Bio-based double-dynamic crosslinking epoxy resin with green closed-loop recycling and preparation method, recycling method and application thereof

Abstract

The application discloses a green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin and a preparation method, a recycling method and an application thereof, and the preparation method comprises the following steps: under the condition of no catalyst, curing reaction is performed on a bio-based epoxy compound, a dimer acid and an amine-based compound to obtain the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin. The application effectively solves the problems of recycling difficulty and low recycling efficiency of traditional epoxy resin materials, and provides a new idea for structural performance design of a novel epoxy resin material.

Description

TECHNICAL FIELD

[0001] The present application relates to a green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin and its preparation method, recycling method and application, belonging to the technical field of bio-based polymer materials. BACKGROUND

[0002] The rapid development of the world economy has accelerated the consumption of petrochemical resources, and the efficient utilization of biomass resources has opened up a promising green and sustainable development path for the global energy shortage problem. 5-hydroxymethylfurfural (HMF) as a top-level biomass-derived platform compound can be synthesized into some high-value-added chemicals through hydrogenation, hydration, hydrogenolysis and oxidation, etc. Chemical methods are widely used in the production of food, medicine, polymer materials and other fields. Due to the rigid ring and double functionality structure of HMF, it can be easily introduced into the network structure of high polymer materials and play a role in enhancing mechanical properties, so it has developed rapidly in the field of epoxy resin polymer reinforcement.

[0003] Epoxy resin is an important general-purpose thermosetting polymer material, which is widely used in the fields of aviation industry, biomedicine, building and home, automobile industry, etc. due to its excellent mechanical properties, high thermal and chemical stability, low hardening shrinkage, etc. and plays an indispensable role in the development of modern society. However, due to the existence of permanent crosslinking network in the molecule, it is difficult to repair and recycle after long-term service damage (wear and tear, etc.). These losses will reduce the performance of the material and lead to abandonment, which will have a huge impact on the environment and economy. In recent years, with the promotion of green chemistry and sustainable development concept, it is of great significance to realize the self-repair and recycling of materials.

[0004] The introduction of dynamic covalent bonds into the traditional epoxy resin network structure can cause the network topology to rearrange through bond exchange reaction under external stimulus, thereby realizing the self-repair, recycling and reprocessing of the material. However, due to the slow speed of the corresponding bond exchange process, the self-repair rate and recycling efficiency of the material are low, which cannot meet the needs of practical applications. Therefore, it is of great importance to develop high-strength epoxy resin with efficient self-repair and recycling for improving the reliability and durability of polymers and the sustainable development of the resin industry. SUMMARY

[0005] Therefore, the main purpose of the present application is to provide a green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin and its preparation method, recycling method and application. The technical problem to be solved is to introduce dynamic ester bonds and dynamic disulfide bonds into the network structure of epoxy resin through structural design starting from bio-based raw materials, and to realize efficient self-repair and green closed-loop recycling of the material under the synergistic action of double-dynamic covalent bonds.

[0006] The object and solution to the technical problem of the present application are realized by the following technical scheme. The present application provides a preparation method of a green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, comprising the following steps:

[0007] Under the condition of no catalyst, a curing reaction is carried out on a bio-based epoxy compound, a dimer acid and an amine-based compound to obtain the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin.

[0008] The object and solution to the technical problem of the present application can also be further realized by the following technical measures.

[0009] Preferably, the preparation method of the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, wherein the raw material of the bio-based epoxy compound is one of 1,2,4-benzene triol and 1,4-cyclohexanediol.

[0010] Preferably, the preparation method of the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, wherein the dimer acid is selected from one of Pripol 1004, Pripol 1006, Pripol 1025 and Pripol 1022 VEG.

[0011] Preferably, the preparation method of the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, wherein the amine-based compound is selected from one of 4,4'-diaminodiphenyl disulfide and 2,2'-diaminodiphenyl disulfide.

[0012] Preferably, the preparation method of the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, wherein the preparation method of the 1,2,4-benzene triol comprises the following steps:

[0013] First, 30-80ml of 0.01-0.1M HMF aqueous solution and 5-15mM ZnCl2 catalyst are added to a high-pressure reaction kettle, and after the reaction kettle is closed, it is flushed with 100-140bar N2 for 2-4 times;

[0014] Then, continue to fill N2 into the kettle until the pressure reaches 60-100bar, and react at 380-450℃ for 2-20min to obtain 1,2,4-benzene triol.

[0015] Preferably, the preparation method of the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, wherein the preparation method comprises the following steps:

[0016] Step one, the bio-based phenolic alcohol compound, epichlorohydrin and catalyst are mixed uniformly, the reaction temperature is controlled at 100-120℃, and stirring reaction is carried out for 3-6h; then, it is cooled to room temperature, an aqueous solution of alkali metal hydroxide is added, and the reaction is continuously carried out at room temperature for 1-3h; after the reaction is completed, ethyl acetate is added for extraction, and deionized water is washed for 2-3 times, and then anhydrous magnesium sulfate is dried, and then the solvent is removed by distillation under reduced pressure to obtain a bio-based epoxy compound;

[0017] Step two, the bio-based epoxy compound obtained in step one is dissolved with dimer acid and amine-based compound in a solvent, and stirring reaction is carried out at 70-120℃ for 1-2h, and then the solvent is removed under vacuum, and then it is molded and cured at 60-160℃ for 12-24h to obtain the bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop.

