaction at 30-40 °C and 1200-1500 r / min for 20-30 min, and then reduce the rotation speed to 500-800 r / min and continue the emulsification reaction for 30-60 min to obtain a melamine-crosslinked modified aqueous polyurethane emulsion;

[0035] (3) Add the aluminum-zinc modified sodium phytate solution obtained in step (1) into the melamine-crosslinked modified aqueous polyurethane emulsion obtained in step (2), and mechanically stir for 30-60 min to obtain the above-mentioned aqueous polyurethane with flame retardancy, antibacterial, and self-healing functions.

[0036] Among them, the zinc metal salt is one of Zn 2+ chlorides, acetates, and nitrates; the aluminum metal salt is one of Al 3+ chlorides, acetates, and nitrates; the polymer diol is one of polytetrahydrofuran ether diol, polycaprolactone diol, and polycarbonate diol, and its number average molecular weight is one of 1000 g / mol, 2000 g / mol, and 3000 g / mol; the diisocyanate is one of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; the catalyst is one of dibutyltin dilaurate and organobismuth; the diselenodiol is one of 2,2'-diselenodiethanol and 3,3'-diselenodipropanol.

[0037] The advantages of the present invention are as follows: The waterborne polyurethane with flame retardant, antibacterial and self-healing functions prepared by the present invention can provide efficient self-healing function at room temperature through the coordination bonds formed by chelating metal ions with sodium phytate, the coordination bonds formed by metal ions with carboxyl ions on the main chain of waterborne polyurethane, the hydrogen bonds formed by aluminum-zinc modified sodium phytate and the main chain of waterborne polyurethane, and the diselenide bonds formed by adding diselenodiol chain extender; The introduction of phosphorus, nitrogen elements and diselenium endows the material with the synergistic effect of various flame retardant methods such as capturing active free radicals, dehydrating and carbonizing, generating incombustible gases and forming a dense carbon layer. At the same time, the formation of melamine crosslinking and metal coordination bonds increases the viscosity of the system, thus playing the role of anti-dripping; The dual antibacterial properties of zinc and phytic acid can endow the material with antibacterial properties; The three-dimensional crosslinking network structure formed by melamine, the hydrogen bonds formed by phytic acid and the coordination bonds formed by metal ions can solve the problem of the decrease in mechanical properties caused by the introduction of low bond energy diselenide bonds, and significantly improve the mechanical properties of the material. The material prepared by the present invention is a waterborne system, does not contain organic solvents, is green and environmentally friendly, has flame retardant function and overcomes the problem that waterborne polyurethane is not anti-dripping. At the same time, it has excellent self-healing performance, antibacterial performance and mechanical properties, and can be applied to fields such as leather finishing and floor painting. Detailed implementation mode

[0038] Example 1: (1) Dissolve 4.62 g of sodium phytate in 18.48 g of deionized water to prepare a sodium phytate solution with a concentration of 20 wt%; then add 0.136 g of zinc chloride to the sodium phytate solution, stir mechanically, and reflux at 100 °C for 1 h; then add 0.133 g of aluminum chloride, stir mechanically, and reflux at 100 °C for 1 h to obtain an aluminum-zinc modified sodium phytate solution; (2) Add 30 g of dry polytetrahydrofuran ether diol (Mn≈2000), 4.02 g of dimethylolpropionic acid, 13.34 g of isophorone diisocyanate, and 0.01 g of dibutyltin dilaurate to a dry three-necked flask equipped with a mechanical stirrer and react at 90 °C for 2 h to obtain a terminal isocyanate prepolymer; cool down to 60 °C, add 0.45 g of 1,4-butanediol and 0.496 g of 2,2'-diselenodiethanol, and react for 3 h; cool down to 40 °C, add 3.04 g of triethylamine and neutralize for 20 min to obtain a chain-extended product with terminal isocyanate groups; then dissolve 0.631 g of melamine in 265.85 g of deionized water and add it to the three-necked flask, and carry out high-speed emulsification reaction at 40 °C and 1500 r / min for 20 min, then reduce the rotation speed to 500 r / min and continue emulsification reaction for 40 min to obtain a melamine-crosslinked modified waterborne polyurethane emulsion; (3) Add 23.369 g of aluminum-zinc modified sodium phytate solution to 317.837 g of melamine-crosslinked modified waterborne polyurethane emulsion, stir mechanically for 30 min, and obtain the above-mentioned waterborne polyurethane with flame retardant, antibacterial and self-healing functions.

