Bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing imide structure

Abstract

The invention discloses a bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure. The preparation method comprises the following steps: (1) reacting hydroxyl amide, an aldehyde compound and sulfydryl carboxylic acid to obtain a sulfydryl compound A3; (2) N-phenylmaleimide, 2, 5-furandimethylamine and mercaptan are subjected to a mercaptan-olefin click reaction to synthesize a diamino compound, the diamino compound and maleic anhydride are subjected to an imidization reaction, and bio-based maleimide (B2) is synthesized; (3) synthesizing a sulfydryl-terminated hyperbranched polymer from A3 and B2 through a click reaction, and then generating bio-based hyperbranched epoxy resin from the sulfydryl-terminated hyperbranched polymer and an alkenyl epoxy compound through a click reaction; and (4) blending and curing bisphenol A type epoxy resin with the imide structure to obtain the bio-based hyperbranched epoxy resin / bisphenol A type epoxy resin composite resin containing the imide structure. The prepared material is environment-friendly, can be continuously produced, and can be applied to various frontier fields such as aerospace, turbine technology and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of degradable hyperbranched epoxy resins, and in particular relates to a bio-based hyperbranched epoxy resin / bisphenol A type epoxy resin composite resin containing an imide structure. Background Art

[0002] Epoxy resin (EP) is an important class of thermosetting resins. It has good dimensional stability, heat resistance and excellent mechanical properties due to its highly cross-linked structure after curing. It is widely used in cutting-edge fields such as aerospace, turbine technology, shipping, and electronic information. However, the synthetic raw materials of traditional epoxy resins mainly come from non-renewable resources such as petroleum, which inhibits the sustainable development of the epoxy resin industry. Therefore, it is crucial to develop bio-based epoxy resins based on renewable resources to produce sustainable and environmentally friendly high-performance materials.

[0003] In recent years, more and more research has been devoted to the preparation of new epoxy materials to overcome the trade-off between toughness and strength and to solve the energy and environmental problems caused by plastic waste. Bio-based hyperbranched epoxy resins synthesized from bio-monomers can be used as matrix resins or toughening agents to form partially or fully bio-based epoxy thermosetting plastics. The introduction of hyperbranched structures can balance the strength, toughness, degradability and recyclability of epoxy thermosetting plastics. From the perspective of molecular design, dynamic covalent bonds are introduced to design and prepare epoxy resins containing imide skeletons and triazine skeletons, and traditional bisphenol A epoxy resins are reinforced and toughened. The hexahydrotriazine structure has good degradability under acidic conditions, which realizes the recycling of epoxy resins. The introduction of imide structures into hyperbranched epoxy resins can make them obtain higher strength and expand the application of epoxy resins in high-end fields.

[0004] The synthetic raw materials of traditional epoxy resins are mainly derived from non-renewable resources such as petroleum, which inhibits the sustainable development of the epoxy resin industry. The development of bio-based hyperbranched resins not only conforms to the principles of sustainable development and circular economy, but also takes into account the degradability, recyclability, thermal stability, mechanical properties and other functionalities of the resin. Therefore, the development of composite resin preparation technology containing imide structure bio-based hyperbranched epoxy resin / bisphenol A epoxy resin is a fundamental way to solve the current problems in this field. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof.

[0006] The present invention solves the above technical problems with the following technical solutions:

[0007] Technical solution 1: A bio-based hyperbranched epoxy resin containing an imide structure, the structural formula of which is shown in the following general formula (1):

[0008]

[0009] Among them, the R structure is a pyridine ring, and the -CH 2 O- is in at least one of the ortho, meta and para positions of pyridine.

[0010] Among them, R 1 For the following structure:

[0011] n is a natural number from 1 to 5

[0012] Among them, -CO- in mercaptocarboxylic acid and -OH in hydroxyamide form -COO- through esterification reaction, and the thiol in mercaptocarboxylic acid and the olefin in the olefin compound form -CS- through thiol-olefin click reaction and connect with one or more of R', R", and R"'.

[0013] Wherein, R', R", and R'" are the same or different and are independently represented by the structure of general formula (2), general formula (3) or general formula (4):

[0014]

[0015] General formula (2) General formula (3) General formula (4);

[0016] Wherein, X is one or more of the following structures:

[0017]

[0018] R 2 For the following structure:

[0019]

[0020] R 3 For the following structure:

[0021]

[0022] Among them, R 4 A fatty alkane group having 4 to 18 carbon atoms -C 4 H 9～ -C 18 H 37、 Aromatic hydrocarbon-C 6 H 5 、Aromatic heterocyclic group-C 5 H 4 One or more of N structures.

[0023] The number average molecular weight of the imide structure-containing bio-based hyperbranched epoxy resin is 4000-14000 g / mol, and the epoxy value is 0.08-0.14 mol / 100 g.