[0018] Preferably, the preparation method of the bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop, wherein in step one, the catalyst is selected from one of benzyltriethylammonium chloride, tetrabutylammonium iodide, tetrabutylammonium chloride and tetrabutylammonium bromide.

[0019] Preferably, the preparation method of the bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop, wherein in step one, the alkali metal hydroxide is selected from one of sodium hydroxide, potassium hydroxide and lithium hydroxide.

[0020] Preferably, the preparation method of the bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop, wherein in step one, the mass fraction of the aqueous solution of alkali metal hydroxide is 40-80%.

[0021] Preferably, the preparation method of the bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop, wherein in step one, the molar ratio of the bio-based epoxy compound, epichlorohydrin and catalyst is 1:10:0.02-1:14:0.05.

[0022] Preferably, the preparation method of the bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop, wherein in step two, the solvent is selected from one of ethyl acetate and N,N-dimethylformamide.

[0023] The object and technical problem of the present application are solved by the following technical scheme. The present application provides a bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop, which comprises hard segments and soft segments connected with each other, the hard segment is a rigid benzene ring, and the soft segment is a flexible aliphatic chain; the hard segments are connected through tertiary amine and dynamic disulfide bond, and the hard segment and the soft segment are connected through dynamic ester bond; and the bio-based double dynamic crosslinking epoxy resin which can be recycled in a green closed loop is prepared by the above method.

[0024] The object and technical problem of the present application are solved by the following technical scheme. The present application provides a green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin recovery method, which comprises the following steps: the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin is immersed in pure water at 180-200 DEG C, and is completely degraded after stirring for 12-48 hours; the degradation liquid is subjected to solvent removal at 60-80 DEG C, and then is cured to obtain regenerated bio-based double-dynamic crosslinking epoxy resin.

[0025] The object and technical problem of the present application can also be further solved by the following technical measures.

[0026] Preferably, the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin recovery method, wherein the curing temperature is 160-180 DEG C, and the curing time is 8-12 hours.

[0027] The object and technical problem of the present application are solved by the following technical scheme. The present application provides an electronic sensing material, which comprises the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, wherein the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin comprises hard segments and soft segments connected with each other, the hard segment is a rigid benzene ring, and the soft segment is a flexible aliphatic chain; the hard segments are connected through tertiary amines and dynamic disulfide bonds, and the hard segments and the soft segments are connected through dynamic ester bonds.

[0028] Compared with the prior art, the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin, the preparation method, the recovery method and the application thereof have the following beneficial effects:

[0029] The present application uses renewable bio-based epoxy compounds as raw materials, dimer acid and amine-based compounds as curing agents, and is prepared under the condition of no catalyst to obtain the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin; under the synergistic induction of the topological network rearrangement of the dynamic disulfide bond and the dynamic ester bond, the material shows excellent self-repairing and recycling capabilities, and solves the problems of recycling difficulty and low recycling efficiency of traditional epoxy resins.

[0030] The green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin prepared by the present application has a double-dynamic crosslinking network system of disulfide bond and ester bond, and the self-catalytic effect of the tertiary amine group promotes the bond exchange reaction of the dynamic ester bond; meanwhile, under the synergistic action of the dynamic ester bond and the dynamic disulfide bond, the rearrangement of the network topological structure is accelerated, and the material is endowed with the capabilities of self-repairing, recycling and reprocessing, and solves the problems of recycling difficulty and low recycling efficiency of traditional epoxy resin materials.

[0031] The prepared green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin has a tensile strength of 12.1-32.4 MPa, a tensile strain of 54.1%-234.1%, can effectively shield light in a wavelength range of 200-400 nm, and has application potential as an ultraviolet shielding material. In addition, the material can be closed-loop recycled in an aqueous solution, and the recycling efficiency is more than 60%.

[0032] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application, and to implement the content of the specification, the following will be described in detail as follows. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 Structure formula of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin of the present application;

[0034] Figure 2 Stress-strain curve of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin in Example 1 of the present application;

[0035] Figure 3 Thermogravimetric curve of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin in Example 1 of the present application;

[0036] Figure 4 DSC curve of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin in Example 1 of the present application;

[0037] Figure 5 Transmittance spectrum of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin in Example 1 of the present application in a wavelength range of 200-800 nm. DETAILED DESCRIPTION

[0038] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined purposes, the following will describe in detail the specific embodiments, structures, characteristics and effects of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin, its preparation method, recycling method and application thereof according to the present application, combined with the preferred embodiments. In the following description, different "an embodiment" or "embodiments" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0039] Unless otherwise defined, all terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Methods and materials are described herein for use in the present application; other, suitable methods and materials known in the art can also be used. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, suitable methods and materials are described herein. The materials, methods, and examples provided herein are illustrative only and not intended to be limiting. Other features, objects, and / or advantages of the application will be apparent from the description and drawings, and from the claims.

