A biomass-based multifunctional epoxy resin and its preparation method and application

Abstract

The invention discloses a biomass-based multifunctional epoxy resin, a preparation method and an application thereof, belonging to the technical field of high-value utilization of biomass. Lignin and a nitrogen-containing polymer are extruded and granulated, and then microwave-assisted co-pyrolysis is performed to achieve synergistic pyrolysis of the lignin and the nitrogen-containing polymer. Under acidic conditions, the ionization of the solute and the affinity between the solution and the solute decrease, making it easier to extract and obtain the target product. Formate provides a hydrogen donor in the low-temperature section of the microwave-assisted depolymerization reaction. The phenolic hydroxyl groups of the lignin monomers are further oxidized to aldehyde groups by utilizing the oxidation effect of an oxygen carrier in the high-temperature section of microwave radiation and oxygen vacancy defects. A SiO2-based catalyst provides an acidic catalytic site to induce the protonation of the carbonyl group in the aldehyde, making it easier for the aldehyde to combine with the amino group in the aromatic amine. The dehydration reaction of the aldehyde group and the amino group is used to successfully introduce an alkylimino group HC=N. A triamine is used as a curing agent to introduce an epoxy resin network with a dynamic Schiff base, thereby having good reprocessability and antibacterial properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-value utilization of biomass-based materials, and specifically relates to a biomass-based multifunctional epoxy resin and a preparation method and application thereof. Background Art

[0002] Epoxy resins are widely used in industrial production and aerospace due to their advantages, such as lightweight and excellent insulation properties. However, commercial epoxy resins are almost entirely dependent on petroleum-based derivatives, with bisphenol A epoxy resin accounting for 90% of production, which is not sustainable. Therefore, the development of green and simple biomass-based epoxy resins is of great significance in the synthesis of resin materials.

[0003] There are currently some reports on the synthesis of biomass-based epoxy resins, such as those prepared using vegetable oils, lignin, or lignin derivatives (such as vanillin) as raw materials. In the invention patent "A plant oil-based recyclable epoxy resin, its preparation method, and application" (CN116023565A), a plant oil-based epoxy polymer is used as a raw material to controllably construct an all-biomass-based epoxy supramolecular polymer network, resulting in a low glass transition temperature all-biomass-based epoxy resin. In the invention patent "A solvent-free method for preparing a lignin-based biomass epoxy resin" (CN115850657A), lignin extracted from bioethanol is used instead of bisphenol A as a raw material to achieve a solvent-free reaction to synthesize a lignin-based epoxy resin. The resulting lignin has a molecular weight of 3.6 kDa. In the invention patent "A vanillin-based epoxy resin and its preparation method" (CN115073710A), a biodegradable and recyclable biomass-based epoxy resin is prepared using vanillin and 4-aminocyclohexanol as raw materials. However, the above-mentioned patents or other related biomass-based epoxy resin syntheses not mentioned have more or less disadvantages such as low glass transition temperature of the prepared biomass-based epoxy resin, certain pollution in the preparation method, low reaction performance due to excessive molecular weight of bio-based raw materials, low acid resistance of the product and single functionality.

[0004] Therefore, in view of the problems of existing biomass-based epoxy resins, such as low glass transition temperature, certain pollution in the preparation method, low reaction performance due to the large molecular weight of bio-based raw materials, low acid resistance of products and single functionality, it is urgent to find a new preparation method for biomass-based multifunctional epoxy resins to effectively improve the functionality of biomass-based epoxy resins. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a biomass-based multifunctional epoxy resin to solve the technical problems of the existing biomass-based synthetic epoxy resin, such as low glass transition temperature, poor antibacterial property, acid resistance and processability.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] The present invention discloses a method for preparing a biomass-based multifunctional epoxy resin, comprising the following steps:

[0008] 1) mixing lignin and a nitrogen-containing polymer and stirring them uniformly, extruding and granulating them to obtain a wood-plastic polymer; washing and drying them to obtain lignin nitrogen-based microspheres; ball-milling the lignin nitrogen-based microspheres, a molecular sieve catalyst, and a microwave absorbing medium, and then subjecting them to microwave-assisted co-pyrolysis, collecting the liquid product, and obtaining an aromatic amine-rich bio-oil;

[0009] 2) placing the aromatic amine-rich bio-oil obtained in step 1) into an HCl solution, extracting and distilling under reduced pressure to obtain aromatic amine compounds;

[0010] 3) impregnating the lignin in a formate solution, drying the lignin to obtain treated lignin powder, mixing the lignin powder with an oxygen carrier, stirring the powder, and performing microwave-assisted depolymerization. The liquid product is collected to obtain a vanillin-rich bio-oil.

[0011] 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation, condensing and collecting the liquid component, extracting the organic phase, and concentrating the organic phase to obtain vanillin compounds;

[0012] 5) ball-milling the aromatic amine compound obtained in step 2) and the vanillin compound obtained in step 4) to obtain a mixed product, which is then placed in deionized water with a spherical X-SiO2-based catalyst, stirred for reaction, and filtered to obtain the spherical X-SiO2-based catalyst and a reaction product powder. The reaction product powder is then separated, washed, and dried to obtain a Schiff base-containing bisphenol A compound;

[0013] 6) dissolving the Schiff base-containing bisphenol A compound and benzyltriethylammonium chloride obtained in step 5) in epichlorohydrin under a nitrogen atmosphere. After the reaction is completed, adding a NaOH solution, stirring for 1 to 2 hours, filtering, washing, drying, and distilling under reduced pressure to obtain a Schiff base diepoxide compound;

[0014] 7) The Schiff base diepoxide obtained in step 6) is mixed with triamine and stirred, and then vacuum degassed. After curing, grinding, and hot pressing, a biomass-based multifunctional epoxy resin is obtained.

[0015] Preferably, in step 1), the mass ratio of lignin: nitrogen-containing polymer is 5:(1-0.8); the stirring time is 1-3h; the conditions for extrusion granulation are: extrusion granulation in the temperature range of 100-150°C and 180-210°C; the drying conditions are: drying at 55-75°C for 12-18h; the mass ratio of lignin nitrogen-based microspheres: molecular sieve catalyst: microwave absorption medium is 5:1:(1-0.5); the microwave absorption medium is SiC; the lignin is any one of coniferous wood lignin, broadleaf wood lignin and herbaceous lignin; the nitrogen-containing polymer is any one of nitrile amine polymer, amide polymer and alcohol amine polymer; the molecular sieve catalyst is any one of HZSM-5 molecular sieve, SAPO-34 molecular sieve and SBA-15 molecular sieve; the parameters for microwave-assisted co-pyrolysis are set to a power of 1000-1500W under N2 atmosphere, heating to 450-700°C, and keeping warm for 5-10min.