[0024] Technical solution 2: A method for preparing a bio-based hyperbranched epoxy resin containing an imide structure, comprising the following steps:

[0025] (1) Adding a hydroxylamide, an aldehyde compound and anhydrous ethanol to a reaction flask, stirring and reacting at 65-95° C. for 4-7 hours to obtain a terminal hydroxyl compound, then adding a mercaptocarboxylic acid, a catalyst and an organic solvent to the reaction flask, stirring and reacting at 20-30° C. for 10-15 hours, and removing the solvent by rotary evaporation to obtain a mercapto compound (A) 3 );

[0026] (2) adding N-phenylmaleimide, 2,5-furandimethylamine, thiol and an organic solvent to a reaction flask, stirring and reacting at 75-105° C. for 10-15 hours to obtain a diamino compound, then adding maleic anhydride to the reaction flask, stirring and reacting at 60-170° C. for 10-14 hours, and removing the solvent by rotary evaporation to obtain bio-based maleimide (B 2 );

[0027] (3) the thiol compound (A) obtained in step (1) 3 ), the bio-based maleimide (B 2 ), a photoinitiator and an organic solvent are added to a reaction bottle, and a thiol-olefin click reaction is carried out under ultraviolet light with a power of 400W to 800W for 20 to 60 minutes to obtain a bio-based terminal thiol hyperbranched polymer, and then an olefin epoxy compound is added to the reaction bottle, and a thiol-olefin click reaction is carried out under ultraviolet light with a power of 400W to 800W for 60 to 100 minutes, and the solvent is removed by rotary evaporation to obtain a bio-based hyperbranched epoxy resin containing an imide structure, with a number average molecular weight of 4000 to 14000 g / mol and an epoxide value of 0.08 to 0.14 mol / 100g.

[0028] Further, the hydroxyamide is one or more of 3-amino-4-hydroxymethylpyridine, 2-amino-3-hydroxymethylpyridine and 2-(hydroxymethyl)-5-aminopyridine; the aldehyde compound is one or more of formaldehyde solution, trioxymethylene and polyformaldehyde; the mercaptocarboxylic acid is n=1-5, preferably one or two of mercaptopropionic acid (MPA) and thioglycolic acid (TGA); the thiol is C 4 H 9 -SH ～ C 18 H 37-SH, phenylthiol, pyridinethiol, one or more, preferably C 4 H 9 -SH ～ C 14 H 29 -SH, phenyl mercaptan and 4-pyridinethiol, more preferably one or more of butanethiol, phenyl mercaptan and 4-pyridinethiol; the alkenyl epoxy compound is one or more of allyl glycidyl ether, 2,3-epoxypropyl acrylate and 1,2-epoxy-5-hexene.

[0029] Furthermore, the organic solvents in steps (1), (2) and (3) are the same or different and are independently one or more of tetrahydrofuran, 1,4-dioxane, acetone, and N,N-dimethylformamide; the catalyst is one or more of 4-dimethylaminopyridine, p-toluenesulfonic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and stannous oxalate; and the photoinitiator is one or more of benzophenone, p-aminopropiophenone, 2,2-dimethoxy-2-phenylacetophenone, and 1-hydroxycyclohexylphenyl ketone.

[0030] Furthermore, in the step (1), the molar ratio of the hydroxyamide to the aldehyde compound is 1:(1.1-1.5), the mass ratio of the hydroxyamide to anhydrous ethanol is 1:5, the molar ratio of the hydroxyamide to mercaptocarboxylic acid is 1:(1.1-1.25), and the mass of the catalyst is 10%-20% of the mass of the hydroxyamide;

[0031] In the step (2), the molar ratio of N-phenylmaleimide, 2,5-furandimethylamine and mercaptan is 1:(1.5-2.22):1, and the molar ratio of N-phenylmaleimide to maleic anhydride is 1:(2.0-2.4);

[0032] In the steps (1), (2) and (3), the mass of the organic solvent added is 1 to 10 times the total mass of the monomers added in the step;

[0033] In the step (3), the thiol compound (A 3 ) and bio-based maleimide (B 2 ) is 1:(0.75-0.9), the thiol compound (A 3 ) and the photoinitiator in a molar ratio of 1: (0.1 to 1.14), the thiol compound (A 3 ) and the alkenyl epoxy compound in a molar ratio of 1:(1.28-1.72);

[0034] Technical solution three: A composite resin of a bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin, the composite resin comprising the above-mentioned bio-based hyperbranched epoxy resin containing an imide structure or the bio-based hyperbranched epoxy resin containing an imide structure prepared by the above-mentioned method and bisphenol A epoxy resin. The preparation steps of the composite resin include: uniformly mixing the bio-based hyperbranched epoxy resin containing an imide structure, bisphenol A epoxy resin and a curing agent, pouring into a mold for thermal curing to obtain the composite resin; the thermal curing temperature is 60-170°C, and the thermal curing time is 3-15 hours; the curing agent is one or more of 4,4'-diaminodiphenyl sulfone, 2,5-furandimethylamine and 4,4'-diaminodiphenylmethane.