[0040] Some embodiments of the present application provide a method for preparing a green-closed-loop recyclable bio-based dual-dynamic crosslinking epoxy resin, comprising the following steps:

[0041] In the absence of a catalyst, a bio-based epoxy compound, a dimer acid, and an amine-based compound are subjected to a curing reaction to obtain the green-closed-loop recyclable bio-based dual-dynamic crosslinking epoxy resin.

[0042] In order to balance the performance of the product, in some optional embodiments, the raw material used to prepare the bio-based epoxy compound is one of 1,2,4-benzene triol and 1,4-cyclohexanediol. The bio-based phenolic alcohol compound obtained by reacting these bio-based phenolic alcohol compounds with epichlorohydrin can end-cap the epoxy group, and in addition, they all have a rigid six-membered ring structure, which can improve the mechanical strength of the material.

[0043] In order to balance the sustainability of the product, in some optional embodiments, the dimer acid is selected from one of Pripol 1004, Pripol 1006, Pripol 1025, and Pripol 1022 VEG. These are all bio-based dimer acids, which can be reacted with the aforementioned epoxy compounds and amine-based compounds to prepare the target epoxy resin, and these dimer acids all have long-chain structures, which can improve the flexibility of the material.

[0044] In some optional embodiments, the amine-based compound is selected from one of 4,4'-diaminodiphenyl disulfide and 2,2'-diaminodiphenyl disulfide. Both of these compounds have disulfide bonds and amine groups, which can be reacted with the aforementioned epoxy compounds and dimer acids to obtain the target epoxy resin, in addition, the disulfide bonds in these compounds can improve the recycling efficiency of the material.

[0045] In some alternative embodiments, wherein the preparation method of 1,2,4-benzene triol is as follows, first, 30-80ml of 0.01-0.1M aqueous solution of MIF (5-hydroxymethylfurfural) and 5-15mM ZnCl2 catalyst are added to the high-pressure reactor, less than 30ml or more than 80ml will reduce the yield of the target product; less than 0.01M or more than 0.1M will reduce the yield of the target product, within the range of 0.01-0.1M can achieve the highest yield; less than 5mM or more than 15mM will reduce the yield of the target product; after the reactor is sealed, it is flushed with 100-140bar of N2 (purity 99.50%-99.9%) for 2-4 times, less than 100bar cannot completely exclude the air in the reactor, 100-140bar can completely exclude the air in the reactor, and more than 140bar will cause resource waste; less than 99.50% will reduce the yield of the target product, within the range of 99.50%-99.9% the target product can achieve the highest yield, and more than 99.99% will cause unnecessary resource waste; less than 2 times cannot completely exclude the air in the reactor, 2-4 times can completely exclude the air in the reactor, and more than 4 times will cause resource waste. Then, continue to fill N2 into the reactor until the pressure reaches 60-100bar, react at 380-450℃ for 2-20min, within the pressure range of 60-100bar can form a subcritical atmosphere, less than 60bar or more than 100bar cannot form; less than 380℃ or more than 450℃ will reduce the yield of the target product, within the range of 380-450℃ can achieve the highest yield; less than 2min the substrate is not completely reacted, and more than 20min the yield of the target product will be reduced; to obtain 1,2,4-benzene triol.

[0046] In some alternative embodiments, the preparation method comprises the following steps:

[0047] Step (1), after the bio-based phenolic alcohol compound, epichlorohydrin and catalyst are added into a flask and mixed uniformly, the reaction temperature is controlled at 100-120℃, which is lower than 100℃, the bio-based phenolic alcohol compound cannot be completely reacted, selecting 100-120℃ can make the raw materials completely react, and higher than 120℃ will cause resource waste; stirring for 3-6h, which is lower than 3h, the bio-based phenolic alcohol compound cannot be completely reacted, selecting 3-6h can make the raw materials completely react, and higher than 6h will cause resource waste; then cooling to room temperature, adding an aqueous alkali metal hydroxide solution, and continuing to react at room temperature for 1-3h, which is lower than 1h, the intermediate product cannot be completely ring-closed, and the yield of the target product is low, selecting 1-3h can make the intermediate product be completely ring-closed, and the reaction has ended, and higher than 3h will cause resource waste; after the reaction is completed, ethyl acetate is added for extraction, and deionized water is washed for 2-3 times, which is lower than 2 times, the alkali metal hydroxide and catalyst in the product cannot be completely removed, selecting 2-3 times can completely remove the alkali metal hydroxide and catalyst in the product, and higher than 3 times will cause unnecessary resource waste; anhydrous magnesium sulfate is dried, and then the solvent is removed by reduced pressure distillation to obtain a bio-based epoxy compound;

[0048] Step (2), the bio-based epoxy compound prepared in step (1) is dissolved with dimer acid and amine-based compound in a solvent, and then stirred at 70-120℃ for 1-2h, which is lower than 70℃, the raw materials cannot be completely reacted, selecting 70-120℃ can make the raw materials completely react, and higher than 120℃ will cause resource waste; lower than 1h, the raw materials cannot be completely consumed, 2h can make the raw materials completely react, and prolonging the time will cause unnecessary resource waste, then poured into a mold, the solvent is removed by vacuum, and then solidified at 60-160℃ for 12-24h, which is lower than 60℃, the material cannot be completely solidified, selecting 60-160℃ can make the material completely solidify, and higher than 160℃ will cause resource waste; less than 12h, the material cannot be completely solidified, selecting 12-24h can make the material completely solidify, and greater than 24h will cause resource waste, to obtain a bio-based double dynamic crosslinking epoxy resin which can be greenly closed-loop recycled.

