Lignin-based waterborne epoxy resin emulsion as well as preparation method and application thereof

Abstract

The invention discloses lignin-based waterborne epoxy resin emulsion as well as a preparation method and application thereof, and belongs to the technical field of high polymer materials. The lignin-based epoxy resin is prepared by taking lignin modified bisphenol A as a raw material and carrying out ring-opening reaction on the lignin modified bisphenol A and epoxy chloropropane under the action of a phase transfer catalyst and then carrying out ring-closing reaction in the presence of alkali; and mixing the lignin-based epoxy resin with an emulsifier for reaction, and dropwise adding deionized water for phase inversion treatment to obtain the lignin-based waterborne epoxy resin emulsion. The lignin-modified bisphenol A is used as a raw material to prepare the novel bio-based epoxy resin, the key problems that lignin is complex in chemical structure and composition, low in reaction activity and the like and influences application of the lignin are effectively solved, and the prepared lignin-based water-borne epoxy resin emulsion has good storage stability, uniform particle size distribution and good water resistance. The problems that lignin-based epoxy resin is difficult to disperse and poor in compatibility in emulsified asphalt can be effectively solved, and the obtained modified asphalt material has excellent mechanical properties.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer materials, and particularly relates to a lignin-based waterborne epoxy resin emulsion and a preparation method and application thereof. Background Art

[0002] Emulsified asphalt has advantages such as a wide range of raw materials, low cost, simple construction, and no need for heating, making it widely used in road construction, building waterproofing, and other fields. However, conventional emulsified asphalt suffers from low bond strength, poor shear strength, and insufficient thermal and storage stability, which seriously restricts its application in high-performance functional layers.

[0003] Epoxy resins are a class of thermosetting polymers with exceptional properties, including excellent bonding, chemical resistance, and cure shrinkage. Asphalt materials produced using them as modifiers not only retain the advantages of emulsified asphalt, requiring no heating and simplifying construction, but also exhibit excellent mechanical properties and high- and low-temperature stability, offering broad application prospects. However, the synthesis of epoxy resins currently relies primarily on fossil resources, with bisphenol A accounting for over 85% of these. With growing concern about environmental and resource issues, the development of green, environmentally friendly epoxy resins using renewable biomass as an alternative to traditional fossil resources has become a research hotspot.

[0004] Lignin is a natural phenolic macromolecular compound with abundant reserves in nature. It is widely available and cheap, and contains multiple active groups such as phenolic hydroxyl, alcoholic hydroxyl, and carboxyl groups in its molecular structure. It can replace traditional fossil resources to synthesize epoxy resins, and its particularly large molecular rigid skeleton can give epoxy resin materials good mechanical properties and thermal stability. However, lignin has a complex structure and composition, low reactivity, and is insoluble in most organic solvents, which seriously limits its application in epoxy resin synthesis. In addition, although the synthesis and application research of lignin-based epoxy resins have made certain progress, the epoxy resin obtained has a large viscosity at room temperature, is difficult to effectively disperse in emulsified asphalt, and has poor compatibility with emulsified asphalt, which not only brings inconvenience to practical applications, but also greatly affects the mechanical properties of the asphalt material after solidification. Summary of the Invention

[0005] The first technical problem to be solved by the present invention is to provide a lignin-based water-based epoxy resin emulsion, which has good storage stability and uniform particle size distribution, and can effectively solve the problems of lignin-based epoxy resin being difficult to disperse and having poor compatibility in emulsified asphalt; the second technical problem to be solved by the present invention is to provide a preparation method of the lignin-based water-based epoxy resin emulsion, which is simple, easy to operate and industrially produced; the third technical problem to be solved by the present invention is to provide an application of the lignin-based water-based epoxy resin emulsion in emulsified asphalt modification.

[0006] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0007] A method for preparing a lignin-based waterborne epoxy resin emulsion comprises the following steps: using lignin-modified bisphenol A as a raw material and carrying out a ring-opening reaction with epichlorohydrin in the presence of a phase transfer catalyst, followed by a ring-closing reaction in the presence of an alkali, to prepare a lignin-based epoxy resin; then, mixing the lignin-based epoxy resin with an emulsifier, reacting the mixture, and dropwise adding deionized water to carry out a phase inversion treatment, to obtain the lignin-based waterborne epoxy resin emulsion.