[0016] Preferably, in step 2), the concentration of the HCl solution is 3 to 5 mol / L; the extraction liquid used is prepared by mixing ethyl acetate and deionized water in a volume ratio of 2:(1 to 0.5); the temperature of the reduced pressure distillation is 70 to 80° C., and the pressure of the reduced pressure distillation is 1.0 to 2.0 kPa.

[0017] Preferably, in step 3), the concentration of the formate solution is 22 to 28 mol / L; the immersion time is 1 to 3 hours; the drying conditions are: drying at 60 to 80°C for 12 to 24 hours; the mass ratio of the treated lignin powder: oxygen carrier is 1:(1 to 0.8); the formate is any one of sodium formate, calcium formate and nickel formate; the oxygen carrier is any one of Fe2O3, CuO and MoO2; the parameters for microwave-assisted depolymerization are set to a power of 1200 to 1800 W under N2 atmosphere, heating to 500 to 800°C, and keeping the reaction warm for 10 to 20 minutes.

[0018] Preferably, in step 4), the temperature of the vacuum distillation is 60-70° C., the pressure of the vacuum distillation is 1.3-2.3 kPa, and the time of the vacuum distillation is 10-20 min; the temperature of the concentration is 20-30° C., and the pressure of the concentration is 1.5-2.5 kPa.

[0019] Preferably, in step 5), the mass ratio of aromatic amine compounds: vanillin compounds is 1: (1 to 0.8); the mass ratio of mixed product: spherical X-SiO2-based catalyst is 1: (0.5 to 0.3); the stirring reaction conditions are: at a speed of 800 to 1200 rpm, react at 25 to 35 ° C for 4 to 6 hours; the washing conditions are: using deionized water at 80 to 90 ° C, washing 5 to 8 times; the drying conditions are: drying at 80 to 120 ° C for 12 to 18 hours; the spherical X-SiO2-based catalyst is any one of Co-SiO2, Ni-SiO2 and Fe-SiO2.

[0020] Preferably, in step 6), the mass ratio of Schiff base-containing bisphenol A compound to benzyltriethylammonium chloride is 1:(1-0.8); the reaction conditions are: reaction at 80-100°C for 4-6 hours; the washing conditions are: washing 3-5 times with deionized water at a temperature of 55-75°C; the drying conditions are: drying at 65-85°C for 10-15 hours; the temperature of the reduced pressure distillation is 75-85°C, and the pressure of the reduced pressure distillation is 1.5-2.5 kPa.

[0021] Preferably, in step 7), the mass ratio of the Schiff base diepoxide compound to the triamine is 10:(1-0.5); the stirring conditions are: stirring at a speed of 1000-1500 rpm and at 80-120° C. for 3-5 min; the vacuum degassing pressure is -2--2.7 kPa; the curing conditions are: keeping warm at 100-200° C. for 2-4 h; the hot pressing conditions are: hot pressing at 160-180° C. and 5-7 MPa for 1-3 h; the shape of the biomass-based multifunctional epoxy resin can be changed by multiple grinding and hot pressing; the triamine is any one of tris(2-aminoethyl)amine and tris(3-aminopropyl)amine.

[0022] The present invention also discloses a biomass-based multifunctional epoxy resin obtained by the above-mentioned preparation method. The biomass-based multifunctional epoxy resin has a glass transition temperature of 230 to 270°C, an antibacterial rate of 99.991% to 99.998%, and strong acid resistance, as shown by no degradation in a 10wt% to 15wt% sulfuric acid solution at 50 to 60°C for 24 to 36 hours.

[0023] The present invention also discloses the use of the biomass-based multifunctional epoxy resin in preparing temperature-resistant electronic components, antibacterial diaphragms and acid-resistant equipment.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention discloses a method for preparing a biomass-based multifunctional epoxy resin. Lignin nitrogen-based microspheres are obtained by extruding and granulating lignin and a nitrogen-containing polymer. During microwave-assisted co-pyrolysis, conventional physical blending produces mostly aliphatic amines and aromatic rings due to the independent reactions between monomers and their significantly different reaction temperature gradients. However, the lignin nitrogen-based microspheres prepared by the present invention have similar glass transition temperatures and pyrolysis temperatures. During microwave-assisted co-pyrolysis, the production time of amino compound vapor and lignin vapor coincides, providing a synergistic effect for aromatic amine synthesis and facilitating the microwave-assisted co-pyrolysis of lignin and nitrogen-containing polymers to produce aromatic amine-rich bio-oil. The unique "dielectric heating" method of microwaves enables synergistic pyrolysis of lignin and nitrogen-containing polymers in a microwave system. Specifically, during depolymerization of the nitrogen-containing polymer, -NH2 radicals rapidly attach to the benzene rings or methylene groups of the lignin monomers, thereby preserving the original phenolic structure. Compared with traditional chemical preparations of phenolic aromatic amines, this method successfully addresses the key issue of traditional phenolic preparations requiring the protection of phenolic hydroxyl groups. Compared with traditional rapid pyrolysis, microwave-assisted co-pyrolysis offers advantages such as strong controllability and synergistic effects. It can be applied to the co-pyrolysis of biomass and nitrogen-containing polymers, thus achieving a leap forward in the conversion of biomass to aromatic amines. Pre-impregnation of lignin with formate helps the formate provide a hydrogen donor during the low-temperature phase of the microwave-assisted depolymerization reaction, providing reducing power and selective β-O-4 bond cleavage for lignin depolymerization into phenolic monomers. Furthermore, ball-milling the formate-pre-impregnated lignin with an oxygen carrier further oxidizes the phenolic hydroxyl groups of the lignin monomers to aldehydes through the oxygen carrier's high-temperature oxidation under microwave irradiation and oxygen vacancy defects. The combination of formic acid's reducing and selective bond cleavage capabilities with the oxygen carrier's oxidative properties facilitates the microwave-assisted depolymerization of lignin to produce vanillin-rich bio-oils. Furthermore, the introduction of an oxygen carrier during microwave-assisted depolymerization allows for the targeted production of aldehydes from the lignin product. By using SiO2-based catalysts as aqueous catalysts for the synthesis of Schiff base-containing bisphenol A compounds, compared with the conventional aldehyde-amine condensation of aromatic amine compounds and vanillin compounds, the addition of SiO2-based catalysts provides acidic catalytic sites that can trigger the protonation of the carbonyl group in the aldehyde, making it easier to combine with the amino group in the aromatic amine. In addition, the doping of transition metals Fe, Co, and Ni also greatly enhances the activity and water resistance of the SiO2-based catalyst, thereby solving the problem of catalyst deactivation in the aqueous phase.A 100% bio-based bisphenol A compound was constructed by using aromatic amine compounds, the products of microwave-assisted co-pyrolysis of lignin and nitrogen-containing polymers, and vanillin compounds, the products of microwave-assisted depolymerization of lignin. Compared with the simple CC bond of traditional bisphenol A compounds, the alkylimino group HC=N was successfully introduced through the dehydration reaction of the aldehyde group and the amino group. When cross-linking and curing were carried out using triamines (tris(2-aminoethyl)amine and tris(3-aminopropyl)amine) as curing agents, the imino group (HC-N) replaced the alkylimino group HC=N, introducing an epoxy resin network with a dynamic Schiff base. The resulting biomass-based multifunctional epoxy resin has good reprocessability and antibacterial properties.