[0049] In some optional embodiments, the catalyst in step (1) is selected from one of benzyltriethylammonium chloride, tetrabutylammonium iodide, tetrabutylammonium chloride and tetrabutylammonium bromide. These catalysts can catalyze the reaction of epichlorohydrin and bio-based phenolic alcohol compound.

[0050] In some optional embodiments, the alkali metal hydroxide in step (1) is selected from one of sodium hydroxide, potassium hydroxide and lithium hydroxide. These alkali metal hydroxides can catalyze the ring-closing reaction of the epoxy group to finally form the target compound.

[0051] In some alternative embodiments, the mass fraction of the aqueous alkali metal hydroxide solution in step (1) is 40-80%. A mass fraction lower than 40% will result in incomplete ring closure of the epoxy groups, reducing the yield of the target product, and a mass fraction higher than 80% will result in resource waste.

[0052] In some alternative embodiments, the molar ratio of the bio-based epoxy compound, epichlorohydrin and catalyst in step (1) is 1:10:0.02-1:14:0.05. If the molar ratio of the bio-based epoxy compound, epichlorohydrin and catalyst is lower than the lower limit, the bio-based phenolic alcohol compound will not react completely; if the molar ratio of the bio-based epoxy compound, epichlorohydrin and catalyst is higher than the upper limit, the concentration of the bio-based phenolic alcohol compound and the catalyst in the reaction system will be low, resulting in a reduced reaction rate.

[0053] In some alternative embodiments, the solvent in step (2) is selected from one of ethyl acetate and N,N-dimethylformamide. These solvents can completely dissolve the raw materials.

[0054] In some alternative embodiments, the mold material in step (2) is polytetrafluoroethylene or stainless steel. These molds can maintain good shape at high temperatures, and the material obtained by pouring the raw materials into these molds and solidifying at high temperatures has a regular morphology.

[0055] Some embodiments of the present application also provide a green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin, which comprises interconnected hard segments and soft segments, the hard segments are rigid benzene rings, the soft segments are flexible aliphatic chains, and the combination of rigid benzene rings and flexible aliphatic chain segments endows the material with good mechanical properties, and the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin is prepared by the above method. Specifically, the hard segments are connected by tertiary amines and dynamic disulfide bonds, and the hard segments and soft segments are connected by dynamic ester bonds. The structure of the prepared green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin is shown in Figure 1 The network structure of the material contains dynamic ester bonds and dynamic disulfide bonds, and under the synergistic action of the double dynamic covalent bonds, it shows good self-repairing and recycling properties, and can be used for electronic sensing materials.

[0056] Some embodiments of the present application also provide a regeneration method of a green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin, comprising the following steps:

[0057] The green-closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin is immersed in pure water at 180-200 DEG C, and the material cannot be completely degraded into small molecules below 180 DEG C, 180-200 DEG C can make the material completely degrade, and higher than 200 DEG C will cause resource waste, and the material is completely degraded after stirring for 12-48 h, the material is not completely degraded below 12 h, 12 h-48 h is selected, the resin material can be completely degraded into small molecules, and higher than 48 h will cause unnecessary waste; the degradation liquid is removed at 60 DEG C-80 DEG C, the solvent cannot be completely removed below 60 DEG C, the solvent can be completely removed in the temperature range of 60 DEG C-80 DEG C, and higher than 80 DEG C will cause resource waste; and the regenerated epoxy resin is obtained by curing the degradation product at 160 DEG C-180 DEG C for 8-12 h; the degradation product is not completely cured below 160 DEG C, the degradation product can be completely cured in 160 DEG C-180 DEG C, and higher than 180 DEG C will cause resource waste.

[0058] Some embodiments of the application also provide an electronic sensing material, which comprises the above-mentioned closed-loop recyclable high-strength bio-based epoxy resin.

[0059] The application will be further described below in conjunction with specific examples, but it should not be understood as limiting the scope of protection of the application, and some non-essential improvements and adjustments made by the person skilled in the art to the application according to the above content of the application still belong to the protection scope of the application.