[0039] Example 2: (1) Dissolve 4.62 g of sodium phytate in 18.48 g of deionized water to prepare a sodium phytate solution with a concentration of 20 wt%; then add 0.136 g of zinc chloride to the sodium phytate solution, stir mechanically, and reflux at 80 °C for 2 h; subsequently add 0.133 g of aluminum chloride, stir mechanically, and reflux at 80 °C for 2 h to obtain an aluminum-zinc modified sodium phytate solution; (2) Add 30 g of dried polytetrahydrofuran ether diol (Mn≈2000), 4.02 g of dimethylolpropionic acid, 13.34 g of isophorone diisocyanate, and 0.01 g of dibutyltin dilaurate to a dried three-necked flask equipped with a mechanical stirrer and react at 80 °C for 3 h to obtain an isocyanate-terminated prepolymer; cool to 60 °C, add 0.45 g of 1,4-butanediol and 0.496 g of 2,2'-diselenodiethanol, and react for 4 h; cool to 40 °C, add 3.04 g of triethylamine to neutralize and react for 20 min to obtain an isocyanate-terminated chain-extended product; then dissolve 0.631 g of melamine in 265.85 g of deionized water and add it to the three-necked flask, and carry out high-speed emulsification reaction at 40 °C and 1500 r / min for 30 min, and then reduce the rotation speed to 800 r / min and continue the emulsification reaction for 30 min to obtain a melamine-crosslinked modified aqueous polyurethane emulsion; (3) Add 23.369 g of the aluminum-zinc modified sodium phytate solution to 317.837 g of the melamine-crosslinked modified aqueous polyurethane emulsion, stir mechanically for 30 min, and the above-mentioned aqueous polyurethane with flame retardant, antibacterial and self-healing functions is obtained.

[0040] Example 3: (1) Dissolve 4.62 g of sodium phytate in 18.48 g of deionized water to prepare a sodium phytate solution with a concentration of 20 wt%; then add 0.136 g of zinc chloride to the sodium phytate solution, stir mechanically, and reflux at 100 °C for 1 h; subsequently, add 0.2 g of aluminum chloride, stir mechanically, and reflux at 100 °C for 1 h to obtain an aluminum-zinc modified sodium phytate solution; (2) Add 30 g of dried polytetrahydrofuran ether diol (Mn≈2000), 4.02 g of dimethylolpropionic acid, 15.56 g of isophorone diisocyanate, and 0.01 g of dibutyltin dilaurate to a dried three-necked flask equipped with a mechanical stirrer and react at 90 °C for 2 h to obtain an isocyanate-terminated prepolymer; cool to 60 °C, add 0.45 g of 1,4-butanediol and 0.496 g of 2,2'-diselenodiethanol, and react for 3 h; cool to 40 °C, add 3.04 g of triethylamine and neutralize for 20 min to obtain an isocyanate-terminated chain-extended product; then dissolve 0.631 g of melamine in 277.285 g of deionized water and add it to the three-necked flask, and carry out high-speed emulsification reaction at 40 °C and 1500 r / min for 20 min, and then reduce the rotation speed to 500 r / min and continue the emulsification reaction for 40 min to obtain a melamine-crosslinked modified aqueous polyurethane emulsion; (3) Add 23.436 g of the aluminum-zinc modified sodium phytate solution to 331.492 g of the melamine-crosslinked modified aqueous polyurethane emulsion, stir mechanically for 30 min, and obtain the above-mentioned aqueous polyurethane with flame retardant, antibacterial, and self-healing functions.