[0026] Furthermore, extrusion granulation is divided into two temperature zones. In the first stage, the raw material is preheated to soften it, and in the second stage, it is molten to facilitate granulation. The separation conditions are set in an acidic solution, and then ethyl acetate and deionized water are used in a volume ratio of 2: (1 to 0.5) to extract the organic phase, and then vacuum distillation is performed at 70 to 80°C and 1.0 to 2.0 kPa to obtain aromatic amine compounds. Compared with traditional direct evaporation or direct vacuum distillation to separate the target product, in the acidic solution, the ionization of the solute and the decrease in the affinity between the solution and the solute make it easier to extract the target product, which greatly improves the separation efficiency of lignin depolymerization products, and also solves the problem of separating products from complex co-pyrolysis environments.

[0027] Furthermore, by using triamines (tris(2-aminoethyl)amine, tris(3-aminopropyl)amine) as curing agents for cross-linking and curing, compared with traditional diamines and secondary amines, the primary amine and triamine properties of tri(2-aminoethyl)amine and tri(3-aminopropyl)amine require lower energy and higher cross-linking density during cross-linking, and the higher cross-linking density makes its acid resistance better than other epoxy resins with Schiff base bonds.

[0028] The present invention also discloses a biomass-based multifunctional epoxy resin obtained by the above-mentioned preparation method. The glass transition temperature of the biomass-based multifunctional epoxy resin is 230-270°C; the antibacterial rate is 99.991%-99.998%; the strong acid resistance is manifested as no degradation occurs in a 10wt%-15wt% sulfuric acid solution at 50-60°C for 24-36 hours, and the shape of the biomass-based multifunctional epoxy resin can be changed by multiple grinding and hot pressing; compared with existing biomass-based synthetic epoxy resins, the glass transition temperature, antibacterial property, acid resistance and processability of the biomass-based multifunctional epoxy resin are improved by introducing a dynamic Schiff base.

[0029] The present invention also discloses the use of the above-mentioned biomass-based multifunctional epoxy resin in the preparation of high-temperature resistant electronic components, antibacterial diaphragms and acid-resistant equipment. The prepared biomass-based multifunctional epoxy resin can be applied to some components and equipment of outdoor industrial buildings due to its high glass transition temperature and acid resistance. In addition, its antibacterial properties can be utilized in the field of biomedicine. The biomass-based epoxy resin can effectively replace the single-functional epoxy resins currently on the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The present invention discloses a flow chart for the preparation of a biomass-based multifunctional epoxy resin. DETAILED DESCRIPTION

[0031] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0033] The present invention is described in further detail below with reference to the accompanying drawings:

[0034] The present invention prepares aromatic amine compounds through microwave-assisted co-pyrolysis of lignin and nitrogen-containing polymers, and prepares vanillin compounds through microwave-assisted depolymerization of lignin. The two are used to prepare 100% bio-based bisphenol A compounds, which are cross-linked and cured by triamines to prepare multifunctional epoxy resins with high glass transition temperature, reprocessability and good antibacterial properties. This provides a feasible idea for the synthesis of bio-based aromatic amine compounds and a strategy for constructing high-performance, multi-purpose bio-based epoxy resins.

[0035] See also Figure 1The flow chart of the preparation of the biomass-based multifunctional epoxy resin disclosed in the present invention is as follows. As can be seen from the figure, the preparation method of the biomass-based multifunctional epoxy resin includes the following steps:

[0036] 1) Lignin and a nitrogen-containing polymer are mixed in a mass ratio of 5:1:(1-0.8), stirred for 1-3 hours, and then extruded and granulated in a temperature range of 100-150°C and 180-210°C to obtain a wood-plastic polymer. The mixture is then washed with deionized water 3-5 times and dried at 55-75°C for 12-18 hours to obtain lignin nitrogen-based microspheres. The lignin nitrogen-based microspheres, a molecular sieve catalyst, and a microwave absorbing medium SiC are ball-milled in a mass ratio of 5:1:(1-0.5). The obtained powder is then subjected to microwave-assisted co-pyrolysis, and the liquid product is collected in -25°C ethanol cold hydrazine to obtain an aromatic amine-rich bio-oil.

[0037] Wherein, the lignin is any one of softwood lignin, hardwood lignin and herbaceous lignin;

[0038] The nitrogen-containing polymer is any one of a nitrile-amine polymer, an amide polymer, and an alcoholamine polymer;

[0039] The molecular sieve catalyst is any one of HZSM-5 molecular sieve, SAPO-34 molecular sieve and SBA-15 molecular sieve;

[0040] The parameters of the microwave-assisted co-pyrolysis were set as follows: a power of 1000-1500 W under N2 atmosphere, a temperature rise to 450-700°C, and a holding time of 5-10 min;

[0041] 2) placing the aromatic amine-rich bio-oil obtained in step 1) into a 3-5 mol / L HCl solution, extracting the obtained organic phase with an ethyl acetate and deionized water extractant in a volume ratio of 2:(1-0.5), and then performing reduced pressure distillation at 70-80° C. and 1.0-2.0 kPa to obtain aromatic amine compounds;

[0042] 3) impregnating the lignin in a formate solution having a concentration of 22 to 28 mol / L for 1 to 3 hours, followed by drying at 60 to 80°C for 12 to 24 hours, and then mixing the lignin with an oxygen carrier at a mass ratio of 1:(1 to 0.8) and stirring to obtain a mixed powder. The mixed powder is subjected to microwave-assisted depolymerization, and the liquid product is collected in -25°C ethanol cold hydrazine to obtain a vanillin-rich bio-oil;