[0060] Example 1

[0061] First, 50 ml of 0.05 M aqueous HMF and 12 mM ZnCl2 catalyst were added to a high-pressure reactor, and the reactor was sealed. The reactor was then purged three times with 120 bar of N2 (purity 99.9%). Then, the reactor was filled with N2 until the pressure reached 80 bar, and the reaction was carried out at 400°C for 5 min to obtain 1,2,4-benzene triol. The obtained 1,2,4-benzene triol (20 g) and epichlorohydrin (205.4 g), tetrabutylammonium bromide (1 g) were added to a three-necked flask, and the reaction was carried out at 120°C for 3 h with stirring (600 rpm). The stirring was then stopped. After the solution cooled to room temperature, 95.2 g of 40 wt% aqueous NaOH was added, and the reaction was continued at room temperature for 3 h. After the reaction was completed, 200 ml of ethyl acetate was added for extraction, and the solution was washed with 100 ml of deionized water three times. Then, 5 g of anhydrous magnesium sulfate was added to remove water, and finally, the ethyl acetate and unreacted epichlorohydrin were removed by distillation at a temperature of 90°C and a vacuum degree of -0.1 MPa to obtain benzene triol triglycidyl ether. 1 g of the benzene triol triglycidyl ether obtained in the above step was dissolved in 1 ml of N,N-dimethylformamide, and then 1.98 g of Pripol 1006 and 0.3725 g of 4,4'-diamino diphenyl disulfide were added. The reaction was carried out at 120°C for 1 h with stirring. Subsequently, the reaction solution was poured into a polytetrafluoroethylene mold, and the mold was placed in a vacuum drying oven to remove bubbles. Then, the mold was cured at 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, and 180°C, respectively, for 2 h to obtain a brown transparent film material, i.e., the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin.

[0062] As shown in Figure 2 , the tensile stress of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin prepared in this embodiment was 12.1 MPa, and the tensile strain was 234.1%. As can be seen from the Figure 3 thermogravimetric curve, the temperature at which the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin lost 5% of its weight was 304.5°C, showing good thermal stability. The glass transition temperature of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin was 24.0°C, and there was only one glass transition temperature, proving that the material obtained after curing was uniform (see Figure 4 ). Figure 5 is the transmittance curve of the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin under a wavelength light source of 200-800 nm. It can be seen that the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin can completely absorb light in the wavelength range of 200-400 nm, proving that the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin can be applied in the field of ultraviolet shielding.

[0063] The green-closed-loop recyclable bio-based double dynamic crosslinking epoxy resin prepared in this embodiment can be used in the preparation of electronic sensing materials.

[0064] Example 2

[0065] First, 50 ml of 0.05 M HMF aqueous solution and 12 mM ZnCl2 catalyst were added to a high-pressure reaction kettle, and the kettle was closed. Then, the kettle was flushed with 120 bar of N2 (purity 99.9%) for 3 times. Then, the kettle was continuously filled with N2 until the pressure reached 80 bar, and the reaction was carried out at 400℃ for 5 min to obtain 1,2,4-benzene triol. The obtained 1,2,4-benzene triol (5 g) and epichlorohydrin (51.4 g), tetrabutylammonium bromide (0.3 g) were added to a three-necked flask, and after stirring (600 rpm) at 120℃ for 3 h, the stirring was stopped. After the solution was cooled to room temperature, 23.8 g of 40 wt% sodium hydroxide aqueous solution was added, and the reaction was continued at room temperature for 3 h. After the reaction was completed, 50 ml of ethyl acetate was added for extraction, and 25 ml of deionized water was used for washing three times, then 1 g of anhydrous magnesium sulfate was added for drying to remove water, and finally, ethyl acetate and unreacted epichlorohydrin were removed by distillation at a temperature of 90℃ and a vacuum degree of -0.1 MPa to obtain benzene triol triglycidyl ether. 1 g of the benzene triol triglycidyl ether prepared in the above step was dissolved in 1 ml of N,N-dimethylformamide, and then 1.69 g of Pripol 1006 and 0.5 g of 4,4'-diamino diphenyl disulfide were added. The reaction was stirred at 120℃ for 1 h. Subsequently, the reaction solution was poured into a polytetrafluoroethylene mold, and the bubbles were removed by vacuumizing in a vacuum drying oven, and then the material was cured at 60℃, 80℃, 100℃, 120℃, 140℃, 160℃ and 180℃ for 2 h respectively to obtain a brown transparent film material, which is the green-closed-loop recyclable bio-based double dynamic crosslinking epoxy resin.

[0066] The green-closed-loop recyclable bio-based double dynamic crosslinking epoxy resin prepared in this embodiment has a tensile stress of 13.9 MPa, a strain of 177.8%, a temperature of 303.1℃ at 5% of thermogravimetric, a glass transition temperature of 36.3℃, and can effectively shield light in the 200-400 nm wave band.

[0067] The green-closed-loop recyclable bio-based double dynamic crosslinking epoxy resin prepared in this embodiment can be used in the preparation of electronic sensing materials.