[0035] Furthermore, the bisphenol A epoxy resin model is E51.

[0036] Furthermore, the mass ratio of the bio-based hyperbranched epoxy resin containing an imide structure, the bisphenol A epoxy resin and the curing agent is 1:(5.67-15.67):(1.45-4.83), preferably 1:(5.67-7.33):(1.45-4.56).

[0037] Furthermore, the thermal curing conditions are: curing at 60-70°C for 2 hours, curing at 90-100°C for 2-3 hours, curing at 120-130°C for 2-3 hours, and curing at 140-170°C for 1-2 hours.

[0038] Technical solution 4: Application of bio-based hyperbranched epoxy resin containing imide structure in the reinforcement and toughening of linear epoxy resin.

[0039] The present invention has the advantages that:

[0040] (1) The present invention prepares bio-based hyperbranched epoxy resin through a click reaction, and the preparation method has high selectivity, high yield and high efficiency.

[0041] (2) The hydroxyamide and 2,5-furandimethylamine used in the present invention are mainly derived from cellulose / starch and other sugar bio-based raw materials, which are widely available, green and environmentally friendly, and in line with the concept of sustainable development.

[0042] (3) The present invention achieves reinforcement and toughening of bisphenol A epoxy resin by introducing imide ring and hexahydrotriazine structure into the structure of hyperbranched epoxy resin.

[0043] (4) The present invention obtains a bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure. Compared with the bio-based epoxy resin, the introduction of the hyperbranched topological structure effectively improves the mechanical properties of the composite resin, thereby obtaining a high-strength composite resin.

[0044] (5) The present invention blends the imide structure bio-based hyperbranched epoxy resin with the linear structure bisphenol A type epoxy resin to increase the polarity of the system, improve the compatibility, and effectively improve the mechanical properties of the composite material.

[0045] (6) The preparation method of the imide structure bio-based hyperbranched epoxy resin / bisphenol A type epoxy resin composite resin of the present invention is simple, the reaction conditions are mild, the reaction time is short, it is green and environmentally friendly, and it is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is the infrared characterization image of the bio-based hyperbranched epoxy resin (TMEP-12) containing an imide structure prepared in Example 1.

[0047] Located at 2572cm -1 The -SH absorption vibration peak in the epoxy resin at the end disappears; the peak at 913 cm -1 A new infrared characteristic peak appears at , which is the bending vibration peak of the epoxy group. DETAILED DESCRIPTION

[0048] The method of the present invention is further described below in conjunction with specific examples, but these examples should not limit the scope of protection of the present invention in any way.

[0049] The bisphenol A epoxy resin used is model E51.

[0050] The mass concentration of the formaldehyde aqueous solution used is 35wt%; the polymerization degree n of the paraformaldehyde used is 3.

[0051] Example 1 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0052] 6 g (0.048 mol) of 3-amino-4-hydroxymethylpyridine, 4.56 g (0.053 mol) of formaldehyde solution and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 65° C. for 7 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 5.642 g (0.0528 mol) of MPA, 1.12 g of catalyst stannous oxalate and 32.9 g of acetone were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3). 4 g (0.023 mol) of N-phenylmaleimide, 4.37 g (0.035 mol) of 2,5-furandimethylamine, 5.30 g (0.023 mol) of tetradecanethiol and 20 g of N,N-dimethylformamide were added to a reaction bottle and stirred at 100°C for 15 hours to obtain a diamino compound. Then 9.02 g (0.046 mol) of maleic anhydride was added to the reaction bottle and stirred at 160°C for 13 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3 )4.68g (0.007mol), bio-based maleimide (B 2 )4.14g (0.006mol), 0.164g (0.9mmol) of benzophenone and 20g of N,N-dimethylformamide were added into a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 60 minutes to carry out thiol-olefin click reaction to synthesize 8.098g (0.7mmol) of bio-based terminal thiol hyperbranched polymer; 1.03g (0.009mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 400W for 80 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin (TMEP-12) containing an imide structure.

[0053] 3.6 g of bio-based hyperbranched epoxy resin (TMEP-12) containing an imide structure, 10.28 g of 4,4'-diaminodiphenyl sulfone and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 2.

[0054] Example 2 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0055] 3.6 g of the bio-based hyperbranched epoxy resin (TMEP-12) containing an imide structure prepared in Example 1, 8.20 g of 4,4'-diaminodiphenylmethane and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 2.

[0056] Example 3 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0057] 3.6 g of the bio-based hyperbranched epoxy resin (TMEP-12) containing an imide structure prepared in Example 1, 5.22 g of 2,5-furandimethylamine and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 2.