[0008] Furthermore, the step of modifying bisphenol A with lignin is as follows: lignin and bisphenol A are melt-mixed in a mass ratio of 1:9 to 4:1, concentrated sulfuric acid accounting for 2 to 20% of the total mass of the reactants is added as a catalyst, and the mixture is reacted at 110 to 170° C. for 1 to 6 hours. After the reaction is completed, the product is washed with deionized water until it is neutral, residual acid catalyst is removed, and the mixture is dried to obtain lignin-modified bisphenol A; the lignin is selected from any one of alkali lignin, enzymatic lignin, sulfate lignin, lignin sulfonate, and chemical pulp lignin.

[0009] Furthermore, the phase transfer catalyst is selected from any one of tetrabutylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, and tetrabutylammonium hydrogen sulfate, or a mixture of two or more thereof, and the amount used is 1 to 5% of the mass of the lignin-modified bisphenol A.

[0010] Furthermore, the alkali is selected from any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide, or a mixture of two or more thereof, and the molar ratio of the alkali to the phenolic hydroxyl group in the lignin-modified bisphenol A is 0.5 to 2.5:1.

[0011] Furthermore, the ring-opening reaction temperature is 70-120° C., the ring-opening reaction time is 2-10 h, the ring-closing reaction temperature is 40-80° C., and the ring-closing reaction time is 1-5 h.

[0012] Furthermore, the step of reacting the lignin-based epoxy resin with the emulsifier is: melt-mixing the lignin-based epoxy resin and the emulsifier in a mass ratio of 9:1 to 1:1, reacting at 100 to 140° C. for 1 to 5 hours, cooling to 60 to 90° C., slowly adding deionized water under stirring conditions, and performing emulsification and dispersion treatment to obtain a lignin-based water-based epoxy resin emulsion with a solid content of 30 to 55%.

[0013] Furthermore, the method for preparing the lignin-based waterborne epoxy resin emulsion prepares the lignin-based waterborne epoxy resin emulsion.

[0014] Furthermore, the lignin-based waterborne epoxy resin emulsion is used in emulsified asphalt modification.

[0015] Furthermore, the lignin-based water-based epoxy resin emulsion and the emulsified asphalt are mixed in a mass ratio of 1 to 1.5:1, a curing agent is added, and after mixing evenly, the mixture is allowed to stand at room temperature to dry on the surface, and then cured at 80 to 180°C for 1 to 6 hours to obtain a lignin-based water-based epoxy resin modified asphalt material.

[0016] Furthermore, the curing agent is selected from one or more of polyamide, polyetheramine, alicyclic amine, and fatty amine, and the molar ratio of the active hydrogen content to the epoxy group of the amine curing agent is 0.8:1 to 2:1.

[0017] Compared with the prior art, the present invention has the following advantages:

[0018] (1) The present invention uses lignin-modified bisphenol A as a raw material to prepare a new bio-based epoxy resin, effectively overcoming the key problems affecting the application of lignin, such as the complex chemical structure and composition and low reactivity, and achieving a high-proportion replacement of bisphenol A. This is of great significance for promoting the high-value utilization of lignin resources and expanding its application in the field of high-performance polymer materials.

[0019] (2) The method for preparing a lignin-based waterborne epoxy resin emulsion according to the present invention is simple, easy to operate, and can be industrially produced. The prepared lignin-based waterborne epoxy resin emulsion has good storage stability and uniform particle size distribution. It can effectively solve the problems of difficulty in dispersing and poor compatibility of lignin-based epoxy resin in emulsified asphalt. The resulting modified asphalt material has excellent mechanical properties and has broad application prospects in the fields of road transportation, building waterproofing, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the infrared spectrum of the lignin-based epoxy resin (LEP1) in Example 1 of the present application;

[0021] Figure 2 A physical picture of the lignin-based waterborne epoxy resin emulsion prepared for this application. DETAILED DESCRIPTION

[0022] The present invention will be further illustrated below with reference to specific examples. The examples are implemented based on the technical solutions of the present invention. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention.

[0023] The emulsifiers in the following examples were prepared according to the method of Example 3 in Chinese invention patent 202110214043.X.