[0068] Example 3

[0069] First, 50 ml of 0.05 M aqueous HMF and 12 mM ZnCl2 catalyst were added to a high-pressure reactor, and the reactor was closed. The reactor was then flushed three times with 120 bar of N2(purity 99.9%). Then, the reactor was filled with N2until the pressure reached 80 bar, and the reaction was carried out at 400°C for 5 min to obtain 1,2,4-benzene triol. The obtained 1,2,4-benzene triol (10 g) and epichlorohydrin (102.8 g), tetrabutylammonium bromide (0.6 g) were added to a three-necked flask, and the reaction was carried out at 120°C for 3 h with stirring (600 rpm). After the reaction, the solution was cooled to room temperature, and then 47.6 g of 40 wt% aqueous NaOH was added. The reaction was continued at room temperature for 3 h. After the reaction, 100 ml of ethyl acetate was added for extraction, and the organic phase was washed with 50 ml of deionized water three times. Then, 2.5 g of anhydrous magnesium sulfate was added to remove water, and finally, ethyl acetate and unreacted epichlorohydrin were removed by distillation at a temperature of 90°C and a vacuum degree of -0.1 MPa. The obtained benzene triol triglycidyl ether was dissolved in 1 ml of N,N-dimethylformamide, and then 1.41 g of Pripol 1006 and 0.62 g of 4,4'-diamino diphenyl disulfide were added. The reaction was carried out at 120°C for 1 h with stirring. Subsequently, the reaction solution was poured into a polytetrafluoroethylene mold, and the mold was placed in a vacuum drying oven to remove bubbles. Then, the mold was heated at 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, and 180°C, respectively, for 2 h to obtain a brown transparent film material, i.e., the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin.

[0070] The green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin prepared in this example has a tensile stress of 21.1 MPa, a strain of 125.6%, a temperature at 5% weight loss of 300.4°C, a glass transition temperature of 41.4°C, and can effectively shield light in the 200-400 nm wavelength band.

[0071] The green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin prepared in this example can be used in the preparation of electronic sensing materials.

[0072] Example 4

[0073] First, 50 ml of 0.05 M aqueous HMF and 12 mM ZnCl2 catalyst were added to a high-pressure reactor, and the reactor was closed. The reactor was then purged three times with 120 bar of N2 (purity 99.9%). Then, the reactor was filled with N2 until the pressure reached 80 bar, and the reaction was carried out at 400°C for 5 min to obtain 1,2,4-benzene triol. The obtained 1,2,4-benzene triol (15 g), epichlorohydrin (154.2 g), and tetrabutylammonium bromide (0.9 g) were added to a three-necked flask, and the mixture was stirred (600 rpm) at 120°C for 3 h. After the stirring was stopped, the solution was allowed to cool to room temperature, and then 71.4 g of 40 wt% aqueous NaOH was added. The reaction was continued at room temperature for 3 h. After the reaction was completed, 150 ml of ethyl acetate was added for extraction, and the mixture was washed with 750 ml of deionized water three times. Then, 4 g of anhydrous magnesium sulfate was added to remove water, and finally, the ethyl acetate and unreacted epichlorohydrin were removed by distillation at a temperature of 90°C and a vacuum degree of -0.1 MPa to obtain benzene triol triglycidyl ether. 1 g of the benzene triol triglycidyl ether obtained in the above step was dissolved in 1 ml of N,N-dimethylformamide, and then 1.13 g of Pripol 1006 and 0.75 g of 4,4'-diamino diphenyl disulfide were added. The mixture was stirred at 120°C for 1 h. Subsequently, the reaction solution was poured into a polytetrafluoroethylene mold, and the mold was placed in a vacuum drying oven to remove bubbles. Then, the mold was cured at 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, and 180°C, respectively, for 2 h to obtain a brown transparent film material, i.e., the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin.

[0074] The green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin obtained in this example had a tensile stress of 25.2 MPa, a strain of 88.8%, a temperature at 5% weight loss of 289.7°C, a glass transition temperature of 46.8°C, and could effectively shield light in the 200-400 nm wavelength band.

[0075] The green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin obtained in this example can be used in the preparation of electronic sensing materials.

[0076] Example 5

[0077] First, 50 ml of 0.05 M aqueous HMF and 12 mM ZnCl2 catalyst were added to a high-pressure reactor, and the reactor was closed. The reactor was then flushed three times with 120 bar of N2 (purity 99.9%). Then, the reactor was filled with N2 until the pressure reached 80 bar, and the reaction was carried out at 400°C for 5 min to obtain 1,2,4-benzene triol. The obtained 1,2,4-benzene triol (20 g) and epichlorohydrin (205.4 g), tetrabutylammonium bromide (1 g) were added to a three-necked flask, and the reaction was carried out at 120°C for 3 h with stirring (600 rpm). After the reaction, the solution was cooled to room temperature, and then 95.2 g of 40 wt% aqueous NaOH was added, and the reaction was continued at room temperature for 3 h. After the reaction, 200 ml of ethyl acetate was added for extraction, and the organic phase was washed with 100 ml of deionized water three times, and then 5 g of anhydrous magnesium sulfate was added to remove water. Finally, the ethyl acetate and unreacted epichlorohydrin were removed by distillation at a temperature of 90°C and a vacuum degree of -0.1 MPa to obtain benzene triol triglycidyl ether. 1 g of the benzene triol triglycidyl ether obtained in the above step was dissolved in 1 ml of N,N-dimethylformamide, and then 0.85 g of Pripol 1006 and 0.87 g of 4,4'-diamino diphenyl disulfide were added. The reaction was carried out at 120°C for 1 h with stirring. Subsequently, the reaction solution was poured into a polytetrafluoroethylene mold, and the mold was placed in a vacuum drying oven to remove bubbles. Then, the mold was heated at 60°C, 80°C, 100°C, 120°C, 140°C, 160°C, and 180°C, respectively, for 2 h to obtain a brown transparent film material, i.e., the green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin.