[0058] Example 4 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0059] 6 g (0.048 mol) of 2-hydroxymethyl-5-aminopyridine, 6.22 g (0.072 mol) of formaldehyde solution and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 95° C. for 4 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 6.41 g (0.06 mol) of MPA, 0.650 g of a catalyst 4-dimethylaminopyridine and 32.9 g of acetone were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 6.41 g (0.051 mol) of 2,5-furandimethylamine, 2.07 g (0.023 mol) of butanethiol and 20 g of N,N-dimethylformamide were added to a reaction bottle and stirred at 75°C for 10 hours to obtain a diamino compound. Then, 12.99 g (0.0552 mol) of maleic anhydride was added to the reaction bottle and stirred at 135°C for 10 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3 )4.68g (0.007mol), bio-based maleimide (B 2)3.52g (0.006mol), 1-hydroxycyclohexyl phenyl ketone 0.164g (0.8mmol) and N,N-dimethylformamide 20g were added into a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 60 minutes to carry out thiol-olefin click reaction to synthesize 8.10g (0.7mmol) of bio-based terminal thiol hyperbranched polymer; 1.03g (0.009mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 800W for 60 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin containing an imide structure (BMEP-12).

[0060] 3.6 g of bio-based hyperbranched epoxy resin (BMEP-12) containing an imide structure, 8.22 g of 4,4'-diaminodiphenylmethane and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 2.

[0061] Example 5 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0062] The thiol compound (A) prepared in Example 4 3 ) 4.68 g (0.005 mol), bio-based maleimide (B prepared in Example 4 2 )2.06g (0.00375mol), 0.138g (0.6mmol) of 1-hydroxycyclohexyl phenyl ketone and 20g of N,N-dimethylformamide were added into a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 40 minutes to carry out thiol-olefin click reaction to synthesize 5.84g (0.5mmol) of bio-based terminal thiol hyperbranched polymer; 0.91g (0.008mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 800W for 60 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin (BMEP-6) containing an imide structure.

[0063] 3.6 g of bio-based hyperbranched epoxy resin (BMEP-6) containing an imide structure, 8.23 ​​g of 4,4'-diaminodiphenylmethane and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 2.

[0064] Example 6 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0065] 6 g (0.048 mol) of 2-hydroxymethyl-5-aminopyridine, 6.22 g (0.072 mol) of formaldehyde solution and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 95° C. for 4 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 6.41 g (0.06 mol) of MPA, 0.650 g of a catalyst 4-dimethylaminopyridine and 32.9 g of acetone were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 6.41 g (0.051 mol) of 2,5-furandimethylamine, 3.04 g (0.023 mol) of heptanethiol and 20 g of N,N-dimethylformamide were added to a reaction bottle and stirred at 75°C for 10 hours to obtain a diamino compound. Then, 12.99 g (0.0552 mol) of maleic anhydride was added to the reaction bottle and stirred at 135°C for 10 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3 )4.68g (0.007mol), bio-based maleimide (B 2 )3.08g (0.00525mol), 0.164g (0.8mmol) of 1-hydroxycyclohexyl phenyl ketone and 20g of N,N-dimethylformamide were added into a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 60 minutes to carry out thiol-olefin click reaction to synthesize 5.43g (0.0018mol) of bio-based terminal thiol hyperbranched polymer; 1.37g (0.012mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 400W for 80 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin (HMEP-6) containing an imide structure.

[0066] 2.4 g of bio-based hyperbranched epoxy resin (HMEP-6) containing an imide structure, 11.58 g of 4,4'-diaminodiphenylmethane and 37.6 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 2.

[0067] Example 7 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0068] 6 g (0.048 mol) of 2-amino-3-hydroxymethylpyridine, 5.22 g (0.058 mol) of paraformaldehyde and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 80° C. for 6 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 6.16 g (0.0576 mol) of MPA, 0.885 g of a catalyst 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 32.9 g of acetone were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 5.83 g (0.046 mol) of 2,5-furandimethylamine, 2.53 g (0.023 mol) of benzenethiol and 20 g of N,N-dimethylformamide were added to a reaction bottle and stirred at 90°C for 12 hours to obtain a diamino compound. Then, 10.92 g (0.0506 mol) of maleic anhydride was added to the reaction bottle and stirred at 150°C for 12 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3 )4.68g (0.007mol), bio-based maleimide (B 2 )3.31g (0.00525mol), p-aminopropiophenone 1.19g (0.008mol) and N,N-dimethylformamide 20g were added into a reaction bottle, and irradiated with ultraviolet light at a power of 800W for 30 minutes to carry out thiol-olefin click reaction to synthesize 6.50g (0.0018mol) of bio-based terminal thiol hyperbranched polymer; 1.37g (0.012mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 400W for 75 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin containing an imide structure (BEEP-6).

