Three-functionality bio-based epoxy resin monomer, bio-based epoxy resin, preparation method and remolding method

Abstract

The invention relates to the technical field of bio-based epoxy resin, and provides a three-functionality bio-based epoxy resin monomer, bio-based epoxy resin, a preparation method and a remodeling method. The bio-based epoxy resin monomer provided by the invention has a rigid benzene ring structure, is beneficial to improving the thermal stability and mechanical properties of the epoxy resin, and also contains a dynamic covalent bond Schiff base bond, so that the epoxy resin has a good surface damage repair function and a good remodeling function; in addition, the bio-based epoxy resin monomer provided by the invention has three degrees of functionality, so that the crosslinking density of epoxy resin can be improved. The bio-based epoxy resin monomer provided by the invention is prepared on the basis of protocatechuic aldehyde, compared with commercial epoxy resin, the bio-based epoxy resin monomer has the advantages of greenness, no toxicity and simple synthesis method, and consumption and dependence on petrochemical products can be reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of bio-based epoxy resins, and in particular to a trifunctional bio-based epoxy resin monomer, a bio-based epoxy resin, and preparation methods and reshaping methods thereof. Background Art

[0002] Epoxy resin is a general term for a class of high molecular polymers containing more than two epoxy groups in the molecule. Compared with most thermosetting materials, epoxy resin has excellent dimensional stability, high modulus, high strength, good heat resistance, chemical resistance, etc., and is widely used in coatings, adhesives, composite materials, electronic packaging and other fields.

[0003] At present, common epoxy resins are mainly petroleum-based products such as bisphenol A diglycidyl ether (BPA). However, petrochemical raw materials are non-renewable and limited in storage, which is not conducive to the long-term development and application of epoxy resins.

[0004] Due to their significant advantages such as environmental friendliness and degradability, bio-based materials have been widely used in the research of epoxy resins in recent years. However, the current bio-based epoxy resins have problems of poor thermal stability and mechanical properties, which affect their further wide application. Summary of the Invention

[0005] In view of this, the present invention provides a trifunctional bio-based epoxy resin monomer, a bio-based epoxy resin, and preparation methods and reshaping methods thereof. The bio-based epoxy resin provided by the present invention has good thermal stability and mechanical properties, has self-healing properties, is green and non-toxic at the same time, and reduces the consumption of petroleum resources.

[0006] In order to achieve the above-mentioned invention purpose, the present invention provides the following technical solutions:

[0007] A trifunctional bio-based epoxy resin monomer, the structural formula of which is shown in Formula I:

[0008]

[0009] The present invention also provides a preparation method of the trifunctional bio-based epoxy resin monomer described in the above solution, including the following steps:

[0010] Mix vanillin amine hydrochloride, a salt of a strong base and a weak acid, an alcohol solvent and protocatechuic aldehyde for a condensation reaction to obtain a bisphenol monomer; the structure of the bisphenol monomer is shown in Formula II;

[0011]

[0012] Mix the bisphenol monomer, catalyst, and epichlorohydrin for epoxidation reaction, and mix the obtained epoxidation reaction solution with sodium hydroxide and benzene solvent for ring-closing reaction to obtain a trifunctional bio-based epoxy resin monomer with the structure shown in Formula I.

[0013] Preferably, the strong base weak acid salt includes one or more of potassium carbonate and sodium carbonate; the molar ratio of vanillin amine hydrochloride to the strong base weak acid salt is 1:1 to 1.5; the molar ratio of vanillin amine hydrochloride to protocatechuic aldehyde is 1:1 to 1.5;

[0014] The temperature of the condensation reaction is 60 to 100 °C, and the time is 2 to 7 h.

[0015] Preferably, the molar ratio of the bisphenol monomer to the catalyst is 1:0.001 to 0.1; the molar ratio of the bisphenol monomer to epichlorohydrin is 1:1 to 30; the molar ratio of the bisphenol monomer to sodium hydroxide is 1:0.1 to 0.7.

[0016] Preferably, the catalyst is one or more of quaternary ammonium salts and pyridine; the sodium hydroxide is used in the form of an aqueous sodium hydroxide solution, and the mass concentration of the aqueous sodium hydroxide solution is 20% to 45%.