[0078] The green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin prepared in this example has a tensile stress of 32.4 MPa, a strain of 54.1%, a temperature at 5% weight loss of 281.9°C, a glass transition temperature of 52.6°C, and can effectively shield light in the 200-400 nm wavelength band.

[0079] The green closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin prepared in this example can be used in the preparation of electronic sensing materials.

[0080] The green-closed-loop recyclable bio-based double-dynamic crosslinking epoxy resin obtained in Examples 1-5 (1 g) was respectively placed in a hydrothermal reactor kettle with pure water (30 ml) at 200 ℃, and after stirring for 12 h, the material crosslinking network was completely degraded. The solvent in the degradation solution was removed by a rotary evaporator at 70 ℃, and then a regenerated epoxy resin was obtained by curing at 160 ℃ for 12 h. The performance of the epoxy resin in each example can be restored to more than 60%. Among them, the stress recovery of the epoxy resin recovered in Example 1 is 76%, the stress recovery of the epoxy resin recovered in Example 2 is 72%, the stress recovery of the epoxy resin recovered in Example 3 is 70%, the stress recovery of the epoxy resin recovered in Example 4 is 67%, and the stress recovery of the epoxy resin recovered in Example 5 is 63%.

[0081] Comparative Example 1

[0082] First, 50 ml of 0.05 M HMF aqueous solution and 12 mM ZnCl2 catalyst were added to a high-pressure reactor kettle, and the reactor kettle was closed. Then, the reactor kettle was flushed with 120 bar of N2 (purity 99.9%) for 3 times. Then, the reactor kettle was continuously filled with N2 until the pressure reached 80 bar, and then reacted at 400 ℃ for 5 min to obtain 1,2,4-benzene triol. The obtained 1,2,4-benzene triol (15 g), epichlorohydrin (154.2 g), and tetrabutylammonium bromide (0.9 g) were added to a three-necked flask, and after stirring (600 rpm) at 120 ℃ for 3 h, the stirring was stopped. After the solution cooled to room temperature, 71.4 g of 40 wt% sodium hydroxide aqueous solution was added, and the reaction was continued at room temperature for 3 h. After the reaction was completed, 150 ml of ethyl acetate was added for extraction, and then the organic phase was washed with 750 ml of deionized water for three times. Then, 4 g of anhydrous magnesium sulfate was added for drying to remove water. Finally, the ethyl acetate and unreacted epichlorohydrin were removed by distillation at a temperature of 90 ℃ and a vacuum degree of -0.1 MPa to obtain benzene triol triglycidyl ether. 1 g of the benzene triol triglycidyl ether prepared in the above step was dissolved in 1 ml of N,N-dimethylformamide, and then 1.98 g of Pripol 1006 and 0.30 g of 4,4'-diaminodiphenyl methane were added. The reaction was stirred at 120 ℃ for 1 h. Subsequently, the reaction solution was poured into a polytetrafluoroethylene mold, and the mold was vacuumed in a vacuum drying oven to remove bubbles. Then, the mold was cured at 60 ℃, 80 ℃, 100 ℃, 120 ℃, 140 ℃, 160 ℃, and 180 ℃ for 2 h, respectively, to obtain a brown transparent thin film material, i.e., a green-closed-loop recyclable bio-based epoxy resin.

[0083] The tensile stress of the green closed-loop recyclable bio-based epoxy resin prepared in the present comparative example is 18.9 MPa, the strain is 316%, the temperature of the material at 5% of the thermal weight is 308.6 DEG C, the glass transition temperature is 31.3 DEG C, and the material can effectively shield light in the wavelength range of 200-400 nm. The green closed-loop recyclable bio-based epoxy resin obtained in Comparative Example 1 (1 g) was placed in a hydrothermal reactor containing pure water (30 ml) at 200 DEG C and stirred for 12 h. Since only a single type of dynamic covalent bond exists in the network structure of the material, the movement rate of the molecular chain segment is reduced, and therefore the material cannot be completely degraded within 12 h of stirring.

[0084] In the description of the present application, a large number of specific details are described. However, it can be understood that the embodiments of the present application can be practiced without these specific details. In some embodiments, well-known methods, structures and techniques are not shown in detail in order not to obscure the understanding of the present description.

[0085] It should be further noted that each specific technical feature described in the above specific embodiments can be combined in any appropriate manner without contradiction, and in order to avoid unnecessary repetition, the present application will not further describe various possible combinations.

