Biomass epoxy monomer, biomass self-repairing epoxy resin and preparation method

Abstract

The present invention discloses a biomass epoxy monomer, a biomass self-healing epoxy resin and a preparation method thereof. Biomass resveratrol and epichlorohydrin are used as raw materials, and epoxy resin monomers are prepared by heating reaction; the biomass epoxy monomers are cured by citric acid to obtain a fully bio-based epoxy resin. Compared with the prior art, the epoxy resin of the present invention can be efficiently self-healed without a catalyst, and has excellent thermal properties, high bending modulus and strength, and high tensile strength.

Description

Technical Field

[0001] The invention relates to a biomass epoxy monomer, a biomass self-repairing epoxy resin and a preparation method thereof, and belongs to the technical field of functional polymer materials. Background Art

[0002] Epoxy resin is a thermosetting resin with the largest demand and excellent comprehensive performance. It has good heat resistance, chemical resistance, mechanical properties, adhesion, dimensional stability and electrical insulation. It is widely used in electronics, aerospace, new energy, civil engineering and other fields as coatings, adhesives, and high-performance composite resin matrices. However, more than 90% of the commercial epoxy resins are bisphenol A epoxy resins, which are made from non-renewable petroleum resources. BPA is considered an endocrine disruptor and toxic substance, so it is banned from food packaging in many countries. During use, epoxy resins will inevitably be subjected to physical effects such as collisions and scratches, which will cause microcracks inside and spread to the surface to produce cracks, thereby shortening its service life and reducing its mechanical properties. In recent years, researchers have proposed epoxy resin glass polymer materials based on reversible covalent bonds such as dynamic ester exchange, disulfide bond exchange, siloxane exchange, hindered urea bond, and dynamic imine bond, which provide possibilities for reprocessing and self-repair of epoxy resins. Usually, these epoxy resin glass polymers require the addition of catalysts such as zinc acetylacetonate and 1,5,7-triazidebicyclo(4.4.0)dec-5-ene (TBD). These catalysts are toxic, expensive, and have poor thermal stability and are prone to failure.

[0003] Combining the research on high-performance bio-based epoxy resins at home and abroad, it is found that plant oil-based epoxy resins have long flexible molecular chains and low epoxy group reactivity, which ultimately leads to low crosslinking density and low heat resistance of the cured product. The network structure of lignin-derived epoxy resins has rigid groups such as benzene rings, which can effectively improve the thermal properties of lignin-based epoxy resins, but their self-healing properties are poor. Therefore, the current bio-based self-healing epoxy resins cannot have high heat resistance, high mechanical properties and good self-healing properties.

[0004] In summary, the development of a biomass-based catalyst-free self-healing epoxy resin with high heat resistance and high mechanical strength still has certain challenges. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a biomass self-healing epoxy resin with high heat resistance and high mechanical strength and a preparation method thereof. In addition to having excellent heat resistance and mechanical properties, the epoxy resin disclosed in the present invention can achieve a self-healing efficiency of more than 80% without the need for a catalyst or additive, which is unpredictable in the prior art and effectively solves the problem that the existing self-healing epoxy resins all require a catalyst.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A biomass epoxy monomer, the preparation method of which comprises the following steps: heating resveratrol and epichlorohydrin to react to obtain the biomass epoxy monomer.

[0008] In the present invention, the molar ratio of resveratrol to epichlorohydrin is 1:(10-20), preferably 1:20.

[0009] In the present invention, the heating reaction is carried out in the presence of an inorganic base and in an alcohol solvent, preferably, the alcohol solvent is ethanol; preferably, the usage ratio of the inorganic base to the alcohol solvent is 1g:10-16mL, preferably 1g:12-14mL. The molar ratio of resveratrol to the inorganic base is 1:(3-3.3); preferably, the inorganic base is sodium hydroxide; the usage amount of the inorganic base is 1.1 times the molar amount of the phenolic hydroxyl group in resveratrol.

[0010] In the present invention, resveratrol and epichlorohydrin are mixed, and then an inorganic alkali alcohol solution is added dropwise, and then heated for reaction to prepare a biomass epoxy monomer; the sodium hydroxide alcohol solution is added dropwise for 0.5 to 2 hours, preferably 1 to 1.5 hours.