[0069] 2.4 g of bio-based hyperbranched epoxy resin (BEEP-6) containing an imide structure, 11.58 g of 4,4'-diaminodiphenylmethane and 37.6 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 2.

[0070] Example 8 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0071] 2.4 g of the bio-based hyperbranched epoxy resin (BEEP-6) containing an imide structure prepared in Example 7, 11.58 g of 4,4'-diaminodiphenylmethane and 37.6 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 70°C for 2 hours, curing at 100°C for 3 hours, curing at 120°C for 2.5 hours, and curing at 150°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 3.

[0072] Example 9 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0073] 6 g (0.048 mol) of 2-hydroxymethyl-5-aminopyridine, 5.22 g (0.058 mol) of trioxymethylene and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 85° C. for 6 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 5.31 g (0.0576 mol) of TGA, 0.982 g of p-toluenesulfonic acid as a catalyst and 32.9 g of tetrahydrofuran were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 5.83 g (0.046 mol) of 2,5-furandimethylamine, 2.53 g (0.023 mol) of benzenethiol and 20 g of 1,4-dioxane were added to a reaction bottle and stirred at 100°C for 15 hours to obtain a diamino compound. Then 10.92 g (0.0506 mol) of maleic anhydride was added to the reaction bottle and stirred at 160°C for 13 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3)4.68g (0.007mol), bio-based maleimide (B 2 )4.08g (0.00525mol), 0.179g (0.7mmol) of 2,2-dimethoxy-2-phenylacetophenone and 20g of N,N-dimethylformamide were added to a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 40 minutes to carry out thiol-olefin click reaction to synthesize 6.16g (0.0018mol) of bio-based terminal thiol hyperbranched polymer; 1.37g (0.012mol) of allyl glycidyl ether was added to the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 400W for 80 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin containing an imide structure (BEHEP-6).

[0074] 2.4 g of bio-based hyperbranched epoxy resin (BEHEP-6) containing an imide structure, 11.57 g of 4,4'-diaminodiphenylmethane and 37.6 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 1 hour, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 3.

[0075] Example 10 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0076] 6 g (0.048 mol) of 2-amino-3-hydroxymethylpyridine, 6.22 g (0.072 mol) of formaldehyde solution and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 95° C. for 4 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 6.41 g (0.06 mol) of MPA, 0.650 g of a catalyst 4-dimethylaminopyridine and 32.9 g of acetone were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 6.41 g (0.051 mol) of 2,5-furandimethylamine, 2.56 g (0.023 mol) of 4-pyridinethiol and 20 g of N,N-dimethylformamide were added to a reaction bottle and stirred at 75°C for 10 hours to obtain a diamino compound. Then, 12.99 g (0.0552 mol) of maleic anhydride was added to the reaction bottle and stirred at 135°C for 10 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3)4.68g (0.007mol), bio-based maleimide (B 2 )3.52g (0.006mol), 1-hydroxycyclohexyl phenyl ketone 0.164g (0.8mmol) and N,N-dimethylformamide 20g were added into a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 40 minutes to carry out thiol-olefin click reaction to synthesize 7.33g (0.7mmol) of bio-based terminal thiol hyperbranched polymer; 1.03g (0.009mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 800W for 60 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin containing an imide structure (MMEP-12).

[0077] 3.6 g of bio-based hyperbranched epoxy resin (MMEP-12) containing an imide structure, 8.21 g of 4,4'-diaminodiphenylmethane and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 3.

[0078] Example 11 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0079] 6 g (0.048 mol) of 3-amino-4-hydroxymethylpyridine, 4.56 g (0.053 mol) of formaldehyde solution and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 65° C. for 7 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 4.86 g (0.0528 mol) of TGA, 0.838 g of a catalyst 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide and 32.9 g of tetrahydrofuran were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 4.37 g (0.035 mol) of 2,5-furandimethylamine, 2.56 g (0.023 mol) of 4-pyridinethiol and 1,4-dioxane were added to a reaction bottle and stirred at 75°C for 10 hours to obtain a diamino compound. Then, 9.02 g (0.046 mol) of maleic anhydride was added to the reaction bottle and stirred at 135°C for 10 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3)4.68g (0.007mol), bio-based maleimide (B 2 )4.14g (0.006mol), p-aminopropiophenone 0.134g (0.9mmol) and N,N-dimethylformamide 20g were added into a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 40 minutes to carry out thiol-olefin click reaction to synthesize 7.23g (0.7mmol) of bio-based terminal thiol hyperbranched polymer; 1.03g (0.009mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 800W for 60 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin containing an imide structure (MEMEP-12).

[0080] 3.6 g of bio-based hyperbranched epoxy resin containing an imide structure, 8.22 g of 4,4'-diaminodiphenylmethane and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 1 hour, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 3.