[0086] In addition, any combination of various different embodiments of the present application can also be made, as long as it does not deviate from the idea of the present application, and it should also be considered as disclosed by the present application.

[0087] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Any simple modification, equivalent change and modification of the above embodiment according to the technical essence of the present application still belongs to the scope of the technical solution of the present application.

Claims

1. A method for preparing a bio-based dual-dynamic crosslinking epoxy resin that is green closed-loop recyclable, characterized in that, The method comprises the following steps: The bio-based epoxy compound, the dimer acid and the amine-based compound are subjected to a curing reaction under a catalyst-free condition to obtain the bio-based double-dynamic crosslinking epoxy resin which can be closed-loop recycled in a green way. The bio-based epoxy compound adopts one of 1,2,4-benzene triol and 1,4-cyclohexanediol; the dimer acid is selected from one of Pripol 1004, Pripol 1006, Pripol 1025 and Pripol 1022 VEG; and the amine-based compound is selected from one of 4,4'-diamino diphenyl disulfide and 2,2'-diamino diphenyl disulfide.

2. The process for the preparation of a green-closed loop recyclable bio-based dual-dynamic crosslinking epoxy resin according to claim 1, characterized in that, The preparation method of the 1,2,4-benzene triol comprises the following steps: First, 30-80ml of 0.01-0.1 M HMF aqueous solution and 5-15mM ZnCl2 catalyst are added into a high-pressure reaction kettle, the kettle is closed, and then 100-140bar of N2 is used to flush 2-4 times; Then, N2 is continuously filled into the kettle until the pressure reaches 60-100bar, and the reaction is carried out at 380-450℃ for 2-20min to obtain 1,2,4-benzene triol.

3. The process for the preparation of green-closed loop recyclable bio-based dual-dynamic crosslinking epoxy resin as claimed in claim 1 wherein, The preparation method comprises the following steps: Step one, the bio-based phenolic alcohol compound, epichlorohydrin and catalyst are uniformly mixed, the reaction temperature is controlled at 100-120℃, and the stirring reaction is carried out for 3-6h; then the reaction system is cooled to room temperature, an aqueous alkali metal hydroxide solution is added, and the reaction is continuously carried out at room temperature for 1-3h; after the reaction is completed, ethyl acetate is added for extraction, the obtained solution is washed with deionized water for 2-3 times, dried over anhydrous magnesium sulfate, and then the solvent is removed by vacuum distillation to obtain the bio-based epoxy compound; Step two, the bio-based epoxy compound obtained in step one is dissolved with the dimer acid and the amine-based compound in a solvent, and then the stirring reaction is carried out at 70-120℃ for 1-2h; after the solvent is removed under vacuum, the obtained product is molded and cured at 60-160℃ for 12-24h to obtain the bio-based double-dynamic crosslinking epoxy resin which can be closed-loop recycled in a green way.

4. The process for the preparation of a green-closed-loop recyclable bio-based dual-dynamic crosslinking epoxy resin according to claim 3, characterized in that, In step one, the catalyst is selected from one of benzyltriethylammonium chloride, tetrabutylammonium iodide, tetrabutylammonium chloride and tetrabutylammonium bromide; the alkali metal hydroxide is selected from one of sodium hydroxide, potassium hydroxide and lithium hydroxide; the mass fraction of the aqueous alkali metal hydroxide solution is 40-80%; and the molar ratio of the bio-based phenolic alcohol compound, epichlorohydrin and catalyst is 1:10:0.02~1:14:0.

05.

5. The process for the preparation of green-closed loop recyclable bio-based dual-dynamic crosslinking epoxy resin as claimed in claim 3 wherein, In step two, the solvent is selected from one of ethyl acetate and N,N-dimethylformamide.

6. A bio-based dual-dynamic crosslinking epoxy resin that is green closed loop recyclable, characterized in that, The bio-based double-dynamic crosslinking epoxy resin which can be closed-loop recycled in a green way comprises hard segments and soft segments which are connected to each other, the hard segment is a rigid benzene ring, and the soft segment is a flexible aliphatic chain; the hard segments are connected through tertiary amine and dynamic disulfide bond, and the hard segments and the soft segments are connected through dynamic ester bond; The bio-based double-dynamic crosslinking epoxy resin which can be closed-loop recycled in a green way is prepared by the method in any one of claims 1-5.

7. A method for recycling a bio-based dual-dynamic crosslinking epoxy resin that is green closed-loop recyclable, characterized in that, The method comprises the following steps: the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin of claim 6 is immersed in pure water at 180-200 DEG C, and is completely degraded after stirring reaction for 12-48 h; the degradation liquid is subjected to solvent removal at 60-80 DEG C, and then is cured to obtain a regenerated bio-based double dynamic crosslinking epoxy resin.

8. The recycling method of green-closed-loop recyclable bio-based dual-dynamic crosslinking epoxy resin according to claim 7, characterized in that, The curing temperature is 160-180 DEG C, and the curing time is 8-12 h.

9. An electronic sensing material, characterized in that, The electronic sensing material comprises the green closed-loop recyclable bio-based double dynamic crosslinking epoxy resin of claim 6.

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