[0011] In the present invention, the temperature of the heating reaction is 80-100° C., and the time is 3-6 hours. Preferably, the temperature of the heating reaction is 80-90° C., and the time is 4-5 hours.

[0012] A biomass self-healing epoxy resin, the preparation method of which comprises the following steps: the biomass epoxy monomer is reacted with a biomass curing agent to obtain the biomass self-healing epoxy resin.

[0013] In the present invention, the biomass curing agent is a biomass acid, such as citric acid; preferably, the citric acid is pre-dissolved in a solvent and then mixed with the above-mentioned biomass epoxy monomer; preferably, the solvent is tetrahydrofuran.

[0014] In the present invention, the biomass epoxy monomer and citric acid are prepolymerized at 80-100°C, and the prepolymer is cured after degassing; the curing temperature is 110-150°C, and the time is 5-16 hours. Preferably, the curing is a step-by-step heating method, and the insulation time at each step temperature is not less than 1 hour, and the temperature difference between adjacent steps does not exceed 30°C.

[0015] In the present invention, the molar ratio of the biomass epoxy monomer to the biomass curing agent is 1:(0.5-1.5), preferably 1:(0.5-1).

[0016] The present invention discloses the use of biomass epoxy monomer or biomass self-healing epoxy resin in the preparation of epoxy resin material. Compared with the prior art, the epoxy resin of the present invention can self-heal efficiently without catalyst or additive, and has excellent thermal properties, high bending modulus and strength, and high tensile strength.

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

[0018] 1. The present invention uses biomass resveratrol and epichlorohydrin as raw materials to synthesize epoxy monomer.

[0019] 2. The biomass self-healing epoxy resin prepared by the present invention has outstanding heat resistance, and the glass transition temperature (T g ) is 129°C, it also has high flexural modulus (2.40GPa) and strength (123.5MPa), it also has high tensile strength (74.6MPa), and a self-healing efficiency of 82.1%, providing a reliable basis for its application in cutting-edge fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] FIG1 is a synthesis of biomass epoxy monomers, a curing reaction formula and a chemical structure formula of biomass self-healing epoxy resins according to the present invention;

[0021] Figure 2 is the nuclear magnetic resonance hydrogen spectrum of the biomass epoxy monomer of the present invention ( 1 H NMR);

[0022] Figure 3 is the nuclear magnetic resonance hydrogen spectrum of the biomass epoxy monomer of the present invention ( 13 C-NMR);

[0023] Figure 4 The high-resolution mass spectrum of the biomass epoxy monomer of the present invention (key peak: 397.1653 [M+H + ],419.1472[M+Na + ]);

[0024] Figure 5 is the thermogravimetric (TGA) curve of the biomass self-healing epoxy resin of the present invention, 10°C / min, nitrogen;

[0025] Figure 6 It is the dynamic thermomechanical analysis (DMA) curve of the biomass self-healing epoxy resin of the present invention, 3°C / min;

[0026] Figure 7 is the bending stress-strain curve of the biomass self-healing epoxy resin of the present invention;

[0027] Figure 8 is the tensile stress-strain curve of the biomass self-healing epoxy resin before and after self-healing of the present invention;

[0028] Fig. 9 It is an electronic image of the scratch repair of the biomass self-healing epoxy resin of the present invention. DETAILED DESCRIPTION

[0029] The biomass self-repairing epoxy resin preparation process disclosed in the present invention can be found in Figure 1 , as follows:

[0030] (1) Resveratrol and epichlorohydrin are reacted by heating to obtain a biomass epoxy monomer;

[0031] (2) The biomass epoxy monomer is cured with citric acid to obtain a biomass self-healing epoxy resin; curing does not require the addition of any catalyst, accelerator, etc.