[0041] Example 4: (1) Dissolve 4.62 g of sodium phytate in 18.48 g of deionized water to prepare a sodium phytate solution with a concentration of 20 wt%; then add 0.183 g of zinc acetate to the sodium phytate solution, stir mechanically, and reflux at 100 °C for 1 h; subsequently, add 0.133 g of aluminum chloride, stir mechanically, and reflux at 100 °C for 1 h to obtain an aluminum-zinc modified sodium phytate solution; (2) Add 30 g of dried polycaprolactone diol (Mn≈2000), 4.02 g of dimethylolpropionic acid, 10.45 g of toluene diisocyanate, and 0.01 g of organobismuth to a dry three-necked flask equipped with a mechanical stirrer and react at 90 °C for 2 h to obtain an isocyanate-terminated prepolymer; cool to 60 °C, add 0.45 g of 1,4-butanediol and 0.496 g of 2,2'-diselenodiethanol, and react for 3 h; cool to 40 °C, add 3.04 g of triethylamine to neutralize and react for 20 min to obtain an isocyanate-terminated chain-extended product; then dissolve 0.631 g of melamine in 251.64 g of deionized water and add it to the three-necked flask, and carry out high-speed emulsification reaction at 40 °C and 1500 r / min for 20 min, and then reduce the rotation speed to 500 r / min and continue the emulsification reaction for 40 min to obtain a melamine-crosslinked modified aqueous polyurethane emulsion; (3) Add 23.416 g of the aluminum-zinc modified sodium phytate solution to 300.737 g of the melamine-crosslinked modified aqueous polyurethane emulsion, stir mechanically for 30 min to obtain the above-mentioned aqueous polyurethane with flame retardant, antibacterial and self-healing functions.

Claims

1. A preparation method of a waterborne polyurethane with flame retardant, antibacterial and self-healing functions, characterized in that The waterborne flame-retardant, antibacterial and self-healing polyurethane is prepared by blending and compounding melamine-crosslinked waterborne polyurethane containing diselenide bonds with a solution of sodium phytate modified with aluminum and zinc. The raw material composition ratio is as follows: Zinc metal salt 0.01 - 0.2; Aluminum metal salt 0.01 - 0.2; Sodium phytate 1 - 10; Polymeric diol 25 - 70; Dimethylolpropionic acid 3 - 7; Diisocyanate 10 - 25; Catalyst 0.01 - 0.02; 1,4-Butanediol 0.4 - 4; Diselenide diol 0.4 - 6; Triethylamine 3 - 6; Deionized water 150 - 300; Melamine 0.5 - 5; The waterborne polyurethane with flame-retardant, antibacterial and self-healing functions is prepared by the following specific method: (1) Dissolve sodium phytate in deionized water to prepare a sodium phytate solution with a concentration of 5 - 25 wt%. Then add the zinc metal salt to the sodium phytate solution, stir mechanically, and reflux at 80 - 100 °C for 1 - 2 h. Subsequently, add the aluminum metal salt, stir mechanically, and reflux at 80 - 100 °C for 1 - 2 h to obtain a solution of sodium phytate modified with aluminum and zinc; (2) Add the dry polymeric diol, dimethylolpropionic acid, diisocyanate and catalyst to a dry three-necked flask equipped with a mechanical stirrer and react at 65 - 90 °C for 2 - 3 h to obtain a prepolymer with terminal isocyanate groups. Cool down to 50 - 60 °C, add 1,4-butanediol and diselenide diol, and react for 2 - 4 h. Cool down to 30 - 40 °C, add triethylamine to neutralize for 10 - 20 min to obtain an extended-chain product with terminal isocyanate groups. Then dissolve melamine in deionized water and add it to the three-necked flask. Under the conditions of 30 - 40 °C and 1200 - 1500 r / min, carry out high-speed emulsification reaction for 20 - 30 min, and then reduce the rotation speed to 500 - 800 r / min and continue the emulsification reaction for 30 - 60 min to obtain a waterborne polyurethane emulsion crosslinked and modified with melamine; (3) Add the solution of sodium phytate modified with aluminum and zinc obtained in step (1) to the waterborne polyurethane emulsion crosslinked and modified with melamine obtained in step (2), stir mechanically for 30 - 60 min to obtain the above-mentioned waterborne polyurethane with flame-retardant, antibacterial and self-healing functions.

2. The preparation method of the waterborne polyurethane with flame retardant, antibacterial and self-healing functions according to claim 1, characterized in that: The zinc metal salt is one of the chlorides, acetates, and nitrates of Zn 2+ ; the aluminum metal salt is one of the chlorides, acetates, and nitrates of Al 3+ ; the high molecular weight diol is one of polytetrahydrofuran ether diol, polycaprolactone diol, and polycarbonate diol, and its number average molecular weight is one of 1000 g / mol, 2000 g / mol, and 3000 g / mol; the diisocyanate is one of isophorone diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, and diphenylmethane diisocyanate; the catalyst is one of dibutyltin dilaurate and organic bismuth; the diselenodiol is one of 2,2'-diselenodiethanol and 3,3'-diselenodipropanol.