[0017] Preferably, the temperature of the epoxidation reaction is 50 to 100 °C, and the time is 2 to 7 h; the temperature of the ring-closing reaction is 50 to 100 °C, and the time is 2 to 7 h.

[0018] The present invention also provides a bio-based epoxy resin, and the preparation raw materials include an epoxy resin monomer, a curing agent, and a curing catalyst. The epoxy resin monomer is the trifunctional bio-based epoxy resin monomer described in the above scheme or the trifunctional bio-based epoxy resin monomer prepared by the preparation method described in the above scheme; the curing agent includes one or more of an amino-containing curing agent, a disulfide bond-containing curing agent, and an amino-siloxane bond-containing curing agent; the curing catalyst includes one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), imidazole, 2-ethyl-4-methylimidazole, and 4-dimethylaminopyridine.

[0019] Preferably, the amino-containing curing agent is 4,4'-diaminodiphenylmethane and / or hexamethylenediamine; the disulfide bond-containing curing agent is one or two of 4,4'-diaminodiphenyl disulfide and 3,3'-dithiobispropionic acid; the amino-siloxane bond-containing curing agent is one or two of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and bis(4-aminophenoxy)dimethylsilane.

[0020] The present invention also provides a preparation method of the bio-based epoxy resin described in the above scheme, including the following steps:

[0021] Mix a trifunctional bio - based epoxy resin monomer, a curing agent, and a curing catalyst for curing to obtain the cured epoxy resin; the curing includes first curing and second curing successively. The temperature of the first curing is 60 - 120°C, and the time is 4 - 12 h. The temperature of the second curing is 120 - 160°C, and the time is 2 - 12 h.

[0022] The present invention also provides a reshaping method for a bio - based epoxy resin, comprising the following steps:

[0023] Crush the bio - based epoxy resin and then conduct hot - press reshaping; the temperature of the hot - press reshaping is 160 - 200°C, the pressure is 1 - 20 MPa, and the time is 0.1 - 2 h; the bio - based epoxy resin is the bio - based epoxy resin described in the above - mentioned solution or the bio - based epoxy resin prepared by the preparation method described in the above - mentioned solution.

[0024] The present invention provides a trifunctional bio - based epoxy resin monomer, and its structural formula is shown in Formula I. The rigid benzene ring structure in the bio - based epoxy resin monomer provided by the present invention helps to improve the thermal stability and mechanical properties of the epoxy resin. At the same time, the monomer structure contains a dynamic covalent bond, Schiff base bond, enabling the epoxy resin to have a good surface damage repair function; moreover, the bio - based epoxy resin provided by the present invention has trifunctionality, which can increase the cross - linking degree of the epoxy resin, form a more complex and dense cross - linked network structure, and thus improve the mechanical properties of the epoxy resin. The bio - based epoxy resin provided by the present invention is prepared based on protocatechuic aldehyde, which is derived from the roots, stems, and leaves of plants, has a wide source, is green and non - toxic, is a renewable bio - based material, can reduce the consumption and dependence on petrochemical products, and promote the sustainable development of the epoxy resin industry.

[0025] The present invention also provides a preparation method for the trifunctional bio - based epoxy resin monomer described in the above - mentioned solution. The preparation method provided by the present invention has simple steps and high yield. Description of the Drawings

[0026] Figure 1 1H - NMR spectrum of the bisphenol monomer synthesized in Example 1;

[0027] Figure 2 IR spectrum of the bisphenol monomer synthesized in Example 1;

[0028] Figure 3 MS spectrum of the bisphenol monomer synthesized in Example 1;

[0029] Figure 4 1H - NMR spectrum of the trifunctional bio - based epoxy resin monomer synthesized in Example 2;

[0030] Figure 5It is the infrared spectrum diagram of the bio-based epoxy resin obtained after curing in Example 3;

[0031] Figure 6 It is the hot pressing and reshaping diagram of the bio-based epoxy resin;

[0032] Figure 7 It is the stress-strain curve of the bio-based epoxy resin;

[0033] Figure 8 It is the self-healing diagram of the bio-based epoxy resin, and the scale is 75 μm for all. Detailed implementation manners