[0043] Wherein, the lignin is any one of softwood lignin, hardwood lignin and herbaceous lignin;

[0044] The formate is any one of sodium formate, calcium formate and nickel formate;

[0045] The oxygen carrier is any one of Fe2O3, CuO and MoO2;

[0046] The parameters of the microwave-assisted depolymerization are set as follows: power of 1200-1800 W under N2 atmosphere, temperature raised to 500-800°C, and holding time of 10-20 min;

[0047] 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation at 60-70° C. and 1.3-2.3 kPa for 10-20 minutes, condensing the fraction in -25° C. ethanol cold hydrazine to collect the liquid component, then extracting the liquid component 3-6 times with ether to obtain an organic phase, and concentrating the organic phase at 20-30° C. and 1.5-2.5 kPa to obtain vanillin compounds;

[0048] 5) ball-milling the aromatic amine compound obtained in step 2) and the vanillin compound obtained in step 4) at a mass ratio of 1:(1-0.8), then placing 10 g of the ball-milled product and a spherical X-SiO2-based catalyst in a mass ratio of 1:(0.5-0.3) into 300-500 mL of deionized water, stirring for 4-6 hours to react, filtering and collecting the spherical X-SiO2-based catalyst and the reaction product powder, then separating the reaction product powder, washing it 5-8 times with deionized water at 80-90° C., and drying it at 80-120° C. for 12-18 hours to obtain a Schiff base-containing bisphenol A compound;

[0049] Wherein, the spherical X-SiO2-based catalyst is any one of Co-SiO2, Ni-SiO2 and Fe-SiO2;

[0050] The stirring conditions are a rotation speed of 800-1200 rpm and a temperature of 25-35°C;

[0051] 6) dissolving the Schiff base-containing bisphenol A compound obtained in step 5) and benzyltriethylammonium chloride in a mass ratio of 1:(1-0.8) in epichlorohydrin at 80-100° C. under a N2 atmosphere for 4-6 hours, then adding a 0.5-1 mol / L NaOH solution dropwise at a rate of 0.1-0.3 mL / min, reacting for 1-2 hours, and filtering. The filtrate is washed 3-5 times with deionized water at a temperature of 55-75° C., dried at 65-85° C. for 10-15 hours, and then distilled under reduced pressure at 75-85° C. and 1.5-2.5 kPa to obtain a Schiff base diepoxide compound;

[0052] 7) the Schiff base diepoxide obtained in step 6) and the triamine are stirred at a mass ratio of 10:(1-0.5), vacuum degassed, and then cured at 100-200° C. for 2-4 hours. The mixture is then ground into a powder and hot-pressed at 160-180° C. and 5-7 MPa for 1-3 hours to obtain a multifunctional epoxy resin. The obtained multifunctional epoxy resin is ground into a powder and hot-pressed at 160-180° C. and 5-7 MPa for 1-3 hours. The multifunctional epoxy resin can be repeatedly processed into multifunctional epoxy resins with different shapes.

[0053] Wherein, the triamine is any one of tris(2-aminoethyl)amine and tris(3-aminopropyl)amine;

[0054] The stirring conditions are: rotation speed 1000-1500 rpm, temperature 80-120°C, and stirring time 3-5 min;

[0055] The vacuum degassing pressure is -2 to -2.7 kPa;

[0056] The particle size of the powder is 1 to 10 mm.

[0057] Example 1

[0058] A method for preparing a biomass-based multifunctional epoxy resin comprises the following steps:

[0059] 1) 15 g of masson pine lignin and 3 g of nitrile amine polymer were mixed and stirred for 1 h, and then extruded and granulated in a temperature range of 100°C and 180°C to obtain a wood-plastic polymer. The mixture was then washed three times with deionized water and dried at 55°C for 18 h to obtain lignin nitrogen-based microspheres. 15 g of lignin nitrogen-based microspheres, 3 g of HZSM-5 molecular sieve, and 3 g of microwave absorbing medium SiC were ball-milled. The obtained powder was then microwave-assisted co-pyrolyzed at a power of 1000 W, heated to 450°C, and kept at this temperature for 10 min under a nitrogen atmosphere. The liquid product was collected in ethanol cold hydrazine at -25°C to obtain an aromatic amine-rich bio-oil.

[0060] 2) placing the aromatic amine-rich bio-oil obtained in step 1) into a 3 mol / L HCl solution, extracting the organic phase with 100 mL of ethyl acetate and 50 mL of deionized water, and then performing reduced pressure distillation at 70° C. and 2.0 kPa to obtain aromatic amine compounds, comprising 5-aminoguaiacol (35.6%), 4-aminoguaiacol (27.5%), 3-aminophenol (22.2%), and 4-aminophenol (14.7%);

[0061] 3) 15 g of Masson pine lignin was immersed in a 22 mol / L calcium formate solution for 1 h, then dried at 60°C for 24 h. The mixture was then mixed with 15 g of Fe2O3 and stirred to obtain a mixed powder. The mixed powder was microwave-assisted depolymerized at 1200 W in a nitrogen atmosphere at 500°C for 20 min. The liquid product was collected in ethanol cold hydrazine at -25°C to obtain a vanillin-rich bio-oil.

[0062] 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation at 60° C. and 2.3 kPa for 20 minutes, condensing the fraction in −25° C. ethanol cold hydrazine to collect the liquid component, then extracting the liquid component three times with ether to obtain an organic phase, and concentrating the organic phase at 20° C. and 2.5 kPa to obtain vanillin compounds comprising vanillin (41.2%), vanillic acid (25.9%), and o-vanillin (32.9%);

[0063] 5) ball-milling 5 g of the aromatic amine compound obtained in step 2) and 5 g of the vanillin compound obtained in step 4), then placing 10 g of the ball-milled product and 5 g of the spherical Co-SiO2-based catalyst into 300 mL of deionized water, stirring at 800 rpm and 25° C. for 4 h to react, collecting the spherical Co-SiO2-based catalyst and the reaction product powder by filtration, then separating the reaction product powder, washing it five times with 80° C. deionized water, and drying it at 80° C. for 18 h to obtain a Schiff base-containing bisphenol A compound;

[0064] 6) 5 g of the Schiff base-containing bisphenol A compound obtained in step 5) and 5 g of benzyltriethylammonium chloride were dissolved in epichlorohydrin at 80° C. under a N2 atmosphere, and the reaction was carried out for 4 h. Subsequently, a 1 mol / L NaOH solution was added dropwise at 0.1 mL / min, and the mixture was reacted for 1 h. The mixture was filtered, and the filtrate was washed three times with deionized water at 55° C. and dried at 65° C. for 15 h. The Schiff base diepoxide compound was then distilled under reduced pressure at 75° C. and 2.5 kPa to obtain the Schiff base diepoxide.