[0024] In the following examples, the lignin is alkali lignin, enzymatic lignin, sulfate lignin, lignin sulfonate, and chemical pulp lignin; polyetheramine D230, isophorone diamine, and hexamethylenediamine are all commercially available; and the polyamide curing agent (PA, Y330, amine value 330±20 mg / g) is from the Research Institute of Forest Products Chemical Industry, Chinese Academy of Forestry.

[0025] The average particle size test method in the following examples includes the following steps: taking a small amount of lignin waterborne epoxy resin emulsion sample into a beaker, diluting it to 0.5% with water, and characterizing the particle size distribution of the emulsion using a 2000nm-ZS laser particle size meter.

[0026] The pull-out strength performance test in the following embodiment includes the following steps: uniformly coating the modified asphalt on the surface of the substrate (0.3 kg / m 2 ), after the surface is dry, place the pulling head on the surface of the bonding layer and press for a few seconds to ensure complete bonding and fixation. After curing and cooling at a certain temperature, use the SJ-10 facing tile bonding strength tester to measure its pulling strength.

[0027] Example 1

[0028] 1) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, 60 g of alkali lignin and 40 g of bisphenol A were added. After stirring and heating to 170°C until melted, 10 g of concentrated sulfuric acid was slowly added dropwise and stirred for 2 hours. After the reaction, the concentrated sulfuric acid was removed by washing three times with deionized water. The solid was dried to yield 72 g of lignin-modified bisphenol A (L1) with a hydroxyl value of 318 mg / g.

[0029] 2) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, add 15 g of L1 and 300 g of epichlorohydrin, stir to dissolve, add 0.3 g of benzyltriethylammonium chloride, and heat to 110°C and reflux for 5 h. Cool to 50°C, then add 4.1 g of sodium hydroxide in portions and heat to 60°C for 4 h. After the reaction, wash three times with water, and distill the organic phase under reduced pressure to obtain a lignin-based epoxy resin (LEP1) with an epoxy value of 0.36 mol / 100 g.

[0030] Figure 1 This is the infrared spectrum of lignin-based epoxy resin (LEP1), and it can be seen that 3456cm -1 The broad peak at 2925 cm is the characteristic absorption peak of -OH. -1 The peaks at 1713 cm are the CH stretching vibration absorption peaks of -OCH3 and -CH3 and -CH2- in the side chains. -1 The characteristic absorption peak of C=O is 1592cm -1 、1498cm -1 、1454cm -1 The characteristic absorption peak of lignin phenylpropane skeleton is at 907cm-1 The absorption peak is the characteristic absorption peak of the epoxy group, and the relevant characterization shows that the lignin-based epoxy resin was successfully prepared.

[0031] 3) In a four-necked round-bottom flask equipped with a stirrer, a thermometer, and a reflux condenser, 20 g of LEP1 and 6 g of emulsifier were added, and the mixture was stirred at 130° C. for 4 h. The temperature was then lowered to 80° C., and an appropriate amount of deionized water was slowly added dropwise with vigorous stirring to obtain a lignin-based waterborne epoxy resin emulsion (WLEP1) with a solid content of 30 wt.%, a Z-average particle size of 420 nm, and a room temperature storage stability of more than 6 months. Figure 2 shown.

[0032] 4) 11g WLEP1, 11g emulsified asphalt, and 2g polyamide curing agent (PA, Y330) were mixed and stirred evenly. The mixture was applied to the surface of the cement substrate and cured at room temperature until the surface was dry. It was then cured at 140°C for 2h. After cooling to room temperature and standing for one week, the tensile strength was measured to be 3.78kN, an increase of 45.9% compared to the emulsified asphalt.

[0033] Example 2

[0034] 1) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, 60 g of alkali lignin and 40 g of bisphenol A were added. After stirring and heating to 170°C until melted, 10 g of concentrated sulfuric acid was slowly added dropwise and stirred for 2 hours. After the reaction, the concentrated sulfuric acid was removed by washing three times with deionized water. The solid was dried to yield 72 g of lignin-modified bisphenol A (L1) with a hydroxyl value of 318 mg / g.

[0035] 2) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, add 15 g of L1 and 300 g of epichlorohydrin, stir to dissolve, add 0.3 g of benzyltriethylammonium chloride, and heat to 110°C and reflux for 5 h. Cool to 50°C, then add 4.1 g of sodium hydroxide in portions and heat to 60°C for 4 h. After the reaction, wash three times with water, and distill the organic phase under reduced pressure to obtain a lignin-based epoxy resin (LEP1) with an epoxy value of 0.36 mol / 100 g.