[0034] The present invention provides a trifunctional bio-based epoxy resin monomer, and its structural formula is shown in Formula I:

[0035]

[0036] The present invention also provides a preparation method of the trifunctional bio-based epoxy resin monomer described in the above solution, including the following steps:

[0037] Mix vanillin amine hydrochloride, a salt of a weak base and a strong acid, an alcohol solvent and protocatechuic aldehyde for a condensation reaction to obtain a bisphenol monomer; the structure of the bisphenol monomer is shown in Formula II;

[0038]

[0039] Mix the bisphenol monomer, a catalyst and epichlorohydrin for an epoxidation reaction, and mix the obtained epoxidation reaction solution with sodium hydroxide and a benzene solvent for a ring-closure reaction to obtain a trifunctional bio-based epoxy resin monomer with the structure shown in Formula I.

[0040] In the present invention, vanillin amine hydrochloride, a salt of a weak base and a strong acid, an alcohol solvent and protocatechuic aldehyde are mixed for a condensation reaction to obtain a bisphenol monomer (PCA-AM). In the present invention, the reaction formula of the condensation reaction is as follows:

[0041]

[0042] In the present invention, the salt of a weak base and a strong acid includes one or more of potassium carbonate and sodium carbonate; the molar ratio of vanillin amine hydrochloride to the salt of a weak base and a strong acid is preferably 1:1 to 1.5, specifically it can be 1:1.05; the molar ratio of vanillin amine hydrochloride to protocatechuic aldehyde is preferably 1:1 to 1.5, specifically it can be 1:1.05; the alcohol solvent is preferably methanol. Protocatechuic aldehyde is derived from the roots, stems and leaves of plants, has a wide source, and has a rigid aromatic ring structure and an aldehyde group in terms of chemical structure. By carrying out a condensation reaction with an amino group to synthesize a bisphenol monomer containing dynamic covalent bonds, the finally obtained epoxy resin has better performance in terms of self-healing or reshaping.

[0043] In the present invention, the temperature of the condensation reaction is preferably 60 to 100 °C, specifically it can be 60 °C, 70 °C, 80 °C, 90 °C or 100 °C. In the specific embodiments of the present invention, the condensation reaction is preferably carried out under reflux conditions. The time of the condensation reaction is preferably 2 to 7 h, specifically it can be 3 h, 4 h, 5 h or 6 h. By carrying out the condensation reaction under the above conditions, the present invention can promote the efficient progress of the condensation reaction.

[0044] In the specific embodiments of the present invention, it is preferred to dissolve vanillin amine hydrochloride and protocatechuic aldehyde in an alcohol solvent respectively to obtain a vanillin amine hydrochloride solution and a protocatechuic aldehyde solution. Potassium carbonate is added to the vanillin amine hydrochloride solution, and after stirring at 50 °C for 30 min, the protocatechuic aldehyde solution is added dropwise to the system. After the addition is completed, the condensation reaction is carried out under reflux conditions; the concentration of vanillin amine hydrochloride in the vanillin amine hydrochloride solution is preferably 2 mol / L, and the concentration of protocatechuic aldehyde in the protocatechuic aldehyde solution is preferably 3 mol / L.

[0045] After the condensation reaction is completed, the present invention preferably filters the obtained reaction solution, washes the obtained solid product with methanol and then dries it to obtain the bisphenol monomer.

[0046] After obtaining the bisphenol monomer, the present invention mixes the bisphenol monomer, a catalyst and epichlorohydrin to carry out an epoxidation reaction, and mixes the obtained epoxidation reaction solution with sodium hydroxide and a benzene solvent to carry out a ring closure reaction to obtain a trifunctional bio-based epoxy resin monomer having the structure shown in Formula I.

[0047] In the present invention, the reaction processes of the epoxidation reaction and the ring closure reaction are comprehensively represented as follows:

[0048]

[0049] In the present invention, the molar ratio of the bisphenol monomer to the catalyst is preferably 1:0.001 to 0.1, specifically it can be 1:0.02, 1:0.03, 1:0.04, 1:0.06 or 1:0.08; the catalyst is preferably one or more of quaternary ammonium salts and pyridine; the quaternary ammonium salt preferably includes one or more of tetrabutylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium iodide and cetyltrimethylammonium bromide. By using the above catalyst, the present invention can promote the reaction, accelerate the reaction rate and improve the selectivity.