[0065] 7) 5 g of the Schiff base diepoxide obtained in step 6) was stirred with 0.5 g of tris(2-aminoethyl)amine at a speed of 1000 rpm, a temperature of 80° C., and a stirring time of 5 min. The mixture was then vacuum degassed at -2.7 kPa and then cured at 100° C. for 4 h. The mixture was then ground into a powder with a particle size of 1 mm and hot pressed at 160° C. and 7 MPa for 3 h to obtain a multifunctional epoxy resin.

[0066] The multifunctional epoxy resin has a glass transition temperature of 270°C, an antibacterial rate of 99.998% and strong acid resistance. The strong acid resistance is manifested in that it does not degrade in a 10wt% sulfuric acid solution at 50°C for 36 hours. After being ground into powder and hot-pressed at 160°C and 7MPa for 3 hours, it can be repeatedly processed into multifunctional epoxy resins with different shapes.

[0067] Example 2

[0068] A method for preparing a biomass-based multifunctional epoxy resin comprises the following steps:

[0069] 1) 15 g of poplar lignin and 2.4 g of amide polymer were mixed and stirred for 3 h, then extruded and granulated in a temperature range of 150°C and 210°C to obtain a wood-plastic polymer. The mixture was then washed with deionized water five times and dried at 75°C for 12 h to obtain lignin nitrogen-based microspheres. 15 g of lignin nitrogen-based microspheres, 3 g of SBA-15 molecular sieve, and 1.5 g of microwave absorbing medium SiC were ball-milled. The obtained powder was then subjected to microwave-assisted co-pyrolysis in a nitrogen atmosphere at a power of 1500 W, heated to 700°C, and kept at this temperature for 5 min. The liquid product was collected in ethanol cold hydrazine at -25°C to obtain an aromatic amine-rich bio-oil.

[0070] 2) placing the aromatic amine-rich bio-oil obtained in step 1) into a 5 mol / L HCl solution, extracting the organic phase with 100 mL of ethyl acetate and 25 mL of deionized water, and then performing reduced pressure distillation at 80° C. and 1.0 kPa to obtain aromatic amine compounds, comprising 5-aminoguaiacol (37.2%), 4-aminoguaiacol (31.4%), 3-aminophenol (21.3%), and 4-aminophenol (10.1%);

[0071] 3) 15 g of poplar lignin was immersed in a 28 mol / L nickel formate solution for 3 h, then dried at 80°C for 12 h. The mixture was then mixed with 12 g of CuO and stirred to obtain a mixed powder. The mixed powder was microwave-assisted depolymerized at 800°C for 10 min at a power of 1800 W under a nitrogen atmosphere. The liquid product was collected in ethanol cold hydrazine at -25°C to obtain a vanillin-rich bio-oil.

[0072] 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation at 70° C. and 1.3 kPa for 10 minutes, condensing the fraction in −25° C. ethanol cold hydrazine to collect the liquid component, then extracting the liquid component six times with ether to obtain an organic phase, and concentrating the organic phase at 30° C. and 1.5 kPa to obtain vanillin compounds comprising vanillin (43.4%), vanillic acid (21.9%), and o-vanillin (34.7%);

[0073] 5) ball-milling 5 g of the aromatic amine compound obtained in step 2) and 4 g of the vanillin compound obtained in step 4), then placing 9 g of the ball-milled product and 2.7 g of a spherical Fe-SiO2-based catalyst into 500 mL of deionized water, stirring at 1200 rpm and 35° C. for 6 h to react, collecting the spherical Fe-SiO2-based catalyst and the reaction product powder by filtration, then separating the reaction product powder, washing it 8 times with deionized water at 90° C., and drying it at 120° C. for 12 h to obtain a Schiff base-containing bisphenol A compound;

[0074] 6) 5 g of the Schiff base-containing bisphenol A compound obtained in step 5) and 4 g of benzyltriethylammonium chloride were dissolved in epichlorohydrin at 100° C. under a N2 atmosphere, and the reaction was carried out for 6 h. Subsequently, a 0.5 mol / L NaOH solution was added dropwise at 0.3 mL / min, and the reaction was carried out for 2 h. The mixture was filtered, and the filtrate was washed five times with deionized water at 75° C. and dried at 85° C. for 10 h. Subsequently, the Schiff base diepoxide was obtained by distillation at 85° C. and 1.5 kPa under reduced pressure.

[0075] 7) 8 g of the Schiff base diepoxide obtained in step 6) was stirred with 0.4 g of tris(3-aminopropyl)amine at a speed of 1500 rpm, a temperature of 120° C., and a stirring time of 3 min. The mixture was then vacuum degassed at -2.0 kPa and then cured at 200° C. for 2 h. The mixture was then ground into a powder with a particle size of 10 mm and hot pressed at 180° C. and 5 MPa for 1 h to obtain a multifunctional epoxy resin.

[0076] The multifunctional epoxy resin has a glass transition temperature of 230°C, an antibacterial rate of 99.991% and strong acid resistance. The strong acid resistance is manifested in that it does not degrade in a 15wt% sulfuric acid solution at 60°C for 24 hours. After being ground into powder and hot-pressed at 180°C and 5MPa for 1 hour, it can be repeatedly processed into multifunctional epoxy resins with different shapes.

[0077] Example 3

[0078] A method for preparing a biomass-based multifunctional epoxy resin comprises the following steps:

[0079] 1) 15 g of reed lignin and 2.7 g of alcohol amine polymer were mixed and stirred for 2 h, then extruded and granulated in a temperature range of 130°C and 190°C to obtain a wood-plastic polymer, which was then washed four times with deionized water and dried at 65°C for 15 h to obtain lignin nitrogen-based microspheres. 15 g of lignin nitrogen-based microspheres, 3 g of SAPO-15 molecular sieve, and 2.1 g of microwave absorbing medium SiC were ball-milled. The obtained powder was then microwave-assisted co-pyrolyzed at a power of 1200 W, heated to 600°C, and kept at this temperature for 8 min under a nitrogen atmosphere. The liquid product was collected in ethanol cold hydrazine at -25°C to obtain an aromatic amine-rich bio-oil;

[0080] 2) placing the aromatic amine-rich bio-oil obtained in step 1) into a 4 mol / L HCl solution, extracting the organic phase with 100 mL of ethyl acetate and 40 mL of deionized water, and then performing reduced pressure distillation at 75° C. and 1.5 kPa to obtain aromatic amine compounds, comprising 5-aminoguaiacol (31.6%), 4-aminoguaiacol (23.4%), 3-aminophenol (28.7%), and 4-aminophenol (16.3%);

[0081] 3) 15 g of reed lignin was immersed in a 24 mol / L sodium formate solution for 2 h, then dried at 70°C for 18 h. The mixture was then mixed with 13.5 g of MoO2 and stirred to obtain a mixed powder. The mixed powder was microwave-assisted depolymerized in a nitrogen atmosphere at a power of 1500 W, heated to 650°C, and held for 15 min. The liquid product was collected in ethanol cold hydrazine at -25°C to obtain a vanillin-rich bio-oil.