[0081] Example 12 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0082] 6 g (0.048 mol) of 2-hydroxymethyl-5-aminopyridine, 5.22 g (0.058 mol) of trioxymethylene and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 85° C. for 6 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 6.41 g (0.0576 mol) of MPA, 0.650 g of a catalyst 4-dimethylaminopyridine and 32.9 g of acetone were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 6.41 g (0.051 mol) of 2,5-furandimethylamine, 6.59 g (0.023 mol) of octadecanethiol and 20 g of N,N-dimethylformamide were added to a reaction bottle and stirred at 75°C for 10 hours to obtain a diamino compound. Then, 12.99 g (0.0552 mol) of maleic anhydride was added to the reaction bottle and stirred at 135°C for 10 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3 )4.68g (0.007mol), bio-based maleimide (B 2)3.52g (0.006mol), 0.164g (0.8mmol) of 1-hydroxycyclohexyl phenyl ketone and 20g of N,N-dimethylformamide were added into a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 40 minutes to carry out thiol-olefin click reaction to synthesize 8.45g (0.7mmol) of bio-based terminal thiol hyperbranched polymer; 1.03g (0.009mol) of allyl glycidyl ether was added into the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 800W for 60 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin containing an imide structure (OMEP-12).

[0083] 3.6 g of bio-based hyperbranched epoxy resin containing an imide structure, 8.19 g of 4,4'-diaminodiphenylmethane and 26.4 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 1 hour, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 3.

[0084] Example 13 A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure and a preparation method thereof, wherein the steps are as follows:

[0085] 6 g (0.048 mol) of 2-hydroxymethyl-5-aminopyridine, 5.22 g (0.058 mol) of trioxymethylene and 30 g of anhydrous ethanol were added to a reaction flask, and stirred at 85° C. for 6 hours to obtain 6.58 g (0.016 mol) of a terminal hydroxyl compound; then 5.31 g (0.0576 mol) of TGA, 0.982 g of p-toluenesulfonic acid as a catalyst and 32.9 g of tetrahydrofuran were added to the reaction flask, and stirred at 25° C. for 10 hours, and the solvent was removed by rotary evaporation to obtain a thiol compound (A 3 ). 4 g (0.023 mol) of N-phenylmaleimide, 5.83 g (0.046 mol) of 2,5-furandimethylamine, 6.59 g (0.023 mol) of octadecanethiol and 20 g of 1,4-dioxane were added to a reaction bottle and stirred at 100°C for 15 hours to obtain a diamino compound. Then, 10.92 g (0.0506 mol) of maleic anhydride was added to the reaction bottle and stirred at 160°C for 13 hours. The solvent was removed by rotary evaporation to obtain bio-based maleimide (B 2 ) 3 )4.68g (0.007mol), bio-based maleimide (B 2)4.08g (0.00525mol), 0.179g (0.7mmol) of 2,2-dimethoxy-2-phenylacetophenone and 20g of N,N-dimethylformamide were added to a reaction bottle, and irradiated with ultraviolet light at a power of 650W for 40 minutes to carry out thiol-olefin click reaction to synthesize 7.33g (0.0018mol) of bio-based terminal thiol hyperbranched polymer; 1.37g (0.012mol) of allyl glycidyl ether was added to the mixed solution after the click reaction, and irradiated with ultraviolet light at a power of 400W for 80 minutes. The solvent was removed by rotary evaporation to synthesize a bio-based hyperbranched epoxy resin containing an imide structure (OEMEP-6).

[0086] 4.8 g of the imide structure-containing bio-based hyperbranched epoxy resin, 8.60 g of 4,4'-diaminodiphenylmethane and 27.2 g of bisphenol A epoxy resin were blended, and the specimens were cast and cured. The curing conditions were: curing at 60°C for 1 hour, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, the bio-based hyperbranched epoxy resin containing an imide structure / bisphenol A epoxy resin composite resin was taken out, and its mechanical properties were shown in Table 3.

[0087] Comparative Example 1

[0088] 30 g of the imide structure-containing bio-based hyperbranched epoxy resin (TMEP-12) prepared in Example 1 was cured, and the curing agent used was 4,4'-diaminodiphenylmethane, with a mass of 1.66 g. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, it was taken out, and its mechanical properties were shown in Table 2.

[0089] Comparative Example 4

[0090] 30 g of the imide structure-containing bio-based hyperbranched epoxy resin (BMEP-12) prepared in Example 4 was cured, and the curing agent used was 4,4'-diaminodiphenylmethane, with a mass of 1.84 g. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, it was taken out, and its mechanical properties were shown in Table 2.