[0050] In the present invention, the molar ratio of the bisphenol monomer to epichlorohydrin is preferably 1:10 to 30, and specifically can be 1:10, 1:15, 1:20, 1:25 or 1:30; the molar ratio of the bisphenol monomer to sodium hydroxide is preferably 1:0.1 to 0.7, and specifically can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6 or 1:0.7; the sodium hydroxide is used in the form of an aqueous sodium hydroxide solution, and the mass concentration of the aqueous sodium hydroxide solution is preferably 20% to 45%, and specifically can be 40%; the addition method of the sodium hydroxide solution is preferably dropwise addition. The benzene solvent is preferably toluene, and the molar ratio of the bisphenol monomer to toluene is preferably 1:10 to 20.

[0051] In the present invention, the temperature of the epoxidation reaction is preferably 50 to 100 °C, specifically can be 80 °C, the time is preferably 2 to 7 h, specifically can be 6 h; after the epoxidation reaction is completed, it is preferred to subject the obtained reaction solution to vacuum distillation to remove the excessive epichlorohydrin in the system, and then add a benzene solvent and an aqueous sodium hydroxide solution for the ring-closing reaction.

[0052] In the present invention, the temperature of the ring-closing reaction is preferably 50 to 100 °C, specifically can be 90 °C, and the time of the ring-closing reaction is preferably 2 to 7 h, specifically can be 3 h, 4 h, 5 h or 6 h.

[0053] After the ring-closing reaction is completed, in the present invention, it is preferred to cool the obtained reaction solution to room temperature, then wash it with deionized water until neutral, and subject the washed material solution to vacuum distillation, drying and column chromatography purification to obtain the trifunctional bio-based epoxy resin monomer; the eluent used for the column chromatography purification is preferably petroleum ether.

[0054] The present invention also provides a bio-based epoxy resin, and the raw materials for preparation include an epoxy resin monomer, a curing agent and a curing catalyst. The epoxy resin monomer is the trifunctional bio-based epoxy resin monomer described in the above scheme or the trifunctional bio-based epoxy resin monomer prepared by the preparation method described in the above scheme; the curing agent includes one or more of an amino-containing curing agent, a disulfide bond-containing curing agent, and an amino-siloxane bond-containing curing agent.

[0055] In the present invention, the amino-containing curing agent is preferably 4,4'-diaminodiphenylmethane and / or hexamethylenediamine; the disulfide bond-containing curing agent is preferably one or two of 4,4'-diaminodiphenyl disulfide and 3,3'-dithiodipropionic acid; the amino-siloxane bond-containing curing agent is preferably one or two of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and bis(4-aminophenoxy)dimethylsilane.

[0056] In the present invention, the molar ratio of the trifunctional bio-based epoxy resin monomer to the curing agent is preferably 1:0.5 to 2, and specifically can be 1:0.75.

[0057] In the present invention, the curing catalyst includes one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), imidazole, 2-ethyl-4-methylimidazole, and 4-dimethylaminopyridine, and more preferably TBD; the molar ratio of the trifunctional bio-based epoxy resin monomer to the curing catalyst is preferably 1:0.01 to 0.1. Taking TBD as an example to illustrate the action principle of the curing agent catalyst in the present invention: in the presence of an alcohol group, the secondary amine hydrogen ion on TBD can combine with the silicon atom or oxygen atom in the siloxane, changing the electron cloud distribution of the silicon-oxygen bond, weakening the bond strength, making it easier to break and recombine, thereby promoting the progress of the dynamic exchange reaction.

[0058] The present invention also provides a preparation method of the bio-based epoxy resin described in the above solution, including the following steps:

[0059] Mix the trifunctional bio-based epoxy resin monomer, the curing agent, and the curing catalyst for curing to obtain the epoxy resin cured product.

[0060] In the present invention, the curing includes first curing and second curing in sequence. The temperature of the first curing is 60 to 120 °C, and the time is 4 to 12 h. The temperature of the second curing is 120 to 160 °C, and the time is 2 to 12 h.