[0082] 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation at 65° C. and 1.8 kPa for 15 minutes, condensing the fraction in −25° C. ethanol cold hydrazine to collect the liquid component, then extracting the liquid component four times with ether to obtain an organic phase, and concentrating the organic phase at 25° C. and 2.0 kPa to obtain vanillin compounds, comprising vanillin (39.2%), vanillic acid (28.2%), and o-vanillin (32.6%);

[0083] 5) ball-milling 5 g of the aromatic amine compound obtained in step 2) and 4.5 g of the vanillin compound obtained in step 4), then placing 8 g of the ball-milled product and 3.2 g of a spherical Ni-SiO2-based catalyst in 400 mL of deionized water, stirring at 1000 rpm and 30° C. for 5 h to react, collecting the spherical Ni-SiO2-based catalyst and the reaction product powder by filtration, then separating the reaction product powder, washing it six times with deionized water at 85° C., and drying it at 100° C. for 15 h to obtain a Schiff base-containing bisphenol A compound;

[0084] 6) 6 g of the Schiff base-containing bisphenol A compound obtained in step 5) and 5.4 g of benzyltriethylammonium chloride were dissolved in epichlorohydrin at 90° C. under a N2 atmosphere, and the reaction was carried out for 5 h. Subsequently, a 0.8 mol / L NaOH solution was added dropwise at 0.2 mL / min, and the reaction was continued for 1.5 h. The mixture was filtered, and the filtrate was washed four times with deionized water at 65° C. and dried at 75° C. for 12 h. Subsequently, the Schiff base diepoxide was obtained by vacuum distillation at 80° C. and 2.0 kPa.

[0085] 7) 6 g of the Schiff base diepoxide obtained in step 6) was stirred with 0.42 g of tris(2-aminoethyl)amine at a speed of 1200 rpm, a temperature of 100° C., and a stirring time of 4 min. The mixture was then vacuum degassed at -2.2 kPa and then cured at 150° C. for 3 h. The mixture was then ground into a powder with a particle size of 5 mm and hot pressed at 170° C. and 6 MPa for 2 h to obtain a multifunctional epoxy resin.

[0086] The multifunctional epoxy resin has a glass transition temperature of 250°C, an antibacterial rate of 99.995% and strong acid resistance. The strong acid resistance is manifested in that it does not degrade in a 12wt% sulfuric acid solution at 55°C for 30 hours. After being ground into powder and hot-pressed at 170°C and 6MPa for 2 hours, it can be repeatedly processed into multifunctional epoxy resins with different shapes.

[0087] Example 4

[0088] A method for preparing a biomass-based multifunctional epoxy resin comprises the following steps:

[0089] 1) 15 g of wheat straw lignin and 2.55 g of an alcoholamine polymer were mixed and stirred for 1.5 h, and then extruded and granulated in a temperature range of 125° C. and 195° C. to obtain a wood-plastic polymer. The mixture was then washed four times with deionized water and dried at 60° C. for 16 h to obtain lignin nitrogen-based microspheres. 12 g of the lignin nitrogen-based microspheres, 2.4 g of HZSM-5 molecular sieve, and 1.68 g of microwave absorbing medium SiC were ball-milled. The obtained powder was then microwave-assisted co-pyrolyzed at 650° C. for 6 min under a nitrogen atmosphere at a power of 1400 W. The liquid product was collected in ethanol cold hydrazine at -25° C. to obtain an aromatic amine-rich bio-oil.

[0090] 2) placing the aromatic amine-rich bio-oil obtained in step 1) into a 3.5 mol / L HCl solution, extracting the organic phase with 100 mL of ethyl acetate and 37 mL of deionized water, and then performing reduced pressure distillation at 72° C. and 1.8 kPa to obtain aromatic amine compounds, comprising 5-aminoguaiacol (30.7%), 4-aminoguaiacol (25.6%), 3-aminophenol (29.8%), and 4-aminophenol (13.9%);

[0091] 3) 15 g of wheat straw lignin was immersed in a 23 mol / L calcium formate solution for 1.5 h, then dried at 65°C for 14 h. The mixture was then mixed with 12.5 g of MoO2 and stirred to obtain a mixed powder. The mixed powder was microwave-assisted depolymerized in a nitrogen atmosphere at a power of 1400 W, heated to 700°C, and held for 14 min. The liquid product was collected in cold ethanol at -25°C to obtain a vanillin-rich bio-oil.

[0092] 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation at 68° C. and 2.0 kPa for 18 minutes, condensing the fraction in −25° C. ethanol cold hydrazine to collect the liquid component, then extracting the liquid component five times with ether to obtain an organic phase, and concentrating the organic phase at 26° C. and 1.8 kPa to obtain vanillin compounds comprising vanillin (37.9%), vanillic acid (28.7%), and o-vanillin (33.4%);

[0093] 5) ball-milling 5 g of the aromatic amine compound obtained in step 2) and 4.8 g of the vanillin compound obtained in step 4), then placing 8 g of the ball-milled product and 3.6 g of a spherical Ni-SiO2-based catalyst in 400 mL of deionized water, stirring at 1100 rpm and 28° C. for 4.5 h to react, collecting the spherical Ni-SiO2-based catalyst and the reaction product powder by filtration, then separating the reaction product powder, washing it seven times with deionized water at 88° C., and drying it at 90° C. for 16 h to obtain a Schiff base-containing bisphenol A compound;

[0094] 6) 5 g of the Schiff base-containing bisphenol A compound obtained in step 5) and 4.25 g of benzyltriethylammonium chloride were dissolved in epichlorohydrin at 85° C. under a N2 atmosphere, and the reaction was carried out for 4.5 h. Subsequently, a 0.85 mol / L NaOH solution was added dropwise at 0.15 mL / min, and the reaction was carried out for 1.8 h. The mixture was filtered, and the filtrate was washed three times with deionized water at 60° C. and dried at 70° C. for 14 h. The Schiff base diepoxide compound was then distilled under reduced pressure at 85° C. and 1.8 kPa to obtain the Schiff base diepoxide;

[0095] 7) 5 g of the Schiff base diepoxide obtained in step 6) was stirred with 0.3 g of tris(2-aminoethyl)amine at a speed of 1300 rpm, a temperature of 90° C., and a stirring time of 3.5 min. The mixture was then vacuum degassed at -2.6 kPa and then cured at 180° C. for 2.5 h. The mixture was then ground into a powder with a particle size of 5 mm and hot pressed at 165° C. and 5.5 MPa for 1.5 h to obtain a multifunctional epoxy resin.