[0091] Comparative Example 10

[0092] 30 g of the imide structure-containing bio-based hyperbranched epoxy resin (MMEP-12) prepared in Example 10 was cured, and the curing agent used was 4,4'-diaminodiphenylmethane, with a mass of 1.80 g. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, it was taken out, and its mechanical properties were shown in Table 2.

[0093] Comparative Example 12

[0094] 30 g of the imide structure-containing bio-based hyperbranched epoxy resin (OMEP-12) prepared in Example 12 was cured, and the curing agent used was 4,4'-diaminodiphenylmethane, with a mass of 1.59 g, and the curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, it was taken out, and its mechanical properties are shown in Table 2.

[0095] Comparative Example 14

[0096] 30g of bisphenol A epoxy resin was cured, and the curing agent used was 4,4'-diaminodiphenylmethane, with a mass of 9.09g. The curing conditions were: curing at 60°C for 2 hours, curing at 90°C for 2 hours, curing at 130°C for 3 hours, and curing at 160°C for 2 hours. After the curing was completed, it was taken out to obtain pure bisphenol A epoxy resin, and its mechanical properties are shown in Table 2.

[0097] Table 1 Properties of various bio-based hyperbranched epoxy resins containing imide structures

[0098]

[0099]

[0100] Table 2 Mechanical properties of various imide-containing bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resins

[0101]

[0102] Note: The determination method of "tensile strength" in Table 2 is: using a universal material testing machine (Instron 5943) to refer to ASTM standard ASTM D638-14 "Standard Test Method for Tensile Properties of Polymer-based Composite Resins" for testing; the determination method of "flexural strength" is: using a universal material testing machine (Instron 5943) to refer to ASTM standard D790M-92 "Flexural Test Method" for testing; the determination method of "impact strength" is: using a CEAST9050 pendulum impact tester to use ASTM standard D256-97 for testing, and the test temperature is 25°C.

[0103] 1) From the test results in Table 1, we can see that:

[0104] The number average molecular weight of the bio-based hyperbranched epoxy resin containing an imide structure obtained in Examples 1-13 of the present invention gradually increases with the increase in the number of terminal epoxy groups. When the number of terminal groups is 12, the number average molecular weight reaches the maximum value; the epoxy value gradually decreases with the increase in the number of epoxy groups.

[0105] 2) From the test results in Table 2, we can see that:

[0106] The bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure obtained by the present invention has a significant strengthening and toughening effect on linear epoxy resins such as bisphenol A epoxy resin. Among them, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenylmethane, 2,5-furandimethylamine, etc. can be selected as curing agents for blending the bio-based hyperbranched epoxy resin containing an imide structure with the bisphenol A epoxy resin, and 4,4'-diaminodiphenylmethane is the optimal curing agent. (By regulating the ratio of thiol compounds and bio-based maleimide monomers) changing the number of terminal epoxy groups of the bio-based hyperbranched epoxy resin in the bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure will lead to different mechanical properties of the composite resin. When the number of terminal epoxy groups of the bio-based hyperbranched epoxy resin is 12, the composite resin reaches the maximum value in tensile strength, flexural strength and impact strength. Changing the structure of bio-based maleimide monomers will greatly affect the mechanical properties of bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resins containing imide structures. Specifically, when synthesizing bio-based maleimide monomers, end chain groups are introduced by adding thiols, and phenylthiol and pyridinethiol are preferred over fatty chain thiols, and short-chain thiols among fatty chain thiols are preferred over long-chain thiols.

Claims

1. A bio-based hyperbranched epoxy resin containing an imide structure, characterized in that: Its structural formula is the following general formula (1): Wherein, the R structure is a pyridine ring, and the -CH2O- connected to R is in at least one of the ortho, meta and para positions of pyridine; Wherein, R1 is the following structure: n is a natural number from 1 to 5; -CO- and -CH2O- in R1 are connected; Wherein, R', R", and R'" are the same or different and are independently represented by the structure of general formula (2), general formula (3) or general formula (4): Wherein, X is one or more of the following structures: R2 is the following structure: R3 is the following structure: Wherein, R4 is one or more of the structures of aliphatic alkane group, aromatic hydrocarbon group -C6H5, aromatic heterocyclic group -C5H4N with 4 to 18 carbon atoms; The number average molecular weight of the imide structure-containing bio-based hyperbranched epoxy resin is 4000-14000 g / mol, and the epoxy value is 0.08-0.14 mol / 100 g.