[0061] The present invention preferably first stirs and mixes the trifunctional bio-based epoxy resin monomer, the curing agent, and the curing catalyst evenly, then performs vacuum degassing, and then pours them into a mold for curing.

[0062] In the present invention, taking the curing agent as 1,3-bis(3-aminopropyl)tetramethyldisiloxane (Bas) as an example, the structure of the bio-based epoxy resin obtained after curing is shown in Formula III:

[0063]

[0064] The present invention also provides a reshaping method of the bio-based epoxy resin, including the following steps:

[0065] Crush the bio-based epoxy resin and then perform hot pressing and reshaping; the bio-based epoxy resin is the bio-based epoxy resin described in the above solution or the bio-based epoxy resin prepared by the preparation method described in the above solution.

[0066] In the present invention, the temperature for hot pressing and reshaping is 160 - 200 °C, specifically it can be 200 °C, the pressure is 1 - 20 MPa, specifically it can be 5 MPa, 8 MPa, 10 MPa, 15 MPa or 20 MPa, and the time is 0.1 - 2 h, specifically it can be 0.5 h, 1 h, 1.5 h or 2 h.

[0067] Next, the technical solutions in the present invention will be clearly and completely described in conjunction with the embodiments in the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present invention without making creative efforts belong to the scope of protection of the present invention.

[0068] Example 1

[0069] In a three-necked round-bottom flask equipped with a thermometer and a reflux condenser, set the temperature to 50 °C. Under magnetic stirring, dissolve vanillin amine hydrochloride (37.93 g, 0.2 mol) in 100 mL of methanol, and add solid K 2 CO 3 (27.64 g, 0.21 mmol). Stir at 50 °C for 30 min, dissolve protocatechuic aldehyde (29 g, 0.21 mol) in methanol (70 mL), then add it dropwise to the reaction system, and reflux the entire mixed system for 4 h. After the reaction is completed, filter to obtain a yellow powder, wash it three times with methanol, and dry it overnight to obtain the bisphenol monomer (PCA-AM).

[0070] The nuclear magnetic hydrogen spectrum of the obtained bisphenol monomer is as Figure 1 shown, the infrared spectrum is as Figure 2 shown, and the mass spectrum is as Figure 3 shown; according to Figure 1 it can be seen that the appearance of the signal peak at f represents the successful synthesis of the imine bond; according to Figure 2 it can be seen that: the absorption characteristic peak attributed to the hydroxyl group is at 3200 cm -1 , and the characteristic peak representing the imine bond is at 1645 cm -1 , indicating the successful synthesis of the bisphenol monomer; according to Figure 3 it can be seen that the relative molecular mass of the bisphenol monomer is consistent with the expected molecular weight. The above results show that the bisphenol monomer prepared in this example has the target structure.

[0071] Example 2

[0072] In a three-necked flask equipped with a mechanical stirring device and a condenser, add the bisphenol monomer (20 g) prepared in Example 1, 160 mL of epichlorohydrin (converted, epichlorohydrin is 2 mol), and 2 g of the catalyst tetrabutylammonium bromide (converted, tetrabutylammonium bromide is 0.0062 mol). Mix well, raise the temperature to 80 °C and react for 6 h. Stop heating and remove the excess epichlorohydrin in the system by vacuum distillation. After the epichlorohydrin is completely removed, add 100 mL of toluene (converted, toluene is 0.95 mol) and 4.8 g of an aqueous sodium hydroxide solution (mass concentration is 40%) to the reaction system, and then heat to 90 °C and continue to react for 3 h. After the reaction is completed, cool the system to room temperature, wash the reaction solution with deionized water multiple times until neutral, remove toluene and water from the washed product by vacuum distillation, and then obtain a red-brown viscous liquid after drying and purification by column chromatography, which is the trifunctional bio-based epoxy resin monomer (PCA-AM-EP) with the structure shown in Formula I.

[0073] The 1H NMR spectrum of the obtained trifunctional bio-based epoxy resin monomer is as Figure 4 shown; according to Figure 4 it can be seen that: the hydrogen resonance peak at 7 - 7.6 ppm is the hydrogen resonance peak in the benzene ring structure. The successful synthesis of PCA-AM-EP can be demonstrated by 1H NMR spectrum analysis.