[0036] 3) In a four-necked round-bottom flask equipped with a stirrer, a thermometer, and a reflux condenser, 20 g of LEP1 and 6 g of emulsifier were added, and the mixture was stirred at 130° C. for 4 h. The temperature was then lowered to 80° C., and an appropriate amount of deionized water was slowly added dropwise with vigorous stirring to obtain a lignin-based waterborne epoxy resin emulsion (WLEP1) with a solid content of 30 wt.%, a Z-average particle size of 420 nm, and a room temperature storage stability of more than 6 months. Figure 2 shown.

[0037] 4) Mix 15g WLEP1, 13g emulsified asphalt, and 2.4g polyetheramine curing agent (D230), stir evenly, apply to the surface of the cement substrate, and cure at room temperature until the surface is dry. Cure at 140°C for 2h, cool to room temperature, and let it stand for one week. The tensile strength is 3.53kN, which is 36.3% higher than that of emulsified asphalt.

[0038] Example 3

[0039] 1) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, 20 g of kraft lignin and 80 g of bisphenol A were added and heated to 170°C with stirring until melted. 20 g of concentrated sulfuric acid was then slowly added dropwise and stirred for 3 h. After the reaction, the concentrated sulfuric acid was removed by washing three times with deionized water. The solid was then dried to yield 87 g of lignin-modified bisphenol A (L2) with a hydroxyl value of 387 mg / g.

[0040] 2) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, add 13.2 g of L2 and 300 g of epichlorohydrin, stir to dissolve, add 0.30 g of tetrabutylammonium bromide, and heat to 90°C for 4 h. Cool to 50°C, add 4.37 g of sodium hydroxide in portions, and heat to 70°C for 3 h. After the reaction, wash with water three times, and distill the organic phase under reduced pressure to obtain a lignin-based epoxy resin (LEP2) with an epoxy value of 0.38 mol / 100 g.

[0041] 3) In a four-necked round-bottom flask equipped with a stirrer, a thermometer, and a reflux condenser, 30 g of LEP2 and 12 g of emulsifier were added, and the mixture was stirred at 140° C. for 4 h. The temperature was then lowered to 80° C., and an appropriate amount of deionized water was slowly added dropwise with vigorous stirring to obtain a lignin-based waterborne epoxy resin emulsion (WLEP2) with a solid content of 40 wt.%, a Z-average particle size of 398 nm, and a room temperature storage stability of more than 6 months. Figure 2 shown.

[0042] 4) 7g of WLEP2, 7g of emulsified asphalt, and 2g of isophorone diamine were mixed and stirred evenly. The mixture was applied to the surface of a cement substrate and cured at room temperature until the surface was dry. The mixture was then cured at 140°C for 2 hours. After cooling to room temperature and allowing to stand for one week, the tensile strength was measured to be 7.67 kN, a 196% increase compared to the emulsified asphalt.

[0043] Example 4

[0044] 1) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, 20 g of kraft lignin and 80 g of bisphenol A were added and heated to 170°C with stirring until melted. 20 g of concentrated sulfuric acid was then slowly added dropwise and stirred for 3 h. After the reaction, the concentrated sulfuric acid was removed by washing three times with deionized water. The solid was then dried to yield 87 g of lignin-modified bisphenol A (L2) with a hydroxyl value of 387 mg / g.

[0045] 2) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, add 13.2 g of L2 and 300 g of epichlorohydrin, stir to dissolve, add 0.30 g of tetrabutylammonium bromide, and heat to 90°C for 4 h. Cool to 50°C, add 4.37 g of sodium hydroxide in portions, and heat to 70°C for 3 h. After the reaction, wash with water three times, and distill the organic phase under reduced pressure to obtain a lignin-based epoxy resin (LEP2) with an epoxy value of 0.38 mol / 100 g.

[0046] 3) In a four-necked round-bottom flask equipped with a stirrer, a thermometer, and a reflux condenser, 30 g of LEP2 and 12 g of emulsifier were added, and the mixture was stirred at 140° C. for 4 h. The temperature was then lowered to 80° C., and an appropriate amount of deionized water was slowly added dropwise with vigorous stirring to obtain a lignin-based waterborne epoxy resin emulsion (WLEP2) with a solid content of 40 wt.%, a Z-average particle size of 398 nm, and a room temperature storage stability of more than 6 months. Figure 2 shown.