[0096] The multifunctional epoxy resin has a glass transition temperature of 245°C, an antibacterial rate of 99.996% and strong acid resistance. The strong acid resistance is manifested in that it does not degrade in a 13wt% sulfuric acid solution at 58°C for 28 hours. After being ground into powder, it is hot-pressed at 175°C and 6.5MPa for 2.5 hours and can be repeatedly processed into multifunctional epoxy resins with different shapes.

[0097] Example 5

[0098] A method for preparing a biomass-based multifunctional epoxy resin comprises the following steps:

[0099] 1) 15 g of moso bamboo lignin and 2.85 g of amide polymer were mixed and stirred for 2.5 h, then extruded and granulated at a temperature range of 145°C and 205°C to obtain a wood-plastic polymer. The mixture was then washed three times with deionized water and dried at 70°C for 13 h to obtain lignin nitrogen-based microspheres. 15 g of lignin nitrogen-based microspheres, 3 g of SAPO-15 molecular sieve, and 1.8 g of microwave absorbing medium SiC were ball-milled. The obtained powder was then subjected to microwave-assisted co-pyrolysis at a power of 1250 W, heated to 550°C, and held at this temperature for 9 min under a nitrogen atmosphere. The liquid product was collected in ethanol cold hydrazine at -25°C to obtain a bio-oil rich in aromatic amines.

[0100] 2) placing the aromatic amine-rich bio-oil obtained in step 1) into a 4.5 mol / L HCl solution, extracting the organic phase with 100 mL of ethyl acetate and 35 mL of deionized water, and then performing reduced pressure distillation at 76° C. and 1.3 kPa to obtain aromatic amine compounds, comprising 5-aminoguaiacol (34.7%), 4-aminoguaiacol (21.5%), 3-aminophenol (26.1%), and 4-aminophenol (17.7%);

[0101] 3) 15 g of bamboo lignin was immersed in a 27 mol / L sodium formate solution for 2.5 h, dried at 78°C for 14 h, and then mixed with 14.5 g of CuO and stirred to obtain a mixed powder. The mixed powder was microwave-assisted depolymerized at 1600 W under a nitrogen atmosphere at 750°C for 16 min. The liquid product was collected in cold ethanol at -25°C to obtain a vanillin-rich bio-oil.

[0102] 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation at 68° C. and 1.4 kPa for 13 minutes, condensing the fraction in −25° C. ethanol cold hydrazine to collect the liquid component, then extracting the liquid component five times with ether to obtain an organic phase, and concentrating the organic phase at 26° C. and 1.6 kPa to obtain vanillin compounds comprising vanillin (38.5%), vanillic acid (26.9%), and o-vanillin (34.6%);

[0103] 5) ball-milling 5 g of the aromatic amine compound obtained in step 2) and 4.4 g of the vanillin compound obtained in step 4), then placing 9 g of the ball-milled product and 3.8 g of a spherical Co-SiO2-based catalyst in 400 mL of deionized water, stirring at 900 rpm and 28° C. for 5.5 h to react, collecting the spherical Co-SiO2-based catalyst and the reaction product powder by filtration, then separating the reaction product powder, washing it seven times with deionized water at 84° C., and drying it at 110° C. for 13 h to obtain a Schiff base-containing bisphenol A compound;

[0104] 6) 5 g of the Schiff base-containing bisphenol A compound obtained in step 5) and 4.6 g of benzyltriethylammonium chloride were dissolved in epichlorohydrin at 95° C. under a N2 atmosphere, and the reaction was carried out for 5.5 h. Subsequently, a 0.95 mol / L NaOH solution was added dropwise at 0.25 mL / min, and the reaction was carried out for 1.8 h. The mixture was filtered, and the filtrate was washed five times with deionized water at 70° C. and dried at 80° C. for 14 h. The Schiff base diepoxide compound was then distilled under reduced pressure at 82° C. and 1.6 kPa to obtain the Schiff base diepoxide;

[0105] 7) 5 g of the Schiff base diepoxide obtained in step 6) was stirred with 0.35 g of tris(2-aminoethyl)amine at a speed of 1400 rpm, a temperature of 110° C., and a stirring time of 4.5 min. The mixture was then vacuum degassed at -2.3 kPa and then cured at 170° C. for 3.5 h. The mixture was then ground into a powder with a particle size of 5 mm and hot pressed at 175° C. and 6.5 MPa for 2.5 h to obtain a multifunctional epoxy resin.

[0106] The multifunctional epoxy resin has a glass transition temperature of 265°C, an antibacterial rate of 99.997% and strong acid resistance. The strong acid resistance is manifested in that it does not degrade in a 14wt% sulfuric acid solution at 54°C for 32 hours. After being ground into powder, it is hot-pressed at 165°C and 5.5MPa for 1.5 hours and can be repeatedly processed into multifunctional epoxy resins with different shapes.

[0107] The present invention subjects lignin to microwave-assisted co-pyrolysis and pre-impregnation microwave-assisted pyrolysis to prepare aromatic amine-rich bio-oil and vanillin-rich bio-oil, thereby further reducing their molecular weight so that they have abundant hydroxyl groups at the same mass, and effectively improve the functionality of biomass-based epoxy resin by introducing Schiff base.