[0074] Example 3

[0075] Preparation of bio-based epoxy resin. The preparation raw materials include Material A, Material B, and Material C. Among them, Material A is the trifunctional bio-based epoxy resin monomer prepared in Example 2, Material B is the curing agent 1,3-bis(3-aminopropyl)tetramethyldisiloxane (Bas), and Material C is the curing catalyst TBD. The molar ratio of Material A to Material B is 1:0.75, and the molar ratio of Material A to Material C is 1:0.05. The specific preparation process of the bio-based epoxy resin is as follows: First, add Material A to a 25 mL beaker, place it at room temperature, stir well, then add the weighed curing agent and TBD, and stir for 10 min to make it evenly mixed; then, in a vacuum oven at room temperature, vacuum degas for 10 min, and then pour the mixture into a mold, cure it at a constant temperature of 60 °C for 12 h, and then cure it at a constant temperature of 120 °C for 4 h to obtain the bio-based epoxy resin (PCA-AM-EP / Bas).

[0076] The infrared spectrum of the obtained bio-based epoxy resin is as Figure 5 shown, according to Figure 5 it can be seen that: the characteristic peak attributed to the hydroxyl group in PCA-AM-EP / Bas at 3200 cm -1 , and the characteristic peak attributed to the epoxy group in PCA-AM-EP at 910 cm -1 disappear, and at 1270 cm -1Characteristic peaks belonging to C-N in PCA-AM-EP / Bas appeared here.

[0077] Example 4

[0078] The bio-based epoxy resin obtained in Example 3 was tested for hot-pressing reshaping performance, tensile performance, and self-healing performance, as follows.

[0079] I. Hot-pressing reshaping experiment

[0080] The PCA-AM-EP / Bas cured spline obtained in Example 3 was crushed in a pulverizer to obtain crushed epoxy resin, and then hot-pressed under a hot press at a hot-pressing temperature of 200 °C, a pressure of 10 MPa, and a time of 60 min. As Figure 6 shown, the powder of the bio-based epoxy resin cured spline was hot-pressed and reshaped at 200 °C, and after 60 min, the powder was reshaped into a sheet again. The above results show that introducing multiple dynamic bonds into the epoxy resin and increasing the content of dynamic bonds in the present invention helps the bio-based epoxy resin cured spline to be reprocessed at a lower temperature.

[0081] II. Stress-strain tensile test

[0082] Dumbbell-shaped cured splines of the bio-based epoxy resin prepared in Example 3 were taken and subjected to tensile testing on an electronic universal material testing machine at room temperature. The tensile strength TS was calculated according to formula (A), with the unit of MPa:

[0083]

[0084] In formula (A): F m is the recorded maximum force, N; W is the width of the narrow part of the sample, mm; t is the thickness of the sample, mm.

[0085] Figure 7 is the tensile stress-strain curve of the bio-based epoxy resin. As Figure 7 shown, the tensile strength of the bio-based epoxy resin provided by the present invention is 50.1 MPa, and the elongation at break is 11.5%. Due to the presence of a large number of rigid structures such as aromatic rings in the epoxy network, this bio-based epoxy resin has high mechanical strength, and its mechanical properties can be comparable to those of commercial epoxy resins, meeting the usage requirements as a structural material.

[0086] III. Self-healing ability

[0087] A blade was used to make a single-character scratch on the surface of the bio-based epoxy resin cured spline prepared in Example 3, and then a self-healing experiment was carried out at 200 °C. The self-healing situation of the bio-based epoxy resin cured spline at 200 °C was observed using a polarized light microscope. The results are as Figure 8As shown, the width of the scratch before repair was 19.42 μm. After repairing at 200 °C for 20 min, the width of the linear scratch was only 9.71 μm. After 40 min, the linear scratch was basically completely repaired. After 60 min, it was completely repaired. Combining Figure 8 with the crack width in

[0088]

[0089] In formula (B), W 1 is the crack width after heating, in μm; W 0 is the initial crack width, in μm.

[0090] Table 1 Self-healing rate of the cured sample of bio-based epoxy resin after heating

[0091]

[0092] It can be seen from Table 1 that the bio-based epoxy resin PCA-AM-EP / Bas containing dual dynamic bonds (Si-O-Si and C=N) has good self-healing performance.