[0032] Specifically, the preparation of the biomass self-repairing epoxy resin of the present invention is as follows:

[0033] (1) Resveratrol and epichlorohydrin are mixed by mole, and then sodium hydroxide alcohol solution is added dropwise to the mixture, reacted at 80-100° C. for 3-6 hours, cooled naturally to room temperature, filtered, and then the filtrate is mixed with dichloromethane, washed with deionized water for times, rotary evaporated to remove the solvent, and vacuum dried to obtain a biomass epoxy monomer;

[0034] (2) Dissolve citric acid in tetrahydrofuran by weight, prepolymerize the biomass epoxy monomer and the citric acid, and then solidify the prepolymer after degassing to obtain a biomass self-healing epoxy resin; no other raw materials or reagents need to be added in this step.

[0035] The present invention prepares a biomass epoxy monomer by heating resveratrol and epichlorohydrin; then the biomass epoxy monomer is cured by citric acid to obtain a biomass self-healing epoxy resin; curing does not require the addition of any catalyst or accelerator. The technical solution of the present invention is further described below in conjunction with the accompanying drawings and examples; all raw materials are commercially available, and the specific preparation operations and testing methods involved are conventional methods in the art, and a universal testing machine is used to test the mechanical properties.

[0036] Example 1

[0037] (1) Preparation of biomass epoxy monomer

[0038] Under nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 90 ° C. The addition was completed in 1 h, and then refluxed at 90 ° C for 5 h, and then naturally cooled to room temperature, filtered, and the filtrate was extracted with dichloromethane. The organic phase was washed with deionized water for 3 times, concentrated under reduced pressure (80 ° C, -0.1 MPa), and dried in a vacuum oven at 90 ° C for 12 h to obtain an orange-yellow oily substance, which is a biomass epoxy monomer with a yield of 92%; Figure 2 Its H NMR spectrum ( 1 H NMR); Figure 3 Its H NMR spectrum ( 13 C-NMR); Figure 4 This is its high-resolution mass spectrum.

[0039] (2) Preparation of biomass self-healing epoxy resin

[0040] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer (the molar ratio of biomass epoxy monomer to citric acid was 1:0.8), and prepolymerized at 90 ° C for 2 hours. The prepolymer was then degassed in a vacuum oven (80 ° C, 40 min, -0.1 MPa), and then cured according to the process of 110 ° C / 2 h + 130 ° C / 4 h + 150 ° C / 2 h. After the curing, it was naturally cooled to room temperature to obtain a biomass self-healing epoxy resin. Its thermal weight loss curve, dynamic thermal mechanical analysis (DMA) curve, bending stress-strain curve, tensile stress-strain curve, and electronic image of scratch repair are shown in Figure 2, respectively. Figure 5 , Figure 6 , Figure 7 , Figure 8 , Fig. 9 .

[0041] A scratch (depth 66.45 μm) was made on the prepared specimen using a scalpel, and then heat-treated at 180°C for 10 minutes in an oven without external pressure, and the repair of the scratch was photographed using an ultra-depth-of-field microscope. Self-repair efficiency = (initial scratch width - repaired scratch width) / initial scratch width * 100%.

[0042] It can be seen that the glass transition temperature (T g ) is 129°C, T d5%285°C. Furthermore, the flexural modulus, flexural strength and tensile strength of the biomass self-healing epoxy resin at room temperature are 2.40GPa, 123.5MPa and 74.3MPa respectively, which has outstanding mechanical properties. At the same time, it has good self-healing properties, with a scratch self-healing efficiency of 82.1% and a tensile strength of 81.9% of the original sample.

[0043] Referring to the above method, the present invention also prepared two groups of bio-based self-healing epoxy resins with a molar ratio of biomass epoxy monomer to citric acid of 1:1 and 1:0.6, wherein the epoxy resin prepared with a molar ratio of 1:1 had a glass transition temperature of 104°C, a tensile strength of 58.8 MPa, and a scratch self-healing efficiency of 88.0%; the epoxy resin prepared with a molar ratio of 1:0.6 had a glass transition temperature of 146°C, a tensile strength of 52.8 MPa, and a scratch self-healing efficiency of 74.2%.

[0044] Existing literature reports that a fully bio-based self-healing epoxy resin was prepared using biomass kraft lignin and sebacic acid as raw materials and zinc acetylacetonate as a catalyst. The tensile strength of Se-EP / Oz-L was 9.8 MPa, the initial thermal decomposition temperature was 222°C, and the self-healing efficiency was 77.4%.