2. The method for preparing the imide structure-containing bio-based hyperbranched epoxy resin according to claim 1, characterized in that: The steps include: (1) adding a hydroxylamide, an aldehyde compound and anhydrous ethanol to a reaction flask, stirring and reacting at 65-95° C. for 4-7 hours to obtain a terminal hydroxyl compound, then adding a mercaptocarboxylic acid, a catalyst and an organic solvent to the reaction flask, stirring and reacting at 20-30° C. for 10-15 hours, and removing the solvent by rotary evaporation to obtain a mercapto compound; (2) adding N-phenylmaleimide, 2,5-furandimethylamine, thiol and an organic solvent to a reaction flask, stirring and reacting at 75-105° C. for 10-15 hours to obtain a diamino compound, then adding maleic anhydride to the reaction flask, stirring and reacting at 60-170° C. for 10-14 hours, and removing the solvent by rotary evaporation to obtain a bio-based maleimide; (3) adding the thiol compound obtained in step (1), the bio-based maleimide obtained in step (2), a photoinitiator and an organic solvent to a reaction bottle, and irradiating with ultraviolet light at a power of 400 W to 800 W for 20 to 60 minutes to carry out a thiol-olefin click reaction to obtain a bio-based terminal thiol hyperbranched polymer, then adding an olefin epoxy compound to the reaction bottle, and irradiating with ultraviolet light at a power of 400 W to 800 W for 60 to 100 minutes to carry out a thiol-olefin click reaction, and removing the solvent by rotary evaporation to obtain a bio-based hyperbranched epoxy resin containing an imide structure, wherein the number average molecular weight is 4000 to 14000 g / mol and the epoxy value is 0.08 to 0.14 mol / 100 g.

3. The preparation method according to claim 2, characterized in that: The hydroxyamide is one or more of 3-amino-4-hydroxymethylpyridine, 2-amino-3-hydroxymethylpyridine and 2-(hydroxymethyl)-5-aminopyridine; the thiol is C4H9-SH ～ C 18 H 37 -SH, phenylthiol, pyridinethiol or one or more thereof.

4. The preparation method according to claim 2, characterized in that: The aldehyde compound is one or more of formaldehyde solution, trioxymethylene, and polyformaldehyde; the mercaptocarboxylic acid is n=1-5; the alkenyl epoxy compound is one or more of allyl glycidyl ether, 2,3-epoxypropyl acrylate and 1,2-epoxy-5-hexene.

5. The preparation method according to claim 2, characterized in that: The organic solvents in steps (1) to (3) are the same or different and are independently one or more of tetrahydrofuran, 1,4-dioxane, acetone, and N,N-dimethylformamide; the catalyst is one or more of 4-dimethylaminopyridine, p-toluenesulfonic acid, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, and stannous oxalate; and the photoinitiator is one or more of benzophenone, p-aminopropiophenone, 2,2-dimethoxy-2-phenylacetophenone, and 1-hydroxycyclohexylphenyl ketone.

6. The preparation method according to claim 2, characterized in that: In the step (1), the molar ratio of the hydroxyamide to the aldehyde compound is 1:(1.1-1.5), the mass ratio of the hydroxyamide to anhydrous ethanol is 1:5, the molar ratio of the hydroxyamide to mercaptocarboxylic acid is 1:(1.1-1.25), and the mass of the catalyst is 10%-20% of the mass of the hydroxyamide; In the step (2), the molar ratio of N-phenylmaleimide, 2,5-furandimethylamine and mercaptan is 1:(1.5-2.22):1, and the molar ratio of N-phenylmaleimide to maleic anhydride is 1:(2.0-2.4); In the steps (1) to (3), the mass of the organic solvent added is 1 to 10 times the total mass of the monomers added in the step; In the step (3), the molar ratio of the thiol compound to the bio-based maleimide is 1:(0.75-0.9), the molar ratio of the thiol compound to the photoinitiator is 1:(0.1-1.14), and the molar ratio of the thiol compound to the alkenyl epoxy compound is 1:(1.28-1.72).

7. A bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin containing an imide structure, characterized in that: The composite resin comprises the bio-based hyperbranched epoxy resin containing an imide structure according to claim 1 or the bio-based hyperbranched epoxy resin containing an imide structure prepared by any method according to claims 2-6 and a bisphenol A type epoxy resin.

8. The bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin according to claim 7, characterized in that: The bio-based hyperbranched epoxy resin containing an imide structure, a bisphenol A type epoxy resin and a curing agent are uniformly mixed, poured into a mold for thermal curing to obtain the composite resin; the curing agent is one or more of 4,4'-diaminodiphenyl sulfone, 2,5-furandimethylamine and 4,4'-diaminodiphenylmethane.

9. The bio-based hyperbranched epoxy resin / bisphenol A epoxy resin composite resin according to claim 8, characterized in that: The mass ratio of the imide structure-containing bio-based hyperbranched epoxy resin, the bisphenol A type epoxy resin and the curing agent is 1:(5.67-15.67):(1.45-4.83).

10. Use of the bio-based hyperbranched epoxy resin containing an imide structure according to claim 1 or the bio-based hyperbranched epoxy resin containing an imide structure prepared by the method according to any one of claims 2 to 6 in strengthening and toughening linear epoxy resin.

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