[0093] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A trifunctional bio-based epoxy resin monomer, characterized in that: The structural formula is shown in Formula I:

2. The method for preparing the trifunctional bio-based epoxy resin monomer according to claim 1, characterized in that: The following steps are involved: Vanillinamine hydrochloride, a strong base and a weak acid salt, an alcohol solvent and protocatechuic aldehyde are mixed for condensation reaction to obtain a bisphenol monomer; the structure of the bisphenol monomer is shown in Formula II; The bisphenol monomer, the catalyst and epichlorohydrin are mixed for epoxidation reaction, and the obtained epoxidation reaction liquid is mixed with sodium hydroxide and a benzene solvent for ring-closing reaction to obtain a trifunctional bio-based epoxy resin monomer with a structure shown in formula I.

3. The preparation method according to claim 2, characterized in that: The strong base weak acid salt comprises one or more of potassium carbonate and sodium carbonate; the molar ratio of vanillin amine hydrochloride to the strong base weak acid salt is 1:1-1.5; the molar ratio of vanillin amine hydrochloride to protocatechuic aldehyde is 1:1-1.5; The condensation reaction temperature is 60-100° C. and the reaction time is 2-7 hours.

4. The preparation method according to claim 2, characterized in that: The molar ratio of the bisphenol monomer to the catalyst is 1:0.001-0.1; the molar ratio of the bisphenol monomer to epichlorohydrin is 1:10-30; and the molar ratio of the bisphenol monomer to sodium hydroxide is 1:0.1-0.

7.

5. The preparation method according to claim 2, characterized in that: The catalyst is one or more of quaternary ammonium salt and pyridine; the sodium hydroxide is used in the form of sodium hydroxide aqueous solution, and the mass concentration of the sodium hydroxide aqueous solution is 20% to 45%.

6. The preparation method according to claim 2, characterized in that: The temperature of the epoxidation reaction is 50-100° C., and the time is 2-7 hours; the temperature of the ring-closing reaction is 50-100° C., and the time is 2-7 hours.

7. A bio-based epoxy resin, characterized in that The preparation raw materials include epoxy resin monomer, curing agent and curing catalyst, wherein the epoxy resin monomer is the trifunctional bio-based epoxy resin monomer described in claim 1 or the trifunctional bio-based epoxy resin monomer prepared by the preparation method described in any one of claims 2 to 6; the curing agent includes one or more of an amino-containing curing agent, a disulfide bond-containing curing agent, and an amino-silicon-silicon bond-containing curing agent; the curing catalyst includes one or more of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, imidazole, 2-ethyl-4-methylimidazole and 4-dimethylaminopyridine.

8. The bio-based epoxy resin according to claim 7, characterized in that The amino-containing curing agent is 4,4'-diaminodiphenylmethane and / or hexamethylenediamine; the disulfide bond-containing curing agent is one or two of 4,4'-diaminodiphenyl disulfide and 3,3'-dithiodipropionic acid; the amino-silicon-oxygen-silicon bond-containing curing agent is one or two of 1,3-bis(3-aminopropyl)tetramethyldisiloxane and bis(4-aminophenoxy)dimethylsilane.

9. The method for preparing the bio-based epoxy resin according to claim 7 or 8, characterized in that: The following steps are involved: A trifunctional bio-based epoxy resin monomer, a curing agent and a curing catalyst are mixed and cured to obtain the epoxy resin cured product; the curing includes sequentially performing a first curing and a second curing, wherein the first curing temperature is 60 to 120° C. and the time is 4 to 12 hours, and the second curing temperature is 120 to 160° C. and the time is 2 to 12 hours.

10. A method for reshaping a bio-based epoxy resin, characterized in that: The following steps are involved: The bio-based epoxy resin is crushed and then hot-pressed and reshaped; the temperature of the hot-pressing and reshaping is 160-200° C., the pressure is 1-20 MPa, and the time is 0.1-2 h; the bio-based epoxy resin is the bio-based epoxy resin according to claim 7 or 8 or the bio-based epoxy resin prepared by the preparation method according to claim 9.

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