[0045] Existing literature reports that bio-based self-healing epoxy resin was prepared using biomass rosin, fumaric acid and petroleum-based 2,2-(1,4-phenyl)-bis(4-mercapto-1,3,2-dioxaborane) (BDB) as raw materials. The tensile strength of 20% C-FPAE is 39.5MPa.

[0046] Existing literature reports that biomass menthane diamine was used as raw material to prepare bio-based epoxy resin through a one-step reaction, and adipic acid was used as a curing agent to prepare a fully bio-based self-healing epoxy resin, EMDA-AA 1.0 The glass transition temperature is 72°C (T g , DMA), the tensile strength is 57.4MPa.

[0047] Existing literature reports that biomass menthane diamine and tung oil triglycidyl ester were used as raw materials to prepare a fully bio-based self-healing epoxy resin, TOTGE-MDA. 1.0 The glass transition temperature is 83°C (T g , DMA), the tensile strength is 57.6MPa.

[0048] The prior art discloses a self-healing epoxy resin prepared from N,N'-bis(tert-butyl)ethylenediamine, bisphenol A glycidyl ether epoxy resin and hexamethylene diisocyanate, with a tensile strength of 22 MPa and a mechanical damage repair efficiency of about 73%.

[0049] The above description shows that, compared with the prior art, the biomass self-healing epoxy resin prepared in the present invention has excellent heat resistance, outstanding mechanical properties and good self-healing properties.

[0050] Example 2

[0051] (1) Preparation of biomass resveratrol epoxy monomer

[0052] Under a nitrogen atmosphere, 10 g of resveratrol and 60.802 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 90°C. The addition was completed within 1 h, and then refluxed at 90°C for 5 h. The mixture was naturally cooled to room temperature, filtered, and the filtrate was extracted with dichloromethane. The organic phase was washed three times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0053] (2) Preparation of biomass self-healing epoxy resin

[0054] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0055] Example 3

[0056] (1) Preparation of biomass resveratrol epoxy monomer

[0057] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 100°C. The addition was completed in 1 h, and then refluxed at 100°C for 3 h, and then naturally cooled to room temperature, filtered, and the filtrate was extracted with dichloromethane. The organic phase was washed 3 times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0058] (2) Preparation of biomass self-healing epoxy resin

[0059] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0060] Example 4

[0061] (1) Preparation of biomass resveratrol epoxy monomer

[0062] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 80°C. The addition was completed in 1 h, and then refluxed at 80°C for 5 h. The mixture was naturally cooled to room temperature and filtered. The filtrate was extracted with dichloromethane, the organic phase was washed 3 times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0063] (2) Preparation of biomass self-healing epoxy resin

[0064] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0065] Example 5

[0066] (1) Preparation of biomass resveratrol epoxy monomer

[0067] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.257 g of sodium hydroxide (1.0 equivalent per mole of phenolic hydroxyl group) was added dropwise at 90°C. The addition was completed in 1 h, and then refluxed at 90°C for 5 h. The mixture was naturally cooled to room temperature and filtered. The filtrate was extracted with dichloromethane, the organic phase was washed 3 times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0068] (2) Preparation of biomass self-healing epoxy resin

[0069] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0070] Example 6

[0071] (1) Preparation of biomass resveratrol epoxy monomer

[0072] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 70 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 90°C. The addition was completed in 1 h, and then refluxed at 90°C for 5 h. The mixture was naturally cooled to room temperature and filtered. The filtrate was extracted with dichloromethane, the organic phase was washed 3 times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0073] (2) Preparation of biomass self-healing epoxy resin

[0074] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0075] Example 7

[0076] (1) Preparation of biomass resveratrol epoxy monomer

[0077] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 90°C. The addition was completed over 1.5 h, and then refluxed at 90°C for 5 h. The mixture was naturally cooled to room temperature and filtered. The filtrate was extracted with dichloromethane, the organic phase was washed three times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0078] (2) Preparation of biomass self-healing epoxy resin