[0108] The above content is only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a biomass-based multifunctional epoxy resin, characterized in that: The following steps are involved: 1) The lignin and nitrogen-containing polymer are mixed and stirred uniformly, and then extruded and granulated to obtain a wood-plastic polymer; After washing and drying, lignin nitrogen-based microspheres are obtained; the lignin nitrogen-based microspheres, molecular sieve catalyst and microwave absorption medium are mixed and ball-milled, and then microwave-assisted co-pyrolysis is performed, and liquid products are collected to obtain aromatic amine-rich bio-oil; the nitrogen-containing polymer is any one of a nitrile amine polymer, an amide polymer and an alcoholamine polymer; 2) placing the aromatic amine-rich bio-oil obtained in step 1) into an HCl solution, extracting and distilling under reduced pressure to obtain aromatic amine compounds; 3) impregnating the lignin in a formate solution, drying it, and obtaining a treated lignin powder, which is then mixed with an oxygen carrier, stirred, and subjected to microwave-assisted depolymerization. The liquid product is collected to obtain a vanillin-rich bio-oil; 4) subjecting the vanillin-rich bio-oil obtained in step 3) to vacuum distillation, condensing and collecting the liquid component, extracting the organic phase, and concentrating the organic phase to obtain vanillin compounds; 5) ball-milling the aromatic amine compound obtained in step 2) and the vanillin compound obtained in step 4) to obtain a mixed product, which is then placed in deionized water with a spherical X-SiO2-based catalyst, stirred for reaction, and filtered to obtain the spherical X-SiO2-based catalyst and a reaction product powder; then separating the reaction product powder, washing it, and drying it to obtain a Schiff base-containing bisphenol A compound; the spherical X-SiO2-based catalyst is any one of Co-SiO2, Ni-SiO2, and Fe-SiO2; 6) dissolving the Schiff base-containing bisphenol A compound and benzyltriethylammonium chloride obtained in step 5) in epichlorohydrin under a nitrogen atmosphere. After the reaction is completed, adding a NaOH solution, stirring for 1 to 2 hours, filtering, washing, drying, and distilling under reduced pressure to obtain a Schiff base diepoxide compound. 7) The Schiff base diepoxide obtained in step 6) is mixed with triamine and stirred, and then vacuum degassed. After curing, grinding, and hot pressing, a biomass-based multifunctional epoxy resin is obtained.

2. The method for preparing a biomass-based multifunctional epoxy resin according to claim 1, wherein In step 1), the mass ratio of the lignin to the nitrogen-containing polymer is 5:(1-0.8); the stirring time is 1-3 h; the extrusion granulation conditions are: extrusion granulation within the temperature range of 100-150°C and 180-210°C; the drying conditions are: drying at 55-75°C for 12-18 h; the mass ratio of the lignin nitrogen-based microspheres to the molecular sieve catalyst to the microwave absorption medium is 5:1:(1-0.5); the microwave absorption medium is SiC; the lignin is any one of coniferous wood lignin, hardwood wood lignin, and herbaceous lignin; the molecular sieve catalyst is any one of HZSM-5 molecular sieve, SAPO-34 molecular sieve, and SBA-15 molecular sieve; the parameters of the microwave-assisted co-pyrolysis are set as follows: a power of 1000-1500 W under N2 atmosphere, a temperature rise to 450-700°C, and a heat preservation reaction for 5-10 min.

3. The method for preparing a biomass-based multifunctional epoxy resin according to claim 1, wherein In step 2), the concentration of the HCl solution is 3-5 mol / L; the extraction liquid used in the extraction is prepared by mixing ethyl acetate and deionized water in a volume ratio of 2:(1-0.5); the temperature of the reduced pressure distillation is 70-80°C, and the pressure of the reduced pressure distillation is 1.0-2.0 kPa.

4. The method for preparing a biomass-based multifunctional epoxy resin according to claim 1, wherein In step 3), the concentration of the formate solution is 22-28 mol / L; the impregnation time is 1-3 h; the drying conditions are: drying at 60-80°C for 12-24 h; the mass ratio of the treated lignin powder:oxygen carrier is 1:(1-0.8); the formate is any one of sodium formate, calcium formate and nickel formate; the oxygen carrier is any one of Fe2O3, CuO and MoO2; the parameters of the microwave-assisted depolymerization are set as 1200-1800 W power under N2 atmosphere, heating to 500-800°C, and keeping the reaction warm for 10-20 min.

5. The method for preparing a biomass-based multifunctional epoxy resin according to claim 1, wherein In step 4), the temperature of the vacuum distillation is 60-70°C, the pressure of the vacuum distillation is 1.3-2.3 kPa, and the time of the vacuum distillation is 10-20 min; the temperature of the concentration is 20-30°C, and the pressure of the concentration is 1.5-2.5 kPa.

6. The method for preparing a biomass-based multifunctional epoxy resin according to claim 1, wherein In step 5), the mass ratio of the aromatic amine compound to the vanillin compound is 1:(1-0.8); the mass ratio of the mixed product to the spherical X-SiO2-based catalyst is 1:(0.5-0.3); the stirring reaction conditions are: a speed of 800-1200 rpm, a reaction at 25-35°C for 4-6 hours; the washing conditions are: using deionized water at 80-90°C, washing 5-8 times; the drying conditions are: drying at 80-120°C for 12-18 hours.

7. The method for preparing a biomass-based multifunctional epoxy resin according to claim 1, wherein In step 6), the mass ratio of the Schiff base-containing bisphenol A compound to benzyltriethylammonium chloride is 1:(1-0.8); the reaction conditions are: reaction at 80-100°C for 4-6 hours; the washing conditions are: washing 3-5 times with deionized water at a temperature of 55-75°C; the drying conditions are: drying at 65-85°C for 10-15 hours; the temperature of the reduced pressure distillation is 75-85°C, and the pressure of the reduced pressure distillation is 1.5-2.5 kPa.

8. The method for preparing a biomass-based multifunctional epoxy resin according to claim 1, wherein In step 7), the mass ratio of the Schiff base diepoxide compound to the triamine is 10:(1-0.5); the stirring conditions are: stirring at a speed of 1000-1500 rpm and at 80-120°C for 3-5 min; the vacuum degassing pressure is -2--2.7 kPa; the curing conditions are: keeping warm at 100-200°C for 2-4 h; the hot pressing conditions are: hot pressing at 160-180°C and 5-7 MPa for 1-3 h; the shape of the biomass-based multifunctional epoxy resin can be changed by multiple grinding and hot pressing; the triamine is any one of tris(2-aminoethyl)amine and tris(3-aminopropyl)amine.

9. A biomass-based multifunctional epoxy resin prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The biomass-based multifunctional epoxy resin has a glass transition temperature of 230-270°C, an antibacterial rate of 99.991%-99.998%, and strong acid resistance, as evidenced by no degradation within 24-36 hours in a 10 wt%-15 wt% sulfuric acid solution at 50-60°C.

10. Use of the biomass-based multifunctional epoxy resin according to claim 9 in the preparation of temperature-resistant electronic components, antibacterial diaphragms and acid-resistant equipment.

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