[0047] 4) 15g WLEP2, 13.2g emulsified asphalt, and 2.4g hexamethylenediamine were mixed and stirred evenly. The mixture was applied to the surface of the cement substrate and cured at room temperature until the surface was dry. The mixture was cured at 140°C for 2h. After cooling to room temperature and standing for one week, the tensile strength was measured to be 3.98kN, a 54% increase compared to the emulsified asphalt.

[0048] Example 5

[0049] 1) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, 80 g of enzymatically hydrolyzed lignin and 20 g of bisphenol A were added. The mixture was heated to 110°C with stirring. 2 g of concentrated sulfuric acid was slowly added dropwise and stirred for 6 h. After the reaction, the mixture was washed three times with deionized water to remove the concentrated sulfuric acid. The solid was dried to yield 83 g of lignin-modified bisphenol A (L3) with a hydroxyl value of 327 mg / g.

[0050] 2) In a four-necked round-bottom flask equipped with a stirrer, thermometer, and reflux condenser, add 16 g of L3 and 300 g of epichlorohydrin, stir to dissolve, add 0.8 g of tetrabutylammonium bromide, and heat to 120°C for 4 h. Cool to 70°C, then add 3.71 g of sodium hydroxide in portions and react for 5 h. After the reaction, wash with water three times, and distill the organic phase under reduced pressure to obtain a lignin-based epoxy resin (LEP3) with an epoxy value of 0.33 mol / 100 g.

[0051] 3) In a four-necked round flask with stirrer, thermometer and reflux condenser, 30 g LEP3, 30 g emulsifier were added, stirred at 100 °C for 5 h, then cooled to 80 °C, slowly added with appropriate amount of deionized water under vigorous stirring to disperse, and a lignin-based waterborne epoxy resin emulsion (WLEP3) with 30 wt.% solid content was obtained, with Z-average particle size of 367 nm, room temperature storage stability of more than 6 months, and WLEP3 as shown in Figure 2 .

[0052] 4) 15 g WLEP3, 10 g emulsified asphalt and 1.92 g hexanediamine were mixed and uniformly stirred, coated on the surface of a cement base material, cured to surface dry at room temperature, cured at 80 °C for 6 h, and after cooling to room temperature, left to stand for one week, and the pull-off strength was measured to be 3.41 kN, increased by 32% compared with emulsified asphalt.

[0053] Example 6

[0054] 1) In a four-necked round flask with stirrer, thermometer and reflux condenser, 80 g enzymatic lignin, 20 g bisphenol A were added, stirred and heated to 110 °C, slowly added with 2 g concentrated sulfuric acid, and stirred for 6 h. After the reaction was completed, deionized water was used for washing 3 times to remove the concentrated sulfuric acid, and the solid was dried to obtain 83 g of lignin-modified bisphenol A (L3), with a hydroxyl value of 327 mg / g.

[0055] 2) In a four-necked round flask with stirrer, thermometer and reflux condenser, 16 g L3, 300 g epoxy chloropropane were added and stirred to dissolve, 0.8 g tetrabutylammonium bromide was added, and the temperature was raised to 70 °C for 10 h. After cooling to 70 °C, 3.71 g sodium hydroxide was added in batches, and the reaction was carried out for 5 h. After the reaction was completed, water was used for washing 3 times, and the organic phase was distilled under reduced pressure to obtain a lignin-based epoxy resin (LEP4), with an epoxy value of 0.28 mol / 100 g.

[0056] 3) In a four-necked round flask with stirrer, thermometer and reflux condenser, 30 g LEP4, 3.3 g emulsifier were added, stirred at 100 °C for 5 h, then cooled to 80 °C, slowly added with appropriate amount of deionized water under vigorous stirring to disperse, and a lignin-based waterborne epoxy resin emulsion (WLEP4) with 35 wt.% solid content was obtained, with Z-average particle size of 465 nm, room temperature storage stability of more than 3 months, and WLEP4 as shown in Figure 2 .