[0079] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0080] Example 8

[0081] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 90°C. The addition was completed over 1.5 h, and then refluxed at 90°C for 4 h. The mixture was naturally cooled to room temperature and filtered. The filtrate was extracted with dichloromethane, the organic phase was washed three times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0082] (2) Preparation of biomass self-healing epoxy resin

[0083] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0084] Example 9

[0085] (1) Preparation of biomass resveratrol epoxy monomer

[0086] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.783 g of sodium hydroxide (1.1 equivalents per mole of phenolic hydroxyl group) was added dropwise at 90°C. The addition was completed in 1 h, and then refluxed at 90°C for 4 h. The mixture was naturally cooled to room temperature and filtered. The filtrate was extracted with dichloromethane, the organic phase was washed 3 times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0087] (2) Preparation of biomass self-healing epoxy resin

[0088] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0089] Example 10

[0090] (1) Preparation of biomass resveratrol epoxy monomer

[0091] Under a nitrogen atmosphere, 10 g of resveratrol and 81.069 g of epichlorohydrin were added to a three-necked flask equipped with a reflux condenser and a dropping funnel, and then 80 mL of ethanol containing 5.257 g of sodium hydroxide (1.0 equivalent per mole of phenolic hydroxyl group) was added dropwise at 100°C. The addition was completed in 1 h, and then refluxed at 100°C for 4 h, and then naturally cooled to room temperature, filtered, and the filtrate was extracted with dichloromethane. The organic phase was washed 3 times with deionized water, concentrated under reduced pressure (80°C, -0.1 MPa), and dried in a vacuum oven at 90°C for 12 h to obtain an orange-yellow oil.

[0092] (2) Preparation of biomass self-healing epoxy resin

[0093] 3.877 g of citric acid was dissolved in 8 mL of tetrahydrofuran, and then poured into a beaker containing 10 g of biomass epoxy monomer. Prepolymerization was carried out at 90 °C, and the prepolymer was degassed in a vacuum oven (80 °C, 40 min, -0.1 MPa), and then cured according to the process of 110 °C / 2 h + 130 °C / 4 h + 150 °C / 2 h. After curing, it was naturally cooled with the hot press to obtain the biomass self-healing epoxy resin.

[0094] The present invention uses resveratrol and epichlorohydrin as raw materials to synthesize bio-based epoxy resin, and uses biomass citric acid as a curing agent. The prepared biomass-based self-healing epoxy resin has outstanding heat resistance, T g At a temperature above 100°C, a tensile strength above 50 MPa, and without a catalyst, the self-healing efficiency is above 74%. Preferably, the glass transition temperature (T g , DMA) is 129℃, and it also has high flexural modulus (2.40GPa) and strength (123.5MPa), high tensile strength (74.3MPa) and good self-repair efficiency, of which the scratch self-repair efficiency is 82.1% and the tensile strength repair efficiency is 81.9%. Compared with the prior art, the present invention prepares biomass epoxy resin with all biomass raw materials, and the resin can achieve self-repair without a catalyst. At the same time, it has very excellent comprehensive performance, thus providing a reliable foundation for its application in cutting-edge fields.

Claims

1. A method for preparing a biomass self-repairing epoxy resin, characterized in that: The method comprises the following steps: preparing a biomass epoxy monomer by heating resveratrol and epichlorohydrin; reacting the biomass epoxy monomer with a biomass curing agent at 110-150° C. for 6-12 hours to obtain a biomass self-healing epoxy resin; the biomass acid is citric acid; and the molar ratio of the biomass epoxy monomer to the biomass curing agent is 1:(0.5-1.5).

2. The method for preparing the biomass self-repairing epoxy resin according to claim 1, characterized in that: The molar ratio of resveratrol to epichlorohydrin is 1:(10-20).

3. The method for preparing the biomass self-repairing epoxy resin according to claim 1, characterized in that: The heating reaction is carried out in the presence of an inorganic base and in an alcohol solvent; the heating reaction temperature is 80-100° C. and the time is 3-6 hours.

4. The biomass self-healing epoxy resin prepared according to the preparation method of the biomass self-healing epoxy resin according to claim 1.

5. Use of the biomass self-healing epoxy resin according to claim 4 in the preparation of epoxy resin materials.

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