[0057] 4) 15 g WLEP4, 10 g emulsified asphalt and 4.2 g hexanediamine were mixed and uniformly stirred, coated on the surface of a cement base material, cured to surface dry at room temperature, cured at 180 °C for 2 h, and after cooling to room temperature, left to stand for one week, and the pull-off strength was measured to be 3.51 kN, increased by 36% compared with emulsified asphalt.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a lignin-based waterborne epoxy resin emulsion, characterized in that: Lignin-modified bisphenol A is used as a raw material to react with epichlorohydrin in the presence of a phase transfer catalyst for a ring-opening reaction, followed by a ring-closing reaction in the presence of an alkali to prepare a lignin-based epoxy resin; the lignin-based epoxy resin is then mixed with an emulsifier for reaction, and deionized water is added dropwise for phase inversion treatment to obtain a lignin-based waterborne epoxy resin emulsion.

2. The method for preparing the lignin-based waterborne epoxy resin emulsion according to claim 1, wherein: The steps of modifying bisphenol A with lignin are as follows: lignin and bisphenol A are melt-mixed in a mass ratio of 1:9 to 4:1, concentrated sulfuric acid accounting for 2 to 20% of the total mass of the reactants is added as a catalyst, and the mixture is reacted at 110 to 170° C. for 1 to 6 hours. After the reaction, the product is washed with deionized water until it is neutral, residual acid catalyst is removed, and the mixture is dried to obtain the lignin-modified bisphenol A. The lignin is selected from any one of alkali lignin, enzymatic lignin, sulfate lignin, lignin sulfonate, and chemical pulp lignin.

3. The method for preparing the lignin-based waterborne epoxy resin emulsion according to claim 1, wherein: The phase transfer catalyst is selected from any one of tetrabutylammonium chloride, tetrabutylammonium bromide, benzyltrimethylammonium chloride, benzyltriethylammonium chloride, and tetrabutylammonium hydrogen sulfate, or a mixture of two or more thereof, and its usage is 1-5% of the mass of the lignin-modified bisphenol A.

4. The method for preparing the lignin-based waterborne epoxy resin emulsion according to claim 1, wherein: The alkali is selected from any one of sodium hydroxide, potassium hydroxide, and calcium hydroxide, or a mixture of two or more thereof, and the molar ratio of the alkali to the phenolic hydroxyl group in the lignin-modified bisphenol A is 0.5-2.5:

1.

5. The method for preparing the lignin-based waterborne epoxy resin emulsion according to claim 1, wherein: The ring-opening reaction temperature is 70-120° C., the ring-opening reaction time is 2-10 hours, the ring-closing reaction temperature is 40-80° C., and the ring-closing reaction time is 1-5 hours.

6. The method for preparing the lignin-based waterborne epoxy resin emulsion according to claim 1, wherein: The steps of reacting the lignin-based epoxy resin with the emulsifier are as follows: melt-mixing the lignin-based epoxy resin and the emulsifier in a mass ratio of 9:1 to 1:1, reacting at 100 to 140° C. for 1 to 5 hours, cooling to 60 to 90° C., slowly adding deionized water dropwise under stirring, and performing emulsification and dispersion treatment to obtain a lignin-based water-based epoxy resin emulsion with a solid content of 30 to 55%.

7. The method for preparing a lignin-based waterborne epoxy resin emulsion according to any one of claims 1 to 6, wherein the lignin-based waterborne epoxy resin emulsion is prepared.

8. Use of the lignin-based waterborne epoxy resin emulsion according to claim 7 in emulsified asphalt modification.

9. The use of the lignin-based waterborne epoxy resin emulsion in emulsified asphalt modification according to claim 8, characterized in that: The lignin-based waterborne epoxy resin emulsion and the emulsified asphalt are mixed in a mass ratio of 1 to 1.5:1, a curing agent is added, and the mixture is evenly mixed. The mixture is allowed to stand at room temperature to dry on the surface, and then cured at 80 to 180° C. for 1 to 6 hours to obtain a lignin-based waterborne epoxy resin modified asphalt material.

10. The use of the lignin-based waterborne epoxy resin emulsion in emulsified asphalt modification according to claim 9, characterized in that: The curing agent is selected from one or more of polyamide, polyetheramine, alicyclic amine and fatty amine, and the molar ratio of active hydrogen content to epoxy group of the amine curing agent is 0.8:1 to 2:1.

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